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An autonomous system for thermal convection of viscoelastic fluids in a porous layer using a thermal

Qi WEI, Xiaohui ZHANG

《能源前沿(英文)》 2010年 第4卷 第4期   页码 507-516 doi: 10.1007/s11708-010-0017-x

摘要: Thermal convection of viscoelastic fluids saturating a horizontal porous layer heated from below is analyzed using a thermal nonequilibrium model to take account of the interphase heat transfer between the fluid and the solid. The viscoelastic character of the flow is considered by a modified Darcy’s law. An autonomous system with five differential equations is deduced by applying the truncated Galerkin expansion to the momentum and heat transfer equations. The effects of interphase heat transfer on the thermal convection of viscoelastic fluids in a porous medium are analyzed and discussed. The results show that the weak interphase heat transfer tends to stabilize the steady convection.

关键词: thermal convection     porous media     viscoelastic fluid     thermal nonequilibrium model    

Simulation of viscoelastic behavior of defected rock by using numerical manifold method

Feng REN, Lifeng FAN, Guowei MA

《结构与土木工程前沿(英文)》 2011年 第5卷 第2期   页码 199-207 doi: 10.1007/s11709-011-0102-1

摘要: Numerical simulations of longitudinal wave propagation in a rock bar with microcracks are conducted by using the numerical manifold method which has great advantages in the simulation of discontinuities. Firstly, validation of the numerical manifold method is carried out by simulations of a longitudinal stress wave propagating through intact and cracked rock bars. The behavior of the stress wave traveling in a one-dimensional rock bar with randomly distributed microcracks is subsequently studied. It is revealed that the highly defected rock bar has significant viscoelasticity to the stress wave propagation. Wave attenuation as well as time delay is affected by the length, quantity, specific stiffness of the distributed microcracks as well as the incident stress wave frequency. The storage and loss moduli of the defected rock are also affected by the microcrack properties; however, they are independent of incident stress wave frequency.

关键词: stress wave propagation     defected rock     numerical manifold method     viscoelastic behavior     storage modulus     loss modulus    

Linear viscoelastic behavior of asphalt binders and mixtures containing very high percentages of reclaimed

《结构与土木工程前沿(英文)》   页码 1211-1227 doi: 10.1007/s11709-023-0983-9

摘要: The primary aim of this study is to correlate the impact of aggregates, if any, on the viscoelastic behavior of rejuvenated asphalt mixtures containing very high amounts of reclaimed asphalt pavement (RAP) (> 50%). First, gradation of 100% RAP was rectified, using a modified Bailey method by adding virgin aggregates to achieve two coarse dense-graded and one fine dense-graded blends. Complex modulus test was then performed from −35 to +35 °C and 0.01–10 Hz. In addition to performance grade (PG) testing, extracted and recovered binders from different asphalt mixtures underwent shear complex modulus test within −8 °C to high temperature PG and frequencies from 0.001 to 30 Hz. Cole−Cole, Black space, complex modulus and phase angle master curves were constructed and Shift-Homothety-Shift in time-Shift (SHStS) transformation was used to compare the linear viscoelastic behavior of asphalt binders and mixtures. The influence of aggregates on the viscoelastic behavior of asphalt mixtures depends on temperature and/or frequency. The role of asphalt binders in the behavior of asphalt mixtures is more pronounced at high temperatures and the effect of the aggregate structure increases as the temperature falls. The maximum difference (60% to 70%) in the viscoelastic behavior of the binder and mixture based on SHStS transformed Cole−Cole curves is within the phase angle of 15°–20°.

