检索结果-南通市图书馆

Journal of Computational Mathematics 2006年第3期24卷 281-294页

作者： zhang-xin chen Xi-jun Yu Center for Scientific Computation Box 750156 Southern Methodist University Dallas TX 75275-0156 USA Research Center for Science Xi'an Jiaotong University Xi'an 710049 China Center for Advanced Reservoir Modeling and Simulation College Vof Engineering'PekingI University China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China

In this paper we consider mixed finite element methods for second order elliptic problems. In the case of the lowest order Brezzi-Douglas-Marini elements （if d = 2） or Brezzi- Douglas-Duran-Fortin elements （if d = 3） on rectangular parallelepipeds, we show that the mixed method system, by incorporating certain quadrature rules, can be written as a simple, cell-centered finite difference method. This leads to the solution of a sparse, positive semidefinite linear system for the scalar unknown. For a diagonal tensor coefficient, the sparsity pattern for the scalar unknown is a five point stencil if d = 2, and seven if d = 3. For a general tensor coefficient, it is a nine point stencil, and nineteen, respectively. Applications of the mixed method implementation as finite differences to nonisothermal multiphase, multicomponent flow in porous media are presented.

关键词： Finite difference Implementation Mixed method Error estimates Superconvergence Tensor coefficient Nonisothermal multiphase Multicomponent flow Porousmedia.

Electrodeposition of photocatalytic TiO2 film on surface of alumina prepared by anodic oxidation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2004年第Z1期14卷 173-177页

作者： zhang xin-yu chen Tie-qun College of Mechanical Engineering South China University of TechnologyGuangzhou 510640 China College of Mechanical Engineering South China University of TechnologyGuangzhou 510640 China

A new electrochemical method to prepare photocatalytic TiO2 thin film was developed, by which the TiO2 was electrodeposited on surface of alumina by AC electrolysis in solution consisting of K2 [TiO(C2O4 )2] and C2H2O4. The deposited TiO2 thin film was primarily characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and energy dispersive spectrum (EDS) methods. The photocatalytic properties of this film were also studied by the photocatalytic degradation of methyl orange. The results show that the TiO2 film electrodeposited by this method is mainly in amorphous and with a little crystalline component mixed anatase and rutile. The surface of the alumina prepared by anodic oxidation is porous and the TiO2 electrodeposited on it is scattered and incompact. TiO2 thin film fixed on the surface of alumina shows photocatalytic activity to the degradation of methyl orange.

关键词： electrodeposition TiO2 film alumina anodic oxidation

Heat-treated microstructure and mechanical properties of laser solid forming Ti-6Al-4V alloy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2009年第6期28卷 537-544页

作者： zhang Shuangyin LIN xin chen Jing HUANG Weidong School of Materials Science and Engineering State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇ an 710072 China

The effects of heat treatment on the microstructure and mechanical properties of laser solid forming （LSF） Ti-6Al-4V alloy were investigated The influences of the temperature and time of solution treatment and aging treatment were analyzed. The results show that the microstructure of LSFed samples consists of Widmanstatten α laths and a little acicular in columnar prior β grains with an average grain width of 300 μm, which grow epitaxiaUy from the substrate along the deposition direction （27）. Solution treatment had an important effect on the width, aspect ratio, and volmne fraction of primary and secondary a laths, and aging treatment mainly affects the aspect ratio and volume fraction of primary α laths and the width and volume fraction of secondary a laths. Globular a phase was first observed in LSFed samples when the samples were heat treated with solution treatment （950℃, 8 h/air cooling （AC）） or with solution treatment （950℃, 1 h/AC） and aging treatment （550℃, above 8 h/AC）, respectively. The coarsening and globularization mechanisms of a phase in LSFed Ti-6Al-4V alloy during heat treatment were presented. To obtain good integrated mechanical properties for LSFed Ti-6Al-4V alloys, an optimized heat treatment regimen was suggested.

