Nowadays, Ambient Backscatter Communication (AmBC) systems have emerged as a green communication technology to enable massive self-sustainable wireless networks by leveraging Radio Frequency (RF) Energy Harvesting (EH...
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Nowadays, Ambient Backscatter Communication (AmBC) systems have emerged as a green communication technology to enable massive self-sustainable wireless networks by leveraging Radio Frequency (RF) Energy Harvesting (EH) capability. A Full-duplex Ambient Backscatter Communication (FAmBC) network with a Full-duplex Access Point (AP), a dedicated Legacy User (LU), and several Backscatter Devices (BDs) is considered in this study. The AP with two antennas transfers downlink Orthogonal Frequency Division multiplexing (OFDM) information and energy to the dedicated LU and several BDs, respectively, while receiving uplink backscattered information from BDs at the same time. One of the key aims in AmBC networks is to ensure fairness among BDs. To address this, we propose the multi-objective Lexicographical optimizationproblem (MLOP), which aims to maximize the minimum BD's throughput while enhancing overall BDs' throughput, subject to the AP's subcarrier power, BDs' reflection coefficients, and backscatter time allocation. Owe to the MLOP is non-convex, we propose Difference Convex Algorithm (DCA) using Exterior Penalty Function Method (EPFM)-an inventive non-convex optimization method- to reach the optimal solution. The most critical advantage of applying this proposed approach is finding the globally optimal solution. The effectiveness of the proposed method supported by theoretical analysis confirms its superiority compared to some of the investigated suboptimal algorithms with the same computational complexity.
As a new-style stochastic algorithm, the electromagnetism-like mechanism(EM) method gains more and more attention from many researchers in recent years. A novel model based on EM(NMEM) for multiobjective optimizat...
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As a new-style stochastic algorithm, the electromagnetism-like mechanism(EM) method gains more and more attention from many researchers in recent years. A novel model based on EM(NMEM) for multiobjectiveoptimizationproblems is proposed, which regards the charge of all particles as the constraints in the current population and the measure of the uniformity of non-dominated solutions as the objective function. The charge of the particle is evaluated based on the dominated concept, and its magnitude determines the direction of a force between two particles. Numerical studies are carried out on six complex test functions and the experimental results demonstrate that the proposed NMEM algorithm is a very robust method for solving the multiobjectiveoptimizationproblems.
Seismic resistance and cost effectiveness are often two important building planning objectives for architects. However, these objectives nearly always share a negative correlation with each other, which can cause plan...
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Seismic resistance and cost effectiveness are often two important building planning objectives for architects. However, these objectives nearly always share a negative correlation with each other, which can cause planning delays and confusion. The conflict between these two is a multi-objective optimization problem (MOOP). Besides, building planning often encompasses both subjective and objective factors. However, most current efficiency evaluation methods focus on the latter and underemphasize the former. Current efficiency evaluation methods are thus not optimized for actual building planning needs. The aim of this study is to develop a new planning efficiency evaluation approach to resolve the above problems. Research methods include the indifference curve, efficient frontier and Data Envelopment Analysis (DEA). The indifference curve deduced the subjective planning preferences of architects;efficient frontier theory constructed the efficient frontier of school buildings;and DEA evaluated the efficiency of various building factors objectively. A total of 326 school buildings in Taichung City, Taiwan in an empirical study designed to illustrate proposed approach effectiveness. The results show that using only objective evaluation or subjective recognition is insufficient to explain the true nature of building planning. Findings can serve as benchmarks for inefficient school buildings at preliminary planning stage.
The short-term load forecast is an important part of power system operation, which is usually a nonlinear problem. The processing of load forecast data and the selection of forecasting methods are particularly importa...
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The short-term load forecast is an important part of power system operation, which is usually a nonlinear problem. The processing of load forecast data and the selection of forecasting methods are particularly important. In order to get accurate and effective prediction for power system load, this article proposes a hybrid multi-objective quantum particle swarm optimization (QPSO) algorithm for short-term load forecast of power system based on diagonal recursive neural network. Firstly, a multi-objective mathematical model for short-term load forecast is proposed. Secondly, the discrete particle swarm optimization (PSO) algorithm is used to select the characteristics of load data and screen out the appropriate data. Finally, the hybrid multi-objective QPSO algorithm is used to train diagonal recursive neural network. The experimental results show that the hybrid multi-objective QPSO for short-term load forecast based on diagonal recursive neural network is effective.
A new approach for an integrated optimum design of a structural control system is described in this paper. The method considers the structure and active control system as a combined or an integrated system, i.e. the s...
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A new approach for an integrated optimum design of a structural control system is described in this paper. The method considers the structure and active control system as a combined or an integrated system, i.e. the structural sizing variables, locations of controllers and the feedback control gain are both treated as design variables. The size of the structural members, the required control efforts and dynamic responses of the structure are considered as objective functions to be optimized. The simultaneous optimization of the structural control system is essentially formulated as a multi-objective optimization problem. To effectively address this problem, we propose a preference-based optimization model and a genetic algorithm is applied as a numerical searching technique. In the method, for each objective criterion, preference functions are defined that delineate degrees of desirability and optimum variables in both systems are simultaneously found through a preference-guided random searching process. As an example to verify the validity of the proposed approach, an earthquake-excited 10-story building is used and the numerical results are presented. (C) 2004 Elsevier Ltd. All rights reserved.
In this paper a new multi-objective clonal selection algorithm (theta-MCSA) is presented to solve multi-objectiveproblems with multimodal and non-continuous functions. The concept of clonal selection algorithm (CSA) ...
