检索结果-内蒙古大学图书馆

Receive maximal-ratio combining with outdated arbitrary transmit antenna selection in Nakagami-m fading

IET COMMUNICATIONS 2009年第10期3卷 1638-1648页

作者： Radaydeh, R. M. Jordan Univ Sci & Technol Dept Elect Engn Irbid 22110 Jordan

The use of transmit antenna selection algorithms in multiple-antenna systems enables significant reduction in implementation cost and complexity while maintaining acceptable performance. An attractive and quite. flexible selection algorithm is to allow the receiver to pick any of the transmit antennas that can satisfy a predetermined performance target. Such an algorithm is referred to as the arbitrarily ordered transmit antenna selection algorithm. However, the effectiveness of transmit antenna selection is decreased by several propagation impairments over the feedback channel from the receiver to the transmitter. Of these impairments, the feedback channel time delay may impose a significant impact on the achieved performance. This paper aims to investigate the impact of this time delay on the performance of receive maximal-ratio combining (MRC) diversity employing the arbitrarily ordered transmit antenna selection algorithm. In order to obtain quantitative measures for this impact, new expressions for various performance criteria are obtained by using the new derived formulas for the probability density function (pdf) and the moment generating function (MGF) of the combined signal-to-noise ratio (SNR). Numerical and simulation results are presented to illustrate the effect of delayed (i.e. outdated) feedback information on the system performance for various transmit antenna selection scenarios.

关键词： System performance ANTENNA SYSTEM Performance metrics Receivers transmitter receivers transmitting antennas selection algorithm feedback information feedback channel diversity reception

来源：评论

学校读者我要写书评

暂无评论

selection from read-only memory with limited workspace

引用

THEORETICAL COMPUTER SCIENCE 2014年第0期554卷 64-73页

作者： Elmasry, Amr Juhl, Daniel Dahl Katajainen, Jyrki Satti, Srinivasa Rao Univ Alexandria Dept Comp Engn & Syst Alexandria Egypt Univ Copenhagen Dept Comp Sci DK-1168 Copenhagen Denmark Seoul Natl Univ Sch Comp Sci & Engn Seoul 151 South Korea

Given an unordered array of N elements drawn from a totally ordered set and an integer k in the range from 1 to N, in the classic selection problem the task is to find the k-th smallest element in the array. We study the complexity of this problem in the space-restricted random-access model: The input array is stored on read-only memory, and the algorithm has access to a limited amount of workspace. We prove that the linear-time prune-and-search algorithm-presented in most textbooks on algorithms-can be modified to use Theta(N) bits instead of Theta(N) words of extra space. Prior to our work, the best known algorithm by Frederickson could perform the task with Theta(N) bits of extra space in O (Nlg* N) time. Our result separates the space-restricted randomaccess model and the multi-pass streaming model, since we can surpass the Omega(Nlg* N) lower bound known for the latter model. We also generalize our algorithm for the case when the size of the workspace is O (S) bits, where lg(3) N <= S <= N. The running time of our generalized algorithm is O (Nlg* (N/S) + N(lgN)/lg S), slightly improving over the O (Nlg*(N (lgN)/S) + N(lgN)/lg S) bound of Frederickson's algorithm. To obtain the improvements mentioned above, we developed a new data structure, called the wavelet stack, that we use for repeated pruning. We expect the wavelet stack to be a useful tool in other applications as well. (C) 2014 Elsevier B.V. All rights reserved.

关键词： selection algorithm Read-only memory Random-access machine Multi-pass streaming Bit vector Wavelet stack

来源：评论

学校读者我要写书评

暂无评论

selection and Rate-Adaptation Schemes for MIMO Multiple-Access Channels With Low-Rate Channel Feedback

引用

IEEE TRANSACTIONS ON INFORMATION THEORY 2015年第11期61卷 5948-5975页

作者： Tang, Ti-Wen Tien, Hsiao-Ting Lu, Hsiao-feng (Francis) Natl Chiao Tung Univ Dept Elect & Comp Engn Hsinchu 300 Taiwan Natl Chiao Tung Univ Dept Elect & Comp Engn Hsinchu 30010 Taiwan

