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Influence of yttrium on the structure and magnetostriction of Fe_(83)Ga_(17) alloy

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International Journal of Minerals,Metallurgy and Materials 2012年第9期19卷 849-855页

作者： xi-ming xiao Xue-xu Gao ji-heng Li jian-xin xie State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Polycrystalline Fe83Ga17 alloy rods with various amounts of yttrium were prepared by high vacuum induction melting. It is found that yttrium addition has a significant effect on the structure and magnetostriction of Fes3Ga17 alloy. The small addition of yttrium alters the solidification character and the grain shape of Fe83Ga17 alloy, and as a result, columnar grains with the 〈100〉 preferential direction are pro- duced. Yttrium addition improves the magnetostrictive performance of the as-cast Fes3Ga17 alloy. The magnetostriction values of the as-cast alloy with 0.32at% and 0.64at% yttrium addition go up to 119×10^-6 and 137×10^-6 under 15 MPa compressive stress, respectively. The energy dispersive spectroscopy （EDS） result shows that almost all of the yttrium atoms exist in the Y2Fe17-xGax phase. A small amount of this kind of secondary phase cannot obviously increase the saturate magnetic field.

关键词： gallium alloys iron alloys yttrium magnetostfiction supercooling polycrystallirte materials

Magnetostriction of 〈100〉 oriented Fe–Ga rods with large diameter

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Rare Metals 2015年第7期34卷 472-476页

作者： ji-heng Li Xue-Xu Gao xi-Ming xiao xiao-Qian Bao Mao-Cai Zhang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing

The Fe83Ga17 alloy rods with h100 i preferential orientation was prepared by directional solidification *** dimension of oriented Fe83Ga17 rods is large up to 40 mm greater than diameter in previous investigations of3–10 *** growth direction of columnar grain is nearly parallel to the solidification direction of *** deviation angle between axial direction and h100 i direction of columnar crystal was investigated by method of electron backscattering diffraction, and the deviation is smaller than10°.The large columnar grain and h100 i preferential orientation along axial direction of rods could be attributed to the calm solid–liquid interface during solidification process that is difficultly formed due to electromagnetism agitation in induction heating zone-melting *** corresponding magnetostriction is large up to 290 9 10-6under pre-compressive press of 15 MPa.

关键词： Fe–Ga alloys Directional solidification Crystallog

Alternative industrial carbon emissions benchmark based on input-output analysis

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Frontiers of Earth Science 2016年第4期10卷 731-739页

作者： Mengyao HAN xi ji Institute of Geographic Sciences and Natural Resources Research Chineses Academy of Sciences Beijing 100871 China College of Engineering Peking University Beijing 100871 China School of Economics Peking University Beijing 100871 China

Some problems exist in the current carbon emissions benchmark setting systems. The primary con- sideration for industrial carbon emissions standards highly relate to direct carbon emissions （power-related emissions） and only a portion of indirect emissions are considered in the current carbon emissions accounting processes. This practice is insufficient and may cause double counting to some extent due to mixed emission sources. To better integrate and quantify direct and indirect carbon emissions, an embodied industrial carbon emissions benchmark setting method is proposed to guide the establishment of carbon emissions benchmarks based on input-output analysis. This method attempts to link direct carbon emissions with inter-industrial economic exchanges and systematically quantifies carbon emissions embodied in total product delivery chains. The purpose of this study is to design a practical new set of embodied intensity-based benchmarks for both direct and indirect carbon emissions. Beijing, at the first level of carbon emissions trading pilot schemes in China, plays a significant role in the establish- ment of these schemes and is chosen as an example in this study. The newly proposed method tends to relate emissions directly to each responsibility in a practical way through the measurement of complex production and supply chains and reduce carbon emissions from their original sources. This method is expected to be developed under uncertain internal and external contexts and is further expected to be generalized to guide the establish- ment of industrial benchmarks for carbon emissions trading schemes in China and other countries.

关键词： emissions trading scheme benchmarking,carbon emissions input-output analysis

Scalable peer-to-peer resource discovering scheme for wireless self-organized networks

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The Journal of China Universities of Posts and Telecommunications 2009年第2期16卷 47-52,57页

作者： LI xi ji Hong Key Laboratory of Universal Wireless Communications Minisa-y of Education Beijing University of Posts and Telecommunications Beijing 100876 China

Peer-to-peer technologies have attracted increasing research attention with fruitful protocols and applications proposed for wired networks. As to mobile environments, there are currently no mature deployments. A novel resource managing and discovering protocol, Cheer, is proposed to realize scalable and effective peer-to-peer lookup in wireless self-organized networks. Cheer resolves the topologies mismatch problem between peer-to-peer overlay networks and actual nodes distribution, allowing for frequent nodes membership changes. With specially designed resource storage table, Cheer also supports multikey and fuzzy lookup. Its hybrid architecture and improved routing scheme based on small-world theory may realize effective lookup routing. Theoretical analysis and simulation results both prove that Cheer makes using peer-to-peer applications in large-scale self-organized mobile networks feasible and promising.

