The Method of Failure Probability of Pressure Vessel

Through thousands of accidents summarized by the department of quality supervision, comparing the design, manufacture, installation, using, and maintenance, through statistics, modeling and experience formula, the index is quantized and the calculation formula of failure probability of pressure vessel is obtained. According to the parameter, the pressure vessel can be examined quickly, be classified safely and provide support for failure probability.     

Parsimonious Covering Probability Model for Turbogenerator Vibration Faulty Diagnosis

The turbogenerator vibration faults have the character of variety. Many faults often occur synchronously. This paper introduces a diagnosing model based on parsimonious covering theory and probability. A model for turtogenerator's fault diagnosis is proposed. The availability of this method is proved by two fault diagnosis examples of turbogenerator. The results show that the model proposed can be used for multi_fault diagnosis together. It may make up shortage for some of expert systems and neural networks in some aspect. From the practice,this model has higher reliability and practicability.     

Step-by-step Method of Structural Damage Diagnosis

Base on the existing step-by-step structural damage diagnosis method, a three-step structural damage diagnosis method is developed. According to the analysis of the characteristic of genetic algorithm, a new idea of excluding the undamaged element by means of step-by-step evaluation is developed to deal with the damage diagnosis problem. In this method, sensitivity genetic algorithm is used to exclude the undamaged element step by step and residual force method is used to fix the damage district. According to the simulation research of a 2D framed structure, it is shown that the step-by-step structural damage diagnosis method can gain the ideal results when it's difficult for a single damage diagnosis method to get the good results. It is also indicated that sensitivity genetic algorithm is a good way to exclude the undamaged element step by step.     

Improved BP Algorithm in Vibration Failure Diagosis of Steam Turbine-Generator Set

A failure diagnosis model of neural networks for the vibration failure feature of steam turbine-generator set is established on the basis of the improved BP algorithm ,and used for diagnosing practical generator set,the results of verification show that the method is effective.     

Single Compression Experimental Analysisand Failure Mode of Loess with Different Structural

Based on the single compression experiments in laboratory, the structural change characteristic of loess with different initial structural in single compression stress conditions was studied. The conclusions are: compared to the single axial compression strength between intact loess and remold loess in the same moisture conditions, strength of intact loess was way bigger than remold loess; when the water content was low, all of a sudden, the destruction model of loess samples was mainly brittle tensile failure; when the water content was low, there was relative little effect on metastable of structural and was relative little loss of initial structural strength, and relative more variability; and then, there was way higher initial structural strength. The structural index decreased sharply with the moisture increase of intact loess, and the effect of water content on initial structural is obvious; when the water content reached a certain value, moisture effect on initial structural of intact loess become more and more unobvious, and structural index of loess was relative small. In other words, the initial structural has been fully released by remolding and saturating; the reasonability of structural index which was quantitative described the initial structural of loess was verified.     

Probability Algorism for Attributes Reduction in Incomplete Information System

Attributes reduction based on rough set theory is an important but difficult task under incomplete information system. For the attributes reduction which is gained by the old attributes reduction algorisms , the attribute belongs to it or not . Nevertheless in the practice when there is the probability that the attribute can discern two objects , this shows the attribute may belong to the attribute reduction. Probability discernibility matrix is defined and corresponding discernibility function is given. Then a probability algorism for attributes reduction is proposed and an example shows the algorism is effective. The probability that the attribute belong to the reduction can be know from the reduction which is gained by the algorism.     

Envelope Analysis Technique and Its Application in the Gear Failure Vibration Diagnosis

The gear failure vibration diagnosiS in a gearbox is of great importance in manyfields.Through theoretical analysis and engineering application,two methods of gear vibration en-velope analysis technique are discussed in this paper.Zoom Hilbert transform en velope and zcomnarrow-band en velope are formed by applying zoom technique to Hilbert transform demodulationand narrow-band demodulation in order to increase the frequency resolution of demodulation spec-trum.     

