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孔隙网络模型法计算气液体系吸吮过程相对渗透率 被引量:12
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作者 王金勋 吴晓东 +1 位作者 杨普华 李贤兵 《天然气工业》 EI CAS CSCD 北大核心 2003年第3期8-11,共4页
针对实验法难以直接测定气液体系吸吮过程相对渗透率曲线的问题 ,利用驱替过程相对渗透率实验资料 ,通过孔隙网络模型确定合适的孔隙结构参数 ,然后再由网络模型计算吸吮过程的相对渗透率曲线。利用文献中一油气体系的实验资料进行了初... 针对实验法难以直接测定气液体系吸吮过程相对渗透率曲线的问题 ,利用驱替过程相对渗透率实验资料 ,通过孔隙网络模型确定合适的孔隙结构参数 ,然后再由网络模型计算吸吮过程的相对渗透率曲线。利用文献中一油气体系的实验资料进行了初步验算 ,由一实际储层岩样的气驱水实验数据 。 展开更多
关键词 孔隙网络模型法 计算 气液体系 吸吮过程 相对渗透率 水驱气 采气
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计及IGBT模块键合线与芯片焊料层老化的热网络法结温计算 被引量:1
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作者 何梦宇 许智亮 +2 位作者 谢望玉 葛兴来 王为介 《铁道机车车辆》 北大核心 2024年第4期28-35,共8页
文中提出一种计及IGBT模块键合线与芯片焊料层老化的热网络法结温计算,基于Simulink对短时间尺度下损耗与结温的相互依赖关系进行更新,并分别通过双脉冲测试及有限元仿真修正长时间尺度下键合线与芯片焊料层老化对IGBT结温计算的影响,... 文中提出一种计及IGBT模块键合线与芯片焊料层老化的热网络法结温计算,基于Simulink对短时间尺度下损耗与结温的相互依赖关系进行更新,并分别通过双脉冲测试及有限元仿真修正长时间尺度下键合线与芯片焊料层老化对IGBT结温计算的影响,在此基础上,根据芯片焊料层不同老化状态下键合线的应力特征,实现两种老化模式的相互关联,较为准确地计算IGBT结温。最终利用试验平台与传统结温计算方法进行对比验证了所提结温计算方法的准确性。该结温计算方法有助于在实际运行工况及IGBT模块老化状态下精确计算结温。 展开更多
关键词 IGBT结温计算 网络模型法 模块老化 双脉冲试验 有限元仿真
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用网络模型PERT技术对工程项目工期进度进行风险评价 被引量:6
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作者 李兵 陈晓宇 《建筑施工》 2005年第5期77-78,81,共3页
论述通过网络模型法中计划评审技术(PERT),对实例项目进行风险评价,该方法既方便又操作性强,值得广泛应用。
关键词 网络模型法 PERT技术 项目 风险评价
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基于烟羽模型法对开放式小区的宏观评价 被引量:1
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作者 邢锐 薛莹 +1 位作者 黄江浩 王玲 《华北理工大学学报(自然科学版)》 CAS 2017年第2期120-124,共5页
建设开放式小区,推行社区"街区化"成为社会各界关注的热点问题,有策略地将小区开放能够缓解社区周围道路的交通压力,优化城市路网结构。然而,现阶段研究大多致力于讨论开放型小区的优点,对某类型小区是否适宜开放的研究不足,... 建设开放式小区,推行社区"街区化"成为社会各界关注的热点问题,有策略地将小区开放能够缓解社区周围道路的交通压力,优化城市路网结构。然而,现阶段研究大多致力于讨论开放型小区的优点,对某类型小区是否适宜开放的研究不足,为了解决这一问题,通过考虑如小区内部结构、内部道路网总里程、小区位置、周围路况等小区规模参数,基于烟羽模型法从宏观层面评价了不同规模的小区开放后对周围道路交通的影响程度。结果表明,在推进"街区化"的进程中,优先开放大规模社区对周围道路交通状况具有更大的影响。 展开更多
关键词 开放式小区 烟羽模型 网络节点模型 宏观评价
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Simultaneous Identification of Thermophysical Properties of Semitransparent Media Using a Hybrid Model Based on Artificial Neural Network and Evolutionary Algorithm
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作者 LIU Yang HU Shaochuang 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2024年第4期458-475,共18页
A hybrid identification model based on multilayer artificial neural networks(ANNs) and particle swarm optimization(PSO) algorithm is developed to improve the simultaneous identification efficiency of thermal conductiv... A hybrid identification model based on multilayer artificial neural networks(ANNs) and particle swarm optimization(PSO) algorithm is developed to improve the simultaneous identification efficiency of thermal conductivity and effective absorption coefficient of semitransparent materials.For the direct model,the spherical harmonic method and the finite volume method are used to solve the coupled conduction-radiation heat transfer problem in an absorbing,emitting,and non-scattering 2D axisymmetric gray medium in the background of laser flash method.For the identification part,firstly,the temperature field and the incident radiation field in different positions are chosen as observables.Then,a traditional identification model based on PSO algorithm is established.Finally,multilayer ANNs are built to fit and replace the direct model in the traditional identification model to speed up the identification process.The results show that compared with the traditional identification model,the time cost of the hybrid identification model is reduced by about 1 000 times.Besides,the hybrid identification model remains a high level of accuracy even with measurement errors. 展开更多
