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Strengthening and stress drop of ultrafine grain aluminum after annealing

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Transactions of Nonferrous Metals Society of China 2010年第11期20卷 2139-2142页

作者：任江伟单爱党 School of Materials Engineering Shanghai University of Engineering Science School of Materials Science and Engineering Shanghai Jiao Tong University

Ultrafine grain pure aluminum was produced by equal channel angular pressing and cold rolling, the deformed aluminum was annealed at 200 ℃ for 1 h. The tensile curves of deformed and annealed aluminum show that yield strength of deformed aluminum increases by 100%-300% and its elongation decreases by about 20%. After low temperature annealing, strength of annealed aluminum increases by 20% and elongation decreases by over 50%, the recovery of dislocations may be the main cause of annealing strengthening. In addition, there is an abrupt stress drop in the tensile curves of annealed aluminum and the formation of shear band is responsible for it.

关键词： aluminum ultraftne grain mechanical properties heat treatment

Electromechanical responses and instability of electro-active polymer cylindrical shells

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Applied Mathematics and Mechanics(English Edition) 2016年第8期37卷 1067-1076页

作者： Jiusheng REN Chengmin WANG Department of Mechanics Shanghai Key Laboratory of Mechanics in Energy and Environment EngineeringShanghai University shanghai Institute of Applied Mathematics and Mechanics Shanghai University

Based on the theories of finite deformation elasticity, electromechanical responses and instability of an incompressible electro-active polymer （EAP） cylindrical shell, which is subjected to an internal pressure and a static electric field, are studied. Deformation curves and distribution of stresses are obtained. It is found that an internal pressure together with an electric field may cause the unstable non-monotonic deforma- tion of the shell. It is also shown that a critical thickness for the shell exists, and the shell may undergo the unstable deformation if its thickness is less than this critical value. In addition, the effects of the electric field, axial stretch, thickness, and internal pressure on the instability of the shell are discussed.

关键词： electro-active polymer (EAP) electromechanical instability finite deformation elastic theory non-monotonic critical thickness

Changes during late-stage embryonic development from egg-juvenile to free-living hatchling in Chinese freshwater crab Sinopotamon yangtsekiense (Decapoda, Brachyura, Potamidae)

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Chinese Journal of Oceanology and Limnology 2013年第3期31卷 542-551页

作者：薛俊增刘艳 Neil CUMBERLIDGE 吴惠仙 Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources Shanghai Ocean University Department of Biology Northern Michigan UniversityMarquette

This study expands on recent reports that direct development in the Chinese potamid freshwater crab Sinopotamon yangtsekiense involves the completion of all brachyuran larval stages (nauplius, zoea, and megalopa) inside the egg case during embryonic development. Detailed studies of embryonic development in this species revealed the presence of an additional larval stage (the egg-juvenile) between the megalopa and the free-living hatchling crab. We described and compared the appendages of the head, thorax, and abdomen of the egg-juvenile with those of the hatchling crab in S. yangtsekiense. Significant differences were found between most of the appendages of these two stages with a soft exoskeleton in the egg-juvenile, no joint articulation, a slimmer appearance, and a lack of setae when compared with the newly emerged free-living hatchling crab. These modifications of the appendages are related to the confinement within the egg case of the egg-megalopa and egg-juvenile during direct development, and the need for the free-living hatchling freshwater crab to move, feed, and respire. In marine crabs, the megalopa gives rise to the first crab stage whereas in freshwater crabs the egg-juvenile follows the megalopa and immediately precedes the free-living first crab stage.

