TY - JOUR
TI - LOW RANK UPDATE OF SINGULAR VALUES
AU - Chu, Delin
AU - Chu, Moody
DA - 2006///
PY - 2006///
UR - http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.153.6877
ER -
TY - JOUR
TI - On the low-rank approximation of data on the unit sphere
AU - Chu, M.
AU - Del Buono, N.
AU - Lopez, L.
AU - Politi, T.
T2 - SIAM Journal on Matrix Analysis and Applications
AB - In various applications, data in multidimensional space are normalized to unit length. This paper considers the problem of best fitting given points on the m-dimensional unit sphere Sm-1 by k-dimensional great circles with k much less than m. The task is cast as an algebraically constrained low-rank matrix approximation problem. Using the fidelity of the low-rank approximation to the original data as the cost function, this paper offers an analytic expression of the projected gradient which, on one hand, furnishes the first order optimality condition and, on the other hand, can be used as a numerical means for solving this problem.
DA - 2006///
PY - 2006///
DO - 10.1137/S0895479803433295
VL - 27
IS - 1
SP - 46-60
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33144482741&partnerID=MN8TOARS
ER -
TY - CONF
TI - Challenges in Symbolic Computation Software, number 06271
T2 - Internationales Begegnungs- und Forschungszentrum für Informatik (IBFI)
A2 - Decker, Wolfram
A2 - Dewar, Mike
A2 - Kaltofen, Erich
A2 - Watt, Stephen
C2 - 2006///
C3 - Dagstuhl Seminar Proceedings
CY - Schloss Dagstuhl
DA - 2006///
PB - Schloss Dagstuhl
ER -
TY - CHAP
TI - Generalized vertex algebras
AU - Bakalov, B.
AU - Kac, V.G.
T2 - Lie theory and its applications in physics VI
A2 - Doebner, H.-D.
A2 - Dobrev, V.K.
PY - 2006///
SP - 3–25
PB - Heron Press
ER -
TY - BOOK
TI - Developmental biology: Branching morphogenesis
AU - Lubkin, Sharon R.
AU - Deisboeck, TS
AU - Kresh, JY
DA - 2006///
PY - 2006///
PB -
SE - 357-374
UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=BCI&KeyUT=BCI:BCI200700025770&KeyUID=BCI:BCI200700025770
ER -
TY - JOUR
TI - Efficient numerical methods for the 2D nonlinear Poisson–Boltzmann equation modeling charged spheres
AU - Li, Zhilin
AU - Qiao, Zhong-hua
AU - Tang, Tao
T2 - Journal of Computational Mathematics
DA - 2006///
PY - 2006///
VL - 24
IS - 3
SP - 252–264
ER -
TY - CONF
TI - Active Incipient Failure Detection: A Nonlinear Case Study
AU - Drake, K.J.
AU - Campbell, S.L.
AU - Andjelkovic, I.
AU - Sweetingham, K.
T2 - 4th International Conference on Computing, Communications and Control Technologies: CCCT '06
C2 - 2006///
C3 - Proceedings of the 4th International Conference on Computing, Communications and Control Technologies: CCCT '06
CY - Orlando, FL
DA - 2006///
PY - 2006/7/20/
ER -
TY - MGZN
TI - New ideas for SIAM conferences from Europe
AU - Ipsen, I.C.F.
T2 - SIAM News
DA - 2006/12//
PY - 2006/12//
VL - 39
SP - 5
M1 - 10
ER -
TY - CONF
TI - Dynamic Multidrug Therapies for HIV: Feedback and Structured Treatment Interruption Control Approaches
AU - Tran, H.
AU - Banks, H.T.
AU - David, John
AU - Toivanen, J.A.
AU - Kwon, Hae-Dae
T2 - 17th International Symposium on Mathematical Theory of Networks and Systems
C2 - 2006///
C3 - MTNS 2006 : proceedings of the 17th international symposium on mathematical theory of networks and systems, Kyoto, Japan, 24-28.07.2006.
CY - Kyoto International Conference Hall, Kyoto, Japan
DA - 2006///
PY - 2006/7/24/
PB - Kyoto University
ER -
TY - JOUR
TI - Book Review
AU - Lloyd, Alun L.
T2 - Journal of Difference Equations and Applications
DA - 2006/5//
PY - 2006/5//
DO - 10.1080/10236190600601508
VL - 12
IS - 5
SP - 501-502
J2 - Journal of Difference Equations and Applications
LA - en
OP -
SN - 1023-6198 1563-5120
UR - http://dx.doi.org/10.1080/10236190600601508
DB - Crossref
ER -
TY - CONF
TI - Solving Dynamic Geometric Constraints Involving Inequalities
AU - Hong, Hoon
AU - Li, Liyun
AU - Liang, Tielin
AU - Wang, Dongming
A2 - Calmet, Jacques
A2 - Ida, Tetsuo
A2 - Wang, Dongming
C2 - 2006///
C3 - Artificial Intelligence and Symbolic Computation
CY - Berlin, Heidelberg
DA - 2006///
SP - 181-195
PB - Springer Berlin Heidelberg
ER -
TY - BOOK
TI - Automated Deduction in Geometry, 5th International Workshop, ADG 2004, Gainesville, FL, USA, September 16-18, 2004, Revised Papers
AU - Hong, Hoon
AU - Wang, Dongming
A3 - Hong, Hoon
A3 - Wang, Dongming
DA - 2006/1//
PY - 2006/1//
DO - 10.1007/11615798
VL - 3763
PB - Springer Berlin Heidelberg
SE -
UR - http://dx.doi.org/10.1007/11615798
ER -
TY - BOOK
TI - Spectral Analysis of Large Dimensional Random Matrices
AU - Bai, Z.D.
AU - Silverstein, Jack
DA - 2006///
PY - 2006///
ET - 1
PB - Springer / Science Press
ER -
TY - JOUR
TI - Wellposedness and Blow-up of Solutions to Wave Equations with Supercritical Boundary Sources and Boundary Damping
T2 - Proceedings of the Conference on Differential and Difference Equations and Applications
DA - 2006///
PY - 2006///
ER -
TY - CONF
TI - A decomposition method for nonsmooth convex variational signal recovery
AU - Bauschke, H.H.
AU - Combettes, P.L.
AU - Pesquet, J.-C.
T2 - Proceedings of the IEEE International Conference on Acoustics, Speech, and Signal Processing
AB - Under consideration is the large body of signal recovery problems that can be formulated as the problem of minimizing the sum of two (not necessarily smooth) proper lower semicontinuous convex functions in a real Hilbert space. This generic problem is analyzed and a decomposition method is proposed to solve it. The convergence of the method, which is based on an extension of the Douglas-Rachford algorithm for monotone operators splitting, is established under general conditions. Various signal recovery applications are discussed and numerical results are provided
C2 - 2006///
C3 - Proceedings of the IEEE International Conference on Acoustics, Speech, and Signal Processing
CY - Toulouse, France
DA - 2006///
PY - 2006/5/14/
DO - 10.1109/ICASSP.2006.1661444
VL - 5
SP - 989–992
ER -
TY - CONF
TI - Iterative image deconvolution using overcomplete representations
AU - Chaux, C.
AU - Combettes, P.L.
AU - Pesquet, J.C.
AU - Wajs, V.R.
T2 - 14th European Signal Processing Conference
C2 - 2006///
C3 - Proceedings of the European Signal Processing Conference
CY - Florence, Italy
DA - 2006///
PY - 2006/9/4/
ER -
TY - JOUR
TI - Re: “Multivariate subresultants in roots” [J. Algebra 302 (2006) 16–36]
AU - D'Andrea, Carlos
AU - Krick, Teresa
AU - Szanto, Agnes
T2 - Journal of Algebra
DA - 2006/9//
PY - 2006/9//
DO - 10.1016/j.jalgebra.2006.07.004
VL - 303
IS - 2
SP - 449
J2 - Journal of Algebra
LA - en
OP -
SN - 0021-8693
UR - http://dx.doi.org/10.1016/j.jalgebra.2006.07.004
DB - Crossref
ER -
TY - CONF
TI - Hybrid symbolic-numeric computation
AU - Kaltofen, Erich
AU - Zhi, Lihong
T2 - the 2006 international symposium
AB - Several standard problems in symbolic computation, such as greatest common divisor and factorization of polynomials, sparse interpolation, or computing solutions to overdetermined systems of polynomial equations have non-trivial solutions only if the input coefficients satisfy certain algebraic constraints. Errors in the coefficients due to floating point round-off or through phsical measurement thus render the exact symbolic algorithms unusable. By symbolic-numeric methods one computes minimal deformations of the coefficients that yield non-trivial results. We will present hybrid algorithms and benchmark computations based on Gauss-Newton optimization, singular value decomposition(SVD) and structure-preserving total least squares (STLS) fitting for several of the above problems.A significant body of results to solve those "approximate computer algebra" problems has been discovered in the past 10 years. In the Computer Algebra Handbook the section on "Hybrid Methods" concludes as follows [2]: "The challenge of hybrid symbolic-numeric algorithms is to explore the effects of imprecision, discontinuity, and algorithmic complexity by applying mathematical optimization, perturbation theory, and inexact arithmetic and other tools in order to solve mathematical problems that today are not solvable by numerical or symbolic methods alone." The focus of our tutorial is on how to formulate several approximate symbolic computation problems as numerical problems in linear algebra and optimization and on software that realizes their solutions.Approximate Greatest Common Divisors [3]. Our paper at this conference presents a solution to the approximate GCD problem for several multivariate polynomials with real or complex coefficients. In addition, the coefficients of the minimally deformed input coefficients can be linearly constrained. In our tutorial we will give a precise definition of the approximate polynomial GCD problem and we will present techniques based on parametric optimization (slow) and STLS or Gauss/Newton iteration (fast) for its numerical solution. The fast methods can compute globally optimal solutions, but they cannot verify global optimality. We show how to apply the constrained approximate GCD problem to computing the nearest singular polynomial with a root of multiplicity at least k≥2.Approximate Factorization of Multivariate Polynomials [1]. Our solution and implementation of the approximate factorization problem follows our approach for the approximate GCD problem. Our algorithms are based on a generalization of the differential forms introduced by W. Ruppert and S. Gao to many variables, and use SVD or STLS and Gauss/Newton optimization to numerically compute the approximate multivariate factors.Solutions of Zero-dimensional Polynomial Systems [4]. We translate a system of polynomials into a system of linear partial differential equations (PDEs) with constant coefficients. The PDEs are brought to an involutive form by symbolic prolongations and numeric projections via SVD. The solutions of the polynomial system are obtained by solving an eigen-problem constructed from the null spaces of the involutive system and its geometric projections.
C2 - 2006///
C3 - Proceedings of the 2006 international symposium on Symbolic and algebraic computation - ISSAC '06
DA - 2006///
DO - 10.1145/1145768.1145775
PB - ACM Press
SN - 1595932763
UR - http://dx.doi.org/10.1145/1145768.1145775
DB - Crossref
ER -
TY - CONF
TI - Finding small degree factors of multivariate supersparse (lacunary) polynomials over algebraic number fields
AU - Kaltofen, Erich
AU - Koiran, Pascal
T2 - the 2006 international symposium
AB - We present algorithms that compute all irreducible factors of degree ≤ d of supersparse (lacunary) multivariate polynomials in n variables over an algebraic number field in deterministic polynomial-time in (l+d)n, where l is the size of the input polynomial. In supersparse polynomials, the term degrees enter logarithmically as their numbers of binary digits into the size measure l. The factors are again represented as supersparse polynomials. If the factors are represented as straight-line programs or black box polynomials, we can achieve randomized polynomial-time in (l+d)O(1). Our approach follows that by H. W. Lenstra, Jr., on computing factors of univariate supersparse polynomials over algebraic number fields. We generalize our ISSAC 2005 results for computing linear factors of supersparse bivariate polynomials over the rational numbers by appealing to recent lower bounds on the height of algebraic numbers and to a special case of the former Lang conjecture.
C2 - 2006///
C3 - Proceedings of the 2006 international symposium on Symbolic and algebraic computation - ISSAC '06
DA - 2006///
DO - 10.1145/1145768.1145798
PB - ACM Press
SN - 1595932763
UR - http://dx.doi.org/10.1145/1145768.1145798
DB - Crossref
ER -
TY - CONF
TI - Theory of Large Dimensional Random Matrices for Engineers
AU - Silverstein, Jack
AU - Tulino, Antonia
T2 - 2006 IEEE Ninth International Symposium on Spread Spectrum Techniques and Applications
AB - In the last few years, the asymptotic distribution of the singular values of certain random matrices has emerged as a key tool in the analysis and design of wireless communication channels. These channels are characterized by random matrices that admit various statistical descriptions depending on the actual application. The goal of this paper is the investigation and application of random matrix theory with particular emphasis on the asymptotic theorems on the distribution of the squared singular values under various assumption on the joint distribution of the random matrix entries
C2 - 2006/8//
C3 - 2006 IEEE Ninth International Symposium on Spread Spectrum Techniques and Applications
DA - 2006/8//
DO - 10.1109/isssta.2006.311814
PB - IEEE
SN - 0780397800 0780397797
UR - http://dx.doi.org/10.1109/isssta.2006.311814
DB - Crossref
ER -
TY - CHAP
TI - Infection dynamics on small-world networks
AU - Lloyd, Alun L
AU - Valeika, Steve
AU - Cintrón-Arias, Ariel
T2 - Contemporary Mathematics
PY - 2006///
DO - http://dx.doi.org/10.1090/conm/410/07729
VL - 410
SP - 209-234
PB - Providence, RI: American Mathematical Society
ER -
TY - CHAP
TI - Solving Dynamic Geometric Constraints Involving Inequalities
AU - Hong, Hoon
AU - Li, Liyun
AU - Liang, Tielin
AU - Wang, Dongming
T2 - Artificial Intelligence and Symbolic Computation
AB - This paper presents a specialized method for solving dynamic geometric constraints involving equalities and inequalities. The method works by decomposing the system of constraints into finitely many explicit solution representations in terms of parameters with radicals using triangular decomposition and real quantifier elimination. For any given values of the parameters, if they verify some set of computed relations, the values of the dependent variables may be easily computed by direct evaluation of the corresponding explicit expressions. The effectiveness of our method and its experimental implementation is illustrated by some examples of diagram generation.
PY - 2006///
DO - 10.1007/11856290_17
SP - 181-195
OP -
PB - Springer Berlin Heidelberg
SN - 9783540397281 9783540397304
UR - http://dx.doi.org/10.1007/11856290_17
DB - Crossref
ER -
TY - CONF
TI - Applications of Robust Failure Detection Algorithms to Power Systems
AU - Drake, K.J.
AU - Campbell, S.L.
AU - Andjelkovic, I.V.
AU - Hannas, B.L.
AU - Sweetingham, K.A.
T2 - 13th International Conference on, Intelligent Systems Application to Power Systems
AB - As modelling and simulation become increasingly popular in the design process and as an alternative to expensive testing, fault detection methods based on model identification algorithms become more reliable as well as less expensive and easier to implement. In this paper we discuss the application of two active fault detection algorithms based on model identification to power systems. The algorithms are similar in theory though differ in implementation. The first is a direct optimization approach that handles more general systems and more varied constraints. It requires more sophisticated software but it's easily adapted to more than two models. The second algorithm is a constrained control approach that can be implemented on common math software, such as Matlab or Scilab, and handles model uncertainty. In both cases, the algorithms are free of false alarms depending upon the quality of the models used.
C2 - 2006/3/21/
C3 - Proceedings of the 13th International Conference on, Intelligent Systems Application to Power Systems
DA - 2006/3/21/
DO - 10.1109/isap.2005.1599275
PB - IEEE
SN - 1599751747
UR - http://dx.doi.org/10.1109/isap.2005.1599275
DB - Crossref
ER -
TY - CONF
TI - Order of Convergence in the Direct Transcription Solution of Optimal Control Problems
AU - Engelsone, A.
AU - Campbell, S.L.
AU - Betts, J.T.
T2 - 44th IEEE Conference on Decision and Control
AB - In the direct transcription approach to the numerical solution of optimal control problems, the optimal control problem is discretized and the resulting nonlinear programming problem is solved numerically. There has been considerable study over the last 10 years on order of convergence of cost, state, multipliers, and control. This paper discusses these questions, and the highly technical results in the literature, in the context of their implications for industrial grade optimal control packages.
C2 - 2006/10/4/
C3 - Proceedings of the 44th IEEE Conference on Decision and Control
DA - 2006/10/4/
DO - 10.1109/cdc.2005.1582741
PB - IEEE
SN - 0780395670
UR - http://dx.doi.org/10.1109/cdc.2005.1582741
DB - Crossref
ER -
TY - JOUR
TI - Problems and techniques: Introduction
AU - Ipsen, I.C.F.
T2 - SIAM Review
DA - 2006///
PY - 2006///
VL - 48
IS - 2
SP - 485-486
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33744920863&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Problems and techniques
AU - Ipsen, I.
T2 - SIAM Review
DA - 2006///
PY - 2006///
VL - 48
IS - 1
SP - 41-42
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33644586567&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Problems and Techniques
AU - Ipsen, Ilse
T2 - SIAM Review
AB - The Problems and Techniques section features two papers: one on differential equations, and one on sums containing binomial coefficients and their logarithms. The deflection u(x) of a beam at point x can be described by an ordinary differential equation (ODE) of fourth order, such as, for instance, $$ \hspace*{58pt}\frac{ \mbox{ \textit{d}$^{\mbox{\fontsize{6pt}{6pt}\selectfont 4}}$\textit{u}(\textit{x})}} {\mbox{ \textit{dx}$^{\mbox{\fontsize{6pt}{6pt}\selectfont 4}}$}} \mbox{ = – 100,\qquad 0 $\leq$ \textit{x} $\leq$ 1.} $$ In this specific example the vertical load on the beam is uniform, as is the bending stiffness, and the beam has length 1. A unique solution u(x) exists if appropriate boundary conditions are prescribed, e.g., u(0) = u(1) = u$^{\prime}$(0) = u$^{\prime}$(1) = 0, which means that the beam is fixed at both ends. But what if the beam isn't fixed and we don't know the boundary conditions precisely? What if we have only bounds on the deflection and rotation at the endpoints, that is, inequalities of the form –1 $\leq$ u(x) $\leq$ 1 and –1 $\leq$ u$^{\prime}$(x) $\leq$ 1 for x = 0 and x = 1? Does a solution still exist? Enrique Castillo, Antonio Conejo, Carmen Castillo, and Roberto Mínguez, in “Solving Ordinary Differential Equations with Range Conditions,” show that it does indeed. The authors present a method to determine all solutions for linear ODEs whose boundary conditions are linear and are prescribed within intervals (or ranges) rather than at single points. Based on the inequalities in the boundary conditions, they formulate a system of linear inequalities. The solutions to this system represent coefficients in a linear combination that describes all solutions of the ODE. The authors also discuss tests for existence and uniqueness of solutions. The second paper, “Difference of Sums Containing Products of Binomial Coefficients and Their Logarithms,” is concerned with the expression $$ \hspace*{59pt}\displaystyle\frac{\mbox{1}} {\mbox{2$^{\mbox{\fontsize{6pt}{6pt}\selectfont \textit{n}}}$}} \mbox{$\displaystyle\sum_{\mbox{\fontsize{6pt}{6pt}\selectfont \textit{k} = 0}} ^{\mbox{\fontsize{6pt}{6pt}\selectfont \textit{n}}}$} \left(\displaystyle\frac{\mbox{1}}{\mbox{2}} \mbox{$\alpha_{\mbox{\fontsize{6pt}{6pt}\selectfont \textit{k}}}$} \mbox{ ln } \alpha_{\mbox{\fontsize{6pt}{6pt}\selectfont \textit{k}}}-\beta_{\mbox{\fontsize{6pt}{6pt}\selectfont \textit{k}}} \mbox{ ln } \beta_{\mbox{\fontsize{6pt}{6pt}\selectfont \textit{k}}} \right)\mbox{,} \qquad \mbox{$\alpha_{\mbox{\fontsize{6pt}{6pt}\selectfont \textit{k}}}$} \equiv {\mbox{\textit{n} + 1}\choose \mbox{\textit{k}}}\mbox{,}\quad \mbox{$\beta_{\mbox{\fontsize{6pt}{6pt}\selectfont \textit{k}}}$} \equiv {\mbox{\textit{n}}\choose \mbox{\textit{k}}}\mbox{,} $$ which occurs in an analysis of covert communication channels and is related to the capacity of the covert channel. Authors Allen Miller and Ira Moskowitz use binomial identities to simplify the expression, show that it increases monotonically with n, and prove that it converges to ln 2 as n $\rightarrow \infty$.
