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A HYBRID STAGGERED/SEMISTAGGERED FINITE-DIFFERENCE ALGORITHM FOR SOLVING TIME-DEPENDENT INCOMPRESSIBLE NAVIER-STOKES EQUATIONS ON CURVILINEAR GRIDS

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NUMERICAL HEAT TRANSFER PART B-FUNDAMENTALS 2014年第1期65卷 1-26页

作者： Babaee, Hessam Acharya, Sumanta Louisiana State Univ Dept Mech Engn Baton Rouge LA 70803 USA

An accurate and efficient finite-difference method for solving the incompressible Navier-Stokes equations on curvilinear grids is developed. This method combines the favorable features of the staggered grid and semistaggered grid approaches. All components of velocity are stored at the corner vertices, and pressure is stored at the grid cell centers. All components of the momentum equations are discretized at cell vertices, facilitating a consistent discretization of the diffusive and convective terms as the boundaries are approached. The Christoffel symbol does not appear in the transformed equations and the cost of computation is comparable to that of the staggered-grid approach. A projection method is used to effectively evolve the discrete system in time, while ensuring a divergence-free velocity field. The discrete divergence and gradient operators of the projection step are constructed on a staggered gird layout leading to exact satisfaction of the discrete continuity. The solution of the Poisson-Neumann equation in the projection step is free of any spurious eigenmodes. The validity of the method is demonstrated on four benchmark problems. The Taylor-Green vortex problem is solved on a curvilinear grid with highly skewed cells and a second-order convergence in l-norm is observed. The mixed convection in a lid-driven cavity is solved on a highly curvilinear grid and excellent agreement with literature is obtained. The results for flow past a cylinder and pusatile flow in a 90 degrees bend are compared with the existing experimental data in the literature. The predictions agree well with the measured data, and validate the approach used.

关键词： FINITE difference method computer algorithms NAVIER-Stokes equations CURVILINEAR coordinates MOMENTUM (Mechanics) LINEAR operators CHRISTOFFEL-Darboux formula

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Simplified method of calculating the operating characteristics of a face seal

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CHEMICAL AND PETROLEUM ENGINEERING 2003年第9-10期37卷 547-552页

作者： Mel'nik, VA MV Keldysh Res Ctr Moscow Russia

We note that the seal can function stably in the fluid friction mode (for thechosen design characteristics of the seal unit) when the axial rigidity of the lifting layer at thecontact of the parr of surfaces of the face seal ring pair is high. That rigidity is the parameterfor optimizing a seal with a wedge-shaped slot. When designing the unit, the designer must strive tocreate a face seal with the highest attainable lifting layer rigidity in the contact of the facesurfaces of the ring pair.

关键词： algorithms GELS (Pharmacy) FLUID dynamics ARITHMETIC -- Foundations FLUID mechanics computer algorithms

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Congested Link Inference algorithms in Dynamic Routing IP Network

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MATHEMATICAL PROBLEMS IN ENGINEERING 2017年第1期2017卷 1-17页

作者： Chen, Yu Duan, Zhe-min Northwestern Polytech Univ Xian 710072 Peoples R China Zhengzhou Univ Aeronaut Zhengzhou 450015 Peoples R China

The performance descending of current congested link inference algorithms is obviously in dynamic routing IP network, such as the most classical algorithm CLINK. To overcome this problem, based on the assumptions of Markov property and time homogeneity, we build a kind of Variable Structure Discrete Dynamic Bayesian (VSDDB) network simplified model of dynamic routing IP network. Under the simplified VSDDB model, based on the Bayesian Maximum A Posteriori (BMAP) and Rest Bayesian Network Model (RBNM), we proposed an Improved CLINK (ICLINK) algorithm. Considering the concurrent phenomenon of multiple link congestion usually happens, we also proposed algorithm CLILRS (Congested Link Inference algorithm based on Lagrangian Relaxation Subgradient) to infer the set of congested links. We validated our results by the experiments of analogy, simulation, and actual Internet.

关键词： INFERENTIAL statistics DISCRETE systems MARKOV processes ROUTING (computer network management) BAYESIAN analysis computer algorithms

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APPRAISAL OF LIQUEFACTION POTENTIAL USING NEURAL NETWORK AND NEURO FUZZY APPROACH

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APPLIED ARTIFICIAL INTELLIGENCE 2013年第8期27卷 700-720页

作者： Venkatesh, Kumar Kumar, Vijay Tiwari, R. P. Motilal Nehru Natl Inst Technol Dept Civil Engn Allahabad 211004 Uttar Pradesh India