关键词 semitransparent medium coupled conduction-radiation heat transfer thermophysical properties simultaneous identification multilayer artificial neural networks(ANNs) evolutionary algorithm hybrid identification model
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Combining the genetic algorithms with artificial neural networks for optimization of board allocating 被引量:2
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作者 曹军 张怡卓 岳琪 《Journal of Forestry Research》 SCIE CAS CSCD 2003年第1期87-88,共2页
This paper introduced the Genetic Algorithms (GAs) and Artificial Neural Networks (ANNs), which have been widely used in optimization of allocating. The combination way of the two optimizing algorithms was used in boa... This paper introduced the Genetic Algorithms (GAs) and Artificial Neural Networks (ANNs), which have been widely used in optimization of allocating. The combination way of the two optimizing algorithms was used in board allocating of furniture production. In the experiment, the rectangular flake board of 3650 mm 1850 mm was used as raw material to allocate 100 sets of Table Bucked. The utilizing rate of the board reached 94.14 % and the calculating time was only 35 s. The experiment result proofed that the method by using the GA for optimizing the weights of the ANN can raise the utilizing rate of the board and can shorten the time of the design. At the same time, this method can simultaneously searched in many directions, thus greatly in-creasing the probability of finding a global optimum. 展开更多
关键词 Artificial neural network Genetic algorithms Back propagation model (BP model) OPTIMIZATION
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大型波导纵缝阵列天线的分析与设计 被引量:8
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作者 李 龙 张 玉 +1 位作者 李建瀛 梁昌洪 《微波学报》 CSCD 北大核心 2002年第1期11-14,共4页
本文利用矩量法和等效网络法对矩形波导宽边纵缝阵列进行了精确的理论分析,严格计算阵中缝隙的内部和外部互耦,并利用等效网络法提取阵中缝隙的等效导纳特性。在此基础上,提出模型阵列和模型缝隙的大型波导缝隙阵的设计方法.理论结... 本文利用矩量法和等效网络法对矩形波导宽边纵缝阵列进行了精确的理论分析,严格计算阵中缝隙的内部和外部互耦,并利用等效网络法提取阵中缝隙的等效导纳特性。在此基础上,提出模型阵列和模型缝隙的大型波导缝隙阵的设计方法.理论结果与实验比较吻合。 展开更多
关键词 矩量 等效网络 波导缝隙阵 模型阵列 模型缝隙
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CCM模式下非理想Buck变换器的建模与仿真 被引量:12
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作者 宣传 徐慧芳 解光军 《电子器件》 CAS 北大核心 2012年第1期70-74,共5页
首先运用能量守恒原理将非理想型Buck变换器进行理想化转换;然后,就转换后的电路根据开关网络平均模型法建立平均变量模型,从而得到Buck变换器的大信号平均等效电路、直流等效电路和交流小信号等效电路,进而进行稳态和动态小信号特性分... 首先运用能量守恒原理将非理想型Buck变换器进行理想化转换;然后,就转换后的电路根据开关网络平均模型法建立平均变量模型,从而得到Buck变换器的大信号平均等效电路、直流等效电路和交流小信号等效电路,进而进行稳态和动态小信号特性分析;接着在此基础上,设计补偿网络,实现闭环控制;最后借助MATLAB软件进行仿真,与补偿前的仿真图形进行比较分析得出结论。 展开更多
关键词 BUCK变换器 能量守恒 开关网络平均模型 补偿网络
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The Research on Social Networks Public Opinion Propagation Influence Models and Its Controllability 被引量:10
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作者 Lejun Zhang Tong Wang +3 位作者 Zilong Jin Nan Su Chunhui Zhao Yongjun He 《China Communications》 SCIE CSCD 2018年第7期98-110,共13页
Public opinion propagation control is one of the hot topics in contemporary social network research. With the rapid dissemination of information over the Internet, the traditional isolation and vaccination strategies ... Public opinion propagation control is one of the hot topics in contemporary social network research. With the rapid dissemination of information over the Internet, the traditional isolation and vaccination strategies can no longer achieve satisfactory results. A positive guidance technology for public opinion diffusion is urgently needed. First, based on the analysis of influence network controllability and public opinion diffusion, a positive guidance technology is proposed and a new model that supports external control is established. Second, in combination with the influence network, a public opinion propagation influence network model is designed and a public opinion control point selection algorithm(POCDNSA) is proposed. Finally, An