DA - 2006/1//
PY - 2006/1//
DO - 10.1137/siread000048000002000305000001
VL - 48
IS - 2
SP - 305-305
ER -
TY - JOUR
TI - Problems and Techniques
AU - Ipsen, Ilse
T2 - SIAM Review
AB - Readers may be surprised to learn that there is something on which everybody in my department agrees: the heating system is absolutely ineffective. Some offices get too hot too fast (usually inhabitated by some who like it cold), while other offices (like mine, unfortunately) take forever to become even slightly warm. The building is heated by a network of pipes through which hot steam is circulated. Question: How to design a heating system that delivers the same amount of steam to each office as fast as possible, thereby ensuring that all offices have the same temperature as fast as possible? Answer: Construct a specific matrix, called a weighted Laplacian, and choose the weights so as to maximize its second largest eigenvalue. The weights tell us how wide each pipe needs to be. Of course, this is a constrained optimization problem, because we are on a budget and can afford only a limited amount of material for the pipes. A more general problem is discussed by Jun Sun, Stephen Boyd, Lin Xiao, and Persi Diaconis in their paper “The Fastest Mixing Markov Process on a Graph and a Connection to a Maximum Variance Unfolding Problem.” They express the problem of maximizing the second largest eigenvalue of the Laplacian as a semidefinite program. The dual of this program has a simple geometric interpretation: It’s the problem of positioning n points in n‐space, so that they are as far apart as possible, but do not exceed prescribed distances between any two points. Coming back now to the heating issues in my department, we have been promised a new building. Ground breaking is to start anytime now (or so, at least, we are told). I have been thinking about giving this paper to the architects; it might inspire them to install a more effective heating system. In the well‐written paper “Globalization Techniques for Newton–Krylov Methods and Applications to the Fully Coupled Solution of the Navier–Stokes Equations,” Roger Pawlowski, John Shadid, Joseph Simonis, and Homer Walker discuss methods for the solution of systems of nonlinear equations $F(u)=0$. Such systems arise, for instance, when one discretizes partial differential equations to solve fluid flow problems. Arguably the most popular method for solving $F(u)=0$ is Newton’s method. It starts from an initial approximation $u_0$ and produces successively better (we hope) iterates $u_{k+1}$ as updates of the previous iterate, $u_{k+1}=u_k+s_k$. The step $s_k$ is computed as the solution to the linear system $F^{\prime}(u_k)s_k=-F(u_k)$, where the Jacobian $F^{\prime}(u)$ is the matrix of derivatives. When the linear system is solved by a Krylov space method, for instance, one talks about a Newton–Krylov method. Convincing Newton’s method to converge to the solution is not always easy, especially when the initial approximation $u_0$ is far away. A variety of strategies is available that can enhance the performance of Newton’s method. The authors discuss two. To increase robustness, one can solve the linear systems more or less accurately; this is done by terminating the linear system solution as soon as the residual norm $\|F^{\prime}(u_k)+F(u_k)s_k\|$ falls below a specified forcing term. To improve the chances for convergence, one can globalize Newton’s method by changing the length of the step $s_k$ (as opposed to its direction), or by choosing a step $s_k$ that minimizes the residual norm over a particular region. The authors prove convergence results, and perform numerical experiments on standard benchmark problems to compare different forcing terms and globalization strategies. Are you one of those people who firmly believes that there is one and only one way to win a tennis match? And that’s by subjecting your opponent to that impossible‐to‐return 700‐horse‐power serve? Yes? Then we might have just the paper for you. In “Monte Carlo Tennis,” Paul Newton and Kamran Aslam analyze the probability of winning in tennis, and express it in terms of the probability that a player wins a point when serving. In previous work, Paul Newton and coauthor Joe Keller had assumed that this probability is constant—throughout the whole match, and even a tournament. This amounts to assuming that points in tennis are random variables, independently and identically distributed (i.i.d.). However, this assumption fails to account for the “hot‐hand,” when everything goes just swimmingly; the “back‐to‐the‐wall” effect, when miraculous feats become possible in the face of looming loss; or simply the adjustment to new tennis balls. Do these things really make a difference? Is the i.i.d. assumption unrealistic? Paul Newton and Kamran Asham perform Monte Carlo simulations in MATLAB to answer this question. Read the paper if you want to know what they come up with.
DA - 2006/1//
PY - 2006/1//
DO - 10.1137/siread000048000004000679000001
VL - 48
IS - 4
SP - 679-680
ER -
TY - CONF
TI - Clusters, Coxeter-sortable elements and noncrossing partitions
AU - Reading, N.
C2 - 2006///
C3 - FPSAC 2006 - Proceedings: 18th Annual International Conference on Formal Power Series and Algebraic Combinatorics
DA - 2006///
SP - 275-281
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84860648750&partnerID=MN8TOARS
ER -
TY - CONF
TI - Computer Optimized Gun Design
AU - Ives, R. L.
AU - Read, M.E.
AU - Bui, Thuc
AU - David, John
AU - Tran, Hien
T2 - >2006 Joint 31st International Conference on Infrared Millimeter Waves and 14th International Conference on Teraherz Electronics
AB - Computer optimization can explore a wider parameter space than practical with manual design, particularly for 3D geometries. This allows rapid, economical development of higher performance devices. The proliferation of parametric solid modeling programs allows optimization of both geometry and operating parameters. This presentation described computer optimization in the 3D trajectory code beam optics analysis (BOA). This is possible because meshing in BOA is completely automatic, allowing the program to be controlled by the optimization routines.
C2 - 2006/9//
C3 - 2006 Joint 31st International Conference on Infrared Millimeter Waves and 14th International Conference on Teraherz Electronics
DA - 2006/9//
DO - 10.1109/icimw.2006.368358
PB - IEEE
SN - 1424403995 1424404002
UR - http://dx.doi.org/10.1109/icimw.2006.368358
DB - Crossref
ER -
TY - JOUR
TI - Stochastic portfolio optimization with log utility
AU - Pang, Tao
T2 - International Journal of Theoretical and Applied Finance
AB - A portfolio optimization problem on an infinite time horizon is considered. Risky asset price obeys a logarithmic Brownian motion, and the interest rate varies according to an ergodic Markov diffusion process. Moreover, the interest rate fluctuation is correlated with the risky asset price fluctuation. The goal is to choose optimal investment and consumption policies to maximize the infinite horizon expected discounted log utility of consumption. A dynamic programming principle is used to derive the dynamic programming equation (DPE). The explicit solutions for optimal consumption and investment control policies are obtained. In addition, for a special case, an explicit formula for the value function is given.
DA - 2006///
PY - 2006///
DO - 10.1142/s0219024906003858
VL - 9
IS - 6
SP - 869-887
SN - 0219-0249 1793-6322
UR - http://dx.doi.org/10.1142/s0219024906003858
KW - Portfolio optimization
KW - dynamic programming equations
KW - subsolution and supersolutions
ER -
TY - CONF
TI - Comparison between failure detection test signals for continuous systems and sampled-data systems
AU - Choe, D.
AU - Campbell, S. L.
AU - Nikoukhah, R.
T2 - Proceedings of the 45th IEEE Conference on Decision and Control
AB - In active failure detection it is essential to have auxiliary signal inputs that are capable of identifying the status of observed systems while the operations of the systems are minimally disturbed by the extra input. Recently, two signal-design-algorithms for active failure detection were introduced: one that computes optimal continuous detection signals for continuous systems (CS) and the other that designs optimal piecewise-constant signal inputs for sampled-data systems (SDS). In some applications simple piecewise constant inputs are sought. In this paper, we combine the key ideas of the two previous algorithms and present an algorithm that finds optimal piecewise-constant signals for continuous systems. This modified algorithm provides a suboptimal detection signal inputs for continuous systems and would appear to be greatly faster than the original CS algorithm. We also compare the three algorithms and the corresponding optimal signals through a computational experiment
C2 - 2006///
C3 - Proceedings of the 45th IEEE Conference on Decision and Control
DA - 2006///
DO - 10.1109/cdc.2006.377349
PB - IEEE
SN - 1424401712
UR - http://dx.doi.org/10.1109/cdc.2006.377349
DB - Crossref
ER -
TY - CONF
TI - Model Based Failure Detection using Test Signals from Linearizations: A Case Study
AU - Campbell, S.
AU - Drake, K.
AU - Andjelkovic, I.
AU - Sweetingham, K.
AU - Choe, D.
T2 - 2006 IEEE Conference on Computer-Aided Control Systems Design
C2 - 2006/10//
C3 - 2006 IEEE Conference on Computer-Aided Control Systems Design
DA - 2006/10//
DO - 10.1109/cacsd.2006.285526
PB - IEEE
SN - 0780397975
UR - http://dx.doi.org/10.1109/cacsd.2006.285526
DB - Crossref
ER -
TY - CONF
TI - Robust detection of incipient faults: an active approach
AU - Nikoukhah, R.
AU - Campbell, S. L.
T2 - 2006 14th Mediterranean Conference on Control and Automation
AB - The methodology of auxiliary signal design for robust failure detection based on multi-model formulation of normal and failed systems is used to study the problem of incipient fault detection. Here, the fault is modeled as a drift in a system parameter, and an auxiliary signal is to be designed to enhance the detection of variations in this parameter. It is shown that it is possible to consider the model of the system with a drifted parameter as a second model and use the multi-model framework for designing the auxiliary signal by considering the limiting case as the parameter variation goes to zero. The result can be applied very effectively to early detection problems where small parameter variations should be detected
C2 - 2006/6//
C3 - 2006 14th Mediterranean Conference on Control and Automation
DA - 2006/6//
DO - 10.1109/med.2006.328694
PB - IEEE
SN - 0978672011 0978672003
UR - http://dx.doi.org/10.1109/med.2006.328694
DB - Crossref
ER -
TY - JOUR
TI - Approximating curves for nonexpansive and monotone operators
AU - Combettes, P.L.
AU - Hirstoaga, S.A.
T2 - Journal of Convex Analysis
DA - 2006/12//
PY - 2006/12//
VL - 13
IS - 3-4
SP - 633–646
ER -
TY - JOUR
TI - The Problem of Active Shielding for Composite Regions
AU - Ryaben’kii, V. S.
AU - Utyuzhnikov, S. V.
AU - Tsynkov, S. V.
T2 - Dokl. Akad. Nauk
DA - 2006///
PY - 2006///
VL - 411
IS - 2
SP - 164-166
UR - https://stsynkov.math.ncsu.edu/publications/a45r.pdf
N1 - [Russian]
RN - [Russian]
ER -
TY - JOUR
TI - Weak lacunae of electromagnetic waves in dilute plasma
AU - Tsynkov, Semyon
T2 - SIAM Journal on Applied Mathematics
AB - The propagation of waves is said to be diffusionless, and the corresponding governing PDE (or system) is said to satisfy Huygens' principle if the waves due to compactly supported sources have sharp aft fronts. The areas of no disturbance behind the aft fronts are called lacunae. Diffusionless propagation of waves is rare, whereas its opposite—diffusive propagation accompanied by aftereffects—is common. Nonetheless, lacunae can still be observed in a number of important applications, including the Maxwell equations in vacuum or in dielectrics with static response. In the framework of these applications, lacunae can be efficiently exploited for the numerical simulation of unsteady waves, and considerable progress has been made toward the development of lacunae-based methods for computational electromagnetism. Maxwell equations in vacuum are Huygens' because they reduce to a set of d'Alembert equations. Besides d'Alembert equations, there are no other scalar Huygens' equations in the standard $3+1$-dimensional Minkowski space-time. In terms of physics, this means that the mechanisms of dissipation and dispersion destroy the lacunae. In fact, all conventional low-frequency electromagnetic models, such as metals with Ohm conductivity, semiconductors, and magnetohydrodynamic media, are diffusive. An important case of the propagation of high-frequency electromagnetic waves in plasma is governed by the Klein–Gordon equation. It does not reduce to the d'Alembert equation either, and therefore the corresponding propagation is diffusive as well. However, one can still identify “weak lacunae” in the solutions of the Klein–Gordon equation, with the aft fronts that can be clearly observed, although they may not be as sharp as in the pure Huygens' case. Moreover, one can show that the “depth” of a weak lacuna is controlled by the dimensionless ratio of the Langmuir frequency to the primary carrying frequency of the waves.
DA - 2006///
PY - 2006///
DO - 10.1137/060655134
VL - 67
IS - 6
SP - 1548–1581
KW - Huygens' principle
KW - wave diffusion
KW - aftereffects
KW - aft fronts
KW - lacunae
KW - ionospheric propagation
KW - isotropic plasma
KW - Langmuir frequency
KW - cold plasma
KW - transverse waves
KW - Maxwell equations
KW - Klein-Gordon equation
KW - weak dispersion
KW - short waves
KW - external magnetic field
KW - cyclotron frequency
KW - gyrotropy
KW - Faraday rotation
ER -
TY - JOUR
TI - Active control of sound for composite regions
AU - Peterson, A. W.
AU - Tsynkov, Semyon
T2 - SIAM Journal on Applied Mathematics
AB - We present a methodology for the active control of time-harmonic wave fields, e.g., acoustic disturbances, in composite regions. This methodology extends our previous approach developed for the case of arcwise connected regions. The overall objective is to eliminate the effect of all outside field sources on a given domain of interest, i.e., to shield this domain. In this context, active shielding means introducing additional field sources, called active controls, that generate the annihilating signal and cancel out the unwanted component of the field. As such, the problem of active shielding can be interpreted as a special inverse source problem for the governing differential equation or system. For a composite domain, not only do the controls prevent interference from all exterior sources, but they can also enforce a predetermined communication pattern between the individual subdomains (as many as desired). In other words, they either allow the subdomains to communicate freely with one another or otherwise have them shielded from their peers. In the paper, we obtain a general solution for the composite active shielding problem and show that it reduces to solving a collection of auxiliary problems for arcwise connected domains. The general solution is constructed in two stages. Namely, if a particular subdomain is not allowed to hear another subdomain, then the supplementary controls are employed first. They communicate the required data prior to building the final set of controls. The general solution can be obtained with only the knowledge of the acoustic signals propagating through the boundaries of the subdomains. No knowledge of the field sources is required, nor is any knowledge of the properties of the medium needed.
DA - 2006///
PY - 2006///
DO - 10.1137/060662368
VL - 67
IS - 6
SP - 1582–1609
KW - active shielding
KW - noise control
KW - inverse source problem
KW - time-harmonic acoustic fields
KW - composite domain
KW - communication pattern
KW - the Helmholtz equation
KW - generalized Calderon's potentials
KW - exact volumetric cancellation
KW - general solution
KW - incoming and outgoing waves
KW - wave split
ER -
TY - JOUR
TI - Using Water Transfers to Manage Supply Risk
AU - Characklis, G W
AU - Kirsch, B R
AU - Ramsey, J
AU - Dillard, K E M
AU - Kelley, C T
T2 - Proceedings of Symposium on Safe Drinking Water: Where Science Meets Policy
DA - 2006///
PY - 2006///
ER -
TY - JOUR
TI - Reduced order models for nonlinear least squares problems
AU - Kelley, C T
AU - Sorensen, D
AU - Reese, J P
AU - Winton, C
DA - 2006///
PY - 2006///
ER -
TY - CONF
TI - Simulating Non-{D}arcy Flow through Porous Media using {S}undance
AU - Reese, J P
AU - Long, Kevin
AU - Kelley, C T
AU - Miller, C T
AU - Gray, W G
C2 - 2006///
C3 - Proceedings of Computational Methods in Water Resources XVI
DA - 2006///
SP - Paper number 148, 8 pages
ER -
TY - JOUR
TI - {SETraNS} Manual: Simulation of Electronic Transport in Nanoscale Structures
AU - Lasater, M S
AU - Recine, Greg
AU - Kelley, C T
AU - Woolard, D L
AU - Zhao, P
DA - 2006///
PY - 2006///
ER -
TY - CONF
TI - Simulating Nanoscale Devices
AU - Lasater, M S
AU - Kelley, C T
AU - Salinger, A
AU - Zhao, P
AU - Woolard, D L
A2 - Iwai, H
A2 - Nishi, Y
A2 - Shur, M S
A2 - Wong, H
C2 - 2006///
C3 - International Journal of High Speed Electronics and Systems
DA - 2006///
VL - 16
SP - 677-690
PB - World Scientific
ER -
TY - JOUR
TI - Parallel Parameter Study of the {Wigner-Poisson} Equations for {RTDs}
AU - Lasater, M S
AU - Kelley, C T
AU - Salinger, A
AU - Woolard, D L
AU - Zhao, P
T2 - Computers and Mathematics with Applications
DA - 2006///
PY - 2006///
VL - 51
SP - 1677-1688
ER -
TY - CONF
TI - Nonlinear multilevel iterative methods for multiscale models of air/water flow in porous media
AU - Kees, C E
AU - Farthing, M W
AU - Howington, S E
AU - Jenkins, E W
AU - Kelley, C T
C2 - 2006///
C3 - Proceedings of Computational Methods in Water Resources XVI
DA - 2006///
SP - Paper number 256, 8 pages
ER -
TY - JOUR
TI - Model Reduction for Nonlinear Least Squares
AU - Kelley, C T
AU - Sorensen, D
AU - Reese, J P
AU - Winton, C
DA - 2006///
PY - 2006///
ER -
TY - JOUR
TI - Special issue on accurate solution of eigenvalue problems
AU - Ipsen, I.C.F.
T2 - SIAM Journal on Matrix Analysis and Applications
DA - 2006///
PY - 2006///
VL - 28
IS - 4
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-35348933724&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Problems and techniques: Introduction
AU - Ipsen, I.C.F.
T2 - SIAM Review
DA - 2006///
PY - 2006///
VL - 48
IS - 2
SP - 485-486
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33744920863&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Problems and Techniques
AU - Ipsen, Ilse
T2 - SIAM Review
AB - Related DatabasesWeb of Science You must be logged in with an active subscription to view this.Article DataHistoryPublished online: 17 February 2012Publication DataISSN (print): 0036-1445ISSN (online): 1095-7200Publisher: Society for Industrial and Applied MathematicsCODEN: siread
DA - 2006/1//
PY - 2006/1//
DO - 10.1137/siread000048000003000485000001
VL - 48
IS - 3
SP - 485-485
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33751424677&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Problems and Techniques
AU - Ipsen, Ilse
T2 - SIAM Review
AB - The Problems and Techniques section in this issue contains three papers on very different topics: achieving reliability through optimization, improving the solution of systems of linear equations by preconditioning, and determining asymptotic expansion of integrals in Laplace form. Reliability is an important aspect in engineering design. One can make a system (such as a car) more reliable by introducing redundancy (e.g., carrying around a spare tire) or by making individual system components more reliable (e.g., using better material to manufacture car parts). In the first paper, James Falk, Nozer Singpurwalla, and Yefim Vladimirsky pursue the latter approach, opting to increase the reliability of individual components. This is called reliability allocation. Why not just adopt the simplest strategy and make all components of a system more reliable? This could be way too expensive. Consider, for instance, my Volkswagen GTI, a system with probably at least 3000 different components. Let's measure the reliability of the GTI by whether it drives or not. Replacing the plastic cup holder by one made from aluminum would cost a lot but would do nothing to increase the car's reliability. That's because the cup holder does not contribute to the drivability of the car (provided we disregard the driver who needs the cupholder for coffee to stay awake). However, replacing the plastic radiator by one made from aluminum costs only slightly more, but increases the reliability of the car significantly because the added cooling capacity prevents the engine from overheating when one wants to drive really fast. The question therefore is, which components of a system should we make more reliable, while keeping an eye on the cost? The authors propose to maximize a utility function that is aware of the interaction among components of the system, and trades off the cost of increasing reliability with greater probability of system functioning. In the second paper, Luis González presents a well-written and elegant analysis to justify the effectiveness of a particular approach for solving systems of linear equations. Systems of linear equations Ax = b whose coefficient matrix A has large dimension and is sparse (i.e., contains many zero elements) occur, for instance, whenever partial differential equations are discretized. Direct methods for solving Ax = b, such as Gaussian elimination, can be too expensive when they introduce too many nonzero elements during the course of the computation. In this case one may resort to iterative methods, which in successive iterations produce better and better approximations—or so one hopes. Unless one is lucky with one's matrix A, though, iterative methods can be slow and unreliable. Efficiency and reliability can be improved by preconditioning the system, i.e., transforming Ax = b into a preconditioned system (AN) y = b, where the matrix N is chosen such that the system (AN) y = b can be solved quickly, and the original solution x = Ny can be recovered easily. In this paper, the matrix N is chosen as an approximate inverse of A, so that the preconditioned matrix AN is close to the identity matrix I, and iterative methods applied to (AN) y = b converge fast. To ensure that recovery of the solution x = Ny is still easy, restrictions must be placed on N. The paper sets a very general context by assuming that N comes from some subspace S of matrices. Formally, the criterion is to choose N such that the residual $\|$AN – I$\|_{\fontsize{6pt}{6pt}\selectfont\textit{F}}$ is minimized, in the Frobenius norm, over all matrices from the subspace S. The idea for justifying the effectiveness of the preconditioner N is to cast the minimization problem in the form min$_{\fontsize{6pt}{6pt}\selectfont\textit{Q}}\|$Q – I$\|_{\fontsize{6pt}{6pt}\selectfont\textit{F}}$, where Q is a matrix from the subspace AS. The problem now amounts to analyzing orthogonal projections Q of the identity matrix I (hence the title of the paper). It turns out that if the smallest singular value of the preconditioned matrix AN is close to one and if also the smallest eigenvalue in magnitude is close to one, then everything works out: the residual $\|$AN – I$\|_{\fontsize{6pt}{6pt}\selectfont\textit{F}}$ is small, the matrix AN is well-conditioned, and its departure from normality is small. These are exactly the conditions that guarantee (in exact arithmetic) the effectiveness and reliability of the preconditioner N. To understand what's going on in the third paper, let's start with an example. The Gamma function can be represented as $$\hspace*{21pt}\hskip3pc \mbox{$\Gamma$($\lambda$ + 1) = $\displaystyle\int_{\mbox{\fontsize{6pt}{6pt}\selectfont 0}}^{\infty}$ u$^{\lambda}e^{\fontsize{6pt}{6pt}\selectfont\mbox{\fontsize{6pt}{6pt}\selectfont –}\textit{u}}$\textit{du},} $$ where $\lambda> $ 0. If we are interested in how $\Gamma$ depends on the positive parameter $\lambda$, we can determine the asymptotic expansion $$\hskip3pc\hspace*{21pt}\mbox{$\Gamma$($\lambda$ + 1) ~ \textit{e}$^{\mbox{\fontsize{6pt}{6pt}\selectfont–}\lambda} \lambda^{\mbox{\fontsize{6pt}{6pt}\selectfont$\lambda$ +\,1}}$ $\left(\frac{\displaystyle\mbox{2} \pi}{\mbox{\fontsize{9}{9pt}\selectfont$\lambda$}}\right)^{\mbox{\fontsize{6pt}{6pt}\selectfont 1/2}} \left[\mbox{1 + }{\mbox{1} \over \mbox{12}\mbox{\fontsize{9}{9pt}\selectfont$\lambda$}}\mbox{\,+\,}{\mbox{1}\over \mbox{288}\,\mbox{\fontsize{9}{9pt}\selectfont$\lambda$}^{\mbox{\fontsize{6pt}{6pt}\selectfont 2}}}\mbox{\,+\,}\cdots\right].$} $$ One way of obtaining such an asymptotic expansion is to change variables, u = $\lambda$(1 + x),set h(x) $\equiv$ x – log(1 + x), and write $$\hspace*{0pt}\hskip3pc\hspace*{26pt}\mbox{$\Gamma$($\lambda$ + 1) = \textit{e}$^{\mbox{\fontsize{6pt}{6pt}\selectfont–}\lambda} \lambda^{\mbox{\fontsize{6pt}{6pt}\selectfont$\lambda$ +\,1}} \displaystyle\int_{-1}^{\infty}$ \textit{e}$^{\mbox{\fontsize{6pt}{6pt}\selectfont–$\lambda$\textit{h}(\textit{x})}}$\textit{dx}.} $$ The integral is in Laplace form, i.e., it is of the form $$\hskip3pc\hspace*{23pt}\mbox{\textit{I}($\lambda$) = $\displaystyle\int_{\fontsize{6pt}{6pt}\selectfont\textit{a}}^{\fontsize{6pt}{6pt}\selectfont\textit{b}} \phi$(\textit{x})\textit{e}$^{\mbox{\fontsize{6pt}{6pt}\selectfont–$\lambda$\textit{h}(\textit{x})}}\textit{dx}$,} $$ where, in this special case, $\phi$(x) = 1, a = –1, and b = $\infty$. Here is the reason why Laplace's form is important, and why it was named after Laplace: Laplace observed that the major contributions to the integral I($\lambda$) come from those points where e$^{\fontsize{6pt}{6pt}\selectfont{-\textit{h}(\textit{x})}}$ attains its greatest values. He showed that if, among other things, h(x) has a minimum only at the left endpoint x = a, then the integral has the asymptotic expansion $$\hskip3pc \mbox{\textit{I}($\lambda$) ~ \textit{e}$^{\mbox{\fontsize{6pt}{6pt}\selectfont–$\lambda$\textit{h}(\textit{a})}}\> \displaystyle\sum_{\fontsize{6pt}{6pt}\selectfont\textit{s = 0}}^{\infty} \frac{\mbox{\textit{d}$_{\fontsize{6pt}{6pt}\selectfont\textit{s}}$}} {\lambda^{\mbox{\fontsize{6pt}{6pt}\selectfont($\alpha$ + \textit{s})$/\mu$}}}\qquad \mbox{as}~\lambda\rightarrow\infty$, } $$ where the numbers $\alpha$ and $\mu$ come from expansions of h(x) and $\phi$(x), respectively. However, symbolic computation of the coefficients d$_{\fontsize{6pt}{6pt}\selectfont\textit{s}}$ in asymptotic expansions of integrals in Laplace form I($\lambda$) has often been intractable. In his paper, John Wojdylo presents explicit expressions for the coefficients d$_{\fontsize{6pt}{6pt}\selectfont\textit{s}}$ that are more efficient and simpler than existing ones, and which should facilitate symbolic implementations. Laplace's method is one of several popular methods for determining asymptotic expansions of integrals (integration by parts is another). Asymptotic expansions can be more advantageous than numerical methods because they can reveal dependence on parameters that are physically significant, they can be differentiated or integrated exactly, and they can be more accurate.
