Railroad transportation of dangerous goods: Population exposure to airborne toxins

Hazardous materials are potentially harmful to people and environment due to their toxic ingredients. Although a significant portion of dangerous goods transportation is via railroads, prevailing studies on dangerous goods transport focus on highway shipments. We present an analytical framework that incorporates the differentiating features of trains, notably volume and nature of cargo, in the assessment of transport risk. We focus on hazardous materials that are airborne upon an accidental release into the environment. Each railcar is a potential source of release, and hence risk assessment of trains requires representation of multiple release sources in the model. We propose a risk approximation approach, which is not only effective but also robust with regards to the positioning of hazardous cargo in the train. We report on the use of the proposed approach for the assessment of population exposure associated with “Ultra-train” that passes through the city of Montreal everyday.     

铁水轨道衡在高炉的实践与应用

着重介绍了无基坑与有基坑2种轨道衡在高炉上的应用特点,阐述了高炉出铁场特殊环境对轨道衡的影响,以及在采购、安装和维护过程中的注意事项。     

Vibration of portable orbital sanders and its impact on the development of work-related musculoskeletal disorders in the furniture industry

The wood furniture industry has a strong presence in Canada, where it employs over 100,000 workers. Because of the extensive number of manual tasks required in this industry, several studies have been undertaken to characterize the health and safety risk factors to which these workers are exposed, such as awkward postures, repetitive movements and the application of undue force. However, very little research has been done on workers’ exposure to vibration from portable orbital sanders, one of the most common tools used in this industry. Vibration is responsible for a specific occupational disease called vibration syndrome, but is also recognized as a risk factor that increases the prevalence of more common work-related musculoskeletal disorders (WMSDs). This study proposed to determine the level of vibration to which sanders of furniture parts are exposed, and to analyze its impact on the risk of WMSDs. The results show that the level of vibration to which the workers are exposed is well above acceptable levels defined by recognized standards and directives and that this vibration is combined with many other risk factors, thus representing a risk for the development of WMSDs.     

Multi-route railroad blocking problem by improved model and ant colony algorithm in real world

In rail freight transportation, general merchandise freight cars may pass through many classification stations on their route from origin to destination. The Railroad Blocking Problem (RBP) is to reclassify inbound traffic from various origins in the classification stations and put them on outbound trains with the same or close destinations, the objective of the RBP is to minimize the total operating costs of delivering all traffic on the railway network while satisfying the resource and capacity constraints at the stations and the priority constraints for shipments. In this paper, we introduce a new mathematic model which can comprehensively describe the blocking strategy and various combinations of multi-route O–D pairs in large scale railway network. Furthermore, we propose an improved Ant Colony (AC) algorithm for RPB, and a computational experiment derived from the real life instances of coal heavy haul rail network in north China is given. Experimental results verified the validation of the model and effectiveness of the algorithm.     

Partitioning of chemicals—important factors in exposure assessment of offshore discharges

The CHARM (chemical hazard assessment and risk management) model was developed to give operators, chemical suppliers, and environmental authorities a scientific framework for analyzing the environmental hazard and risk of offshore chemicals used and discharged to the marine environment. This paper presents results from an R and D project carried out on partitioning of typical offshore chemicals where the objective was to validate the partitioning algorithms in CHARM. The work included further development and verification of the HPLC (OECD 117) method for determining oil/water partitioning, or fraction released of production chemicals, for evaluation of the applicability of the Shake Flask method (OECD 107) and modification of the sediment/water partitioning test methods, as well as establishment of a calculation method for determining the weighted average log P_ow for chemical mixtures of homologs. The calculation method was recommended adopted in CHARM. Based on the experimental partitioning results, the CHARM partitioning algorithms were evaluated. The test results showed that the HPLC technique is a “robust” method for determining the P_ow, but has limitations for surfactants and chemicals with high log P_ow-values, which are typical offshore chemicals. The traditional correlations reported between P_ow, the BCF, the fraction of a chemical released with produced water, and the P_sw is not valid for typical surfactants. Another approach is therefore used in CHARM, which also was evaluated in this project. There is, however, a need for further validation of the CHARM partitioning algorithms.     

Work/rest cycles in railroad operations: effects of shorter than 24-h shift work schedules and on-call schedules on sleep

The current study examined the frequency with which shorter than 24-h work/rest cycles occur in locomotive engineer work schedules, and what effects these work/rest cycles had on sleep quantity and sleep quality. The results indicated that shorter than 24-h work/rest cycles occurred in 33.6% of the work days reported by 198 locomotive engineers. In addition, the shorter than 24-h work/rest cycles occurred more frequently in work schedules that created an on-call work system, such as road pool turn and extra board assignments, than in work schedules that used more predictable or regular work times, such as regular road assignments and yard/local work. As would be expected, when engineers worked shorter than 24-h work/rest cycles, they reported less sleep and poorer sleep than under the longer than 24-h work/rest cycles. Similarly, on-call work assignments resulted in less sleep and poorer sleep than regular work assignments. These results indicate that specific aspects of the work schedules used in railroad operations, particularly on-call operations that result in shorter than 24-h work/rest cycles, can lead to increased sleep-related problems. Although the North American railroad industry is making significant changes in on-call operations to minimize sleep-related problems from on-call schedules, better fatigue-related models validated within the railroad industry are needed.     