关键词: RAP     complex modulus     SHStS transformation     rejuvenation     behavior of asphalt binder and mixture    

Review of the LNG intermediate fluid vaporizer and its heat transfer characteristics

《能源前沿(英文)》 2022年 第16卷 第3期   页码 429-444 doi: 10.1007/s11708-021-0747-y

摘要: The intermediate fluid vaporizer (IFV), different from other liquefied natural gas (LNG) vaporizers, has many advantages and has shown a great potential for future applications. In this present paper, studies of IFV and its heat transfer characteristics in the LNG vaporization unit E2 are systematically reviewed. The research methods involved include theoretical analysis, experimental investigation, numerical simulation, and process simulation. First, relevant studies on the overall calculation and system design of IFV are summarized, including the structural innovation design, the thermal calculation model, and the selection of different intermediate fluids. Moreover, studies on the fluid flow and heat transfer behaviors of the supercritical LNG inside the tubes and the condensation heat transfer of the intermediate fluid outside the tubes are summarized. In the thermal calculations of the IFV, the selections of the existing heat transfer correlations about the intermediate fluids are inconsistent in different studies, and there lacks the accuracy evaluation of those correlations or comparison with experimental data. Furthermore, corresponding experiments or numerical simulations on the cryogenic condensation heat transfer outside the tubes in the IFV need to be further improved, compared to those in the refrigeration and air-conditioning temperature range. Therefore, suggestions for further studies of IFV are provided as well.

关键词: intermediate fluid vaporizer     design of structure and intermediate fluid     condensation heat transfer    

Review of fluid and control technology of hydraulic wind turbines

Maolin CAI, Yixuan WANG, Zongxia JIAO, Yan SHI

《机械工程前沿(英文)》 2017年 第12卷 第3期   页码 312-320 doi: 10.1007/s11465-017-0433-2

摘要:

This study examines the development of the fluid and control technology of hydraulic wind turbines. The current state of hydraulic wind turbines as a new technology is described, and its basic fluid model and typical control method are expounded by comparing various study results. Finally, the advantages of hydraulic wind turbines are enumerated. Hydraulic wind turbines are expected to become the main development direction of wind turbines.

关键词: wind turbine     hydraulic system     fluid model     control technology    

Computational fluid dynamics simulation of aerosol transport and deposition

Yingjie TANG, Bing GUO

《环境科学与工程前沿(英文)》 2011年 第5卷 第3期   页码 362-377 doi: 10.1007/s11783-011-0365-8

摘要: In this article computational fluid dynamics (CFD) simulation of aerosol transport and deposition, i.e. the transport and deposition of particles in an aerosol, is reviewed. The review gives a brief account of the basics of aerosol mechanics, followed by a description of the general CFD approach for flow field simulation, turbulence modeling, wall treatments and simulation of particle motion and deposition. Then examples from the literature are presented, including CFD simulation of particle deposition in human respiratory tract and particle deposition in aerosol devices. CFD simulation of particle transport and deposition may provide information that is difficult to obtain through physical experiments, and it may help reduce the number of experiments needed for device design. Due to the difficulty of describing turbulent flow and particle-eddy interaction, turbulent dispersion of particles remains one of the greatest challenges for CFD simulation. However, it is possible to take a balanced approach toward quantitative description of aerosol dispersion using CFD simulation in conjunction with empirical relations.

关键词: computational fluid dynamics (CFD)     aerosol     transport     deposition    

Investigation of carbon dioxide photoreduction process in a laboratory-scale photoreactor by computational fluid

《化学科学与工程前沿(英文)》 2022年 第16卷 第7期   页码 1149-1163 doi: 10.1007/s11705-021-2096-0

摘要: The production of solar fuels via the photoreduction of carbon dioxide to methane by titanium oxide is a promising process to control greenhouse gas emissions and provide alternative renewable fuels. Although several reaction mechanisms have been proposed, the detailed steps are still ambiguous, and the limiting factors are not well defined. To improve our understanding of the mechanisms of carbon dioxide photoreduction, a multiphysics model was developed using COMSOL. The novelty of this work is the computational fluid dynamic model combined with the novel carbon dioxide photoreduction intrinsic reaction kinetic model, which was built based on three-steps, namely gas adsorption, surface reactions and desorption, while the ultraviolet light intensity distribution was simulated by the Gaussian distribution model and Beer-Lambert model. The carbon dioxide photoreduction process conducted in a laboratory-scale reactor under different carbon dioxide and water moisture partial pressures was then modeled based on the intrinsic kinetic model. It was found that the simulation results for methane, carbon monoxide and hydrogen yield match the experiments in the concentration range of 10−4 mol·m–3 at the low carbon dioxide and water moisture partial pressure. Finally, the factors of adsorption site concentration, adsorption equilibrium constant, ultraviolet light intensity and temperature were evaluated.

