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Mechanical criterion for coal and gas outburst:a perspective from multiphysics coupling

International Journal of coal Science & Technology 2021年第6期8卷 1423-1435页

作者： Ting Liu Baiquan Lin Xuehai Fu ang Liu School of Safety Engineering China University of Mining&TechnologyXuzhou 221116China Key Laboratory of cBM Resources and Dynamic Accumulation Process China University of Mining&TechnologyXuzhou 221008China Department of Energy and Mineral Engineering G3 Center and EMS Energy InstituteThe Pennsylvania State UniversityUniversity ParkPAUSA

Although a series of hypotheses have been proposed,the mechanism underlying coal and gas outburst remains *** the low-index outbursts encountered in mining practice,we attempt to explore this mechanism using a multiphysics coupling model considering the effects of coal strength and gas mass transfer on *** on force analysis of coal ahead of the heading face,a risk identification index c_(m)and a critical criterion(c_(m)≥1)of coal instability are *** to this criterion,the driving force of an outburst consists of stress and gas pressure gradients along the heading direction of the roadway,whereas resistance depends on the shear and tensile strengths of the *** results show that outburst risk decreases slightly,followed by a rapid increase,with increasing vertical stress,whereas it decreases with increasing coal strength and increases with gas pressure *** the response surface method,a coupled multi-factor model for the risk identification index is *** results indicate strong interactions among the controlling ***,the critical values of the factors corresponding to outburst change depending on the environment of the coal seams,rather than being *** the buried depth of a coal seam increases,the critical values of gas pressure and coal strength decrease slightly,followed by a rapid *** to its controlling factors,outburst can be divided into stress-dominated,coal-strength-dominated,gas-pressure-dominated,and multi-factor compound *** on this classification,a classified control method is proposed to enable more targeted outburst prevention.

关键词： coal and gas outburst critical criterion Multiphysics coupling Response surface method

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Synthesis of self-assembled nanorod vanadium oxide bundles by sonochemical treatment

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Journal of Natural Gas chemistry 2009年第3期18卷 312-318页

作者： Y.H.Taufiq-Yap Y.c.Wong z.zainal M.z.Hussein centre of Excellence for catalysis Science and Technology Faculty of ScienceUniversiti Putra Malaysia Department of chemistry Faculty of ScienceUniversiti Putra Malaysia

Self-assembled nanorod of vanadium oxide bundles were synthesized by treating bulk V2O5 with high intensity sonochemical technique. The synthesized materials were characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM）, transmission electron microscope （TEM） and temperature-programmed reduction （TPR） in H2. catalytic behaviour of the materials over anaerobic n-butane oxidation was studied through temperature-programmed reaction （TPRn）. catalytic evaluation of the sonochemical treated V2O5 products was also studied on microreactor. XRD patterns of all the vanadium samples were perfectly indexed to V2O5. The morphologies of the nanorod vanadium oxides as shown in SEM and TEM depended on the duration of the ultrasound irradiation. Prolonging the ultrasound irradiation duration resulted in materials with uniform, well defined shapes and surface structures and smaller size of nanorod vanadium oxide bundles. H2-TPR profiles showed that larger amount of oxygen species were removed from the nanorod V2O5 compared to the bulk. Furthermore, the nanorod vanadium oxide bundles, which were produced after 90, 120 and 180 min of sonochemical treatment, showed an additional reduction peak at lower temperature （-850 K）, suggesting the presence of some highly active oxygen species. TPRn in n-butane/He over these materials showed that the nanorod V2O5 with highly active oxygen species showed markedly higher activity than the bulk material, which was further proven by catalytic oxidation of n-butane.

关键词： nanorod vanadium oxide sonochemical treatment butane oxidation

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charge self-trapping in two strand biomolecules:Adiabatic polaron approach

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chinese Physics B 2023年第1期32卷 253-263页

作者： D chevizovich S zdravković A V chizhov z Ivić University of Belgrade Vinča Institute of Nuclear SciencesP.O.Box 522Belgrade 11001Serbia Joint Institute for Nuclear Research Laboratory for Radiation BiologyDubna 141980Russia Dubna State University Dubna 141980Russia Department of Physics University of CreteP.O.Box 2208Heraklion 71003Greece National University of Science and Technology MISiS Leninsky prosp.4Moscow 119049Russia

We investigate the properties of the excess charge(electron, hole) introduced into a two-strand biomolecule. We consider the possibility that the stable soliton excitation can be formed due to interaction of excess charge with the phonon subsystem. The influence of overlap of the molecular orbitals between adjacent structure elements of the macromolecular chain on the soliton properties is discussed. Special attention is paid to the influence of the overlapping of the molecular orbitals between structure elements placed on the different chains. Using the literature values of the basic energy parameters of the two-chain biomolecular structures, possible types of soliton solutions are discussed.

