Consequence analysis by means of characteristic curves to determine the damage to humans from the detonation of explosive substances as a function of TNT equivalence

In a previous paper, the characteristic overpressure–impulse–distance curves for the detonation of explosive substances were presented. They allow the overpressure and impulse to be determined at each distance from the detonation. When combined with damage criteria (such as those shown by the Probit equations), the characteristic curves allow consequence analysis for this kind of explosion to be carried out in only one step, as the damage is shown in the same diagram as the overpressure, impulse and distance. In this paper, diagrams and equations are presented to determine the damage to humans (eardrum rupture, death due to displacement and skull fracture, death due to displacement and whole body impact, and death due to lung damage or lung haemorrhage).     

Modelling of time-varying dispersion for elevated pressurised releases without rainout

Many commonly used atmospheric dispersion models are limited to continuous or instantaneous releases only, and cannot accurately simulate time-varying releases. The current paper discusses a new enhanced dispersion formulation accounting for time-varying effects resulting from a pressure drop in a vessel or pipe, and presuming no rainout. This new formulation is implemented in the Unified Dispersion Model (UDM), and is planned to be included in a future version of Phast.First existing methods are summarised for modelling finite-duration and time-varying releases, and limitations of these methods are identified.Secondly the new mathematical model is summarised. The new formulation presumes a number of ‘observers’ to be released at successive times from the point of discharge. The UDM carries out pseudo steady-state calculations for each observer, where the release data correspond to the time at which the observer is released. Subsequently the model applies a correction to the observer concentrations to ensure mass conservation when observers move with different velocities. Finally effects of along-wind diffusion (due to ambient turbulence) are included by means of Gaussian integration over the downwind distance. This results in reduced concentrations while the cloud travels in the downwind direction.The benefits of the new UDM methodology are illustrated for the case of a H₂S toxic release from a long pipeline representative of some extremely sour fields in the Middle East that are now being developed. Using corrected observer concentrations and along-wind diffusion significantly reduces toxic effect distances when compared to the current Phast 7.1 approach.     

Determining Attenuation of Impulse Noise With an Electrical Equivalent of a Hearing Protection Device

Determining the effectiveness of impulse noise attenuation with hearing protection devices (HPDs) is an important part of their selection. Measuring impulse noise parameters under an HPD would involve exposing subjects to impulses with a high peak sound pressure level. This paper presents a computational method of determining impulse noise parameters under the cups of earmuffs. Calculations are done using the transfer function of earmuffs, determined with Shaw’s electrical equivalent of an HPD, taking into account the design parameters of earmuffs. The developed method was used for calculations in the presence of impulse noise generated by gunshots. To verify the computational method, the results of these calculations were compared with the results of measurements.     

Using Sound to Reduce Visual Distraction from In-vehicle Human–Machine Interfaces

Objective: Driver distraction and inattention are the main causes of accidents. The fact that devices such as navigation displays and media players are part of the distraction problem has led to the formulation of guidelines advocating various means for minimizing the visual distraction from such interfaces. However, although design guidelines and recommendations are followed, certain interface interactions, such as menu browsing, still require off-road visual attention that increases crash risk. In this article, we investigate whether adding sound to an in-vehicle user interface can provide the support necessary to create a significant reduction in glances toward a visual display when browsing menus.

Methods: Two sound concepts were developed and studied; spearcons (time-compressed speech sounds) and earcons (musical sounds). A simulator study was conducted in which 14 participants between the ages of 36 and 59 took part. Participants performed 6 different interface tasks while driving along a highway route. A 3 × 6 within-group factorial design was employed with sound (no sound /earcons/spearcons) and task (6 different task types) as factors. Eye glances and corresponding measures were recorded using a head-mounted eye tracker. Participants’ self-assessed driving performance was also collected after each task with a 10-point scale ranging from 1 = very bad to 10 = very good. Separate analyses of variance (ANOVAs) were conducted for different eye glance measures and self-rated driving performance.

Results: It was found that the added spearcon sounds significantly reduced total glance time as well as number of glances while retaining task time as compared to the baseline (= no sound) condition (total glance time M = 4.15 for spearcons vs. M = 7.56 for baseline, p =.03). The earcon sounds did not result in such distraction-reducing effects. Furthermore, participants ratings of their driving performance were statistically significantly higher in the spearcon conditions compared to the baseline and earcon conditions (M = 7.08 vs. M = 6.05 and M = 5.99 respectively, p =.035 and p =.002).

Conclusions: The spearcon sounds seem to efficiently reduce visual distraction, whereas the earcon sounds did not reduce distraction measures or increase subjective driving performance. An aspect that must be further investigated is how well spearcons and other types of auditory displays are accepted by drivers in general and how they work in real traffic.     

