Impact of work boots and load carriage on the gait of oil rig workers

Effects of work boots and load carriage (6.4?kg and 12.8?kg) on gait pattern were investigated. The protective work boots were examined by comparison with running shoes through human performance tests with 15 male participants. The loads were carried symmetrically and asymmetrically on the shoulder and hand. Statistical data analysis showed a prolonged stance phase and decreased double support for work boots. A significantly increased ground reaction force was found in work boot conditions as the weight of loads increases. This study demonstrates that inflexible and heavy work boots restrict foot movement and require greater torque at the ankle to propel the body forward, which may increase physical strain and the risk of musculoskeletal injuries. Development of improved fixation methods for work boots, increased use of flexible protective layers and further study of anthropometry of human foot morphology for improved safety and work efficiency of industry workers are suggested.     

A Comparison of Two Methods of Determining Thermal Properties of Footwear

The present European Standard for footwear testing (Standard No. EN 344:1992; European Committee for Standardization [CEN], 1992) classifies footwear thermally by a temperature drop inside the footwear during 30 min at defined conditions. Today, other methods for footwear thermal testing are also available. The aim of this study was to compare EN 344:1992 with a thermal foot method. Six boots were tested according to both methods. Additional tests with modified standard tests were also carried out. The methods ranked the footwear in a similar way. However, the test according to standard EN 344:1992 is a pass-or-fail test, whereas data that is gained from the thermal foot method gives more information and allows further use in research and product development. A change of the present standard method is suggested.     

Effect of Sweating on Insulation of Footwear

The study aimed to find out the influence of sweating on footwear insulation with a thermal foot model. Simultaneously, the influence of applied weight (35 kg), sock, and steel toe cap were studied. Water to 3 sweat glands was supplied with a pump at the rate of 10 g/hr in total. Four models of boots with steel toe caps were tested. The same models were manufactured also without steel toe. Sweating reduced footwear insulation 19–25% (30–37% in toes). During static conditions, only a minimal amount of sweat evaporated from boots. Weight affected sole insulation: Reduction depended on compressibility of sole material. The influence of steel toe varied with insulation. The method of thermal foot model appears to be a practical tool for footwear evaluation.     

Underwater LNG release: Does a pool form on the water surface? What are the characteristics of the vapor released?

One of the scenarios of concern in assessing the safety issues related to transportation of LNG in a marine environment (ship or underwater pipeline) is the release of LNG underwater. This scenario has not been given the same level of scientific attention in the literature compared to surface releases and assessment of consequences therefrom. This paper addresses questions like, (1) does an LNG spill underwater form a pool on the water surface and subsequently evaporate like an LNG spill “on the surface” producing cold, heavier than air vapors?, and (2) what is the range of expected temperatures of the vapor, generated by LNG release due to heat transfer within the water column, when it emanates from the water surface?Very limited data from two field tests of LNG underwater release are reviewed. Also presented are the results from tests conducted in other related industries (metal casting, nuclear fission and fusion, chemical processing, and alternative fuel vehicles) where a hot (or cold) liquid is injected into a bulk cold (or hot) liquid at different depths.A mathematical model is described which calculates the temperature of vapor emanating at the water surface, and the liquid fraction of released LNG that surfaces, if any, to form a pool on the water surface. The model includes such variables as the LNG release rate, diameter of the jet at release, depth of release and water body temperature. Results obtained from the model for postulated release conditions are presented. Comparison of predicted results with available LNG underwater release test data is also provided.     

Effects of load carriage and work boots on lower limb kinematics of industrial workers

Load and footwear condition are two crucial elements varying the kinematic responses during walking, which probably lead to chronic injury. Fifteen healthy male individuals with no obvious gait abnormalities participated in this study. Apart from a no-load condition, four external load conditions with two load levels were investigated. Work boots were compared with running shoes to determine footwear effects. Significant impacts were found for lower limb range of motion at certain joints when carrying loads. A greater hip and ankle flexion–extension while wearing the work boots indicated that participants needed to lift the leg higher to complete toe clearance off the walking surface. Work boots also increased the vertical excursion of the center of body mass, which may impact body balance and induce falling. No significant influencing pattern of carrying modes was found, which was probably due to the light load and relatively stable mode of shoulder carrying.     

