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Numerical Comparison for Focused Wave Propagation Between the Fully Nonlinear Potential Flow and the Viscous Fluid Flow Models 认领
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作者 JIANG Sheng-chao LIU Chang-feng SUN Lei 《中国海洋工程:英文版》 SCIE EI CSCD 2020年第2期279-288,共10页
Numerical simulations on focused wave propagation are carried out by using three types of numerical models,including the linear potential flow,the nonlinear potential flow and the viscous fluid flow models.The wave-wa... Numerical simulations on focused wave propagation are carried out by using three types of numerical models,including the linear potential flow,the nonlinear potential flow and the viscous fluid flow models.The wave-wave interaction of the focused wave group with different frequency bands and input wave amplitudes is examined,by which the influence of free surface nonlinearity and fluid viscosity on the related phenomenon of focused wave is investigated.The significant influence of free surface nonlinearity on the characteristics of focused wave can be observed,including the increased focused wave crest,delayed focused time and downstream shift of focused position with the increase of input amplitude.It can plot the evident difference between the results of the nonlinear potential flow and linear potential flow models.However,only a little discrepancy between the nonlinear potential flow and viscous fluid flow models can be observed,implying the insignificant effect of fluid viscosity on focused wave behavior.Therefore,the nonlinear potential flow model is recommended for simulating the non-breaking focused wave problem in this study. 展开更多
关键词 focused wave linear potential flow fully nonlinear potential flow viscous fluid flow boundary element method OPENFOAM
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Experimental study on combined buoyant-thermocapillary flow along with rising liquid film on the surface of a horizontal metallic mesh tube 认领
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作者 Manuel J.GOMES Ning MEI 《能源前沿:英文版》 SCIE CSCD 2020年第1期114-126,共13页
Temperature distribution and variation with time has been considered in the analysis of the influences of the initial level of immersion of a horizontal metallic mesh tube in the liquid on combined buoyant and thermoc... Temperature distribution and variation with time has been considered in the analysis of the influences of the initial level of immersion of a horizontal metallic mesh tube in the liquid on combined buoyant and thermocapillary flow.The combined flow occurs along with the rising liquid film flow on the surface of a horizontal metallic mesh tube.Three different levels of immersion of the metallic mesh tube in the liquid have been tested.Experiments of 60 min in duration have been performed using a heating metallic tube with a diameter of 25 mm and a length of 110 mm,sealed outside with a metallic mesh of 178 mm by 178 mm,and distilled water.These reveal two distinct flow patterns.Thermocouples and infrared thermal imager are utilized to measure the temperature.The level of the liquid free surface relative to the lower edge of the tube is measured as angleθ.The results show that for a smallerθangle,or a low level of immersion,with a relatively low heating power,it is possible to near fully combine the upwards buoyant flow with the rising liquid film flow.In this case,the liquid is heated only in the vicinity of the tube,while the liquid away from the flow region experiences small changes in temperature and the system approaches steady conditions.For largerθangles,or higher levels of immersion,a different flow pattern is noticed on the liquid free surface and identified as the thermo-capillary(Marangoni)flow.The rising liquid film is also present.The higher levels of immersion cause a high temperature gradient in the liquid free surface region and promote thermal stratification;therefore the system could not approach steady conditions. 展开更多
