Causality-Network-Based Critical Hazard Identification for Railway Accident Prevention: Complex Network-Based Model Development and Comparison

This study investigates a critical hazard identification method for railway accident prevention. A new accident causation network is proposed to model the interaction between hazards and accidents. To realize consistency between the most likely and shortest causation paths in terms of hazards to accidents, a method for measuring the length between adjacent nodes is proposed, and the most-likely causation path problem is first transformed to the shortest causation path problem. To identify critical hazard factors that should be alleviated for accident prevention, a novel critical hazard identification model is proposed based on a controllability analysis of hazards. Five critical hazard identification methods are proposed to select critical hazard nodes in an accident causality network. A comparison of results shows that the combination of an integer programming-based critical hazard identification method and the proposed weighted direction accident causality network considering length has the best performance in terms of accident prevention.     

Risk assessment and laser safety

The basic tenets of risk assessment have always been applied in laser safety during the development of safety standards. For example, statistical methods were used in the probit analysis of the threshold of ocular injury; concepts of risk analysis were employed in the development of hazard classes, where the increased risk of exposure and potential for injury from increasing laser output power led to assignment of an increasing hazard class. In recent years, however, there has been a number of attempts to apply statistical probability analysis in the risk assessment of actual use conditions. However, once the hazard classification has been assigned, how should one further apply the techniques of risk assessment in the determination of hazard control measures, or does this lead to a potential controversy of what is the risk? Risk analysis is the evaluation of potentially hazardous exposure conditions coupled with a realistic assessment of actual human exposure. The maximum permissible exposure values for laser radiation coupled with the laser hazards classification scheme, already permit realistic health hazard evaluations. However, in determining effective hazard control measures, one must perform a risk analysis. A risk analysis must consider aspects of human behaviour and how behaviour affects exposure. This is frequently the area of greatest controversy in the derivation of safety standards; however, it is this aspect where standards are most needed.     

Insights into hazard from intense impulses from a mathematical model of the ear

In order to provide insight into the mechanisms that operate in the ear when it is exposed to intense sounds, time and frequency domain mathematical models of the ear including significant nonlinearities in the middle ear were developed to trace energy flow from the free field to the inner ear and ultimately allow the calculation of basilar membrane displacement and a consequent hazard function. These models match the ear's behavior at low intensities and also reproduce many of the features of the data on hearing hazard from intense impulses. They provide critical insights into the loss mechanisms, suggest new strategies for protecting hearing as well as reducing hazard at the source and could also serve as a framework for a new, accurate, theoretically based method for rating hazard from intense sounds.     

一种光源的蓝光危害与节律效应可视化评估方法

为了使基层质检人员经济快速的评估光源蓝光危害与节律效应,测量了六种常见人工照明和三种显示器的光谱分布,结合QB5型钴蓝玻璃片的透射率,对九种光源透过QB5型钴蓝玻璃片的光谱分布进行计算分析,研究了光源蓝光危害因子和节律因子与1931 CIE-XYZ色坐标Z值、透过钴蓝玻璃片的主波长及明视觉光通量的关系;以人眼对波长及亮度变化的分辨力为依据,验证了以烛光为参照,根据人眼透过QB5型钴蓝玻璃片观察到的光源亮度,对光源蓝光危害与节律效应进行可视化评估的可行性。结果表明：九种光源的蓝光危害因子和节律因子均随色坐标Z值、透过钴蓝玻璃片的主波长及明视觉光通量的增大而增加;该可视化评估方法可行。研究方法与结果可为光生物安全评估与相关仪器设备开发提供参考。     

Earmuff comfort

In many industrial and military situations it is not practical or economical to reduce ambient noise to levels that present neither a hazard to hearing nor annoyance. In these situations, personal hearing protection devices are capable of reducing the noise by 20–30 dB. Although the use of a hearing protector is recommended as a temporary solution until action is taken to control the noise, in practice, it ends up as a permanent solution in most cases. Therefore, hearing protectors must be both efficient in terms of noise attenuation and comfortable to wear. Comfort in this case is related to the agreement of the user to wear the hearing protector consistently and correctly at all times. The purpose of this paper is, firstly, to provide some background on the publications related to earmuff comfort, most of which are based on measurement of the total headband force and subjective evaluation using questionnaires. Most of the published results show a weak correlation between total headband force and subjective evaluation. Secondly, this paper presents a new method to measure the contact pressure distribution between the earmuff cushions and the circumaural flesh of the human head and estimate a comfort index. The comfort parameters were investigated and equations developed to calculate comfort indices and overall quality indices. The most important calculated comfort index is measured from the contact pressure distribution and correlated with a subjective evaluation. Measurement results for the pressure distribution of 10 earmuffs show good correlation with the subjective evaluation.     

