TY - CHAP
TI - Algebraic algorithms
AU - Díaz, A.
AU - Kaltofen, E.
AU - Pan, V.
T2 - The computer science and engineering handbook
A2 - Tucker, A.B.
PY - 1997///
SP - 226–248
PB - CRC Press
SN - 9780849329098
ER -
TY - JOUR
TI - Immersed interface methods for moving interface problems
AU - Li, Zhilin
T2 - Numerical Algorithms
DA - 1997/5//
PY - 1997/5//
DO - 10.1023/A:1019173215885
VL - 14
SP - 269–293
KW - immersed interface method
KW - Stefan problem
KW - moving interface
KW - discontinuous coefficients
KW - singular source term
KW - immersed boundary method
KW - Cartesian grid
KW - heat conduction
ER -
TY - JOUR
TI - Front fixing vs. front tracking for diffusive transport with moving boundaries
AU - Heine, J. T.
AU - Li, Zhilin
AU - McTigue, D. F.
T2 - International Journal for Numerical & Analytical Methods in Geomechanics
DA - 1997///
PY - 1997///
VL - 21
SP - 653–662
ER -
TY - JOUR
TI - An Inverse Problem in a Parabolic Equation
AU - Li, Zhilin
AU - Zheng, K
T2 - Electronic Journal of Differential Equations
DA - 1997///
PY - 1997///
VL - 1
SP - 193–199
ER -
TY - CONF
TI - Mixed symbolic-numerical computations with general DAEs
AU - Campbell, Stephen L.
AU - Hollenbeck, R.
AU - Marszalek, W.
T2 - Symposium on Differential Algebraic Equations
C2 - 1997///
C3 - Proceedings of the Symposium on Differential-Algebraic Equations: Algebraic and Numerical Aspects
CY - Grenoble, France
DA - 1997///
PY - 1997/5/26/
SP - 23–34
ER -
TY - JOUR
TI - Observer design for linear time varying descriptor systems
AU - Campbell, Stephen L.
AU - Delebecque, F.
AU - Nikoukhah, R.
T2 - Proceedings of the Control Industrial Systems
DA - 1997///
PY - 1997///
VL - 1
SP - 507–512
ER -
TY - JOUR
TI - Highest weight modules of W_(1+∞), Darboux transformations and the bispectral problem
AU - Bakalov, B.
AU - Horozov, E.
AU - Yakimov, M.
T2 - Serdica Mathematical Journal
DA - 1997///
PY - 1997///
VL - 23
IS - 2
SP - 95–112
ER -
TY - BOOK
TI - Mechanisms for branching morphogenesis of the lung
AU - Lubkin, S. R.
A3 - Alt, W.
A3 - Deutsch, A.
A3 - Dunn, G.
DA - 1997///
PY - 1997///
PB -
SE - 229-234
UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000071666700027&KeyUID=WOS:000071666700027
ER -
TY - BOOK
TI - PASCO '97: Proceedings of the second international symposium on Parallel symbolic computation
A3 - Hong, Hoon
A3 - Kaltofen, Erich
A3 - Hitz, Markus
DA - 1997///
PY - 1997///
DO - 10.1145/266670
PB - ACM Press
SN - 0897919513 9780897919517
UR - http://dx.doi.org/10.1145/266670
ER -
TY - CONF
TI - Stress fluctuations in granular materials
AU - Schaeffer, D.G.
AU - Shearer, Michael
A2 - Chang, C.S.
A2 - Misra, A.
A2 - Liang, R.Y.
A2 - Babic, M.
C2 - 1997///
C3 - Mechanics of deformation and flow of particulate materials : proceedings of a symposium, Evanston, Illinois, June 29-July 2, 1997
DA - 1997///
PB - ASCE Publications
ER -
TY - CONF
TI - Models for stress fluctuations in plasticity
AU - Schaeffer, D.G.
AU - Shearer, Michael
T2 - International Conference on Powders & Grains
A2 - Behringer, R.P.
A2 - Jenkins, J.
C2 - 1997///
C3 - Powders & grains 97 : proceedings of the third International Conference on Powders & Grains, Durham, North Carolina, 18-23 May 1997
CY - Durham, North Carolina
DA - 1997///
PY - 1997/5/18/
SP - 325-328
PB - Balkema
ER -
TY - RPRT
TI - If a matrix has a single eigenvalue, how sensitive is this eigenvalue?
AU - Cho, G.E.
AU - Ipsen, I.C.F.
A3 - Center for Research in Scientific Computation, Department of Mathematics, North Carolina State University
DA - 1997///
PY - 1997///
M1 - CRSC-TR97-20
M3 - Technical Report
PB - Center for Research in Scientific Computation, Department of Mathematics, North Carolina State University
SN - CRSC-TR97-20
ER -
TY - JOUR
TI - Immersed Interface Methods for Stokes Flow with Elastic Boundaries or Surface Tension
AU - LeVeque, Randall J.
AU - Li, Zhilin
T2 - SIAM Journal on Scientific Computing
AB - A second-order accurate interface tracking method for the solution of incompressible Stokes flow problems with moving interfaces on a uniform Cartesian grid is presented. The interface may consist of an elastic boundary immersed in the fluid or an interface between two different fluids. The interface is represented by a cubic spline along which the singularly supported elastic or surface tension force can be computed. The Stokes equations are then discretized using the second-order accurate finite difference methods for elliptic equations with singular sources developed in our previous paper [SIAM J. Numer. Anal., 31(1994), pp. 1019--1044]. The resulting velocities are interpolated to the interface to determine the motion of the interface. An implicit quasi-Newton method is developed that allows reasonable time steps to be used.
DA - 1997/5//
PY - 1997/5//
DO - 10.1137/s1064827595282532
VL - 18
IS - 3
SP - 709-735
J2 - SIAM J. Sci. Comput.
LA - en
OP -
SN - 1064-8275 1095-7197
UR - http://dx.doi.org/10.1137/s1064827595282532
DB - Crossref
KW - Stokes flow
KW - creeping flow
KW - interface tracking
KW - discontinuous coefficients
KW - immersed interface methods
KW - Cartesian grids
KW - bubbles
ER -
TY - CONF
TI - Proceedings of the 2nd International Workshop on Parallel Symbolic
Computation, PASCO 1997, July 20-22, 1997, Kihei, Hawaii, USA
A2 - Hong, Hoon
A2 - Kaltofen, Erich
A2 - Hitz, Markus A.
C2 - 1997///
DA - 1997///
PB - ACM
ER -
TY - JOUR
TI - Multivariate Resultants Under Composition
AU - Hong, Hoon
DA - 1997/4//
PY - 1997/4//
VL - 4
SP -
ER -
TY - JOUR
TI - Subresultants Under Composition
AU - Hong, Hoon
T2 - Journal of Symbolic Computation
AB - Composition is an operation of replacing a variable in a polynomial with another polynomial. The main question of this paper is:What happens to subresultants under composition? The main contribution of the paper is to show that the subresultants ``almost'' commute with composition. This generalizes the well-known fact that the resultant is invariant under translation.
DA - 1997/4//
PY - 1997/4//
DO - 10.1006/jsco.1996.0093
VL - 23
IS - 4
SP - 355-365
UR - http://dx.doi.org/10.1006/jsco.1996.0093
ER -
TY - JOUR
TI - Implicitization of Nested Circular Curves
AU - HONG, HOON
T2 - Journal of Symbolic Computation
AB - A nested circular curve is a real plane curve traced by a point on a circle that rotates around another circle that again rotates around still another circle, and so on. In this paper, we give an efficient method for obtaining an implicit equation of a nested circular curve.
DA - 1997/2//
PY - 1997/2//
DO - 10.1006/jsco.1996.0082
VL - 23
IS - 2-3
SP - 177-189
UR - http://dx.doi.org/10.1006/jsco.1996.0082
ER -
TY - JOUR
TI - Testing Stability by Quantifier Elimination
AU - HONG, HOON
AU - LISKA, RICHARD
AU - STEINBERG, STANLY
T2 - Journal of Symbolic Computation
AB - For initial and initial-boundary value problems described by differential equations, stability requires the solutions to behave well for large times. For linear constant-coefficient problems, Fourier and Laplace transforms are used to convert stability problems to questions about roots of polynomials. Many of these questions can be viewed, in a natural way, as quantifier-elimination problems. The Tarski–Seidenberg theorem shows that quantifier-elimination problems are solvable in a finite number of steps. However, the complexity of this algorithm makes it impractical for even the simplest problems. The newer Quantifier Elimination by Partial Algebraic Decomposition (QEPCAD) algorithm is far more practical, allowing the solution of some non-trivial problems. In this paper, we show how to write all common stability problems as quantifier-elimination problems, and develop a set of computer-algebra tools that allows us to find analytic solutions to simple stability problems in a few seconds, and to solve some interesting problems in from a few minutes to a few hours.
DA - 1997/8//
PY - 1997/8//
DO - 10.1006/jsco.1997.0121
VL - 24
IS - 2
SP - 161-187
UR - http://dx.doi.org/10.1006/jsco.1997.0121
ER -
TY - JOUR
TI - Special Issue on Application of Quantifier Elimination. Foreword of the Guest Editors
AU - Hong, Hoon
AU - Liska, Richard
T2 - Journal of Symbolic Computation
AB - No abstract
DA - 1997/8//
PY - 1997/8//
DO - 10.1006/jsco.1997.0117
VL - 24
IS - 2
SP - 123
UR - http://dx.doi.org/10.1006/jsco.1997.0117
ER -
TY - JOUR
TI - Heuristic Search and Pruning in Polynomial Constraints Satisfaction.
AU - Hong, Hoon
T2 - Ann. Math. Artif. Intell.
DA - 1997/4//
PY - 1997/4//
DO - 10.1023/A:1018911907086
VL - 19
IS - 3-4
SP - 319-334
UR - https://doi.org/10.1023/A:1018911907086
ER -
TY - JOUR
TI - Comparison of Several Decision Algorithms for the Existential Theory of the Reals
AU - Hong, Hoon
DA - 1997/5//
PY - 1997/5//
VL - 5
SP -
ER -
TY - JOUR
TI - A Hybrid Method for Moving Interface Problems with Application to the Hele–Shaw Flow
AU - Hou, Thomas Y.
AU - Li, Zhilin
AU - Osher, Stanley
AU - Zhao, Hongkai
T2 - Journal of Computational Physics
AB - In this paper, a hybrid approach which combines theimmersed interface methodwith thelevel set approachis presented. The fast version of the immersed interface method is used to solve the differential equations whose solutions and their derivatives may be discontinuous across the interfaces due to the discontinuity of the coefficients or/and singular sources along the interfaces. The moving interfaces then are updated using the newly developed fast level set formulation which involves computation only inside some small tubes containing the interfaces. This method combines the advantage of the two approaches and gives a second-order Eulerian discretization for interface problems. Several key steps in the implementation are addressed in detail. This new approach is then applied to Hele–Shaw flow, an unstable flow involving two fluids with very different viscosity.
DA - 1997/7//
PY - 1997/7//
DO - 10.1006/jcph.1997.5689
VL - 134
IS - 2
SP - 236-252
J2 - Journal of Computational Physics
LA - en
OP -
SN - 0021-9991
UR - http://dx.doi.org/10.1006/jcph.1997.5689
DB - Crossref
ER -
TY - CHAP
TI - Formation of Shear Bands in Models of Granular Materials
AU - Shearer, M.
AU - Garaizar, F. X.
AU - Gordon, M. K.
T2 - IUTAM Symposium on Mechanics of Granular and Porous Materials
AB - In this paper we analyze the behavior of a granular material just prior to the appearance of a shear band. Shear band formation has long been associated with stress and strain localization — the deformation develops abruptly and locally near the site of the shear band (Rudnicki and Rice, 1975). It is also recognized that the phenomenon is connected with a change of type in the governing partial differential equations resulting from a continuum theory (Schaeffer, 1990).
