检索结果-内蒙古大学图书馆

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

来源：评论

学校读者我要写书评

暂无评论

General Nonlinear Equilibrium Equation Solution of the Straight Wire Strand

引用

AIP Conference Proceedings 2007年第1期936卷 174-177页

作者： C. Erdönmez C. E. İmrak aIstanbul Technical University Institute of Informatics Computational Science and Engineering Program 34469 Maslak Istanbul Turkey bIstanbul Technical University Faculty of Mechanical Engineering 34394 Gumussuyu Istanbul Turkey

The most analyses of wire ropes are based on the well known classical treatise on elasticity by Love in 1944. A general theory of thin rods are included and investigated extensively. General equilibrium equations of a thin rod on arc length are derived and presented. The analytical and numerical solutions of wire ropes are based on the equilibrium equations as the starting point for the solutions in most of the papers. Helical rod model is first introduced by Phillips and Costello based on the equilibrium equations given by Love. General nonlinear equilibrium equation solution of the straight wire strand is given in this study and showed that it is harmonious with the results presented by Costello.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Unsteady aerodynamic effects of wing-body interactions in three-dimensional insects' flapping flight 50

Unsteady aerodynamic effects of wing-body interactions in th...

引用

50th AIAA Aerospace sciences Meeting Including the New Horizons Forum and Aerospace Exposition

作者： Lee, Kuen-Bae Kim, Jin-Ho Park, Jin Seok Kim, Chongam Interdisciplinary Program in Computational Science and Technology Seoul National Univ. Seoul 151-742 Korea Republic of Department of Aerospace Engineering Seoul National Univ. Seoul 151-742 Korea Republic of School of Mechanical and Aerospace Engineering Institute of Advanced Aerospace Technology Seoul National University Korea Republic of

ISBN: (数字)9781600869365

This paper investigates the unsteady aerodynamic features of wing-wing, wing-body and vortex-vortex interactions in insects' flapping motions under forward flight condition. A realistic wing trajectory, called the 'figure-of-eight' motion, is extracted from a blowfly (Phormia regina)'s tethered flight experiment under the freestream velocity of 2.75m/s. Since the flow field around the blowfly exhibits characteristics of low-Reynolds number flow, the three-dimensional unsteady incompressible Navier-Stokes equations are employed as the governing equations. In order to simulate the realistic insect flapping flight including geometric and kinematical complexity with a sufficient level of grid quality, overset grid technique is used. From the authors' previous researches on two- and three-dimensional rigid wing simulation, it has been observed that the pattern of vortical flows and the interaction of vortices play an important role in generating unsteady aerodynamic forces and determining the propulsive efficiency of flapping motion. Detailed numerical simulations of a blowfly's 'wing-body' motion are conducted to examine unsteady flow features resulted from the wing-body interaction. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： Navier Stokes equations

来源：评论

学校读者我要写书评

暂无评论

Incomplete inverse preconditioners

引用

ARI Bulletin of the Istanbul Technical University 2005年第3期54卷 48-64页

作者： Alvarado, Fernando Dag, Hasan Department of Electrical and Computer Engineering University of Wisconsin Madison 53706 United States Computational Science and Engineering Program Informatics Institute Istanbul Technical University 34469 Maslak Istanbul Turkey

Incomplete LU factorization is a valuable preconditioning approach for sparse iterative solvers. An "ideal" but inefficient preconditioner for the iterative solution of Ax = b is A-1 itself. This paper describes a preconditioner based on sparse approximations to partitioned representations of A-1, in addition to the results of implementation of the proposed method in a shared memory parallel environment. The partitioned inverses are normally somewhat sparse. Their sparsity can be enhanced with suitable ordering and partitioning algorithms. Sparse approximations to these partitioned inverse representations can be obtained either by discarding selected nonzero entries of these inverses or by precluding the creation of some inversion fills. Experimental results indicate that the use of these partitioned incomplete inverses as preconditioners results in excellent highly parallel preconditioners.

关键词： Conjugate gradient Iterative methods Parallel computation Partitioned inverse method Preconditioner

来源：评论

学校读者我要写书评

暂无评论

Approaching maximum resolution in structured illumination microscopy via accurate noise modeling

Npj imaging

引用

Npj imaging 2025年第1期3卷 5页

作者： Ayush Saurabh Peter T Brown J Shepard Bryan Iv Zachary R Fox Rory Kruithoff Cristopher Thompson Comert Kural Douglas P Shepherd Steve Pressé Center for Biological Physics Arizona State University Tempe AZ USA. Department of Physics Arizona State University Tempe AZ USA. Computational Science and Engineering Division Oak Ridge National Laboratory Oak Ridge TN USA. Department of Physics The Ohio State University Columbus OH USA. Interdisciplinary Biophysics Graduate Program The Ohio State University Columbus OH USA. School of Molecular Sciences Arizona State University Tempe AZ USA.

