检索结果-内蒙古大学图书馆

SSRN 2024年

作者： Takeuchi, Nobuaki Iizuka, Masatoshi Kosuke, Kemmotsu Ando, Daisuke Ishida, Kiyohito Sutou, Yuji Department of Materials Science Graduate School of Engineering Tohoku University Sendai980-8579 Japan Advanced Institute for Materials Research Tohoku University Sendai980-8577 Japan

Metallic alloys typically follow the Mooij rule, which describes the trade-off relationship between electrical resistivity and the temperature coefficient of resistivity (TCR). Fe-20Mn-11Al-5Cr-1C-0.01B (mass%) alloy, annealed at temperatures ranging from 600℃ to 1000℃, deviates from the Mooij rule and exhibits excellent electrical properties, including high electrical resistivity and low TCR. X-ray diffraction measurements revealed that the constituent phases of the alloys are α-, γ-, κ-, and carbide phases. TCR is significantly influenced by the fraction of α-phase, the concentration of solute elements in the matrix phases, magnetism, and the quantity of precipitated carbides in the matrix. The results indicate that controlling the microstructure of metallic alloys can achieve high resistivity and low TCR, thereby deviating from the Mooij rule. © 2024, The Authors. All rights reserved.

关键词： Microstructure

来源：评论

学校读者我要写书评

暂无评论

A High Efficiency Hybrid Modular Multilevel Converter with a SiC Device-Based External Shaping Module

引用

IEEE Transactions on Power Electronics 2025年

作者： Ren, Peng Guo, Qi Hou, Yuchao Tu, Chunming Zhu, Donghai Sun, Kai Wang, Lei Xiao, Fan Hunan University College of Electrical and Information Engineering Changsha410082 China Tsinghua Shenzhen International Graduate School Shenzhen518000 China Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic Engineering Wuhan430074 China Tsinghua University State Key Lab of Power Systems Department of Electrical Engineering Beijing100084 China

In order to improve the waveform quality and efficiency of medium voltage modular multilevel converter (MMC), a hybrid MMC (HMMC) topology with an external shaping module is proposed. Each arm of the HMMC consists of N half-bridge submodules (HSMs) based on Si IGBT, while a full-bridge submodule (FSM) based on SiC MOSFET on the ac side. Furthermore, a 2N+1 level hybrid modulation strategy is proposed for this topology. The HSMs operate in the low-frequency state to output the staircase wave voltage, while the FSM operates in the high-frequency state to reduce the harmonics of the output voltage. It makes full use of the advantages of low on-state loss of Si devices and low switching loss of SiC devices. Additionally, the energy fluctuation of the HMMC submodules is analyzed in detail, and a voltage balancing scheme is proposed. In the end, the feasibility and effectiveness of the proposed topology and modulation method are validated by simulation and experimental studies on a single-phase HMMC. Moreover, the comparison of cost and loss between HMMC and existing MMCs proves that the proposed HMMC can better balance the device cost and operating loss. © 1986-2012 IEEE.

关键词： Silicon carbide

来源：评论

学校读者我要写书评

暂无评论

Microstructure Observation of T-Phases in Al-Zn-Mg Alloy with Low Zn/Mg Ratio

SSRN

引用

SSRN 2024年

作者： Ahmed, Abrar Lee, Seungwon Tsuchiya, Taiki Matsuda, Kenji Nishimura, Katsuhiko Numomura, Norio Toda, Hiroyuki Hirayama, Kyosuke Shimizu, Kazuyuki Yamaguchi, Masatake Tsuru, Tomohito Graduate School of Science and Engineering for Education University of Toyama Toyama930-8555 Japan Graduate School of Science and Engineering for Research University of Toyama Toyama930-8555 Japan Department of Mechanical Engineering Kyushu University Fukuoka819-0395 Japan Department of Materials Science and Engineering Kyoto University Kyoto606-8501 Japan Graduate School of Science and Engineering Tottori University 4-101 kyoama Minami Tottori Japan Center for Computational Science and e-Systems Japan Atomic Energy Agency Tokai Ibaraki319-1195 Japan Nuclear Science and Engineering Center Japan Atomic Energy Agency Tokai Ibaraki319-1195 Japan