关键词 RISING liquid film combined FLOW thermocapillary FLOW BUOYANT FLOW metallic MESH TUBE HORIZONTAL TUBE
Effects of loose deposits on debris flow processes in the Aizi Valley, southwest China 认领
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作者 LIU Mei ZHANG Yong +3 位作者 TIAN Shu-feng CHEN Ning-sheng MAHFUZR Rahman JAVED Iqbal 《山地科学学报:英文版》 SCIE CSCD 2020年第1期156-172,共17页
Loose deposits, rainfall and topography are three key factors that triggering debris flows.However, few studies have investigated the effects of loose deposits on the whole debris flow process.On June 28, 2012, a cata... Loose deposits, rainfall and topography are three key factors that triggering debris flows.However, few studies have investigated the effects of loose deposits on the whole debris flow process.On June 28, 2012, a catastrophic debris flow occurred in the Aizi Valley, resulting in 40 deaths.The Aizi Valley is located in the Lower Jinsha River,southwestern Sichuan Province, China. The Aizi Valley debris flow has been selected as a case for addressing loose deposits effects on the whole debris flow process through remote sensing, field investigation and field experiments. Remote sensing interpretation and laboratory experiments were used to obtain the distribution and characteristics of the loose deposits, respectively. A field experiment was conducted to explore the mechanics of slope debris flows, and another field investigation was conducted to obtain the processes of debris flow formation, movement and amplification. The results showed that loose deposits preparation, slope debris flow initiation,gully debris flow confluence and valley debris flow amplification were dominated by the loose deposits.Antecedent droughts and earthquake activities may have increased the potential for loose soil sources in the Aizi Valley, which laid the foundation for debris flow formation. Slope debris flow initiated under rainfall, and the increase in the water content as well as the pore water pressure of the loose deposits were the key factors affecting slope failure. The nine gully debris flows converged in the valley, and the peak discharge was amplified 3.3 times due to a blockage and outburst caused by a large boulder. The results may help in predicting and assessing regional debris flows in dry-hot and seismic-prone areas based on loose deposits, especially considering large boulders. 展开更多
关键词 Aizi VALLEY Loose deposits DEBRIS FLOW process Slope DEBRIS FLOW BOULDER BLOCKAGE Discharge amplification
Flow Resistance Modeling for Coolant Distribution within Canned Motor Cooling Loops 认领
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作者 Shengde Wang Zhenqiang Yao Hong Shen 《中国机械工程学报:英文版》 SCIE EI CAS CSCD 2020年第1期210-220,共11页
Taylor–Couette–Poiseuille(TCP)flow dominates the inner water-cooling circulation of canned motor reactor coolant pumps.Current research on TCP flow focuses on torque behaviors and flow regime transitions through exp... Taylor–Couette–Poiseuille(TCP)flow dominates the inner water-cooling circulation of canned motor reactor coolant pumps.Current research on TCP flow focuses on torque behaviors and flow regime transitions through experiments and simulations.However,research on axial flow resistance in a large Reynolds number turbulent state is not sufficient,especially for the various flow patterns.This study is devoted to investigating the influence of annular flow on the axial flow resistance of liquid in the coaxial cylinders of the stator and rotor in canned motor reactor coolant pumps,and predicting the coolant flow distribution between the upper coil cooling loop