红层与煤系复合结构覆岩采动破坏分析及其应用

许多矿区煤层采动影响范围内的覆岩层由红层和煤层共同构成。本文研究了山东省太平煤矿东区二叠系 3号煤层覆岩破坏和防水煤柱留设的问题 ,在对上覆第四系水文地质条件分析的基础上 ,对红层和煤系复合结构覆岩的工程地质特征和破坏状况进行了分析 ,确定了合理的防水煤岩柱高度 ,并经过开采验证 ,避免了水害发生.     

Experimental study of the creation of a fire‐rod II: Emissive probe measurements

A planar electrode (collector) is immersed into a weakly magnetized discharge plasma column. Positive voltage steps are applied to the collector and time resolved measurements of the plasma response are performed by emissive probes using standard boxcar technique. On the emissive probe characteristics an interesting phenomenon is observed: a few μs after the application of the voltage step to the collector (time depends on the distance between the collector and the probe), the emissive probe starts to collect additional positive current in the potential region between plasma potentials of the high and low potential plasma. This phenomenon is investigated experimentally. We give a possible qualitative explanation that additional positive current collection is due to a combination of an interaction between the collector and the probe and space charge effects of positive ions around the probe.     

高密实含能颗粒床对流燃烧过程的实验研究

高密实含能颗粒床对流燃烧过程的实验研究张小兵，金志明，袁亚雄（南京理工大学动力学院南京２１００９４）关键词对流燃烧；含能颗粒床；实验研究１引言在高能燃料火箭推进系统和粒状火药炮膛内，火药颗粒燃烧的热量传递机理是强迫对流。当装填密度高到一定程度时，火焰...     

Nonlinear generation of sheared flows and zonal magnetic fields by electron whistlers in plasmas

The nonlinear generation of shear field and flow in whistler waves is considered. It is shown that a coherent parametric process leads to modulational instability of four waves whistler interaction. Growth rates for the flow/field are compared with published simulation results.     

Effect of Second Nonthermal Ion on the Characteristics of Dust Acoustic Solitary Waves in a Magnetized Dusty Plasma with Variable Dust Charge

The nonlinear dust acoustic solitary waves in a magnetized dusty plasma with nonthermal ions and variable dust electric charge is studied analytically. Using reductive perturbation method the Zakharov‐Kuznetsov (ZK) equation is derived and effect of nonthermal coefficient, external magnetic field, and variable dust electric charge on the amplitude and width of soliton in dusty plasma is investigated. With increasing the rate of dust charge variation with respect of plasma potential, the amplitude of generated solitary waves in magnetized dusty plasma increases to a constant magnitude while its width decreases. Increasing the nonthermal ions coefficient leads to a noticeable decrease in the amplitude of solitons while the width of soliton increases. The amplitude of generated solitary waves in such a dusty plasma is independent of applied external magnetic field but we will have more localized solitons with increasing the external magnetic field strength. It is found that solitons are strongly influenced by the direction of external magnetic field. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Two and three dimensional modeling of fluidized bed with multiple jets in a DEM-CFD framework

Fluidized beds with multiple jets have widespread industrial applications. The objective of this paper is to investigate the jet interactions and hydrodynamics of a fluidized bed with multiple jets. Discrete element modeling coupled with in-house CFD code GenlDLEST has been used to simulate a bed with nine jets. The results are compared with published experiments. Mono dispersed particles of size 550 ~m are used with 1.4 times the minimum fluidization velocity of the particles. Both two and three dimensional computations have been performed. To the best of our knowledge, the results presented in this paper are the first full 3D simulations of a fluidized bed performed with multiple jets. Discrepancies between the experiment and simulations are discussed in the context of the dimensionality of the simulations. The 2D solid fraction profile compares well with the experiment close to the distributor plate. At higher heights, the 2D simulation over-predicts the solid fraction profiles near the walls. The 3D simulation on the other hand is better able to capture the solid fraction profile higher up in the bed compared to that near the distributor plate. Similarly, the normalized particle velocities and the particle fluxes compare well with the experiment closer to the distributor plate for the 2D simulation and the freeboard for the 3D simulation, respectively. A lower expanded bed height is predicted in the 2D simulation compared to the 3D simulation and the experiment. The results obtained from DEM computations show that a 2D simulation can be used to capture essential jetting trends near the distributor plate regions, whereas a full scale 3D simulation is needed to capture the bubbles near the freeboard regions. These serve as validations for the experiment and help us understand the complex jet interaction and solid circulation patterns in a multiple jet fluidized bed system.     

Particuology and climate change

The global concern over the greenhouse gas emissions and its effect on global warming and climate change has focused attention on the necessity of carbon dioxide capture and sequestration. There are many processes proposed to capture carbon either before or after combustion and these processes invariably involve investigation and application of traditional particuology. The solids employed are of different sizes, densities, morphologies, and strengths. Their handling, transportation, recirculation, and reactor applications are the essence of ＇particuology＇. Particuology can play an important and vital role in achieving cost-effective removal of carbon and minimize emissions of greenhouse gases. In this paper, the existing and developing carbon capture processes are briefly reviewed and the opportunities for application of particuology are identified. The review was not intended to be exhaustive. It is only in sufficient detail to make connection between particuology and climate change. For immediate and future challenges of reducing global warming and carbon capture and sequestration, innovative reactor design and application of parricuology is imperative. Expertise and innovation in particuology can greatly enhance the speed of development of those technologies and help to achieve cost-effective implementation. Particuology is indeed intimately related to the climate change and global warming.     

强激光在磁化等离子体中的调制不稳定性

采用洛伦兹变换推导出左旋椭圆偏振强激光在磁化等离子体中的非线性色散关系,根据Karpman方法推导出激光场包络的非线性控制方程,分析了在磁化等离子体中左旋椭圆偏振激光的调制不稳定性,得到了调制不稳定的时间增长率。分析结果表明,磁化等离子体中自调制不稳定的极大增长率较非磁化情况明显减小,且在激光等离子体临界面附近处调制不稳定性的时间增长率显著增大。     

Nonlinear excitation and stability analysis of ion-acoustic waves in a magnetized quantum plasma with exchange-correlation effects of degenerate electrons

The nonlinear ion-acoustic wave excitation and its stability analysis are investigated in a magnetized quantum plasma with exchange-correlation and Bohm diffraction effects of degenerate electrons in the model. Using reductive perturbation technique, the Zakharov-Kuznetsov (ZK) equation is derived for two dimensional propagation of ion-acoustic wave in a magnetized quantum plasma. It is found that the phase speed, amplitude and width of the nonlinear ion-acoustic wave structures are affected in the presence of exchange-correlation potential in the model. The stability analysis of the 2D ion-acoustic wave pulse is also presented. It is found that growth rate of the first and second order instabilities of 2D ion acoustic wave soliton is enhanced with the inclusion of exchange-correlation potential effect in the model.     

Modified KdV equation for magnetized Rossby waves in a zonal flow of the ionospheric E-layer

Nonlinear interaction of magnetized Rossby waves with sheared zonal flow in the Earth's ionospheric E-layer is investigated. It is shown that in case of weak nonlinearity 2D Charney vorticity equation can be reduced to the one-dimensional modified KdV equation.