期刊文献+
共找到141篇文章
< 1 2 8 >
每页显示 20 50 100
The Cox-Aalen Models as Framework for Construction of Bivariate Probability Distributions, Universal Representation 被引量:1
1
作者 Jerzy K. Filus 《Journal of Statistical Science and Application》 2017年第2期56-63,共8页
Starting with the Aalen (1989) version of Cox (1972) 'regression model' we show the method for construction of "any" joint survival function given marginal survival functions. Basically, however, we restrict o... Starting with the Aalen (1989) version of Cox (1972) 'regression model' we show the method for construction of "any" joint survival function given marginal survival functions. Basically, however, we restrict ourselves to model positive stochastic dependences only with the general assumption that the underlying two marginal random variables are centered on the set of nonnegative real values. With only these assumptions we obtain nice general characterization of bivariate probability distributions that may play similar role as the copula methodology. Examples of reliability and biomedical applications are given. 展开更多
关键词 Cox model Aalen additive hazards model construction of bivariate probability distributions givenmarginal distributions "joiner" as dependence function "connecting" the marginals general characterization ofbivariate distributions similarity to the copula methodology reliability and biomedical applications
在线阅读 下载PDF
Fault-tolerant distributed fusion of PDFs using KLDs-induced functional FCM clustering
2
作者 Zheng WEI Zhansheng DUAN 《Chinese Journal of Aeronautics》 2025年第7期493-506,共14页
In distributed fusion,when one or more sensors are disturbed by faults,a common problem is that their local estimations are inconsistent with those of other fault-free sensors.Most of the existing fault-tolerant distr... In distributed fusion,when one or more sensors are disturbed by faults,a common problem is that their local estimations are inconsistent with those of other fault-free sensors.Most of the existing fault-tolerant distributed fusion algorithms,such as the Covariance Union(CU)and Faulttolerant Generalized Convex Combination(FGCC),are only used for the point estimation case where local estimates and their associated error covariances are provided.A treatment with focus on the fault-tolerant distributed fusions of arbitrary local Probability Density Functions(PDFs)is lacking.For this problem,we first propose Kullback–Leibler Divergence(KLD)and reversed KLD induced functional Fuzzy c-Means(FCM)clustering algorithms to soft cluster all local PDFs,respectively.On this basis,two fault-tolerant distributed fusion algorithms of arbitrary local PDFs are then developed.They select the representing PDF of the cluster with the largest sum of memberships as the fused PDF.Numerical examples verify the better fault tolerance of the developed two distributed fusion algorithms. 展开更多
关键词 Distributed fusion Fault tolerance probability Density function(pdf) functional fuzzy c-means clustering Kullback-Leibler Divergence(KLD)
原文传递
Developing theory of probability density function for stochastic modeling of turbulent gas-particle flows
3
作者 Lixing ZHOU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2018年第7期1019-1030,共12页