Ageing management and monitoring of critical equipment at Seveso sites: An ontological approach

A safe “ageing” of Seveso establishments is a challenge for both operators and regulators. To this scope, Seveso III Directive required to integrate the equipment integrity issue into the safety management system for the major accident prevention; at the same time, the Italian Authority adopted a short-cut method for a quick ageing evaluation, which awards the application of the best techniques to control integrity and prevent deterioration-related failures. In this paper, the use of the ontology has been proposed to support decision-making about the implementation of technical solutions to control equipment ageing and comply the requirements of the Seveso legislation. To contrast deterioration mechanisms, the rapid development of data intensive smart sensors should be exploited and, in this frame, the automated on-line direct monitoring of equipment conditions, based on innovative low-cost sensors, is a novelty and promising solution. The developed ontology-based system points towards the adoption, when possible, of on-line monitoring. This solution provides much more data than traditional measurements and it is essential for the operators to understand how to merge concurrent information and data and to adequately control equipment deterioration. The ontology-based approach appears a viable solution even for this purpose. To demonstrate its potentiality, a real use-case has been used, where the model has been tested in finding the best technical solutions to improve the ageing management of an atmospheric distillation unit of a refinery in order to comply with safety requirements. A further use-case is given to show how the model can be used to react, after real-time damage signals, to restore safety conditions by means of an adequate decision-making.     

Influence of thermal shock of piezoelectric pressure sensors on the measurement of explosion pressures

Piezoelectric pressure sensors are susceptible to changing temperatures, because resulting mechanical deformations of the sensor membrane and housing may exert a positive or negative force on the piezo crystal, thus changing the reading of this sensor. The consideration and compensation of this influence quantity is a frequent topic of many investigations in the field of combustion chambers, of spark-ignition engines and internal combustion engines. However, this is not the case in the field of the type of protection “flameproof enclosures”. Here a peculiarity is the fast temperature rise during a single explosion and the concurrent influence of the temperature gradient, which is often described as thermal shock. The whole event has a typical duration time of the order of seconds and less. Thermal shocks have so far received little attention, as was also a lesson learnt from the evaluation of an interlaboratory comparison between Ex testing laboratories. The laboratories handle thermal shock in a variety of ways, starting from complete ignorance up to various sophisticated coatings. This was a main source of different results within the field of participants. This work evaluates the behavior of different piezoelectric pressure sensor types with respect to thermal shock. Different temperature protection measures are investigated regarding their functionality, practicability and stability. Possible influences on the sensitivity of the sensors due to the used protective measures regarding thermal shock are shown. The transient temperature load of the sensor membrane is estimated by physical calculations as well as numerical analysis based on surface temperature measurements transformed in a surface heat flux density. This work provides guidelines for typical end-users in the field of flameproof enclosures how to handle thermal shock correctly.     

Locating the gas leakage source in the atmosphere using the dispersion wave method

A new and simple method for locating emission source was proposed in this work based on gas dynamic dispersion information. The simulation of the unsteady state dispersion of leakage gas emission from the geosequestration project showed that the transportation process of emission gases in the atmosphere is similar to wave propagation, and the time parameter of the dispersion wave is linearly related to the downwind distance. Therefore, monitoring the dispersion wave at different downwind positions can be used to estimate the leakage source position. An estimation formula for locating emission sources was derived. First, an estimation formula for locating emission sources was derived under some initial assumptions. Then, the deviation of the location formula was investigated using a computational fluid dynamics (CFD) model and analytic solution to get the offset distance under different conditions. The results showed that the average distance is stable for a certain atmosphere and terrestrial conditions. This method needs no more than 3 sensors’ dynamic information to locate the emission source, and hence it is highly useful for conditions with limited sensors. A numerical test demonstrated that the absolute error of the source estimation is within the range of 1–30 m. Finally, experimental tests were conducted to verify the feasibility of the source location with dispersion waves. Therefore, the dispersion wave monitor is a potentially simple and feasible way to estimate the source location for gas emission event management with limited sensors in the process industries.     

Safety assessment of potential supercritical solvents for Fischer–Tropsch Synthesis

Fischer–Tropsch Synthesis (FTS) is a primary pathway for gas-to-liquid (GTL) technology. In order to overcome commercial problems associated with reaction and transport phenomena, the use of supercritical solvents has been proposed to enhance conversion, catalyst stability and improve temperature control in fixed-bed reactors. One of the major challenges in designing the supercritical FTS reactor unit is selecting appropriate solvents of critical properties within the required reaction operating conditions. Numerous alternatives exist and should be screened based on relevant criteria. The main aim of this paper is to develop a screening methodology to identify an optimum supercritical solvent or a mixture of solvents that meet the aforementioned criteria while minimizing the cost and more importantly satisfying the safety constraints. A safety metric system was developed in order to compare the risk issues associated with using different solvents. In addition, an economic analysis of using the different solvents was performed. Finally, a case study was solved to illustrate the use of the proposed metrics and the selection of solvents based on safety and techno-economic criteria.     

