Analyzing Effect of Demand Rate on Safety of Systems with Periodic Proof-tests

Quantitative safety assessment of safety systems plays an important role in decision making at all stages of system lifecycle, i.e., design, deployment and phase out. Most safety assessment methods consider only system parameters, such as configuration, hazard rate, coverage, repair rate, etc. along with periodic proof-tests （or inspection）. Not considering demand rate will give a pessimistic safety estimate for an application with low demand rate such as nuclear power plants, chemical plants, etc. In this paper, a basic model of IEC 61508 is used. The basic model is extended to incorporate process demand and behavior of electronic- and/or computer-based system following diagnosis or proof-test. A new safety index, probability of failure on actual demand （PFAD） based on extended model and demand rate is proposed. Periodic proof-test makes the model semi-Markovian, so a piece-wise continuous time Markov chain （CTMC） based method is used to derive mean state probabilities of elementary or aggregated state. Method to determine probability of failure on demand （PFD） （IEC 61508） and PFAD based on these state probabilities are described. In example, safety indices of PFD and PFAD are compared.

Game-Based Automated Security Proofs for Cryptographic Protocols

Provable security has become a popular approach for analyzing the security of cryptographic protocols.However,writing and verifying proofs by hand are prone to errors.This paper advocates the automatic security proof framework with sequences of games.We make slight modifications to Blanchet's calculus to make it easy for parsing the initial game.The main contribution of this work is that it introduces algebraic properties with observational equivalences to automatic security proofs,and thus can deal with some practical cryptographic schemes with hard problems.We illustrate the use of algebraic properties in the framework by proving the semantic security of the ElGamal encryption scheme.

Load distributions of some classic DHTs

The load balance is a critical issue of distributed Hash table （DHT）, and the previous work shows that there exists O（logn） imbalance of load in Chord. The load distribution of Chord, Pastry, and the virtual servers （VS） balancing scheme and deduces the closed form expressions of the probability density function （PDF） and cumulative distribution function （CDF） of the load in these DHTs is analyzes. The analysis and simulation show that the load of all these DHTs obeys the gamma distribution with similar formed parameters.

Rethinking the Method and Function of Proportionality Test in the European Court of Human Rights

Strasbourg’s application of proportionality test has some unique features.Due to the Court inherent subsidiary role,it hardly transplants the formulas and criteria adopted by the German Constitutional Court or Court of Justice European Union(CJEU) in the complete sense.Consequently,the Strasbourg application of the proportionality has been depicted as a "mysterious house" for the reason that it lacks of certainty.Therefore,some scholars often worry the application of the proportionality test will threaten the predictability and the Strasbourg rule of law.Generally,the proportionality test has two internal functions for the Strasbourg judges:(1) strike fair balance between/among the competing interests;(2) testing on the reasonableness and appropriateness between the measures employed and aim pursued.In the first category,the primary task of the Court is to protect the scope of "essence" of the Convention rights from the interference of collective goods relying on the interest-based rights theory.Beyond this scope,the Court would have to balance the interests explicitly incorporated into the Convention rights as well as the external collective goods claimed by the state authorities.In some sensitive judgments,the Strasbourg Court tends to impose the onerous responsibility of "burden of proof" to the State authorities,or strategically defers to the domestic decisions unless they will be found "manifestly unreasonable".Secondly,the Court must take a scrutiny towards the appropriateness between the means employed and ends pursued,and then it has to decide whether a less intrusive alternative existed or will possibly be found or not.Sometimes,the Court might impose state authorities an obligation looking for a new alternation.However,due to subsidiarity characteristic of the Strasbourg Court,the task of the assessments sometimes is complicated and time-consuming,so the Court are not capable of evaluations in all occasions.Finally,the Court could strike down the "chilling consequence" caused by some few of the legitimate measures which may highly potentially threaten the individual rights in the National legal order.

