综掘工作面风幕控尘除尘系统数值模拟及试验研究

针对综掘工作面掘进过程中粉尘污染问题,设计了一种新型高效的风幕控尘除尘系统,利用风幕风速衰减试验分析了风幕风速与距出口距离衰减的关系,当风幕末端风速达到2 m/s以上就能够有效控制呼吸性粉尘逃逸,另外,利用数值模拟的方法,对风幕控尘除尘系统工作原理进行了模拟,当风幕初速度为15 m/s、除尘风筒负压为-250 Pa时,风流到达巷道壁时的风速均达到了3m/s以上,风幕控尘除尘系统起到了很好的控尘和除尘作用.并对压入式通风+湿式除尘机除尘的方式进行了数值模拟,压入式通风的风流大部分被除尘风筒吸入,掘进头和压入式风筒与除尘风筒重叠段形成了无风区,大部分粉尘颗粒和瓦斯不能够及时排出,给生产带来了极大的安全隐患.     

镗床除尘装置

无锡县电机厂用JO2-9#机座双头镗床加工100千瓦电机外壳内表面,飞散出大量铁屑粉尘。生产一个班以后,工人的皮肤、鼻孔以及机床上都沾满了铁粉,不仅有害工人健康,还会磨损设备。 为了解决粉尘危害,我们和该厂技术人员一起设计安装了一套扩散式旋风除尘装置,效果良好。除尘效率达95%左右,加工时粉尘不再在车间飞扬,操作地点空气中含尘浓度已下降到6毫克/米3,除尘后排气筒含尘浓度为24.5毫克/米3,低于国家排放标准。 除尘装置如图所示。镗床的两头卡盘和镗刀杆处,是切削时产生粉尘的关键部位,在这个部位安装两个弧形吸尘罩,罩口迎着粉尘产生…     

综掘面风幕集尘除尘系统的参数优化与数值模拟

针对目前井下综掘面粉尘治理难的问题,研制了一种新型风幕集尘除尘系统。其中风幕风机的风速、除尘风筒的结构尺寸及出口压力是影响整个系统集尘除尘效果的决定性因素。为使风幕集尘除尘系统的防治粉尘效果达到最优,通过计算流体力学FLUENT软件,分析风幕风机风速、除尘风筒直径及出口压力改变的条件下风机的表面空气流线以及粉尘颗粒轨迹。得到风机风速、除尘风筒的直径及出口压力对整个系统集尘除尘效果影响的规律。结果表明:单方面增加风幕风机的风速或出口压力时,系统的集尘除尘效果在一定范围内可以变好,但是超过一定范围之后,风速的增加或者出口压力的增大反而使系统集尘除尘效果变差;在其他条件不变的情况下,除尘风筒直径越大系统集尘除尘效果越好。     

综掘面尘源位置对负压抽风口位置的影响

为探究综掘机配套抽风口位置对巷道除尘效果的影响,利用FLUENT软件建立综掘巷道相似几何模型,开展粉尘从不同尘源位置释放时,压入式通风系统和综掘机配套抽尘系统的流场及粉尘场模拟研究。结果表明:综掘工作面压入式通风系统的粉尘扩散范围在距工作面1～2 m处;综掘机配套抽尘口位置在距工作面1 m时的风流特征最利于除尘且此时各个尘源位置巷道内的粉尘均得到明显改善;当采用综掘机配套抽尘技术后,综掘工作面各个尘源释放粉尘时,巷道内的总体粉尘质量浓度都得到降低,平均除尘效率在80%以上,最高可达93%,可以很好地满足煤矿井下的降尘要求。     

敞开式TBM施工隧道粉尘扩散及除尘系统研究

TBM掘进过程中产生大量粉尘，为了掌握粉尘的分布规律并优化除尘系统，以敞开式TBM为例，采用数值计算方法研究不同除尘风管位置，不同除尘风速和不同掘进面产尘量下的洞内粉尘浓度分布规律。研究结果表明:敞开式TBM隧道施工过程中，掘进面至除尘风管区域质量粉尘浓度较高，在除尘风管口后方区域下降到 2 mg/m3以下；除尘风管布置在距掘进面30 m位置处时，洞内沿程粉尘含量相对较大，除尘风管布置在距掘进面20 m位置处时洞内沿程及TBM支护区域粉尘含量相对较小；排风风速为15 m/s时，敞开式TBM支护区域粉尘质量浓度最小，排风风速为30 m/s时，该区域粉尘质量浓度最大；掘进面产尘量越大，洞内沿程及敞开式TBM支护区域粉尘质量浓度越大，不同产尘量下洞内粉尘浓度均在除尘风管后方达到规范限值以下。     