and lower bearing lubricating loop for safe operation.The axial flow resistance,coupled with the annular rotation,is experimentally investigated at a flow rate with an axial Reynolds number,Rea,from 2.6×10~3 to 6.0×10~3 and rotational Reynolds number,Ret,from 1.6×10~4 to 4.0×10~4.It is revealed that the axial flow frictional coe cient varies against the axial flow rate in linear relation sets with logarithmic coordinates,which shift up when the flow has a higher Ret.Further examination of the axial flow resistance,with the Rea extending to 3.5×10~5 and Ret up to 1.6×10~5,by simulation shows gentle variation rates in the axial flow frictional coe cients against the Rea.The relation curves with different Ret values converge when the Rea exceeds 3.5×10~5.A prediction model for TCP flow consisting of a polygonal approximation with logarithmic coordinates is developed to estimate the axial flow resistance against different axial and rotational Reynolds numbers for the evaluation of heat and mass transfer during transition states and the engineering design of the canned motor chamber structure. 展开更多
关键词 FLOW resistance Rotating effect REYNOLDS numbers Taylor–Couette–Poiseuille FLOW CANNED motor
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Reynolds number effect on compressible cylindrical cavity flow 认领
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作者 Kung-Ming CHUNG Yi-Xuan HUANG +1 位作者 Kuan-Huang LEE Keh-Chin CHANG 《中国航空学报:英文版》 SCIE EI CAS CSCD 2020年第2期456-464,共9页
Presence of a cavity changes the mean and fluctuating pressure distributions inside and near the cavity.For cylindrical cavity flow,the diameter-to-depth ratio is the dominant factor.In this study,flow is naturally de... Presence of a cavity changes the mean and fluctuating pressure distributions inside and near the cavity.For cylindrical cavity flow,the diameter-to-depth ratio is the dominant factor.In this study,flow is naturally developed along a flat plate with two different lengths,resulting in different incoming boundary layer thicknesses ahead of the cavity.The effect of Reynolds number based on incoming boundary layer thickness on characteristics of mean and fluctuating pressure distributions is addressed.Pressure sensitive paint was also used to visualize the mean surface pressure patterns.The effect of Reynolds number on the classification of compressible cylindrical cavity flow and self-sustained oscillating frequency is not significant.An increase in Reynolds number results in a reduction in the value of differential pressure or momentum flux near the rear edge. 展开更多
关键词 CAVITY FLOW COMPRESSIBLE FLOW CONVECTION velocity Open CAVITY OSCILLATION
基于不同阀芯颈部直径参数的液压锥阀流量特性的影响研究 认领
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作者 石金艳 龚煌辉 李辉 《计算机与数字工程》 2020年第4期967-969,共3页
建立了液压锥阀三维模型,运用计算流体动力学(Computational Fluid Dynamics,CFD)方法对锥阀进行仿真研究,得到阀芯颈部直径对液压锥阀流量特性的规律。其结果表明:在阀口开度大小相同的情况下,液压锥阀的阀芯颈部直径数值大小不会引起... 建立了液压锥阀三维模型,运用计算流体动力学(Computational Fluid Dynamics,CFD)方法对锥阀进行仿真研究,得到阀芯颈部直径对液压锥阀流量特性的规律。其结果表明:在阀口开度大小相同的情况下,液压锥阀的阀芯颈部直径数值大小不会引起流量的变化,同时流量系数基本保持不变约为0.87。 展开更多
关键词 液压锥阀 流量 流量系数
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全国首例“暗刷流量”案的规范刍议与实践指引 认领
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作者 张小余 《嘉应学院学报》 2020年第1期61-66,共6页
全国首例"暗刷流量"案的审理,为人们提供司法途径以了解这一产业的运行模式,同时也展现了法律对"暗刷流量"行为的否定评价。这一现象对社会公共秩序的影响恶劣,如不加以遏制,将会助长社会的不正之风,个案的审结仅... 全国首例"暗刷流量"案的审理,为人们提供司法途径以了解这一产业的运行模式,同时也展现了法律对"暗刷流量"行为的否定评价。这一现象对社会公共秩序的影响恶劣,如不加以遏制,将会助长社会的不正之风,个案的审结仅是价值上的引导,更重要的是针对这一现象法律规则的树立和完善。由此便需要从"暗刷流量"现象的产生与演变、规范刍议和实践指引三个方面展开,明确"暗刷流量"的产生背景与演变路径,通过"暗刷流量"案的审理明确已有的行为规制规范及改进方向,进而通过理论与实践的联系,指明典型案件对立法、行政、司法与守法的实践指引作用。 展开更多
关键词 流量 暗刷流量 法律规制 责任承担 实践指引
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Mechanism from particle compaction to fluidization of liquid–solid two-phase flow 认领
