检索结果-内蒙古大学图书馆

Mediterranean Conference on Control and Automation

作者： Baras, John S. Applied Mathematics Statistics and Scientific Computation Program Institute for Systems Research University of Maryland College Park United States

ISBN: (纸本)9781457701252

Networked systems are ubiquitous. A taxonomy of networked systems includes infrastructure and communication networks, social and economic networks, biological networks and biological swarms, robotic swarms, and several other categories. Most networked systems include physical components and cyber components implemented in various ways. Thus many networked systems come from the domain of cyberphysical systems (CPS). Cooperative networked systems represent from a certain abstract point of view a distributed and (at least partially) asynchronous implementation of the well known cycle "sense-decide-actuate" of control systems. Yet the interaction of dynamics, sensing, control and decision making, with network structures has created the need for a new scientific basis for the modeling, analysis, design and performance evaluation of such networked systems. For example, efforts to develop a new "Network Science" have emerged. Similarly, efforts to develop new theories of computation that emphasize multiple agents interacting over networks, beyond the conventional concepts and principles of computation and computability, have been also undertaken very recently. In another direction, several efforts have been undertaken very recently to develop models for such systems that integrate continuous and event-triggered dynamics within a framework that permits validation and testing of correctness. Thus the consideration of cooperative networked systems have raised fundamental new questions and challenges. © 2011 IEEE.

关键词： Decision making

来源：评论

学校读者我要写书评

暂无评论

Spontaneous Rotational Inversion in Phycomyces

引用

Physical Review Letters 2011年第13期106卷 138103-138103页

作者： Alain Goriely Michael Tabor Program in Applied Mathematics University of Arizona Tucson Arizona 85721 USA

The filamentary fungus Phycomyces blakesleeanus undergoes a series of remarkable transitions during aerial growth. During what is known as the stage IV growth phase, the fungus extends while rotating in a counterclockwise manner when viewed from above (stage IVa) and then, while continuing to grow, spontaneously reverses to a clockwise rotation (stage IVb). This phase lasts for 24–48 h and is sometimes followed by yet another reversal (stage IVc) before the overall growth ends. Here, we propose a continuum mechanical model of this entire process using nonlinear, anisotropic, elasticity and show how helical anisotropy associated with the cell wall structure can induce spontaneous rotation and, under appropriate circumstances, the observed reversal of rotational handedness.

关键词： Antennas

来源：评论

学校读者我要写书评

暂无评论

Tracking maneuvering targets with a soft bound on the number of maneuvers

Tracking maneuvering targets with a soft bound on the number...

引用

51st Israel Annual Conference on Aerospace Sciences 2011

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

ISBN: (纸本)9781617824012

We revisit the problem of tracking the state of a hybrid system capable of performing a bounded number of mode switches. In a previous paper we have addressed a version of the problem where we have assumed the existence of a deterministic, known hard bound on the number of mode transitions. In addition, it was assumed that the system can possess only two modes, e.g., the maneuvering and non-maneuvering regimes of a tracked target. In the present paper we relax both assumptions: we assume a soft, stochastic bound on the number of mode transitions, and altogether remove the restriction on the number of modes of the system (thus, e.g., the target can have multiple different maneuvering modes, in addition to the non-maneuvering one). While admitting an unlimited number of mode transitions, the soft bound renders that number finite with probability 1. In addition, similarly to the case where the number of transition was deterministically hard-bounded, the existence of the bound renders the mode switching mechanism non-Markov. Thus, the two formulations address similar, though not identical, problems, that cannot be solved by direct application of algorithms devised for hybrid systems having Markov mode switching mechanisms. The novel solution approach adopted herein is based on transforming the non-Markovian mode switching mechanism to an equivalent Markovian one, at the price of augmenting the mode definition, and increasing the dimension of the state space involved. A standard interacting multiple model (IMM) filter is then applied to the transformed (Markovian) problem in a straightforward manner. The performance of the new method is demonstrated via a simulation study comprising three examples, in which the new method is compared with 1) the filter for hard-bounded mode transitions, and 2) a standard IMM filter directly applied to the original problem. The study shows that even when working outside its operating envelope (e.g., when the number of mode switches is har

关键词： Hybrid systems

来源：评论

学校读者我要写书评

暂无评论

A framework for relating neural activity to freely moving behavior

A framework for relating neural activity to freely moving be...

