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Optimization for the Redundancy Allocation Problem of Reliability Using an Improved Particle Swarm Optimization Algorithm 基于改进粒子群算法的可靠性冗余分配优化
IF 4 Pub Date : 2021-11-23 DOI: 10.1155/2021/6385713
H. Marouani
This paper presents an enhanced and improved particle swarm optimization (PSO) approach to overcome reliability-redundancy allocation problems in series, series-parallel, and complex systems. The problems mentioned above can be solved by increasing the overall system reliability and minimizing the system cost, weight, and volume. To achieve this with these nonlinear constraints, an approach is developed based on PSO. In particular, the inertia and acceleration coefficients of the classical particle swarm algorithm are improved by considering a normal distribution for the coefficients. The new expressions can enhance the global search ability in the initial stage, restrain premature convergence, and enable the algorithm to focus on the local fine search in the later stage, and this can enhance the perfection of the optimization process. Illustrative examples are provided as proof of the efficiency and effectiveness of the proposed approach. Results show that the overall system reliability is far better when compared with that of some approaches developed in previous studies for all three tested cases.
本文提出了一种改进的粒子群算法来解决串联、串并联和复杂系统的可靠性冗余分配问题。上述问题可以通过提高整体系统可靠性和最小化系统成本、重量和体积来解决。为了在这些非线性约束条件下实现这一目标,提出了一种基于粒子群算法的方法。特别是,通过考虑惯性系数和加速度系数的正态分布,改进了经典粒子群算法的惯性系数和加速度系数。新的表达式可以增强初始阶段的全局搜索能力,抑制过早收敛,并使算法在后期专注于局部精细搜索,从而增强优化过程的完善性。举例说明了该方法的有效性和有效性。结果表明,在所有三个测试案例中,与先前研究中开发的一些方法相比,系统的整体可靠性要好得多。
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引用次数: 8
Optimum Design and Performance Analyses of Convective-Radiative Cooling Fin under the Influence of Magnetic Field Using Finite Element Method 磁场影响下对流辐射散热片优化设计及性能有限元分析
IF 4 Pub Date : 2019-02-17 DOI: 10.1155/2019/9705792
M. Sobamowo
In this study, the optimum design dimensions and performance analyses of convective-radiative cooling fin subjected to magnetic field are presented using finite element method. The numerical solutions are verified by the exact analytical solution for the linearized models using Laplace transform. The optimum dimensions for the optimum performance of the convection-radiative fin with variable thermal conductivity are investigated and presented graphically. Also, the effects of convective, radiative, and magnetic parameters as well as Biot number on the thermal performance of the cooling fin are analyzed using the numerical solutions. From the results, it is established that the optimum length of the fin and the thermogeometric parameter increases as the nonlinear thermal conductivity term increases. Further analyses also reveal that as the Biot number, convective, radiative, and magnetic parameters, increases, the rate of heat transfer from the fin increases and consequently improves the efficiency of the fin. Additionally, effects of the thermal stability values for the various multiboiling heat transfer modes are established. It is established that, in order to ensure stability and avoid numerical diffusion of the solution by the Galerkin finite element method, the thermogeometric parameter must not exceed some certain values for the different multiboiling heat transfer modes. It is hope that the present study will enhance the understanding of thermal response of solid fin under various factors and fin design considerations.