CuO and ZnO nanoparticles: phytotoxicity, metal speciation, and induction of oxidative stress in sand-grown wheat

Given the almost limitless variety of nanomaterials, it will be virtually impossible to assess the possible occupational health hazard of each nanomaterial individually. The development of science-based hazard and risk categories for nanomaterials is needed for decision-making about exposure control practices in the workplace. A possible strategy would be to select representative (benchmark) materials from various mode of action (MOA) classes, evaluate the hazard and develop risk estimates, and then apply a systematic comparison of new nanomaterials with the benchmark materials in the same MOA class. Poorly soluble particles are used here as an example to illustrate quantitative risk assessment methods for possible benchmark particles and occupational exposure control groups, given mode of action and relative toxicity. Linking such benchmark particles to specific exposure control bands would facilitate the translation of health hazard and quantitative risk information to the development of effective exposure control practices in the workplace. A key challenge is obtaining sufficient dose?Cresponse data, based on standard testing, to systematically evaluate the nanomaterials?? physical?Cchemical factors influencing their biological activity. Categorization processes involve both science-based analyses and default assumptions in the absence of substance-specific information. Utilizing data and information from related materials may facilitate initial determinations of exposure control systems for nanomaterials.     

Hidden Markov models revealing the stress field underlying the earthquake generation

The application of the hidden Markov models (HMMs) is attempted for revealing key features for the earthquake generation which are not accessible to direct observation. Considering that the states of the HMM correspond to levels of the stress field, our objective is to identify these states. The observations are considered after grouping earthquake magnitudes and the cases of different number of states are examined. The problems of HMMs theory are solved and the ensuing HMMs are compared on the basis of Akaike and Bayesian information criteria. A new insight on the evaluation of future seismic hazard is given by calculating the mean number of steps for the first visit to a particular state, along with the respective variance. We further calculate an estimator of the mean number of steps for the first visit to a particular state and we construct its confidence interval. Additionally, a second approach to the problem is followed by assuming a different determination of observations. The HMMs applied to both approaches, contribute significantly to seismic hazard assessment via revealing the number of the stress levels as well as the way in which these levels are associated with certain earthquake occurrence.     

Validation of the auditory hazard assessment algorithm for the human with impulse noise data

Predicting auditory hazard from intense acoustic impulses, such as weapons fire or airbags, has been an intractable problem. The U.S. Army developed a theoretically based mathematical model of the ear designed to predict such hazards [the Auditory Hazard Assessment Algorithm for the Human (AHAAH)]. To validate it as a predictor of hazard, data from the literature (wave forms and changes in hearing sensitivity) were processed with the model in order to predict the onset of unacceptable threshold shift (25 dB or more) in the 95th percentile human ear. For comparison, alternate standards MIL-STD-1747D and A-weighted energy were also used to compute hazards for the same data. The primary dataset was that of the US Army's "Albuquerque studies" (53 different cases) and other impulses from the literature (19 additional predictions). The AHAAH model predicted correctly in over 95% of the cases, the MIL-STD-1474D was correct in 42% of the cases, and A-weighted energy was correct in 25% of the cases. Errors for all methods tended to be in the direction of overprediction of hazard. In addition to greatly increased accuracy, the AHAAH model also has the advantage of being theoretically based and including novel diagnostic features.     

A new solver for granular avalanche simulation: Indoor experiment verification and field scale case study

A new solver based on the high-resolution scheme with novel treatments of source terms and interface capture for the Savage-Hutter model is developed to simulate granular avalanche flows. The capability to simulate flow spread and deposit processes is verified through indoor experiments of a two-dimensional granular avalanche. Parameter studies show that reduction in bed friction enhances runout efficiency, and that lower earth pressure restraints enlarge the deposit spread. The April 9, 2000, Yigong avalanche in Tibet, China, is simulated as a case study by this new solver. The predicted results, including evolution process, deposit spread, and hazard impacts, generally agree with site observations. It is concluded that the new solver for the Savage-Hutter equation provides a comprehensive software platform for granular avalanche simulation at both experimental and field scales. In particular, the solver can be a valuable tool for providing necessary information for hazard forecasts, disaster mitigation, and countermeasure decisions in mountainous areas.     