In this study, standard penetration test dependent bore-log charts of different boreholes were collected for selected locations in order to prepare the datasets. Datasets were applied to the Idriss and Boulanger method to evaluate liquefaction potential. Complete datasets were used for development of neural network and neuro-fuzzy models. Feed forward backpropagation algorithm with a multilayer perceptron network is utilized to analyze the liquefaction occurrence in different locations. To meet the objective, 159 sets of geotechnical data were collected, out of which 133 datasets were used for development of models and 26 datasets were used for validation. Neural network models were trained with six input vectors by optimum numbers of hidden layers, epoch, and suitable transfer functions. Neuro-fuzzy models have been developed using the Takagi-Sugeno-Kang reliant approach. The predicted values of liquefaction potential by artificial neural networks and neuro-fuzzy models were compared with an empirical method (i.e., Idriss and Boulanger method). The compared values of liquefaction potential obtained by neural network and neuro-fuzzy models shows that trained artificial neural network models' prediction capability are better than that of neuro-fuzzy models.

关键词： NEURAL networks (computer science) computer algorithms MATHEMATICAL models DATA analysis BOREHOLES FUZZY neural networks COMPARATIVE studies

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Consistent DOA estimation of heavily noisy gunshot signals using a microphone array

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IET RADAR SONAR AND NAVIGATION 2016年第9期10卷 1519-1527页

作者： Cardoso Ribeiro Borzino, Angelo Marcio Apolinario, Jose Antonio, Jr. Rodrigues de Campos, Marcello Luiz Mil Inst Engn IME Program Def Engn Rio De Janeiro Brazil Fed Univ Rio De Janeiro UFRJ Program Elect Engn Rio De Janeiro Brazil

Direction of arrival (DOA) estimation of a gunshot is an important issue in shooter localisation. As the distance between the firing position and the sensor array increases, the signal-to-noise ratio decreases, which degrades the accuracy of the DOA estimation. Strong noise may lead to false peaks in cross-correlation functions, which may result in spurious time difference of arrival (TDOA) estimates and hence spurious DOA estimates. The proposed gunshot DOA estimation algorithm [exhaustive search-searching consistent fundamental loop (ES-SCFL)] reduces this problem by combining the methods of standard estimation, ES, and SCFL. The ES-SCFL method looks for the best set of microphone pairs and the correct peaks of their cross-correlation functions, and uses the time lags of these peaks as the TDOA estimates for DOA estimation. The performance of the proposed algorithm is evaluated using real gunshot data recorded from a field experiment.

关键词： DIRECTION of arrival estimation (Signal processing) GUNFIRE detection systems SENSOR arrays computer algorithms ESTIMATION theory DATA recorders & recording

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Spectral matching approaches in hyperspectral image processing

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INTERNATIONAL JOURNAL OF REMOTE SENSING 2014年第24期35卷 8217-8251页

作者： Shanmugam, S. SrinivasaPerumal, P. Anna Univ Dept Geol Madras 600025 Tamil Nadu India

Many spectral matching algorithms, ranging from the traditional clustering techniques to the recent automated matching models, have evolved. This paper provides a review and up-to-date information on the past and current role of the spectral matching approaches adopted in hyperspectral satellite image processing. The need for spectral matching has been deliberated and a list of spectral matching algorithms has been compared and described. A review of the conventional spectral angle measures and the advanced automated spectral matching tools indicates that, for better performance of target detection, there is a need for combining two or more spectral matching techniques. From the studies of several authors, it is inferred that continuous improvement in the matching techniques over the past few years is due to the need to handle and analyse hyperspectral image data for various applications. The need to develop a well-built and specialized spectral library to accommodate the resources from enormous spectral data is suggested. This may improve accuracy in mineral and soil mapping, vegetation species identification and health monitoring, and target detection. The future role of cloud computing in accessing globally distributed spectral libraries and performing spectral matching is highlighted. Rather than inferring that a particular matching algorithm is the best, this paper points out the requirements of an ideal algorithm. With increasing usage of hyperspectral data for resources mapping, the review presented in this paper will certainly benefit the large and emerging community of hyperspectral image users.

关键词： RESEARCH Image registration Soil mapping Plant species computer algorithms Remote-sensing images Hyperspectral imaging systems

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Competitive algorithms for the dynamic selection of component implementations

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IBM SYSTEMS JOURNAL 2003年第1期42卷 85-97页

作者： Yellin, DM IBM Corp Div Res Thomas J Watson Res Ctr Yorktown Hts NY 10598 USA

As component-based development matures, more and more applications are built by integrating multiple distributed components. We suggest providing components with multiple implementations, each optimized for a particular workload,and augmenting the component run-time environment with a mechanism for switching between implementations. This mechanism monitors the types of requests the component is receiving, and adaptively switches implementations for optimal application performance. Achieving this optimal performance depends on making good choices as to when and how to switch implementations, a problem, we refer to as the adaptive component problem. We first formalize the generic problem and then provide an algorithm, named Delta, for switching implementations in the special case when the component has exactly two implementations. We show that this algorithm is (3 + epsilon)-competitive with respect to the optimal algorithm, where epsilon is a small fraction. We establish a 3-competitve lower bound for the problem, which implies that Delta is close to optimal. We describe the application of these results to the distributed pub/sub problem, and the data structure selection problem.

