Multi objective optimization

多目标优化
  • 文章类型: Journal Article
    本研究引入了多目标肝癌算法(MOLCA),一种受肝脏肿瘤生长和增殖模式启发的新方法。MOLCA模仿肝脏肿瘤的进化趋势,利用它们的扩展动力学作为解决工程设计中的多目标优化问题的模型。该算法独特地将遗传算子与随机基于对立的学习(ROBL)策略相结合,优化本地和全局搜索功能。通过整合精英非主导排序(NDS),进一步增强信息反馈机制(IFM)和拥挤距离(CD)选择方法,它们的共同目标是有效地识别帕累托最优前沿。MOLCA的性能使用一套全面的标准多目标测试基准进行严格评估,包括ZDT,DTLZ和各种约束(CONSTR,TNK,SRN,BNH,OSY和KITA)和实际工程设计问题,例如无刷直流轮毂电机,安全隔离变压器,螺旋弹簧,双杆桁架和焊接梁。它的功效以突出的算法为基准,例如非主导排序灰狼优化器(NSGWO),多目标多逆优化(MOMVO),非支配排序遗传算法(NSGA-II),基于分解的多目标进化算法(MOEA/D)和多目标海洋捕食者算法(MOMPA)。使用GD进行定量分析,IGD,SP,SD,表示收敛和分布的HV和RT指标,而定性方面是通过帕累托战线的图形表示来呈现的。MOLCA源代码可在以下网址获得:https://github.com/kanak02/MOLCA。
    This research introduces the Multi-Objective Liver Cancer Algorithm (MOLCA), a novel approach inspired by the growth and proliferation patterns of liver tumors. MOLCA emulates the evolutionary tendencies of liver tumors, leveraging their expansion dynamics as a model for solving multi-objective optimization problems in engineering design. The algorithm uniquely combines genetic operators with the Random Opposition-Based Learning (ROBL) strategy, optimizing both local and global search capabilities. Further enhancement is achieved through the integration of elitist non-dominated sorting (NDS), information feedback mechanism (IFM) and Crowding Distance (CD) selection method, which collectively aim to efficiently identify the Pareto optimal front. The performance of MOLCA is rigorously assessed using a comprehensive set of standard multi-objective test benchmarks, including ZDT, DTLZ and various Constraint (CONSTR, TNK, SRN, BNH, OSY and KITA) and real-world engineering design problems like Brushless DC wheel motor, Safety isolating transformer, Helical spring, Two-bar truss and Welded beam. Its efficacy is benchmarked against prominent algorithms such as the non-dominated sorting grey wolf optimizer (NSGWO), multiobjective multi-verse optimization (MOMVO), non-dominated sorting genetic algorithm (NSGA-II), decomposition-based multiobjective evolutionary algorithm (MOEA/D) and multiobjective marine predator algorithm (MOMPA). Quantitative analysis is conducted using GD, IGD, SP, SD, HV and RT metrics to represent convergence and distribution, while qualitative aspects are presented through graphical representations of the Pareto fronts. The MOLCA source code is available at: https://github.com/kanak02/MOLCA.
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  • 文章类型: Journal Article
    建立车辆粒子模型,对比分析3种不同的避碰方法的有效性。结果表明,在车辆高速紧急避碰过程中,变道防撞比制动防撞需要更小的纵向距离,并且更接近变道和制动防撞的组合。根据上述情况,提出了一种双层控制策略,以避免车辆在高速变道时发生碰撞。在比较和分析三个多项式参考轨迹之后,选择五次多项式作为参考路径。多目标优化模型预测控制用于跟踪横向位移,优化目标是最小化横向位置偏差,偏航率跟踪偏差,和控制增量。下纵向速度跟踪控制策略是控制车辆驱动系统和制动系统跟踪预期速度。最后,验证车辆在120km/h时的变道条件和其他速度条件。结果表明,该控制策略能够很好地跟踪纵向和横向轨迹,实现有效的车道变换和防撞。
    The vehicle particle model was built to compare and analyze the effectiveness of three different collision avoidance methods. The results show that during vehicle high-speed emergency collision avoidance, lane change collision avoidance requires a smaller longitudinal distance than braking collision avoidance and is closer to that with a combination of lane change and braking collision avoidance. Based on the above, a double-layer control strategy is proposed to avoid collision when vehicles change lanes at high speed. The quintic polynomial is chosen as the reference path after comparing and analyzing three polynomial reference trajectories. The multiobjective optimized model predictive control is used to track the lateral displacement, and the optimization objective is to minimize the lateral position deviation, yaw rate tracking deviation, and control increment. The lower longitudinal speed tracking control strategy is to control the vehicle drive system and brake system to track the expected speed. Finally, the lane changing conditions and other speed conditions of the vehicle at 120 km/h are verified. The results show that the control strategy can track the longitudinal and lateral trajectories well and achieve effective lane change and collision avoidance.
