检索结果-南通市图书馆

New judging model of fuzzy cluster optimal dividing based on rough sets theory

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2007年第2期18卷 392-397页

作者： wang yun Liu Qinghong Mu Yong Shi Kaiquan School of Mathematics and System Sciences Shandong Univ. Jinan 250100 P. R. China School of Science Univ. of Jinan Jinan 250022 P. R. China

To investigate the judging problem of optimal dividing matrix among several fuzzy dividing matrices in fuzzy dividing space, correspondingly, which is determined by the various choices of cluster samples in the totality sample space, two algorithms are proposed on the basis of the data analysis method in rough sets theory： information system discrete algorithm （algorithm 1） and samples representatives judging algorithm （algorithm 2）. On the principle of the farthest distance, algorithm 1 transforms continuous data into discrete form which could be transacted by rough sets theory. Taking the approximate precision as a criterion, algorithm 2 chooses the sample space with a good representative. Hence, the clustering sample set in inducing and computing optimal dividing matrix can be achieved. Several theorems are proposed to provide strict theoretic foundations for the execution of the algorithm model. An applied example based on the new algorithm model is given, whose result verifies the feasibility of this new algorithm model.

关键词： Rough sets theory Fuzzy optimal dividing matrix Representatives of samples Fuzzy cluster analysis Information system approximate precision.

Pd catalysts supported on modified Zr_(0.5)Al_(0.5)O_(1.75) used for lean-burn natural gas vehicles exhaust purification

在线全文

学校读者我要写书评

暂无评论

Journal of Natural Gas Chemistry 2012年第4期21卷 393-399页

作者： Hongyan Shang yun wang Maochu Gong Yaoqiang Chen Key Laboratory of Green Chemistry&Technology Ministry of EducationCollege of ChemistrySichuan UniversityChengdu 610064SichuanChina

Composite supports Zr0.5Al0.5O1.75 modified by metal oxides, such as La2O3, ZnO, Y2O3 or BaO, were prepared by co-precipitation method, and palladium catalysts supported on the modified composite supports were prepared by impregnation method. Their properties were characterized by X-ray diffraction （XRD）, NH3 temperature-programmed desorption （NH3-TPD）, He temperature-programmed reduction （He-TPR）, N2 adsorption/desorption, and CO-chemisorption. The catalytic activity and the resistance to water poisoning of the prepared Pd catalysts were tested in a simulated exhaust gas from lean-burn natural gas vehicles with and without water vapor. The results demonstrated that the modified supports had an apparent effect on the performance of Pd catalysts, compared with the Pd catalyst supported on the unmodified ZrA1. The addition of ZnO or Y203 promoted the conversion of CH4. In the absence of water vapor, Pd/ZnZrA1 exhibited the best activity for CH4 conversion with the light-off temperature （Tso） of 275 ℃ and the complete conversion temperature （T90） of 314 ℃, respectively. However, in the presence of water vapor, Pd/YZrA1 was the best one over which the light-off temperature （Tso） of methane was 339 ℃ and the complete conversion temperature （T90） was 371 ℃. These results indicated that Pd catalyst supported on the modified composite ZrA1 support showed excellent catalytic activity at low temperature and high resistance to H20 poisoning for the exhaust purification of lean-burn natural gas vehicles.

关键词： modified Zr0.5Al0.5O1.75 palladium lean-bum natural gas vehicle methane oxidation water vapor

Comparative Study on Optical Properties and Scratch Resistance of Nanocomposite Coatings Incorporated with Flame Spray Pyrolyzed Silica Modified via in-situ Route and ex-situ Route

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2016年第3期32卷 251-258页

作者： yun wang Ling Zhang Yanjie Hu Chunzhong Li Key Laboratory for Ultrafine Materials of Ministry of Education School of Materials Science and Engineering East China University of Science and Technology