The influence of shock-type vibrations on the absorption of mechanical energy in the hand and arm

In recent years there has been a discussion as to whether shock-type vibration from hand tools has stronger effects on the hand-arm system in comparison with non-impulsive vibration. The purpose of the investigation is to compare the influence of these two types of vibration on the absorption of mechanical energy in the human hand and on the grip and feed forces applied by the subjects.

The energy absorption has been measured by use of a specially designed laboratory handle. The grip and feed forces applied by the subject to the handle were measured simultaneously. In the study two different frequency weighted acceleration levels were used.

The outcome showed that the vibration exposure levels made a significant contribution to the vibration absorption as well as to the strength of the grip and feed forces. Moreover, it was found that the hand forces decrease while the absorption of energy increases during the experiment. Furthermore, the influence of shock-type exposure gave a significantly higher hand forces and absorption of energy compared with the non-impulsive exposure. It was, therefore, concluded that the vibration response characteristics of the hand and arm differ, depending upon whether the exposure is of shock or non-impulsive type.

Relevance to industry

The paper discusses the dynamic response of the hand and arm during exposure to shock and non-impulsive vibration. Whenever possible, a tool that requires low grip and feed forces should be used as well as tools that not generate shock-type excitation. This can be helpful in choosing the proper tool for the job.     

Numerical investigation of micro shock waves generation

The shock wave propagation in the micro channel of the different sizes is studied numerically in order to estimate the possibility of the experimental apparatus development. The full compressible Navier–Stokes equations are used for the numerical simulation. The shock wave velocity attenuation is found for the channel height smaller than H = 200 μm. The influence of the channel size and of the diaphragm pressure ratio on the shock wave velocity is considered. The considerable influence of the viscous effects on the shock propagation is shown.

加权滤波在电梯振动测量中的应用研究

电梯运行振动可以反映电梯整体性能状况。介绍一种加权滤波测量方法，根据人体对不同频率振动的敏感程度，对电梯运行振动数据采用加权滤波方法衡量。该方法在广州东部地区乘客电梯实际测量中得到验证，取得良好效果。     

Study of simultaneous shock and vibration control by a fore-and-aft suspension system of a driver’s seat

A single degree-of-freedom simulation model of a seat equipped with a non-linear fore-and-aft suspension system was developed. The performance of a typical fore-and-aft suspension system was analysed using typical vibration and shock acceleration signals measured in loaders while travelling on off-road terrain and while driving the bucket into a heap of soil. Damper modification was suggested to improve the suspension performance in the control of both vibration and shocks. Suspension system performance was analysed using the simulation approach for variations in both mass loading and excitation intensity. A discussion of results obtained and practical suggestions for improvement of the fore-and-aft driver’s seat suspension system concludes this contribution.

Relevance to industry

The simulations are of use to seat manufacturers in developing improved fore-and-aft seat suspension for wheel loaders. It is shown that a damper with an optimised progressive damping characteristic provides better shock mitigation than is available with either a seat without any suspension or a suspended commercial seat as presently available on the market.     

SPVT系统的框架结构研究

目前,由物理模型、数值方法和可视化技术相结合而发展起来的仿真技术,受到广泛的重视,正在迅速发展.在振动工程界,利用计算机技术将振动试验与计算机仿真技术集成在一起也是一个追求的目标.虚拟振动仿真系统SPVT（Simulation Platform of Vibration Test）,是在对振动环境试验和振动环境试验的数值仿真分析的研究基础上,研制的具备试验项目管理、数据信息处理、试验控制、振动分析、夹具设计、模型修正、试验再现等多种功能的集成化系统.该系统基于分布式异构网络,以项目管理为核心,实现仿真自动化,为振动环境试验的发展探索出一种试验与计算机仿真相结合、相互促进的新途径.该文介绍了系统的框架结构和实现该结构的关键技术.     

皮带秤称重传感器振动能吸收装置的研究与开发

为有效降低和消除振动,研发了皮带秤称重传感器振动能吸收装置.对油缸活塞的结构和液压油路控制增加液体流动的行程进行了设计,通过液体流动阻尼将振动能转换为热能,以此吸收振动能达到减振的目的.该装置采用了能量吸收器的振动能转换与吸收技术,具有运行同步、减振及时的优点.     

