In order to reduce the loss and improve the operating efficiency, it is necessary to optimize the operating schedule for the sources, grids and loads of active distribution network (ADN). Firstly, an operation model i...
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ISBN:
(纸本)9781538660058
In order to reduce the loss and improve the operating efficiency, it is necessary to optimize the operating schedule for the sources, grids and loads of active distribution network (ADN). Firstly, an operation model is established for source-grid-load interactive operation of ADN. In this model, the minimum loss is treated as the objective function, and the distributed generation sources, the tie-line switches of the grid, and the controllable loads serve as the optimized variables. Considering that the established model is about mix-integer nonlinear programming (MINTY) problem, the model is transformed into a bi-level combinatorialoptimization problem to simplify the solving process. Finally, numerical tests are performed on the IEEE 33-node distribution network system, and results show that the proposed optimization method for the source-grid-load interactive operation of ADN can reduce the power loss and raise the operational efficiency.
In the k-terminal cut problem, we are given a graph with edge weights and k distinct vertices called "terminals." the goal is to remove a minimum weight collection of edges from the graph such that there is ...
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ISBN:
(纸本)9783030046514;9783030046507
In the k-terminal cut problem, we are given a graph with edge weights and k distinct vertices called "terminals." the goal is to remove a minimum weight collection of edges from the graph such that there is no path between any pair of terminals. the k-terminal cut problem is NP-hard. the k-terminal cut problem has been extensively studied and a number of algorithms have been devised for it. Most of the algorithms devised for the problem are approximation algorithms or heuristic algorithms. there are also fixed-parameter tractable algorithms that solve the problem optimally in time that is polynomial when the value of the optimum is fixed, but none have been shown empirically practical. It is possible to apply implicit enumeration using any integerprogramming formulation of the problem and solve it with a branch-and-bound algorithm. Here, we present a branch-and-bound algorithm for the k-terminal cut problem which does not rely on an integerprogramming formulation. Our algorithm employs "isolating cuts" and, for this reason, we call our branch-and-bound algorithm Isolation Branching. In an empirical experiment, we compare the performance of the Isolation Branching algorithm to that of a branch-and-bound applied to the strongest known integerprogramming formulation of k-terminal cut. the integerprogramming branch-and-bound procedure is implemented with Gurobi, a commercial mixed-integerprogramming solver. We compare the performance of the two approaches for real-world instances and synthetic data. the results on real data indicate that Isolation Branching, coded in Python, runs an order of magnitude faster than Gurobi for problems of sizes of up to tens of thousands of vertices and hundreds of thousands of edges. Our results on synthetic data also indicate that Isolation Branching scales more effectively. though we primarily focus on creating a practical tool for k-terminal cut, as a byproduct of our algorithm we prove that the complexity of Isolation Branching i
Despite the existence of efficient solution methods for bin packing problems, in practice these seldom occur in such a pure form but feature instead various considerations such as pairwise conflicts or profits between...
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ISBN:
(纸本)9783319930312;9783319930305
Despite the existence of efficient solution methods for bin packing problems, in practice these seldom occur in such a pure form but feature instead various considerations such as pairwise conflicts or profits between items, or aiming for balanced loads amongst the bins. the Wedding Seating Problem is a combinatorialoptimization problem incorporating elements of bin packing with conflicts, bin packing with profits, and load balancing. We use this representative problem to present and compare constraint programming, integerprogramming, and met aheuristic approaches.
Vehicle Routing Problem (VRP) is an important element of many logistic systems which involve routing and scheduling of vehicles from a depot to a set of customers node. this is a hard combinatorialoptimization proble...
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Vehicle Routing Problem (VRP) is an important element of many logistic systems which involve routing and scheduling of vehicles from a depot to a set of customers node. this is a hard combinatorialoptimization problem withthe objective to find an optimal set of routes used by a fleet of vehicles to serve the demands a set of customers It is required that these vehicles return to the depot after serving customers' demand. the problem incorporates time windows, fleet and driver scheduling, pick-up and delivery in the planning horizon. the goal is to determine the scheduling of fleet and driver and routing policies of the vehicles. the objective is to minimize the overall costs of all routes over the planning horizon. We model the problem as a linear mixed integer program. We develop a combination of heuristics and exact method for solving the model.
We address a single machine scheduling problem arising in a last mile delivery setting for a food company. the same problem finds obvious applications also in the context of internal manufacturing logistics. A set of ...
