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AlexNet改进及优化方法的研究 被引量:28
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作者 郭敏钢 宫鹤 《计算机工程与应用》 CSCD 北大核心 2020年第20期124-131,共8页
通过对Normalization、优化器、激活函数三方面对AlexNet卷积神经网络进行了改进及优化。针对LRN(Local Response Normalization)不存在可学习参数,提出了用WN(Weight Normalization)来代替LRN,同时将WN置于所有池化层(Pooling layer)之... 通过对Normalization、优化器、激活函数三方面对AlexNet卷积神经网络进行了改进及优化。针对LRN(Local Response Normalization)不存在可学习参数,提出了用WN(Weight Normalization)来代替LRN,同时将WN置于所有池化层(Pooling layer)之后,提高了AlexNet模型训练的准确率;通过对比分析Adam、RMSProp、Momentum三种优化器在不同学习率(Learning rate)下对AlexNet模型训练的影响,并得出了相应的学习率的优化区间,提高了AlexNet在Optimizer的学习率区间选择上的准确性;针对AlexNet中ReLU激活函数存在的部分权重无法更新以及梯度爆炸问题,提出了ReLU6与Swish的融合分段函数算法,提升了AlexNet模型训练收敛速度以及准确率的同时也缓解了过拟合现象的发生。 展开更多
关键词 AlexNet 卷积神经网络(CNN) NORMALIZATION 优化器 激活函数
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Optimal planning of battery energy storage considering reliability benefit and operation strategy in active distribution system 被引量:26
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作者 Wenxia LIU Shuya NIU Huiting XU 《Journal of Modern Power Systems and Clean Energy》 SCIE EI 2017年第2期177-186,共10页
In this paper, a cost-benefit analysis based optimal planning model of battery energy storage system(BESS) in active distribution system(ADS) is established considering a new BESS operation strategy. Reliability impro... In this paper, a cost-benefit analysis based optimal planning model of battery energy storage system(BESS) in active distribution system(ADS) is established considering a new BESS operation strategy. Reliability improvement benefit of BESS is considered and a numerical calculation method based on expectation is proposed for simple and convenient calculation of system reliability improvement with BESS in planning phase. Decision variables include both configuration variables and operation strategy control variables. In order to prevent the interaction between two types of variables and enhance global search ability, intelligent single particle optimizer(ISPO) is adopted to optimize this model. Case studies on a modified IEEE benchmark system verified the performance of the proposed operation strategy and optimal planning model of BESS. 展开更多
关键词 Battery energy storage system Cost-benefit analysis Reliability improvement benefit Operation strategy Intelligent single particle optimizer
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Oracle数据库查询优化方法研究 被引量:22
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作者 杨小艳 尹明 戴学丰 《计算机与现代化》 2008年第4期4-7,共4页
Oracle数据库是当前应用最广泛的大型数据库之一,其系统结构复杂,性能受多方面因素影响,其中查询操作是影响其性能的关键因素。为了提高Oracle数据库查询效率,本文通过分析Oracle处理查询语句的过程以及优化器的工作原理,结合实例,讨论... Oracle数据库是当前应用最广泛的大型数据库之一,其系统结构复杂,性能受多方面因素影响,其中查询操作是影响其性能的关键因素。为了提高Oracle数据库查询效率,本文通过分析Oracle处理查询语句的过程以及优化器的工作原理,结合实例,讨论了Oracle数据库查询优化的多种有效方法。 展开更多
关键词 ORACLE数据库 SQL语句 优化器 执行计划
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ORACLE数据库SQL优化原则 被引量:20
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作者 郭珉 《计算机系统应用》 2010年第4期170-173,165,共5页
Oracle数据库是当前应用最广泛的大型数据库之一,其系统结构复杂,性能受多方面因素影响,其中SQL语句的执行效率是影响其性能的关键因素。以一个省级通信运营商的ORACLE ERP系统为例,从ORACLE数据库的SQL共享原理和SQL执行过程入手,指出... Oracle数据库是当前应用最广泛的大型数据库之一,其系统结构复杂,性能受多方面因素影响,其中SQL语句的执行效率是影响其性能的关键因素。以一个省级通信运营商的ORACLE ERP系统为例,从ORACLE数据库的SQL共享原理和SQL执行过程入手,指出合理配置数据库参数,提高SQL语句共享、提高数据缓存命中率是SQL语句性能提高的前提;并在此基础提出了SQL语句优化的四个原则。 展开更多
关键词 ORACLE数据库 SQL 性能优化 优化器 共享池
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多条件分页查询优化的设计方法 被引量:21
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作者 李辉 王瑞波 《计算机工程》 CAS CSCD 北大核心 2010年第2期51-52,55,共3页
随着数据量的不断增加,数据库的分页查询效率成为提高数据库访问性能的重要问题。从分析影响分页查询速度的关键因素入手,结合优化器中SQL语句的优化原理和分页算法,通过理论推导和实验结果的分析,提出分页查询优化的设计方法。将该方... 随着数据量的不断增加,数据库的分页查询效率成为提高数据库访问性能的重要问题。从分析影响分页查询速度的关键因素入手,结合优化器中SQL语句的优化原理和分页算法,通过理论推导和实验结果的分析,提出分页查询优化的设计方法。将该方法应用于实际系统的分页框架中,取得了较好的效果。 展开更多
关键词 优化器 查询优化 分页框架
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改进的群搜索优化算法 被引量:19
