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Magnetohydrodynamic slip flow and diffusion of a reactive solute past a permeable flat plate with suction

Krishnendu BHATTACHARYYA, G. C. LAYEK

《化学科学与工程前沿(英文)》 2011年 第5卷 第4期   页码 471-476 doi: 10.1007/s11705-011-1130-z

摘要: The magnetohydrodynamic (MHD) boundary layer slip flow and solute transfer over a porous plate in the presence of a chemical reaction are investigated. The governing equations were transformed into self-similar ordinary differential equations by adopting the similarity transformation technique. Then the numerical solutions are obtained by a shooting technique using the fourth order Runge-Kutta method. The study reveals that due to the increase in the boundary slip, the concentration decreases and the velocity increases. On the other hand, with an increase in the magnetic field and mass suction, both boundary layer thicknesses decreased. As the Schmidt number and the reaction rate parameter increases, the concentration decreases and the mass transfer increases.

关键词: slip flow     MHD boundary layer     reactive solute diffusion     flat plate     suction/injection    

A preliminary analysis and discussion of the condominium building collapse in surfside, Florida, US, June 24, 2021

《结构与土木工程前沿(英文)》 2021年 第15卷 第5期   页码 1097-1110 doi: 10.1007/s11709-021-0766-0

摘要: On June 24, 2021, a 40-year-old reinforced concrete flat plate structure building in Miami suffered a sudden partial collapse. This study analyzed the overall performance and key components of the collapsed building based on the building design codes (ACI-318 and GB 50010). Punching shear and post-punching performances of typical slab-column joints are also studied through the refined finite element analysis. The collapse process was simulated and visualized using a physics engine. By way of these analyses, weak design points of the collapsed building are highlighted. The differences between the reinforcement detailing of the collapsed building and the requirements of the current Chinese code are discussed, together with a comparison of the punching shear and post-punching performances. The simulated collapse procedure and debris distribution are compared with the actual collapse scenes.

关键词: progressive collapse     flat plate     simulation     punching    

Quantitative analysis of microplastics in coastal tidal-flat reclamation in Dongtai, China

《环境科学与工程前沿(英文)》 2022年 第16卷 第8期 doi: 10.1007/s11783-022-1528-5

摘要:

• Reclamation projects are important disturbances on microplastic risk in coasts.

关键词: Coastal reclamation     Engineering geotextiles     Soil microplastics     Weathering simulation     Marine emission    

Multi-objective optimization of surface texture for the slipperswash plate interface in EHA pumps

《机械工程前沿(英文)》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0704-4

摘要: Well-designed surface textures can improve the tribological properties and the efficiency of the electro-hydrostatic actuator (EHA) pump under high-speed and high-pressure conditions. This study proposes a multi-objective optimization model to obtain the arbitrarily surface textures design of the slipper/swash plate interface for improving the mechanical and volumetric efficiency of the EHA pump. The model is composed of the lubrication film model, the component dynamic model considering the spinning motion, and the multi-objective optimization model. In this way, the arbitrary-shaped surface texture with the best comprehensive effect in the EHA pump is achieved and its positive effects in the EHA pump prototype are verified. Experimental results show a reduction in wear and an improvement in mechanical and volumetric efficiency by 1.4% and 0.8%, respectively, with the textured swash plate compared with the untextured one.

关键词: electro-hydrostatic actuator     axial piston pump     slipper/swash plate interface     multi-objective optimization     surface texture    

Nonlinear numerical simulation of punching shear behavior of reinforced concrete flat slabs with shear-heads

Dan V. BOMPA, Ahmed Y. ELGHAZOULI

《结构与土木工程前沿(英文)》 2020年 第14卷 第2期   页码 331-356 doi: 10.1007/s11709-019-0596-5

摘要: This paper examines the structural response of reinforced concrete flat slabs, provided with fully-embedded shear-heads, through detailed three-dimensional nonlinear numerical simulations and parametric assessments using concrete damage plasticity models. Validations of the adopted nonlinear finite element procedures are carried out against experimental results from three test series. After gaining confidence in the ability of the numerical models to predict closely the full inelastic response and failure modes, numerical investigations are carried out in order to examine the influence of key material and geometric parameters. The results of these numerical assessments enable the identification of three modes of failure as a function of the interaction between the shear-head and surrounding concrete. Based on the findings, coupled with results from previous studies, analytical models are proposed for predicting the rotational response as well as the ultimate strength of such slab systems. Practical recommendations are also provided for the design of shear-heads in RC slabs, including the embedment length and section size. The analytical expressions proposed in this paper, based on a wide-ranging parametric assessment, are shown to offer a more reliable design approach in comparison with existing methods for all types of shear-heads, and are suitable for direct practical application.

