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Developing an algorithm for reconstruction of blocky systems in discontinuous media: two-dimensional analysis

GEOMECHANICS AND GEOENGINEERING-AN INTERNATIONAL JOURNAL 2011年第3期6卷 171-183页

作者： Khishvand, Mohammad Jafari, Ahmad Rahami, Hossein Univ Tehran Univ Coll Engn Sch Min Engn POB 14395-515North Amirabad Ave Tehran Iran Univ Tehran Univ Coll Engn Dept Engn Sci Tehran Iran

Block detection is one of the most important steps in all discontinuous methods of analysis like Discontinuous Deformation Analysis (DDA) and Discrete ElementMethod (DEM). This is in fact a pre-processing step for those methods. In this study, a comprehensive computational algorithm, for tracing rock block created by discontinuities, has been developed. Using square matrices with integer elements and performing edge regularization step, reduce the size of the matrices due to elimination of unnecessary edges and vertices. Therefore speed and accuracy of block tracing operation will be increased. This algorithm is able to trace and identify all kind of blocks including convex and concave blocks formed by limited or unlimited fractures. The algorithm was programmed in C#. Net by over 3400 code lines and some cases were modeled by the code as example.

关键词： rock block tracing block detection computational algorithm matrix based method DDA DEM

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A framework for motion capture system design using Cramer-Rao lower bound

A framework for motion capture system design using Cramer-Ra...

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IEEE Pacific Rim Conference on Communications, Computers and Signal Processing (PACRIM)

作者： Aloui, Saifeddine Villien, Christophe Lesecq, Suzanne CEA LETI MINATEC Campus 17 Rue Martyrs F-38000 Grenoble France CEA LETI MINATEC F-38610 Gires France

ISBN: (纸本)9781457702518

Motion capture system design is becoming an important subject since the number of its applications is steadily growing and new technologies are introduced into the market. This paper presents a theoretical approach based on Cramer-Rao Lower Bound allowing the designer to choose a configuration (i.e. modality, placement) of sensors, compare different approaches and validate the efficiency of the estimation algorithm to be used in estimating the pose of a subject. An adapted Cramer-Rao bound expression has been derived, and its computational algorithm is presented. The optimization of the design of a human machine interface system based on arm, forearm and hand pose capture using magnetic sensors is then presented as an example.

关键词： Cramer-Rao bounds Cramer-Rao lower bound Joints Magnetic sensors Magnetic separation Sensor systems Ultrasonic variables measurement computational algorithm hand pose capture human machine interface magnetic sensors magnetic sensors motion capture system

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On the Use of Computation Optimization Opportunities in Computer Technologies for Applied and computational Mathematics Problems with Prescribed Quality Characteristics

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computational MATHEMATICS AND MATHEMATICAL PHYSICS 2010年第12期50卷 2166-2174页

作者： Babich, M. D. Zadiraka, V. K. Lyudvichenko, V. A. Sergienko, I. V. Natl Acad Sci Ukraine Glushkov Inst Cybernet UA-03187 Kiev Ukraine

The use of various opportunities for computation optimization in computer technologies for applied and computational mathematics problems with prescribed quality characteristics is investigated. More precisely, the choice and determination of computational resources and methods of their efficient use for finding an approximate solution of problems up to prescribed accuracy in a limited amount of processor time are investigated.

关键词： computer technology mathematical model of applied problem model of computations computation procedure computational algorithm estimates of computational algorithm quality

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computational algorithms for a Damage-coupled Cyclic Viscoplasticity Material Model

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INTERNATIONAL JOURNAL OF DAMAGE MECHANICS 2009年第6期18卷 507-532页