A new type of transparent scratch resistant coatings including in-situ modified SiO2 （g-SiO2） in flame spray pyrolysis （FSP） process was prepared. The maximum content of g-SiO2 in the coating was 15 wt%, which is higher than that of SiO2 modified by traditional wet chemical route （I-SiO2, only 10 wt%）. The results of transmission electron microscopy have demonstrated that in-situ surface modified g-SiO2 particles dispersed well with smaller agglomerates in the final coating, which was much better than the particles modified via wet chemical route. Visible light transmittance and haze tests were introduced to characterize the optical quality of the films. All coatings were highly transparent with the visible light transmittance of above 80%, especially for coatings containing g-SiO2, which exhibited slightly higher visible light transmittance than l-SiO2 embedded one. The haze value of coatings incorporated with 15 wt% g-SiO2 was 1.85%, even lower than the coating with 5 wt% I-SiO2 （haze value of 2.09%）, indicating much better clarity of g-SiO2. The excellent optical property of g-SiO2 filled coatings was attributed to the good dispersion and distribution of particles. Nano-indention and nano-scratch tests were con- ducted to investigate the scratch resistance of coatings on nano-scale. The surface hardness of the coatings rose by 18% and 14%, and the average friction coefficient decreased by 15% and 11%, respectively, compared to the neat coat due to the addition of 10 wt% g-SiO2 and I-SiO2. The pencil hardness of the coating with 15 wt% g-SiO2 increased from 2B for the neat coating to 2H. However, the pencil hardness of coating with 10 wt% I-SiO2 was only H. The results showed that the g-SiO2 embedded coatings exhibited higher scratch resistance and better optical properties.

关键词： ln-situ modification Silica Coating Scratch resistance Optical property

In situ Surface Functionalization of Hydrophilic Silica Nanoparticles via Flame Spray Process

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2015年第9期31卷 901-906页

Hydrophobic silica nanoparticles grafted with a high amount of organic molecules were successfully pre- pared by an in situ functionalization method in flame spray pyrolysis （FSP） process. Hydrophilic SiO2 nanoparticles were converted into hydrophobic ones by silylation between 3-methacryloxypropyltrimethoxyl silane （MPS） and silica＇s surface hydroxyl groups. The freshly formed silica nanoparticles in flame were continuously functionalized by a fine spray of 3-methacryloxypropyltrimethoxyl silane （MPS） solution at a preferred temperature. The functionalization extent, morphology structure and size of silica nanoparticles were characterized by transmission electron microscopy （TEM）, Brunauer-Emmett- Teller （BET）, thermogravimetric analysis （TGA）, Fourier transform infrared spectroscopy （FT-IR） and X-ray photoelectronic spectroscopy （XPS）. The influence of concentration, pH value and pre-activation of organic silane solution on the surface grafting density was investigated in detail. The obtained silica nanoparticles had a higher MPS functional content of 15.0 wt% （an average density of 2.7 MPS molecule/nm^2） than that of the silica modified by wet chemistry route, showing an excellent, stable hydrophobic property. The results have demonstrated that the in situ FSP functionalization process is a simple, effective and prom- ising route for the scalable preparation of advanced, hydrophobic nanomaterials.

关键词： SilicaIn situ functionalizationHydrophobicFlameModification

Relation of hepatic EROD activity and cytochrome P4501A level in Sebastiscus marmoratus exposed to benzo[a]pyrene

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2008年第1期20卷 101-104页

作者： wang yun ZHENG Ronghui ZUO Zhenghong CHEN Yixin wang Chonggang Key Laboratory of the Ministry of Education for Cell Biology and Tumor Cell Engineering School of Life Sciences Xiamen University Xiamen 361005 China.

This study was designed to investigate the in vivo effects of benzo[a]pyrene （BaP） on hepatic ethoxyresorufin-O-deethylase （EROD） activity and its correlation with cytochrome P4501A （CYP1A） protein levels in Sebastiscus marmoratus, which were exposed through a water column to BaP （10, 100, 1000 ng/L, respectively） or were treated with intraperitoneal injections of BaP （0.5, 1, 5, 10 mg/kg, respectively） every 7 d. The results showed that after 25 d of waterborne exposure to 1000 ng/L BaP, fish hepatic CYP1A levels and EROD activity were significantly induced. In contrast, EROD activity was not altered 7 d after second intraperitoneal injections, whereas, CYP1A protein levels were increased. Dose-dependent increase of biliary BaP metabolites demonstrated that the catalytic activity of CYP1A was induced by treatment with BaP. The lowest observable effect concentration with regard to biliary BaP metabolites （100 ng/L） was much lower than that with reference to EROD activity （1000 ng/L）. The results suggest that biliary polycyclic aromatic hydrocarbon （PAH） metabolites were shown to better reflect the contamination gradients of PAHs than EROD activity. It appeared to be necessary to measure CYP1A protein levels to complement the EROD activity in relevant toxicological assessments.

