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The mathematical model of wetting angle of heterogeneous nucleation

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Science china(Technological Sciences) 2004年第4期47卷 391-397页

作者： HUANG Cheng1. SONG Bo1. MAO Jinghong2 & ZHAO Pei3 1. school of Metallurgical and Ecological Engineering, University of Science and Technology {1., {1. 1.0083, china 2. school of Material Science, University of Science and Technology {1., {1. 1.0083, china 3. Central Iron and Steel Research Institute, {1. 1.0081. china 1. school of Metallurgical and Ecological Engineering University of Science and Technology Beijing 100083 Beijing China 2. school of Material Science University of Science and Technology Beijing 100083 Beijing China 3. Central Iron and Steel Research Institute 100081 Beijing China

The heterogeneous nucleation has been analyzed in terms of the thermodynamic theory, and the mathematical model of wetting angle of heterogeneous nucleation has been developed based on the dynamic requirements of hetero- and homogeneous nucleation. With the wetting angel model, the wetting angles of different catalysts in liquid iron have been calculated. The result shows that the wetting angle of most catalysts is smaller than 40, and the value of f() is far less than 1. The wetting angles of TiN, TiC and RE2O3 are smaller, while the wetting angle of MnO is bigger among the ordinary nucleation catalysts. The wetting angles calculated by this model are in agreement with the results of other research work.

关键词： heterogeneous nucleation, mathematical model, wetting angle, undercooling.

The regular representation and regular covariant representation of crossed products of Woronowicz C^(*)-algebras

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Science china Mathematics 2005年第9期48卷 1245-1259页

作者： ZHANG Xiaoxia~(1.2) & GUO Maozheng~(1.3) 1. school of Mathematical Sciences,Peking University,{1. 1.0871.china 2. Department of Mathematics,Yantai University,Yantai 264005,china 3. LMAM,Peking University,{1. 1.0871.china 1. school of Mathematical Sciences Peking University 100871 Beijing China 2. Department of Mathematics Yantai University 264005 Yantai China 3. LMAM Peking University 100871 Beijing China

In this paper,it is shown that the regular representation and regular covariant representation of the crossed products A×α G correspond to the twisted multiplicative unitary operators,where A is a Woronowicz C~*-algebra acted upon by a discrete group ***,it is also shown that the regular covariant C~*-algebra is the Woronowicz C~*-algebra which corresponds to a multiplicative ***,an explicit description of the multiplicative unitary operator for C(SU_q(2) )×α (?) is given in terms of those of the Woronowicz C~*-algebra C(SU_q(2) ) and the discrete group G.

关键词： multiplicative unitary operator, Woronowicz C*-algebra, crossed product.

A new method of discovering new meteor showers from the IMO single-station video meteor database

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Science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 1170-1178页

作者： LI Jun1.2 & ZHU Jin3 1.No.2 Middle school of {1.,{1. 1.001.,china 2 school of Journalism and Communication,Tsinghua University,{1. 1.0084,china 3 {1. Planterium,{1. 1.0044,china 1. No.2 Middle school of {1. Beijing 100010 China 2. school of Journalism and Communication Tsinghua University Beijing 100084 China 3. beijing Planterium Beijing 100044 China

It has been found that unknown meteor showers could be efficiently discovered from the single station video meteor database of the International Meteor Organization(IMO) by assuming the geocentric velocity and adjusting it within the dynamically permitted range. The mean geocentric velocities of new meteor showers can be obtained,as well as the coordinates of the radiants. The activity period and maximum time can also be obtained if there are sufficient shower meteors. All single station video meteor observations between February 1. and 1.(from 2000 to 2005) in IMO's database are processed with this method. As a result,two new meteor showers,one near RA=245.1.°,Dec=41.82° in Hercules and the other near RA=233.03°,Dec=1..04° in Serpenids,are discovered. Some dynamical characteristics of the new meteor showers are also determined. Considering the random nature on the selection of period in this work,it is expected that there are some more potential new meteor showers in IMO's video database.

