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作者： Sigalov, Daniel Oshman, Yaakov Technion Israel Institute of Technology Program for Applied Mathematics Haifa 32000 Israel Technion Israel Institute of Technology Department of Aerospace Engineering Haifa 32000 Israel

ISBN: (纸本)9780982443811

We consider the problem of tracking the state of a hybrid system capable of performing a bounded number of mode switches. The system is assumed to follow either a nominal or an anomalous model, where the nominal model may stand for, e.g., the non-maneuvering motion regime of a target or the fault-free operation mode of a sensor, and the anomalous model may stand for, e.g., the abrupt evasive maneuvers of a target or the faulty operation of a sensor. As is well known, the optimal algorithm requires implementation of an exponentially growing number of primitive Kalman filters. On the other hand, the system's switching dynamics is not Markov because of the a priori bounded number of model switches, thus ruling out the use of popular estimation schemes such as the interacting multiple model (IMM) and generalized pseudo-Bayesian (GPB) filters. We derive an efficient scheme that uses a number of primitive Kalman filters that is linear in the number of possible maneuvers. The scheme resembles the IMM algorithm in that it uses interaction between some of the primitive filters before every estimation cycle, thus reducing the number of such filters. The algorithm's performance is evaluated via a simulation study, and shown to outperform the state-of-the-art IMM filter in a typical example.

关键词： Hybrid systems

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Opportunities for students and faculty stemming from engineering technology program reform

Opportunities for students and faculty stemming from enginee...

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2010 ASEE Annual Conference and Exposition

作者： Spang, David Genis, Vladimir Department of Science Mathematics and Technology Burlington County College United States Applied Engineering Technology Program School of Technology and Professional Studies Drexel University United States

Burlington County College (BCC) is implementing the findings of an institution-level reform of its engineering Technology programs in order to create meaningful job opportunities for displaced and incumbent workers, work-based activities and/or internships for students, and faculty development opportunities. In addition, the findings of this engineering Technology program reform effort will be tailored to develop initiatives to increase enrollment in the engineering Technology programs, with special attention to under-represented students. The goal of this synergistic approach is to promote and improve discussion, collaboration, and the working relationship among interested stakeholders vested in the central/southern NJ manufacturing-related industry. This project has brought together a robust consortium made up of secondary schools, a community college, a four-year university, workforce development professionals, and industry leaders. The approach of cooperative interaction is expected to serve as a model for transforming a community college technical education program in an effort to create a seamless and meaningful educational and work-entry pathway for future engineering technologists and technicians. This project is based upon work supported by the Advanced Technological Education (ATE) program at the National Science Foundation (NSF) under Grant No. 0703836. © American Society for engineering Education, 2010.

关键词： Students

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Why Gabor frames? Two fundamental measures of coherence and their role in model selection

Why Gabor frames? Two fundamental measures of coherence and ...

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作者： Bajwa, Waheed U. Calderbank, Robert Jafarpour, Sina Department of Electrical Engineering Program in Applied and Computational Mathematics Princeton University Princeton NJ 08544 United States Department of Computer Science Princeton University Princeton NJ 08544 United States

The problem of model selection arises in a number of contexts, such as subset selection in linear regression, estimation of structures in graphical models, and signal denoising. This paper studies non-asymptotic model selection for the general case of arbitrary (random or deterministic) design matrices and arbitrary nonzero entries of the signal. In this regard, it generalizes the notion of incoherence in the existing literature on model selection and introduces two fundamental measures of coherence- termed as the worst-case coherence and the average coherence-among the columns of a design matrix. It utilizes these two measures of coherence to provide an in-depth analysis of a simple, model-order agnostic one-step thresholding (OST) algorithm for model selection and proves that OST is feasible for exact as well as partial model selection as long as the design matrix obeys an easily verifiable property, which is termed as the coherence property. One of the key insights offered by the ensuing analysis in this regard is that OST can successfully carry out model selection even when methods based on convex optimization such as the lasso fail due to the rank deficiency of the submatrices of the design matrix. In addition, the paper establishes that if the design matrix has reasonably small worst-case and average coherence then OST performs near-optimally when either (i) the energy of any nonzero entry of the signal is close to the average signal energy per nonzero entry or (ii) the signal-to-noise ratio in the measurement system is not too high. Finally, two other key contributions of the paper are that (i) it provides bounds on the average coherence of Gaussian matrices and Gabor frames, and (ii) it extends the results on model selection using OST to low-complexity, model-order agnostic recovery of sparse signals with arbitrary nonzero entries. In particular, this part of the analysis in the paper implies that an Alltop Gabor frame together with OST can successfully carr

关键词： Recovery

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Hydrogen in tungsten: Absorption, diffusion, vacancy trapping, and decohesion

Hydrogen in tungsten: Absorption, diffusion, vacancy trappin...