关键词： metal material Ti-6Al-4V alloy laser solid forming microstructure mechanical properties heat treatment

Effectiveness and safety of splenectomy for gastric carcinoma:A meta-analysis

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2009年第42期15卷 5352-5359页

作者： Kun Yang xin-Zu chen Jian-Kun Hu Bo zhang Zhi-xin chen Jia-Ping chen Department of Gastrointestinal Surgery West China Hospital Sichuan University No. 37 Guo Xue Xiang Chengdu 610041 Sichuan Province China

AIM： To evaluate the impact of splenectomy on longterm survival, postoperative morbidity and mortality of patients with gastric cancer by performing a metaanalysis METHODS： A search of electronic databases to identify randomized controlled trials in The Cochrane Library trials register, Mediine, CBMdisc （Chinese Biomedical Database） and J-STAGE, etc was performed. Data was extracted from the studies by 2 independent reviewers. Outcome measures were survival, postoperative morbidity and mortality and operation-related events. The meta-analyses were performed by RevMan 4.3. RESULTS： Three studies comprising 466 patients were available for analysis, with 231 patients treated by gastrectomy plus splenectomy. Splenectomy could not increase the 5-year overall survival rate [RR = 1.17, 95% confidence interval （CI） 0.97-1.41]. The postoperative morbidity （RR = 1.76, 95% CI 0.82-3.80） or mortality （RR = 1.58, 95% CI 0.45-5.50） did not suggest any significant differences between the 2 groups. No significant differences were noted in terms of number of harvested lymph nodes, operation time, length of hospital stay and reoperation rate. Subgroup analyses showed splenectomy did not increase the survival rate for proximal and whole gastric cancer. No obvious differences were observed between the 2 groups when stratified by stage. Sensitivity analyses indicated no significant differences regarding the survival rates （P 〉 0.05）. CONCLUSION： Splenectomy did not show a beneficial effect on survival rates compared to splenic preservation. Routinely performing splenectomy should not be recommended.

关键词： Gastric cancer Splenectomy Survival rate Morbidity Operative surgical procedure Postoperative period Treatment outcome

A synthetical geoengineering approach to evaluate the largest hydraulic fracturing-induced earthquake in the East Shale Basin, Alberta

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum Science 2023年第1期20卷 460-473页

作者： Gang Hui zhang-xin chen Zheng-Dong Lei Zhao-Jie Song Lin-Yang zhang xin-Ran Yu Fei Gu State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249PR China Department of Chemical and Petroleum Engineering University of CalgaryCalgaryABT2N1N4Canada Research Institute of Petroleum Exploration and Development Beijing10083PR China School of Environmental and Municipal Engineering Qingdao University of TechnologyQingdao257000ShandongPR China College of Pipeline and Civil Engineering China University of Petroleum(East China)Qingdao266580ShandongPR China

On 2019-03-04,the largest induced earthquake(ML4.18)occurred in the East Shale Basin,Alberta,and the underlying physical mechanisms have not been fully *** paper proposes a synthetical geoengineering methodology to comprehensively characterize this earthquake caused by hydraulic *** on 3D structural,petrophysical,and geomechanical models,an unconventional fracture model is constructed by considering the stress shadow between adjacent hydraulic fractures and the interactions between hydraulic and natural *** poroelastic simulations are conducted to reveal the triggering mechanisms of induced *** is found that four vertical basement-rooted faults were identified via focal mechanisms *** brittleness index(BI)along two horizontal wells has a high magnitude(BI>0.5),indicating the potential susceptibility of rock *** to the presence of overpressure,pre-existing faults in the Duvernay Formation are highly susceptible to fault *** occurrence of the earthquake clusters has been attributed to the fracturing fluid injection during the west 38^(th)-39^(th) stage and east 38^(th) stage *** brittleness,formation overpressure,and large fracturing job size account for the nucleation of earthquake clusters,and unconventional natural-hydraulic fracture networks provide fluid flow pathways to cause fault *** workflow can be used to mitigate potential seismic risks in unconventional reservoirs in other fields.

关键词： Geoengineering Hydraulic fracturing Induced seismicity Fault reactivation Mitigation strategies East Shale Basin

Hydrocarbon expulsion model and resource potential evaluation of high-maturity marine source rocks in deep basins:Example from the Ediacaran microbial dolomite in the Sichuan Basin,China

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2022年第6期19卷 2618-2630页

作者： Wen-Yang Wang Xiong-Qi Pang Ya-Ping Wang zhang-xin chen Chang-Rong Li xin-Hua Ma State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Beijing)Beijing 102249China College of Geosciences China University of Petroleum(Beijing)Beijing 102249China Research Institute of Exploration and Development Petro China Southwest Oil&Gas Field CompanyChengduSichuan 610041China Chemical and Petroleum Engineering Schulich School of EngineeringUniversity of CalgaryCalgary T2N 1N4Canada School of Earth and Space Sciences Peking UniversityBeijing 100871China Research Institute of Petroleum Exploration and Development(RIPED) Petro ChinaBeijing 100083China

