To solve the problem of water loss during mining of shallow, buried coal seams, we have first analyzed the mechanism and suitability of solid-liquid coupling, i.e., we used the FLUID-MECHANICS system of 3-Dimensional ...To solve the problem of water loss during mining of shallow, buried coal seams, we have first analyzed the mechanism and suitability of solid-liquid coupling, i.e., we used the FLUID-MECHANICS system of 3-Dimensional Distinct Element Code (3DEC) in simulating dynamic water crannies in overlying strata, under mining conditions of a large longwall coalface. Next the dynamic initiation of a water cranny, its propagation and close phases were studied with 3DEC, along with the overlying strata breakage and recombination as the mining space of the shallow, buried coal seam increased. Combined with the change in the stress and displacement fields, the distribution features of the mining cranny were systematically studied. The effect of regularities and their effective measures of local filling and mine slicing technology in controlling mine crannies were investigated and the potential danger areas of water loss identified. Our results can be applied to decrease water loss during the exploitation of shallow, buried coal seams with a thin bedrock. The results also prove that 3DEC is a credible numerical analytical method to predict initiations of dynamic water crannies, their propagation, their closure phases and other concomitant hazards.展开更多
Sloshing of liquid can increase the dynamic pressure on the storage sidewalls and bottom in tanker ships and LNG careers. Different geometric shapes were suggested for storage tank to minimize the sloshing pressure on...Sloshing of liquid can increase the dynamic pressure on the storage sidewalls and bottom in tanker ships and LNG careers. Different geometric shapes were suggested for storage tank to minimize the sloshing pressure on tank perimeter. In this research, a numerical code was developed to model liquid sloshing in a rectangular partially filled tank. Assuming the fluid to be inviscid, Laplace equation and nonlinear free surface boundary conditions are solved using coupled FEM-BEM. The code performance for sloshing modeling is validated against available data. To minimize the sloshing pressure on tank perimeter, rectangular tanks with specific volumes and different aspect ratios were investigated and the best aspect ratios were suggested. The results showed that the rectangular tank with suggested aspect ratios, not only has a maximum surrounded tank volume to the constant available volume, but also reduces the sloshing pressure efficiently.展开更多
The coupled effect of viscosity enhancing admixtures(VEA)and superplasticizer(SP)on the rheological behavior of cement paste was investigated in this work.Two types of VEAs,including hydroxypropyl methylcellulose(HPMC...The coupled effect of viscosity enhancing admixtures(VEA)and superplasticizer(SP)on the rheological behavior of cement paste was investigated in this work.Two types of VEAs,including hydroxypropyl methylcellulose(HPMC)and Welan gum,and two types of SPs,i.e.polycarboxylate(PCA)and polynaphthalenesulfonate(PNS)were used as admixtures for cement paste.Rheological curves of cement paste and simulated pore solution containing VEA and SP were tested.Simulated pore solution test results show that molecules of different SPs may generate different effects on the viscosity of VEA solutions.Hershel-Bulkley(H-B)model was used to fit rheological curve of cement paste.Strong interaction between PNS and HPMC was observed in this work.展开更多
A new solar coupling regeneration system is proposed in order to improve the reliability of solar desiccant regeneration system.The new system makes comprehensively use of the solar energy and can also be appropriate ...A new solar coupling regeneration system is proposed in order to improve the reliability of solar desiccant regeneration system.The new system makes comprehensively use of the solar energy and can also be appropriate for energy-storage in a night operation mode when the electric power supply is at its valley.Comparison of the performance of the new system,the solar thermal regeneration system and the solar electrodialysis regeneration system are made and the influential factors of the performance of the new system are investigated.The results reveal that the new system will be more energy efficient than the solar thermal regeneration system and the solar electrodialysis regeneration system.展开更多
This study investigated the adsorption ability of ZCHC （zeolite/chitosan hybrid composite） as adsorbent for chromium （Cr（Ⅵ））, ZCHC was prepared with sol-gel method by mixing zeolite and chitosan. Adsorption exp...This study investigated the adsorption ability of ZCHC （zeolite/chitosan hybrid composite） as adsorbent for chromium （Cr（Ⅵ））, ZCHC was prepared with sol-gel method by mixing zeolite and chitosan. Adsorption experiment from aqueous solutions containing known amount of Cr（Ⅵ） using zeolite, chitosan and ZCHC was explored to evaluate the efficiency of ZCHC as adsorbent for Cr in a batch system. The amount of Cr（Ⅵ） adsorbed at different pH values, initial concentrations, adsorbent dosages, and contact times were determined by ICP-AES （inductively coupled plasma-atomic emission spectrometry） in order to determine the optimum conditions for Cr（Ⅵ） adsorption. Furthermore, the adsorption mechanism of Cr（Ⅵ） by zeolite, chitosan and ZCHC was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained. In addition, the rates of adsorption were found to conform to pseudo-second order kinetics.展开更多