experiment verified that this algorithm can lead to users receiving the correct guidance quickly and accurately, reducing the impact of false public opinion information; the effect of CELF is no better than that of the POCDNSA algorithm. The main reason is that the former is completely based on the diffusion cascade information contained in the training data, but does not consider the specific situation of the network structure and the diffusion of public opinion information in the closed set. thus, the effectiveness and feasibility of the algorithm is proven. The findings of this article therefore provide useful insights for the implementation of public opinion control. 展开更多
关键词 social network public opinion propagation control influence network
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An Iterative Clustering-Based Localization Algorithm for Wireless Sensor Networks 被引量:1
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作者 罗海勇 李慧 +1 位作者 赵方 彭金华 《China Communications》 SCIE CSCD 2011年第1期58-64,共7页
In wireless sensor networks,node localization is a fundamental middleware service.In this paper,a robust and accurate localization algorithm is proposed,which uses a novel iterative clustering model to obtain the most... In wireless sensor networks,node localization is a fundamental middleware service.In this paper,a robust and accurate localization algorithm is proposed,which uses a novel iterative clustering model to obtain the most representative intersection points between every two circles and use them to estimate the position of unknown nodes.Simulation results demonstrate that the proposed algorithm outperforms other localization schemes (such as Min-Max,etc.) in accuracy,scalability and gross error tolerance. 展开更多
关键词 wireless sensor network node localization iterative clustering model
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Caching Algorithm with a Novel Cost Model to Deliver Content and Its Interest over Content Centric Networks 被引量:1
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作者 SU Zhou FANG Dongfeng HAN Bo 《China Communications》 SCIE CSCD 2015年第7期23-30,共8页
Recently the content centric networks(CCNs) have been advocated as a new solution to design future networks. In the CCNs, content and its interest are delivered over the content store and pending interest table, respe... Recently the content centric networks(CCNs) have been advocated as a new solution to design future networks. In the CCNs, content and its interest are delivered over the content store and pending interest table, respectively, where both have limited capacities. Therefore, how to design the corresponding algorithms to efficiently deliver content and inertest over them becomes an important issue. In this paper, based on the analysis of content distribution, status of content store, and pending interest, we propose a novel caching algorithm with which the resources of content store and pending interest table can be efficiently used. Simulation results prove that the proposal can outperform the conventional methods. 展开更多
关键词 content centric networks content delivery CACHING future networks
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A New Evaluation Algorithm for the Influence of User in Social Network 被引量:6
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作者 JIANG Wei GAO Mengdi +1 位作者 WANG Xiaoxi WU Xianda 《China Communications》 SCIE CSCD 2016年第2期200-206,共7页