关键词： charge self-trapping adiabatic polaron soliton two-stranded biomolecules

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Non-existence of Shilnikov chaos in continuous-time systems

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Applied Mathematics and Mechanics(English Edition) 2012年第3期33卷 371-374页

作者： z.ELHADJ J.c.SPROTT Department of Mathematics University of T'ebessaT'ebessa 12002Algeria Department of Physics University of Wisconsin-MadisonWI 53706USA

In this paper, a non-existence condition for homoclinic and heteroclinic orbits in n-dimensional, continuous-time, and smooth systems is obtained, Based on this result and an elementary example, it can be conjectured that there is a fourth kind of chaos in polynomial ordinary differential equation （ODE） systems characterized by the nonexistence of homoclinic and heteroclinic orbits.

关键词： homoclinic chaos heteroclinic chaos non-existence of Shilnikov chaos

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Identification of Hammerstein-Wiener model with discontinuous input nonlinearity

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Science china(Information Sciences) 2023年第12期66卷 33-47页

作者： A.BROURI F.z.EL MANSOURI F.z.cHAOUI c.ABDELAALI F.GIRI ENSAM Moulay Ismail University ENSAM University Mohammed V Normandie Universite

This paper deals with the identification of Hammerstein-Wiener models with an irregular function in the input block. These models comprise a set of linear segments. The linear time invariant(LTI) block may be parametric or nonparametric. The nonlinearity of the output can be any continuous function of arbitrary shape; it is not necessarily assumed to be invertible. Subsequently, sine inputs will be used to identify the system parameters. First, the output nonlinearity is determined by filtering the system output and varying the phase of a given reference sine signal; second, the parameters of the linear block can be determined for any frequency; and finally, the input nonlinearity can be obtained by changing the offset and amplitude of the input sine signal.

关键词： nonlinear systems nonlinear systems identification Hammerstein-Wiener models discontinuous nonlinearities hard nonlinearities

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Influence of plasma condition on carbon nanotube growth by rf-PEcVD

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Nano-Micro Letters 2010年第1期2卷 37-41页

作者： Y.H.Man z.c.Li z.J.z.ang Advanced Materials Laboratory Department of Materials Science and Engineering Tsinghua University

carbon nanotubes(cNTs)have been synthesized from Ar-cH_4 mixtures using rf-plasma enhanced chemical vapor deposition(rf-PEcVD)at *** gases such as H_2 and NH_3 were found unnecessary for carbon nanotube formation compared to thermal *** relationship between the growth of cNTs and the plasma condition in PEcVD has been investigated by in situ self bias *** conditions were controlled by changing the interelectrode distance,rf power and the applied substrate negative *** increasing the interelectrode distance and rf power,the spatial density of cNTs was on a rise as a result of the increase in ions density and self *** the applied substrate negative bias increased,the spatial density of cNTs decreased possibly due to the positive ions over bombarding effect.

关键词： carbon nanotube Plasma enhanced cVD Plasma condition

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Wavelet-Based Mixed-Resolution coding Approach Incorporating with SPT for the Stereo Image

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Journal of Systems Engineering and Electronics 2001年第3期12卷 39-44页

作者： Xu, c. z.ang, z. An, P. communication School Shanghai University Shanghai 200072 China

With the advances of display technology, three-dimensional(3-D) imaging systems are becoming increasingly popular. One way of stimulating 3-D perception is to use stereo pairs, a pair of images of the same scene acquired from different perspectives. Since there is an inherent redundancy between the images of a stereo pairs, data compression algorithms should be employed to represent stereo pairs efficiently. The proposed techniques generally use block-based disparity compensation. In order to get the higher compression ratio, this paper employs the wavelet-based mixed-resolution coding technique to incorporate with SPT-based disparity-compensation to compress the stereo image data. The mixed-resolution coding is a perceptually justified technique that is achieved by presenting one eye with a low-resolution image and the other with a high-resolution image. Psychophysical experiments show that the stereo image pairs with one high-resolution image and one low-resolution image provide almost the same stereo depth to that of a stereo image with two high-resolution images. By combining the mixed-resolution coding and SPT-based disparity-compensation techniques, one reference (left) high-resolution image can be compressed by a hierarchical wavelet transform followed by vector quantization and Huffman encoder. After two level wavelet decompositions, for the low-resolution right image and low-resolution left image, subspace projection technique using the fixed block size disparity compensation estimation is used. At the decoder, the low-resolution right subimage is estimated using the disparity from the low-resolution left subimage. A full-size reconstruction is obtained by upsampling a factor of 4 and reconstructing with the synthesis low pass filter. Finally, experimental results are presented, which show that our scheme achieves a PSNR gain (about 0.92dB) as compared to the current block-based disparity compensation coding techniques.