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作者 张雯雰 滕少华 李丽娟 《计算机工程与应用》 CSCD 北大核心 2009年第4期48-51,168,共5页
群搜索优化(Group Search Optimizer,GSO)算法是一种新的群集智能优化算法,适宜于解决多模态高维问题。对GSO算法进行了一些改进,简化了计算过程,提高了优化性能。主要在两个方面进行改进,一是在迭代过程中,控制允许变异的维的数量,使... 群搜索优化(Group Search Optimizer,GSO)算法是一种新的群集智能优化算法,适宜于解决多模态高维问题。对GSO算法进行了一些改进,简化了计算过程,提高了优化性能。主要在两个方面进行改进,一是在迭代过程中,控制允许变异的维的数量,使之从多到少变化,以提高收敛速度。二是用随机数来确定生成个体新位置所用的一组随机值的正负数比例,避免正负数比例趋于固定,增加随机性。经过6个常用测试函数测试及与其他文献结果对比后可知,在低维情况下,此算法与GA、EP、ES、PSO、GSO算法相比有较好的整体收敛性能,高维时,此算法与GA、PSO、GSO比较,收敛性能有明显优势。 展开更多
关键词 搜索 优化 群集智能 进化算法 高维 函数优化
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Landslide susceptibility modeling based on ANFIS with teaching-learning-based optimization and Satin bowerbird optimizer 被引量:14
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作者 Wei Chen Xi Chen +2 位作者 Jianbing Peng Mahdi Panahi Saro Lee 《Geoscience Frontiers》 SCIE CAS CSCD 2021年第1期93-107,共15页
As threats of landslide hazards have become gradually more severe in recent decades,studies on landslide prevention and mitigation have attracted widespread attention in relevant domains.A hot research topic has been ... As threats of landslide hazards have become gradually more severe in recent decades,studies on landslide prevention and mitigation have attracted widespread attention in relevant domains.A hot research topic has been the ability to predict landslide susceptibility,which can be used to design schemes of land exploitation and urban development in mountainous areas.In this study,the teaching-learning-based optimization(TLBO)and satin bowerbird optimizer(SBO)algorithms were applied to optimize the adaptive neuro-fuzzy inference system(ANFIS)model for landslide susceptibility mapping.In the study area,152 landslides were identified and randomly divided into two groups as training(70%)and validation(30%)dataset.Additionally,a total of fifteen landslide influencing factors were selected.The relative importance and weights of various influencing factors were determined using the step-wise weight assessment ratio analysis(SWARA)method.Finally,the comprehensive performance of the two models was validated and compared using various indexes,such as the root mean square error(RMSE),processing time,convergence,and area under receiver operating characteristic curves(AUROC).The results demonstrated that the AUROC values of the ANFIS,ANFIS-TLBO and ANFIS-SBO models with the training data were 0.808,0.785 and 0.755,respectively.In terms of the validation dataset,the ANFISSBO model exhibited a higher AUROC value of 0.781,while the AUROC value of the ANFIS-TLBO and ANFIS models were 0.749 and 0.681,respectively.Moreover,the ANFIS-SBO model showed lower RMSE values for the validation dataset,indicating that the SBO algorithm had a better optimization capability.Meanwhile,the processing time and convergence of the ANFIS-SBO model were far superior to those of the ANFIS-TLBO model.Therefore,both the ensemble models proposed in this paper can generate adequate results,and the ANFIS-SBO model is recommended as the more suitable model for landslide susceptibility assessment in the study area considered due to its excellent accuracy and ef 展开更多
关键词 Landslide susceptibility Step-wise weight assessment ratio analysis Adaptive neuro-fuzzy fuzzy inference system Teaching-learning-based optimization Satin bowerbird optimizer
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深度学习优化器进展综述 被引量:9
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作者 常禧龙 梁琨 李文涛 《计算机工程与应用》 CSCD 北大核心 2024年第7期1-12,共12页
优化器是提高深度学习模型性能的关键因素,通过最小化损失函数使得模型的参数和真实参数接近从而提高模型的性能。随着GPT等大语言模型成为自然语言处理领域研究焦点,以梯度下降优化器为核心的传统优化器对大模型的优化效果甚微。因此... 优化器是提高深度学习模型性能的关键因素,通过最小化损失函数使得模型的参数和真实参数接近从而提高模型的性能。随着GPT等大语言模型成为自然语言处理领域研究焦点,以梯度下降优化器为核心的传统优化器对大模型的优化效果甚微。因此自适应矩估计类优化器应运而生,其在提高模型泛化能力等方面显著优于传统优化器。以梯度下降、自适应梯度和自适应矩估计三类优化器为主线,分析其原理及优劣。将优化器应用到Transformer架构中,选取法-英翻译任务作为评估基准,通过实验深入探讨优化器在特定任务上的效果差异。实验结果表明,自适应矩估计类优化器在机器翻译任务上有效提高模型的性能。同时,展望优化器的发展方向并给出在具体任务上的应用场景。 展开更多
