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IET International Radar Conference 2013

作者： Liu, Jin Zhao, Feng Zhang, Yanqing Ai, Xiaofeng Yang, Jianhua State Key Lab. of Complex Electromagnetic Environ. Effects on Electron./Info. Syst. Changsha 410073 China College of Electronic Science and Engineering National University of Defense Technology Changsha 410073 China Unit 61135 of PLA Beijing China

ISBN: (纸本)9781849196031

Non-ideal scattering centers exist commonly on radar targets. The scattering characteristics of them induce additional modulation or components to the micro-Doppler. Two typical kinds of non-ideal scattering centers are analyzed and micro- Doppler model of the scattering centers on the ring structure of precession targets are introduced as a detailed example. The experimental results demonstrate the model.

关键词： Radiation

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Structure and Magnetic Properties of Perpendicularly Anisotropic Hcp-Co–Sio2 Nanocrystalline Films with In-Plane Isotropy

SSRN

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SSRN 2023年

作者： Che, Shenglei Li, Wangchang Xu, Ziyang Zhang, Sen Chen, Rui Zhou, Yi Dang, Yongdi Li, Wanjia Ying, Yao Yu, Jing Zheng, Jingwu Qiao, Liang Li, Juan Ma, Yungui College of Materials Science and Engineering Zhejiang University of Technology Hangzhou310014 China Research Center of Magnetic and Electronic Materials Zhejiang University of Technology Hangzhou310014 China State Key Lab of Modern Optical Instrumentation Centre for Optical and Electromagnetic Research College of Optical Science and Engineering International Research Center for Advanced Photonics Zhejiang University Haining Campus China

Hcp-Co-SiO2 nanocrystalline films with different thicknesses were fabricated by homogeneously distributing nanocrystalline hcp-Co particles with a size of 5~10 nm in the amorphous SiO2 matrix. The hcp-Co nanoparticles grow perpendicularly to the film and exhibit perpendicular magnetic anisotropy and in-plane isotropy. The tilting angle (θ) of the magnetic moments to the vertical direction decreases to 7.5° as the film thickness increases to 1097 nm. The Co fraction reaches 0.64, leading to a low coercivity of only 30-35 Oe for magnetic exchange coupling of closely packed Co nanocrystalline particles. Perpendicular anisotropy and competition between the poles lead to a ripple-stripe domain with a width two orders of magnitude larger than the nanoparticle size. The natural resonance frequency of this film is about 1.9 GHz, corresponding to the low-anisotropy field, Hk. However, it increases to 18 GHz as the in-plane magnetic bias field reaches 2400 Oe, exhibiting in-plane isotropy. This perpendicularly anisotropic hcp-Co-SiO2 nanocrystalline film provides an opportunity for the potential application of isotropic films in on-chip micro-inductance and other electromagnetic devices. © 2023, The Authors. All rights reserved.

关键词： Silica

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Near-field radiative heat transfer between hybrid polaritonic structures

arXiv

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arXiv 2022年

作者： Iqbal, Naeem Zhang, Sen Wang, Shuai Fang, Zezheng Hu, Yaoyuan Dang, Yongdi Zhang, Minjie Jin, Yi Xu, Jianbin Ju, Binfeng Ma, Yungui State Key Lab of Modern Optical Instrumentation Centre for Optical and Electromagnetic Research College of Optical Science and Engineering International Research Center for Advanced Photonics Zhejiang University China The State Key Lab of Fluid Power Transmission and Control School of Mechanical Engineering Zhejiang University Hangzhou310027 China Zhejiang Province Key Laboratory of Quantum Technology and Device Department of Physics Zhejiang University Hangzhou China Department of Electrical and Electronic Engineering The University of Hong Kong Pokfulam Road Hong Kong

Near-field radiative heat transfer between close objects may exceed the far-field blackbody radiation in orders of magnitude when exploiting polaritonic materials. Great efforts have been made to experimentally measure this fundamental stochastic effect but mostly based on simple materials. In this work, we foster an all-optical method to characterize the heat transfer between less explored plasmon-phonon hybrid polaritonic systems made of graphene-SiC heterostructures. A large heat flux about 26 times of the blackbody radiation limit is obtained over a 150-nm vacuum gap, attributed to the couplings of three different surface modes (plasmon, phonon polaritons and frustrated mode). The interaction of polaritonic modes in the hybrid system is also explored to build a switchable thermophotonic device with nearly unity heat flux tunability. This work paves the way for understanding mode-mediated near-field heat transfer and provides a platform for building thermophotonic or thermo-optoelectronic blocks for various applications. © 2022, CC BY.

