In this paper, we consider the task of discovering the common objects in images. Initially, object candidates are generated in each image and an undirected weighted graph is constructed over all the candidates. Each c...
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ISBN:
(数字)9783030140854
ISBN:
(纸本)9783030140854;9783030140847
In this paper, we consider the task of discovering the common objects in images. Initially, object candidates are generated in each image and an undirected weighted graph is constructed over all the candidates. Each candidate serves as a node in the graph while the weight of the edge describes the similarity between the corresponding pair of candidates. The problem is then expressed as a search for the Maximum Weight Clique (MWC) in this graph. The MWC corresponds to a set of object candidates sharing maximal mutual similarity, and each node in the MWC represents a discovered common object across the images. Since the problem of finding the MWC is NP-hard, most research of the MWC problem focuses on developing various heuristics for finding good cliques within a reasonable time limit. We utilize a recently very popular class of heuristics called localsearch methods. They search for the MWC directly in the discrete domain of the solution space. The proposed approach is evaluated on the PASCAL VOC image dataset and the YouTube-Objects video dataset, and it demonstrates superior performance over recent state-of-the-art approaches.
Balancing diversity and convergence seems to be a difficult task when solving multi-objective optimization problems (MOPs). For addressing this issue, researchers’ interest has been drawn to hybrid approaches since t...
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Balancing diversity and convergence seems to be a difficult task when solving multi-objective optimization problems (MOPs). For addressing this issue, researchers’ interest has been drawn to hybrid approaches since this cooperation allows benefiting from the advantages of both approaches and gains better trade-offs overall. Considering such fact, this paper aims at introducing a hybrid approach as a synergy of a multi-directional Ant Colony Optimization algorithm with a localsearch method based on a weighted version of epsilon Indicator using a self-adaptive neighborhood operator coined as Indicator Weighted Based localsearch with Ant Colony Optimization (IWBLS/ACO) to handle the knapsack problem within the multi-objective framework. In IWBLS/ACO, initial solutions are created by the ant colony. Then, the enhancement phase is ensured by the localsearch procedure. The algorithm is evolving based on different configurations of the epsilon quality indicator through different weight vectors. Moreover, we propose in this work, a novel self-adaptive neighborhood operator which changes automatically and dynamically as the IWBLS algorithm runs. The proposed IWBLS/ACO was tested on widely used Multi-objective Multidimensional Knapsack Problem (MOMKP) instances and compared with powerful state-of-the-art algorithms. Experimental results highlight that the proposed approach can lead to finding a good compromise between exploration and exploitation.
establishment of communications in disaster scenarios is of paramount importance, especially because preexisting communication infrastructure is likely to be destroyed or malfunctioning. Consequently, there is a need ...
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establishment of communications in disaster scenarios is of paramount importance, especially because preexisting communication infrastructure is likely to be destroyed or malfunctioning. Consequently, there is a need for an alternative and self-organizing communication infrastructure that can be rapidly deployed in disaster situations. In this paper, we propose to use drones or unmanned aerial vehicles as 0th responders to form a network that provides communication services to victims. Finding the best positions of the 0th responders is a non-trivial problem and is, therefore, divided into two phases. The first phase is the initial deployment, where the 0th responders are placed using partial information on the disaster scenario. In the second phase, which we call the adaptation to real conditions, the drones move according to a local search algorithm to find positions that provide better coverage to the victims. We conduct extensive simulations to validate our proposed approach for rural disaster scenarios under different conditions. We show that our proposed initial deployment based on genetic algorithm provides coverage for up to 94% (maximum) and 86% (mean) of victims if complete knowledge of the disaster scenario is known and 10 drones are used. When the adaptation to the real condition phase is used, this percentage is increased to 95% (maximum). If no knowledge of the scenario and 10 UAVs are used 80% (maximum) and 59% (mean) of victims are found and successfully covered. The proposed approach outperforms in 6.4% the random deployment method, and in 2.4% the best grid deployment approach. Finally, we show that by using different numbers of drones for the two phases of the proposed approach, the percentage of victims is increased up to 51% for low values of knowledge of the scenario. (C) 2018 Elsevier B.V. All rights reserved.
Constant stress accelerated degradation tests (CSADT) are widely used in life perdition for highly reliable products to infer the lifetime distribution under operating conditions. Optimal design of an CSADT can improv...
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Constant stress accelerated degradation tests (CSADT) are widely used in life perdition for highly reliable products to infer the lifetime distribution under operating conditions. Optimal design of an CSADT can improve life prediction accuracy and reduce test costs significantly. In the literature of CSADT design, most approaches focus on how to determine the sample allocation scheme, inspection frequency and test duration, but the issue of how to optimize the stress levels is seldom considered. In this work, we propose a novel method to optimize the CSADT considering both stress levels selection and samples allocation. First, an accelerated degradation model based on the Wiener process is used to model the degradation data. Next, under the constraint of sample size, a local-search based iterative algorithm is proposed to optimize parameters including stress levels and sample number under each level so as to obtain an accurate estimate of the distribution statistics. Finally, a case study of lithium-ion batteries is presented to validate the proposed method.
Train delays occur often in daily railway operations due to a variety of initiating incidents. On a heavily loaded mainline railway, a single train delay may lead to a series of secondary delays across the network. In...
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Train delays occur often in daily railway operations due to a variety of initiating incidents. On a heavily loaded mainline railway, a single train delay may lead to a series of secondary delays across the network. In this study, the authors describe a peer-to-peer system to solve train rescheduling problems in railway network bottlenecks. A designed Genetic algorithm is chosen as the local search algorithm on each side. Based on the local search algorithm, different negotiation protocols are raised to find globally feasible solutions. The proposed approach is tested in a railway bottleneck section in the UK, and the computational result is compared with a centralised method to show its performance in terms of computation time and optimality.