关键词： BaP BaP metabolites EROD activity CYP1A protein Sebastiscus marmoratus

Simulation of Secondary Dendritic Arm Spacing of Free Cutting Steel 38MnVS

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2011年第6期18卷 54-60,73页

作者： XIA yun-jin wang Fu-ming wang Jin-long School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China

The secondary dendritic arm spacing （SDAS） of free cutting steel 38MnVS during continuous casting process was simulated based on a Mixed Lagrangian and Eulerian Method （MILE Method） and SDAS model. The simulation results are basically in agreement with measured ones. The effect of composition, superheat and casting speed on SDAS are studied, and the relationship between SDAS and interdendritic segregation is discussed. The results show that SDAS increases with increasing carbon and silicon content, and decreases with increasing manganese and sulfur content. The increase of superheat and casting speed also makes SDAS increase. The permeability of co lumnar mushy zone which is parallel to the primary dendritic arms is calculated based on Carman-Kozeny relationship, and the increase of SDAS makes the permeability increase, which exacerbates interdendritic segregation of columnar crystal zone.

关键词： MiLE method secondary dendritic arm spacing permeability interdendritic segregation

Magnetization of Coupled Ultrathin Ferromagnetic Films

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2002年第7期38卷 107-112页

作者： wang Huai-Yu ZHOU yun-Song wang Chong-Yu Department of Physics Tsinghua University Beijing 100084 China Department of Physics Capital Normal University Beijing 100037 China Department of Physics Tsinghua University Beijing 100084 China

The magnetization of coupled ferromagnetic films is calculated by Green's function method. The coupling can either be ferromagnetic or antiferromagnetic. For the latter case, a concept of pseudo-spin is suggested to make calculation possible. A pseudo-spin is actually an anti-spin with its properties being analogue to other known anti particles such as a hole. The decreasing of Curie point as the coupling strength decays is computed. It is noted that with the same strength, antiferromagnetic coupling has higher Curie point than ferromagnetic coupling.

关键词： magnetization, pseudo-spin, coupled ferromagnetic films

Hand-assisted laparoscopic splenectomy is a useful surgical treatment method for patients with excessive splenomegaly: A metaanalysis

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2019年第3期7卷 320-334页

作者： Yong Huang Xiao-yun wang Kai wang Department of General Surgery Hepato-Biliary-Pancreatic Surgery Division The Second Affiliated Hospital of Nanchang University Department of Operating Room The Second Affiliated Hospital of Nanchang University

BACKGROUND Hand-assisted laparoscopic splenectomy(HALS) can help overcome the drawbacks of laparoscopic splenectomy(LS) while maintaining its *** To evaluate the efficacy and advantages of HALS for *** The relevant literature was reviewed using the PubMed, EMBASE, Cochrane,Ovid Medline, and Wanfang databases to compare the clinical outcomes of HALS and LS. Odds ratios or mean differences were calculated with 95% confidence intervals for fixed-effects and random-effects models. Overall, 754 patients from16 trials who met the inclusion criteria were *** In pure splenectomy, blood loss volume(P 0.001) and conversion rate(P =0.008) were significantly lower in the HALS group than in the LS ***, for splenomegaly, the operative time(P = 0.04) was shorter and blood loss volume(P 0.001) and conversion rate(P = 0.001) were significantly lower in the HALS group than in the LS group. However, no significant difference was observed in hospital stay length, blood transfusion, time to food intake, complications, or mortality rate between the two groups. Moreover, in splenectomy and devascularization of the upper stomach(DUS), the operative time(P = 0.04) was significantly shorter and blood loss volume(P 0.001) andconversion rate(P = 0.05) were significantly lower in the HALS + DUS group than in the LS + DUS group. However, no significant difference was observed in hospital stay length, timing of diet, and complications between the two *** HALS is an ideal surgical treatment method for splenomegaly because it can maximize the benefits for patients while maintaining the advantages of LS.

关键词： Hand-assisted Laparoscopic Splenectomy Splenomegaly Devascularization

Multicomponent Seismic Data Reconstruction via Anti-Aliasing Vector POCS Method

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Earth Science 2024年第4期35卷 1385-1392页

作者： Fan Li Jianjun Gao yun wang Chunming wang Sian Hou School of Geophysics and Information Technology China University of GeosciencesBeijing 100083China Research Institute of Petroleum Exploration and Development Petro ChinaBeijing 100083China

0 INTRODUCTION Due to the ability to comprehensively utilize P and S wave information,multi-component seismic exploration has already played an important role in fracture detection,lithology prediction,fluid identification,etc.,and it has also become an important technology for complex reservoir exploration(Yuan et al.,2021;Stewart et al.,2003).

关键词： reservoir Seismic prediction