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We address a single machine scheduling problem arising in a last mile delivery setting for a food company. the same problem finds obvious applications also in the context of internal manufacturing logistics. A set of food orders are placed by the customers and are to be fulfilled by the company. Each order comprises a delivery point and an ideal delivery time An order is considered on time if it is delivered within a certain given time interval around the ideal delivery time. All food is prepared in a single production facility (restaurant) and immediately carried to the customers by a single courier, who may dispatch one or two different orders in a single trip. Since late deliveries correspond to canceled orders and an economic loss for the company, it is of interest to schedule orders so that the number of late orders is minimized. We model the resulting decision problem as a special single machine scheduling problem and propose different mixed integer programs to solve it. their performance is assessed through a computational study on a set of test instances derived by our real-world application. (C) 2019, IFAC (international Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.
this paper deals with a multi-core reconfigurable real-time system specified with a set of implementations, each of which is raised under a predefined condition and executes multiple functions which are in turns execu...
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ISBN:
(纸本)9789897583001
this paper deals with a multi-core reconfigurable real-time system specified with a set of implementations, each of which is raised under a predefined condition and executes multiple functions which are in turns executed by threads. the implementation as threads generates a complex system code. this is due to the huge number of threads and the redundancy between the different implementations which may lead to an increase in the energy consumption. thus we aim in this paper to optimize the system code by avoiding the redundancy between implementations and reducing the number of threads while meeting all related real-time constraints. the proposed approach adopts mixed integer linear programming (MILP) techniques in the exploration phase in order to provide a feasible task model. An optimal reconfigurable POSIX-based code of the system is manually generated as an output of this technique. An application to a case study and performance evaluation confirm and validate the expected results.
A subset selection problem from a finite set of items is considered, where a constraint is imposed on the cardinality of a selected subset. the subset selection problem is motivated by automated packaging systems, so-...
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ISBN:
(纸本)9781538626337
A subset selection problem from a finite set of items is considered, where a constraint is imposed on the cardinality of a selected subset. the subset selection problem is motivated by automated packaging systems, so-called multi-head weighers. Given a set of n items withtheir integral weights, a positive integer target weight t and a positive integer k, the subset selection problem asks to find a subset of the items so that the total weight of chosen items is no less than the target weight, and the number of the chosen items is exactly k, and further the total weight of them is as close to the target weight as possible. In this paper, an O(knt) time algorithm is presented to solve the subset selection problem. Numerical experiments are also conducted to demonstrate the performance of the pseudo-polynomial time algorithm on certain test instances having a feasible solution, and the results are reported.
Graph pebbling, as introduced by Chung, is a two-player game on a graph G. Player one distributes "pebbles" to vertices and designates a root vertex. Player two attempts to move a pebble to the root vertex v...
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ISBN:
(纸本)9783030046514;9783030046507
Graph pebbling, as introduced by Chung, is a two-player game on a graph G. Player one distributes "pebbles" to vertices and designates a root vertex. Player two attempts to move a pebble to the root vertex via a sequence of pebbling moves, in which two pebbles are removed from one vertex in order to place a single pebble on an adjacent vertex. the pebbling number of a simple graph G is the smallest number pi(G) such that if player one distributes pi(G) pebbles in any configuration, player two can always win. Computing pi(G) is provably difficult, and recent methods for bounding pi(G) have proved computationally intractable, even for moderately sized graphs. Graham conjectured that the pebbling number of the Cartesianproduct of two graphs G and H, denoted G square H, is no greater than pi(G)pi(H). Graham's conjecture has been verified for specific families of graphs;however, in general, the problem remains open. this study combines the focus of developing a computationally tractable method for generating good bounds on pi(G) square (H), withthe goal of providing evidence for (or disproving) Graham's conjecture. In particular, we present a novel integer-programming (IP) approach to bounding pi(G) square (H) that results in significantly smaller problem instances compared with existing IP approaches to graph pebbling. Our approach leads to a sizable improvement on the best known bound for pi(L) square (L), where L is the Lemke graph. L square L is among the smallest known potential counterexamples to Graham's conjecture.
the trippers are equipments often found in mineral processing plants. their role is to distribute ore coming from past stages of process in a silo with several hoppers. Positioning trippers is a scheduling problem def...
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To tackle the massive access and different computation offloading requirements of IoT devices in 5G MEC system, Dynamic User Pairing NOMA-based offloading is considered in this paper. An overall energy consumption min...
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To tackle the massive access and different computation offloading requirements of IoT devices in 5G MEC system, Dynamic User Pairing NOMA-based offloading is considered in this paper. An overall energy consumption minimization framework is established by joint optimizing user pairing, of-floading decision and uplink power control under the time and maximum multiplexing number of user constraints. Due to the combinatorial nature of the formulated mixed integer non-linear programming problem, we adapt two-phase approach to solve the challenging problem. First, a low-complexity heuristic algorithm is designed to solve the user pairing problem. After we get the sub-optimal user pairing scheme, the original problem is proved to be a convex problem, we then get the optimal offloading decision and transmission power of devices. Numerical results show that the proposed DUP NOMA-based offloading scheme can significantly improve system performance in terms of energy consumption comparing to OMA and Fixed User Pairing NOMA based offloading.
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