PY - 1997///
DO - 10.1007/978-94-011-5520-5_31
SP - 343-352
OP -
PB - Springer Netherlands
SN - 9789401063241 9789401155205
UR - http://dx.doi.org/10.1007/978-94-011-5520-5_31
DB - Crossref
ER -
TY - CONF
TI - Fast polynomial factorization over high algebraic extensions of finite fields
AU - Kaltofen, Erich
AU - Shoup, Victor
T2 - the 1997 international symposium
AB - New algorithms are presented for factoring polynomials of degree n over the finite field of q elements, where q is a power of a fixed prime number. When log q = n, where a > 0 is constant, these algorithms are asymptotically faster than previous known algorithms, the fastest of which required time Ω(n(log q)), or Ω(n) in this case, which corresponds to the cost of computing x modulo an n degree polynomial. The new algorithms factor an arbitrary polynomial in time O(n+n). All measures are in fixed precision operations, that is in bit complexity. Moreover, in the special case where all the irreducible factors have the same degree, the new algorithms run in time O(n). In particular, one may test a polynomial for irreducibility in O(n) bit operations. These results generalize to the case where q = p, where p is a small prime number relative to q.
C2 - 1997///
C3 - Proceedings of the 1997 international symposium on Symbolic and algebraic computation - ISSAC '97
DA - 1997///
DO - 10.1145/258726.258777
PB - ACM Press
SN - 0897918754
UR - http://dx.doi.org/10.1145/258726.258777
DB - Crossref
ER -
TY - CONF
TI - On randomized Lanczos algorithms
AU - Eberly, Wayne
AU - Kaltofen, Erich
T2 - the 1997 international symposium
AB - Article Free Access Share on On randomized Lanczos algorithms Authors: Wayne Eberly Department of Computer Science, University of Calgary, Calgary, Alberta, Canada T2N 1N4 Department of Computer Science, University of Calgary, Calgary, Alberta, Canada T2N 1N4View Profile , Erich Kaltofen Department of Mathematics, North Carolina State University, Raleigh, North Carolina Department of Mathematics, North Carolina State University, Raleigh, North CarolinaView Profile Authors Info & Claims ISSAC '97: Proceedings of the 1997 international symposium on Symbolic and algebraic computationJuly 1997 Pages 176–183https://doi.org/10.1145/258726.258776Published:01 July 1997Publication History 23citation416DownloadsMetricsTotal Citations23Total Downloads416Last 12 Months41Last 6 weeks3 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF
C2 - 1997///
C3 - Proceedings of the 1997 international symposium on Symbolic and algebraic computation - ISSAC '97
DA - 1997///
DO - 10.1145/258726.258776
PB - ACM Press
SN - 0897918754
UR - http://dx.doi.org/10.1145/258726.258776
DB - Crossref
ER -
TY - JOUR
TI - The extent of early viral replication is a critical determinant of the natural history of simian immunodeficiency virus infection.
AU - Lifson, Jeffrey D
AU - Nowak, Martin A
AU - Goldstein, Simoy
AU - Rossio, Jeffrey L
AU - Kinter, Audrey
AU - Vasquez, Gabriela
AU - Wiltrout, Theresa A
AU - Brown, Charles
AU - Schneider, Douglas
AU - Wahl, Linda
AU - others
T2 - Journal of Virology
DA - 1997///
PY - 1997///
VL - 71
IS - 12
SP - 9508-9514
ER -
TY - RPRT
TI - Optimal Design of High Speed Mechanical Systems
AU - David, J W
AU - Cheng, C Y
AU - Choi, T D
AU - Kelley, C T
AU - Gablonsky, J
A3 - North Carolina State University, Center for Research in Scientific Computation
DA - 1997/7//
PY - 1997/7//
M1 - CRSC-TR97-18
PB - North Carolina State University, Center for Research in Scientific Computation
SN - CRSC-TR97-18
ER -
TY - JOUR
TI - Convex set theoretic image recovery by extrapolated iterations of parallel subgradient projections
AU - Combettes, P.L.
T2 - IEEE Transactions on Image Processing
AB - Solving a convex set theoretic image recovery problem amounts to finding a point in the intersection of closed and convex sets in a Hilbert space. The projection onto convex sets (POCS) algorithm, in which an initial estimate is sequentially projected onto the individual sets according to a periodic schedule, has been the most prevalent tool to solve such problems. Nonetheless, POCS has several shortcomings: it converges slowly, it is ill suited for implementation on parallel processors, and it requires the computation of exact projections at each iteration. We propose a general parallel projection method (EMOPSP) that overcomes these shortcomings. At each iteration of EMOPSP, a convex combination of subgradient projections onto some of the sets is formed and the update is obtained via relaxation. The relaxation parameter may vary over an iteration-dependent, extrapolated range that extends beyond the interval [0,2] used in conventional projection methods. EMOPSP not only generalizes existing projection-based schemes, but it also converges very efficiently thanks to its extrapolated relaxations. Theoretical convergence results are presented as well as numerical simulations.
DA - 1997/4//
PY - 1997/4//
DO - 10.1109/83.563316
VL - 6
IS - 4
SP - 493-506
J2 - IEEE Trans. on Image Process.
OP -
SN - 1057-7149
UR - http://dx.doi.org/10.1109/83.563316
DB - Crossref
ER -
TY - JOUR
TI - Hilbertian convex feasibility problem: Convergence of projection methods
AU - Combettes, P. L.
T2 - Applied Mathematics & Optimization
DA - 1997/5//
PY - 1997/5//
DO - 10.1007/bf02683333
VL - 35
IS - 3
SP - 311-330
J2 - Appl Math Optim
LA - en
OP -
SN - 0095-4616 1432-0606
UR - http://dx.doi.org/10.1007/bf02683333
DB - Crossref
ER -
TY - JOUR
TI - Viral dynamics of primary viremia and antiretroviral therapy in simian immunodeficiency virus infection
AU - Nowak, M.A.
AU - Lloyd, A.L.
AU - Vasquez, G.M.
AU - Wiltrout, T.A.
AU - Wahl, L.M.
AU - Bischofberger, N.
AU - Williams, J.
AU - Kinter, A.
AU - Fauci, A.S.
AU - Hirsch, V.M.
AU - Lifson, J.D.
T2 - Journal of Virology
DA - 1997///
PY - 1997///
VL - 71
IS - 10
SP - 7518–7525
ER -
TY - JOUR
TI - Presence of an inducible HIV-1 latent reservoir during highly active antiretroviral therapy
AU - Chun, T.-W.
AU - Stuyver, L.
AU - Mizell, S. B.
AU - Ehler, L. A.
AU - Mican, J. A. M.
AU - Baseler, M.
AU - Lloyd, A. L.
AU - Nowak, M. A.
AU - Fauci, A. S.
T2 - Proceedings of the National Academy of Sciences
AB - Although highly active antiretroviral therapy (HAART) in the form of triple combinations of drugs including protease inhibitors can reduce the plasma viral load of some HIV-1-infected individuals to undetectable levels, it is unclear what the effects of these regimens are on latently infected CD4+ T cells and what role these cells play in the persistence of HIV-1 infection in individuals receiving such treatment. The present study demonstrates that highly purified CD4+ T cells from 13 of 13 patients receiving HAART with an average treatment time of 10 months and with undetectable (<500 copies HIV RNA/ml) plasma viremia by a commonly used bDNA assay carried integrated proviral DNA and were capable of producing infectious virus upon cellular activation in vitro. Phenotypic analysis of HIV-1 produced by activation of latently infected CD4+ T cells revealed the presence in some patients of syncytium-inducing virus. In addition, the presence of unintegrated HIV-1 DNA in infected resting CD4+ T cells from patients receiving HAART, even those with undetectable plasma viremia, suggests persistent active virus replication in vivo.
DA - 1997/11/25/
PY - 1997/11/25/
DO - 10.1073/pnas.94.24.13193
VL - 94
IS - 24
SP - 13193-13197
J2 - Proceedings of the National Academy of Sciences
LA - en
OP -
SN - 0027-8424 1091-6490
UR - http://dx.doi.org/10.1073/pnas.94.24.13193
DB - Crossref
ER -
TY - JOUR
TI - Damage Detection as Inverse Problems for Distributed Parameter Systems: Computational Approaches
AU - Banks, H.T.
AU - Smith, R.C.
AU - Zhang, Y.
T2 - International Journal of Applied Electromagnetics and Mechanics
DA - 1997///
PY - 1997///
VL - 8
SP - 61–76
ER -
TY - JOUR
TI - Numerical Recovery of Material Parameters in Euler-Bernoulli Beam Models
AU - Smith, R.C.
AU - Bowers, K.L.
AU - Vogel, C.R.
T2 - Journal of Mathematical Systems, Estimation and Control
DA - 1997///
PY - 1997///
VL - 7
IS - 2
SP - 157–195
ER -
TY - JOUR
TI - Bispectral Algebras of Commuting Ordinary Differential Operators
AU - Bakalov, B.
AU - Horozov, E.
AU - Yakimov, M.
T2 - Communications in Mathematical Physics
AB - We develop a systematic way for constructing bispectral algebras of commuting ordinary differential operators of any rank N. It combines and unifies the ideas of Duistermaat–Grünbaum and Wilson. Our construction is completely algorithmic and enables us to obtain all previously known classes or individual examples of bispectral operators. The method also provides new broad families of bispectral algebras which may help to penetrate deeper into the problem.
DA - 1997/12/1/
PY - 1997/12/1/
DO - 10.1007/s002200050244
VL - 190
IS - 2
SP - 331-373
J2 - Communications in Mathematical Physics
OP -
SN - 0010-3616 1432-0916
UR - http://dx.doi.org/10.1007/s002200050244
DB - Crossref
ER -
TY - JOUR
TI - Bispectrum and Analysis of the Statistics of Electromagnetic Waves Backscattered by Sea Surface
AU - Gilman, M.A.
T2 - Journal of Computer and System Sciences International
DA - 1997///
PY - 1997///
VL - 36
IS - 6
SP - 972–980
ER -
TY - CHAP
TI - Analytic approximations to the deformation of a thin compressible elastic layer by a rigid indenter
AU - Haider, M.A.
AU - Holmes, M.H.
T2 - Applied Mathematics: Methods and Applications
A2 - Oyibo, G.
PY - 1997///
SP - 257–288
PB - Nova Science
ER -
TY - JOUR
TI - The extent of early viral replication is a critical determinant of the natural history of simian immunodeficiency virus infection
AU - Lifson, J.D.
AU - Nowak, M.A.
AU - Goldstein, S.
AU - Rossio, J.L.
AU - Kinter, A.
AU - Vasquez, G.
AU - Wiltrout, T.A.
AU - Brown, C.
AU - Schneider, D.
AU - Wahl, L.
AU - Lloyd, A.L.
AU - Williams, J.
AU - Elkins, W.R.
AU - Fauci, A.S.
AU - Hirsch, V.M.
T2 - Journal of Virology
DA - 1997///
PY - 1997///
VL - 71
IS - 12
SP - 9508–9514
ER -
TY - JOUR
TI - A Galerkin Method for Linear PDE Systems in Circular Geometries with Structural Acoustic Problems
AU - Smith, Ralph C.
T2 - SIAM Journal on Scientific Computing
AB - A Galerkin method for systems of PDEs in circular geometries is presented with motivating problems being drawn from structural, acoustic, and structural acoustic applications. Depending upon the application under consideration, piecewise splines or Legendre polynomials are used when approximating the system dynamics with modifications included to incorporate the analytic solution decay near the coordinate singularity. This provides an efficient method which retains its accuracy throughout the circular domain without degradation at the singularity. Because the problems under consideration are linear or weakly nonlinear with constant or piecewise constant coefficients, transform methods for the problems are not investigated. While the specific method is developed for the 2-D wave equation on a circular domain and the equation of transverse motion for a thin circular plate, examples demonstrating the extension of the techniques to a fully coupled structural acoustic system are used to illustrate the flexibility of the method when approximating the dynamics of more complex systems.
DA - 1997/3//
PY - 1997/3//
DO - 10.1137/s1064827594268531
VL - 18
IS - 2
SP - 371-402
J2 - SIAM J. Sci. Comput.
LA - en
OP -
SN - 1064-8275 1095-7197
UR - http://dx.doi.org/10.1137/s1064827594268531
DB - Crossref
KW - Galerkin method
KW - PDEs in circular geometries
KW - structural acoustics
ER -
TY - JOUR
TI - THE ESTIMATION OF MATERIAL AND PATCH PARAMETERS IN A PDE-BASED CIRCULAR PLATE MODEL
AU - Banks, H.T.
