TY - RPRT TI - Industrial Mathematics Modeling Workshop for Graduate Students Series DA - 2000/// PY - 2000/// M3 - CRSC Technical Reports ER - TY - BOOK TI - Industrial Mathematics A3 - Gremaud, P. A3 - Li, Zhilin A3 - Smith, R A3 - Tran, H. DA - 2000/// PY - 2000/// PB - SIAM SN - O-89871-467-2 ER - TY - RPRT TI - A note on a certain class of preconditioners for symmetric indefinite linear systems AU - Ipsen, I.C.F. A3 - Mathematics & Computing Technology, Phantom Works Division, The Boeing Company DA - 2000/7// PY - 2000/7// M1 - M&CT-TECH-00-005 M3 - Technical Report PB - Mathematics & Computing Technology, Phantom Works Division, The Boeing Company SN - M&CT-TECH-00-005 ER - TY - BOOK TI - Industrial Mathematics: The 1998 CRSC Workshop A3 - Gremaud, P.A. A3 - Li, Z. A3 - Smith, R.C. A3 - Tran, H.T. DA - 2000/10// PY - 2000/10// SP - 70 PB - SIAM Publications ER - TY - JOUR TI - Editorial AU - Hong, Hoon T2 - J. Symb. Comput. DA - 2000/// PY - 2000/// DO - 10.1006/jsco.2000.0345 VL - 29 IS - 1 SP - 3-4 UR - https://doi.org/10.1006/jsco.2000.0345 ER - TY - BOOK TI - Industrial Mathematics: The 1998 CRSC Workshop DA - 2000/// PY - 2000/// PB - SIAM ER - TY - THES TI - Inductive approach to Cartan's moving frame method with applications to classical invariant theory DA - 2000/// PY - 2000/// UR - https://www-proquest-com.prox.lib.ncsu.edu/docview/304612470/fulltextPDF/23BAF25E0A874972PQ/8?accountid=12725 ER - TY - CONF TI - Early termination in Ben-Or/Tiwari sparse interpolation and a hybrid of Zippel's algorithm AU - Kaltofen, Erich AU - Lee, Wen-shin AU - Lobo, Austin A. T2 - the 2000 international symposium AB - Article Early termination in Ben-Or/Tiwari sparse interpolation and a hybrid of Zippel's algorithm Share on Authors: Erich Kaltofen Department of Mathematics, North Carolina State University, Raleigh, North Carolina Department of Mathematics, North Carolina State University, Raleigh, North CarolinaView Profile , Wen-shin Lee Department of Mathematics, North Carolina State University, Raleigh, North Carolina Department of Mathematics, North Carolina State University, Raleigh, North CarolinaView Profile , Austin A. Lobo Dept. of Mathematics and Computer Science, Washington College, Chestertown, Maryland Dept. of Mathematics and Computer Science, Washington College, Chestertown, MarylandView Profile Authors Info & Claims ISSAC '00: Proceedings of the 2000 international symposium on Symbolic and algebraic computationJuly 2000 Pages 192–201https://doi.org/10.1145/345542.345629Online:01 July 2000Publication History 22citation308DownloadsMetricsTotal Citations22Total Downloads308Last 12 Months14Last 6 weeks2 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 SiteGet Access C2 - 2000/// C3 - Proceedings of the 2000 international symposium on Symbolic and algebraic computation symbolic and algebraic computation - ISSAC '00 DA - 2000/// DO - 10.1145/345542.345629 PB - ACM Press SN - 1581132182 UR - http://dx.doi.org/10.1145/345542.345629 DB - Crossref ER - TY - JOUR TI - On a Combinatorial Identity AU - Ding, J. AU - Jing, N. T2 - International Mathematics Research Notices DA - 2000/// PY - 2000/// VL - 2000 IS - 6 SP - 324-332 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0346737810&partnerID=MN8TOARS ER - TY - JOUR TI - Direct quantitation of rapid elimination of viral antigen-positive lymphocytes by antiviral CD8+ T cellsin vivo AU - Barchet, Winfried AU - Oehen, Stephan AU - Klenerman, Paul AU - Wodarz, Dominik AU - Bocharov, Gennadii AU - Lloyd, Alun L. AU - Nowak, Martin A. AU - Hengartner, Hans AU - Zinkernagel, Rolf M. AU - Ehl, Stephan T2 - European Journal of Immunology AB - Lysis of infected cells by CD8(+) T cells is an important mechanism for the control of virus infections, but remains difficult to quantify in vivo. Here, we study the elimination kinetics of viral antigen-positive lymphocytes by antiviral CD8(+) T cells using flow cytometry and mathematical analysis. In mice acutely infected with lymphocytic choriomeningitis virus, more than 99.99 % of target cells were eliminated each day, corresponding to a half-life of 1.4 h. Even in mice exposed to virus 300 days previously, and with no ex vivo killing activity, 84 % of the target cells were eliminated per day. Unexpectedly, the elimination kinetics of antigen-positive lymphocytes was not significantly impaired in mice deficient in either perforin-, CD95 ligand- or TNF-mediated cytotoxicity. For viruses with a particular tropism for lymphocytes, such as Epstein-Barr virus or HIV, our results illustrate how effectively CD8(+) T cell-mediated elimination of target cells can potentially contribute to virus control and immunosuppression. DA - 2000/5// PY - 2000/5// DO - 10.1002/(SICI)1521-4141(200005)30:5<1356::AID-IMMU1356>3.0.CO;2-K VL - 30 IS - 5 SP - 1356-1363 J2 - Eur. J. Immunol. LA - en OP - SN - 0014-2980 1521-4141 UR - http://dx.doi.org/10.1002/(SICI)1521-4141(200005)30:5<1356::AID-IMMU1356>3.0.CO;2-K DB - Crossref KW - CD8(+) T cell KW - virus KW - cytotoxicity KW - perforin KW - CD95 ER - TY - JOUR TI - Nonreflecting artificial boundary conditions for the replacement of rejected equations with gaps T2 - Mat. Model. DA - 2000/// PY - 2000/// VL - 12 IS - 12 SP - 108-127 UR - https://mathscinet.ams.org/mathscinet-getitem?mr=1833776 N1 - [in Russian] RN - [in Russian] ER - TY - JOUR TI - Global Artificial Boundary Conditions for Computation of External Flows with Jets AU - Tsynkov, Semyon AU - Abarbanel, Saul AU - Nordström, Jan AU - Ryaben'kii, Victor AU - Vatsa, Veer T2 - AIAA Journal AB - We propose new global artificial boundary conditions (ABCs) for computation of flows with propulsive jets. The algorithm is based on application of the difference potentials method (DPM). Previously, similar boundary conditions have been implemented for calculation of external compressible viscous flows around finite bodies. The proposed modification substantially extends the applicability range of the DPM-based algorithm. We present the general formulation of the problem, describe our numerical methodology, and discuss the corresponding computational results. The particular configuration that we analyze is a slender three-dimensional body with boat-tail geometry and supersonic jet exhaust in a subsonic external flow under zero angle of attack. Similar to the results obtained earlier for the flows around airfoils and wings, current results for the jet flow case corroborate the superiority of the DPM-based ABCs over standard local methodologies from the standpoints of accuracy, overall numerical performance, and robustness DA - 2000/11// PY - 2000/11// DO - 10.2514/2.888 VL - 38 IS - 11 SP - 2014-2022 SN - 0001-1452 1533-385X UR - http://dx.doi.org/10.2514/2.888 ER - TY - CONF TI - A Two-Level Aggregation-Based {Newton-Krylov-Schwarz} Method for Hydrology AU - Jenkins, E W AU - Berger, R C AU - Hallberg, J P AU - Howington, Stacy E AU - Kelley, C T AU - Schmidt, Joseph H AU - Stagg, Alan AU - Tocci, M D A2 - Keyes, D E A2 - Ecer, A A2 - Periaux, J A2 - Satofuka, N C2 - 2000/// C3 - Parallel Computational Fluid Dynamics 1999 DA - 2000/// SP - 257-264 PB - North Holland ER - TY - CONF TI - Broyden Method AU - Kelley, C T A2 - Hazenwinkel, M C2 - 2000/// C3 - Encyclopedia of Mathematics: Supplement II CY - Dordrecht DA - 2000/// SP - 96-98 PB - Kluwer ER - TY - JOUR TI - Mesh Independence of Matrix-Free Methods for Path Following AU - Ferng, W R AU - Kelley, C T T2 - SIAM J. Sci. Comp. DA - 2000/// PY - 2000/// VL - 21 SP - 1835-1850 ER - TY - CONF TI - {Broyden-Fletcher-Goldfarb-Shanno} Method AU - Kelley, C T A2 - Hazenwinkel, M C2 - 2000/// C3 - Encyclopedia of Mathematics: Supplement II CY - Dordrecht DA - 2000/// SP - 95-96 PB - Kluwer ER - TY - RPRT TI - Transformation Approaches for Simulating Flow in Variably Saturated Porous Media AU - Miller, C T AU - Williams, G A AU - Kelley, C T A3 - North Carolina State University, Center for Research in Scientific Computation DA - 2000/1// PY - 2000/1// VL - 36 SP - 923-934 PB - North Carolina State University, Center for Research in Scientific Computation ER - TY - JOUR TI - Strong Convergence of Block-Iterative Outer Approximation Methods for Convex Optimization AU - Combettes, Patrick L. T2 - SIAM Journal on Control and Optimization AB - The strong convergence of a broad class of outer approximation methods for minimizing a convex function over the intersection of an arbitrary number of convex sets in a reflexive Banach space is studied in a unified framework. The generic outer approximation algorithm under investigation proceeds by successive minimizations over the intersection of convex supersets of the feasibility set determined in terms of the current iterate and variable blocks of constraints. The convergence analysis involves flexible constraint approximation and aggregation techniques as well as relatively mild assumptions on the constituents of the problem. Various well-known schemes are recovered as special realizations of the generic algorithm and parallel block-iterative extensions of these schemes are devised within the proposed framework. The case of inconsistent constraints is also considered. DA - 2000/1// PY - 2000/1// DO - 10.1137/s036301299732626x VL - 38 IS - 2 SP - 538-565 J2 - SIAM J. Control Optim. LA - en OP - SN - 0363-0129 1095-7138 UR - http://dx.doi.org/10.1137/s036301299732626x DB - Crossref KW - block-iterative KW - convex feasibility problem KW - convex programming KW - constrained minimization KW - cutting plane KW - fixed point KW - inconsistent constraints KW - outer approximation KW - projection onto an intersection of convex sets KW - reflexive Banach space KW - surrogate cut KW - uniformly convex function ER - TY - CONF TI - Wave propagation in photonic crystal models AU - Venakides, S. AU - Haider, M. A. AU - Papanicolaou, V. T2 - Proceedings of the 4th International Workshop A2 - Dassios, G. A2 - Fotiadis, D. I. A2 - Massalas, C. V. A2 - Kiriaki, K. AB - Abstract : We compute the transmission properties of 2-D electromagnetic TM waves that are normally incident on a Fabry-Perot structure with mirrors consisting of photonic crystals. We use a boundary integral formulation with quadratic boundary elements and utilize the Ewald representation for the Green's functions. We trace the frequencies of the Fabry-Perot cavity modes traversing the photon bandgap as the cavity length increases and calculate corresponding Q-values. For the case of lossy dielectrics, we compare bandgap frequencies and Q-values to experimental results obtained by H. Everitt and his group at Duke University. C2 - 2000/10// C3 - Scattering Theory and Biomedical Engineering Modelling and Applications CY - Peridika, Greece DA - 2000/10// PY - 1999/10/8/ DO - 10.1142/9789812792327_0013 SP - 120–134 PB - World Scientific SN - 9789810243913 9789812792327 UR - http://dx.doi.org/10.1142/9789812792327_0013 ER - TY - CHAP TI - A one-dimensional fluid dynamic model of the systemic arteries AU - Olufsen, M.S. T2 - Mathematical modelling in medicine A2 - Ottesen, Johnny T. A2 - Danielsen, M. T3 - Studies in health technology and informatics PY - 2000/// DO - 10.3233/978-1-60750-915-8-79 SP - 79–97 PB - IOS Press SN - 9781586030261 SV - 71 ER - TY - BOOK TI - Industrial Mathematics: The 1998 CRSC Workshop A3 - Gremaud, P.A. A3 - Li, Z. A3 - Smith, R. C. A3 - Tran, H.T. DA - 2000/// PY - 2000/// PB - SIAM SN - 0898714672 ER - TY - JOUR TI - Radar Sensing of Sea Surface: Some Problems of Numerical Simultaion of Scattering of Electromagnetic Waves, review AU - Gilman, M.A. AU - Sadov, S. Yu AU - Shamaev, A.S. AU - Shamaev, S.I. T2 - Radiotechnics and Electronics DA - 2000/// PY - 2000/// VL - 45 IS - 2 SP - 229–246 ER - TY - JOUR TI - Symmetries of Polynomials AU - Berchenko, Irina AU - Olver, Peter J. T2 - Journal of Symbolic Computation AB - New algorithms for determining discrete and continuous symmetries of polynomials - also known as binary forms in classical invariant theory - are presented, and implemented in MAPLE. The results are based on a new, comprehensive theory of moving frames that completely characterizes the equivalence and symmetry properties of submanifolds under general Lie group actions. DA - 2000/5// PY - 2000/5// DO - 10.1006/jsco.1999.0307 VL - 29 IS - 4-5 SP - 485-514 J2 - Journal of Symbolic Computation LA - en OP - SN - 0747-7171 UR - http://dx.doi.org/10.1006/jsco.1999.0307 DB - Crossref ER - TY - JOUR TI - Self-similar intermediate asymptotics for a degenerate parabolic filtration-absorption equation AU - Barenblatt, G. I. AU - Bertsch, M. AU - Chertock, A. E. AU - Prostokishin, V. M. T2 - Proceedings of the National Academy of Sciences AB - The equation partial differential(t)u = u partial differential(xx)(2)u -(c-1)( partial differential(x)u)(2) is known in literature as a qualitative mathematical model of some biological phenomena. Here this equation is derived as a model of the groundwater flow in a water-absorbing fissurized porous rock; therefore, we refer to this equation as a filtration-absorption equation. A family of self-similar solutions to this equation is constructed. Numerical investigation of the evolution of non-self-similar solutions to the Cauchy problems having compactly supported initial conditions is performed. Numerical experiments indicate that the self-similar solutions obtained represent intermediate asymptotics of a wider class of solutions when the influence of details of the initial conditions disappears but the solution is still far from the ultimate state: identical zero. An open problem caused by the nonuniqueness of the solution of the Cauchy problem is discussed. DA - 2000/8/29/ PY - 2000/8/29/ DO - 10.1073/pnas.97.18.9844 VL - 97 IS - 18 SP - 9844-9848 J2 - Proceedings of the National Academy of Sciences LA - en OP - SN - 0027-8424 1091-6490 UR - http://dx.doi.org/10.1073/pnas.97.18.9844 DB - Crossref ER - TY - JOUR TI - Fluctuations in HIV-1 Viral Load Are Correlated to CD4+ T-Lymphocyte Count During the Natural Course of Infection AU - Masel, Joanna AU - Arnaout, Ramy A. AU - O'Brien, Thomas R. AU - Goedert, James J. AU - Lloyd, Alun L. T2 - JAIDS Journal of Acquired Immune Deficiency Syndromes AB - Background: To find out about the prophylactic value of antiretroviral therapy on HIV-1-associated subclinical and clinical psychomotor slowing as one marker of HIV-1-associated CNS disease. Methods: Prospective study with regular clinical and neurophysiologic examination every three months of 1482 consecutive HIV-1-seropositive and AIDS patients seen at our department till June 30, 1999. Results: Antiretroviral therapy has a significant prophylactic value over an individual observation period of ten years with regard to the first, potentially transient manifestation of HIV-1-associated subclinical psychomotor slowing and with regard to the clinical manifestation of motor signs. However, a