DA - 2006/1//
PY - 2006/1//
DO - 10.1137/siread000048000001000041000001
VL - 48
IS - 1
SP - 41-42
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33644586567&partnerID=MN8TOARS
ER -
TY - CONF
TI - Approximate greatest common divisors of several polynomials with linearly constrained coefficients and singular polynomials
AU - Kaltofen, Erich
AU - Yang, Zhengfeng
AU - Zhi, Lihong
T2 - the 2006 international symposium
AB - We consider the problem of computing minimal real or complex deformations to the coefficients in a list of relatively prime real or complex multivariate polynomials such that the deformed polynomials have a greatest common divisor (GCD) of at least a given degree k. In addition, we restrict the deformed coefficients by a given set of linear constraints, thus introducing the linearly constrained approximate GCD problem. We present an algorithm based on a version of the structured total least norm (STLN) method and demonstrate on a diverse set of benchmark polynomials that the algorithm in practice computes globally minimal approximations. As an application of the linearly constrained approximate GCD problem we present an STLN-based method that computes a real or complex polynomial the nearest real or complex polynomial that has a root of multiplicity at least k. We demonstrate that the algorithm in practice computes on the benchmark polynomials given in the literature the known globally optimal nearest singular polynomials. Our algorithms can handle, via randomized preconditioning, the difficult case when the nearest solution to a list of real input polynomials actually has non-real complex coefficients.
C2 - 2006///
C3 - Proceedings of the 2006 international symposium on Symbolic and algebraic computation - ISSAC '06
DA - 2006///
DO - 10.1145/1145768.1145799
PB - ACM Press
SN - 1595932763
UR - http://dx.doi.org/10.1145/1145768.1145799
DB - Crossref
ER -
TY - JOUR
TI - Differential-Algebraic Equations
AU - Campbell, Stephen
AU - März, Roswitha
AU - Rentrop, Peter
AU - Petzold, Linda
T2 - Oberwolfach Reports
AB - The topic of Differential Algebraic Equations (DAEs) began to attract significant research interest in applied and numerical mathematics in the early 1980's. Today, a quarter of a century later, DAEs are an independent field of research, which is gaining in importance and becoming of increasing interest for both applications and mathematical theory.\\\ This Oberwolfach workshop brought together 48 experts in applied mathematics, among them, on the one hand, some who have already influenced and formed the developments of the field, and on the other hand, some very young researchers who have shown outstanding creativity and competence in connection with their PhD theses and thus raise great hopes for further advances.\\\ The 16 female and 32 male scientists came from 13 countries to meet and work together in the wonderful, unique Oberwolfach atmosphere, which stimulated a fruitful and pleasant collaboration.\\\ The schedule comprised a total of 34 presentations, 18 of which were arranged into 14 survey lectures (some of them with more than one speaker) offering a broader treatment of a particular subject. 16 shorter contributions supplemented the scientific programmme. The areas can be classified (of course with large overlap) into 4 groups: \begin{itemize} \item abstract differential algebraic systems, coupled systems, partial differential algebraic systems; \item analysis of (ordinary) differential algebraic equations and application of numerical methods to problems having new mathematical complexity; \item innovative and improved numerical integration methods to solve highly complex application problems; \item optimization with constraints described by DAEs and control problems concerning DAEs. \end{itemize} The broad range of these areas and the diversity of the participants stimulated fruitful discussions between the different branches and gave rise to new contacts and collaborations. A considerable gain in knowledgde and progress became obvious, which includes the formulation of open questions and challenges for the future.\\\ We are grateful to the Mathematisches Forschungsinstitut Oberwolfach for providing an inspiring setting for this workshop.
DA - 2006///
PY - 2006///
DO - 10.4171/owr/2006/18
SP - 1077-1168
ER -
TY - JOUR
TI - Effective solution of linear Diophantine equation systems with an application in chemistry
T2 - Journal of Mathematical Chemistry
DA - 2006/1//
PY - 2006/1//
DO - 10.1007/s10910-005-9001-9
UR - http://dx.doi.org/10.1007/s10910-005-9001-9
KW - decomposition of overall reaction
KW - linear Diophantine equations
KW - linear programming
ER -
TY - JOUR
TI - A strongly convergent reflection method for finding the projection onto the intersection of two closed convex sets in a Hilbert space
AU - Bauschke, Heinz H.
AU - Combettes, Patrick L.
AU - Luke, D. Russell
T2 - Journal of Approximation Theory
AB - A new iterative method for finding the projection onto the intersection of two closed convex sets in a Hilbert space is presented. It is a Haugazeau-like modification of a recently proposed averaged alternating reflections method which produces a strongly convergent sequence.
DA - 2006/7//
PY - 2006/7//
DO - 10.1016/j.jat.2006.01.003
VL - 141
IS - 1
SP - 63-69
J2 - Journal of Approximation Theory
LA - en
OP -
SN - 0021-9045
UR - http://dx.doi.org/10.1016/j.jat.2006.01.003
DB - Crossref
KW - best approximation problem
KW - convex set
KW - projection
KW - strong convergence
ER -
TY - CONF
TI - Wellposedness and Blow-up of Solutions to Wave Equations with Supercritical Boundary Sources and Boundary Damping
AU - Bociu, Lorena
AU - Lasiecka, I.
C2 - 2006///
C3 - Proceedings of the Conference on Differential and Difference Equations and Applications
DA - 2006///
SP - 635–643
PB - Hindawi Publishing Corporation
ER -
TY - JOUR
TI - The Problem of Active Shielding for Multiply Connected Regions
AU - Ryaben’kii, V.S.
AU - Utyuzhnikov, S.V.
AU - Tsynkov, S.V.
T2 - Doklady Rossiiskoi Akademii Nauk Matematika (Transactions of the Russian Academy of Sciences, Mathematics)
DA - 2006///
PY - 2006///
VL - 411
IS - 2
SP - 164–166
ER -
TY - JOUR
TI - Stochastic optimal control problems with a bounded memory
AU - Chang, M.-H.
AU - Pang, T.
AU - Pemy, Moustapha
T2 - Operations Research and Its Applications, Lecture Notes in Operations Research
DA - 2006///
PY - 2006///
VL - 6
SP - 82–94
ER -
TY -
ER -
TY - CHAP
TI - Drug resistance in acute viral infections:
Rhinovirus as a case study
AU - Lloyd, Alun
AU - Wodarz, Dominik
T2 - Disease Evolution
AB - The emergence and spread of drug resistant virus variants reflects both within-host and between-host processes. We develop an epidemiological model that can be used to address the spread of resistance at the population level, and a virus dynamics model that can be used to study the dynamics of virus over the time course of an individual’s infection. The dynamics depend in an important way on the competition between drug sensitive and drug resistant virus strains. A key observation is that the strength of competition between strains is strongly modulated by the degree of cross-immunity that infection with one strain confers against infection with the other. At the within-host level, we see that an efficient immune response can reduce the likelihood of the emergence of resistant virus. Consequently, resistance poses more of a problem for chronic infections in which there is significant immune impairment than for acute infections. These findings are discussed in the setting of rhinovirus infections, which are an important cause of infection in humans and for which novel antiviral drugs are being developed.
PY - 2006/7/26/
DO - 10.1090/dimacs/071/10
SP - 193-212
OP -
PB - American Mathematical
Society
SN - 9780821837535 9781470440282
UR - http://dx.doi.org/10.1090/dimacs/071/10
DB - Crossref
ER -
TY - JOUR
TI - Joint minimization with alternating Bregman proximity operators
AU - Bauschke, H.H.
AU - Combettes, P.L.
AU - Noll, D.
T2 - Pacific Journal of Optimization
DA - 2006/9//
PY - 2006/9//
VL - 2
IS - 3
SP - 401–424
ER -
TY - CHAP
TI - Cardiovascular modeling at IMFUFA, in The way through science and philosophy
AU - Larsen, J.K.
AU - Andreasen, V.
AU - Larsen, H.
AU - Olufsen, M.S.
AU - Ottesen, J.T.
T2 - Tributes
A2 - Andersen, H.B.
A2 - Christiansen, F.V.
A2 - Jorgensen, K.F.
A2 - Hendricks, V.F.
PY - 2006///
VL - 4
SP - 87–96
PB - College Publications
ER -
TY - JOUR
TI - Mathematical properties and analysis of Google’s PageRank
AU - Ipsen, I.C.F.
AU - Wills, R.S.
T2 - Boletin de la Sociedad Espanola de Matematica Aplicada
DA - 2006///
PY - 2006///
VL - 34
SP - 191–196
ER -
TY - JOUR
TI - Combinatorial secant varieties.
AU - Sturmfels, Bernd
AU - Sullivant, Seth
T2 - Quarterly Journal of Pure and Applied Mathematics
DA - 2006///
PY - 2006///
VL - 2
SP - 285-309
ER -
TY - BOOK
TI - A Theoretical Introduction to Numerical Analysis
AU - Ryaben’kii, V.S.
AU - Tsynkov, S.V.
AB - PREFACE ACKNOWLEDGMENTS INTRODUCTION Discretization Conditioning Error On Methods of Computation INTERPOLATION OF FUNCTIONS. QUADRATURES ALGEBRAIC INTERPOLATION Existence and Uniqueness of Interpolating Polynomial Classical Piecewise Polynomial Interpolation Smooth Piecewise Polynomial Interpolation (Splines) Interpolation of Functions of Two Variables TRIGONOMETRIC INTERPOLATION Interpolation of Periodic Functions Interpolation of Functions on an Interval. Relation between Algebraic and Trigonometric Interpolation COMPUTATION OF DEFINITE INTEGRALS. QUADRATURES Trapezoidal Rule, Simpson's Formula, and the Like Quadrature Formulae with No Saturation. Gaussian Quadratures Improper Integrals. Combination of Numerical and Analytical Methods Multiple Integrals SYSTEMS OF SCALAR EQUATIONS SYSTEMS OF LINEAR ALGEBRAIC EQUATIONS: DIRECT METHODS Different Forms of Consistent Linear Systems Linear Spaces, Norms, and Operators Conditioning of Linear Systems Gaussian Elimination and Its Tri-Diagonal Version Minimization of Quadratic Functions and Its Relation to Linear Systems The Method of Conjugate Gradients Finite Fourier Series ITERATIVE METHODS FOR SOLVING LINEAR SYSTEMS Richardson Iterations and the Like Chebyshev Iterations and Conjugate Gradients Krylov Subspace Iterations Multigrid Iterations OVERDETERMINED LINEAR SYSTEMS. THE METHOD OF LEAST SQUARES Examples of Problems that Result in Overdetermined Systems Weak Solutions of Full Rank Systems. QR Factorization Rank Deficient Systems. Singular Value Decomposition NUMERICAL SOLUTION OF NONLINEAR EQUATIONS AND SYSTEMS Commonly Used Methods of Rootfinding Fixed Point Iterations Newton's Method THE METHOD OF FINITE DIFFERENCES FOR THE NUMERICAL SOLUTION OF DIFFERENTIAL EQUATIONS NUMERCAL SOLUTION OF ORDINARY DIFFERENTIAL EQUATIONS Examples of Finite-Difference Schemes. Convergence Approximation of Continuous Problem by a Difference Scheme. Consistency Stability of Finite-Difference Schemes The Runge-Kutta Methods Solution of Boundary Value Problems Saturation of Finite-Difference Methods The Notion of Spectral Methods FINITE-DIFFERENCE SCHEMES FOR PARTIAL DIFFERENTIAL EQUATIONS Key Definitions and Illustrating Examples Construction of Consistent Difference Schemes Spectral Stability Criterion for Finite-Difference Cauchy Problems Stability for Problems with Variable Coefficients Stability for Initial Boundary Value Problems Explicit and Implicit Schemes for the Heat Equation DISCONTINUOUS SOLUTIONS AND METHODS OF THEIR COMPUTATION Differential Form of an Integral Conservation Law Construction of Difference Schemes DISCRETE METHODS FOR ELLIPTIC PROBLEMS A Simple Finite-Difference Scheme. The Maximum Principle The Notion of Finite Elements. Ritz and Galerkin Approximations THE METHODS OF BOUNDARY EQUATIONS FOR THE NUMERICAL SOLUTION OF BOUNDARY VALUE PROBLEMS BOUNDARY INTEGRAL EQUATIONS AND THE METHOD OF BOUNDARY ELEMENTS Reduction of Boundary Value Problems to Integral Equations Discretization of Integral Equations and Boundary Elements The Range of Applicability for Boundary Elements BOUNDARY EQUATIONS WITH PROJECTIONS AND THE METHOD OF DIFFERENCE POTENTIALS Formulation of Model Problems Difference Potentials Solution of Model Problems LIST OF FIGURES REFERENCED BOOKS REFERENCED JOURNAL ARTICLES INDEX
DA - 2006/11/2/
PY - 2006/11/2/
DO - 10.1201/9781420011166
SP - 537
PB - Chapman and Hall/CRC
SN - 9781420011166
UR - http://dx.doi.org/10.1201/9781420011166
ER -
TY - JOUR
TI - Cambrian lattices
AU - Reading, Nathan
T2 - Advances in Mathematics
AB - For an arbitrary finite Coxeter group W, we define the family of Cambrian lattices for W as quotients of the weak order on W with respect to certain lattice congruences. We associate to each Cambrian lattice a complete fan, which we conjecture is the normal fan of a polytope combinatorially isomorphic to the generalized associahedron for W. In types A and B we obtain, by means of a fiber-polytope construction, combinatorial realizations of the Cambrian lattices in terms of triangulations and in terms of permutations. Using this combinatorial information, we prove in types A and B that the Cambrian fans are combinatorially isomorphic to the normal fans of the generalized associahedra and that one of the Cambrian fans is linearly isomorphic to Fomin and Zelevinsky's construction of the normal fan as a “cluster fan.” Our construction does not require a crystallographic Coxeter group and therefore suggests a definition, at least on the level of cellular spheres, of a generalized associahedron for any finite Coxeter group. The Tamari lattice is one of the Cambrian lattices of type A, and two “Tamari” lattices in type B are identified and characterized in terms of signed pattern avoidance. We also show that open intervals in Cambrian lattices are either contractible or homotopy equivalent to spheres.
DA - 2006/10//
PY - 2006/10//
DO - 10.1016/j.aim.2005.07.010
VL - 205
IS - 2
SP - 313-353
J2 - Advances in Mathematics
LA - en
OP -
SN - 0001-8708
UR - http://dx.doi.org/10.1016/j.aim.2005.07.010
DB - Crossref
KW - cluster
KW - Coxeter group
KW - fiber polytope
KW - generalized associahedron
KW - lattice congruence
KW - lattice quotient
KW - Tamari lattice
ER -
TY - JOUR
TI - Growing surfactant waves in thin liquid films driven by gravity
AU - Witelski, T. P.
AU - Shearer, M.
AU - Levy, R.
T2 - Applied Mathematics Research eXpress
AB - The dynamics of a gravity-driven thin film flow with insoluble surfactant are described in the lubrication approximation by a coupled system of nonlinear PDEs. When the total quantity of surfactant is fixed, a traveling wave solution exists. For the case of constant flux of surfactant from an upstream reservoir, global traveling waves no longer exist as the surfactant accumulates at the leading edge of the thin film profile. The dynamics can be described using matched asymptotic expansions for t → ∞. The solution is constructed from quasistatically evolving traveling waves. The rate of growth of the surfactant profile is shown to be $$O\left(\sqrt{t}\right)$$ and is supported by numerical simulations.
DA - 2006/1/1/
PY - 2006/1/1/
DO - 10.1155/amrx/2006/15487
VL - 1
J2 - Applied Mathematics Research eXpress
LA - en
OP -
SN - 1687-1200 1687-1197
UR - http://dx.doi.org/10.1155/amrx/2006/15487
DB - Crossref
ER -
TY - JOUR
TI - Sequential importance sampling for multiway tables
AU - Chen, Yuguo
AU - Dinwoodie, Ian H.
AU - Sullivant, Seth
T2 - The Annals of Statistics
AB - We describe an algorithm for the sequential sampling of entries in multiway contingency tables with given constraints. The algorithm can be used for computations in exact conditional inference. To justify the algorithm, a theory relates sampling values at each step to properties of the associated toric ideal using computational commutative algebra. In particular, the property of interval cell counts at each step is related to exponents on lead indeterminates of a lexicographic Gröbner basis. Also, the approximation of integer programming by linear programming for sampling is related to initial terms of a toric ideal. We apply the algorithm to examples of contingency tables which appear in the social and medical sciences. The numerical results demonstrate that the theory is applicable and that the algorithm performs well.
DA - 2006/2//
PY - 2006/2//
DO - 10.1214/009053605000000822
VL - 34
IS - 1
SP - 523-545
J2 - Ann. Statist.
LA - en
OP -
SN - 0090-5364
UR - http://dx.doi.org/10.1214/009053605000000822
DB - Crossref
KW - conditional inference
KW - contingency table
KW - exact test
KW - Monte Carlo sequential importance sampling
KW - toric ideal
ER -
TY - JOUR
TI - The space of compatible full conditionals is a unimodular toric variety
AU - Slavkovic, Aleksandra B.
AU - Sullivant, Seth
T2 - Journal of Symbolic Computation
AB - The set of all m -tuples of compatible full conditional distributions on discrete random variables is an algebraic set whose defining ideal is a unimodular toric ideal. We identify the defining polynomials of these ideals with closed walks on a bipartite graph. Our algebraic characterization provides a natural generalization of the requirement that compatible conditionals have identical odds ratios and holds regardless of the patterns of zeros in the conditional arrays.
DA - 2006/2//
PY - 2006/2//
DO - 10.1016/j.jsc.2005.04.006
VL - 41
IS - 2
SP - 196-209
J2 - Journal of Symbolic Computation
LA - en
OP -
SN - 0747-7171
UR - http://dx.doi.org/10.1016/j.jsc.2005.04.006
DB - Crossref
KW - odds ratios
KW - toric ideal
KW - unimodular
ER -
TY - JOUR
TI - Algebraic factor analysis: tetrads, pentads and beyond
AU - Drton, Mathias
AU - Sturmfels, Bernd
AU - Sullivant, Seth
T2 - Probability Theory and Related Fields
AB - Factor analysis refers to a statistical model in which observed variables are conditionally independent given fewer hidden variables, known as factors, and all the random variables follow a multivariate normal distribution. The parameter space of a factor analysis model is a subset of the cone of positive definite matrices. This parameter space is studied from the perspective of computational algebraic geometry. Gr\"obner bases and resultants are applied to compute the ideal of all polynomial functions that vanish on the parameter space. These polynomials, known as model invariants, arise from rank conditions on a symmetric matrix under elimination of the diagonal entries of the matrix. Besides revealing the geometry of the factor analysis model, the model invariants also furnish useful statistics for testing goodness-of-fit.
DA - 2006/11/15/
PY - 2006/11/15/
DO - 10.1007/s00440-006-0033-2
VL - 138
IS - 3-4
SP - 463-493
J2 - Probab. Theory Relat. Fields
LA - en
OP -
SN - 0178-8051 1432-2064
UR - http://dx.doi.org/10.1007/s00440-006-0033-2
DB - Crossref
ER -
TY - JOUR
TI - Polyhedral conditions for the nonexistence of the MLE for hierarchical log-linear models
AU - Eriksson, Nicholas
AU - Fienberg, Stephen E.
AU - Rinaldo, Alessandro
AU - Sullivant, Seth
T2 - Journal of Symbolic Computation
AB - We provide a polyhedral description of the conditions for the existence of the maximum likelihood estimate (MLE) for a hierarchical log-linear model. The MLE exists if and only if the observed margins lie in the relative interior of the marginal cone. Using this description, we give an algorithm for determining if the MLE exists. If the tree width is bounded, the algorithm runs in polynomial time. We also perform a computational study of the case of three random variables under the no three-factor effect model.
DA - 2006/2//
PY - 2006/2//
DO - 10.1016/j.jsc.2005.04.003
VL - 41
IS - 2
SP - 222-233
J2 - Journal of Symbolic Computation
LA - en
OP -
SN - 0747-7171
UR - http://dx.doi.org/10.1016/j.jsc.2005.04.003
DB - Crossref
KW - maximum likelihood estimate (MLE)
KW - marginal cone
KW - tree width
KW - collapsing
ER -
TY - JOUR
TI - Compressed polytopes and statistical disclosure limitation
AU - Sullivant, Seth
T2 - Tohoku Mathematical Journal
AB - We provide a characterization of the compressed lattice polytopes in terms of their facet defining inequalities and prove that every compressed lattice polytope is affinely isomorphic to a 0/1-polytope. As an application, we characterize those graphs whose cut polytopes are compressed and discuss consequences for studying linear programming relaxations in statistical disclosure limitation.
