水石流概化水槽试验相似律的探讨

针对水石流粒粗，粘性小的特点，提出了利用水槽进行分段模拟水石流的设想，首次通过几何率解决难度较大的阻力相似问题，改变以往过度加糙的方式，通过变粒径尺度的方法消除了相模型沙级配不连续相似的问题，较好地实现了固体物质级配相停，达到了泥石流的密度相似和输沙相似，通过水槽概化模型实验实例，对本方法进行了验证。     

高架斜坡道路三维交通噪声动态模拟

为研究高架斜坡道路声场分布规律,根据城市快速路设计规范建立相应的斜坡道路模型,通过微观交通仿真软件结合噪声计算插件对其进行噪声动态模拟,获取三维空间的噪声值及道路垂直截面声场分布图,给出高架斜坡道路的声场分布规律。结果表明:高架斜坡道路上下坡两侧声场分布不对称,上坡一侧声影区界限划分较为明显,而下坡一侧声影区界限划分不明显;下坡侧接受点在高度4~20 m时,噪声值大于上坡侧对称点处的噪声值。     

Modeling Runoff Response to Land Cover and Rainfall Spatial Variability in Semi-Arid Watersheds

Hydrologic response is an integrated indicator of watershed condition, and significant changes in land cover may affect the overall health and function of a watershed. This paper describes a procedure for evaluating the effects of land cover change and rainfall spatial variability on watershed response. Two hydrologic models were applied on a small semi-arid watershed; one model is event-based with a one-minute time step (KINEROS), and the second is a continuous model with a daily time step (SWAT). The inputs to the models were derived from Geographic Information System (GIS) theme layers of USGS digital elevation models, the State Soil Geographic Database (STATSGO) and the Landsat-based North American Landscape Characterization classification (NALC) in conjunction with available literature and look up tables. Rainfall data from a network of 10 raingauges and historical stream flow data were used to calibrate runoff depth using the continuous hydrologic model from 1966 to 1974. No calibration was carried out for the event-based model, in which six storms from the same period were used in the calculation of runoff depth and peak runoff. The assumption on which much of this study is based is that land cover change and rainfall spatial variability affect the rainfall-runoff relationships on the watershed. To validate this assumption, simulations were carried out wherein the entire watershed was transformed from the 1972 NALC land cover, which consisted of a mixture of desertscrub and grassland, to a single uniform land cover type such as riparian, forest, oak woodland, mesquite woodland, desertscrub, grassland, urban, agriculture, and barren. This study demonstrates the feasibility of using widely available data sets for parameterizing hydrologic simulation models. The simulation results show that both models were able to characterize the runoff response of the watershed due to changes of land cover.     

CENTRIFUGE MODELING OF ONE-DIMENSIONAL SUBSURFACE CONTAMINATION1

ABSTRACT: One-dimensional contaminant transport through a saturated soil is modeled using a 1.2-m radius geotechnical centrifuge. Small-scale physical modeling in the centrifuge is achieved in relatively short time, at stress distributions that are similar to those experienced in the prototype (actual site). A 0.05 mol/l of sodium chloride solution is used as a contaminant and conductivity cells measure the concentration of the contaminant throughout the porous medium. Scaling analysis for centrifuge modeling and 1-g modeling are briefly discussed and it is concluded that centrifuge modeling simulates the effect of molecular diffusion; however, scaling of the effect of mechanical dispersion may be violated in the centrifuge if the interstitial fluid velocity is high. Centrifuge test results show good agreement with the predicted relationship between the coefficient of hydrodynamic dispersion and the Peclet number using column tests. Centrifuge modeling can be used as a complement of numerical modeling although the effect of mechanical dispersion may be overestimated in the former.     

大豆油乙氧基化合物的生物降解

采用振荡培养实验和活性污泥模拟实验对大豆油乙氧基化合物（SOE）进行了生物降解研究。实验结果表明，振荡培养实验中SOE的初级生物降解度随平均环氧乙烷加成数的增多而略有下降，且SOE-4，SOE-10，SOE-20的初级生物降解度在第6天时分别为97．3％，91．1％，89．4％；活性污泥模拟实验中SOE的初级生物降解度随平均环氧乙烷加成数的增多而增加，且SOE-4，SOE-10，SOE-20的初级生物降解度在第8天时分别为29．0％，81．2％，100．0％。用激光粒度仪测量SOE水合物在不同静置时间时的粒径分布及分散度结果表明，随静置时间的延长，平均环氧乙烷加成数少的SOE水合物粒径逐渐增大，且分散性或水溶性变差，易产生团聚导致初级生物降解度降低。对水溶性或分散性较差的表面活性剂，建议以振荡培养实验研究其生物降解性较为恰当。     