For the first time, this study clarifies the T'', T', and T phases in Al-Zn-Mg alloy with a low Zn/Mg ratio and evaluates the shape of the precipitate morphology according to different zone directions of the Al matrix. The orientation relationship, shape, misfit, and interfacial conditions between the T'', T', and T phases and the Al matrix were investigated using high-resolution transmission electron microscopy (HR-TEM). We differentiated the T'' (1.387 nm), T' (1.422 nm), and T (1.456 nm) phases by calculating the lattice parameters in HR-TEM images. We also identified the T'', T', and T phases by diffraction patterns along the , , , and zone directions of the Al matrix. Additionally, we introduce the different orientation relationships of the T phase with the Al matrix, The [[[EQUATION]]0] zone direction of the Al is parallel to the [[[EQUATION]]20] direction of the T-phase, and the plane of ([[EQUATION]]1) of the Al is parallel to the plane of ([[EQUATION]]) of the T-phase. Among Al alloys, the 7xxx series is known for its superior strength due to the co-precipitation of the η and T phases. While previous research has extensively examined the precipitation sequence, composition, atomic structure, and phase transformation mechanisms of the η phase, the T phase has received less attention. Our observations provide insight into the behavior of T phase crystals, which is crucial for understanding the microstructural evolution of Al-Zn-Mg alloys and for designing materials with desired properties. © 2024, The Authors. All rights reserved.

关键词： High resolution transmission electron microscopy

来源：评论

学校读者我要写书评

暂无评论

New Level-Set-Based Shape Recovery Method and its application to sparse-view shape tomography 21

New Level-Set-Based Shape Recovery Method and its applicatio...

引用

2021 4th International Conference on Digital Medicine and Image Processing

作者： Haytham A. Ali Hiroyuki Kudo Department of Computer Science Graduate School of Systems and Information Engineering University of Tsukuba Japan and Department of MathematicsFaculty of Science Sohag University Egypt Department of Computer Science Graduate School of Systems and Information Engineering University of Tsukuba Japan

ISBN: (纸本)9781450386487

The recovery of shapes from a few numbers of their projections is very important in Computed tomography. In this paper, we propose a novel scheme based on a collocation set of Gaussian functions to represent any object by using a limited number of projections. This approach provides a continuous representation of both the implicit function and its zero level set. We show that the appropriate choice of a basis function to represent the parametric level-set leads to an optimization problem with a modest number of parameters, which exceeds many difficulties with traditional level set methods, such as regularization, re-initialization, and use of signed distance function. For the purposes of this paper, we used a dictionary of Gaussian function to provide flexibility in the representation of shapes with few terms as a basis function located at lattice points to parameterize the level set function. We propose a convex program to recover the dictionary coefficients successfully so it works stably with only four projections by overcoming the issue of local-minimum of the cost function. Finally, the performance of the proposed approach in three examples of inverse problems shows that our method compares favorably to Sparse Shape Composition (SSC), Total Variation, and Dual Problem.

关键词： Compressed sensing Computed tomography Convex optimization Gaussian function Level set Reconstruction method Shape identification X-ray tomography

来源：评论

学校读者我要写书评

暂无评论

Continuous structural phase transition and antiferromagnetic order in ilmenite-type NiVO3

引用

Physical Review Materials 2024年第9期8卷 094402页

作者： Hajime Yamamoto Osamu Ikeda Takashi Honda Kenta Kimura Takuya Aoyama Kenya Ohgushi Akio Suzuki Kenji Ishii Daiju Matsumura Takuya Tsuji Shintaro Kobayashi Shogo Kawaguchi Matteo d’Astuto Tadashi Abukawa Institute of Multidisciplinary Research for Advanced Materials Department of Earth Science Graduate School of Science Institute of Materials Structure Science Department of Materials Science Graduate School of Engineering Department of Physics Graduate School of Science National Institutes for Quantum Science and Technology (QST) 1-1-1 Kouto Sayo-cho Sayo-gun Hyogo 679-5198 Japan 1-1-1 Kouto Sayo-cho Sayo-gun Hyogo 679-5198 Japan CNRS Grenoble INP Institut Néel F-38000 Grenoble France International Center for Synchrotron Radiation Innovation Smart