引用

Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

作者： Justin D. Foster Paul Nuyujukian Oren Freifeld Stephen I. Ryu Michael J. Black Krishna V. Shenoy Department of Electrical Engineering University of Stanford Stanford CA USA Bioengineering and Stanford Medical School University of Stanford Stanford CA USA Division of Applied Mathematics Brown University Providence RI USA Department of Neurosurgery Palo Alto Medical Foundation Palo Alto CA USA Department of Computer Science Brown University Providence RI USA Departments of Electrical Engineering Bioengineering and Neurobiology Neurosciences Program Neurosciences Program University of Stanford Stanford CA USA

Two research communities, motor systems neuroscience and motor prosthetics, examine the relationship between neural activity in the motor cortex and movement. The former community aims to understand how the brain controls and generates movement; the latter community focuses on how to decode neural activity as control signals for a prosthetic cursor or limb. Both have made progress toward understanding the relationship between neural activity in the motor cortex and behavior. However, these findings are tested using animal models in an environment that constrains behavior to simple, limited movements. These experiments show that, in constrained settings, simple reaching motions can be decoded from small populations of spiking neurons. It is unclear whether these findings hold for more complex, full-body behaviors in unconstrained settings. Here we present the results of freely-moving behavioral experiments from a monkey with simultaneous intracortical recording. We investigated neural firing rates while the monkey performed various tasks such as walking on a treadmill, reaching for food, and sitting idly. We show that even in such an unconstrained and varied context, neural firing rates are well tuned to behavior, supporting findings of basic neuroscience. Further, we demonstrate that the various behavioral tasks can be reliably classified with over 95% accuracy, illustrating the viability of decoding techniques despite significant variation and environmental distractions associated with unconstrained behavior. Such encouraging results hint at potential utility of the freely-moving experimental paradigm.

关键词： Legged locomotion Maximum likelihood decoding Kinematics Animals Educational institutions Cameras Neuroscience

来源：评论

学校读者我要写书评

暂无评论

Microstructural degeneracy associated with a two-point correlation function and its information content

引用

Physical Review E 2012年第5期85卷 051140-051140页

作者： C. J. Gommes Y. Jiao S. Torquato Department of Chemical Engineering University of Liège Liège 4000 Belgium Department of Chemistry Princeton University Princeton New Jersey 08544 USA Department of Physics Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA Princeton Center for Theoretical Science Princeton University Princeton New Jersey 08544 USA Princeton Institute for the Science and Technology of Materials Princeton University Princeton New Jersey 08544 USA

A two-point correlation function provides a crucial yet an incomplete characterization of a microstructure because distinctly different microstructures may have the same correlation function. In an earlier Letter [Gommes, Jiao, and Torquato, Phys. Rev. Lett. 108, 080601 (2012)], we addressed the microstructural degeneracy question: What is the number of microstructures compatible with a specified correlation function? We computed this degeneracy, i.e., configurational entropy, in the framework of reconstruction methods, which enabled us to map the problem to the determination of ground-state degeneracies. Here, we provide a more comprehensive presentation of the methodology and analyses, as well as additional results. Since the configuration space of a reconstruction problem is a hypercube on which a Hamming distance is defined, we can calculate analytically the energy profile of any reconstruction problem, corresponding to the average energy of all microstructures at a given Hamming distance from a ground state. The steepness of the energy profile is a measure of the roughness of the energy landscape associated with the reconstruction problem, which can be used as a proxy for the ground-state degeneracy. The relationship between this roughness metric and the ground-state degeneracy is calibrated using a Monte Carlo algorithm for determining the ground-state degeneracy of a variety of microstructures, including realizations of hard disks and Poisson point processes at various densities as well as those with known degeneracies (e.g., single disks of various sizes and a particular crystalline microstructure). We show that our results can be expressed in terms of the information content of the two-point correlation functions. From this perspective, the a priori condition for a reconstruction to be accurate is that the information content, expressed in bits, should be comparable to the number of pixels in the unknown microstructure. We provide a formula to calculate the

关键词： MICROSTRUCTURE CORRELATION (Statistics) INFORMATION theory ENTROPY (Information theory) GROUND state (Quantum mechanics) MONTE Carlo method POISSON processes

来源：评论

学校读者我要写书评

暂无评论

Optimal Filling of Shapes

引用

Physical Review Letters 2012年第19期108卷 198304-198304页

作者： Carolyn L. Phillips Joshua A. Anderson Greg Huber Sharon C. Glotzer Applied Physics Program University of Michigan Ann Arbor Michigan 48109 USA Department of Chemical Engineering University of Michigan Ann Arbor Michigan 48109 USA Center for Cell Analysis and Modeling University of Connecticut Health Center Farmington Connecticut 06032 USA Department of Cell Biology University of Connecticut Health Center Farmington Connecticut 06032 USA Department of Mathematics University of Connecticut Storrs Connecticut 06032 USA Department of Materials Science and Engineering University of Michigan Ann Arbor Michigan 48109 USA

We present filling as a type of spatial subdivision problem similar to covering and packing. Filling addresses the optimal placement of overlapping objects lying entirely inside an arbitrary shape so as to cover the most interior volume. In n-dimensional space, if the objects are polydisperse n-balls, we show that solutions correspond to sets of maximal n-balls. For polygons, we provide a heuristic for finding solutions of maximal disks. We consider the properties of ideal distributions of N disks as N→∞. We note an analogy with energy landscapes.