Turbulent gas-particle flows are studied by a kinetic description using a prob- ability density function (PDF). Unlike other investigators deriving the particle Reynolds stress equations using the PDF equations, the... Turbulent gas-particle flows are studied by a kinetic description using a prob- ability density function (PDF). Unlike other investigators deriving the particle Reynolds stress equations using the PDF equations, the particle PDF transport equations are di- rectly solved either using a finite-difference method for two-dimensional (2D) problems or using a Monte-Carlo (MC) method for three-dimensional (3D) problems. The proposed differential stress model together with the PDF (DSM-PDF) is used to simulate turbulent swirling gas-particle flows. The simulation results are compared with the experimental results and the second-order moment (SOM) two-phase modeling results. All of these simulation results are in agreement with the experimental results, implying that the PDF approach validates the SOM two-phase turbulence modeling. The PDF model with the SOM-MC method is used to simulate evaporating gas-droplet flows, and the simulation results are in good agreement with the experimental results. 展开更多
关键词 probability density functionpdfmodeling turbulent flow gas-particleflow
在线阅读 下载PDF
Reconstruction of Probability Density Function for Gamma Distribution
4
作者 FAN Jinwei LI Zhongsheng TIAN Bin 《Journal of Donghua University(English Edition)》 EI CAS 2020年第4期327-333,共7页
The probability distributions of small sample data are difficult to determine,while a large proportion of samples occur in the early failure period,so it is particularly important to make full use of these data in the... The probability distributions of small sample data are difficult to determine,while a large proportion of samples occur in the early failure period,so it is particularly important to make full use of these data in the statistical analysis.Based on gamma distribution,four methods of probability density function(PDF)reconstruction with early failure data are proposed,and then the mean time between failures(MTBF)evaluation expressions are concluded from the reconstructed PDFs.Both theory analysis and an example show that method 2 is the best evaluation method in dealing with early-failure-small-sample data.The reconstruction methods of PDF also have certain guiding significance for other distribution types. 展开更多
关键词 small sample probability density function(pdf) gamma distribution early failure mean time between failures(MTBF)
在线阅读 下载PDF
Identification of Neuro-Fuzzy Hammerstein Model Based on Probability Density Function
5
作者 方甜莲 贾立 《Journal of Donghua University(English Edition)》 EI CAS 2016年第5期703-707,共5页
A new identification method of neuro-uzzy Hammerstein model based on probability density function(PDF) is presented,which is different from the idea that mean squared error(MSE) is employed as the index function in tr... A new identification method of neuro-uzzy Hammerstein model based on probability density function(PDF) is presented,which is different from the idea that mean squared error(MSE) is employed as the index function in traditional identification methods.Firstly,a neuro-fuzzy based Hammerstein model is constructed to describe the nonlinearity of Hammerstein process without any prior process knowledge.Secondly,a kind of special test signal is used to separate the link parts of the Hammerstein model.More specifically,the conception of PDF is introduced to solve the identification problem of the neuro-fuzzy Hammerstein model.The antecedent parameters are estimated by a clustering algorithm,while the consequent parameters of the model are identified by designing a virtual PDF control system in which the PDF of the modeling error is estimated and controlled to converge to the target.The proposed method not only guarantees the accuracy of the model but also dominates the spatial distribution of PDF of the model error to improve the generalization ability of the model.Simulated results show the effectiveness of the proposed method. 展开更多
