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A way to explain the thermal boundary effects on laminar convection through a square duct

Liangbi WANG, Xiaoping GAI, Kun HUANG, Yongheng ZHANG, Xiang YANG, Xiang WU

《能源前沿（英文）》 2010年 第4卷 第4期   页码 496-506 doi: 10.1007/s11708-010-0020-2

摘要： A way using the reformulation of the energy conservation equation in terms of heat flux to explain the thermal boundary effects on laminar convective heat transfer through a square duct is presented. For a laminar convection through a square duct, it explains that on the wall surface, the velocity is zero, but convection occurs for uniform wall heat flux (UWHF) boundary in the developing region due to the velocity gradient term; for uniform wall temperature (UWT) boundary, only diffusion process occurs on the wall surface because both velocity and velocity gradient do not contribute to convection; for UWHF, the largest term of the gradient of velocity components (the main flow velocity) on the wall surface takes a role in the convection of the heat flux normal to the wall surface, and this role exists in the fully developed region. Therefore, a stronger convection process occurs for UWHF than for UWT on the wall surface. The thermal boundary effects on the laminar convection inside the flow are also detailed.

关键词： convective transport     heat transfer     mass transfer     laminar flow     thermal boundary effects    

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Effects of radiation and heat source/sink on unsteady MHD boundary layer flow and heat transfer over

Krishnendu Bhattacharyya

《化学科学与工程前沿（英文）》 2011年 第5卷 第3期   页码 376-384 doi: 10.1007/s11705-011-1121-0

摘要： In this paper, an investigation is made to study the effects of radiation and heat source/sink on the unsteady boundary layer flow and heat transfer past a shrinking sheet with suction/injection. The flow is permeated by an externally applied magnetic field normal to the plane of flow. The self-similar equations corresponding to the velocity and temperature fields are obtained, and then solved numerically by finite difference method using quasilinearization technique. The study reveals that the momentum boundary layer thickness increases with increasing unsteadiness and decreases with magnetic field. The thermal boundary layer thickness decreases with Prandtl number, radiation parameter and heat sink parameter, but it increases with heat source parameter. Moreover, increasing unsteadiness, magnetic field strength, radiation and heat sink strength boost the heat transfer.

关键词： MHD boundary layer     unsteady flow     heat transfer     thermal radiation     heat source/sink     shrinking sheet     suction/injection    

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Effects of Boundary Condition and Helix Angle on Meshing Performance of TI Worm Gearing

SUN Yue-hai, DUAN Lu-qian, WANG Shu-ren, ZHANG Ce

《机械工程前沿（英文）》 2006年 第1卷 第1期   页码 90-95 doi: 10.1007/s11465-005-0006-7

摘要：

To exactly describe the contact state and contact area of tooth surface of toroidal involute (TI) worm gearing, the authors introduced boundary condition into contact line analysis.With helix angle chosen as parameter, the criterion for the existence of meshing boundary line on the surface of TI worm gearing is derived. Results show that there can be four situations for meshing boundary line on the tooth surface of gear, namely, inexistence of meshing boundary line, a unique line, two lines, and two coincident lines. If the helix angle is equal to or slightly smaller than the bigger angle, which makes two meshing boundary lines superpose, a preferable meshing performance is obtained. Computer simulation proves the validity of the above conclusion.

关键词： preferable     inexistence     Results     validity     boundary condition    

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波浪与两相连浮体的相互作用

勾莹,滕斌,宁德志

《中国工程科学》 2004年 第6卷 第7期   页码 75-80

摘要：

应用边界积分方程方法研究了波浪与2个相连三维浮体的相互作用问题。计算中考虑了浮体相互间的水动力干涉，通过联立各浮体的运动方程以及运动连续条件求得浮体运动量。计算了2个铰连接漂浮方箱组成的系统，同Newman的结果进行了对比,当入射波的频率不在系统的自振频率附近时，结果与Newman的结果吻合良好，在自振频率附近时，铰接点处的转角和垂向位移都发生快速变化，而Newman未提到这一现象。

关键词： 边界积分     水动力影响     运动响应    

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Effects of hemin and thermal stress exposure on JWA expression