关键词: carbon dioxide photoreduction     computational fluid dynamic simulation     kinetic model     Langmuir adsorption    

Wind-induced vibration control of Hefei TV tower with fluid viscous damper

Zhiqiang ZHANG , Aiqun LI , Jianping HE , Jianlei WANG ,

《结构与土木工程前沿(英文)》 2009年 第3卷 第3期   页码 249-254 doi: 10.1007/s11709-009-0038-x

摘要: The Hefei TV tower is taken as an analytical case to examine the control method with a fluid viscous damper under wind load fluctuation. Firstly, according to the random vibration theory, the effect of fluctuating wind on the tower can be modeled as a 19-dimensional correlated random process, and the wind-induced vibration analysis of the tower subjected to dynamic wind load was further obtained. On the basis of the others’ works, a bi-model dynamic model is proposed. Finally, a dynamic model is proposed to study the wind-induced vibration control analysis using viscous fluid dampers, and the optimal damping coefficient is obtained regarding the wind-induced response of the upper turret as optimization objectives. Analysis results show that the maximum peak response of the tower under dynamic wind load is far beyond the allowable range of the code. The wind-induced responses and the wind vibration input energy of the tower are decreased greatly by using a fluid viscous damper, and the peak acceleration responses of the upper turret is reduced by 43.4%.

关键词: high-rise structure     wind-induced response     fluid viscous damper     vibration control    

Effect of gastric fluid on adsorption and desorption of endocrine disrupting chemicals on microplastics

《环境科学与工程前沿(英文)》 2022年 第16卷 第8期 doi: 10.1007/s11783-022-1525-8

摘要:

• Effect of gastric fluid on EDCs adsorption-desorption to microplastics was evaluated.

关键词: Microplastics     Gastric fluid     Endocrine-disrupting chemicals     Adsorption     Desorption    

Detection of digestive malignancies and post-gastrectomy complications via gastrointestinal fluid examination

null

《医学前沿(英文)》 2017年 第11卷 第1期   页码 20-31 doi: 10.1007/s11684-016-0493-4

摘要:

To date, gastric carcinoma (GC) is one of the common and fatal digestive malignancies worldwide. The prognosis of GC is not always satisfactory because of late diagnosis. Scholars are keen on discovering novel accurate and economical biomarkers in body liquids for GC screening to detect and evaluate the lesion before the results of imaging techniques are obtained. While traditional serum assays have limited sensitivity and specificity, gastrointestinal juice may provide relevant specific biomarkers because of its close contact with the tumor. Herein, the current progress in the relationship between gastrointestinal fluid analyses and GC is systematically and comprehensively reviewed. The detection of gastric juice pH, fluorescence spectrum, cytology, Helicobacter pylori-associated markers, nitrosamines, conventional tumor markers, amino acids, proteomics, microRNAs, long noncoding RNAs, protein-coding genes, vitamin C, etc., and combination tests of different category markers could provide important diagnostic and prognostic clues for gastrointestinal diseases. Particularly, early GC may be efficiently screened using gastric juice. Gastrointestinal fluid examination could also predict the adverse effects of postgastrectomy, such as pancreatic leakage, fistula, and abscess. Gastric fluid markers should be further studied to reveal the early predicators of malignancy and complications. The methods for obtaining the samples of gastrointestinal juice with minimum incision should also be comprehensively investigated.