公共汽车的抛光除尘系统

目前,在公共汽车修理行业,为节约资金,汽车内外铝线条与车头上的铝框架,大多采用抛光后再重复使用的办法。由于吸尘装置受抛光件几何形状的限制,吸尘效果很差,粉尘对操作工人健康危害极大。另外,排出的尘味也使附近居氏难以忍受,向有关部门提出了申诉。 怎样才能做到既要吸尘又要除掉难闻的尘味呢?笔者对此进行了可行性论证,并进行了安装、使用。经半年实践,效果甚好。得到了操作工人的肯定。粉尘浓度已由原来的300毫克/米3以上,下降到2。7毫克/米3,低于国家标准4毫克/米’。 该抛光除尘系统从生产实际出发,主要应该解决三个技术问题:一是各…     

电石破碎湿法除尘

我厂电石破碎采用旋风除尘器和水浴除尘器二级除尘,效果很好,具有结构简单、投资少、检修量小、除尘效率高、安全可靠等优点。 除尘系统 在颚式破碎机进料口、提升机下部和小料仓下料口设吸尘罩,含尘空气经扩散式旋风除尘器进入风机,风机出口接水浴除尘器,经两级净化,然后排入大气。除尘系统见示意图。 设计与选型设:吸入粉尘浓度为5,000毫克/ 米3,工作截面周长为5米。工作面离吸风口距离为0.35米。 排尘浓度标准为150毫克/米3。选用二级除尘: ①一级用:扩散式旋风除尘器,除尘效率85%,进口风速18米/秒。 二级用:水浴除尘器,除尘效率85%,进口…     

茶厂自动车色机除尘

我厂在茶叶生产时,经常为茶尘及附着的泥土杂物粉尘严重污染车间环境而苦恼。为了保护作业工人的身体健康,我们设计安装了自动车色机机械除尘装置。该装置已使用投产。经有关部门测定,效果良好。见表1、表2。 1.多分枝管网的布置 自动车色机共有24对,48只滚筒。本着节省投资与能源的原则,分设两个除尘系统。每一系统内有24只滚筒。滚筒在运转中有两处产尘点,因操作需要不能采用整体密闭罩。所以在每只滚筒中只设一吸尘点,另一产尘点则采取密闭形式。由于每个系统的抽风点多,我们采取两条措施来实现节点压力平衡。一是因上下重迭的两只滚筒的…     

高冲程压砖机除尘系统的改进

包钢耐火厂矽砖车间共有五台摩擦压砖机,其中有一台260吨高冲程压砖机。过去这五台摩擦压砖机都装有除尘系统。吸尘咀安装在滑块上,用蛇形管和上部管道连接,随着滑块的升降而吸尘,除尘效果较好。但是,由于260吨高冲程压砖机行程高,装料时粉尘浓度大,而吸尘咀却升到行程的最高度,离产尘点距离远,吸力不够,效果不理想。而且对生产操作有一定妨碍。     

综掘面旋流风幕抽吸控尘流场数值模拟

针对目前井下巷道内综掘工作面产尘量大,煤尘浓度高,降尘效率低的实际现状,探讨了配有附壁风筒的综掘工作面旋流风幕抽吸控尘的新型降尘方式,建立气体-粉尘颗粒两相流动的数学模型,利用Fluent对巷道流场进行数值模拟,并分析了风流扩散规律、粉尘分布规律以及影响粉尘分布规律的因素.模拟结果显示,综掘面旋流风幕抽吸控尘系统可在机掘工作面的有限空间内形成一个具有屏蔽作用的旋转风幕,将粉尘基本封闭在距掘进面0～3m的范围内.抽风口距离掘进面越近,高浓度粉尘存在范围和巷道中的粉尘浓度越小;增加抽风口个数可以提高除尘效率.     