We present an in-depth computational study of two localsearch metaheuristics for the classical uncapacitated facility location problem. We investigate four problem instance models, studied for the same problem size, ...
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local search algorithms are widely adopted in solving large-scale Distributed Constraint Optimization Problems (DCOPs). However, since each agent always makes its value decision based on the values of its neighbors in...
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ISBN:
(纸本)9781510855076
local search algorithms are widely adopted in solving large-scale Distributed Constraint Optimization Problems (DCOPs). However, since each agent always makes its value decision based on the values of its neighbors in localsearch, those algorithms usually suffer from local premature convergence. More concretely, an agent cannot make a wise decision with poor values of its neighbors since its decision space is bound up with those poor values. In this paper, we propose a Partial Decision Scheme (PDS) to relax the decision space of an agent by ignoring the value of its neighbor which has the bad impact on its local benefits. The PDS comprises two partial decision processes: trigger partial decision and recursive partial decision. The former is iteratively performed by agents who cannot enhance their local benefits unilaterally to break out of potential local optima. The latter is recursively performed by neglected agents to improve global benefits. Besides, the trigger conditions along with a self-adaptive probability are introduced to control the use of PDS. The PDS can be easily applied to any local search algorithm to overcome its local premature convergence with a small additional overhead. In our theoretical analysis, we prove the feasibility and convergence of PDS. Moreover, the experimental results also demonstrate the superiority of the use of PDS in the typical local search algorithms over state-of-the-art local search algorithms.
The Boolean satisfiability problem, abbreviated as SAT, is the backbone of many applications in VLSI design automation and verification. Over the years, many SAT solvers, both complete and incomplete, have been develo...
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The Boolean satisfiability problem, abbreviated as SAT, is the backbone of many applications in VLSI design automation and verification. Over the years, many SAT solvers, both complete and incomplete, have been developed. Complete solvers are usually based on the DPLL (Davis–Putnam–Logemann–Loveland) algorithm, which is a backtracking algorithm. Industrial strength problems are very large and make DPLL based solvers impractical for some applications. In such cases, local search algorithms that try to find a solution within a stipulated time can be used. These algorithms look at SAT problem as an optimization problem. They start with an initial random solution and explore a certain search space by iteratively making local changes to the solution using a greedy, heuristic algorithm to find a global optimum. Over the past few years, heterogeneous devices such as Graphics Processing Units (GPU) and Field Programmable Gate Arrays (FPGA) have been used to accelerate the SAT problem and handle large SAT instances. There has been a growing interest in exploiting the parallel and pipeline processing power of FPGAs for various applications. New process technologies have allowed for more logic blocks, memory elements, and faster FPGAs, making it a perfect candidate for parallel computing. This thesis presents a local search algorithm Walksat, implemented on the Xilinx Alveo U250 Accelerator card. The entire solver has been developed using the OpenCL framework. On-chip memory available on the FPGA has been exploited to a great extent and the solver can handle SAT problems of up to 98,000 variables and 401,800 clauses. We have also analyzed the performance of our solver against the state of the art complete and incomplete solvers.
The Traveling Salesman Problem (TSP) is easy to qualify and describe but difficult and very hard to be solved. There is known algorithm that can solve it and find the ideal outcome in polynomial time, so it is NP-Comp...
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The Traveling Salesman Problem (TSP) is easy to qualify and describe but difficult and very hard to be solved. There is known algorithm that can solve it and find the ideal outcome in polynomial time, so it is NP-Complete problem. The Traveling Salesman Problem (TSP) is related to many others problems because the techniques used to solve it can be easily used to solve other hard Optimization problems, which allows of circulating it results on many other optimization problems. Many techniques were proposed and developed to solve such problems, including Genetic algorithms. The aim of the paper is to improve and enhance the performance of genetic algorithms to solve the Traveling Salesman Problem (TSP) by proposing and developing a new Crossover mechanism and a local search algorithm called the search for Neighboring Solution algorithm, with the goal of producing a better solution in a shorter period of time and fewer generations. The results of this study for a number of different size standard benchmarks of TSP show that the proposed algorithms that use Crossover proposed mechanism can find the optimum solution for many of these TSP benchmarks by (100%), and within the rate (96%-99%) of the optimal solution to some for others. The comparison between the proposed Crossover mechanism and other known Crossover mechanisms show that it improves the quality of the solutions. The proposed local search algorithm and Crossover mechanism produce superior results compared to previously propose local search algorithms and Crossover mechanisms. They produce near optimum solutions in less time and fewer generations.
This paper introduces a near-optimal path planning for industrial robot for multiple point tasks. For instance, spot welding, drilling, screwing and inspection with camera are popular multiple point work for industria...
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ISBN:
(数字)9781728134581
ISBN:
(纸本)9781728134581
This paper introduces a near-optimal path planning for industrial robot for multiple point tasks. For instance, spot welding, drilling, screwing and inspection with camera are popular multiple point work for industrial robots. How to decide the sequence of robot motions is important issue for factory automation because it directory influences to system productivity. Though getting optimal tour is not easy because this is kind of Traveling Salesman Problem (TSP) that is almost impossible to solve in polynomial time. In TSP the cost between two cities is Oven by geometrical distance though in robotics time for moving between two task points is gets cost. This article adopts heuristic algorithm that is often used to solve TSP to solve about 50 task points path planning for industrial robot. As a result, the algorithm gives under PA gap solution against best known solutions. For actual robot tasks, it generates about 6 to 10% efficient results compared with human task planner's path.
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