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991.
992.
从围护结构节能与防火一体化思路出发,提倡钢筋混凝土结构保温一体化建筑体系和砌体结构保温一体化建筑体系;尤其主张在我国建筑工业化全面升级的基础上大力开发与推广保温型混凝土预制装配化技术,统一建筑模数,实现标准化与多样化;针对预制装配化保温型混凝土在梁、构造柱等容易出现的冷、热桥问题的部位,创新式提出以相变储能材料与建筑结构相融合来提高建这些部位的热工性能,减少温度梯度;从系统上做到保温与建筑同寿命、免维护、工序少,工期短、耐火等,从而真正实现低碳,构建建筑围护结构节能防火一体化建筑体系。 相似文献
993.
994.
安全仪表系统的开发与要求 总被引:1,自引:1,他引:0
综述安全仪表系统的发展过程;对其主要组成、特点以及其各自要求进行研讨;给出安全仪表系统开发的简化流程;探讨安全仪表系统的经济性分析和仪表选择方法;对安全仪表系统整体生命周期中的计划编制、设计、实施、运行、维护和确认等各阶段活动的关键要求进行了讨论和研究。该研究对安全仪表系统的深入理解有指导作用,并为安全仪表系统的分析、设计、实施、运行和维护等活动提供参考。 相似文献
995.
汽车行人碰撞接触中行人运动学规律仿真研究 总被引:6,自引:2,他引:4
基于交通事故模拟分析PC-Crash软件及其内嵌多体系统动力学分析MADYMO模块,建立并验证了车辆多体模型和行人多体模型;对汽车与行人碰撞接触阶段的行人运动学具有较大影响的因素展开广泛分析,并构建汽车行人碰撞仿真试验方案;通过选取对汽车与行人碰撞接触阶段具有较大影响的因素作为仿真试验的自变量,对不同碰撞环境下汽车与行人碰撞接触过程中的行人运动学规律(包括运动姿态和对应的碰撞车速阈值)进行深入研究;汽车行人碰撞仿真与真实事故以及碰撞试验对比具有较好的规律吻合性和一致性。研究表明,笔者采用的计算机建模仿真方法在汽车行人碰撞运动学研究中具有实用价值。 相似文献
996.
The ability of polydimethlysiloxane coated solid phase microextraction (SPME) fibers to predict bioavailability has been documented for a number of species and compounds. There are also a variety of established methods for establishing SPME-based bioavailability estimates; however, factors such as time until equilibrium and exposure regimen could affect fiber concentrations and have not yet been thoroughly tested. Exposure time may influence SPME fiber concentrations at equilibrium. Co-exposure of the fibers with different animals or the invertebrate species used could yield different estimates than those acquired using a shaker table system to achieve equilibrium between the sediment and SPME fibers. The current study examined the effects of time and exposure method (shaker table versus co-exposure with test species) on SPME fiber concentrations for two hydrophobic compounds: permethrin and p,p′-dichlorodiphenyldichloroethylene (DDE). An additional experiment with permethrin determined whether animal densities or fiber number influenced fiber concentrations. There were significant differences between the time required for SPME fibers to reach equilibrium when co-exposed with different species or separately, but fiber concentrations at equilibrium among treatments for both compounds were similar. Furthermore, among the 12 variations in species and fiber densities, there were no significant differences among treatments indicating that neither the route of exposure, animal density, nor fiber volume influenced SPME fiber estimates. This demonstrated that SPME fiber concentrations at equilibrium were not affected by exposure conditions, increasing their versatility in environmental assessments. 相似文献
997.
高效液相色谱法检测与化感现象相关的5种酚酸 总被引:17,自引:2,他引:15
建立了香草酸、对羟基苯甲酸、丁香酸、香豆酸和阿魏酸等5种酚酸的高效液相色谱测定方法,利用本方法在土壤溶液和残茬腐解产物中进行5种酚酸的检测,结果表明,大豆生长一段时间后,在灭菌土壤中、未灭菌土壤中和不同茬口的土壤中,均检测到丁香酸,在残茬腐解产物中检测到香草酸、丁香酸、香豆酸和阿魏酸。 相似文献
998.
Hamid-Reza Heidari Farideh Golbabaei Mahmoud Alimohammadi Abbas Rahimi-Froushani 《International journal of occupational safety and ergonomics》2013,19(4):395-405
This study describes optimization of headspace solid phase microextraction followed by gas chromatography equipped with a flame ionization detector for toluene at trace level in spiked urine. The parameters affecting the extraction and gas chromatographic determination of analytes were studied: extraction time and temperature; desorption time and temperature; addition of NaCl; and pH, volume and agitation of the sample. Optimized headspace extraction was carried out at 30 °C for 6 min in the presence of 0.2 g-m-1of NaCl in the sample solution. Also, sample volume and sample pH were optimized at 5 ml and 7 (neutral pH), respectively. Desorption of the analytes was carried out at 250 °C for 60 s. The optimized procedure was validated with 3 different pools of spiked urine; it showed good reproducibility over 6 consecutive days and 6 within-day experiments. The study also determined the accuracy, linearity and detection limits of this method. 相似文献
999.
1000.
Methodologies are presented for dating releases of light nonaqueous phase liquids (LNAPLs) using an inverse modeling approach with simple analytical models. Models for LNAPL plume migration are presented to predict LNAPL plume velocity in the unsaturated and saturated zones as a function of basic soil and fluid properties. A relative mobility factor is introduced for LNAPL movement at the water table that depends primarily on the van Genuchten n parameter (related to the breadth of the soil pore size distribution) and the magnitude of water table fluctuations. Estimated LNAPL plume velocities compare reasonably with more rigorous numerical models, which may be used in cases where data availability warrant the greater effort entailed.Two methods of estimating release timing and its uncertainty are investigated. A direct estimation method is described that determines travel time for a single observed travel distance based on estimated soil and fluid properties. Release date uncertainty may be determined using the first order (FO) or Monte Carlo (MC) methods. The second method for estimating release date involves nonlinear parameter estimation utilizing distance vs. time measurements and other data.A case study is presented for a field site where independent estimates of release timing were obtained from a numerical modeling analysis. Release timing estimates based on direct inversion of the analytical timing model agree well with the numerical analysis. Results for a second field site indicate that release date confidence limits estimated by the FO method, assuming log-normally distributed travel times, are close to values determined by the MC method, which makes no assumption regarding the form of the travel time probability distribution.Results for a hypothetical problem indicate that LNAPL velocity and travel time may be accurately estimated if sufficient data on travel distance vs. time are available. Incorporating prior information on relevant soil and fluid properties into the objective function reduces the uncertainty in release date if prior estimates are accurate. However, biased prior estimates may lead to over- or underestimation of release date uncertainty. Simultaneous estimation of soil and fluid properties and release date is possible if prior information is available to condition the parameter estimates. 相似文献