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Synthesis of clock tree topologies to implement nonzero clock skew schedule

IEE PROCEEDINGS-CIRCUITS DEVICES AND SYSTEMS 1999年第6期146卷 321-326页

作者： Kourtev, IS Friedman, EG Univ Rochester Dept Elect & Comp Engn Rochester NY 14627 USA

Designing the topology of a clock distribution network is considered for a synchronous digital integrated circuit so as to satisfy a nonzero clock skew schedule. A methodology and related algorithms for synthesising the topology of the clock distribution network from a clock schedule derived from circuit timing information are presented. A new formulation of the problem of designing the clock distribution network is given as an efficiently solvable integer linear programming problem. The approach is demonstrated on the suite of ISCAS'89 benchmark circuits. Up to 64% performance improvement is attained on these circuits by exploiting nonzero clock skew throughout the synchronous system. Clock tree topologies that implement the nonzero clock skew schedule based on the synthesis algorithms presented are described for each of the benchmark circuits.

关键词： clocks clock distribution network synthesis algorithms VLSI circuit timing information ISCAS'89 benchmark circuits integer programming integer linear programming problem nonzero clock skew schedule synchronous digital integrated circuit timing integrated circuit design linear programming logic CAD clock tree topologies

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On the Existence of an integer Solution to the Relaxed Weber problem for a Tree Network

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AUTOMATION AND REMOTE CONTROL 2019年第7期80卷 1288-1293页

作者： Panyukov, A. V. Natl Res Univ South Ural State Univ Chelyabinsk Russia

The problem of finding an optimal location of the vertices of a tree network in an assembly space representing a finite set is considered. The optimality criterion is the minimum total cost of location and communications in all points of this space. Different vertices of the tree can be located in a single point of the assembly space. This problem is well-known as the Weber problem. The representation of the Weber problem as a linear programming problem is given. It is proved that the set of all optimal solutions to the corresponding relaxed Weber problem for the tree network contains an integer solution. This fact can be used to improve the efficiency of algorithms for the problems differing from the Weber problem by the presence of additional constraints: it allows us to find the optimal value of the objective function, which in turn significantly reduces the complexity of calculating the optimal solution itself, e.g., by the branch-and-bound method.

关键词： location problem integer linear programming problem relaxed problem computational complexity polynomial algorithm

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Lagrangean relaxation for service location in large-scale networks with QoS constraints

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WIRELESS COMMUNICATIONS & MOBILE COMPUTING 2009年第12期9卷 1668-1682页

作者： Kamal, Zille Huma Al-Fuqaha, Ala Gupta, Ajay Western Michigan Univ Dept Comp Sci Kalamazoo MI 49008 USA

Current trends in computing indicate that there is a great potential for service-oriented computing and similar technologies, such as application-oriented networks (AONs), where services can relocate to adapt to the conditions of the underlying network. In Such environments, providing and consuming services and establishing a relationship between consumers (users of services) and producers (providers of services) are still challenging and vastly researched aspects. Bearing this in mind, we define a service location and planning (SLP) problem that uniquely matches producers to consumers and accounts for realistic parameters Such as, quality of service (QoS) constraints of throughput and delay, and network constraints of underlying link layer bandwidth capacities, and cost of meeting consumer requests. Our contribution lies in the mathematical formulation of the SLP problem as an integer linear programming (ILP) problem that can be solved optimally for small-scale networks and extending this work using Lagrangean relaxation (LR) approximation techniques to solve the SLP problem for large-scale networks. Copyright (C) 2009 John Wiley & Sons, Ltd.

关键词： managing network resources and services Lagrangean relaxation service location and planning problem application-oriented networks opportunistic networks optimization problem integer linear programming problem

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Synthesis of coupled antenna arrays using digital phase control via integer programming

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IET MICROWAVES ANTENNAS & PROPAGATION 2018年第6期12卷 999-1003页

作者： Echeveste, Jose Ignacio Gonzalez de Aza, Miguel A. Rubio, Jesus Zapata, Juan Catholic Univ Louvain ICTEAM Inst Louvain La Neuve Belgium Univ Politecn Madrid Dept SSR ETSI Telecomunicac Madrid Spain Univ Extremadura Escuela Politecn Caceres Dept TCC Caceres Spain

A pattern synthesis technique for real and coupled antenna arrays by using digital phase-only excitation weights is introduced here. The method is formulated as an integer linear programming problem incorporating a fast full-wave analysis of the array, based on the finite element method and spherical mode expansions. The method achieves radiation patterns with specified pointing directions, main lobe widths, minimum sidelobe level, and prescribed nulls, controlled by digital phase shifters.