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.     

基于区域对比度的图像清晰度评价算法

高效、准确的图像清晰度评价是实现自动调焦的关键。在分析了现有图像清晰度评价方法优缺点的基础上,提出了一种基于图像区域对比度的清晰度评价新方法,建立和分析了评价函数的数学模型,并对航空摄像机采集的系列图像进行实验和仿真。与其他算法比较的结果表明:该方法具有精确度高、对比度明显等优点,能够应用于实际的图像清晰度评价和自动对焦中,克服了单纯依靠计算灰度差带来的不足,具有较高的实用性和可靠性。     

Reliability Analysis of the New Exponential Inverted Topp–Leone Distribution with Applications

The inverted Topp–Leone distribution is a new, appealing model for reliability analysis. In this paper, a new distribution, named new exponential inverted Topp–Leone (NEITL) is presented, which adds an extra shape parameter to the inverted Topp–Leone distribution. The graphical representations of its density, survival, and hazard rate functions are provided. The following properties are explored: quantile function, mixture representation, entropies, moments, and stress–strength reliability. We plotted the skewness and kurtosis measures of the proposed model based on the quantiles. Three different estimation procedures are suggested to estimate the distribution parameters, reliability, and hazard rate functions, along with their confidence intervals. Additionally, stress–strength reliability estimators for the NEITL model were obtained. To illustrate the findings of the paper, two real datasets on engineering and medical fields have been analyzed.     

基于视觉感知的光谱评估尺度

光谱颜色复现和色度精度是评价光谱重建算法准确的基础。简单而直观的评价指标对颜色复现控制是必不可少。该指标需要同时表征复现颜色的光谱差和色度差。在研究光谱匹配评估的方法基础上,提出基于颜色视觉感知的三种光谱评估指标,通过加权人眼视觉匹配函数,实现颜色光谱差与色度的评估。通过孟塞尔颜色系统的光谱数据,该论文分析与验证三种视觉加权的评估指标的有效性。通过孟塞尔颜色系统数据,这些指标在CIELab均匀色空间中分布均匀而稳定,从而证明加权算法的评估指标是既表征到颜色感知又反映出颜色的光谱相似度。实证结果表明,加权的指标可以实现同时表征实际人眼的颜色感知和颜色光谱差异。基于人眼视觉感知的评估指标解决了颜色的原始光谱和重建光谱的光谱匹配精度的定量评价问题。所提出评价指标通过一个简单而直观的数值实现对复现颜色光谱与色度评估。     

微波消解-氢化物发生-原子荧光光谱法检测烟草中的汞

采用HNO3-H2O2体系微波消解烟样,氢化物发生-原子荧光光谱法检测烟草中的Hg。通过实验对样品前处理试剂的用量,载流酸度,干扰离子的允许量等进行了优化,方法检出限0.0388μg/L、RSD为1.28%、回收率98%—102%,准确测定Hg元素在成品烟丝中的量,对于烟气的安全性评价及降低卷烟危害具有一定意义。     

火灾烟气毒害物HCl和HCN的分析及危害性评价方法

火灾是一种失去控制的燃烧,具有双重性规律。火灾产生的有害烟气是造成人员伤亡的主要原因。本文选定火灾中主要的有害燃烧产物氯化氢(HCl)和氰化氢(HCN)作为目标气体,考虑了影响实验数据的各种因素,通过对实验数据的分析,证明了“等生成率假设”在考虑火灾中其它影响因素如温度时是不正确的;分析实验浓度变化曲线达到致死浓度的关键时间,提出了一种新的火灾烟气对人员伤亡影响的危险性评价体系,为火灾燃烧有害产物释放机理研究在工程技术上的应用奠定了基础。     