ZHAO Ming, CHEN Rui, LI Aiping, ZHOU Jianwei

《医学前沿（英文）》 2007年 第1卷 第1期   页码 104-108 doi: 10.1007/s11684-007-0020-8

摘要： To investigate the expression of JWA after hemin and (or) thermal stress exposure, we treated K562 (chronic myelogenous leukemia cells) cells with different doses of hemin and thermal stress using different exposure times. The expression of JWA protein was determined by Western blot analysis. Reverse transcription-polymerase chain reaction was carried out to determine JWA mRNA expression. JWA promoter transcription activity analysis was performed by chloramphenicol acetyl transferase-enzyme linked immunosorbent assay (CAT-ELISA). The expression of JWA protein was significantly increased by up to (3.23±0.57) folds compared to the control in K562 cells after hemin treatment (50 µM for one week), and a similar pattern was observed in the cells after treatment with thermal stress (42 °C) for 2 hours [increased by (8.00±1.73) folds]. The expression of JWA mRNA was also significantly elevated by up to (1.37±0.06) folds in K562 cells treated with hemin (30 µM for 48 hours), and a similar regulatory pattern [increased by (1.87±0.13) folds] was observed with thermal stress exposure (42 °C) for 30 minutes. However, a combined antagonistic effect was observed in the treatment of K562 cells with hemin (30 µM, 48 h) followed by thermal stress (42 °C, 30 min). CAT-ELISA further confirmed that either hemin or thermal stress treatment could up-regulate JWA transcription activity, however, the effects could be counteracted partly by treatment with a combination of both. Hemin and thermal stress might regulate JWA expression via distinct intracellular signal transduction pathways.
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energy distribution of modulated multi-pulse injection modes based diesel HCCI combustion and their effectson engine thermal efficiency and emissions

LIU Bin, SU Wanhua, WANG Hui, HUANG Haozhong

《能源前沿（英文）》 2007年 第1卷 第4期   页码 420-427 doi: 10.1007/s11708-007-0061-7

摘要： Cycle fuel energy distribution and combustion characteristics of early in-cylinder diesel homogenous charge compression ignition (HCCI) combustion organized by modulated multi-pulse injection modes are studied by the engine test.

关键词： combustion     compression     homogenous     in-cylinder     modulated multi-pulse    

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Effects of thermocline on performance of underwater glider’s power system propelled by ocean thermal

Hai YANG, Jie MA,

《能源前沿（英文）》 2009年 第3卷 第4期   页码 472-479 doi: 10.1007/s11708-009-0052-7

摘要： The thermal glider’s changeable volume produces propelling force to power the glider’s descending and ascending through the thermocline. The different depth, thickness, and intensity of the thermocline at different seasons and locations affect the working processes of the glider’s power system. Based on the enthalpy method, a mathematical model of the underwater glider’s power system was established and the time efficiency of operation was introduced, so that the effects of different thermoclines on the underwater glider’s power system were analyzed theoretically. The simulation result shows that the thermocline affects the transition time of the phase change processes of working fluids within the thermal engine tubes. There exist the threshold values of the thermocline’s depth and upper thickness for the power system’s operation. A depth or upper thickness of the thermocline less than the corresponding threshold leads the power system to work abnormally. To keep the power system working efficiently, a glider must be kept in warm surface water for a certain period before it moves through cold water, so that the time efficiency of operation is reduced. A less time efficiency of operation is unfavorable to the thermal glider to penetrate through the ocean currents.

关键词： mathematical     underwater glider     system working     certain     corresponding threshold    

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Chemically reactive solute transfer in a boundary layer slip flow along a stretching cylinder

Swati Mukhopadhyay

《化学科学与工程前沿（英文）》 2011年 第5卷 第3期   页码 385-391 doi: 10.1007/s11705-011-1101-4

摘要： This paper presents the distribution of a solute undergoing a first order chemical reaction in an axisymmetric laminar boundary layer flow along a stretching cylinder. Velocity slip condition at the boundary is used instead of no-slip condition. Similarity transformations are used to convert the partial differential equations corresponding to momentum and concentration into highly nonlinear ordinary differential equations. Numerical solutions of these equations are obtained by the shooting method. The velocity decreases with increasing slip parameter. The skin friction as well as the mass transfer rate at the surface is larger for a cylinder than for a flat plate.

关键词： boundary layer     stretching cylinder     partial slip     mass transfer     similarity solution    

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Controlling nested wrinkle morphology through the boundary effect on narrow-band thin films

Hanyang XU, Tielin SHI, Guanglan LIAO, Qi XIA

《机械工程前沿（英文）》 2019年 第14卷 第2期   页码 235-240 doi: 10.1007/s11465-017-0458-6

摘要： We describe the formation of nested wrinkles created by the thermal mismatch between a narrow-band thin film and a compliant substrate. When a film is described as “narrow-band”, it literally means that the film band width is much shorter than its length; more precisely, it means that the width is comparable with the wavelength of the wrinkles. A silicon mask was used during film sputtering to create narrow-band films on poly (dimethylsiloxane) substrate, thus creating regular boundaries to steer local stresses and control wrinkle morphology. Disordered nano-scale wrinkles were found nested within highly ordered micro-scale sinusoidal wrinkles. The formation of nested wrinkles was explained through the amplitude and wavelength saturation of nano-scale wrinkles. The disordered morphology of nano-scale wrinkles and the highly ordered morphology of micro-scale wrinkles were explained by using the boundary effect.

