检索结果-南通市图书馆

Growth,optical dispersion and magnetic behavior of Dy^(3+) doped yttrium iron garnet crystals

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 Rare Earths 2024年第6期42卷 1110-1117,I0004页

作者： Yating Fang Hui Shen Yudie Ma Shijie Liao Shuang Xia Tian Tian Ding Zhou Yunfeng Ma Jiayue Xu Institute of Crystal Growth School of Materials Science and EngineeringShanghai Institute of Technology National engineering Center of Electromagnetic Radiation Control Materials School of Electronic Science and EngineeringUniversity of Electronic Science and Technology of China

Y_(3)Fe_(5)O_(12)(YIG)crystals are highly desirable for the fabrication of mid-infrared isolators with the rapid growth of optical communications,although it is rather challenging to grow large size and high-quality single ***^(3+)doping is expected to improve the optical and magneto-optical prope ***,high quality Dy:YIG crystals and the adjustment of Dy^(3+)on the structure and optical behavior of YIG crystal remain unclear,impeding its practical ***,a series of Y_(3-x)Dy_(x)Fe_(5)O_(12)(x=0,0.5,1.0,1.5,3)solid solution crystals was grown by the flux-Bridgman method and single crystals up to 25 mm were *** the introduction of Dy^(3+),lattice parameters are gradually enlarged from 1.2379 nm(YIG)to 1.2420 nm(DyIG).Typical Dy^(3+)absorption peaks are observed around 1070,1265 and 1670 *** refractive index decreases from 2.37(500 nm)to 2.10(2500 nm)for YIG crystal,and it reduces from 2.47(500 nm)to 2.16(2500 nm)for DyIG *** optical bandgaps remain almost unchanged for Dy:YIG *** optical dispersion of the refractive indices was finely fitted by the Wemple and DiDomenico(WDD)and the Sellmeier models,*** the increase of Dy^(3+)content,the saturation magnetization(Ms)decreases significantly from 23.62 emu/g(YIG)to 5.33 emu/g(DyIG).Small coercive field is persisted for this system,endowing small external magnetic *** results provide valuable references for the manipulation of rare earths on the properties of magnetooptical crystals,which is beneficial to the design of high-performance garnet crystals for the application of optical switching and non-reciprocal related devices.

关键词： Magneto-optical crystal Yttrium iron garnet Dy^(3+)doping Crystal growth Optical dispersion Rare earths

Effective Capacity of URLLC over Parallel Fading Channels with Imperfect Channel State Information

在线全文

学校读者我要写书评

暂无评论

China Communications 2024年第5期21卷 45-63页

作者： Peng Hongsen Tao Meixia department of electronic engineering and the Cooperative Medianet Innovation Center Shanghai Jiao Tong UniversityShanghai 200240China

This paper investigates the effective capacity of a point-to-point ultra-reliable low latency communication(URLLC)transmission over multiple parallel sub-channels at finite blocklength(FBL)with imperfect channel state information(CSI).Based on reasonable assumptions and approximations,we derive the effective capacity as a function of the pilot length,decoding error probability,transmit power and the sub-channel *** we reveal significant impact of the above parameters on the effective capacity.A closed-form lower bound of the effective capacity is derived and an alternating optimization based algorithm is proposed to find the optimal pilot length and decoding error *** results validate our theoretical analysis and show that the closedform lower bound is very *** addition,through the simulations of the optimized effective capacity,insights for pilot length and decoding error probability optimization are provided to evaluate the optimal parameters in realistic systems.

关键词： effective capacity finite blocklength regime imperfect CSI parallel fading channels URLLC

Kinematic-mapping-model-guided analysis and optimization of 2-PSS&1-RR circular-rail parallel mechanism for fully steerable phased array antennas

在线全文

学校读者我要写书评

暂无评论

Defence Technology 2024年第8期38卷 136-154页

作者： Guodong Tan Xiangfei Meng Xuechao Duan Lulu Cheng Dingchao Niu Shuai He Dan Zhang Laboratory of Electromechanical Coupling in electronic Equipment Xidian University department of Mechanical engineering The Hong Kong Polytechnic University

This paper presents a systematic methodology for analyzing and optimizing an innovative antenna mount designed for phased array antennas, implemented through a novel 2-PSS&1-RR circular-rail parallel mechanism. Initially, a comparative motion analysis between the 3D model of the mount and its full-scale prototype is conducted to validate effectiveness. Given the inherent complexity, a kinematic mapping model is established between the mount and the crank-slider linkage, providing a guiding framework for subsequent analysis and optimization. Guided by this model, feasible inverse and forward solutions are derived, enabling precise identification of stiffness singularities. The concept of singularity distance is thus introduced to reflect the structural stiffness of the mount. Subsequently, also guided by the mapping model, a heuristic algorithm incorporating two backtracking procedures is developed to reduce the mount's mass. Additionally, a parametric finite-element model is employed to explore the relation between singularity distance and structural stiffness. The results indicate a significant reduction(about 16%) in the antenna mount's mass through the developed algorithm, while highlighting the singularity distance as an effective stiffness indicator for this type of antenna mount.

