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When thermoelectric materials come across with magnetism

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Rare Metals 2021年第4期40卷 752-766页

作者： chen-chen zhao Chong Xiao Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China Institute of Energy Hefei Comprehensive National Science CenterHefei 230031China

Nowadays,thermoelectric materials have attracted a lot of attention as they can directly convert heat into electricity and vice ***,while strenuous efforts have been made,those conventional strategies are still inevitably going to meet their performance optimization *** this reason,brand new strategies are badly needed to achieve further ***,the roles played by magnetism in recent advances of thermoelectric optimization are ***,magnetic thermoelectric materials can just be treated like other normal materials because the use of universal optimization strategies can still get good ***,it is not a situation which is all or nothing and the tactics of using magnetism for thermoelectric optimization can coexist with other ***,through magnetic doping,we can introduce and adjust magnetism in materials for further *** provides more possibilities in thermoelectric optimization as it can directly influence the spin states in ***,in the form of magnetic secondphase nanoclusters,magnetism can be introduced to thermoelectric materials to conquer the dilemma that the solid solubility of many magnetic ions in thermoelectric materials is too low to have any significant effect on thermoelectric ***,when exposed to an external magnetic field,topological materials can rely on its unique band structures to optimize.

关键词： Thermoelectricity Magnetic thermoelectric materials Magnetism Magnetic doping Magnetic second phase

Motion Characteristics Analysis of a Novel Spherical Two-degree-of-freedom Parallel Mechanism

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Chinese Journal of Mechanical Engineering 2022年第2期35卷 91-99页

作者： Ziming chen Xuechan chen Min Gao chen zhao Kun zhao Yanwen Li School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004HebeiChina Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao 066004HebeiChina

Current research on spherical parallel mechanisms(SPMs)mainly focus on surgical robots,exoskeleton robots,entertainment equipment,and other ***,compared with the SPM,the structure types and research contents of the SPM are not abundant *** this paper,a novel two-degree-of-freedom(2DOF)SPM with symmetrical structure is proposed and ***,the models of forward kinematics and inverse kinematics are established based on D-H parameters,and the Jacobian matrix of the mechanism is obtained and ***,the workspace of the mechanism is obtained according to inverse kinematics and link interference ***,rotational characteristics analysis shows that the end effector can achieve continuous rotation about an axis located in the mid-plane and passing through the rotation center of the ***,the rotational characteristics of the mechanism are proved,and motion planning is carried out.A numerical example is given to verify the kinematics analysis and motion ***,some variant mechanisms can be *** work lays the foundation for the motion control and practical application of this 2DOF SPM.

关键词： Spherical parallel mechanism 2DOF Workspace Equivalent rotation

Spectral-spatial classification for hyperspectral imagery: a novel combination method based on affinity scoring

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Science China(Information Sciences) 2016年第10期59卷 181-193页

作者： zhao chen Bin WANG State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University Key Laboratory for Information Science of Electromagnetic Waves (Ministry of Education) Fudan University Research Center of Smart Networks and Systems School of Information Science and Technology Fudan University

Recently, a general framework for spectral-spatial classification has caught the attention of the hyperspectral imagery(HSI) society. It consists of three parts: classification, segmentation and combination of the former results to make a refined labeled map. Seeing the potentials of the last part, we derive a novel combination rule based on affinity scoring(CRAS). The core of the system is affinity score(AS), which is derived from fuzzy logic. Every AS measures the degree, i.e., the affinity, by which a pixel belongs to a class. The score is essentially decided by three factors: local spatial consistency, spectral similarity, and prior knowledge. The method is compatible with basic classification and segmentation tools, thus saving the trouble of designing complex techniques for the other parts in the framework. Experimental results show that CRAS excels several basic techniques as well as various state-of-the-art methods in the area of spectral-spatial classification.

关键词： hyperspectral imagery spectral-spatial classification affinity score local spatial consistency fuzzy superpixel

Composite quantile regression estimation for P-GARCH processes

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Science China Mathematics 2016年第5期59卷 977-998页

作者： zhao Biao chen zhao TAO GuiPing chen Min Department of Statistics and Finance University of Science and Technology of China Department of Statistics Pennsylvnia State University School of Statistics Capital University of Economics and Business Academy of Mathematics and Systems Science Chinese Academy of Sciences

We consider the periodic generalized autoregressive conditional heteroskedasticity(P-GARCH) process and propose a robust estimator by composite quantile regression. We study some useful properties about the P-GARCH model. Under some mild conditions, we establish the asymptotic results of proposed *** Monte Carlo simulation is presented to assess the performance of proposed estimator. Numerical study results show that our proposed estimation outperforms other existing methods for heavy tailed *** proposed methodology is also illustrated by Va R on stock price data.