AU - Smith, R.C.
AU - Brown, D.E.
AU - Metcalf, V.L.
AU - Silcox, R.J.
T2 - Journal of Sound and Vibration
AB - The estimation of material and patch parameters for a system involving a circular plate, to which piezoceramic are bonded, is considered. A partial differential equation (PDE) model for the thin circular plate is used with the passive and active contributions from the patches included in the internal and external bending moments. This model contains piecewise constant parameters describing the density, flexural rigidity, Poisson ratio and Kelvin-Voigt damping for the system, as well as patch constants and a coefficient for viscous air damping. Examples demonstrating the estimation of these parameters with experimental acceleration data and a variety of inputs to the experimental plate are presented. By using a physically derived PDE model to describe the system, parameter sets consistent across experiments are obtained, even when phenomena such as damping due to electric circuits affect the system dynamics.
DA - 1997/2//
PY - 1997/2//
DO - 10.1006/jsvi.1996.0649
VL - 199
IS - 5
SP - 777-799
J2 - Journal of Sound and Vibration
LA - en
OP -
SN - 0022-460X
UR - http://dx.doi.org/10.1006/jsvi.1996.0649
DB - Crossref
ER -
TY - JOUR
TI - Artificial Boundary Conditions for Computation of Oscillating External Flows
AU - Tsynkov, S. V.
T2 - SIAM Journal on Scientific Computing
AB - In this paper, we propose a new technique for the numerical treatment of external flow problems with oscillatory behavior of the solution in time. Specifically, we consider the case of unbounded compressible viscous plane flow past a finite body (airfoil). Oscillations of the flow in time may be caused, for example, by the time-periodic injection of fluid into the boundary layer, which in accordance with experimental data, may essentially increase the performance of the airfoil. To conduct the actual computations, we have to somehow restrict the original unbounded domain, that is, to introduce an artificial (external) boundary and to further consider only a finite computational domain. Consequently, we will need to formulate some artificial boundary conditions (ABCs) at the introduced external boundary. The ABCs we are aiming to obtain must meet the following fundamental requirement. One should be able to uniquely complement the solution calculated inside the finite computational domain to its infinite exterior so that the original problem is solved within the desired accuracy. Our construction of such ABCs for oscillating flows is based on an essential assumption: the Navier--Stokes equations can be linearized in the far field against the free-stream background. To actually compute the ABCs, we represent the far-field solution as a Fourier series in time and then apply the difference potentials method (DPM) of V. S. Ryaben'kii. This paper contains a general theoretical description of the algorithm for setting the DPM-based ABCs for time-periodic external flows. Based on our experience in implementing analogous ABCs for steady-state problems (a simpler case), we expect that these boundary conditions will become an effective tool for constructing robust numerical methods to calculate oscillatory flows.
DA - 1997/11//
PY - 1997/11//
DO - 10.1137/s1064827595291145
VL - 18
IS - 6
SP - 1612-1656
J2 - SIAM J. Sci. Comput.
LA - en
OP -
SN - 1064-8275 1095-7197
UR - http://dx.doi.org/10.1137/s1064827595291145
DB - Crossref
KW - oscillating flows
KW - artificial boundary conditions
KW - boundary equations with projections
KW - auxiliary problem
KW - difference potentials method
ER -
TY - THES
TI - Analysis of partial differential algebraic equations
AU - Marszalek, Wieslaw
DA - 1997///
PY - 1997///
PB - Raleigh: North Carolina State University
ER -
TY - JOUR
TI - Instantaneous multiple depth soil mechanical impedance sensing from a moving vehicle
AU - Chukwu, E.
AU - Bowers, C. G.
T2 - Paper (American Society of Agricultural Engineers)
DA - 1997///
PY - 1997///
IS - 971077
SP - 23
ER -
TY - BOOK
TI - Computer modeling : from sports to spaceflight--from order to chaos
AU - Danby, J. M. A.
DA - 1997///
PY - 1997///
PB - Richmond, VA: Willmann-Bell
SN - 0943396514
ER -
TY - JOUR
TI - Generalized polynomial bases and the Bezoutian
AU - Mani, V
AU - Hartwig, RE
T2 - LINEAR ALGEBRA AND ITS APPLICATIONS
AB - A foundation polynomial is used to induce polynomial bases for Fn−1[x], the vector space of polynomials of degree less than n over an arbitrary field F. The associated bases are then used to block diagonalize the Bezout matrix of two polynomials under congruence.
DA - 1997/1/15/
PY - 1997/1/15/
DO - 10.1016/0024-3795(95)00585-4
VL - 251
SP - 293-320
SN - 0024-3795
ER -
TY - JOUR
TI - Use of an epidemiologic model to evaluate feline leukemia virus control measures
AU - Romatowski, J.
AU - Lubkin, S. R.
T2 - Feline Practice
DA - 1997///
PY - 1997///
VL - 25
IS - 4
SP - 6-11
UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:A1997XU72500002&KeyUID=WOS:A1997XU72500002
ER -
TY - JOUR
TI - Mechanisms for Branching Morphogenesis of the Lung
AU - Lubkin, Sharon R.
T2 - Dynamics of Cell and Tissue Motion
AB - The human lung is a dichotomously branched, hollow structure, which forms in a similar manner to other glandular organs such as the kidney, pancreas, mammary and salivary glands. A hollow finger of epithelium grows into surrounding mesenchyme, and branches repeatedly, over some 23 generations. In turn, the surrounding mesenchyme condenses around the epithelium. Although a great deal is known about branching morphogenesis, primarily from studies of the mouse submandibular gland, branching is not a fully understood process.
CN - QH647 .D96 1997
DA - 1997///
PY - 1997///
DO - 10.1007/978-3-0348-8916-2_27
SP - 229-234
ER -
TY - CHAP
TI - Dynamics within tissues stresses, growth, and morphogenesis
AU - Lubkin, S. R.
AU - Beloussov, L. V.
T2 - Dynamics of cell and tissue motion
A2 - W. Alt, A. Deutsch
A2 - Dunn, G.
CN - QH647 .D96 1997
PY - 1997///
SP - 211-284
PB - Basel: Birkhauser Verlag
ER -
TY - JOUR
TI - Limit theorems and a general framework for risk analysis in clonal forestry
AU - Bishir, J
AU - Roberds, J
T2 - MATHEMATICAL BIOSCIENCES
AB - Use of clonally propagated plantings in reforestation offers management advantages of phenotypic uniformity and high yields. Disadvantages include low genetic diversity and the possibility that the clone or clones chosen are particularly susceptible to attack by an insect or pathogen unforeseen as a problem at the time of clonal selection. In this paper, we continue consideration of the problem of choosing an optimal number of clones to minimize the risk of plantation failure. We present an analysis in which risk of failure for a plantation is represented by the probability that the proportion, S, of ramets that survive until harvest is less than or equal to a prescribed value. Our approach includes most earlier treatments as special cases. We show that the proportion S converges in distribution and, furthermore, that, under general conditions, a moderate number of clones, usually no more than 20 to 40 and often fewer, provides equivalent or better protection against catastrophic loss than does a large number of clones.
DA - 1997/5//
PY - 1997/5//
DO - 10.1016/S0025-5564(96)00184-8
VL - 142
IS - 1
SP - 1-11
SN - 0025-5564
ER -
TY - JOUR
TI - Response of ovule development and post-pollen production processes in male-sterile tomatoes to chronic, sub-acute high temperature stress
AU - Peet, MM
AU - Willits, DH
AU - Gardner, R
T2 - JOURNAL OF EXPERIMENTAL BOTANY
AB - In order to determine the effects of high temperature on ovule development and reproductive processes subsequent to pollen production, nine day/night temperature combinations were imposed over a 9 month period as four separate experiments, each with three treatments, including one common treatment. In order to eliminate known effects of high temperatures on pollen production and stylar position, high temperature treatments were applied only to male-sterile tomatoes (Lycopersicon esculentum Mill.). Pollen was obtained from male-fertile plants given optimal growth conditions. This allowed comparison of mean daily temperatures from 25–29 °C; day/night temperature differentials (DIFs) of 2, 6, and 10°C; day temperatures of 28, 30 and 32°C at night temperatures of 22, 24, and 26°C; and night temperatures of 22, 24 and 26°C at day temperatures of 28, 30 and 32°C. Average weight per fruit and flower number did not demonstrate a consistent pattern of response to high temperature. Other reproductive characteristics (% fruitset, total number and weight of fruit per plant, and seediness index) decreased as mean daily temperature rose from 25°C to 26°C and from 28°C to 29°C. The primary parameter affecting these variables was mean daily temperature, with day temperature having a secondary role. Thus, in determining reproductive responses of tomato to temperatures within this range, day temperature, night temperature and DIFs do not need to be considered independently of their effect on mean daily temperature. If this relationship holds true in other species, and for pre-pollen production pro- cesses as well, modelling the effects of projected climate change should be simplified.
DA - 1997/1//
PY - 1997/1//
DO - 10.1093/jxb/48.1.101
VL - 48
IS - 306
SP - 101-111
SN - 0022-0957
KW - global climate change
KW - thermotolerance
KW - stress resistance
KW - ovule development
KW - pollination
ER -
TY - JOUR
TI - Principles of competitive exclusion for discrete populations with reproducing juveniles and adults
AU - Franke, JE
AU - Yakubu, AA
T2 - NONLINEAR ANALYSIS-THEORY METHODS & APPLICATIONS
AB - We invent notions of dominance and weak dominance for discrete multi-species systems with competing juveniles and adults. In this model, both the juveniles and adults are allowed to reproduce. We prove that, a dominant species drives the dominated species to extinction. In discrete juvenile-adult systems that do not allow juveniles to reproduce, it is known that weak dominance is equivalent to dominance, provided all the growth functions are exponentials. We show that if juveniles are allowed to reproduce, then a weakly dominant species could be driven to extinction. It all the growth functions are exponential functions, we obtain sufficient conditions that guarantee the equivalence of weak dominance and dominance.
DA - 1997/12//
PY - 1997/12//
DO - 10.1016/S0362-546X(97)00299-X
VL - 30
IS - 2
SP - 1197-1205
SN - 0362-546X
ER -
TY - JOUR
TI - Plane shear waves in a fully saturated granular medium with velocity and stress controlled boundary conditions
AU - Gordon, MS
AU - Shearer, M
AU - Schaeffer, D
T2 - INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
AB - A one-dimensional system describing small shearing disturbances in a semi-infinite, fully saturated granular medium is studied. The system is fully non-linear as a result of the incrementally non-linear constitutive law for the material. In particular, there are two different wave speeds corresponding to loading or unloading of the material. Global solutions are constructed with boundary data consisting of a single pulse in either velocity or stress. In the case of velocity controlled boundary conditions, the solution is a traveling pulse of increasing kinetic energy which eventually unloads the material, regardless of whether the initial pulse loads or unloads. The solution with stress controlled boundary conditions has these features only if the initial stress pulse unloads the material. If the initial stress pulse is loading then the solution is a slowly traveling pulse of decreasing kinetic energy which is also loading.
DA - 1997/5//
PY - 1997/5//
DO - 10.1016/S0020-7462(96)00080-7
VL - 32
IS - 3
SP - 489-503
SN - 0020-7462
KW - plane shear waves
KW - saturated granular material
KW - hypoplastic flow rule
KW - scale-invariant problem
KW - characteristic wave
KW - shock wave
KW - rarefaction wave
KW - wave curve
KW - state space
KW - kinetic energy
ER -
TY - JOUR
TI - Identification of hysteretic control influence operators representing smart actuators part I: Formulation
AU - Banks, HT
AU - Kurdila, AJ
AU - Webb, G
T2 - MATHEMATICAL PROBLEMS IN ENGINEERING
AB - A large class of emerging actuation devices and materials exhibit strong hysteresis characteristics during their routine operation. For example, when piezoceramic actuators are operated under the influence of strong electric fields, it is known that the resulting input–output behavior is hysteretic. Likewise, when shape memory alloys are resistively heated to induce phase transformations, the input–output response at the structural level is also known to be strongly hysteretic. This paper investigates the mathematical issues that arise in identifying a class of hysteresis operators that have been employed for modeling both piezoceramic actuation and shape memory alloy actuation. Specifically, the identification of a class of distributed hysteresis operators that arise in the control influence operator of a class of second order evolution equations is investigated. In Part I of this paper we introduce distributed,hysteretic control influence operators derived from smoothed Preisach operators and generalized hysteresis operators derived from results of Krasnoselskii and Pokrovskii. For these classes, the identification problem in which we seek to characterize the hysteretic control influence operator can be expressed as an ouput least square minimization over probability measures defined on a compact subset of a closed half-plane. In Part II of this paper, consistent and convergent approximation methods for identification of the measure characterizing the hysteresis are derived.
