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Spectral Approximation Based on the Pressure Stabilization Mathod for Unsteady Navier-Stokes Equations
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作者 何松年 杨彩萍 《Journal of Mathematical Research and Exposition》 CSCD 1999年第1期25-36,共12页
A Legendre spectral approximation based on the pressure stabilization method for non-periodic, unsteady Navier-Stokes equations is considered. The generalized stability and the convergence are proved strictly. The app... A Legendre spectral approximation based on the pressure stabilization method for non-periodic, unsteady Navier-Stokes equations is considered. The generalized stability and the convergence are proved strictly. The approximation results in this paper are also useful for other non-linear problems. 展开更多
关键词 Legendre spectral approximation pressure stabilization method NavierStokes equation.
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The Effect of Oxygen Partial Pressure during Active Layer Deposition on Bias Stability of a-InGaZnO TFTs 被引量:2
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作者 黄晓明 武辰飞 +3 位作者 陆海 任芳芳 朱洪波 王永进 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第7期171-174,共4页
The effect of oxygen partial pressure (Po2) during the channel layer deposition on bias stability of amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) is investigated. As Po2 increases fr... The effect of oxygen partial pressure (Po2) during the channel layer deposition on bias stability of amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) is investigated. As Po2 increases from 10% to 30%, it is found that the device shows enhanced bias stress stability with significantly reduced threshold voltage drift under positive gate bias stress. Based on the x-ray photoelectron spectroscopy measurement, the concentration of oxygen vacancies (Or) within the a-IGZO layer is suppressed by increasing Po2. Meanwhile, the low-frequency noise analysis indicates that the average trap density near the channel/dielectric interface continuously drops with increasing Po2. Therefore, the improved interface quality with increasing Po2 during the channel layer deposition can be attributed to the reduction of interface Ov-related defects, which agrees with the enhanced bias stress stability of the a-IGZO TFTs. 展开更多
关键词 TFT The Effect of Oxygen Partial pressure during Active Layer Deposition on Bias Stability of a-InGaZnO TFTs
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Limit analysis method for active earth pressure on laggings between stabilizing piles 被引量:2
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作者 WANG Ming-min WU Shu-guang WANG Gui-lin 《Journal of Mountain Science》 SCIE CSCD 2017年第1期196-204,共9页
Stabilizing pile is a kind of earth shoring structure frequently used in slope engineering. When the piles have cantilever segments above the ground,laggings are usually installed to avoid collapse of soil between pil... Stabilizing pile is a kind of earth shoring structure frequently used in slope engineering. When the piles have cantilever segments above the ground,laggings are usually installed to avoid collapse of soil between piles. Evaluating the earth pressure acting on laggings is of great importance in design process.Since laggings are usually less stiff than piles,the lateral pressure on lagging is much closer to active earth pressure. In order to estimate the lateral earth pressure on lagging more accurately,first,a model test of cantilever stabilizing pile and lagging systems was carried out. Then,basing the experimental results a three-dimensional sliding wedge model was established. Last,the calculation process of the total active force on lagging is presented based on the kinematic approach of limit analysis. A comparison is made between the total active force on lagging calculated by the formula presented in this study and the force on a same-size rigid retaining wall obtained from Rankine's theory. It is found that the proposed method fits well with the experimental results.Parametric studies show that the total active force on lagging increases with the growth of the lagging height and the lagging clear span; while decreases asthe soil internal friction angle and soil cohesion increase. 展开更多
关键词 Stabilizing pile Lagging Active earth pressure Limit analysis method Sliding surface
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LaB6 Work Function and Structural Stability under High Pressure
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作者 李鹏善 崔巍然 +6 位作者 李蕊 孙华蕾 李延春 杨栋亮 宫宇 李晖 李晓东 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第7期185-189,共5页
The work functions of the (110) and (10(3) surfaces of LaB6 are determined from ambient pressure to 39.1 GPa. The work function of the (110) surface slowly decreases but that of the (100) surface remains at a... The work functions of the (110) and (10(3) surfaces of LaB6 are determined from ambient pressure to 39.1 GPa. The work function of the (110) surface slowly decreases but that of the (100) surface remains at a relatively constant value. To determine the reason for this difference, the electron density distribution (EDD) is determined from high-pressure single-crystal x-ray diffraction data by the maximum entropy method. The EDD results show that the chemical bond properties in LaB6 play a key role also investigated by single-crystal x-ray diffraction. In observed from ambient pressure to 39.1 GPa. The structural stability of LaB6 under high pressure is this study, no structural or electronic phase transition is 展开更多
关键词 CASTEP EDD 110 MEM LaB6 Work Function and Structural Stability under High pressure
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Numerical Analysis of Three-Layer Deep Tunnel Composite Structure 被引量:3
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作者 Weiwei Sun Hongping Min +3 位作者 Jianzhong Chen Chao Ruan Yanjun Zhang Lei Wang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2021年第4期223-239,共17页