海洋平台振动监测技术试验研究

为保证海洋平台服役期间安全运行,以实验室海洋平台模型为研究对象,开展有关振动监测技术的试验研究。通过预制损伤等物理手段,模拟海洋平台模型完好与损伤状态。使用加载设备对平台模型加载,采集其在不同加载角度、频率与增益下的动力响应。对振动传感器校准后,利用传感器、信号调理仪以及信号采集软硬件设备,组成监测系统。分析试验数据,调整相关试验参数,选取最佳信号采集状态。选取双谱分析法对试验数据进行信号处理,得出平台模型完好与损伤状态的数据变化。结果表明:根据振动监测数据的双谱模量与频率分布,能够识别损伤。     

Safety evaluation of joint and conventional lane merge configurations for freeway work zones

Inefficient operation of traffic in work zone areas not only leads to an increase in travel time delays, queue length, and fuel consumption but also increases the number of forced merges and roadway accidents. This study evaluated the safety performance of work zones with a conventional lane merge (CLM) configuration in Louisiana. Analysis of variance (ANOVA) was used to compare the crash rates for accidents involving fatalities, injuries, and property damage only (PDO) in each of the following 4 areas: (1) advance warning area, (2) transition area, (3) work area, and (4) termination area. The analysis showed that the advance warning area had higher fatality, injury, and PDO crash rates when compared to the transition area, work area, and termination area. This finding confirmed the need to make improvements in the advance warning area where merging maneuvers take place. Therefore, a new lane merge configuration, called joint lane merge (JLM), was proposed and its safety performance was examined and compared to the conventional lane merge configuration using a microscopic simulation model (VISSIM), which was calibrated with real-world data from an existing work zone on I-55 and used to simulate a total of 25 different scenarios with different levels of demand and traffic composition. Safety performance was evaluated using 2 surrogate measures: uncomfortable decelerations and speed variance. Statistical analysis was conducted to determine whether the differences in safety performance between both configurations were significant. The safety analysis indicated that JLM outperformed CLM in most cases with low to moderate flow rates and that the percentage of trucks did not have a significant impact on the safety performance of either configuration. Though the safety analysis did not clearly indicate which lane merge configuration is safer for the overall work zone area, it was able to identify the possibly associated safety changes within the work zone area under different traffic conditions.     

矿井热宽温度环境人体热健康分区热调节模型*

为评价矿井热环境中工人职业健康安全状况,提出矿井热宽温度环境人体热健康状态的基本特征与生理要求,分析热宽温度环境人体分区热调节规律与热健康状态的对应关系。基于生物控制论的观点,提出热宽温度范围内不同热应力作用下人体分区热调节机制,建立人体分区热调节模型。结果表明:模型能实现对环境热应力作用下人体物理热平衡状态与生理状态的参数化描述,揭示多因素作用下人体热健康状态的热应力边界与变化规律。分区热调节模型提供了人体热健康状态定量模拟平台,通过参数调整可使模型适应研究需求,模型为井下热环境工人职业健康安全状况分析与评价提供了可参考的思路与方法。     

基于改进的YOLOv4安全帽佩戴检测研究

为了加强建筑工人佩戴安全帽情况的检测,防止安全事故的发生,提出1种改进的轻量级YOLOv4安全帽佩戴检测算法,用于运行在移动设备端,降低现场部署的条件;制作1个8 000幅图像的数据集,用于训练和评估安全帽检测算法;为了评估改进的YOLOv4的性能,从5个不同建筑工地采集到600张施工人员图像和60条施工视频作为验证集;根据建筑工地不同的视觉条件对图像进行分类,用于验证本文算法在不同外界环境下的性能。结果表明:改进后的模型检测速度是YOLOv4的3.4倍,可用于实时检测施工人员在不同施工现场条件下是否佩戴安全帽的情况,有利于提高安全检查和监督水平。     

基于微型惯性传感器的井下人员跟踪定位系统*

为了解决当前煤矿井下使用的WIFI人员定位系统在煤矿井下复杂环境中受到干扰,造成使用精度误差等问题,研究并提出使用微型惯性传感器制作足部轨迹测量传感器,通过惯性轨迹测量算法计算并跟踪井下人员的移动轨迹。使用基于固定阈值的零速检测技术和基于Kalman滤波的零速校正技术估计并校正由于系统长期工作造成的偏移误差。通过实验证明采用微型惯性传感器能够在不依赖于外部传感器的情况下对人员轨迹实现测量跟踪,Kalman滤波的应用能够减少惯性轨迹测量系统造成的长期漂移误差,可避免井下复杂工作环境对定位造成的干扰。     