本文采用有限元法对磁场作用下的对流辐射散热片进行了优化设计尺寸和性能分析。用拉普拉斯变换对线性化模型的精确解析解验证了数值解的正确性。研究了变导热对流辐射翅片的最佳尺寸,并给出了图形。利用数值解分析了对流、辐射、磁参数以及Biot数对散热片热性能的影响。结果表明,随着非线性导热系数项的增大,翅片的最佳长度和热几何参数均增大。进一步的分析还表明,随着Biot数、对流、辐射和磁参数的增加,翅片的换热速率增加,从而提高了翅片的效率。此外,还建立了热稳定性值对各种多沸换热模式的影响。通过Galerkin有限元法确定了在不同的多沸腾传热模式下,为了保证溶液的稳定性和避免数值扩散,热几何参数不能超过一定的值。希望本文的研究能加深对固体翅片在各种因素和设计考虑下的热响应的认识。
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引用次数: 6
Theoretical Analysis of an Imprecise Prey-Predator Model with Harvesting and Optimal Control 具有收获和最优控制的不精确捕食-捕食模型的理论分析
IF 4 Pub Date : 2019-01-21 DOI: 10.1155/2019/9512879
Anjana P. Das, M. Pal
In our present paper, we formulate and study a prey-predator system with imprecise values for the parameters. We also consider harvesting for both the prey and predator species. Then we describe the complex dynamics of the proposed model system including positivity and uniform boundedness of the system, and existence and stability criteria of various equilibrium points. Also the existence of bionomic equilibrium and optimal harvesting policy are thoroughly investigated. Some numerical simulations have been presented in support of theoretical works. Further the requirement of considering imprecise values for the set of model parameters is also highlighted.
在本文中,我们建立并研究了一个参数值不精确的食饵-捕食系统。我们还考虑了对猎物和捕食者的收获。然后描述了模型系统的复杂动力学特性,包括系统的正有界性和一致有界性,以及各平衡点的存在性和稳定性准则。并对生物平衡和最优采收策略的存在性进行了深入的研究。本文给出了一些数值模拟来支持理论工作。此外,还强调了考虑模型参数集的不精确值的要求。
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引用次数: 15
Extended GRASP-Capacitated K-Means Clustering Algorithm to Establish Humanitarian Support Centers in Large Regions at Risk in Mexico 扩展grip - capacitated K-Means聚类算法在墨西哥大风险地区建立人道主义支持中心
IF 4 Pub Date : 2018-12-20 DOI: 10.1155/2018/3605298
S. Caballero-Morales, Erika Barojas-Payán, Diana Sánchez-Partida, J. Martínez-Flores
Mexico is located within the so-called Fire Belt which makes it susceptible to earthquakes. In fact, two-thirds of the Mexican territory have a significant seismic risk. On the other hand, the country’s location in the tropical zone makes it susceptible to hurricanes which are generated in both the Pacific and Atlantic Oceans. Due to these situations, each year many communities are affected by diverse natural disasters in Mexico and efficient logistic systems are required to provide prompt support. This work is aimed at providing an efficient metaheuristic to determine the most appropriate location for support centers in the State of Veracruz, which is one of the most affected regions in Mexico. The metaheuristic is based on the K-Means Clustering (KMC) algorithm which is extended to integrate (a) the associated capacity restrictions of the support centers, (b) a micro Genetic Algorithm μGA to estimate a search interval for the most suitable number of support centers, (c) variable number of assigned elements to centers in order to add flexibility to the assignation task, and (d) random-based decision model to further improve the final assignments. These extensions on the KMC algorithm led to the GRASP-Capacitated K-Means Clustering (GRASP-CKMC) algorithm which was able to provide very suitable solutions for the establishment of 260 support centers for 3837 communities at risk in Veracruz, Mexico. Validation of the GRASP-CKMC algorithm was performed with well-known test instances and metaheuristics. The validation supported its suitability as alternative to standard metaheuristics such as Capacitated K-Means (CKM), Genetic Algorithms (GA), and Variable Neighborhood Search (VNS).