关键词： antenna arrays digital control phase control integer programming antenna radiation patterns linear programming finite element analysis phase shifters coupled antenna array synthesis digital phase control pattern synthesis technique real antenna array digital phase-only excitation weights integer linear programming problem fast full-wave analysis finite element method spherical mode expansions radiation patterns specified pointing directions digital phase shifters prescribed nulls minimum sidelobe level main lobe widths

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Accurate inference of isoforms from multiple sample RNA-Seq data

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BMC GENOMICS 2015年第Sup2期16卷 S15-S15页

作者： Tasnim, Masruba Ma, Shining Yang, Ei-Wen Jiang, Tao Li, Wei Univ Calif Riverside Dept Comp Sci & Engn Riverside CA 92507 USA Tsinghua Univ MOE Key Lab Bioinformat TNLIST Dept Automat Beijing 100084 Peoples R China Tsinghua Univ Bioinformat Div TNLIST Dept Automat Beijing 100084 Peoples R China Tsinghua Univ Bioinformat Div TNLIST Dept Comp Sci & Technol Beijing 100084 Peoples R China Dana Farber Canc Inst Dept Biostat & Computat Biol Boston MA 02115 USA Harvard Univ Sch Publ Hlth Boston MA 02115 USA

Background: RNA-Seq based transcriptome assembly has become a fundamental technique for studying expressed mRNAs (i.e., transcripts or isoforms) in a cell using high-throughput sequencing technologies, and is serving as a basis to analyze the structural and quantitative differences of expressed isoforms between samples. However, the current transcriptome assembly algorithms are not specifically designed to handle large amounts of errors that are inherent in real RNA-Seq datasets, especially those involving multiple samples, making downstream differential analysis applications difficult. On the other hand, multiple sample RNA-Seq datasets may provide more information than single sample datasets that can be utilized to improve the performance of transcriptome assembly and abundance estimation, but such information remains overlooked by the existing assembly tools. Results: We formulate a computational framework of transcriptome assembly that is capable of handling noisy RNA-Seq reads and multiple sample RNA-Seq datasets efficiently. We show that finding an optimal solution under this framework is an NP-hard problem. Instead, we develop an efficient heuristic algorithm, called Iterative Shortest Path (ISP), based on linear programming (LP) and integer linear programming (ILP). Our preliminary experimental results on both simulated and real datasets and comparison with the existing assembly tools demonstrate that (i) the ISP algorithm is able to assemble transcriptomes with a greatly increased precision while keeping the same level of sensitivity, especially when many samples are involved, and (ii) its assembly results help improve downstream differential analysis.

关键词： integer linear programming Transcriptome Assembly Differential Analysis Assembly Result integer linear programming problem

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Performance of a routing and wavelength assignment scheme for an optical-carrier-reusable ring network

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IET NETWORKS 2014年第4期3卷 267-274页

作者： Keri, Masafumi Kitsuwan, Nattapong Matsuura, Motoharu Oki, Eiji Univ Electrocommun Dept Commun Engn & Informat Tokyo Japan Univ Electrocommun Ctr Frontier Sci & Engn Tokyo Japan

This study investigates a heuristic routing and wavelength assignment (RWA) scheme for an optical-carrier-reusable ring network. This network has two unique features. First, only one light source, called the multi-carrier light source, is required which eases the difficulty of controlling many light source devices. Second, optical carriers are reused in order to improve the efficiency of wavelength usage. Given the target of wavelength-resource-efficient channel establishment, performance of the heuristic RWA scheme is evaluated. To realise efficient wavelength usage, the authors formulate the RWA problem as an integer linear programming (ILP) problem of obtaining the minimum number of required wavelengths for given requests. With the ILP approach, the calculation process is not tractable in practical time. The heuristic RWA scheme introduced in this study solves the RWA problem. This scheme consists of two algorithms. Channel routes are obtained by the routing algorithm, and the wavelength assignment algorithm is then performed to assign a wavelength to each route. Moreover, two candidates, considering the shortest path and considering the avoidance of wavelength conversion, for the routing algorithm are examined. Numerical results show that the first candidate is more suitable in terms of reducing the number of required wavelengths than the second candidate.