subgroup of patients is characterized through a second, more sustained manifestation of subclinical psychomotor slowing which cannot be prevented by any type of currently available antiretroviral therapy. Conclusions: These findings suggest the existence of different pathomechanisms underlying HIV-1-associated brain disease which may in part be effectively prevented, but which in part also escape all antiretroviral treatment strategies in use today. DA - 2000/4// PY - 2000/4// DO - 10.1097/00126334-200004150-00003 VL - 23 IS - 5 SP - 375-379 J2 - JAIDS Journal of Acquired Immune Deficiency Syndromes LA - en OP - SN - 1525-4135 UR - http://dx.doi.org/10.1097/00126334-200004150-00003 DB - Crossref ER - TY - JOUR TI - Local stability analysis of spatially homogeneous solutions of multi-patch systems AU - Jansen, Vincent A.A. AU - Lloyd, Alun L. T2 - Journal of Mathematical Biology DA - 2000/9/1/ PY - 2000/9/1/ DO - 10.1007/s002850000048 VL - 41 IS - 3 SP - 232-252 J2 - Journal of Mathematical Biology OP - SN - 0303-6812 1432-1416 UR - http://dx.doi.org/10.1007/s002850000048 DB - Crossref KW - diffusive instability KW - symmetry breaking KW - metapopulation model KW - coupled map lattice ER - TY - JOUR TI - The Influence of HLA Class I Alleles and Heterozygosity on the Outcome of Human T Cell Lymphotropic Virus Type I Infection AU - Jeffery, Katie J. M. AU - Siddiqui, Asna A. AU - Bunce, Mike AU - Lloyd, Alun L. AU - Vine, Alison M. AU - Witkover, Aviva D. AU - Izumo, Shuji AU - Usuku, Koichiro AU - Welsh, Kenneth I. AU - Osame, Mitsuhiro AU - Bangham, Charles R. M. T2 - The Journal of Immunology AB - The inflammatory disease human T cell lymphotropic virus type I (HTLV-I)-associated myelopathy (HAM/TSP) occurs in only 1-2% of HTLV-I-infected individuals and is associated with a high provirus load of HTLV-I. We hypothesize that a person's risk of developing HAM/TSP depends upon the efficiency of their immune response to the virus, which differs between individuals because of polymorphism in genes that influence this response. Previously we showed that the possession of HLA-A*02 was associated with a lower risk of HAM/TSP, and with a lower provirus load in healthy carriers of HTLV-I. However, HLA-A*02 did not account for all the observed difference in the risk of HAM/TSP. Here we present evidence, in the same study population in Japan, that HLA-Cw*08 was also associated with disease protection (probability value, two-tailed test = 0.002) and with a lower proviral load in healthy carriers. Possession of the A*02 and/or Cw*08 genes prevented 36% of potential HAM/TSP cases. In contrast, HLA-B*5401 was associated with a higher susceptibility to HAM/TSP (probability value, two-tailed test = 0.0003) and with a higher provirus load in HAM/TSP patients. At a given provirus load, B*5401 appeared to increase the risk of disease. The fraction of HAM/TSP cases attributable to B*5401 was 17%. Furthermore, individuals who were heterozygous at all three HLA class I loci have a lower HTLV-I provirus load than those who were homozygous at one or more loci. These results are consistent with the proposal that a strong class I-restricted CTL response to HTLV-I reduces the proviral load and hence the risk of disease. DA - 2000/12/15/ PY - 2000/12/15/ DO - 10.4049/jimmunol.165.12.7278 VL - 165 IS - 12 SP - 7278-7284 J2 - J Immunol LA - en OP - SN - 0022-1767 1550-6606 UR - http://dx.doi.org/10.4049/jimmunol.165.12.7278 DB - Crossref ER - TY - JOUR TI - Numerical Simulation and Experimental Validation of Blood Flow in Arteries with Structured-Tree Outflow Conditions AU - Olufsen, Mette S. AU - Peskin, Charles S. AU - Kim, Won Yong AU - Pedersen, Erik M. AU - Nadim, Ali AU - Larsen, Jesper T2 - Annals of Biomedical Engineering DA - 2000/11// PY - 2000/11// DO - 10.1114/1.1326031 VL - 28 IS - 11 SP - 1281-1299 J2 - Annals of Biomedical Engineering LA - en OP - SN - 0090-6964 UR - http://dx.doi.org/10.1114/1.1326031 DB - Crossref KW - arterial blood flow KW - arterial modeling KW - blood flow modeling KW - arterial outflow conditions KW - biofluid dynamics KW - mathematical modeling ER - TY - JOUR TI - On the Lego-Teichmüller game AU - Bakalov, B. AU - Kirillov, A., Jr. T2 - Transformation Groups DA - 2000/9// PY - 2000/9// DO - 10.1007/bf01679714 VL - 5 IS - 3 SP - 207-244 J2 - Transformation Groups LA - en OP - SN - 1083-4362 1531-586X UR - http://dx.doi.org/10.1007/bf01679714 DB - Crossref ER - TY - JOUR TI - Strict Stability of High-Order Compact Implicit Finite-Difference Schemes: The Role of Boundary Conditions for Hyperbolic PDEs, I AU - Abarbanel, Saul S. AU - Chertock, Alina E. T2 - Journal of Computational Physics AB - Temporal, or “strict,” stability of approximation to PDEs is much more difficult to achieve than the “classical” Lax stability. In this paper, we present a class of finite-difference schemes for hyperbolic initial boundary value problems in one and two space dimensions that possess the property of strict stability. The approximations are constructed so that all eigenvalues of corresponding differentiation matrix have a nonpositive real part. Boundary conditions are imposed by using penalty-like terms. Fourth- and sixth-order compact implicit finite-difference schemes are constructed and analyzed. Computational efficacy of the approach is corroborated by a series of numerical tests in 1-D and 2-D scalar problems. DA - 2000/5// PY - 2000/5// DO - 10.1006/jcph.2000.6420 VL - 160 IS - 1 SP - 42-66 J2 - Journal of Computational Physics LA - en OP - SN - 0021-9991 UR - http://dx.doi.org/10.1006/jcph.2000.6420 DB - Crossref KW - hyperbolic PDEs KW - boundary conditions KW - stability KW - accuracy KW - error bounds ER - TY - JOUR TI - Strict Stability of High-Order Compact Implicit Finite-Difference Schemes: The Role of Boundary Conditions for Hyperbolic PDEs, II AU - Abarbanel, Saul S. AU - Chertock, Alina E. AU - Yefet, Amir T2 - Journal of Computational Physics AB - This paper deals with the problem of systems of hyperbolic PDEs in one and two space dimensions, using the theory of part I [7]. DA - 2000/5// PY - 2000/5// DO - 10.1006/jcph.2000.6421 VL - 160 IS - 1 SP - 67-87 J2 - Journal of Computational Physics LA - en OP - SN - 0021-9991 UR - http://dx.doi.org/10.1006/jcph.2000.6421 DB - Crossref KW - hyperbolic PDEs KW - boundary conditions KW - stability KW - accuracy KW - error bounds ER - TY - JOUR TI - Optimization of Automotive Valve Train Components with Implict Filtering AU - Choi, T.D. AU - Eslinger, O.J. AU - Kelley, C.T. AU - David, J.W. AU - Etheridge, M. T2 - Optimization and Engineering DA - 2000/// PY - 2000/// VL - 1 SP - 9–28 ER - TY - JOUR TI - Non-Reflecting Artificial Boundary Conditions for the Replacement of Truncated Equations with Lacunae AU - Ryaben’kii, V.S. AU - Turchaninov, V.I. AU - Tsynkov, S.V. T2 - Mathematical Modeling DA - 2000/// PY - 2000/// VL - 12 IS - 12 SP - 108–127 ER - TY - JOUR TI - Mathematical Model of Airflow in the Lungs of Children II: Effects of Ventilatory Parameters AU - Guan, X. AU - Segal, R. A. AU - Shearer, M. AU - Martonen, T. B. T2 - Journal of Theoretical Medicine AB - In an effort to develop more effective aerosol therapy procedures, we examined airflow patterns in the lung of a child (age four years). In particular, we were concerned with how ventilatory parameters (i.e., breathing rate and tidal volume) affected the patterns of airflow around tumors. To conduct the study, a computational fluid dynamics package, FIDAP was used to define a model lung. The results of simulations show the extent to which changing ventilatory parameters can affect flow patterns in the neighborhood of the tumors as well as drug distribution throughout the lung. DA - 2000/// PY - 2000/// DO - 10.1080/10273660008833064 VL - 3 IS - 1 SP - 51-62 J2 - Journal of Theoretical Medicine LA - en OP - SN - 1027-3662 1607-8578 UR - http://dx.doi.org/10.1080/10273660008833064 DB - Crossref ER - TY - JOUR TI - Mathematical Model of Airflow in the Lungs of Children I: Effects of Tumor Sizes and Locations AU - Segal, R. A. AU - Guan, X. AU - Shearer, M. AU - Martonen, T. B. T2 - Journal of Theoretical Medicine AB - To contribute to the development of more effective aerosol therapy protocols in pediatric medicine, we examined airflow patterns in the lung of a four-year-old child. In particular, we addressed how the presence of tumors in airways affected the character of airflow patterns. To study the effects of tumors we employed a computational fluid dynamics package, FIDAP, to define flow conditions within a model lung. The results indicated that tumors have a pronounced affect on both (i) localized velocity profiles in airways and (ii) bulk flow distribution within the lung. By identifying the effects of physical factors on flow conditions the findings will lead to improved drug delivery regimens. DA - 2000/// PY - 2000/// DO - 10.1080/10273660008833046 VL - 2 IS - 3 SP - 199-213 J2 - Journal of Theoretical Medicine LA - en OP - SN - 1027-3662 1607-8578 UR - http://dx.doi.org/10.1080/10273660008833046 DB - Crossref ER - TY - ER - TY - JOUR TI - Global artificial boundary conditions for computation of external flows with jets AU - Tsynkov, Semyon AU - Abarbanel, Saul AU - Nordstrom, Jan AU - Ryaben'kii, Victor AU - Vasta, Veer T2 - AIAA Journal DA - 2000/1// PY - 2000/1// DO - 10.2514/3.14645 VL - 38 SP - 2014-2022 J2 - AIAA Journal LA - en OP - SN - 0001-1452 1533-385X UR - http://dx.doi.org/10.2514/3.14645 DB - Crossref ER - TY - JOUR TI - Sun Leaper, a hybrid tomato, and its parent, NCHS-1 AU - Gardner, R. G. T2 - HortScience DA - 2000/// PY - 2000/// VL - 35 IS - 5 SP - 960-961 ER - TY - JOUR TI - Poiseuille and thermal-creep flow in a cylindrical tube AU - Siewert, CE T2 - JOURNAL OF COMPUTATIONAL PHYSICS AB - A version of the discrete-ordinates method is used to solve, for the case of flow in a cylindrical tube, the classical Poiseuille and thermal-creep problems based on the Bhatnagar, Gross, and Krook model in the theory of rarefied-gas dynamics. In addition to the development of a discrete-ordinates solution that is valid for a wide range of the Knudsen number, the solution is evaluated numerically for selected cases to yield results, thought to be correct to many significant figures, for the slip velocities, the macroscopic velocity profiles, and the flow rates. DA - 2000/5/20/ PY - 2000/5/20/ DO - 10.1006/jcph.2000.6464 VL - 160 IS - 2 SP - 470-480 SN - 0021-9991 ER - TY - CONF TI - On a general descriptor LQ problem AU - Nikoukhah, R. AU - Campbell, S. L. AU - Delebecque, F. C2 - 2000/// C3 - Proceedings of the 8th IEEE Mediterranean Conference on Control & Automation: July 17-19, 2000, University of Patras, Patras, Greece. CN - TJ212.2 .I325 2000 DA - 2000/// ER - TY - CONF TI - Computational experience with exploiting order variation in mesh refinement for direct transcription methods AU - Betts, J. T. AU - Biehn, N. AU - Campbell, S. L. AU - Huffman, W.P. C2 - 2000/// C3 - Proceedings: 16th IMACS World Congress. DA - 2000/// PB - New Brunswick, NJ: IMACS ER - TY - JOUR TI - The order of groups satisfying a converse to Lagrange's theorem AU - Jing, NH T2 - MATHEMATIKA AB - One of the converse statements to Lagrange's theorem is that, for each subgroup H of G and any prime factor p of |G: H|, there exists a subgroup K such that H≤K≤G with |K: H | = p. This paper treats integers n such that all groups of order n have this property. DA - 2000/// PY - 2000/// DO - 10.1112/S0025579300015813 VL - 47 IS - 93-94 SP - 197-204 SN - 0025-5793 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0039013810&partnerID=MN8TOARS ER - TY - CONF TI - Rapid model selection and the separability index AU - Campbell, Stephen AU - Horton, K. AU - Nikoukhah, R. AU - Delebecque, F. AB - Under the assumption that one of two given models is the real underlying model of the system, a proper auxiliary signal is defined as an input signal that allows one to select the correct model. It is assumed that there is no knowledge prior to the beginning of the application of the auxiliary signal and that detection is to be done within a specified detection horizon. Under the assumption that the noise energy is bounded, the separability index is defined as the least energy of a proper auxiliary signal. A method for computation of this index is presented. C2 - 2000/// C3 - Fault detection, supervision and safety for technical processes 2000 (SAFEPROCESS 2000): A proceedings volume from the 4th IFAC Symposium, Budapest, Hungary, 14-16 June 2000 CN - TJ212.2 .I325 2000 DA - 2000/// DO - 10.1016/s1474-6670(17)37517-1 SP - 1187–1192 PB - Oxford, UK; New York: Published for the International Federation of Automatic Control by Pergamon ER - TY - CONF TI - Convergence of nonconvergent IRK discretizations of optimal control problems AU - Betts, J. T. AU - Biehn, N. AU - Campbell, S. L. AU - Huffman, W.P. C2 - 2000/// C3 - Proceedings: 16th IMACS World Congress. DA - 2000/// PB - New Brunswick, NJ: IMACS ER - TY - BOOK TI - Matrix analysis and applied linear algebra AU - Meyer, C. D. CN - QA188 .M495 2000 DA - 2000/// PY - 2000/// PB - Philadelphia: Society for Industrial and Applied Mathematics SN - 0898714540 ER - TY - JOUR TI - Compensating for order variation in mesh refinement for direct transcription methods AU - Betts, JT AU - Biehn, N AU - Campbell, SL AU - Huffman, WP T2 - JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS AB - The numerical theory for Implicit Runge–Kutta methods shows that there can be order reduction when these methods are applied to either stiff or differential algebraic equations. This paper discusses how this theory can be utilized in direct transcription trajectory optimization by modifying a currently used mesh refinement strategy. DA - 2000/12/15/ PY - 2000/12/15/ DO - 10.1016/S0377-0427(00)00465-9 VL - 125 IS - 1-2 SP - 147-158 SN - 0377-0427 KW - implicit Runge-Kutta KW - optimization KW - differential algebraic equation ER - TY - JOUR TI - Analysis and comparison of four anhysteretic polarization models for lead magnesium niobate AU - Piquette, JC AU - Smith, RC T2 - JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA AB - Four anhysteretic polarization models that have been used in the literature to evaluate data acquired from lead magnesium niobate (PMN) are analyzed and compared. Derivations of two of the models from assumed spatial distributions of dipole energy states, using first physical principles, are presented. A third model is derived from a suitable integral averaging calculation. These derivations are used as the basis for developing an integral equation for determining an energy-state distribution that produces a fourth model, which was not originally formulated in terms of an assumed distribution. A new polarization function is also presented. Excellent approximations to each of the four polarization