检索结果-内蒙古大学图书馆

Crashworthiness optimization of thin-walled rail with different collision boundary conditions

Open Mechanical engineering Journal 2015年第1期9卷 558-563页

作者： Wu, Hequan Cao, Libo Mao, Hongfeng State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Changsha China Key Laboratory of Lightweight and Reliability Technology for Engineering Vehicle College of Hunan province Changsha University of Science and Technology Changsha China

As the world automotive crash safety regulations are different, it’s very important to design the energy absorbing structures that satisfy different collision boundary conditions. A large number of vehicle energy absorption beams dimensions were measured and then a common thin-walled rail was chosen. Considering the complexity of automobile collision boundary, finite element analysis and experimental design, interval uncertain algorithms, Kriging approximate model, NSGA - II genetic algorithm were combined to optimize the structure of the thin-walled rail with different impact velocity and different impact angle. Then the Pareto optimal solution was obtained. Thin walled beam after optimization has good energy absorption characteristics under different collision boundary conditions. Research results provide a method for the designing of a car that meets various crash regulations at the same time. © Gong et al.

关键词： Boundary conditions

来源：评论

学校读者我要写书评

暂无评论

Di-tert-butyl Peroxide-Promoted α-Alkylation of α-Amino Carbonyl Compounds by Simple Alkanes

引用

JOURNAL OF ORGANIC CHEMISTRY 2014年第20期79卷 9847-9853页

作者： Peng, Haibo Yu, Jin-Tao Jiang, Yan Yang, Haitao Cheng, Jiang Changzhou Univ Jiangsu Prov Key Lab Fine Petrochem Engn Jiangsu Key Lab Adv Catalyt Mat & Technol Sch Petrochem Engn Changzhou 213164 Peoples R China Nanjing Univ State Key Lab Coordinat Chem Nanjing 210093 Jiangsu Peoples R China

A di-tert butyl peroxide (DTBP)-promoted alpha-alkylation of alpha-amino carbonyl compounds by simple alkanes is developed, proceeding through dual sp(3) C-H bonds cleavage. The reaction was applicable for alpha-amino ketones and alpha-amino esters, providing a facile pathway for the alpha-functionalization of these substrates. The radical pathway is involved in this transformation.

关键词： Column chromatography Silica Ethers Gels Ethyl groups

来源：评论

学校读者我要写书评

暂无评论

High resolution radar target recognition based on distributed glint

High resolution radar target recognition based on distribute...

引用

2013 International Conference on Mechatronics and Automatic Control Systems, ICMS 2013

作者： Li, Baoguo Qi, Zongfeng Zhou, Ying Lei, Jing State Key Lab. of Complex Electromagnetic Environ. Effects on Electronics and Info. System of China Luoyang China School of Electronic Science and Engineering National University of Defense Technology Changsha China

ISBN: (纸本)9783319012728

To solve the problem of aspect angle sensitivity of range profile while used in radar target recognition, the concept "distributed glint" is presented for high resolution radar. The detailed deducing procedure of "distributed glint" is given through theoretical analysis. A new target recognition strategy based on range profile and distributed glint is proposed. Computer simulation proves that this method can greatly enhance the performance of recognition strategy based on range profile. © Springer International Publishing Switzerland 2014.

关键词： Radar target recognition

来源：评论

学校读者我要写书评

暂无评论

Numerical simulation of failure modes of concrete gravity dams subjected to underwater explosion

引用

engineering FAILURE ANALYSIS 2014年 36卷 49-64页

作者： Zhang, Sherong Wang, Gaohui Wang, Chao Pang, Bohui Du, Chengbo Tianjin Univ State Key Lab Hydraul Engn Simulat & Safety Tianjin 300072 Peoples R China

The failure modes of concrete gravity dams under blast loading are the key problems to evaluate the antiknock safety of the dam. Dynamic failure process of structures under blast loading is much more complicated than that under other loadings such as static and earthquake loadings. Many researchers have conducted comprehensive experimental and numerical investigations of civil structures' response to blast loading. However, corresponding studies of concrete gravity dams are limited. This paper performs numerical simulation of antiknock performance and failure modes of concrete gravity dams under blast loading. Firstly, the pressure and impulse produced by underwater explosion are calculated. The numerical results are verified by comparing with analytical expressions in different scaled distances. By analyzing the effects of mesh size, some interesting conclusions regarding the mesh size for actual events are obtained. Subsequently, the possible failure modes of concrete gravity dams subjected to underwater explosion are discussed. Strain rate effect of concrete materials is also taken into consideration in establishing the fully coupled model of the gravity dam. The dynamic response of the dam subjected to underwater explosion is performed for different dam heights, varying from 30 to 142 m. The influence of the dam height, standoff distance and the upstream water level on the antiknock performance of the dam is also investigated. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Concrete gravity dam Failure mode Mesh size effect Antiknock performance Underwater explosion

来源：评论

学校读者我要写书评

暂无评论

Investigation of the shock wave propagation characteristics and cavitation effects of underwater explosion near boundaries