墨西哥位于所谓的“火带”内,这使它容易受到地震的影响。事实上,墨西哥三分之二的领土都有严重的地震风险。另一方面,该国位于热带地区,容易受到太平洋和大西洋产生的飓风的影响。由于这些情况,墨西哥每年都有许多社区受到各种自然灾害的影响,需要高效的物流系统提供及时的支持。这项工作旨在提供一种有效的元启发式方法,以确定韦拉克鲁斯州支持中心的最合适位置,韦拉克鲁斯州是墨西哥受灾最严重的地区之一。元启发式算法是基于k -均值聚类(K-Means Clustering, KMC)算法,该算法扩展到综合(a)支持中心的相关容量限制,(b)微遗传算法μGA来估计最合适的支持中心数量的搜索区间,(c)分配给中心的元素数量可变,以增加分配任务的灵活性,(d)基于随机的决策模型来进一步改进最终的分配。这些对KMC算法的扩展导致了GRASP-Capacitated K-Means Clustering (GRASP-CKMC)算法,该算法能够为墨西哥韦拉克鲁斯州3837个面临风险的社区建立260个支持中心提供非常合适的解决方案。利用众所周知的测试实例和元启发式方法对GRASP-CKMC算法进行了验证。验证支持其作为标准元启发式方法(如Capacitated K-Means (CKM),遗传算法(GA)和可变邻域搜索(VNS))的替代方案的适用性。
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引用次数: 13
Topology-Aware Strategy for MPI-IO Operations in Clusters 集群中MPI-IO操作的拓扑感知策略
IF 4 Pub Date : 2018-11-19 DOI: 10.1155/2018/2068490
Weifeng Liu, Jie Zhou, Meng Guo
This paper presents the topology-aware two-phase I/O (TATP), which optimizes the most popular collective MPI-IO implementation of ROMIO. In order to improve the hop-bytes metric during the file access, topology-aware two-phase I/O employs the Linear Assignment Problem (LAP) for finding an optimal assignment of file domain to aggregators, an aspect which is not considered in most two-phase I/O implementations. The distribution is based on the local data stored by each process, and its main purpose is to reduce the total hop-bytes of the I/O collective operation. Therefore, the global execution time can be improved. In most of the considered scenarios, topology-aware two-phase I/O obtains important improvements when compared with the original two-phase I/O implementations.
本文提出了拓扑感知的两阶段I/O (TATP),它优化了最流行的ROMIO集体MPI-IO实现。为了改善文件访问期间的跳字节度量,拓扑感知两阶段I/O采用线性分配问题(LAP)来寻找文件域到聚合器的最佳分配,这是大多数两阶段I/O实现中没有考虑的一个方面。该分布基于每个进程存储的本地数据,其主要目的是减少I/O集体操作的总跳字节数。因此,可以提高全局执行时间。在大多数考虑的场景中,与最初的两阶段I/O实现相比,拓扑感知的两阶段I/O获得了重要的改进。
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引用次数: 4
Jaya Algorithm Guided Procedure to Segment Tumor from Brain MRI Jaya算法指导脑MRI肿瘤分割
IF 4 Pub Date : 2018-11-14 DOI: 10.1155/2018/3738049
S. Satapathy, V. Rajinikanth
Brain abnormality is a cause for the chief risk factors in human society with larger morbidity rate. Identification of tumor in its early stage is essential to provide necessary treatment procedure to save the patient. In this work, Jaya Algorithm (JA) and Otsu’s Function (OF) guided method is presented to mine the irregular section of brain MRI recorded with Flair and T2 modality. This work implements a two-step process to examine the brain tumor from the axial, sagittal, and coronal views of the two-dimensional (2D) MRI slices. This paper presents a detailed evaluation of thresholding procedure with varied threshold levels (Th=2,3,4,5), skull stripping process before/after the thresholding practice, and the tumor extraction based on the Chan-Vese approach. Superiority of JA is confirmed among other prominent heuristic approaches found in literature. The outcome of implemented study confirms that Jaya Algorithm guided method is capable of presenting superior values of Jaccard-Index, Dice-Coefficient, sensitivity, specificity, accuracy, and precision on the BRATS 2015 dataset.
