检索结果-内蒙古大学图书馆

A divide-and-conquer method to improve performance in quantum transport calculations: conductance in rotated graphene nanoribbons side-contact junctions

引用

ELECTRONIC STRUCTURE 2022年第4期4卷 047001-047001页

作者： Rodriguez, Mauricio J. Ramirez, Carlos Univ Nacl Autonoma Mexico Fac Ciencias Dept Fis Apartado Postal 70-542 Ciudad De Mexico 04510 Mexico

We propose a divide-and-conquer algorithm to find recursively the scattering matrix of general tight-binding structures. The scattering matrix allows a direct calculation of transport properties in mesoscopic systems by using the Landauer formula. The method is exact, and by analyzing the performance of the algorithm in square, triangular and honeycomb lattices, we show a significant improvement in comparison to other state-of-the-art recursive and non-recursive methods. We utilize this algorithm to compute the conductance of a rotated graphene nanoribbon side-contact junction, revealing that for electrons with energies smaller than -2.7 eV the transmission function depends negligibly on the angle of the junction, whereas for electrons with energies greater than -2.7 eV, there exists a set of angles for the system that increase its conductance independently of the energy of the particles.

关键词： quantum transport Landauer conductance scattering matrix recursive methods divide-and-conquer algorithm side-contact graphene

来源：评论

学校读者我要写书评

暂无评论

A fast method for variable-order space-fractional diffusion equations

引用

NUMERICAL algorithmS 2020年第4期85卷 1519-1540页

作者： Jia, Jinhong Zheng, Xiangcheng Fu, Hongfei Dai, Pingfei Wang, Hong Shandong Normal Univ Sch Math & Stat Jinan 250358 Shandong Peoples R China Univ South Carolina Dept Math Columbia SC 29208 USA China Univ Petr Coll Sci Qingdao 266580 Peoples R China Zhejiang Univ Sch Math Sci Hangzhou 310027 Zhejiang Peoples R China

We develop a fast divide-and-conquer indirect collocation method for the homogeneous Dirichlet boundary value problem of variable-order space-fractional diffusion equations. Due to the impact of the space-dependent variable order, the resulting stiffness matrix of the numerical scheme does not have a Toeplitz structure. In this paper, we derive a fast approximation of the coefficient matrix by the means of a finite sum of Toeplitz matrices multiplied by diagonal matrices. We show that the approximation is asymptotically consistent with the original problem, which requires O(Nlog2N)\ memory and O(Nlog3N) computational complexity with N being the numbers of unknowns. Numerical experiments are presented to demonstrate the effectiveness and the efficiency of the proposed method.

关键词： Variable-order space-fractional diffusion equation Collocation method divide-and-conquer algorithm Toeplitz matrix

来源：评论

学校读者我要写书评

暂无评论

Adaptive Strategy and Decision Making Model for Sensing-Based Network Applications 19

Adaptive Strategy and Decision Making Model for Sensing-Base...

引用

19th International Symposium on Communications and Information Technologies (ISCIT)

作者： Ibrahim, Marwa Harb, Hassan Nasser, Abbass Mansour, Ali Osswald, Christophe ENSTA Bretagne CNRS UMR 6285 Lab STICC Brest France Amer Univ Culture & Educ AUCE Comp Sci Dept Beirut Lebanon

ISBN: (纸本)9781728150093

Energy conservation and decision making are at the heart of wireless sensor network (WSN) research. Indeed, the limited power of sensors, which is mostly not rechargeable, accompanied to the dense deployment of sensors, which collect a huge amount of data, complicate the makers' decision. In this paper, we propose an energy-efficient adaptive strategy and decision making technique based on a grid architecture of WSN, where a Grid-Leader (GL) is assigned for each grid. Our technique works on the three tiers of WSN: sensors, grid-leader (GL) and sink. At the first tier, each sensor applies a divide-and-conquer algorithm in order to send a reduced set of data to its appropriate GL;At the second tier, the GL combines data coming from sensors and sends useful information, i.e. satisfying a confidence threshold, about the monitored grid to the sink. The last tier, e.g. sink node, introduces two decision tables (score and early decisions) in order to make a real-time decision for each grid in the network. Extensive simulations on real sensor data demonstrated that our technique can be efficiently saving the network energy and helping in taking decisions, while maintaining an acceptable data accuracy level.

