HAZARD FUNCTION AND CHARACTERIZATIONS ON DISTRIBUTION TAILS OF NONNEGATIVE RANDOM VARIABLES

Some equivalent conditions on the classes of lighted-tailed and heavily heavy-tailed and lightly heavy-tailed d.f.s are introduced.The limit behavior of xα(x) and e λx(x) are discussed.Some properties of the subclass DKc and subclass DK 1 are obtained.

Consistency of the Estimator of Cumulative Hazard Function in Estimated Pseudo-Partial-Likelihood Approach

For multivariate failure time with auxiliary covariate information, an estimated pseudo-partial-likelihood estimator under the marginal hazard model with distinguishable baseline hazard has been proposed. However, the asymptotic properties of the corresponding estimated cumulative hazard function have not been studied. In this paper, based on counting process martingale, we use the continuous mapping theorem and Lenglart inequality and prove the consistency of the estimated cumulative hazard function in estimated pseudo-partial-likelihood approach.

ASYMPTOTIC NORMALITY OF THE NONPARAMETRIC KERNEL ESTIMATION OF THE CONDITIONAL HAZARD FUNCTION FOR LEFT-TRUNCATED AND DEPENDENT DATA

Under some mild conditions, we derive the asymptotic normality of the Nadaraya-Watson and local linear estimators of the conditional hazard function for left-truncated and dependent data. The estimators were proposed by Liang and Ould-Sa?d [1]. The results confirm the guess in Liang and Ould-Sa?d [1].

Hazard Rate Function Estimation Using Weibull Kernel

In this paper, we define the Weibull kernel and use it to nonparametric estimation of the probability density function (pdf) and the hazard rate function for independent and identically distributed (iid) data. The bias, variance and the optimal bandwidth of the proposed estimator are investigated. Moreover, the asymptotic normality of the proposed estimator is investigated. The performance of the proposed estimator is tested using simulation study and real data.

Copula joint function and its application in probability seismic hazard analysis

A mature mathematical technique called copula joint function is introduced in this paper, which is commonly used in the financial risk analysis to estimate uncertainty. The joint function is generalized to the n-dimensional Frank’s copula. In addition, we adopt two attenuation models proposed by YU and Boore et al, respectively, and construct a two-dimensional copula joint probabilistic function as an example to illustrate the uncertainty treatment at low probability. The results show that copula joint function gives us a better prediction of peak ground motion than that resultant from the simple linear weight technique which is commonly used in the traditional logic-tree treatment of model uncertainties. In light of widespread application in the risk analysis from financial investment to insurance assessment, we believe that the copula-based technique will have a potential application in the seismic hazard analysis.

The Lambert-G Family:Properties,Inference,and Applications

This study proposes a new flexible family of distributions called the Lambert-G family.The Lambert family is very flexible and exhibits desirable properties.Its three-parameter special sub-models provide all significantmonotonic and non-monotonic failure rates.A special sub-model of the Lambert family called the Lambert-Lomax(LL)distribution is investigated.General expressions for the LL statistical properties are established.Characterizations of the LL distribution are addressed mathematically based on its hazard function.The estimation of the LL parameters is discussed using six estimation methods.The performance of this estimation method is explored through simulation experiments.The usefulness and flexibility of the LL distribution are demonstrated empirically using two real-life data sets.The LL model better fits the exponentiated Lomax,inverse power Lomax,Lomax-Rayleigh,power Lomax,and Lomax distributions.

考虑时间变化的洪涝灾害损失评估

洪涝灾害是对我国影响最大的自然灾害之一。聚焦灾害损失评估问题,本文构建了考虑时间变化的洪涝灾害损失函数。一方面,表征灾害损失随着致灾因子强度先递增、而后增幅趋缓的静态S型曲线关系;另一方面,通过量级、形状和位置三个参数综合考虑灾害损失随时间的动态变化情况。基于《中国水旱灾害防御公报》提供的受灾人口、直接经济损失数据,对于各省级行政区2006—2021年洪涝灾害损失进行评估分析。结果表明:通过拟合洪涝灾害损失函数,洪涝灾害损失关于致灾因子强度和时间的三维空间散点图可有效地拓展成为连续的三维空间曲面及二维空间热力图。各省级行政区受灾人口整体上呈现出逐年下降的特征,但随致灾因子强度的增加而趋于增加。各省级行政区直接经济损失则表现出明显的差异,随时间呈现出大幅下降、缓慢下降和略有增加等不同特征。考虑时间变化的洪涝灾害损失函数是变化环境下灾害评估的有效工具,可为区域洪涝灾情评估提供借鉴和参考。