基金Projects 50374065, 50490273, 50474068 supported by the National Natural Science Foundation of ChinaNCET-05-0480 by the New Century Excellent Talentsin University+1 种基金07KF09 by the 2007 Research Fund of the State Key Laboratory of Coal Resources and Mine SafetyCUMT and 2005B002 by the Scientific Re-search Foundation of China University of Mining & Technology
文摘To solve the problem of water loss during mining of shallow, buried coal seams, we have first analyzed the mechanism and suitability of solid-liquid coupling, i.e., we used the FLUID-MECHANICS system of 3-Dimensional Distinct Element Code (3DEC) in simulating dynamic water crannies in overlying strata, under mining conditions of a large longwall coalface. Next the dynamic initiation of a water cranny, its propagation and close phases were studied with 3DEC, along with the overlying strata breakage and recombination as the mining space of the shallow, buried coal seam increased. Combined with the change in the stress and displacement fields, the distribution features of the mining cranny were systematically studied. The effect of regularities and their effective measures of local filling and mine slicing technology in controlling mine crannies were investigated and the potential danger areas of water loss identified. Our results can be applied to decrease water loss during the exploitation of shallow, buried coal seams with a thin bedrock. The results also prove that 3DEC is a credible numerical analytical method to predict initiations of dynamic water crannies, their propagation, their closure phases and other concomitant hazards.
文摘Sloshing of liquid can increase the dynamic pressure on the storage sidewalls and bottom in tanker ships and LNG careers. Different geometric shapes were suggested for storage tank to minimize the sloshing pressure on tank perimeter. In this research, a numerical code was developed to model liquid sloshing in a rectangular partially filled tank. Assuming the fluid to be inviscid, Laplace equation and nonlinear free surface boundary conditions are solved using coupled FEM-BEM. The code performance for sloshing modeling is validated against available data. To minimize the sloshing pressure on tank perimeter, rectangular tanks with specific volumes and different aspect ratios were investigated and the best aspect ratios were suggested. The results showed that the rectangular tank with suggested aspect ratios, not only has a maximum surrounded tank volume to the constant available volume, but also reduces the sloshing pressure efficiently.
基金Project(2017YFB0310101)supported by National High Technology Research and Development Program of ChinaProject(51778269)supported by the National Natural Science Foundation of China
文摘The coupled effect of viscosity enhancing admixtures(VEA)and superplasticizer(SP)on the rheological behavior of cement paste was investigated in this work.Two types of VEAs,including hydroxypropyl methylcellulose(HPMC)and Welan gum,and two types of SPs,i.e.polycarboxylate(PCA)and polynaphthalenesulfonate(PNS)were used as admixtures for cement paste.Rheological curves of cement paste and simulated pore solution containing VEA and SP were tested.Simulated pore solution test results show that molecules of different SPs may generate different effects on the viscosity of VEA solutions.Hershel-Bulkley(H-B)model was used to fit rheological curve of cement paste.Strong interaction between PNS and HPMC was observed in this work.
基金Project(51036001)supported by the National Natural Science Foundation of ChinaProject(2011BAJ03B05)supported by the National Science and Technology Pillar Program during the 12th Five-Year Plan Period of China
文摘A new solar coupling regeneration system is proposed in order to improve the reliability of solar desiccant regeneration system.The new system makes comprehensively use of the solar energy and can also be appropriate for energy-storage in a night operation mode when the electric power supply is at its valley.Comparison of the performance of the new system,the solar thermal regeneration system and the solar electrodialysis regeneration system are made and the influential factors of the performance of the new system are investigated.The results reveal that the new system will be more energy efficient than the solar thermal regeneration system and the solar electrodialysis regeneration system.
文摘This study investigated the adsorption ability of ZCHC （zeolite/chitosan hybrid composite） as adsorbent for chromium （Cr（Ⅵ））, ZCHC was prepared with sol-gel method by mixing zeolite and chitosan. Adsorption experiment from aqueous solutions containing known amount of Cr（Ⅵ） using zeolite, chitosan and ZCHC was explored to evaluate the efficiency of ZCHC as adsorbent for Cr in a batch system. The amount of Cr（Ⅵ） adsorbed at different pH values, initial concentrations, adsorbent dosages, and contact times were determined by ICP-AES （inductively coupled plasma-atomic emission spectrometry） in order to determine the optimum conditions for Cr（Ⅵ） adsorption. Furthermore, the adsorption mechanism of Cr（Ⅵ） by zeolite, chitosan and ZCHC was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained. In addition, the rates of adsorption were found to conform to pseudo-second order kinetics.