We investigate the crystal and electronic structures as well as magnetic properties of ilmenite-type NiVO3, which has attracted research interest as an S = 1 honeycomb lattice magnet. Ilmenite-type NiVO3 samples were synthesized under high-pressure and high-temperature conditions. Synchrotron x-ray diffraction and Rietveld refinement results demonstrated that NiVO3 underwent a continuous structural phase transition from the triclinic (P1¯) phase to the rhombohedral (R3¯) phase at 450 K. This transition is concomitant with the decomposition of the V-V dimers formed by the tetravalent V ions. X-ray absorption spectroscopy measurements confirmed that the Ni and V ions were divalent and tetravalent, respectively. Magnetic and specific heat measurements revealed that NiVO3 underwent an antiferromagnetic transition at 140 K, and a zigzag-type magnetic order with magnetic propagation vector k=(0,1/2,0) was observed by neutron diffraction measurements.

关键词： Antiferromagnetism Chemical bonding Crystal structure Magnetic order Magnetism Methods in magnetism Peierls transition Phase transitions Structural properties Antiferromagnets Ceramics Crystal structures Crystalline systems Inorganic compounds Magnetic insulators Mott insulators Nickelates Oxides Polycrystalline materials Strongly correlated systems Transition metal oxides Vanadates Crystallization Crystallography DC susceptibility measurements Magnetic techniques Magnetization measurements Neutron diffraction Neutron techniques Pressure techniques Sample preparation Sintering Specific heat measurements X-ray absorption near-edge spectroscopy X-ray absorption spectroscopy X-ray diffraction X-ray powder diffraction

来源：评论

学校读者我要写书评

暂无评论

Carbon Penetration Behavior of Cr-Mo Steel Specimen in Carburizing Above Eutectic Temperature 27

Carbon Penetration Behavior of Cr-Mo Steel Specimen in Carbu...

引用

27th Congress of the International Federation for Heat Treatment and Surface engineering, IFHTSE 2022 and European Conference on Heat Treatment 2022, ECHT 2022

作者： Yamamoto, Ryosuke Nishimoto, Akio Graduate School of Science and Engineering Kansai University Osaka564-8680 Japan JTEKT Thermo Systems Coporation Nara632-0084 Japan Department of Chemistry and Materials Engineering Faculty of Chemistry Materials and Bioengineering Kansai University Osaka564-8680 Japan

ISBN: (纸本)9783200085848

Carburizing and quenching are one of the surface modification treatments to impart mechanical properties to materials. Carburizing is a lengthy process, generally performed at approximately 1203 K. Conventional carburizing (gas carburizing or low pressure carburizing) is processed in batches. Consequently, this creates many in-process inventories, which negatively affects the production efficiency. To devise an efficient production process, it is necessary to reduce the carburizing duration. Carburizing is a carbon-diffusion phenomenon, and increasing the temperature accelerates the process. In this study, we investigated the carbon penetrating behavior of a steel specimen by carburization it at temperatures 1473 K to 1573 K, which are above the eutectic temperature of the specimen. A ring specimen-Cr-Mo steel (JIS SCM420) was used in this investigation. Methane and nitrogen gases were used for carburizing. The specimen was rapidly heated by induction heating in a carburized atmosphere and kept for processing at each temperature, followed by quenching. It was observed that the time required to reach the same total carburizing depth was 1/20 times of the treatment at 1203 K compared to that of the treatment at 1523 K. Moreover, the total carburizing depth variations followed the parabolic law, the Harris’s empirical formula. It was evident that carbon penetration is proportional to the duration of the carburizing process. The rate of carbon penetration per unit time varied exponentially with the carburizing temperature. The activation energy was calculated from the Arrhenius plot of carbon penetration rate, which was close to that in the decomposition reaction of methane. Thereby, it was verified that the carburizing reaction is rate-controlled by the decomposition reaction of methane. © 2022 Quaker Houghton. All right reserved.