DA - 2006/9//
PY - 2006/9//
DO - 10.2748/tmj/1163775139
VL - 58
IS - 3
SP - 433-445
J2 - Tohoku Math. J.
LA - en
OP -
SN - 0040-8735
UR - http://dx.doi.org/10.2748/tmj/1163775139
DB - Crossref
KW - compressed polytope
KW - disclosure limitation
KW - algebraic statistics
KW - integer programming
KW - cut polytope
ER -
TY - JOUR
TI - Theory of reproducing systems on locally compact Abelian groups
AU - Kutyniok, G.
AU - Labate, D.
T2 - Colloquium Mathematicum
AB - A *reproducing system* is a countable collection of functions $\{\phi_j: j \in {\cal J}\}$ such that a general function $f$ can be decomposed as $f = \sum_{j \in {\cal J}} c_j(f) \, \phi_j$, with some control on the analyzing coefficients $c_j(f)$. S
DA - 2006///
PY - 2006///
DO - 10.4064/cm106-2-3
VL - 106
SP - 197-220
ER -
TY - CHAP
TI - The theory of wavelets with composite dilations
AU - Guo, K.
AU - Labate, D.
AU - Lim, W.
AU - Weiss, G.
AU - Wilson, E.
T2 - Harmonic analysis and applications
AB - A wavelet with composite dilations is a function generating an orthonormal basis or a Parseval frame for L 2(ℝn) under the action of lattice translations and dilations by products of elements drawn from non-commuting sets of matrices A and B. Typically, the members of B are matrices whose eigenvalues have magnitude one, while the members of A are matrices expanding on a proper subspace of ℝn. The theory of these systems generalizes the classical theory of wavelets and provides a simple and flexible framework for the construction of orthonormal bases and related systems that exhibit a number of geometric features of great potential in applications. For example, composite wavelets have the ability to produce “long and narrow” window functions, with various orientations, well-suited to applications in image processing.
PY - 2006///
DO - 10.1007/0-8176-4504-7_11
SP - 231-249
PB - Boston: Birkhauser
SN - 0817637788
ER -
TY - JOUR
TI - The problem of active noise shielding in composite domains
AU - Ryaben'kii, V. S.
AU - Utyuzhnikov, S. V.
AU - Tsynkov, Semyon
T2 - Doklady. Mathematics
DA - 2006///
PY - 2006///
DO - 10.1134/S106456240606007X
VL - 74
IS - 3
SP - 812–814
ER -
TY - JOUR
TI - Electromagnetic inverse problems involving distributions of dielectric mechanisms and parameters
AU - Banks, H. T.
AU - Gibson, N. L.
T2 - QUARTERLY OF APPLIED MATHEMATICS
AB - We consider electromagnetic interrogation problems for complex materials involving distributions of polarization mechanisms and also distributions for the parameters in these mechanisms. A theoretical and computational framework for such problems is given. Computational results for specific problems with multiple Debye mechanisms are given in the case of discrete, uniform, log-normal, and log-bi-Gaussian distributions.
DA - 2006/12//
PY - 2006/12//
DO - 10.1090/S0033-569X-06-01036-X
VL - 64
IS - 4
SP - 749-795
SN - 1552-4485
KW - electromagnetic interrogation
KW - pulsed antenna source microwaves
KW - inverse problems
KW - complex dielectric materials
KW - distributions of relaxation parameters and mechanisms
ER -
TY - JOUR
TI - Spatially distributed stochastic systems: Equation-free and equation-assisted preconditioned computations
AU - Qiao, Liang
AU - Erban, Radek
AU - Kelley, C. T.
AU - Kevrekidis, Ioannis G.
T2 - JOURNAL OF CHEMICAL PHYSICS
AB - Spatially distributed problems are often approximately modeled in terms of partial differential equations (PDEs) for appropriate coarse-grained quantities (e.g., concentrations). The derivation of accurate such PDEs starting from finer scale, atomistic models, and using suitable averaging is often a challenging task; approximate PDEs are typically obtained through mathematical closure procedures (e.g., mean field approximations). In this paper, we show how such approximate macroscopic PDEs can be exploited in constructing preconditioners to accelerate stochastic computations for spatially distributed particle-based process models. We illustrate how such preconditioning can improve the convergence of equation-free coarse-grained methods based on coarse timesteppers. Our model problem is a stochastic reaction-diffusion model capable of exhibiting Turing instabilities.
DA - 2006/11/28/
PY - 2006/11/28/
DO - 10.1063/1.2372492
VL - 125
IS - 20
SP -
SN - 1089-7690
ER -
TY - JOUR
TI - Simulated physical mechanisms associated with climate variability over Lake Victoria basin in East Africa
AU - Anyah, Richard O.
AU - Semazzi, Fredrick H. M.
AU - Xie, Lian
T2 - MONTHLY WEATHER REVIEW
AB - Abstract A fully coupled regional climate, 3D lake modeling system is used to investigate the physical mechanisms associated with the multiscale variability of the Lake Victoria basin climate. To examine the relative influence of different processes on the lake basin climate, a suite of model experiments were performed by smoothing topography around the lake basin, altering lake surface characteristics, and reducing or increasing the amount of large-scale moisture advected into the lake region through the four lateral boundaries of the model domain. Simulated monthly mean rainfall over the basin is comparable to the satellite (Tropical Rainfall Measuring Mission) estimates. Peaks between midnight and early morning hours characterize the simulated diurnal variability of rainfall over the four quadrants of the lake, consistent with satellite estimates, although the simulated peaks occur a little earlier. It is evident in the simulations with smoothed topography that the upslope/downslope flow generated by the mountains east of the lake and the land–lake breeze circulations play important roles in influencing the intensity, the location of lake/land breeze fronts, and the horizontal extent of the land–lake breeze circulation, as well as lake basin precipitation. When the lake surface is replaced with marsh (water hyacinth), the late night and early morning rainfall maximum located over the western sector of the lake is dramatically reduced. Our simulations also indicate that large-scale moisture transported via the prevailing easterly trades enhances lake basin precipitation significantly. This is in contrast to the notion advanced in some of the previous studies that Lake Victoria generates its own climate (rainfall) through precipitation–evaporation–reprecipitation recycling only.
DA - 2006/12//
PY - 2006/12//
DO - 10.1175/MWR3266.1
VL - 134
IS - 12
SP - 3588-3609
SN - 1520-0493
ER -
TY - JOUR
TI - Potential individual versus simultaneous climate change effects on soybean (C-3) and maize (C-4) crops: An agrotechnology model based study
AU - Mera, Roberto J.
AU - Niyogi, Dev
AU - Buol, Gregory S.
AU - Wilkerson, Gail G.
AU - Semazzi, Fredrick H. M.
T2 - GLOBAL AND PLANETARY CHANGE
AB - Landuse/landcover change induced effects on regional weather and climate patterns and the associated plant response or agricultural productivity are coupled processes. Some of the basic responses to climate change can be detected via changes in radiation (R), precipitation (P), and temperature (T). Past studies indicate that each of these three variables can affect LCLUC response and the agricultural productivity. This study seeks to address the following question: What is the effect of individual versus simultaneous changes in R, P, and T on plant response such as crop yields in a C3 and a C4 plant? This question is addressed by conducting model experiments for soybean (C3) and maize (C4) crops using the DSSAT: Decision Support System for Agrotechnology Transfer, CROPGRO (soybean), and CERES-Maize (maize) models. These models were configured over an agricultural experiment station in Clayton, NC [35.65°N, 78.5°W]. Observed weather and field conditions corresponding to 1998 were used as the control. In the first set of experiments, the CROPGRO (soybean) and CERES-Maize (maize) responses to individual changes in R and P (25%, 50%, 75%, 150%) and T (± 1, ± 2 °C) with respect to control were studied. In the second set, R, P, and T were simultaneously changed by 50%, 150%, and ± 2 °C, and the interactions and direct effects of individual versus simultaneous variable changes were analyzed. For the model setting and the prescribed environmental changes, results from the first set of experiments indicate: (i) precipitation changes were most sensitive and directly affected yield and water loss due to evapotranspiration; (ii) radiation changes had a non-linear effect and were not as prominent as precipitation changes; (iii) temperature had a limited impact and the response was non-linear; (iv) soybeans and maize responded differently for R, P, and T, with maize being more sensitive. The results from the second set of experiments indicate that simultaneous change analyses do not necessarily agree with those from individual changes, particularly for temperature changes. Our analysis indicates that for the changing climate, precipitation (hydrological), temperature, and radiative feedbacks show a non-linear effect on yield. Study results also indicate that for studying the feedback between the land surface and the atmospheric changes, (i) there is a need for performing simultaneous parameter changes in the response assessment of cropping patterns and crop yield based on ensembles of projected climate change, and (ii) C3 crops are generally considered more sensitive than C4; however, the temperature–radiation related changes shown in this study also effected significant changes in C4 crops. Future studies assessing LCLUC impacts, including those from agricultural cropping patterns and other LCULC–climate couplings, should advance beyond the sensitivity mode and consider multivariable, ensemble approaches to identify the vulnerability and feedbacks in estimating climate-related impacts.
DA - 2006/11//
PY - 2006/11//
DO - 10.1016/j.gloplacha.2005.11.003
VL - 54
IS - 1-2
SP - 163-182
SN - 1872-6364
KW - land surface response
KW - climate change impacts
KW - crop yield
KW - soybeans
KW - maize
KW - crop models
KW - evapotranspiration
ER -
TY - JOUR
TI - On the computation of steady hopper flows III: Model comparisons
AU - Gremaud, Pierre A.
AU - Matthews, John V.
AU - Schaeffer, David G.
T2 - JOURNAL OF COMPUTATIONAL PHYSICS
AB - Gravity flows of granular materials through hoppers are considered. For hoppers shaped as general nonaxisymmetric cones, i.e., “pyramids”, the flow inherits some simplified features from the geometry: similarity solutions can be constructed. Using two different plasticity laws, namely Matsuoka–Nakai and von Mises, those solutions are obtained by solving first-order nonlinear partial differential algebraic systems for stresses, velocities, and a plasticity function. A pseudospectral discretization is applied to both models and the resulting flow fields are examined. Some similarities are found, but important differences appear, especially with regard to velocities near the wall and normal wall stresses. Preliminary comparisons with recent experiments [J.F. Wambaugh, R.P. Behringer, Asymmetry-induced circulation in granular hopper flows, in: R. Garcia-Rojo, H.J. Herrmann, S. McNamara (Eds.), Powders and Grains, 2005, pp. 915–918] based on the present results indicate that for slow granular flows the lesser known Matsuoka–Nakai plasticity law yields better results than more common models based on a von Mises criterion.
DA - 2006/11/20/
PY - 2006/11/20/
DO - 10.1016/j.jcp.2006.03.032
VL - 219
IS - 1
SP - 443-454
SN - 0021-9991
KW - granular
KW - similarity
KW - spectral
KW - plasticity
ER -
TY - JOUR
TI - Google's PageRank - The Math behind the search engine
AU - Wills, Rebecca S.
T2 - MATHEMATICAL INTELLIGENCER
DA - 2006///
PY - 2006///
DO - 10.1007/BF02984696
VL - 28
IS - 4
SP - 6-11
SN - 0343-6993
ER -
TY - JOUR
TI - Globally attracting attenuant versus resonant cycles in periodic compensatory Leslie models
AU - Franke, John E.
AU - Yakubu, Abdul-Aziz
T2 - MATHEMATICAL BIOSCIENCES
AB - We use a periodically forced density-dependent compensatory Leslie model to study the combined effects of environmental fluctuations and age-structure on pioneer populations. In constant environments, the models have globally attracting positive fixed points. However, with the advent of periodic forcing, the models have globally attracting cycles. We derive conditions under which the cycle is attenuant, resonant, and neither attenuant nor resonant. These results show that the response of age-structured populations to environmental fluctuations is a complex function of the compensatory mechanisms at different life-history stages, the fertile age classes and the period of the environment.
DA - 2006/11//
PY - 2006/11//
DO - 10.1016/j.mbs.2006.08.016
VL - 204
IS - 1
SP - 1-20
SN - 0025-5564
ER -
TY - JOUR
TI - Gaussian fluctuations for non-Hermitian random matrix ensembles
AU - Rider, B.
AU - Silverstein, Jack W.
T2 - ANNALS OF PROBABILITY
AB - Consider an ensemble of N×N non-Hermitian matrices in which all entries are independent identically distributed complex random variables of mean zero and absolute mean-square one. If the entry distributions also possess bounded densities and finite (4+ɛ) moments, then Z. D. Bai [Ann. Probab. 25 (1997) 494–529] has shown the ensemble to satisfy the circular law: after scaling by a factor of $1/\sqrt{N}$ and letting N→∞, the empirical measure of the eigenvalues converges weakly to the uniform measure on the unit disk in the complex plane. In this note, we investigate fluctuations from the circular law in a more restrictive class of non-Hermitian matrices for which higher moments of the entries obey a growth condition. The main result is a central limit theorem for linear statistics of type XN(f)=∑k=1Nf(λk) where λ1, λ2, …, λN denote the ensemble eigenvalues and the test function f is analytic on an appropriate domain. The proof is inspired by Bai and Silverstein [Ann. Probab. 32 (2004) 533–605], where the analogous result for random sample covariance matrices is established.
DA - 2006/11//
PY - 2006/11//
DO - 10.1214/009117906000000403
VL - 34
IS - 6
SP - 2118-2143
SN - 0091-1798
KW - random matrix theory
KW - central limit theorem
KW - spectral statistics
ER -
TY - JOUR
TI - A structured erythropoiesis model with nonlinear cell maturation velocity and hormone decay rate
AU - Ackleh, Azmy S.
AU - Deng, Keng
AU - Ito, Kazufumi
AU - Thibodeaux, Jeremy
T2 - MATHEMATICAL BIOSCIENCES
AB - We develop a quasilinear structured model that describes the regulation of erythropoiesis, the process in which red blood cells are developed. In our model, the maturation velocity of precursor cells is assumed to be a function of the erythropoietin hormone, and the decay rate of this hormone is assumed to be a function of the number of precursor cells, unlike other models which assume these parameters to be constants. Existence-uniqueness results are established and convergence of a finite difference approximation to the unique solution of the model is obtained. The finite difference scheme is then used to investigate the effects of these nonlinear parameters on the model dynamics. Our results show that a velocity of precursor cells maturation rate which is an increasing function of the hormone level and a decay rate of the hormone which is an increasing function of the number of precursor cells have a stabilizing effect on the dynamics of the model. While assuming that one parameter is a function and letting the other be a constant stabilizes the oscillations in the mature cells level, the effect is more significant when both parameters are taken to be functions. A study of robustness with respect to the forms of these functions and parameter sensitivity is also carried out.
DA - 2006/11//
PY - 2006/11//
DO - 10.1016/j.mbs.2006.08.004
VL - 204
IS - 1
SP - 21-48
SN - 1879-3134
KW - erythropoiesis
KW - structured model
KW - finite difference approximation
KW - existence-uniqueness
KW - behavior of solutions
ER -
TY - JOUR
TI - The spatiotemporal climate variability over Senegal and its relationship to global climate
AU - Fall, Souleymane
AU - Semazzi, Fredrick H. M.
AU - Dutta, Dev
AU - Niyogi, S.
AU - Anyah, Richard O.
AU - Bowden, Jared
T2 - INTERNATIONAL JOURNAL OF CLIMATOLOGY
AB - Abstract Climate variability over Senegal (West Africa) and its relationship to global climate are examined for the period 1979–1998. Monthly observed rainfall for 20 stations and monthly CPC merged analysis precipitation (CMAP) over Senegal were averaged for the months of June, July, August, and September in order to generate seasonal rainfall totals for the wet season, as well as climate indices averaged over the study period. The spatial distribution patterns are mapped and analyzed using ArcGIS Spatial Analyst. Rainfall distribution over Senegal is dominated by a N–S gradient. To investigate the climate variability over Senegal, an empirical orthogonal function (EOF) analysis is performed for the 1979–1998 period, using rain‐gauge and CMAP rainfall data over Senegal, and CMAP data only for West Africa. The first West African mode agrees strongly with Lamb's rainfall index. One of our major findings is that EOF2 for West Africa is well correlated with EOF1 for rainfall in Senegal. This relationship is supported by the projection of winds on the EOF2 mode by the National Centers for Environmental Prediction (NCEP), as well as the grid‐point correlation between the time series of EOF2 over West Africa and the Atlantic sea‐surface temperature (SST). The typical circulation associated with positive anomalies over Senegal is a moisture convergence, which takes place over the Guinea Gulf, in conjunction with the warm waters in this area. The time series for rainfall over Senegal show positive correlations with the South Atlantic SST. Over the Pacific Ocean, the greatest correlation coefficients (up to −0.72) are observed during the April–July period, which provide a modest possibility of predicting Senegal's rainy season. Given the specificity of coastal West Africa, the traditional indices used by policy makers and end users for the whole Sahel–Sudan region will not work for Senegal. The CMAP data are robust and suitable for analyses over West Africa. On the basis of its reliability, CMAP data has proven to be a good validation for analyses based on rain‐gauge precipitation. Copyright © 2006 Royal Meteorological Society
DA - 2006/11/30/
PY - 2006/11/30/
DO - 10.1002/joc.1355
VL - 26
IS - 14
SP - 2057-2076
SN - 1097-0088
KW - Senegal
KW - West Africa
KW - EOF
KW - GIS
KW - precipitation
KW - temperature
ER -
TY - JOUR
TI - Special issue on accurate solution of eigenvalue problems
AU - Ipsen, Ilse C. F.
T2 - SIAM JOURNAL ON MATRIX ANALYSIS AND APPLICATIONS
AB - The occasion for this special issue is the Fifth International Workshop on Accurate Solution of Eigenvalue Problems, which took place in Hagen, Germany from June 29 to July 1, 2004. This issue provides an outlet for papers from the workshop and recognizes advances in the numerical solution of eigenvalue and related problems. Refined perturbation theory, careful error analyses, and creative algorithms have led to numerical methods that are more accurate and at the same time more efficient. The fourteen papers in this issue are concerned with ordinary eigenvalue problems, eigenvalue problems for matrix polynomials, and singular value decompositions. A common thread is the judicious exploitation of structure in the matrices. Thanks go to Henk van der Vorst, Mitch Chernoff, and the SIAM staff for providing a home for the special issue and to the guest editors Jesse Barlow, Beresford Parlett, and Kresimir Veselić, who saw to the careful and timely review of the papers.
DA - 2006///
PY - 2006///
DO - 10.1137/sjmael0000280000040000ix000001
VL - 28
IS - 4
SP - IX-IX
SN - 0895-4798
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-35348933724&partnerID=MN8TOARS
ER -
TY - JOUR
TI - Parabolic monoids I. Structure
AU - Putcha, Mohan S.
T2 - INTERNATIONAL JOURNAL OF ALGEBRA AND COMPUTATION
AB - We determine the closure of a parabolic subgroup of a reductive group in a reductive monoid. This allows us to define parabolic submonoids of a finite monoid of Lie type. These are analogues of the monoid of block upper triangular matrices. We determine the structure of [Formula: see text]-class of a finite parabolic monoid and show that such a monoid is generated by its unit group and diagonal idempotents.
DA - 2006/12//
PY - 2006/12//
DO - 10.1142/S0218196706003414
VL - 16
IS - 6
SP - 1109-1129
SN - 0218-1967
KW - reductive monoid
KW - parabolic subgroups
KW - J-classes
ER -
TY - BOOK
TI - Google's PageRank and beyond: The science of search engine rankings
AU - Langville, A. N.
AU - Meyer, C. D.
AB - Why doesn't your home page appear on the first page of search results, even when you query your own name? How do other web pages always appear at the top? What creates these powerful rankings? And how? The first book ever about the science of web page rankings, Google's PageRank and Beyond supplies the answers to these and other questions and more. The book serves two very different audiences: the curious science reader and the technical computational reader. The chapters build in mathematical sophistication, so that the first five are accessible to the general academic reader. While other chapters are much more mathematical in nature, each one contains something for both audiences. For example, the authors include entertaining asides such as how search engines make money and how the Great Firewall of China influences research. The book includes an extensive background chapter designed to help readers learn more about the mathematics of search engines, and it contains several MATLAB codes and links to sample web data sets. The philosophy throughout is to encourage readers to experiment with the ideas and algorithms in the text. Any business seriously interested in improving its rankings in the major search engines can benefit from the clear examples, sample code, and list of resources provided. Many illustrative examples and entertaining asides MATLAB code Accessible and informal style Complete and self-contained section for mathematics review
CN - TK5101.884 .L36 2006
DA - 2006///
PY - 2006///
DO - 10.1515/9781400830329
PB - Princeton, NJ: Princeton University Press
SN - 0691122024
ER -
TY - JOUR
TI - Wavelets with composite dilations and their MRA properties
AU - Guo, KH
AU - Labate, D
AU - Lim, WQ
AU - Weiss, G
AU - Wilson, E
T2 - APPLIED AND COMPUTATIONAL HARMONIC ANALYSIS
AB - Affine systems are reproducing systems of the formAC={DcTkψℓ:1⩽ℓ⩽L,k∈Zn,c∈C}, which arise by applying lattice translation operators Tk to one or more generators ψℓ in L2(Rn), followed by the application of dilation operators Dc, associated with a countable set C of invertible matrices. In the wavelet literature, C is usually taken to be the group consisting of all integer powers of a fixed expanding matrix. In this paper, we develop the properties of much more general systems, for which C={c=ab:a∈A,b∈B} where A and B are not necessarily commuting matrix sets. C need not contain a single expanding matrix. Nonetheless, for many choices of A and B, there are wavelet systems with multiresolution properties very similar to those of classical dyadic wavelets. Typically, A expands or contracts only in certain directions, while B acts by volume-preserving maps in transverse directions. Then the resulting wavelets exhibit the geometric properties, e.g., directionality, elongated shapes, scales, oscillations, recently advocated by many authors for multidimensional signal and image processing applications. Our method is a systematic approach to the theory of affine-like systems yielding these and more general features.