关键词： computer algorithms AUTOMATIC programming (computer science)

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Least Trimmed Squares Approach to Lucas-Kanade Algorithm in Object Tracking Problems

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MATHEMATICAL PROBLEMS IN ENGINEERING 2013年第1期2013卷 1-6页

作者： Lin, Yih-Lon I Shou Univ Dept Informat Engn Kaohsiung 84001 Taiwan

The object tracking problem is an important research topic in computer vision. For real applications such as vehicle tracking and face tracking, there are many efficient and real-time algorithms. In this study, we will focus on the Lucas-Kanade (LK) algorithm for object tracking. Although this method is time consuming, it is effective in tracking accuracy and environment adaptation. In the standard LK method, the sum of squared errors is used as the cost function, while least trimmed squares is adopted as the cost function in this study. The resulting estimator is robust against outliers caused by noises and occlusions in the tracking process. Simulations are provided to show that the proposed algorithm outperforms the standard LK method in the sense that it is robust against the outliers in the object tracking problems.

关键词： LEAST squares computer algorithms OBJECT tracking (computer vision) computer vision APPLICATION software REAL-time computing

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Substation planning method based on the weighted Voronoi diagram using an intelligent optimisation algorithm

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IET GENERATION TRANSMISSION & DISTRIBUTION 2014年第12期8卷 2173-2182页

作者： Lu, Zhiying Wang, Shiju Ge, Shaoyun Wang, Chengshan Tianjin Univ Minist Educ Key Lab Power Syst Simulat & Control Tianjin 300072 Peoples R China

Distribution network planning is a very complicated, non-linear, large scale multi-objective and multi-constraint combinatorial optimisation problem. The capacity, location and power supply range of the substation and the distribution network are optimised based on the load forecasting. In previous studies, this problem usually decomposes into two sub-problems, one is substation planning and the other is distribution network planning. The authors propose a method based on the self-adjustment weighted Voronoi diagram (WVD) using genetic algorithms and particle swarm optimisation for planning substations, which can optimise the location and power range of the substations when both the number and capacity of the substations are known. The weight is calculated according to the substation capacity and load distribution, and then the authors form the self-adjusted WVD whose weight can be adaptively adjusted. This method ensures the convergence of the algorithm and also makes the location and power supply range of the substations more reasonable. On this basis, the self-adjusted WVD based on the elitist selection genetic algorithm (ESGA-WVD) or the particle swarm optimisation algorithm (PSO-WVD) is achieved using the global search feature of the ESGA or the PSO. Numerical results show that ESGA-WVD and PSO-WVD are more reliable and reasonable than single ESGA, PSO or WVD;both in the determination of substation location and in the division of the substation power supply range. Compared with ESGA-WVD, PSO-WVD is better in terms of running time, convergence rate and investment costs.

关键词： ELECTRIC power distribution -- Planning ELECTRIC substations VORONOI polygons INTELLIGENT control systems computer algorithms

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All I really need to know about pair programming I learned in kindergarten

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COMMUNICATIONS OF THE ACM 2000年第5期43卷 108-114页

作者： Williams, LA Kessler, RR Univ Utah Dept Comp Sci Salt Lake City UT 84112 USA

The article highlights the success of pair programming based on a 'pair programming survey,' in context of Robert L. Fulgham's essay titled 'All I Really Need to Know I Learned in Kindergarten.' The article reports that when it comes to programming practices, studies show two heads are almost better than one. Pair programming is a practice in which two programmers work side-by-side at one computer, continuously collaborating on the same design, algorithm, code, or test. Anecdotal and initial statistical evidence indicates pair programming is highly beneficial, which is also attributed by Extreme programming. In the case of transition to pair programming from solitary programming, to avoid hesitation and to work successfully, some principles referred to are sharing of the work, sharing of key board typing and continuous analysis, avoiding negative thoughts, leaving ego etc. As a final thought, the article points out that making transition to pair programming involves breaking down some personal barriers. The success lies in hands of them in understanding the value of intercommunication skills, in confidently sharing the work and accepting the ownership of the partner's work. INSET: All I Really Need to Know I Learned in Kindergarten..

关键词： computer algorithms computer programmers computer software Intercommunication systems Electronic systems

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