functions of interest can be deduced from this new polarization function by adjusting the numerical value of just a single parameter. An application of two of the models to data is presented. It is shown that it can be necessary to consider a sample to be an admixture of two distinct species of poles, in the sense that two polarization functions must be added together in order to accommodate the data. DA - 2000/10// PY - 2000/10// DO - 10.1121/1.1310670 VL - 108 IS - 4 SP - 1651-1662 SN - 0001-4966 ER - TY - JOUR TI - Algebra structures on Hom (C, L) AU - Barnich, G AU - Fulp, R AU - Lada, T AU - Stasheff, J T2 - COMMUNICATIONS IN ALGEBRA AB - Abstract We consider the space of linear maps from a coassociative coalgebra C into a Lie algebra L. Unless C has a cocommutative coproduct, the usual symmetry properties of the induced bracket on Hom(C L) fail to hold. We define the concept of twisted domain (TD) algebras in order to recover the symmetries and also construct a modified Chevalley-Eilenbcrg complex in order to define the cohomology of such algebras. *Research supported in part by NSF grant DMS-9803435 *Research supported in part by NSF grant DMS-9803435 Notes *Research supported in part by NSF grant DMS-9803435 DA - 2000/// PY - 2000/// DO - 10.1080/00927870008827169 VL - 28 IS - 11 SP - 5481-5501 SN - 0092-7872 ER - TY - JOUR TI - q-wedge modules for quantized enveloping algebras of classical type AU - Jing, NH AU - Misra, KC AU - Okado, M T2 - JOURNAL OF ALGEBRA AB - We use the fusion construction in the twisted quantum affine algebras to obtain a unified method to deform the wedge product for classical Lie algebras. As a byproduct we uniformly realize all non-spin fundamental modules for quantized enveloping algebras of classical types, and show that they admit natural crystal bases as modules for the (derived) twisted quantum affine algebra. These crystal bases are parametrized in terms of the $q$-wedge products. DA - 2000/8/15/ PY - 2000/8/15/ DO - 10.1006/jabr.2000.8325 VL - 230 IS - 2 SP - 518-539 SN - 0021-8693 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0034662533&partnerID=MN8TOARS ER - TY - JOUR TI - The temperature-jump problem in rarefied-gas dynamics AU - Barichello, LB AU - Siewert, CE T2 - EUROPEAN JOURNAL OF APPLIED MATHEMATICS AB - An analytical version of the discrete-ordinates method is used here to solve the classical temperature-jump problem based on the BGK model in rarefied-gas dynamics. In addition to a complete development of the discrete-ordinates method for the application considered, the computational algorithm is implemented to yield very accurate results for the temperature jump and the complete temperature and density distributions in the gas. The algorithm is easy to use, and the developed code runs typically in less than a second on a 400 MHz Pentium-based PC. DA - 2000/8// PY - 2000/8// DO - 10.1017/S0956792599004180 VL - 11 SP - 353-364 SN - 0956-7925 ER - TY - JOUR TI - On state constraint representations and mesh-dependent gradient projection convergence rates for optimal control problems AU - Dunn, JC T2 - SIAM JOURNAL ON CONTROL AND OPTIMIZATION AB - Two distinct nonlinear programming formulations are investigated for ODE optimal control problems with pointwise state and control constraints. The first formulation treats the differential equations of state as an equality constraint in the conventional manner. The second formulation employs a different equality constraint entailing the integrated state transition map. Related convergence rate estimates are developed for augmented gradient projection methods and discrete-time approximations to a large representative class of ODE control problems. In the first formulation, the rate estimates are mesh-dependent, and the predicted number of inner loop gradient projection iterations needed to achieve a fixed small deviation from the optimal value of the augmented Lagrangian is inversely proportional to the square of the mesh width. In the second formulation, the convergence rates and predicted iteration counts are mesh-invariant. The computational costs-per-iteration in the two formulations are comparable. These estimates elucidate previously published numerical experiments with augmented gradient projection% AGP methods and constrained regulator problems. DA - 2000/12/20/ PY - 2000/12/20/ DO - 10.1137/S0363012999351656 VL - 39 IS - 4 SP - 1082-1111 SN - 0363-0129 KW - optimal control KW - pointwise state/control constraints KW - regulator problems KW - nonlinear programs KW - constrain representations KW - discrete-time approximations KW - gradient projection methods KW - mesh-dependent convergence rates ER - TY - JOUR TI - Gaussian filters for nonlinear filtering problems AU - Ito, K AU - Xiong, KQ T2 - IEEE TRANSACTIONS ON AUTOMATIC CONTROL AB - We develop and analyze real-time and accurate filters for nonlinear filtering problems based on the Gaussian distributions. We present the systematic formulation of Gaussian filters and develop efficient and accurate numerical integration of the optimal filter. We also discuss the mixed Gaussian filters in which the conditional probability density is approximated by the sum of Gaussian distributions. A new update rule of weights for Gaussian sum filters is proposed. Our numerical tests demonstrate that new filters significantly improve the extended Kalman filter with no additional cost, and the new Gaussian sum filter has a nearly optimal performance. DA - 2000/5// PY - 2000/5// DO - 10.1109/9.855552 VL - 45 IS - 5 SP - 910-927 SN - 0018-9286 ER - TY - JOUR TI - Effect of Ar+ ion beam in the process of plasma surface modification of PET films AU - Hyun, J AU - Barletta, P AU - Koh, K AU - Yoo, S AU - Oh, J AU - Aspnes, DE AU - Cuomo, JJ T2 - JOURNAL OF APPLIED POLYMER SCIENCE AB - In general, plasma modified polymer surfaces tend to show short aging time and rapid hydrophobic recovery after treatment. To prevent reorientation from the surface to the bulk, appropriate crosslinking is necessary among the polymer chains. In this work, an Ar+ ion beam was used to provide crosslinking to the surface. Crosslinking was shown by spectroscopic ellipsometry, AFM, and FTIR. Contact angle measurements were performed to see the aging of the modified surfaces. The surface modified with Ar+ ion beam followed by RF plasma treatment exhibited reduced chain mobility and a highly stable hydrophilic surface. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1679–1683, 2000 DA - 2000/8/22/ PY - 2000/8/22/ DO - 10.1002/1097-4628(20000822)77:8<1679::AID-APP4>3.0.CO;2-F VL - 77 IS - 8 SP - 1679-1683 SN - 0021-8995 KW - polymer KW - plasma KW - ion beam KW - crosslinking KW - hydrophilic ER - TY - JOUR TI - Approximation methods for inverse problems governed by nonlinear parabolic systems AU - Banks, HT AU - Musante, CJ AU - Raye, JK T2 - NUMERICAL FUNCTIONAL ANALYSIS AND OPTIMIZATION AB - Abstract We present a rigorous theoretical framework for approximation of nonlinear parabolic systems with delays in the context of inverse least squares problems. Convergence of approximate optimal parameters and that of forward solutions in the context of semidiscrete Galerkin schemes are given. Sample numerical results demonstrating the convergence are given for a model of dioxin uptake and elimination in a distributed liver model that is a special case of the general theoretical framework. Keywords: Inverse problemsnonlinear parabolic systemsapproximation techniquesleast squares optimizationcomputational methods *This research was supported in part by the Air Force Office of Scientific Research (AFOSR) under Grants F-49620-95-1-0236, F-49620-98-1-0180, F-49620-95-1-0375, and F-49620-93-1-0355 The research of CJM and JKR was funded by US Department of Education Graduate Assistance in Areas of National Need (GAANN) Fellowships under Grants P200A50075 and P200A70707, respectively. CJM also received support from the 1997 AFOSR Graduate Summer Research Program and the Armstrong Laboratory. Part of this research was carried out while HTB and CJM were visitors of the Institut Henri Poincare, Centre Emile Borel. † Author to whom correspondence should be addressed. ‡ Current address: U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Experimental Toxicology Division, Mail Drop 74, Research Triangle Park, NC 27711. *This research was supported in part by the Air Force Office of Scientific Research (AFOSR) under Grants F-49620-95-1-0236, F-49620-98-1-0180, F-49620-95-1-0375, and F-49620-93-1-0355 The research of CJM and JKR was funded by US Department of Education Graduate Assistance in Areas of National Need (GAANN) Fellowships under Grants P200A50075 and P200A70707, respectively. CJM also received support from the 1997 AFOSR Graduate Summer Research Program and the Armstrong Laboratory. Part of this research was carried out while HTB and CJM were visitors of the Institut Henri Poincare, Centre Emile Borel. † Author to whom correspondence should be addressed. ‡ Current address: U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Experimental Toxicology Division, Mail Drop 74, Research Triangle Park, NC 27711. Notes *This research was supported in part by the Air Force Office of Scientific Research (AFOSR) under Grants F-49620-95-1-0236, F-49620-98-1-0180, F-49620-95-1-0375, and F-49620-93-1-0355 The research of CJM and JKR was funded by US Department of Education Graduate Assistance in Areas of National Need (GAANN) Fellowships under Grants P200A50075 and P200A70707, respectively. CJM also received support from the 1997 AFOSR Graduate Summer Research Program and the Armstrong Laboratory. Part of this research was carried out while HTB and CJM were visitors of the Institut Henri Poincare, Centre Emile Borel. † Author to whom correspondence should be addressed. ‡ Current address: U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Experimental Toxicology Division, Mail Drop 74, Research Triangle Park, NC 27711. DA - 2000/// PY - 2000/// DO - 10.1080/01630560008816986 VL - 21 IS - 7-8 SP - 791-816 SN - 0163-0563 KW - inverse problems KW - nonlinear parabolic systems KW - approximation techniques KW - least squares optimization KW - computational methods ER - TY - JOUR TI - An approximation theory or strongly stabilizing solutions to the operator LQ Riccati equation AU - Oostveen, JC AU - Curtain, RF AU - Ito, K T2 - SIAM JOURNAL ON CONTROL AND OPTIMIZATION AB - The linear-quadratic (LQ) control problem is considered for a class of infinite-dimensional systems with bounded input and output operators, that are not exponentially stabilizable, but only strongly stabilizable. A sufficient condition for the existence of a minimizing control and of a stabilizing solution to the associated LQ Riccati equation is given. The main contribution of this paper is the convergence of the stabilizing solutions of a sequence of finite-dimensional Riccati equations to the strongly stabilizing solution of the infinite-dimensional Riccati equation. The result is applied to a model of propagation of sound waves in a one-dimensional wave-guide. DA - 2000/8/4/ PY - 2000/8/4/ DO - 10.1137/S0363012998339691 VL - 38 IS - 6 SP - 1909-1937 SN - 0363-0129 KW - linear quadratic control problem KW - algebraic Riccati equation on Hilbert space KW - dissipative systems KW - collocated actuators and sensors ER - TY - JOUR TI - A model of gonadotropin regulation during the menstrual cycle in women: Qualitative features AU - Schlosser, PM AU - Selgrade, JF T2 - ENVIRONMENTAL HEALTH PERSPECTIVES DA - 2000/10// PY - 2000/10// DO - 10.2307/3454321 VL - 108 SP - 873-881 SN - 0091-6765 KW - estradiol KW - follicle-stimulating hormone KW - luteinizing hormone KW - mathematical model KW - menstrual cycle KW - progesterone ER - TY - JOUR TI - Existence of undercompressive traveling waves in thin film equations AU - Bertozzi, AL AU - Shearer, M T2 - SIAM JOURNAL ON MATHEMATICAL ANALYSIS AB - We consider undercompressive traveling wave solutions of the partial differential equation $$\partial_t h+ \partial_x f(h) = -\partial_x(h^3\partial_x^3 h) + D\partial_x(h^3 \partial_x h),$$ when the flux function f has the nonconvex form f(h) = h2 -h3 . In numerical simulations, these waves appear to play a central role in the dynamics of the PDE; they also explain unusual phenomena in experiments of driven contact lines modeled by the PDE. We prove existence of an undercompressive traveling wave solution for sufficiently small nonnegative D and nonexistence when D is sufficiently large. DA - 2000/6/23/ PY - 2000/6/23/ DO - 10.1137/S0036141099350894 VL - 32 IS - 1 SP - 194-213 SN - 1095-7154 KW - undercompressive shocks KW - traveling waves KW - heteroclinic orbit KW - existence ER - TY - JOUR TI - Detection signal design for failure detection: a robust approach AU - Nikoukhah, R AU - Campbell, SL AU - Delebecque, F T2 - INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING AB - The detection signal is an input signal that enhances the detectability of failure. Assuming that the normal and the failed behaviours of a process can be modelled by two linear systems subject to bounded energy perturbations, a method for constructing a minimum energy detection signal, which guarantees detection of failure is presented. The on-line implementation of the failure decision filter is also considered. Copyright © 2000 John Wiley & Sons, Ltd. DA - 2000/11// PY - 2000/11// DO - 10.1002/1099-1115(200011)14:7<701::AID-ACS617>3.0.CO;2-6 VL - 14 IS - 7 SP - 701-724 SN - 0890-6327 KW - failure detection KW - diagnosis KW - auxiliary signal ER - TY - JOUR TI - Computing orbits of minimal parabolic k-subgroups acting on symmetric k-varieties AU - Helminck, AG T2 - JOURNAL OF SYMBOLIC COMPUTATION AB - In this paper we present an algorithm to compute the orbits of a minimal parabolic k -subgroup acting on a symmetric k -variety and most of the combinatorial structure of the orbit decomposition. This algorithm can be implemented in LiE, GAP4, Magma, Maple or in a separate program. These orbits are essential in the study of symmetric k -varieties and their representations. In a similar way to the special case of a Borel subgroup acting on the symmetric variety, (see A. G. Helminck. Computing B -orbits on G / H. J. Symb. Comput.,21 , 169–209, 1996.) one can use the associated twisted involutions in the restricted Weyl group to describe these orbits (see A. G. Helminck and S. P. Wang. On rationality properties of involutions of reductive groups. Adv. Math., 99, 26–96, 1993). However, the orbit structure in this case is much more complicated than the special case of orbits of a Borel subgroup. We will first modify the characterization of the orbits of minimal parabolic k -subgroups acting on the symmetric k -varieties given in Helminck and Wang (1993), to illuminate the similarity to the one for orbits of a Borel subgroup acting