关键词： Data reduction Decoding Image coding Image compression Image reconstruction Imaging techniques Motion compensation Motion estimation Optical resolving power Projection systems Stereo vision Wavelet transforms

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Blue light is more essential than red light for maintaining the activities of photosystem Ⅱ and Ⅰ and photosynthetic electron transport capacity in cucumber leaves

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Journal of Integrative Agriculture 2016年第1期15卷 87-100页

作者： MIAO Yan-xiu W ang Xiao-zhuo G AO Li-hong c HEN Qing-yun QU Mei Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable crops College of Agriculture and Biotechnology China Agricultural UniversityBeijing 100193P.R.China

Blue and red lights differently regulate leaf photosynthesis. Previous studies indicated that plants under blue light generally exhibit better photosynthetic characteristics than those under red light. However, the regulation mechanism of related photosynthesis characteristics remains largely unclear. Here, four light qualities treatments （300 μmol m-2 s-1） including white fluorescent light （FL）, blue monochromatic light （B, 440 nm）, red monochromatic light （R, 660 nm）, and a combination of red and blue light （RB, R：B=8：1） were carried out to investigate their effects on the activity of photosystem II （PSII） and photosystem I （PSI）, and photosynthetic electron transport capacity in the leaves of cucumber （cucumis sativus L.） seedlings. The results showed that compared to the FL treatment, the R treatment significantly limited electron transport rate in PSII （ETR11） and in PSI （ETR1） by 79.4 and 66.3%, respectively, increased non-light induced non-photochemical quenching in PSII （q^No） and limitation of donor side in PSI （φND） and reduced most JIP-test parameters, suggesting that the R treatment induced suboptimal activity of photosystems and inhibited electron transport from PSII donor side up to PSI. However, these suppressions were effectively alleviated by blue light addition （RB）. compared with the R treatment, the RB treatment significantly increased ETR, and ETR1 by 176.9 and 127.0%, respectively, promoted photosystems activity and enhanced linear electron transport by elevating electron transport from QA to PSI. The B treatment plants exhibited normal photosystems activity and photosynthetic electron transport capacity similar to that of the FL treatment. It was concluded that blue light is more essential than red light for normal photosynthesis by mediating photosystems activity and photosynthetic electron transport capacity.

关键词： cucumber photosystem II photosystem I electron transport

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Numerical simulation of the three-dimensional flow-path in a ram-rotor

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航空动力学报 2010年第6期25卷 1358-1365页

作者： HAN Ji-ang zHONG Jing-jun YAN Hong-ming Marine Engineering college Dalian Maritime UniversityDalian 116026China School of Energy Science and Engineering Harbin institute of TechnologyHarbin 150001China

A kind of three-dimensional flow-path of the ram-rotor was designed in this paper according to the design method of the typical supersonic intake of aircraft and missiles,especially the design method of the compression ramp,the throat and the subsonic *** design Mach number of the flow-path was based on the averaged relative Mach number,regardless of the change of incoming Mach number along radial direction of the ***,the flowfield of the designed flow-path was simulated numerically with computational fluid dynamics software at design *** purpose of simulation was to obtain the details of the flowfield,including the structure of the shock wave system,position of flow separation zone,and so *** performance of the ram-rotor was also *** numerical results show the structure of the shock wave system in the flow-path is similar to that in the supersonic *** improve the overall performance of the ram-rotor,the reasonable compromise between the total pressure ratio and the isentropic adiabatic efficiency should be *** structure optimization of the flow-path and the configuration of the shock wave system have great influence on the performance of the ram-rotor.

关键词： ram-rotor flow-path supersonic intake numerical simulation design point

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NEW VIEW ABOUT BAINITIc TRANSFORMATION IN STEEL

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Acta Metallurgica Sinica(English Letters) 1999年第3期12卷 229-234页

作者： Liu, c.c. Liu, z. chen, G.X. Tsinghua Univ Beijing China

The bainitic transformation was analyzed according to the factors such as morphology, crystallography, mechanical property of bainite and transformation kinetics. It was found that the bainitic transformation is controlled by displacive mechanism and self-tempering of displacive microstructure, i.e. bainite is the product of such procedure during which undercooled austenite first transforms into one certain displacive microstructure by displacive mechanism and then this microstructure experiences self-tempering. With this idea, several questions that can not be illustrated only by displacive transformation mechanism can be explained successfully.

关键词： Bainite Morphology Steel

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