关键词： peer-to-peer small-world resource discovering

Tuning the Learning Rate for Stochastic Variational Inference

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Journal of Computer Science & Technology 2016年第2期31卷 428-436页

作者： xi-Ming Li ji-Hong Ouyang College of Computer Science and Technology Jilin University Changchun 130000 China Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education Jilin University Changchun 130000 China

Stochastic variational inference （SVI） can learn topic models with very big corpora. It optimizes the variational objective by using the stochastic natural gradient algorithm with a decreasing learning rate. This rate is crucial for SVI; however, it is often tuned by hand in real applications. To address this, we develop a novel algorithm, which tunes the learning rate of each iteration adaptively. The proposed algorithm uses the Kullback-Leibler （KL） divergence to measure the similarity between the variational distribution with noisy update and that with batch update, and then optimizes the learning rates by minimizing the KL divergence. We apply our algorithm to two representative topic models： latent Dirichlet allocation and hierarchical Dirichlet process. Experimental results indicate that our algorithm performs better and converges faster than commonly used learning rates.

关键词： stochastic variational inference online learning adaptive learning rate topic model

Efficiency of Profinite Rigidity of Triangle Groups

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Acta Mathematica Sinica,English Series 2022年第10期38卷 1939-1948页

作者： ji Ming MA Zi xi WANG School of Mathematical Sciences Fudan UniversityShanghai 200433P.R.China

It is already known that finitely-generated Fuchsian groups are profinitely rigid among all lattices of connected Lie groups by the result of Bridson,Conder and *** the triangle groups are distinguished among themselves by their finite *** focus on the question about quantifying the size of a quotient which separates two triangle groups and give an explicit upper bound.

关键词： Triangle groups profinite completion finite quotients

Preparation of High Activity Admixture from Steel Slag,Phosphate Slag and Limestone Powder

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Journal of Renewable Materials 2023年第11期11卷 3977-3989页

作者： Ying ji xi Liu College of Materials Science and Engineering Xi’an University of Architecture&TechnologyXi’an710055China

The problem of low disposal and utilization rate of bulk industrial solid waste needs to be *** this paper,a high-activity admixture composed of steel slag-phosphate slag-limestone powder was proposed for most of the solid waste with low activity and a negative impact on concrete workability,combining the characteristics of each solid *** paper demonstrates the feasibility and explains the principle of the composite system in terms of water requirement of standard consistency,setting time,workability,and mechanical properties,combined with the composition of the phases,hydration temperature,and microscopic *** results showed that the steel slag:phosphate slag:limestone=5:2:3 gave the highest activity of the composite system,over 92%.Besides,the composite system had no significant effect on water demand and setting time compared to cement,and it could significantly increase the 7 and 28 d activity of the *** composite system delayed the exothermic hydration of the cement and reduced the exothermic heat but had no effect on the hydration ***,the research in this paper dramatically improved the solid waste dissipation in concrete,reduced the amount of cement in concrete and positively responded to the national slogan of carbon neutral and peaking.

关键词： Steel slag phosphorus slag limestone powder high activity admixture solid waste

RECURSIVE INTEGRAL METHOD FOR THE NONLINEAR NON-SELFADJOINT TRANSMISSION EIGENVALUE PROBLEM

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Journal of Computational Mathematics 2017年第6期35卷 828-838页

作者： Yingxia xi xia ji LSEC NCMIS Institute of Computational Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

The transmission eigenvalue problem is an eigenvalue problem that arises in the scatter- ing of time-harmonic waves by an inhomogeneous medium of compact support. Based on a fourth order formulation, the transmission eigenvalue problem is discretized by the Mor- ley element. For the resulting quadratic eigenvalue problem, a recursive integral method is used to compute real and complex eigenvalues in prescribed regions in the complex plane. Numerical examples are presented to demonstrate the effectiveness of the proposed method.

关键词： Transmission eigenvalue problem Nonlinear eigenvalue problem Contour integrals.

Distributed cooperative deployment strategy in multi-UAVs assisted heterogeneous networks

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The Journal of China Universities of Posts and Telecommunications 2021年第3期28卷 11-19页

作者： Zhang Yi Zhang Heli ji Hong Li xi School of Information and Communication Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China

Unmanned aerial vehicle base stations(UAV-BSs)can provide a fast network deployment scheme for heterogeneous ***,unmanned aerial vehicle(UAV)has limited capability and cannot assist the base station(BS)*** ability of a UAV to assist the BSs is limited,and the cluster deployment relies on the leading *** dispersive deployment of multiple UAVs(multi-UAVs)need a macro base station(MBS)to determine their positions to prevent collisions or ***,a distributed cooperative deployment scheme is proposed for UAVs to solve this *** scheme can increase the ability of UAVs to assist users and reduce the pressure on BSs to deploy ***,the randomly distributed users are *** the placement problem was modeled as a circle expansion problem and a pre-clustering radius expansion algorithm was *** the constraint of users'data rates,it provides services for more ***,the proposed algorithm was compared with the density-aware placement *** simulation results show that the proposed algorithm can provide services for more users and improve the coverage rate of users while ensuring the data rates.

关键词： unmanned aerial vehicle base stations(UAV-BSs) distributed cooperative pre-clustering radius expansion algorithm unmanned aerial vehicles(UAVs)deployment

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