关键词: gastrointestinal fluid     gastric carcinoma     biomarker     diagnosis     prognosis     gastrectomy     adverse events    

Static and dynamic analysis of functionally graded fluid-infiltrated porous skew and elliptical nanoplates

《结构与土木工程前沿(英文)》 2023年 第17卷 第3期   页码 477-502 doi: 10.1007/s11709-023-0918-5

摘要: The analysis of static bending and free and forced vibration responses of functionally graded fluid-infiltrated porous (FGFP) skew and elliptical nanoplates placed on Pasternak’s two-parameter elastic foundation is performed for the first time using isogeometric analysis (IGA) based on the non-uniform rational B-splines (NURBSs) basis function. Three types of porosity distributions affect the mechanical characteristics of materials: symmetric distribution, upper asymmetric distribution, and lower asymmetric distribution. The stress–strain relationship for Biot porous materials was determined using the elastic theory. The general equations of motion of the nanoplates were established using the four-unknown shear deformation plate theory in conjunction with the nonlocal elastic theory and Hamilton’s principle. A computer program that uses IGA to determine the static bending and free and forced vibration of a nanoplate was developed on MATLAB software platform. The accuracy of the computational program was validated via numerical comparison with confidence assertions. This set of programs presents the influence of the following parameters on the static bending and free and forced vibrations of nanoplates: porosity distribution law, porosity coefficient and geometrical parameters, elastic foundation, deviation angle, nonlocal coefficient, different boundary conditions, and Skempton coefficients. The numerical findings demonstrated the uniqueness of the FGFP plate’s behavior when the porosities are saturated with liquid compared with the case without liquid. The findings of this study have significant implications for engineers involved in the design and fabrication of the aforementioned type of structures. Furthermore, this can form the basis for future research on the mechanical responses of the structures.

关键词: static bending     free and forced vibrations     nonlocal theory     isogeometric analysis     fluid-infiltrated porous nanoplates    

Creep and recovery behaviors of magnetorheological elastomers

Weihua LI, Yang ZHOU, Tongfei TIAN, Gursel ALICI,

《机械工程前沿(英文)》 2010年 第5卷 第3期   页码 341-346 doi: 10.1007/s11465-010-0096-8

摘要: This paper presents experimental and modeling study of creep and recovery behaviors of magneto-rheological elastomers (MREs) under constant stresses. Experimental study was accomplished using a rheometer with parallel-plate geometry. Under constant stresses ranging from a small value to a large one, the resultant strains were recorded. The experimental results demonstrated that MREs behave as linear visocleastic properties. The effects of the magnetic field and stress on MRE creep behaviors were discussed. Moreover, a four-parameter viscoelastic model was developed to describe MRE creep behaviors. The comparison between the experimental results and the modeling predictions indicates that the model can predict MRE creep behaviors very well.

关键词: magneto-rheological elastomers (MREs)     creep     recovery     linear viscoelastic model    

Introduction to the special section on the Symposium on Computational Fluid Dynamics and Molecular Simulation

Tianwei TAN, Peiyong QIN,

《化学科学与工程前沿(英文)》 2010年 第4卷 第3期   页码 241-241 doi: 10.1007/s11705-009-0285-3

Hydrotreating of light gas oil using a NiMo catalyst supported on activated carbon produced from fluid

N. Rambabu,Sandeep Badoga,Kapil K. Soni,A.K. Dalai,J. Adjaye

《化学科学与工程前沿(英文)》 2014年 第8卷 第2期   页码 161-170 doi: 10.1007/s11705-014-1430-1

摘要: Nitric acid functionalized steam activated carbon (NAFSAC) was prepared from waste fluid petroleum coke (FPC) and used as a support material for the synthesis of a NiMo catalyst (2.5 wt-% Ni and 13 wt-% Mo). The catalyst was then used for the hydrotreatment of light gas oil. The support and catalysts were characterized by Brunauer-Emmett-Teller (BET) gas adsorption method, X-ray diffraction, H -temperature programmed reduction, NH -temperature programmed desorption, CO-chemisorption, mass spetrography, scanning electron microscopy (SEM), Boehm titration, and Fourier transform infrared spectroscopy (FTIR). The SEM results showed that the carbon material retained a needle like structure after functionalization with HNO . The Boehm titration, FTIR, and BET results confirmed that the HNO functionalized material had moderate acidity, surface functional groups, and mesoporosity respectively. The produced NAFSAC had an inert nature, exhibited the sink effect and few metal support interactions, and contained functional groups. All of which make it a suitable support material for the preparation of a NiMo hydrotreating catalyst. Hydrotreating activity studies of the NiMo/NAFSAC catalyst were carried out under industrial operating conditions in a laboratory trickle bed reactor using coker light gas oil as the feedstock. A parallel study was performed on the hydrotreating activity of NiMo/ -Al O as a reference catalyst. The hydrodesulfurization and hydrodenitrogenation activities of the NiMo/NAFSAC catalyst were 62% and 30%, respectively.