DA - 2006/3//
PY - 2006/3//
DO - 10.1016/j.acha.2005.07.002
VL - 20
IS - 2
SP - 202-236
SN - 1096-603X
KW - affine systems
KW - frames
KW - multiwavelets
KW - wavelets
ER -
TY - JOUR
TI - Updating Markov chains with an eye on Google's PageRank
AU - Langville, AN
AU - Meyer, CD
T2 - SIAM JOURNAL ON MATRIX ANALYSIS AND APPLICATIONS
AB - An iterative algorithm based on aggregation/disaggregation principles is presented for updating the stationary distribution of a finite homogeneous irreducible Markov chain. The focus is on large-scale problems of the kind that are characterized by Google's PageRank application, but the algorithm is shown to work well in general contexts. The algorithm is flexible in that it allows for changes to the transition probabilities as well as for the creation or deletion of states. In addition to establishing the rate of convergence, it is proven that the algorithm is globally convergent. Results of numerical experiments are presented.
DA - 2006///
PY - 2006///
DO - 10.1137/040619028
VL - 27
IS - 4
SP - 968-987
SN - 1095-7162
KW - Markov chains
KW - updating
KW - stationary vector
KW - PageRank
KW - stochastic complementation
KW - aggregation/disaggregation
KW - Google
ER -
TY - JOUR
TI - Some remarks on the unified characterization of reproducing systems
AU - Guo, K. H.
AU - Labate, D.
T2 - Collectanea Mathematica (Barcelona, Spain)
DA - 2006///
PY - 2006///
VL - 57
IS - 3
SP - 295-307
ER -
TY - JOUR
TI - Some exact results basic to the linearized Boltzmann equations for a binary mixture of rigid spheres
AU - Garcia, R. D. M.
AU - Siewert, C. E.
T2 - ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND PHYSIK
DA - 2006/11//
PY - 2006/11//
DO - 10.1007/s00033-005-0027-4
VL - 57
IS - 6
SP - 999-1010
SN - 1420-9039
KW - rarefied gas dynamics
KW - binary mixtures
KW - rigid spheres
ER -
TY - JOUR
TI - Reduced order control based on approximate inertial manifolds
AU - Ito, Kazufumi
AU - Kunisch, Karl
T2 - LINEAR ALGEBRA AND ITS APPLICATIONS
AB - A reduced-order method based on approximate inertial manifolds is applied to optimal control problems in infinite-dimensional state spaces. A detailed analysis of the method is given for the linear quadratic regulator problem. The method can also be applied to higher-order control systems with an appropriate decomposition of the state space in terms of slow and fast exponential decay.
DA - 2006/6/1/
PY - 2006/6/1/
DO - 10.1016/j.laa.2004.10.019
VL - 415
IS - 2-3
SP - 531-541
SN - 1873-1856
KW - reduced order method
KW - approximate inertial manifold
KW - LQR-problern
KW - decomposition of state space
KW - infinite-dimensional system
ER -
TY - JOUR
TI - Receding horizon control with incomplete observations
AU - Ito, K
AU - Kunisch, K
T2 - SIAM JOURNAL ON CONTROL AND OPTIMIZATION
AB - To overcome the difficulties related to the computational requirements for solving the optimality systems for optimal control problems on long time horizons, receding horizon techniques provide an important alternative. Rather than finding the optimal solution, a suboptimal control is obtained which achieves the design objective with significantly less computational effort. Moreover, the obtained control can be interpreted as a state feedback control. In this work we continue our analysis of receding horizon strategies, considering the situation when only partial state observations are available. The receding horizon strategy is combined with a state estimator framework. A linearquadratic Gaussian design based on a linearization procedure is proposed and its asymptotic performance is analyzed for systems with nonlinear dynamics. Numerical examples validate the proposed methodology.
DA - 2006///
PY - 2006///
DO - 10.1137/S0363012903437988
VL - 45
IS - 1
SP - 207-225
SN - 1095-7138
KW - receding horizon control
KW - incomplete observations
KW - dynamic compensator
ER -
TY - JOUR
TI - QDENSITY - A Mathematica Quantum Computer simulation
AU - Julia-Diaz, Bruno
AU - Burdis, Joseph M.
AU - Tabakin, Frank
T2 - COMPUTER PHYSICS COMMUNICATIONS
AB - This Mathematica 5.2 package1 is a simulation of a Quantum Computer. The program provides a modular, instructive approach for generating the basic elements that make up a quantum circuit. The main emphasis is on using the density matrix, although an approach using state vectors is also implemented in the package. The package commands are defined in Qdensity.m which contains the tools needed in quantum circuits, e.g., multiqubit kets, projectors, gates, etc. Selected examples of the basic commands are presented here and a tutorial notebook, Tutorial.nb is provided with the package (available on our website) that serves as a full guide to the package. Finally, application is made to a variety of relevant cases, including Teleportation, Quantum Fourier transform, Grover's search and Shor's algorithm, in separate notebooks: QFT.nb, Teleportation.nb, Grover.nb and Shor.nb where each algorithm is explained in detail. Finally, two examples of the construction and manipulation of cluster states, which are part of “one way computing” ideas, are included as an additional tool in the notebook Cluster.nb. A Mathematica palette containing most commands in QDENSITY is also included: QDENSpalette.nb. Title of program: QDENSITY Catalogue identifier: ADXH_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/ADXH_v1_0 Program available from: CPC Program Library, Queen's University of Belfast, N. Ireland Operating systems: Any which supports Mathematica; tested under Microsoft Windows XP, Macintosh OS X, and Linux FC4 Programming language used: Mathematica 5.2 No. of bytes in distributed program, including test data, etc.: 180 581 No. of lines in distributed program, including test data, etc.: 19 382 Distribution format: tar.gz Method of solution: A Mathematica package is provided which contains commands to create and analyze quantum circuits. Several Mathematica notebooks containing relevant examples: Teleportation, Shor's Algorithm and Grover's search are explained in detail. A tutorial, Tutorial.nb is also enclosed.
DA - 2006/6/1/
PY - 2006/6/1/
DO - 10.1016/j.cpc.2005.12.021
VL - 174
IS - 11
SP - 914-934
SN - 1879-2944
KW - analysis and design of quantum circuits
KW - quantum algorithms and quantum clusters
ER -
TY - JOUR
TI - Model development for atomic force microscope stage mechanisms
AU - Smith, Ralph C.
AU - Hatch, Andrew G.
AU - De, Tathagata
AU - Salapaka, Murti V.
AU - Del Rosario, Ricardo C. H.
AU - Raye, Julie K.
T2 - SIAM JOURNAL ON APPLIED MATHEMATICS
AB - In this paper, we develop nonlinear constitutive equations and resulting system models quantifying the nonlinear and hysteretic field‐displacement relations inherent to lead zirconate titanate (PZT) devices employed in atomic force microscope stage mechanisms. We focus specifically on PZT rods utilizing $d_{33}$ motion and PZT shells driven in $d_{31}$ regimes, but the modeling framework is sufficiently general to accommodate a variety of drive geometries. In the first step of the model development, lattice‐level energy relations are combined with stochastic homogenization techniques to construct nonlinear constitutive relations which accommodate the hysteresis inherent to ferroelectric compounds. Second, these constitutive relations are employed in classical rod and shell relations to construct system models appropriate for presently employed nanopositioner designs. The capability of the models for quantifying the frequency‐dependent hysteresis inherent to the PZT stages is illustrated through comparison with experimental data.
DA - 2006///
PY - 2006///
DO - 10.1137/05063307X
VL - 66
IS - 6
SP - 1998-2026
SN - 1095-712X
KW - atomic force microscope
KW - hysteresis model
KW - dynamics
ER -
TY - JOUR
TI - Finite-volume-particle methods for models of transport of pollutant in shallow water
AU - Chertock, Alina
AU - Kurganov, Alexander
AU - Petrova, Guergana
T2 - JOURNAL OF SCIENTIFIC COMPUTING
DA - 2006/6//
PY - 2006/6//
DO - 10.1007/s10915-005-9060-x
VL - 27
IS - 1-3
SP - 189-199
SN - 1573-7691
UR - https://doi-org.prox.lib.ncsu.edu/10.1007/s10915-005-9060-x
KW - Saint-Venant system of shallow water equations
KW - transport of pollutant
KW - finite-volume schemes
KW - particle methods
KW - central-upwind schemes
KW - balance laws
ER -
TY - JOUR
TI - Eigenvalues of large sample covariance matrices of spiked population models
AU - Baik, Jinho
AU - Silverstein, Jack W.
T2 - JOURNAL OF MULTIVARIATE ANALYSIS
AB - We consider a spiked population model, proposed by Johnstone, in which all the population eigenvalues are one except for a few fixed eigenvalues. The question is to determine how the sample eigenvalues depend on the non-unit population ones when both sample size and population size become large. This paper completely determines the almost sure limits of the sample eigenvalues in a spiked model for a general class of samples.
DA - 2006/7//
PY - 2006/7//
DO - 10.1016/j.jmva.2005.08.003
VL - 97
IS - 6
SP - 1382-1408
SN - 0047-259X
KW - eigenvalues
KW - sample covariance matrices
KW - spiked population models
KW - almost sure limits
KW - non-null case
ER -
TY - JOUR
TI - Diffusional anisotropy in collagenous tissues: Fluorescence imaging of continuous point photobleaching
AU - Leddy, Holly A.
AU - Haider, Mansoor A.
AU - Guilak, Farshid
T2 - BIOPHYSICAL JOURNAL
AB - Molecular transport in avascular collagenous tissues such as articular cartilage occurs primarily via diffusion. The presence of ordered structures in the extracellular matrix may influence the local transport of macromolecules, leading to anisotropic diffusion depending on the relative size of the molecule and that of extracellular matrix structures. Here we present what we believe is a novel photobleaching technique for measuring the anisotropic diffusivity of macromolecules in collagenous tissues. We hypothesized that macromolecular diffusion is anisotropic in collagenous tissues, depending on molecular size and the local organization of the collagen structure. A theoretical model and experimental protocol for fluorescence imaging of continuous point photobleaching was developed to measure diffusional anisotropy. Significant anisotropy was observed in highly ordered collagenous tissues such as ligament, with diffusivity ratios >2 along the fiber direction compared to the perpendicular direction. In less-ordered tissues such as articular cartilage, diffusional anisotropy was dependent on site in the tissue and size of the diffusing molecule. Anisotropic diffusion was also dependent on the size of the diffusing molecule, with greatest anisotropy observed for larger molecules. These findings suggest that diffusional transport of macromolecules is anisotropic in collagenous tissues, with higher rates of diffusion along primary orientation of collagen fibers.
DA - 2006/7//
PY - 2006/7//
DO - 10.1529/biophysj.105.075283
VL - 91
IS - 1
SP - 311-316
SN - 1542-0086
ER -
TY - JOUR
TI - Combustion fronts in a porous medium with two layers
AU - Da Mota, J. C.
AU - Schecter, S.
T2 - JOURNAL OF DYNAMICS AND DIFFERENTIAL EQUATIONS
DA - 2006/7//
PY - 2006/7//
DO - 10.1007/s10884-006-9019-0
VL - 18
IS - 3
SP - 615-665
SN - 1572-9222
KW - reaction-diffusion-convection system
KW - traveling wave
KW - nonhyperbolic equilibrium
KW - geometric singular perturbation theory
KW - Melnikov integral
ER -
TY - JOUR
TI - Bruno Buchberger - A life devoted to symbolic computation
AU - Hong, H
AU - Kapur, D
AU - Paule, P
AU - Winkler, F
T2 - JOURNAL OF SYMBOLIC COMPUTATION
DA - 2006///
PY - 2006///
DO - 10.1016/j.jsc.2005.09.005
VL - 41
IS - 3-4
SP - 255-258
SN - 0747-7171
UR - https://doi.org/10.1016/j.jsc.2005.09.005
ER -
TY - JOUR
TI - Asymptotic behavior of Markov semigroups on preduals of von Neumann algebras
AU - Ernel'yanov, EY
AU - Wolff, MPH
T2 - JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS
AB - We develop a new approach for investigation of asymptotic behavior of Markov semigroup on preduals of von Neumann algebras. With using of our technique we establish several results about mean ergodicity, statistical stability, and constrictiviness of Markov semigroups.
DA - 2006/2/15/
PY - 2006/2/15/
DO - 10.1016/j.jmaa.2005.04.016
VL - 314
IS - 2
SP - 749-763
SN - 1096-0813
KW - von neumann algebra
KW - predual
KW - Markov operator
KW - mean ergodicity
KW - statistical stability
KW - domination
ER -
TY - JOUR
TI - Additive scaling and the DIRECT algorithm
AU - Finkel, D. E.
AU - Kelley, C. T.
T2 - JOURNAL OF GLOBAL OPTIMIZATION
DA - 2006/12//
PY - 2006/12//
DO - 10.1007/s10898-006-9029-9
VL - 36
IS - 4
SP - 597-608
SN - 0925-5001
KW - DIRECT
KW - global optimization
KW - additive scaling
ER -
TY - JOUR
TI - A new construction for Hamiltonian BRST operators
AU - Gao, JI
T2 - LETTERS IN MATHEMATICAL PHYSICS
DA - 2006/3//
PY - 2006/3//
DO - 10.1007/s11005-005-0048-0
VL - 75
IS - 3
SP - 213-223
SN - 1573-0530
KW - BRST operator
KW - contracting homotopy
ER -
TY - JOUR
TI - A homogenized energy model for the direct magnetomechanical effect
AU - Smith, Ralph C.
AU - Dapino, Marcelo J.
T2 - IEEE TRANSACTIONS ON MAGNETICS
AB - This paper focuses on the development of a homogenized energy model which quantifies certain facets of the direct magnetomechanical effect. In the first step of the development, Gibbs energy analysis at the lattice level is combined with Boltzmann principles to quantify the local average magnetization as a function of input fields and stresses. A macroscopic magnetization model, which incorporates the effects of polycrystallinity, material nonhomogeneities, stress-dependent interaction fields, and stress-dependent coercive behavior, is constructed through stochastic homogenization techniques based on the tenet that local coercive and interaction fields are manifestations of underlying distributions rather than constants. The resulting framework incorporates previous ferromagnetic hysteresis theory as a special case in the absence of applied stresses. Attributes of the framework are illustrated through comparison with previously published steel and iron data
DA - 2006/8//
PY - 2006/8//
DO - 10.1109/TMAG.2006.875705
VL - 42
IS - 8
SP - 1944-1957
SN - 0018-9464
KW - ferromagnetic materials
KW - magnetic hysteresis
KW - magnetornechanical effects
KW - magnetostrictive devices
KW - modeling
KW - nonlinear magnetics
ER -
TY - JOUR
TI - Time-delayed finite difference reaction-diffusion systems with nonquasimonotone functions
AU - Wang, YM
AU - Pao, CV
T2 - NUMERISCHE MATHEMATIK
DA - 2006/5//
PY - 2006/5//
DO - 10.1007/s00211-006-0685-y
VL - 103
IS - 3
SP - 485-513
SN - 0945-3245
KW - reaction-diffusion system
KW - finite difference system
KW - monotone iterative method
KW - asymptotic behavior
KW - local and global attractors
ER -
TY - BOOK
TI - The immersed interface method: Numerical solutions of PDEs involving interfaces and irregular domains
AU - Li, Zhilin
AU - Ito, K.
CN - QA374 .L42 2006
DA - 2006///
PY - 2006///
DO - 10.1137/1.9780898717464
PB - Philadelphia: SIAM, Society for Industrial and Applied Mathematics
SN - 0898716098
ER -
TY - JOUR
TI - The Picard iteration and its application
AU - Chen, X
AU - Hartwig, RE
T2 - LINEAR & MULTILINEAR ALGEBRA
AB - The convergence behavior of the Picard iteration Xk+1=AXk+B and the weighted case Yk=Xk/bk is investigated. It is shown that the convergence of both these iterations is related to the so-called effective spectrum of A with respect to some matrix. As an application of our convergence results we discuss the convergence behavior of a sequence of scaled triangular matrices {DNTN }.
DA - 2006/9//
PY - 2006/9//
DO - 10.1080/03081080500209703
VL - 54
IS - 5
SP - 329-341
SN - 0308-1087
KW - Picard iteration
KW - Schur complement
KW - path condition
ER -
TY - JOUR
TI - Preconditioned iterative methods on sparse subspaces
AU - Ito, Kazufumi
AU - Toivanen, Jari
T2 - APPLIED MATHEMATICS LETTERS
AB - When some rows of the system matrix and a preconditioner coincide, preconditioned iterations can be reduced to a sparse subspace. Taking advantage of this property can lead to considerable memory and computational savings. This is particularly useful with the GMRES method. We consider the iterative solution of a discretized partial differential equation on this sparse subspace. With a domain decomposition method and a fictitious domain method the subspace corresponds a small neighborhood of an interface. As numerical examples we solve the Helmholtz equation using a fictitious domain method and an elliptic equation with a jump in the diffusion coefficient using a separable preconditioner.
DA - 2006/11//
PY - 2006/11//
DO - 10.1016/j.aml.2005.11.027
VL - 19
IS - 11
SP - 1191-1197
SN - 0893-9659
KW - subspace iteration
KW - preconditioning
KW - Krylov subspace method
KW - domain decomposition method
KW - fictitious domain method
KW - interface problem
ER -
TY - JOUR
TI - Note on a linear difference equation
AU - Hartwig, RE
T2 - AMERICAN MATHEMATICAL MONTHLY
DA - 2006/3//
PY - 2006/3//
DO - 10.2307/27641892
VL - 113
IS - 3
SP - 250-256
SN - 0002-9890
ER -
TY - BOOK
TI - Modeling and simulation in Scilab/Scicos
AU - Campbell, S.
AU - Chancelier, J.-P.
AU - Nikoukhah, R.
DA - 2006///
PY - 2006///
PB - New York: Springer
SN - 0387278028
ER -
TY - JOUR
TI - Material surface design to counter electromagnetic interrogation of targets
AU - Banks, HT
AU - Ito, K
AU - Kepler, GM
AU - Toivanen, JA
T2 - SIAM JOURNAL ON APPLIED MATHEMATICS
AB - Utilization of controllable ferromagnetic layers coating a conducting object to provide an attenuation capability against electromagnetic interrogation is discussed. The problem is formulated as a differential game and/or a robust optimization. The scattered field due to interrogation can be attenuated with the assumption of an uncertainty in the interrogation wave numbers. The controllable layer composed of ferromagnetic materials [H. How and C. Vittoria, Implementation of Microwave Active Nulling, private communication; H. How and C. Vittoria, IEEE Trans. Microwave Theory Tech., 52 (2004), pp. 2177-2182] is incorporated in a mathematical formulation based on the time-harmonic Maxwell equation. Fresnel's law for the reflectance index is extended to the electromagnetic propagation in anisotropic composite layers of ferromagnetic and electronic devices and is used to demonstrate feasibility of control of reflections. Our methodology is also tested for a nonplanar geometry of the conducting object (an NACA airfoil) in which we report our findings in the form of reduced radar cross sections (RCS)\@.
DA - 2006///
PY - 2006///
DO - 10.1137/040621430
VL - 66
IS - 3
SP - 1027-1049
SN - 1095-712X
KW - electromagnetic
KW - inverse scattering
KW - attenuation
ER -
TY - JOUR
TI - Homogenization of periodically varying coefficients in electromagnetic materials
AU - Banks, H. T.
AU - Bokil, V. A.
AU - Cioranescu, D.
AU - Gibson, N. L.
AU - Griso, G.
AU - Miara, B.
T2 - JOURNAL OF SCIENTIFIC COMPUTING
AB - In this paper, we employ the periodic unfolding method for simulating the electromagnetic field in a composite material exhibiting heterogeneous microstructures which are described by spatially periodic parameters. We consider cell problems to calculate the effective parameters for a Debye dielectric medium in the case of a circular microstructure in two dimensions. We assume that the composite materials are quasi-static in nature, i.e., the wavelength of the electromagnetic field is much larger than the relevant dimensions of the microstructure.
DA - 2006/9//
PY - 2006/9//
DO - 10.1007/s10915-006-9091-y
VL - 28
IS - 2-3
SP - 191-221
SN - 1573-7691
KW - Homogenization
KW - Maxwell's equations
KW - debye dielectric materials
KW - pulsed antenna source microwaves
ER -
TY - JOUR
TI - Efficient implementation algorithms for homogenized energy models
AU - Braun, Thomas R.
AU - Smith, Ralph C.
T2 - CONTINUUM MECHANICS AND THERMODYNAMICS
AB - The homogenized energy framework quantifying ferroelectric and ferromagnetic hysteresis is increasingly used for comprehensive material characterization and model-based control design. For operating regimes in which thermal relaxation mechanisms and stress-dependencies are negligible, existing algorithms are sufficiently efficient to permit device optimization and the potential for real-time control implementation. In this paper, we develop algorithms employing lookup tables which permit the high speed implementation of formulations which incorporate relaxation mechanisms and electromechanical coupling. Aspects of the algorithms are illustrated through comparison with experimental data.
DA - 2006/9//
PY - 2006/9//
DO - 10.1007/s00161-006-0015-8
VL - 18
IS - 3-4
SP - 137-155
SN - 0935-1175
ER -
TY - JOUR
TI - Convergence analysis of a PageRank updating algorithm by Langville and Meyer
AU - Ipsen, ICF
AU - Kirkland, S
T2 - SIAM JOURNAL ON MATRIX ANALYSIS AND APPLICATIONS
AB - The PageRank updating algorithm proposed by Langville and Meyer is a special case of an iterative aggregation/disaggregation (SIAD) method for computing stationary distributions of very large Markov chains. It is designed, in particular, to speed up the determination of PageRank, which is used by the search engine Google in the ranking of web pages. In this paper the convergence, in exact arithmetic, of the SIAD method is analyzed. The SIAD method is expressed as the power method preconditioned by a partial LU factorization. This leads to a simple derivation of the asymptotic convergence rate of the SIAD method. It is known that the power method applied to the Google matrix always converges, and we show that the asymptotic convergence rate of the SIAD method is at least as good as that of the power method. Furthermore, by exploiting the hyperlink structure of the web it can be shown that the asymptotic convergence rate of the SIAD method applied to the Google matrix can be made strictly faster than that of the power method.
DA - 2006///
PY - 2006///
DO - 10.1137/S0895479804439808
VL - 27
IS - 4
SP - 952-967
SN - 1095-7162
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33646455491&partnerID=MN8TOARS
KW - Google
KW - PageRank
KW - Markov chain
KW - power method
KW - stochastic complement
KW - aggregation/disaggregation
ER -
TY - JOUR
TI - Construction and experimental implementation of a model-based inverse filter to attenuate hysteresis in ferroelectric transducers
AU - Hatch, Andrew G.
AU - Smith, Ralph C.
AU - De, Tathagata
AU - Salapaka, Murti V.