基于一阶梯度信息的光谱相似度评价方法

目前的光谱相似度评价方法主要基于光谱形状和幅值两种信息,但这两种信息仅仅能体现出光谱的轮廓,并不能很好的反应地物光谱的吸收峰等“指纹”特征,为了更好的体现出光谱特征在评价中的作用,提出了基于一阶梯度信息的光谱相似度评价方法。首先对传统光谱角度匹配度评价方法SAM进行了改进,提出MSAM评价方法,进而提出了调整的梯度光谱角度匹配(MGSAM)法。MGSAM比较了两条光谱曲线的梯度角匹配度,光谱曲线的梯度信息可以突出光谱吸收峰等“指纹”特性的存在,因此MGSAM可以充分体现出两条对比曲线的光谱特征相似度。分析了偏置信息和光谱深度对于MSAM和MGSAM的影响,指出MGSAM对于偏置信息具有更强的鲁棒性,且可以客观地反映出光谱深度差异,进而直观地反映出光电系统或相关算法的光谱特征保真能力。将MGSAM作为评价方法应用到压缩感知光谱成像系统评价中,仿真结果表明,随着采样率的变化,MSAM的值在 0.998~1之间,而MGSAM的值在0.72~1之间,具有明显的变化并具有较大的差异性,可以客观地反映出压缩感知系统对于光谱特征的保真能力,并具有更强的差异化分辨力,为该类系统提供了一个更客观的评价方法。将MGSAM应用到了基于光谱相似度的地物分类中,测试数据选择了Salinas,Pavia和Indian Pines三个公开数据,结果显示基于MSAM的平均分类精度为0.86,基于MGSAM的平均分类精度0.93,由此说明MGSAM可以突出光谱特征在分类中的作用,大大提高了分类精度。     

粉体工业静电防护技术研究进展

粉体静电灾害涉及面广、危害大，开发合理的粉体静电防灾技术是国民经济发展过程中需要解决的热点问题之一．近年来，粉体静电测试研究方法、粉体静电起电与放电研究方法、粉体静电危险性评价方法、粉体静电危险性分级理论等研究工作取得了较好的研究成果．根据粉体静电现实危险性量化分析的结果而采取的粉体防静电灾害技术措施，为粉体工业生产提供了一定的安全保障．     

基于改进Apriori的网络安全感知方法

针对网络安全态势评估过程中存在数据源单一、实时性不强、准确率不高的问题,提出一种基于改进关联规则算法(Apriori算法)的网络安全态势感知方法。通过对数据的分析,发现在网络中存在关于安全态势的关联规则;通过网络攻击影响熵值序列的分析,对关联规则进行分类为空间正常和异常空间,进而对关联规则进行聚类分析;根据聚类后的规则划分网络安全态势等级。将改进后的算法应用到网络安全态势感知当中,实验结果表明,该方法满足了网络安全危险预警和实时监控的要求。改进的算法用于安全态势感知是可行的、有效的。     

基于微粒群区域搜索和小波评价的差分式自动聚焦

为进一步提高图像法自动聚焦的性能,提出了一种差分式提取图像边缘的方法,并构造了图像清晰度的小波评价函数,同时利用微粒群(PSO)算法对聚焦区域进行快速搜索。首先,介绍了差分式边缘提取方法及其优势,给出了一种评价区域的选取判据以及基于PSO的高效搜索方法;然后,对小波评价函数参数进行了比较分析和优选;最后,与传统方法进行了对比实验。结果表明,由于采用了差分式提取方法以及新的自适应聚焦窗口和评价函数,聚焦曲线较传统方法具有更高的调焦分辨率,PSO算法的使用使聚焦速度提高了约170 ms,聚焦精度约为2.3μm,同时调焦效果不受初始位置的影响。     

Quality assessment for visible and infrared color fusion images of typical scenes

Two comprehensive evaluation metrics, image perceptual quality based on target detectability (PQTD) and perceptual quality based on scene understanding (PQSU), are proposed to measure image quality for visible and infrared color fusion images of typical scenes. A psychophysical experiment is performed to explore the relationship between conventional quality attributes and the proposed evaluation metrics. The prediction models for PQTD and PQSU are derived by multiple linear regression statistical analyses. Results show that the variation of PQTD can be predicted by sharpness and perceptual contrast between the target and background, and that color harmony and sharpness can predict PQSU. The proposed evaluation metrics and their prediction models provide a foundation for further developing objective quality evaluation of color fusion images.