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作者 张悦 宋锦春 +2 位作者 马连喜 郑连存 刘明贺 《中国物理B:英文版》 SCIE EI CAS CSCD 2020年第1期373-377,共5页
A new model of particle yield stress including cohesive strength is proposed,which considers the friction and cohesive strength between particles.A calculation method for the fluidization process of liquid–solid two-... A new model of particle yield stress including cohesive strength is proposed,which considers the friction and cohesive strength between particles.A calculation method for the fluidization process of liquid–solid two-phase flow in compact packing state is given,and the simulation and experimental studies of fluidization process are carried out by taking the sand–water two-phase flow in the jet dredging system as an example,and the calculation method is verified. 展开更多
关键词 liquid–solid FLOW two-phase FLOW COHESIVE strength yield stress
Discharge flow of granular particles through an orifice on a horizontal hopper:Effect of the hopper angle 认领
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作者 王欣 朱红伟 +1 位作者 史庆藩 郑宁 《中国物理B:英文版》 SCIE EI CAS CSCD 2020年第4期312-315,共4页
We experimentally investigate the effect of the hopper angle on the flow rate of grains discharged from a twodimensional horizontal hopper on a conveyor belt.The flow rate grows with the hopper angle,and finally reach... We experimentally investigate the effect of the hopper angle on the flow rate of grains discharged from a twodimensional horizontal hopper on a conveyor belt.The flow rate grows with the hopper angle,and finally reaches a plateau.The curve feature appears to be similar for different orifice widths and conveyor belt-driven velocities.On the basis of an empirical law of flow rate for a flat-bottom hopper,we propose a modified equation to describe the relation between the flow rate and hopper angle,which is in a good agreement with the experimental results. 展开更多
关键词 GRANULAR FLOW FLOW rate HOPPER ANGLE Beverloo law
柴油机燃烧室的系统设计方法研究与应用 认领
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作者 雷基林 于跃 +3 位作者 辛千凡 申立中 宋国富 陈丽琼 《农业工程学报》 EI CAS CSCD 北大核心 2020年第6期36-46,共11页
为使柴油机燃烧室设计走向系统化和正规化,提出了柴油机燃烧室系统设计的概念。通过对因子处理方法和响应分析方法的梳理总结了9种因子-响应组合方法,选取其中1个燃烧室设计方法进行方法展示。此方法以一款四气门直喷式柴油机作为研究对... 为使柴油机燃烧室设计走向系统化和正规化,提出了柴油机燃烧室系统设计的概念。通过对因子处理方法和响应分析方法的梳理总结了9种因子-响应组合方法,选取其中1个燃烧室设计方法进行方法展示。此方法以一款四气门直喷式柴油机作为研究对象,建立了缸内气体瞬态流动模型,以缸内气体流速和湍流动能作为评价标准,在压缩比基本保持不变的前提下,对比分析了缩口率分别为16.4%、6.1%、9.8%、9.8%且底面凸台形状不同的A、B、C、D 4种ω型燃烧室对缸内流场的影响。研究结果表明,燃烧室几何结构对柴油机进气阶段和压缩阶段前期的缸内气流运动影响较小,对压缩阶段后期缸内气流运动影响显著。在上止点前后20°曲轴转角区段,底面凸台呈锥形的C型燃烧室的平均挤流速度、逆挤流速度比底面凸台呈球形的D型燃烧室分别高25.2%、26.4%;缩口率为16.4%的A型燃烧室内气体平均湍流动能比缩口率为9.8%的D型燃烧室高25.4%。与底面凸台呈椭球形的A型和呈球形的D型燃烧室相比,底面凸台呈45°锥形的B、C型燃烧室在湍流动能强度和逆挤流强度方面的保持性更好。该文研究结果可为柴油机燃烧室结构设计和优化提供参考。 展开更多
关键词 柴油机 燃烧 流动 系统设计 湍流动能 挤流 缸内气流运动
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Influence of Secondary Sealing Flow on Performance of Turbine Axial Rim Seals 认领
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作者 WANG Ruonan DU Qiang +3 位作者 LIU Guang LIAN Zengyan XIE Lei ZHU Junqiang 《热科学学报:英文版》 SCIE EI CAS CSCD 2020年第3期840-851,共12页
Purge flow is of great importance in cooling turbine disks and sealing rotor-stator disc cavity to reduce hot gas ingestion in gas turbines.The amount of cooling air extracted from the compressor is crucial to engine ... Purge flow is of great importance in cooling turbine disks and sealing rotor-stator disc cavity to reduce hot gas ingestion in gas turbines.The amount of cooling air extracted from the compressor is crucial to engine efficiency.Excessive sealing air will cause not only a reduction in work transfer but also an increase in aerodynamic losses caused by the mixing of main and sealing flow.In order to simplify rim seal structure while ensuring high sealing efficiency,the current paper optimizes the flow path of the secondary air system and presents