作者： Zhao, A. H. Chow, C. L. Univ Michigan Dept Mech Engn Dearborn MI 48128 USA

The primary objective of this investigation is to develop efficient and robust computational schemes for a damage-coupled cyclic thermoviscoplasticity model for solder materials. Three constitutive integration algorithms, Euler, modified Euler, and semi-implicit algorithm for the model are examined. The three algorithms for the model are coded in the commercial finite element (FE) code ABAQUS (version 6.21) via its user-defined material subroutine UMAT. Two single-step algorithms of the substep scheme are applied for the modified Euler algorithm to control the error in the integration of constitutive laws. A semi-empirical formulation is established for an adaptive time stepping algorithm that is based on the Euler algorithm. The simulations of single-element, miniature specimen and notched specimen simulations have been conducted and compared with the test results under monotonic tensile, creep, and fatigue tests of 63Sn-37Pb solder. It is observed that the explicit algorithm consistently requires much less CPU time than others. The modified Euler algorithm has shown, on the other hand, to be not only efficient but also accurate. The semi-implicit algorithm yields an accurate solution. It is worth noting that the method is also effective by applying an appropriate integration scheme.

关键词： thermoviscoplasticity damage mechanics solder finite element computational algorithm

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computational algorithm for inventory model with a service level constraint, lead time demand with the mixture of distributions and controllable negative exponential backorder rate

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APPLIED MATHEMATICS AND COMPUTATION 2006年第2期175卷 1125-1138页

作者： Lee, Wen-Chuan Wu, Jong-Wuu Hsu, Jye-Wei Natl Chiayi Univ Dept Appl Math Chiayi 60004 Taiwan Chang Jung Christian Univ Dept Int Business Tainan 711 Taiwan Tamkang Univ Dept Stat Tamsui 25137 Taipei Taiwan

In this paper, let the backorder rate be a control variable to widen applications of Wu and Tsai's model [J.W. Wu, H.Y. Tsai, Mixture inventory model with back orders and lost sales for variable lead time demand with the mixtures of normal distribution, International Journal of Systems Science 32 (2001) 259-268.]. And, we also assume that the backorder rate is dependent on the length of lead time through the amount of shortages. In addition, we assume that the lead time demand follows a mixture of normal distributions, and then we relax the assumption about the form of the mixture of distributions for the lead time demand and apply the minimax distribution free procedure to solve the problem. Further, instead of having a stock-out term in the objective function, a service level constraint is added to the models. Finally, we develop two computational algorithms to find the optimal order quantity and the optimal lead time. Furthermore, two numerical examples are also given to illustrate the results. (c) 2005 Elsevier Inc. All rights reserved.

关键词： order quantity backorder rate lead time service level minimax distribution free procedure mixture of distributions computational algorithm

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An efficient solution to a retrial queue for the performability evaluation of DHCP

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COMPUTERS & OPERATIONS RESEARCH 2010年第7期37卷 1191-1198页

作者： Tien Van Do Budapest Univ Technol & Econ Dept Telecommun H-1117 Budapest Hungary

The Dynamic Host Configuration Protocol (DHCP) is designed to provide an automatic mechanism for the allocation, configuration and management of IP addresses and TCP/IP protocol stack parameters of computers and devices in IP networks. The important feature of DHCP is a "dynamic allocation" mechanism, which assigns an IP address to a client for a limited period of time (called a lease time). Therefore, a previously allocated IP address can automatically be assigned to another host by a DHCP server upon the expiration of the lease time if a host does not renew the use of an allocated IP address. This paper proposes a retrial queueing model to approximate the performability of the DHCP dynamic allocation mechanism. An efficient computational algorithm is developed to calculate the steady state probabilities of a continuous time discrete state Markov process. A comparison of our approximate model with a detailed simulation model of the DHCP dynamic allocation mechanism shows an excellent agreement between the analytical and the simulation results. The impact of the lease time parameter on the performability of the DHCP dynamic allocation mechanism is also illustrated through a numerical study. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： Retrial queue computational algorithm DHCP dynamic allocation Lease time Performance model

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Energy balance analysis of wind-based pumped hydro storage systems in remote island electrical networks

