Density-dependent separation of dry fine coal in a vibrated fluidized bed

The main purpose of coal separation is to reduce ash, sulfur, mercury and other mineral contaminants in the coal to increase the calorific value and benefit the environment. Dry coal beneficiation has obvious advantages over the wet process although the latter is currently the predominant method in use throughout the world. A vibrated fluidized bed was constructed for separating dry fine coal particles from unwanted gangue particles. An experimental investigation of vibrational energy transmission, and the interaction between vibration and gas flow, was performed. The motivation for these experiments was a theoretical development of the principles involved in forming a dense-media vibrated fluidized bed (DMVFB). The mechanism of bubble breaking by vibration is discussed. A formula for calculating the critical vibration frequency at which bubbles can be efficiently broken and bubble formation restrained is proposed. The experimental results demonstrate that the density of a dense-media vibrated fluidized bed is uniform, with a maximum relative error of 1.68% under optimal technological and operating conditions. The < 6 mm fine coal was efficiently separated with a probable error E value of 0.07 t/m³. A lower limit of separation of 0.5 mm was achieved. The DMVFB separation efficiency is higher than wet jig with E value of 0.11 t/m³.     

紧凑但不拥挤——对紧凑城市理论在我国应用的思考

西方发达国家倡导的紧凑城市理论,在我国提倡集约发展的背景下受到关注。但我国与西方发达国家在城市发展阶段、资源与环境方面存在差异,对于紧凑城市所提倡的高密度理解要有所区别。通过辨识高密度与拥挤的关系,建议我国城市已有建成区采用高密度建设要慎重。认为在密度已经较高的地区,宜通过环境整治,增强宜居性;通过在城市地区构建良好的城市结构,使其整体上达到紧凑而不拥挤。     

An Arrangement of Channels and Transceivers in Optical Packet Switching Networks

Based on a media access and control（MAC）protocol,an arrangement of channels and transceivers in optical packet switching dense wavelength division multiplexing（DWDM）networks is proposed in this paper.In order to reduce the cost of nodes,fixed transmitters and receivers are used instead of tunable transmitters and receivers.Two fixed transmitters and many fixed receivers are used in each node in the scheme.The average waiting delay of this scheme is analyzed through mathematics and computer simulation.The result shows that the property of the scheme is almost the same as using tunable transmitter and receiver.Furthermore,if the tuning time of tunable transmitters is taken into account,the performance of the tunable transmitter scheme is poor than this scheme at the average waiting delay and throughput of the network.     

Crowd counting via learning perspective for multi-scale multi-view Web images

Estimating the number of people in Web images still remains a challenging problem owing to the perspective variation, different views, and diverse backgrounds. Existing deep learning models still have difficulties in dealing with scenarios where the size of a person is either extremely large or extremely small. In this paper, we propose a novel perspective-aware architecture to estimate the number of people in a crowd in web images. Specifically, we use a two-stage framework, where we first learn a policy network to infer the perspective of the target scene, which outputs a scale label for the subsequent perspective normalization. Next, given the aligned inputs, we further adjust the scale-specific counting network to regress the final count. Experiments on challenging datasets demonstrate our approach can deal with a large perspective variation and that we have achieved state-of-theart results.     

Using computer vision to simulate the motion of virtual agents

In this paper, we propose a new model to simulate the movement of virtual humans based on trajectories captured automatically from filmed video sequences. These trajectories are grouped into similar classes using an unsupervised clustering algorithm, and an extrapolated velocity field is generated for each class. A physically‐based simulator is then used to animate virtual humans, aiming to reproduce the trajectories fed to the algorithm and at the same time avoiding collisions with other agents. The proposed approach provides an automatic way to reproduce the motion of real people in a virtual environment, allowing the user to change the number of simulated agents while keeping the same goals observed in the filmed video. Copyright © 2007 John Wiley & Sons, Ltd.     

基于2.5维元胞自动机的人群疏散模型

在二维元胞自动机的基础上提出2.5维元胞自动机的新概念.以大型运动场馆为研究对象,研究和建立了基于2.5维元胞自动机的人群疏散网格模型.该模型兼顾考虑了场地客观因素及人员主观因素方面的影响,引入的高程因素对人群疏散情况分析是有效的.最后通过实例论证了提出的2.5维元胞自动机模型对人群疏散仿真效果的实用性及合理性.     

论西铭矿选煤厂合理的洗选工艺

分析了西铭矿选煤厂主要分选工艺、粗煤泥分选、细煤泥分选、选前脱泥与不脱泥流程、有压与无压重介旋流器的选择.该矿选煤厂采用大直径重介旋流器作为主要分选设备,采用螺旋分选机处理粗煤泥,细煤泥不分选直接落地销售.整个工艺系统在提高洗选效率、保证产品质量,提高选煤厂经济效益等方面成效显著.     

重介旋流器的研究现状及发展前景

针对国内外重介旋流器的发展状况,介绍了重介旋流器的发展背景和应用现状.结合重介旋流器的分选原理,介绍了3GDMC 无压三产品重介旋流器的选煤过程.根据屯兰矿选煤厂的技术改造效益,论述了重介旋流器选煤的优越性,并展望了重介旋流器的发展前景.     

Prediction of human crowd pressures

Published data on accidents in human crowds that occurred over the past decade show that one of the fatal consequences of crowding was asphyxia, that is by crushing. Here a study was made of our ability to predict human crowd pressures at barriers and thereby be able to take preventive action before crushing causes injury. Utilizing the standard forward-backward autoregressive modeling techniques for spectral analysis of a measured signal, predictions of pressures generated by very high densities of pedestrians have been formulated. The study suggests that several minutes are available for corrective action to be taken to avoid an accident involving crushing of pedestrians.