A global index of acoustic assessment of machines-results of experimental and simulation tests

A global index of machines was developed to assess noise emitted by machines and to predict noise levels at workstations. The global index is a function of several partial indices: sound power index, index of distance between the workstation and the machine, radiation directivity index, impulse and impact noise index and noise spectrum index. Tests were carried out to determine values of the global index for engine-generator; the inversion method for determining sound power level was used. It required modelling each tested generator with one omnidirectional substitute source. The partial indices and the global index were simulated, too. The results of the tests confirmed the correctness of the simulations.     

城际铁路环境影响评价中道路交通噪声现状评价与预测

在统计某县公路类型、规模的基础上,选择代表性区段测试高速公路、国道、省道、县道、乡道、村道交通噪声影响状况,计算了达到不同声环境功能区的控制距离要求.研究结果表明,该县境内平均道路交通噪声水平昼间、夜间均可满足《声环境质量标准》(GB 3096-2008)中4a类声环境功能区标准要求.现状条件下若要达到1类声环境功能区...     

Analysis of noise pollution in an andesite quarry with the use of simulation studies and evaluation indices

This paper presents the verification of two partial indices proposed for the evaluation of continuous and impulse noise pollution in quarries. These indices, together with the sound power of machines index and the noise hazard index at the workstation, are components of the global index of assessment of noise hazard in the working environment of a quarry. This paper shows the results of acoustic tests carried out in an andesite quarry. Noise generated by machines and from performed blasting works was investigated. On the basis of acoustic measurements carried out in real conditions, the sound power levels of machines and the phenomenon of explosion were determined and, based on the results, three-dimensional models of acoustic noise propagation in the quarry were developed. To assess the degree of noise pollution in the area of the quarry, the continuous and impulse noise indices were used.     

Noise generated by multiple-jet nozzles with conical profiles 287

Conical multiple-jet nozzles, which reduce the risk of nozzle openings being blocked, are tested for their effectiveness in noise reduction. Nozzles with different exit spacings are tested. It is found that the multiple-jet design significantly decreases noise levels in the audible range by shifting emitted sound power to higher and ultrasonic frequencies. No significant difference in noise characteristics between exits distributed on a flat plane and beveled exits on a conical surface is observed. When the exits are more densely distributed, there is a trend of spectra shifting back toward the low frequency. This phenomenon is found to increase sound levels in a certain range of frequencies much lower than the peak one. Although this increase contributes little to the total emitted sound power, it is an important factor in determining the sound levels of audible noise.     

Characteristic overpressure–impulse–distance curves for the detonation of explosives, pyrotechnics or unstable substances

A number of models have been proposed to calculate overpressure and impulse from accidental industrial explosions. When the blast is produced by explosives, pyrotechnics or unstable substances, the TNT equivalent model is widely used. From the curves given by this model, data are fitted to obtain equations showing the relationship between overpressure, impulse and distance. These equations, referred to here as characteristic curves, can be fitted by means of power equations, which depend on the TNT equivalent mass. Characteristic curves allow determination of overpressure and impulse at each distance.     

Estimation of pressure distribution for shock wave through the bend of bend laneway

Propagation of the air shock wave caused by explosion via the bend of a bend laneway has obvious nonlinear characteristics, compared with its propagation in a straight laneway. These characteristics are important bases to analyze the accident of gas explosion in underground mines and to estimate the blast resistance of underground structures in mines. In this work, the rule of the shock wave propagation via the laneway bend and the pressure distribution are studied by means of the numerical simulation approach. Theoretical results show that attenuation of the peak overpressure with distance does not obey exponent law when the air shock wave goes through the laneway bend. At some locations within the bend zone, the overpressures are higher than ones around those locations, the front of original plane wave bends in the bend of the laneway and after passing through the bend, it gradually returns to the state of plane wave propagation. There is a span dependent on the cross section dimension of laneway and the bend angle and increasing with the bend angle, in which the peak overpressure of shock wave does not uniformly attenuate with distance. When the bend angle is equal to 135°, this span is about five times as long as the corresponding equivalent diameter of the laneway. Additionally, the impulse of air shock wave attenuates uniformly via the laneway bend. On the end section of the complicated pressure distribution area in the bend, it is 66.65–98.7% of that in the straight laneway at the same scaled distance.     

古商业街木结构建筑防火间距的数值模拟研究

古商业街木结构建筑较多,防火间距先天不足,发生火灾后蔓延迅速,有必要开展木结构建筑引燃特性研究以获得合理的防火间距设置参数.以古商业街为研究对象,以临界温度和热辐射强度作为着火建筑对面木结构建筑被引燃的判定指标,综合考虑环境风速、建筑间距、火源功率、喷淋系统等因素,运用火灾动力学模拟软件FDS分析系列火灾场景下的温度和...     

