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181.
A central concern of Intelligent Transportation Systems (ITS) is the effect of in-vehicle devices (e.g., cell phones, navigation systems, radios, etc.) on driver performance and safety. As diverse and innovative technologies are designed and implemented for in-vehicle use, questions regarding the presence and use of these devices assume progressively greater importance. Further concerns for advanced driver training require us to develop and validate reliable and effective procedures for assessing such effects. This work examines a number of candidate procedures, in particular the evaluation of change in cognitive workload as a strategy by which such goals might be achieved.  相似文献   
182.
For wearers of protective clothing in radiation environments there are no quantitative guidelines available for the effect of a radiative heat load on heat exchange. Under the European Union funded project ThermProtect an analytical effort was defined to address the issue of radiative heat load while wearing protective clothing. As within the ThermProtect project much information has become available from thermal manikin experiments in thermal radiation environments, these sets of experimental data are used to verify the analytical approach. The analytical approach provided a good prediction of the heat loss in the manikin experiments, 95% of the variance was explained by the model. The model has not yet been validated at high radiative heat loads and neglects some physical properties of the radiation emissivity. Still, the analytical approach provides a pragmatic approach and may be useful for practical implementation in protective clothing standards for moderate thermal radiation environments.  相似文献   
183.
Quantifying the risk of accidental ignition of flammable mixtures is extremely important in industry and aviation safety. The concept of a minimum ignition energy (MIE), obtained using a capacitive spark discharge ignition source, has traditionally formed the basis for determining the hazard posed by fuels. While extensive tabulations of historical MIE data exist, there has been little work done on ignition of realistic industrial and aviation fuels, such as gasoline or kerosene. In the current work, spark ignition tests are performed in a gaseous kerosene–air mixture with a liquid fuel temperature of 60 °C and a fixed spark gap of 3.3 mm. The required ignition energy was examined, and a range of spark energies over which there is a probability of ignition is identified and compared with previous test results in Jet A (aviation kerosene). The kerosene results are also compared with ignition test results obtained in previous work for traditional hydrogen-based surrogate mixtures used in safety testing as well as two hexane–air mixtures. Additionally, the statistical nature of spark ignition is discussed.  相似文献   
184.
Concerns over public safety and security of a potential liquefied natural gas (LNG) spill have promoted the need for continued improvement of safety measures for LNG facilities. The mitigation techniques have been recognized as one of the areas that require further investigation to determine the public safety impact of an LNG spill. Forced mitigation of LNG vapors using a water curtain system has been proven to be effective in reducing the vapor concentration by enhancing the dispersion. Currently, no engineering criteria for designing an effective water curtain system are available, mainly due to a lack of understanding of the complex droplet–vapor interaction. This work applies computational fluid dynamics (CFD) modeling to evaluate various key design parameters involved in the LNG forced mitigation using an upwards-oriented full-cone water spray. An LNG forced dispersion model based on a Eulerian–Lagrangian approach was applied to solve the physical interactions of the droplet–vapor system by taking into account the various effects of the droplets (discrete phase) on the air–vapor mixture (continuous phase). The effects of different droplet sizes, droplet temperatures, air entrainment rates, and installation configurations of water spray applications on LNG vapor behavior are investigated. Finally, the potential of applying CFD modeling in providing guidance for setting up the design criteria for an effective forced mitigation system as an integrated safety element for LNG facilities is discussed.  相似文献   
185.
Major Accident Hazard (MAH) and Occupational Safety and Health (OSH) are two separated topics in both industrial practice and legislation; recently, interest is increasing toward an integrated risk assessment mainly forced by the tendency to a more efficient safety management system. The present study proposes a semi-quantitative approach to integrate MAH in OSH risk assessment. The two risk types are characterized by opposite features: the OSH analysis is usually task-based and focused on job profiles, while the MAH analysis is space-based and focused on plant characteristics. The basic idea of the proposed approach is to merge spatial information and job profile features in order to improve OSH assessment; thus, a risk index derived by the recent standard ISO 12100 (2010) has been adapted. In detail, the proposed index combines exposure times of each worker at each plant unit – derived from the OSH analysis – with damage areas derived from MAH analysis allowing a quantitative assessment of the MAH risk level for each individual job profile. The model has been tested in a large petrochemical plant; several hypotheses have been developed in order to validate the model. Results have showed the potentiality of the proposed approach in providing a common and coherent representation of both MAH and OSH risks, according to job profiles and plant units.  相似文献   
186.