Biological images captured by microscopes are characterized by heterogeneous signal-to-noise ratios (SNRs) due to spatially varying photon emission across the field of view convoluted with camera noise. State-of-the-art unsupervised structured illumination microscopy (SIM) reconstruction methods, commonly implemented in the Fourier domain, often do not accurately model this noise. Such methods therefore suffer from high-frequency artifacts, user-dependent choices of smoothness constraints making assumptions on biological features, and unphysical negative values in the recovered fluorescence intensity map. On the other hand, supervised algorithms rely on large datasets for training, and often require retraining for new sample structures. Consequently, achieving high contrast near the maximum theoretical resolution in an unsupervised, physically principled manner remains an open problem. Here, we propose Bayesian-SIM (B-SIM), a Bayesian framework to quantitatively reconstruct SIM data, rectifying these shortcomings by accurately incorporating known noise sources in the spatial domain. To accelerate the reconstruction process, we use the finite extent of the point-spread-function to devise a parallelized Monte Carlo strategy involving chunking and restitching of the inferred fluorescence intensity. We benchmark our framework on both simulated and experimental images, and demonstrate improved contrast permitting feature recovery at up to 25% shorter length scales over state-of-the-art methods at both high- and low SNR. B-SIM enables unsupervised, quantitative, physically accurate reconstruction without the need for labeled training data, democratizing high-quality SIM reconstruction and expands the capabilities of live-cell SIM to lower SNR, potentially revealing biological features in previously inaccessible regimes.

关键词： Biophysics Image processing Imaging and sensing Super-resolution microscopy

来源：评论

学校读者我要写书评

暂无评论

Proposed framework for applying adaptive critics in real-time realm

Proposed framework for applying adaptive critics in real-tim...

引用

International Joint Conference on Neural Networks (IJCNN)

作者： G.G. Lendaris R.A. Santiago M.S. Carroll Systems Science and of Electrical & Computer Engineering Northwest Computational Intelligence Laboratory Portland State University Portland OR USA Systems Science Program Northwest Computational Intelligence Laboratory Portland State University Portland OR USA

Adaptive critics have shown much promise for designing optimal nonlinear controllers in an off-line context. Still, their greatest potential exists in the context Of reconfigurable control, that is, real time controller redesign in response to (substantial) changes in plant dynamics. To accomplish this, a framework is proposed for the application of adaptive critics in real-time control (for those critic methods requiring a model of the plant). The framework is presented in the context of work being done in reconfigurable flight control by the NW computational Intelligence Lab (NWCIL) at Portland State University. The proposal incorporates recent work (by others) in fast and efficient on-line plant identification, considerations for bounding the computational costs of converging neural networks, and a novel approach (by us) toward the task of assuring system stability during the adaptation process. The potential and limitations of the proposed framework are discussed. It is suggested that with the recent rapid reduction in computational barriers, only certain theoretical issues remain as the central barriers to successful on-line application of the methods.

关键词： programmable control Adaptive control Optimal control Neural networks computational intelligence Control systems Stability State-space methods Design methodology Piecewise linear approximation

来源：评论

学校读者我要写书评

暂无评论

Facial expression recognition in the wild using improved dense trajectories and Fisher vector encoding

Facial expression recognition in the wild using improved den...

引用

IEEE Conference on Computer Vision and Pattern Recognition Workshops

作者： Sadaf Afshar Albert Ali Salah Computational Science and Engineering Program Boğaziçi University Istanbul Turkey Department of Computer Engineering Boğaziçi University Istanbul Turkey

Improved dense trajectory features have been successfully used in video-based action recognition problems, but their application to face processing is more challenging. In this paper, we propose a novel system that deals with the problem of emotion recognition in real-world videos, using improved dense trajectory, LGBP-TOP, and geometric features. In the proposed system, we detect the face and facial landmarks from each frame of a video using a combination of two recent approaches, and register faces by means of Procrustes analysis. The improved dense trajectory and geometric features are encoded using Fisher vectors and classification is achieved by extreme learning machines. We evaluate our method on the extended Cohn-Kanade (CK+) and EmotiW2015 Challenge databases. We obtain state-of-the-art results in both databases.

关键词： Videos Trajectory Feature extraction Mouth Face recognition Support vector machines Cameras

来源：评论

学校读者我要写书评

暂无评论

Quasicontinuum-like reduction of density functional theory calculations of nanostructures

Quasicontinuum-like reduction of density functional theory c...