预报-观测概率匹配订正法在降水预报业务中应用研究

为提高和改进模式产品对汛期降水预报准确率,利用近两年3—7 月江西省92 个地面气象观测站逐日降水资料和欧洲中心高分辨率数值模式预报24~72 h 相应降水预报资料,采用Gamma函数作为累积降水概率分布拟合函数,将模式预报降水累积概率分布与观测降水累积概率分布进行概率匹配,获得不同量级降水的预报订正值,并检验了订正前后预报评分变化。结果显示：模式预报对江西降水预报存在大雨以上量级预报多漏报、小雨多空报的现象;经预报-观测概率匹配订正法订正后,可有效地修正模式预报系统性误差,对各等级降水有良好订正效果,尤其对暴雨的订正效果明显;时效越短订正效果越好。该订正法在业务中具有良好的应用效果。     

雷电引起接触电压、跨步电压导致生物伤害的损害概率计算方法探析

为了提高人员生命损失风险计算的针对性、准确性,为人工接地装置安全布设提出建设性的指导意见,通过对人工接地装置泄流时接触电压、跨步电压的计算方法的分析,确定了人工接地体泄流时接触电压、跨步电压导致人身伤亡的损害概率的定量计算方法。计算时,通过对接触电压、跨步电压计算值与人体耐受接触电压、跨步电压阈值的比较分析,确定能达到该阈值的最小雷电流幅值,再通过对项目所在位置雷电活动特征的分析,确定可能超过灾害阈值对应的雷电流幅值,即可能产生风险的雷电流所占的频率,认为该频率即为接触电压、跨步电压导致生物伤害的损害概率。对人工接地装置接触电压、跨步电压的计算以垂直接地极为例,同时考虑了冲击电流较工频电流对计算方法的影响。     

Interval Probability Random Variable and Its Numerical Characters

In this paper,based on the idea of fuzzy number origin,an interval probability space of the finite origin is established by the operation of fuzzy probability.Definitions of interval probability random variable (vecter) and it,s distribution function,distribution sequence,math expectation,variance and so on are given,and some special operation rules on them are studied.     

Fatigue Reliability Analysis Based on Probability Density Evolution Method

Based on the probability conservation principle, a joint probability density evolution equation of random parameters and fatigue damage is derived. Probability density evolution surface and cumulative probability isoline of fatigue damage in term of the evolution equation can be used to predict the probability distribution of fatigue damage and fatigue reliability with a given damage threshold. The numerical solution of fatigue reliability for a constant-amplitude test has a good agreement with the experimental result. For a variable-amplitude fatigue test, the computation results, which are calculated according to probability parameters of two constant-amplitude fatigue life tests and Miner's rule, are also in good agreement with the experimental results.     

Erosion Optimized Diagnosis of Brand Grounding Grid

To find the corrosion of the grid ,large area cutting has been adopting in practice for a very long time. But this method is blind, difficult and influences the system operating. The erosion diagnosis method in the past is effective for the smaller grid. To the brand ones, it can not take effect. The method of separating the grounding grid into several parts and diagnosing step by step is discussed by lots of simulation about middle or brand grounding grid erosion diagnosis. This method makes the brand grounding grid erosion diagnosis quick and truly without power cut and digging large area, satisfies the demand in practice. Putting this optimized diagnosis method into practice , the result is good.     

Sequential Diagnosis Algorithms in Asymmetric Models

We discuss the diagnosis algorithm for sequentially t-diagnosable systems.Wepresent two algorithms,based on the Malek and the BGM model,respectively,with a polynomialtime com pleAlty when the test graph is a bipartite groph.     

