A three dimensional model of muckpile formation and grade boundary movement in open pit blasting

Summary Formulation and case studies of a three dimensional kinematic model are presented. Thein situ overburden geometry can be simulated accurately and various initiation patterns of blasts can be modelled. The overburden geometry, hole patterns and explosive distribution are all explicit model inputs. Because the effect of explosive properties, rock mass condition and inter-row delay are very difficult to measure in terms of blast performance, these are represented in the model by control parameters which are left for calibration using field data. The output of the model is a three dimensional muckpile shape of any cross section and a contour map of grade distribution within the muckpile. Two case studies are presented which have shown that the model is a valuable tool for optimizing production blasting as well as for controlling grade dilution during blasting.     

从水流挟沙力和河槽形态规律分析黄河调水调沙

在分析水流挟沙力和河槽水力形态规律的基础上，研究调节流量、含沙量和泥沙组成的优化组合，解决河道输沙减淤和河槽相对稳定问题，提出调水调沙方向。达到合理利用水资源和河道减淤与治理相结合的目的．     

基于超熵理论的泥石流危险性模糊综合评判

泥石流灾害往往造成巨大经济损失,但由于其影响因素众多,如何合理进行危险性评判一直是研究的焦点问题.本文以研究项目为依托,选择泥石流流域沟谷的纵剖面形态指数作为流域的地貌特征指标,用超熵理论量化泥石流流域地貌系统的稳定性与演化趋势,并借助于模糊综合评判手段,对泥石流危险性进行评价.评判结果表明:该方法的评价结果与实际较为接近,为泥石流流域系统的演化趋势预测以及危险性等级划分提供了良好的分析方法.     

Performance of a base isolator with shape memory alloy bars

A new and innovative base isolation device is introduced in this paper based on extensive research carried out by the authors and their co-workers. A prototype of the device was built and experimentally tested on the shaking table. The new base isolation device consists of two disks, one vertical cylinder with an upper enlargement sustained by three horizontal cantilevers, and at least three inclined shape memory alloy (SMA) bars. The role of the SMA bars is to limit the relative motion between the base and the superstructure, to dissipate energy by their super-elastic constitutive law and to guarantee the re-centring of the device. To verify the expected performance, a prototype was built and tested under sinusoidal waves of displacement of increasing frequency with different amplitudes. It is shown that the main feature of the proposed base isolation device is that for cyclic loading, the super-elastic behavior of the alloy results in wide load-displacement loops, where a large amount of energy is dissipated.     

Shaking‐table tests on reinforced concrete frames with different isolation systems

The effectiveness of seismic isolation in protecting structural and non‐structural elements from damage has been assessed in an extensive programme of shaking‐table tests, carried out on four identical 1/3.3‐scale, two‐dimensional, reinforced concrete (R/C) frames. Four different isolation systems were considered, namely: (i) rubber‐based, (ii) steel‐based, (iii) shape memory alloy (SMA)‐based and (iv) hybrid, i.e. based on both SMA and steel components, isolation systems. This paper presents a comprehensive overview of the main results of the experimental tests on base‐isolated models, whose structural response is described through: (i) maximum base displacements; (ii) maximum interstorey drifts; (iii) maximum storey accelerations and (iv) maximum storey shear forces. The evolution of the fundamental frequency of vibration of the R/C frame during the tests is also described. The beneficial effects of using base isolation resulted in no or slight damage, under strong earthquakes, to both structural and non‐structural members, as well as to the internal content of the building. The comparison with the experimental results obtained in shaking‐table tests on similar fixed‐base models emphasizes these positive aspects. Finally, advantages and drawbacks related to the use of each isolation system are discussed in the paper. Copyright © 2006 John Wiley & Sons, Ltd.     

某隔震结构动力特性的理论分析与脉动测试

本文针对国内最大单体隔震建筑建立了SAP2000三维分析模型,并进行了动力特性的理论分析;现场对实际建筑进行了平移振动、扭转振动、垂直振动和平面内弯曲4个方面的脉动测试。利用工程振动反演理论分析了该结构的固有频率、振型、阻尼等动力特性,将实测结构动力特性与理论分析结果进行比较,详细分析实测结果与理论结果差别的原因,并据此对理论模型进行修正,为今后类似结构的设计积累了资料。     

Shape Similarity measures of Linear Entities

The essential of feature matching technology lies in how to measure the similarity of spatial entities.Among all the possible similarity measures,the shape similarity measure is one of the most important measures because it is easy to collect the necessary parameters and it is also well matched with the human intuition.In this paper a new shape similarity measure of linear entities based on the differences of direction change along each line is presented and its effectiveness is illustrated.     

Strain and competence contrast estimation from fold shape

A new method to estimate strain and competence contrast from natural fold shapes is developed and verified by analogue and numerical experiments. Strain is estimated relative to the nucleation amplitude, A_N, which is the fold amplitude when the amplification velocities caused by kinematic layer thickening and dynamic folding are identical. A_N is defined as the initial amplitude corresponding to zero strain because folding at amplitudes smaller than A_N is dominantly by kinematic layer thickening. For amplitudes larger than A_N, estimates of strain and competence contrast are contoured in thickness-to-wavelength (H/λ) and amplitude-to-wavelength (A/λ) space. These quantities can be measured for any observed fold shape. Contour maps are constructed using existing linear theories of folding, a new nonlinear theory of folding and numerical simulations, all for single-layer folding. The method represents a significant improvement to the arc length method. The strain estimation method is applied to folds in viscous (Newtonian), power-law (non-Newtonian) and viscoelastic layers. Also, strain partitioning in fold trains is investigated. Strain partitioning refers to the difference in strain accommodated by individual folds in the fold train and by the whole fold train. Fold trains within layers exhibiting viscous and viscoelastic rheology show different characteristic strain partitioning patterns. Strain partitioning patterns of natural fold trains can be used to assess the rheological behaviour during fold initiation.     

雨滴尺度谱谱参数和形状因子的分析

作者计算了３次降不过程的雨滴尺度谱参数，并进行Ｍ－Ｐ分布拟合和Г分布拟合。同时还计算了雨滴谱形状因子Ｓ（Ｚ，Ｒ），分析了形状因子与雨强之间的关系。     

ICE Particle Size and Shape Effect on Solar Energy Scattering Angular Distribution

The rare occurrence of te halos produced by cirrus ice crystals in nature has been investigated by modelling the incident solar (visible) light scattering angular distribution using the Monte Carlo/ray tracing method.The results show that the irregular shapes of ice crystals and large population of small ice particles in cirrus are responsible forthe rare occurrence of halos.