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排序方式: 共有105条查询结果,搜索用时 31 毫秒
51.
Corona discharge and electromagnetic environment on AC long-term operated conductors are important issues for extra-high-voltage transmission lines. To investigate the relation between conductor age and electromagnetic environment, including audible noise and radio noise, several groups of long-term operated conductors in China are selected for corona cage experiment. According to corona tests, corona discharge becomes more serious as the applied voltage improves. Difference of electromagnetic environment between conductors of different operated year increases. Corona discharge and electromagnetic noise become more serious as the service year lengthens. When the operated years are close, the general environment is important in electromagnetic environment degradation. 相似文献
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This paper proposes a random effects multinomial regression model to estimate transition probabilities of credit ratings. Unlike the previous studies on the rating transition, we applied a random effects model, which accommodates not only the environmental characteristics of the exposures of a rating but also the uncertainty not explained by such factors. The rating category specific factors such as retained earning and market equity are included in our proposed model. The random effects model provides less diagonally dominant matrix, where the transition probabilities are over-dispersed from the diagonal elements. Our study is expected to incorporate potential chances of rating transitions due to extra random variations. 相似文献
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在提升管催化裂化中试装置上,考察了操作苛刻度对重油催化裂化(RFCC)装置沉降器中油气重组分,特别是大于550℃的馏分以及油浆中胶质、沥青质的影响,并结合操作苛刻度对产品分布的影响规律,建立了操作苛刻度函数。结果表明,随着操作苛刻度的提高,油浆中的馏分呈现出中间馏分增加,两端馏分降低的变化趋势,并且油浆中大于550℃馏分的含量明显减少,油浆中的胶质、沥青质含量减少。随着操作苛刻度的提高,在一定范围内轻质油收率基本不变,但是达到一定反应程度后,轻质油产率明显降低。建立的操作苛刻度函数为合理控制操作条件,保证目的产物收率的同时降低了油气中重组分的含量,从而为防止沉降器结焦提供了操作依据。 相似文献
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Maria Conceição A. LeiteNikola P. Petrov Ensheng Weng 《Nonlinear Analysis: Real World Applications》2012,13(2):497-512
We consider a semistochastic continuous-time continuous-state space random process that undergoes downward disturbances with random severity occurring at random times. Between two consecutive disturbances, the evolution is deterministic, given by an autonomous ordinary differential equation. The times of occurrence of the disturbances are distributed according to a general renewal process. At each disturbance, the process gets multiplied by a continuous random variable (“severity”) supported on [0,1). The inter-disturbance time intervals and the severities are assumed to be independent random variables that also do not depend on the history.We derive an explicit expression for the conditional density connecting two consecutive post-disturbance levels, and an integral equation for the stationary distribution of the post-disturbance levels. We obtain an explicit expression for the stationary distribution of the random process. Several concrete examples are considered to illustrate the methods for solving the integral equations that occur. 相似文献
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In nonlife insurance, frequency and severity are two essential building blocks in the actuarial modeling of insurance claims. In this paper, we propose a dependent modeling framework to jointly examine the two components in a longitudinal context where the quantity of interest is the predictive distribution. The proposed model accommodates the temporal correlation in both the frequency and the severity, as well as the association between the frequency and severity using a novel copula regression. The resulting predictive claims distribution allows to incorporate the claim history on both the frequency and severity into ratemaking and other prediction applications. In this application, we examine the insurance claim frequencies and severities for specific peril types from a government property insurance portfolio, namely lightning and vehicle claims, which tend to be frequent in terms of their count. We discover that the frequencies and severities of these frequent peril types tend to have a high serial correlation over time. Using dependence modeling in a longitudinal setting, we demonstrate how the prediction of these frequent claims can be improved. 相似文献
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