on a symmetric variety in Helminck (1996). Using this characterization we show how the algorithm in Helminck (1996) can be adjusted and extended to compute these twisted involutions as well. DA - 2000/11// PY - 2000/11// DO - 10.1006/jsco.2000.0395 VL - 30 IS - 5 SP - 521-553 SN - 0747-7171 ER - TY - JOUR TI - A domain wall model for hysteresis in piezoelectric materials AU - Smith, RC AU - Ounaies, Z T2 - JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES DA - 2000/1// PY - 2000/1// DO - 10.1177/104538900772664413 VL - 11 IS - 1 SP - 62-79 SN - 1045-389X ER - TY - JOUR TI - A coupled structural-magnetic strain and stress model for magnetostrictive transducers AU - Dapino, M. J. AU - Smith, Ralph AU - Faidley, L. E. AU - Flatau, A. B. T2 - Journal of Intelligent Material Systems and Structures AB - This paper addresses the modeling of strains and forces generated by magnetostrictive transducers in response to applied magnetic fields. The magnetostrictive effect is modeled by considering both the rotation of magnetic moments in response to the field and the elastic vibrations in the transducer. The former is modeled with the Jiles-Atherton model of ferromagnetic hysteresis in combination with a quartic magnetostriction law. The latter is modeled through force balancing which yields a PDE system with magnetostrictive inputs and boundary conditions given by the specific transducer design. The solution to this system provides both rod displacements and forces. The calculated forces are used to quantify the magnetomechanical effect in the transducer core, i.e., the stress-induced magnetization changes. This is done by considering a “law of approach” to the anhysteretic magnetization. The resulting model provides a representation of the bidirectional coupling between the magnetic and elastic states. It is demonstrated that the model accurately characterizes the magnetic hysteresis in the material, as well as the strains and forces output by the transducer under conditions typical of engineering applications. DA - 2000/// PY - 2000/// DO - 10.1106/MJ6A-FBP9-9M61-0E1F VL - 11 IS - 2 SP - 135–152 ER - TY - JOUR TI - Stable and unstable solitary-wave solutions of the generalized regularized long-wave equation AU - Bona, JL AU - McKinney, WR AU - Restrepo, JM T2 - JOURNAL OF NONLINEAR SCIENCE AB - Investigated here are interesting aspects of the solitary-wave solutions of the generalized Regularized Long-Wave equation $$u_t + u_x + \alpha \left( {u^p } \right)_x - \beta u_{xxt} = 0.$$ For p>5, the equation has both stable and unstable solitary-wave solutions, according to the theory of Souganidis and Strauss. Using a high-order accurate numerical scheme for the approximation of solutions of the equation, the dynamics of suitably perturbed solitary waves are examined. Among other conclusions, we find that unstable solitary waves may evolve into several, stable solitary waves and that positive initial data need not feature solitary waves at all in its long-time asymptotics. DA - 2000/// PY - 2000/// DO - 10.1007/s003320010003 VL - 10 IS - 6 SP - 603-638 SN - 1432-1467 KW - BBM equation KW - generalized BBM equation KW - RLW equation KW - generalized RLW equation KW - stable solitary-waves KW - unstable solitary-waves ER - TY - JOUR TI - Remarks on the Schur-Howe-Sergeev duality AU - Cheng, SJ AU - Wang, WQ T2 - LETTERS IN MATHEMATICAL PHYSICS DA - 2000/4// PY - 2000/4// DO - 10.1023/A:1007668930652 VL - 52 IS - 2 SP - 143-153 SN - 0377-9017 KW - Lie superalgebra q(n) KW - Schur-Howe-Sergeev duality ER - TY - JOUR TI - Feedback control methodologies for nonlinear systems AU - Beeler, SC AU - Tran, HT AU - Banks, HT T2 - JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS AB - A number of computational methods have been proposed in the literature to design and synthesize feedback controls when the plant is modeled by nonlinear dynamics. However, it is not immediately clear which is the best method for a given problem; this may depend on the nature of the nonlinearities, size of the system, whether the amount of control used or time needed for the method is a concern, and other factors. In this paper, a comprehensive comparison study of five methods for the synthesis of nonlinear control systems is carried out. The performance of the methods on several test problems are studied, and some recommendations are made as to which feedback control method is best to use under various conditions. DA - 2000/10// PY - 2000/10// DO - 10.1023/A:1004607114958 VL - 107 IS - 1 SP - 1-33 SN - 0022-3239 KW - nonlinear optimal feedback control KW - Hamilton-Jacobi-Bellman equation KW - state-dependent Riccati equation KW - interpolation of open-loop controls ER - TY - CHAP TI - Dynamics of a Volterra-Lotka competition model with diffusion and time delays, integral and integro differential equations AU - Pao, C. V. T2 - Integral and integrodifferential equations: Theory, method and applications (Series in mathematical analysis and applications ; v.2 ) A2 - Agarwal, R. P. A2 - O'Regan, D. CN - QA431 .I469 2000 PY - 2000/// VL - 2 SP - 269-277 PB - Amsterdam: Gordon and Breach Science Publishers ER - TY - JOUR TI - Covariant field theory on frame bundles of fibered manifolds AU - McLean, M AU - Norris, LK T2 - JOURNAL OF MATHEMATICAL PHYSICS AB - We show that covariant field theory for sections of π : E→M lifts in a natural way to the bundle of vertically adapted linear frames LπE. Our analysis is based on the fact that LπE is a principal fiber bundle over the bundle of 1-jets J1π. On LπE the canonical soldering 1-forms play the role of the contact structure of J1π. A lifted Lagrangian ℒ: LπE→R is used to construct modified soldering 1-forms, which we refer to as the Cartan–Hamilton–Poincaré 1-forms. These 1-forms on LπE pass to the quotient to define the standard Cartan–Hamilton–Poincaré m-form on J1π. We derive generalized Hamilton–Jacobi and Hamilton equations on LπE, and show that the Hamilton–Jacobi and canonical equations of Carathéodory–Rund and de Donder–Weyl are obtained as special cases. DA - 2000/10// PY - 2000/10// DO - 10.1063/1.1288797 VL - 41 IS - 10 SP - 6808-6823 SN - 0022-2488 ER - TY - JOUR TI - Vertex representations via finite groups and the McKay correspondence AU - Frenkel, IB AU - Jing, NH AU - Wang, WQ T2 - INTERNATIONAL MATHEMATICS RESEARCH NOTICES AB - Given a finite group $\Gamma$ and a virtual character $\wt$ on it, we construct a Fock space and associated vertex operators in terms of representation ring of wreath products $\Gamma\sim S_n$. We recover the character tables of wreath products $\Gamma\sim S_n$ by vertex operator calculus. When $\Gamma$ is a finite subgroup of $SU_2$, our construction yields a group theoretic realization of the basic representations of the affine and toroidal Lie algebras of $ADE$ type, which can be regarded as a new form of McKay correspondence. DA - 2000/// PY - 2000/// DO - 10.1155/s107379280000012x VL - 2000 IS - 4 SP - 195-222 SN - 1687-0247 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0347016085&partnerID=MN8TOARS ER - TY - JOUR TI - Transformation approaches for simulating flow in variably saturated porous media AU - Williams, GA AU - Miller, CT AU - Kelley, CT T2 - WATER RESOURCES RESEARCH AB - Sharp fronts with rapid changes in fluid saturations over short distance and timescales often exist in multiphase flow in subsurface systems. Such highly nonlinear problems are notoriously difficult to solve, and standard solution approaches are often inefficient and unreliable. We summarize four existing and one new transformation method (IT2) for solving Richards'; equation within a common framework and compare performance for a range of medium properties and simulation conditions. The new IT2 transform is defined as a linear combination of volumetric water fraction of the aqueous phase and integrated hydraulic conductivity terms. We show that transformation methods can significantly improve solution efficiency and robustness compared to standard solution approaches; optimal transformation parameters depend upon auxiliary conditions, medium properties, and spatial and temporal discretization and are difficult to evaluate a priori; and IT2 compares favorably with existing transforms. DA - 2000/4// PY - 2000/4// DO - 10.1029/1999WR900349 VL - 36 IS - 4 SP - 923-934 SN - 0043-1397 ER - TY - JOUR TI - Stability of the human respiratory control system II. Analysis of a three-dimensional delay state-space model AU - Batzel, JJ AU - Tran, HT T2 - JOURNAL OF MATHEMATICAL BIOLOGY DA - 2000/7// PY - 2000/7// DO - 10.1007/s002850000045 VL - 41 IS - 1 SP - 80-102 SN - 0303-6812 KW - respiratory control models KW - time delay KW - delay dependent stability KW - instability KW - numerical simulations ER - TY - JOUR TI - Stability of the human respiratory control system I. Analysis of a two-dimensional delay state-space model AU - Batzel, JJ AU - Tran, HT T2 - JOURNAL OF MATHEMATICAL BIOLOGY DA - 2000/7// PY - 2000/7// DO - 10.1007/s002850000044 VL - 41 IS - 1 SP - 45-79 SN - 1432-1416 KW - respiratory control models KW - time delay KW - delay-dependent stability KW - instability KW - numerical simulations ER - TY - JOUR TI - Singularly perturbed control systems using non-commutative computer algebra AU - Helton, JW AU - Kronewitter, FD AU - McEneaney, WM AU - Stankus, M T2 - INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL DA - 2000/// PY - 2000/// DO - 10.1002/1099-1239(200009/10)10:11/12<983::AID-RNC535>3.0.CO;2-# VL - 10 IS - 11-12 SP - 983-1003 SN - 1049-8923 KW - non-commutative algebra KW - computer algebra KW - dynamic control KW - singular perturbation KW - control systems ER - TY - JOUR TI - On orbit closures of symmetric subgroups in flag varieties AU - Brion, M AU - Helminck, AG T2 - CANADIAN JOURNAL OF MATHEMATICS-JOURNAL CANADIEN DE MATHEMATIQUES AB - Abstract We study K -orbits in G/P where G is a complex connected reductive group, P ⊆ G is a parabolic subgroup, and K ⊆ G is the fixed point subgroup of an involutive automorphism θ . Generalizing work of Springer, we parametrize the (finite) orbit set K \ G/P and we determine the isotropy groups. As a consequence, we describe the closed (resp. affine) orbits in terms of θ -stable (resp. θ -split) parabolic subgroups. We also describe the decomposition of any ( K, P )-double coset in G into ( K, B )-double cosets, where B ⊆ P is a Borel subgroup. Finally, for certain K -orbit closures X ⊆ G/B , and for any homogeneous line bundle on G/B having nonzero global sections, we show that the restriction map res X : H 0 ( G/B , ) → H 0 ( X , ) is surjective and that H i ( X , ) = 0 for i ≥ 1. Moreover, we describe the K -module H 0 ( X , ). This gives information on the restriction to K of the simple G -module H 0 ( G/B , ). Our construction is a geometric analogue of Vogan and Sepanski’s approach to extremal K -types. DA - 2000/4// PY - 2000/4// DO - 10.4153/CJM-2000-012-9 VL - 52 IS - 2 SP - 265-292 SN - 1496-4279 ER - TY - BOOK TI - Derivatives in financial markets with stochastic volatility AU - Fouque, J.-P AU - Papanicolaou, G. AU - Sircar, K. R. CN - HG6024 .A3 F68 2000 DA - 2000/// PY - 2000/// PB - Cambridge; New York: Cambridge University Press SN - 0521791634 ER - TY - JOUR TI - Constitutive hydrolytic enzymes are associated with polygenic resistance of tomato to Alternaria solani and may function as an elicitor release mechanism AU - Lawrence, CB AU - Singh, NP AU - Qiu, JS AU - Gardner, RG AU - Tuzun, S T2 - PHYSIOLOGICAL AND MOLECULAR PLANT PATHOLOGY AB - Foliar resistance to early blight disease of tomato, caused by the necrotrophic fungus Alternaria solani, is inherited in a complex quantitative manner. Our previous studies revealed that three moderately-resistant tomato breeding lines with different sources of early blight resistance, all possessed higher constitutive and more rapid accumulation of PR proteins, including specific antifungal isozymes of chitinase and β-1,3-glucanase than susceptible genotypes. In the present study, additional early blight resistant tomato breeding lines and susceptible genotypes were investigated for their constitutive levels of PR proteins. All resistant lines possessed higher constitutive levels of chitinase and β-1,3-glucanase than susceptible genotypes supporting earlier reported findings. Constitutive and pathogen-induced expression of PR genes during early stages of the interaction was found to be much higher in the highly resistant breeding line NC 24-E than a susceptible line.In vitro elicitor release experiments were performed with purified A. solani cell walls treated with constitutive total enzyme preparations isolated from resistant and susceptible plants. Enzyme preparations from resistant and susceptible genotypes differed in their ability to produce hypersensitive response (HR) elicitors from fungal cell walls: the enzyme preparations from resistant breeding lines released HR elicitors, while enzyme preparations from susceptible lines did not. Additionally, experiments with a partially purified preparation of basic tomato chitinases demonstrated that these enzymes were able to release HR elicitors from germinating spores of A. solani, but not mature, intact cell walls. The possibility that constitutively produced hydrolytic enzymes may act as an elicitor-releasing mechanism in resistance to early blight of tomato is discussed. DA - 2000/11// PY - 2000/11// DO - 10.1006/pmpp.2000.0298 VL - 57 IS - 5 SP - 211-220 SN - 0885-5765 KW - Alternaria solani KW - Lycopersicon esculentum KW - pathogenesis-related proteins ER - TY - JOUR TI - Comparison of computer simulations of total lung deposition to human subject data in healthy test subjects AU - Segal, RA AU - Martonen, TB AU - Kim, CS T2 - JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION AB - A mathematical model was used to predict the deposition fractions (DF) of PM within human lungs. Simulations using this computer model were previously validated with human subject data and were used as a control case. Human intersubject variation was accounted for by scaling the base lung morphology dimensions based on measured functional residual capacity (FRC) values. Simulations were performed for both controlled breathing (tidal volumes [VT] of 500 and 1000 mL, respiratory times [T] from 2 to 8 sec) and spontaneous breathing conditions. Particle sizes ranged from 1 to 5 microns. The deposition predicted from the computer model compared favorably with the experimental data. For example, when VT = 1000 mL and T = 2 sec, the error was 1.5%. The errors were slightly higher for smaller tidal volumes. Because the computer model is deterministic (i.e., derived from first principles of physics), the model can be used to predict deposition fractions for a range of situations (i.e., for different ventilatory parameters and particle sizes) for which data are