The Study of Overhead Line Fault Probability Model Based on Fuzzy Theory

In the background of the design and construction of Smart Grid Operation Supporting System for District Power Networks, this paper established the weighted fault probability model of the overhead line which is based on equipment operating status, utility theory and fuzzy theory. In this model, the proper membership function is adopted to describe the influence of lightning, wind speed, line ice and temperature, and the outage rate of overhead line, derived from historical statistics, is amended. Based on this model, the power supply risk analysis software is developed to calculate the online risk indicators of district grid, and provide real-time decision support information based on risk theory for scheduling operations personnel.

GENERAL FAILURE PROBABILITY SIMULATION AND APPLICATION FOR MULTI-MODE

A general failure probability simulation and deviation evaluation methods were presented for fuzzy safety state and fuzzy failure state. And the corresponding number integral method was simultaneously established. As the distribution of state variable and the membership of the state variable to the fuzzy safety set were normal, the general failure probability of the single failure mode had precise analytic solution, which was used to verify the precision of the presented methods. The results show that the evaluation of the simulation method convergences to the analytic solution with the number increase of the sampling. The above methods for the single failure mode was extended to the multi-mode by the expansion and probability principles. The presented methods were applied to the engineering problem. For the number of significant mode is not too many, the high precision solution can be given by the presented number simulation and number integral methods, which is illustrated by the engineering examples. In addition, the application scope of the methods was discussed.

基于Geiger-mode APD的激光雷达性能分析

针对基于盖革模式雪崩光电二极管(Gm-APD)阵列的激光雷达,提出一种分析其探测性能的方法。以分析单个Gm-APD像元产生的初始光电子和暗计数噪声为基础,对Gm-APD像元的探测概率、虚警概率和漏警概率进行研究,并进一步提出一种多脉冲阈值探测法,并对其探测概率、虚警概率进行了研究和仿真。结果表明,对2～10 km外的目标,采用128×128像元面阵探测器,单脉冲能量小于200 mJ时,探测概率随脉冲能量提高而提高;单脉冲能量大于200 mJ时,探测概率保持不变;当采用多脉冲阈值探测、信号较弱时,探测概率总是随脉冲能量提高而提高,虚警概率总是随脉冲能量提高而降低。

New model for deducing directional extrema based on multivariate extremum statistical theory

The parameters of principal and directional extrema in a marine environment are important in marine engineering design, especially for appropriate construction of oceanic platforms and other structures. When designing wave walls and break water structures, the orientation of the breakwater or seawall depends mainly on the direction of the strongest waves. However, the strength of the breakwater and the elevation of the seawall depend on the magnitude of the biggest wave height of the strongest waves. Thus, identification of directional extrema plays an important role in the design of wave factors. When calculating the directional extremum, different materials may require different specific computational methods, yet few theoretical studies have been conducted in this field of research. Based on multivariate extremnm statistical theory, this paper utilizes a discrete random variable to build a joint probability model compounded by a discrete random variable and a multivariate continuous random variable. Furthermore, this paper provides the first investigation on the theories and methodologies to deduce wave directional extrema. The results provide tools for both creating the calculation method of the directional extremum value and providing the rational directional extremum parameters for marine engineering design.

Methodology for estimating probability of dynamical system's failure for concrete gravity dam

Methodology for the reliability analysis of hydraulic gravity dam is the key technology in current hydropower construction.Reliability analysis for the dynamical dam safety should be divided into two phases:failure mode identification and the calculation of the failure probability.Both of them are studied based on the mathematical statistics and structure reliability theory considering two kinds of uncertainty characters(earthquake variability and material randomness).Firstly,failure mode identification method is established based on the dynamical limit state system and verified through example of Koyna Dam so that the statistical law of progressive failure process in dam body are revealed; Secondly,for the calculation of the failure probability,mathematical model and formula are established according to the characteristics of gravity dam,which include three levels,that is element failure,path failure and system failure.A case study is presented to show the practical application of theoretical method and results of these methods.

State and Mode Feedback Control for Discrete-time Markovian Jump Linear Systems With Controllable MTPM

In this note, the state and mode feedback control problems for a class of discrete-time Markovian jump linear systems(MJLSs) with controllable mode transition probability matrix(MTPM) are investigated. In most achievements, controller design of MJLSs pays more attention to state/output feedback control for stability, while the system cost in practice is out of consideration. In this paper, we propose a control mechanism consisting of two parts: finite-path-dependent state feedback controller design with which uniform stability of MJLSs can be ensured, and mode feedback control which aims to decrease system cost. Differing from the traditional state/output feedback controller design, the main novelty is that the proposed control mechanism not only guarantees system stability, but also decreases system cost effectively by adjusting the occurrence probability of system modes. The effectiveness of the proposed mechanism is illustrated via numerical examples.

Time-Delayed Feedback Control in a Single-Mode Laser System

The effects of time-delayed feedback control in a single-mode laser system is investigated.Using the smalltime delay approximation,the analytic expression of the stationary probability distribution function of the laser field isobtained.The mean,normalized variance and skewness of the steady-state laser intensity are calculated.It is found thatthe time-delayed feedback control can suppress the intensity fluctuation of the laser system.The numerical simulationsare in good agreement with the approximate analytic results.