Hydrocarbon expulsion features and resource potential evaluation of source rocks are crucial for the petroleum ***-maturity marine source rocks have not exhibited a hydrocarbon expulsion mode owing to the lack of low-maturity source rocks in deep petroliferous *** considered the Ediacaran microbial dolomite in the Sichuan Basin,the largest high-maturity marine gas layer in China,to exhibit a method that quantitatively characterizes the hydrocarbon expulsion of high-maturity marine source *** experiment of fluid inclusion,rock pyrolysis,and vitrinite reflectance(Ro)of 119 microbial dolomite core samples obtained from the Dengying Formation were performed.A hydrocarbon expulsion model of high-maturity source rock was established,and its resource potential was *** results showed that the Ediacaran microbial dolomite in the Sichuan Basin is a good source rock showing vast resource *** hydrocarbon expulsion threshold is determined to be vitrinite reflectance at 0.92%.The hydrocarbon expulsion intensities in the geologic history is high with maximum of 1.6×10^(7)t/km^(2).The Ediacaran microbial dolomite expelled approximately 1.008×10^(12)t of hydrocarbons,and the recoverable resource was 1.5×10^(12)m^(3).The region can be categorized into areasⅠ,Ⅱ,Ⅲ,andⅣ,in decreasing order of hydrocarbon expulsion *** with a higher hydrocarbon expulsion intensity have a lower drilling risk and should be prioritized for exploration in the orderⅠ>Ⅱ>Ⅲ>Ⅳ.Two areas,northern and central parts of Ediacaran in the Sichuan Basin,were selected as prospects which had the drilling priority in the future gas *** production data of 55 drilled wells verified the high reliability of this *** model in this study does not require low-maturity samples and can be used for evaluating high-maturity marine source rocks,which has broad applicability in deep basins worldwide.

关键词： Deep petroliferous basin Overmatured source rocks Hydrocarbon expulsion model Resource evaluation Sichuan basin

Quantitative prediction model for the depth limit of oil accumulation in the deep carbonate rocks:A case study of Lower Ordovician in Tazhong area of Tarim Basin

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第1期21卷 115-124页

作者： Wen-Yang Wang Xiong-Qi Pang Ya-Ping Wang zhang-xin chen Fu-Jie Jiang Ying chen State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Beijing)Beijing102249China College of Geosciences China University of Petroleum(Beijing)Beijing102249China Research Institute of Exploration and Development PetroChina Southwest Oil&Gas Field CompanyChengdu610041SichuanChina Chemical and Petroleum Engineering Schulich School of EngineeringUniversity of CalgaryCalgaryT2N 1N4Canada

With continuous hydrocarbon exploration extending to deeper basins,the deepest industrial oil accumulation was discovered below 8,200 m,revealing a new exploration ***,the extent to which oil exploration can be extended,and the prediction of the depth limit of oil accumulation(DLOA),are issues that have attracted significant attention in petroleum *** it is difficult to characterize the evolution of the physical properties of the marine carbonate reservoir with burial depth,and the deepest drilling still cannot reach the ***,the DLOA cannot be predicted by directly establishing the relationship between the ratio of drilling to the dry layer and the *** this study,by establishing the relationships between the porosity and the depth and dry layer ratio of the carbonate reservoir,the relationships between the depth and dry layer ratio were obtained *** depth corresponding to a dry layer ratio of 100%is the *** on this,a quantitative prediction model for the DLOA was finally *** results indicate that the porosity of the carbonate reservoir,Lower Ordovician in Tazhong area of Tarim Basin,tends to decrease with burial depth,and manifests as an overall low porosity reservoir in deep *** critical porosity of the DLOA was 1.8%,which is the critical geological condition corresponding to a 100%dry layer ratio encountered in the *** depth of the DLOA was 9,000 *** study provides a new method for DLOA prediction that is beneficial for a deeper understanding of oil accumulation,and is of great importance for scientific guidance on deep oil drilling.

关键词： Deep layer Tarim Basin Hydrocarbon accumulation Depth limit of oil accumulation Prediction model

Treatment of talipes equinovarus after triceps surae intramuscular hemangioma surgery by Ilizarov technology in adults:A case report

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2023年第12期11卷 2803-2810页

作者： zhang-xin chen Meng-Yuan Wang Cong zhang Zhen-Qi Ding Wei chen Department of Orthopedics The 909th HospitalSchool of MedicineXiamen UniversityZhangzhou 363000Fujian ProvinceChina School of Medicine Xiamen UniversityXiamen 361000Fujian ProvinceChina

BACKGROUND Postoperative complications of triceps surae intramuscular hemangioma surgery with talipes equinovarus have rarely been described,and the evidence for treatment is *** purpose of this case study was to report the new application of the Ilizarov technique,which successfully treated talipes equinovarus in adults after triceps surae intramuscular *** SUMMARY A 29-year-old woman treated with the Ilizarov technique for talipes equinovarus in the right leg after triceps surae intramuscular hemangioma *** equinus deformity was roughly corrected after 2 years of follow-up,without significant secondary *** Talipes equinovarus caused by postoperative sequelae of intramuscular hemangioma was successfully corrected by the Ilizarov *** Ilizarov technique may be used for treating talipes equinovarus caused by various causes.