深基坑边坡锚土墙支护设计与施工

简述了航华科贸中心０—２，３楼基坑边坡锚土墙支护设计与施工情况；针对不同边坡进行了局部加固设计；对施工工艺作了较为全面的介绍；分析了边坡稳定的有害因素并提出了相应的处理措施；介绍了边坡位移的控制方法，分析了作为工程验收主要指标之一的锚钉拉拔试验。     

Comparing the usability and reliability of a generic and a domain-specific medical error taxonomy

Medical error taxonomies are used to report and analyse patient safety incidents. Medical error taxonomies can be generic or domain-specific. In comparing generic and domain-specific medical error taxonomies, the literature compares the information both type of taxonomies classify. There is little evidence the taxonomies have been compared in terms of usability and reliability. Twenty nurses and 21 pharmacists participated in a study comparing the usability and reliability of a generic medical error taxonomy and a medication error taxonomy. The medical error taxonomies utilized were the Patient Safety Event Taxonomy and the NCC MERP Taxonomy of Medication Error. The study found no significant difference in the usability ratings of both taxonomies. The taxonomies required different amount of time to classify patient safety incidents and had significantly different reliability levels. The reliability of the NCC MERP Taxonomy of Medication Error was significantly different when used by nurses and pharmacists. The taxonomy was also preferred by the majority of participants. Some recommendations are made about the design of future medical error taxonomies.     

Between a rock and a hard place: Accident and near-miss reporting on offshore service vessels

Reporting accidents and near misses is an important aspect of safety management. This study explores reporting in contract work, exemplified by offshore service vessels, and the associations with external and internal organisational factors. The empirical foundation for the study is a questionnaire survey (N = 1108). Reporting was negatively related to high efficiency demands from external actors and low quality of feedback to the reporting community. These factors were more strongly related to reporting than internal factors within the safety climate construct. Short-term contract engagement was also negatively associated with reporting. The results could reflect the organisational complexity that characterises much contract work. The study implies that attempts to increase the level of reporting in contract work should not be limited to focusing on internal organisational factors. Framework conditions and signals from external actors regarding the actual priority accorded to safety should also be considered.     

Fatal crash between a car operating with automated control systems and a tractor-semitrailer truck

Abstract

Objective: The objective of this investigation was to evaluate the interaction between an SAE level 2 automated vehicle and the driver, including the limitations imposed by the vehicle on the driver.

Methods: A case study of the first fatal crash involving a vehicle operating with an automated control system was performed using scene evidence, vehicle damage, and recorded data available from the vehicle, and information from both drivers, including experience, phone records, computer systems, and medical information, was reviewed.

Results: System performance data downloaded from the car indicated that the driver was operating it using the Traffic-Aware Cruise Control and Autosteer lane-keeping systems, which are automated vehicle control systems within Tesla’s Autopilot suite. As the car crested the hill, a tractor trailer began its left turn onto a crossing roadway. Although reconstruction of the crash determined that there was sufficient sight distance for both drivers to see each other and take action, neither responded to the circumstances leading to the collision. Further, based on the speeds of the vehicles and simulations of the truck’s path, the car driver had at least 10.4?s to detect the truck and take evasive action. Neither the car driver nor the Autopilot system changed the vehicle’s velocity.

?At the time of the crash, the system performance data indicated that the last driver interaction with the system was 1?min 51?s prior when the cruise control speed was set to 74?mph. The driver was operating the vehicle using the Autopilot system for 37 of the 41?min in the last trip. During this period, the vehicle detected the driver’s hands on the steering wheel for a total of 25?s; each time his hands were detected on the wheel was preceded by a visual alert or auditory warning.

Conclusions: The National Transportation Safety Board (NTSB) determined that the probable cause of the Williston, Florida, crash was the truck driver’s failure to yield the right of way to the car, combined with the car driver’s inattention due to overreliance on vehicle automation, which resulted in the car driver’s lack of reaction to the presence of the truck. Contributing to the car driver’s overreliance on the vehicle automation was the car’s operational design, which permitted the driver’s prolonged disengagement from the driving task and his use of the automation in ways inconsistent with guidance and warnings from the manufacturer.     

