基于SPSS因子分析的舰载机航材保障风险因素分析

为做好舰载机航材保障风险管理工作,必须对其可能存在的风险因素进行深入、细致的分析,查找出其关键风险因素并研究风险因素之间的关系。因此,文章在依据舰载机航材保障风险因素初步识别结果的基础上,通过调查问卷的方式,归纳总结出21个舰载机航材保障风险因素,并利用SPSS统计软件和因子分析法对调查问卷的结果进行分析和计算,最终提炼出具有代表性的7个公共因子,从而完成了舰载机航材保障关键风险因素的确定和分类。     

Biomonitoring and risk assessment on earth and during exploratory missions using AquaHab

Bioregenerative closed ecological life support systems (CELSS) will be necessary in the exploration context revitalizing atmosphere, waste water and producing food for the human CELSS mates. During these long-term space travels and stays far away from Earth in an hostile environment as well as far for example from any hospital and surgery potential, it will be necessary to know much more about chemical and drug contamination in the special sense and by human’s themselves in detail.     

对银行信贷风险形成因素的分析

银行信贷风险是重要的金融风险，笔者对银行信贷风险形成机理和因素作了较详细地分析。     

军用飞机推行综合保障工程的研究

阐述了ILS的涵义及ILS在军用飞机形成战斗力中的重要作用,结合军用飞机实施ILS的现状,对大力推行军用飞机ILS的实施提出了几点建议。     

Assessment of the consequences of the Fengyun-1C breakup in low Earth orbit

On 11 January 2007, the People’s Republic of China conducted a successful anti-satellite test against one of their defunct polar-orbiting weather satellites. The target satellite, called Fengyun-1C, had a mass of 880 kg and was orbiting at an altitude of about 863 km when the collision occurred. Struck by a direct-ascent interceptor at a speed of 9.36 km/s, the satellite disintegrated, spreading the cataloged fragments between 200 and 4000 km, with the highest concentration near the breakup height. By the end of April 2008, 2377 pieces of debris, including the original payload remnant, had officially been cataloged by the US Space Surveillance Network. Of these, nearly 1% had reentered the Earth’s atmosphere. This deliberate act is the largest debris-generating event on record, and its consequences will adversely affect circumterrestrial space for many years.     

民航机场风险评价模型应用探讨

机场安全是民航安全管理的重点之一,是正确的指导民航风险管理工作的重要内容.在对民航机场进行风险因素辨识及风险分析的基础上,利用层次分析法和模糊数学理论建立了民航机场风险评价模型,并以首都机场为评价对象,对其进行了风险评价.     

Cellular communication and “non-targeted effects”: Modelling approaches

During the last decade, a large number of experimental studies on the so-called “non-targeted effects”, in particular bystander effects, outlined that cellular communication plays a significant role in the pathways leading to radiobiological damage. Although it is known that two main types of cellular communication (i.e. via gap junctions and/or molecular messengers diffusing in the extra-cellular environment, such as cytokines, NO etc.) play a major role, it is of utmost importance to better understand the underlying mechanisms, and how such mechanisms can be modulated by ionizing radiation. Though the “final” goal is of course to elucidate the in vivo scenario, in the meanwhile also in vitro studies can provide useful insights. In the present paper we will discuss key issues on the mechanisms underlying non-targeted effects and cell communication, for which theoretical models and simulation codes can be of great help. In this framework, we will present in detail three literature models, as well as an approach under development at the University of Pavia. More specifically, we will first focus on a version of the “State-Vector Model” including bystander-induced apoptosis of initiated cells, which was successfully fitted to in vitro data on neoplastic transformation supporting the hypothesis of a protective bystander effect mediated by apoptosis. The second analyzed model, focusing on the kinetics of bystander effects in 3D tissues, was successfully fitted to data on bystander damage in an artificial 3D skin system, indicating a signal range of the order of 0.7–1 mm. A third model for bystander effect, taking into account of spatial location, cell killing and repopulation, showed dose–response curves increasing approximately linearly at low dose rates but quickly flattening out for higher dose rates, also predicting an effect augmentation following dose fractionation. Concerning the Pavia approach, which can model the release, diffusion and depletion/degradation of candidate signals (e.g. cytokines) travelling in the extra-cellular environment, the good agreement with ad hoc experimental data obtained in our laboratory validated the adopted approach, which in the future can be applied also to other candidate signals.     

Micro-meteoroids and space debris impact risk assessment for the ConeXpress satellite using ESABASE2/Debris

Micro-meteoroid and space debris impact risk assessments are performed to investigate the risk from hypervelocity impacts to sensitive spacecraft sub-systems. For these analyses, ESA’s impact risk assessment tool ESABASE2/Debris is used. This software tool combines micro-particle environment models, damage equations for different shielding designs and satellite geometry models to perform a detailed 3D micro-particle impact risk assessment. This paper concentrates on the impact risk for exposed pressurized tanks. Pressure vessels are especially susceptible to hypervelocity impacts when no protection is available from the satellite itself. Even small particles in the mm size range can lead to a fatal burst or rupture of a tank when impacting with a typical collision velocity of 10–20 km/s. For any space mission it has to be assured that the impact risk is properly considered and kept within acceptable limits. The ConeXpress satellite mission is analysed as example. ConeXpress is a planned service spacecraft, intended to extend the lifetime of telecommunication spacecraft in the geostationary orbit. The unprotected tanks of ConeXpress are identified as having a high failure risk from hypervelocity impacts, mainly caused by micro-meteoroids. Options are studied to enhance the impact protection. It is demonstrated that even a thin additional protective layer spaced several cm from the tank would act as part of a double wall (Whipple) shield and greatly reduce the impact risk. In case of ConeXpress with 12 years mission duration the risk of impact related failure of a tank can be reduced from almost 39% for an unprotected tank facing in flight direction to below 0.1% for a tank protected by a properly designed Whipple shield.     

Collision Probabilities for Keplerian Orbits

We present a new derivation of the probability of collisions between spherical satellites occupying Keplerian orbits. The equations follow from the central concept of the instantaneous collision rate, an expression that describes the occurrence of collisions by using a Dirac -function. The derivation proceeds by showing how this instantaneous collision rate can be averaged over orbital mean anomaly angles and, additionally, over orbital precession angles to generate expressions appropriate for intermediate and long time scales. Collision rates averaged over mean anomalies tend to be non-zero during relatively brief collision seasons, when the peak collision probability may exceed the long-term average by several orders of magnitude. Derived precession-angle averages have a functional form similar but not identical to the collision probability expression derived using the spatial density approach of Kessler (Icarus, 48: 39–48, 1981), and the two methods have been found to yield numerical results to within 1% for all cases examined.