CDMA/OFDMA异构网络中最小化中断概率的网络选择方案

该文针对采用周期式负载测量机制的CDMA/OFDMA异构网络场景,提出了一种最小化SIR中断概率(Minimizing SIR Outage Probability,MSOP)网络选择方案。该算法采用Wilkinson近似方法得出呼叫最佳接纳概率。仿真结果证明,在较长的测量周期下,该算法能有效实现负载均衡,获得更高的中继增益,提高资源的使用效率;同时,该算法也能大大降低呼叫的平均中断概率,使用户获得更好的通信体验。

A NOTE ON ASYMPTOTIC BEHAVIOR FOR NEGATIVE DRIFT RANDOM WALK WITH DEPENDENT HEAVY-TAILED STEPS AND ITS APPLICATION TO RISK THEORY

In this article, the dependent steps of a negative drift random walk are modelled as a two-sided linear process. Xn=-u＋∑j=-∞^∞ φn-jεj, where { ε, εn; -∞〈n〈＋∞} is a sequence of independent, identically distributed random variables with zero mean, u 〉 0 is a constant and the coefficients {φi; -∞〈i〈∞} satisfy 0〈 ∑j=-∞^∞ ｜jφj｜〈 ∞ . Under the conditions that the distribution function of ｜ε｜ has dominated variation and ε satisfies certain tail balance conditions, the asymptotic behavior of P{sup n≥0 （-qu＋∑j=-∞^∞ εj βnj）〉x} is discussed. Then the result is applied to ultimate ruin probability.

The Theoretical Defects in DRIS and the Restructuring of a New Approach

There are two kinds of theoretical defects export in the diagnosis and recommendationintegrated system (DRIS): the distribution of nutrient elements ratios with two normaldistribution displays an abnormal distribution of positive skewness; there is a blinddiagnostic area by DRIS on the occasion of the nutrient elements with equal ratios butwithout equal quantity. In the light of the quadratic form theory of multidimensionalnormal distribution and the view of balance of equal probability, the balance diagnosisand recommendation integrated system (BDRIS) was developed in this paper, which issuperior to DRIS and its diagnosis method is unified to critical value diagnosis. Whenthe correlation matrix of nutrient elements R=I(identity matrix), i.e., the effects ofelements antagonism is disregarded, BDRIS will be simplified into the critical valuediagnosis. In addition, the diagnosis program written in SAS language was also providedin this paper.

ASON中基于传输损伤的RWA算法研究

路由和波长分配(RWA)算法是ASON中的一个关键问题。由于信号传输过程中存在传输损伤,这将会影响到不同连接请求的公平性。对现有算法进行研究,提出了一种改进算法,在保证公平性的同时,尽量降低网络的阻塞率。仿真表明该算法能有效的降低阻塞,提高资源利用率。

CBPS-Based Inference in Nonlinear Regression Models with Missing Data

In this article, to improve the doubly robust estimator, the nonlinear regression models with missing responses are studied. Based on the covariate balancing propensity score (CBPS), estimators for the regression coefficients and the population mean are obtained. It is proved that the proposed estimators are asymptotically normal. In simulation studies, the proposed estimators show improved performance relative to usual augmented inverse probability weighted estimators.

提供虚假证明文件涉受贿条款修改之检视

基于1997年《刑法》第229条第2款的立法缺陷和受贿犯罪的立法发展,《中华人民共和国刑法修正案(十一)》对该款规定的故意提供虚假证明文件涉受贿行为进行了修正,将其定罪处罚的条件从“提供虚假证明文件罪法定刑升格”修改为“依照处罚较重的规定定罪处罚”。从立法学角度分析,这一修改试图纠正立法缺陷,但却引发了新的问题:该款中的“依照处罚较重的规定定罪处罚”的适用条件与刑法分则中其他类似条款的普遍性适用条件不一致;此外,该款牵连犯的处断规则与刑法分则其他法定牵连犯的处断规则不一致,造成了该款牵连犯内部、该款牵连犯与其他法定牵连犯之间,以及该款牵连犯与其他条款规定的想象竞合犯之间的罪刑失衡。从刑法释义学角度分析,该款规定的罪数处断条件的表述与实际处断规则不符,导致在解释时难以确定具体的罪数形态。因此,有必要进一步修改该款规定的处断规则及其适用条件的表述,以实现罪刑均衡和法律适用的一致性。