关键词 probability clustering guarantees separate converge prior generalization conception squared nonlinearity
在线阅读 下载PDF
A Novel Statistical Delay Model Based on the Birnbaum-Saunders Distribution for RLC Interconnects in 90nm Technologies
6
作者 周磊 孙玲玲 蒋立飞 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第7期1313-1317,共5页
For performance optimization such as placement,interconnect synthesis,and routing, an efficient and accurate interconnect delay metric is critical,even in design tools development like design for yield (DFY) and des... For performance optimization such as placement,interconnect synthesis,and routing, an efficient and accurate interconnect delay metric is critical,even in design tools development like design for yield (DFY) and design for manufacture (DFM). In the nanometer regime, the recently proposed delay models for RLC interconnects based on statistical probability density function (PDF)interpretation such as PRIMO,H-gamma,WED and RLD bridge the gap between accuracy and efficiency. However, these models always require table look-up when operating. In this paper, a novel delay model based on the Birnbaum-Saunders distribution (BSD) is presented. BSD can accomplish interconnect delay estimation fast and accurately without table look-up operations. Furthermore, it only needs the first two moments to match. Experimental results in 90nm technology show that BSD is robust, easy to implement,efficient,and accurate. 展开更多
关键词 delay model INTERCONNECT MOMENT probability distribution function
在线阅读 下载PDF
Computational Precision of the Power Function for Conditional Tests of Assumptions of the Rasch Model
7
作者 Clemens Draxler Jan Philipp Nolte 《Open Journal of Statistics》 2018年第6期873-884,共12页
Draxler and Zessin [1] derived the power function for a class of conditional tests of assumptions of a psychometric model known as the Rasch model and suggested an MCMC approach developed by Verhelst [2] for the numer... Draxler and Zessin [1] derived the power function for a class of conditional tests of assumptions of a psychometric model known as the Rasch model and suggested an MCMC approach developed by Verhelst [2] for the numerical approximation of the power of the tests. In this contribution, the precision of the Verhelst approach is investigated and compared with an exact sampling procedure proposed by Miller and Harrison [3] for which the discrete probability distribution to be sampled from is exactly known. Results show no substantial differences between the two numerical procedures and quite accurate power computations. Regarding the question of computing time the Verhelst approach will have to be considered much more efficient. 展开更多
关键词 CONDITIONAL Tests CONDITIONAL probability distribution HYPERGEOMETRIC distribution Power function RANDOM Sampling RASCH model
在线阅读 下载PDF
基于λ-PDF和一次二阶矩的不确定性反求方法 被引量:8
8
作者 刘杰 许灿 +2 位作者 李凡 刘光昭 王先一 《机械工程学报》 EI CAS CSCD 北大核心 2015年第20期135-143,共9页
为了有效评价测量响应中不确定性对结构参量识别结果的影响,提出一种基于λ概率密度函数(Probability distribution function,PDF)和一次二阶矩的不确定性计算反求方法。采用二次衍生λ-PDF对待识不确定性参量的PDF进行建模。内层通过... 为了有效评价测量响应中不确定性对结构参量识别结果的影响,提出一种基于λ概率密度函数(Probability distribution function,PDF)和一次二阶矩的不确定性计算反求方法。采用二次衍生λ-PDF对待识不确定性参量的PDF进行建模。内层通过对参量呈λ-PDF的功能函数采用一次二阶矩法进行正问题求解,得到计算响应的概率分布;外层通过最小化测量响应与计算响应之间的概率分布特征量将不确定性反问题转化为确定性的最优化问题,并用隔代映射遗传算法识别未知参量λ-PDF的参数。本方法不仅有效地实现了结构未知参量PDF的估计,而且与传统基于抽样的统计方法相比,计算效率较高。数值算例和工程应用验证了本方法的可行性和有效性。 展开更多
关键词 不确定性反问题 一次二阶矩 λ-pdf 参数识别 概率密度函数(probability distribution function pdf)估计
在线阅读 下载PDF
考虑化学反应的标量耗散率及其在PDF小尺度混合模型中的应用 被引量:5
9
作者 李艺 黄鹰 +1 位作者 陈义良 董刚 《燃烧科学与技术》 EI CAS CSCD 2002年第1期69-74,共6页