a new rim seal structure with auxiliary sealing holes transporting a certain amount of secondary sealing flow.The new structure was compared with the conventional counterpart using validated CFD methods,showing that the additional secondary sealing flow is possible to improve sealing efficiency in disk cavity.The current paper investigates the secondary sealing flow with and without swirl(the angle of auxiliary sealing hole inclination is 0°and 45°respectively),while maintaining the total amount of the sealing flow,flowrate ratio of sealing air(main sealing flow rate versus secondary sealing flow rate=1:1,2:1,3:1,4:1),found that both two parameters have essential impacts on sealing efficiency.The relationship between these two parameters and sealing efficiency was obtained,and it provides a new philosophy for the design of rim seal in gas turbines. 展开更多
关键词 rim seal sealing efficiency secondary sealing flow sealing flowrate ratio swirled flow
Two integrable generalizations of WKI and FL equations: Positive and negative flows, and conservation laws 认领
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作者 耿献国 郭飞英 翟云云 《中国物理B:英文版》 SCIE EI CAS CSCD 2020年第5期70-73,共4页
With the aid of Lenard recursion equations,an integrable hierarchy of nonlinear evolution equations associated with a 22 matrix spectral problem is proposed,in which the first nontrivial member in the positive flows ... With the aid of Lenard recursion equations,an integrable hierarchy of nonlinear evolution equations associated with a 22 matrix spectral problem is proposed,in which the first nontrivial member in the positive flows can be reduced to a new generalization of the Wadati-Konno-Ichikawa(WKI)equation.Further,a new generalization of the Fokas-Lenells(FL)equation is derived from the negative flows.Resorting to these two Lax pairs and Riccati-type equations,the infinite conservation laws of these two corresponding equations are obtained. 展开更多
关键词 integrable generalizations positive flow and negative flow infinite conservation laws
Visualization of flow behavior in ore-segregated packed beds with fine interlayers 认领
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作者 Lei-ming Wang Sheng-hua Yin Ai-xiang Wu 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2020年第7期900-909,共10页
Ore particles,especially fine interlayers,commonly segregate in heap stacking,leading to undesirable flow paths and changeable flow velocity fields of packed beds.Computed tomography(CT),COMSOL Multiphysics,and MATLAB... Ore particles,especially fine interlayers,commonly segregate in heap stacking,leading to undesirable flow paths and changeable flow velocity fields of packed beds.Computed tomography(CT),COMSOL Multiphysics,and MATLAB were utilized to quantify pore structures and visualize flow behavior inside packed beds with segregated fine interlayers.The formation of fine interlayers was accompanied with the segregation of particles in packed beds.Fine particles reached the upper position of the packed beds during stacking.CT revealed that the average porosity of fine interlayers(24.21%)was significantly lower than that of the heap packed by coarse ores(37.42%),which directly affected the formation of flow paths.Specifically,the potential flow paths in the internal regions of fine interlayers were undeveloped.Fluid flowed and bypassed the fine interlayers and along the sides of the packed beds.Flow velocity also indicated that the flow paths easily gathered in the pore throat where flow velocity(1.8×10-5 m/s)suddenly increased.Fluid stagnant regions with a flow velocity lower than 0.2×10-5 m/s appeared in flow paths with a large diameter. 展开更多
关键词 fine interlayer flow behavior computed tomography SEGREGATION preferential flow