T2 - IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY
AB - Hysteresis and constitutive nonlinearities are inherent properties of ferroelectric transducer materials due to the noncentrosymmetric nature of the compounds. In certain regimes, these effects can be mitigated through restricted input fields, charge- or current-controlled amplifiers, or feedback designs. For general operating conditions, however, these properties must be accommodated in models, transducer designs, and model-based control algorithms to achieve the novel capabilities provided by the compounds. In this paper, we illustrate the construction of inverse filters, based on homogenized energy models, which can be used to approximately linearize the piezoceramic transducer behavior for linear design and control implementation. Attributes of the inverse filters are illustrated through numerical examples and experimental open loop control implementation for an atomic force microscope stage
DA - 2006/11//
PY - 2006/11//
DO - 10.1109/TCST.2006.883195
VL - 14
IS - 6
SP - 1058-1069
SN - 1558-0865
KW - atomic force microscopy (AFM)
KW - control systems
KW - dielectric hysteresis
KW - ferroelectric devices
KW - modeling
ER -
TY - JOUR
TI - Computational study of fast methods for the eikonal equation
AU - Gremaud, PA
AU - Kuster, CM
T2 - SIAM JOURNAL ON SCIENTIFIC COMPUTING
AB - A computational study of the fast marching and the fast sweeping methods for the eikonal equation is given. It is stressed that both algorithms should be considered as "direct" (as opposed to iterative) methods. On realistic grids, fast sweeping is faster than fast marching for problems with simple geometry. For strongly nonuniform problems and/or complex geometry, the situation may be reversed. Finally, fully second order generalizations of methods of this type for problems with obstacles are proposed and implemented.
DA - 2006///
PY - 2006///
DO - 10.1137/040605655
VL - 27
IS - 6
SP - 1803-1816
SN - 1064-8275
KW - Hamilton-Jacobi
KW - eikonal
KW - viscosity solution
KW - fast marching
KW - fast sweeping
ER -
TY - JOUR
TI - An instability of the Godunov scheme
AU - Bressan, Alberto
AU - Jenssen, Helge Kristian
AU - Baiti, Paolo
T2 - COMMUNICATIONS ON PURE AND APPLIED MATHEMATICS
AB - We construct a solution to a 2 × 2 strictly hyperbolic system of conservation laws, showing that the Godunov scheme [13] can produce an arbitrarily large amount of oscillations. This happens when the speed of a shock is close to rational, inducing a resonance with the grid. Differently from the Glimm scheme or the vanishing-viscosity method, for systems of conservation laws our counterexample indicates that no a priori BV bounds or L1-stability estimates can in general be valid for finite difference schemes. © 2006 Wiley Periodicals, Inc.
DA - 2006/11//
PY - 2006/11//
DO - 10.1002/cpa.20141
VL - 59
IS - 11
SP - 1604-1638
SN - 0010-3640
ER -
TY - JOUR
TI - An augmented approach for the pressure boundary condition in a Stokes flow
AU - Li, Z. L.
AU - Wan, X. H.
AU - Ito, K.
AU - Lubkin, S. R.
T2 - Communications in Computational Physics
DA - 2006///
PY - 2006///
VL - 1
IS - 5
SP - 874-885
UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000241516600006&KeyUID=WOS:000241516600006
ER -
TY - JOUR
TI - A state-dependent Riccati equation-based estimator approach for HIV feedback control
AU - Banks, HT
AU - Kwon, HD
AU - Toivanen, JA
AU - Tran, HT
T2 - OPTIMAL CONTROL APPLICATIONS & METHODS
AB - Abstract We consider optimal dynamic multidrug therapies for human immunodeficiency virus (HIV) type 1 infection. In this context, we describe an optimal tracking problem attempting to drive the states of the system to a stationary state in which the viral load is low and the immune response is strong. We consider optimal feedback control with full‐state as well as with partial‐state measurements. In the case of partial‐state measurement, a state estimator is constructed based on viral load and T‐cell count measurements. We demonstrate by numerical simulations that by anticipation of and response to the disease progression, the dynamic multidrug strategy reduces the viral load, increases the CD4+ T‐cell count and improves the immune response. Copyright © 2006 John Wiley & Sons, Ltd.
DA - 2006///
PY - 2006///
DO - 10.1002/oca.773
VL - 27
IS - 2
SP - 93-121
SN - 1099-1514
KW - multidrug therapies
KW - feedback control
KW - estimator
KW - HIV model
KW - SDRE
ER -
TY - JOUR
TI - A reordering for the PageRank problem
AU - Langville, AN
AU - Meyer, CD
T2 - SIAM JOURNAL ON SCIENTIFIC COMPUTING
AB - We describe a reordering particularly suited to the PageRank problem, which reduces the computation of the PageRank vector to that of solving a much smaller system and then using forward substitution to get the full solution vector. We compare the theoretical rates of convergence of the original PageRank algorithm to that of the new reordered PageRank algorithm, showing that the new algorithm can do no worse than the original algorithm. We present results of an experimental comparison on five datasets, which demonstrate that the reordered PageRank algorithm can provide a speedup of as much as a factor of 6. We also note potential additional benefits that result from the proposed reordering.
DA - 2006///
PY - 2006///
DO - 10.1137/040607551
VL - 27
IS - 6
SP - 2112-2120
SN - 1095-7197
KW - Markov chains
KW - PageRank
KW - reorderings
KW - power method
KW - convergence
KW - stationary vector
KW - dangling nodes
ER -
TY - JOUR
TI - A homogenization model for laser beam-induced current imaging and detection of non-uniformities in semiconductor arrays
AU - Fang, Weifu
AU - Ito, Kazufumi
AU - Redfern, David A.
T2 - JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS
AB - We present an approximate model for laser beam-induced current (LBIC) imaging of arrays of semiconductor devices based on homogenization. LBIC is a non-destructive technique useful for the characterization and quality control of semiconductor focal plane arrays, a key component in modern imaging systems. The model provides not only an efficient alternative for LBIC image simulation of large uniform arrays, but also an effective method for detection of non-uniformities among arrays. Numerical examples are presented to illustrate the effectiveness of this method in detecting array non-uniformities due to variations in dislocation/size or doping level among p–n junction diodes.
DA - 2006/10/1/
PY - 2006/10/1/
DO - 10.1016/j.cam.2005.08.007
VL - 194
IS - 2
SP - 395-408
SN - 1879-1778
KW - semiconductor arrays
KW - laser beam-induced current
KW - LBIC
KW - homogenization
KW - inverse problems
ER -
TY - JOUR
TI - The pericellular matrix as a transducer of biomechanical and biochemical signals in articular cartilage
AU - Guilak, Farshid
AU - Alexopoulos, Leonidas G.
AU - Upton, Maureen L.
AU - Youn, Inchan
AU - Choi, Jae Bong
AU - Cao, Li
AU - Setton, Lori A.
AU - Haider, Mansoor A.
T2 - SKELETAL DEVELOPMENT AND REMODELING IN HEALTH, DISEASE, AND AGING
AB - The pericellular matrix (PCM) is a narrow tissue region surrounding chondrocytes in articular cartilage, which together with the enclosed cell(s) has been termed the "chondron." While the function of this region is not fully understood, it is hypothesized to have important biological and biomechanical functions. In this article, we review a number of studies that have investigated the structure, composition, mechanical properties, and biomechanical role of the chondrocyte PCM. This region has been shown to be rich in proteoglycans (e.g., aggrecan, hyaluronan, and decorin), collagen (types II, VI, and IX), and fibronectin, but is defined primarily by the presence of type VI collagen as compared to the extracellular matrix (ECM). Direct measures of PCM properties via micropipette aspiration of isolated chondrons have shown that the PCM has distinct mechanical properties as compared to the cell or ECM. A number of theoretical and experimental studies suggest that the PCM plays an important role in regulating the microenvironment of the chondrocyte. Parametric studies of cell-matrix interactions suggest that the presence of the PCM significantly affects the micromechanical environment of the chondrocyte in a zone-dependent manner. These findings provide support for a potential biomechanical function of the chondrocyte PCM, and furthermore, suggest that changes in the PCM and ECM properties that occur with osteoarthritis may significantly alter the stress-strain and fluid environments of the chondrocytes. An improved understanding of the structure and function of the PCM may provide new insights into the mechanisms that regulate chondrocyte physiology in health and disease.
DA - 2006///
PY - 2006///
DO - 10.1196/annals.1346.011
VL - 1068
IS - 1068
SP - 498-512
SN - 0077-8923
KW - articular cartilage
KW - chondron
KW - chondrocyte
KW - osteoarthritis
KW - collagen
KW - proteoglycan
KW - collagen VI
ER -
TY - JOUR
TI - Semi-mechanistic partial buffer approach to modeling pH, the buffer properties, and the distribution of ionic species in complex solutions
AU - Dougherty, Daniel P.
AU - Ramos Da Conceicao Neta, Edith
AU - McFeeters, Roger F.
AU - Lubkin, Sharon R.
AU - Breidt, Frederick, Jr.
T2 - JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
AB - In many biological science and food processing applications, it is very important to control or modify pH. However, the complex, unknown composition of biological media and foods often limits the utility of purely theoretical approaches to modeling pH and calculating the distributions of ionizable species. This paper provides general formulas and efficient algorithms for predicting the pH, titration, ionic species concentrations, buffer capacity, and ionic strength of buffer solutions containing both defined and undefined components. A flexible, semi-mechanistic, partial buffering (SMPB) approach is presented that uses local polynomial regression to model the buffering influence of complex or undefined components in a solution, while identified components of known concentration are modeled using expressions based on extensions of the standard acid-base theory. The SMPB method is implemented in a freeware package, (pH)Tools, for use with Matlab. We validated the predictive accuracy of these methods by using strong acid titrations of cucumber slurries to predict the amount of a weak acid required to adjust pH to selected target values.
DA - 2006/8/9/
PY - 2006/8/9/
DO - 10.1021/jf0531508
VL - 54
IS - 16
SP - 6021-6029
SN - 1520-5118
UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000239454700045&KeyUID=WOS:000239454700045
KW - buffer capacity
KW - Cucumis sativus
KW - vegetable
KW - titration
KW - pH prediction
KW - Davies equation
ER -
TY - JOUR
TI - Quantum geometrodynamics of the Bianchi IX cosmological model
AU - Kheyfets, Arkady
AU - Miller, Warner A.
AU - Vaulin, Ruslan
T2 - CLASSICAL AND QUANTUM GRAVITY
AB - The canonical quantum theory of gravity—quantum geometrodynamics (QG)—is applied to the homogeneous Bianchi type IX cosmological model. As a result, a framework for the quantum theory of homogeneous cosmologies is developed. We show that the theory is internally consistent and prove that it possesses the correct classical limit (the theory of general relativity). To emphasize the special role that the constraints play in this new theory, we compare it to the traditional ADM square-root and Wheeler–DeWitt quantization schemes. We show that, unlike traditional approaches, QG leads to a well-defined Schrödinger equation for the wavefunction of the universe that is inherently coupled to the expectation value of the constraint equations. This coupling to the constraints is responsible for the appearance of a coherent spacetime picture. Thus, the physical meaning of the constraints of the theory is quite different from Dirac's interpretation. In light of this distinctive feature of the theory, we re-address the question of the dark energy effects in the Bianchi IX cosmological model for highly non-classical quantum states. We show that, at least for this model, for any choice of the initial wavefunction, quantum corrections will not produce accelerated expansion of the universe.
DA - 2006/7/7/
PY - 2006/7/7/
DO - 10.1088/0264-9381/23/13/003
VL - 23
IS - 13
SP - 4333-4351
SN - 1361-6382
ER -
TY - JOUR
TI - Quantifying the significance of phage attack on starter cultures: a mechanistic model for population dynamics of phage and their hosts isolated from fermenting sauerkraut
AU - Mudgal, P.
AU - Breidt, F., Jr.
AU - Lubkin, S. R.
AU - Sandeep, K. P.
T2 - APPLIED AND ENVIRONMENTAL MICROBIOLOGY
AB - ABSTRACT We investigated the possibility of using starter cultures in sauerkraut fermentation and thereby reducing the quantity of salt used in the process. This, in turn, would reduce the amount of waste salt that would enter in our water resources. Phage, naturally present in sauerkraut fermentation, could potentially affect the starter cultures introduced. Thus, a mechanistic mathematical model was developed to quantify the growth kinetics of the phage and starter cultures. The model was validated by independent experiments with two Leuconostoc mesenteroides strains isolated from sauerkraut and their corresponding phage. Model simulations and experimental evidence showed the presence of phage-resistant cell populations in starter cultures which replaced phage-sensitive cells, even when the initial phage density ( P 0 ) and multiplicity of infection (MOI) were low ( P 0 < 1 × 10 3 PFU/ml; MOI < 10 −4 ) in the MRS media. Based on the results of model simulation and parameter optimization, it was suggested that the kinetic parameters of phage-host interaction, especially the adsorption rate, vary with the initial phage and host densities and with time. The model was validated in MRS broth. Therefore, the effects of heterogeneity and other environmental factors, such as temperature and pH, should be considered to make the model applicable to commercial fermentations.
DA - 2006/6//
PY - 2006/6//
DO - 10.1128/AEM.02429-05
VL - 72
IS - 6
SP - 3908-3915
SN - 1098-5336
UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000238620100013&KeyUID=WOS:000238620100013
ER -
TY - JOUR
TI - Quantifying a possible Miocene phyletic change in Hemipristis (Chondrichthyes) teeth
AU - Chandler, R. E.
AU - Chiswell, K. E.
AU - Faulkner, G. D.
T2 - Palaeontologia Electronica
DA - 2006///
PY - 2006///
VL - 9
IS - 1
ER -
TY - JOUR
TI - Parabolic variational inequalities: The Lagrange multiplier approach
AU - Ito, K
AU - Kunisch, K
T2 - JOURNAL DE MATHEMATIQUES PURES ET APPLIQUEES
AB - Parabolic variational inequalities are discussed and existence and uniqueness of strong as well as weak solutions are established. Our approach is based on a Lagrange multiplier treatment. Existence is obtained as the unique asymptotic limit of solutions to a family of appropriately regularized nonlinear parabolic equations. Two regularization techniques are presented resulting in feasible and unfeasible approximations respectively. Monotonicity results of the regularized solutions and convergence rate estimate are established. The results are applied to the Black–Scholes model for American options. The case of the bilateral constraints is also treated. Numerical results for the Black–Scholes model are presented and prove the practical efficiency of our results. Des inégalités variationnelles paraboliques sont discutées et l'existence et l'unicité des solutions fortes faibles sont établies. Notre approche des solutions utilise une méthode de multiplicateur de Lagrange. L'existence est obtenue comme limite asymptotique unique des solutions à une famille d'équations paraboliques non linéaires convenablement régularisées. Deux techniques de régularisation sont présentées ayant pour résultat des approximations acceptées ou rejetées. Des résultats de monotonie des solutions régularisées et d'évaluation de taux de convergence sont établis. Les résultats sont appliqués au modèle Black–Scholes pour des options américaines. Le cas des contraintes bilatérales est également traité. Des résultats numériques pour le modèle Black–Scholes sont présentés et prouvent l'efficacité pratique de nos techniques.
DA - 2006/3//
PY - 2006/3//
DO - 10.1016/j.matpur.2005.08.005
VL - 85
IS - 3
SP - 415-449
SN - 1776-3371
KW - parabolic variational inequalities
KW - Lagrange multipliers
KW - feasible and unfeasible regularization
KW - Black-Scholes
ER -
TY - JOUR
TI - On a practical implementation of particle methods
AU - Chertock, Alina
AU - Kurganov, Alexander
T2 - APPLIED NUMERICAL MATHEMATICS
AB - This paper is devoted to a practical implementation of deterministic particle methods for solving transport equations with discontinuous coefficients and/or initial data, and related problems. In such methods, the solution is sought in the form of a linear combination of the delta-functions, whose positions and coefficients represent locations and weights of the particles, respectively. The locations and weights of the particles are then evolved in time according to a system of ODEs, obtained from the weak formulation of the transport PDEs. The major theoretical difficulty in solving the resulting system of ODEs is the lack of smoothness of its right-hand side. While the existence of a generalized solution is guaranteed by the theory of Filippov, the uniqueness can only be obtained via a proper regularization. Another difficulty one may encounter is related to an interpretation of the computed solution, whose point values are to be recovered from its particle distribution. We demonstrate that some of known recovering procedures, suitable for smooth functions, may fail to produce reasonable results in the nonsmooth case, and discuss several successful strategies which may be useful in practice. Different approaches are illustrated in a number of numerical examples, including one- and two-dimensional transport equations and the reactive Euler equations of gas dynamics.
DA - 2006///
PY - 2006///
DO - 10.1016/j.apnum.2006.03.024
VL - 56
IS - 10-11
SP - 1418-1431
SN - 1873-5460
UR - https://doi-org.prox.lib.ncsu.edu/10.1016/j.apnum.2006.03.024
KW - linear transport equations with discontinuous coefficients
KW - deterministic particle method
KW - method of characteristics
KW - finite-volume methods
KW - reactive Euler equations of gas dynamics
ER -
TY - JOUR
TI - Modeling baroreflex regulation of heart rate during orthostatic stress
AU - Olufsen, Mette S.
AU - Tran, Hien T.
AU - Ottesen, Johnny T.
AU - Lipsitz, Lewis A.
AU - Novak, Vera
T2 - AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY
AB - During orthostatic stress, arterial and cardiopulmonary baroreflexes play a key role in maintaining arterial pressure by regulating heart rate. This study presents a mathematical model that can predict the dynamics of heart rate regulation in response to postural change from sitting to standing. The model uses blood pressure measured in the finger as an input to model heart rate dynamics in response to changes in baroreceptor nerve firing rate, sympathetic and parasympathetic responses, vestibulo-sympathetic reflex, and concentrations of norepinephrine and acetylcholine. We formulate an inverse least squares problem for parameter estimation and successfully demonstrate that our mathematical model can accurately predict heart rate dynamics observed in data obtained from healthy young, healthy elderly, and hypertensive elderly subjects. One of our key findings indicates that, to successfully validate our model against clinical data, it is necessary to include the vestibulo-sympathetic reflex. Furthermore, our model reveals that the transfer between the nerve firing and blood pressure is nonlinear and follows a hysteresis curve. In healthy young people, the hysteresis loop is wide, whereas, in healthy and hypertensive elderly people, the hysteresis loop shifts to higher blood pressure values, and its area is diminished. Finally, for hypertensive elderly people, the hysteresis loop is generally not closed, indicating that, during postural change from sitting to standing, baroreflex modulation does not return to steady state during the first minute of standing.
DA - 2006/11//
PY - 2006/11//
DO - 10.1152/ajpregu.00205.2006
VL - 291
IS - 5
SP - R1355-R1368
SN - 1522-1490
KW - mathematical modeling
KW - heart rate control
KW - baroreflex function
KW - sympathetic and parasympathetic responses
KW - vestibulo-sympathetic reflex
ER -
TY - JOUR
TI - Low rank update of singular values
AU - Chu, Delin
AU - Chu, Moody
T2 - Mathematics of Computation
AB - The notion of a low rank update arises in many important applications. This paper deals with the inverse problem of updating a rectangular matrix by additive low rank matrices so as to reposition the associated singular values. The setting is analogous to the classical pole assignment problem where eigenvalues of a square matrix are relocated. Precise and easy-to-check necessary and sufficient conditions under which the problem is solvable are completely characterized, generalizing some traditional Weyl inequalities for singular values. The constructive proof makes it possible to compute such a solution numerically. A pseudo algorithm is outlined.
DA - 2006/2/27/
PY - 2006/2/27/
DO - 10.1090/S0025-5718-06-01825-4
VL - 75
IS - 255
SP - 1351-1367
J2 - Math. Comp.
LA - en
OP -
SN - 0025-5718
UR - http://dx.doi.org/10.1090/s0025-5718-06-01825-4
DB - Crossref
KW - singular values
KW - low rank update
KW - interlacing properties
KW - pole assignment
ER -
TY - JOUR
TI - Irreducible modules over finite simple Lie pseudoalgebras I. Primitive pseudoalgebras of type W and S
AU - Bakalov, Bojko
AU - D'Andrea, Alessandro
AU - Kac, Victor G.
T2 - ADVANCES IN MATHEMATICS
AB - One of the algebraic structures that has emerged recently in the study of the operator product expansions of chiral fields in conformal field theory is that of a Lie conformal algebra. A Lie pseudoalgebra is a generalization of the notion of a Lie conformal algebra for which C[∂] is replaced by the universal enveloping algebra H of a finite-dimensional Lie algebra. The finite (i.e., finitely generated over H) simple Lie pseudoalgebras were classified in our previous work [B.Bakalov, A.D’Andrea, V.G. Kac, Theory of finite pseudoalgebras, Adv. Math. 162 (2001) 1–140]. In a series of papers, starting with the present one, we classify all irreducible finite modules over finite simple Lie pseudoalgebras.
DA - 2006/8/1/
PY - 2006/8/1/
DO - 10.1016/j.aim.2005.07.003
VL - 204
IS - 1
SP - 278-346
SN - 1090-2082
KW - Lie pseudoalgebra
KW - Lie-Cartan algebra of vector fields
KW - Hopf algebra
ER -
TY - JOUR
TI - Involutions of SL(n,k), (n < 2)
AU - Helminck, Aloysius G.
AU - Wu, Ling
AU - Dometrius, Christopher E.
T2 - ACTA APPLICANDAE MATHEMATICAE
DA - 2006/1//
PY - 2006/1//
DO - 10.1007/s10440-006-9032-7
VL - 90
IS - 1-2
SP - 91-119
SN - 1572-9036
KW - flag variety
KW - symmetric subgroup
ER -
TY - JOUR
TI - Experimental validation of a homogenized energy model for magnetic after-effects
AU - Braun, TR
AU - Smith, RC
AU - Dapino, MJ
T2 - APPLIED PHYSICS LETTERS
AB - In this letter, we experimentally validate the ability of a recently developed ferromagnetic hysteresis model to characterize magnetic after-effects in ferromagnetic materials. The modeling framework, which combines energy analysis at the lattice level with stochastic homogenization techniques to accommodate material, stress, and field nonhomogeneities, quantifies after-effects through a balance of the Gibbs and relative thermal energies. Attributes of the framework are illustrated through fits to experimental steel data.
DA - 2006/3/20/
PY - 2006/3/20/
DO - 10.1063/1.2188595
VL - 88
IS - 12
SP -
SN - 1077-3118
ER -
TY - JOUR
TI - Climate variability over the Greater Horn of Africa based on NCAR AGCM ensemble
AU - Anyah, R. O.