脑异常是造成人类社会主要危险因素之一,发病率较高。早期发现肿瘤对于提供必要的治疗程序以挽救患者至关重要。本文采用Jaya算法(JA)和Otsu 's Function (OF)引导方法对Flair和T2模态记录的脑MRI不规则切片进行挖掘。这项工作实现了两步的过程,从二维(2D) MRI切片的轴向,矢状面和冠状面检查脑肿瘤。本文详细评价了不同阈值水平(Th=2,3,4,5)的阈值分割过程,阈值分割前后的颅骨剥离过程,以及基于Chan-Vese方法的肿瘤提取。在文献中发现的其他突出的启发式方法中,JA的优越性得到了证实。实施的研究结果证实,Jaya算法指导方法能够在BRATS 2015数据集上呈现优越的Jaccard-Index、Dice-Coefficient、灵敏度、特异性、准确度和精密度值。
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引用次数: 45
HybridHAM: A Novel Hybrid Heuristic for Finding Hamiltonian Cycle HybridHAM:一种寻找哈密顿循环的新型混合启发式算法
IF 4 Pub Date : 2018-10-16 DOI: 10.1155/2018/9328103
K. R. Seeja
Hamiltonian Cycle Problem is one of the most explored combinatorial problems. Being an NP-complete problem, heuristic approaches are found to be more powerful than exponential time exact algorithms. This paper presents an efficient hybrid heuristic that sits in between the complex reliable approaches and simple faster approaches. The proposed algorithm is a combination of greedy, rotational transformation and unreachable vertex heuristics that works in three phases. In the first phase, an initial path is created by using greedy depth first search. This initial path is then extended to a Hamiltonian path in second phase by using rotational transformation and greedy depth first search. Third phase converts the Hamiltonian path into a Hamiltonian cycle by using rotational transformation. The proposed approach could find Hamiltonian cycles from a set of hard graphs collected from the literature, all the Hamiltonian instances (1000 to 5000 vertices) given in TSPLIB, and some instances of FHCP Challenge Set. Moreover, the algorithm has O(n3) worst case time complexity. The performance of the algorithm has been compared with the state-of-the-art algorithms and it was found that HybridHAM outperforms others in terms of running time.
哈密顿循环问题是研究最多的组合问题之一。作为一个np完全问题,启发式方法被发现比指数时间精确算法更强大。本文提出了一种介于复杂可靠方法和简单快速方法之间的高效混合启发式算法。该算法是贪婪、旋转变换和不可达顶点启发式的结合,分三个阶段工作。在第一阶段,使用贪婪深度优先搜索创建初始路径。然后利用旋转变换和贪婪深度优先搜索,在第二阶段将初始路径扩展为哈密顿路径。第三阶段通过旋转变换将哈密顿路径转换成哈密顿循环。该方法可以从文献中收集的一组硬图、TSPLIB中给出的所有哈密顿实例(1000 ~ 5000个顶点)以及FHCP挑战集的一些实例中找到哈密顿环。该算法的最坏情况时间复杂度为0 (n3)。该算法的性能与最先进的算法进行了比较,发现HybridHAM在运行时间方面优于其他算法。
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引用次数: 7
Asymptotics for Optimal Design Problems for the Schrödinger Equation with a Potential 带势Schrödinger方程最优设计问题的渐近性
IF 4 Pub Date : 2018-10-08 DOI: 10.1155/2018/8162845
Alden Waters, Ekaterina Merkurjev
We study the problem of optimal observability and prove time asymptotic observability estimates for the Schrödinger equation with a potential in L∞Ω, with Ω⊂Rd, using spectral theory. An elegant way to model the problem using a time asymptotic observability constant is presented. For certain small potentials, we demonstrate the existence of a nonzero asymptotic observability constant under given conditions and describe its explicit properties and optimal values. Moreover, we give a precise description of numerical models to analyze the properties of important examples of potentials wells, including that of the modified harmonic oscillator.