not available. Now that the model has been validated, it may be applied to risk assessment efforts to estimate the inhalation hazards of airborne pollutants. DA - 2000/7// PY - 2000/7// DO - 10.1080/10473289.2000.10464155 VL - 50 IS - 7 SP - 1262-1268 SN - 1047-3289 ER - TY - JOUR TI - Approximation of the Kushner equation for nonlinear filtering AU - Ito, K AU - Rozovskii, B T2 - SIAM JOURNAL ON CONTROL AND OPTIMIZATION AB - In this paper we discuss the well-posedness and approximation of solutions to the Kushner equation in nonlinear filtering problems. We develop and analyze a time integration method based on the operator splitting. Also, we discuss its relation to the operator-splitting method for the Zakai equation. DA - 2000/3/16/ PY - 2000/3/16/ DO - 10.1137/S0363012998344270 VL - 38 IS - 3 SP - 893-915 SN - 0363-0129 KW - Kushner equation KW - operator-splitting method ER - TY - JOUR TI - Some comments on DAE theory for IRK methods and trajectory optimization AU - Biehn, N AU - Campbell, SL AU - Jay, L AU - Westbrook, T T2 - JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS AB - It has been observed elsewhere in the literature that the activation of constraints in a trajectory optimization problem can lead to higher index DAEs. Several existing codes can handle a number of these constrained problems. In this note we will discuss why the situation is more complex than just saying a higher index DAE occurs. The discussion is in the context of a specific industrial code SOCS but the observations made here have relevance for a number of methods and have implications for what types of test problems a code should be tested on. DA - 2000/8/1/ PY - 2000/8/1/ DO - 10.1016/S0377-0427(00)00306-X VL - 120 IS - 1-2 SP - 109-131 SN - 0377-0427 KW - implicit Runge-Kutta KW - optimization KW - differential algebraic equation ER - TY - JOUR TI - Reduced order model compensator control of species transport in a CVD reactor AU - Kepler, GM AU - Tran, HT AU - Banks, HT T2 - OPTIMAL CONTROL APPLICATIONS & METHODS AB - We propose the use of proper orthogonal decomposition (POD) techniques as a reduced basis method for computation of feedback controls and compensators in a high-pressure chemical vapour deposition (HPCVD) reactor. In this paper, we present a proof-of-concept computational implementation of this method with a simplified growth example for III–V layers in which we implement Dirichlet boundary control of a dilute Group III reactant transported by convection and diffusion to an absorbing substrate with no reactions. We implement the model-based feedback control using a reduced order state estimator based on observations of the flux of reactant at the substrate centre. This is precisely the type of measurements available with current sensing technology. We demonstrate that the reduced order state estimator or compensator system is capable of substantial control authority when applied to a high-order system. In principle, these ideas can be extended to more general HPCVD control situations by including multiple species with gas-phase reactions and surface reactions. Copyright © 2000 John Wiley & Sons, Ltd. DA - 2000/// PY - 2000/// DO - 10.1002/1099-1514(200007/08)21:4<143::AID-OCA671>3.0.CO;2-Y VL - 21 IS - 4 SP - 143-160 SN - 0143-2087 KW - linear quadratic control KW - proper orthogonal decomposition KW - reduced order model KW - chemical vapour deposition KW - Dirichlet boundary control ER - TY - JOUR TI - Preconditioning highly indefinite and nonsymmetric matrices AU - Benzi, M. AU - Haws, J. C. AU - Tuma, M. T2 - SIAM Journal on Scientific Computing DA - 2000/// PY - 2000/// VL - 22 IS - 4 SP - 1333-1353 ER - TY - JOUR TI - Periodic solutions of parabolic systems with time delays AU - Pao, CV T2 - JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS AB - Existence of maximal and minimal periodic solutions of a coupled system of parabolic equations with time delays and with nonlinear boundary conditions is discussed. The proof of the existence theorem is based on the method of upper and lower solutions and its associated monotone iterations. This method is constructive and can be used to develop a computational algorithm for numerical solutions of the periodic-parabolic system. An application is given to a competitor-competitor-mutualist model which consists of a coupled system of three reaction-diffusion equations with time delays. DA - 2000/11/1/ PY - 2000/11/1/ DO - 10.1006/jmaa.2000.7045 VL - 251 IS - 1 SP - 251-263 SN - 1096-0813 ER - TY - JOUR TI - Optimal control of elliptic variational inequalities AU - Ito, K AU - Kunisch, K T2 - APPLIED MATHEMATICS AND OPTIMIZATION DA - 2000/// PY - 2000/// DO - 10.1007/s002459911017 VL - 41 IS - 3 SP - 343-364 SN - 0095-4616 KW - optimal control KW - variational inequalities KW - augmented Lagrangians KW - Lagrange multipliers KW - active set methods KW - strict complementarity ER - TY - JOUR TI - Multisplitting methods: Optimal schemes for the unknowns in a given overlap AU - White, RE T2 - SIAM JOURNAL ON MATRIX ANALYSIS AND APPLICATIONS AB - Consider a linear algebraic problem where the set of unknowns is a union of subsets. Let the coefficient matrix have a splitting associated with each subset. The traditional multisplitting method forms a weighted sum, over the overlapping unknowns, of the iterates for each such splitting to obtain a single parallel iterative method. An optimal alternative to the weighted sums will be presented. Convergence of this new form of multisplitting (MS) method can be studied for both symmetric positive definite (SPD) matrices and M-matrices. Applications to PDEs and the equilibrium equations for fluid flow in a driven cavity will be presented. DA - 2000/9/20/ PY - 2000/9/20/ DO - 10.1137/S0895479898334678 VL - 22 IS - 2 SP - 554-568 SN - 0895-4798 KW - multisplitting KW - comparison KW - fluid flow ER - TY - JOUR TI - Modeling instability in the control system for human respiration: applications to infant non-REM sleep AU - Batzel, JJ AU - Tran, HT T2 - APPLIED MATHEMATICS AND COMPUTATION AB - Mathematical models of the human respiratory control system have been developed since 1940 to study a wide range of features of this complex system. The phenomena collectively referred to as periodic breathing (including Cheyne–Stokes respiration and apneustic breathing) have important medical implications. The hypothesis that periodic breathing is the result of delay in the feedback signals to the respiratory control system has been studied since the work of F.S. Grodins, J. Gray, A.I. Norins, R.W. Jones [J. Appl. Physiol. 1 (1954) 283–308] in the early 1950s. The purpose of this paper is to extend the model presented by M.C.K. Khoo, R.E. Kronauer, K.P. Strohl, A.S. Slutsky [J. Appl. Physiol. 53 (3) (1982) 644–659] in 1991 to include variable delay in the feedback control loop and to study the phenomena of periodic breathing and apnea as they occur during quiet sleep in infant sleep respiration at around 4 months of age. The nonlinear mathematical model consists of a feedback control system of five delay differential equations. Numerical simulations are performed to study instabilities in the control system and the occurrence of periodic breathing and apnea in the above case which is a time frame of high incidence of sudden infant death syndrome (SIDS). DA - 2000/4/1/ PY - 2000/4/1/ DO - 10.1016/s0096-3003(99)00112-5 VL - 110 IS - 1 SP - 1-51 SN - 0096-3003 ER - TY - JOUR TI - Markov chain sensitivity measured by mean first passage times AU - Cho, GE AU - Meyer, CD T2 - LINEAR ALGEBRA AND ITS APPLICATIONS AB - The purpose of this article is to present results concerning the sensitivity of the stationary probabilities for an n-state, time-homogeneous, irreducible Markov chain in terms of the mean first passage times in the chain. DA - 2000/9/1/ PY - 2000/9/1/ DO - 10.1016/S0024-3795(99)00263-3 VL - 316 IS - 1-3 SP - 21-28 SN - 1873-1856 KW - Markov chains KW - stationary distribution KW - mean first passage times KW - stochastic matrix KW - sensitivity analysis KW - perturbation theory KW - stability of a Markov chain KW - condition numbers ER - TY - JOUR TI - Energy-based hysteresis model for magnetostrictive transducers AU - Calkins, FT AU - Smith, RC AU - Flatau, AB T2 - IEEE TRANSACTIONS ON MAGNETICS AB - This paper addresses the modeling of hysteresis in magnetostrictive transducers in the context of control applications that require an accurate characterization of the relation between input currents and strains output by the transducer. This relation typically exhibits significant nonlinearities and hysteresis because of inherent properties of magnetostrictive materials. The characterization considered here is based on the Jiles-Atherton mean field model for ferromagnetic hysteresis in combination with a quadratic moment rotation model for magnetostriction. As demonstrated by comparison with experimental data, the magnetization model very adequately quantifies both major and minor loops under various operating conditions. The combined model can then be used to accurately characterize output strains at moderate drive levels. The advantages of this model lie in the small number (six) of required parameters and its flexibility under a variety of operating conditions. DA - 2000/3// PY - 2000/3// DO - 10.1109/20.825804 VL - 36 IS - 2 SP - 429-439 SN - 0018-9464 KW - hysteresis model KW - magnetorestrictive transducer ER - TY - JOUR TI - Dynamical analysis of density-dependent selection in a discrete one-island migration model AU - Roberds, JH AU - Selgrade, JF T2 - MATHEMATICAL BIOSCIENCES AB - A system of non-linear difference equations is used to model the effects of density-dependent selection and migration in a population characterized by two alleles at a single gene locus. Results for the existence and stability of polymorphic equilibria are established. Properties for a genetically important class of equilibria associated with complete dominance in fitness are described. The birth of an unusual chaotic attractor is also illustrated. This attractor is produced when migration causes chaotic dynamics on a boundary of phase space to bifurcate into the interior of phase space, resulting in bistable genetic polymorphic behavior. DA - 2000/3// PY - 2000/3// DO - 10.1016/s0025-5564(00)00002-x VL - 164 IS - 1 SP - 1-15 SN - 0025-5564 KW - selection KW - migration KW - genotype KW - density-dependence KW - bifurcation ER - TY - JOUR TI - Domain decomposition splittings AU - White, RE T2 - LINEAR ALGEBRA AND ITS APPLICATIONS AB - Domain decomposition splittings have the form A=B−C, where B has a nonzero arrow pattern. By using Schur complement one can study these splittings for both the symmetric positive-definite (SPD) and the M-matrix cases. Convergence results and some comparison results will be given. DA - 2000/9/1/ PY - 2000/9/1/ DO - 10.1016/S0024-3795(00)00016-1 VL - 316 IS - 1-3 SP - 105-112 SN - 0024-3795 KW - domain decomposition KW - Schur complement KW - M-matrix ER - TY - JOUR TI - An overview of relative sin Theta theorems for invariant subspaces of complex matrices AU - Ipsen, ICF T2 - JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS AB - Relative perturbation bounds for invariant subspaces of complex matrices are reviewed, with emphasis on bounding the sines of the largest principal angle between two subspaces, i.e. sinΘ theorems. The goal is to provide intuition, as well as an idea for why the bounds hold and why they look the way they do. Relative bounds have the advantage of being better at exploiting structure in a perturbation than absolute bounds. Therefore the reaction of subspaces to relative perturbations can be different than to absolute perturbations. In particular, there are certain classes of relative perturbations to which subspaces of indefinite Hermitian matrices can be more sensitive than subspaces of definite matrices. DA - 2000/11/1/ PY - 2000/11/1/ DO - 10.1016/S0377-0427(00)00404-0 VL - 123 IS - 1-2 SP - 131-153 SN - 1879-1778 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0034322243&partnerID=MN8TOARS KW - invariant subspace KW - eigenspace KW - relative bound KW - eigenvalues KW - grading KW - scaling ER - TY - JOUR TI - A mathematical framework for the linear reconstructor problem in adaptive optics AU - Chu, MT AU - Pauca, VP AU - Plemmons, RJ AU - Sun, XB T2 - LINEAR ALGEBRA AND ITS APPLICATIONS AB - The wave front field aberrations induced by atmospheric turbulence can severely degrade the performance of an optical imaging system. Adaptive optics refers to the process of removing unwanted wave front distortions in real time, i.e., before the image is formed, with the use of a phase corrector. The basic idea in adaptive optics is to control the position of the surface of a deformable mirror in such a way as to approximately cancel the atmospheric turbulence effects on the phase of the incoming light wave front. A phase computation system, referred to as a reconstructor, transforms the output of a wave front sensor into a set of drive signals that control the shape of a deformable mirror. The control of a deformable mirror is often based on a linear wave front reconstruction algorithm that is equivalent to a matrix–vector multiply. The matrix associated with the reconstruction algorithm is called the reconstructor matrix. Since the entire process, from the acquisition of wave front measurements to the positioning of the surface of the deformable mirror, must be performed at speeds commensurate with the atmospheric changes, the adaptive optics control imposes several challenging computational problems. The goal of this paper is twofold: (i) to describe a simplified yet feasible mathematical framework that accounts for the interactions among main components involved in an adaptive optics imaging system, and (ii) to present several ways to estimate the reconstructor matrix based on this framework. The performances of these various reconstruction techniques are illustrated using some simple computer simulations. DA - 2000/9/1/ PY - 2000/9/1/ DO - 10.1016/S0024-3795(00)00019-7 VL - 316 IS - 1-3 SP - 113-135 SN - 0024-3795 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0034392470&partnerID=MN8TOARS KW - adaptive optics KW - atmospheric turbulence KW - deformable mirror KW - linear reconstruction KW - minimum variance estimator KW - adaptive control ER - TY - JOUR TI - A fast recursive algorithm for constructing matrices with prescribed eigenvalues and singular values AU - Chu, MT T2 - SIAM JOURNAL ON NUMERICAL ANALYSIS AB - The Weyl--Horn theorem characterizes a relationship between the eigenvalues and the singular values of an arbitrary matrix. Based on that characterization, a fast recursive algorithm is developed to construct numerically a matrix with prescribed eigenvalues and singular values. Besides being of theoretical