护听器个人防护值验证技术

本文介绍了关于护听器实际防护值的研究数据,和用于护听器个人防护效果验证的方法,以及3ME-A-RfitTM听力防护验证系统。研究表明,护听器的标称降噪值对其实际防护值的指示性非常差,目前也还没有一个可靠的方法来使用护听器的标称值。3ME-A-RfitTM听力防护验证系统是使用实地真耳内置麦克风(F-MIRE)方法,在实际工作现场中快速、定量地测定护听器在具体使用者身上取得的个人声衰减值(PAR),让安全管理人员对员工实际获得的防护水平有清晰的了解。     

让实验室测试值更贴近真实世界防护值——护听器的声衰减值评价方法讨论

本文介绍了护听器声衰减值的评价方法,对比了我国、ISO、欧洲EN、美国ANSI和澳大利亚新西兰AS/NZS标准中关于护听器声衰减值评价方法的差异。着重讨论在测试过程中,使用不同的受试者和护听器佩戴方式得出的检测数据与真实世界防护值的一致性情况。研究表明,使用"受试者自行佩戴"的方式测得的数据能更好地反映护听器在真实世界的防护性能。     

护听器选择方法研究

简要介绍了护听器选择原则和一般要求,比较了评价护听器声衰减性能和选择护听器的常用方法,结合我国国情,给出了选择护听器的建议。     

护听器个人防护值验证的新方法

面对噪声的危害,佩戴护听器是很常用的方法。关于护听器的使用,企业的安全管理人员和职业卫生专家们很关心的问题是:在实际工作现场,通过佩戴护听器,到底员工获得了多少防护呢?护听器包装上标称的声衰减值,能够准确地反映员工在真实世界使用时获     

头部防护工作组召开护听器测试专业实验室建设研讨会

正新国标GB/T 31422-2015《个体防护装备护听器的通用技术条件》于2015年5月15日发布,2015年10月1日起实施。近年来国内多家检测机构对建设护听器的测试实验室进行了前期调研,可见听力保护和护听器受到越来越多的关注。2015年3月,头部防护工作组曾召开技术研讨会,多位专家就护听器的声衰减、标称值和质量控制     

护听器国际标准及对我国护听器标准的思考

本文基于目前欧盟和ISO护听器标准的现状、各标准间的关系及今年欧盟与护听器相关的法规和标准更新动态,结合全球护听器法规和标准的制定趋势,对我国护听器标准制定和实施的要点和难点进行了讨论。     

护听器的特点、选用及其管理

护听器是一种保护听觉、使人免受噪声过度刺激的个体防护装备.为了预防在高噪声环境中的疲劳、听力损失或因此而可能导致的误操作和生产安全事故,工业企业噪声作业场所相关从业人员应配备适宜的护听器.全面了解护听器类个人防护用品的特点、正确掌握选用护听器类产品的原则和方法以及建立行之有效的管理体系是践行我国安全生产法、职业病防治法的重要环节.本文在简要分析护听器类产品的分类和特点的基础上,详细介绍了护听器的选择原则及如何选用护听器产品;最后讨论了护听器管理及人员培训的重要性.     

听阈位移法测量护听器降噪值

使用护听器是最常用的降低雇员噪声暴露的方法之一。选择适合使用的护听器受很多因素影响,护听器降噪值是首要因素之一。本文所介绍的一些信息．可对护听器降噪值测量的一些细节问题进行说明。     

护听器使用现场调查与选用规范探析

正依据标准制定的标称值扣减方法选择、配备护听器,是多年来普遍的做法。这样看来似乎"简化"了听力保护工作,但是,这样做无法确切了解员工的实际防护情况,没有从根本上解决问题。大量研究已经表明,护听器的标称值不能准确反映护听器在实际现场的防护性能。     