关键词： nested and hierarchical wrinkles     morphology     amplitude saturation     boundary effect    

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Approaching the upper boundary of driver-response relationships: identifying factors using a novel framework

《环境科学与工程前沿（英文）》 2023年 第17卷 第6期 doi: 10.1007/s11783-023-1676-2

摘要：

● A novel framework integrating quantile regression with machine learning is proposed.

关键词： Driver-response     Upper boundary of relationship     Interpretable machine learning     Quantile regression     Total phosphorus     Chlorophyll a    

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Comparison of indirect boundary element and finite element methods A case study: Shiraz-Esfahan railway

Amin MANOUCHEHRIAN, Mohammad Fatehi MARJI, Mohsen MOHEBBI

《结构与土木工程前沿（英文）》 2012年 第6卷 第4期   页码 385-392 doi: 10.1007/s11709-012-0173-7

摘要： Because of the high importance of transportation tunnels, most precise analyses of stress concentration and displacement around them are essential to provide safety of them as much as possible. Recently, various numerical methods such as finite element method (FEM), discrete element method (DEM), finite difference method (FDM) and boundary element method (BEM) have been used extremely in geosciences problems, but among these numerical methods, BEM has been used less than others because the computational algorithm is not so straightforward. This paper suggests the implementation of the indirect boundary element method (IBEM) as a formulation of BEM to analyze displacement around Shiraz-Esfahan railway tunnel in Zagros Mountains southwest of Iran. For this purpose, this tunnel has been modeled numerically using two-dimensional fictitious stress method (TWOFS) algorithm. To validate the results, they were compared with FEM results as a commonly used numerical method. Results of current theoretical study have shown that the presented approach using IBEM is reasonably accurate and can be used for analysis of displacement in geosciences problems. In rock mechanics, for problems with a low ratio of boundary surface to volume, FEM is not very well suited and may be cumbersome, but use of such a proposed IBEM approach can be particularly attractive.

关键词： indirect boundary element method     finite element method     displacement     tunnel     case study    

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Molecular dynamics investigation of mechanical properties of single-layer phagraphene

Ali Hossein Nezhad SHIRAZI

《结构与土木工程前沿（英文）》 2019年 第13卷 第2期   页码 495-503 doi: 10.1007/s11709-018-0492-4

摘要： Phagraphene is a very attractive two-dimensional (2D) full carbon allotrope with very interesting mechanical, electronic, optical, and thermal properties. The objective of this study is to investigate the mechanical properties of this new graphene like 2D material. In this work, mechanical properties of phagraphene have been studied not only in the defect-free form, but also with the critical defect of line cracks, using the classical molecular dynamics simulations. Our study shows that the pristine phagraphene in zigzag direction experience a ductile behavior under uniaxial tensile loading and the nanosheet in this direction are less sensitive to temperature changes as compared to the armchair direction. We studied different crack lengths to explore the influence of defects on the mechanical properties of phagraphene. We also investigated the temperature effect on the mechanical properties of pristine and defective phagraphene. Our classical atomistic simulation results confirm that larger cracks can reduce the strength of the phagraphene. Moreover, it was shown the temperature has a considerable weakening effect on the tensile strength of phagraphene. The results of this study may be useful for the design of nano-devices using the phagraphene.

关键词： phaqraphene     mechanical properties     crack propaqation     molecular dynamics     thermal effects    

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Engineering the grain boundary: a promising strategy to configure NiCoPO/NiCoP nanowire arrays for ultra-stable

《化学科学与工程前沿（英文）》 2022年 第16卷 第8期   页码 1259-1267 doi: 10.1007/s11705-021-2132-0

摘要： NiCoP4O12/NiCoP nanorod-like arrays with tunable grain boundary density and pores were synthesized by the processes composed of hydrothermal and pyrolysis, in which, the electron structure of Ni and Co atoms characterized by X-ray photoelectron spectroscopy was contemporaneous inverse manipulated. The optimized NiCoP4O12/NiCoP arrays have a high specific capacitance of 507.8 μAh∙cm–2 at 1 mA∙cm–2, and good rate ability of 64.7% retention at 30-folds increased current density. Importantly, an ultra-stable ability, 88.5% of retention after 10000 cycles, was achieved in an asymmetric cell assembled of the NiCoP4O12/NiCoP arrays with activated carbon. In addition, the energy and power densities of an asymmetric cell were higher than those of other work, demonstrating as-prepared NiCoP4O12/NiCoP arrays are promising electrodes for supercapacitors.