引用

作者： Negrut, Dan Anitescu, Mihai El-Azab, Anter Zapol, Peter Materials Science Program Department of Mechanical Engineering University of Wisconsin Madison WI 53706 United States Mathematics and Computer Science Division Argonne National Laboratory Argonne IL 60439 United States School of Computational Science Florida State University Tallahassee FL 32306 United States Materials Science and Chemistry Divisions Argonne National Laboratory Argonne IL 60439 United States

Density functional theory can accurately predict chemical and mechanical properties of nanostructures, although at a high computational cost. A quasicontinuum-like framework is proposed to substantially increase the size of the nanostructures accessible to simulation. It takes advantage of the near periodicity of the atomic positions in some regions of nanocrystalline materials to establish an interpolation scheme for the electronic density in the system. The electronic problem embeds interpolation and coupled cross-domain optimization techniques through a process called electronic reconstruction. For the optimization of nuclei positions, computational gains result from explicit consideration of a reduced number of representative nuclei and interpolating the positions of the rest of nuclei following the quasicontinuum paradigm. Numerical tests using the Thomas-Fermi-Dirac functional demonstrate the validity of the proposed framework within the orbital-free density functional theory. Copyright © 2008 American Scientific Publishers All rights reserved.

关键词： Electronic structure

来源：评论

学校读者我要写书评

暂无评论

Diffusion maps - A probabilistic interpretation for spectral embedding and clustering algorithms

Diffusion maps - A probabilistic interpretation for spectral...

引用

作者： Nadler, Boaz Lafon, Stephane Coifman, Ronald Kevrekidis, Ioannis G. Department of Computer Science and Applied Mathematics Weizmann Institute of Science Rehovot 76100 Israel Google Inc. United States Department of Mathematics Yale University New Haven CT 06520-8283 United States Department of Chemical Engineering Program in Applied and Computational Mathematics Princeton University Princeton NJ 08544 United States

ISBN: (纸本)9783540737490

Spectral embedding and spectral clustering are common methods for non-linear dimensionality reduction and clustering of complex high dimensional datasets. In this paper we provide a diffusion based probabilistic analysis of algorithms that use the normalized graph Laplacian. Given the pairwise adjacency matrix of all points in a dataset, we define a random walk on the graph of points and a diffusion distance between any two points. We show that the diffusion distance is equal to the Euclidean distance in the embedded space with all eigenvectors of the normalized graph Laplacian. This identity shows that characteristic relaxation times and processes of the random walk on the graph are the key concept that governs the properties of these spectral clustering and spectral embedding algorithms. Specifically, for spectral clustering to succeed, a necessary condition is that the mean exit times from each cluster need to be significantly larger than the largest (slowest) of all relaxation times inside all of the individual clusters. For complex, multiscale data, this condition may not hold and multiscale methods need to be developed to handle such situations.

关键词： Relaxation time

来源：评论

学校读者我要写书评

暂无评论

Coarse Grained Molecular Dynamics Simulation of Interaction between Hemagglutinin Fusion Peptides and Lipid Bilayer Membranes

引用

Advances in Applied Mathematics and Mechanics 2010年第4期2卷 430-450页

作者： Naveen K.Vaidya Huaxiong Huang Shu Takagi Theoretical Biology and Biophysics Group MS K710Los Alamos National LaboratoryLos AlamosNM 87545 USA Department of Mathematics and Statistics York UniversityTorontoM3J 1P3 Canada Organ and Body Scale Team Computational Science Research ProgramRiken Department of Mechanical Engineering The University of TokyoTokyoJapan

Microscopic level interaction between fusion-peptides and lipid bilayer membranes plays a crucial role in membrane fusion,a key step of viral *** this paper,we use coarse-grained molecular dynamics(CGMD)simulations to study the interaction between hemagglutinin fusion-peptides and phospholipid bilayer *** CGMD,we are able to simulate the interaction of fusion peptides with a relatively large piece of membrane for a sufficiently long time period,which is necessary for a detailed understanding of the fusion process.A conformation of the peptide with a kink at the level of phosphate group is obtained,consistent with NMR and EPR *** results show that the N-terminal segment of the peptide inserts more deeply into the membrane bilayer compared to the C-terminal segment,as observed in previous *** simulations also show that the presence of fusion peptides inside the membrane may cause bilayer thinning and lipid molecule ***,our results reveal that peptides tend to aggregate,indicating cluster formation as seen in many experiments.

关键词： Coarse-grained molecular dynamics fusion peptide hemagglutinin protein phospholipid bilayer membrane fusion

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：