电缆隧道火灾数值仿真及分析

电缆隧道灭火以及人员疏散的关键,在于对灾变条件下隧道火灾参数变化的正确预测,特别是火焰、烟气蔓延范围,烟气浓度变化以及有毒气体的扩散范围等参数的预测。为了获得电缆隧道火灾参数,应用美国国家标准和技术研究院(NIST)开发的FDS(Fire Dynam ics Simulator)软件,建立电缆隧道模型,对隧道火灾进行全尺寸模拟,通过对模拟实验数据处理和分析,给出电缆隧道火灾时烟气浓度和氧气浓度,纵向温度的变化规律,火焰蔓延情况以及高温烟气在隧道中水平蔓延规律,为有效救援和紧急疏散以及消防决策提供一定依据。     

A dynamic hydrological Monte Carlo simulation model to inform decision-making at Lake Toolibin,Western Australia

Lake Toolibin, an ephemeral lake in the agricultural zone of Western Australia, is under threat from secondary salinity due to land clearance throughout the catchment. The lake is extensively covered with native vegetation and is a Ramsar listed wetland, being one of the few remaining significant migratory bird habitats in the region. Currently, inflow with salinity greater than 1000 mg/L TDS is diverted from the lake in an effort to protect sensitive lakebed vegetation. However, this conservative threshold compromises the frequency and extent of lake inundation, which is essential for bird breeding. It is speculated that relaxing the threshold to 5000 mg/L may pose negligible additional risk to the condition of lakebed vegetation. To characterise the magnitude of improvement in the provision of bird breeding habitat that might be generated by relaxing the threshold, a dynamic water and salt balance model of the lake was developed and implemented using Monte Carlo simulation. Results from best estimate model inputs indicate that relaxation of the threshold increases the likelihood of satisfying habitat requirements by a factor of 9.7. A second-order Monte Carlo analysis incorporating incertitude generated plausible bounds of [2.6, 37.5] around the best estimate for the relative likelihood of satisfying habitat requirements. Parameter-specific sensitivity analyses suggest the availability of habitat is most sensitive to pan evaporation, lower than expected inflow volume, and higher than expected inflow salt concentration. The characterisation of uncertainty associated with environmental variation and incertitude allows managers to make informed risk-weighted decisions.     

Optimal heat rejection pressure for transcritical CO2 refrigeration cycle with an expander

Heat rejection pressure plays an important role in designing a transcritical CO₂ refrigeration system, and it has an optimal value to maximize the system’s coefficient of performance (COP). With a thermodynamic simulation model, the optimal heat rejection pressure is studied in the paper for an expander cycle, as well as conventional throttle valve cycle. The effects of compressor efficiency, expander efficiency, gas cooler outlet temperature, and evaporation temperature on the optimal heat rejection pressure are analyzed. It is the first time for a transcritical CO₂ expander cycle that the optimal heat rejection pressure is correlated with the gas cooler outlet temperature and the evaporation temperature at given compressor efficiency and expander efficiency. The average deviation from the correlation to simulation results is less than 1.0%. The correlation provides a guideline to system development and performance optimization of a transcritical CO₂ expander cycle.     

基于可拓学的尾矿库安全评价

为综合评价尾矿库的安全状态,基于尾矿库灾变机理和大量工程实践构建了一套包括3级指标、22个因素的评价指标体系,并确定了评价指标的等级量值区间。采用EAHP和熵权法结合的方式确定指标权重,基于可拓理论评价尾矿库的安全等级。以湖南黄金集团责任有限公司旗下的7座尾矿库为案例,评价其安全状态,根据蒙特卡洛模拟基本理论,基于Crystal Ball对案例进行敏感性分析,找出具体敏感因素,为后期尾矿库安全管理提供简单有效的控制方法。     

冲击响应谱规范试验室模拟述评

冲击响应谱试验已是航天产品必做的力学环境试验,本文介绍了目前试验室普遍使用的冲击响应谱模拟的手段,阐述了用电动振动台模拟和用机械式试验机模拟的差异,并对存在的差异进行了讨论。