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Research on nonlinear constitutive relationship of permanent deformation in asphalt pavements

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science china(Physics,Mechanics & Astronomy) 2006年第6期49卷 671-682页

作者： PENG Miaojuan1 & XU Zhihong2 1. Department of Civil engineering,shanghai university,shanghai 200072,china 2. school of Transportation engineering,Tongji university,shanghai 200092,china Department of Civil engineering Shanghai University Shanghai China school of Transportation engineering Tongji University Shanghai China

To predict correctly the rut depths in asphalt pavements,a new nonlinear viscoelastic-elastoplastic constitutive model of permanent deformation in asphalt pave-ments is presented. The model combines a generalized Maxwell model with an elasto-plastic one. Then from the creep theory,the linear and nonlinear constitutive equations of the generalized Maxwell model are obtained. From the nonlinear finite element method for the rutting of the asphalt pavement,the rut depths of 4 asphalt-aggregate mixtures are obtained. And the results are compared with the ones from the finite element method by SHRP and the experiments by SWK/UN. The results in this paper are better than the ones by SHRP,and agree with the ones of the experiment by SWK/UN. This shows that the nonlinear viscoelastic-elastoplastic constitutive model,which is presented in this paper for the rutting of the asphalt pavement,is effective. The properties,such as nonlinear elastic-ity,plasticity,viscoelasticity and nonlinear viscoelasticity,which affect the rutting of an asphalt pavement,can be shown in the model. And the characteristics of the permanent deformation of the asphalt pavement can be presented entirely in the model.

关键词： asphalt pavement,permanent deformation,nonlinear viscoelastic-elastoplastic constitutive relationship,generalized Maxwell model,creep compliance.

Flow Behavior and Evolution of Microstructure during Hot Deformation for a High Mo Stainless Steel

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Journal of Materials science & Technology 2000年第3期16卷 341-344页

作者： Yourong XU, Liangsheng CHEN, Deying WANG and Lei JIN (school of Materials science and engineering, shanghai university, shanghai 201800, china) school of Materials science and engineering Shanghai University Shanghai 201800 China

The mechanical behaviors of high Mo austenitic stainless steel OOCr20Nil8Mo6Cu[N] have been investigated using the methods of hot compression simulation test on the Thermecmaster-Z simulator. The dynamic recrystallization kinetic equation was established, Avrami coefficient n lies in between 0.9～2 depending on deformation parameters. A perfect flow stress model considering dynamic recrystallization was also established. Dynamic recrystallization tends to complete at 1050℃ and high strain rate, but at temperature below 950℃, it is hard to occur. Double-stage interrupt compression tests were carried out. Activation energy for static and metadynamic re-crystallization have been obtained respectively (QSRX=483.7, QMDEX=253.5 kJ/mol). Avrami coefficient of MDRX is about 0.5, and t.0.5-kinetics equations of SRX and MDRX have also been constructed. The evolution of microstructures during interrupt compression deformation was investigated. Static and metadynamic recrystaltlzation is essential to improve plasticity, at temperature above 1000℃ increasing interpass time has advantage for static and metadynamic recrystallization.

关键词： Stainless steel

Mechanically Driven Alloying and Structural Evolution of Nanocrystalline Fe_(60)Cu_(40) Powder

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Journal of Materials science & Technology 1997年第4期13卷 354-358页

作者： Yuanda DONG and Xueming MA(school of Materials science and engineering, shanghai university, shanghai 200072, china)Yuanzheng YANG(Dept. of Mechanical engineering(2), South china university of Technology, Guangzhou 510641, china)Fangxin LIU and Genmiao WA school of Materials science and engineering Shanghai University Shanghai 200072 China Dept. of Mechanical engineering(2) South China University of Technology Guangzhou 510641 China Lab. of Structure Analysis University of Science and Technology of China Hefei 230026 China

Highly supersaturated nanocrystalline fcc Fe60Cu40 alloy has been prepared by mechanical alloying of elemental powders. The phase transformation is monitored by X-ray diffraction (XRD),Mossbauer spectroscopy and extended X-ray absorption fine structure (EXAFS). The powder obtained after milling is of single fcc structure with grain size of nanometer order. The Mossbauer spectra of the milled powder can be fitted by two subspectra whose hyperfine magnetic fields are 16 MA/m and 20 MA/m while that of pure Fe disappeared. EXAFS results show that the radial structure function (RSF) of Fe K-edge changed drastically and finally became similar to that of reference Cu K-edge, while that of Cu K-edge nearly keeps unchanged in the process of milling. These imply that bcc Fe really transforms to fcc structure and alloying between Fe and Cu occurs truly on an atomic scale. EXAFS results indicate that iron atoms tend to segregate at the boundaries and Cu atoms are rich in the fcc lattice. Annealing experiments show that the Fe atoms at the interfaces are easy to cluster to α-Fe at a lower temperature, whereas the iron atoms in the lattice will form γ-Fe first at temperature above 350℃, and then transform to bcc Fe

