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Effects of radiation and heat source/sink on unsteady MHD boundary layer flow and heat transfer over a shrinkingsheet with suction/injection

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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Formation mechanism and modeling of surface waviness in incremental sheet forming

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0679-1

摘要： Improving and controlling surface quality has always been a challenge for incremental sheet forming (ISF), whereas the generation mechanism of waviness surface is still unknown, which impedes the widely application of ISF in the industrial field. In this paper, the formation mechanism and the prediction of waviness are both investigated through experiments, numerical simulation, and theoretical analysis. Based on a verified finite element model, the waviness topography is predicted numerically for the first time, and its generation is attributed to the residual bending deformation through deformation history analysis. For more efficient engineering application, a theoretical model for waviness height is proposed based on the generation mechanism, using a modified strain function considering deformation modes. This work is favorable for the perfection of formation mechanism and control of surface quality in ISF.

关键词： surface waviness     incremental sheet forming     numerical simulation     formation mechanism     deformation history    

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Establishment and verification of a shrinking core model for dilute acid hydrolysis of lignocellulose

Cunwen WANG, Xiaoling DUAN, Weiguo WANG, Zihao LI, Yuanhang QIN

《能源前沿（英文）》 2012年 第6卷 第4期   页码 413-419 doi: 10.1007/s11708-012-0212-z

摘要： The kinetics of lignocellulose hydrolysis under the conditions of high temperature and dilute acid (mass fraction 0.05%) was investigated in this paper. By studying the reducing sugar concentration versus reaction temperature (170°C–220°C) and reaction time (150–1800 s) during the hydrolysis process of five kinds of crop straw (rice, wheat, cotton, rape and corn), the shrinking core model was established, and the differential equation of the model and its analytical solution were obtained. With a numerical calculation method, the kinetic equation was estimated, and the degradation of reducing sugar obeyed first-order kinetics was obtained. The calculated results from the equations agreed well with the original experimental data. The calculation by the model showed that the reducing sugar concentration increases as the size of the particles decrease, and the uniform particles increase.

关键词： lignocellulose     dilute acid hydrolysis     shrinking core model    

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Combination form analysis and experimental study of mechanical properties on steel sheet glass fiber

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 834-850 doi: 10.1007/s11709-021-0743-7

摘要： The concept of steel sheet glass fiber reinforced polymer (GFRP) composite bar (SSGCB) was put forward. An optimization plan was proposed in the combined form of SSGCB. The composite principle, material selection, and SSGCB preparation technology have been described in detail. Three-dimensional finite element analysis was adopted to perform the combination form optimization of different steel core structures and different steel core contents based on the mechanical properties. Mechanical tests such as uniaxial tensile, shear, and compressive tests were carried out on SSGCB. Parametric analysis was conducted to investigate the influence of steel content on the mechanical properties of SSGCB. The results revealed that the elastic modulus of SSGCB had improvements and increased with the rise of steel content. Shear strength was also increased with the addition of steel content. Furthermore, the yield state of SSGCB was similar to the steel bar, both of which indicated a multi-stage yield phenomenon. The compressive strength of SSGCB was lower than that of GFRP bars and increased with the increase of the steel core content. Stress-strain curves of SSGCB demonstrated that the nonlinear-stage characteristics of SSGCB-8 were much more obvious than other bars.

关键词： steel sheet GFRP composite bar     combination form     numerical modeling     mechanical properties test     strength    

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FEM-based strain analysis study for multilayer sheet forming process

Rongjing ZHANG,Lihui LANG,Rizwan ZAFAR

《机械工程前沿（英文）》 2015年 第10卷 第4期   页码 373-379 doi: 10.1007/s11465-015-0371-9

摘要：

Fiber metal laminates have many advantages over traditional laminates (e.g., any type of fiber and resin material can be placed anywhere between the metallic layers without risk of failure of the composite fabric sheets). Furthermore, the process requirements to strictly control the temperature and punch force in fiber metal laminates are also less stringent than those in traditional laminates. To further explore the novel method, this study conducts a finite element method-based (FEM-based) strain analysis on multilayer blanks by using the 3A method. Different forming modes such as wrinkling and fracture are discussed by using experimental and numerical studies. Hydroforming is used for multilayer forming. The Barlat 2000 yield criteria and DYNAFORM/LS-DYNA are used for the simulations. Optimal process parameters are determined on the basis of fixed die-binder gap and variable cavity pressure. The results of this study will enhance the knowledge on the mechanics of multilayer structures formed by using the 3A method and expand its commercial applications.