DA - 1997///
PY - 1997///
DO - 10.1155/S1024123X97000586
VL - 3
IS - 4
SP - 287-328
SN - 1024-123X
KW - hysteretic Preisach operators
KW - smart materials
KW - evolution equations
KW - identification
ER -
TY - JOUR
TI - Dynamics of reaction-diffusion systems and applications
AU - Pao, CV
T2 - NONLINEAR ANALYSIS-THEORY METHODS & APPLICATIONS
AB - The dynamics of a system of arbitrary number of nonlinear parabolic equations in terms of the quasisolutions of the corresponding system of elliptic equations is discussed. The conclusions for the general system are used to study the coexistence and permanence of a three-species predator-prey model and a food-chain model arising from ecology.
DA - 1997/12//
PY - 1997/12//
DO - 10.1016/S0362-546X(97)00350-7
VL - 30
IS - 6
SP - 3371-3377
SN - 0362-546X
ER -
TY - JOUR
TI - The influence of material non-uniformity preceding shear-band formation in a model for granular flow
AU - Schaeffer, DG
AU - Shearer, M
T2 - EUROPEAN JOURNAL OF APPLIED MATHEMATICS
AB - The onset of shear-banding in a deforming elastoplastic solid has been linked to change of type of the governing partial differential equations. If uniform material properties are assumed, then (i) deformations prior to shear-banding are uniform, and (ii) the onset of shear-banding occurs simultaneously at all points in the sample. In this paper we study, in the context of a model for anti-plane shearing of a granular material, the effect of a small variation in material properties (e.g. in yield strength) within the sample. Using matched asymptotic expansions, we find that (i) the deformation is extremely non-uniform in a short time period immediately preceding the formation of shear-bands; and (ii) generically, a shear-band forms at a single location in the sample.
DA - 1997/10//
PY - 1997/10//
DO - 10.1017/S0956792597003070
VL - 8
IS - 1997 Oct.
SP - 457-483
SN - 0956-7925
ER -
TY - JOUR
TI - Spline approximation of thin shell dynamics
AU - Rosario, R. C. Del
AU - Smith, Ralph
T2 - International Journal for Numerical Methods in Engineering
AB - A spline-based method for approximating thin shell dynamics is presented here. While the method is developed in the context of the Donnell–Mushtari thin shell equations, it can be easily extended to the Byrne–Flügge–Lur'ye equations or other models for shells of revolution as warranted by applications. The primary requirements for the method include accuracy, flexibility and efficiency in smart material applications. To accomplish this, the method was designed to be flexible with regard to boundary conditions, material non-homogeneities due to sensors and actuators, and inputs from smart material actuators such as piezoceramic patches. The accuracy of the method was also of primary concern, both to guarantee full resolution of structural dynamics and to facilitate the development of PDE-based controllers which ultimately require real-time implementation. Several numerical examples provide initial evidence demonstrating the efficacy of the method. © 1997 John Wiley & Sons, Ltd.
DA - 1997///
PY - 1997///
DO - 10.1002/(sici)1097-0207(19970815)40:15<2807::aid-nme192>3.0.co;2-h
VL - 40
IS - 15
SP - 2807–2840
ER -
TY - CONF
TI - Radiative transfer with asymmetric ground reflection
AU - Barichello, L. B.
AU - Garcia, R. D. M.
AU - Siewert, C. E.
C2 - 1997///
C3 - Proceedings of the 2nd Italian-Latinamerican Conference on Applied and Industrial Mathematics - ITLA 97, Roma, 1997
DA - 1997///
SP - 13
M1 - 1997
ER -
TY - CHAP
TI - Nonlinear delay differential economic systems in W-2((1))
AU - Chukwu, E. N.
T2 - Advances in nonlinear dynamics
A2 - S. Sivasundaram,
A2 - Martynyuk, A. A.
CN - QA845 .A35 1997
PY - 1997///
SP - 157-170
PB - Australia: Gordon and Breach
ER -
TY - CHAP
TI - Dynamics of weakly coupled parabolic systems with nonlocal boundary conditions
AU - Pao, C. V.
T2 - Advances in nonlinear dynamics
A2 - S. Sivasundaram,
A2 - Martynyuk, A. A.
CN - QA845 .A35 1997 [Hill]
PY - 1997///
VL - 5
SP - 319-327
PB - Australia: Gordon and Breach
ER -
TY - JOUR
TI - On the convergence of power scaled Cesaro sums
AU - Chen, XZ
AU - Hartwig, RE
T2 - LINEAR ALGEBRA AND ITS APPLICATIONS
AB - Power scaling is combined with Cesáro summation, and necessary and sufficient local conditions are given for the resulting matrix sequence JN(T) to converge. It is shown that this convergence is closely related to path conditions on the one hand as well as suitable bilinear consistency conditions on the other hand.
DA - 1997/12//
PY - 1997/12//
DO - 10.1016/S0024-3795(97)80056-0
VL - 267
SP - 335-358
SN - 0024-3795
ER -
TY - JOUR
TI - On a variational formulation of the generalized singular value decomposition
AU - Chu, MT
AU - Funderlic, RE
AU - Golub, GH
T2 - SIAM JOURNAL ON MATRIX ANALYSIS AND APPLICATIONS
AB - A variational formulation for the generalized singular value decomposition (GSVD) of a pair of matrices $A \in R^{m \times n}$ and $B \in R^{p \times n}$ is presented. In particular, a duality theory analogous to that of the SVD provides new understanding of left and right generalized singular vectors. It is shown that the intersection of row spaces of A and B plays a key role in the GSVD duality theory. The main result that characterizes left GSVD vectors involves a generalized singular value deflation process.
DA - 1997/10//
PY - 1997/10//
DO - 10.1137/S0895479895287079
VL - 18
IS - 4
SP - 1082-1092
SN - 0895-4798
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0031520186&partnerID=MN8TOARS
KW - generalized eigenvalue and eigenvector
KW - generalized singular value and singular vector
KW - stationary value and stationary point
KW - deflation
KW - duality
ER -
TY - JOUR
TI - Hydrogen transfer between methanogens and fermentative heterotrophs in hyperthermophilic cocultures
AU - Muralidharan, V.
AU - Rinker, K. D.
AU - Hirsh, I. S.
AU - Bouwer, E. J.
AU - Kelly, R. M.
T2 - Biotechnology and Bioengineering
AB - Interactions involving hydrogen transfer were studied in a coculture of two hyperthermophilic microorganisms: Thermotoga maritima, an anaerobic heterotroph, and Methanococcus jannaschii, a hydrogenotrophic methanogen. Cell densities of T. maritima increased 10-fold when cocultured with M. jannaschii at 85°C, and the methanogen was able to grow in the absence of externally supplied H2 and CO2. The coculture could not be established if the two organisms were physically separated by a dialysis membrane, suggesting the importance of spatial proximity. The significance of spatial proximity was also supported by cell cytometry, where the methanogen was only found in cell sorts at or above 4.5 μm in samples of the coculture in exponential phase. An unstructured mathematical model was used to compare the influence of hydrogen transport and metabolic properties on mesophilic and hyperthermophilic cocultures. Calculations suggest the increases in methanogenesis rates with temperature result from greater interactions between the methanogenic and fermentative organisms, as evidenced by the sharp decline in H2 concentration in the proximity of a hyperthermophilic methanogen. The experimental and modeling results presented here illustrate the need to consider the interactions within hyperthermophilic consortia when choosing isolation strategies and evaluating biotransformations at elevated temperatures. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 268–278, 1997.
DA - 1997///
PY - 1997///
DO - 10.1002/(sici)1097-0290(19971105)56:3<268::aid-bit4>3.0.co;2-h
VL - 56
IS - 3
SP - 268-278
ER -
TY - JOUR
TI - Analysis and approximation of optimal control problems for a simplified Ginzburg-Landau model of superconductivity
AU - Gunzburger, MD
AU - Hou, LS
AU - Ravindran, SS
T2 - NUMERISCHE MATHEMATIK
DA - 1997/8//
PY - 1997/8//
DO - 10.1007/s002110050285
VL - 77
IS - 2
SP - 243-268
SN - 0029-599X
ER -
TY - JOUR
TI - Accurate and economical solution of the pressure-head form of Richards' equation by the method of lines
AU - Tocci, MD
AU - Kelley, CT
AU - Miller, CT
T2 - ADVANCES IN WATER RESOURCES
AB - The pressure-head form of Richards' equation (RE) is difficult to solve accurately using standard time integration methods. For example, mass balance errors grow as the integration progresses unless very small time steps are taken. Further, RE may be solved for many problems more economically and robustly with variable-size time steps rather than with a constant time-step size, but variable step-size methods applied to date have relied upon empirical approaches to control step size, which do not explicitly control temporal truncation error of the solution. We show how a differential algebrain equation implementation of the method of lines can give solutions to RE that are accurate, have good mass balance properties, explicitly control temporal truncation error, and are more economical than standard approaches for a wide range of solution accuracy. We detail changes to a standard integrator, DASPK, that improves efficiency for the test problems considered, and we advocate the use of this approach for both RE and other problems involving subsurface flow and transport phenomena.
DA - 1997/2//
PY - 1997/2//
DO - 10.1016/S0309-1708(96)00008-5
VL - 20
IS - 1
SP - 1-14
SN - 0309-1708
ER -
TY - JOUR
TI - The solution operator in W-p((1)) for systems of neutral type
AU - Chukwu, EN
AU - Simpson, HC
T2 - NONLINEAR ANALYSIS-THEORY METHODS & APPLICATIONS
DA - 1997/11//
PY - 1997/11//
DO - 10.1016/S0362-546X(96)00169-1
VL - 29
IS - 10
SP - 1173-1195
SN - 0362-546X
KW - neutral functional differential equation
KW - atomic Sobolev space
KW - solution operator
ER -
TY - JOUR
TI - The role of orography in determining the Sahelian climate
AU - Semazzi, FHM
AU - Sun, LQ
T2 - INTERNATIONAL JOURNAL OF CLIMATOLOGY
AB - We have examined numerical modelling evidence based on the NASA GEOS-1 general circulation model in order to investigate the role of orography in determining the West African summer climate anomalies. Orographic climatic control and the influence of sea-surface temperature (SST) anomaly forcing were investigated by systematic suppression or inclusion of these effects in the numerical experiments. Our main finding is that the orography of Africa plays a major role in determining the climate of the Sahel and the coastal region of West Africa during the northern hemispheric summer season. These orographic effects are comprised of: (i) a quasi-stationary orographic ridge–trough dipole generated by the passage of the low-level prevailing easterlies over the Atlas–Ahaggar mountain complex over northern Africa, and (ii) an elongated zonal windward orographic ridge generated as the cross-equatorial summer monsoons from the South Atlantic Ocean basin ascends over the elevated landmass of West Africa. Over the Sahel, the moist south-westerly flow emanating from the Atlas–Ahaggar orographic trough over the Atlantic Ocean and the dry hot north-easterlies originating from the corresponding orographic windward ridge tend to converge along a zonal axis thus reinforcing the Inter-Tropical Convergence Zone. This results in wetter conditions over the Sahel than would have been the case in the absence of orography. The model simulations show that further to the south along the coastal region of West Africa, the zonal orographic ridge results in drier conditions than in the model runs when orography is suppressed. The net result is a permanent orographic-induced rainfall dipole pattern over West Africa. Further model simulations were conducted in which the 1973 SST anomaly conditions were described with or without the orography of Africa. The 1973 SST anomaly pattern is characterized by positive anomalies in the Southern Hemisphere and negative anomalies in the Northern Hemisphere. The model results show a weaker orographic-induced rainfall dipole pattern across West Africa in response to the 1973 SST anomaly pattern. The net result is wetter conditions along the coastal region and rainfall deficits over the Sahelian zonal strip. © 1997 by the Royal Meteorological Society.
