检索结果-南通市图书馆

Building trust networks in the absence of trust relations

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

Frontiers of Information Technology & Electronic Engineering 2017年第10期18卷 1591-1600页

作者： Xin WANG Ying WANG jian-hua GUO College of Computer Science and Technology Jilin University Changchun 130012 China School of Computer Technology and Engineering Changchun Institute of Technology Changchun 130012 China School of Mathematics and Statistics Northeast Normal University Changchun 130024 China Key Laboratory of Symbolic Computation and Knowledge Engineering Ministry of Education Changchun 130012 China Guangxi Key Laboratory of Trusted Software Guilin University of Electronic Technology Guilin 541004 China

User-specified trust relations are often very sparse and dynamic, making them difficult to accurately predict from online social media. In addition, trust relations are usually unavailable for most social media *** issues pose a great challenge for predicting trust relations and further building trust networks. In this study,we investigate whether we can predict trust relations via a sparse learning model, and propose to build a trust network without trust relations using only pervasively available interaction data and homophily effect in an online world. In particular, we analyze the reliability of predicting trust relations by interaction behaviors, and provide a principled way to mathematically incorporate interaction behaviors and homophily effect in a novel framework,b Trust. Results of experiments on real-world datasets from Epinions and Ciao demonstrated the effectiveness of the proposed framework. Further experiments were conducted to understand the importance of interaction behaviors and homophily effect in building trust networks.

关键词： Trust network Sparse learning Homophily effect Interaction behaviors

Effects of Nb on microstructure and wear resistance of Fe-Cr-C-B surfacing alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2018年第2期25卷 243-251页

作者： jian Gou Zheng-jun Liu hua Jia Department of Material Science and Engineering ShenyangUniversity of Technology Shenyang 110870 LiaoningChina

The influence of Nb on the microstructure and wear resistance of the surfacing layer was investigated by using the Fe-based flux-cored wire in the Fe-Cr-C-B system. The microstructure, microhardness and wear resistance properties of the samples were investigated by X-ray diffraction, scanning electron microscopy, microhardness testing and abrasive wear testing, respectively. The results indicate that microstructures of the alloy are composed of martensite, retained austenite, M23（C,B）6 and NbC. Boride M23（C,B）6 is distributed along the grain boundaries, while NbC in shape-regular quadrilateral is distributed in martensite. The microhardness is distributed from the substrate to the surfacing layer gradiently. NbC significantly improved the wear resistance of surfacing layer.

关键词： Flux-cored wire Surfacing layer Microhardness Microstructure Wear resistance

Distributed anonymous data perturbation method for privacy-preserving data mining

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 Zhejiang University-Science A(Applied Physics & Engineering) 2009年第7期10卷 952-963页

作者： Feng LI Jin MA jian-hua LI School of Electronic Information and Electrieal Engineering Shanghai Jiao Tong University Shanghai 200030 China

Privacy is a critical requirement in distributed data mining. Cryptography-based secure multiparty computation is a main approach for privacy preserving. However, it shows poor performance in large scale distributed systems. Meanwhile, data perturbation techniques are comparatively efficient but are mainly used in centralized privacy-preserving data mining (PPDM). In this paper, we propose a light-weight anonymous data perturbation method for efficient privacy preserving in distributed data mining. We first define the privacy constraints for data perturbation based PPDM in a semi-honest distributed environment. Two protocols are proposed to address these constraints and protect data statistics and the randomization process against collusion attacks: the adaptive privacy-preserving summary protocol and the anonymous exchange protocol. Finally, a distributed data perturbation framework based on these protocols is proposed to realize distributed PPDM. Experiment results show that our approach achieves a high security level and is very efficient in a large scale distributed environment.

