叛逆者追踪方案的密码学分析

对一种叛逆者追踪方案提出安全性分析,指出它存在的安全缺陷有被撤销的叛逆者可以在合法用户的帮助下继续解密新密文及合法用户可以合谋伪造有效的解密密钥。提出伪造攻击方案,并给出方案被攻击的原因。指出方案的一个设计错误,说明该方案在实际操作上是不可行的。     

基于数据挖掘和神经网络的赛马决策与分析

运用了数据挖掘技术和神经网络技术，对赛马数据信息进行自动获取和智能分析。首先，分析了目前赛马的有关数据，按照现存的数据信息创建相关的数据库；在数据的搜集方面，建立了一个提取器，在一些网页中读取有关的数据，大大提高了系统自动获取数据的能力；在分析与预测方面，结合了神经网络逻辑建立一个数学线性回归方程，其功能是通过已有的大量的数据资料预测出将要进行的赛事结果，即参加该场赛事的所有马匹的成绩排名。系统主要包括管理模块、数据查询模块、预测模块3大模块，其中预测模块是核心，它是利用对赛马结果有一定影响的13个因素进行数据分析，得出一个预测时间，再与由优先级数据筛选得出的时间值通过两个调节参数做出修正，得出最终的预测结果。     

Study of human–seat interface pressure distribution under vertical vibration

The influence of whole-body vertical vibration on the dynamic human–seat interface pressure is investigated using a flexible grid of pressure sensors. The ischium pressure and the overall pressure distribution at the human–seat interface are evaluated as functions of the magnitude and frequency of vibration excitation, and seated posture and height. The dynamic pressure at the seat surface is measured under sinusoidal vertical vibration of different magnitudes in the 1–10 Hz frequency range. Two methods based on ischium pressure and ischium force are proposed to study the influence of seat height, posture and characteristics of vibration. The results of the study reveal that the amplitude of dynamic pressure component increases with an increase in the excitation amplitude in almost entire frequency range considered in this study. The dynamic components of both the ischium pressure and the ischium force reveal peaks in the 4 to 5 Hz frequency band, the range of primary resonant frequency of the seated human body in the vertical mode. The mean values of the dynamic ischium pressure and the ischium force remain constant, irrespective of the excitation frequency and amplitude. The magnitudes of mean pressure and force at the human–seat interface, however, are dependent upon the seat height and the subject's posture. The inter-subject variability of the static ischium pressure and effective contact area are presented as functions of the subject weight and subject weight-to-height ratio. It was found that heavy subjects tend to induce low ischium pressure as a result of increased effective contact area.

Relevance to industry

Pressure distribution at the human–seat interface has been found to be an important factor affecting the seating comfort and work efficiency of various workers. The study of human–seat interface pressure distribution under vibration is specifically critical to the comfort, work efficiency and health of vehicle drivers, who are regularly exposed to vibration. The results reported in this paper will be useful to study dynamic response of the interface pressure and design vehicle seats.     

Chosen postures during specific sitting activities

This research study analysed the interaction between people's postures and activities while in semi-public/leisure situations and during transportation (journey by train). In addition, the use of small electronic devices received particular emphasis. Video recordings in German trains and photographs in Dutch semi-public spaces were analysed using a variation of Branton and Grayson's (An evaluation of train seats by observation of sitting behaviour. Ergonomics, 10 (1), (1967), 35–51) postural targeting forms and photos. The analysis suggests a significant relationship between most activities and the position of the head, trunk and arms during transportation situations. The relationship during public situations is less straightforward. Watching, talking/discussing and reading were the most observed activities for the transportation and leisure situations combined. Surprisingly, differences in head, trunk, arm and leg postures were not significant when using small electronic devices. Important issues not considered in this study include the duration of the activities, the gender and age of observed subjects and the influence of the time of day. These are interesting issues to consider and include for future research.

Statement of Relevance: This study shows what activities people choose to carry out and their related postures when not forced to a specific task (e.g. driving). The results of this study can be used for designing comfortable seating in the transportation industry (car passenger, train, bus and aircraft seats) and semi-public/leisure spaces.     

基于巴哈越野车的一种儿童赛车防倾装置

巴哈赛车是非常典型的高速越野型车辆,常在野外或沙地中行驶,大部分人尤其是青少年及儿童较难接触巴哈赛车并体验驾驶。若使儿童赛车能够实现安全、高速的巴哈赛车体验,有助于更早的让儿童接触中国的车辆知识,这对未来中国在汽车业的发展有所帮助。因此,采用对巴哈赛车的应力分析与物理计算方式,通过数据分析与控制系统改变车辆重心的方式,制造出有效防止儿童越野赛车倾倒的装置。使儿童越野车能够更安全的体验与发展。     

On drop-tower test methodology for blast mitigation seat evaluation

Blast mitigation seats have been employed in armored vehicles to protect occupants from injuries caused by improvised explosive devices (IEDs). Currently, there exist no standard experimental evaluation methods that can be used to fully assess the protection capability of a particular seat design. For historical reasons, drop-towers have been used extensively for such purpose, as a repeatable laboratory method with some limitations. In this paper, the authors developed analytical models to study the difference between results obtained from a drop tower test and those from actual blast events. It was found that the selection of the test method had a significant effect on the results. In particular, it was found that the drop-tower methodology can often overestimate the performance of blast mitigation seats, which can result in the fielding of sub-optimal solutions for the protection of occupants.     

老山自行车馆大厅自然排烟系统性能研究

采用性能化防火设计思想，分析老山自行车馆大厅的排烟系统所应达到的安全目标，设计了可能发生的火灾场景，使用CFD技术研究自然排烟系统的性能，通过数值模拟给出发生火灾时的流场和温度分布，证实大厅自然排烟系统能够保证人员安全疏散，满足该建筑消防安全要求。     

改进Viterbi算法在机动目标跟踪中的应用

为在不影响检测概率的情况下有效降低计算量，在一种适用于机动目标且对目标的观测噪声未加任何限制的模型检测与跟踪算法中，采用了改进自适应Viterbi算法。针对Viterbi算法计算量大，实时性较差的缺点，采用一种改进的自适应算法，即结合Viterbi—Beam和Viterbi—Window算法以减少原Viterbi算法中的冗余状态，同时保证差错率无明显提高。我们通过对此算法的仿真表明，在相同的多目标跟踪仿真环境下，改进自适应Viterbi算法可以更有效地提高计算速度。且算法性能与原Viterbi算法相似。     

The effect of seating location on the injury of properly restrained children in child safety seats

Properly restrained child passengers in the National Automotive Sampling System (NASS), General Estimates System (GES), were studied for the effect of seating position on the risk of injury. The analysis focused on children seated in a child safety seat in a rear seat location. A multiple logistic regression model was used to assess whether the center rear seat is a safer seating position than either of the outboard rear seats. Standard errors for the odds ratios (ORs) of injury for several correlates of injury including seating position were obtained using a jackknife procedure. This analysis of the data showed that the center rear seat is not a safer seating position than either of the outboard rear seats in terms of odds of injury (left seat OR = 0.88, 95% CI = 0.73-1.03; right seat OR = 1.03, 95% CI = 0.85-1.20). These results do not agree with those of previous studies that suggested the center rear seat is the safest position for parents to place a child safety seat.