关键词： Radiative transfer

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Observation of topologically enabled complete polarization conversion

arXiv

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arXiv 2021年

作者： Chen, Fujia Gao, Zhen Zhang, Li Chen, Qiaolu Yan, Qinghui Xi, Rui Jing, Liqiao Li, Erping Yin, Wenyan Chen, Hongsheng Yang, Yihao Interdisciplinary Center for Quantum Information State Key Lab. of Modern Optical Instrumentation College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China ZJU-Hangzhou Global Science and Technology Innovation Center Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang ZJU-UIUC Institute Zhejiang University Hangzhou310027 China Department of Electrical and Electronic Engineering Southern University of Science and Technology Shenzhen518055 China

Exploiting topological ideas has been a major theme in modern photonics, which provides unprecedented opportunities to design photonic devices with robustness against defects and flaws. While most previous works in topological photonics have focused on band theory, recent theoretical advances extend the topological concepts to the analysis of scattering matrices and suggest a topological route to complete polarization conversion (CPC), a unique photonic phenomenon without an electronic counterpart. Here, we report on the experimental observation of the topological effect in reflection matrices of a photonic crystal slab. enabling CPC between two linear polarizations over a wide range of frequencies. Using angle-resolved reflection measurements, we observe CPC occurring at vortex singularities of reflection coefficients in momentum space, verifying the topological nature of CPC. In addition, the topological effect also guarantees the spin-preserved reflection of a circularly polarized wave. Remarkably, we experimentally establish a connection between two seemingly unrelated topological phenomena-CPC and bound states in the continuum (BICs): BICs lie on the critical coupling curves that define the condition for CPC. Our work paves the way to exploring the topological properties in scattering matrices for controlling light polarization and spin and creating robust photonic devices. © 2021, CC BY.

关键词： Photonic devices

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An Improved Interleaved Buck/Boost Integrated CLLLC Three-Port DC-DC Converter for Wide Input Range

An Improved Interleaved Buck/Boost Integrated CLLLC Three-Po...

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Electrical engineering (CIYCEE), IEEE China International Youth Conference on

作者： Xu Yan Caifeng Liu Shuang Liu Xiang Guo Xudong Zou State Key Lab. of Advanced Electromagnetic Eng. and Tech Huazhong Uni. of Sci. and Tech Wuhan China China-EU Institute for Clean and Renewable Energy Huazhong Uni. of Sci. and Tech Wuhan China School of Electrical and Electronic Engineering Huazhong Uni. of Sci. and Tech Wuhan China

ISBN: (纸本)9781665400657

Power electronic converters are widely used in renewable energy generation scenarios. However, the power fluctuations of renewable energy will make DC microgrid bus voltage perturbed. As a result, the input voltage for the converter is not constant. This paper proposes an improved three-port converter with the advantages of wide input voltage and high integration levels. The interleaved Buck/Boost integrated CLLLC (IBBI-CLLLC) converter can balance power difference by the energy storage device, which expands the operation range. Then, an improved PWM+PFM modulation method is proposed in this paper. By satisfying a specific relationship between duty cycle and switching frequency, the CLLLC converter has no power return phenomenon when the secondary switches are in the synchronous rectification state, which improves the efficiency of the converter. Moreover, the converter has a wide range of DC gain and can realize zero voltage switching (ZVS) in a wide input voltage range. Finally, the correctness of the theoretical analysis is verified by simulation.

