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A beam-Steering broadband Microstrip Antenna with High Isolation

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Chinese Journal of Electronics 2023年第2期32卷 325-333页

作者： JIANG Zhaoneng sha Yongxin NIE Liying XUAN Xiaofeng School of Computer and Information Hefei University of Technology School of Electronic Science and Applied Physics Hefei University of Technology

In this paper, a 4.2–7.2 GHz(52.6%)beam-steering microstrip antenna was proposed. The proposed antenna consists of three tapered slots and *** three radiation directions of the antenna on the plane are independent of each other, and the three feeds correspond to the three radiation structures. Symmetry isolation trenches are introduced to improve isolation between different ports. Radiation pattern simulation and measurement show horizontal beam steering at the sampled frequencies of 4.2, 5, 6, and 7.2 GHz. The results shows that the overlapped beam of the three ports in the Eplane and H-plane can cover more than 200 degrees and 60degrees, respectively. Apart from the capability of beamsteering, high isolation(more than 28 d b) of the proposed antenna in the operating band is obtained.

关键词： Antenna measurements Mutual coupling Slot antennas Microstrip antennas Antenna feeds Frequency measurement broadband antennas

Time-Domain Dual Component Computation Diversity based on Generalized Hybrid Carrier

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China Communications 2021年第10期18卷 148-157页

作者： Yuqing Feng Xuejun sha Yong Li Xiaojie Fang Yusi Zhang School of Electronics and Information Engineering Harbin Institute of TechnologyHarbin 150001China Science and Technology on Communication Networks Laboratory Shijiazhuang 050080China The 54th Research Institute of China Electronics Technology Group Corporation Shijiazhuang 050081China Engineering Research Center for Dedicated Communication System Ministry of EducationHarbin 150080China

In this paper,the concept of computation diversity is proposed by employing generalized hybrid carrier(GHC)*** signal is backed up by transform-domain computation to enhance the anti-fading *** analysis is presented to demonstrate the superiority of the proposed *** simulations in doubly-selective fading channels are provided to verify the *** bit error rate(bER)performance is guaranteed with a small computational complexity *** proposed method not only extends the new diversity dimension,but also improves the diversity gain of the system without occupying additional wireless ***,the proposed method shows good adaptability with single carrier modulation and improves diversity *** the simulation results shown,time-domain dual component computation diversity(TDC-CD)has 1d b bER gain and 0.1diversity gain at high signal-to-noise ratio,and single carrier system with TDC-CD achieves 2d b bER gain at 10~(-4).

关键词： TDC-CD transform domain GHC system diversity order

Microstructure and grain boundary morphology evolution of a novel Co-9Al-9W-2Ta-0.02b alloy doped with yttrium

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Rare Metals 2017年第12期36卷 951-961页

作者： Jian-Qiang Ma Fei Zhong Shu-Suo Li Jiang-bo sha School of Materials Science and Engineering Beihang University Beijing 100191 China

The microstructures and grain boundary morphologies of a novel Co-9 Al-9 W-2 Ta-0.02 b alloy doped with yttrium(Y)(0.01,0.05,0.10,and 0.20; at%) were investigated as functions of aging temperatures(900 and1000 ℃) and time(50 and 150 h). The aged alloys all exhibit a γ/γ’-Co(Al,W) coherent microstructure in grain interiors, whereas an intermetallic κ-Co(W) phase precipitates at grain boundaries. Y is found to fully segregate at grain boundaries and changes grain boundary precipitate morphologies. For 0.01 Y alloy, bright κ-Co(W) stripes precipitate along grain boundaries, where a needlelike κ-Co(W) phase grows from grain boundaries or κ-Co(W) stripes toward grain interior. As the nominal Y content increases, the stripe and needlelike κ-Co(W) precipitates at grain boundaries are strongly restrained and disappear in 0.20 Y alloy, leaving fine κ-Co(W) particles scattered at grain boundaries. It is noted that more Y segregation may increase the number of low-angle grain boundaries(LAbS, with misorientations of boundaries. Finally,the effect of Y segregation on tensile behavior of Co-AlW-Ta-b alloy was discussed from the viewpoints of grain boundary precipitate morphologies, grain boundary character distribution(GbCD), and impurity segregation.

关键词： Intermetallics Alloy design Grain boundary segregation Casting Microstructure

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社区获得性重症肺炎患者死亡风险因素探讨

医学信息 2024年第15期37卷 27-32页

作者：李卫东沈玄洋张美琪谭文涛将莎莎冯尧川北医学院附属医院急诊医学科

目的探讨社区获得性重症肺炎死亡相关危险因素，为进一步优化社区获得性重症肺炎治疗提供理论依据。方法回顾性收集2020年1月-2022年12月川北医学院附属医院住院的社区获得性重症肺炎患者资料，并将纳入的病例分为存活组与死亡组。通... 详细信息