DA - 1997/5//
PY - 1997/5//
DO - 10.1002/(SICI)1097-0088(199705)17:6<581::AID-JOC134>3.0.CO;2-E
VL - 17
IS - 6
SP - 581-596
SN - 0899-8418
KW - Sahel
KW - orography
KW - summer climate anomalies
KW - NASA GEOS-1 GCM
ER -
TY - JOUR
TI - Period-doubling bifurcations for systems of difference equations and applications to models in population biology
AU - Selgrade, JF
AU - Roberds, JH
T2 - NONLINEAR ANALYSIS-THEORY METHODS & APPLICATIONS
DA - 1997/7//
PY - 1997/7//
DO - 10.1016/S0362-546X(96)00041-7
VL - 29
IS - 2
SP - 185-199
SN - 1873-5215
KW - discrete models
KW - period-doubling bifurcation
KW - Henon map
KW - population genetics
KW - pioneer and climax populations
ER -
TY - JOUR
TI - Numerical solutions of optimal control for thermally convective flows
AU - Ravindran, S. S.
T2 - International Journal for Numerical Methods in Fluids
DA - 1997///
PY - 1997///
VL - 25
IS - 2
SP - 205-223
ER -
TY - JOUR
TI - Modeling aggregation and growth processes in an algal population model: Analysis and computations
AU - Ackleh, AS
AU - Fitzpatrick, BG
T2 - JOURNAL OF MATHEMATICAL BIOLOGY
AB - Aggregation, the formation of large particles through multiple collision of smaller ones is a highly visible phenomena in oceanic waters which can control material flux to the deep sea. Oceanic aggregates more than 1 cm in diameter have been observed and are frequently described to consist of phytoplankton cells as well as other organic matter such as fecel pellets and mucus nets from pteropods. Division of live phytoplankton cells within an aggregate can also increase the size of aggregate (assuming some daughter cells stay in the aggregate) and hence could be a significant factor in speeding up the formation process of larger aggregate. Due to the difficulty of modeling cell division within aggregates, few efforts have been made in this direction. In this paper, we propose a size structured approach that includes growth of aggregate size due to both cell division and aggregation. We first examine some basic mathematical issues associated with the development of a numerical simulation of the resulting algal aggregation model. The numerical algorithm is then used to examine the basic model behavior and present a comparison between aggregate distribution with and without division in aggregates. Results indicate that the inclusion of a growth term in aggregates, due to cell division, results in higher densities of larger aggregates; hence it has the impact to speed clearance of organic matter from the surface layer of the ocean.
DA - 1997/3//
PY - 1997/3//
DO - 10.1007/s002850050062
VL - 35
IS - 4
SP - 480-502
SN - 0303-6812
KW - phytoplankton aggregation
KW - size structure population model
KW - numerical approximation
ER -
TY - JOUR
TI - Elimination of sub-oxide transition regions at Si-SiO2 interfaces by rapid thermal annealing at 900 degrees C
AU - Lucovsky, G
AU - Banerjee, A
AU - Niimi, H
AU - Koh, K
AU - Hinds, B
AU - Meyer, C
AU - Lupke, G
AU - Kurz, H
T2 - APPLIED SURFACE SCIENCE
AB - In many spectroscopic studies, particularly by X-ray photoelectron spectroscopy, XPS, it has been generally assumed that the existence of sub-oxide transition regions at SiSiO2 interfaces were not strongly dependent on synthesis chemistries and processing conditions. This paper presents experimental evidence for a kinetically-limited phase transition at SiSiO2 interfaces at approximately 900°C that can minimize and to a large degree eliminate significant interfacial sub-oxide transition regions. The paper emphasizes a connection between (i) differences in photoluminescence from SiOx bulk films before and after 900°C annealing and (ii) differences in electrical performance of SiSiO2 interfaces and optical second harmonic generation from SiSiO2 interfaces, also before and after 900°C annealing
DA - 1997/6//
PY - 1997/6//
DO - 10.1016/S0169-4332(97)80079-7
VL - 117
SP - 202-206
SN - 1873-5584
KW - Si-SiO2 interfaces
KW - sub-oxide transition regions
KW - plasma processing
KW - rapid thermal annealing
ER -
TY - JOUR
TI - Control of nonlinear delay differential equations in W-2((1)) with economic applications
AU - Chukwu, EN
T2 - APPLIED MATHEMATICS AND COMPUTATION
AB - The control of economic system's growth with delay is formulated to illustrate Euclidean (En) and function space (W2(1)) controllability of a general nonlinear delay equation. Sufficient conditions are given, in terms of the control matrix, for controllability of the general nonlinear system. These conditions are shown to be necessary for W2(1) controllability. The theory is then applied to a simple dynamics of gross national product and interest rate. The concept of function space controllability is very appropriate: once the target is hit, it remains on a certain growing function for some time.
DA - 1997/8//
PY - 1997/8//
DO - 10.1016/S0096-3003(96)00108-7
VL - 85
IS - 1
SP - 17-59
SN - 0096-3003
ER -
TY - JOUR
TI - A robust control framework for option pricing
AU - McEneaney, WM
T2 - MATHEMATICS OF OPERATIONS RESEARCH
AB - A new approach is taken to the problem of option pricing. In the standard framework, the option pricing problem involves determining a price such that the option writer can guarantee a certain bound on the cost almost surely. Due to this form, the problem may be reformulated in terms of deterministic differential games of the type employed in robust and H ∞ control. Different models yield different prices. The standard model yields the Black and Scholes price. Both a deterministic model and the standard model with the Ito integral replaced by the Stratonovich integral yield the price corresponding to a stop-loss hedging technique. With these methods, it can also easily be shown that for the standard model with a bounded, stochastic volatility, the Black and Scholes price corresponding to the upper bound for volatility is sufficient to hedge the option.
DA - 1997/2//
PY - 1997/2//
DO - 10.1287/moor.22.1.202
VL - 22
IS - 1
SP - 202-221
SN - 0364-765X
KW - option pricing
KW - Black-Scholes formula
KW - robust control
KW - viscosity solutions
ER -
TY - JOUR
TI - Schouten-Nijenhuis brackets
AU - Norris, LK
T2 - JOURNAL OF MATHEMATICAL PHYSICS
AB - The Poisson and graded Poisson Schouten–Nijenhuis algebras of symmetric and antisymmetric contravariant tensor fields, respectively, on an n-dimensional manifold M are shown to be n-symplectic. This is accomplished by showing that both brackets may be defined in a unified way using the n-symplectic structure on the bundle of linear frames LM of M. New results in n-symplectic geometry are presented and then used to give globally defined representations of the Hamiltonian operators defined by the Schouten–Nijenhuis brackets.
DA - 1997/5//
PY - 1997/5//
DO - 10.1063/1.531981
VL - 38
IS - 5
SP - 2694-2709
SN - 0022-2488
ER -
TY - JOUR
TI - Numerical solution of optimal distributed control problems for incompressible flows
AU - Hou, LS
AU - Ravindran, SS
AU - Yan, Y
T2 - INTERNATIONAL JOURNAL OF COMPUTATIONAL FLUID DYNAMICS
AB - Abstract We study the numerical solution of optimal control problems associated with the two-dimensional viscous incompressible flows which are governed by the Navier-Stokes equations. Although the techniques apply to more general settings, the presentation is confined to the objectives of minimizing the vorticity in the steady-state case with distributed controls and tracking the velocity field in the nonstationary case with piecewise distributed controls. In the steady-state case, we develop a systematic way to use the Lagrange multiplier rules to derive an optimality system of equations from which an optimal solution can be computed; finite element methods are used to find approximate solutions for the optimality system of equations. In the time-dependent case, a piecewise-in-time optimal control approach is proposed and the fully discrete approximation algorithm for solving the piecewise optimal control problem is defined. Numrical results are presented for both the steady-state and time-dependent optimal control problems.
DA - 1997///
PY - 1997///
DO - 10.1080/10618569708940798
VL - 8
IS - 2
SP - 99-114
SN - 1029-0257
KW - optimal control
KW - Navier-Stokes equations
KW - finite element method
KW - fully discrete approximations
ER -
TY - JOUR
TI - Identification of hysteretic control influence operators representing smart actuators, Part II: Convergent approximations
AU - Banks, HT
AU - Kurdila, AJ
AU - Webb, G
T2 - JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES
AB - In a previous paper, the authors investigated the lower semicontinuity properties of two generalizations of the classical Preisach operator: the smoothed Preisach operator and the Krasnoselskii/Pokrovskii (KP) integral hysteresis operators. In particular, it was demonstrated that the output least squares identification problem for the KP operator is well-posed over compact subsets of the Preisach plane. The identification of the hysteretic control influence operator was shown to be equivalent to the identification of a measure in the space of probability measures taken with the weak* topology. In this paper, a consistent and convergent approximation scheme is introduced for this class of integral hysteresis operator. The Galerkin approximation scheme is shown to be function space parameter convergent. A numerical example is presented that illustrates aspects of the theory derived in this paper.
DA - 1997/6//
PY - 1997/6//
DO - 10.1177/1045389X9700800606
VL - 8
IS - 6
SP - 536-550
SN - 1045-389X
ER -
TY - JOUR
TI - a priori error estimates for numerical methods for scalar conservation laws .2. Flux-splitting monotone schemes on irregular Cartesian grids
AU - Cockburn, B
AU - Gremaud, PA
T2 - MATHEMATICS OF COMPUTATION
AB - This paper is the second of a series in which a general theory of a priori error estimates for scalar conservation laws is constructed. In this paper, we focus on how the lack of consistency introduced by the nonuniformity of the grids influences the convergence of flux-splitting monotone schemes to the entropy solution. We obtain the optimal rate of convergence of ( Δ x ) 1 / 2 (\Delta x)^{1/2} in L ∞ ( L 1 ) L^{\infty }(L^{1}) for consistent schemes in arbitrary grids without the use of any regularity property of the approximate solution. We then extend this result to less consistent schemes, called p − p- consistent schemes, and prove that they converge to the entropy solution with the rate of ( Δ x ) min { 1 / 2 , p } (\Delta x)^{\min \{1/2,p\}} in L ∞ ( L 1 ) L^{\infty }(L^{1}) ; again, no regularity property of the approximate solution is used. Finally, we propose a new explanation of the fact that even inconsistent schemes converge with the rate of ( Δ x ) 1 / 2 (\Delta x)^{1/2} in L ∞ ( L 1 ) L^{\infty }(L^{1}) . We show that this well-known supraconvergence phenomenon takes place because the consistency of the numerical flux and the fact that the scheme is written in conservation form allows the regularity properties of its approximate solution (total variation boundedness) to compensate for its lack of consistency; the nonlinear nature of the problem does not play any role in this mechanism. All the above results hold in the multidimensional case, provided the grids are Cartesian products of one-dimensional nonuniform grids.
DA - 1997/4//
PY - 1997/4//
DO - 10.1090/S0025-5718-97-00838-7
VL - 66
IS - 218
SP - 547-572
SN - 1088-6842
KW - a priori error estimates
KW - irregular grids
KW - monotone schemes
KW - conservation laws
KW - supraconvergence
ER -
TY - JOUR
TI - Weak solutions to a one-dimensional hydrodynamic model of two carrier types for semiconductors
AU - Fang, WF
AU - Ito, K
T2 - NONLINEAR ANALYSIS-THEORY METHODS & APPLICATIONS
DA - 1997/3//
PY - 1997/3//
DO - 10.1016/0362-546X(95)00189-3
VL - 28
IS - 5
SP - 947-963
SN - 0362-546X
KW - hydrodynamic model for semiconductors
KW - hyperbolic systems
KW - viscosity method
KW - compensated compactness
ER -
TY - JOUR
TI - Tori invariant under an involutorial automorphism .2.