关键词: non-linear numerical modelling     concrete damage plasticity     RC flat slabs     shear-heads     punching shear    

Effects of sheet thickness and material on the mechanical properties of flat clinched joint

Chao CHEN, Huiyang ZHANG, Shengdun ZHAO, Xiaoqiang REN

《机械工程前沿(英文)》 2021年 第16卷 第2期   页码 410-419 doi: 10.1007/s11465-020-0618-y

摘要: The flat clinching process is attracting a growing attention in the joining field of lightweight materials because it avoids the geometric protrusion that appears in the conventional clinching process. In this paper, the effects of sheet thickness and material on the mechanical properties of the clinched joint were studied. Al1060 and Al2024 sheets with 2 mm thickness were employed to develop the clinched joint by using different material configurations, and Al1060 sheets with 2.5- and 1.5-mm thicknesses were used to produce the clinched joint by using different thickness configurations. The clinched joints using various sheet configurations were sectioned, and dimensional analysis was conducted. Cross-tensile and shearing tests were carried out to analyze the mechanical properties of the clinched joint, including tensile strength, shearing strength, and absorbed energy. In addition, the failure modes of the clinched joints were discussed. Results indicated that the clinched joint with a stiff top sheet had increased static strength regardless of the test type. The clinched joint with a thick top sheet demonstrated lower static strength than the joint with a thick bottom sheet in the cross-tensile test. However, this result was reversed in the shearing tests. The flat clinching process has a great potential in joining dissimilar and various thickness materials.

关键词: clinched joint     flat clinching process     thickness configuration     material configuration     mechanical property    

Preparation and characterization of PVDF-PFSA flat sheet ultrafiltration membranes

Jiquan MA, Junhong ZHAO, Zhongbin REN, Lei LI

《化学科学与工程前沿(英文)》 2012年 第6卷 第3期   页码 301-310 doi: 10.1007/s11705-012-1204-6

摘要: High performance polyvinylidene fluoride (PVDF) flat sheet ultrafiltration (UF) membranes have been prepared by an immersion precipitation phase inversion method using perfluorosulfonic acid (PFSA) as a pore former and as a hydrophilic component of the membranes and polyethylene glycol ( = 400) (PEG400) as a pore forming agent. The effects of the presence of PEG and the concentration of the PFSA on the phase separation of the casting solutions and on the morphologies and performance of UF membranes including their porosity, water flux, rejection of bovine serum albumin (BSA) protein, and anti-fouling property were investigated. Phase diagrams, viscosities and the phase separations upon exposure to water vapor showed that both PEG400 and PFSA promoted demixing of the casting solution. Scanning electron microscopy measurements showed that the PVDF-PFSA blend membranes had more macropores and finger-like structures than the native PVDF membranes. The PVDF-PFSA membrane (5 wt-% PEG400+ 5 wt-% PFSA) had a pure water flux of 141.7 L/m ·h, a BSA rejection of 90.1% and a relative pure water flux reduction (RFR) of 15.28%. These properties were greatly superior to those of the native PVDF membrane (pure water flux of 5.6 L/m ·h, BSA rejection of 96.3% and RFR of 42.86%).

关键词: polyvinylidene fluoride     perfluorosulfonic acid     polyethylene glycol     flat sheet membrane     ultrafiltration    

Initial stiffness and moment resistance of reinforced joint with end-plate connection

Sufang WANG, Yiyi CHEN,

《结构与土木工程前沿(英文)》 2009年 第3卷 第4期   页码 345-351 doi: 10.1007/s11709-009-0054-x

摘要: In beam-to-column joint with bolted end-plate connection, the structural details of column flange reinforced by backing plate and column web panel reinforced by supplementary plate are analyzed. The joint is divided into some basic components, and the initial stiffness of each component is obtained. Especially, the initial stiffness of reinforced components is drawn by theoretical model and finite element analysis. The initial stiffness of reinforced joint can be obtained by assembling the initial stiffness of each component. The design moment resistance of column flange reinforced by backing plate is deduced based on yield line method, and the design moment resistances of other components are deduced based on present codes. The design moment resistance of the reinforced joint is then determined by the minimum of the design moment resistances of all components. By comparison with the results of finite element calculation, it is verified that the method to calculate the initial stiffness of reinforced joint is accurate enough to be used to estimate the rigid behavior of the joint and to make parametric study.