关键词： Sinopotamon yangtsekiense freshwater crab embryonic development egg-juvenile hatchlingcrab appendage

Influences of Marangoni effect on solidification of curved interfaces with constant curvature

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Applied Mathematics and Mechanics(English Edition) 2008年第2期29卷 145-151页

作者：胡国辉周哲玮 shanghai Institute of Applied Mathematics and Mechanics Shanghai University shanghai Key Laboratory of Mechanics in Energy and Environment Engineering Shanghai 200072P.R.China

The asymptotic method and phase field simulation are applied to study the influences of variation of the surface tension with temperature on the movements of solid-liquid interfaces in the solidification process of spherical and cylindrical nuclei, respectively. Results indicate that Marangoni effect will increase the critical nucleation radius, slow up the movement of interface. The tip speed of dendrite decreases linearly with Marangoni number for melt without convection. The results of phase field simulation are qualitatively in accord with that of asymptotic method.

关键词： solidification phase field simulation Marangoni effect asymptotic method wcrystal growth

The role of capsule endoscopy combined with double-balloon enteroscopy in diagnosis of small bowel diseases

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Chinese Medical Journal 2007年第1期120卷 30-35页

作者： LI Xiao-bo GE Zhi-zheng DAI Jun GAO Yun-jie LIU Wen-zhong HU Yun-biao XIAO Shu-dong Department of Gastroenterology Renji Hospital Medical Collegeof Shanghai Jiaotong University Shanghai Institute of DigestiveDiseases Shanghai 200001 China

Background The diagnosis of small bowel diseases remains relatively inefficient using traditional imaging techniques. Capsule endoscopy （CE） and double-balloon enteroscopy （DBE） are two novel methods of enteroscopy for examining the entire small bowel. The aim of this study was to evaluate the detection rate and diagnostic accuracy of CE and DBE in patients with suspected small bowel diseases and to investigate the clinical significance of combined use of these two novel modalities. Methods Two hundred and eighteen patients were evaluated for suspected small bowel disease, including 116 with obscure gastrointestinal bleeding and 102 with obscure abdominal pain or chronic diarrhea. One hundred and sixty-five out of these patients underwent CE first and 53 patients underwent DBE （under anesthesia with propofol） first. DBE was recommended after negative or equivocal evaluation on CE and vise versa. Introduction of the endoscope during DBE was either orally or anally and the patients were referred for a second procedure using the opposite route several days later when no abnormalities were found on the first procedure. The detection rates, diagnostic accuracy, tolerance and frequency of adverse events of these two modalities were then analyzed. Results Failure of the procedure was seen in one patient with CE and in two patients with DBE. Sixty-four DBE procedures were carded out in 51 patients; by the oral route in 34 cases, the anal route in 4 and both routes in 13 cases. The overall detection rate of small bowel diseases using CE （72.0%, 118/164） was superior to that with DBE （41.2%, 21/51）; X2=16.1218, P〈0.0001. The diagnostic rate （51.8%, 85/164） was also higher than that with the latter procedure （39.2%, 20/51）, but was not significantly different （X^2=2.4771, P〉0.05）. Furthermore, the detection rate of small bowel diseases in patients with obscure gastrointestinal bleeding using CE （88.0%, 88/100） was superior to that of DBE （60.0%, 9/15）; X2=7.7457, P=0.0054. Les

关键词： capsule endoscopy double-balloon enteroscopy small intestinal disease obscure gastrointestinal bleeding

Fluid-structure interaction simulation of three-dimensional flexible hydrofoil in water tunnel

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Applied Mathematics and Mechanics(English Edition) 2016年第1期37卷 15-26页

作者： Shiliang HU Chuanjing LU Yousheng HE Department of Engineering Mechanics Shanghai Jiao Tong University Ministry of Education (MOE) Key Laboratory of Hydrodynamics Shanghai Jiao Tong University

The closely coupled approach combined with the finite volume method （FVM） solver and the finite element method （FEM） solver is used to investigate the fluid-structure interaction （FSI） of a three-dimensional cantilevered hydrofoil in the water tunnel. The FVM solver and the coupled approach are verified and validated by compar- ing the numerical predictions with the experimental measurements, and good agreement is obtained concerning both the lift on the foil and the tip displacement. In the noncav- itating flow, the result indicates that the growth of the initial incidence angle and the Reynolds number improves the deformation of the foil, and the lift on the foil is increased by the twist deformation. The normalized twist angle and displacement along the span of the hydrofoil for different incidence angles and Reynolds numbers are almost uniform. For the cavitation flow, it is shown that the small amplitude vibration of the foil has limited influence on the developing process of the partial cavity, and the quasi two-dimensional cavity shedding does not change the deformation mode of the hydrofoil. However, the frequency spectrum of the lift on the foil contains the frequency which is associated with the first bend frequency of the hydrofoil.