关键词： finite element method (FEM)     strain analysis     multilayer sheet forming    

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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    

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东太湖湖泊水面萎缩的状况及影响

魏清福

《中国工程科学》 2010年 第12卷 第6期   页码 123-126

摘要：

东太湖是长江中下游地区典型的草型湖泊，是太湖的浅水湖湾和主要出水通道，也是上海市、浙江省杭嘉湖城镇供水取水口的主要来水水源和江苏省吴江市的供水水源地，具有防洪、供水、水生态环境保护和水产养殖等多种功能。近半个世纪以来在自然和人为因素的长期作用下，东太湖水面不断缩小，湖泊形态和水生态环境遭到严重破坏，湖泊衰亡进程加快，其行洪、供水、水生态环境保护等湖泊良好的服务功能无法正常发挥。回顾东太湖的演变历程，初步探讨了东太湖水面萎缩的现状及对湖泊功能的影响，并针对目前规划采取的治理措施提出了几点看法，供湖泊治理参考。

关键词： 东太湖     水面     萎缩     影响     关键技术    

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微型医疗设备变得更智能

Chris Palmer

《工程（英文）》 2021年 第7卷 第1期   页码 8-10 doi: 10.1016/j.eng.2020.12.004

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A hierarchical system to predict behavior of soil and cantilever sheet wall by data-driven models

Nang Duc BUI; Hieu Chi PHAN; Tiep Duc PHAM; Ashutosh Sutra DHAR

《结构与土木工程前沿（英文）》 2022年 第16卷 第6期   页码 667-684 doi: 10.1007/s11709-022-0822-4

摘要： The study proposes a framework combining machine learning (ML) models into a logical hierarchical system which evaluates the stability of the sheet wall before other predictions. The study uses the hardening soil (HS) model to develop a 200-sample finite element analysis (FEA) database, to develop the ML models. Consequently, a system containing three trained ML models is proposed to first predict the stability status (random forest classification, RFC) followed by 1) the cantilever top horizontal displacement of sheet wall (artificial neural network regression models, RANN1) and 2) vertical settlement of soil (RANN2). The uncertainty of this data-driven system is partially investigated by developing 1000 RFC models, based on the application of random sampling technique in the data splitting process. Investigation on the distribution of the evaluation metrics reveals negative skewed data toward the 1.0000 value. This implies a high performance of RFC on the database with medians of accuracy, precision, and recall, on test set are 1.0000, 1.0000, and 0.92857, respectively. The regression ANN models have coefficient of determinations on test set, as high as 0.9521 for RANN1, and 0.9988 for RANN2, respectively. The parametric study for these regressions is also provided to evaluate the relative insight influence of inputs to output.

关键词： finite element analysis     cantilever sheet wall     machine learning     artificial neural network     random forest    

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Finite element simulations of sheet metal forming under complex strain paths

CHEN Wei, YANG Jichang, WU Xiaofeng, LU Dun, GUO Weigang

《机械工程前沿（英文）》 2007年 第2卷 第4期   页码 399-403 doi: 10.1007/s11465-007-0069-8

摘要： Fracture is a common defect in sheet metal forming and it is essentially caused by tensile instability. This paper analyzes some experiments and theories for building forming limit diagrams of sheet metal and points out the advantages and disadvantages of current experiments and theories. According to this, a method that integrates the finite element simulation and experiment was used to research the forming limit diagrams of the sheet metal under complex strain paths. Taking the rear hanger that undergoes twice stamping as an example, the strain paths of the dangerous point of the rear hanger is investigated. Finally, the forming method of the rear hanger is confirmed. Results indicate that finite element method (FEM) can achieve the complex strain paths and different strain paths will have great impacts on the result of the sheet metal forming.

关键词： dangerous     forming method     different     hanger     forming    

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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    

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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    

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Electro-assisted CNTs/ceramic flat sheet ultrafiltration membrane for enhanced antifouling and separation