模糊概率在棉花品种综合评价中的应用初探

本文运用模糊数学中隶属度和模糊概率的概念及计算公式,提出了棉花品种综合评价的模糊概率值法,并说明了方法的原理和使用步骤。为了验证该法的有效性,综合评价了1984年黄河流域棉花品种区试的各参试品种。结果表明,模糊概率值法与文献[2]中的多级模糊综合评定法采用同一资料得出的结果完全一致,但本法比文献[2]大大简化了计     

地形对于村落雷击概率影响模拟研究

在对中国传统村落名录收录的古村落进行保护规划时,防雷保护是其中重要的一部分。现有的村落防雷保护研究更多侧重于定性的保护方法,对不同地形条件下的村落雷击概率的定量化研究还不多。本研究基于闪电随机模拟的方法,利用Matlab对闪电路径进行模拟,并分别分析村落位于平原、山脚及山谷处的雷击概率。模拟结果显示,平原的村落雷击概率最高,当村落位于山脚时,其雷击概率要比位于平原处小;当村落位于山谷时,其雷击概率比位于山脚处更小。主要原因是：建筑物周边的高大山体对于闪电有截收效应,位于山体周边时建筑雷击概率比平原时降低。模拟结果还显示小尺寸、低高度的建筑物仍然有发生侧击的危险,在农村的防雷保护工作中需加以关注。     

The Probability Risk Analysis of Bidding and Pricing for the Use of Land

In this paper by the probability method the effect of the undefinite indexes and the risk indexes on interior revenue rate(IRR) the main economic evaluation index in bidding and pricing of the use of land, is researched. The risk of the item is appreciated and the basis of bidding and pricing for the use of land is acquired. An example is presented.     

Analysis of Failure Behaviors in Glass under Shock Loading

The failure wave phenomena in glass media under shock loading are analyzed. The propagating mechanism and dynamic characteristics of failure wave and the property of failure layer are revealed. On the basis of experimental analysis, a damage accumulating model determinated by partial stress impulse is proposed, which describes the phenomenon of failure delay in materials being done with the Heaviside function. The propagating procedure, the evolution characters of transverse stress and longitudinal compression strain in failure layer are simulated. Furthermore a phenomenon is revealed that the failure wave velocity decreases after reflection of rarefaction wave at the boundary of failure layer.     

A Calculation Methed for Failure Probability of Typical Element at Landslide Risk

From the point of view of system theory, the landslide hazard system includes two subsystems: subsystem of hazard and subsystem of stricken. The consequence of landslide hazard is based on the interaction of these two subsystems. previous studies concenerate on evaluation of landslide stability. Hence, the study of a typical element at landslide risk is focused. And a method to calculate failure probability of typical element (frame structure) at landslide risk is discussed. Furthermore, the influences of both impact force and impact resistance capability of element at risk on failure probability are analyzed, which shows that, for each elements at risk, the landslide impact area can be divided into absolutely dangerous zone, relatively dangerous zone and absolutely safety zone. In addition, with the condition that the structure failure probability is above 50%, as the variability of impact force increases, the structure failure probability decreases; with the condition that structure failure probability is below 50%, as the variability of impact force increases, the structure failure probability also increases.     

Numerical Simulation of Berthing Velocity of the Ship

Based on the field data of berthing velocity for the ship (10000t-50000t), the berthing velocities have been numerically simulated by using Monte Carlo method in this paper. After statistical tests, it shows that the maximum values of the berthing velocity follow a Gumber distribution and the probability curves of failure for the means of maximum values are also obtained. The present results have been compared with the ones determined by specification of harbor engineering both at home and abroad.     

Probability Analysis of Failure Cause for Light Weight Steel Structure under Snow Disaster

In the current unified standard for reliability design, it lacks full considerations of the range of load effect ratio for reliability analysis of light weight steel structures. Firstly, a computational method based on stress was proposed to calculate load effect ratio, which solves the problem that which kind of load effects can be chosen to calculate load effect ratio when the member fails with actions of several kinds of internal forces. Then, the range of load effect ratio was studied for light weight steel structures after some analyses of several members with this method. It is found that the load effect ratio of light weight steel structures can adopt large values under the disadvantage distributions of snow load. The reliability was also calculated for light weight steel structures designed with current partial factors. Its result shows that the reliability of light weight steel structure is low. Finally, the reliability was analyzed for light weight steel structures with different load effect ratios when snow load exceeded the design standard level. It indicates that the reliability is low for light weight steel structures with large load effect ratio. This provides some complementary explanations for the phenomena that the light steel structures are more likely to fail under snow disaster.