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  • 文章类型: Journal Article
    我们可以在许多不同的领域找到团队选择问题的解决方案。问题求解器需要在搜索过程中扫描大量可用解决方案。该问题属于一类组合和NP-Hard问题,需要有效的搜索算法来保持解的质量和合理的执行时间。为了在决策过程中实现多个目标,团队选择问题变得更加复杂。本研究引入了一个跨职能团队(CFT)选择模型,该模型具有不同的技能要求,适用于在深度和广泛方面都满足最大要求的候选人。我们介绍了一种结合折衷编程(CP)方法和元启发式算法的方法,包括遗传算法(GA)和蚁群优化算法(ACO),来解决所提出的优化问题。我们将开发的算法与MIQP-CPLEX求解器对500名具有37项技能和几个随机分布数据集的编程参赛者进行了比较。我们的实验结果表明,所提出的算法在几个评估方面都优于CPLEX,包括解决方案质量和执行时间。与多目标进化算法(MOEA)相比,所开发的方法还证明了多准则决策过程的有效性。
    We can find solutions to the team selection problem in many different areas. The problem solver needs to scan across a large array of available solutions during their search. This problem belongs to a class of combinatorial and NP-Hard problems that requires an efficient search algorithm to maintain the quality of solutions and a reasonable execution time. The team selection problem has become more complicated in order to achieve multiple goals in its decision-making process. This study introduces a multiple cross-functional team (CFT) selection model with different skill requirements for candidates who meet the maximum required skills in both deep and wide aspects. We introduced a method that combines a compromise programming (CP) approach and metaheuristic algorithms, including the genetic algorithm (GA) and ant colony optimization (ACO), to solve the proposed optimization problem. We compared the developed algorithms with the MIQP-CPLEX solver on 500 programming contestants with 37 skills and several randomized distribution datasets. Our experimental results show that the proposed algorithms outperformed CPLEX across several assessment aspects, including solution quality and execution time. The developed method also demonstrated the effectiveness of the multi-criteria decision-making process when compared with the multi-objective evolutionary algorithm (MOEA).
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  • 文章类型: Journal Article
    车辆路径问题(VRP)及其变体存在于许多领域,尤其是物流。在这项研究中,我们将一种自适应方法引入到复杂的VRP中。它将多目标优化和几种形式的VRP与城市装运系统的实际要求相结合。优化器需要考虑地形和交通状况。拟议的模型还将客户的期望和托运人的考虑作为目标,以及运输成本等共同目标。通过将原始的多目标问题分解为基于距离的最小化问题,我们提供了折衷编程来解决多目标问题。我们设计了一种混合版本的遗传算法与局部搜索算法来解决所提出的问题。我们用禁忌搜索算法和原始遗传算法在测试数据集上评估了该算法的有效性。结果表明,该方法是多目标VRP的有效决策工具,也是VRP新变化的有效求解器。
    The Vehicle Routing Problem (VRP) and its variants are found in many fields, especially logistics. In this study, we introduced an adaptive method to a complex VRP. It combines multi-objective optimization and several forms of VRPs with practical requirements for an urban shipment system. The optimizer needs to consider terrain and traffic conditions. The proposed model also considers customers\' expectations and shipper considerations as goals, and a common goal such as transportation cost. We offered compromise programming to approach the multi-objective problem by decomposing the original multi-objective problem into a minimized distance-based problem. We designed a hybrid version of the genetic algorithm with the local search algorithm to solve the proposed problem. We evaluated the effectiveness of the proposed algorithm with the Tabu Search algorithm and the original genetic algorithm on the tested dataset. The results show that our method is an effective decision-making tool for the multi-objective VRP and an effective solver for the new variation of VRP.
