In order to provide to his patients a quality medical service at lower cost, the General Administration Department of a University Hospital wants to maintain the number of the allocated nurses as low as possible while...
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In order to provide to his patients a quality medical service at lower cost, the General Administration Department of a University Hospital wants to maintain the number of the allocated nurses as low as possible while guaranteeing a satisfying level of health care. The nurses' redeployment is an optimization problem that falls under the category of integer linear programming problems whose graphical model is a digraph. The mathematical model is composed of an objective function of several interdependent variables to be obtained and some equality and side constraints that the General Administration Department should not violate in order to achieve satisfaction. The solution of this kind of problems rests on the use of an iterative method known as the simplex algorithm.
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-car...
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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 integerlinearprogramming (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.
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 t...
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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.
Recent studies show that most of the licensed bands are under-utilized at certain time and location. The emergence of cognitive radio made it possible for nodes to use licensed channels, as well as unlicensed ones for...
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ISBN:
(纸本)9781457702518
Recent studies show that most of the licensed bands are under-utilized at certain time and location. The emergence of cognitive radio made it possible for nodes to use licensed channels, as well as unlicensed ones for data transmission provided that there is no licensed user active simultaneously. This leads to a new challenge, where nodes need efficient mechanisms to sense the spectrum bands and identify the spectrum holes. Based on this information, nodes will pick the best channel among all available channels, while maintaining the priority of licensed users and minimizing the network interference at the same time. By formulating the problem as an integerlinearprogramming (ILP) problem, we try to minimize the network interference in different scenarios, assuming nodes are equipped with cognitive radios and they are able to use licensed bands when appropriate.
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 s...
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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.
Energy-efficient optical networks are gaining momentum as environmental-friendly solutions with reduced operational costs. Energy-efficiency can be achieved by using devices in sleep mode, i.e., a low-power, inactive ...
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ISBN:
(纸本)9781424456383
Energy-efficient optical networks are gaining momentum as environmental-friendly solutions with reduced operational costs. Energy-efficiency can be achieved by using devices in sleep mode, i.e., a low-power, inactive state in which devices can be suddenly waken-up upon occurrence of triggering events. This paper advocates a sleep mode option for the optical devices (e. g., amplifiers, optical switches) installed for protection purposes only. These devices can be put in sleep mode to reduce the network power consumption, but they can be promptly waken up (if necessary) upon a failure occurrence. This principle is proposed and applied in Wavelength Division Multiplexing (WDM) networks with dedicated-path protection to ensure survivability against single-link failures. The main contribution of the paper is the definition of the energy-efficient network planning problem for resilient WDM networks where optical devices can be configured in sleep mode. Optimal results of the integerlinearprogramming (ILP) problem show savings of up to 25% in the overall power consumption.
In this paper, we consider the coordinated spectrum access problem in a multiuser single-transceiver cognitive radio network (CRN). Our objective is to maximize the sum-rate achieved by all contending cognitive radio ...
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ISBN:
(纸本)9781424456383
In this paper, we consider the coordinated spectrum access problem in a multiuser single-transceiver cognitive radio network (CRN). Our objective is to maximize the sum-rate achieved by all contending cognitive radio users with respect to both spectrum assignment and transmission rate. The problem is posed as a rate-maximization problem subject to hardware and interference constraints. Specifically, we show that this problem can be formulated as an integer linear programming problem (ILP) with unimodular constraint matrix, which can be optimally solved in polynomial time using linearprogramming. Unlike previous research, our formulation is not restricted to the information-theoretic capacity, and can be applied to any arbitrarily given rate-SINR function. We also develop a distributed CSMA/CA-based MAC protocol for CRNs to realize the optimal assignment in a distributed manner. Simulation results indicate that compared to a reference CSMA/CA CRN MAC protocol, the proposed protocol significantly improves network throughput and preserves fairness.
With the move to deep submicron processes, the design-productivity gap has continued to widen for RTL-based design methodologies. High-level synthesis has been touted as a solution to the design-productivity gap by al...
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ISBN:
(纸本)9781424481927
With the move to deep submicron processes, the design-productivity gap has continued to widen for RTL-based design methodologies. High-level synthesis has been touted as a solution to the design-productivity gap by allowing designers to move up to a higher level of abstraction where they focus on the functionality of the circuit instead of the low level details. However, at the same time, the move to deep submicron processes has led to increased levels of process variation, which must be considered during synthesis so that the performance yield of the circuit meets design specifications. In this paper, we tackle the problem of performance yield optimization during the scheduling task of high-level synthesis. We formulate the problem of performance yield optimization for scheduling as an integer linear programming problem (ILP) and offer the following contributions: 1) a totally unimodular ILP formulation for performance yield maximization and 2) a variation-aware and layout-driven iterative algorithm for performance yield improvement. Experimental results show that we can obtain significant gain in performance yield compared to a state-of-the-art variation-aware high-level synthesis tool FastYield.
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 c...
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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 integerlinearprogramming (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.
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 t...
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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.
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