关键词： integer programming light sources linear programming telecommunication network routing wavelength assignment ILP problem destination node heuristic RWA scheme heuristic routing and wavelength assignment integer linear programming problem multicarrier light source optical carrier reusable ring network source node wavelength converters wavelength resource efficient channel establishment

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Finding the Optimal Metric in Classification problems with Ordinal Features

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COMPUTATIONAL MATHEMATICS AND MATHEMATICAL PHYSICS 2010年第3期50卷 558-565页

作者： Iofina, G. V. Moscow Inst Phys & Technol Dolgoprudnyi 141700 Moscow Oblast Russia

A method for finding the optimal distance function for the classification problem with two classes in which the objects are specified by vectors of their ordinal features is proposed. An optimal distance function is sought by the minimization of the weighted difference of the average intraclass and interclass distances. It is assumed that a specific distance function is given for each feature, which is defined on the Cartesian product of the set of integer numbers in the range from 0 to N - 1 and takes values from 0 to M. Distance functions satisfy modified metric properties. The number of admissible distance functions is calculated, which enables one to significantly reduce the complexity of the problem. To verify the appropriateness of metric optimization and to perform experiments, the nearest neighbor algorithm is used.

关键词： classification problem metric classification algorithms integer linear programming problem

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Numerical optimization methods for packing equal orthogonally oriented ellipses in a rectangular domain

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COMPUTATIONAL MATHEMATICS AND MATHEMATICAL PHYSICS 2013年第11期53卷 1748-1762页

作者： Galiev, Sh. I. Lisafina, M. S. Kazan Natl Res Technol Univ Kazan 420111 Tatarstan Russia

linear models are constructed for the numerical solution of the problem of packing the maximum possible number of equal ellipses of given size in a rectangular domain R. It is shown that the l (p) metric can be used to determine the conditions under which ellipses with mutually orthogonal major axes (orthogonally oriented ellipses) do not intersect. In R a grid is constructed whose nodes generate a finite set T of points. It is assumed that the centers of the ellipses can be placed only at some points of T. The cases are considered when the major axes of all the ellipses are parallel to the x or y axis or the major axes of some of the ellipses are parallel to the x axis and the others, to the y axis. The problems of packing equal ellipses with centers in T are reduced to integer linear programming problems. A heuristic algorithm based on the linear models is proposed for solving the ellipse packing problems. Numerical results are presented that demonstrate the effectiveness of this approach.

关键词： numerical methods for ellipse packing packing of equal ellipses linear models for ellipse packing ellipse packing in rectangular domain integer linear programming problem

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Further reduction of minimal first-met bad markings for the computationally efficient synthesis of a maximally permissive controller

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INTERNATIONAL JOURNAL OF CONTROL 2015年第8期88卷 1423-1428页

作者： Liu, GaiYun Chao, Daniel Yuh Xidian Univ Sch Electromech Engn Xian 710071 Peoples R China Natl Chengchi Univ Dept Management & Informat Syst Taipei 116 Taiwan

To date, research on the supervisor design for flexible manufacturing systems focuses on speeding up the computation of optimal (maximally permissive) liveness-enforcing controllers. Recent deadlock prevention policies for systems of simple sequential processes with resources ((SPR)-P-3) reduce the computation burden by considering only the minimal portion of all first-met bad markings (FBMs). Maximal permissiveness is ensured by not forbidding any live state. This paper proposes a method to further reduce the size of minimal set of FBMs to efficiently solve integer linear programming problems while maintaining maximal permissiveness using a vector-covering approach. This paper improves the previous work and achieves the simplest structure with the minimal number of monitors.

关键词： flexible manufacturing system Petri net deadlock siphon integer linear programming problem

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A Two-phase Heuristic Method for Agri-fresh Inventory Optimisation

A Two-phase Heuristic Method for Agri-fresh Inventory Optimi...

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IEEE Symposium Series on Computational Intelligence (IEEE SSCI)

作者： Abedi, Mehdi Paam, Parichehr Berretta, Regina Univ Newcastle Sch Elect Engn & Comp Newcastle NSW Australia

ISBN: (纸本)9781728125473

This paper proposes a heuristic method for inventory optimisation of agri-fresh food products. The problem consists of multiple varieties of agri-fresh products collected in the harvest season that must be stored in a limited number of warehouses to supply demand throughout the whole planning horizon. The warehouses can be set on two modes with different energy consumption rates and different impacts on preventing product losses. The aim is to minimise the costs of energy consumption and product loss. Based on a mixed integer linear programming model for the problem, which is effective only for small instances due to the complexity of the problem, we propose an efficient two-phase heuristic method. In the first phase, a problem-specific heuristic determines and fixes the values of the binary variables, and then, in the second phase, the mixed integer linear programming problem is solved to determine the remaining variables. We evaluated the performance of the proposed approach by solving instances with different sizes. The results illustrate that the two-phase approach can efficiently find solutions of good quality.

关键词： Inventory optimisation fresh food supply chain heuristic integer linear programming problem

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