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11th AIAA/ISSMO Multidisciplinary Analysis and Optimaztion Conference

作者： Marhadi, Kun Venkataraman, Satchi San Diego State University San Diego CA 92182-1308 United States Computational Science Program AIAA United States Department of Aerospace Engineering and Engineering Mechanics San Diego State University Mail Code 1308 5500 Campanile Drive San Diego CA 92182-1308 United States

ISBN: (纸本)1563478234

The progressive failure of redundant truss structures was investigated. Energy absorption of the truss under progressive failure is taken as a measure of its performance. The non-deterministic energy absorption when small random design variations were introduced was calculated. Measures for robustness and predictability are proposed. Designs with different performance, robustness and predictability identified using a deterministic optimization procedure are investigated and characteristics that contribute to better energy absorption, robustness and predictable progressive failure are identified. The presence of competing failures is shown to lead to competing failure sequences. Investigating the failure sequence events and the energy absorption of competing failure sequences in non-robust designs indicate that energy absorption is a function of the stiffness of the competing member that fails first. To improve the total energy dissipated, failure sequences must be tailored so that the stiffer members whose failures do not lead to the structure becoming mechanism fails before the less loaded and less stiff members that are needed to keep the structure intact fail. To improve predictability, competing failures must be eliminated by separating the safety factors of critical members at each failure event.

关键词： Trusses

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Circadian phase entrainment via nonlinear model predictive control

Circadian phase entrainment via nonlinear model predictive c...

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2006 AIChE Annual Meeting

作者： Bagheri, Neda Stelling, Jorg Doyle, III, Francis J. Department of Electrical and Computer Engineering University of California Santa Barbara Santa Barbara CA 93106-5080 United States Department of Chemical Engineering University of California Santa Barbara Santa Barbara CA 93106-5080 United States Biomolecular Science and Engineering Program University of California Santa Barbara Santa Barbara CA 93106-5080 United States Institute of Computational Science ETH Zurich 8092 Zurich Switzerland

No abstract available

ISBN: (纸本)081691012X

No abstract available

关键词： Biological oscillators Entrainment Model predictive control Phase resetting

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Instantaneous Radar Polarimetry with Multiple Dually-polarized Antennas

Instantaneous Radar Polarimetry with Multiple Dually-polariz...

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Asilomar Conference on Signals, Systems & Computers

作者： A. R. Calderbank S. D. Howard W. Moran A. Pezeshki M. Zoltowski Program Applied and Computational Mathematics Princeton University Princeton NJ USA Defence Science and Technology Organization Edinburgh Australia Electrical Engineering and Computer Science University of Melbourne Melbourne Australia Electrical and Computer Engineering Purdue University West Lafayette IN USA

Fully polarimetric radar systems are capable of simultaneously transmitting and receiving in two orthogonal polarizations. Instantaneous radar polarimetry exploits both polarization modes of a dually-polarized radar transmitter and receiver on a pulse by pulse basis, and can improve the radar detection performance and suppress range sidelobes . In this paper, we extend the use of instantaneous radar polarimetry for radar systems with multiple dually-polarized transmit and receive antennas. Alamouti signal processing is used to coordinate transmission of Golay pairs of phase codes waveforms across polarizations and multiple antennas. The integration of multi- antenna signal processing with instantaneous radar polarimetry can further improve the detection performance, at a computational cost comparable to single channel matched filtering.

关键词： Radar polarimetry Radar antennas Polarization Radar detection Radar signal processing Transmitters Receiving antennas Transmitting antennas computational efficiency Matched filters

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Guest editorial nonlinear optimization of communication systems

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IEEE Journal on Selected Areas in Communications 2006年第8期24卷 1421-1423页

作者： Chiang, Mung Low, Steven H. Luo, Zhi-Quan Shroff, Ness B. Yu, Wei Steenstrup, M. Princeton University Department of Electrical Engineering Program in Applied and Computational Mathematics Princeton NJ 08544 United States California Institute of Technology Department of Computer Science Pasadena CA 91125 United States University of Minnesota Department of Electrical and Computer Engineering Minneapolis MN 55455 United States Purdue University School of Electrical and Computer Engineering West Lafayette IN 47907 United States University of Toronto Edward S. Rogers Sr. Department of Electrical and Computer Engineering Toronto Ont. M4S 3G5 Canada

No abstract available

关键词： Communication systems Design optimization Communication system control Optimization methods Protocols Distributed algorithms Power system modeling Nonlinear control systems Lagrangian functions Surges

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Quadruped robot obstacle negotiation via reinforcement learning

Quadruped robot obstacle negotiation via reinforcement learn...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Honglak Lee Yirong Shen Chih-Han Yu G. Singh A.Y. Ng Stanford University Stanford CA US Department of Electrical Engineering University of Stanford Stanford CA USA Scientific Computing and Computational Mathematics Program University of Stanford Stanford CA USA Computer Science Department University of Stanford Stanford CA USA

Legged robots can, in principle, traverse a large variety of obstacles and terrains. In this paper, we describe a successful application of reinforcement learning to the problem of negotiating obstacles with a quadruped robot. Our algorithm is based on a two-level hierarchical decomposition of the task, in which the high-level controller selects the sequence of foot-placement positions, and the low-level controller generates the continuous motions to move each foot to the specified positions. The high-level controller uses an estimate of the value function to guide its search; this estimate is learned partially from supervised data. The low-level controller is obtained via policy search. We demonstrate that our robot can successfully climb over a variety of obstacles which were not seen at training time

关键词： Learning Robot kinematics Legged locomotion Foot Mobile robots Leg Motion control Robotics and automation Path planning Computer science

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Identifying interaction sites in "Recalcitrant" proteins: Predicted protein and RNA binding sites in REV proteins of HIV-1 and EIAV agree with experimental data

Identifying interaction sites in "Recalcitrant" proteins: Pr...