interest, the technique could be employed to create test matrices with desired spectral features. Numerical experiment shows this algorithm to be quite efficient and robust. DA - 2000/3/9/ PY - 2000/3/9/ DO - 10.1137/S0036142998339301 VL - 37 IS - 3 SP - 1004-1020 SN - 0036-1429 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0012087393&partnerID=MN8TOARS KW - eigenvalues KW - singular values KW - inverse problems KW - Weyl-Horn theorem KW - recursive algorithm ER - TY - JOUR TI - Superlinear convergence and implicit filtering AU - Choi, TD AU - Kelley, CT T2 - SIAM JOURNAL ON OPTIMIZATION AB - In this paper we show how the implicit filtering algorithm can be coupled with the BFGS quasi-Newton update to obtain a superlinearly convergent iteration if the noise in the objective function decays sufficiently rapidly as the optimal point is approached. In this way we give insight into the observations of good performance in practice of quasi-Newton methods when they are coupled with implicit filtering. We also report on numerical experiments that show how an implementation of implicit filtering that exploits these new results can improve the performance of the algorithm. DA - 2000/6/18/ PY - 2000/6/18/ DO - 10.1137/S1052623499354096 VL - 10 IS - 4 SP - 1149-1162 SN - 1052-6234 KW - noisy optimization KW - implicit filtering KW - BFGS algorithm KW - superlinear convergence ER - TY - JOUR TI - Reduced-order model feedback control design: Numerical implementation in a thin shell model AU - Banks, HT AU - Rosario, RCH AU - Smith, RC T2 - IEEE TRANSACTIONS ON AUTOMATIC CONTROL AB - Reduced-order models employing the Lagrange and popular proper orthogonal decomposition (POD) reduced-basis methods in numerical approximation and feedback control of systems are presented and numerically tested. The system under consideration is a thin cylindrical shell with surface-mounted piezoceramic actuators. Donnell-Mushtari equations, modified to include Kelvin-Voigt damping, are used to model the system dynamics. Basis functions constructed from Fourier polynomials tensored with cubic splines are employed in the Galerkin expansion of the full-order model. Reduced-basis elements are then formed from full order approximations of the exogenously excited shell taken at different time instances. Numerical examples illustrating the features of the reduced-basis methods are presented. As a first step toward investigating the behavior of the methods when implemented in physical systems, the use of reduced-order model feedback control gains in the full order model is considered and numerical examples are presented. DA - 2000/7// PY - 2000/7// DO - 10.1109/9.867024 VL - 45 IS - 7 SP - 1312-1324 SN - 0018-9286 KW - LQR feedback control KW - proper orthogonal decomposition KW - reduced-basis computational methods KW - thin shell dynamics ER - TY - JOUR TI - Quantum Z-algebras and representations of quantum affine algebras AU - Jing, NH T2 - COMMUNICATIONS IN ALGEBRA AB - Generalizing our earlier work, we introduce the homogeneous quantum Z-algebras for all quantum affine algebras U q(gcirc;) of type one. With the new algebras we unite previously scattered realizations of quantum affine algebras in various cases. As a result we find a realization of . DA - 2000/// PY - 2000/// DO - 10.1080/00927870008826863 VL - 28 IS - 2 SP - 829-844 SN - 1532-4125 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-26044457008&partnerID=MN8TOARS KW - quantum enveloping algebras KW - quantum Z-operators KW - vertex operators KW - Hopf algebras ER - TY - JOUR TI - Plum Dandy, a hybrid tomato, and its parents, NC EBR-5 and NC EBR-6 AU - Gardner, R. G. T2 - HortScience DA - 2000/// PY - 2000/// VL - 35 IS - 5 SP - 962-963 ER - TY - JOUR TI - Paths, Demazure crystals, and symmetric functions AU - Kuniba, A AU - Misra, KC AU - Okado, M AU - Takagi, T AU - Uchiyama, J T2 - JOURNAL OF MATHEMATICAL PHYSICS AB - The path realization of Demazure crystals is reviewed and Demazure characters in the light of symmetric functions are discussed. DA - 2000/9// PY - 2000/9// DO - 10.1063/1.1286284 VL - 41 IS - 9 SP - 6477-6486 SN - 1089-7658 ER - TY - JOUR TI - Nondestructive evaluation using a reduced-order computational methodology AU - Banks, HT AU - Joyner, ML AU - Wincheski, B AU - Winfree, WP T2 - INVERSE PROBLEMS AB - This paper uses eddy current based techniques and reduced-order modelling to explore the feasibility of detecting subsurface damage in structures such as air foils and pipelines. To identify the geometry of the damage, an optimization algorithm is employed which requires solving the forward problem numerous times. To implement these methods in a practical setting, the forward algorithm must be solved with extremely fast and accurate solution methods. Therefore, our computational methods are based on the reduced-order Karhunen-Loeve or proper orthogonal decomposition techniques. For proof of concept, we implement the methodology on a 2D problem and find the methods to be efficient and robust even with data containing 10% relative noise. Furthermore, the methods are fast: our findings suggest we can reduce the computational time on average by a factor of 3000. DA - 2000/8// PY - 2000/8// DO - 10.1088/0266-5611/16/4/304 VL - 16 IS - 4 SP - 929-945 SN - 0266-5611 ER - TY - JOUR TI - Linearly compact rings having a simple group of units AU - Cohen, JA AU - Berry, E T2 - COMMUNICATIONS IN ALGEBRA AB - Those linearly compact rings with identity having a simple group of units and a transfinitely nilpotent Jacobson radical are identified. A consequence of this characterization is Cohen and Koh's classification theorem for compact rings with identity having a simple group of units. DA - 2000/// PY - 2000/// DO - 10.1080/00927870008826826 VL - 28 IS - 1 SP - 33-49 SN - 0092-7872 ER - TY - JOUR TI - Carolina Gold, a hybrid tomato, and its parents, NC1Y and NC2Y AU - Gardner, R. G. T2 - HortScience DA - 2000/// PY - 2000/// VL - 35 IS - 5 SP - 966-967 ER - TY - JOUR TI - A male-sterile cherry tomato breeding line, NC2C ms-10,aa AU - Gardner, R. G. T2 - HortScience DA - 2000/// PY - 2000/// VL - 35 IS - 5 SP - 964-965 ER - TY - JOUR TI - Schild's ladder parallel transport procedure for an arbitrary connection AU - Kheyfets, A. AU - Miller, W. A. AU - Newton, G. A. T2 - International Journal of Theoretical Physics DA - 2000/// PY - 2000/// DO - 10.1023/A:1026473418439 VL - 39 IS - 12 SP - 2891-2898 ER - TY - JOUR TI - Relationships between QBO in the lower equatorial stratospheric zonal winds and east African seasonal rainfall AU - Indeje, M AU - Semazzi, FHM T2 - METEOROLOGY AND ATMOSPHERIC PHYSICS DA - 2000/// PY - 2000/// DO - 10.1007/s007030050075 VL - 73 IS - 3-4 SP - 227-244 SN - 0177-7971 ER - TY - JOUR TI - Real-time thickness and compositional control of Ga1-xInxP growth using p-polarized reflectance AU - Woods, V AU - Dietz, N AU - Ito, K AU - Lauko, I T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS AB - Advances in the engineering and design of advanced electro-optical materials require sensors and control strategies that allow tight control over thickness and composition of multilayered structures. In response to this demand, we developed and applied p-polarized reflectance (PR) for real-time optical characterization and control of heteroepitaxial GaP/GaInP growth under pulsed chemical beam epitaxy conditions. For closed-loop control, we applied nonlinear control algorithms (based on nonlinear Kalman filtering) that utilizes the PR signals to adjust the source flows involved in the heteroepitaxial growth of Ga1−xInxP on Si(001). A reduced order surface kinetics model has been formulated to establish the linkage between the surface reaction kinetic and its optical response. These data are linked to compute the compositional and thickness change per time unit, utilizing the monitored PR signals for validation. This allows the establishment of feedback control algorithms, able to control both the growth rate and composition of Ga1−xInxP heterostructures. DA - 2000/// PY - 2000/// DO - 10.1116/1.582469 VL - 18 IS - 4 SP - 1190-1195 SN - 0734-2101 ER - TY - JOUR TI - Quantum vertex representations via finite groups and the McKay correspondence AU - Frenkel, IB AU - Jing, NH AU - Wang, WQ T2 - COMMUNICATIONS IN MATHEMATICAL PHYSICS AB - We establish a q-analog of our recent work on vertex representations and the McKay correspondence. For each finite group Γ we construct a Fock space and associated vertex operators in terms of wreath products of $Γ×ℂ× and the symmetric groups. An important special case is obtained when Γ is a finite subgroup of SU 2, where our construction yields a group theoretic realization of the representations of the quantum affine and quantum toroidal algebras of ADE type. DA - 2000/4// PY - 2000/4// DO - 10.1007/s002200050817 VL - 211 IS - 2 SP - 365-393 SN - 0010-3616 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0347016085&partnerID=MN8TOARS ER - TY - JOUR TI - Periodic solutions of systems of parabolic equations in unbounded domains AU - Pao, CV T2 - NONLINEAR ANALYSIS-THEORY METHODS & APPLICATIONS DA - 2000/// PY - 2000/// DO - 10.1016/s0362-546x(00)85031-2 VL - 40 IS - 1-8 SP - 523-535 SN - 1873-5215 KW - parabolic system KW - periodic solution KW - existence and stability KW - upper and lower solutions KW - maximal and minimal solutions ER - TY - JOUR TI - On the classification of k-involutions AU - Helminck, AG T2 - ADVANCES IN MATHEMATICS AB - Let G be a connected reductive algebraic group defined over a field k of characteristic not 2, θ an involution of G defined over k, H a k-open subgroup of the fixed point group of θ, and Gk (resp. Hk) the set of k-rational points of G (resp. H). The variety Gk/Hk is called a symmetric k-variety. These varieties occur in many problems in representation theory, geometry, and singularity theory. Over the last few decades the representation theory of these varieties has been extensively studied for k=R and C. As most of the work in these two cases was completed, the study of the representation theory over other fields, like local fields and finite fields, began. The representations of a homogeneous space usually depend heavily on the fine structure of the homogeneous space, like the restricted root systems with Weyl groups, etc. Thus it is essential to study first this structure and the related geometry. In this paper we give a characterization of the isomorphy classes of these symmetric k-varieties together with their fine structure of restricted root systems and also a classification of this fine structure for the real numbers, p-adic numbers, finite fields and number fields. DA - 2000/7/15/ PY - 2000/7/15/ DO - 10.1006/aima.1998.1884 VL - 153 IS - 1 SP - 1-117 SN - 0001-8708 KW - symmetric spaces KW - symmetric varieties KW - k-involutions ER - TY - JOUR TI - Finite difference reaction-diffusion equations with nonlinear diffusion coefficients AU - Wang, JH AU - Pao, CV T2 - NUMERISCHE MATHEMATIK DA - 2000/5// PY - 2000/5// DO - 10.1007/s002110000140 VL - 85 IS - 3 SP - 485-502 SN - 0029-599X ER - TY - JOUR TI - Boundary integral calculations of two-dimensional electromagnetic scattering by photonic crystal Fabry-Perot structures AU - Venakides, S. AU - Haider, Mansoor A AU - Papanicolaou, V. T2 - SIAM Journal on Applied Mathematics AB - We compute the transmission properties of two-dimensional (2-D) electromagnetic transverse magnetic (TM) waves that are normally incident on a Fabry--Perot structure with mirrors consisting of photonic crystals. We use a boundary integral formulation with quadratic boundary elements and utilize the Ewald representation for Green's functions. We trace the frequencies of the Fabry--Perot cavity modes traversing the photonic bandgap as the cavity length increases and calculate corresponding Q-values. DA - 2000/// PY - 2000/// DO - 10.1137/s0036139999350779 VL - 60 IS - 5 SP - 1686–1706 ER - TY - JOUR TI - Renewal and circulation of intermediate waters in the Canadian Basin observed on the SCICEX 96 cruise AU - Smethie, WM AU - Schlosser, P AU - Bonisch, G AU - Hopkins, TS T2 - JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS AB - During the summer of 1996 the nuclear submarine USS Pogy occupied a line of stations extending through the middle of the Canadian Basin between about 88°N, 44°W (Lomonosov Ridge) and about 78°N, 144°W (center of the Canada Basin). CTD/Niskin bottle casts extending to 1600 m were carried out at eight stations, providing the first high‐quality temperature, salinity, CFC, tritium, and 3 He data obtained from this region, although XCTD data had previously been collected in this region. These data, along with data from stations at the basin boundary to the south and west, reveal the presence of well‐ventilated intermediate water beneath the halocline in the center of the Canada Basin, indicating renewal times of the order of 1–2 decades. The least ventilated intermediate water was observed at the northern end of the Canada Basin along the southern flank of the Alpha Ridge. Intermediate water is derived from the Atlantic Ocean and enters the Arctic Ocean through Fram Strait and the Barents Sea. It flows around the Arctic basins in boundary currents and splits in the eastern Amundsen Basin with one branch crossing the Lomonosov Ridge and flowing along the East Siberian continental slope and the other flowing along the Eurasian flank of the Lomonosov Ridge. From the 1996 Scientific Ice Expedition (SCICEX 96) observations we conclude that the branch that flows along the East Siberian continental slope transports this water to the Chukchi Rise, where it apparently enters the central Canada Basin with some flow continuing along the boundary to the southern Canada Basin. The Fram Strait Branch Water mixes extensively with waters from the Canadian Basin during its transit along the East Siberian continental slope, being diluted by a factor of about 5 by the time it reaches the central Canada Basin. The Barents Sea Branch Water does not undergo such extensive mixing and is diluted by a factor of only about 2 when it reaches the central Canada Basin. DA - 2000/1/15/ PY - 2000/1/15/ DO - 10.1029/1999jc900233 VL - 105 IS - C1 SP - 1105-1121 SN - 2169-9291 ER - TY - JOUR TI - Numerical determination of flow corrective inserts for granular materials in conical hoppers AU - Gremaud, PA AU - Schaeffer, DG AU - Shearer, M T2 - INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS AB - The flow of granular materials in hoppers is studied. In industrial applications, inserts of various sizes and shapes are often used to improve the flow properties and get rid of undesirable effects such as material sticking to the walls, funnel flow, arching, etc. We study the case of inverted conical inserts in conical hoppers. In spite of the complexity of the phenomenon as observed in