Consolidation of double‐layered ground with vertical drains

Vertical drains are usually installed in subsoil consisting of several layers. Due to the complex nature of the problem, over the past decades, the consolidation properties of multi‐layered ground with vertical drains have been analysed mainly by numerical methods. An analytical solution for consolidation of double‐layered ground with vertical drains under quasi‐equal strain condition is presented in this paper. The main steps for the computation procedure are listed. The convergence of the series solution is discussed. The comparisons between the results obtained by the present analytical method and the existing numerical solutions are described by figures. The orthogonal relation for the system of double‐layered ground with vertical drains is proven. Finally, some consolidation properties of double‐layered ground with vertical drains are analysed. Copyright © 2001 John Wiley & Sons, Ltd.     

Morphological characters of the two-ribbon flare of 1981 May 13 and their explanation

We give a summary of the morphology of the two-ribbon flare of 1981 May 13. One striking feature is that the Ha flare began at about 0338' UT and the double-ribbon structure was formed about 0346, $\text{before}$ the impulsive phase of the radio 3 cm burst at 04 11 UT. The 3 cm radio burst flux beginning at 03 33 UT showed only slow, stepwise increases lasting half an hour until the impulsive phase and this type of increase is usually regarded to be a typical thermal process. Each step in the radio flux corresponded to a variation in the Ha flare, showing that the radio and Hα emissions during this period came from the same thermal source. In this paper, we explain this behaviour in terms of Hyder's model: we think that the magnetic trough supporting the solar prominence rose for some reason, causing the prominence matter (the dark filaments) to fall along the magnetic lines and to hit the chromosphere and trigger off the flare. We give rough estimates of the energy density, the height of prominence and the infall matter at the different radio increments. We also give a qualitative explanation for the appearances of the single-peak structure in the radio burst at 0411 and the covering of the sunspot shortly after at 04 13 and propose several possible mechanisms.     

Numerical prediction of blast‐induced stress wave from large‐scale underground explosion

This paper presents a numerical model for predicting the dynamic response of rock mass subjected to large‐scale underground explosion. The model is calibrated against data obtained from large‐scale field tests. The Hugoniot equation of state for rock mass is adopted to calculate the pressure as a function of mass density. A piecewise linear Drucker–Prager strength criterion including the strain rate effect is employed to model the rock mass behaviour subjected to blast loading. A double scalar damage model accounting for both the compression and tension damage is introduced to simulate the damage zone around the charge chamber caused by blast loading. The model is incorporated into Autodyn3D through its user subroutines. The numerical model is then used to predict the dynamic response of rock mass, in terms of the peak particle velocity (PPV) and peak particle acceleration (PPA) attenuation laws, the damage zone, the particle velocity time histories and their frequency contents for large‐scale underground explosion tests. The computed results are found in good agreement with the field measured data; hence, the proposed model is proven to be adequate for simulating the dynamic response of rock mass subjected to large‐scale underground explosion. Extended numerical analyses indicate that, apart from the charge loading density, the stress wave intensity is also affected, but to a lesser extent, by the charge weight and the charge chamber geometry for large‐scale underground explosions. Copyright © 2004 John Wiley & Sons, Ltd.     

基于审查回归模型的公众气象服务支付意愿影响因素分析——以无锡、武汉和西安为例

采用审查回归模型,分别选取了中国东、中、西部的三个典型城市无锡、武汉和西安,计算了三城市受访者的支付意愿值,并对其影响因素进行了分析。结果表明：（1）支付意愿值与地区经济发展水平直接相关。无锡、武汉和西安受访者的支付意愿分别为21.68,17.15和10.07元/年;（2）年龄越长者,由于其天气知识更丰富、日常消费较节俭,对气象服务的支付意愿越低;（3）文化程度越高者,更能理解和支持气象服务事业,对气象服务的支付意愿越高;（4）月收入变量对气象服务的支付意愿有显著影响,但就不同城市的受访者而言,影响的方向并不一致。     

Simulating Temporal Fluctuations of Real Estate Development in a Cellular Automata City