关键词： single-station video meteor database the process of single-station video meteor database discovery of new meteor showers

Recommendation Method for Contrastive Enhancement of Neighborhood Information

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Computers, Materials & Continua 2024年第1期78卷 453-472页

作者： Hairong Wang beijing Zhou Lisi Zhang He Ma school of Computer Science and Engineering North Minzu UniversityNingxia750021China

Knowledge graph can assist in improving recommendation performance and is widely applied in various person-alized recommendation ***,existing knowledge-aware recommendation methods face challenges such as weak user-item interaction supervisory signals and noise in the knowledge *** tackle these issues,this paper proposes a neighbor information contrast-enhanced recommendation method by adding subtle noise to construct contrast views and employing contrastive learning to strengthen supervisory signals and reduce knowledge ***,first,this paper adopts heterogeneous propagation and knowledge-aware attention networks to obtain multi-order neighbor embedding of users and items,mining the high-order neighbor informa-tion of users and ***,in the neighbor information,this paper introduces weak noise following a uniform distribution to construct neighbor contrast views,effectively reducing the time overhead of view *** paper then performs contrastive learning between neighbor views to promote the uniformity of view information,adjusting the neighbor structure,and achieving the goal of reducing the knowledge noise in the knowledge ***,this paper introduces multi-task learning to mitigate the problem of weak supervisory *** validate the effectiveness of our method,experiments are conducted on theMovieLens-1.,MovieLens-20M,Book-Crossing,and Last-FM *** results showthat compared to the best baselines,our method shows significant improvements in AUC and F1.

关键词： Contrastive learning knowledge graph recommendation method

Analysis for twinning and slip in face-centered cubic crystals under axisymmetric co-deformation

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Science china(Technological Sciences) 2006年第5期49卷 521-536页

作者： CHEN Zhiyong1.2, CAI Hongnian1. ZHANG Xinming2, WANG Fuchi1.& TAN Chengwen1.3 1. school of Material Science and Engineering, {1. Institute of Technology, {1. 1.0081. china 2. school of Material Science and Engineering, Central South University, Changsha 41.083, china 3. school of Material Science and Engineering, {1. University of Aeronautics and Astronautics, {1. 1.0083, china 1. school of Material Science and Engineering Beijing Institute of Technology Beijing 100081 China 2. school of Material Science and Engineering Central South University Changsha 410083 China 3. school of Material Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112 and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.

关键词： twinning slip face-centered cubic crystals axisymmetric co-deformation Bishop-Hill maximum work principle yield strength anisotropy

Similar component analysis

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Progress in Natural Science:Materials International 2006年第12期16卷 1343-1347页

作者： ZHANG Hong~1.*, WANG Xin~1. LI Junwei~2 and CAO Xianguang~1.1. Image Center, Astronautics school, {1. University, beijing 1.0083, china 2. The 207th Institute of the Second Academy of china Aerospace Science Industry Corporation, beijing 1.0854, china) [a]Image Center Astronautics School BeiHang University Beijing China [b]The 207th Institute of the Second Academy of china Aerospace Science Industry Corporation Beijing China

A new unsupervised feature extraction method called similar component analysis (SCA) is proposed in this paper. SCA method has a self-aggregation property that the data objects will move towards each other to form clusters through SCA theoretically, which can reveal the inherent pattern of similarity hidden in the dataset. The inputs of SCA are just the pairwise similarities of the dataset, which makes it easier for time series analysis due to the variable length of the time series. Our experimental results on many problems have verified the effectiveness of SCA on some engineering application.

关键词： clustering feature extraction similar component.

A preliminary study on seismic design criteria of offshore platforms in Bohai Sea of china

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Earthquake Engineering and Engineering Vibration 2010年第2期9卷 223-231页

作者： Peng Yanju1.Lu Yuejun1.Yan Jiaquan2,Tang Rongyu1.Wang Junqin3 and Li Jiagang3 1. Institute of Crustal Dynamics,china Earthquake Administration,{1. 1.0085,china 2. Institute of Geophysics,china Earthquake Administration,{1. 1.0081.china 3. {1. Research Center of china National Offshore Oil Corp.,{1. 1.0027,china Institute of Crustal Dynamics China Earthquake Administration Beijing 100085 China

This paper analyzes the seismicity in Bohai Sea,introducing a shape factor K to characterize the seismic risk distribution in sub-regions of the sea. Based on the seismic design ground motions for 46 platforms located in the Bohai Sea,a statistical analysis was performed for different peak ground acceleration (PGA) ratios at two different probability levels. In accordance with the two-stage design method,a scheme of two seismic design levels is proposed,and two seismic design objectives are established respectively for the strength level earthquake and the ductility level earthquake. By analogy with and comparison to the Chinese seismic design code for buildings,it is proposed that the probability level for the strength level earthquake and ductility level earthquake have a return period of 200 and 1.00 - 2500 years,respectively. The validity of these proposed values is discussed. Finally,the PGAs corresponding to these two probability levels are calculated for different sub-regions of the Bohai Sea.