关键词： Electrical engineering Renewable energy sources Fluctuations Switching frequency Soft switching Modulation Microgrids

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Active Landmark Configuration for Accurate Nano-Positioning

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IFAC Proceedings Volumes 2013年第5期46卷 594-599页

作者： Shuai Yuan Lianqing Liu Zhidong Wang Ning Xi Yuechao Wang Zaili Dong State Key Lab. Robot. SIA. Chinese Academy of Sciences Shenyang 110016 China Shenyang Jianzhu University Shenyang110168 Chinae Graduate University of the Chinese Academy of Sciences Beijing 100039 China Dept. of Advanced Robotics Chiba Institute of Technology Chiba 275-0016 Japan Dept. of Electrical and Computer Engineering Michigan State University US

The spatial uncertainties of atom force microscopy (AFM) tip position hinder the AFM based nano-manipulation. Although the landmark based tip localization can be applied to improve the tip position accuracy in the task space, the PZT nonlinearity and system drift are still a challenge to compensation performance when the tip is positioned far from the landmark. Therefore this paper proposes an active landmark configuration. This method first estimates the nearby area called as the landmark domain around the target position, and then actively manipulates the landmark into the landmark domain by using virtual hand to improve the positioning accuracy. Simulation and experiment illustrate the validity of the proposed method.

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Cooperative and Active Sensing in Mobile Sensor Networks for Scalar Field Mapping

Cooperative and Active Sensing in Mobile Sensor Networks for...

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IEEE International Conference on Automation Science and engineering

作者： Hung Manh La Weihua Sheng Jiming Chen Center for Advanced Infrastructure and Transportation (CAIT) Rutgers University Piscataway NJ 08854 USA School of Electrical and Computer Engineering Oklahoma State University Stillwater OK 74078 USA State Key Lab. of Industrial Control Technology Department of Control Zhejiang University Hangzhou P.R.China 310027

ISBN: (纸本)9781479915132

Scalar field mapping has many applications including environmental monitoring, search and rescue, etc. In such applications there is a need to achieve a certain level of confidence regarding the estimates at each location. In this paper, a cooperative and active sensing framework is developed to enable scalar field mapping using multiple mobile sensor nodes. The cooperative and active controller is designed via the real-time feedback of the sensing performance to steer the mobile sensors to new locations in order to improve the sensing quality. During the movement of the mobile sensors, the measurements from each sensor node and its neighbors are taken and fused with the corresponding confidences using distributed consensus filters. As a result an online map of the scalar field is built with a certain level of confidence of the estimates. We conducted computer simulations to validate and evaluate our proposed algorithms

关键词： Active sensing Sensor fusion Sensor networks

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Triply degenerate topological phase and stretchable Fermi arc surface states in gyromagnetic metamaterials

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Physical Review B 2023年第3期108卷 035422-035422页

作者： Mingzhu Li Ning Han Lu Qi Liang Peng School of Information and Electrical Engineering Hangzhou City University Hangzhou 310015 China Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation College of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China ZJU-Hangzhou Global Science and Technology Innovation Center Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang ZJU-UIUC Institute Zhejiang University Hangzhou 310027 China School of Physical Science and Technology Yangzhou University Yangzhou 225002 China

Triple-fold band degeneracy (TBD) is an intriguing phase of topological semimetals which appears as the intermediate state between the four-folded degenerated Dirac points and the two-folded Weyl points. The resemblance of TBD in the photonics is interesting, because it indicates nonzero Berry curvature in momentum space and nontrivial topological property in real space. Recently, it was reported that TBD could be realized in the classical wave systems including phononic and photonic crystals. Unfortunately, those periodic structures can hardly provide a systematic strategy nor a compact layout in practical implementations. Hence, the resemblance of TBD is still a big challenge in topological photonics. In this work, we demonstrate that homogeneous gyromagnetic metamaterials (GMs) can be a good framework to stimulate the peculiar TBD. We discuss the emulation of triple degeneracy in dispersive GMs by carefully tuning the constitutive parameters. The introduction of nonlocality in the constitutive parameter of GMs provides the freedom of topology control of the GMs. Further, Fermi arc surface states are discussed and shown to be reflectionless against sharp corners. Remarkably, Fermi arc surface states, which occur at the boundary between the vacuum and the GMs, can be stretchable by tailoring the gap width of the GM's band structure. Our work provides a practical and flexible route to resemble TBD, which is of fundamental importance in designing reflectionless and unidirectional photonic topological devices.