在 Sanders和 Borghi工作的基础上 ,推导出考虑化学反应的标量耗散率和标量时间尺度 ,在标量的联合概率密度函数方程的小尺度混合模型中采用考虑化学反应的标量的时间尺度 ,结合求解流场的 k- ε模型对甲烷轴对称射流扩散火焰进行了计... 在 Sanders和 Borghi工作的基础上 ,推导出考虑化学反应的标量耗散率和标量时间尺度 ,在标量的联合概率密度函数方程的小尺度混合模型中采用考虑化学反应的标量的时间尺度 ,结合求解流场的 k- ε模型对甲烷轴对称射流扩散火焰进行了计算 ,最后分析了标量时间尺度对小尺度混合模型 (IEM模型 )和计算结果的影响。 展开更多
关键词 标量时间尺度 概率密度函数 小尺度混合模型 标量耗散率 化学反应 κ-ε模型 IEM模型 pdf
在线阅读 下载PDF
基于建模误差PDF形状的间歇过程数据驱动模型 被引量:9
10
作者 贾立 曹鲁明 邱铭森 《仪器仪表学报》 EI CAS CSCD 北大核心 2012年第7期1505-1512,共8页
间歇过程的优化控制依赖于过程精确的数学模型,数据驱动的建模方法是目前间歇过程模型研究中的热点问题。突破传统数据驱动建模方法中采用均方差(mean squared error,MSE)作为准则函数的思想,提出一种新颖的间歇过程数据驱动建模方法,... 间歇过程的优化控制依赖于过程精确的数学模型,数据驱动的建模方法是目前间歇过程模型研究中的热点问题。突破传统数据驱动建模方法中采用均方差(mean squared error,MSE)作为准则函数的思想,提出一种新颖的间歇过程数据驱动建模方法,引入了概率密度函数(probability density function,PDF)控制的概念,构造间歇过程模型误差控制系统,将模型的可调参数作为控制系统的输入,模型误差PDF的形状作为控制系统的输出,从而把开环模型参数辨识问题转化为模型误差PDF形状的闭环控制问题。通过可调参数控制模型误差PDF的空间分布状态,不仅能够保障模型精度,还可控制模型误差的空间分布状态,从而消除模型中的有色噪声。仿真实验表明,基于模型误差PDF形状的间歇过程数据驱动模型具有较好的建模精度、鲁棒性和泛化能力,为间歇过程的数据驱动建模提供了一条新途径。 展开更多
关键词 间歇过程 输出pdf控制 数据驱动模型
在线阅读 下载PDF
Establishment Method of a Mixture Model and Its Practical Application for Transmission Gears in an Engineering Vehicle 被引量:6
11
作者 WANG Jixin WANG Zhenyu +3 位作者 YU Xiangjun YAO Mingyao YAO Zongwei ZHANG Erping 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2012年第5期1001-1010,共10页
Highly versatile machines, such as wheel loaders, forklifts, and mining haulers, are subject to many kinds of working conditions, as well as indefinite factors that lead to the complexity of the load. The load probabi... Highly versatile machines, such as wheel loaders, forklifts, and mining haulers, are subject to many kinds of working conditions, as well as indefinite factors that lead to the complexity of the load. The load probability distribution function (PDF) of transmission gears has many distributions centers; thus, its PDF cannot be well represented by just a single-peak function. For the purpose of representing the distribution characteristics of the complicated phenomenon accurately, this paper proposes a novel method to establish a mixture model. Based on linear regression models and correlation coefficients, the proposed method can be used to automatically select the best-fitting function in the mixture model. Coefficient of determination, the mean square error, and the maximum deviation are chosen and then used as judging criteria to describe the fitting precision between the theoretical distribution and the corresponding histogram of the available load data. The applicability of this modeling method is illustrated by the field testing data of a wheel loader. Meanwhile, the load spectra based on the mixture model are compiled. The comparison results show that the mixture model is more suitable for the description of the load-distribution characteristics. The proposed research improves the flexibility and intelligence of modeling, reduces the statistical error and enhances the fitting accuracy, and the load spectra complied by this method can better reflect the actual load characteristic of the gear component. 展开更多
关键词 mixture distribution model probability distribution function correlation coefficient load spectra wheel loader
在线阅读 下载PDF
Enhancement of density divergence in an insect outbreak model driven by colored noise
12
作者 肖荣 王参军 张林 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第11期121-125,共5页
