捕获再捕获与捕获移出模型的概念、方法和新进展

捕获再捕获与捕获移出研究是数理统计的一个重要方向，它研究如何利用随机样本估计有限群体的总体数目。本文对捕获再捕获与捕获移出模型的历史、基本统计思想、方法及近年来的新进展作一个简要而又较系统的回顾。     

基于分散型和扩散型随机序对几种寿命分布类的刻画

本文基于分散型和(或)扩散型随机序，利用随机变量的剩余寿命给出了寿命分布类ILR，IFR，DMRL和IFR(2)及其对偶类的刻画．作为主要结果的一个应用，用k／n-系统的剩余寿命对IFR和DMRLS及其对偶类进行了刻画．这些结果拓宽和加强了文献中已有的结果．     

Safety aspects in the use of outdoor and surveying lasers

This paper reviews the variety of laser instruments currently used in the surveying and construction industry. Their manner of use and individual function are described and an indication provided of the sources of ocular hazard they present to users and others in the vicinity of their beams. Methods of making quantitative assessment of the laser ocular hazards are then introduced in relation to the current European Standard of Laser Safety EN 60825:1991. This is followed by a discussion of practicalities in applying administrative and engineering methods of hazard control.     

Monotonicity of optimal flow control for failure-prone production systems

In this paper, we consider the problem of the optimal flow control for a production system with one machine which is subject to failures and produces one part type. In most previous work, it has been assumed that the machine has exponential up and down times, i.e., its state process is a Markov process. The system considered in our study has general machine up and down times. Our main result is establishing monotone properties for the optimal control policy.This work was partially supported by the National Science Foundation under Grants DDM-9215368 and EDI-9212122. The authors thank two anonymous reviewers for helpful comments and suggestions.     

Limit of hazard rate function of coherent system with discrete life

In this paper we study the limiting behavior of the hazard rate function of a coherent system 𝒮 whose components are independent and have discrete lifetimes. The lifetime of the system 𝒮 can be viewed as the lifetime of a parallel system consisting of the series systems obtained from the minimal paths of 𝒮. If we appropriately interpret the ‘strongest’ minimal path(s) of the system 𝒮, it will be shown that the limit of the hazard rate functions of 𝒮 is the same as that of the ‘strongest’ path(s) of 𝒮. The application of the main results are also provided. Copyright © 2010 John Wiley & Sons, Ltd.     

Actuarial applications of the linear hazard transform in life contingencies

In this paper, we study the linear hazard transform and its applications in life contingencies. Under the linear hazard transform, the survival function of a risk is distorted, which provides a safety margin for pricing insurance products. Combining the assumption of α-power approximation with the linear hazard transform, the net single premium of a continuous life insurance policy can be approximated in terms of the net single premiums of discrete ones. Moreover, Macaulay duration, modified duration and dollar duration, all measuring the sensitivity of the price of a life insurance policy to force of mortality movements under the linear hazard transform, are defined and investigated. Some examples are given for illustration.     

Simulation of crowd dynamics in pedestrian evacuation concerning panic contagion: A cellular automaton approach

The study of the panic evacuation process is of great significance to emergency management. Panic not only causes negative emotions such as irritability and anxiety, but also affects the pedestrians decision-making process, thereby inducing the abnormal crowd behavior. Prompted by the epidemiological SIR model, an extended floor field cellular automaton model was proposed to investigate the pedestrian dynamics under the threat of hazard resulting from the panic contagion. In the model, the conception of panic transmission status (PTS) was put forward to describe pedestrians' behavior who could transmit panic emotions to others. The model also indicated the pedestrian movement was governed by the static and hazard threat floor field. Then rules that panic could influence decision-making process were set up based on the floor field theory. The simulation results show that the stronger the pedestrian panic, the more sensitive pedestrians are to hazards, and the less able to rationally find safe exits. However, when the crowd density is high, the panic contagion has a less impact on the evacuation process of pedestrians. It is also found that when the hazard position is closer to the exit, the panic will propagate for a longer time and have a greater impact on the evacuation. The results also suggest that as the extent of pedestrian's familiarity with the environment increases, pedestrians spend less time to escape from the room and are less sensitive to the hazard. In addition, it is essential to point out that, compared with the impact of panic contagion, the pedestrian's familiarity with environment has a more significant influence on the evacuation.     

On allocation of redundancies in two-component series systems

Allocation of active [standby] redundancies in a system is a topic of great interest in reliability engineering and system safety because optimal configurations can significantly increase the reliability of a system. In this paper, we study the problem of allocating two exponentially distributed active [standby] redundancies in a two-component series system using the tools of stochastic ordering. We establish two interesting results on likelihood ratio ordering which have no restriction on the parameters.     

Radiometric analysis and radiological hazards of Chinese commercial marble

The activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in commercial marble materials have been determined using a NaI(Tl) γ-ray spectrometer with a matrix-inversion-based spectral stripping technique. Knowledge of radioactivity present in marble materials enables one to assess any possible radiological risks to human health. The concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in Chinese commercial marble range from 8.4 to 157.4, 5.6 to 165.5 and 44.1 to 1352.7 Bq kg^?1, respectively. The natural radionuclide concentration varied with color and production site of commercial marble. The activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in white, gray, black, green and yellow marble samples are comparatively smaller than those in brown and red marble samples. The radium equivalent activity (Ra_eq), the external hazard index (H _ex), the internal hazard index (H _in) and the annual gonadal dose equivalent were also calculated and compared with the internationally recommended values. One type of brown commercial marble (TSB) of China does not satisfy the universal standards.     

过度自信、违约补偿与众创投资平台三边道德风险规制

基于投资型众创空间运营过程中众创投资平台、风险投资机构和创业企业之间复杂的委托代理关系,构建了一个三边道德风险分析模型,将众创投资平台的过度自信倾向和风险投资机构的违约补偿引入模型设计,探讨了各利益主体的行为选择与道德风险约束。研究发现,众创投资平台过度自信对三边融资结构具有双重影响,既降低了创业企业的道德风险;又助长了投资平台的违约倾向,提高了代理成本和风险投资机构的道德风险。违约补偿可以有效规制三边道德风险,不仅降低了风险投资机构的违约行为,也有助于缓解投资平台和创业企业的道德风险。