关键词： Wireless Sensor Networks (WSNs) Data Reduction Grid Topology divide-and-conquer algorithm Support-Confidence Method Decision Making Model

来源：评论

学校读者我要写书评

暂无评论

Optimization problem and efficient partitioning algorithm for transitions to finer-scale models in adaptive resolution simulation of articulated biopolymers

引用

MULTIBODY SYSTEM DYNAMICS 2018年第1期42卷 97-117页

作者： Poursina, Mohammad Anderson, Kurt S. Univ Arizona Dept Aerosp & Mech Engn Computat Dynam Complex Syst Lab Tucson AZ 85721 USA Rensselaer Polytech Inst Mech Aerosp & Nucl Engn Dept 110 8th St Troy NY 12180 USA

Adaptive coarse graining of highly complex biomolecular systems is conducted by either imposing constraints on the system model to generate a coarser model, or releasing certain constraints from it to create a higher fidelity one. This paper addresses some of the challenges of transitions to finer-scale models. It is shown that the kinetic energy associated with ignored modes of motion during the coarse graining process must be estimated and put back into the simulation. As such, unlike real mechanical systems, transitioning back to a finer biomolecular model may result in an infinite number of solutions. Herein, an optimization-based approach subject to the satisfaction of impulse-momentum balance and desired kinetic energy is presented to arrive at a physically meaningful state of the system immediately after the transition. In order to reduce the cost of formulating and solving this optimization problem, generalized velocities of the system are partitioned into two categories: independent joint velocities associated with the released joints, and dependent joint velocities associated with the rest of the joints. This paper further develops a divide-and-conquer algorithm to efficiently perform this partitioning process and express dependent velocities in terms of independent ones. The presented method is highly parallelizable and avoids the construction of the mass and Jacobian matrices of the entire system, resulting in a significant improvement in computational efficiency.

关键词： Adaptive coarse graining Model transition Molecular dynamics Optimization divide-and-conquer algorithm

来源：评论

学校读者我要写书评

暂无评论

Enhanced hybrid method of divide-and-conquer and RBF neural networks for function approximation of complex problems

引用

TURKISH JOURNAL OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCES 2017年第2期25卷 1095-1105页

作者： Awad, Mohammed Arab Amer Univ Fac Engn & Informat Technol Dept Comp Syst Engn Jenin Palestine

This paper provides an enhanced method focused on reducing the computational complexity of function approximation problems by dividing the input data vectors into small groups, which avoids the curse of dimensionality. The computational complexity and memory requirements of the approximated problem are higher when the input data dimensionality increases. A divide-and-conquer algorithm is used to distribute the input data of the complex problem to a divided radial basis function neural network (Div-RBFNN). Under this algorithm, the input data variables are typically distributed to different RBFNNs based on whether the number of the input data dimensions is odd or even. In this paper, each Div-RBFNN will be executed independently and the resulting outputs of all Div-RBFNNs will be grouped using a system of linear combination function. The parameters of each Div-RBFNN (centers, radii, and weights) will be optimized using an efficient learning algorithm, which depends on an enhanced clustering algorithm for function approximation, which clusters the centers of the RBFs. Compared to traditional RBFNNs, the proposed methodology reduces the number of executing parameters. It further outperforms traditional RBFNNs not only with respect to the execution time but also in terms of the number of executing parameters of the system, which produces better approximation error.