关键词： Backtracking Circular rail Crank-slider linkage Innovative antenna mount Kinematic mapping model Stiffness singularity

Wideband low-scattering metasurface with an in-band reconfigurable transparent window

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第2期33卷 334-341页

作者：朱瑛杨维旭段坤姜田赵俊明陈克冯一军 School of electronic Science and engineering Nanjing UniversityNanjing 210023China

Active metasurfaces with dynamically reconfigurable functionalities are highly demanded in various practical ***,we propose a wideband low-scattering metasurface that can realize an in-band reconfigurable transparent window by altering the operation states of the PIN diodes loaded on the *** metasurface is composed of a band-pass frequency selective surface(FSS)sandwiched between two polarization conversion metasurfaces(PCMs).PIN diodes are integrated into the FSS to switch the transparent window,while a checkerboard configuration is applied in PCMs for the diffusive-reflective function.A sample with 20×20 elements is designed,fabricated,and experimentally *** simulated and measured results show that the in-band functions can be dynamically switched between beam-splitting scattering and high transmission by controlling the biasing states of the diodes,while low backscattering can be attained outside the ***,the resonant structures of FSS also play the role of feeding lines,thus significantly eliminating extra interference compared with conventional feeding *** envision that the proposed metasurface may provide new possibilities for the development of an intelligent stealth platform and its antenna applications.

关键词： metasurface reconfigurable transparent window radar cross section(RCS)reduction

Diamond-based electron emission:Structure,properties and mechanisms

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第9期33卷 165-177页

作者： Liang-Xue Gu Kai Yang Yan Teng Wei-Kang Zhao Geng-You Zhao Kang-Kang Fan Bo Feng Rong Zhang You-Dou Zheng Jian-Dong Ye Shun-Ming Zhu Kun Tang Shu-Lin Gu School of electronic Science and engineering Nanjing UniversityNanjing 210046China

Diamond has an ultrawide bandgap with excellent physical properties,such as high critical electric field,excellent thermal conductivity,high carrier mobility,*** with a hydrogen-terminated(H-terminated)surface has a negative electron affinity(NEA)and can easily produce surface electrons from valence or trapped electrons via optical absorption,thermal heating energy or carrier transport in a PN *** NEA of the H-terminated surface enables surface electrons to emit with high efficiency into the vacuum without encountering additional barriers and promotes further development and application of diamond-based emitting *** article reviews the electron emission properties of H-terminated diamond surfaces exhibiting NEA *** electron emission is induced by different physical *** advancements in electron-emitting devices based on diamond are also ***,the current challenges and future development opportunities are discussed to further develop the relevant applications of diamond-based electronemitting devices.

关键词： diamond negative electron affinity (NEA) PN junction electron emission

SmartMicro Grid Energy System Management Based on Optimum Running Cost for Rural Communities in Rwanda

在线全文

学校读者我要写书评

暂无评论

Energy engineering 2024年第7期121卷 1805-1821页

作者： Fabien Mukundufite Jean Marie Vianney Bikorimana Alexander Kyaruzi Lugatona Electrical and electronic engineering department University of RwandaKigaliRwanda Electrical engineering department University of Dar es SalaamDar es SalaamTanzania

The governmental electric utility and the private sector are joining hands to meet the target of electrifying all households by ***,the aforementioned goal is challenged by households that are scattered in remote *** far,Solar Home Systems(SHS)have mostly been applied to increase electricity access in rural *** have continuous constraints to meet electricity demands and cannot run income-generating *** current research presents the feasibility study of electrifying Remera village with the smart microgrid as a case *** renewable energy resources available in Remera are the key sources of electricity in that *** generation capacity is estimated based on the load *** microgrid configurations are simulated with HOMER,and the genetic algorithm is used to analyze the optimum *** analyzing the impact of operation and maintenance costs,the results show that the absence of subsidies increases the levelized cost of electricity(COE)five times greater than the electricity price from the public *** microgrid made up of PV,diesel generator,and batteries proved to be the most viable solution and ensured continuous power supply to *** considering the subsidies,COE reaches 0.186$/kWh,a competitive price with electricity from public utilities in Rwanda.