The steady states and the transient properties of an insect outbreak model driven by Gaussian colored noise are studied in this paper. According to the Fokker-Planck equation in the unified colored-noise approximation... The steady states and the transient properties of an insect outbreak model driven by Gaussian colored noise are studied in this paper. According to the Fokker-Planck equation in the unified colored-noise approximation, we analyse the stationary probability distribution and the mean first-passage time of this model. By numerical analysis, the effects of the self-correlation time of insect birth rate and predation rate respectively reveal a manifest population divergence on the insect density. The decrease of the mean first-passage time indicates an enhancement dynamic on the density divergency with colored noise of a large self-correlation time based on the insect outbreak model. 展开更多
关键词 colored noise insect outbreak model stationary probability distribution function meanfirst-passage time
原文传递
On the Relationship between Statistical and Phenomenological Models of the Thermodynamic Systems
13
作者 Igor Samkhan 《Journal of Modern Physics》 2013年第7期38-44,共7页
The paper deals with the performing of a critical analysis of the problems arising in matching the classical models of the statistical and phenomenological thermodynamics. The performed analysis shows that some concep... The paper deals with the performing of a critical analysis of the problems arising in matching the classical models of the statistical and phenomenological thermodynamics. The performed analysis shows that some concepts of the statistical and phenomenological methods of describing the classical systems do not quite correlate with each other. Particularly, in these methods various caloric ideal gas equations of state are employed, while the possibility existing in the thermodynamic cyclic processes to obtain the same distributions both due to a change of the particle concentration and owing to a change of temperature is not allowed for in the statistical methods. The above-mentioned difference of the equations of state is cleared away when using in the statistical functions corresponding to the canonical Gibbs equations instead of the Planck’s constant a new scale factor that depends on the parameters of a system and coincides with the Planck’s constant in going of the system to the degenerate state. Under such an approach, the statistical entropy is transformed into one of the forms of heat capacity. In its turn, the agreement of the methods under consideration in the question as to the dependence of the molecular distributions on the concentration of particles, apparently, will call for further refinement of the physical model of ideal gas and the techniques for its statistical description. 展开更多
关键词 THERMODYNAMICS CLASSICAL Systems DESCRIPTION models STATISTICAL functions Phase Space probability distribution Particle Concentration
暂未订购
Reverse Monte Carlo Modeling of the Rigidity Percolation Threshold in Ge<SUB>x</SUB>Se<SUB>1-x</SUB>Glassy Networks
14
作者 Moneeb T. M. Shatnawi 《New Journal of Glass and Ceramics》 2015年第3期31-43,共13页
Based on Maxwell’s constraint counting theory, rigidity percolation in GexSe1-x glasses occurs when the mean coordination number reaches the value of 2.4. This corresponds to Ge0.20Se0.80 glass. At this composition, ... Based on Maxwell’s constraint counting theory, rigidity percolation in GexSe1-x glasses occurs when the mean coordination number reaches the value of 2.4. This corresponds to Ge0.20Se0.80 glass. At this composition, the number of constraints experienced by an atom equals the number of degrees of freedom in three dimensions. Hence, at this composition, the network changes from a floppy phase to a rigid phase, and rigidity starts to percolate. In this work, we use reverse Monte Carlo (RMC) modeling to model the structure of Ge0.20Se0.80 glass by simulating its experimental total atomic pair distribution function (PDF) obtained via high energy synchrotron radiation. A three-dimensional configuration