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  • 文章类型: Journal Article
    存在许多分为亚类的膜活性肽,例如能够进入真核细胞的细胞穿透肽(CPP)或能够与原核细胞包膜相互作用的抗微生物肽(AMP)。肽膜相互作用产生于解释特定物理化学性质的肽的独特序列基序。膜活性肽主要是阳离子,通常是初级或次级两亲性,它们与膜相互作用取决于双层脂质的组成。这些肽的序列由源自天然蛋白质或合成来源的短5-30个氨基酸部分组成。膜活性肽可以使用计算方法设计或可以在组合文库的筛选中鉴定。这篇综述的重点是成功应用于膜活性肽的设计和优化的策略,因为成功的候选肽的不同特征是生物医学应用的先决条件。不仅膜活性,而且在生物环境中的降解稳定性,诱导抗性的倾向,和有利的毒理学性质是在设计有用的膜活性肽的尝试中必须考虑的关键参数。获得许多膜活性肽的不同生物学特性的可靠测定系统是多目标肽优化的重要工具。
    A multitude of membrane active peptides exists that divides into subclasses, such as cell penetrating peptides (CPPs) capable to enter eukaryotic cells or antimicrobial peptides (AMPs) able to interact with prokaryotic cell envelops. Peptide membrane interactions arise from unique sequence motifs of the peptides that account for particular physicochemical properties. Membrane active peptides are mainly cationic, often primary or secondary amphipathic, and they interact with membranes depending on the composition of the bilayer lipids. Sequences of these peptides consist of short 5-30 amino acid sections derived from natural proteins or synthetic sources. Membrane active peptides can be designed using computational methods or can be identified in screenings of combinatorial libraries. This review focuses on strategies that were successfully applied to the design and optimization of membrane active peptides with respect to the fact that diverse features of successful peptide candidates are prerequisites for biomedical application. Not only membrane activity but also degradation stability in biological environments, propensity to induce resistances, and advantageous toxicological properties are crucial parameters that have to be considered in attempts to design useful membrane active peptides. Reliable assay systems to access the different biological characteristics of numerous membrane active peptides are essential tools for multi-objective peptide optimization.
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  • 文章类型: Journal Article
    In this research the engine performance of biodiesel made with castor oil through homogeneous alkali catalyzed transesterification was analyzed. The input variables for the performance analysis were biodiesel blend and engine speed while the response variables were break power (BP), basic specific fuel consumption (BSFC), break thermal efficiency (BTE), torque and unit cost. The engine performance was modeled using artificial neural network (ANN) and the ANN was subsequently used as the objective function for a non dominated sorting genetic algorithm (NSGA-II) for multi objective optimization of the engine performance. The ANN was equally coupled with a desirability function whose outputs were optimized using simulated annealing for multi objective optimization of the engine performance. Subsequent comparison of the two optimization models was done. The results show that biodiesel from castor oil could be a good replacement for biodiesels from fossil fuels. The ANN model predicted engine performance very well with the lowest value of the correlation coefficient between the experimental responses and ANN predictions being 0.9733. The multi objective optimization using desirability function performed excellently well with the optimum blend and speed being 78.7% and 1754.48 rpm respectively. The Pareto front from the NSGA-II algorithm generally has high desirability values. The Pareto front solution which is more flexible than the desirability function solution would serve as an excellent guide for engine designers. Finally, castor oil based biodiesel cost was for the first time integrated into engine performance optimization studies.
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  • 文章类型: Journal Article
    Oil pipeline network system health monitoring is important primarily due to the high cost of failure consequences. Optimal sensor selection helps provide more effective system health information from the perspective of economic and technical constraints. Optimization models confront different issues. For instance, many oil pipeline system performance models are inherently nonlinear, requiring nonlinear modelling. Optimization also confronts modeling uncertainties. Oil pipeline systems are among the most complicated and uncertain dynamic systems, as they include human elements, complex failure mechanisms, control systems, and most importantly component interactions. In this paper, an entropy-based Bayesian network optimization methodology for sensor selection and placement under uncertainty is developed. Entropy is a commonly used measure of information often been used to characterize uncertainty, particularly to quantify the effectiveness of measured signals of sensors in system health monitoring contexts. The entropy based Bayesian network optimization outlined herein also incorporates the effect that sensor reliability has on system information entropy content, which can also be related to the sensor cost. This approach is developed further by incorporating system information entropy and sensor costs in order to evaluate the performance of sensor combinations. The paper illustrates the approach using a simple oil pipeline network example. The so-called particle swarm optimization algorithm is used to solve the multi-objective optimization model, establishing the Pareto frontier.
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  • 文章类型: Journal Article
    The research of innovative methodologies to improve the Aluminium alloys formability at room temperature still remains an open question: the local modification of the material properties via short-term heat treatments followed by the stamping at room temperature is reported to be an effective alternative to the forming in warm conditions. In the present work, such a methodology has been applied to the deep drawing of an age-hardenable Aluminium alloy (AA6082-T6) using an experimental/numerical approach. A preliminary extensive material characterization was aimed at investigating the material behaviour: (i) in the as-received condition (peak hardening), (ii) in the supersaturated condition (obtained by physical simulation) and (iii) after being locally solutioned via laser heating. A Finite Element based approach (Abaqus CAE, v. 6.17) was then used to design the laser treatment of the blanks to be subsequently deep drawn at room temperature: a 2D axisymmetric model of the deep drawing process was coupled with the optimization platform modeFRONTIER in order to define the radial extent of the laser heat treated area able to maximize the Limit Drawing Ratio. The experimental tests were finally conducted for validation purposes and revealed the effectiveness of the adopted approach which allowed to improve the drawability of more than 20% with respect to the as received condition (T6).