引用

APPLIED OCEAN RESEARCH 2014年 46卷 40-53页

作者： Wang, Gaohui Zhang, Sherong Yu, Mao Li, Hongbi Kong, Yuan Tianjin Univ State Key Lab Hydraul Engn Simulat & Safety Tianjin 300072 Peoples R China

The shock wave propagation characteristics of underwater explosion have been of great interest to researchers. While the physical processes during an underwater explosion near boundaries are extremely complex, which involve lots of complex issues such as the explosion, shock wave propagation, water-air or water-structure interaction, etc. After the underwater detonation of an explosive, the shock wave may approach two main types of boundaries: the free surface of the water and the fluid-structure interface. The presence of these boundaries will significantly affect the wave propagation phenomena, and lead to bulk cavitation near the free surface or the structure surface. This paper deals with the behavior of shock wave propagation and cavitation from underwater explosion near different boundaries. A coupled numerical approach with combined Lagrangian and Eulerian methods is used to simulate the water-air interface and shock wave-structure interaction. A numerical model of free-field explosion in water is established, and the results have been compared with the published empirical formulas to verify the results of numerical solutions. The shock wave propagation characteristics from explosions in water near different boundaries are simulated and compared. In addition, the unsteady cavitations just near the free surface and the structure surface are described and captured. The water-air and water-structure interaction effects are examined. The results show that the free surface and structure surface boundaries have significant influence on the shock wave propagation characteristics. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Underwater explosion Air explosion Free surface Structure surface Explosion shock loading Shock wave propagation

来源：评论

学校读者我要写书评

暂无评论

Damage prediction of concrete gravity dams subjected to underwater explosion shock loading

引用

engineering FAILURE ANALYSIS 2014年 39卷 72-91页

作者： Wang, Gaohui Zhang, Sherong Tianjin Univ State Key Lab Hydraul Engn Simulat & Safety Tianjin 300072 Peoples R China

The damage prediction of concrete gravity dams under blast loads has gained importance in recent years due to the great number of accidental events and terrorist bombing attacks that affected engineering safety. It has long been known that an underwater explosion can cause significantly more damage to the targets in water than the same amount of explosive in air. While the physical processes during an underwater explosion and the subsequent response of structures are extremely complex, which involve lots of complex issues such as the explosion, shock wave propagation, shock wave-structure interaction and structural response. Hence a sophisticated numerical model for the loading and material responses would be required to enable more realistic reproduction of the underlying physical processes. In this paper, a fully coupled numerical approach with combined Lagrangian and Eulerian methods, incorporating the explosion processes, is performed. The RHT (RiedelHiermaier-Thoma) model including the strain rate effect is employed to model the concrete material behavior subjected to blast loading. Detailed numerical simulation and analysis of a typical concrete gravity dam subjected to underwater explosion are presented in this study. In terms of different TNT charge weights, the structural response and damage characteristics of the dam at different standoff distances are investigated. Based on the numerical results, critical curves related to different damage levels are derived. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Concrete gravity dam Underwater explosion Damage prediction Shock wave propagation Coupled model

来源：评论

学校读者我要写书评

暂无评论

Deformation behaviour and 6H-LPSO structure formation at nanoindentation in lamellar high Nb containing TiAl alloy

引用

PHILOSOPHICAL MAGAZINE LETTERS 2015年第2期95卷 85-91页

作者： Song, L. Xu, X. J. Peng, C. Wang, Y. L. Liang, Y. F. Shang, S. L. Liu, Z. K. Lin, J. P. Univ Sci & Technol Beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China Zhongyuan Univ Technol Mat & Chem Sch Zhengzhou 450007 Peoples R China Penn State Univ Dept Mat Sci & Engn University Pk PA 16802 USA

Microstructure and deformation mechanisms at a nanoindentation in the lamellar colony of high Nb containing TiAl alloy have been studied using the focused ion beam and the transmission electron microscopy. Considerable deformation twins are observed around the nanoindentation, and a strain gradient is generated. A continuous change in the bending angle of the lamellar structure can be derived, and a strain-induced grain refinement process is observed as various active deformations split the gamma grains into subgrains. In addition to all possible deformation mechanisms (ordinary dislocation, super-dislocation and deformation twining) activated due to the heavy plastic deformation, a 6-layer hexagonal (6H) long-period stacking ordered structure is identified for the first time near the contact zone and is thought to be closely related to the glide of partial dislocations.

