用计算机模拟送进角与辗轧角对Accu-Roll轧机变形区的影响

在建立Accu-Roll轧机变形区模型的基础上,开发出计算机模拟软件,可方便地通过变形区纵剖面计算机图象显示分析工艺参数对变形区的影响,从而为合理地选取与优化工艺参数提供依据。     

The internal barriers of rotation for the 209 polychlorinated biphenyls

The internal barrier of rotation (Erot) was calculated for all 209 polychlorinated biphenyls (PCBs) by using a semi-empirical method, viz. the Austin Model 1 (AMI) Hamiltonian. The difference in total energy between a forced planar state and an optimised twisted structure was defined as Erot. The Erot values were in the range of 8.33 to 483 kj/mol, and were significantly influenced by the number of chlorine atoms inortho position. An additional structural characteristic of the PCBs influencing Erot ofortho substituted congeners was substitution by chlorine atoms in vicinalmeta positions, which is assumed to prevent outward bending ofortho substituents. This so-called buttressing effect contributed with 4 to 31 kj/mol per added chlorine atom. In conclusion, the internal barrier of rotation, calculated for all 209 PCBs, provides an important structure dependent physico-chemical parameter for multivariate modelling of future quantitative structure-activity and structure-property relationships (QSARs/QSPRs).     

含油污水的综合处理法及其应用

概述了竖向隔板分油法、蜂窝斜管分油法及磁性颗粒吸附过滤法 ,将这 3种方法结合处理某机修厂的含油污水 ,取得了满意效果。     

Migration of saline solutions in variably saturated porous media

Migration of concentrated NaNO3 solutions in homogeneous packs of pre-wetted silica sands was investigated using a light transmission system. Solutions of 5 molal NaNO3 were found to migrate downward 24-62% faster than pure water, in an unstable, fingered manner. This behavior was attributed primarily to a surface tension induced, non-zero apparent contact angle between the imbibing and the resident fluids. For saline solutions of similar surface tension to that of pure water (achieved by the addition of 2% methanol), the migration rates and plume shapes were comparable to that of water, demonstrating that density was not the primary source of the observed differences in migration patterns. At depths where resident saturation increased above residual, the migration process appeared to occur via film flow with slight changes in saturation (<4%), rather than in a series of abrupt jumps, as observed at shallower depths. A method for contact angle scaling was used to illustrate the effects of non-zero contact angles on capillary pressure-saturation curves.     

斜刃冲裁力计算方法的探讨

对剪切线为直线的斜刃冲裁,给出了可普遍适用的冲裁力的计算式,并分析了剪切线为直线、斜刃形状为曲线的冲裁力的计算.     

双斜面刃口切舌弯曲模的设计

通过理论分析 ,介绍了双斜面刃口切舌弯曲模的设计方法及单面切舌零件的卸料及防止垂直切口撕裂的方法     

煤尘润湿接触角的BP神经网络估算方法研究

通过采集和测定35个矿区煤样品的化学组成、结构参数和润湿接触角,构建了以13个影响因子为输入参数和以接触角为输出目标的3层BP人工神经网络,并利用该模型估算煤尘润湿接触角。结果表明,隐含层节点数为19时,接触角估算值与实测值的决定系数R2=0.957,平均相对误差为4.59%,表明基于BP神经网络建立的煤尘润湿接触角估算模型具有很高的精度。     

Safety effectiveness and crash cost benefit of red light cameras in Missouri

Objective: Red light cameras (RLCs) have generated heated discussions over issues of safety effectiveness, revenue generation, and procedural due process. This study focuses on the safety evaluation of RLCs in Missouri, including the economic valuation of safety benefits. The publication of the national Highway Safety Manual (HSM; American Association of State Highway and Transportation Officials) in 2010 produced statistical safety models for intersections and spurred the calibration of these models to local conditions.

Methods: This study adds to existing knowledge by applying the latest statistical methodology presented in the HSM and more current data. Driver behavior constantly changes due in part to driving conditions and the use of technology. The safety and economic benefit evaluation was performed using the empirical Bayes method, which accounts for regression to the mean bias. For the economic benefit evaluation, the KABCO crash severity scale and crash cost estimates were used. A total of 24 4-leg urban intersections were randomly selected from a master list of RLCs in Missouri from 2006 to 2011. Additionally, 35 comparable nontreated intersections were selected for the analysis.

Results and Conclusions: The implementation of RLCs reduced overall angle crashes by 11.6%, whereas rear-end crashes increased by 16.5%. The net economic crash cost benefit of the implementation of RLCs was $35,269 per site per year in 2001 dollars (approximately $47,000 in 2015 dollars). Thus, RLCs produced a sizable net positive safety benefit that is consistent with previous statistical studies.     

某电子方舱舱内热环境的模拟研究

目的以某电子方舱为研究对象,分析在现有结构条件下,空调所提供的冷量能否满足舱内电子设备正常工作要求和人员舒适要求。方法分析和研究舱内的传热问题,采用FLUENT软件,并结合κ-ε两方程紊流模型与SIMPLE算法对方舱内的热环境进行三维数值模拟。结果在保证空调送风温度和速度不变的前提下,送风角度分别为30°和0°时,都能基本保证电子设备正常工作要求和舒适性要求。当送风角度为30°时,方舱降温效果较好。结论通过分析得到方舱制冷系统设计的不足之处,并提出了改进制冷系统冷气通路的方法,对今后方舱的制冷系统设计改进具有指导意义。     

多因素下小尺度油罐火火焰倾角的研究

以柴油为研究对象,搭建了小尺度油罐火实验台,采用理论分析与实验研究相结合的方法,开展了有风条件下不同液位深度和罐顶开口宽度的小尺度油罐火火焰倾角的实验研究。结果表明,火焰倾角随风速的增加先迅速增加,然后趋于平稳。在相同的罐顶开口宽度和风速条件下,火焰倾角随着液位深度的增加呈现出减小的趋势。这是因为火焰微元在油罐开口处的速度随着液位深度的增加而增加,风速对火焰倾角的影响显著减小。当风速和液位深度一定时,质量损失速率随罐顶开口宽度的增大而增大,火焰倾角随着罐顶开口宽度的增大逐渐减小。