In this paper, two selection schemes are proposed for coded transmission over multiple-input multiple-output (MIMO) multiple-access channels (MAC) to yield a much higher diversity-multiplexing gain tradeoff (DMT) performance. These schemes require a channel feedback, but at an extremely low rate. The first scheme is based on user selection and can be easily implemented in the existing MIMO-MAC systems. Upper bounds on the minimal computational complexity required by sphere decoders to decode DMT-optimal codes for this scheme as well as for MIMO MAC without feedback are given. It is shown that this scheme can offer both a much larger DMT and an exponential reduction on decoding complexity, compared with the latter. The second scheme selects jointly the users and their transmit antennas. It requires an additional design of rate assignments for performance optimization. A very general framework on the design of optimal rate assignments is thus provided. It is shown that this scheme can yield DMT performances far superior to the optimal MIMO-MAC DMT without channel feedback. The simulation results confirm that in some cases, this scheme can provide an astonishing SNR gain of 14.64 dB at outage probability 10(-6) compared with the optimal MIMO-MAC coding schemes without feedback.

关键词： MIMO multiple-access channel feedback channel diversity-multiplexing tradeoff selection algorithm rate adaptation

来源：评论

学校读者我要写书评

暂无评论

Feature selection, Clustering, and Prototype Placement for Turbulence Datasets

引用

AIAA JOURNAL 2022年第3期60卷 1332-1346页

作者： Barone, Matthew Ray, Jaideep Domino, Stefan Sandia Natl Labs Aerosci Dept Tech Staff Albuquerque NM 87185 USA Sandia Natl Labs Extreme Scale Data Sci & Analyt Dept Tech Staff Albuquerque NM 87185 USA Sandia Natl Labs Computat Thermal & Fluid Mech Dept Tech Staff Albuquerque NM 87185 USA Stanford Univ Inst Computat & Math Engn Stanford CA 94305 USA

This paper explores automated approaches for the analysis and categorization of turbulent flow data as a means of assessing the quality of a turbulence dataset used for constructing data-driven turbulence closures. Single-point statistics from several high-fidelity turbulent flow simulation datasets are differentiated into groups using a Gaussian mixture model clustering algorithm. Candidate features are proposed, and a feature selection algorithm is applied to the data in a sequential fashion, flow by flow, to identify a good feature set and an optimal number of clusters for each dataset. Clusters are first identified for plane channel flows, producing results that agree with existing theory and empirical observations. Further clusters are then identified in an incremental fashion for flow over a wavy-walled channel, flow over a bump in a channel, and flow past a square cylinder. Some clusters are closely identified with the anisotropy state of the turbulence, whereas others can be connected to physical phenomena, such as boundary-layer separation and free shear layers. Exemplar points from the clusters, or prototypes, are then identified using a prototype placement method. These exemplars effectively summarize the dataset using a greatly reduced collection of data points. The clusters and their prototypes are used to assess the quality of a training dataset constructed by simply pooling the four flows. We enumerate the dataset's shortcomings and state the limits of generalizability of any data-driven closure trained on it.

关键词： Turbulence Kinetic Energy Turbulent Flow Boundary Layer Separation Gaussian Mixture Models selection algorithm Computational Fluid Dynamics Reynolds Averaged Navier Stokes Turbulence Models Velocity Profiles Principal Stresses

来源：评论

学校读者我要写书评

暂无评论

Efficient frequency-domain sample selection for recovering limited-support images

引用

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2003年第1期20卷 67-77页

作者： Blakeley, ND Bones, PJ Millane, RP Renaud, P Univ Canterbury Dept Elect & Comp Engn Christchurch 1 New Zealand Univ Canterbury Dept Math Christchurch New Zealand

An image whose region of support is smaller than its bounding rectangle can, in principle, be reconstructed from a subset of the Nyquist samples. However, determining such a sampling set that gives a stable reconstruction is a difficult and computationally intensive problem. An algorithm is developed for determining periodic nonuniform sampling patterns that is orders of magnitude faster than existing algorithms. The speedup is achieved by using a sequential selection algorithm and heuristic metrics for the quality of sampling sets that are fast to compute, as opposed to the more rigorous linear algebraic metrics that have been used previously. Simulations show that the sampling sets determined using the new algorithm give image reconstructions that are of accuracy comparable with those determined by other slower algorithms. (C) 2003 Optical Society of America.