AU - Semazzi, F. H. M.
T2 - THEORETICAL AND APPLIED CLIMATOLOGY
DA - 2006/9//
PY - 2006/9//
DO - 10.1007/s00704-005-0203-7
VL - 86
IS - 1-4
SP - 39-62
SN - 0177-798X
ER -
TY - JOUR
TI - A mechano-chemical model for the passive swelling response of an isolated chondron under osmotic loading
AU - Haider, MA
AU - Schugart, RC
AU - Setton, LA
AU - Guilak, F
T2 - BIOMECHANICS AND MODELING IN MECHANOBIOLOGY
DA - 2006/6//
PY - 2006/6//
DO - 10.1007/s10237-006-0026-1
VL - 5
IS - 2-3
SP - 160-171
SN - 1617-7959
ER -
TY - JOUR
TI - Time-dependent solutions for particle-size segregation in shallow granular avalanches
AU - Gray, JMNT
AU - Shearer, M
AU - Thornton, AR
T2 - PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
AB - Rapid shallow granular free-surface flows develop in a wide range of industrial and geophysical flows, ranging from rotating kilns and blenders to rock-falls, snow slab-avalanches and debris-flows. Within these flows, grains of different sizes often separate out into inversely graded layers, with the large particles on top of the fines, by a process called kinetic sieving. In this paper, a recent theory is used to construct exact time-dependent two-dimensional solutions for the development of the particle-size distribution in inclined chute flows. The first problem assumes the flow is initially homogeneously mixed and is fed at the inflow with homogeneous material of the same concentration. Concentration shocks develop during the flow and the particles eventually separate out into inversely graded layers sufficiently far downstream. Sections with a monotonically decreasing shock height, between these layers, steepen and break in finite time. The second problem assumes that the material is normally graded, with the small particles on top of the coarse ones. In this case, shock waves, concentration expansions, non-centred expanding shock regions and breaking shocks develop. As the parameters are varied, nonlinearity leads to fundamental topological changes in the solution, and, in simple-shear, a logarithmic singularity prevents a steady-state solution from being attained.
DA - 2006/3/8/
PY - 2006/3/8/
DO - 10.1098/rspa.2005.1580
VL - 462
IS - 2067
SP - 947-972
SN - 1471-2946
KW - particle-size segregation
KW - kinetic sieving
KW - inverse-grading
KW - shocks
ER -
TY - JOUR
TI - Slow eigenvalues of self-similar solutions of the Dafermos regularization of a system of conservation laws: An analytic approach
AU - Lin, Xiao-Biao
T2 - JOURNAL OF DYNAMICS AND DIFFERENTIAL EQUATIONS
AB - The Dafermos regularization of a system of n hyperbolic conservation laws in one space dimension has, near a Riemann solution consisting of n Lax shock waves, a self-similar solution u = u ε(X/T). In Lin and Schecter (2003, SIAM J. Math. Anal. 35, 884–921) it is shown that the linearized Dafermos operator at such a solution may have two kinds of eigenvalues: fast eigenvalues of order 1/ε and slow eigenvalues of order one. The fast eigenvalues represent motion in an initial time layer, where near the shock waves solutions quickly converge to traveling-wave-like motion. The slow eigenvalues represent motion after the initial time layer, where motion between the shock waves is dominant. In this paper we use tools from dynamical systems and singular perturbation theory to study the slow eigenvalues. We show how to construct asymptotic expansions of eigenvalue-eigenfunction pairs to any order in ε. We also prove the existence of true eigenvalue-eigenfunction pairs near the asymptotic expansions.
DA - 2006/1//
PY - 2006/1//
DO - 10.1007/s10884-005-9001-2
VL - 18
IS - 1
SP - 1-52
SN - 1040-7294
KW - conservation law
KW - Riemann solution
KW - Dafermos regularization
KW - stability
KW - eigenvalue
KW - eigenfunction
KW - SLEP method
KW - asymptotic expansion
ER -
TY - JOUR
TI - Signature function for predicting resonant and attenuant population 2-cycles
AU - Franke, John E.
AU - Yakubu, Abdul-Aziz
T2 - BULLETIN OF MATHEMATICAL BIOLOGY
DA - 2006/11//
PY - 2006/11//
DO - 10.1007/s11538-006-9086-8
VL - 68
IS - 8
SP - 2069-2104
SN - 1522-9602
KW - attenuance
KW - periodic carrying capacity
KW - periodic demographic characteristic
KW - signature function
KW - resonance
ER -
TY - JOUR
TI - Parallel parameter study of the Wigner-Poisson equations for RTDs
AU - Lasater, M. S.
AU - Kelley, C. T.
AU - Salinger, A. G.
AU - Woolard, D. L.
AU - Zhao, P.
T2 - COMPUTERS & MATHEMATICS WITH APPLICATIONS
AB - We will discuss a parametric study of the solution of the Wigner-Poisson equations for resonant tunneling diodes. These structures exhibit self-sustaining oscillations in certain operating regimes. We will describe the engineering consequences of our study and how it is a significant advance from some previous work, which used much coarser grids. We use LOCA and other packages in the Trilinos framework from Sandia National Laboratory to enable efficient parallelization of the solution methods and to perform bifurcation analysis of this model. We report on the parallel efficiency and scalability of our implementation.
DA - 2006/6//
PY - 2006/6//
DO - 10.1016/j.camwa.2006.05.006
VL - 51
IS - 11
SP - 1677-1688
SN - 1873-7668
KW - Wigner-Poisson equation
KW - resonant tunneling diode
KW - continuation
KW - LOCA
KW - scalability
ER -
TY - JOUR
TI - Optimizing detection of tissue anisotropy by fluorescence recovery after photobleaching
AU - Lubkin, S. R.
AU - Wan, X.
T2 - BULLETIN OF MATHEMATICAL BIOLOGY
DA - 2006/11//
PY - 2006/11//
DO - 10.1007/s11538-006-9074-z
VL - 68
IS - 8
SP - 1873-1891
SN - 1522-9602
UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000241796800003&KeyUID=WOS:000241796800003
KW - hindered diffusion
KW - anisotropic diffusion
KW - polydisperse
KW - cartilage
KW - fluorescence microscopy
ER -
TY - JOUR
TI - Multivariate subresultants in roots
AU - D'Andrea, Carlos
AU - Krick, Teresa
AU - Szanto, Agnes
T2 - JOURNAL OF ALGEBRA
AB - We give a rational expression for the subresultants of n+1 generic polynomials f1,…,fn+1 in n variables as a function of the coordinates of the common roots of f1,…,fn and their evaluation in fn+1. We present a simple technique to prove our results, giving new proofs and generalizing the classical Poisson product formula for the projective resultant, as well as the expressions of Hong for univariate subresultants in roots.
DA - 2006/8/1/
PY - 2006/8/1/
DO - 10.1016/j.jalgebra.2005.08.016
VL - 302
IS - 1
SP - 16-36
SN - 1090-266X
KW - subresultants
KW - Poisson product formula
KW - Vandermonde determinants
ER -
TY - JOUR
TI - Jacobi identity for vertex algebras in higher dimensions
AU - Bakalov, Bojko
AU - Nikolov, Nikolay M.
T2 - JOURNAL OF MATHEMATICAL PHYSICS
AB - Vertex algebras in higher dimensions, introduced previously by Nikolov, provide an algebraic framework for investigating axiomatic quantum field theory with global conformal invariance. We develop further the theory of such vertex algebras by introducing formal calculus techniques and investigating the notion of polylocal fields. We derive a Jacobi identity which together with the vacuum axiom can be taken as an equivalent definition of vertex algebra.
DA - 2006/5//
PY - 2006/5//
DO - 10.1063/1.2197687
VL - 47
IS - 5
SP -
SN - 1089-7658
ER -
TY - JOUR
TI - Eigenvalues of self-similar solutions of the dafermos regularization of a system of conservation laws via geometric singular perturbation theory
AU - Schecter, Stephen
T2 - JOURNAL OF DYNAMICS AND DIFFERENTIAL EQUATIONS
DA - 2006/1//
PY - 2006/1//
DO - 10.1007/s10884-005-9000-3
VL - 18
IS - 1
SP - 53-101
SN - 1572-9222
KW - conservation law
KW - Dafermos regularization
KW - eigenfunction
KW - eigenvalue
KW - geometric singular perturbation theory
KW - Riemann problem
KW - stability
ER -
TY - JOUR
TI - Determination of interrogating frequencies to maximize electromagnetic backscatter from objects with material coatings
AU - Banks, H. T.
AU - Ito, K.
AU - Toivanen, J.
T2 - Communications in Computational Physics
DA - 2006///
PY - 2006///
VL - 1
IS - 2
SP - 362-382
ER -
TY - JOUR
TI - Analysis of mean climate conditions in Senegal (1971-98)
AU - Fall, S.
AU - Niyogi, D.
AU - Semazzi, F. H. M.
T2 - Earth Interactions
AB - Abstract This paper presents a GIS-based analysis of climate variability over Senegal, West Africa. It responds to the need for developing a climate atlas that uses local observations instead of gridded global analyses. Monthly readings of observed rainfall (20 stations) and mean temperature (12 stations) were compiled, digitized, and quality assured for a period from 1971 to 1998. The monthly, seasonal, and annual temperature and precipitation distributions were mapped and analyzed using ArcGIS Spatial Analyst. A north–south gradient in rainfall and an east–west gradient in temperature variations were observed. June exhibits the greatest variability for both quantity of rainfall and number of rainy days, especially in the western and northern parts of the country. Trends in precipitation and temperature were studied using a linear regression analysis and interpolation maps. Air temperature showed a positive and significant warming trend throughout the country, except in the southeast. A significant correlation is found between the temperature index for Senegal and the Pacific sea surface temperatures during the January–April period, especially in the El Niño zone. In contrast to earlier regional-scale studies, precipitation does not show a negative trend and has remained largely unchanged, with a few locations showing a positive trend, particularly in the northeastern and southwestern regions. This study reveals a need for more localized climate analyses of the West Africa region because local climate variations are not always captured by large-scale analysis, and such variations can alter conclusions related to regional climate change.
DA - 2006///
PY - 2006///
DO - 10.1175/ei158.1
VL - 10
ER -
TY - JOUR
TI - Analysis of blood flow velocity and pressure signals using the multipulse method
AU - Justice, D. H.
AU - Trussell, H. J.
AU - Olufsen, M. S.
T2 - Mathematical Biosciences and Engineering
AB - This paper shows how the multipulse method from digital signal processing can be used to accurately synthesize signals obtained from blood pressure and blood flow velocity sensors during posture change from sitting to standing. The multipulse method can be used to analyze signals that are composed of pulses of varying amplitudes. One of the advantages of the multipulse method is that it is able to produce an accurate and efficient representation of the signals at high resolution. The signals are represented as a set of input impulses passed through an autoregressive (AR) filter. The parameters that define the AR filter can be used to distinguish different conditions. In addition, the AR coefficients can be transformed to tube radii associated with digital wave guides, as well as pole-zero representation. Analysis of the dynamics of the model parameters have potential to provide better insight and understanding of the underlying physiological control mechanisms. For example, our data indicate that the tube radii may be related to the diameter of the blood vessels.
DA - 2006///
PY - 2006///
DO - 10.3934/mbe.2006.3.419
VL - 3
IS - 2
SP - 419-440
ER -
TY - JOUR
TI - An extended procedure for implementing the relative operating characteristic graphical method
AU - Semazzi, Fredrick H. M.
AU - Mera, Roberto J.
T2 - JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY
AB - Abstract The functional relationship between the relative operating characteristic (ROC) and the economic value (EV) graphical methods have been exploited to develop a hybrid procedure called the extended ROC (EROC) method. The EROC retains the appealing simplicity of the traditional ROC method and the ability of the EV method to provide evaluation of the performance of an ensemble climate prediction system (EPS) for a hypothetical end user defined by the cost–loss ratio (μ = C/L). An inequality defining the lower and upper theoretical bounds of μ has been derived. Outside these limits, the EPS yields no added benefits for end user μ relative to the use of climatological persistence as an alternative prediction system. In the traditional ROC graphical method, the ROC skill (ROCS) is often expressed in terms of the area between the ROC graph and the diagonal baseline passing through the origin with slope m = 1. Thus, ROCS = 2A − 1, where A is the area under the ROC graph. In the proposed EROC approach, a more general procedure is recommended based on the construction of user-specific baselines that do not necessarily pass through the origin and, in general, have slope m ≠ 1. The skill of a particular EPS computed from the EROC method is proportional to the corresponding estimated value based on the EV graphical method. Therefore, the EROC geometry conveys the same basic information as the EV method. The Semazzi–Mera skill score (SMSS) is proposed as a convenient and compact way of expressing the combined verification based on the ROC and EV methods. The ROCS estimate is a special case of the SMSS. The near-horizontal trail-like geometry sometimes exhibited by EV graphs is also examined. It is shown to occur when either the hit-rate or false-alarm term dominates in the formula for EV, unlike the more typical situation in which both terms are comparable in magnitude.
DA - 2006/9//
PY - 2006/9//
DO - 10.1175/JAM2397.1
VL - 45
IS - 9
SP - 1215-1223
SN - 1558-8432
ER -
TY - JOUR
TI - A homogenized energy framework for ferromagnetic hysteresis
AU - Smith, Ralph C.
AU - Dapino, Marcelo J.
AU - Braun, Thomas R.
AU - Mortensen, Anthony P.
T2 - IEEE TRANSACTIONS ON MAGNETICS
AB - In this paper, we develop a macroscopic framework quantifying the hysteresis and constitutive nonlinearities inherent to ferromagnetic materials. In the first step of the development, we construct Helmholtz and Gibbs energy relations at the mesoscopic or lattice level based on the assumption that magnetic moments or spins are restricted to two orientations. Direct minimization of the Gibbs energy yields local average magnetization relations appropriate for operating regimes in which relaxation mechanisms are negligible whereas the balance of the Gibbs and relative thermal energies through Boltzmann principles provides local models which incorporate mechanisms such as thermal after-effects. To construct macroscopic relations that incorporate material nonhomogeneities, polycrystallinity, and variable effective fields, we employ stochastic homogenization techniques based on the assumption that parameters such as local coercive and interaction fields are manifestations of underlying distributions. The resulting framework quantifies in a natural manner the anhysteretic magnetization provided by decaying ac fields and guarantees the closure of biased minor loops once transient accommodation and after-effects are complete. Furthermore, noncongruency at differing magnetization levels is achieved with certain choices for the energy functionals. Hence, the framework provides an energy basis for certain extended Preisach models and the relation of the framework to several macroscopic hysteresis models is detailed. The behavior of both the nonlinear anhysteretic relations and full hysteresis model are validated through comparison with steel and nickel data.
DA - 2006/7//
PY - 2006/7//
DO - 10.1109/TMAG.2006.875717
VL - 42
IS - 7
SP - 1747-1769
SN - 1941-0069
KW - actuators
KW - Boltzmann equation
KW - magnetic hysteresis
KW - modeling
KW - nonlinear magnetics
ER -
TY - JOUR
TI - Plum Crimson, fresh-market plum tomato hybrid and its parents, NC EBR-7 and NC EBR-8
AU - Gardner, R. G.
T2 - HortScience
DA - 2006///
PY - 2006///
VL - 41
IS - 1
SP - 259-260
ER -
TY - JOUR
TI - Mountain Crest, hybrid tomato and its parent, NC 1 rinEC
AU - Gardner, R. G.
T2 - HortScience
DA - 2006///
PY - 2006///
VL - 41
IS - 1
SP - 261-262
ER -
TY - JOUR
TI - Gauged Wess-Zumino model in noncommutative Minkowski superspace
AU - Cook, JS
T2 - JOURNAL OF MATHEMATICAL PHYSICS
AB - We develop a gauged Wess–Zumino model in noncommutative Minkowski superspace. This is the natural extension of the work of Carlson and Nazaryan, which extended N=1∕2 supersymmetry written over deformed Euclidean superspace to Minkowski superspace. We investigate the coupling of the vector and chiral superfields. Noncommutativity is implemented by replacing products with star products. Although, in general, our star product is nonassociative, we prove that it is associative to the first order in the deformation parameter C. We show that our model reproduces the N=1∕2 theory in the appropriate limit, namely when the deformation parameters C¯α̇β̇=0. Essentially, we find the N=1∕2 theory and a conjugate copy. As in the N=1∕2 theory, a reparametrization of the gauge parameter, vector superfield, and chiral superfield are necessary to write standard C-independent gauge theory. However, our choice of parametrization differs from that used in the N=1∕2 supersymmetry, which leads to some unexpected new terms.
DA - 2006/1//
PY - 2006/1//
DO - 10.1063/1.2162330
VL - 47
IS - 1
SP -
SN - 1089-7658
ER -
TY - JOUR
TI - Fast solvers for 3D Poisson equations involving interfaces in a finite or the infinite domain
AU - Lai, MC
AU - Li, ZL
AU - Lin, XB
T2 - JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS
AB - In this paper, numerical methods are proposed for Poisson equations defined in a finite or infinite domain in three dimensions. In the domain, there can exists an interface across which the source term, the flux, and therefore the solution may be discontinuous. The existence and uniqueness of the solution are also discussed. To deal with the discontinuity in the source term and in the flux, the original problem is transformed to a new one with a smooth solution. Such a transformation can be carried out easily through an extension of the jumps along the normal direction if the interface is expressed as the zero level set of a three-dimensional function. An auxiliary sphere is used to separate the infinite region into an interior and exterior domain. The Kelvin's inversion is used to map the exterior domain into an interior domain. The two Poisson equations defined in the interior and the exterior written in spherical coordinates are solved simultaneously. By choosing the mesh size carefully and exploiting the fast Fourier transform, the resulting finite difference equations can be solved efficiently. The approach in dealing with the interface has also been used with the artificial boundary condition technique which truncates the infinite domain. Numerical results demonstrate second order accuracy of our algorithms.
DA - 2006/6/15/
PY - 2006/6/15/
DO - 10.1016/j.cam.2005.04.025
VL - 191
IS - 1
SP - 106-125
SN - 1879-1778
KW - arbitrary interface
KW - fast 3D Poisson solver
KW - immersed interface method
KW - infinite domain
KW - extension of jumps
KW - spherical coordinates
KW - level set function
KW - artificial boundary condition
ER -
TY - JOUR
TI - Auxiliary signal design for active failure detection in uncertain linear systems with a priori information
AU - Nikoukhah, R
AU - Campbell, SL
T2 - AUTOMATICA
AB - A method for auxiliary signal design for active failure detection based on a multi-model formulation of normal and failed systems is developed which allows for a priori information about initial conditions and the possibility of having a known input in addition to the test signal. These results permit the consideration of additional types of failures, such as biases, that a previous approach could not handle. Both theoretical results and computational algorithms are developed.
DA - 2006/2//
PY - 2006/2//
DO - 10.1016/j.automatica.2005.09.011
VL - 42
IS - 2
SP - 219-228
SN - 1873-2836
KW - failure detection
KW - active detection
KW - test signal construction
KW - model-based fault detection
ER -
TY - JOUR
TI - A Legendre expansion and some exact solutions basic to the McCormack model for binary gas mixtures
AU - Siewert, CE
T2 - EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
AB - A Legendre expansion of the scattering kernel, a conservation condition and some exact solutions are reported for the McCormack kinetic model that is used to describe a binary mixture of rarefied gases.
DA - 2006///
PY - 2006///
DO - 10.1016/j.euromechflu.2005.04.005
VL - 25
IS - 1
SP - 130-136
SN - 1873-7390
KW - rarefied gas dynamics
KW - McCormack model
KW - binary gas mixture
ER -
TY - JOUR
TI - A semidefinite programming based polyhedral cut and price approach for the maxcut problem
AU - Krishnan, K
AU - Mitchell, JE
T2 - COMPUTATIONAL OPTIMIZATION AND APPLICATIONS
DA - 2006/1//
PY - 2006/1//
DO - 10.1007/s10589-005-5958-3
VL - 33
IS - 1
SP - 51-71
SN - 1573-2894
KW - semidefinite programming
KW - column generation
KW - cutting plane methods
KW - combinatorial optimization
ER -
TY - JOUR
TI - A level-set method for interfacial flows with surfactant
AU - Xu, JJ
AU - Li, ZL
AU - Lowengrub, J
AU - Zhao, HK
T2 - JOURNAL OF COMPUTATIONAL PHYSICS
AB - A level-set method for the simulation of fluid interfaces with insoluble surfactant is presented in two-dimensions. The method can be straightforwardly extended to three-dimensions and to soluble surfactants. The method couples a semi-implicit discretization for solving the surfactant transport equation recently developed by Xu and Zhao [J. Xu, H. Zhao. An Eulerian formulation for solving partial differential equations along a moving interface, J. Sci. Comput. 19 (2003) 573–594] with the immersed interface method originally developed by LeVeque and Li and [R. LeVeque, Z. Li. The immersed interface method for elliptic equations with discontinuous coefficients and singular sources, SIAM J. Numer. Anal. 31 (1994) 1019–1044] for solving the fluid flow equations and the Laplace–Young boundary conditions across the interfaces. Novel techniques are developed to accurately conserve component mass and surfactant mass during the evolution. Convergence of the method is demonstrated numerically. The method is applied to study the effects of surfactant on single drops, drop–drop interactions and interactions among multiple drops in Stokes flow under a steady applied shear. Due to Marangoni forces and to non-uniform Capillary forces, the presence of surfactant results in larger drop deformations and more complex drop–drop interactions compared to the analogous cases for clean drops. The effects of surfactant are found to be most significant in flows with multiple drops. To our knowledge, this is the first time that the level-set method has been used to simulate fluid interfaces with surfactant.
DA - 2006/3/1/
PY - 2006/3/1/
DO - 10.1016/j.jcp.2005.07.016
VL - 212
IS - 2
SP - 590-616
SN - 1090-2716
KW - incompressible stokes flow
KW - interfaces
KW - insoluble surfactant
KW - Marangoni force
KW - capillary force
KW - level set method
KW - immersed interface method
ER -
TY - JOUR
TI - Void detection in foam with knit lines using THz pulse interrogation
AU - Banks, H. T.
AU - Gibson, N. L.