系统安全性评估中飞行机组人为因素的分析方法

随着飞机系统日益高度综合复杂和自动化水平逐渐提高,飞行员在应对失效或应急情况时通常准备不足,纠正动作可能是不正确、不及时或不完整的,因此系统安全性评估中迫切需要考虑飞行机组人为因素问题。通过分析CCAR25.1309(b)和(c)条款的要求和飞行机组对失效的处理过程,基于功能危险性评估中的失效状态,提出人为因素需求的捕获方法和人为因素分析方法;通过在型号中应用这些方法,从失效状态向告警和程序的角度实现安全性正向设计,建立安全性评估中飞行机组人为因素的完整适航符合性证据链。结果表明:本文提出的方法可有效表明对CCAR25.1309(b)和(c)条款中人为因素相关的适航符合性。

The Cox Proportional Hazard Regression Model Vis-à-Vis ITN-Factor Impact on Mortality Due to Malaria

This study has provided a starting point for defining and working with Cox models in respect of multivariate modeling. In medical researches, there may be situations, where several risk factors potentially affect patient prognosis, howbeit, only one or two might predict patient’s predicament. In seeking to find out which of the risk factors contribute the most to the survival times of patients, there was the need for researchers to adjust the covariates to realize their impact on survival times of patients. Aside the multivariate nature of the covariates, some covariates might be categorical while others might be quantitative. Again, there might be cases where researchers need a model that has the capability of extending survival analysis methods to assessing simultaneously the effect of several risk factors on survival times. This study unveiled the Cox model as a robust technique which could accomplish the aforementioned cases. An investigation meant to evaluate the ITN-factor vis-à-vis its contribution towards death due to Malaria was exemplified with the Cox model. Data were taken from hospitals in Ghana. In doing so, we assessed hospital in-patients who reported cases of malaria (origin state) to time until death or censoring (destination stage) as a result of predictive factors (exposure to the malaria parasites) and some socioeconomic variables. We purposefully used Cox models to quantify the effect of the ITN-factor in the presence of other risk factors to obtain some measures of effect that could describe the relationship between the exposure variable and time until death adjusting for other variables. PH assumption holds for all three covariates. Sex of patient was insignificant to deaths due to malaria. Age of patient and user status were both significant. The magnitude of the coefficient (0.384) of ITN user status depicts its high contribution to the variation in the dependent variable.

不同构型电动垂直起降飞行器动力系统的安全性评估

安全性评估对电动垂直起降飞行器的架构开发、安全管理、设计验证及商业化有着至关重要的作用,但目前国内少有对电动垂直起降飞行器整机构型、系统设计等相关的研究。本文针对4种不同构型的电动垂直起降飞行器,包括垂起尾推固定翼构型、四轴八桨多旋翼构型、固定翼加倾转旋翼构型以及倾转机翼构型,使用功能危害分析和故障树分析方法对4种不同构型的动力系统进行了分析比较。分析表明:垂起尾推固定翼电动垂直起降飞行器动力架构在本文的特定使用场景中相对可靠性更优。2种分析方法的结合,增加了对功能危害理解的全面性和深度,并识别了减轻动力系统失效风险的多种潜在途径。安全性评估结果可以为电动垂直起降飞行器动力构型选择和产品开发提供依据。

STRONG REPRESENTATIONS OF THE SURVIVAL FUNCTION ESTIMATOR ON INCREASING SETS FOR TRUNCATED AND CENSORED DATA

In this paper, based on random left truncated and right censored data, the authors derive strong representations of the cumulative hazard function estimator and the product-limit estimator of the survival function. which are valid up to a given order statistic of the observations. A precise bound for the errors is obtained which only depends on the index of the last order statistic to be included.

相关标准紫外危害评估的差异研究

紫外产品目前在世界上被广泛应用于医院、学校、家庭等场所,具有净化空气、消毒环保的作用,由于产品存在紫外波段对人体有一定的危害性,评估紫外危害程度就显得尤为重要。本文从波长采样间隔、曝辐限值、紫外危害加权函数等方面,对不同的光生物标准IEC 62471:2006、GB/T 20145—2006和ANSI/IES RP-27.1-22在紫外危害评估的差异进行了分析比较,期望能够帮助读者更深入了解不同国家或地区在光化学紫外安全相关标准之间的差异。实验随机选取了三个光谱源数据,通过参考不同区域的标准来分析光化学紫外危害评估的差异。

Local Polynomial Estimation of Distribution Functions

Under the condition that the total distribution function is continuous and bounded on （ -∞,∞ ）, we constructed estimations for distribution and hazard functions with local polynomial method, and obtained the rate of strong convergence of the estimations.