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  • 文章类型: Journal Article
    OBJECTIVE: In cancer therapy optimization, an optimal amount of drug is determined to not only reduce the tumor size but also to maintain the level of chemo toxicity in the patient\'s body. The increase in the number of objectives and constraints further burdens the optimization problem. The objective of the present work is to solve a Constrained Multi- Objective Optimization Problem (CMOOP) of the Cancer-Chemotherapy. This optimization results in optimal drug schedule through the minimization of the tumor size and the drug concentration by ensuring the patient\'s health level during dosing within an acceptable level.
    METHODS: This paper presents two hybrid methodologies that combines optimal control theory with multi-objective swarm and evolutionary algorithms and compares the performance of these methodologies with multi-objective swarm intelligence algorithms such as MOEAD, MODE, MOPSO and M-MOPSO. The hybrid and conventional methodologies are compared by addressing CMOOP.
    RESULTS: The minimized tumor and drug concentration results obtained by the hybrid methodologies demonstrate that they are not only superior to pure swarm intelligence or evolutionary algorithm methodologies but also consumes far less computational time. Further, Second Order Sufficient Condition (SSC) is also used to verify and validate the optimality condition of the constrained multi-objective problem.
    CONCLUSIONS: The proposed methodologies reduce chemo-medicine administration while maintaining effective tumor killing. This will be helpful for oncologist to discover and find the optimum dose schedule of the chemotherapy that reduces the tumor cells while maintaining the patients\' health at a safe level.
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  • 文章类型: Journal Article
    背景:16S核糖体RNA基因的靶向扩增子测序是研究微生物多样性的关键工具之一。这种方法的准确性在很大程度上取决于引物对的选择,特别是,在效率之间的平衡上,样品中含有的不同细菌16S序列的扩增的特异性和灵敏度。因此,需要计算方法来设计能够考虑由新测序技术提供的知识的最佳细菌16S引物。
    结果:我们在这里提出了一种用于优化引物组选择的计算方法,基于多目标优化,其同时:1)最大化靶扩增的效率和特异性;2)最大化与至少一个引物匹配的不同细菌16S序列的数目;3)最小化匹配每个细菌16S序列的引物数目的差异。我们的算法可以应用于任何所需的扩增子长度,而不会影响计算性能。所开发算法的源代码作为GNU通用公共许可证下的mopo16S软件工具(16S实验的多目标引物优化)发布,可在http://sysbiobig上获得。dei.unipd.it/?q=Software#mopo16S。
    结论:结果表明,根据所有三个优化标准,我们的策略能够找到比文献中可用的更好的引物对。我们还通过实验验证了通过我们的方法在多种细菌物种上鉴定的三个引物对,属于不同的属和门。结果证实了预测的效率和使引物匹配的不同细菌16S序列的数量最大化的能力。
    BACKGROUND: Targeted amplicon sequencing of the 16S ribosomal RNA gene is one of the key tools for studying microbial diversity. The accuracy of this approach strongly depends on the choice of primer pairs and, in particular, on the balance between efficiency, specificity and sensitivity in the amplification of the different bacterial 16S sequences contained in a sample. There is thus the need for computational methods to design optimal bacterial 16S primers able to take into account the knowledge provided by the new sequencing technologies.
    RESULTS: We propose here a computational method for optimizing the choice of primer sets, based on multi-objective optimization, which simultaneously: 1) maximizes efficiency and specificity of target amplification; 2) maximizes the number of different bacterial 16S sequences matched by at least one primer; 3) minimizes the differences in the number of primers matching each bacterial 16S sequence. Our algorithm can be applied to any desired amplicon length without affecting computational performance. The source code of the developed algorithm is released as the mopo16S software tool (Multi-Objective Primer Optimization for 16S experiments) under the GNU General Public License and is available at http://sysbiobig.dei.unipd.it/?q=Software#mopo16S .
    CONCLUSIONS: Results show that our strategy is able to find better primer pairs than the ones available in the literature according to all three optimization criteria. We also experimentally validated three of the primer pairs identified by our method on multiple bacterial species, belonging to different genera and phyla. Results confirm the predicted efficiency and the ability to maximize the number of different bacterial 16S sequences matched by primers.
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