护耳器使用现状评述

研究表明：护耳器现场使用实际声衰减值低于实验室值,其原因是护耳器的实验室测量条件较为严格。工人在现场实际使用护耳器时,未能同实验室中的受试者一样佩戴护耳器,因而获得的护耳器声衰减比实验室所测得的值低。另一方面,在８小时强噪声环境中工作期间,未自始至终佩戴护耳器,则也达不到预期的保护听力的效果。笔者还综合分析和评述了护耳器现场使用时实际声衰减值降低的原因,并提出了一些有益的建议     

Hearing Protectors: Topicality and Research Needs

Occupational noise specialists do not generally recommend hearing protection devices (HPDs) as a preferred solution to noise risk prevention. Nevertheless, these devices are widely used and are in fact often necessary. Selection of an HPD should take into account comfort and the capacity for perceiving external signals, when they are worn. Current European regulations require that HPD attenuation be considered, when comparing noise exposure to limit values. However, HPD attenuation is effectively unknown under real-world conditions. Some methods are designed to give approximate attenuation values and these provide results within a wide statistical range. Field measurement methods and current standards have been developed to deal with this situation. The specific characteristic of impulse noise requires establishment of dedicated criteria and tools for HPD selection and testing. This paper introduces a number of avenues for research, which could be of assistance in improving HPD selection, qualification and design.     

环空带压气井保护液液位测试方法研究

为了有效检测环空保护液位,评估气井环空带压情况,在传统回声法检测的基础上,提出了基于频谱分析及自相关分析的2种液位检测方法;搭建了液位检测试验系统,开展了不同环空压力下的液位检测试验,计算了不同压力下的环空声速;设计了FIR低通滤波器对液面回波信号进行滤波处理,同时利用了上述2种方法计算液位值并与实际值及传统液位计算方法对比,得出了声衰减系数并评判了衰减过程对液面回波信号频谱分析的影响程度。研究结果表明:设计的FIR低通滤波器适用于所建液位检测试验的滤波处理过程;频谱分析及自相关分析都能够有效检测液位高度,最大误差分别为1.65%和0.61%,自相关分析方法具有更高的精确度;声衰减系数整体较小,对液面回波信号频谱分析结果影响较小。     

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.     

Assessing the performance of motorcyclists’ impact protectors in simulated ATD knee and shoulder impacts

Objective: Fractures are a common injury among motorcycle riders and can have serious health implications. Impact protection (IP) has been designed to help prevent fractures, yet there are conflicting opinions as to whether this IP does in fact help prevent fractures in real-world crashes. This work aimed to (1) use simulated dummy impacts to examine whether existing types of IP could reduce the force transferred to the underlying bone to below fracture tolerance levels and (2) investigate whether current European Standard (EN 1621-1) test procedures for impact protectors designed for motorcyclists are sufficient to ensure fracture protection.

Method: Twenty-three shoulder and 7 knee IP specimens were tested using a 23-kg impactor contacting axially along the clavicle and femur of an anthropomorphic test device (ATD) at an energy level corresponding to the fracture tolerance of these bones. Sixteen IP specimens were the same as those worn by motorcycle riders involved in crashes where injury outcome was known (knee: n?=?3; shoulder: n?=?13) and the IP had been previously tested to EN 1621-1. Other IP tested represented a wide range of IP available for purchase at a motorcycle accessory store. Double and triple layers of IP were also tested. Energy attenuated during the dummy impacts was compared to energy attenuated when tested to EN 1621-1.

Results: Of the 23 shoulder IP tested, the average percentage reduction of transferred force to the shoulder from the baseline test was 7.6?±?4.8%. The percentage reduction of transferred force to the knee from the baseline was 43.9?±?7.5%. The entire group of knee IP tested reduced the transferred force to the knee to below the 10-kN injury threshold for the femur. There was a positive but nonsignificant correlation between the ATD test and the EN 1621-1 impact test performance, suggesting that the European standard test method likely provides a good indication of IP performance. However, given the low correlation coefficient, the relationship between IP performance in the European standard test method and injury protection remains unclear.

Conclusion: Though the energy attenuation test method in the European standard may be an appropriate approach, distinct differences in injury protection performance observed between knee and shoulder IP indicate that there may be a need for different performance criteria for IP designated to protect different body regions.     