关键词： SHAPES FORCE & energy COMBINATORIAL packing & covering ANALOGY HEURISTIC THEORY of distributions (Functional analysis)

来源：评论

学校读者我要写书评

暂无评论

Impact of generalized benefit functions on the evolution of cooperation in spatial public goods games with continuous strategies

引用

Physical Review E 2012年第6期85卷 066133-066133页

作者： Xiaojie Chen Attila Szolnoki Matjaž Perc Long Wang Evolution and Ecology Program International Institute for Applied Systems Analysis (IIASA) Schlossplatz 1 A-2361 Laxenburg Austria Institute of Technical Physics and Materials Science Research Centre for Natural Sciences Hungarian Academy of Sciences P. O. Box 49 H-1525 Budapest Hungary Faculty of Natural Sciences and Mathematics University of Maribor Koroška cesta 160 SI-2000 Maribor Slovenia State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University Beijing China

Cooperation and defection may be considered to be two extreme responses to a social dilemma. Yet the reality is much less clear-cut. Between the two extremes lies an interval of ambivalent choices, which may be captured theoretically by means of continuous strategies defining the extent of the contributions of each individual player to the common pool. If strategies are chosen from the unit interval, where 0 corresponds to pure defection and 1 corresponds to the maximal contribution, the question is what is the characteristic level of individual investments to the common pool that emerges if the evolution is guided by different benefit functions. Here we consider the steepness and the threshold as two parameters defining an array of generalized benefit functions, and we show that in a structured population there exist intermediate values of both at which the collective contributions are maximal. However, as the cost-to-benefit ratio of cooperation increases, the characteristic threshold decreases while the corresponding steepness increases. Our observations remain valid if more complex sigmoid functions are used, thus reenforcing the importance of carefully adjusted benefits for high levels of public cooperation.

关键词： GENERALIZATION PUBLIC goods GAME theory CONTINUOUS functions DILEMMA PARAMETER estimation SOCIAL reality STRATEGIC planning

来源：评论

学校读者我要写书评

暂无评论

Manifold learning techniques and model reduction for dissipative dynamics

Manifold learning techniques and model reduction for dissipa...

引用

Computing and Systems Technology Division - Core programming Topic at the 2011 AIChE Annual Meeting

作者： Sonday, Benjamin Rajendran, Karthikeyan Gear, William Singer, Amit Kevrekidis, Ioannis G. Program in Applied and Computational Mathematics Princeton University PrincetonNJ United States Chemical and Biological Engineering Princeton University PrincetonNJ United States Mathematics and PACM Princeton University PrincetonNJ United States

来源：评论

学校读者我要写书评

暂无评论

Hardware realization of chaos based block cipher for image encryption

Hardware realization of chaos based block cipher for image e...

引用

2011 23rd International Conference on Microelectronics, ICM 2011

作者： Barakat, Mohamed L. Radwan, Ahmed G. Salama, Khaled N. Electrical Engineering Program King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia Electrical Engineering Program Applied Engineering Mathematics Cairo University Egypt

ISBN: (纸本)9781457722073

Unlike stream ciphers, block ciphers are very essential for parallel processing applications. In this paper, the first hardware realization of chaotic-based block cipher is proposed for image encryption applications. The proposed system is tested for known cryptanalysis attacks and for different block sizes. When implemented on Virtex-IV, system performance showed high throughput and utilized small area. Passing successfully in all tests, our system proved to be secure with all block sizes. © 2011 IEEE.

关键词： Image processing

来源：评论

学校读者我要写书评

暂无评论

The Origin and Implications of (111)-Textured Grains Obtained via Nucleation and Growth of Solids in Pulsed-Laser-Quenched Al Films on SiO 2

引用

MRS Online Proceedings Library 2011年第1期979卷 1-6页

作者： J. B. Choi Min H. Choi U. J. Chung A. B. Limanov James S. Im Program in Materials Science Applied Physics and Applied Mathematics Columbia University New York USA

We have investigated excimer laser irradiation of 2000-Å-thin as-deposited Al films on SiO2. Microstructural analysis of the irradiated films conducted with AFM and EBSD techniques reveals that there exists a wide energy density interval over which large equaxed grains with a strong (111) texture are obtained. Based on thermal, transformational, and microstructural considerations, we propose a heterogeneous nucleation model to account for the observed behaviors, and discuss the implication of the model on the phenomenon of heterogeneous nucleation of crystalline solids in condensed systems as regards the thermodynamic role played by the orientation of subcritical clusters.

关键词： Al laser annealing texture

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：