关键词： Triceps surae intramuscular hemangioma Ilizarov technique Talipes equinovarus Treatment Case report

Diagnosis and surgical treatment of hepatic hilar cholangiocarcinoma

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Hepatobiliary & Pancreatic Diseases International 2007年第6期6卷 631-635页

作者： Yang, Wei-Liang zhang, xin-chen zhang, Dong-Wei Tong, Bai-Feng Harbin Med Coll Affiliated Hosp 2 Dept Gen Surg Harbin 150086 Peoples R China

BACKGROUND: Hepatic hilar cholangiocarcinoma can be diagnosed early with the progress in diagnostic imaging, and thus the rate of resection of the tumor has increased markedly. To assess the effectiveness of resection, we reviewed 185 cases of hepatic hilar cholangiocarcinoma diagnosed and treated at our hospital. METHODS: The clinical data of 185 patients with hepatic hilar cholangiocarcinoma who had been treated surgically from 1972 to 2006 were retrospectively analyzed. RESULTS: The records of the 185 patients were divided into first stage (1972-1986) or second stage (1987-2006) according to the incidence of the tumor and its resection rate. Primary symptoms included upper abdominal discomfort or pain, anorexia, tiredness, weight loss and progressive jaundice. Ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and magnetic resonance cholangiopancreatography (MRCP) were first line methods for atraumatic diagnosis. If the patients displayed intrahepatic bile duct dilatation or were diagnosed as suffering from extrahepatic obstructive jaundice, percutaneous transhepatic cholangiography (PTC), MRCP or endoscopic retrograde cholangiopancreatography (ERCP) should be used. In this series, 87 patients underwent resection of the tumor (47.0%). Of the 87 patients, 43 received radical resection and 44 palliative resection. Fifteen patients underwent resection in the first stage and 72 in the second stage. A total of 74 patients were followed up after the resection. The median survival time of the radical resection group was 37 months and that of the palliative resection group was 17 months (P<0.001). The other 62 patients receiving no resection died within 1.5 years. CONCLUSIONS: Once patients are diagnosed with hepatic hilar cholangiocarcinoma, they should undergo exploratory laparotomy. Resection is the most effective method for the treatment of hepatic hilar cholangiocarcinoma.

关键词： bile duct neoplasms hepatic hilar cholangiocarcinoma diagnosis surgical treatment

A machine learning-based study of multifactor susceptibility and risk control of induced seismicity in unconventional reservoirs

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2023年第4期20卷 2232-2243页

作者： Gang Hui zhang-xin chen Hai Wang Zhao-Jie Song Shu-Hua Wang Hong-Liang zhang Dong-Mei zhang Fei Gu National Key Laboratory of Petroleum Resources and Engineering China University of PetroleumBeijing102249PR China Department of Chemical and Petroleum Engineering University of CalgaryCalgaryABT2N1N4Canada Eastern Institute for Advanced Study Ningbo315200ZhejiangPR China Computer Modeling Group Ltd.Calgary ABT2L2M1Canada CNOOC Research Institute Beijing100028PR China China University of Geoscience(Wuhan) Wuhan430074HubeiPR China Research Institute of Petroleum Exploration and Development Beijing10083PR China

A comprehensive dataset from 594 fracturing wells throughout the Duvernay Formation near Fox Creek, Alberta, is collected to quantify the influences of geological, geomechanical, and operational features on the distribution and magnitude of hydraulic fracturing-induced seismicity. An integrated machine learning-based investigation is conducted to systematically evaluate multiple factors that contribute to induced seismicity. Feature importance indicates that a distance to fault, a distance to basement, minimum principal stress, cumulative fluid injection, initial formation pressure, and the number of fracturing stages are among significant model predictors. Our seismicity prediction map matches the observed spatial seismicity, and the prediction model successfully guides the fracturing job size of a new well to reduce seismicity risks. This study can apply to mitigating potential seismicity risks in other seismicity-frequent regions.

关键词： Induced seismicity Hydraulic fracturing Seismicity susceptibility Risk control Machine learning