我们研究了最优可观察性问题,并使用谱理论证明了具有L∞Ω中一个位势的Schrödinger方程的时间渐近可观察性估计,其中Ω∧Rd。提出了一种利用时间渐近可观测常数对问题进行建模的简便方法。对于某些小势,我们证明了在给定条件下一个非零渐近可观测常数的存在性,并描述了它的显式性质和最优值。此外,我们给出了一个精确的数值模型来分析势阱的重要例子,包括修正谐振子的势阱。
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引用次数: 0
Optimizing Testing-Resource Allocation Using Architecture-Based Software Reliability Model 基于体系结构的软件可靠性模型优化测试资源分配
IF 4 Pub Date : 2018-09-27 DOI: 10.1155/2018/6948656
H. Okamura, T. Dohi
In the management of software testing, testing-recourse allocation is one of the most important problems due to the tradeoff between development cost and reliability of released software. This paper presents the model-based approach to design the testing-resource allocation. In particular, we employ the architecture-based software reliability model with operational profile to estimate the quantitative software reliability in operation phase and formulate the multiobjective optimization problems with respect to cost, testing effort, and software reliability. In numerical experiment, we investigate the difference of the presented optimization problem from the existing testing-resource allocation model.
在软件测试管理中,测试资源的分配是一个非常重要的问题,因为它需要权衡软件的开发成本和可靠性。本文提出了一种基于模型的测试资源分配设计方法。特别地,我们采用基于体系结构的软件可靠性模型和运行轮廓来定量评估软件运行阶段的可靠性,并制定了关于成本、测试工作量和软件可靠性的多目标优化问题。通过数值实验,研究了该优化问题与现有测试资源分配模型的区别。
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引用次数: 3
A New Modified Three-Term Hestenes–Stiefel Conjugate Gradient Method with Sufficient Descent Property and Its Global Convergence 一种新的改进的具有充分下降性质的三项Hestenes-Stiefel共轭梯度法及其全局收敛性
IF 4 Pub Date : 2018-09-27 DOI: 10.1155/2018/5057096
B. Baluch, Z. Salleh, Ahmad Alhawarat
This paper describes a modified three-term Hestenes–Stiefel (HS) method. The original HS method is the earliest conjugate gradient method. Although the HS method achieves global convergence using an exact line search, this is not guaranteed in the case of an inexact line search. In addition, the HS method does not usually satisfy the descent property. Our modified three-term conjugate gradient method possesses a sufficient descent property regardless of the type of line search and guarantees global convergence using the inexact Wolfe–Powell line search. The numerical efficiency of the modified three-term HS method is checked using 75 standard test functions. It is known that three-term conjugate gradient methods are numerically more efficient than two-term conjugate gradient methods. Importantly, this paper quantifies how much better the three-term performance is compared with two-term methods. Thus, in the numerical results, we compare our new modification with an efficient two-term conjugate gradient method. We also compare our modification with a state-of-the-art three-term HS method. Finally, we conclude that our proposed modification is globally convergent and numerically efficient.
本文提出了一种改进的三项Hestenes-Stiefel (HS)方法。原始HS法是最早的共轭梯度法。虽然HS方法使用精确的线搜索实现全局收敛,但在不精确的线搜索情况下不能保证这一点。此外,HS方法通常不满足下降特性。本文改进的三项共轭梯度法具有充分的下降性质,无论线搜索的类型如何,都保证了非精确Wolfe-Powell线搜索的全局收敛性。用75个标准测试函数检验了改进的三项HS方法的数值效率。众所周知,三项共轭梯度法在数值上比两项共轭梯度法更有效。重要的是,本文量化了与两期方法相比,三期方法的性能有多好。因此,在数值结果中,我们将新的修正与一种有效的两项共轭梯度法进行了比较。我们还比较了我们的修改与最先进的三期HS方法。最后,我们得出结论,我们提出的修正是全局收敛的和数值有效的。
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引用次数: 11
期刊
Journal of Optimization
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