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Sensitivity analysis of flowfield modeling parameters upon the flow structure and aerodynamics of an opposing jet over a hypersonic blunt body 认领
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作者 Jinghui GUO Guiping LIN +1 位作者 Xueqin BU Hao LI 《中国航空学报:英文版》 SCIE EI CAS CSCD 2020年第1期161-175,共15页
Implementation of an opposing jet in design of a hypersonic blunt body significantly modifies the external flowfield and yields a considerable reduction in the aerodynamic drag.This study aims to investigate the effec... Implementation of an opposing jet in design of a hypersonic blunt body significantly modifies the external flowfield and yields a considerable reduction in the aerodynamic drag.This study aims to investigate the effects of flowfield modeling parameters of injection and freestream on the flow structure and aerodynamics of a blunt body with an opposing jet in hypersonic flow.Reynolds-Averaged Navier-Stokes(RANS)equations with a Shear Stress Transport(SST)turbulence model are employed to simulate the intricate jet flow interaction.Through utilizing a Non-Intrusive Polynomial Chaos(NIPC)method to construct surrogates,a functional relation is established between input modeling parameters and output flowfield and aerodynamic quantities in concern.Sobol indices in sensitivity analysis are introduced to represent the relative contribution of each parameter.It is found that variations in modeling parameters produce large variations in the flow structure and aerodynamics.The jet-to-freestream total-pressure ratio,jet Mach number,and freestream Mach number are the major contributors to variation in surface pressure,demonstrating an evident location-dependent behavior.The penetration length of injection,reattachment angle of the shear layer,and aerodynamic drag are also most sensitive to the three crucial parameters above.In comparison,the contributions of freestream temperature,freestream density,and jet total temperature are nearly negligible. 展开更多
关键词 AERODYNAMICS FLOW structure HYPERSONIC FLOW Opposing JET Sensitivity analysis Surrogate model
Side Chain Engineering of Sulfonated Poly(arylene ether)s for Proton Exchange Membranes 认领
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作者 Xiang Zhang Zhi-Wen Li +2 位作者 Xia-Lin Chen Dong-Yang Chen Yu-Ying Zheng 《高分子科学:英文版》 SCIE CAS CSCD 2020年第6期644-652,共9页
Proton conductivity of proton exchange membranes(PEMs)strongly relies on microscopic morphology,which can be modulated by engineering the distribution of ionic groups.Herein,poly(arylene ether)s with densely distribut... Proton conductivity of proton exchange membranes(PEMs)strongly relies on microscopic morphology,which can be modulated by engineering the distribution of ionic groups.Herein,poly(arylene ether)s with densely distributed allyl functionalities are polymerized from a tetra-allyl bisphenol A monomer.The subsequent thiol-ene addition with sodium 3-mercapto-1-propanesulfonate yields comb-shaped sulfonated fluorinated poly(arylene ether)s(SFPAEs)with ion exchange capacities(lECs)ranging from 1.29 mmol·g^-1 to 1.78 mmol g^-1.These SFPAEs exhibit superior proton conductivity over the whole temperature range,which is attributed to the enhanced hydrophilic/hydrophobic phase separation as evidenced by small angle X-ray scattering characterizations.The SFPAE-4-40 with an IEC of 1.78 mmol·g^-1 shows the largest proton conductivity of 93 mS-crrr1 at room temperature under fully hydrated condition,higher than that of Nafion 212.Furthermore,the vanadium redox flow battery(VRFB)assembled with SFPAE-4-40 separator exhibits higher energy efficiency than the VRFB assembled with Nafion 212. 展开更多
关键词 PROTON exchange membrane THIOL-ENE addition SIDE-CHAIN ENGINEERING Phase separation VANADIUM redox flow battery
Characteristics of geothermal reservoirs and utilization of geothermal resources in the southeastern coastal areas of China 认领