关键词 优化器 机器翻译 TRANSFORMER 深度学习 学习率预热算法
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Advance Artificial Intelligence Technique for Designing Double T-Shaped Monopole Antenna 被引量:11
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作者 El-Sayed M.El-kenawy Hattan F.Abutarboush +1 位作者 Ali Wagdy Mohamed Abdelhameed Ibrahim 《Computers, Materials & Continua》 SCIE EI 2021年第12期2983-2995,共13页
Machine learning(ML)has taken the world by a tornado with its prevalent applications in automating ordinary tasks and using turbulent insights throughout scientific research and design strolls.ML is a massive area wit... Machine learning(ML)has taken the world by a tornado with its prevalent applications in automating ordinary tasks and using turbulent insights throughout scientific research and design strolls.ML is a massive area within artificial intelligence(AI)that focuses on obtaining valuable information out of data,explaining why ML has often been related to stats and data science.An advanced meta-heuristic optimization algorithm is proposed in this work for the optimization problem of antenna architecture design.The algorithm is designed,depending on the hybrid between the Sine Cosine Algorithm(SCA)and the Grey Wolf Optimizer(GWO),to train neural networkbased Multilayer Perceptron(MLP).The proposed optimization algorithm is a practical,versatile,and trustworthy platform to recognize the design parameters in an optimal way for an endorsement double T-shaped monopole antenna.The proposed algorithm likewise shows a comparative and statistical analysis by different curves in addition to the ANOVA and T-Test.It offers the superiority and validation stability evaluation of the predicted results to verify the procedures’accuracy. 展开更多
关键词 Antenna optimization machine learning artificial intelligence multilayer perceptron sine cosine algorithm grey wolf optimizer
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PCR扩增纳豆激酶基因的程序优化 被引量:7
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作者 罗立新 凌均建 +1 位作者 黄志立 杨汝德 《华南理工大学学报(自然科学版)》 EI CAS CSCD 北大核心 2000年第10期92-95,共4页
研究了利用PCR从纳豆菌基因组DNA中扩增纳豆激酶基因的最优化条件,得到PCR反应在本研究中的最重要的三个参数值为:模板量 10ng; Mg2+浓度豆.5 mmol/L;退火温度60℃.在这种优化程序下进行PCR反应,... 研究了利用PCR从纳豆菌基因组DNA中扩增纳豆激酶基因的最优化条件,得到PCR反应在本研究中的最重要的三个参数值为:模板量 10ng; Mg2+浓度豆.5 mmol/L;退火温度60℃.在这种优化程序下进行PCR反应,获得了特异、高效和忠实的纳豆激酶基因产物. 展开更多
关键词 聚合酶链式反应 纳豆激酶基因 程序优化 DNA
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Improved gray wolf optimizer for distributed flexible job shop scheduling problem 被引量:9
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作者 LI XinYu XIE Jin +2 位作者 MA QingJi GAO Liang LI PeiGen 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2022年第9期2105-2115,共11页
The distributed flexible job shop scheduling problem(DFJSP),which is an extension of the flexible job shop scheduling problem,is a famous NP-complete combinatorial optimization problem.This problem is widespread in th... The distributed flexible job shop scheduling problem(DFJSP),which is an extension of the flexible job shop scheduling problem,is a famous NP-complete combinatorial optimization problem.This problem is widespread in the manufacturing industries and comprises the following three subproblems:the assignment of jobs to factories,the scheduling of operations to machines,and the sequence of operations on machines.However,studies on DFJSP are seldom because of its difficulty.This paper proposes an effective improved gray wolf optimizer(IGWO)to solve the aforementioned problem.In this algorithm,new encoding and decoding schemes are designed to represent the three subproblems and transform the encoding into a feasible schedule,respectively.Four crossover operators are developed to expand the search space.A local search strategy with the concept of a critical factory is also proposed to improve the exploitability of IGWO.Effective schedules can be obtained by changing factory assignments and operation sequences in the critical factory.The proposed IGWO algorithm is evaluated on 69 famous benchmark instances and compared with six state-of-the-art algorithms to demonstrate its efficacy considering solution quality and computational efficiency.Experimental results show that the proposed algorithm has achieved good improvement.Particularly,the proposed IGWO updates the new upper bounds of 13 difficult benchmark instances. 展开更多