关键词： closely coupled approach fluid-structure interaction (FSI) hydrofoil,cavitation

Magnetic Behavior of Ferri-ferromagnetic Alloy in Presence of External Magnetic Field

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Communications in Theoretical Physics 2008年第4期49卷 1059-1063页

作者： HU Hong-Liang XIN Zi-Hua LIU Wei-Jie Department of Physics Shanghai University Shanghai 200444~ China

The magnetic behavior of the mixed ferro-ferrimagnetie alloy with （Aa Bb Cc）y D structure composed of Ising spins SA=1, SB = 5/2, SC= 2, and SD = 3/2 in the presence of the external magnetic field is investigated by the use of the effective field theory. The role of concentration b is discussed in this system in detail. Results show that for a =0.4, only when the concentration b is in the region 0.60 ≥b 〉 0.34 can the ferrimagnetic behavior be seen. Otherwise, the alloy shows ferromagnetic behavior.

关键词： magnetic susceptibility magnetization Prussian blue analogs effective field theory

Amino Acids Production from Fish Proteins Hydrolysis in Subcritical Water

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Chinese Journal of Chemical Engineering 2008年第3期16卷 456-460页

作者：朱宪朱超赵亮程洪斌 Department of Chemical Engineering School of Environment and Chemical Engineering Shanghai University Shanghai 201800 China

The hydrolysis technology and reaction kinetics for amino acids production from fish proteins in subcritical water reactor without catalysts were investigated in a reactor with volume of 400 ml under the conditions of reaction temperature from 180-320℃, pressure from 5-26 MPa, and time from 5-60 rain. The quality and quantity of amino acids in hydrolysate were determined by bioLiquid chromatography, and 17 kinds of amino acids were obtained. For the important 8 amino acids, the experiments were conducted to examine the effects of reaction temperature, pressure and time on amino acids yield. The optimum conditions for high yield are obtained from the experimental results. It is found that the nitrogen and carbon dioxide atmosphere should be used for leucine, isoleucine and histidine production while the air atmosphere might be used for other amino acids. The reaction time of 30 rain and the experimental temperature of 220℃, 240℃ and 260℃ were adopted for reaction kinetic research. The total yield of amino acids versus reaction time have been examined experimentally. According to these experimental data and under the condition of water excess, the macroscopic reaction kinetic equation of fish proteins hydrolysis was obtained with the hydrolysis reaction order of 1.615 and the rate constants being 0.0017, 0.0045 and 0.0097 at 220℃, 240℃ and 260℃ respectively. The activation energy is 145.1 kJ·mol^- 1.

关键词： biomass subcritical water hydrolysis reaction kinetics amino acids

INTERFACE EFFECT ON THE EFFECTIVE BULK MODULUS OF A PARTICLE-REINFORCED COMPOSITE

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Acta Mechanica Sinica 2004年第6期20卷 676-679页

作者：孙黎武义明黄筑平王建祥 LTCS and Department of Mechanics and Engineering Science Peking UniversityBeijing 100871China

Classical micromechanical methods for calculating the effective moduli of a heteroge- neous material are generalized to include the interface(surface)*** using Hashin's Composite Sphere Assemblage(CSA)model,a new expression of the bulk modulus for a particle-reinforced com- posite is *** is emphasized that the present study is within the finite-deformation framework such that the effective properties are not influenced by the interface stress itself solely,but influenced by the change of the interface stress due to changes of the shape and size of the *** some inadequacies in previous papers are pointed out.

关键词： effective bulk modulus interface effect Hashin's Composite Sphere Assemblage