Shuo Wei, Lei Du, Shuo Chen, Hongtao Yu, Xie Quan

《环境科学与工程前沿（英文）》 2021年 第15卷 第1期 doi: 10.1007/s11783-020-1303-4

摘要： Abstract • A stable and electroconductive CNTs/ceramic membrane was fabricated. • The membrane with the electro-assistance exhibited optimal fouling mitigation. • The removal efficiency was improved by the -2.0 V electro-assistance. • Electro-assisted filtration is energy-saving than that of commercial membrane. Ultrafiltration is employed as an important process for water treatment and reuse, which is of great significance to alleviate the shortage of water resources. However, it suffers from severe membrane fouling and the trade-off between selectivity and permeability. In this work, a CNTs/ceramic flat sheet ultrafiltration membrane coupled with electro-assistance was developed for improving the antifouling and separation performance. The CNTs/ceramic flat sheet membrane was fabricated by coating cross-linked CNTs on ceramic membrane, featuring a good electroconductivity of 764.75 S/m. In the filtration of natural water, the permeate flux of the membrane with the cell voltage of -2.0 V was 1.8 times higher than that of the membrane without electro-assistance and 5.7-fold greater than that of the PVDF commercial membrane. Benefiting from the electro-assistance, the removal efficiency of the typical antibiotics was improved by 50%. Furthermore, the electro-assisted membrane filtration process showed 70% reduction in energy consumption compared with the filtration process of the commercial membrane. This work offers a feasible approach for membrane fouling mitigation and effluent quality improvement and suggests that the electro-assisted CNTs/ceramic membrane filtration process has great potential in the application of water treatment.

关键词： Ultrafiltration     Electro-assistance     CNTs     Membrane fouling mitigation    

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汽车板精益成形技术

林忠钦,李淑慧,王武荣,来新民

《中国工程科学》 2009年 第11卷 第11期   页码 22-29

摘要：

建立了面向零件成形特征的合理选材方法，发明了高效的拉延筋阻力混合优化设计方法，构建了变压边力控制实验平台。从降低成形质量对材料和工艺过程波动敏感性的角度出发，研究面向材料和工艺参数随机波动的成形质量的稳健控制。形成了基于“合理选材、工艺优化、稳健设计”思想的汽车板精益成形技术体系。通过在宝钢股份和多家汽车厂10多年的成功应用，支持宝钢汽车板的市场占有率稳步达到50 %，有效地推动了国产汽车板使用技术的发展。

关键词： 汽车板     精益成形     合理选材     工艺优化     稳健设计    

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板面弹性压板力对提升板料失稳临界应力的作用及其应用

宋爱平,王隆太,李吉中,王树峰

《中国工程科学》 2009年 第11卷 第2期   页码 53-59

摘要：

从分析矩形薄板的受压失稳临界应力入手，提出在冲压成形板料的上下面设置弹性压板力，从而提 升板料的失稳临界应力，减少板料的受压屈曲与起皱。根据这个原理设计的新型冲压模具可有效地控制板 料的起皱，同时具有“一模多用”的作用。试验也表明，具有板面多点压板功能的冲压模具，可以显著地提升 板料的失稳临界应力，减少板料的起皱。

关键词： 起皱     临界应力     模具     冲压工艺    

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标题 作者 时间 类型 操作

Effects of radiation and heat source/sink on unsteady MHD boundary layer flow and heat transfer over a shrinkingsheet with suction/injection

Krishnendu Bhattacharyya

期刊论文

Formation mechanism and modeling of surface waviness in incremental sheet forming

期刊论文

Establishment and verification of a shrinking core model for dilute acid hydrolysis of lignocellulose

Cunwen WANG, Xiaoling DUAN, Weiguo WANG, Zihao LI, Yuanhang QIN

期刊论文

Combination form analysis and experimental study of mechanical properties on steel sheet glass fiber

期刊论文

FEM-based strain analysis study for multilayer sheet forming process

Rongjing ZHANG,Lihui LANG,Rizwan ZAFAR

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

东太湖湖泊水面萎缩的状况及影响

魏清福

期刊论文

微型医疗设备变得更智能

Chris Palmer

期刊论文

A hierarchical system to predict behavior of soil and cantilever sheet wall by data-driven models

Nang Duc BUI; Hieu Chi PHAN; Tiep Duc PHAM; Ashutosh Sutra DHAR

期刊论文

Finite element simulations of sheet metal forming under complex strain paths

CHEN Wei, YANG Jichang, WU Xiaofeng, LU Dun, GUO Weigang

期刊论文

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

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

Electro-assisted CNTs/ceramic flat sheet ultrafiltration membrane for enhanced antifouling and separation

Shuo Wei, Lei Du, Shuo Chen, Hongtao Yu, Xie Quan

期刊论文

汽车板精益成形技术

林忠钦,李淑慧,王武荣,来新民

期刊论文

板面弹性压板力对提升板料失稳临界应力的作用及其应用

宋爱平,王隆太,李吉中,王树峰

期刊论文