关键词 distributed and flexible job shop scheduling gray wolf optimizer critical factory
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ORCA海上综合导航系统的基本原理及应用 被引量:9
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作者 靳春光 王立明 《石油仪器》 2013年第5期36-40,2-3,共5页
文章对用于海上地震勘探的ORCA综合导航系统进行了系统架构、测线采集工作流程、近实时处理(NRT)和自动化等功能特点进行了介绍和分析,阐述了作为当今国际上先进的海上地震综合导航系统在作业优化、与PCS电缆定位系统和DigiSTREAMER地... 文章对用于海上地震勘探的ORCA综合导航系统进行了系统架构、测线采集工作流程、近实时处理(NRT)和自动化等功能特点进行了介绍和分析,阐述了作为当今国际上先进的海上地震综合导航系统在作业优化、与PCS电缆定位系统和DigiSTREAMER地震采集系统相结合、多方位角和多船作业,以及4D作业方面的特点与优势。 展开更多
关键词 地震勘探 近实时 作业优化器 多方位角 4D 多船作业
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Improved dynamic grey wolf optimizer 被引量:6
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作者 Xiaoqing ZHANG Yuye ZHANG Zhengfeng MING 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2021年第6期877-890,共14页
In the standard grey wolf optimizer(GWO), the search wolf must wait to update its current position until the comparison between the other search wolves and the three leader wolves is completed. During this waiting per... In the standard grey wolf optimizer(GWO), the search wolf must wait to update its current position until the comparison between the other search wolves and the three leader wolves is completed. During this waiting period, the standard GWO is seen as the static GWO. To get rid of this waiting period, two dynamic GWO algorithms are proposed: the first dynamic grey wolf optimizer(DGWO1) and the second dynamic grey wolf optimizer(DGWO2). In the dynamic GWO algorithms, the current search wolf does not need to wait for the comparisons between all other search wolves and the leading wolves, and its position can be updated after completing the comparison between itself or the previous search wolf and the leading wolves. The position of the search wolf is promptly updated in the dynamic GWO algorithms, which increases the iterative convergence rate. Based on the structure of the dynamic GWOs, the performance of the other improved GWOs is examined, verifying that for the same improved algorithm, the one based on dynamic GWO has better performance than that based on static GWO in most instances. 展开更多
关键词 Swarm intelligence Grey wolf optimizer Dynamic grey wolf optimizer optimization experiment
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最优化控制的若干问题探讨 被引量:3
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作者 贾春阳 《化工自动化及仪表》 CAS 2000年第2期1-4,共4页
石油化工生产装置的在线优化控制存在着巨大的潜在效益。浅析了在线优化系统实施过程中应加以注意的几个问题 ,以期对今后优化系统的成功应用具有一定的参考价值。
关键词 最优化控制 控制系统 石油化工 控制过程
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A New Metaheuristic Optimization Algorithms for Brushless Direct Current Wheel Motor Design Problem 被引量:8
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作者 M.Premkumar R.Sowmya +2 位作者 Pradeep Jangir Kottakkaran Sooppy Nisar Mujahed Aldhaifallah 《Computers, Materials & Continua》 SCIE EI 2021年第5期2227-2242,共16页