关键词: activated carbon     fluid petroleum coke     NiMo catalyst     hydrotreating     light gas oil    

effect on the critical temperature differences of oscillatory thermocapillary convection in two-layer fluid

Hulin HUANG, Xiaoming ZHOU,

《能源前沿(英文)》 2010年 第4卷 第2期   页码 155-160 doi: 10.1007/s11708-009-0063-4

摘要: The effect of different directional magnetic fields on critical temperature differences of oscillatory thermocapillary convection in a rectangular cavity with differentially heated side walls filled with two viscous, immiscible, incompressible fluids is simulated in the absence of gravity. In this two-layer fluid system, the upper layer fluid is the electrically non-conducting encapsulant boron oxide (BO), while the lower one is the electrically conducting molten indium phosphide (InP). The interface between the two fluids is assumed to be flat and non-deformable. The computational results show that all the magnetic fields along the , and directions can delay the transition from steady convection to oscillatory convection, and critical temperature differences increase with an increasing Hartmann number. Furthermore, the effect of a magnetic field along the direction is strongest, followed by that along the direction, and that along the direction is the weakest for the same intensity of the magnetic field.

关键词: magnetohydrodynamic     magnetic fields     thermocapillary convection     critical temperature difference     oscillatory convection     two-layer fluid system    

标题 作者 时间 类型 操作

An autonomous system for thermal convection of viscoelastic fluids in a porous layer using a thermal

Qi WEI, Xiaohui ZHANG

期刊论文

Simulation of viscoelastic behavior of defected rock by using numerical manifold method

Feng REN, Lifeng FAN, Guowei MA

期刊论文

Linear viscoelastic behavior of asphalt binders and mixtures containing very high percentages of reclaimed

期刊论文

Review of the LNG intermediate fluid vaporizer and its heat transfer characteristics

期刊论文

Review of fluid and control technology of hydraulic wind turbines

Maolin CAI, Yixuan WANG, Zongxia JIAO, Yan SHI

期刊论文

Computational fluid dynamics simulation of aerosol transport and deposition

Yingjie TANG, Bing GUO

期刊论文

Investigation of carbon dioxide photoreduction process in a laboratory-scale photoreactor by computational fluid

期刊论文

Wind-induced vibration control of Hefei TV tower with fluid viscous damper

Zhiqiang ZHANG , Aiqun LI , Jianping HE , Jianlei WANG ,

期刊论文

Effect of gastric fluid on adsorption and desorption of endocrine disrupting chemicals on microplastics

期刊论文

Detection of digestive malignancies and post-gastrectomy complications via gastrointestinal fluid examination

null

期刊论文

Static and dynamic analysis of functionally graded fluid-infiltrated porous skew and elliptical nanoplates

期刊论文

Creep and recovery behaviors of magnetorheological elastomers

Weihua LI, Yang ZHOU, Tongfei TIAN, Gursel ALICI,

期刊论文

Introduction to the special section on the Symposium on Computational Fluid Dynamics and Molecular Simulation

Tianwei TAN, Peiyong QIN,

期刊论文

Hydrotreating of light gas oil using a NiMo catalyst supported on activated carbon produced from fluid

N. Rambabu,Sandeep Badoga,Kapil K. Soni,A.K. Dalai,J. Adjaye

期刊论文

effect on the critical temperature differences of oscillatory thermocapillary convection in two-layer fluid

Hulin HUANG, Xiaoming ZHOU,

期刊论文