AU - Helminck, AG
T2 - ADVANCES IN MATHEMATICS
AB - The geometry of the orbits of a minimal parabolick-subgroup acting on a symmetrick-variety is essential in several areas, but its main importance is in the study of the representations associated with these symmetrick-varieties (see for example [5, 6, 20, and 31]). Up to an action of the restricted Weyl group ofG, these orbits can be characterized by theHk-conjugacy classes of maximalk-split tori, which are stable underk-involutionθassociated with the symmetrick-variety. HereHis a openk-subgroup of the fixed point group ofθ. This is the second in a series of papers in which we characterize and classify theHk-conjugacy classes of maximalk-split tori. The first paper in this series dealt with the case of algebraically closed fields. In this paper we lay the foundation for a characterization and classification for the case of nonalgebraically closed fields. This includes a partial classification in the cases, where the base field is the real numbers, p-adic numbers, finite fields, and number fields.
DA - 1997/10/15/
PY - 1997/10/15/
DO - 10.1006/aima.1997.1633
VL - 131
IS - 1
SP - 1-92
SN - 0001-8708
ER -
TY - JOUR
TI - Steady-state solutions of a one-dimensional hydrodynamic model for semiconductors
AU - Fang, WF
AU - Ito, K
T2 - JOURNAL OF DIFFERENTIAL EQUATIONS
AB - Steady-stateBVsolutions to a one-dimensional hydrodynamic model for semiconductors are shown to exist as limits of viscous solutions as the viscosity vanishes.
DA - 1997/1/20/
PY - 1997/1/20/
DO - 10.1006/jdeq.1996.3203
VL - 133
IS - 2
SP - 224-244
SN - 0022-0396
ER -
TY - JOUR
TI - Parameter estimation in a structured algal coagulation-fragmentation model
AU - Ackleh, AS
T2 - NONLINEAR ANALYSIS-THEORY METHODS & APPLICATIONS
DA - 1997/3//
PY - 1997/3//
DO - 10.1016/0362-546X(95)00195-2
VL - 28
IS - 5
SP - 837-854
SN - 0362-546X
KW - parameter estimation
KW - phytoplankton
KW - coagulation
KW - fragmentation
ER -
TY - JOUR
TI - Molecular layer epitaxy by real-time optical process monitoring
AU - Bachmann, K. J.
AU - Hopfner, C.
AU - Sukidi, N.
AU - Miller, A. E.
AU - Harris, C. J.
AU - Aspnes, D. E.
AU - Dietz, N. A.
AU - Tran, Hien
AU - Beeler, S. C.
AU - Ito, K.
AU - Banks, H. T.
T2 - Applied Surface Science
AB - In this paper we consider modern methods of optical process monitoring and control in the context of atomic layer epitaxy. One specific method, p-polarized reflectance spectroscopy (PRS), is chosen to assess details of layer-by-layer growth. We show that PRS monitoring under conditions of steady-state growth by pulsed chemical beam epitaxy (PCBE) can achieve the deposition of molecular layers of GaP on silicon (100) deposited with a precision of 5%, which can be improved by reducing the growth rate and increasing the period of time averaging of the reflectance data. Since in the nucleation period prior to formation of a contiguous heteroepitaxial film inhomogeneous surface chemistry and roughening complicates the modeling of the overgrowth process, advances in both experimental methods and theory are required for extending the control to non-steady-state growth conditions. Results of simultaneous single-wavelength PR monitoring and laser light scattering measurements in conjunction with atomic force microscopy studies of short period heteroepitaxial overgrowth processes are presented. The extension of PRS to the monitoring of organometallic chemical vapor deposition at higher pressures is also discussed.
DA - 1997///
PY - 1997///
DO - 10.1016/S0169-4332(96)00975-0
VL - 112
IS - 1997 Mar.
SP - 38–47
ER -
TY - JOUR
TI - Modeling of nonsymmetrical damage in plate-like structures
AU - Banks, HT
AU - Emeric, P
AU - Plancke, L
T2 - MATHEMATICAL AND COMPUTER MODELLING
AB - A two-dimensional model for in-plane vibrations of a damped linear elastic Hookean partially clamped plate-like structure with a nonsymmetrical damage is proposed. The model includes both active and passive contributions of piezoelectric ceramic patches bonded to the surface of the structure. Both strong and weak formulations of the equations of motion are presented. The problem is then formulated as a second-order equation in time. The existence, uniqueness of the solutions, and continuity with respect to the data are discussed.
DA - 1997/8//
PY - 1997/8//
DO - 10.1016/S0895-7177(97)00131-3
VL - 26
IS - 3
SP - 55-65
SN - 0895-7177
KW - damped elastic plates
KW - in-plane dynamic vibrations
KW - nonsymmetric damage
KW - well-posedness
ER -
TY - JOUR
TI - Influence of mixed boundary conditions in some reaction-diffusion systems
AU - Martin, RH
AU - Pierre, M
T2 - PROCEEDINGS OF THE ROYAL SOCIETY OF EDINBURGH SECTION A-MATHEMATICS
AB - Synopsis We analyse global existence of solutions to a system of two reaction–diffusion equations for whicha ‘balance’ law holds. The main aim is to make clear the influence of different combinations ofboundary conditions on global existence under the assumption that the nonlinearities satisfy polynomial growth estimates.
DA - 1997///
PY - 1997///
DO - 10.1017/s0308210500026883
VL - 127
SP - 1053-1066
SN - 0308-2105
ER -
TY - JOUR
TI - Ultra-thin gate dielectrics prepared by low-temperature remote plasma-assisted oxidation
AU - Niimi, H
AU - Koh, K
AU - Lucovsky, G
T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
AB - Abstract This paper discusses the formation of ultra-thin nitrided gate oxides by a low temperature plasma assisted oxidation process using remotely excited N2O as the source gas for both oxygen and nitrogen atoms. Three aspects of this process are addressed: (i) the differences in oxide growth rates for O2 or N2O plasma oxidation processes; (ii) the reaction pathways for the incorporation of nitrogen at the SiSiO2 interface for the N2O plasma process; and (iii) possible nitrogen atom depletion during processing steps that follow the plasma assisted oxidation/nitridation process.
DA - 1997/5//
PY - 1997/5//
DO - 10.1016/S0168-583X(96)00958-5
VL - 127
SP - 364-368
SN - 0168-583X
ER -
TY - JOUR
TI - The effects of computational delay in descriptor-based trajectory tracking control
AU - vonWissel, D
AU - Nikoukhah, R
AU - Campbell, SL
AU - Delebecque, F
T2 - INTERNATIONAL JOURNAL OF CONTROL
AB - Descriptor Predictive Control (DPC) has been shown to be a useful method for solving nonlinear tracking problems. A rigorous analysis of local stability and performance characteristics of this method has been achieved previously by studying the linear plant under the assumption that the delay introduced in the control due to numerical computation can be neglected. It was shown that, if the plant is controllable and minimum phase, stability is guaranteed and tracking is achieved exponentially with any desired rate of convergence. It was also shown that sometimes DPC must include a specially designed preliminary feedback. In this paper, we carry out a similar analysis by taking into account computational delay, which is unavoidable in actual implementation of DPC. We show, in particular, that under the same assumptions, and provided the special preliminary feedback is used, that the closed loop system remains stable as long as the delay is smaller than a threshold and that exponential tracking is achieved. However, the rate of convergence of the tracking error cannot be chosen arbitrarily because it is constrained by the plant zeros. The delay analysis is used to explain experimental observations in the literature about the occasional failure of previous implementations of the DPC approach at small sampling periods. A nonlinear robotics problem is worked in detail.
DA - 1997/5/20/
PY - 1997/5/20/
DO - 10.1080/002071797224289
VL - 67
IS - 2
SP - 251-273
SN - 1366-5820
ER -
TY - JOUR
TI - Systems of parabolic equations with continuous and discrete delays
AU - Pao, CV
T2 - JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS
AB - In this paper we investigate the global existence and the dynamics of a coupled system of nonlinear parabolic equations where the nonlinear “reaction function” may depend on both continuous (infinite or finite) and discrete delays. It is shown that if the reaction function is locally Lipschitz continuous and the system possesses a pair of coupled upper and lower solutions then there exists a unique global solution to the system without any quasimonotone condition on the reaction function. For systems with mixed quasimonotone reaction functions we use the monotone method to establish more dynamic property of the parabolic system in terms of the quasisolutions of the corresponding elliptic system. This approach yields a (global) attractor of the parabolic system, and under some additional conditions this attractor leads to the existence and asymptotic stability of a solution of the elliptic system. Application to three model problems in population dynamics and chemical reactions is given.
DA - 1997/1/1/
PY - 1997/1/1/
DO - 10.1006/jmaa.1996.5177
VL - 205
IS - 1
SP - 157-185
SN - 1096-0813
ER -
TY - JOUR
TI - On the inhomogeneous system of isentropic gas dynamics by the viscosity method
AU - Fang, WF
AU - Ito, K
T2 - PROCEEDINGS OF THE ROYAL SOCIETY OF EDINBURGH SECTION A-MATHEMATICS
AB - The existence of global weak solutions is shown for the equations of isentropic gas dynamics with inhomogeneous terms by the viscosity method. A generalised version of the method of invariant regions is developed to obtain the uniform L ∞ bounds of the viscosity solutions, and the method of compensated compactness is applied to show the existence of weak solutions as limits of the viscosity solutions. The lower positive bound for the density function is also obtained. As an example, a hydrodynamic model for semiconductors is analysed
DA - 1997///
PY - 1997///
DO - 10.1017/s0308210500023647
VL - 127
SP - 261-280
SN - 0308-2105
ER -
TY - JOUR
TI - On products of EP matrices
AU - Hartwig, RE
AU - Katz, IJ
T2 - LINEAR ALGEBRA AND ITS APPLICATIONS
AB - Necessary and sufficient conditions are given for the product of two EP matrices to be EP. Some special cases are considered.
DA - 1997/2//
PY - 1997/2//
DO - 10.1016/0024-3795(95)00693-1
VL - 252
SP - 339-345
SN - 0024-3795
ER -
TY - JOUR
TI - Minimization of sub-oxide transition regions at Si-SiO2 interfaces by 900 degrees C rapid thermal annealing
AU - Lucovsky, G
AU - Banerjee, A
AU - Hinds, B
AU - Claflin, B
AU - Koh, K
AU - Yang, H
T2 - MICROELECTRONIC ENGINEERING
AB - Abstract Combining previously reported optical second harmonic generation (SHG) data with i) newly-reported X-ray photoelectron spectroscopy (XPS) data and ii) the Auger electron spectroscopy (AES) results presented in this paper demonstrates that interfacial sub-oxide bonding (SiOx, x
DA - 1997/6//
PY - 1997/6//
DO - 10.1016/s0167-9317(97)00049-x
VL - 36
IS - 1-4
SP - 207-210
SN - 0167-9317
ER -
TY - JOUR
TI - Identification of benzene oxide as a product of benzene metabolism by mouse, rat, and human liver microsomes
AU - Lovern, MR
AU - Turner, MJ
AU - Meyer, M
AU - Kedderis, GL
AU - Bechtold, WE
AU - Schlosser, PM
T2 - CARCINOGENESIS
AB - Benzene is a ubiquitous environmental pollutant that is known to cause hematotoxicity and leukemia in humans. The initial oxidative metabolite of benzene has long been suspected to be benzene oxide (3,5-cyclohexadiene-1,2-oxide). During in vitro experiments designed to characterize the oxidative metabolism of [14C]benzene, a metabolite was detected by HPLC-radioactivity analysis that did not elute with other known oxidative metabolites. The purpose of our investigation was to prove the hypothesis that this metabolite was benzene oxide. Benzene (1 mM) was incubated with liver microsomes from human donors, male B6C3F1 mice, or male Fischer-344 rats, NADH (1 mM), and NADPH (1 mM) in 0.1 M sodium phosphate buffer (pH 7.4) and then extracted with methylene chloride. Gas chromatography-mass spectrometry analysis of incubation extracts for mice, rats, and humans detected a metabolite whose elution time and mass spectrum matched that of synthetic benzene oxide. The elution time of the benzene oxide peak was approximately 4.1 min, while phenol eluted at approximately 8 min. Benzene oxide also coeluted with the HPLC peak of the previously unidentified metabolite. Based on the 14C activity of this peak, the concentration of benzene oxide was determined to be approximately 18 microM, or 7% of total benzene metabolites, after 18 min of incubation of mouse microsomes with 1 mM benzene. The metabolite was not observed in incubations using heat-inactivated microsomes. This is the first demonstration that benzene oxide is a product of hepatic benzene metabolism in vitro. The level of benzene oxide detected suggests that benzene oxide is sufficiently stable to reach significant levels in the blood of mice, rats, and humans and may be translocated to the bone marrow. Therefore benzene oxide should not be excluded as a possible metabolite involved in benzene-induced leukemogenesis.