基于平衡分布自适应迁移学习的多风电机组运行状态监测方法

风电机组状态的准确监测对风电机组安全稳定运行和经济效益提升至关重要。但是,受不同风电机组运行数据分布差异的影响,现有状态监测方法在多风电机组应用场景下存在精度和效率难以兼顾的问题,而平衡分布自适应迁移学习(BDA)可以拉近数据距离,同化数据分布。因此,文章提出了一种基于BDA的多风电机组状态监测方法。首先,基于Copula熵的互信息法挖掘风电机组运行状态关键影响参量;然后,构建基于门控循环单元模型(GRU)和序贯概率比检验(SPRT)方法的单风电机组状态监测模型;最后,构建基于BDA的多风电机组运行数据分布同化模型,并用于多风电机组运行状态监测。算例结果表明,所提方法可以有效节省建模成本和计算成本,能够在保障多风电机组运行状态监测精度的前提下,显著提升监测效率。

电伴热下极地装备踏步板构件的对流换热影响

为解决恶劣极地环境引起的海洋装备防寒问题,工程上通常采用电伴热的方式.采用数值模拟和实验的方法,对电伴热踏步板构件在典型极地环境下热平衡的影响因素进行分析.环境要素为风速和温度,风速为0~40 m/s、温度为-40~0℃.基于数值仿真和实验测试获得电加热踏步板构件在不同风速及温度下的对流换热系数.结果表明,增大风速和降低温度都会增大踏步板的对流换热系数;风速是影响踏步板换热的主要因素,而温度的影响较小.基于实验数据,参考平板构件对流换热的经典理论,建立电加热踏步板构件的对流换热系数预测模型,并采用数值仿真验证该模型的正确性.

一种适用于Ad hoc网络的基于概率负载均衡算法

为解决移动自组织网络(MANET)中网络拥塞导致的网络时延增大和吞吐量下降,提出一种基于概率的负载均衡算法,节点利用历史负载信息映射网络负载状态,用概率算法进行路由准入,从而完成负载均衡。基于历史状态的负载映射有效解决了分布式独立运算中存在的负载状态判断困难等问题,概率算法能有效克服门限准入法则存在的模糊判别问题,同时大量减少广播包的洪泛,节省信道资源。结合经典的按需路由协议,设计了H&P_DSR(history and probability based dynamic source routing)协议。仿真和理论分析一致表明,该负载均衡算法能够准确有效地对网络负载进行均衡,H&P_DSR协议在没有增加任何信道开销的情况下显著提高了网络吞吐量,降低了时延。

分布式光伏波动事件多级区间滚动预警方法

大范围极端天气影响下的分布式光伏波动事件对电力系统功率平衡问题影响显著,可能引起弃光、切负荷等风险事故。为此,提出了基于区间分析理论的分布式光伏波动事件多级区间滚动预警方法,以针对分布式光伏波动事件可能的危害程度进行滚动预警。首先,明晰电力系统应对分布式光伏波动的功率调控机理,并制定预警等级,确定不同功率控制手段能够应对的分布式光伏波动幅度区间,即不同预警等级对应的预警界限;然后,依据分布式光伏波动的概率密度,通过对各预警区间内的概率密度积分,计算各预警等级的概率;最后,分析不同时间尺度下光伏波动预测精度的差异水平,通过定时滚动预警校正结果,实现分布式光伏波动事件多级区间滚动预警。算例结果表明,该方法能够在确定各预警区间界限的同时,决策电力系统在不同系统运行状态和光伏波动事件下的预警结果,且与蒙特卡洛法预警结果的均方根误差仅为1.6718%,进而验证了该方法的有效性和适用性。

PSM⁃DID在政策评价中的应用现状与改进方法

倾向得分匹配-双重差分模型(PSM⁃DID)是政策评估及因果推断中最为流行的方法之一.但是在实际应用中,该方法面临着控制变量在处理组样本和控制组样本之间非平衡性的挑战.传统基于均值差异t检验的平衡性检验容易产生片面和误导性的结论,使得后续因果推断产生偏误.为克服上述问题,本文对传统的平衡性检验提出以下改进:一是推荐更全面的多维度的平衡性测度指标,便于在匹配后更严谨地比较处理组和控制组的平衡性;二是提出了适用于非平衡样本的新估计方法:倾向得分匹配-逆概率加权-双重差分(PSM⁃IPW⁃DID),该方法结合了倾向得分匹配(PSM)克服样本自选择内生性及对非平衡样本稳健的优势和逆概率加权(inverse probability weighting,IPW)利用全样本信息的长处,在不进一步删除样本的情况下得到一种更稳健的双重差分估计方法.数据模拟和应用实例显示,本文提出的新方法能更全面、客观地评价宏观、微观政策的作用,得到更为可信的因果推断.

