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Air flow exploration of abrasive feed tube

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Acta Mechanica Sinica 2009年第6期25卷 761-768页

作者： Shijin Zhang Xiaohong Li Yilei Gu college of Resources and Environmental science,Chongqing university, 400044 Chongqing,{3. college of Resources and Environmental science Chongqing University 400044 Chongqing China

An abrasive water-jet cutting process is one in which water pressure is raised to a very high pressure and forced through a very small orifice to form a very thin high speed jet beam. This thin jet beam is then directed through a chamber and then fed into a secondary nozzle, or mixing tube. During this process, a vacuum is generated in the cham- ber, and garnet abrasives and air are pulled into the chamber, through an abrasive feed tube, and mixes with this high speed stream of water. Because of the restrictions introduced by the abrasive feed tube geometry, a vacuum gradient is generated along the tube. Although this phenomenon has been recog- nized and utilized as a way to monitor nozzle condition and abrasive flowing conditions, yet, until now, conditions inside the abrasive feed line have not been completely understood. A possible reason is that conditions inside the abrasive feed line are complicated. Not only compressible flow but also multi- phase, multi-component flow has been involved in inside of abrasive feed tube. This paper explored various aspects of the vacuum creation process in both the mixing chamber and the abrasive feed tube. Based on an experimental exploration, an analytical framework is presented to allow theoretical calculations of vacuum conditions in the abrasive feed tube.

关键词： Abrasive feed tube- Water jet cutting. Vacuum gradient

Stress distribution rule of roadway affected by overhead mining in gently inclined coal seams group

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中国有色金属学会会刊：英文版 2011年第S3期21卷 529-535页

作者： KANG Qin-rong1, 2, TANG Jian-xin1, 2, HU Hai1, 2, ZHANG Wei-zhong1, 3.1. college of Resource and Environmental sciences, Chongqing university, Chongqing 40003.,{3. 2. State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing university, Chongqing 40003.,{3. 3. School of Safety science and Administration, Zhongnan university of Economics and Law, Wuhan 43.074,{3. [a] college of Resource and Environmental sciences Chongqing University Chongqing 400030 China [b] State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing University Chongqing 400030 China [c] School of Safety science and Administration Zhongnan University of Economics and Law Wuhan 430074 China

In light of the severe deformation and destruction of the district raise tunnel in the mining area at the northern part of the Lubanshan colliery, by the theoretic analysis and numerical simulation, both the mining stress distribution in seams group and the deformation and destruction mechanism of floor district raise were investigated. The results show that, at the maximum vertical distance of 40 m, the abutment stress has an influence on the recovery of 2# and 3. coal seam and 8# coal seam at distance of 3. m. As a result, the recovery of 8# is rather than those of 2# or 3. coal seam, which contributes to the deformation and destruction of the district raise surrounding rock. The major factors affecting the abutment stress include the mining depth, mining height, residual gob space, adjacent working faces and short spacing coal seam recovery.

关键词： coal seams group stress distribution district raise surrounding rock deformation and destruction abutment stress

A Raw Signal Simulator for Bistatic SAR

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Chinese Journal of Aeronautics 2009年第4期22卷 434-443页

作者： Xia Weijie,Zhou Jianjiang college of Information science and Technology,Nanjing university of Aeronautics and Astronautics,Nanjing 210016,{3. [a]college of Information science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

This article proposes a new efficient raw signal simulator for the bistatic synthetic aperture radar （SAR） based on 2D fast Fourier transform （FFT） to deal with cases of both ideal trajectory and trajectory deviation. It begins with analyzing the geometric configuration and the range history of the bistatic SAR in side-looking and squint modes of ideal trajectory as well as trajectory deviation. Then a detailed and mathematical study is conducted on the equivalence relation of bistatic-to-monostatic applications （BTMA） in the case of ideal trajectory and trajectory deviation. Also a set of formulas are derived for the equivalence relation between bistatic SAR and monostatic SAR on some reasonable assumptions. Therefore, the application of the simulation method based on the 2D FFT for the monostatic SAR can be extended to the case of bistatic SAR. Finally, the simulation results prove the validity of this method. By comparing the efficiency of the proposed method with that of the time domain method, it is shown that the former is a few orders of magnitude higher.

关键词： bistatic synthetic aperture radar raw signal simulation fast Fourier transform

Lattice dynamical simulation of methane hydrate

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Journal of Natural Gas Chemistry 2010年第1期19卷 43-46页

作者： Lin Wang, Shunle Dong Physics Department, college of Information science and Engineering, Ocean university of{3., Qingdao 266100, Shandong,{3. [a] Physics Department College of Information Science and Engineering Ocean University of China Qingdao 266100 Shandong China

INS （Inelastic Neutron Scattering） spectrum of methane hydrate was measured on MARI （a direct-geometry chopper spectrometer） at Ruther-ford Appleton Laboratory, UK. Compared with ice Ih, it is found that the whole spectrum of methane hydrate moves toward high-energy by about 1.5 meV. Using lattice dynamical （LD） technique, computer simulations of methane hydrate were carried out. In the simulations, four potential models （BE TIP3., TIP4P, MCY） were employed to calculate the phonon density of states （PDOS）. Comparing the calculated PDOS spectrum with the experimental spectrum, it is found that BF, TIP4P, and TIP3. potential lattices give out well-separated translational and librational bands while MCY potential lattice is unstable to do so and this model is not suitable to describe hydrate system.