practice, existing methods assume in general a radial structure of the stress and velocity fields. A new numerical approach to the problem of designing “optimal” inserts is proposed and tested. It allows for non-purely radial solutions. General comments about the overall approach and its relationship with experiments are offered. DA - 2000/9// PY - 2000/9// DO - 10.1016/S0020-7462(99)00064-5 VL - 35 IS - 5 SP - 869-882 SN - 0020-7462 ER - TY - JOUR TI - Structural magnetic strain model for magnetostrictive transducers AU - Dapino, MJ AU - Smith, RC AU - Flatau, AB T2 - IEEE TRANSACTIONS ON MAGNETICS AB - This paper addresses the modeling of strains generated by magnetostrictive transducers in response to applied magnetic fields. The measured strains depend on both the rotation of moments within the material in response to the field and the elastic properties of the material. The magnetic behavior is characterized by considering the Jiles-Atherton mean field theory for ferromagnetic hysteresis in combination with a quadratic moment rotation model for magnetostriction. Elastic properties must be incorporated to account for the dynamics of the material as it vibrates. This is modeled by force balancing, which yields a wave equation with magnetostrictive inputs. The validity of the resulting transducer model is illustrated by comparison with experimental data. DA - 2000/5// PY - 2000/5// DO - 10.1109/20.846217 VL - 36 IS - 3 SP - 545-556 SN - 0018-9464 KW - hysteresis KW - magnetomechanical model KW - magnetostrictive transducer ER - TY - JOUR TI - Augmented Lagrangian methods for nonsmooth, convex optimization in Hilbert spaces AU - Ito, K AU - Kunisch, K T2 - NONLINEAR ANALYSIS-THEORY METHODS & APPLICATIONS DA - 2000/8// PY - 2000/8// DO - 10.1016/S0362-546X(98)00299-5 VL - 41 IS - 5-6 SP - 591-616 SN - 0362-546X KW - optimality conditions for nonsmooth optimization problems KW - augmented Lagrangian techniques KW - bingham flow KW - image restoration KW - friction problem KW - optimal control ER - TY - JOUR TI - A putative role for the tomato genes DUMPY and CURL-3 in brassinosteroid biosynthesis and response AU - Koka, CV AU - Cerny, RE AU - Gardner, RG AU - Noguchi, T AU - Fujioka, S AU - Takatsuto, S AU - Yoshida, S AU - Clouse, SD T2 - PLANT PHYSIOLOGY AB - Abstract Thedumpy (dpy) mutant of tomato (Lycopersicon esculentum Mill.) exhibits short stature, reduced axillary branching, and altered leaf morphology. Application of brassinolide and castasterone rescued the dpyphenotype, as did C-23-hydroxylated, 6-deoxo intermediates of brassinolide biosynthesis. The brassinolide precursors campesterol, campestanol, and 6-deoxocathasterone failed to rescue, suggesting thatdpy may be affected in the conversion of 6-deoxocathasterone to 6-deoxoteasterone, similar to the Arabidopsisconstitutive photomorphogenesis and dwarfism(cpd) mutant. Measurements of endogenous brassinosteroid levels by gas chromatography-mass spectrometry were consistent with this hypothesis. To examine brassinosteroid-regulated gene expression in dpy, we performed cDNA subtractive hybridization and isolated a novel xyloglucan endotransglycosylase that is regulated by brassinosteroid treatment. The curl-3(cu-3) mutant (Lycopersicon pimpinellifolium [Jusl.] Mill.) shows extreme dwarfism, altered leaf morphology, de-etiolation, and reduced fertility, all strikingly similar to the Arabidopsis mutantbrassinosteroid insensitive 1 (bri1). Primary root elongation of wild-type L. pimpinellifoliumseedlings was strongly inhibited by brassinosteroid application, whilecu-3 mutant roots were able to elongate at the same brassinosteroid concentration. Moreover, cu-3 mutants retained sensitivity to indole-3-acetic acid, cytokinins, gibberellin, and abscisic acid while showing hypersensitivity to 2,4-dichlorophenoxyacetic acid in the root elongation assay. Thecu-3 root response to hormones, coupled with itsbri1-like phenotype, suggests that cu-3may also be brassinosteroid insensitive. DA - 2000/1// PY - 2000/1// DO - 10.1104/pp.122.1.85 VL - 122 IS - 1 SP - 85-98 SN - 0032-0889 ER - TY - JOUR TI - Particular solutions for the discrete-ordinates method AU - Barichello, LB AU - Garcia, RDM AU - Siewert, CE T2 - JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER AB - A full-range orthogonality relation is developed and used to construct the infinite-medium Green’s function for a general form of the discrete-ordinates approximation to the transport equation in plane geometry. The Green’s function is then used to define a particular solution that is required in the solution of inhomogeneous versions of the discrete-ordinates equations. DA - 2000/2// PY - 2000/2// DO - 10.1016/S0022-4073(98)00146-0 VL - 64 IS - 3 SP - 219-226 SN - 0022-4073 ER - TY - BOOK TI - Applications of abstract algebra with Maple AU - Klima, R. E. AU - Sigmon, N. AU - Stitzinger, E. CN - QA162 .K65 2000 DA - 2000/// PY - 2000/// PB - Boca Raton, FL: CRC Press SN - 0849381703 ER - TY - JOUR TI - An axisymmetric boundary integral model for incompressible linear viscoelasticity: Application to the micropipette aspiration contact problem AU - Haider, MA AU - Guilak, F T2 - JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME AB - The micropipette aspiration test has been used extensively in recent years as a means of quantifying cellular mechanics and molecular interactions at the microscopic scale. However, previous studies have generally modeled the cell as an infinite half-space in order to develop an analytical solution for a viscoelastic solid cell. In this study, an axisymmetric boundary integral formulation of the governing equations of incompressible linear viscoelasticity is presented and used to simulate the micropipette aspiration contact problem. The cell is idealized as a homogeneous and isotropic continuum with constitutive equation given by three-parameter (E, tau 1, tau 2) standard linear viscoelasticity. The formulation is used to develop a computational model via a "correspondence principle" in which the solution is written as the sum of a homogeneous (elastic) part and a nonhomogeneous part, which depends only on past values of the solution. Via a time-marching scheme, the solution of the viscoelastic problem is obtained by employing an elastic boundary element method with modified boundary conditions. The accuracy and convergence of the time-marching scheme are verified using an analytical solution. An incremental reformulation of the scheme is presented to facilitate the simulation of micropipette aspiration, a nonlinear contact problem. In contrast to the halfspace model (Sato et al., 1990), this computational model accounts for nonlinearities in the cell response that result from a consideration of geometric factors including the finite cell dimension (radius R), curvature of the cell boundary, evolution of the cell-micropipette contact region, and curvature of the edges of the micropipette (inner radius a, edge curvature radius epsilon). Using 60 quadratic boundary elements, a micropipette aspiration creep test with ramp time t* = 0.1 s and ramp pressure p*/E = 0.8 is simulated for the cases a/R = 0.3, 0.4, 0.5 using mean parameter values for primary chondrocytes. Comparisons to the half-space model indicate that the computational model predicts an aspiration length that is less stiff during the initial ramp response (t = 0-1 s) but more stiff at equilibrium (t = 200 s). Overall, the ramp and equilibrium predictions of aspiration length by the computational model are fairly insensitive to aspect ratio a/R but can differ from the half-space model by up to 20 percent. This computational approach may be readily extended to account for more complex geometries or inhomogeneities in cellular properties. DA - 2000/6// PY - 2000/6// DO - 10.1115/1.429654 VL - 122 IS - 3 SP - 236-244 SN - 0148-0731 KW - cartilage KW - osteoarthritis KW - cell mechanics KW - chondrocyte KW - mechanotransduction ER - TY - JOUR TI - A discrete-ordinates solution for radiative-transfer models that include polarization effects AU - Siewert, CE T2 - JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER AB - A recently developed version of the discrete-ordinates method is used along with elementary numerical linear-algebra techniques to establish an accurate solution for all components in a Fourier representation of the Stokes vector basic to the scattering of polarized light. Computational aspects of the solution are discussed, and numerical results for each of the four Stokes parameters are given for a test case based on an atmosphere of randomly orientated oblate spheroids. DA - 2000/2// PY - 2000/2// DO - 10.1016/S0022-4073(99)00006-0 VL - 64 IS - 3 SP - 227-254 SN - 1879-1352 ER - TY - JOUR TI - A discrete-ordinates solution for multigroup transport theory with upscattering AU - Siewert, CE T2 - JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER AB - Abstract A recently developed version of the discrete-ordinates method is used along with elementary numerical linear-algebra techniques to establish an efficient and especially accurate solution to a class of multigroup transport problems for which upscattering is an important aspect of the model. The problems considered are defined for finite plane-parallel media, and anisotropic scattering from any group to any group is included in the formulation. Computational details of the solution are discussed, and accurate numerical results for two previously defined test problems are established. DA - 2000/2// PY - 2000/2// DO - 10.1016/S0022-4073(99)00098-9 VL - 64 IS - 3 SP - 255-273 SN - 0022-4073 ER - TY - JOUR TI - A concise and accurate solution to Chandrasekhar's basic problem in radiative transfer AU - Siewert, CE T2 - JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER AB - A recently developed version of the discrete-ordinates method is used along with elementary numerical linear-algebra techniques to establish an efficient and especially accurate solution to what can be called Chandrasekhar’s basic problem in radiative transfer, namely the problem of computing the radiation intensity in a finite plane-parallel layer illuminated by an incident beam of radiation and in which scattering can be described by a (rather) general scattering law. DA - 2000/1// PY - 2000/1// DO - 10.1016/s0022-4073(98)00144-7 VL - 64 IS - 2 SP - 109-130 SN - 0022-4073 ER - TY - CONF TI - Multi-model identification and the separability index AU - Nikoukhah, R. AU - Delebecque, F. AU - Campbell, S.L. AU - Horton, K. C2 - 2000/// C3 - Proceedings of Mathematical Theory of Networks and Systems, 2000 DA - 2000/// M1 - 2000 ER - TY - JOUR TI - Time in quantum geometrodynamics AU - Kheyfets, A. AU - Miller, W. A. T2 - International Journal of Modern Physics. A AB - We revisit the issue of time in quantum geometrodynamics and suggest a quantization procedure on the space of true dynamic variables. This procedure separates the issue of quantization from enforcing the constraints caused by the general covariance symmetries. The resulting theory, unlike the standard approach, takes into account the states that are off shell with respect to the constraints, and thus avoids the problems of time. In this approach, quantum geometrodynamics, general covariance, and the interpretation of time emerge together as parts of the solution of the total problem of geometrodynamic evolution. DA - 2000/// PY - 2000/// DO - 10.1142/s0217751x00001361 VL - 15 IS - 26 SP - 4125-4140 ER - TY - JOUR TI - The transport of neutral hydrogen atoms in a hydrogen plasma AU - Garcia, RDM AU - Siewert, CE T2 - NUCLEAR SCIENCE AND ENGINEERING AB - An analytical version of the discrete ordinates method is used to solve a class of boundary-value problems based on a linear Boltzmann equation relevant to the transport of neutral hydrogen atoms in a hydrogen plasma. In addition to a complete development of the discrete ordinates method for the considered application, the computational algorithm is implemented to yield very accurate results for a number of half-space and finite-slab problems. The developed code is also used to correct some entries in a previously reported tabulation of results. The established algorithm is considered especially easy to use, and the code runs (typically) in <1 s on a 400-MHz Pentium-based personal computer. DA - 2000/9// PY - 2000/9// DO - 10.13182/NSE00-A2150 VL - 136 IS - 1 SP - 140-149 SN - 0029-5639 ER - TY - JOUR TI - Subspace semigroups AU - Okninski, J AU - Putcha, MS T2 - JOURNAL OF ALGEBRA AB - For a finite dimensional algebra A over an infinite field K, the subspace semigroup S(A) consists of all subspaces of A with operation V ∗ W = linK(VW). We describe the structure of S(A), showing in particular that, similarly to any algebraic linear semigroup, S(A) is strongly π-regular; we describe its regular elements and regular T-classes. As the key intermediate step, for an arbitrary connected algebraic monoid M, we study the semigroup C(M) consisting of all irreducible closed subsets with operation X · Y = XY, and we transfer the information to S(A) via the natural onto homomorphism C(A) → S(A). With potential applications in mind, our primary focus in this paper is on the case of the full matrix algebra A = Mn(K). DA - 2000/11/1/ PY - 2000/11/1/ DO - 10.1006/jabr.2000.8417 VL - 233 IS - 1 SP - 87-104 SN - 0021-8693 ER - TY - JOUR TI - Optimized design of switching amplifiers for piezoelectric actuators AU - Chandrasekaran, S AU - Lindner, DK AU - Smith, RC T2 - JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES AB - The formulation and solution of an optimization problem for the design of a current controlled switching power amplifier to drive a piezoelectric actuator is the subject of this paper. The design is formulated as a continuous optimization problem. A detailed model that includes the anhysteretic nonlinearity between the electric field and polarization is developed and is coupled with a dynamic model of the amplifier. The design specifications are formulated as optimization constraints. The objective function is chosen to be the weight of the inductor. Optimization results are presented to demonstrate the efficiency of the proposed design methodology. DA - 2000/11// PY - 2000/11// DO - 10.1106/XFC7-PD82-LDFC-T2R9 VL - 11 IS - 11 SP - 887-901 SN - 1045-389X ER - TY - JOUR TI - On fourth-order elliptic boundary value problems AU - Pao, C. V. T2 - Proceedings of the American Mathematical Society DA - 2000/// PY - 2000/// VL - 128 IS - 4 SP - 1023-1030 ER - TY - JOUR TI - Generalized Rankine-Hugoniot condition and shock solutions for quasilinear hyperbolic systems AU - Lin, XB T2 - JOURNAL OF DIFFERENTIAL EQUATIONS AB - For a quasilinear hyperbolic system, we use the method of vanishing viscosity to construct shock solutions. The solution consists of two regular regions separated by a free