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作者： Johnson, Donald F. Carter, Emily A. Department of Chemistry Princeton University Princeton NJ 08544 United States Department of Mechanical and Aerospace Engineering Program in Applied and Computational Mathematics Princeton University Princeton NJ 08544 United States

Understanding the interaction between atomic hydrogen and solid tungsten is important for the development of fusion reactors in which proposed tungsten walls would be bombarded with high energy particles including hydrogen isotopes. Here, we report results from periodic density-functional theory calculations for three crucial aspects of this interaction: surface-to-subsurface diffusion of H into W, trapping of H at vacancies, and H-enhanced decohesion, with a view to assess the likely extent of hydrogen isotope incorporation into tungsten reactor walls. We find energy barriers of (at least) 2.08 eV and 1.77 eV for H uptake (inward diffusion) into W(001) and W(110) surfaces, respectively, along with very small barriers for the reverse process (outward diffusion). Although H dissolution in defect-free bulk W is predicted to be endothermic, vacancies in bulk W are predicted to exothermically trap multiple H atoms. Furthermore, adsorbed hydrogen is predicted to greatly stabilize W surfaces such that decohesion (fracture) may result from high local H concentrations. © 2010 Materials Research Society.

关键词： Tungsten

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Investigating engineering students' mathematical modeling abilities in capstone design

Investigating engineering students' mathematical modeling ab...

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2010 ASEE Annual Conference and Exposition

作者： Cole, Jennifer Linsenmeier, Robert McKenna, Ann Glucksberg, Matthew Department of Chemical and Biological Engineering Robert R. McCormick School of Engineering and Applied Science Northwestern University United States Department of Biomedical Engineering Inderdepartmental Neuroscience Graduate Program Northwestern University United States Department of Mechanical Engineering School of Education and Social Policy Northwestern University United States Department of Biomedical Engineering Robert R. McCormick School of Engineering and Applied Science Northwestern University United States

engineering capstone design is a culminating experience that is intended to provide an opportunity for students to apply their previous engineering knowledge to develop solutions to open-ended problems. Capstone design problems are often analytically complex, and their solutions integrate several disciplinary fundamentals, as well as more general design process knowledge. Often, the expectation is that a thorough or rigorous solution to a capstone level problem would include some type of computational or mathematical analysis appropriate to that discipline. However, engineering students often struggle in recognizing when and how disciplinary knowledge (e.g. mathematical analysis inherent in many engineering fundamentals) applies to their particular design solutions. This paper describes the strategy for and initial results of a study exploring how students use mathematical reasoning when developing design solutions. Specifically, we want to understand where students struggle in the development and implementation of a mathematical model. We conducted our study in a biomedical capstone (senior) design course. We presented students with a scenario based on a design problem in using phototherapy to treat jaundice, and asked specific questions relating to mathematical modeling in the solution to this problem. We developed the scenario and corresponding assignments based on previous work that identified six steps for what mathematical modeling should include. We staged the activities over a four-week period such that students addressed two of these steps at each time interval, or assignment stage. This report analyzes results from the first two activities, which focused on identifying the real-world phenomenon and simplifying or idealizing it. We found that in an open-ended statement of the problem, no students proposed using a mathematical model to assist in designing the device. When we specifically asked for a mathematical model in a second activity, only five students

关键词： Students

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Unsteady Magnetohydrodynamic Heat Transfer in a Semi-Infinite Porous Medium with Thermal Radiation Flux: Analytical and Numerical Study

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Advances in Numerical Analysis 2011年第1期2011卷

作者： O. Anwar Bég J. Zueco S. K. Ghosh Alireza Heidari Aerospace Engineering Department of Engineering and Mathematics Sheaf Building Sheffield Hallam University Sheffield S1 1WB UKshu.ac.uk Thermal Engineering and Fluids Department Technical University of Cartagena Campus Muralla del Mar 30202 Cartagena Spainupct.es Magnetohydrodynamics Applied Mathematics Program Department of Mathematics Narajole Raj College P.O. Narajole Midnapore 721 211 WB India Institute for Advanced Studies Tehran 14456-63543 Iranias.edu

The unsteady, buoyancy-induced, hydromagnetic, thermal convection flow in a semi-infinite porous regime adjacent to an infinite hot vertical plate moving with constant velocity, is studied in the presence of significant thermal radiation. The momentum and energy conservation equations are normalized and then solved using both the Laplace transform technique and Network Numerical Simulation. Excellent agreement is obtained between both analytical and numerical methods. An increase in Hartmann number ( M 2 ) strongly decelerates the flow and for very high strength magnetic fields ( M 2 = 20), the flow is reversed after a short time interval. The classical velocity overshoot is also detected close to the plate surface for low to intermediate values of M 2 at both small and large times; however this overshoot vanishes for larger strengths of the transverse magnetic field ( M 2 = 10). An increase in radiation-conduction parameter ( K r ) significantly increases temperature throughout the porous regime at both small and larger times, adjacent to the plate, but decreases the shear stress magnitudes at the plate. Temperature gradient is reduced at the plate surface for all times, with a rise in radiation-conduction parameter ( K r ). Shear stress is reduced considerably with an increase in Darcian drag parameter ( K p ).

