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Search Results: 1 - 10 of 28569 matches for " XUE Xiang "
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Techniques for improving computational speed in numerical simulation of casting thermal stress based on finite difference method
Xue Xiang,Wang Yueping
China Foundry , 2013,
Abstract: Finite difference method (FDM) was applied to simulate thermal stress recently, which normally needs a long computational time and big computer storage. This study presents two techniques for improving computational speed in numerical simulation of casting thermal stress based on FDM, one for handling of nonconstant material properties and the other for dealing with the various coefficients in discretization equations. The use of the two techniques has been discussed and an application in wave-guide casting is given. The results show that the computational speed is almost tripled and the computer storage needed is reduced nearly half compared with those of the original method without the new technologies. The stress results for the casting domain obtained by both methods that set the temperature steps to 0.1 ℃ and 10 ℃, respectively are nearly the same and in good agreement with actual casting situation. It can be concluded that both handling the material properties as an assumption of stepwise profile and eliminating the repeated calculation are reliable and effective to improve computational speed, and applicable in heat transfer and fluid flow simulation.
Numerical simulation of boundary heat flow effects on directional solidification microstructure of a binary alloy
Xue Xiang,Tang Jinjun
China Foundry , 2010,
Abstract: The boundary heat flow has important significance for the microstructures of directional solidified binary alloy. Interface evolution of the directional solidified microstructure with different boundary heat flow was discussed. In this study, only one interface was allowed to have heat flow, and Neumann boundary conditions were imposed at the other three interfaces. From the calculated results, it was found that different boundary heat flows will result in different microstructures. When the boundary heat flow equals to 20 W·cm-2, the growth of longitudinal side branches is accelerated and the growth of transverse side branches is restrained, and meanwhile, there is dendritic remelting in the calculation domain. When the boundary heat flow equals to 40 W·cm-2, the growths of the transverse and longitudinal side branches compete with each other, and when the boundary heat flow equals to 100-200 W·cm-2, the growth of transverse side branches dominates absolutely. The temperature field of dendritic growth was analyzed and the relation between boundary heat flow and temperature field was also investigated.
Numerical Simulation of Microstructure and Microsegregation in Ni-Cu Alloy under Isothermal Condition

Xiang XUE,Jinjun TANG,

材料科学技术学报 , 2008,
Abstract: Phase-field method can be used to describe the complicated morphologies of dendrite growth without explicitly tracking the complex phase boundaries. The influences of initial temperature and initial concentration on dendrite growth are investigated by using the phase-field model coupling concentration field equations. The calculated results indicate that the supersaturation, which is larger in lower initial temperature and lower concentration under isothermal condition, plays a very important role in microsegregation. It is found that the larger supersaturation causes higher degree microsegregation and faster dendrite growth, and the more serious side-branchs occur. The simulated results agree well with the solidification theory.
Intestinal Iron Homeostasis and Colon Tumorigenesis
Xiang Xue,Yatrik M. Shah
Nutrients , 2013, DOI: 10.3390/nu5072333
Abstract: Colorectal cancer (CRC) is the third most common cause of cancer-related deaths in industrialized countries. Understanding the mechanisms of growth and progression of CRC is essential to improve treatment. Iron is an essential nutrient for cell growth. Iron overload caused by hereditary mutations or excess dietary iron uptake has been identified as a risk factor for CRC. Intestinal iron is tightly controlled by iron transporters that are responsible for iron uptake, distribution, and export. Dysregulation of intestinal iron transporters are observed in CRC and lead to iron accumulation in tumors. Intratumoral iron results in oxidative stress, lipid peroxidation, protein modification and DNA damage with consequent promotion of oncogene activation. In addition, excess iron in intestinal tumors may lead to increase in tumor-elicited inflammation and tumor growth. Limiting intratumoral iron through specifically chelating excess intestinal iron or modulating activities of iron transporter may be an attractive therapeutic target for CRC.
Magnetic Method Surveying and Its Application for the Concealed Ore-Bodies Prospecting of Laba Porphyry Molybdenum Ore Field in Shangri-La, Northwestern Yunnan Province, China  [PDF]
Nguyen Ba Dai, Chuan Dong Xue, Kun Xiang, Kun Xiang, Tran Trong Lap, Qureshi Javed Akhter, Shi Lei Li
Journal of Geoscience and Environment Protection (GEP) , 2014, DOI: 10.4236/gep.2014.23006
Abstract:

Recently, a number of large molybdenum (-copper) deposits have been discovered successively in the Laba area, Shangri-La county, northwestern Yunnan province. The investigation confirmed that there is a superlarge porphyry-skarn hydrothermal vein type molybdenum-polymetallic- metallogenic system with the total prediction reservoir of more than 150 mt molybdenum. The porphyry intrusions contributed to the mineralization closely, the superficial little vein molybdenum (-copper, lead, silver) ore-bodies are usually located in faults and fractures, and the deep porphyry type ore-bodies occurred in the granodiorite porphyries, the skarn type ore-bodies occurred in the contact zone intrused into Triassic limestone or Permian basalts. Laba ore block is a new exploration area with great prospecting potential. In order to reduce the target area and guide the further exploration work, the magnetic method measurement about 3.3 square kilometres was carried out in the ore field. This paper presents an application of analyzing the horizontal and vertical derivative, using Fast Fourier Transform (FFT) filter (FFT high-pass, low-pass, cosine roll-off, suscepbility), calculated spectra frequency energy to predict the depth and intensity of the apparent remanence magnetization of source (Hilbert). The calculated results and magnetic anomalous show that the remanence anomaly is caused by the intrusions into the Triassic limestone and Permian basalts with small anomalies, and the depth of located source is not great. We have identified a number of positions to the three drilled well, the drilled result specify interpretation with very high accuracy. The magnetic method is helpful to identify porphyry mineralization, and judge the shape and depth of the concealed ore-bearing intrusive bodies under the similar geological condition.