建筑材料火灾烟气减光性能的试验研究

笔者以木材、纺织品和塑料(聚苯乙烯) 3类材料作为高层建筑常用的可燃性建筑材料,对其在燃烧状态下释放的烟气进行了减光性能试验,研究了3种建筑材料在燃烧状态下,释放烟气的光学密度、减光系数、能见度及其相互关系,并建立了简明的函数关系式。通过试验,其结果表明,3种建筑材料释放烟气的光学密度随时间呈线性增长,烟场内疏散标志的能见度与烟气的减光系数、燃烧建材的性质、室内其他照明装置的开闭、疏散标志自身的亮度有关     

声发射检测灵敏度校准声源实验分析

在声发射技术的应用中,传感器的工作频率和灵敏度对AE检测的结果具有决定性的作用,传感器的校准是AE定量研究的基础,也是声发射检测技术研究中的重要课题。根据二级校准的相关要求设计了三个不同声源的实验:落球、断铅和压断毛细玻璃管法。通过重复性实验,测量了不同大小的钢球从不同高度下落;不同粗细、硬度以及不同长度的铅芯的断裂;不同粗细的毛细玻璃管被压断产生的脉冲声源,分别比较以上三个实验在不同状态条件下产生的脉冲声源信号,分析其实时特征和频谱特征(峰值,上升时间),通过计算确定其不确定度和稳定度,总结优化操作方法,同时分析了实验误差。在此基础上得出最适合做声发射传感器灵敏度校准的脉冲声源,为声发射传感器校准中的参考声源提供性能评判的依据。     

Computer-aided modeling of the protective effect of explosion relief vents in tunnel structures

This paper aims at contributing to the efficient design of explosion protection systems against confined explosions. The issue addressed concerns the quantitative estimation of the protective effect of explosion relief vents in the case of confined explosions inside tunnels. A series of virtual experiments performed by computer simulation, revealed how the number of vents, their diameter, as well as the angle between the vents and the tunnel, influences the blast wave attenuation. The computational study was performed considering a complicated large-scale tunnel configuration with branches on its half portion. The purpose was the calculation of the attenuation effect due to the presence of vents by comparing the total explosion-specific impulse developing at antidiametric positions inside the tunnel. Simulations were carried out via a three-dimensional numerical model built in the computational fluid dynamics code CFX 5.7.1, which has been validated in previous papers against experimental overpressure histories data demonstrating reasonable performance. Computer results showed that the use of branch vents provides an effective method for shock wave attenuation following an explosion, whereas their statistical elaboration revealed that the attenuation is mainly affected by the number of vents and their diameter. In contrast, the angle between the side vents and the main tunnel appeared to slightly affect the pressure wave weakening. Eventually, the quantitative influence of the above parameters was effectively illustrated in functional diagrams, so that the total attenuation effect may be promptly estimated, if the design variables are known. In addition, two statistical models with reasonable fitting to the calculated data are proposed, which express the attenuation effect as a dependent variable of the design variables including their interactions.     

长管拖车气瓶声发射技术定位检测方法分析

长管拖车气瓶是盛装有危险介质的高压储运设备,能否进行及时有效的检验,是保障其安全可靠运行的关键。我国开始长管拖车气瓶的应用、研究时间不长,相关积累不充分,而现有的水压试验法对危险性缺陷不敏感。声发射检测是动态缺陷整体检测的有效方法,将其应用于长管拖车气瓶的检测可节省大量的时间和人力、物力。对框架式长管拖车气瓶进行了不拆车声发射定位试验,测定了瓶体上断铅源声发射信号随距离衰减的曲线,采用数值分析方法得到曲线拟合方程式,探讨总结出定位过程中声发射采集的关键参数——门槛、探头间距和声速的设定方法和初始值,以及拖车结构对定位的影响,为长管拖车气瓶声发射定期检验工作的开展提供了参考,在分析定位源强度、定位方法研究方面有重要意义。