T2 - MATHEMATICAL AND COMPUTER MODELLING
AB - We model the electromagnetic interrogation of a polyurethane foam using the transverse electric (TE) mode of the two-dimensional (2D) Maxwell’s equations reduced to the wave equation for a fixed frequency in the terahertz (THz) regime. The foam block target contains knit lines which are modeled by modifying the speed of propagation, i.e., by altering the index of refraction. We describe our efforts to estimate the dielectric constant in the knit lines, as well as in the surrounding foam, by use of the classical Clausius–Mossotti equation, assuming only a change in density. We compare the numerical simulations accounting for knit lines to those in which knit lines are neglected, each in the context of modeling reflections of plane waves in foam with voids.
DA - 2006/11//
PY - 2006/11//
DO - 10.1016/j.mcm.2006.02.014
VL - 44
IS - 9-10
SP - 807-815
SN - 0895-7177
KW - terahertz electromagnetic waves
KW - heterogeneous materials
KW - numerical simulations
ER -
TY - JOUR
TI - Variational approach to shape derivatives for a class of Bernoulli problems
AU - Ito, K
AU - Kunisch, K
AU - Peichl, GH
T2 - JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS
AB - The shape derivative of a functional related to a Bernoulli problem is derived without using the shape derivative of the state. The gradient information is combined with level set ideas in a steepest descent algorithm. Numerical examples show the feasibility of the approach.
DA - 2006/2/1/
PY - 2006/2/1/
DO - 10.1016/j.jmaa.2005.03.100
VL - 314
IS - 1
SP - 126-149
SN - 1096-0813
KW - shape derivative
KW - Bernoulli problem
KW - level set
ER -
TY - JOUR
TI - The motion of a thin liquid film driven by surfactant and gravity
AU - Levy, R.
AU - Shearer, M.
T2 - SIAM JOURNAL ON APPLIED MATHEMATICS
AB - We investigate wave solutions of a lubrication model for surfactant-driven flow of a thin liquid film down an inclined plane. We model the flow in one space dimension with a system of nonlinear PDEs of mixed hyperbolic-parabolic type in which the effects of capillarity and surface diffusion are neglected. Numerical solutions reveal distinct patterns of waves that are described analytically by combinations of traveling waves, some with jumps in height and surfactant concentration gradient. The various waves and combinations are strikingly different from what is observed in the case of flow on a horizontal plane. Jump conditions admit new shock waves sustained by a linear surfactant wave traveling upstream. The stability of these waves is investigated analytically and numerically. For initial value problems, a critical ratio of upstream to downstream height separates two distinct long-time wave patterns. Below the critical ratio, there is also an exact solution in which the height is piecewise constant and the surfactant concentration is piecewise linear and has compact support.
DA - 2006///
PY - 2006///
DO - 10.1137/050637030
VL - 66
IS - 5
SP - 1588-1609
SN - 0036-1399
KW - PDE
KW - surfactants
KW - hyperbolic
KW - parabolic system
ER -
TY - JOUR
TI - Sensitivity of dynamical systems to Banach space parameters
AU - Banks, H. T.
AU - Nguyen, Hoan K.
T2 - JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS
AB - We consider general nonlinear dynamical systems in a Banach space with dependence on parameters in a second Banach space. An abstract theoretical framework for sensitivity equations is developed. An application to measure dependent delay differential systems arising in a class of HIV models is presented.
DA - 2006/11/1/
PY - 2006/11/1/
DO - 10.1016/j.jmaa.2005.09.084
VL - 323
IS - 1
SP - 146-161
SN - 0022-247X
KW - sensitivity equations
KW - delay differential equations
KW - approximation
ER -
TY - JOUR
TI - Physiologically-based pharmacokinetic modeling of benzene in humans: A Bayesian approach
AU - Yokley, Karen
AU - Tran, Hien T.
AU - Pekari, Kaija
AU - Rappaport, Stephen
AU - Riihimaki, Vesa
AU - Rothman, Nat
AU - Waidyanatha, Suramya
AU - Schlosser, Paul M.
T2 - RISK ANALYSIS
AB - Benzene is myelotoxic and leukemogenic in humans exposed at high doses (>1 ppm, more definitely above 10 ppm) for extended periods. However, leukemia risks at lower exposures are uncertain. Benzene occurs widely in the work environment and also indoor air, but mostly below 1 ppm, so assessing the leukemia risks at these low concentrations is important. Here, we describe a human physiologically‐based pharmacokinetic (PBPK) model that quantifies tissue doses of benzene and its key metabolites, benzene oxide, phenol, and hydroquinone after inhalation and oral exposures. The model was integrated into a statistical framework that acknowledges sources of variation due to inherent intra‐ and interindividual variation, measurement error, and other data collection issues. A primary contribution of this work is the estimation of population distributions of key PBPK model parameters. We hypothesized that observed interindividual variability in the dosimetry of benzene and its metabolites resulted primarily from known or estimated variability in key metabolic parameters and that a statistical PBPK model that explicitly included variability in only those metabolic parameters would sufficiently describe the observed variability. We then identified parameter distributions for the PBPK model to characterize observed variability through the use of Markov chain Monte Carlo analysis applied to two data sets. The identified parameter distributions described most of the observed variability, but variability in physiological parameters such as organ weights may also be helpful to faithfully predict the observed human‐population variability in benzene dosimetry.
DA - 2006/8//
PY - 2006/8//
DO - 10.1111/j.1539-6924.2006.00789.x
VL - 26
IS - 4
SP - 925-943
SN - 0272-4332
KW - Bayesian
KW - benzene
KW - dosimetry
KW - human
KW - metabolism
KW - PBPK
KW - variability
ER -
TY - JOUR
TI - Monte Carlo simulation of a solvated ionic polymer with cluster morphology
AU - Matthews, JL
AU - Lada, EK
AU - Weiland, LM
AU - Smith, RC
AU - Leo, DJ
T2 - SMART MATERIALS & STRUCTURES
AB - A multiscale modeling approach for the prediction of material stiffness of the ionic polymer Nafion is presented. Traditional rotational isomeric state theory is applied in combination with a Monte Carlo methodology to develop a simulation model of the conformation of Nafion polymer chains on a nanoscopic level from which a large number of end-to-end chain lengths are generated. The probability density function of end-to-end distances is then estimated and used as an input parameter to enhance existing energetics-based macroscale models of ionic polymer behavior. Several methods for estimating the probability density function are compared, including estimation using Johnson distributions, Bézier distributions, and cubic splines.
DA - 2006/2//
PY - 2006/2//
DO - 10.1088/0964-1726/15/1/048
VL - 15
IS - 1
SP - 187-199
SN - 0964-1726
ER -
TY - JOUR
TI - Discrete-time sis epidemic model in a seasonal environment
AU - Franke, John E.
AU - Yakubu, Abdul-Aziz
T2 - SIAM JOURNAL ON APPLIED MATHEMATICS
AB - We study the combined effects of seasonal trends and diseases on the extinction and persistence of discretely reproducing populations. We introduce the epidemic threshold parameter, R0 , for predicting disease dynamics in periodic environments. Typically, in periodic environments, R0 > 1 implies disease persistence on a cyclic attractor, while R0 < 1 implies disease extinction. We also explore the relationship between the demographic equation and the epidemic process. In particular, we show that in periodic environments, it is possible for the infective population to be on a chaotic attractor while the demographic dynamics is nonchaotic.
DA - 2006///
PY - 2006///
DO - 10.1137/050638345
VL - 66
IS - 5
SP - 1563-1587
SN - 1095-712X
KW - epidemics
KW - infectives
KW - periodic environments
KW - susceptibles
ER -
TY - JOUR
TI - A unified framework for modeling hysteresis in ferroic materials
AU - Smith, RC
AU - Seelecke, S
AU - Dapino, M
AU - Ounaies, Z
T2 - JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
AB - This paper addresses the development of a unified framework for quantifying hysteresis and constitutive nonlinearities inherent to ferroelectric, ferromagnetic and ferroelastic materials. Because the mechanisms which produce hysteresis vary substantially at the microscopic level, it is more natural to initiate model development at the mesoscopic, or lattice, level where the materials share common energy properties along with analogous domain structures. In the first step of the model development, Helmholtz and Gibbs energy relations are combined with Boltzmann theory to construct mesoscopic models which quantify the local average polarization, magnetization and strains in ferroelectric, ferromagnetic and ferroelastic materials. In the second step of the development, stochastic homogenization techniques are invoked to construct unified macroscopic models for nonhomogeneous, polycrystalline compounds exhibiting nonuniform effective fields. The combination of energy analysis and homogenization techniques produces low-order models in which a number of parameters can be correlated with physical attributes of measured data. Furthermore, the development of a unified modeling framework applicable to a broad range of ferroic compounds facilitates material characterization, transducer development, and model-based control design. Attributes of the models are illustrated through comparison with piezoceramic, magnetostrictive and shape memory alloy data and prediction of material behavior.
DA - 2006/1//
PY - 2006/1//
DO - 10.1016/j.jmps.2005.08.006
VL - 54
IS - 1
SP - 46-85
SN - 1873-4782
KW - ferroic materials
KW - unified models
KW - hysteresis
KW - constitutive nonlinearities
ER -
TY - JOUR
TI - Interface conditions for Stokes equations with a discontinuous viscosity and surface sources
AU - Ito, K
AU - Li, ZL
T2 - APPLIED MATHEMATICS LETTERS
AB - The interface conditions, or jump conditions, for the pressure and the velocity of the solution to the incompressible Stokes equations with a discontinuous viscosity and a singular source along an interface are derived in this work. While parts of the results agree with those in the literature, some of the results are new. These theoretical results are useful for developing accurate numerical methods for the interface problem.
DA - 2006/3//
PY - 2006/3//
DO - 10.1016/j.aml.2005.02.041
VL - 19
IS - 3
SP - 229-234
SN - 0893-9659
KW - incompressible Stokes equations
KW - interface
KW - discontinuous viscosity
KW - interface conditions
KW - singular sources
ER -
TY - JOUR
TI - A numerical method for the continuous spectrum biphasic poroviscoelastic model of articular cartilage
AU - Haider, MA
AU - Schugart, RC
T2 - JOURNAL OF BIOMECHANICS
AB - A method for numerical solution of the continuous spectrum linear biphasic poroviscoelastic (BPVE) model of articular cartilage is presented. The method is based on an alternate formulation of the continuous spectrum stress-strain law that is implemented using Gaussian quadrature integration combined with quadratic interpolation of the strain history. For N time steps, the cost of the method is O(N). The method is applied to a finite difference solution of the one-dimensional confined compression BPVE stress-relaxation problem. For a range of relaxation times that are representative of articular cartilage, accuracy of the method is demonstrated by direct comparison to a theoretical Laplace transform solution.
DA - 2006///
PY - 2006///
DO - 10.1016/j.jbiomech.2004.10.037
VL - 39
IS - 1
SP - 177-183
SN - 0021-9290
KW - biphasic poroviscoelastic model
KW - articular cartilage
KW - stress relaxation
KW - numerical method
ER -
TY - JOUR
TI - Developing portfolios of water supply transfers
AU - Characklis, GW
AU - Kirsch, BR
AU - Ramsey, J
AU - Dillard, KEM
AU - Kelley, CT
T2 - WATER RESOURCES RESEARCH
AB - Most cities rely on firm water supply capacity to meet demand, but increasing scarcity and supply costs are encouraging greater use of temporary transfers (e.g., spot leases, options). This raises questions regarding how best to coordinate the use of these transfers in meeting cost and reliability objectives. This paper combines a hydrologic–water market simulation with an optimization approach to identify portfolios of permanent rights, options, and leases that minimize the expected costs of meeting a city's annual demand with a specified reliability. Spot market prices are linked to hydrologic conditions and described by monthly lease price distributions which are used to price options via a risk‐neutral approach. Monthly choices regarding when and how much water to acquire through temporary transfers are made on the basis of anticipatory decision rules related to the ratio of expected supply to expected demand. The simulation is linked with an algorithm that uses an implicit filtering search method designed for solution surfaces that exhibit high‐frequency, low‐amplitude noise. This simulation‐optimization approach is applied to a region that currently supports an active water market, with results suggesting that temporary transfers can reduce expected water supply costs substantially, while still maintaining high reliability. Also evaluated are trade‐offs between expected costs and cost variability that occur with variation in a portfolio's distribution of rights, options, and leases.
DA - 2006/5/3/
PY - 2006/5/3/
DO - 10.1029/2005wr004424
VL - 42
IS - 5
SP -
SN - 1944-7973
ER -
TY - JOUR
TI - Variation in volume production through clonal deployment: Results from a simulation model to minimize risk for both a currently known and unknown future pest
AU - Yanchuk, A. D.
AU - Bishir, J.
AU - Russell, J. H.
AU - Polsson, K. R.
T2 - SILVAE GENETICA
AB - Abstract A simulation model was developed to examine optimum patterns of deploying selected clones in the hypothetical situations of both a currently known pest and an unknown future pest. We modelled the interactions between Sitka spruce (Picea sitchensis (Bong.) Carr.), an economically important forest tree in British Columbia and the northwestern U.S., and the spruce terminal weevil (Pissodes strobi (Peck)), a major pest in western spruces. The model is combined with the Province of British Columbia’s Tree and Stand Simulator (TASS) model to drive individual tree growth and stand establishment and development. Two clonal-sampling strategies are examined: a randomly drawn set of genotypes or clones, to depict the potential consequences of a new (e.g., exotic) or a previously unimportant natural pest attacking a ‘random’ set of genotypes, and a ‘fixed’ set of clones, emulating a ‘commercial’ or known set of clones for growth and resistance mechanisms. Simulations use a range of numbers of genotypes or clones (2, 6, 18 and 30), and three deployment patterns (a random mixture of ramets, single- clone blocks, and a mosaic of smaller clonal blocks), in one and five hectare (Ha) stands. Total merchantable timber volume on a per Ha basis at harvest age 80 is used to compare the various combinations and schemes. With both random and fixed chosen sets of clones, the random planting pattern (i.e., random mixture of ramets from the clonal set) produced the most volume. Eighteen randomly chosen clones generally produced more volume, than 2, 6 and 30 clones, but differences among 6, 18 and 30 clones were small in most cases, irrespective of planting pattern. For fixed clones, the use of more resistant clones with higher growth potential produced more volume; however, pure clonal blocks of the best clone were not better than a mixture of that clone and an inferior one. Reducing the effects of insect activity and attack on trees, by lowering the average annual temperature in the model, or turning off all insect ‘activity’, increased merchantable volume but did not change the optimum number of clones (~18) or deployment pattern (random mixture). Forestry agencies can weigh these findings against economic advantages of block plantings of similar genotypes, in the choice of an appropriate number of clones and a deployment strategy.
DA - 2006///
PY - 2006///
DO - 10.1515/sg-2006-0005
VL - 55
IS - 1
SP - 25-37
SN - 2509-8934
KW - clonal forestry
KW - genetic diversity
KW - risk
KW - merchantable volume loss
KW - insect resistance
ER -
TY - JOUR
TI - Tagged particle limit for a Fleming-Viot type system
AU - Grigorescu, I
AU - Kang, M
T2 - ELECTRONIC JOURNAL OF PROBABILITY
AB - We consider a branching system of $N$ Brownian particles evolving independently in a domain $D$ during any time interval between boundary hits. As soon as one particle reaches the boundary it is killed and one of the other particles splits into two independent particles, the complement of the set $D$ acting as a catalyst or hard obstacle. Identifying the newly born particle with the one killed upon contact with the catalyst, we determine the exact law of the tagged particle as $N$ approaches infinity. In addition, we show that any finite number of labelled particles become independent in the limit. Both results can be seen as scaling limits of a genome population undergoing redistribution present in the Fleming-Viot dynamics.
DA - 2006/4/20/
PY - 2006/4/20/
DO - 10.1214/ejp.v11-316
VL - 11
SP - 311-331
SN - 1083-6489
KW - Fleming-Viot
KW - propagation of chaos
KW - tagged particle
KW - absorbing Brownian motio
ER -
TY - JOUR
TI - Reachable matrices by a QR step with shift
AU - Chu, DL
AU - Chu, M
T2 - SIAM JOURNAL ON APPLIED DYNAMICAL SYSTEMS
AB - One of the most interesting dynamical systems used in numerical analysis is the $QR$ algorithm. An added maneuver to improve the convergence behavior is the $QR$ iteration with shift which is of fundamental importance in eigenvalue computation. This paper is a theoretical study of the set of all isospectral matrices "reachable" by the dynamics of the $QR$ algorithm with shift. A matrix B is said to be reachable by A if $B = RQ + \mu I$, where $A - \mu I = QR$ is the $QR$ decomposition for some $\mu \in \mathbb{R}$. It is proved that in general the $QR$ algorithm with shift is neither reflexive nor symmetric. Examples are given to demonstrate that this relation is neither transitive nor antisymmetric. It is further discovered that the reachable set from a given $n \times n$ matrix A forms $2^{n-1}$ disjoint open loops if n is even and $2^{n-2}$ disjoint components each of which is no longer a loop when n is odd.
DA - 2006///
PY - 2006///
DO - 10.1137/040617844
VL - 5
IS - 1
SP - 91-107
SN - 1536-0040
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33644931671&partnerID=MN8TOARS
KW - QR algorithm
KW - shift
KW - analytic QR decomposition
KW - reachable matrices
KW - reflexivity
KW - symmetry
KW - transitivity
ER -
TY - JOUR
TI - Idempotent-conjugate monoids with nilpotent unit groups
AU - Putcha, MS
T2 - SEMIGROUP FORUM
DA - 2006///
PY - 2006///
DO - 10.1007/s00233-005-0560-7
VL - 72
IS - 2
SP - 329-336
SN - 1432-2137
ER -
TY - JOUR
TI - Physiologically-based pharmacokinetic modeling of genistein in rats, part I: Model development
AU - Schlosser, PM
AU - Borghoff, SJ
AU - Coldham, NG
AU - David, JA
AU - Ghosh, SK
T2 - RISK ANALYSIS
AB - Genistein is a phytoestrogen—a plant‐derived compound that binds to and activates the estrogen receptor—occurring at high levels in soy beans and food products, leading to widespread human exposure. The numerous scientific publications available describing genistein's dosimetry, mechanisms of action, and identified or putative health effects in both experimental animals and humans make it ideal for examination as an example of endocrine‐active compound (EAC). We developed a physiologically‐based pharmacokinetic (PBPK) model to quantify the internal, target‐tissue dosimetry of genistein in adult rats. Complexities of the model include enterohepatic circulation, binding of both genistein and its conjugates to plasma proteins, and the multiple compartments used to describe transport through the bile duct and gastrointestinal tract. Other aspects of the model are simple perfusion‐limited transport to the tissue groups and first‐order rates of metabolism, uptake, and excretion. We describe here the model structure and initial calibration of the model by fitting to a large data set for Wistar rats. The model structure can be readily extrapolated to describe genistein dosimetry in humans or modified to describe the dosimetry of other phytoestrogens and phenolic EACs. The model does a fair job of capturing the pharmacokinetics. Although it does not describe the interindividual variability and we have not identified a single set of parameters that provide a good fit to the data for both oral and intravenous exposures, we believe it provides a good initial attempt at PBPK modeling for genistein, which can serve as a template for other phytoestrogens and in the design of future experiments and research that can be used to fill data gaps and better estimate model parameters.
DA - 2006/4//
PY - 2006/4//
DO - 10.1111/j.1539-6924.2006.00743.x
VL - 26
IS - 2
SP - 483-500
SN - 1539-6924
KW - endocrine-active
KW - genistein
KW - PBPK
KW - phytoestrogen
KW - rat
ER -
TY - JOUR
TI - Communicating applied mathematics: Four examples
AU - Finkel, Daniel E.
AU - Kuster, Christopher
AU - Lasater, Matthew
AU - Levy, Rachel
AU - Reese, Jill P.
AU - Ipsen, Ilse C. F.
T2 - SIAM REVIEW
AB - Communicating Applied Mathematics is a writing- and speaking-intensive graduate course at North Carolina State University. The purpose of this article is to provide a brief description of the course objectives and the assignments. Parts A--D of of this article represent the class projects and illustrate the outcome of the course: We introduce a water-supply problem considered by the optimization and hydrology communities for benchmarking purposes. The objective is to drill five wells so that the cost of pumping water out of the ground is minimized. Using the implicit filtering optimization algorithm to locate the wells, we save approximately $2,500 over the cost of a given initial well configuration. The volume of powder poured into a bin with obstructions is found by calculating the height of the surface at every point. This is done using the fast marching algorithm. We look at two different bin geometries and determine the volumes as a function of the powder height under the spout. The surface of the powder satisfies a two-dimensional eikonal equation. This equation is solved using the fast marching method. Resonant tunneling diodes (RTDs) are ultrasmall semiconductor devices that have potential as very high-frequency oscillators. To describe the electron transport within these devices, physicists use the Wigner--Poisson equations which incorporate quantum mechanics to describe the distribution of electrons within the RTD. Continuation methods are employed to determine the steady-state electron distributions as a function of the voltage difference across the device. These simulations predict the operating state of the RTD under different applied voltages and will be a tool to help physicists understand how changing the voltage applied to the device leads to the development of current oscillations. When a thin film flows down an inclined plane, a bulge of fluid, known as a capillary ridge, forms on the leading edge and is subject to a fingering instability in which the fluid is channeled into rivulets. This process is familiar to us in everyday experiments such as painting a wall or pouring syrup over a stack of pancakes. It is also observed that changes in surface tension due to a temperature gradient can draw fluid up an inclined plane. Amazingly, in this situation the capillary ridge broadens and no fingering instability is observed. Numerical and analytical studies of a mathematical model of this process led to the discovery that these observations are associated with a nonclassical shock wave previously unknown to exist in thin liquid films.
DA - 2006/6//
PY - 2006/6//
DO - 10.1137/S0036144504443523
VL - 48
IS - 2
SP - 359-389
SN - 1095-7200
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33744925177&partnerID=MN8TOARS
KW - education
KW - mathematical writing
KW - presentations
KW - audience
KW - peer critique
ER -
TY - JOUR
TI - Hermitian tensor product approximation of complex matrices and separability
AU - Fei, SM
AU - Jing, NH
AU - Sun, BZ
T2 - REPORTS ON MATHEMATICAL PHYSICS
AB - The approximation of matrices to the sum of tensor products of Hermitian matrices is studied. A minimum decomposition of matrices on tensor space $H_1\otimes H_2$ in terms of the sum of tensor products of Hermitian matrices on $H_1$ and $H_2$ is presented. From this construction the separability of quantum states is discussed.
DA - 2006/4//
PY - 2006/4//
DO - 10.1016/S0034-4877(06)80021-2
VL - 57
IS - 2
SP - 271-288
SN - 0034-4877
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33745738544&partnerID=MN8TOARS
KW - separability
KW - matrix
KW - tensor product decomposition
ER -