关键词： Privacy-preserving data mining (PPDM) Distributed data mining Data perturbation

A new photon kinetic-measurement based on the kinetics of electron-hole pairs in photodegradation of textile wastewater using the UV-H_2O_(2FS)-TiO_2 process

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2007年第3期19卷 367-373页

作者： SHIGWEDHA Nditange hua Zhao-zhe CHEN jian Laboratory of Environmental Biotechnology School of Biotechnology Southern Yangtze University Wuxi 214036 China Key Laboratory of Industrial Biotechnology Ministry of Education Southern Yangtze University Wuxi 214036 China

Actual textile wastewater and synthesized wastewater containing various textile dyes were photocatalytic degraded by the UVH2O2Fs-TiO2 process in an aimular-flow photocatalytic reactor. In this process, a photon kinetic-measure was adopted to obtain constant rates of dyes decomposition. It was theorized that, by illumination at different UV frequencies, the electrons within the semiconductor were excited from the valence band to the conduction band, yielding the formation of electron-hole pairs which are the pre-requisites for photocatalysis. CPT （critical photonic time） exposure required to cause 90% of vibrations between the double and single bonds along the molecular chain of the dyes to be oxidized, was taken to measure the photocatalytic activities. The CPTs varied with the frequencies of the UV spectral areas. The derivatization of CPT from the first-order kinetic law was presented.

关键词： critical photonic time (CPT) photon efficiency UV frequencies regression line textile wastewater

Implicit high-order discontinuous Galerkin method with HWENO type limiters for steady viscous flow simulations

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2013年第4期29卷 526-533页

作者： Zhen-hua jiang Chao Yan jian Yu College of Aeronautics Science and Engineering Beijing University of Aeronautics and Astronautics

Two types of implicit algorithms have been im- proved for high order discontinuous Galerkin （DG） method to solve compressible Navier-Stokes （NS） equations on tri- angular grids. A block lower-upper symmetric Gauss- Seidel （BLU-SGS） approach is implemented as a nonlin- ear iterative scheme. And a modified LU-SGS （LLU-SGS） approach is suggested to reduce the memory requirements while retain the good convergence performance of the origi- nal LU-SGS approach. Both implicit schemes have the sig- nificant advantage that only the diagonal block matrix is stored. The resulting implicit high-order DG methods are applied, in combination with Hermite weighted essentially non-oscillatory （HWENO） limiters, to solve viscous flow problems. Numerical results demonstrate that the present implicit methods are able to achieve significant efficiency improvements over explicit counterparts and for viscous flows with shocks, and the HWENO limiters can be used to achieve the desired essentially non-oscillatory shock tran- sition and the designed high-order accuracy simultaneously.

关键词： Discontinuous Galerkin (DG) scheme ~ Implicitmethod ~ HWENO ~ High order ~ Unstructured grids

Inception point of air entrainment over stepped spillways

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2013年第1期25卷 91-96页

作者： WU jian-hua ZHANG Bin MA Fei College of Water Conservancy and Hydropower Engineering Hohai University

The location of the inception point of the air entrainment directly affects the energy dissipation ratio, the cavitation damage control, and the training wall height designs for a stepped spillway and a stilling basin. In this paper, the boundary layer theory of plates is used to predict the location of the inception point of the air entrainment over the stepped spillways by assuming the steps on the spillways as a kind of roughness. An empirical formula is presented based on the physical model experiments, with the maximum error less than 1% except at one point where the error is 1.6%, as compared to the experimental data. Meanwhile, it is shown that the location of the inception point of the air entrainment for the stepped spillway is much nearer to the top of the spillway than that for a smooth spillways, which explains why the high ratio of the energy dissipation is provided for the stepped spillway.