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11th Pacific Symposium on Biocomputing 2006, PSB 2006

作者： Terribllini, Michael Lee, Jae-Hyung Yan, Changhui Jernigan, Robert L. Carpenter, Susan Honavar, Vasant Dobbs, Drena Bioinformatics and Computational Biology Graduate Program LH. Baker Center for Bioinformatics and Biological Statistics Iowa State University Ames IA 50010 United States Department of Computer Science Iowa State University Ames IA 50010 United States Department of Biochemistry Biophysics and Molecular Biology Iowa State University Ames IA 50010 United States Department of Genetics Development and Cell Biology Iowa State University Ames IA 50010 United States Artificial Intelligence Research Laboratory Center for Computational Intelligence Learning and Discovery Iowa State University Ames IA 50010 United States Department of Veterinary Microbiology and Pathology Washington State University Pullman WA. 99164 United States

ISBN: (纸本)9812564632

Protein-protein and protein nucleic acid interactions are vitally important for a wide range of biological processes, including regulation or gene expression, protein synthesis, and replication and assembly of many viruses. We have developed machine learning approaches for predicting which amino acids of a protein participate in its interactions with other proteins and/or nucleic acids, using only the proiein sequence as input. In this paper, we describe an application of classifiers trained on datasets of well-characterized protein-protein and protein-RNA complexes for which experimental structures are available. We apply these classifiers to the problem of predicting protein and RNA binding sites in the sequence of a clinically important protein for which the structure is not known: the regulatory protein Rev, essential for the replication of HIV-I and other lentiviruses. We compare our predictions with published biochemical, genetic and partial structural information for HIV-1 and EIAV Rev and with our own published experimental mapping of RNA binding sites in EIAV Rev. The predicted and experimentally determined binding sites are in very good agreement. The ability to predict reliably the residues of a protein that directly contribute to specific binding events - without the requirement for structural information regarding either the protein or complexes in which it participates - can potentially generate new disease intervention strategies.

关键词： Binding sites

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Self-assembly of the simple cubic lattice with an isotropic potential

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Physical Review E 2006年第2期74卷 021404-021404页

作者： Mikael C. Rechtsman Frank H. Stillinger Salvatore Torquato Department of Physics Princeton University Princeton New Jersey 08544 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA Princeton Institute for the Science and Technology Materials Princeton University Princeton New Jersey 08544 USA Princeton Center for Theoretical Physics Princeton University Princeton New Jersey 08544 USA

Conventional wisdom presumes that low-coordinated crystal ground states require directional interactions. Using our recently introduced optimization procedure to achieve self-assembly of targeted structures [M. C. Rechtsman et al., Phys. Rev. Lett. 95, 228301 (2005); Phys. Rev. E 73, 011406 (2006)], we present an isotropic pair potential V(r) for a three-dimensional many-particle system whose classical ground state is the low-coordinated simple cubic lattice. This result is part of an ongoing pursuit by the authors to develop analytical and computational tools to solve statistical-mechanical inverse problems for the purpose of achieving targeted self-assembly. The purpose of these methods is to design interparticle interactions that cause self-assembly of technologically important target structures for applications in photonics, catalysis, separation, sensors, and electronics. We also show that standard approximate integral-equation theories of the liquid state that utilize pair correlation function information cannot be used in the reverse mode to predict the correct simple cubic potential. We report in passing optimized isotropic potentials that yield the body-centered-cubic and simple hexagonal lattices, which provide other examples of non-close-packed structures that can be assembled using isotropic pair interactions.

关键词： CRYSTALS CLUSTERS DENSE

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Collective coordinate control of density distributions

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Physical Review E 2006年第3期74卷 031104-031104页

作者： Obioma U. Uche Salvatore Torquato Frank H. Stillinger Department of Chemical Engineering Princeton University Princeton New Jersey 08544 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Princeton Institute for the Science and Technology of Materials Princeton University Princeton New Jersey 08544 USA Program in Applied & Computational Mathematics Princeton University Princeton New Jersey 08544 USA Princeton Center for Theoretical Physics Princeton University Princeton New Jersey 08544 USA

Real collective density variables C(k) [cf. Eq. (1.3)] in many-particle systems arise from nonlinear transformations of particle positions, and determine the structure factor S(k), where k denotes the wave vector. Our objective is to prescribe C(k) and then to find many-particle configurations that correspond to such a target C(k) using a numerical optimization technique. Numerical results reported here extend earlier one- and two-dimensional studies to include three dimensions. In addition, they demonstrate the capacity to control S(k) in the neighborhood of ∣k∣=0. The optimization method employed generates multiparticle configurations for which S(k)∝∣k∣α, ∣k∣⩽K, and α=1, 2, 4, 6, 8, and 10. The case α=1 is relevant for the Harrison-Zeldovich model of the early universe, for superfluid He4, and for jammed amorphous sphere packings. The analysis also provides specific examples of interaction potentials whose classical ground states are configurationally degenerate and disordered.