Online social networks have gradually permeated into every aspect of people's life.As a research hotspot in social network, user influence is of theoretical and practical significant for information transmission, ... Online social networks have gradually permeated into every aspect of people's life.As a research hotspot in social network, user influence is of theoretical and practical significant for information transmission, optimization and integration. A prominent application is a viral marketing campaign which aims to use a small number of targeted infl uence users to initiate cascades of infl uence that create a global increase in product adoption. In this paper, we analyze mainly evaluation methods of user infl uence based on IDM evaluation model, Page Rank evaluation model, use behavior model and some other popular influence evaluation models in currently social network. And then, we extract the core idea of these models to build our influence evaluation model from two aspects, relationship and activity. Finally, the proposed approach was validated on real world datasets,and the result of experiments shows that our method is both effective and stable. 展开更多
关键词 social networks INFLUENCE opinionleaders
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Parallelized Jaccard-Based Learning Method and MapReduce Implementation for Mobile Devices Recognition from Massive Network Data 被引量:2
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作者 刘军 李银周 +2 位作者 Felix Cuadrado Steve Uhlig 雷振明 《China Communications》 SCIE CSCD 2013年第7期71-84,共14页
The ability of accurate and scalable mobile device recognition is critically important for mobile network operators and ISPs to understand their customers' behaviours and enhance their user experience.In this pape... The ability of accurate and scalable mobile device recognition is critically important for mobile network operators and ISPs to understand their customers' behaviours and enhance their user experience.In this paper,we propose a novel method for mobile device model recognition by using statistical information derived from large amounts of mobile network traffic data.Specifically,we create a Jaccardbased coefficient measure method to identify a proper keyword representing each mobile device model from massive unstructured textual HTTP access logs.To handle the large amount of traffic data generated from large mobile networks,this method is designed as a set of parallel algorithms,and is implemented through the MapReduce framework which is a distributed parallel programming model with proven low-cost and high-efficiency features.Evaluations using real data sets show that our method can accurately recognise mobile client models while meeting the scalability and producer-independency requirements of large mobile network operators.Results show that a 91.5% accuracy rate is achieved for recognising mobile client models from 2 billion records,which is dramatically higher than existing solutions. 展开更多
关键词 mobile device recognition data mining Jaccard coefficient measurement distributed computing MAPREDUCE
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A BOD-DO coupling model for water quality simulation by artificial neural network
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作者 郭劲松 LONG +1 位作者 Tengrui 《Journal of Chongqing University》 CAS 2002年第2期46-49,共4页
A one-dimensional BOD-DO coupling model for water quality simulation is presented, which adopts Streeter-Phelps equations and the theory of back-propagation artificial neural network. The water quality data of Yangtze... A one-dimensional BOD-DO coupling model for water quality simulation is presented, which adopts Streeter-Phelps equations and the theory of back-propagation artificial neural network. The water quality data of Yangtze River in the Chongqing region in the year of 1989 are divided into 5 groups and used in the learning and testing courses of this model. The result shows that such model is feasible for water quality simulation and is more accurate than traditional models. 展开更多
关键词 water quality simulation artificial neural network B-P algorithm
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