关键词： air entrainment cavitation energy dissipation inception point stepped spillway unit discharge

Thermally activated phase transitions in Fe-Ni core-shell nanoparticles

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2019年第6期14卷 97-102页

作者： Jin-Bo Wang rao huang Yu-hua Wen Department of Physics Jiujiang Research Institute and Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient DevicesXiamen UniversityXiamen 361005China

Fe-Ni core-shell nanoparticles are versatile functional materials,and their thermal stabilities are crucial for their performances in operating *** this study,the thermodynamic behaviors of Fe-Ni core-shell nanoparticles are examined under continuous *** solid-solid phase transition from body centered cubic(bcc)to face centered cubic(fcc)in the Fe core is *** transition is accompanied with the generation of stacking faults around the core-shell interface,which notably lowers the melting points of the Fe-Ni core-shell nanoparticles and causes even worse thermal stability compared with Ni ***,the temperature of the structural transformation is shown to be tuned by modifying the Ni shell ***,the stress distributions of the core and the shell are also *** relevant results could be helpful for the design,preparation,and utilization of Fe-based nanomaterials.

关键词： core-shell metallic nanoparticle phase transition molecular dynamics

Inclusion variations and calcium treatment optimization in pipeline steel production

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

International Journal of Minerals,Metallurgy and Materials 2011年第5期18卷 527-534页

作者： jian-hua Liu hua-jie Wu Yan-ping Bao Min Wang Research Institute of Metallurgy Engineering University of Science and Technology Beijing Beijing 100083 China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China

SiCa line and SiCaBaFe alloy were injected into liquid pipeline steel at the end of LF refining as calcium treatment,and samples were taken from the ladles,mould,and *** of Ca content and inclusions shows that Ca content in steel decreases obviously in the following process after calcium treatment;the compositions,morphology,and sizes of inclusions also vary much in the production;primary inclusions in the ladles prior to calcium treatment are mainly Al2O3 inclusions,but they turn to fine irregular CaS-CaO-Al2O3 compound inclusions after the treatment,then become fine globular CaO-Al2O3 inclusions in the mould,and finally change to a few larger irregular CaS-CaO-Al2O3 complex inclusions in the *** study reveals that inclusion variations are related with the preferential reactions among Ca,Al2O3,and S and the precipitation of S in CaO-Al2O3 inclusions with high sulfur *** evaluation standards for calcium treatment in high-grade pipeline steel were put forward according to the inclusion variations and requirements of pipeline steel on inclusion controlling,and the calcium process was studied and optimized.

关键词： pipeline steel refining inclusions calcium treatment thermodynamics precipitation

Changes in Ecosystem Service of Soil Conservation Between 2000 and 2010 and Its Driving Factors in Southwestern China

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2016年第2期26卷 165-173页

作者： rao Enming XIAO Yi OUYANG Zhiyun ZHENG hua State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeij'ing 100085China University of Chinese Academy of Sciences Beijing 100049China

Human activities significantly alter ecosystems and their services; however, quantifying the impact of human activities on ecosystems has been a great challenge in ecosystem management. We used the Universal Soil Loss Equation and county-level socioeconomic data to assess the changes in the ecosystem service of soil conservation between 2000 and 2010, and to analyze its spatial characteristics and driving factors in the southwestern China. The results showed that cropland in the southwestern China decreased by 3.74%, while urban land, forest, and grassland areas increased by 46.78%, 0.86%, and 1.12%, respectively. The soil conservation increased by 1.88 × 10^(11) kg, with deterioration only in some local areas. The improved and the degraded areas accounted for 6.41% and 2.44% of the total land area, respectively. Implementation of the Sloping Land Conversion Program and urbanization explained 57.80% and 23.90% of the variation in the soil conservation change, respectively, and were found to be the main factors enhancing soil conservation. The 2008 Wenchuan earthquake was one of the factors that led to the degradation of soil conservation. Furthermore, industrial adjustment, by increasing shares of Industry and Service and reducing those of Agriculture, has also promoted soil conservation. Our results quantitatively showed and emphasized the contributions to soil conservation improvement made by implementing ecological restoration programs and promoting urbanization. Consequently, these results provide basic information to improve our understanding of the effects of ecological restoration programs, and help guide future sustainable urban development and regional industrial restructuring.

关键词： soil conservation ecosystem service Sloping Land Conversion Program(SLCP) ecological restoration urbanization southwestern China