DA - 1997/9//
PY - 1997/9//
DO - 10.1093/carcin/18.9.1695
VL - 18
IS - 9
SP - 1695-1700
SN - 0143-3334
ER -
TY - JOUR
TI - Experimental confirmation of a PDE-based approach to design of feedback controls
AU - Banks, HT
AU - Smith, RC
AU - Brown, DE
AU - Silcox, RJ
AU - Metcalf, VL
T2 - SIAM JOURNAL ON CONTROL AND OPTIMIZATION
AB - Issues regarding the experimental implementation of PDE-based controllers are discussed in this work. While the motivating application involves the reduction of vibration levels for a circular plate through excitation of surface-mounted piezoceramic patches, the general techniques described here will extend to a variety of applications. The initial step is the development of a PDE model which accurately captures the physics of the underlying process. This model is then discretized to yield a vector-valued initial value problem. Optimal control theory is used to determine continuous-time voltages to the patches, and the approximations needed to facilitate discrete-time implementation are addressed. Finally, experimental results demonstrating the control of both transient and steady-state vibrations through these techniques are presented.
DA - 1997/7//
PY - 1997/7//
DO - 10.1137/S0363012995285909
VL - 35
IS - 4
SP - 1263-1296
SN - 0363-0129
KW - feedback control
KW - piezoceramic actuators
KW - PDE model
ER -
TY - JOUR
TI - Computational methods for a curved beam with piezoceramic patches
AU - Banks, HT
AU - Zhang, Y
T2 - JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES
AB - We develop a computational scheme to approximate the solutions of a mathematical model that describes the vibrations of a curved beam structure. The physical model also includes pairs of piezoceramic patches that can be viewed either as passive devices, changing only the structural properties of the beam, or as active devices used to control vibrations of the beam. As part of our numerical experiments, we compare schemes with a method that employs hybrid B-spline basis elements and a method that employs just one family of B-spline basis elements. We calculate the first four fundamental frequencies and mode shapes of the structure, and we simulate patch-activated vibrations. Finally, we devote a section to investigation of locking phenomena which have been reported for some shell problems.
DA - 1997/3//
PY - 1997/3//
DO - 10.1177/1045389X9700800307
VL - 8
IS - 3
SP - 260-278
SN - 1045-389X
ER -
TY - JOUR
TI - An organizing center for wave bifurcation in multiphase flow models
AU - Marchesin, D.
AU - Plohr, B. J.
AU - Schecter, S.
T2 - SIAM Journal on Applied Mathematics
AB - We consider a one-parameter family of nonstrictly hyperbolic systems of conservation laws modeling three-phase flow in a porous medium. For a particular value of the parameter, the model has a shock wave solution that undergoes several bifurcations upon perturbation of its left and right states and the parameter. In this paper we use singularity theory and bifurcation theory of dynamical systems, including Melnikov's method, to find all nearby shock waves that are admissible according to the viscous profile criterion. We use these results to construct a unique solution of the Riemann problem for each left and right state and parameter value in a neighborhood of the unperturbed shock wave solution; together with previous numerical work, this construction completes the solution of the three-phase flow model. In the bifurcation analysis, the unperturbed shock wave acts as an organizing center for the waves appearing in Riemann solutions.
DA - 1997///
PY - 1997///
DO - 10.1137/s0036139995280683
VL - 57
IS - 5
SP - 1189-1215
ER -
TY - JOUR
TI - DAEs arising from traveling wave solutions of PDEs
AU - Campbell, SL
AU - Marszalek, W
T2 - JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS
AB - The study of traveling waves for explicit and implicit PDEs can sometimes result in differential algebraic equations (DAEs) instead of ordinary differential equations. The advantages of using DAEs is discussed as are the implications of DAE theory for the study of traveling waves. A specific type of traveling wave that connects equilibria is examined in more detail. Specific examples are given.
DA - 1997/9/15/
PY - 1997/9/15/
DO - 10.1016/S0377-0427(97)00084-8
VL - 82
IS - 1-2
SP - 41-58
SN - 0377-0427
KW - differential algebraic equation
KW - DAE
KW - traveling waves
KW - equilibria
KW - magnetohydrodynamics
ER -
TY - JOUR
TI - On pattern formation in reptilian dentition
AU - Lubkin, , SR
T2 - JOURNAL OF THEORETICAL BIOLOGY
AB - Pattern formation of placode initiation in reptilian dental development is modeled with a generalized function, which may represent chemical concentrations, strain energy of mechanically deforming tissues, or other quantities representing a local inhibition of placode formation. The conditions on the generalized model which are necessary to account for all experimental observations are examined in detail. Minimal conditions for the correct sequencing of the tooth primordia are determined, and it is found that all known initial reptilian sequences can be accounted for with the same mechanism, with merely a different choice of parameters. An implication of the modeling results is that the lower jaw of the tuatara (Sphenodon punctatus) has a greater growth rate in its anterior portion than in its posterior portion, whereas the opposite is true of all other reptiles studied. Sequences of tooth initiation are observed robustly in the model which have not hitherto been documentedin vivo, suggesting the as yet undocumented occurrence of such a sequence in a living or extinct reptile.
DA - 1997/5/21/
PY - 1997/5/21/
DO - 10.1006/jtbi.1996.0349
VL - 186
IS - 2
SP - 145-157
SN - 0022-5193
UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:A1997XA38000002&KeyUID=WOS:A1997XA38000002
ER -
TY - JOUR
TI - A mathematical approximation for the solution of a static indentation test
AU - Haider, MA
AU - Holmes, MH
T2 - JOURNAL OF BIOMECHANICS
AB - The classical contact problem of the indentation of a thin compressible linear elastic layer bonded to a rigid substrate is considered. Closed-form mathematical approximations of the deformation are presented for the cases of plane indentation by a rectangular block and three dimensional indentation by a plane-ended (axisymmetric) cylinder. The approximations are analyzed in the context of a static indentation test by comparison of applied load values to those obtained using a classical integral transform solution. In the case of plane indentation, the mathematical and classical predictions agree to within 2% relative error for aspect ratios between 0.1 and 1.0 and apparent Poisson ratio between 0.0 and 0.3. Comparisons for the axisymmetric case indicate a similar pattern. The main advantage of the new approach is that it yields closed-form approximations of the static indentation solution which can also capture the essential singular behavior.
DA - 1997/7//
PY - 1997/7//
DO - 10.1016/S0021-9290(97)00024-9
VL - 30
IS - 7
SP - 747-751
SN - 1873-2380
KW - indentation
KW - articular cartilage
KW - joint contact
ER -
TY - JOUR
TI - Jacobian reuse in explicit integrators for higher index DAEs
AU - Campbell, SL
AU - Zhong, YC
T2 - APPLIED NUMERICAL MATHEMATICS
AB - Systems F(y′,y,t) = 0 with Fy′ identically singular are known as differential algebraic equations (DAEs) and occur in a variety of applications. The index v is one measure of numerical difficulty. Most numerical methods for DAEs either require special structure or low index. Two alternative approaches have been proposed for numerically integrating more general higher index DAEs. This paper examines some of the mathematical issues involved in the efficient implementation of the “explicit integration” method. It is first shown that the reuse of Jacobians can lead to the integration of discontinuous vector fields. It is then proven that these discontinuous fields can be successfully integrated. Computational examples back up the theory. A comparison to a standard integrator on an index three control problem illustrates that while the explicit approach can be somewhat more expensive computationally, it can be easier to apply, and does not suffer from order reduction in the higher index variables.
DA - 1997/12//
PY - 1997/12//
DO - 10.1016/S0168-9274(97)00052-4
VL - 25
IS - 4
SP - 391-412
SN - 0168-9274
KW - differential algebraic equation
KW - DAE
KW - numerical methods
ER -
TY - JOUR
TI - Some identities for Chandrasekhar polynomials
AU - Siewert, CE
AU - McCormick, NJ
T2 - JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER
AB - Basic techniques of linear algebra are used to derive some identities involving the Chandrasekhar polynomials that play a vital role in the spherical-harmonics (PN) solution to basic radiative-transfer problems.
DA - 1997/3//
PY - 1997/3//
DO - 10.1016/S0022-4073(96)00122-7
VL - 57
IS - 3
SP - 399-404
SN - 0022-4073
ER -
TY - JOUR
TI - Shape matching with smart material structures using piezoceramic actuators
AU - Fitzpatrick, BG
T2 - JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES
AB - In this paper, we consider the problem of driving a flexible structure from an "unforced" equilibrium position to a given desired shape. Within the context of smart materials, we focus on piezoceramic actuators as controls. Our approach is to base the choice of input voltages on a physical model of the structure, with "good" voltage choices being those whose modelbased displacements "'closely" match the desired shape. This shape matching problem is posed as a least squares problem in a Hilbert space that represents the displacement component of the state space of the flexible structure model. Here we treat the structure as a distributed parameter system, so that the state space is infinite dimensional. Thus, we must examine questions of existence of solutions and convergence of approximations. To illustrate our techniques, we give some numerical examples.
DA - 1997/10//
PY - 1997/10//
DO - 10.1177/1045389X9700801007
VL - 8
IS - 10
SP - 876-882
SN - 1045-389X
ER -
TY - JOUR
TI - On the trace of graded automorphisms
AU - Jing, NH
AU - Zhang, JJ
T2 - JOURNAL OF ALGEBRA
AB - LetA = ⊕d ≥ 0 Adbe a connected algebra with a graded algebra endomorphism σ. The trace of σ is defined to be Tr(σ, t) = ∑d ≥ 0 tr(σ|Ad)td. We prove that Tr(σ, t) is a rational function ifAis either finitely generated commutative or right noetherian with finite global dimension or regular. A version of Molien's theorem follows in these three cases. IfAis a regular algebra or a Frobenius algebra we prove a reciprocity for the trace. We also partially generalize a theorem of Watanabe on the Gorenstein property to the noncommutative case.
DA - 1997/3/15/
PY - 1997/3/15/
DO - 10.1006/jabr.1996.6896
VL - 189
IS - 2
SP - 353-376
SN - 0021-8693
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0031569313&partnerID=MN8TOARS
ER -
TY - JOUR
TI - On inverse boundary-condition problems in radiative transfer
AU - Barichello, LB
AU - Garcia, RDM
AU - Siewert, CE
T2 - JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER
AB - Abstract Some elementary computations are reported to suggest that a certain type of inverse boundary-condition problem in radiative transfer can, in some cases, be solved quite simply.
DA - 1997/3//
PY - 1997/3//
DO - 10.1016/S0022-4073(96)00095-7
VL - 57
IS - 3
SP - 405-410
SN - 0022-4073
ER -
TY - JOUR
TI - Analogue of the Bruhat-Chevalley order for reductive monoids
AU - Pennell, EA
AU - Putcha, MS
AU - Renner, LE
T2 - JOURNAL OF ALGEBRA
AB - The purpose of this paper is to describe the Adherence Order of w x B = B-orbits on a reductive algebraic monoid. By the results of 10 there is already a perfect analogue of the Bruhat decomposition for reductive w x monoids. Indeed, by 10, Corollary 5.8 , if M is reductive with unit group G and maximal torus T : G with Borel subgroup B = T , then the set of two sided B-orbits, B R MrB is canonically identified with a certain finite Ž . inverse monoid R. In fact, R s N T rT , the orbit monoid of the Zariski G Ž . closure of N T in M. By definition, for s , t g R we define the AdherG ence Order by s F t if Bs B : Bt B, where Bt B denotes the Zariski closure in M of Bt B.
DA - 1997/10/15/
PY - 1997/10/15/
DO - 10.1006/jabr.1997.7111
VL - 196
IS - 2
SP - 339-368
SN - 0021-8693
ER -
TY - JOUR
TI - The perturbation theory for the drazin inverse and its applications
AU - Wei, Y.-M.
AU - Wang, G. R.