某危险化学品企业GDS系统主要功能的应用

危险化学品行业面临着易燃、易爆、高温、高压等风险,气体泄漏的检测和管控显得尤为重要。介绍了GDS系统工作原理、主要功能、设置、配套设施、控制室以及供电技术等方面的内容,通过实际运行效果,有效确保了人员安全与工业安全。

安全隐患排查治理在农机安全生产中的作用

农机安全隐患排查治理是农机监理部门的职责,是预防和减少农机事故,实施农机安全生产管理的重要环节。近年来,在诸多因素作用下,农业机械安全隐患排查治理很难落到实处,农机安全生产情况令人担忧。结合实际工作经验,分析了农机安全隐患排查治理在农机安全生产中的重要性,论述农机安全隐患排查存在的问题,提出了对策与建议。

基于RFID技术和ZigBee技术的危险品实验室安全监测系统设计

随着科学技术的不断发展,危险品实验室的安全问题日益引起人们的关注。为了提高实验室的安全性,基于射频识别(Radio Frequency Identification,RFID)技术和紫蜂协议(ZigBee)技术设计了一种危险品实验室安全监测系统,以提高实验室的安全性和管理效率。该系统通过RFID标签对实验室内的危险品进行追踪和管理,利用ZigBee技术实现实时的监测和报警功能。

危化品安全风险监测预警系统建设

随着我国工业化进程的加快和经济的快速发展,危化品的使用量和储存量不断增加,由此带来的安全风险也日益凸显。为保障人民群众的生命财产安全,建立一个高效可靠的危化品安全风险监测预警系统显得尤为重要。基于某市危化品安全风险监测预警系统的建设,文章从监测预警系统业务流程、系统架构、功能设计、系统部署等方面进行详细探讨。实践表明,该系统通过视频监控及智能分析、物联监测和预警等功能,实现了对危化品企业的实时智能监管,提高了企业现场安全管理水平,为监管部门提升监管效能奠定了基础。

山西省地表温度时空变化及其与地质灾害的关系分析

利用山西省107个国家气象站1981—2018年0 cm地表温度及崩塌、滑坡地质灾害的资料,采用线性回归、M-K检验、滑动t检验和经验正交函数(EOF)时空分离等方法,对山西省0 cm地表温度时空变化以及与地质灾害的相关性分析得出:山西省年际及四季地温均呈增温上升趋势;地温在1999年春季、2002和2004年夏季、2004年秋季、1993年冬季分别发生由冷转暖的突变,年均地温无突变。利用EOF经验正交分析得出:年和四季第一模态空间变化具有较好的一致性特征,时间序列年和四季都是从2004年之后一致表现为以正位相为主;第二模态南部和北部具有反位向变化的特征。春季崩塌、滑坡地质灾害与年、春季和秋季地温呈正相关(通过95%的检验),即年、春季和秋季地表温度由冷变暖时,春季地质灾害的发生会由少变多。夏季降水量与年和夏秋季地质灾害呈正相关(通过90%和95%的检验),但年和夏秋季地质灾害的发生略滞后于夏季降水的发生,由此也可推断夏季降水是年、夏秋季崩塌和滑坡地质灾害的主要诱发因素。

Hazard函数估计误差的极限定理

令H_n(x)是基于来自密度函数f(x)的容量为n的一个随机样本的hazard函数H(x)=f^(x)/[1-integral from x=∞ to x(f(t)dt)]的一个核形估计.对于非参数hazard估计的积分均方误差integral ((H_n(x)-H(x))~2ω(x)f(x)dx)中心极限定理成立的一个充分条件被给出,这里ω(x)是一个权函数.

Two Analytical Methods for Detection and Elimination of the Static Hazard in Combinational Logic Circuits

In this paper, the authors continue the researches described in [1], that consists in a comparative study of two methods to eliminate the static hazard from logical functions, by using the form of Product of Sums (POS), static hazard “0”. In the first method, it used the consensus theorem to determine the cover term that is equal with the product of the two residual implicants, and in the second method it resolved a Boolean equation system. The authors observed that in the second method the digital hazard can be earlier detected. If the Boolean equation system is incompatible (doesn’t have solutions), the considered logical function doesn’t have the static 1 hazard regarding the coupled variable. Using the logical computations, this method permits to determine the needed transitions to eliminate the digital hazard.