关键词： Mechanically Driven Alloying and Structural Evolution of Nanocrystalline Fe MA Cu Powder Figure

NUMERICAL SOLUTION FOR TIDAL FLOW IN OPENING CHANNEL USING COMBINED MACCORMACK-FINITE ANALYSIS METHOD

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Journal of Hydrodynamics 2009年第4期21卷 505-511页

作者： WU Zhao-chun WANG Dao-zeng shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China school of Construction and Safety engineering Shanghai Institute of Technology Shanghai 200235 China

A new numerical scheme for solving the tidal flow in an opening channel using the advective-diffusion shallow-water equations as the governing equations is proposed based on the combination of the MacCormack and the finite analysis methods. In the present scheme, the finite analysis method is used to discretize the momentum equation and the MacCormack technique is used to discretize the continuity equation in a single grid system. The matrix of the discretized momentum equation is characterized by predominantly main diagonal elements, which ensures favorable convergence and stability for the numerical simulation by the combined method. To verify the present method, hydraulics simulation is carried out for a section down mainstream of the Huangpu River. The computational results agree with the measured data. By use of orthogonal curvilinear coordinate system, the methods can be easily extended to the numerical simulation of the tidal flow in a tortuous channel.

关键词： MacCormack technique finite analysis method tidal flow shallow water equation numerical simulation

Piezoelectric properties of low loss and high Curie temperature (Bi, La)FeO_3-Pb(Ti, Mn)O_3 ceramics with Mn doping

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Rare Metals 2012年第6期31卷 595-598页

作者： SHI Guiyang, WANG Dalei, BU Shundong, JIN Dengren, and CHENG Jinrong school of Materials science and engineering, shanghai university, shanghai, 200072, china school of Materials science and engineering Shanghai University Shanghai China

Piezoelectric ceramics of 0.6(Bi0.9La0.1)FeO3-0.4Pb(Ti1-xMnx)O3 (BLF-PTM) for x=0, 0.01, 0.02, and 0.03 were prepared by sol-gel process combined with a solid-state reaction method. The tan? for BLF-PTM of x=0.01 is just 0.006 at 1 kHz, drastically decreasing by using Mn dopants. The TC increases to 490 ℃ for BLF-PTM of x=0.02. Furthermore, Mn modification effectively enhances the poling state and the piezoelectric properties of BLF-PTM. The kp, Qm, d33, and g33 of 0.34, 403, and 124 pC1·N-1 and 37×10-3 Vm·N-1 are achieved for BLF-PTM of x=0.01. The results indicate that Mn modified BLF-PTM is a competitive high power and high temperature piezoelectric material with excellent piezoelectric properties.

关键词： piezoelectric property low loss high Curie temperature poling state

Metal chlorides loaded on activated carbon to capture elemental mercury

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Journal of Environmental sciences 2010年第11期22卷 1814-1819页

作者： Zhemin Shen,Jing Ma,Zhijian Mei,Jianda Zhang school of Environmental science and engineering,shanghai Jiao Tong university,shanghai 200240,china school of Environmental science and engineering Shanghai Jiao Tong University Shanghai 200240 China

Activated carbon （AC） was considered to be an effective sorbent to control mercury in combustion systems. However, its capture capacity was low and it required a high carbon-to-mercury mass ratio. AC loaded with catalyst showed a high elemental mercury （Hg 0 ） capture capacity due to large surface area of AC and high oxidization ability of catalyst. In this study, several metal chlorides and metal oxides were used to promote the sorption capacity of AC. As a result, metal chlorides were better than metal oxides loaded on AC to remove gaseous mercury. X-ray diffractometer （XRD）, thermogravimetric analyzer （TGA） and specific surface area by Brunauer- Emmett-Teller method （BET） analysis showed the main mechanisms： first, AC had an enormous surface area for loading enough MClx; second, Cl and MxOy were generated during pyrogenation of MClx; finally, there were lots of active elements such as Cl and MxOy which could react with elemental mercury and convert it to mercury oxide and mercury chloride. The HgO and HgCl 2 might be released from AC’s porous structure by thermo regeneration. A catalytic chemisorption mechanism predominates the sorption process of elemental mercury. As Co and Mn were valence variable metal elements, their catalytic effect on Hg 0 oxidization may accelerate both oxidation and halogenation of Hg 0 . The sorbents loaded with metal chlorides possessed a synergistic function of catalytic effect of valence variable metal and chlorine oxidation.