关键词： Subset Nonuniform sampling Sampling RECOVERING image reconstruction algorithms region of support Fasting selection algorithm SETTING Rectangle

来源：评论

学校读者我要写书评

暂无评论

Rough Terrain Mapping and Classification for Foothold selection in a Walking Robot

引用

JOURNAL OF FIELD ROBOTICS 2011年第4期28卷 497-528页

作者： Belter, Dominik Skrzypczynski, Piotr Poznan Univ Tech Inst Control & Informat Engn Ul Piotrowo 3A PL-60965 Poznan Poland

Although legged locomotion over a moderately rugged terrain can be accomplished by employing simple reactions to the ground contact information, a more effective approach, which allows predictively avoiding obstacles, requires a model of the environment and a control algorithm that takes this model into account when planning footsteps and leg movements. This article addresses the issues of terrain perception and modeling and foothold selection in a walking robot. An integrated system is presented that allows a legged robot to traverse previously unseen, uneven terrain using only onboard perception, provided that a reasonable general path is known. An efficient method for real-time building of a local elevation map from sparse two-dimensional (2D) range measurements of a miniature 2D laser scanner is described. The terrain mapping module supports a foothold selection algorithm, which employs unsupervised learning to create an adaptive decision surface. The robot can learn from realistic simulations;therefore no a priori expert-given rules or parameters are used. The usefulness of our approach is demonstrated in experiments with the six-legged robot Messor. We discuss the lessons learned in field tests and the modifications to our system that turned out to be essential for successful operation under real-world conditions. (C) 2011 Wiley Periodicals, Inc.

关键词： field experimentation walking robots Legged robot Biped locomotion Unsupervised learning Contact Information selection algorithm terrain mapping terrains Rough terrain Computer algorithms

来源：评论

学校读者我要写书评

暂无评论

JOINT PARALLEL INTERFERENCE CANCELLATION AND RELAY selection algorithmS BASED ON GREEDY TECHNIQUES FOR COOPERATIVE DS-CDMA SYSTEMS

JOINT PARALLEL INTERFERENCE CANCELLATION AND RELAY SELECTION...

引用

IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Jiaqi Gu Rodrigo C. de Lamare Communications Research Group Department of Electronics University of York U.K.

ISBN: (纸本)9781479928941

In this work, we propose a cross-layer design strategy based on the parallel interference cancellation (PIC) detection technique and a multi-relay selection algorithm for the uplink of cooperative direct-sequence code-division multiple access (DS-CDMA) systems. We devise a low-cost greedy list-based PIC (GL-PIC) strategy with RAKE receivers as the front-end that can approach the maximum likelihood detector performance. We also present a low-complexity multi-relay selection algorithm based on greedy techniques that can approach the performance of an exhaustive search. Simulations show an excellent bit error rate performance of the proposed detection and relay selection algorithms as compared to existing techniques.

关键词： selection algorithm CDMA mobile communications Direct-sequence code-division multiple access bit error rate performance RAKE receivers relay CANCELLATIONS up link Joints

来源：评论

学校读者我要写书评

暂无评论

Effective Analysis of Feature selection algorithms for Network based Intrusion Detection System

Effective Analysis of Feature Selection Algorithms for Netwo...

引用

IEEE Bombay Section Signature Conference (IBSSC)

作者： Trupti Chandak Chaitanya Ghorpade Sanyam Shukla Computer Science and Engineering MANIT Bhopal India

ISBN: (纸本)9781538674765

Malicious activities can harm the security of the system. These activities must be avoided. Network traffic data can be monitored and analyzed by using intrusion detection system. Different data mining classification techniques are used to detect network attacks. Dimensionality reduction performs key role in the Intrusion Detection System, since detecting anomalies is time-consuming. Recently a lot of work has been done in feature selection. But, most of the authors have modified the KDD99 test dataset. Modification of training dataset is valid but modifying test dataset is against the machine learning ethics. This work comprises some of the recently proposed feature selection algorithm such as Information gain, Gain Ratio and Correlation-based feature selection with the objective of determining the reduced feature set. The performance is evaluated using a combination of any two feature selection technique. This study proposes a new heuristic based feature selection algorithm using naive Bayes classifier to detect the important reduced feature set. The results are evaluated on c4.5 decision tree classifier and the results are compared with the existing works. The evaluated results show that the proposed reduced feature set gives the effective and efficient performance.