Steady-state probability density function in wave turbulence under large volume limit

We investigate the possibility for two-mode probability density function （PDF） to have a non-zero flux steady state solution. We take the large volume limit so that the space of modes becomes continuous. It is shown that in this limit all the steady-state twoor higher-mode PDFs are the product of one-mode PDFs. The flux of this steady-state solution turns out to be zero for any finite mode PDF.

基于EMD-BiLSTM-ANFIS的负荷区间预测

考虑到新型电力负荷随机性增强,传统的准确预测方法已无法满足要求,提出一种EMD-BiLSTM-ANFIS(Empirical Mode Decomposition-Bi-directional Long Short-Term Memory-Adaptive Network-based Fuzzy Inference System)分位数预测负荷概率密度的方法,使用负荷预测区间取代点预测的准确数值,能为电力系统分析与决策提供更多数据,增强预测的可靠性。首先将原始负荷序列通过EMD(Empirical Mode Decomposition)分解成若干分量,并通过计算样本熵分为3类分量。然后将重构后的3类分量与由相关性筛选的外界因素特征采用BiLSTM、ANFIS模型进行训练和分位数回归(QR:Quantile Regression),并将分量的预测区间结果累加得到最终负荷的预测区间。最后利用核密度估计输出任意时刻用户负荷概率密度预测结果。通过与CNN-BiLSTM(Convolutional Neural Network-Bidirectional Long Short-Term Memory)、LSTM(Long Short-Term Memory)模型对比点预测及区间预测结果,证明了该方法的有效性。

基于前景理论的疫后旅游景区交通方式选择行为

基于有限理性的前景理论构建了旅客出行方式选择模型,通过对某景区旅游者的个人信息、出行基本情况以及出行意向进行了调查分析,揭示出其出行行为的特点。并且进一步运用前景理论研究旅游者的出行方式选择行为,在完全理性和有限理性的条件下分别计算了各异质类旅客对不同客运方式的模糊选择概率。在此基础上,建立了基于有限理性作用下旅客个体出行决策的模型,得出了各异质类旅客对不同客运方式的出行偏好。通过比较不同类型旅客的出行偏好,可分析出高收入和务工旅客更倾向于驾车出行,而学生游客更倾向于乘坐大巴。相关研究的结论对于旅游景区周边交通设施的规划和建设有一定的指导意义,可更好地服务和满足游客的出行需求。

新文科建设背景下《概率论与数理统计》课程教学创新实践

在新文科建设背景下,结合经济类专业《概率论与数理统计》课程现状,针对课程教学中出现的问题,从教学内容设计、教学手段模式和教学评价三方面实施了教学创新实践。构建了课前、课中和课后三阶段和课程思政引领的“三阶段一引领”教学内容,设计了课前课后阶段线上、课中阶段线下的混合式教学模式,对评价标准应用线上学习数据和期末考试结合的“全过程”评价模式创新,从多个方面多个角度提升课堂教学效果,改进教学质量,全面提升经济类专业学生数学科学素养。

稀疏网络编码中秩分布分析模型研究

针对现有稀疏网络编码研究中线性相关概率性能指标精准度较低的问题,提出基于马尔可夫链的性能分析模型。对线性相关概率、秩的概率分布等性能指标及其复杂度进行分析,并通过该性能分析模型分析编码包传输后期的译码成功概率;基于吸收马尔可夫链计算编码包传输过程中的瞬态、吸收态以及各状态间的状态转移概率,并对状态转移概率中蒙特卡罗模拟误差较大的问题进行改进,由状态转移概率构建吸收马尔可夫链基本矩阵,得出信宿端收到非再生包的线性相关概率,进而推导出秩的概率分布和译码成功概率性能指标。仿真结果表明,在相同条件下所提模型性能指标精确度均优于对比模型,且能精确地评估信宿端解码矩阵秩的概率分布、译码成功概率等稀疏网络编码的译码行为。

多失效模式与变量相关的管道失效概率预测

针对腐蚀管道多失效模式相互竞争、变量非独立的特点以及小失效概率预测效率低的问题,提出一种基于子集模拟法(SS)的腐蚀管道时变失效概率预测方法。基于泄漏与爆裂失效的极限状态函数,考虑泄漏与爆裂失效的竞争关系,构建管道竞争失效概率预测模型;使用Nataf转换方法描述模拟样本中缺陷深度与长度的相关性,提出考虑失效模式竞争性、变量相关性的腐蚀管道失效概率求解方法,并采用蒙特卡罗模拟(MCS)验证该方法;应用上述方法,探究缺陷深度和长度的弱相关性(相关系数0~0.3)对管道服役15年内失效概率的影响。结果表明:失效概率大于10-6时,使用该方法的计算结果与MCS计算结果基本相同,计算效率高于MCS,且可预测概率水平为10-12的极小概率事件;管道服役15年内,缺陷变量相关系数越大,管道爆裂失效概率越大,越早到达爆裂失效概率阈值年限;而随着相关系数的增大,泄漏失效概率越小,越晚达到泄漏失效概率阈值年限;在预测后期,相关系数增大对2种失效概率的影响均减弱。

