network programming technique is developed to derive exact solutions or their lower (upper) bound estimates in multi-extremal (in particular, discrete) optimization problems. The idea of the technique lies in reducing...
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network programming technique is developed to derive exact solutions or their lower (upper) bound estimates in multi-extremal (in particular, discrete) optimization problems. The idea of the technique lies in reducing the problem to a superposition of simpler problems. The scheme of reduction is conveniently represented in the form of a network (referred to as network representation), with nodes being the subproblems that enter the superposition. Simple optimization problems are solved at each node, while the solution at the terminal node of the network yields the upper (lower) bound estimate for the initial problem. In the case of tree-shaped network representation, the solution at the terminal node of the network provides the exact solution to the initial optimization problem. This paper overviews application of the network programming technique to several problems of project management.
In this paper, a new approach for short-term unit commitment is proposed, The unit commitment problem is formulated as a network problem and solved by a network programming technique. The proposed algorithm has been t...
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In this paper, a new approach for short-term unit commitment is proposed, The unit commitment problem is formulated as a network problem and solved by a network programming technique. The proposed algorithm has been tested on a system of up to 61 units to be scheduled over 24 hours. Experimental results show that this algorithm can obtain a satisfactory solution in 46.51 seconds on a VAX 11/750 computer.
Sensors carried by moving objects in the cities can be used in various applications such as environmental monitoring, traffic control and recreational purposes. A mobile sensor network can be formed by sensors carried...
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Sensors carried by moving objects in the cities can be used in various applications such as environmental monitoring, traffic control and recreational purposes. A mobile sensor network can be formed by sensors carried by people or buses. In this paper, we will present a mobile sensor network programming system (MSNPS) that can program or reprogram such mobile sensor networks. The programming process is usually initiated by a user from the Internet. MSNPS uses a gateway protocol to bridge the Internet and sensor network, so that control and data messages can be exchanged between these two networks. MSNPS sends the program data to the targeted sensor platforms using a tree structure formed by control messages. We developed a prototype implementation, and analyzed MSNPS system performance. We also simulated the system in a mobile sensor network.
In wireless sensor networks, the necessity of network programming becomes more and more important due to the inaccessibility of the sensor nodes. Because the network programming produces a large amount of data, it con...
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In wireless sensor networks, the necessity of network programming becomes more and more important due to the inaccessibility of the sensor nodes. Because the network programming produces a large amount of data, it consumes a great deal of energy and causes the network to suffer from much interference. Many conventional studies regarding the network programming attempted to reduce the energy consumption and the interference effect. However, they overlook transmission power effect on the energy-efficiency and the interference problem. In this paper, we present a novel network programming protocol that controls the transmission power at each sender node in a distributed manner. The protocol deals not only with the energy consumption of individual sensor node but also the network load distribution. Moreover, it reduces the interference effect on the network by decreasing the average transmission power of the sensor nodes. We verify that our protocol extends the lifetime of the sensor network and decreases the packet losses through simulation results.
This paper presents a new decoupled model together with an very efficient coordination algorithm to solve a hydrothermal optimal power flow (HTOPF) problem over a certain time horizon. Based on the Lagrange relaxation...
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This paper presents a new decoupled model together with an very efficient coordination algorithm to solve a hydrothermal optimal power flow (HTOPF) problem over a certain time horizon. Based on the Lagrange relaxation at the level of the KKT conditions of the primal problem, the HTOPF is decomposed into thermal plant subproblems formulated as OFF and hydroplant subproblems. To solve efficiently the thermal OFF subproblems, the warm-starting scheme has been incorporated into interior point quadratic programming (IPQP). As to the hydroplant subproblems, a united network flow model is presented in which a fixed head plant is treated as a special case of a variable head plant. The hydroplant subproblem can be formulated as a minimum-cost maximum-now problem for which unit cost functions of hydroplants are defined exactly. A proposed variant of the partitioning shortest path algorithm has brought about a great speed up in the computation of the subproblems. The validity of the proposed method has been examined by solving the IEEE test systems and a Chinese power system consisting of 13 thermal plants and 12 hydro power plants;the last system is a large size problem such that it has 107,712 primal and dual variables. Simulation results obtained are quire convincing.
