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A Novel 3D CAD Model Retrieval Method Based on Vertices Classification and Weights Combination Optimization

MATHEMATICAL PROBLEMS IN ENGINEERING 2017年第1期2017卷 1-12页

作者： Zhuang, Ting Zhang, Xutang Hou, Zhenxiu Zuo, Wangmeng Liu, Yan Harbin Inst Technol Sch Mechatron Engn Harbin Peoples R China Harbin Inst Technol Sch Comp Sci & Technol Harbin Peoples R China Harbin Inst Technol Sch Sci Harbin Peoples R China

3D shape retrieval is a problem of current interest in different fields, especially in the mechanical engineering domain. According to our knowledge, multifeature based techniques achieve the best performance at present. However, the practicability of those methods is badly limited due to the high computational cost. To improve the retrieval efficiency of 3D CAD model, we propose a novel 3D CAD model retrieval algorithm called VSC-WCO which consists of a new 3D shape descriptor named VSC and Weights Combination Optimization schemeWCO. VSC represents a 3Dmodel with three distance distribution histograms based on vertices classification. The weighted sum of.. 1 norm distances between corresponding distance histograms of two VSC descriptors is regarded as dissimilarity of two models. For higher retrieval accuracy on a classified 3D model database, WCO is proposed based on Particle Swarm Optimization and existing class information. Experimental results on ESB, PSB, and NTU databases show that the discriminative power of VSC is already comparable to or better than several typical shape descriptors. After WCO is employed, the performance of VSC WCO is similar to the leading methods by all performance metrics and is much better by computational efficiency.

关键词： MECHANICAL engineering computer-aided design INFORMATION retrieval MATHEMATICAL optimization computer algorithms

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A general control algorithm for cooling towers in cooling plants with electric and/or gas-driven chillers

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HVAC&R RESEARCH 2007年第4期13卷 581-598页

作者： Braun, James E. Purdue Univ Ray W Herrick Labs W Lafayette IN 47907 USA

A hybrid chiller plant employs a combination of chillers that are "powered" by electricity and natural gas. This paper presents an algorithm for determining cooling tower fan settings in hybrid plants in response to loadings on individual chillers. Parameters of the algorithm are evaluated using design information for the chillers and cooling tower fans. In addition to reducing operating costs, use of the open-loop control strategy simplifies the control and improves the stability of the tower control compared with the use of a constant condenser water supply or approach to wet-bulb. Simulated plant cooling costs associated with the algorithm were compared with costs for optimized settings and were within 1% of the minimum costs. The control method is general, in the sense that it also applies to cooling plants that have all electric or all natural gas chillers.

关键词： GAS DRIVE control strategy algorithms Control Methods COOLING EQUIPMENT CHILLER Water cooling towers Manufacturing costs computer algorithms Bulb (plant) Electricity

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On the Computational Complexity of Matrix Semigroup Problems

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FUNDAMENTA INFORMATICAE 2012年第1-4期116卷 1-13页

作者： Bell, Paul C. Potapov, Igor Univ Loughborough Dept Comp Sci Loughborough LE11 3TU Leics England Univ Liverpool Dept Comp Sci Liverpool L69 3BX Merseyside England

Most computational problems for matrix semigroups and groups are inherently difficult to solve and even undecidable starting from dimension three. The questions about the decidability and complexity of problems for two-dimensional matrix semigroups remain open and are directly linked with other challenging problems in the field. In this paper we study the computational complexity of the problem of determining whether the identity matrix belongs to a matrix semigroup (the Identity Problem) generated by a finite set of 2 x 2 integral unimodular matrices. The Identity Problem for matrix semigroups is a well-known challenging problem, which has remained open in any dimension until recently. It is currently known that the problem is decidable in dimension two and undecidable starting from dimension four. In particular, we show that the Identity Problem for 2 x 2 integral unimodular matrices is NP-hard by a reduction of the Subset Sum Problem and several new encoding techniques. An upper bound for the nontrivial decidability result by C. Choffrut and J. Karhumaki is unknown. However, we derive a lower bound on the minimum length solution to the Identity Problem for a constructible set of instances, which is exponential in the number of matrices of the generator set and the maximal element of the matrices. This shows that the most obvious candidate for an NP algorithm, which is to guess the shortest sequence of matrices which multiply to give the identity matrix, does not work correctly since the certificate would have a length which is exponential in the size of the instance. Both results lead to a number of corollaries confirming the same bounds for vector reachability, scalar reachability and zero in the right upper corner problems.