Approach enhancing inherent safety application in onshore LNG plant design

This study aims to provide the approach for inherent safety design of onshore LNG plants to be applied at the very early stages (concept definition phase) of the project development. Onshore LNG plant development project starts from the “Concept Definition” phase, where financial feasibility is estimated and major conditions, such as site location and plant foot print, are set.The inherent safety design basic criteria and design measures should be identified and selected when setting the basic conditions during the Concept Definition phase of the project development, such as the site location (relative location from populated areas), site condition (prevailing wind direction) and plant production capacity (number of process train, number of product tanks). The safety measures, which are usually not fully developed at the project early stages in the current design execution practices, are the emergency systems, which mitigate an accident escalation, the modularized plant and layout, and the tank selection.The inherent safety design measures discusses in this paper were identified based on the categories of plot plan, emergency system, and module plant application.The proposed approach will contribute to improve inherent safety design of onshore LNG plants and it will also yield schedule and cost benefits.     

库房火灾事故中弹药热安全性研究*

为研究不同火灾条件下弹药发生慢速烤燃的升温速率,以典型地面仓库和舰船舱室火灾为研究对象,建立仿真模型,模拟计算发生火灾时弹药贮存环境的热激源强度及其演化规律,针对发动机在此类环境下的热安全性开展仿真计算,分析其响应规律。研究结果表明:不同火灾条件下弹药慢速烤燃的升温速率有很大区别且往往高于标准慢速烤燃试验常用的升温速率3.3 K/h。随着慢速烤燃升温速率的提高,发动机烤燃点火时间提前,点火时刻发动机中间位置温度下降,两端温度升高,且点火位置向发动机喉部移动。研究结果可以指导弹药库房的设计及弹药安全性增强设计。     

Transferability of accident prediction models

Accident prediction models, the vast majority of which are negative binomial regression models, are of considerable importance to highway agencies since they can be used to conduct many traffic safety studies. However, not every agency possesses sufficient accident statistics that enable it to develop reliable models of its own. This problem gives rise to interest in the transferability of accident prediction models in time and space. It would save time, effort, and money if accident prediction models developed for one region in one period of time could be applied in different time periods and regions to produce reliable safety studies.This paper presents methods for recalibrating negative binomial accident models before transferring them for use in different time periods and regions of space. The paper emphasizes that the recalibration of the shape parameter of a transferred model using local data is absolutely necessary. It explains that it is also desirable to recalibrate the constant term of the transferred model in order to allow the model to better suit local conditions. A moment method is presented for recalibrating the shape parameter of a transferred model when its constant term is not recalibrated. However, a maximum likelihood method is presented for recalibrating both the shape parameter and the constant term of the transferred model and is shown to be superior to the recalibration methods existing in the traffic safety literature.     

Fault detection approach for systems involving soft sensors

This paper develops a new approach for fault detection which involves soft sensors for process monitoring. Unlike existing approaches, which compare current measurements, or linear combinations thereof, to values of these measurements representing normal operations, the methodology presented here deals directly with the state estimates that need to be monitored. The advantage of such an approach is that the effect of abnormal process conditions on the state variables can be directly observed and that it is possible to include nonlinear relationships between measurements and states. At the same time, this type of approach has the drawback that the variances of the unmeasured states are not equal to the variances of the actual process variables due to the use of a soft sensor. However, for many popular soft sensor techniques, such as Kalman filters and related approaches, it is possible to compute variances of the predicted states that correspond to normal operating conditions. This paper presents a general framework for using soft sensors for process monitoring, i.e., soft sensor design and computation of the statistics that represent normal operating conditions, and illustrates this framework in three specific applications. It should be pointed out that the contribution of this work does not lie with the soft sensor design or the computation of the statistics itself as either part has individually already been addressed in the existing literature. However, the authors are not aware of any studies where both tasks are combined for process monitoring, which forms the contribution of this work.     

屏蔽服冷却系统对人体表面温度影响的研究*

为科学有效地论证多种方式组合的冷却屏蔽服在不同环境条件下对人体表面温度控制的效果,需要对冷却系统及人体敏感部位发热量进行客观评估。通过对5名健康男性的高温测试,探究人体在不同环境温度下体表温度的变化,得出胸部、背部及额头为热量最高部位,并构建以“人体-降温屏蔽服-外界环境”为主体的冷却系统数值模型,对不同环境中的屏蔽服冷却效果展开研究,分析穿戴冷却屏蔽服时人体躯干部分的温度分布及影响。结果表明:在屏蔽服中靠近胸部、背部部位引入相变材料和风扇,均可帮助人体降低体温,提高舒适度。