T2 - Linear Algebra and Its Applications
DA - 1997///
PY - 1997///
VL - 258
IS - 1997 June
SP - 179-186
ER -
TY - JOUR
TI - Teaching computational abstract algebra
AU - Kaltofen, E
T2 - JOURNAL OF SYMBOLIC COMPUTATION
AB - We report on the contents and pedagogy of a course in abstract algebra that was taught with the aid of educational software developed within the Mathematica system. We describe the topics covered and the didactical use of the corresponding Mathematica packages, as well as draw conclusions for future such courses from the students' comments and our own experience.
DA - 1997///
PY - 1997///
DO - 10.1006/jsco.1996.0104
VL - 23
IS - 5-6
SP - 503-515
SN - 0747-7171
ER -
TY - JOUR
TI - Risk-sensitive and robust escape criteria
AU - Dupuis, P
AU - McEneaney, WM
T2 - SIAM JOURNAL ON CONTROL AND OPTIMIZATION
AB - The problem of controlling a noisy process so as to prevent it from leaving a prescribed set has a number of interesting applications. In this paper, new approaches to this problem are considered. First, a risk-sensitive criterion for a stochastic diffusion process model is examined, and it is shown that the value is a classical solution of a related PDE. The qualitative properties of this criterion are favorably contrasted with those of existing criteria in the risk-averse limit. It is proved that in the risk-averse limit the value of the risk-sensitive criterion converges to a viscosity solution of a first-order PDE. It is then demonstrated that the value function of a deterministic differential game is also a viscosity solution to the PDE. This game gives a robust control formulation of the escape time problem and is analogous to H$^{\infty}$ control. In particular, the opposing player attempts to push the process out of the prescribed set and suffers an L2 cost for his efforts. Lower bounds on the escape time as a function of this cost are obtained.
DA - 1997/11//
PY - 1997/11//
DO - 10.1137/S0363012995281626
VL - 35
IS - 6
SP - 2021-2049
SN - 0363-0129
KW - exit time control
KW - risk-sensitive control
KW - large deviations
KW - robust control
ER -
TY - JOUR
TI - Risk analyses in clonal forestry
AU - Roberds, JH
AU - Bishir, JW
T2 - CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE
AB - The number of clones to use in plantations is an important problem that must be addressed by practitioners of clonal forestry because of productivity and forest health considerations. This problem has been analyzed from a number of perspectives, but analyses based upon risk of plantation failure have provided special insight about effects produced by an increase in numbers of clones. In this paper, we describe alternative models and methods that have been proposed to investigate the effect of number of clones on risk of plantation failure following an unforeseen catastrophic event. Properties of these models are reviewed and conclusions resulting from the analysis of each model are given. Results from these analyses and recently developed theory indicate that use of 30 to 40 unrelated clones in plantations provides protection against catastrophic failure roughly equivalent to the use of large numbers of unrelated clones. A detailed description of the recently introduced time-to-failure model is also presented, and several examples that illustrate properties of this model are discussed. Finally, some implications regarding the development of breeding populations are identified and explored. Resume : La problOmatique du nombre de clones utilisOs dans les plantations clonales doit Œtre abordOe par les praticiens de la foresterie clonale en raison des implications quielle peut avoir pour la productivitO et la santO des forŒts. Ce problme a OtO OtudiO sous de nombreux angles, mais il siest avOrO que liapproche basOe sur le risque diOchec de plantation a permis de rOvOler les effets rOsultant diune augmentation du nombre de clones utilisOs. Les auteurs de liOtude font la description des mOthodes et modles alternatifs qui ont OtO proposOs pour Otudier lieffet du nombre de clones sur le risque diOchec de plantation suite ‡ un OvOnement catastrophique imprOvisible. Les auteurs prOsentent la revue des caractOristiques ainsi que les conclusions dOcoulant de lianalyse de chacun de ces modles. Les rOsultats de cette analyse ainsi que les considOrations thOoriques dOveloppOes rOcemment indiquent que liutilisation de 30 ‡ 40 clones non apparentOs par plantation procure une protection contre des Ochecs catastrophiques qui est ‡ peu prs Oquivalente ‡ celle qui dOcoule de liutilisation diun grand nombre de clones non apparentOs. Une description dOtaillOe du modle rOcent de «dOlai diOchec» est prOsentOe. Quelques exemples illustrant les caractOristiques de ce modle sont Ogalement discutOs. Enfin, certaines implications relatives au dOveloppement des populations diOlevage sont identifiOes et discutOes. (Traduit par la ROdaction)
DA - 1997/3//
PY - 1997/3//
DO - 10.1139/x96-202
VL - 27
IS - 3
SP - 425-432
SN - 0045-5067
ER -
TY - JOUR
TI - Plasma-assisted formation of low defect density SiC-SiO2 interfaces
AU - Golz, A.
AU - Lucovsky, G.
AU - Koh, K.
AU - Wolfe, D.
AU - Niimi, H.
AU - Kurz, H.
T2 - Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures
DA - 1997///
PY - 1997///
VL - 15
IS - 4
SP - 1097-1104
ER -
TY - JOUR
TI - Optimal control of the growth of wealth of nations: With Austria and USA examples
AU - Chukwu, EN
T2 - NONLINEAR ANALYSIS-THEORY METHODS & APPLICATIONS
DA - 1997/12//
PY - 1997/12//
DO - 10.1016/S0362-546X(96)00246-5
VL - 30
IS - 2
SP - 1029-1041
SN - 0362-546X
KW - optimal control
KW - controllability
KW - function space controllable
KW - economic variables
KW - regression
KW - delay differential equations
KW - stability
ER -
TY - JOUR
TI - Numerical simulation of pattern formation in grain flows
AU - Gremaud, PA
T2 - APPLIED MATHEMATICS AND COMPUTATION
AB - We present numerical computations for the flow of granular materials in hoppers. The algorithm is based on a cellular automaton approach and takes into account various microscopic effects, including “orientational effects”. The formation and the dynamics of density waves, recently discovered in physical experiments, is observed and analyzed computationally.
DA - 1997/7//
PY - 1997/7//
DO - 10.1016/S0096-3003(96)00084-7
VL - 84
IS - 2-3
SP - 145-162
SN - 0096-3003
ER -
TY - JOUR
TI - Monoid Hecke algebras
AU - Putcha, MS
T2 - TRANSACTIONS OF THE AMERICAN MATHEMATICAL SOCIETY
AB - This paper concerns the monoid Hecke algebras $\mathcal {H}$ introduced by Louis Solomon. We determine explicitly the unities of the orbit algebras associated with the two-sided action of the Weyl group $W$. We use this to: find a description of the irreducible representations of $\mathcal {H}$, find an explicit isomorphism between $\mathcal {H}$ and the monoid algebra of the Renner monoid $R$, extend the Kazhdan-Lusztig involution and basis to $\mathcal {H}$, and prove, for a $W\times W$ orbit of $R$, the existence (conjectured by Renner) of generalized Kazhdan-Lusztig polynomials.
DA - 1997/9//
PY - 1997/9//
DO - 10.1090/S0002-9947-97-01823-0
VL - 349
IS - 9
SP - 3517-3534
SN - 0002-9947
ER -
TY - JOUR
TI - Linear differential equations and products of linear forms
AU - Singer, MF
AU - Ulmer, F
T2 - JOURNAL OF PURE AND APPLIED ALGEBRA
AB - We show that liouvillian solutions of an n th-order linear differential equation L ( y ) = 0 are related to semi-invariant forms of the differential Galois group of L ( y ) = 0 which factor into linear forms. The logarithmic derivative of such a form F , evaluated in the solutions of L ( y ) = 0, is the first coefficient of a polynomial P ( u ) whose zeros are logarithmic derivatives of solutions of L ( y ) = 0. Together with the Brill equations, this characterization allows one to efficiently test if a semi-invariant corresponds to such a coefficient and to compute the other coefficients of P ( u ) via a factorization of the form F .
DA - 1997/5//
PY - 1997/5//
DO - 10.1016/S0022-4049(97)00027-3
VL - 117
SP - 549-563
SN - 1873-1376
ER -
TY - JOUR
TI - Extremal properties of Rademacher functions with applications to the Khintchine and Rosenthal inequalities
AU - Figiel, T
AU - Hitczenko, P
AU - Johnson, WB
AU - Schechtman, G
AU - Zinn, J
T2 - TRANSACTIONS OF THE AMERICAN MATHEMATICAL SOCIETY
AB - The best constant and the extreme cases in an inequality of H.P. Rosenthal, relating the p p moment of a sum of independent symmetric random variables to that of the p p and 2 2 moments of the individual variables, are computed in the range 2 > p ≤ 4 2>p\le 4 . This complements the work of Utev who has done the same for p > 4 p>4 . The qualitative nature of the extreme cases turns out to be different for p > 4 p>4 than for p > 4 p>4 . The method developed yields results in some more general and other related moment inequalities.
DA - 1997/3//
PY - 1997/3//
DO - 10.1090/S0002-9947-97-01789-3
VL - 349
IS - 3
SP - 997-1027
SN - 0002-9947
KW - Khintchine inequality
KW - Rosenthal inequality
KW - Orlicz function
KW - extremal problem
KW - Rademacher functions
ER -
TY - JOUR
TI - Estimation of the convection coefficient in elliptic equations
AU - Ito, K
AU - Kunisch, K
T2 - INVERSE PROBLEMS
AB - The parameter estimation problem for the convection coefficient in elliptic equations is considered in the class of -vector fields. The optimality system is characterized and the convergence of the gradient method is proved. To apply the SQP-method to the singular optimality system, a modification involving a feasibility step in the primal and dual variables is introduced. The resulting algorithm has a second-order convergence rate. Numerical experiments are included.
DA - 1997/8//
PY - 1997/8//
DO - 10.1088/0266-5611/13/4/007
VL - 13
IS - 4
SP - 995-1013
SN - 0266-5611
ER -
TY - JOUR
TI - Computing an eigenvector with inverse iteration
AU - Ipsen, ICF
T2 - SIAM REVIEW
AB - The purpose of this paper is two-fold: to analyze the behavior of inverse iteration for computing a single eigenvector of a complex square matrix and to review Jim Wilkinson's contributions to the development of the method. In the process we derive several new results regarding the convergence of inverse iteration in exact arithmetic. In the case of normal matrices we show that residual norms decrease strictly monotonically. For eighty percent of the starting vectors a single iteration is enough. In the case of non-normal matrices, we show that the iterates converge asymptotically to an invariant subspace. However, the residual norms may not converge. The growth in residual norms from one iteration to the next can exceed the departure of the matrix from normality. We present an example where the residual growth is exponential in the departure of the matrix from normality. We also explain the often significant regress of the residuals after the first iteration: it occurs when the non-normal part of the matrix is large compared to the eigenvalues of smallest magnitude. In this case computing an eigenvector with inverse iteration is exponentially ill conditioned (in exact arithmetic). We conclude that the behavior of the residuals in inverse iteration is governed by the departure of the matrix from normality rather than by the conditioning of a Jordan basis or the defectiveness of eigenvalues.
DA - 1997/6//
PY - 1997/6//
DO - 10.1137/S0036144596300773
VL - 39
IS - 2
SP - 254-291
SN - 1095-7200
KW - eigenvector
KW - invariant subspace
KW - inverse iteration
KW - departure from normality
KW - ill-conditioned linear system
ER -
TY - JOUR
TI - Compact rings having a finite simple group of units
AU - Cohen, JA
AU - Koh, K
T2 - JOURNAL OF PURE AND APPLIED ALGEBRA
AB - For a compact Hausdorff ring, one observes that the group of units is a totally disconnected compact topological group and is a finite simple group if and only if it possesses no nontrivial closed normal subgroups. Three classification theorems for compact rings are now given. First, those compact rings with identity having a finite simple group of units are identified. Second, a classification of all compact rings A with identity for which 2 is a unit in A, G modulo the center of G is a finite simple group and the length of W is less than or equal to 4 (or equivalently, W is a torsion group) is given where G is the group of units in A and W is the subgroup of G generated by {g∈ G: g2 = 1}. Finally, those compact rings with identity having 2 as a unit and for which W is a nilpotent group are identified.
DA - 1997/6/2/
PY - 1997/6/2/
DO - 10.1016/S0022-4049(96)00128-4
VL - 119
IS - 1
SP - 13-26
SN - 0022-4049
ER -