关键词： Induction heating

来源：评论

学校读者我要写书评

暂无评论

Bilayer Cell Model and System Design of Highly Efficient Protonic Ceramic Fuel Cells

Bilayer Cell Model and System Design of Highly Efficient Pro...

引用

243rd ECS Meeting

作者： Otomo, J. Yamate, S. Ortiz-Corrales, J.A. Department of Transdisciplinary Science and Engineering School of Environment and Society Tokyo Institute of Technology 2-12-1 Ookayama Meguro Tokyo152-8550 Japan Department of Environment Systems Graduate School of Frontier Sciences The University of Tokyo 5-1-5 Kashiwanoha Chiba Kashiwa277-8563 Japan

ISBN: (纸本)9781607685395

A highly efficient power generation system was designed by minimizing leakage current in protonic ceramic fuel cells (PCFCs) using bilayer electrolytes. The best electrolyte designs are achieved by optimizing the cell efficiency based on the transport properties of electrolyte materials assuming hydrogen as fuel. In parallel, the effect of the electrodes on the overall cell performance was also considered. Additionally, a PCFC system was modeled using the designed cells. Two PCFC systems were investigated. One based on hydrogen as a fuel, and another based on methane as fuel. It was found that a bilayer electrolyte consisting of BaZr0.8Y0.2O3−δ (BZY) with a thin layer of lanthanum tungstate (La28-xW4+xO54+3x/2v2-3x/2) is the most effective at reducing leakage current at 600°C. For this cell, a system efficiency of 69% (LHV, DC) and 65% (LHV, AC) were obtained under the cell voltage of 0.93 V, with a leakage current ratio of less than 1%, and fuel utilization of 95% when using hydrogen as fuel. On the other hand, when methane was used as fuel, the efficiency increased up to 78% (LHV, DC) and 74% (LHV, AC). © The Electrochemical Society.

关键词： Hydrogen

来源：评论

学校读者我要写书评

暂无评论

Optimized Ensemble Algorithm for Predicting Metamaterial Antenna Parameters

引用

Computers, Materials & Continua 2022年第6期71卷 4989-5003页

作者： El-Sayed M.El-kenawy Abdelhameed Ibrahim Seyedali Mirjalili Yu-Dong Zhang Shaima Elnazer Rokaia M.Zaki Department of Communications and Electronics Delta Higher Institute of Engineering and TechnologyMansoura35111Egypt Faculty of Artificial Intelligence Delta University for Science and TechnologyMansoura35712Egypt Computer Engineering and Control Systems Department Faculty of EngineeringMansoura UniversityMansoura35516Egypt Centre for Artificial Intelligence Research and Optimization Torrens University AustraliaFortitude ValleyQLD 4006Australia Yonsei Frontier Lab Yonsei UniversitySeoul03722Korea School of Computing and Mathematical Sciences University of LeicesterLeicesterLE17RHUK Nile Higher Institute for Engineering and Technology MansouraEgypt Computer and Information Technology College Taif UniversityTaifSaudi Arabia Higher Institute of Engineering and Technology Kafrelsheikh Department of Electrical Engineering Shoubra Faculty of EngineeringBenha UniversityEgypt

Metamaterial Antenna is a subclass of antennas that makes use of metamaterial to improve *** antennas can overcome the bandwidth constraint associated with tiny *** learning is receiving a lot of interest in optimizing solutions in a variety of *** learning methods are already a significant component of ongoing research and are anticipated to play a critical role in today’s *** accuracy of the forecast is mostly determined by the model *** purpose of this article is to provide an optimal ensemble model for predicting the bandwidth and gain of the Metamaterial *** Vector Machines(SVM),Random Forest,K-Neighbors Regressor,and Decision Tree Regressor were utilized as the basic *** Adaptive Dynamic Polar Rose Guided Whale Optimization method,named AD-PRS-Guided WOA,was used to pick the optimal features from the *** suggested model is compared to models based on five variables and to the average ensemble *** findings indicate that the presented model using Random Forest results in a Root Mean Squared Error(RMSE)of(0.0102)for bandwidth and RMSE of(0.0891)for *** is superior to other models and can accurately predict antenna bandwidth and gain.