Vibration and noise characteristics of flap type olive harvesters

The object of this study was to measure and evaluate the vibration and noise characteristics of five flap type portable harvesters using for olive harvesting and their effect on operator health during harvesting time.The vibration and sound pressure levels of different harvesters were measured at both idling and full load conditions. The vibration values of harvesters were measured and analyzed for both right and left hands and the sound pressure level was measured at ear level of the operator. The vibration total value was expressed as the root-mean-squares (rms) of three component values. The results indicated that in 10% of the exposed population traumatic vasospastic disease (TVD) appeared after 0.7–7.1 years for the left hand, 1.0–4.7 years for the right hand of the operator in continuous use of these harvesters, under usual working conditions.The sound pressure values at operator’s ear level of harvesters were found below risk levels when compared with ILO standards.     

Vibration and spinal lengthening in simulated vehicle driving

There is active interest in the relationship between back pain and driving. The availability of a precision stadiometer enabled experiments to be done to explore the effects of simulated driving on the change in spinal length, the hypothesis being that the spinal load would cause a shrinking in the length of the spine. The experiments demonstrated that, when exposed to a combination of vertical and horizontal vibration at 4 Hz the spinal length increased for all eight subjects, whilst under no vibration conditions there was a decrease in the average length. At 6 and 8 Hz there was no statistically significant change in length. The results suggest that there is an unloading of the spine when subjects under simulated driving conditions are exposed to vibrations in two directions at a frequency close to the spine's natural frequency.     

鞭炮捆筒机热冲击振动消除方法研究与仿真

鞭炮捆筒机在工作过程中,电机到主轴采用皮带传动.火药靠皮带的两侧面与轮槽侧面压紧产生摩擦力进行动力传递的,在摩擦热载荷作用下会诱发机器结构的振动.传统的PID振动控制方法需要大幅调整参数,去满足热载荷作用下的振动控制要求,容易引发参数过量失调,振动控制效果不佳.提出基于模糊自适应PID控制算法的鞭炮捆筒机热冲击振动消除方法.计算V带基准长度,通过运算获取实际中心距离,研究了鞭炮捆筒机带轮振动关系.计算热冲击振动信号与控制参数之间的关联性,并对热冲击振动信号进行离散化处理,对离散化处理结果进行误差补偿,实现热冲击振动消除.实验结果表明,利用改进算法进行鞭炮捆筒机热冲击振动消除,能够有效提高消除的准确性,提高鞭炮捆筒机的应用价值.     

Development and application of a geospatial wildfire exposure and risk calculation tool

Applying wildfire risk assessment models can inform investments in loss mitigation and landscape restoration, and can be used to monitor spatiotemporal trends in risk. Assessing wildfire risk entails the integration of fire modeling outputs, maps of highly valued resources and assets (HVRAs), characterization of fire effects, and articulation of relative importance across HVRAs. Quantifying and geo-processing wildfire risk can be a complex and time-intensive task, often requiring expertise in geospatial analysis. Researchers and land managers alike would benefit from a standardized and streamlined ability to estimate wildfire risk. In this paper we present the development and application of a geospatial wildfire risk calculation tool, FireNVC. We describe the major components of the tool and how they align with a geospatial wildfire risk assessment framework, detail a recent application of the tool to inform federal wildfire management and planning, and offer suggestions for future improvements and uses of the tool.     

振动仿真在断路器设计中的应用

为解决某型航空断路器的耐振问题,利用MSC Adams/Vibration仿真工具对其建模与仿真. 找出影响耐振性能的主要原因,从而提高产品质量.     

Predicting the health risks related to whole-body vibration and shock: a comparison of alternative assessment methods for high-acceleration events in vehicles

In this paper, alternative assessment methods for whole-body vibration and shocks are compared by means of 70 vibration samples measured from 13 work vehicles, deliberately selected to represent periods containing shocks. Five methodologies (ISO 2631-1:1997, BS 6841:1987, ISO 2631-5:2004, DIN SPEC 45697:2012 and one specified by Gunston [2011], ‘G-method’) were applied to the vibration samples. In order to compare different evaluation metrics, limiting exposures were determined by calculating times to reach the upper limit thresholds given in the methods. Over 10-fold shorter times to exposure thresholds were obtained for the tri-axial VDV (BS 6841) than for the dominant r.m.s. (ISO 2631-1) when exposures were of high magnitude or contained substantial shocks. Under these exposure conditions, the sixth power approaches (ISO 2631-5, DIN SPEC, G-method) are more stringent than a fourth power VDV method. The r.m.s. method may lead to misleading outcomes especially if a lengthy measurement includes a small number of severe impacts. In conclusion, methodologies produce different evaluations of the vibration severity depending on the exposure characteristics, and the correct method must be selected.