关键词： titanium aluminide nanoindentation transmission electron microscopy long-period stacking ordered structure

来源：评论

学校读者我要写书评

暂无评论

Study on the Development of ZIF-8 Membranes for Gasoline Vapor Recovery

引用

INDUSTRIAL & engineering CHEMISTRY RESEARCH 2014年第9期53卷 3662-3668页

作者： Li, Jing Zhong, Jing Huang, Weiqiu Xu, Rong Zhang, Qi Shao, Hui Gu, Xuehong Changzhou Univ Sch Petrochem Engn Jiangsu Key Lab Adv Catalyt Mat & Technol Changzhou 213164 Peoples R China Changzhou Univ Sch Petr Engn Changzhou 213016 Peoples R China Nanjing Univ Technol State Key Lab Mat Oriented Chem Engn Nanjing 210009 Peoples R China

The recovery of gasoline vapor is still a major challenge in the petrochemical industry. In this study, a zeolitic imidazolate frameworks (ZIFs) membrane has been developed and first applied to gasoline vapor recovery. Zeolitic imidazole framework (ZIF-8) membranes were fabricated by a facile solvothermal seed growth method on ZrO2 supports. X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis measurements were conducted to study the morphologies, structure, and physical and chemical properties of ZIF-8 membranes. The effects of trans-membrane pressure drop, operating temperature, feed concentration, and stage cut on the separation performances of ZIF-8 membranes were systematically investigated. At 293 K, the ZIF-8 membrane showed an optimum n-hexane (n-C6H14) permeance of 7.16 X 10(-8) mol/(m(2).***) with the corresponding separation factor of 2.46 for the nitrogen/n-hexane model mixtures at a trans-membrane pressure drop of 0.05 MPa, a stage cut of 0.293, and a n-hexane volume fraction of 30%. Moreover, the separation factor for the multicomponent alkanes decreased with increasing the number of n-alkanes because of competitive adsorption of the n-alkanes in membrane pores.. Experimental results indicated that the ZIF-8 membrane is a fairly promising candidate for the application in gasoline vapor recovery.

关键词： Coating materials Membranes Metal organic frameworks Mixtures Interface engineering

来源：评论

学校读者我要写书评

暂无评论

Synthesis of amino-functionalized mesoporous alumina with enhanced affinity towards Cr(VI) and CO₂

引用

CHEMICAL engineering JOURNAL 2014年 239卷 207-215页

作者： Cai, Weiquan Tan, Lijun Yu, Jiaguo Jaroniec, Mietek Liu, Xiaoqin Cheng, Bei Verpoort, Francis Wuhan Univ Technol Sch Chem Engn State Key Lab Adv Technol Mat Synth & Proc Wuhan 430070 Hubei Peoples R China Kent State Univ Dept Chem & Biochem Kent OH 44242 USA Nanjing Univ Technol State Key Lab Mat Oriented Chem Engn Nanjing 210009 Jiangsu Peoples R China

Amino-functionalized mesoporous alumina (MA) with enhanced affinity towards Cr(VI) and CO2 was successfully synthesized by Pluronic P123-assisted sol-gel method, followed by impregnation process to extract the polymeric template and load tetraethylenepentamine (TEPA) simultaneously. The physicochemical and adsorption properties of MA without and with TEPA were comparatively characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), N-2 adsorption-desorption, X-ray photoelectron spectroscopy (XPS), UV/Vis and temperature programmed desorption of CO2 (CO2-TPD) techniques. Adsorption kinetics for Cr(VI) on mesoporous P123-alumina composites before (PA) and after (PA-TEPA) treatment with TEPA were described by pseudo-second-order and pseudo-first-order kinetics, respectively;while, their adsorption equilibrium isotherms were described reasonably well by Langmuir model. PA-TEPA with specific surface area of 67.4 m(2) g(-1) could be considered as a bifunctional adsorbent showing high adsorption capacity of 59.5 mg g(-1) and extremely fast adsorption kinetics with percentage removal of 92% within 0.5 min for Cr(VI) at an optimal pH = 2, and decent adsorption capacity of 0.7 mmol g(-1) for CO2 at room temperature. The presence of amino functionality in PA-TEPA is essential for both Cr(VI) and CO2 adsorption, which make this material an effective bifunctional adsorbent for environmental applications. (C) 2013 Elsevier B.V. All rights reserved.

关键词： Amino-functionalization Mesoporous alumina Adsorption Cr(VI) CO2

来源：评论

学校读者我要写书评

暂无评论

Mechanical model and stability mechanism of the interaction system of tunnel and slope at tunnel entrances during construction period

引用

International Journal of Earth Sciences and engineering 2015年第6期8卷 3051-3061页

作者： Zhang, She-Rong Yu, Xiang Rong Wang, Chao Pan, Fei State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin University Tianjin300072 China School of Civil Engineering Tianjin University Tianjin300072 China

Structural design and construction of the interaction system of tunnel and slope at tunnel entrances, which have been complicated processes, are affected by many factors during the construction period of tunnel entrances with unfavorable geological conditions, and lacks references in similar engineering. This work focuses on the influences of the position of the tunnel axis relative to the directions in which slopes move on deformation destabilization of a tunnel-slope system;on the one hand, considering the interactional mechanism of tunnel and slope, on the other hand, associating construction sequence with 3D nonlinear characteristics. Then, the mechanical model of the interaction between slope and tunnel is established. This work also researches the temporal-spatial characteristics of the stability of the tunnel-slope system, taking the three-dimensional effect and the corresponding dynamic construction process of surrounding rock and slope at tunnel entrances into consideration. This method and conclusion provide a useful reference for the optimization of construction organization and the improvement of a construction technique for tunnel entrances with unfavorable geological characteristics. © 2015 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.

关键词： System stability

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：