概率统计“3542”课程思政教学模式的研究与实践

以专业人才培养目标为依据,根据教育部颁布的《高等学校课程思政建设指导纲要》,结合概率统计课程的特点,通过明确教学目标,优化教学内容,实施教学过程,设计教学评价,探索并构建了3维度教学目标,5方面教学内容,4环节教学过程,2方面教学评价的“3542”立体化课程思政闭环教学模式,在实践中获得了良好的教学效果。

常泰长江大桥船撞抗力研究及安全性评估

为确保常泰长江大桥建设和服役安全,对大桥进行船撞抗力研究及安全性评估。采用单位荷载法计算各涉水下部结构船撞抗力及其船撞破坏控制模式;基于船-桥碰撞概率模型得到各墩碰撞概率,明确常泰长江大桥船撞风险等级,通过对比数值模拟和经验公式计算的船撞力,确定设防船型碰撞各下部结构船撞力;以船撞安全系数和实际防撞吨位为指标进行船撞安全评估。结果表明:1~4号墩船撞破坏模式均由碰撞截面抗剪强度控制,5号和6号塔船撞破坏模式均由基底地基竖向承载力控制;在目前船舶流量下全桥船舶年碰撞概率为1.58次/年,与同类桥梁相比船舶碰撞风险较低且处于安全可控水平,大桥孔跨布置和航道规划合理;全桥涉水下部结构船撞安全系数为1.10~6.54,各下部结构实际防撞吨位均大于相应设防船型吨位,常泰长江大桥涉水下部结构抗船撞性能满足要求。

动态数据隐私模态分解的保护方法优化研究

由于网络环境中动态隐私数据尺度特征难捕捉、保护需求判定误差大,使得隐私数据保护难度提升。为解决以上问题,提出动态数据隐私模态分解的保护方法。通过采集动态数据信息,建立经验函数并按照数据模态量实行独立分解与转换,计算按照不同尺度规则分解中一组数据的分量变化,求得其高频和低频分量,分量即该数据的隐私泄露风险概率。将网络动态图抽象成模型,明确不同时刻下各节点的相邻变化关系,根据节点保护需求,在加密函数中代入求解密钥,结合明文规则使密钥与隐私数据无限贴合,完成隐私有效保护。实验结果表明,所提方法的隐私保护效果较好,在正常和非正常网络环境下均能够实现数据隐私的有效保护。

生物氧化预处理过程pH值随机分布控制方法研究

生物氧化预处理过程中氧化槽pH值是影响细菌活性的关键因素之一,而pH值输出形态分布不符合高斯分布,使传统的均值和方差难以描述输出pH值分布,本文提出一种对矿浆输出pH的概率密度函数(PDF)统计信息控制方法。首先,采用B样条逼近矿浆输出pH值的PDF统计信息;其次,针对权值向量之间的关系,利用动态神经网络(DNN)建立控制输入和权值向量之间的非线性动态模型,基于建立pH的PDF统计信息权值模型,设计滑模变结构控制器,通过构造Lyapunov函数进行稳定性分析;最后,实现输出PDF统计信息对目标PDF统计信息的跟踪。仿真结果验证了所提方法的有效性,为生物氧化预处理过程提供了新方法。

马尔可夫跳变系统的奇异自适应滑模控制

该文采用奇异系统方法研究了转移速率部分已知的、具有匹配非线性和匹配外部扰动的连续时间马尔可夫跳变系统的自适应积分滑模控制问题.首先,按照奇异系统方法设计积分型滑模面,进而结合原系统及滑模动力学可得奇异马尔可夫跳变系统;其次,以线性矩阵不等式的形式给出了保证所得奇异马尔可夫跳变系统随机容许性的充分条件;紧接着在这一条件下,结合自适应控制来保证状态轨迹对积分滑模面的可达性;最后通过仿真案例验证了所得结果的有效性.

基于风险优先数的航空发动机可靠性设计方法

为了解决故障模式和影响分析难以融入航空发动机设计中的难题,提高可靠性水平,在型号研制工作中摸索出利用故障模式和影响分析中风险优先数的概念开展零部件某故障模式设计改进。运用风险优先数(RPN)的概念对设计故障模式和影响分析中严酷度和故障模式发生概率划分了1~10级评分原则,增加了故障被检测难度,且结合航空发动机特点,对故障被检测难度也划分了1~10级评分原则,得出了故障模式的风险优先数,确定了故障模式的优化排序,提出了确定风险改进项的方法。以某发动机的密封装置为例,利用严酷度、故障模式发生概率和故障被检测难度等级评分原则,得出了密封装置各故障模式风险优先数,确定了2项风险改进项。结果表明:利用严酷度、故障模式发生概率和故障被检测难度划分的1~10级评分原则进行风险优先数计算,可得出风险改进项,为提高发动机的可靠性水平提供了方向。