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作者 ZHANG Ying LUO Jun FENG Jian-yun 《地下水科学与工程:英文版》 2020年第2期134-142,共9页
Based on regional geological setting, stratigraphic distribution and other geological conditions, this paper summarized three types of geothermal reservoirs in the southeast coastal areas of China: Cenozoic sandstone ... Based on regional geological setting, stratigraphic distribution and other geological conditions, this paper summarized three types of geothermal reservoirs in the southeast coastal areas of China: Cenozoic sandstone or sandy conglomerate reservoir, Mesozoic granite fissure reservoir and Paleozoic karst reservoir. Cenozoic sandstone or sandy conglomerate reservoirs are mainly located in Cenozoic basins, such as Zhangzhou, Fuzhou, Sanshui and Leiqiong basins. The Tertiary sedimentary basins such as Leiqiong Basin and Sanshui Basin, are controlled by NE-trending faults, while the Quaternary sedimentary such as Zhangzhou and Fuzhou basins are controlled by NW-trending faults. Mesozoic granite fissure reservoirs are mainly distributed in the southeast coastal areas, such as Zhangzhou, Fuzhou, Fengshun, Yangjiang and southern part of Hainan Province. The distribution of good Mesozoic granite fissure reservoir in these areas is mainly controlled by NE-trending faults. Paleozoic carbonate reservoirs are widely distributed in these areas. Most carbonate rocks are from the upper Paleozoic strata, such as those in the area of Huizhou in Guangdong Province. The major types of geothermal systems in the southeast coastal areas of China belong to medium and low-temperature convection. The geothermal resources developed from the ground to-3 000 m underground could be utilized directly for space heating, greenhouse heating, aquaculture pond heating and industrial uses, as well as other purposes. The geothermal resources with a depth of 3 000~6 000 m underground is mainly featured by Hot Dry Rock(HDR) with a temperature ranges from 150 ℃ to 200 ℃, which is conductive to the development of Enhanced Geothermal System(EGS) and can be utilized for power generation. 展开更多
关键词 Geologic setting Geothermal reservoirs Heat flow Geothermal resources UTILIZATION
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New Differential Harnack Inequalities for Nonlinear Heat Equations 认领
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作者 Jiayong WU 《数学年刊:B辑英文版》 SCIE CSCD 2020年第2期267-284,共18页
This paper deals with constrained trace, matrix and constrained matrix Harnack inequalities for the nonlinear heat equation ωt = ?ω + aωln ω on closed manifolds. A new interpolated Harnack inequality for ωt = ?ω... This paper deals with constrained trace, matrix and constrained matrix Harnack inequalities for the nonlinear heat equation ωt = ?ω + aωln ω on closed manifolds. A new interpolated Harnack inequality for ωt = ?ω-ωln ω +εRω on closed surfaces under ε-Ricci flow is also derived. Finally, the author proves a new differential Harnack inequality for ωt= ?ω-ωln ω under Ricci flow without any curvature condition. Among these Harnack inequalities, the correction terms are all time-exponential functions, which are superior to time-polynomial functions. 展开更多
关键词 Harnack INEQUALITY NONLINEAR HEAT EQUATION RICCI flow
Classifying wakes produced by self-propelled fish-like swimmers using neural networks 认领
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作者 Binglin Li Xiang Zhang Xing Zhang 《力学快报:英文版》 CAS CSCD 2020年第3期149-154,共6页
