检索结果-南通市图书馆

Ionic liquids for electrochemical energy storage devices applications

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of materials Science & technology 2019年第4期35卷 674-686页

作者： Huan Liu Haijun Yu College of materials Science & Engineering Key Laboratory of Advanced Functional MaterialsMinistry of EducationBeijing University of Technology

Ionic liquids, defined here as room-temperature molten salts, composed mainly of organic cations and(in)organic anions ions that may undergo almost unlimited structural variations with melting points below 100?C. They offer a unique series of physical and chemical properties that make them extreme important candidates for several energy applications, especially for clean and sustainable energy storage and conversion materials and devices. Ionic liquids exhibit high thermal and electrochemical stability coupled with low volatility, create the possibility of designing appropriate electrolytes for different type batteries and supercapacitors. Herein, varieties of ionic liquids applications are reviewed on their utilization as electrolytes for Li-ion batteries, Na-ion batteries, Li-O_2(air) batteries, Li-Sulfur(Li-S) batteries, supercapacitors and as precursors to prepare and modify the electrode materials, meanwhile,some important research results in recent years are specially introduced, and the perspective on novel application of ionic liquids is also discussed.

关键词： Ionic liquids Batteries Supercapacito Electrolyte Electrode

Effect of copper on magnetostriction and mechanical properties of TbDyFe alloys

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2019年第1期37卷 68-73,M0004页

作者： Naijuan Wang Yuan Liu Huawei Zhang Xiang Chen Yanxiang Li School of materials Science and Engineering Tsinghua University key laboratory for advanced materials Processing technology Ministry of Education

The intrinsic brittleness of the TbDyFe alloy significantly decreases its mach inability and *** paper aims to improve the toughness of TbDyFe alloy by adding Cu. Various alloys of the type(Tb_(0.3)Dy_(0.7))_(0.37)Fe_(0.63-χ)Cu_χ(χ=0, 0,01.0.03, 0.05, 0.08, 0.1) were fabricated by an arc melting furnace under a high purity argon atmosphere. The microstructure, magnetostrictive properties and mechanical performance were studied systematically. The results show that the (Tb,Dy)Cu phase forms in these alloys upon the addition of Cu. Correspondingly, their toughness improves, attributed to the formation of a (Tb,Dy)Cu phase. Compared to the Cu-free alloy, the fracture toughness (Kic) increases 2-3 times with increasing Cu content. However, the magnetostriction performance of these alloys declines with Cu addition, due to the low-magnetic performance of the (Tb,Dy)Cu phase at room temperature. Compared with other alloys, the alloy with the addition of 1at%Cu shows the best compromise between the saturation magnetostriction and fracture toughness.

关键词： TbDyFeCu alloy Microstructure Magnetostriction Mechanical performance Rare earths

Simulation of the Dendrite Morphology and Microsegregation in Solidification of Al–Cu–Mg Aluminum Alloys

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2015年第2期28卷 173-181页

作者： Rui Chen Qing-Yan Xu Bai-Cheng Liu key laboratory for advanced materials Processing technology Ministry of Education School of Materials Science and Engineering Tsinghua University

Since most typical alloys in industrial applications are multicomponent with three or more components, and various CA models proposed in the past mainly focus on the binary alloys, a two-dimensional modified cellular automaton model allowing for the quantitatively predicting dendrite growth of multicomponent alloys in the low P6clet number regime is presented. The elimination of the mesh-induced anisotropy is achieved by adopting a modified virtual front tracking method. A new efficient method based on the lever rule is applied to calculate the solid fraction increment of the interfacial cells. The thermodynamic data such as liquidus temperature, the partition coefficients, and the slope of liquidus surface, needed for determining the dynamics of dendrite growth, are obtained by coupling with PanEngine. This model is applied to simulate the dendrite morphology and microsegregation of A1-Cu-Mg temary alloy both for single and multi- dendrites growth. The simulated results demonstrate that the difference of the concentration distribution profiles ahead of the dendrite tip for each alloying element mainly results from the different partition coefficients and solute diffusion coefficients. Comparison with the prediction of analytical model is carded out and it reveals the correctness of the model. Consequently, the difference in interdendritic microsegregation behavior of different components is analyzed.