关键词： COMPUTATIONAL complexity DECIDABILITY (Mathematical logic) SEMIGROUPS (Algebra) computer algorithms MATRICES EXPONENTIAL functions

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Verification of cache coherence protocols by aggregation of distributed transactions

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THEORY OF COMPUTING SYSTEMS 1998年第4期31卷 355-376页

作者： Park, S Dill, DL Stanford Univ Dept Comp Sci Stanford CA 94305 USA

This paper presents a method to verify the correctness of protocols and distributed algorithms. The method compares a state graph of the implementation with a specification which is a state graph representing the desired abstract behavior. The steps in the specification correspond to atomic transactions, which are not atomic in the implementation. The method relies on an aggregation function, which is a type of abstraction function that aggregates the steps of each transaction in the implementation into a single atomic transaction in the specification. The key idea in defining the aggregation function is that it must complete atomic transactions which have committed but are not finished. This paper illustrates the method on a directory-based cache coherence protocol developed for the Stanford FLASH multiprocessor. The coherence protocol consisting of more than a hundred different kinds of implementation steps has been reduced to a specification with six kinds of atomic transactions. Based on the reduced behavior, it is very easy to prove crucial properties of the protocol including data consistency of cached copies at the user level. This is the first correctness proof verified by a theorem-prover for a cache coherence protocol of this complexity. The aggregation method is also used to prove that the reduced protocol satisfies a desired memory consistency model.

关键词： DISTRIBUTED computing computer algorithms GRAPHIC methods

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Elliptical-Tukey chirp signal for high-resolution, air-coupled ultrasonic imaging

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IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL 2007年第8期54卷 1530-1540页

作者： Pallav, Prakash Gan, Tat Hean Hutchins, David A. Univ Warwick Sch Engn Coventry CV4 7AL W Midlands England

A new signal processing method, which uses a modified chirp signal for air-coupled ultrasonic imaging, is described. A combination of the elliptical and Tukey window functions has been shown to give a better performance than the Harming windowing used in most pulse-compression algorithms for air-coupled applications. The elliptical-Tukey chirp signal provides an improvement in both the resolution of images and signal-to-noise ratios. In addition, this type of signal also reduces the level of signal voltages required to drive the source transducer while maintaining the performance of the system. This approach, thus, may have wide interest in all forms of wide bandwidth ultrasonic imaging.

关键词： ULTRASONIC imaging SIGNAL processing WINDOWS (Graphical user interfaces) computer algorithms SIGNAL-to-noise ratio TRANSDUCERS BANDWIDTHS

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Automatic mapping of parallel applications on multicore architectures using the Servet benchmark suite

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computerS & ELECTRICAL ENGINEERING 2012年第2期38卷 258-269页

作者： Gonzalez-Dominguez, Jorge Taboada, Guillermo L. Fraguela, Basilio B. Martin, Maria J. Tourino, Juan Univ A Coruna Dept Elect & Syst Comp Architecture Grp La Coruna 15071 Spain

Servet is a suite of benchmarks focused on detecting a set of parameters with high influence on the overall performance of multicore systems. These parameters can be used for autotuning codes to increase their performance on multicore clusters. Although Servet has been proved to detect accurately cache hierarchies, bandwidths and bottlenecks in memory accesses, as well as the communication overhead among cores, up to now the impact of the use of this information on application performance optimization has not been assessed. This paper presents a novel algorithm that automatically uses Servet for mapping parallel applications on multicore systems and analyzes its impact on three testbeds using three different parallel programming models: message-passing, shared memory and partitioned global address space (PGAS). Our results show that a suitable mapping policy based on the data provided by this tool can significantly improve the performance of parallel applications without source code modification. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： computer architecture CLUSTER analysis (Statistics) CACHE memory computer algorithms SYSTEMS theory SOURCE code (computer science) DATA analysis MATHEMATICAL optimization

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CURVE FITTING BASED PARTICLE SWARM OPTIMIZATION FOR UWB PATCH ANTENNA

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JOURNAL OF ELECTROMAGNETIC WAVES AND APPLICATIONS 2009年第17-18期23卷 2421-2432页

作者： Islam, M. T. Moniruzzaman, M. Misran, N. Shakib, M. N. Univ Kebangsaan Malaysia Inst Space Sci ANGKASA Bangi 43600 Selangor De Malaysia Univ Kebangsaan Malaysia Dept Elect Elect & Syst Engn Bangi 43600 Selangor De Malaysia

An optimization technique for microstrip patch antenna using Curve Fitting based Particle Swarm Optimization (CFPSO) is presented in this paper. An E-H shaped patch antenna designed using conventional optimization technique for Ultra Wide Band (UWB) communication is utilized to demonstrate the optimization technique. The conventional optimized antenna is designed by searching an acceptable solution from amongst the invariably huge collective range of geometry variables. The data for curve fitting is obtained from EM simulator by varying different geometrical parameters of the antenna. Using the data, the equations representing the relationship among different parameters of a microstrip antenna are generated. Curve fitting software was used to generate the curve. The CFPSO program was developed and executed in MATLAB. Conventionally optimized antenna is compared with CFPSO optimized antenna in this paper. The result yields that CFPSO showed remarkable improvement over bandwidth. For the E-H shaped antenna, the bandwidth is increased by 27% compared to conventionally optimized antenna.