目的探讨社区获得性重症肺炎死亡相关危险因素，为进一步优化社区获得性重症肺炎治疗提供理论依据。方法回顾性收集2020年1月-2022年12月川北医学院附属医院住院的社区获得性重症肺炎患者资料，并将纳入的病例分为存活组与死亡组。通过多因素Logistic回归分析死亡相关危险因素，联合实验室检查指标绘制受试者工作特征曲线(ROC曲线)分析各指标对社区获得性重症肺炎的预测价值。结果共收集了230例社区获得性重症肺炎病例，其中死亡组78例(33.91%)，存活组152例(66.09%)。两组年龄、性别、是否合并高血压、是否合并慢性阻塞性肺疾病比较，差异无统计学意义(P>0.05)；两组实验室指标中C反应蛋白(CRP)、降钙素原(PCT)、白介素6(IL-6)、N末端b型脑钠肽前体(NT-probNP)、丙氨酸氨基转移酶(ALT)、肌钙蛋白T(cTnT)、凝血酶原时间(PT)、乳酸(LAC)、D-二聚体(D-Dimer)和铁蛋白(Ferritin)比较，差异有统计学意义(P<0.05);LAC、IL-6、铁蛋白联合预测死亡风险的截断值0.174，约登指数0.858，灵敏度92.20%，特异度93.60%，其ROC曲线下面积(AUC)为0.968[95%CI(0.94,0.996)]。结论 LAC、IL-6、铁蛋白增高均是社区获得性重症肺炎死亡独立危险因素，四者联合对社区获得性重症肺炎死亡具有更高的预测价值。

关键词：社区获得性重症肺炎危险因素预测价值死亡

Analysis on vibration characteristics of large-size rectangular piezoelectric composite plate based on quasi-periodic phononic crystal structure

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Chinese Physics b 2022年第5期31卷 438-447页

作者： Li-Qing Hu sha Wang Shu-Yu Lin shaanxi Key Laboratory of Ultrasonics Institute of Applied AcousticsShaanxi Normal UniversityXi’an 710119China

based on the theory of composite materials and phononic crystals(PCs),a large-size rectangular piezoelectric composite plate with the quasi-periodic PC structure composed of PZT-4 and epoxy is proposed in this *** PC structure can suppress the transverse vibration of the piezoelectric composite plate so that the thickness mode is purer and the thickness vibration amplitude is more ***,the vibration of the model is analyzed theoretically,the electromechanical equivalent circuit diagram of three-dimensional coupled vibration is established,and the resonance frequency equation is *** effects of the length,width,and thickness of the piezoelectric composite plate at the resonant frequency are obtained by the analytical method and the finite element method,the effective electromechanical coupling coefficient is also *** results show that the resonant frequency can be changed regularly and the electromechanical conversion can be improved by adjusting the size of the rectangular piezoelectric *** effect of the volume fraction of the scatterer on the resonant frequency in the thickness direction is studied by the finite element *** band gap in X and Y directions of large-size rectangular piezoelectric plate with quasi-periodic PC structures are *** results show that the theoretical results are in good agreement with the simulation *** the resonance frequency is in the band gap,the decoupling phenomenon occurs,and then the vibration mode in the thickness direction is purer.

关键词： composite materials rectangular piezoelectric plate coupled vibration band gap

Improving oil recovery in the CO2 flooding process by utilizing nonpolar chemical modifiers

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Chinese Journal of Chemical Engineering 2016年第5期24卷 646-650页

作者： Yong Yang Xiangliang Li Ping Guo Yayun Zhuo Yong sha Research Institute of Exploration and Development Shengli Oilfield CompanySINOPEC Dongying 257000China College of Chemistry and Chemical Engineering Xiamen University Xiamen 361000China

by means of experiments of C02 miscibility with crude oil, four nonpolar chemicals were evaluated in order to enhance the miscibility of C02 with crude oil. Through pre-slug injection and joint injection of toluene in CO2, crude oil displacement experiments in the slim-tube were conducted to investigate effects of the toluene- enhanced C02 flooding under simulated subterranean reservoir conditions. Experimental results showed that toluene can enhance extraction of oil into C02 and dissolution of C02 into oil with the increment of 251% and 64% respectively. Addition of toluene can obviously improve the oil recovery in either pre-slug injection or joint injection, and the crude oil recovery increased with the increase of the toluene concentration. The oil recov- ery can increase by 22.5% in pre-slug injection with the high toluene concentration. Pre-slug injection was recom- mended because it can consume less toluene than joint injection. This work could be useful to development and application of the CO） flooding in the oil recoverv as well as CO2 emission reduction.