关键词: steel structure     end-plate connection     backing plate     supplementary web plate     initial stiffness     moment resistance    

Modeling of Ce(IV) transport through a dispersion flat combined liquid membrane with carrier P507

Liang PEI,Liming WANG,Zhanying MA

《环境科学与工程前沿(英文)》 2014年 第8卷 第4期   页码 503-509 doi: 10.1007/s11783-013-0540-1

摘要: A mathematical model for the transport of Ce(IV) from hydrochloric acid solutions through dispersion flat combined liquid membrane (DFCLM) with contain 2-ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester (P507) as the carrier, dissolved in kerosene as the membrane solution have been studied. This process of facilitated transport, based on membrane technology, is a variation on the conventional technique of solvent extraction and may be described mathematically using Fick’s second law. The equations for transport velocity are derived considering the diffusion of P507 and its metallic complexes through the liquid membrane. In this work, the system is considered to be in a transient state, and chemical reaction between Ce(IV) and the carrier to take place only at the solvent–aqueous interfaces. Model concentration profiles are obtained for the Ce(IV), from which extraction velocities are predicted. The experimental and simulated Ce(IV) extractions showed similar tendencies for a high Ce(IV) concentration and acidity case.The model results indicate that high initial Ce(IV) concentrations and acidity both have detrimental effects on Ce(IV) extraction and stripping. The diffusion coefficient of Ce(IV) in the membrane and the thickness of diffusion layer between feed phase and membrane phase are obtained and the values are 6.31 × 10 m ·s and 31.2 μm, respectively. The results are in good agreement with experimental results.

关键词: Dispersion flat combined liquid membrane (DFCLM)     dispersion phase     feed phase     2-ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester     Ce (IV)    

On the improvement design of dynamic characteristics for the roller follower of a variable-speed plate

Hui Ching FAN, Hong Sen YAN

《机械工程前沿(英文)》 2012年 第7卷 第1期   页码 5-15 doi: 10.1007/s11465-012-0310-y

摘要:

Without modifying the cam contour, a cam mechanism with a variable input speed trajectory offers an alternative solution to flexibly achieve kinematic and dynamic characteristics, and then decrease the follower’s residual vibration. Firstly, the speed trajectory of cam is derived by employing Bezier curve, and motion continuity conditions are investigated. Then the motion characteristics between the plate cam and its roller follower are derived. To analyze the residual vibration, a single degree of freedom dynamic model of the elastic cam-follower system is introduced. Based on the motion equation derived from the dynamic model, the residual vibration of the follower is yielded. The design procedure to improve the kinematic and dynamic motion characteristics is presented and two design examples with discussions are provided. Finally, the simulations of the kinematic and dynamic models by ADAMS are carried out and verified that the design models as well as the performances of the mechanism are feasible.

关键词: cam mechanism     variable input speed     kinematic design     dynamic design     optimal design    

Frequencies of circular plate with concentric ring and elastic edge support

null

《机械工程前沿(英文)》 2014年 第9卷 第2期   页码 168-176 doi: 10.1007/s11465-014-0299-5

摘要:

Exact solutions for the flexural vibrations of circular plates having elastic edge conditions along with rigid concentric ring support have been presented in this paper. Values of frequency parameter for the considered circular plate are computed for different sets of values of elastic rotational and translation restraints and the radius of internal rigid ring support. The results for the first three modes of plate vibrations are computed and are presented in tabular form. The effects of rotational and linear restraints and the radius of the rigid ring support on the vibration behavior of circular plates are studied over a wide range of non-dimensional parametric values. The values of the exact frequency parameter presented in this paper for varying values of restraint parameters and the radius of the rigid ring support can better serve in design and as benchmark solutions to validate the numerical methods obtained by using other methods of solution.

关键词: circular plate     frequency     elastic edge     rigid ring     mode switching    

Enhanced cross-flow filtration with flat-sheet ceramic membranes by titanium-based coagulation for membrane

《环境科学与工程前沿(英文)》 2022年 第16卷 第8期 doi: 10.1007/s11783-022-1531-x

摘要:

• Ceramic membrane filtration showed high performance for surface water treatment.

关键词: Ceramic membrane     Coagulation     Polytitanium chloride     Membrane fouling    

滩涂湿地利用与保护的协调发展探讨——以上海市为例

陈吉余,程和琴,戴志军

《中国工程科学》 2007年 第9卷 第6期   页码 11-17

摘要:

文章就潮滩一词探索其定义 , 明确其研究范围 , 以长江口 ——— 上海市潮滩 、 湿地为例 , 论述其基本 特点 , 及其对长江来水来沙条件的响应 , 可开发的强度以及对湿地保护的要求 , 并就长江河口不同类型的潮滩 分别阐述它们的发展过程 、 现状与趋势 , 对不同潮滩和湿地的合理开发 、 动态保护 、 生态修复提出具体意见 , 从发展要求提出应对近海水域空间开发进行研究的建议 。