This research aims to understand the source of temporal fluctuations in real estate development through simulating a cellular automata model. In this cellular automata city, investment decisions are made according to the profitability measured in a local neighbourhood. If developers think there is enough of a profit margin in a particular site, i.e. a 'niche' of investment, they will increase investment at that site. However, by increasing investment at the site, new 'niches' might be created. Therefore, the action of converging towards an equilibrium state itself paves the way towards new fluctuations. This model demonstrates the potential of using simulation to increase our understanding of real estate dynamics. The experiments suggest that locally made 'rational' decisions can lead to temporal fluctuations because of non–linearity (discrete changes/densification and local bounded information). Interestingly, the fluctuations may show the property of a temporal fractal. This requires a sufficiently sensitive process of 'niche' formation compared with a relatively large impact of additional investment. The simulation suggests that the impact should be 4 to 20 times higher than the threshold over which a niche will be formed. This condition is satisfied in most cases of real estate investment, thus suggesting a self–organised criticality in complex real estate development.     

数字化地图印刷一种随机挂网计算模型

基于彩色图像像素3刺激值与相应网点面积率之间的α幂修正的Neugebauer方程,建立由常规的调幅网为基础的调频挂网计算模型,以此实现分色胶片随机挂网     

Predicting landslide sliding distance based on energy dissipation and mass point kinematics

Natural Hazards - Based on classical mechanics and the law of energy conservation, we present a model for predicting landslide sliding distance. We conceptualize landslide movement as the movement...     

Evaluation of CBM reservoir fracture characteristics by azimuthal AVA inversion

Exploitation of coalbed methane (CBM) is directly affected by the strike and density of fractures, particularly because fractures can act as conduits for water and gas (after desorption). To realize the azimuthal amplitude versus angle (AVA) inversion for a CBM reservoir, we treated reservoirs whose fractures are aligned vertically as being equivalent to a horizontal transverse isotropic medium and simplified the P-P wave reflection coefficient formula to an approximately linear equation. Then, we adopted a modified damping least squares algorithm to solve the azimuthal AVA inversion problem. With edited macro-bins, corrected residual moveout, and normalized amplitude, the azimuthal gathers exhibited unambiguous azimuthal AVA characteristics. The #3 CBM reservoir in the Qinshui Basin was selected for a case study. The density and strike of the reservoir fractures were obtained and analyzed, and the reservoir was divided into three classes according to fracture density. Finally, in comparison with the gas production data, we confirmed that the inversion results and reservoir classification were both reasonable and credible.     

Study of the interaction between dry granular flows and rigid barriers with an SPH model

This study uses an incompressible smoothed‐particle hydrodynamics model to investigate the interaction between dry granular material flows and rigid barriers. The primary aim is to summarise some practical guidelines for the design of debris‐resisting barriers. The granular materials are modelled as a rigid‐perfectly plastic material where the plastic flow corresponds to the critical state. The coupled continuity equation and momentum equation are solved by a semi‐implicit algorithm. Compared with flows in controlled flume experiments, the model adequately reproduces both the kinetic of the flows and the impact force under various conditions. Then the numerical simulations are used to study the detailed interaction process. It is illustrated quantitatively that the interaction force consists of two parts, ie, the earth pressure force caused by the weight of the soil and a dynamic force caused by the internal deformation (flowing mass on top of a dead zone). For the estimation of impact load, this study suggests that an increased earth pressure coefficient depending on the Froude number should be incorporated into the hydrostatic model.     

湖南娄邵冷城市群结构优化研究

运用分形理论等方法对娄邵冷城市群的结构进行了初步分析,结果表明:娄邵冷城市群等级规模结构尚处于低水平;职能结构仅处于工业化初级向中高级阶段转变的过渡时期,区域产业结构水平不高;湘黔铁路沿线和320、207国道沿线城镇已初步具有城市和经济发展的空间集聚特征,但城镇分布分散,集聚优势微弱,空间网络框架尚不成熟.针对其当前存在的问题,提出了娄邵冷城市群结构优化的基本思路.