关键词： Cellular automaton Multicomponent Dendrite growth Microsegregation

Numerical simulation of macrosegregation during solidification of binary alloys

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2016年第8期35卷 591-597页

作者： Wu-Tao Tu Hou-Fa Shen Bai-Cheng Liu key laboratory for advanced materials Processing technology Ministry of Education School of Materials Science and Engineering Tsinghua University

Macrosegregation as a consequence of solidifi- cation of a binary Pb-48 wt% Sn alloy in two-dimensional rectangle cavity was investigated by two-phase model instead of the common used continuum model. The macroscopic transport of mass, momentum, species and energy was cou- pled with the microscopic descriptions of grain nucleation and growth. The mathematic equations of the two-phase model were discretized on staggered grids and solved by the finite volume method. The final tin concentrations along different heights over the bottom face were compared with the ex- periment measurements. Simulations with different mi- crostructure parameters （second dendrite arm spacing （SDAS）） were conducted to ascertain the influence of microstructure on the final macrosegregation. The results show that with the decrease in SDAS value, the drag force as the resistance to relative motion between solid and liquid phase increases, and the macrosegregation during solidification is alleviated.

关键词： Macrosegregation Two-phase model Solidification Second dendrite arm spacing

Progress in recycling of Nd–Fe–B sintered magnet wastes

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2019年第7期28卷 14-24页

作者： Ming Yue Xiaowen Yin Weiqiang Liu Qingmei Lu College of materials Science and Engineering Key Laboratory of Advanced Functional Materials(Ministry of Education)Beijing University of Technology

Significant efforts have been put into the recycling of bulk Nd–Fe–B sintered magnet wastes around the world in the past decade because bulk Nd–Fe–B sintered magnet wastes are valuable secondary rare-earth *** are two major facts behind the ***, the waste magnets contain total rare-earth content as high as more than 30 wt.%, which is higher than most natural rare-earth ***, the waste magnets maintain the physical and chemical properties of the original magnets even with deterioration of the properties on surfaces due to corrosion and *** this review,various techniques for recycling bulk Nd–Fe–B sintered magnet wastes, the overall properties of the recycled Nd–Fe–B sintered magnets, and the mass production of recycled magnets from the wastes are reviewed.

关键词： Nd–Fe–B sintered magnet rare-earth resource recycling

A Numerical Study of the Effect of Multiple Pouring on Macrosegregation in a 438-Ton Steel Ingot

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2015年第9期28卷 1123-1133页

作者： Zhen-Hu Duan Hou-Fa Shen Bai-Cheng Liu key laboratory for advanced materials Processing technology Ministry of Education School of materials Science and Engineering Tsinghua University

In present paper, a ladle-tundish-mold CFD model and a macrosegregation model were utilized to investigate the effects of the multiple pouring （MP） process on the macrosegregation in a 438-ton steel ingot. Firstly, the model was partially proved as compared to the measured carbon distributions along the transverse sections in the riser of ingot. Then, the comparison between the single pouring （SP） and MP process has been carried out to study their influences on the macrosegregation in ingot. Besides, the predicted macrosegregation results in MP process which introduced the improved riser fixed with an insulating sleeve were compared with that in traditional MP process. The traditional MP process leads to certain favorable initial carbon distribution in the mold, which has some favorable influence on suppressing the positive segregation in ingot. The holding time of the low carbon in the riser is the main factor to suppress the positive segregation in ingot. Improved insulating sleeve can prolong the holding time of the low carbon in the riser and release the positive segregation in the riser of ingot. Improvement of the insulating effect of the riser is an efficient method to control macrosegregation in large steel ingot.