关键词： Electron-cyclotron plasma waves Magneto-optics Surface states Topological effects in photonic systems Topological materials

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Synergistic Effect of Ag and Cu on Improving in Vitro Biological Properties of K2ti6o13 Nanowires for Potential Biomedical Applications

SSRN

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SSRN 2022年

作者： Lei, Shichang Qi, Yumin Zhao, Lichen Shen, Yutian An, Hailong Qu, Chang Wang, Xin Wang, Gaojiong Cui, Chunxiang Key Lab. for New Type of Functional Materials in Hebei Province School of Materials Science and Engineering Hebei University of Technology Tianjin300401 China Key Laboratory of Advanced Materials Ministry of Education Tsinghua University Beijing100084 China Key Laboratory of Molecular Biophysics Hebei Province Institute of Biophysics School of Health Sciences and Biomedical Engineering Hebei University of Technology Tianjin300401 China State Key Laboratory of Reliability and Intelligence of Electrical Equipment School of Electrical Engineering Hebei University of Technology Tianjin300130 China

The development of novel nanomaterials with synergistic biological effects has attracted extensive interest of the researchers. In the study, KTO with the doping amount of 0.5 mol% Ag and 0.5 mol% Cu (0.5 Ag-0.5 Cu-KTO) nanomaterial was successfully synthesized using two-step method of sol-gel and hydrothermal. The crystal structure of 0.5 Ag-0.5 Cu-KTO was still monoclinic KTO, Ag and Cu ions replacing partial Ti ions of KTO lattice. High specific surface area of 0.5 Ag-0.5 Cu-KTO (337.6 m 2 /g) provides more surface active sites for adsorption and Cu-Ag doping. More negative surface zeta potential (-32.83 mV in phosphate buffer solution (PBS) and -21.45 mV in physiological saline solution (PSS), respectively) would be beneficial to prevent the aggregation of the nanowires in physiological environment. Under the same doping amount, compared to single Cu doped KTO with the doping amount of 1.0 mol%, 0.5 Ag-0.5 Cu-KTO exhibited better antibacterial performance against gram-negative and gram-positive bacteria at only 100 μg/mL dose concentration, near to 1.0 mol% Ag doped KTO. And 0.5 Ag-0.5 Cu-KTO showed more excellent biocompatibility than 1.0 Ag-KTO, which was attribute to the introduction of Cu ions effectively decreasing the hemolytic and cytotoxic risks from Ag ions. As expected, the synthesized 0.5 Ag-0.5 Cu-KTO nanowires demonstrated excellent structural stability, high antibacterial activity, good hemocompatibility and cytocompatibility owing to the synergistic biological effects of Cu and Ag ions. 0.5 Ag-0.5 Cu-KTO nanowires will be a promising antimicrobial candidate for biomedical applications. © 2022, The Authors. All rights reserved.

关键词： Nanowires

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Sintering behavior and microwave dielectric properties of Ba1+x(Mg1/3Nb2/3)O3 ceramics

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of technology 2008年第8期30卷 27-29页

作者： Tian, Zhong-Qing Zhao, Wei-Lin Yu, Hong-Tao Chen, Wei-Ling School of Materials Science and Engineering Chongqing Institute of Technology Chongqing 400050 China State Key Lab. of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

Sintering behavior, microstructure and microwave dielectric properties of Ba1+x(Mg1/3Nb2/3)O3 (-0.01 [less-than or equal to] x [less-than or equal to] 0.01) were investigated. An improvement of the degree of 1:2 ordering and sinterability was found in Ba-deficient Ba(Mg1/3 Nb2/3)O3 because there existed Ba vacancies. Excessive Ba inhibits the sintering and the degree of 1:2 ordering. It was proposed that excessive Ba exist in grain boundary and inhibit the movement of grain boundary. Therefore, the sintering was restrained. Ba-deficiency had little effect on dielectric constant of Ba(Mg1/3Nb2/3)O3 ceramics. With Ba-deficiency increasing, Qf value decreased drastically.

关键词： Ba(Mg1/3Nb2/3)O3 Microwave dielectric ceramic Ordering Sinterability

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