关键词： Approximation algorithms computational complexity divide-and-conquer algorithm RBF neural networks

来源：评论

学校读者我要写书评

暂无评论

New fast divide-and-conquer algorithms for the symmetric tridiagonal eigenvalue problem

引用

NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS 2016年第4期23卷 656-673页

作者： Li, Shengguo Liao, Xiangke Liu, Jie Jiang, Hao Natl Univ Def Technol Coll Comp Changsha 410073 Hunan Peoples R China Natl Univ Def Technol Sci & Technol Parallel & Distributed Proc Lab Changsha 410073 Hunan Peoples R China Natl Univ Def Technol State Key Lab High Performance Comp Changsha 410073 Hunan Peoples R China

In this paper, two accelerated divide-and-conquer (ADC) algorithms are proposed for the symmetric tridiagonal eigenvalue problem, which cost O(N(2)r) flops in the worst case, where N is the dimension of the matrix and r is a modest number depending on the distribution of eigenvalues. Both of these algorithms use hierarchically semiseparable (HSS) matrices to approximate some intermediate eigenvector matrices, which are Cauchy-like matrices and are off-diagonally low-rank. The difference of these two versions lies in using different HSS construction algorithms, one (denoted by ADC1) uses a structured low-rank approximation method and the other (ADC2) uses a randomized HSS construction algorithm. For the ADC2 algorithm, a method is proposed to estimate the off-diagonal rank. Numerous experiments have been carried out to show their stability and efficiency. These algorithms are implemented in parallel in a shared memory environment, and some parallel implementation details are included. Comparing the ADCs with highly optimized multi-threaded libraries such as Intel MKL, we find that ADCs could be more than six times faster for some large matrices with few deflations. Copyright (C) 2016 John Wiley & Sons, Ltd.

关键词： HSS matrices cauchy-like matrices eigenvalue problems Schur complements divide-and-conquer algorithm

来源：评论

学校读者我要写书评

暂无评论

A derivation and scalable implementation of the synchronous parallel kinetic Monte Carlo method for simulating long-time dynamics

引用

COMPUTER PHYSICS COMMUNICATIONS 2017年 219卷 246-254页

作者： Byun, Hye Suk El-Naggar, Mohamed Y. Kalia, Rajiv K. Nakano, Aiichiro Vashishta, Priya Univ Southern Calif Dept Phys & Astron Los Angeles CA 90089 USA Univ Southern Calif Dept Biol Sci Los Angeles CA 90089 USA Univ Southern Calif Dept Chem Los Angeles CA 90089 USA Univ Southern Calif Dept Comp Sci Los Angeles CA 90089 USA Univ Southern Calif Dept Chem Engn & Mat Sci Los Angeles CA 90089 USA Univ Southern Calif Collaboratory Adv Comp & Simulat Los Angeles CA 90089 USA

Kinetic Monte Carlo (KMC) simulations are used to study long-time dynamics of a wide variety of systems. Unfortunately, the conventional KMC algorithm is not scalable to larger systems, since its time scale is inversely proportional to the simulated system size. A promising approach to resolving this issue is the synchronous parallel KMC (SPKMC) algorithm, which makes the time scale size-independent. This paper introduces a formal derivation of the SPKMC algorithm based on local transition-state and time dependent Hartree approximations, as well as its scalable parallel implementation based on a dual linked list cell method. The resulting algorithm has achieved a weak-scaling parallel efficiency of 0.935 on 1024 Intel Xeon processors for simulating biological electron transfer dynamics in a 4.2 billion-heme system, as well as decent strong-scaling parallel efficiency. The parallel code has been used to simulate a lattice of cytochrome complexes on a bacterial-membrane nanowire, and it is broadly applicable to other problems such as computational synthesis of new materials. (C) 2017 Elsevier B.V. All rights reserved.