Purification and characterization of a gastrointestinal tract epithelial receptor for the adhesion factor of Lactobacillus  [PDF]
Xue-Yan Lin, Zhong-Hua Wang, Zhong-Xiang Niu, Jun Peng
Advances in Bioscience and Biotechnology (ABB) , 2012, DOI: 10.4236/abb.2012.33038
Abstract: An epithelial receptor for the Lactobacillus surface adhesion factor was isolated and purified from mucus of the gastrointestinal tract of SPF chickens, using chromatography. The purified protein was analyzed with discontinuous, native gel electrophoresis and binding assay with cultured intestinal epithelial cells. A single band was obtained after purification. The molecular weight of this band was about 60 KDa. The purified protein inhibited the attachment of Lactobacillus to intestinal epithelial cells, suggesting that it is the gastrointestinal receptor for the surface adhesion factor of Lactobacillus.
Extraction, purification and identification of surface adhesion ligand from Lactobacillus  [PDF]
Xue-Yan Lin, Zhong-Hua Wang, Zhong-Xiang Niu, Jun Peng
Advances in Bioscience and Biotechnology (ABB) , 2012, DOI: 10.4236/abb.2012.33039
Abstract: The objective of this experiment was to purify and analyze adhesion protein from the surface of Lactobacillus. The surface adhesion ligand of Lactobacillus was isolated with of LiCl method and (NH4)2SO4 method, followed by sephadex chromatography, analyzed with discontinuous native polyacrylamide gel electrophoresis, and tested with a binding assay with intestinal epithelial cells. We get the adhesion matter by two methods: ammonium sulfate and LiCl extraction. Further purification with sephadex chromatography produced 3 components. The second component of eluted from chromatography had adhesion enhancing ability compared with the control. A single band was present in discontinuous native—poly-acrylamide gel electrophoresis analysis and molecular weight was determined to be 43-66 KDa. The purified adhesion ligand can improve the number of Lactobacillus adhering to the intestinal epithelial cells.
The intra-nucleus integration of mitochondrial DNA (mtDNA)in cervical mucosa cells and its relation with c-myc expression
Daozhen Chen, Wenqun Xue, Jinying Xiang
Journal of Experimental & Clinical Cancer Research , 2008, DOI: 10.1186/1756-9966-27-36
Abstract: The expression of c-myc protein was measured by immunohistochemical test in 40 cases of the uterine cervix cancer, 30 cases of cervical intraepithelial neoplasia (CIN) and 30 cases of normal cervical epithelium; the sequence of mtDNA in the nuclei was detected by in situ hybridization technique.The detection rates of mtDNA in the nuclei of cervical epithelium cells were 27.5%, 13.3% and 0% in cervical carcinoma, CIN, and normal cervical epithelium respectively. The expression rate of c-myc in cervical mucoma cells was 67% in the mtDNA sequence positive group and was significantly higher than that in the negative group (36%).The integration of mtDNA into the nuclei of cervical epithelium cells may be involved in the carcinogenesis of cervical epithelium cells and the expression of c-myc might be related to the integration of mtDNA sequence into nuclei of cervical epithelium cells.In recent years, several studies have found that point mutation of some tumors was relevant to that of mtDNA, but it is unclear for causal relation, which could not rule out the possibility of mtDNA integration to the nuclear genome and inducing carcinogenesis. Actually there were objective conditions for the intranuclear transfusion and integration of mtDNA and its fragments. Physical, chemical and certain biological factors may cause mtDNA mutations, the collapse of mitochondrial membrane, and give rise to mtDNA and its fragments dissociation into the cytoplasm. When the free mtDNA and its fragments in the cytoplasm generate excessivelly and the activity of DNAase DNAase-like materials is degraded, the free mtDNA or its fragments probably has the similar effect of tumorgenic virus, passing through nucleopore and randomly integrating into genome DNA. The roles of mtDNA intranuclear integration could be as follows: (1) The integration fragments or integration sites do not influence the normal function of genome and have little impact on the biological characteristics of the host cells; (2) a
Numerical Simulation and Water Analog of Mold Filling Processes
Yuebing ZHANG,Xiang XUE,Bide ZHOU,

材料科学技术学报 , 2001,
Abstract: This paper demonstrates the potential of a computer code, developed by the authors, in shaping gating systems by modeling the fluid flow phenomena through a complex gating system during mold filling. A plate casting with dimension 200 mm×200 mm×50 mm was chosen as the verifying problem. Water analog studies were carried out on this casting. The comparison indicates that computer simulation could be a powerful tool in shaping gating systems.
Communication Performance Research about Netshot Routing Algorithm in Peer-to-Peer Network
P2P网络中Netshot路由算法的消息通信机制性能分析

XIANG Xue-zhe,
向学哲

计算机科学 , 2008,
Abstract: According to the basic structure of the Netshot , we organize the nodes of the network in different ways to form several variations of the network. Then we formulate and simulate the costs of some basic operations to have a general analysis . We also discuss the reliability and cost when the peers make failure.
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