关键词： fixed offshore platform seismic design level seismic design objective return period Bohai Sea

Comparative study on CO_2 corrosion behavior of N80,P1.0,X52 and 1.Cr pipe lines in simulated stratum water

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Science china(Technological Sciences) 2010年第9期53卷 2342-2349页

作者： CAI YiDong1.GUO PengChao1.LIU DaMeng1.CHEN ShiYu2 & LIU JunLai3 1.school of Energy Resources,{1. University of Geosciences,beijing 1.0083,{1. 2 school of Materials Science and Engineering,University of Science and Technology beijing,beijing 1.0083,{1. 3.school of Earth Sciences and Resources,{1. University of Geosciences,beijing 1.0083,{1. 1. school of Energy Resources China University of Geosciences Beijing 100083 China2. School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China3. School of Earth Sciences and Resources China University of Geosciences Beijing 100083 China

To better understand the carbon dioxide (CO2) corrosion behavior of carbon steel and its influence on petroleum development (including drilling,production and transportation) in the Daqing Oilfield,CO2 corrosion behaviors of N80,P1.0,X52 and 1.Cr pipe lines in simulated solution at high temperature and high pressure condition are investigated by dynamic corrosion experiments,scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) *** show that the corrosion rate of all pipe lines increases quickly when CO2 partial pressure increases from 0.5 to 1.5 MPa,but it slows down when CO2 partial pressure further increases from 1.5 to 4.5 MPa,during which localized corrosion is *** the experimental temperature ranges from 60 to 1.0°C,localized corrosion *** corrosion rate of all pipe lines decreases sharply when the temperature changes from 60 to 1.0°C,and it becomes stable after the temperature is higher than 1.0°*** the flow rate is in the range of 0–1.5 m/s,the corrosion rate of sample X52 remains unchanged,but localized corrosion gradually becomes very serious when the flow rate further *** analyzing the corrosion product scales of sample 1.Cr,some remarkable phenomena are *** the temperature range of 60–1.0°C,the corrosion product scales are loose and thick,but become very compact when the temperature increases above 1.0°*** the later case,localized corrosion is *** main components of the corrosion product scales are FeCO3 and Cr2O3.

关键词： CO2 corrosion pipe lines weight loss SEM EDS

Effects of the CNTF-collagen gel-controlled delivery system on rat neural stem/progenitor cells behavior

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Science china(Life Sciences) 2010年第4期53卷 504-510页

作者： YANG ZhaoYang1. QIAO Hui2 & LI XiaoGuang1.3 1.0} of Biological Science and Medical Engineering, {1. University, beijing 1.01.1, china 2Public Heath school, Ningxia Medical University, Yinchuan 750004, china 3beijing Institute for Neuroscience, Capital Medical University, beijing 1.0069, china 1. school of Biological Science and Medical Engineering Beihang University Beijing 100191 China2. Public Heath School Ningxia Medical University Yinchuan 750004 China3. Beijing Institute for Neuroscience Capital Medical University Beijing 100069 China

The injury of central nervous system (CNS) usually causes the cavity formation. Although transplantation of neural stem/precursor cells (NSPCs) into the lesioned area of CNS has been shown to be implicated in the functional restoration, the therapeutic result is limited by the poor survival of NSPCs as well as their insufficient proliferation and differentiation abilities. Type-1.collagen is considered as a candidate scaffold or drug delivery system to overcome the aforementioned obstacle. This study observed the effects of the CNTF (ciliary neurotrophic factor)-collagen gel-controlled delivery system and daily addition of soluble-form CNTF on the NSPC survival, migration, proliferation and differentiation. The results showed that, within 1. h of the initial co-culture, CNTF was released in a burst pattern, then the CNTF-collagen gel-controlled delivery system stably released CNTF for up to 1. d. The cell viability test, together with immunohistochemistry, RT-PCR and Western blotting, showed that the CNTF-collagen gel-controlled delivery system supported the NSPCs seeded on the surface of collagen gel survival and facilitated their migration and proliferation. The daily addition of soluble-form CNTF to the medium had similar effects to the CNTF-collagen gel-controlled delivery system, but large quantities of soluble-form CNTF were consumed during the entire process. Taken together, the CNTF-collagen gel-controlled delivery system not only provides a physical scaffold for the transplanted NSPCs to adhere and migrate, but also facilitates the NSPC survival, growth and proliferation, simultaneously reducing the consumption of the expensive growth factors. This system may be used to enhance the microenvironment in the lesioned area of CNS.

关键词： spinal cord neural stem/progenitor cells control release type-1 collagen CNTF