关键词： Kinetic Monte Carlo simulation divide-and-conquer algorithm Parallel computing

来源：评论

学校读者我要写书评

暂无评论

A divide-and-conquer algorithm FOR FINDING A MOST RELIABLE SOURCE ON A RING-EMBEDDED TREE NETWORK WITH UNRELIABLE EDGES

引用

DISCRETE MATHEMATICS algorithmS AND APPLICATIONS 2011年第4期3卷 503-516页

作者： Ding, Wei Xue, Guoliang Zhejiang Water Conservancy & Hydropower Coll Hangzhou 310018 Zhejiang Peoples R China Arizona State Univ Dept Comp Sci & Engn Tempe AZ 85287 USA

Given an unreliable communication network, we seek a most reliable source (MRS) of the network, which maximizes the expected number of nodes that are reachable from it. The problem of computing an MRS in general graphs is # P-hard. However, this problem in tree networks has been solved in a linear time. A tree network has a weakness of low capability of failure tolerance. Embedding rings into it by adding some additional certain edges to it can enhance its failure tolerance, resulting in another class of sparse networks, called the ring-tree networks. This class of network also has an underlying tree-like topology, leading to its advantage of being easily administrated. This paper concerns with an important case whose underlying topology is a strip graph, called lambda-rings network, and focuses on an unreliable lambda-rings network where each link has an independent operational probability while all nodes are immune to failures. We apply the divide-and-conquer approach to design a fast algorithm for computing an MRS, and employ a binary division tree (BDT) to analyze its time complexity to be O(parallel to lambda parallel to(2)(2) + [log vertical bar lambda vertical bar] center dot parallel to lambda parallel to).

关键词： Most reliable source ring-tree underlying topology divide-and-conquer algorithm

来源：评论

学校读者我要写书评

暂无评论

An adaptive lack of fit test for big data

引用

Statistical Theory and Related Fields 2017年第1期1卷 59-68页

作者： Yanyan Zhao Changliang Zou Zhaojun Wang Institute of Statistics and LPMC Nankai UniversityTianjinChina

New technological advancements combined with powerful computer hardware and high-speed network make big data *** massive sample size of big data introduces unique computational challenges on scalability and storage of statistical *** this paper,we focus on the lack of fit test of parametric regression models under the framework of big *** develop a computationally feasible testing approach via integrating the divide-and-conquer algorithm into a powerful nonparametric test *** theory results show that under mild conditions,the asymptotic null distribution of the proposed test is standard ***,the proposed test benefits fromthe use of data-driven bandwidth procedure and thus possesses certain adaptive *** studies show that the proposed method has satisfactory performances,and it is illustrated with an analysis of an airline data.

关键词： Adaptive test asymptotic distribution divide-and-conquer algorithm massive dataset model specification test

来源：评论

学校读者我要写书评

暂无评论

A divide-and-conquer algorithm for Computing a Most Reliable Source on an Unreliable Ring-Embedded Tree

A Divide-and-Conquer Algorithm for Computing a Most Reliable...

引用

4th Annual International Conference on Combinatorial Optimization and Applications (COCOA)

作者： Ding, Wei Xue, Guoliang Zhejiang Water Conservancy & Hydropower Coll Hangzhou Zhejiang Peoples R China Arizona State Univ Dept Comp Sci & Engn Tempe AZ 85287 USA

ISBN: (纸本)9783642174605

Given an unreliable communication network, we seek a most reliable source (MRS) of the network, which maximizes the expected number of nodes that are reachable from it. The problem of computing an MRS in general graphs is #P-hard. However, this problem in tree networks has been solved in a linear time. A tree network has a weakness of low capability of failure tolerance. Embedding rings into it by adding some additional certain edges to it can enhance its failure tolerance, resulting in another class of sparse networks, called the ring-tree networks. This class of network also has an underlying tree-like topology, leading to its advantage of being easily administrated. This paper concerns with an important case whose underlying topology is a strip graph, called lambda-rings network, and focuses on an unreliable lambda-rings network where each link has an independent operational probability while all nodes are immune to failures. We apply the divide-and-conquer approach to design a fast algorithm for computing its an MRS, and employ a binary division tree (BDT) to analyze its time complexity to be O(parallel to lambda parallel to(2)(2) + inverted right perpendicularlog vertical bar lambda vertical bar inverted left perpendicular . parallel to lambda parallel to(1))

关键词： Most reliable source ring-tree underlying topology divide-and-conquer algorithm

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

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

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：