The Equilibrium Optimizer(EO),Grey Wolf Optimizer(GWO),and Whale Optimizer(WO)algorithms are being recently developed for engineering optimization problems.In this paper,the EO,GWO,and WO algorithms are applied indivi... The Equilibrium Optimizer(EO),Grey Wolf Optimizer(GWO),and Whale Optimizer(WO)algorithms are being recently developed for engineering optimization problems.In this paper,the EO,GWO,and WO algorithms are applied individually for a brushless direct current(BLDC)design optimization problem.The EO algorithm is inspired by the models utilized to find the system’s dynamic state and equilibrium state.The GWO and WO algorithms are inspired by the hunting behavior of the wolf and the whale,respectively.The primary purpose of any optimization technique is to find the optimal configuration by maximizing motor efficiency and/or minimizing the total mass.Therefore,two objective functions are being used to achieve these objectives.The first refers to a design with high power output and efficiency.The second is a constraint imposed by the reality that the motor is built into the wheel of the vehicle and,therefore,a lightweight is needed.The EO,GWO,and WOA algorithms are then utilized to optimize the BLDC motor’s design variables to minimize the motor’s total mass or maximize the motor efficiency by simultaneously satisfying the six inequality constraints.The simulation is carried out using MATLAB simulation software,and the simulation results prove the dominance of the proposed algorithms.This paper also suggests an efficient method from the proposed three methods for the BLDC motor design optimization problem. 展开更多
关键词 BLDC motor CONSTRAINED equilibrium optimizer singleobjective optimization
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ELMAN Neural Network with Modified Grey Wolf Optimizer for Enhanced Wind Speed Forecasting 被引量:5
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作者 M. Madhiarasan S. N. Deepa 《Circuits and Systems》 2016年第10期2975-2995,共21页
The scope of this paper is to forecast wind speed. Wind speed, temperature, wind direction, relative humidity, precipitation of water content and air pressure are the main factors make the wind speed forecasting as a ... The scope of this paper is to forecast wind speed. Wind speed, temperature, wind direction, relative humidity, precipitation of water content and air pressure are the main factors make the wind speed forecasting as a complex problem and neural network performance is mainly influenced by proper hidden layer neuron units. This paper proposes new criteria for appropriate hidden layer neuron unit’s determination and attempts a novel hybrid method in order to achieve enhanced wind speed forecasting. This paper proposes the following two main innovative contributions 1) both either over fitting or under fitting issues are avoided by means of the proposed new criteria based hidden layer neuron unit’s estimation. 2) ELMAN neural network is optimized through Modified Grey Wolf Optimizer (MGWO). The proposed hybrid method (ELMAN-MGWO) performance, effectiveness is confirmed by means of the comparison between Grey Wolf Optimizer (GWO), Adaptive Gbest-guided Gravitational Search Algorithm (GGSA), Artificial Bee Colony (ABC), Ant Colony Optimization (ACO), Cuckoo Search (CS), Particle Swarm Optimization (PSO), Evolution Strategy (ES), Genetic Algorithm (GA) algorithms, meanwhile proposed new criteria effectiveness and precise are verified comparison with other existing selection criteria. Three real-time wind data sets are utilized in order to analysis the performance of the proposed approach. Simulation results demonstrate that the proposed hybrid method (ELMAN-MGWO) achieve the mean square error AVG ± STD of 4.1379e-11 ± 1.0567e-15, 6.3073e-11 ± 3.5708e-15 and 7.5840e-11 ± 1.1613e-14 respectively for evaluation on three real-time data sets. Hence, the proposed hybrid method is superior, precise, enhance wind speed forecasting than that of other existing methods and robust. 展开更多
关键词 ELMAN Neural Network Modified Grey Wolf optimizer Hidden Layer Neuron Units Forecasting Wind Speed
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Distributed learning particle swarm optimizer for global optimization of multimodal problems 被引量:5
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作者 Geng ZHANG Yangmin LI Yuhui SHI 《Frontiers of Computer Science》 SCIE EI CSCD 2018年第1期122-134,共13页