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High-dimensional data fusion via joint manifold learning

High-dimensional data fusion via joint manifold learning

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2010 AAAI Fall Symposium

作者： Davenport, Mark A. Hegde, Chinmay Duarte, Marco F. Baraniuk, Richard G. Department of Statistics Stanford University Stanford CA 94305 United States Department of Electrical and Computer Engineering Rice University Houston TX 77005 United States Program in Applied and Computational Mathematics Princeton University Princeton NJ 08544 United States

ISBN: (纸本)9781577354888

The emergence of low-cost sensing architectures for diverse modalities has made it possible to deploy sensor networks that acquire large amounts of very high-dimensional data. To cope with such a data deluge, manifold models are often developed that provide a powerful theoretical and algorithmic framework for capturing the intrinsic structure of data governed by a low-dimensional set of ***, these models do not typically take into account dependencies among multiple sensors. We thus propose a new joint manifold framework for data ensembles that exploits such dependencies. We show that joint manifold structure can lead to improved performance for manifold learning. Additionally, we leverage recent results concerning random projections of manifolds to formulate a universal, network-scalable dimensionality reduction scheme that efficiently fuses the data from all sensors. Copyright © 2010, Association for the Advancement of Artificial Intelligence. All rights reserved.

关键词： Sensor networks

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Nonlocal orbital-free kinetic energy density functional for semiconductors

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Physical Review B 2010年第4期81卷 045206-045206页

作者： Chen Huang Emily A. Carter Department of Mechanical and Aerospace Engineering and Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544-5263 USA

We propose a nonlocal kinetic energy density functional (KEDF) for semiconductors based on the expected asymptotic behavior of its susceptibility function. The KEDF’s kernel depends on both the electron density and the reduced density gradient, with an internal parameter formally related to the material’s static dielectric constant. We determine the accuracy of the KEDF within orbital-free density functional theory (DFT) by applying it to a variety of common semiconductors. With only two adjustable parameters, the KEDF reproduces quite well the exact noninteracting KEDF (i.e., Kohn-Sham DFT) predictions of bulk moduli, equilibrium volumes, and equilibrium energies. The two parameters in our KEDF are sensitive primarily to changes in the local crystal structure (such as atomic coordination number) and exhibit good transferability between different tetrahedrally-bonded phases. This local crystal structure dependence is rationalized by considering Thomas-Fermi dielectric screening theory.

关键词： .Phases orbital-free KEDF bulk moduli

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Modeling the progression of apoptosis in Chinese Hamster Ovary cells

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IFAC Proceedings Volumes 2010年第6期43卷 467-472页

作者： Mukesh Meshram Yi-Yun Wei Saeideh Naderi Brendan McConkey Brian Ingalls Hector Budman Jeno Scharer Department of Chemical Engineering Department of Biology Department of Applied Mathematics University of Waterloo Waterloo Ontario Canada N2L 3G1

Caspases play important roles in driving the progression of apoptosis. We developed a first principle-based population-balance model to predict the time-evolution of caspase activities in a cell culture process under different cell density conditions. As a model system, we employed a Chinese Hamster Ovary (CHO) cell line producing anti-RhD monoclonal antibody in batch culture. Caspase activity was detected by flow cytometric measurements of the initiators caspase-8, caspase-9 and the executioner caspase-3. Two models were compared. In the first model, apoptosis was assumed to be triggered by one of two independent pathways: extrinsic or intrinsic. In the second model, simultaneous activation of the two pathways was allowed. The model parameters were calibrated by fitting to training data via a nonlinear constrained optimization method. It was found that the second model outperforms the first model, providing better fit between model predictions and experimental measurements. In addition, we analyzed the origin of apoptosis-related cell-to-cell communication and found that cells with caspase-3 activity are most likely responsible for the initiation of the extrinsic pathway of apoptosis.

关键词： Apoptosis Modeling CHO Caspases Cell-to-cell communication

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An end-to-end simulator for the all-electric ship MVDC integrated power system

An end-to-end simulator for the all-electric ship MVDC integ...

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Grand Challenges in Modeling and Simulation Symposium, GCMS 2010, Part of the 2010 Summer Simulation Multiconference, SummerSim 2010

作者： Milošević Marden, M. Prempraneerach, P. Kirtley, J.L. Karniadakis, G. Chryssostomidis, C. Design Laboratory MIT Sea Grant College Program United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA United States Department of Mechanical Engineering Rajamangala University of Technology Thunyaburi Pathumthani Thailand Division of Applied Mathematics Brown University Providence RI United States

ISBN: (纸本)9781617387043

In this paper, a large scale Medium Voltage DC all-electric ship integrated power system is modeled from the prime mover (gas turbine) to the propulsion load. This system has a three-phase 21MW synchronous machine as a main generator and a three-phase 19MW induction motor as a main propulsion drive. The influence of propeller emergence on both electrical and mechanical components of the system is investigated.

关键词： Ship propulsion

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