关键词： Carbon dioxide Petroleum Vapor liquid equilibria Enhanced oil recovery C02 flooding C02 emission reduction

Defective g-C_(3)N_(4)supported Ru_(3)single-cluster catalyst for ammonia synthesis through parallel reaction pathways

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Nano Research 2023年第2期16卷 3580-3587页

作者： Yining Zhang sha Li Chao Sun Xiaorou Cao Xi Wang Jiannian Yao Institute of Molecular Plus Tianjin UniversityTianjin 300072China Chemistry and Chemical Engineering Guangdong Laboratory Shantou 515031China Department of Physics School of Physical Science and EngineeringBeijing Jiaotong UniversityBeijing 100044China Key Laboratory of Photochemistry Beijing National Laboratory for Molecular SciencesInstitute of ChemistryChinese Academy of ScienceBeijing 100190China

Designing catalyst to achieve ammonia synthesis at mild conditions is a meaningful challenge in catalysis *** g-C_(3)N_(4)nanosheet supported single-cluster ruthenium and iron catalysts were investigated for their ammonia synthesis *** on density functional theory(DFT)calculations and microkinetic simulations,Ru_(3)single-cluster anchored on defective g-C3N4 nanosheet(Ru_(3)/Nv-g-C_(3)N_(4))has a turnover frequency(TOF)5.8 times higher than the Ru(0001)step surface at industrial reaction conditions of 673 K and 100 bar for ammonia *** other words,similar TOFs could be achieved on Ru_(3)/Nv-g-C_(3)N_(4)at much milder conditions(623 K,30 bar)than on Ru(0001)(673 K,100 bar).Our computations reveal the reaction proceeds parallelly on Ru_(3)/Nv-g-C_(3)N_(4)through both dissociative and alternative associative mechanisms at typical reaction conditions(600–700 K,10–100 bar);N–N bond cleavage of*N2 and*NNH from the two respective pathways controls the reaction *** increasing temperatures or decreasing pressures,the dissociative mechanism gradually prevails and associative mechanism *** comparison,Fe_(3)/Nv-g-C_(3)N_(4)catalyst shows a much lower catalytic activity than Ru3/Nv-g-C_(3)N_(4)by two orders of magnitude and the reaction occurs solely through the dissociative *** finding provides a prospective candidate and deepens the mechanistic understanding for ammonia synthesis catalyzed by single-cluster catalysts(SCCs).

关键词： Ru_(3)cluster ammonia synthesis parallel reaction pathways density functional theory microkinetic simulations

Flow softening and dynamic recrystallization behavior of a Mg-Gd-Y-Nd-Zr alloy under elevated temperature compressions

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Journal of Magnesium and Alloys 2023年第8期11卷 2891-2900页

作者： Yiping WU Yuzhen JIA sha Zhang Yu Liu Hanqing Xiong Gang Chen Department of Mechanical and Electrical Engineering Changsha UniversityChangsha 410003China bichamp Cutting Technology(Hunan)Co. LtdChangsha 410200China College of Material Science and Engineering Hunan UniversityChangsha Hunan 410082China

Flow softening behavior of a homogenized Mg-7Gd-4Y-1Nd-0.5Zr alloy under compression to a final strain of∼1.8 at elevated temperatures of 450∼550℃ and a constant strain rate of 2s^(−1) has been investigated by optical microscopy,scanning electron microscopy,electron back-scattered diffraction and transmission electron *** results show that true stress first rises to the peak point and then drops to the bottom value and increases again with further increasing strain at each *** dynamic recrystallization(DRX)and continuous DRX contribute to the formation of new fine grains at temperatures 450∼475℃ when the restoration is caused by both DRX and texture change due to extension twinning,resulting in the larger softening degrees compared with the softening effects owing to continuous DRX and discontinuous DRX at 500∼550℃ when twinning activation is suppressed.500℃ is the transition temperature denoting a significant decline in the contribution of twinning and TDRX to the strain with increasing *** cuboid-shape phase exists in both homogenized and compressed samples,while the compositions are varied.

关键词： Mg-Gd-Y alloy Elevated temperature compression Flow softening Dynamic recrystallization

Functional signatures: new definition and constructions

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Science China(Information Sciences) 2021年第12期64卷 189-201页

作者： Qingwen GUO Qiong HUANG sha MA Meiyan XIAO Guomin YANG Willy SUSILO College of Mathematics and Informatics South China Agricultural University Guangzhou Key Laboratory of Intelligent Agriculture South China Agricultural University School of Computing and Information Technology University of Wollongong

Functional signatures(FS) enable a master authority to delegate its signing privilege to an assistant. Concretely, the master authority uses its secret key skFto issue a signing key skffor a designated function f ∈ FFSand sends both f and skfto the assistant E, which is then able to compute a signature σf with respect to pkFfor a message y in the range of f. In this paper, we modify the syntax of FS slightly to support the application scenario where a certificate of authorization is necessary. Compared with the original FS, our definition requires that FFSis an injective function family and for any f0, f1 ∈ FFS there does not exist an intersection between range(f0) and range(f1). Accordingly, we redefine the security of FS and introduce two additional security notions, called unlinkability and accountability. Signatures σfin our definition do not expose the intention of the master authority. We propose two constructions of FS. The first one is a generic construction based on signatures with perfectly re-randomizable keys, non-interactive zero-knowledge proof(NIZK) and traditional digital signatures, and the other is based on RSA(Rivestshamir-Adleman) signatures with full domain hash and NIZK. We prove that both schemes are secure under the given security models.

关键词： cloud computation security digital signature functional signature non-interactive zero-knowledge proof e-commerce