单兵用主动式听力保护技术研究现状分析

战场噪声是造成单兵听力损伤的重要原因,通常要求单兵处于大于85dBA的噪声环境中需佩戴听力保护装置。听力保护装置通常包括耳罩式和耳塞式。新型单兵用耳塞式听力保护装置具有听力保护、环境声音的监听、持续及脉冲噪声抑制、通信接入等多种功能。     

输电线路铁塔基础安全综合评价体系

目前关于输电铁塔基础结构安全评价的文献较少。针对输电线路铁塔基础安全评价问题,首先,确定了输电线路铁塔基础安全评价指标体系;然后,采用层次分析法和模糊综合判断法构建了输电线路铁塔基础安全评价模型,详细分析了材料表观、环境及材料等多重指标,建立了一套比较完整的输电线路铁塔基础安全评价方法。采用该方法,先用层次分析法计算指标权重,再用模糊综合判断法进行安全评估。结果表明,输入铁塔基础结构的表观因素、环境因素及材质因素等,可对其各安全影响因素进行分级评价,确定输电线路铁塔基础的安全等级。     

石油化工行业可接受风险水平研究

石油化工行业存在着巨大的潜在风险,为了明确该行业的风险可接受水平,制定一个合理可行的可接受风险准则极为必要.本文在对国内外风险可接受水平研究的基础上,系统分析了国内外有关标准,对生命风险水平、经济风险水平和环境风险水平确定的基本思想进行了详尽阐述,分别给出了3种风险的可接受水平公式,提出了确定石化行业可接受风险水平的方法,需同时满足可接受生命风险、经济风险和环境风险.     

垂管方式对环境监测质量管理体系的建设性意见

实现环境监测领域的垂直管理是国家做出的一项重要决定。这样有利于全面提高环境监测的质量,满足日益严格的环境监测质量工作需求。因此就需要创建出更加优质的环境检测质量管理体系,完善法律法规,利用垂直管理方式来全方位提高工作效果。本文将对利用垂管方式建设环境监测质量管理体系进行深入研究。     

论环境安全问题

将环境安全分为生产技术性的环境安全和社会政治性的环境安全两类。认为广义的环境安全是指人类赖以生存发展的环境处于一种不受污染和破坏的安全状态,或说人类和世界处于一种不受环境污染和环境破坏的危害的良好状态,它表示自然生态环境和人类生态意义上的生存和发展的风险大小。分析了当代环境安全问题的严重性和主要表现,包括劳动环境。生活环境和生态环境的安全问题,以及环境问题在传统的国家安全和军事活动领域的反映,认为环境安全是可持续发展观的一个核心观点;可持续发展要求满足全体人民的基本需要,而维护环境安全正是人们的一种基本需要,分析了外国,国际社会和中国对环境安全问题的法律控制概况。介绍了一些重要领域的环境安全法观。     

军民航空域安全评估中的碰撞风险研究

碰撞风险是空域安全评估的重要内容。为保证军民航的安全飞行,通过对民航Event模型碰撞风险的研究,构建了军航训练空域与民航航路的碰撞风险模型;根据军航飞机的飞行特点,建立了军航飞机侧向位置偏差概率模型;结合民航飞机的横向位置偏差概率模型重新计算Event模型中的碰撞盒穿越间隔片频率(GERh);选取某一战术动作对军民侧向碰撞风险进行仿真,确定其安全间隔;通过对飞行过程中各个关键点碰撞风险的研究,对空域的使用提出建议,并验证了理论的实用性。结果表明,当前10 km的安全间隔标准并不能符合规定的安全目标等级,至少需要再增加7 km的安全间隔才能使整个飞行过程均满足要求。     

基站电磁辐射防护与环境监管对策分析

移动通信基站是实现通信信号覆盖的重要设备,是保证移动信号覆盖范围与信号质量的基础支撑。现阶段,随着我国现代化、城市化进程不断加快,移动通信基站的架设密集度极大的增加,为实现移动信号全覆盖,为人们的生产生活提供便利发挥重要作用。但是,基站运行过程中,产生的电磁辐射可能会对人体健康造成不利影响。因此,加强基站电磁辐射防护与环境监管是非常必要的。本文对基站电磁辐射安全距离的有效评估进行了分析,提出了基站电磁辐射防护与环境监管的有效对策。     

密闭管道瓦斯爆炸冲击波冲量及压力上升速率的实验研究

针对矿井瓦斯爆炸破坏模式主要在压力破坏和冲量破坏的研究,实验分析瓦斯在密闭管道发生爆炸时瓦斯浓度对冲击波冲量及压力上升速率的影响,利用管道中距离点火源不同位置的压力传感器测试了不同浓度瓦斯的爆炸压力,对冲击波冲量及压力上升速率进行分析,为防爆抑爆提供依据。研究结果显示:在管道中距离点火源的不同位置上,当浓度为9.5%时,瓦斯爆炸冲击波冲量及压力上升速率最大;由于超压衰减和传播距离的增加,在距离点火源4m和8m时压力冲量较大;在瓦斯浓度较低的范围内瓦斯爆炸时,其压力上升速率增长较快,而随着浓度的增加在较宽的浓度范围内,能较稳定地维持在高位值。