of 2836 atoms was obtained, from which we extracted the partial atomic pair distribution functions associated with Ge-Ge, Ge-Se and Se-Se real space correlations that are hard to extract experimentally from total scattering methods. Bond angle distributions, coordination numbers, mean coordination numbers and the number of floppy modes were also extracted and discussed. More structural insights about network topology at this composition were illustrated. The results indicate that in Ge0.20Se0.80 glass, Ge atoms break up and cross-link the Se chain structure, and form structural units that are four-fold coordinated (the GeSe4 tetrahedra). These tetrahedra form the basic building block and are connected via shared Se atoms or short Se chains. The extent of the intermediate ranged oscillations in real space (as extracted from the width of the first sharp diffraction peak) was found to be around 19.6 ?. The bonding schemes in this glass are consistent with the so-called “8-N” rule and can be interpreted in terms of a chemically ordered network model. 展开更多
关键词 Chalcogenide GLASSES Rigidity PERCOLATION Reverse Monte Carlo modeling Atomic Pair distribution function (pdf) GexSe1-x GLASSES
暂未订购
Bridging Classical and Quantum Realms: The Conceptual and Theoretical Framework of the Advanced Observer Model
15
作者 Joseph H. C. Wong 《Journal of Quantum Information Science》 2024年第4期123-157,共35页
This paper presents the Advanced Observer Model (AOM), a groundbreaking conceptual framework designed to clarify the complex and often enigmatic nature of quantum mechanics. The AOM serves as a metaphorical lens, brin... This paper presents the Advanced Observer Model (AOM), a groundbreaking conceptual framework designed to clarify the complex and often enigmatic nature of quantum mechanics. The AOM serves as a metaphorical lens, bringing the elusive quantum realm into sharper focus by transforming its inherent uncertainty into a coherent, structured ‘Frame Stream’ that aids in the understanding of quantum phenomena. While the AOM offers conceptual simplicity and clarity, it recognizes the necessity of a rigorous theoretical foundation to address the fundamental uncertainties that lie at the core of quantum mechanics. This paper seeks to illuminate those theoretical ambiguities, bridging the gap between the abstract insights of the AOM and the intricate mathematical foundations of quantum theory. By integrating the conceptual clarity of the AOM with the theoretical intricacies of quantum mechanics, this work aspires to deepen our understanding of this fascinating and elusive field. 展开更多
关键词 Advanced Observer model AOM DETERMINACY INDETERMINACY Reverse Engineering Observer-Observed Interaction Quantum Wave function probability Density function pdf probability Space Potential Space Quantum Computing Quantum Information Processing Static Configuration SC Dynamic Configuration DC Sequence of Quantum States SQS Perceptual Sequence of Observations PSO Theory of Relativity Lorentz Transformation
在线阅读 下载PDF
具有医疗资源有限和Ornstein-Uhlenbeck过程的随机SIR传染病模型研究
16
作者 刘晓虎 曹虹 聂麟飞 《应用数学》 北大核心 2025年第1期170-181,共12页
基于医疗资源的有限性和疾病的传播规律,提出一类具有Ornstein-Uhlenbeck过程和一般发生率的随机SIR传染病模型.首先,讨论模型全局正解的存在唯一性并给出疾病灭绝性的充分条件.其次,通过构造合适的Lyapunov函数并应用It^o公式等方法,... 基于医疗资源的有限性和疾病的传播规律,提出一类具有Ornstein-Uhlenbeck过程和一般发生率的随机SIR传染病模型.首先,讨论模型全局正解的存在唯一性并给出疾病灭绝性的充分条件.其次,通过构造合适的Lyapunov函数并应用It^o公式等方法,得到模型平稳分布的存在性.此外,通过求解Fokker-Planck方程,给出模型在拟地方病平衡点附近的密度函数的具体形式.最后通过数值模拟解释主要的理论结果并探讨随机扰动对疾病传播的影响. 展开更多
关键词 随机传染病模型 医疗资源有限 灭绝性 平稳分布 概率密度函数
在线阅读 下载PDF
求解多模概率分布Gamma混合模型的半EM算法
17
作者 陈佳琪 何玉林 +1 位作者 成英超 黄哲学 《计算机应用》 北大核心 2025年第7期2153-2161,共9页