关键词： MICROSTRIP antennas MICROWAVE antennas STRIP transmission lines PARTICLE swarm optimization SWARM intelligence computer algorithms

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A hybrid evolutionary preprocessing method for imbalanced datasets

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INFORMATION SCIENCES 2018年 454卷 161-177页

作者： Wong, Ginny Y. Leung, Frank H. F. Ling, Sai-Ho Hong Kong Polytech Univ Dept Elect & Informat Engn Ctr Signal Proc Hong Kong Hong Kong Peoples R China Univ Technol Sydney Fac Engn & Informat Technol Ctr Hlth Technol Sydney NSW Australia

Imbalanced datasets are commonly encountered in real-world classification problems. Many machine learning algorithms are originally designed for well-balanced datasets, therefore re-sampling has become an important step to pre-process imbalanced data. This aims to balance the datasets by increasing the samples of the smaller class or decreasing the samples of the larger class, which are known as over-sampling and under-sampling, respectively. In this paper, a sampling strategy that is based on both over-sampling and under-sampling is proposed, in which the new samples of the smaller class are created based on fuzzy logic. Improvement of the datasets is done by the evolutionary computational method of Cross-generational elitist selection, Heterogeneous recombination and Cataclysmic mutation (CHC) that under-samples both the minority and majority samples. Consequently, a hybrid preprocessing method is proposed to re-sample imbalanced datasets. The evaluation is done by applying the Support Vector Machine (SVM), C4.5 decision tree and nearest neighbor rule to train a classification model from the re-sampled training sets. From the experimental results, it can be seen that our proposed method improves both the F-measure and AUC. The over-sampling rate and complexity of the classification model are also compared. Our proposed method is found to be superior to all other methods under comparison and it is more robust in different classifiers. (C) 2018 Published by Elsevier Inc.

关键词： HYBRID systems EVOLUTIONARY theories MACHINE learning computer algorithms SAMPLING (Statistics)

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Fair TCP congestion control in heterogeneous networks with explicit congestion notification

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IEE PROCEEDINGS-COMMUNICATIONS 2005年第1期152卷 13-21页

作者： Byun, HJ Lim, JT Korea Adv Inst Sci & Technol Dept Elect Engn & Comp Sci Taejon 305701 South Korea

The authors propose a window-based congestion control algorithm to achieve max-min fair sharing of the available bandwidth in ECN capable heterogeneous TCP networks. The proposed algorithm extracts the network status from successive binary congestion information provided by ECN. From the extracted network information, the authors estimate a fair window size proportional to the propagation delay. Through simulations, the effect on TCP fairness of the proposed algorithm is shown for the heterogeneous network.

关键词： effective bandwidth telecommunication congestion control network information Heterogeneous networks Tritolyl Phosphates BECN Window Size tactical command post Propagation delay FECN computer algorithms notification

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Incremental rate control for H.264/AVC video compression

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IET IMAGE PROCESSING 2009年第5期3卷 286-298页

作者： Sun, Y. Zhou, Y. Feng, Z. He, Z. Sun, S. Univ Cent Arkansas Dept Comp Sci Conway AR 72034 USA Univ Elect Sci & Technol China Coll Comp Sci & Engn Chengdu 610054 Peoples R China Acxiom Corp Conway AR 72034 USA Univ Missouri Dept Elect & Comp Engn Columbia MO 65211 USA

In this study, the authors propose a new rate-complexity-quantisation model and an incremental rate control algorithm for H.264/AVC video coding. One unique property of this algorithm is that, the picture complexity estimation and rate-quantisation modelling are jointly designed with an incremental rate control for P-frames. In addition, the proposed algorithm also introduces a number of efficient rate control techniques, including accurate rate control for intra-frames, enhanced proportional-integral-derivative (PID) buffer controller, and adaptive quantisation parameter determination for B-frames. The proposed algorithm has low computational complexity while providing robust rate control. Our extensive experimental results demonstrate that the proposed algorithm outperforms the current rate control algorithm adopted in the H.264/AVC reference software JM13.2 by achieving more accurate rate control, reducing frame skipping, depressing quality fluctuation and improving the overall coding quality by up to 2.83 dB.

关键词： rate control algorithms complexity classes computer algorithms

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