To date,with the increasing attention of countries to urban drainage system,more and more regions around the world have begun to build water conveyance tunnels,sewage pressure deep tunnels and so on.However,the suffic... To date,with the increasing attention of countries to urban drainage system,more and more regions around the world have begun to build water conveyance tunnels,sewage pressure deep tunnels and so on.However,the sufficient bearing capacity and corrosion resistance of the structure,which can ensure the actual service life and safety of the tunnel,remain to be further improved.Glass Fiber Reinforced Plastics(GFRP)pipe,with light weight,high strength and corrosion resistance,has the potential to be applied to the deep tunnel structure.This paper proposed a new composite structure of deep tunnel lined with GFRP pipe,which consisted of three layers of concrete segment,cement paste and GFRP pipe.A new pipe-soil spring element model was proposed for the pipesoil interaction with gaps.Based on the C3D8R solid model and the Combin39 spring model,the finite element numerical analysis of the internal pressure status and external pressure stability of the structure was carried out.Combined with the checking calculation of the theoretical formula,the reliability of the two finite element models was confirmed.A set of numerical analysis methods for the design and optimization of the three-layer structure was established.The results showed that from the internal GFRP pipe to the outer concrete pipe,the pressure decreased from 0.5 to 0.32 MPa,due to the internal pressure was mainly undertaken by the inner GFRP pipe.The allowable buckling pressure of GFRP pipe under the cover of 5 GPa high modulus cement paste was 2.66 MPa.The application of GFRP pipe not only improves the overall performance of the deep tunnel structure but also improves the construction quality and safety.The three-layer structure built in this work is safe and economical. 展开更多
关键词 GFRP pipe deep tunnel structure finite element analysis internal pressure external pressure stability pipe-soil interaction
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Crosswind stability of high-speed trains in special cuts 被引量:3
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作者 张洁 高广军 +1 位作者 刘堂红 李志伟 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第7期2849-2856,共8页
Analysis of the aerodynamic performance of high-speed trains in special cuts would provide references for the critical overturning velocity and complement the operation safety management under strong winds.This work w... Analysis of the aerodynamic performance of high-speed trains in special cuts would provide references for the critical overturning velocity and complement the operation safety management under strong winds.This work was conducted to investigate the flow structure around trains under different cut depths,slope angles using computational fluid dynamics(CFD).The high-speed train was considered with bogies and inter-carriage gaps.And the accuracy of the numerical method was validated by combining with the experimental data of wind tunnel tests.Then,the variations of aerodynamic forces and surface pressure distribution of the train were mainly analyzed.The results show that the surroundings of cuts along the railway line have a great effect on the crosswind stability of trains.With the slope angle and depth of the cut increasing,the coefficients of aerodynamic forces tend to reduce.An angle of 75°is chosen as the optimum one for the follow-up research.Under different depth conditions,the reasonable cut depth for high-speed trains to run safely is 3 m lower than that of the conventional cut whose slope ratio is 1:1.5.Furthermore,the windward slope angle is more important than the leeward one for the train aerodynamic performance.Due to the shield of appropriate cuts,the train body is in a minor positive pressure environment.Thus,designing a suitable cut can contribute to improving the operation safety of high-speed trains. 展开更多
关键词 high-speed train crosswind stability cut pressure distribution numerical simulation
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A first-principles investigation on mechanical and metallic properties of titanium carbides under pressure 被引量:1
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作者 Xiaojing Sha Namin Xiao +1 位作者 Yongjun Guan Xiaosu Yi 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2018年第10期1953-1958,共6页
The titanium carbides are potential candidates to achieve both high hardness and refractory property. We carried out a structural search for titanium carbides at three pressures of 0 GPa, 30 GPa and 50 GPa. A phase di... The titanium carbides are potential candidates to achieve both high hardness and refractory property. We carried out a structural search for titanium carbides at three pressures of 0 GPa, 30 GPa and 50 GPa. A phase diagram of the Ti-C system at 0 K was obtained by elucidating formation enthalpies as a function of compositions, and their mechanical and metallic properties of titanium carbides were investigated sys- tematically. We also discussed the relation of titanium concentration to the both mechanical and metallic properties of titanium carbides. It has been found that the average valence electron density and tractil-ity improved at higher concentrations of titanium, while the degree of covalent bonding directionality decreased. To this effect, the hardness of titanium carbide decreases as the content of titanium increases. Our results indicated that the titanium content significantly affected the metallic properties of the Ti-C system. 展开更多
关键词 First-principles calculation Transition metal carbides Mechanical property and hardness High pressure phase stability
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Polycrystalline diamond compact with enhanced thermal stability 被引量:5
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作者 Shiqi Liu Lei Han +2 位作者 Yongtao Zou Pinwen Zhu Baochang Liu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2017年第11期1386-1391,共6页
Polycrystalline diamond compacts(PDC), which are composed of diamond and WC/Co substrate, and synthesized at high pressure and high temperature(HPHT), are widely applied as the tooth of drilling bit. However, the ... Polycrystalline diamond compacts(PDC), which are composed of diamond and WC/Co substrate, and synthesized at high pressure and high temperature(HPHT), are widely applied as the tooth of drilling bit. However, the thermal stability of PDC will be reduced when diamond transforms into graphite due to cobalt in PDC acting as a catalyst during the drilling work. In this study, a new three-layer structured PDC with enhanced thermal stability has been successfully synthesized at pressures of 5.5–7.0 GPa and temperatures of 1650–1750?C. In this structure, the diamond-Si C composite acts as the working layer,and the diamond-Si C-Co composite and WC/Co cements are as the intermediate layer and substrate,respectively. It is found that the initial oxidizing temperature of the three-layered PDC is enhanced up to820?C, which is significantly higher than that(~780?C) of the conventional PDC counterpart. 展开更多
关键词 Polycrystallie diamond compacts High pressure and high temperature Thermal stability
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