关键词： Intrusion Detection System (IDS) Feature Reduction KDD99 Dataset Naive Bayes Classifier c4.5 Decision tree INTRUSION DETECTION SYSTEMS Feature extraction Bayesian classifier selection algorithm Accidents,emergencies and safety Dataset Network algorithms

来源：评论

学校读者我要写书评

暂无评论

Predicting the Protein Tertiary Structure by Hybrid Clonal selection algorithms on 3D Square Lattice

Predicting the Protein Tertiary Structure by Hybrid Clonal S...

引用

International Conference on Modern Problems of Radio Engineering, Telecommunications and Computer Science

作者： Iryna Fefelova Andrey Fefelov Mariia Voronenko Alexander Kornelyuk Anatoliy Sachenko Eduard Ryzhkov Volodymyr Lytvynenko Department Informatics and Computer Science Kherson National Technical University Kherson Ukraine Department of Design Kherson National Technical University Kherson Ukraine Department of Protein Engineering and Bioinformatics Institute of Molecular Biology and Genetics Kyiv Ukraine Reseach Institute for Intelligent Computer Systems Ternopil National Economic University Ternopil Ukraine Department of economic and information security Dnipro State University of Internal Affairs Dnipro Ukraine

ISBN: (数字)9781728155661

ISBN: (纸本)9781728155678

The article considers the task of predicting the tertiary structure of a protein based on its primary sequence. The task of protein folding is solved by searching for conformation with minimal energy, if you look in terms of optimization problem. The work describes the use of a hybrid artificial immune system. In our work we try to combine clonal selection algorithms with differential and trigonometric differential evolution algorithms. We use special coding and decoding methods for individual individuals. The affinity function reduces the number of solutions with self-intersections (incorrect conformations) in the developed hybrid algorithms. We chose the hydrophobic-polar Dill model on a three-dimensional square lattice to test our algorithms. The study shows the advantages of the developed algorithms in comparison with other existing methods using experimental studies of test sequences.

关键词： artificial immune systems biology computing evolutionary computation molecular biophysics optimisation proteins artificial immune systems biology computing evolutionary algorithm molecular biology selection algorithm algorithms Tertiary Protein Structure Clonal selection Proteins

来源：评论

学校读者我要写书评

暂无评论

selection on k-dimensional meshes with multiple broadcasting

引用

COMPUTER JOURNAL 1996年第2期39卷 140-144页

作者： Pan, Y Hamdi, M Singh, G HONG KONG UNIV SCI & TECHNOL DEPT COMP SCIKOWLOONHONG KONG KANSAS STATE UNIV DEPT COMP & INFORMAT SCIMANHATTANKS 66506

Randomized selection algorithms on k-dimensional mesh-connected computers with multiple broadcasting are proposed in this paper. We first show that a leader can be elected in O(log N) time on any k-dimensional mesh-connected computers with multiple broadcasting of size N. We then shaw that we can find the p-ah smallest element among a data set of size N in O((log N+k+N-1/(k(k+1)) log N) expected time using a regular N-1/k x...x N-1/k k-dimensional mesh and in O((log N+k(2)N(1/(k2k))) log N) expected time rasing an irregular N-(2k-1k+1/(k2k))x N-(2k-2k+1/(k2k)) x...x N-(k+1/(k2k)) dimensional mesh, This leads to a selection algorithm, which runs In O((log N)(2)) expected time on a regular ((log N/log log N)(1/2)))-dimensional mesh ai on an irregular (log log N)-dimensional mesh each with N processors. To our best knowledge, this is the first polylogarithmic selection algorithm on meshes with multiple broadcasting.

关键词： algorithm broadcasting algorithms Computers selection algorithm Medical Subject Headings

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：