关键词： Load demand load profile optimum running cost power demand satisfaction smart meters and smart micro grid

Fabrication of YAG:Ce^(3+) and YAG:Ce^(3+),Sc^(3+) Phosphors by Spark Plasma Sintering Technique

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 Wuhan University of Technology(Materials Science) 2024年第2期39卷 255-260页

作者：周卫新娄朝刚 School of electronic Science and engineering Southeast UniversityNanjing 210096China

In this study,a single-doped phosphors yttrium aluminum garnet(Y_(3)Al_(5)O_(12),YAG):Ce^(3+),single-doped YAG:Sc^(3+),and double-doped phosphors YAG:Ce^(3+),Sc^(3+) were prepared by spark plasma sintering(SPS)(lower than 1 200℃).The characteristics of synthesized phosphors were determined using scanning electron microscopy(SEM),X-ray diffraction(XRD),and fluorescence *** SPS,the lattice structure of YAG was maintained by the added Ce^(3+) and Sc^(3+).The emission wavelength of YAG:Ce^(3+) prepared from SPS(425-700 nm) was wider compared to that of YAG:Ce^(3+) prepared from high-temperature solid-state reaction(HSSR)(500-700 nm).The incorporation of low-dose Sc^(3+) in YAG:Ce^(3+) moved the emission peak towards the short wavelength.

关键词： high-temperature solid-state reaction spark plasma sintering yttrium aluminum garnet phosphors

Constructions of optimal binary locally repairable codes via intersection subspaces

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第6期67卷 418-432页

作者： Wenqin ZHANG Deng TANG Chenhao YING Yuan LUO School of electronic Information and Electrical engineering Shanghai Jiao Tong University

Locally repairable codes（LRCs）, which can recover any symbol of a codeword by reading only a small number of other symbols, have been widely used in real-world distributed storage systems, such as Microsoft Azure Storage and Ceph Storage Cluster. Since binary linear LRCs can significantly reduce coding and decoding complexity, constructions of binary LRCs are of particular interest. The aim of this paper is to construct dimensional optimal binary LRCs with disjoint local repair groups. We introduce a method to connect intersection subspaces with binary LRCs and construct dimensional optimal binary linear LRCs with locality 2b（b 3） and minimum distance d 6 by employing intersection subspaces deduced from the direct sum. This method will sufficiently increase the number of possible repair groups of dimensional optimal LRCs, thus efficiently expanding the range of the construction parameters while keeping the largest code rates compared with all known binary linear LRCs with minimum distance d 6 and locality 2b.

关键词： locally repairable codes disjoint local repair groups distributed storage systems intersection subspaces direct sum

Accurate Distinction of Weak and Strong AC Grids for Emerging Hierarchical-Infeed LCC-UHVDC Systems

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2024年第2期10卷 772-777页

作者： Hao Xiao Xianzhong Duan Yi Zhang department of Electrical and Computer engineering University of ManitobaWinnipeg R3T 2N2ManitobaCanada State Key Laboratory of Advanced Electromagnetic engineering and Technology Hubei Electric Power Security and High Efficiency Key LaboratorySchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074HubeiChina RTDS Technologies Inc. Winnipeg R3T 2E1ManitobaCanada

Distinction of weak and strong AC grids for emerging hierarchical-infeed LCC-UHVDC systems is important for planning and operation departments. However, accuracy of earlier distinction methods is limited as they were developed by empirical reasoning without rigorous theoretical analysis. Hence in this letter, hierarchical-infeed interactive effective short-circuit ratio (HIESCR) index is first used for strength evaluation of HIDC systems with complex inter-inverter interactions considered. Boundary HIESCR (BHIESCR) is also introduced in the proposed distinction method of weak and strong AC grids. That is, weak (or strong) AC grids are, respectively, identified when HIESCR is less (or greater) than BHIESCR. Second, it is shown BHIESCR remains almost unchanged as 3.0 versus various system parameters and rated operation variables based on rigorous theoretical analysis. This salient feature makes the proposed method more accurate than earlier methods. Finally, the proposed method is validated by simulations based on the PSCAD/EMTDC program.

关键词： Hierarchical-Infeedinteractive effective short-circuit ratio hierarchical-infeed LCC-UHVDC systems inter-inverter interactions strong AC grids weak AC grids