SHRP 沥青研究课题进展

1987年春天,美国国会通过了一项法案,为美国迄今为止最大的,最雄心勃勃的战略公路研究计划(Strategic HighwayResearch Program),在五年内提供一亿伍千万美元的资金,占美国联邦公路资金的0.25%。这个研究计划是在美国各州公路和运输官员协会(AASHTO)、美国运输研究委员会(TRB)和美国联邦公路管理局(FHWA)的领导和指导下制定的。1987年秋天,最初的六个大课题集中为四个大课题:沥青 5000万美元路面长期性能 5000万美元公路运行 2120万美元     

岩石普氏坚固性系数的应用

苏联自1976年起实行测定岩石坚固性系数的国家标准,它是用仪捣碎岩石样品来测定的。苏联《矿山杂志》1979年指出,国标21153.1—75必须修正,因为它没有考虑到仪器夯捣垫底的可让性对     

奥林奇县水库二维溃坝洪水流量分析

二维溃坝模型已用来预测奥林奇县水库下游冲积扇的淹没范围。这个模型是以浅水长波的连续方程和动量方程的扩散形式为基础的。而控制方程是用显式数值方法求解的。与一维模型比较,二维模型可以预测更大的淹没范围。     

大地电磁测深数据显示中视电阻率的定义

本文对大地电磁测深数据显示中视电阻率重新进行了定义。该定义以频率归一化阻抗函数为基础。我们从理论上分析了现有定义和本文提出的定义,并用一维地层模型曲线对两者做了比较。用本文的定义计算视电阻率曲线能更好地近似地层的实际电阻率。     

Training for an agricultural discrimination task

Skeleton weed, centaurea juncea, is a declared weed in Western Australia because it competes with grain crops for nutrients and moisture. When it is found during harvesting, mechanised teams search and eradicate it. In an earlier report of field trials (Hartley et al, 1989) it was reported that search teams' detection rate was poor and since search teams had usually never seen skeleton weeds, visual discrimination learning was to be expected and observed during searches. The present study investigated the nature of this discrimination learning in a laboratory by developing a training programme of colour photographic slides of weeds in stubble. Subjects receiving specific training with feedback on their performance compared with those receiving pseudo-training showed a significant improvement in detections. Subsequently the benefit of the programme was validated in a field trial.     

Adaptive synthesis of distance fields

We address the computational resource requirements of 3D example-based synthesis with an adaptive synthesis technique that uses a tree-based synthesis map. A signed-distance field (SDF) is determined for the 3D exemplars, and then new models can be synthesized as SDFs by neighborhood matching. Unlike voxel synthesis approach, our input is posed in the real domain to preserve maximum detail. In comparison to straightforward extensions to the existing volume texture synthesis approach, we made several improvements in terms of memory requirements, computation times, and synthesis quality. The inherent parallelism in this method makes it suitable for a multicore CPU. Results show that computation times and memory requirements are very much reduced, and large synthesized scenes exhibit fine details which mimic the exemplars.     

计算机模拟扫描电镜颗粒边缘粗糙度外貌特征

各种石英颗粒表面特征的发育与否,是任何扫描电镜分析重建地质环境的基础,对于在石英颗粒表面获得的许多可见特征来说,虽然已有许多"清单"(Krinsley和Donahue,1968:Cater,1984),但是,专门检测技术的有效性还是一个争论的问题.由这类分析获得的最为重要的物理参数之一是边缘磨蚀,因为圆度值是一种发现于石英砂颗粒的主要形态特征.例如,1984年Goudie和Bull发现两类非洲沉积物之间的主要差异是,在深度风化剖面中总体缺乏边缘磨蚀颗粒,并以此为基础建立了该研究区的斜坡