关键词： methane hydrate inelastic neutron scattering lattice dynamical simulation

Luminosity-peak energy relation in the decay phases of gamma-ray burst pulses

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science china(Physics,Mechanics & Astronomy) 2010年第1期53卷 163-170页

作者： LU RuiJing & LIANG EnWei Physical science & Technology college, Guangxi university, Nanning 53.004,{3. 1. Physical science & Technology college Guangxi University Nanning 530004 China

Using time-resolved spectral data for a sample of 3. pulses in 27 bright GRBs detected with CGRO/BATSE, we investigate the luminosity-peak energy relation (L-E p relation) in the decay phases of these pulses. A tight L-E p relation is found for most of the pulses, but its power law index is various among pulses, which is normally distributed at 1.84±0.60(1σ) for the pulses in our sample, roughly consistent with the L-E p relation within a GRB and the isotropic gamma-ray energy-E p relation among GRBs. The large scatter of the power law index cannot be explained with both the statistical or observational effects and it may be an intrinsic feature, indicating that no universal L-E p relation would be expected among GRBs/pulses. This may strongly weaken the cosmological use of this relation.

关键词： gamma ray bursts observations statistical luminosity-peak energy relation

Location-Information-Based Multiple-Landmark Multicast Protocol for Ad Hoc Networks

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International Journal of Systems and Control

International Journal of Systems and Control 2008年第2期 134-138页

作者： YUAN Ping,JIANG Zhijun college of Information science & Engineering, northeastern university, Shenyang {3.,china

A typical scenario in Mobile Ad Hoc networks(MANETs) consists of nodes having functional and motorial affinities(e.g., groups in the same exploration). In order to achieve scalability for such a network having a large scale, we propose, in this paper, a novel "Location-Information-Based Multiple-Landmark Multicast Protocol (MLMP). This protocol is an "implicit" , flexible hierarchical routing scheme following the traditional hierarchical method for handling scalability in large, wired networks. MLMP features dynamic distributed election of multiple landmarks with scope constraints and multicast packet forwarding using Location-Information-Based protocol. This protocol is very suit for large scale Ad hoc networks. Simulation result shows the good performance properties of MLMP in general ad hoc network infrastructures.

关键词： Hierarchical routing Multicast Ad Hoc Networks

A new generation of plastic optical fibers and its functional exploiting

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science china(Technological sciences) 2008年第12期51卷 2197-2207页

作者： YU RongJin & ZHANG Bing college of Information science and Engineering,Yanshan university,Qinhuangdao 066004,{3. college of Information science and Engineering Yanshan University Qinhuangdao 066004 China

A major problem of plastic optical fibers(POFs) is large transmission loss in comparison with silica *** adopting a new optical fiber structure,hollow-core Bragg fiber with cobweb-structured cladding,which can suppress the absorption losses of constituent materials by a factor of about 104―106,the problem of POFs with large losses is solved *** the advantage of flexibility and easy bending,the POFs with this structure can guide light with low transmission loss for information and energy in the wavelength range of visible light to terahertz(THz) wave(0.4―1000 μm).This new generation of POFs will find many applications.

关键词： plastic optical fiber hollow-core Bragg fiber cobweb-structured cladding visible light infrared light terahertz wave circular-polarization single-mode

Finite automata based on quantum logic and monadic second-order quantum logic

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science china(Information sciences) 2010年第1期53卷 101-114页

作者： LI YongMing college of Computer science, Shaanxi Normal university, Xi’an 710062,{3. 1. college of Computer science Shaanxi Normal University Xi’an 710062 China

We introduce monadic second-order quantum logic and prove that the behaviors of finite automata based on quantum logic are precisely the quantum languages definable with sentences of our monadic secondorder quantum logic. This generalizes Büchi’s and Elgot’s fundamental theorems to quantum logic setting. We also consider first-order quantum logic and show that star-free quantum languages and aperiodic quantum languages introduced here coincide with the first-order quantum definable ones. This generalizes Schützenberger’s fundamental theorems to quantum logic setting. The determinazation of finite automata based on quantum logic is studied by introducing the generalized subset construction method. Then the Kleene theorem in the frame of quantum logic is presented here.

关键词： quantum logic finite automaton monadic second quantum logic quantum language quantum computation Kleene theorem

Thermal Conductivity and Heat Transfer Coefficient of Concrete

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Journal of Wuhan university of Technology(Materials science) 2011年第4期26卷 791-796页

作者：郭利霞 North china university of Water Resources and Electric Power

A very simple model for predicting thermal conductivity based on its definiensis was presented. The thermal conductivity obtained using the model provided a good coincidence to the investigations performed by other authors. The heat transfer coefficient was determined by inverse analysis using the temperature measurements. From experimental results, it is noted that heat transfer coefficient increases with the increase of wind velocity and relative humidity, a prediction equation on heat transfer coefficient about wind velocity and relative humidity is given.

关键词： thermal conductivity heat transfer coefficient relative humidity wind velocity