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In this paper a new multi-objective clonal selection algorithm (theta-MCSA) is presented to solve multi-objectiveproblems with multimodal and non-continuous functions. The concept of clonal selection algorithm (CSA) is based on the immune system and white blood cells behavior that select the antibodies similar to antigen for cloning. Although the clonal selection is a robust optimization method, however, as a shortcoming, it takes long time to find optimal Pareto front especially in problems with large search space. To overcome this problem, the proposed method replaces the large search space with the theta-search based on the phase angles. To avoid trapping into local optima in mutation step, two strong mutation methods are implemented according to the iteration number and algorithm efficiency. For converging to uniformly Pareto front in less iterations, the proposed multi-objective algorithm handles the size of the repository and a new population updating mechanism is iteratively applied to select the non-dominate, one-dominate and two-dominate solutions of prior iteration. The experimental results show the efficiency of the proposed theta-MCSA algorithm compared to other methods.
This paper deals with design for manufacturing (DFM) approach for additive manufacturing (AM) to investigate simultaneously the different attributes and criteria of design and manufacturing. The integrated design appr...
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This paper deals with design for manufacturing (DFM) approach for additive manufacturing (AM) to investigate simultaneously the different attributes and criteria of design and manufacturing. The integrated design approach is provided in the product definition level and it gradually maps the customer requirements to the final product model. The main contribution of this paper is an interface processing engine that is an interface between the product model and manufacturing model. This study uses the Skin-Skeleton approach to model the first definition of the product and model the material flow of AM technology as the manufacturing process. This engine is developed through analysis of all AM technologies and identification of their parameters, criteria, and drawbacks. In order to evaluate some product and process parameters, a multi-objectiveproblem is formulated based on the analysis of all AM technologies;production time and material mass are optimized regarding mechanical behavior of the material and roughness of product. The approach is validated by a case study through a bag hook example. From its requirement specification to the proposed approach, this article defines an optimized product and its manufacturing parameters for fused deposition modeling (FDM) technology.
This paper presents an optimization method to solve a multi-objective model of a bi-level linear programming problem with intuitionistic fuzzy coefficients. The idea is based on TOPSIS (technique for order preference ...
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This paper presents an optimization method to solve a multi-objective model of a bi-level linear programming problem with intuitionistic fuzzy coefficients. The idea is based on TOPSIS (technique for order preference by similarity to ideal solution) method. TOPSIS method is a multiple criteria method that identifies a satisfactory solution from a given set of alternatives based on the minimization of distance from an ideal point and maximization of distance from the nadir point simultaneously. A new model of multi-objective bi-level programming problem in an intuitionistic fuzzy environment has been considered. The problem is first reduced to a conventional multi-objective bi-level linear programming problem using accuracy function. Then the modified TOPSIS method is proposed to solve the problem at both the leader and the follower level where various linear/non-linear membership functions are used to represent the flexibility in the approach of decision-makers (DMs). The problem is solved hierarchically, i.e., first the problem at the leader level is solved and then the feasible region is extended by relaxing the decision variables controlled by the leader. The feasible region is extended to obtain a satisfactory solution for the DMs at both levels. Finally, the application of the proposed approach in the production planning of a company has been presented. An illustrative numerical example is also given to explain the methodology defined in this paper.
This study presents a compact dual-band dual-sense circularly polarized (CP) fragmental patch antenna that advanced by an improved simulated-annealing-based optimization algorithm. This design replaces truncated corne...
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This study presents a compact dual-band dual-sense circularly polarized (CP) fragmental patch antenna that advanced by an improved simulated-annealing-based optimization algorithm. This design replaces truncated corners of traditional truncated patch antennas with fragmental structures, generating dual-band dual-CP radiation with a small frequency ratio and a high front-to-back ratio. The proposed optimized framework tackles the multi-objective optimization problem through hierarchical optimization to achieve an optimal balance among various performance metrics. Furthermore, the simulated annealing is improved using a matrix-based dynamic step-size perturbation mechanism and a nested cyclic process, averting premature convergence and ensuring multifaceted objective enhancement. The measurement results reveal that the proposed antenna can operate with a small frequency ratio of 1.07, providing left-hand CP radiation from 4.99 to 5.02 GHz and right-hand CP radiation 5.34 to 5.41 GHz, respectively. This compact cost-efficient design demonstrates potential for diverse antenna applications.
Recently, many studies have been conducted on multi-objective Genetic Algorithm (MOGA), in which Genetic Algorithms are applied to multi-objective optimization problems (MOPs). Among various applications, MOGA is also...
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Recently, many studies have been conducted on multi-objective Genetic Algorithm (MOGA), in which Genetic Algorithms are applied to multi-objective optimization problems (MOPs). Among various applications, MOGA is also applied to engineering design problems, which require not only high-performance Pareto solutions to be obtained, but also an analysis of the obtained Pareto solutions and extraction of design knowledge about the problem itself. In order to analyze the Pareto solutions obtained by MOGA, it is necessary to consider the objective space and the design variable space. The aim of this study is to extract and analyze solutions of relevant interest to designers. In this paper, we propose three solutions to analyze and extract design knowledge from MOGA. (1) We define "Non-Correspondence in Spread" between the objective space and the design variable space. (2) We try to extract the Non-Correspondence area in Spread using the index defined in this paper. (3) We apply the defined index to genetic search to obtain Pareto solutions that have different design variables and similar fitness values. This paper applies the above index to the trajectory design optimizationproblem and extracts Non-Correspondence area in Spread from the obtained Pareto solutions. This paper also shows that robust Pareto solutions can be obtained using genetic search using the defined index.
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