Improved method for roadside barrier length of need modeling using real-world trajectories

The 2011 AASHTO Roadside Design Guide (RDG) contains perhaps the most widely used procedure for choosing an appropriate length of need (LON) for roadside barriers. However, this procedure has several limitations. The procedure uses a highly simplified model of vehicle departure, and the procedure does not allow designers to specify an explicit level of protection. A new procedure for choosing LON that addresses these limitations is presented in this paper. This new procedure is based on recent, real-world road departure trajectories and uses this departure data in a more realistic way. The new procedure also allows LON to be specified for a precisely known level of protection – a level which can be based on number of crashes, injury outcomes or even estimated crash cost – while still remaining straightforward and quick to use like the 2011 RDG procedure.     

大麻工艺纤维长度与细度的相关性初探

通过对大麻工艺纤维长度和直径投影宽度的相关性研究，认为大麻工艺纤维长度和细度之间存在“越长越粗，越短越细”的规律。     

A probabilistic model for cleavage fracture with a length scale--parameter estimation and predictions of stationary crack experiments

This study presents a large experimental investigation in the transition temperature region on a modified A508 steel. Tests were carried out on single-edge-notch-bend specimens with three different crack depth over specimen width ratios to capture the strong constraint effect on fracture toughness. Three test temperatures were considered, covering a range of 85 °C. All specimens failed by cleavage fracture prior to ductile tearing. A recently proposed probabilistic model for the cumulative failure by cleavage was applied to the comprehensive sets of experimental data. This modified weakest link model incorporates a length scale, which together with a threshold stress reduce the scatter in predicted toughness distributions as well as introduces a fracture toughness threshold value. Model parameters were estimated by a robust procedure, which is crucial in applications of probabilistic models to real structures. The conformity between predicted and experimental toughness distributions, respectively, were notable at all the test temperatures.     

山区建筑的结构设计注意点及探讨——永安一中教学楼设计心得

本文通过工程实例分析了山区建筑的结构设计特点,并提出了结构设计中应注意的问题。     

传统机械加工表面形貌评定的缺陷及发展方向

本文通过对传统机械加工表面形貌评定体系的分析，指出其不能完整地、从本质上反映表面的特征。并提出轮廓长度率、表面真面积率、表面分形维数D、比例系数K四个评定参数，通过分析可以看出这组参数比传统方法所具有的优越性和代替传统方法的可能性。     

MODELING LIQUID MASS TRANSFER IN HIGEE SEPARATION PROCESS

Correspondence concerning this paper should be addressed to Professor Richard S.H. Mah. Hsien-Hsin Tung is now affiliated with Department of Chemical Engineering, California Institute of Technology

Penetration theory is used to describe the liquid mass transfer in Higee separation process. Within a possible range of effective areas, it is shown that the predicted mass transfer coefficients are in reasonable agreement with the estimated mass transfer coefficients. The estimated coefficients were calculated from the experimental data and the possible effective areas. Hence it is concluded the penetration theory is generally applicable to describe liquid mass transfer in Higee separation process. The comparison also suggests that liquid mixing at the junctions of packing materials may be more complete in Higee process than in traditional process.     

秦山核电厂气载放射性释放的环境影响

本文评价了秦山核电厂气载放射性流出物对环境的影响。应用现场及风洞大气扩释实验结果和厂址周围的人口与食谱调查资料,估算了秦山核电厂在正常运行和事故条件下释放的气载放射性流出物对公众产生的个人有效剂量当量和集体有效剂量当量。计算结果表明,正常运行时厂址边界(0.5km)处的最大个人有效剂量当量为2.7×10~(-2)mSv/a,该剂量的大部分来自~(137)Cs 的食入(主要由地表湿沉积引起);80km 范围内的集体有效剂量当量为1.1人·Sv/a,归一化集体有效剂量当量为3.7人·Sv/GW(e)·a。文中还给出了事故情况下剂量估算结果。     

地震数据通用压缩文件格式设计

本文从生产实际需要提出了进行地震数据压缩和制定规范的压缩数据文件格式的要求，按照通用性，兼容性，可扩充性，操作简便，高缩效率几方面的要求设计了通用压缩数据文件格式及一种具体形式，讨论了数据压缩的具体策略和方法，试验表明，采用压缩数据文件格式，不但可以大比例地减小数据存贮空间（压缩比达４：１－１０：１），而且可以大大加快数据的Ｉ／Ｏ速度（提高１倍以上）。     

羰基铁类随机混合吸波材料等效电磁参数的计算

本文为计及多重散射偶极子间的相互作用，引入参量εｈ和μｈ，导得一组公式。它不仅能计算铁氧体类也能计算羰基铁类的随机混合吸波材料的等效电磁参数，均与实验结果吻合良好。