关键词: 上海市     滩涂     湿地     利用     保护    

Transversal tube pitch effects on local heat transfer characteristics of the flat tube bank fin mounted

Liangbi WANG, Zhimin LIN, Kangjie SUN, Yuanxin DONG, Song LIU, Yongheng ZHANG,

《能源前沿(英文)》 2010年 第4卷 第3期   页码 333-345 doi: 10.1007/s11708-009-0061-6

摘要: The tube bank fin is commonly used to increase the area of the heat transfer surface with a small heat transfer coefficient of a heat exchanger. If vortex generators (VGs) are punched on the fin surface, the heat transfer performance of the fin can be improved. This paper focused on the effect of transversal tube pitch on the local heat transfer performance of the three-row flat tube bank fin mounted with VGs. On the fin surface, constructing the flow channel but without mounted VGs, the transversal tube pitch was greater, and the span averaged Nusselt number downstream was larger because fewer interactions of vortices would be generated from different VGs located upstream. When the area goodness factor was used as the criteria on the condition of one tube unit of heat exchanger for commonly used fin materials and fin thickness, the transversal tube pitch has considerable effect on the heat transfer enhancement of VGs. Large transversal tube pitch is more sensitive to fin material than to fin thickness.

关键词: heat transfer enhancement     vortex generator     finned flat tube bank     heat exchanger    

Linear ultrasonic motor using quadrate plate transducer

Jiamei JIN, Chunsheng ZHAO

《机械工程前沿(英文)》 2009年 第4卷 第1期   页码 88-91 doi: 10.1007/s11465-009-0016-y

摘要: A linear ultrasonic motor using a quadrate plate transducer was developed for precision positioning. This motor consists of two pairs of Pb(Zr,Ti)O piezoelectric ceramic elements, which are piezoelectrically excited into the second-bending mode of the motor stator’s neutral surface in two orthogonal directions, on which the tops of four projections move along an elliptical trajectory, which in turn drives a contacted slider into linear motion via frictional forces. The coincident frequency of the stator is easily obtained for its coincident characteristic dimension in two orthogonal directions. The performance characteristics achieved by the motor are: 1) a maximum linear speed of more than 60 mm/s; 2) a stroke of more than150 mm; 3) a driving force of more than 5.0 N; and 4) a response time of about 2 ms.

关键词: ultrasonic motor     quadrate plate     coincident frequency     alternant contact    

标题 作者 时间 类型 操作

Magnetohydrodynamic slip flow and diffusion of a reactive solute past a permeable flat plate with suction

Krishnendu BHATTACHARYYA, G. C. LAYEK

期刊论文

A preliminary analysis and discussion of the condominium building collapse in surfside, Florida, US, June 24, 2021

期刊论文

Quantitative analysis of microplastics in coastal tidal-flat reclamation in Dongtai, China

期刊论文

Multi-objective optimization of surface texture for the slipperswash plate interface in EHA pumps

期刊论文

Nonlinear numerical simulation of punching shear behavior of reinforced concrete flat slabs with shear-heads

Dan V. BOMPA, Ahmed Y. ELGHAZOULI

期刊论文

Effects of sheet thickness and material on the mechanical properties of flat clinched joint

Chao CHEN, Huiyang ZHANG, Shengdun ZHAO, Xiaoqiang REN

期刊论文

Preparation and characterization of PVDF-PFSA flat sheet ultrafiltration membranes

Jiquan MA, Junhong ZHAO, Zhongbin REN, Lei LI

期刊论文

Initial stiffness and moment resistance of reinforced joint with end-plate connection

Sufang WANG, Yiyi CHEN,

期刊论文

Modeling of Ce(IV) transport through a dispersion flat combined liquid membrane with carrier P507

Liang PEI,Liming WANG,Zhanying MA

期刊论文

On the improvement design of dynamic characteristics for the roller follower of a variable-speed plate

Hui Ching FAN, Hong Sen YAN

期刊论文

Frequencies of circular plate with concentric ring and elastic edge support

null

期刊论文

Enhanced cross-flow filtration with flat-sheet ceramic membranes by titanium-based coagulation for membrane

期刊论文

滩涂湿地利用与保护的协调发展探讨——以上海市为例

陈吉余,程和琴,戴志军

期刊论文

Transversal tube pitch effects on local heat transfer characteristics of the flat tube bank fin mounted

Liangbi WANG, Zhimin LIN, Kangjie SUN, Yuanxin DONG, Song LIU, Yongheng ZHANG,

期刊论文

Linear ultrasonic motor using quadrate plate transducer

Jiamei JIN, Chunsheng ZHAO

期刊论文