Symptoms and musculoskeletal diseases in hospital nurses and in a group of university employees: a cross-sectional study

Background. Most studies have shown that nurses have a higher risk of developing musculoskeletal symptoms compared with other occupational groups. Aim. A cross-sectional study was performed to gain more insight into the prevalence rates of musculoskeletal disorders (MSDs) in nurses. Methods. The presence of musculoskeletal symptoms was revealed by personal interviews in a sample of 177 hospital nurses and in a reference group of 185 university employees. Musculoskeletal diseases were based on radiological examinations in all subjects. Results. Lower back pain (61% vs 42.2%) was the most frequently reported symptom, followed by neck pain (48.6% vs 38.4%) and shoulder pain (36.7% vs 25.9%), with a significantly higher prevalence in nurses. Women had about a 2-fold risk of upper limb region and neck pain compared with men. The most common abnormal findings on radiological examinations were disc herniations (n?=?40). Conclusions. Nurses showed a significantly higher risk of MSDs. Prevalence rates in nurses increased significantly with age. Musculoskeletal symptoms were also common in university employees. This suggests the need for effective intervention strategies involving workers’ active participation, in order to improve the process and organization of work and promote a positive psychosocial work environment.     

一种新型四齿1,2-HOPO螯合剂的合成、金属配位研究

以6-羟基-2-吡啶羧酸为原料,经5步反应合成得到一种新型四齿β-二酮1,2-羟基吡啶酮衍生物。通过红外、核磁、质谱对其结构进行了表征。采用电位-光谱结合的方法,测定了四齿β-二酮1,2-羟基吡啶酮衍生物与UO2+2、Cu~(2+)、Zn~(2+)和Fe~(3+)的络合能力。结果表明,四齿β-二酮1,2-羟基吡啶酮衍生物对UO2+2和Fe3+有明显的络合能力,有望成为一种新型铀酰离子促排剂(p UO2=15.4)和铁螯合剂(p Fe=21.22)。     

光电探测器微变信号放大电路的设计和分析

针对火灾探测过程中的光电探测器输出的微弱信号设计了一个微变信号提取放大电路。将探测器内阻分解为微变内阻和不变内阻,采用两路取样信号方法进行差模放大。经过计算选择了特定的电路参数,使得电路输出和探测器微变内阻成正比关系,从而实现了微变信号的放大。用斩波方法进行了电路输出性能的实验。对电路参数的选择以及温漂问题进行了详细分析。     

Development of a multilevel health and safety climate survey tool within a mining setting

IntroductionThis study aimed to design, implement and evaluate the reliability and validity of a multifactorial and multilevel health and safety climate survey (HSCS) tool with utility in the Australian mining setting.MethodsAn 84-item questionnaire was developed and pilot tested on a sample of 302 Australian miners across two open cut sites.ResultsA 67-item, 10 factor solution was obtained via exploratory factor analysis (EFA) representing prioritization and attitudes to health and safety across multiple domains and organizational levels. Each factor demonstrated a high level of internal reliability, and a series of ANOVAs determined a high level of consistency in responses across the workforce, and generally irrespective of age, experience or job category. Participants tended to hold favorable views of occupational health and safety (OH&S) climate at the management, supervisor, workgroup and individual level.ConclusionThe survey tool demonstrated reliability and validity for use within an open cut Australian mining setting and supports a multilevel, industry specific approach to OH&S climate. Findings suggested a need for mining companies to maintain high OH&S standards to minimize risks to employee health and safety. Future research is required to determine the ability of this measure to predict OH&S outcomes and its utility within other mine settings.Practical applicationsAs this tool integrates health and safety, it may have benefits for assessment, monitoring and evaluation in the industry, and improving the understanding of how health and safety climate interact at multiple levels to influence OH&S outcomes.     

Safety lessons and reflections following incinerator vent commissioning in a chemical plant; a case study of a complex socio-technical system

In a bulk chemical plant producing resins, a flashback from an incinerator through the vent system into the reactor hall occurred during commissioning of a newly installed vent header system. The original design of the vent header system was seriously flawed not being in line with current practice. Subsequently the vent header was re-designed into a rich/lean vent header system. This paper explores the reasons behind a number of incidents and near misses that occurred during both the commissioning of a vent header system and its recommissioning following system re-design. Furthermore, it reflects on some broader implications for approaches to safety around what can be recognised as complex socio-technical systems.     

火蔓延及发展过程的计算机模拟

本文对火蔓延及发展过程进行了计算机模拟,建立了描述火焰在不结焦可燃物垂直表面向上蔓延过程的数学物理模型,其中考虑了有关的四个分过程,即(1)可燃物未燃部分的预热;(2)火蔓延或热解区前沿的确定;(3)可燃物的热解以及(4)挥发份燃烧放热。在分别建立描述这些分过程模型的基础上,构成了体现几何尺寸和其它有关因素影响的总括模型,其结果与PMMA竖板上的实验结果进行了对比。