周期检测策略对基于Markov模型的PFS计算的影响

为准确评估安全仪表系统(SIS)的安全失效概率(PFS),在传统Markov模型基础上,提出一种新的计算模型。考虑周期检测覆盖率,以及周期检测导致的系统安全失效概率的周期检测策略,构建SIS的PFS新计算模型;并以加氢工艺热高压分离器液位控制SIS为例,应用该模型计算不同周期检测策略下该系统的安全失效概率。结果表明:该模型能够解决PFS计算过于理想化的问题;相较于理想检测策略,该模型对现场SIS的PFS计算更准确,且为SIS提供了一定的安全裕度。

基于风光出力累积概率分布的新能源消纳规划方法

风光电出力过程的随机性、间歇性、波动性等特点导致风光电难以被电网消纳,利用水力发电迅速且可调节的优点,可弥补风光电出力的缺陷。笔者提出水电平衡风电和光伏的原理,以电力电量平衡、不弃水调峰和能源基地总发电过程平稳为原则,结合风光出力累积概率分布,推导风光弃电计算公式,得到不同风光装机规模和比例下的弃电率。通过与PSO结果比较,表明两种方法下的风光弃电量误差在5%以内,从而验证该方法的有效性和实用性。以上述理论为基础,分析雅砻江下游电源规划,其研究为大规模新能源消纳提供一种可行的方法。

防爆锂离子电源电池管理系统分析与应用

电池的最高表面温度等于环境温度和温升之和,防爆锂离子蓄电池电源标准规定单体电池和电池组的工作温度不超过60℃,由于季节变化环境温度变化较大,对应的温升也有很大差别。高温环境下,锂离子电池的温升余量非常有限。为了研究温升与放电倍率的关系,搭建了电池放电试验装置,研究了放电倍率对三元锂离子电池表面温升的影响,结果表明:4C放电条件下温升为36.5℃,5C放电条件下温升为47.4℃,6C放电条件下温升为58.1℃。同时对比了其他三元锂电池的温升试验,试验结果一致性较好。对电池的各项参数进行实时监控,限制充放电倍率降低电池的温升和最高表面温度,防止电池热失控是电池管理系统的核心。提出BMS要综合考虑温度保护和过流保护,避免以“小马拉大车”大倍率放电方式配置电池,对保证电池的安全运行十分必要。

10kV高压防爆变频器在煤矿主运皮带机的应用

本文介绍了新风光10kV高压防爆变频器在贵州省大方县营兴煤矿主运皮带机中的应用情况,对应用案例进行了介绍。结果表明,采用单元级联主回路拓扑结构的防爆变电变频器装置,它相比传统井下变频器具有低频力矩大、输入输出谐波含量低、操作供电方便、长距离供电、主从机功率平衡等优点,在煤矿皮带机输送系统上采用防爆变电变频器具有较高的经济效益和社会效益。

PAC最优的RMAX-KNN探索算法

探索与利用的均衡是强化学习研究的重点之一。探索帮助智能体进一步了解环境来做出更优决策;而利用帮助智能体根据其自身当前对于环境的认知来做出当前最优决策。目前大多数探索算法只与值函数相关联,不考虑当前智能体对于环境的认知程度,探索效率极低。针对此问题,提出了一种基于状态空间自适应离散化的RMAX-KNN强化学习算法,算法根据当前智能体对于环境状态空间的离散化程度改写值函数形式,然后基于此值函数对环境进行合理的探索,逐步实现对于环境状态空间的自适应离散化划分。RMAXKNN算法通过将探索与环境状态空间离散化相结合,逐渐加深智能体对于环境的认知程度,进而提高探索效率,同时在理论上证明该算法是一种概率近似正确(PAC)最优探索算法。在Benchmark环境上的仿真实验结果表明,RMAX-KNN算法可以在探索环境的同时实现对于环境状态空间的自适应离散化,并学习到最优策略。