关键词： Multiple pouring process Macrosegregation Numerical simulation Large steel ingot

E-PRedictor: an approach for early prediction of pull request acceptance

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2025年

作者： Kexing CHEN Lingfeng BAO Xing HU Xin XIA Xiaohu YANG State key laboratory of Blockchain and Data Security Zhejiang University Software Engineering Application technology lab

A pull request (PR) is an event in Git where a contributor asks project maintainers to review code he/she wants to merge into a project. The PR mechanism greatly improves the efficiency of distributed software development in the opensource community. Nevertheless, the massive number of PRs in an open-source software (OSS) project increases the workload of developers. To reduce the burden on developers, many previous studies have investigated factors that affect the chance of PRs getting accepted and built prediction models based on these factors. However, most prediction models are built on the data after PRs are submitted for a while (e.g., comments on PRs), making them not useful in practice. Because integrators still need to spend a large amount of effort on inspecting PRs. In this study, we propose an approach named E-PRedictor (earlier PR predictor) to predict whether a PR will be merged when it is created. E-PRedictor combines three dimensions of manual statistic features (i.e., contributor profile, specific pull request, and project profile) and deep semantic features generated by BERT models based on the description and code changes of PRs. To evaluate the performance of E-PRedictor, we collect475192 PRs from 49 popular open-source projects on GitHub. The experiment results show that our proposed approach can effectively predict whether a PR will be merged or not. E-PRedictor outperforms the baseline models (e.g., Random Forest and VDCNN) built on manual features significantly. In terms of F1@Merge, F1@Reject, and AUC (area under the receiver operating characteristic curve), the performance of E-PRedictor is 90.1%, 60.5%, and 85.4%, respectively.

关键词：

Day-ahead Electricity Price Prediction Method Based on Similar Day Screening and Combined Deep Learning Modeling

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Dianwang Jishu/Power System technology 2025年第1期49卷 242-251页

作者： Ai, Yu Jia, Yanbing Han, Xiaoqing Shanxi key laboratory of Power System Operation and Control Taiyuan University of Technology Shanxi Province Taiyuan 030024 China key laboratory of Cleaner Intelligent Control on Coal & Electricity Taiyuan University of Technology Ministry of Education Shanxi Province Taiyuan 030024 China

Accurate day-ahead electricity price prediction is the basis for market operation and policy planning, while market disclosure information is essential for electricity price prediction. This paper proposes a combined CNN-GRU deep-learning electricity price prediction model introducing the Self-attention mechanism. Firstly, for the trading process of the Shanxi electricity spot market and the formation mechanism of electricity price before the day, it is proposed to adopt the maximum mutual information coefficient method to extract features from the market disclosed information data such as boundary conditions before the day, to determine the key influencing factors of electricity price and its weight coefficients;and then based on the weighted grey correlation of the history of similar day screening method to generate the historical dataset of electricity price prediction, and to excavate the internal change rule of electricity price and its features;Finally, the CNN-GRU model introducing Self-attention mechanism is used to get the predicted electricity price based on the historical data set. The effectiveness and accuracy of the prediction method proposed in this paper are verified through examples. © 2025 Power System technology Press. All rights reserved.

关键词：

Non-existence of Shimura curves of Mumford type generically in the non-hyperelliptic locus

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Mathematics 2025年

作者： Xin Lü Shengli Tan Kang Zuo School of Mathematical Sciences Key Laboratory of Mathematics and Engineering Applications(Ministry of Education) Shanghai Key Laboratory of Pure Mathematics and Mathematical PracticeEast China Normal University School of Mathematics and Statistics Wuhan University Institut für Mathematik Universit?t Mainz

We show that there does not exist any Shimura curve with a strictly maximal Higgs field generically in the Torelli locus of non-hyperelliptic curves of genus g≥4. In particular, Shimura curves of Mumford type are not...

关键词：