关键词： STATISTICAL MECHANICS REALIZABILITY SYSTEM

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Crystal-melt interfacial free energies in hcp metals: A molecular dynamics study of Mg

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Physical Review B 2006年第2期73卷 024116-024116页

作者： D. Y. Sun M. I. Mendelev C. A. Becker K. Kudin Tomorr Haxhimali M. Asta J. J. Hoyt A. Karma D. J. Srolovitz Department of Physics East China Normal University Shanghai-200062 China Materials and Engineering Physics Program Ames Laboratory Ames Iowa USA Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 USA Princeton Materials Institute Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544 USA Department of Physics Northeastern University Boston Massachusetts USA Department of Chemical Engineering and Materials Science Center for Computational Science and Engineering University of California Davis Davis California 95616 USA Sandia National Laboratories MS 1411 Albuquerque New Mexico 87185 USA

Crystal-melt interfacial free energies (γ) are computed for hcp Mg by employing equilibrium molecular-dynamics (MD) simulations and the capillary-fluctuation method (CFM). This work makes use of a newly developed embedded-atom-method (EAM) interatomic potential for Mg fit to crystal, liquid, and melting properties. We describe how the CFM, which has previously been applied to cubic systems only, can be generalized for studies of hcp metals by employing a parametrization for the orientation dependence of γ in terms of hexagonal harmonics. The method is applied in the calculation of the Turnbull coefficient (α) and crystalline anisotropies of γ. We obtain a value of α=0.48, with interfacial free energies for different high-symmetry orientations differing by approximately 1%. These results are compared to those obtained in previous MD-CFM studies for cubic EAM metals as well as experimental studies of solid-liquid interfaces in hcp alloys. In addition, the implications of our results for the prediction of dendrite growth directions in hcp metals are discussed.

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The inflammatory and normal transcriptome of mouse bladder detrusor and mucosa

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BMC Physiology 2006年第1期6卷 1-20页

作者： Saban, Marcia R. Hellmich, Helen L. Turner, Mary Nguyen, Ngoc-Bich Vadigepalli, Rajanikanth Dyer, David W. Hurst, Robert E. Centola, Michael Saban, Ricardo Department of Physiology University Oklahoma Health Sciences Center Oklahoma City OK United States Department of Anesthesiology University of Texas Medical Branch Galveston TX United States Oklahoma Medical Research Foundation (OMRF) Arthritis and Immunology Research Program Microarray Core Facility Oklahoma City OK United States Daniel Baugh Institute for Functional Genomics and Computational Biology Department of Pathology Anatomy and Cell Biology Thomas Jefferson University Philadelphia United States Department of Microbiology and Immunology Laboratory for Genomics and Bioinformatics Oklahoma University Health Sciences Center Oklahoma City OK United States Department of Urology University Oklahoma Health Sciences Center Oklahoma City OK United States Cellular and Structural Biology University of Texas Health Science Center at San Antonio San Antonio TX United States

Background: An organ such as the bladder consists of complex, interacting set of tissues and cells. Inflammation has been implicated in every major disease of the bladder, including cancer, interstitial cystitis, and infection. However, scanty is the information about individual detrusor and urothelium transcriptomes in response to inflammation. Here, we used suppression subtractive hybridizations (SSH) to determine bladder tissue- and disease-specific genes and transcriptional regulatory elements (TRE)s. Unique TREs and genes were assembled into putative networks. Results: It was found that the control bladder mucosa presented regulatory elements driving genes such as myosin light chain phosphatase and calponin I that influence the smooth muscle phenotype. In the control detrusor network the Pax-3 TRE was significantly over-represented. During development, the Pax-3 transcription factor (TF) maintains progenitor cells in an undifferentiated state whereas, during inflammation, Pax-3 was suppressed and genes involved in neuronal development (synapsin I) were up-regulated. Therefore, during inflammation, an increased maturation of neural progenitor cells in the muscle may underlie detrusor instability. NF-κB was specifically over-represented in the inflamed mucosa regulatory network. When the inflamed detrusor was compared to control, two major pathways were found, one encoding synapsin I, a neuron-specific phosphoprotein, and the other an important apoptotic protein, siva. In response to LPS-induced inflammation, the liver X receptor was over-represented in both mucosa and detrusor regulatory networks confirming a role for this nuclear receptor in LPS-induced gene expression. Conclusion: A new approach for understanding bladder muscle-urothelium interaction was developed by assembling SSH, real time PCR, and TRE analysis results into regulatory networks. Interestingly, some of the TREs and their downstream transcripts originally involved in organogenesis and oncogene

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