期望最大化(EM)算法在混合模型参数估计中发挥着重要作用,然而现有的EM算法在求解Gamma混合模型(GaMM)参数时存在局限性,主要体现在因近似计算导致的低质量参数估计,以及由于大量数值计算造成的计算效率低下问题。为了克服这些局限,并... 期望最大化(EM)算法在混合模型参数估计中发挥着重要作用,然而现有的EM算法在求解Gamma混合模型(GaMM)参数时存在局限性,主要体现在因近似计算导致的低质量参数估计,以及由于大量数值计算造成的计算效率低下问题。为了克服这些局限,并充分利用数据的多模性质,提出一种半EM(Semi-EM)算法求解用于估计多模概率分布的GaMM。首先,通过聚类探测数据的空间分布特性,以初始化GaMM参数,进而更准确地刻画数据的多模性;其次,在EM算法框架的基础上,对于缺乏封闭更新表达式而导致的参数更新困难问题,采用自定义的启发式策略对GaMM形状参数进行更新,使它们朝着最大化对数似然值的方向逐步调整,同时以封闭形式更新其他参数。经过一系列具有说服力的实验,验证了Semi-EM算法的可行性、合理性和有效性。实验结果表明,Semi-EM算法在精确估计多模概率分布方面优于对比的4种算法,具有更低的误差指标以及更高的对数似然值,表明该算法能提供更准确的模型参数估计,从而更精确地刻画数据的多模性质。 展开更多
关键词 多模概率密度函数 Gamma混合模型 期望最大化算法 聚类 对数似然函数
在线阅读 下载PDF
Interpretable multimodal machine learning analysis of X-ray absorption near-edge spectra and pair distribution functions
18
作者 Tanaporn Na Narong Zoe N.Zachko +1 位作者 Steven B.Torrisi Simon J.L.Billinge 《npj Computational Materials》 2025年第1期1071-1082,共12页
We used interpretable machine learning to combine information from multiple heterogeneous spectra:X-ray absorption near-edge spectra(XANES)and atomic pair distribution functions(PDFs)to extract local structural and ch... We used interpretable machine learning to combine information from multiple heterogeneous spectra:X-ray absorption near-edge spectra(XANES)and atomic pair distribution functions(PDFs)to extract local structural and chemical environments of transition metal cations in oxides.Random forest models were trained on simulated XANES,PDF,and both combined to extract oxidation state,coordination number,and mean nearest-neighbor bond length.XANES-only models generally outperformed PDF-only models,even for structural tasks,although using the metal’s differential-PDFs(dPDFs)instead of total-PDFs narrowed this gap.When combined with PDFs,information from XANES often dominates the prediction.Our results demonstrate that XANES contains rich structural information and highlight the utility of species-specificity.This interpretable,multimodal approach is quick to implement with suitable databases and offers valuable insights into the relative strengths of different modalities,guiding researchers in experiment design and identifying when combining complementary techniques adds meaningful information to a scientific investigation. 展开更多
关键词 multimodal analysis oxidesrandom forest models transition metal cations atomic pair distribution functions pdfs heterogeneous spectra x ray extract local structural chemical environments combine information interpretable machine learning
原文传递
基于点估计和Gram-Charlier展开的含风电电力系统概率潮流实用算法 被引量:67
19
作者 艾小猛 文劲宇 +2 位作者 吴桐 孙树敏 李广磊 《中国电机工程学报》 EI CSCD 北大核心 2013年第16期16-22,共7页
概率潮流(probabilistic load flow,PLF)计算是评估风电并网影响的基础。风电功率具有随机性和波动性,其分布特征难以用常见的概率密度函数进行拟合,而且潮流计算的输出变量与输入变量之间是非线性关系。针对上述特点,提出一种基于点估... 概率潮流(probabilistic load flow,PLF)计算是评估风电并网影响的基础。风电功率具有随机性和波动性,其分布特征难以用常见的概率密度函数进行拟合,而且潮流计算的输出变量与输入变量之间是非线性关系。针对上述特点,提出一种基于点估计(point estimate method,PEM)和Gram-Charlier展开的概率潮流实用算法(PG算法),无需知道输入随机变量的概率密度函数,仅根据其样本数据,在有n个输入随机变量的情况下仅需计算2n+1次潮流便可估计出输出随机变量的期望、方差、累积分布等统计信息。对IEEE 16机系统的仿真结果表明:该方法精度高,计算量小。此外,本文提出的PG算法还可用于分析其他考虑不确定因素但其概率密度函数未知的电力系统问题。 展开更多
关键词 概率潮流 风电功率 概率密度函数 点估计 Gram-Charlier展开 累积分布
原文传递
基于耗损失效模型的金属化膜脉冲电容器可靠性评估 被引量:7
20
作者 赵建印 刘芳 +3 位作者 孙权 周经伦 魏晓峰 贺少勃 《强激光与粒子束》 EI CAS CSCD 北大核心 2005年第7期1031-1034,共4页
高储能密度金属化膜脉冲电容器是惯性约束聚变装置的关键元器件,由于其“自愈”特性,在短时间内很难得到它的失效数据。通过分析电容器的失效机理,给出了金属化膜脉冲电容器的一个耗损失效模型,推导了该模型的失效概率密度函数和分布函... 高储能密度金属化膜脉冲电容器是惯性约束聚变装置的关键元器件,由于其“自愈”特性,在短时间内很难得到它的失效数据。通过分析电容器的失效机理,给出了金属化膜脉冲电容器的一个耗损失效模型,推导了该模型的失效概率密度函数和分布函数,并利用电容器的性能衰退数据对其进行了可靠性分析。所选的某型金属化膜脉冲电容器未知参数估计值为0.0001194和0.0067,将该值代入失效分布函数和概率密度函数中,从而确定电容器的失效模型,由此模型求得该型电容器充放电10000次的可靠度为0.9885,预计寿命为23461次充放电。在工程实践中使用该模型对该型电容器进行可靠性分析可节约大量的试验成本。 展开更多
关键词 耗损失效 可靠性 金属化膜脉冲电容器 概率密度函数 概率分布函数
在线阅读 下载PDF
上一页 1 2 8 下一页 到第
使用帮助 返回顶部