Measuring the power consumption of individual household appliance is an essential task for home energy management and demand response programmes. To this end, this article proposes a simple yet effective, two-stage no...
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Measuring the power consumption of individual household appliance is an essential task for home energy management and demand response programmes. To this end, this article proposes a simple yet effective, two-stage nonintrusive appliance load monitoring scheme. A standard deviation based automatic state detection algorithm is developed in stage-1, which results in the information about states and the transient spans of individual appliances. In stage-2 of the proposal, a penalty-based enhanced integer programming (IP) based load disaggregation method is proposed. The efficacy of the proposed method is initially verified with the reference energy disaggregation data dataset and, then, tested on an actual residential house. Various test results reveal that the proposed enhanced IP-based method is an effective and less complex solution to load disaggregation problem.
In order to improve the energy efficiency of urban rail transit system, it is necessary to figure out the key factor(s) that restrain(s) train rapidity and energy conservation and understand the inner complex relation...
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In order to improve the energy efficiency of urban rail transit system, it is necessary to figure out the key factor(s) that restrain(s) train rapidity and energy conservation and understand the inner complex relationships among them. We first define energy-saving and rapid train control/operation, then simulate and analyze the microscopic train behavior between two successive stations. The result reflects that due to the constraint of the short inter-station distance, the train has no space and time to take advantage of its excellent performance in speed and has to stop frequently at every station, which leads to the increase of energy consumption and the prolongation of running time. Based on the above energy consumption analysis of the microscopic train behavior, a hierarchical Pareto 0-1 integer programming with consideration of passenger flow distribution and public transport characteristics is presented to organically integrate microscopic train control with macroscopic train organization. The case study shows that the presented method can greatly promote the energy-efficient and rapid train operation of urban rail transit system. This study is also helpful to the planning and construction of future cities and urban rail transit systems.
Binding audiovisual content into multimedia applications requires the specification of each media item, including its size and position, to define a screen layout. The multimedia application author must plan the appli...
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Binding audiovisual content into multimedia applications requires the specification of each media item, including its size and position, to define a screen layout. The multimedia application author must plan the application's screen layout (ASL), considering a variety of screen sizes where the application shall be executed. An ASL that maximizes the area occupied by media items on the screen is essential, given that screen space is a valuable asset for media broadcasters. In this paper, we introduce the Application Screen Layout Optimization Problem, and present its NP-hardness. Besides, two integer programming formulations and an Iterated Local Search (ILS) metaheuristic are proposed to solve it. The efficiency of the proposed methods is evaluated, showing that the metaheuristic achieves better results and is at least 12 times faster, on average, than the mathematical formulations. Also, the proposed approaches were compared to a layout design algorithm, showing their effectiveness.
In this thesis, we study the role of cutting planes in reducing the size of the branch-and-bound tree for integer programs. Cutting planes are traditionally used to tighten relaxations of the problem by excluding frac...
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In this thesis, we study the role of cutting planes in reducing the size of the branch-and-bound tree for integer programs. Cutting planes are traditionally used to tighten relaxations of the problem by excluding fractional solutions, which leads to improving the dual bounds. In this research, we study a fundamentally different role of cutting planes that target excluding integer infeasible partial solutions, which leads to improving consistency of the set. Consistency helps to reduce backtracking, thereby reducing the size of the search tree. We investigate the connections between consistency and convex hull, and design a cutting plane framework to achieve consistency. One of the practical challenges in incorporating cutting planes inside of branch-and-bound is the running time required to solve a cut-generating problem. To address this difficulty, we design a function approximation framework to find an estimate for the cut-generating functions. We use machine learning methods that provide a classifier for the binary outcome of the indicator function representing the cut-generating oracle. Computational experiments conducted show significant time improvement as well as size reduction of B&B tree for the proposed approach compared to traditional techniques.
This study aims to find the optimal vertiport design based on the geometry of the candidate site in terms of maximizing the capacity and net profit of the vertiport operator. This study presents a vertiport design pro...
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Given a graph G = (V, E) , the b-coloring problem consists in attributing a color to every vertex in V such that adjacent vertices receive different colors, every color has a b-vertex, and the number of colors is maxi...
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Given a graph G = (V, E) , the b-coloring problem consists in attributing a color to every vertex in V such that adjacent vertices receive different colors, every color has a b-vertex, and the number of colors is maximized. A b-vertex is a vertex adjacent to vertices colored with all used colors but its own. The b- coloring problem is known to be NP-Hard and its optimal solution determines the b-chromatic number of G, denoted X-b(G). This paper presents an integer programming formulation and a very effective multi-greedy randomized heuristic which can be used in a multi-start metaheuristic. In addition, a matheuris-tic approach is proposed combining the multi-start multi-greedy randomized metaheuristic with a MIP (mixed integer programming) based local search procedure using the integer programming formulation. Computational experiments establish the proposed multi-start metaheuristic as very effective in generating high quality solutions, along with the matheuristic approach successfully improving several of those results. Moreover, the computational results show that the multi-start metaheuristic outperforms a state-of-the-art hybrid evolutionary metaheuristic for a subset of the large instances which were previously considered in the literature. An additional contribution of this work is the proposal of a benchmark in-stance set, which consists of newly generated instances as well as others available in the literature for classical graph problems, with the aim of standardizing computational comparisons of approaches for the b-coloring problem in future works. (C) 2021 Elsevier B.V. All rights reserved.
In this work we present modeling and optimally solving a timetabling problem that was given as a compulsory assignment to students attending an Operations Research course. The project aimed at introducing integer Prog...
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Real-world networks are often extremely polarized because the communication between different groups of vertices can be weak and, most of the time, only vertices within the same group or sharing the same beliefs commu...
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Real-world networks are often extremely polarized because the communication between different groups of vertices can be weak and, most of the time, only vertices within the same group or sharing the same beliefs communicate to each other. In this work, we introduce the minimum-cardinality edge addition problem (MinCEAP) as a strategy for reducing polarization in real-world networks based on a principle of minimum external interventions. We present the problem formulation and discuss its complexity, showing that its decision version is NP-complete. We also propose three integer programming formulations for the problem and discuss computational results on artificially generated and real-life instances. Randomly generated instances with up to 1000 vertices are solved to optimality. On the real-life instances, we show that polarization can be reduced to the desired threshold with the addition of a few edges. The minimum intervention principle and the methods developed in this work are shown to constitute an effective strategy for tackling polarization issues in practice in social, interaction, and communication networks, which is a relevant problem in a world characterized by extreme political and ideological polarization.
The Graphical Traveling Salesperson Problem is the problem of assigning, for a given weighted graph, a nonnegative number x(e) to each edge e such that the induced multi-subgraph is of minimum weight among those that ...
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The Graphical Traveling Salesperson Problem is the problem of assigning, for a given weighted graph, a nonnegative number x(e) to each edge e such that the induced multi-subgraph is of minimum weight among those that are spanning, connected and Eulerian. Known MIP formulations are based on integer variables x(e). Carr and Simonetti (IPCO 2021) showed that unless NP = coNP, no (reasonable) formulation can have integrality constraints only on x-variables, a challenge posed by Denis Naddef. We establish the same result unconditionally. (C) 2021 Published by Elsevier B.V.
Counterpoint is a theory for composing western polyphonic music. It consists of many rules that regulate melodic and harmonic relationships within each voice or between voices. Because satisfying all of the rules is d...
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