In this paper, we present a mathematical model for cyclic and non-cyclic scheduling of 12 h shift nurses. The model exploits the fact that a nurse's schedule is made up of an alternating sequence of work-stretch a...
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In this paper, we present a mathematical model for cyclic and non-cyclic scheduling of 12 h shift nurses. The model exploits the fact that a nurse's schedule is made up of an alternating sequence of work-stretch and 'off-stretch patterns. We introduce a concept called a stint, which is a pattern characterized by a start date, a length, a 'cost' and the shifts worked. Using the stints as nodes in a network, we construct an acyclic graph on which the nurse's schedules can be defined. The resulting model is essentially a shortest-path problem with side constraints. The model is quite flexible and can accommodate a variety of constraints. With a minor modification, the network is used to define both the cyclic and non-cyclic scheduling problems. The models are illustrated on sample data from a local hospital and solved using CPLEX optimization software on an IBM RISC6000/330 workstation. (C) 1998 Elsevier Science B.V.
Phase unwrapping is the reconstruction of a function on a grid given its values mod 2 pi, Phase unwrapping is a key problem in all quantitative applications of synthetic aperture radar (SAR) interferometry, but also i...
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Phase unwrapping is the reconstruction of a function on a grid given its values mod 2 pi, Phase unwrapping is a key problem in all quantitative applications of synthetic aperture radar (SAR) interferometry, but also in other fields. A new phase unwrapping method, which is a different approach from existing techniques, Is described and tested. The method starts from the fact that the phase differences of neighboring pixels can be estimated with a potential error that is an integer multiple of 2 pi. This suggests the formulation of the phase unwrapping problem as a global minimization problem with integer variables. Recognizing the network structure underlying the problem makes for an efficient solution, In fact, it is possible to equate the phase unwrapping problem to the problem of finding the minimum cost flow on a network, for the solution of which there exist very efficient techniques. The tests performed on real and simulated interferometric SAR data confirm the validity of our approach.
Two examples of parametric cost programming problems—one in network programming and one in NP-hard 0-1 programming—are given; in each case, the number of breakpoints in the optimal cost curve is exponential in the s...
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Two examples of parametric cost programming problems—one in network programming and one in NP-hard 0-1 programming—are given; in each case, the number of breakpoints in the optimal cost curve is exponential in the square root of the number of variables in the problem.
The network programming model of SRv6 allows the creation of network programs that can be enforced over traffic flows entering a Segment Routing (SR) domain. A network program is a list of instructions that must be ap...
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ISBN:
(纸本)9781665406017
The network programming model of SRv6 allows the creation of network programs that can be enforced over traffic flows entering a Segment Routing (SR) domain. A network program is a list of instructions that must be applied on a packet traversing the SR domain. Instructions, also known as behaviors, currently available in SRv6 are divided into two main categories: i) topological (e.g., send the packet over the shortest path), and ii) service based (e.g., duplicate the packet). In this paper we introduce a new behavior for the SRv6 network programming model, named maximize Throughput (max_T). This function allows to steer an incoming traffic flow toward the egress node over the path that currently guarantees the highest throughput for the flow. The proposed max_T behavior has been implemented over programmable switches, and its effectiveness in improving the performance experienced by flows asking for its application is evaluated through experiments performed over an emulated environment. The preliminary result shows that a 23% reduction of the transfer time for a file over the SR domain is achieved when the max_T behavior is used.
Using SDN to configure and control a multi-site network involves writing code that handles low-level details. We describe preliminary work on a framework that takes a network description and set of policies as input, ...
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ISBN:
(纸本)9781538647905
Using SDN to configure and control a multi-site network involves writing code that handles low-level details. We describe preliminary work on a framework that takes a network description and set of policies as input, and handles all the details of deriving routes and installing flow rules in switches. The paper describes key software components and reports preliminary results.
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