In this study, an Integrated Simulation-Data Envelopment Analysis (DEA) approach is presented for optimum facility layout of maintenance workshop in a gas transmission unit. The process of repair of incoming parts includes various operations on different facilities. The layout problem in this system involves determining the optimum location of all maintenance shop facilities. Layout optimization plays a crucial role in this type of problems in terms of increasing the efficiency of main production line. Standard types of layouts including U, S, W, Z and straight lines are considered. First, the maintenance workshop is modeled with discrete-event-simulation. Time in system, average waiting time, average machine utilization, average availability of facilities, average queue length of facilities (AL) and average operator utilization are obtained from simulation as key performance indicators (KPIs) of DEA. Also, safety index and number of operators are considered as other KPIs. Finally, a unified non-radial Data Envelopment Analysis (DEA) is presented with respect to the stated KPIs to rank all layouts alternatives and to identify the best configuration. Principle Component Analysis (PCA) is used to validate and verify the results. Previous studies do not consider safety factor in layout design problems. This is the first study that presents an integrated approach for identification of optimum layout in a maintenance workshop of gas transmission unit by incorporating safety and conventional factors.  相似文献   
187.
Because of their high organic and nitrogen loads and the presence of toxic and phytotoxic compounds, methanogenic landfill leachates are not easily biodegradable; therefore, direct biological treatment of these wastewaters in conventional treatment plants is not recommended.In the present paper, we report the results of an experimental investigation conducted with the aim of defining an innovative integrated process that is low in cost and easily manageable and that is able to substantially improve the characteristics of methanogenic leachates.Thus, an initial oxidation process was developed using hydrogen peroxide without a catalyst, which, operating under ambient conditions, reduces the phytotoxic compound content to 10% of the initial level, reduces the COD (chemical oxygen demand) content by 50% and increases the rapidly biodegradable substrate content by 50%. Next, nitrogen removal is accomplished by means of struvite precipitation using seawater bittern and bone meal as sources of magnesium and phosphorus, respectively, with this process, abatements were reached of approximately 90% of the ammonia nitrogen, which was recovered as struvite powder.  相似文献   
188.
IntroductionTheuseofchemicals,includingpesticides,hasbecomeanintegralandeconomicallyessentialpartofmodernagriculture.Pesticide?..  相似文献   
189.
Laboratory scale studies on removal of chromium from industrial wastes   总被引:3,自引:0,他引:3  
Chromium being one of the major toxic pollutants is discharged from electroplating and chrome tanning processes and is also found in the effluents of dyes,paint pigments,manufacturing units etc.Chromium exists in aqueous systems in both trivalent(Cr^3 )and hexavalent (Cr^6 )forms.The hexavalent form is carcinogenic and toxic to aquatic life,whereas Cr^3 is however comparatively less toxic.This study was undertaken to investigate the total chromium removal from industial effluents by chemical means in order to achieve the Pakistan NEQS level of 1 mg/L by the methods of reduction and precipitation.The study was conducted in four phase Ⅰ,the optimum pH and cost effective reducing agent among the four popular commercial chemicals was selected.As a result,pH of 2 was found to be most suitable and sodium meta bisulfate was found to be the most cost effective reducing agent respectively.Phase Ⅱ showed that lower dose of sodium meta hisulfate was sufficient to obtain 100% efficiency in reducing Cr^6 to Cr^3 ,and it was noted that reaction time had no significance in the whole process.A design curve for reduction process was established which can act as a tool for treatment of industrial effluents.Phase Ⅲ studies indicated the best pH was 8.5 for precipitation of Cr^3 to chromium hydroxide by using lime.An efficiency of 100% was achievable and a settling time of 30 minutes produced clear effluent.Finally in Phase Ⅳ actual waste samples from chrome tanning and electroplating industries,when precipitated at pH of 12 gave 100% efficiency at a settling time of 30 minutes and confirmed that chemical means of reduction and precipitation is a feasible and viable solution for treating chromium wastes from industries.  相似文献   
190.
火山灰的研究作为探讨古气候和古环境的一种手段,近十年来引起了国内外学者的广泛关注。气候学和古环境学的研究表明,火山喷发可以导致某一区域内短期的气候变化或者对冰期产生强烈影响。同时,火山灰层的成因机制决定了其空间分布的等时性和广泛性,因此,火山灰的地层学特征和精确定年,具有重要的地层对比意义。目前,全球各地已经开展了许多火山灰年代学与地层学的研究。在中国,尤其是东北地区,虽然有着丰富的火山资源,但是火山灰年代学与地层学的研究工作依然比较匮乏,本文简要回顾了一下中国东北、欧洲、新西兰、日本、俄罗斯等地区的火山灰研究工作,旨在为以后的研究提供一定的参考资料。  相似文献   
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