关键词： NiCo     array electrode     grain boundary     stability     supercapacitor    

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Slender reinforced concrete shear walls with high-strength concrete boundary elements

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 138-151 doi: 10.1007/s11709-022-0897-y

摘要： Reinforced concrete structural walls are commonly used for resisting lateral forces in buildings. Owing to the advancements in the field of concrete materials over the past few decades, concrete mixes of high compressive strength, commonly referred to as high-strength concrete (HSC), have been developed. In this study, the effects of strategic placement of HSC on the performance of slender walls were examined. The finite-element model of a conventional normal-strength concrete (NSC) prototype wall was validated using test data available in extant studies. HSC was incorporated in the boundary elements of the wall to compare its performance with that of the conventional wall at different axial loads. Potential reductions in the reinforcement area and size of the boundary elements were investigated. The HSC wall exhibited improved strength and stiffness, and thereby, allowed reduction in the longitudinal reinforcement area and size of the boundary elements for the same strength of the conventional wall. Cold joints resulting from dissimilar concrete pours in the web and boundary elements of the HSC wall were modeled and their impact on behavior of the wall was examined.

关键词： slender walls     high-strength concrete     rectangular and barbell-shaped walls     cold joints    

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Hydrologic experiments and modeling of two laboratory bioretention systems under different boundary conditions

Ruifen Liu, Elizabeth Fassman-Beck

《环境科学与工程前沿（英文）》 2017年 第11卷 第4期 doi: 10.1007/s11783-017-0951-5

摘要： Hydrologic performance of bioretention systems is significantly influenced by the media composition and underdrain configuration. This research measured hydrologic performance of column-scale bioretention systems during a synthetic design storm of 25.9 mm, assuming a system area:catchment area ratio of 5%. The laboratory experiments involved two different engineered media and two different drainage configurations. Results show that the two engineered media with different sand aggregates were able to retain about 36% of the inflow volume with free drainage configuration. However, the medium with marine sand is better at delaying the occurrence of drainage than the one with pumice sand, denoting the better detention ability of the former. For both engineered media, an underdrain configuration with internal water storage (IWS) zone lowered drainage volume and peak drainage rate as well as delayed the occurrence of drainage and peak drainage rate, as compared to a free drainage configuration. The USEPA SWMM v5.1.11 model was applied for the free drainage configuration case, and there is a reasonable fit between observed and modeled drainage-rates when media-specific characteristics are available. For the IWS drainage configuration case, air entrapment was observed to occur in the engineered medium with marine sand. Filling of an IWS zone is most likely to be influenced by many factors, such as the structure of the bioretention system, medium physical and hydraulic properties, and inflow characteristics. More research is needed on the analysis and modeling of hydrologic process in bioretention with IWS drainage configuration.

关键词： Bioretention     Hydrologic process     Underdrain configuration     SWMM     Modeling    

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标题 作者 时间 类型 操作

A way to explain the thermal boundary effects on laminar convection through a square duct

Liangbi WANG, Xiaoping GAI, Kun HUANG, Yongheng ZHANG, Xiang YANG, Xiang WU

期刊论文

Effects of radiation and heat source/sink on unsteady MHD boundary layer flow and heat transfer over

Krishnendu Bhattacharyya

期刊论文

Effects of Boundary Condition and Helix Angle on Meshing Performance of TI Worm Gearing

SUN Yue-hai, DUAN Lu-qian, WANG Shu-ren, ZHANG Ce

期刊论文

波浪与两相连浮体的相互作用

勾莹,滕斌,宁德志

期刊论文

Effects of hemin and thermal stress exposure on JWA expression

ZHAO Ming, CHEN Rui, LI Aiping, ZHOU Jianwei

期刊论文

energy distribution of modulated multi-pulse injection modes based diesel HCCI combustion and their effectson engine thermal efficiency and emissions

LIU Bin, SU Wanhua, WANG Hui, HUANG Haozhong

期刊论文

Effects of thermocline on performance of underwater glider’s power system propelled by ocean thermal

Hai YANG, Jie MA,

期刊论文

Chemically reactive solute transfer in a boundary layer slip flow along a stretching cylinder

Swati Mukhopadhyay

期刊论文

Controlling nested wrinkle morphology through the boundary effect on narrow-band thin films

Hanyang XU, Tielin SHI, Guanglan LIAO, Qi XIA

期刊论文

Approaching the upper boundary of driver-response relationships: identifying factors using a novel framework

期刊论文

Comparison of indirect boundary element and finite element methods A case study: Shiraz-Esfahan railway

Amin MANOUCHEHRIAN, Mohammad Fatehi MARJI, Mohsen MOHEBBI

期刊论文

Molecular dynamics investigation of mechanical properties of single-layer phagraphene

Ali Hossein Nezhad SHIRAZI

期刊论文

Engineering the grain boundary: a promising strategy to configure NiCoPO/NiCoP nanowire arrays for ultra-stable

期刊论文

Slender reinforced concrete shear walls with high-strength concrete boundary elements

期刊论文

Hydrologic experiments and modeling of two laboratory bioretention systems under different boundary conditions

Ruifen Liu, Elizabeth Fassman-Beck

期刊论文