boundary (shock). We use Melnikov's integral to obtain a system of differential/algebraic equations that governs the motion of the shock. For Lax shocks in conservation laws, these equations are equivalent to the Rankine–Hugoniot condition. For under compressive shocks in conservation laws, or shocks in non-conservation systems, the Melnikov-type integral obtained in this paper generalizes the Rankine–Hugoniot condition. Under some generic conditions, we show that the initial value problem of shock solutions can be solved as a free boundary problem by the method of characteristics. DA - 2000/12/10/ PY - 2000/12/10/ DO - 10.1006/jdeq.2000.3889 VL - 168 IS - 2 SP - 321-354 SN - 0022-0396 ER - TY - JOUR TI - Expressions and bounds for the GMRES residual AU - Ipsen, ICF T2 - BIT DA - 2000/// PY - 2000/// DO - 10.1023/A:1022371814205 VL - 40 IS - 3 SP - 524-535 SN - 0006-3835 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0013133887&partnerID=MN8TOARS KW - linear system KW - Krylov space methods KW - GMRES KW - MINRES KW - Vandermonde matrix KW - eigenvalues KW - departure from normality ER - TY - JOUR TI - BV-type regularization methods for convoluted objects with edge, flat and grey scales AU - Ito, K AU - Kunisch, K T2 - INVERSE PROBLEMS AB - A variational approach for the robust inversion of linear smoothing operators is discussed. We employ and generalize the enhancement techniques based on BV- and Perona-Malik-type regularization methods. The problem is cast as the minimization of a cost functional consisting of a data fitting and a restoration energy criterion for multiscale objects consisting of edge, flat and grey regions. An iterative algorithm for finding the restored object that minimizes the cost functional is developed and analysed. It is based upon a fixed-point iteration combining a time-marching and successive substitution method for finding a solution to a quasi-elliptic partial differential equation. Global convergence is proved. Numerical examples illustrate the proposed approach. DA - 2000/8// PY - 2000/8// DO - 10.1088/0266-5611/16/4/303 VL - 16 IS - 4 SP - 909-928 SN - 0266-5611 ER - TY - JOUR TI - The searchlight problem for radiative transfer in a finite slab AU - Barichello, LB AU - Siewert, CE T2 - JOURNAL OF COMPUTATIONAL PHYSICS AB - A version of the discrete-ordinates method recently developed for radiative-transfer calculations is used along with numerical linear-algebra techniques and two-dimensional Fourier-transform procedures to establish the radiation flux and the z component of the radiation current at all locations in a finite plane-parallel layer irradiated by a beam incident only at one point on one surface. In addition to a general formulation basic to a beam that is incident at an oblique angle, for which the flux and current depend on three spatial variables, the Fourier transforms of the flux and current are inverted numerically for the two-dimensional case relevant to a normally incident beam. The reported numerical procedures, while computationally intensive, are thought to yield, for the considered test case, the radiation flux and the normal component of the radiation current with five figures of accuracy. DA - 2000/1/20/ PY - 2000/1/20/ DO - 10.1006/jcph.1999.6396 VL - 157 IS - 2 SP - 707-726 SN - 0021-9991 ER - TY - JOUR TI - The jump behavior and stability analysis for 2-D descriptor systems AU - Zou, Y. AU - Campbell, S.L. T2 - Multidimensional Systems and Signal Processing DA - 2000/// PY - 2000/// DO - 10.1023/a:1008429611994 VL - 11 IS - 4 SP - 339–358 ER - TY - JOUR TI - Stability properties for a compactly supported prescale function AU - Dobric, V AU - Gundy, RF AU - Hitczenko, P T2 - SIAM JOURNAL ON MATHEMATICAL ANALYSIS AB - We show that if $\phi$ is a continuous, minimally supported prescale function, then its translates are linearly independent on any set of positive measure in the unit interval. This generalizes results of Y. Meyer and P. G. Lemari{é. This result implies that a stability condition, introduced by Gundy and Kazarian for the study of local convergence of spline wavelet expansions, is satisfied for all expansions arising from multiresolution analyses generated by such prescale functions $\phi$. DA - 2000/3/6/ PY - 2000/3/6/ DO - 10.1137/S003614109732746X VL - 31 IS - 3 SP - 574-580 SN - 0036-1410 KW - wavelets KW - linear independence KW - local convergence ER - TY - JOUR TI - Semigroups and weights for group representations AU - Putcha, MS T2 - PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY AB - Let $G$ be a finite group. Consider a pair $\chi =(\chi _+,\chi _-)$ of linear characters of subgroups $P,P^-$ of $G$ with $\chi _+$ and $\chi _-$ agreeing on $P\cap P^-$. Naturally associated with $\chi$ is a finite monoid $M_\chi$. Semigroup representation theory then yields a representation $\theta$ of $G$. If $\theta$ is irreducible, we say that $\chi$ is a weight for $\theta$. When the underlying field is the field of complex numbers, we obtain a formula for the character of $\theta$ in terms of $\chi _+$ and $\chi _-$. We go on to construct weights for some familiar group representations. DA - 2000/// PY - 2000/// DO - 10.1090/S0002-9939-00-05464-2 VL - 128 IS - 10 SP - 2835-2842 SN - 0002-9939 ER - TY - JOUR TI - Quenching problem of a reaction-diffusion equation with time delay AU - Pao, CV T2 - NONLINEAR ANALYSIS-THEORY METHODS & APPLICATIONS DA - 2000/7// PY - 2000/7// DO - 10.1016/S0362-546X(98)00269-7 VL - 41 IS - 1-2 SP - 133-142 SN - 0362-546X KW - quenching problem KW - reaction-diffusion equation KW - time delay KW - asymptotic behavior KW - positive solution ER - TY - JOUR TI - On singular equilibria of index-1 DAEs AU - Riaza, R AU - Campbell, SL AU - Marszalek, W T2 - CIRCUITS SYSTEMS AND SIGNAL PROCESSING DA - 2000/// PY - 2000/// DO - 10.1007/BF01212467 VL - 19 IS - 2 SP - 131-157 SN - 0278-081X KW - linearly implicit differential equations KW - semiexplicit differential-algebraic equations KW - singular equilibria KW - weak singularities KW - nonlinear electrical circuits KW - singular flow KW - singularity induced bifurcation ER - TY - JOUR TI - Newton's method for class of weakly singular optimal control problems AU - Ito, K AU - Kunisch, K T2 - SIAM JOURNAL ON OPTIMIZATION AB - Newton's method for optimal control of highly nonlinear partial differential equations is analyzed using a 2-norm technique. We consider the case where neither the linearization of the equality constraint e characterizing the differential equation is surjective nor a second order sufficient optimality condition holds for the topology on which e is well defined. Such problems occur, for instance, in optimal control of semilinear elliptic equations or for parameter estimation problems. Despite the above mentioned difficulties, sufficient conditions for second order convergence are obtained. DA - 2000/6/6/ PY - 2000/6/6/ DO - 10.1137/S1052623497320840 VL - 10 IS - 3 SP - 896-916 SN - 1052-6234 KW - Newton's method KW - optimal control KW - singular systems KW - 2-norm technique ER - TY - JOUR TI - Mesh independence of matrix-free methods for path following AU - Ferng, WR AU - Kelley, CT T2 - SIAM JOURNAL ON SCIENTIFIC COMPUTING AB - In this paper we consider a matrix-free path following algorithm for nonlinear parameter-dependent compact fixed point problems. We show that if these problems are discretized so that certain collective compactness and strong convergence properties hold, then this algorithm can follow smooth folds and capture simple bifurcations in a mesh-independent way. DA - 2000/5/21/ PY - 2000/5/21/ DO - 10.1137/S1064827598339360 VL - 21 IS - 5 SP - 1835-1850 SN - 1064-8275 KW - path following KW - bifurcation KW - collective compactness KW - fold point KW - mesh independence KW - matrix-free method KW - GMRES KW - Arnoldi method KW - singularity ER - TY - JOUR TI - ENSO signals in East African rainfall seasons AU - Indeje, M AU - Semazzi, FHM AU - Ogallo, LJ T2 - INTERNATIONAL JOURNAL OF CLIMATOLOGY AB - The evolutions of ENSO modes in the seasonal rainfall patterns over East Africa are examined in this study. The study covers the period 1961–1990. Both rotated empirical orthogonal function (EOF) and simple correlation analyses were used to delineate a network of 136 stations over East Africa into homogeneous rainfall regions in order to derive rainfall indices. Time series generated from the delineated regions were later used in the rainfall/ENSO analyses. Such analyses involved the development of composite rainfall map patterns for El Niño and post-ENSO (+1) years in order to investigate the associations between seasonal evolution of El Niño–Southern Oscillation (ENSO) signals and the space-time evolution of rainfall anomalies over the region. Analyses based on both EOF and simple correlation techniques yielded eight homogeneous rainfall regions over East Africa. The results showed unique seasonal evolution patterns in rainfall during the different phases of the ENSO cycles. East African rainfall performance characteristics were stratified to identify distinct rainfall anomaly patterns associated with ENSO and post-ENSO (+1) years. These can be applied in conjunction with skilful long lead (up to 12 months) ENSO prediction to provide guidance on likely patterns of seasonal rainfall anomalies over the region. Such information can be crucial for early warning of socio-economic disasters associated with extreme rainfall anomalies over East Africa. Copyright © 2000 Royal Meteorological Society DA - 2000/1// PY - 2000/1// DO - 10.1002/(SICI)1097-0088(200001)20:1<19::AID-JOC449>3.3.CO;2-S VL - 20 IS - 1 SP - 19-46 SN - 0899-8418 KW - Eastern Africa KW - empirical orthogonal function KW - ENSO KW - rainfall anomalies KW - seasonality ER - TY - JOUR TI - Creation and annihilation in matrix theory AU - Hartwig, RE AU - Prasad, KM T2 - LINEAR ALGEBRA AND ITS APPLICATIONS AB - A closed form representation is given for the matrix S that sweeps out a single column. This includes the integer as well as the unitary and regular cases. The closed form is built up from the 2×2 case. The product rule for adjoints is used to show that the dual of this procedure is precisely the completion procedure, which completes a single column to a matrix B such that SB=BS=diagonal. This construction underlines the fact that the completion and elimination processes are complementary. By permuting rows suitably, the matrices may be assumed to be in lower Hessenberg form. DA - 2000/1/15/ PY - 2000/1/15/ DO - 10.1016/s0024-3795(99)00197-4 VL - 305 IS - 1-3 SP - 47-65 SN - 0024-3795 KW - elimination KW - completion KW - adjoints KW - Brahma KW - Shiva ER - TY - JOUR TI - Challenges of symbolic computation: My favorite open problems AU - Kaltofen, E T2 - JOURNAL OF SYMBOLIC COMPUTATION AB - The success of the symbolic mathematical computation discipline is striking. The theoretical advances have been continuous and significant: Gröbner bases, the Risch integration algorithm, integer lattice basis reduction, hypergeometric summation algorithms, etc. From the beginning in the early 1960s, it has been the tradition of our discipline to create software that makes our ideas readily available to scientists, engineers, and educators: SAC-1, Reduce, Macsyma, etc. The commercial viability of our system products is proven by Maple and Mathematica. Today’s user communities of symbolic computation systems are diverse: educators, engineers, stock market analysts, etc. The mathematics and computer science in the design and implementation of our algorithms are sophisticated. The research challenges in symbolic computation at the close of the twentieth century are formidable. I state my favorite eight open problems in symbolic computation. They range from problems in symbolic/numeric computing, symbolic algorithm synthesis, to system component construction. I have worked on seven of my problems and borrowed one from George Collins. I present background to each of my problems and a clear-cut test that evaluates whether a proposed attack has solved one of my problems. An additional ninth open problem by Rob Corless and David Jeffrey on complex function semantics is given in an appendix. DA - 2000/6// PY - 2000/6// DO - 10.1006/jsco.2000.0370 VL - 29 IS - 6 SP - 891-919 SN - 1095-855X ER - TY - JOUR TI - Absolute and relative perturbation bounds for invariant subspaces of matrices AU - Ipsen, ICF T2 - LINEAR ALGEBRA AND ITS APPLICATIONS AB - Absolute and relative perturbation bounds are derived for angles between invariant subspaces of complex square matrices, in the two-norm and in the Frobenius norm. The absolute bounds can be considered extensions of Davis and Kahan's sinθ theorem to general matrices and invariant subspaces of any dimension. The relative bounds are the most general relative bounds for invariant subspaces because they place no restrictions on the matrix or the perturbation. When the perturbed subspace has dimension one, the relative bound is implied by the absolute bound. DA - 2000/4/15/ PY - 2000/4/15/ DO - 10.1016/S0024-3795(99)00104-4 VL - 309 IS - 1-3 SP - 45-56 SN - 1873-1856 KW - invariant subspace KW - absolute error KW - relative error KW - eigenvalue separation KW - angle between subspaces ER - TY - JOUR TI - A max-plus-based algorithm for a Hamilton-Jacobi-Bellman equation of nonlinear filtering AU - Fleming, WH AU - McEneaney, WM T2 - SIAM JOURNAL ON CONTROL AND OPTIMIZATION AB - The Hamilton--Jacobi--Bellman (HJB) equation associated with the {robust/\hinfty} filter (as well as the Mortensen filter) is considered. These filters employ a model where the disturbances have finite power. The HJB equation for the filter information state is a first-order equation with a term that is quadratic in the gradient. Yet the solution operator is linear in the max-plus algebra. This property is exploited by the development of a numerical algorithm where the effect of the solution operator on a set of basis functions is computed off-line. The precomputed solutions are stored as vectors of coefficients of the basis functions. These coefficients are then used directly in the real-time computations. DA - 2000/3/16/ PY - 2000/3/16/ DO - 10.1137/S0363012998332433 VL - 38 IS - 3 SP - 683-710 SN - 0363-0129 KW - nonlinear filtering KW - robust KW - H(infinity) KW - max-plus algebra KW - nonlinear HJB equations ER - TY - JOUR TI - Weak solutions for diffusion-convection equations AU - Fang, W AU - Ito, K T2 - APPLIED MATHEMATICS LETTERS AB - Weak solutions to diffusion-convection equations with less regular convective field and boundary data are shown to exist as limits of solutions to problems with mixed boundary conditions. DA - 2000/4// PY - 2000/4// DO - 10.1016/S0893-9659(99)00188-3 VL - 13 IS - 3 SP - 69-75 SN - 0893-9659 KW - diffusion-convection equations KW - L-infinity bounds of weak solutions ER -