Particle swarm optimizer (PSO) is an effective tool for solving many optimization problems. However, it may easily get trapped into local optimum when solving com- plex multimodal nonseparable problems. This paper p... Particle swarm optimizer (PSO) is an effective tool for solving many optimization problems. However, it may easily get trapped into local optimum when solving com- plex multimodal nonseparable problems. This paper presents a novel algorithm called distributed learning particle swarm optimizer (DLPSO) to solve multimodal nonseparable prob- lems. The strategy for DLPSO is to extract good vector infor- mation from local vectors which are distributed around the search space and then to form a new vector which can jump out of local optima and will be optimized further. Experimen- tal studies on a set of test functions show that DLPSO ex- hibits better performance in solving optimization problems with few interactions between variables than several other peer algorithms. 展开更多
关键词 particle swarm optimizer (PSO) orthogonal ex-perimental design (OED) swarm intelligence
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Oracle数据库性能优化策略 被引量:2
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作者 邵宁军 《计算机与现代化》 2003年第8期38-45,共8页
Oracle数据库应用系统性能优化是一个周而复始的系统工程。本文论述了Oracle数据库管理系统的一些基本工作原理,并分析了一些影响应用性能的可能因素,同时结合实际给出了一些可行的调整数据库应用性能的策略与方法。
关键词 ORACLE 数据库 性能优化策略 应用系统 数据库管理系统
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An optimized grey wolf optimizer based on a mutation operator and eliminating-reconstructing mechanism and its apphcation 被引量:7
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作者 Xiao-qing ZHANG Zheng-feng MING 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2017年第11期1705-1719,共15页
Due to its simplicity and ease of use, the standard grey wolf optimizer (GWO) is attracting much attention. However, due to its imperfect search structure and possible risk of being trapped in local optima, its appl... Due to its simplicity and ease of use, the standard grey wolf optimizer (GWO) is attracting much attention. However, due to its imperfect search structure and possible risk of being trapped in local optima, its application has been limited. To perfect the performance of the algorithm, an optimized GWO is proposed based on a mutation operator and eliminating-reconstructing mechanism (MR-GWO). By analyzing GWO, it is found that it conducts search with only three leading wolves at the core, and balances the exploration and exploitation abilities by adjusting only the parameter a, which means the wolves lose some diversity to some extent. Therefore, a mutation operator is introduced to facilitate better searching wolves, and an eliminating- reconstructing mechanism is used for the poor search wolves, which not only effectively expands the stochastic search, but also accelerates its convergence, and these two operations complement each other well. To verify its validity, MR-GWO is applied to the global optimization experiment of 13 standard continuous functions and a radial basis function (RBF) network approximation experiment. Through a comparison with other algorithms, it is proven that MR-GWO has a strong advantage. 展开更多
关键词 Swarm intelligence Grey wolf optimizer optimIZATION Radial basis function network
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PostgreSQL查询优化器分析研究 被引量:7
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作者 孙振兴 向阳 刘增宝 《计算机技术与发展》 2011年第8期141-144,共4页
作为开源数据库的代表,PostgreSQL的应用范围越来越广泛。文中的目的是研究PostgreSQL查询优化器的工作原理,介绍了PostgreSQL查询优化器的工作流程,分析了PostgreSQL查询优化器的工作原理,深入剖析了PostgreSQL查询优化器实现的具体细... 作为开源数据库的代表,PostgreSQL的应用范围越来越广泛。文中的目的是研究PostgreSQL查询优化器的工作原理,介绍了PostgreSQL查询优化器的工作流程,分析了PostgreSQL查询优化器的工作原理,深入剖析了PostgreSQL查询优化器实现的具体细节和采用的两种优化算法。结合图论中查找最小生成树的算法提出了改进策略,并简要论证了可行性。研究发现,PostgreSQL查询优化器可以处理任意复杂的请求,并能尽快地给出比较合理的执行路径。 展开更多
关键词 POSTGRESQL 查询优化 System-R 基因优化
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