We consider the classification of wake structures produced by self-propelled fish-like swimmers based on local measurements of flow variables.This problem is inspired by the extraordinary capability of animal swimmers... We consider the classification of wake structures produced by self-propelled fish-like swimmers based on local measurements of flow variables.This problem is inspired by the extraordinary capability of animal swimmers in perceiving their hydrodynamic environments under dark condition.We train different neural networks to classify wake structures by using the streamwise velocity component,the crosswise velocity component,the vorticity and the combination of three flow variables,respectively.It is found that the neural networks trained using the two velocity components perform well in identifying the wake types,whereas the neural network trained using the vorticity suffers from a high rate of misclassification.When the neural network is trained using the combination of all three flow variables,a remarkably high accuracy in wake classification can be achieved.The results of this study can be helpful to the design of flow sensory systems in robotic underwater vehicles. 展开更多
关键词 Flow sensing Machine learning Wake classification Self-propelled swimming Fluid-structure interaction
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Study on dynamic characteristics of fission products in 2 MW molten salt reactor 认领
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作者 Bo Zhou Xiao-Han Yu +6 位作者 Yang Zou Pu Yang Shi-He Yu Ya-Fen Liu Xu-Zhong Kang Gui-Feng Zhu Rui Yan 《核技术:英文版》 SCIE CAS CSCD 2020年第2期42-54,共13页
In this study,a numerical flow model of the fission products(FPs)in the primary loop system of a molten salt reactor(MSR)was established and solved using Mathematica 7.0.The simulation results were compared with those... In this study,a numerical flow model of the fission products(FPs)in the primary loop system of a molten salt reactor(MSR)was established and solved using Mathematica 7.0.The simulation results were compared with those of the ORIGEN-S program in the static burnup mode,and the deviation was found to be less than 10%,which indicates that the results are in good agreement.Furthermore,the FPs distribution in the primary loop system under normal operating conditions of the 2 MW MSR was quantitatively analyzed.In addition,the distribution phenomenon of the FPs under different flow rate conditions was studied.At the end of life,the FPs activity in the core region(including active region,and upper and lower plenum regions)accounted for 77.3%,and that in the hot leg #1,main pump,hot leg #2,heat exchanger,and cold leg region accounted for 1.2%,16.15%,0.99%,2.5%,and 1.9%,respectively,of the total FPs in the primary loop under normal operating conditions.The proportion of FPs in the core decreased with the increase in flow rate in the range of 2.24-22,400 cm^3 s^-1.The established analytical method and conclusions of this study can provide an important basis for radiation safety design of the primary loop,radioactive source management design,thermal-hydraulic safety analysis,and radiochemical analysis of FPs of 2 MW MSRs. 展开更多
关键词 MOLTEN salt REACTOR FISSION products RADIOACTIVE source TERM Primary LOOP system Flow model
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学龄前儿童乳牙龋齿采用不同复合树脂充填修复的临床效果分析 认领
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作者 宋旭 李卓骏 孔雪 《吉林医学》 CAS 2020年第5期1204-1206,共3页
目的:分析学龄前儿童乳牙龋齿采用不同树脂充填修复的临床效果。方法:选择150例乳牙患龋齿的学龄前儿童参与研究,随机分为观察组和对照组。观察组采用Beautifil Flow Plus(F00)流动树脂充填修复治疗。对照组采用Filtek Z350 XT复合树脂... 目的:分析学龄前儿童乳牙龋齿采用不同树脂充填修复的临床效果。方法:选择150例乳牙患龋齿的学龄前儿童参与研究,随机分为观察组和对照组。观察组采用Beautifil Flow Plus(F00)流动树脂充填修复治疗。对照组采用Filtek Z350 XT复合树脂充填修复治疗。记录两组治疗时间,评价两组患牙修复体固位性,评价两组患牙继发龋的情况。结果:两组治疗时间相比,观察组治疗用时少,经统计学分析,差异有统计学意义(P<0.05)。观察组患牙固位性Ⅰ级患者率高于对照组,固位性Ⅲ级患者率低于对照组,经统计学分析,差异有统计学意义(P<0.05)。观察组患牙继发龋少于对照组,经统计学分析,差异无统计学意义(P>0.05)。结论:学龄前儿童乳牙龋齿采用Beautifil Flow Plus(F00)流动树脂作为填充材料比采用Filtek Z350 XT树脂效果更佳。 展开更多
关键词 学龄前儿童 乳牙龋齿 Beautifil Flow Plus(F00)流动树脂 Filtek Z350 XT复合树脂
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