关键词： mercury activated carbon flue gas metal chloride metal oxide

Spatial continuity incorporated multi-attribute fuzzy clustering algorithm for blood vessels segmentation

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science china(Information sciences) 2010年第4期53卷 752-759页

作者： HAO JuTao1*, ZHAO JingJing2 & LI MingLu3 1school of Optical-Electrical and computer engineering, university of shanghai for science and Technology, shanghai 200093, china 2Department of Electrical engineering, shanghai university of Electric Power, shanghai 200090, china 3Department of computer science and engineering, shanghai Jiaotong university, shanghai 200240, china school of Optical-Electrical and computer engineering University of Shanghai for Science and Technology Shanghai China Department of Electrical engineering Shanghai University of Electric Power Shanghai China Department of computer science and engineering Shanghai Jiaotong University Shanghai China

A three-dimensional representation of vasculature can be extremely important in image-guided neurosurgery, pre-surgical planning. In this paper, a spatial continuity incorporated multi-attribute fuzzy clustering algorithm (MAFCM S) is proposed to segment entire blood vessels from TOF MRA images. This clustering method takes both the intensity information and the geometrical information into account, while most of the cur- rent clustering methods only deal with the former. In this method, a new dissimilarity measure, which integrates the intensity and the geometry shape dissimilarity, is introduced. Because of the presence of the geometrical information, the new measure is able to differentiate the pixels with similar intensity values within different geometrical shape structures. Experimental results show that the new algorithm can get better segmentation.

关键词： fuzzy c-means clustering scale space analysis spatial continuity blood vessel segmentation multi-attribute fuzzy clustering

Study on rare earth/alkaline earth oxide-doped CeO_2 solid electrolyte

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Rare Metals 2007年第4期26卷 311-316页

作者： YAN Kai ZHEN Qiang Song Xiwen school of Materials science and engineering Shanghai University Shanghai 200072 China Research Center of Nanoscience and Nanotechnology Shanghai Univeesity Shanghai 200444 China school of Materials science and engineering Inner Mongolia University of Science and Technology B aotou 014010 China

Five types of rare earth/alkaline earth oxide-doped CeO2 superfine-powders were synthesized by a low-temperature combustion technique. The relevant solid electrolyte materials were also sintered by pressureless sintering at different temperatures. The results of X-ray diffraction and transmission electron microscopy showed that the grain size of the powders was approximately 20-30 nm, and rare earth/alkaline earth oxides were completely dissolved into ceria-based solid solution with fluorite structure. The electrical conductivities of the SmzO3-CeO2 system were measured by the ac impedance technique in air at temperatures ranging from 513-900℃. The results indicated that the ionic conductivities of Srno.2oCe0.8Ol.875 solid electrolyte increase with increasing sintering temperature, and the relationship between the conductivities and measuring temperature obeys the An＇henius equation. Then the SmzO3-CeO2 material was further doped with other rare earth/alkaline earth oxide, and the conductivities improve with the effective index.

关键词： doped ceria rare earth/alkaline earth oxide solid electrolyte conductivity effective index

Protein Secondary Structure Prediction Using Dynamic Programming

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Acta Biochimica et Biophysica Sinica 2005年第3期37卷 167-172页

作者： Jing ZHAO Pei-Ming SONG Qing FANG Jian-Hua LUO school of Life science & Technology,shanghai Jiaotong university,shanghai 200240,china shanghai Center for Bioinformation and Technology,shanghai 200235,china Logistical engineering university,Chongqing 400016,china school of Life science & Technology Shanghai Jiaotong UniversityShanghai 200240 China shanghai Center for Bioinformation and Technologyshanghai 200235 China Logistical engineering universityChongqing 400016 China

In the present paper,we describe how a directed graph was constructed and then searched forthe optimum path using a dynamic programming approach,based on the secondary structure propensity ofthe protein short sequence derived from a training data *** protein secondary structure was thus pre-dicted in this *** average three-state accuracy of the algorithm used was 76.70%.

关键词： directed graph dynamic programming approach protein secondary structure