关键词： Metamaterial antenna machine learning ensemble model feature selection guided whale optimization support vector machines

来源：评论

学校读者我要写书评

暂无评论

Learning-Based Joint Recommendation, Caching, and Transmission Optimization for Cooperative Edge Video Caching in Internet of Vehicles

SSRN

引用

SSRN 2024年

作者： Cheng, Zhipeng Liu, Lu Liwang, Minghui Chen, Ning Fan, Xuwei School of Future Science and Engineering Soochow University Suzhou China School of Journalism and Communication Xiamen University Xiamen China The Department of Control Science and Engineering The Shanghai Research Institute for Intelligent Autonomous Systems Tongji University Shanghai China School of Informatics Xiamen University Xiamen China

In an era dominated by multimedia information, achieving efficient video transmission in the Internet of Vehicles (IoV) is crucial because of the inherent bandwidth constraints and network volatility within vehicular environments. In this paper, we propose a cooperative edge video caching framework designed to enhance video delivery efficiency in IoV by integrating joint recommendation, caching, and transmission optimization. Leveraging deep reinforcement learning with the discrete soft actor-critic algorithm, our methodology dynamically adapts to fluctuating network conditions and diverse user preferences, aiming to optimize both content delivery efficiency and quality of experience. The proposed approach seamlessly combines recommendation and caching strategies with transmission optimization to provide a comprehensive solution for high-performance video services. Extensive simulation results demonstrate that our framework significantly outperforms traditional baseline methods, achieving superior outcomes in terms of service utility, delivery rate, and delay reduction. These results highlight the robust potential of our solution to facilitate seamless and high-quality video experiences in the complex and dynamic landscape of vehicular networks, advancing the capabilities of IoV content delivery. © 2024, The Authors. All rights reserved.

关键词： Reinforcement learning

来源：评论

学校读者我要写书评

暂无评论

Navigation for precise walking of blind people based on pulling illusion devices embedded in white canes 4

Navigation for precise walking of blind people based on pull...

引用

4th IEEE Global Conference on Life sciences and Technologies, LifeTech 2022

作者： Nunokawa, Kiyohiko Tanabe, Takeshi Takizawa, Hotaka Doi, Kouki Ino, Shuichi Tokyo International University School of Human and Social Sciences Kawagoe Japan Industrial Science and Technology Human Informatics and Interaction Research Institute National Institute of Advanced Tsukuba Japan Information and Systems University of Tsukuba Faculty of Engineering Tsukuba Japan National Institute of Special Needs Education Department of Education Information Yokosuka Japan Osaka University Graduate School of Engineering Osaka Japan

ISBN: (纸本)9781665419048

There have been various types of navigation systems for the visually impaired. Many of them were designed to help the visually impaired walk long distances between large landmarks, such as houses and stations. Moreover, short distance navigation is required for the visually impaired. For example, consider a situation where a visually impaired person moves from a table to a counter in a food court. First, he/she can move roughly, but, near the counter, he/she needs to walk carefully not to collide with or pass through the counter. To the best of our knowledge, such a precise navigation has not been focused on in the past. In this study, we proposed a navigation device for precise walking of the visually impaired. The system comprises a white cane and a small vibration actuator embedded in the grip of the white cane. The actuator can generate asymmetric vibrations, enabling the user to feel a pulling illusion. Using this mechanism, the device can notify the user about the directions to walk. In addition, the actuator is so small and light that the user can use the device with one hand, such as the conventional white cane. Besides, we conducted a user study where two sighted participants who wore eye masked and three visually impaired participants walked 10 m to reach a target destination in a corridor environment to evaluate the proposed device's effectiveness. Based on the results, the device can guide the user precisely. © 2022 IEEE.

关键词： Actuators

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：