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APPLIED ENERGY 2010年第8期87卷 2427-2437页

作者： Kaldellis, J. K. Kapsali, M. Kavadias, K. A. TEI Piraeus Lab Soft Energy Applicat & Environm Protect Athens 12201 Greece

The introduction of pumped hydro storage (PHS) systems in isolated electrical grids, such as those found in island regions, appears to be a promising solution that is able to face both the high electricity production cost and the continuously increasing power demand encountered in these areas In this context, the current work presents a methodology for the sizing of PHS systems that exploit the excess wind energy amounts produced by local wind farms, otherwise rejected due to imposed electrical grid limitations. The methodology is accordingly applied to the Greek island of Lesbos Initially, a calculation of the wind power penetration ability to the local grid is carried out and the corresponding curtailments of existing and future wind farms are determined. An integrated computational algorithm is then presented which simulates the operation of the system during an entire year and gives in detail the hourly operational status as well as the various energy losses of the system main components. Based on the application results obtained, the ability of the wind energy to remarkably contribute to the electrification of the remote islands becomes evident. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： Wind power penetration Wind power curtailments computational algorithm Electricity generation cost Renewable energy storage

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computational algorithm of least absolute deviation method for determining number of outliers under normality

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APPLIED MATHEMATICS AND COMPUTATION 2006年第1期175卷 609-617页

作者： Wu, Jong-Wuu Lee, Wen-Chuan Natl Chiayi Univ Dept Appl Math Chiayi 60004 Taiwan Chang Jung Christian Univ Dept Int Business Tainan Taiwan

In this paper, we suggest a least absolute deviation (LAD) method for the determination of the number of upper or lower outliers in normal sample by minimizing its sample mean absolute deviation. In consequence of computation of the criterion for LAD method need to use iterative numerical analysis, we also give a computational algorithm of LAD method to find the number of upper or lower outliers in normal sample. Finally, we give two examples to study the practical performance of the LAD method. (c) 2005 Elsevier Inc. All rights reserved.

关键词： least absolute deviation outlier normal distribution computational algorithm order statistic

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Controlling setup cost in (Q, r, L) inventory model with defective items

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APPLIED MATHEMATICAL MODELLING 2010年第6期34卷 1418-1427页

作者： Annadurai, K. Uthayakumar, R. PSNA Coll Engn & Technol Dept Math Dindigul 624622 Tamil Nadu India Gandhigram Rural Univ Dept Math Gandhigram 624302 Tamil Nadu India

This study discusses a mixture inventory model with back orders and lost sales in which the order quantity, reorder point, lead time and setup cost are decision variables. It is assumed that an arrival order lot may contain some defective items and the number of defective items is a random variable. There are two inventory models proposed in this paper, one with normally distributed demand and another with distribution free demand. Finally we develop two computational algorithms to obtain the optimal ordering policy, A computer code using the software Matlab is developed to derive the optimal solution and present numerical examples to illustrate the models. Additionally, sensitivity analysis is conducted with respect to the various system parameters. (C) 2009 Elsevier Inc. All rights reserved.

关键词： Setup cost Lead time Defective items Minimax distribution-free procedure computational algorithm Optimization

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On the existence and uniqueness of solutions of the inverse boundary value problem for determining the permittivity of materials

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computational MATHEMATICS AND MATHEMATICAL PHYSICS 2010年第9期50卷 1511-1521页

作者： Mironov, D. A. Smirnov, Yu. G. Penza State Univ Penza 440026 Russia

The problem of determining the permittivity of material samples of arbitrary shape placed in a rectangular waveguide with perfectly conducting walls is investigated. The problem is reduced to solving a nonlinear volume singular integral equation. A theorem on the existence and uniqueness of solutions to the nonlinear volume singular integral equation and of the inverse boundary value problem for determining the permittivity of the material is proved.

关键词： permittivity Maxwell equations inverse boundary value problem volume singular integral equation contraction principle computational algorithm

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