关键词： composite quantile regression periodic GARCH process strictly periodic stationarity strong consistency asymptotic normality

Trusted Attestation Architecture on an Infrastructure-as-a-Service

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Tsinghua Science and Technology 2017年第5期22卷 469-477页

作者： Xin Jin Xingshu chen cheng zhao Dandan zhao the College of Computer Science Sichuan University

Trusted attestation is the main obstruction preventing large-scale promotion of cloud computing. How to extend a trusted relationship from a single physical node to an Infrastructure-as-a-Service （laaS） platform is a problem that must be solved. The laaS platform provides the Virtual Machine （VM）, and the Trusted VM, equipped with a virtual Trusted Platform Module （vTPM）, is the foundation of the trusted laaS platform. We propose a multi-dimensional trusted attestation architecture that can collect and verify trusted attestation information from the computing nodes, and manage the information centrally on a cloud management platform. The architecture verifies the laaS＇s trusted attestation by apprising the VM, Hypervisor, and host Operating System＇s （OS） trusted status. The theory and the technology roadmap were introduced, and the key technologies were analyzed. The key technologies include dynamic measurement of the Hypervisor at the process level, the protection of vTPM instances, the reinforcement of Hypervisor security, and the verification of the laaS trusted attestation. A prototype was deployed to verify the feasibility of the system. The advantages of the prototype system were compared with the Open CIT （Intel Cloud attestation solution）. A performance analysis experiment was performed on computing nodes and the results show that the performance loss is within an acceptable range.

关键词： dynamic measurement trusted cloud vTPM trusted attestation

Almost perfect sequences based on cyclic difference sets

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Journal of Systems Engineering and Electronics 2007年第1期18卷 155-159页

作者： chen Gang zhao Zhengyu Ionosphere Lab Wuhan Univ. Wuhan 430070 E R. China

The perfect sequences are so ideal that all out-of-phase autocorrelation coefficients are zero, and if the sequences are used as the coding modulating signal for the phase-modulated radar, there will be no interference of side lobes theoretically. However, it has been proved that there are no binary perfect sequences of period 4 〈 n ≤ 12100. Hence, the almost perfect sequences with all out-of-phase autocorrelation coefficients as zero except one are of great practice in engineering. Currently, the cyclic difference set is one of most effective tools to analyze the binary sequences with perfect periodic autocorrelation function. In this article, two characteristic formulas corresponding to the autocorrelation and symmetric structure of almost perfect sequences are calculated respectively. All almost perfect sequences with period n, which is a multiple of 4, can be figured out by the two formulas. Several almost perfect sequences with different periods have been hunted by the program based on the two formulas and then applied to the simulation program and practical application for ionospheric sounding.

关键词： Perfect sequence Almost perfect sequence Cyclic difference sets Autocorrelation coefficients Side lobes Ionospheric sounding

The genomic stability of induced pluripotent stem cells

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Protein & Cell 2012年第4期3卷 271-277页

作者： zhao chen Tongbiao zhao Yang Xu Division of Biological Sciences University of CaliforniaSan DiegoLa JollaCA 92093-0322USA

With their capability to undergo unlimited self-renewal and to differentiate into all cell types in the body,in-duced pluripotent stem cells(iPSCs),reprogrammed from somatic cells of human patients with defined fac-tors,hold promise for regenerative medicine because they can provide a renewable source of autologous cells for cell therapy without the concern for immune *** addition,iPSCs provide a unique opportu-nity to model human diseases with complex genetic traits,and a panel of human diseases have been suc-cessfully modeled in vitro by patient-specific *** these progresses,recent studies have raised the concern for genetic and epigenetic abnormalities of iPSCs that could contribute to the immunogenicity of some cells differentiated from *** oncogenic potential of iPSCs is further underscored by the find-ings that the critical tumor suppressor p53,known as the guardian of the genome,suppresses induced ***,the clinic application of iPSCs will require the optimization of the reprogramming technology to minimize the genetic and epigenetic ab-normalities associated with induced pluripotency.

关键词： induced pluripotent stem cells reprogram-ming genetic and epigenetic abnormalities

Optimum Seeking of Redundant Actuators for M-RCM 3-UPU Parallel Mechanism

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Chinese Journal of Mechanical Engineering 2021年第6期34卷 373-384页

作者： chen zhao Jingke Song Xuechan chen Ziming chen Huafeng Ding School of Mechanical Engineering Yanshan UniversityQinhuangdao066004China Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao066004China School of Mechanical Engineering and Electronic Information China University of Geosciences(Wuhan)Wuhan430074China

The singularity problem brings troubles to the design and application for the parallel ***,redun-dant actuation is one of the useful methods to solve this singularity ***,faced to the numerous joints in a parallel mechanism,how to make a quantitative criterion of seeking the most efficient joints added actuators for letting the mechanism passes through singularity is a necessarily open *** paper focuses on a 2R1T 3-UPU(U for universal joint and P for prismatic joint)parallel mechanism(PM)with two rotational and one translational(2R1T)degrees of freedom(DOFs)and the ability of multiple remote centers of motion(M-RCM).The singularity analysis based on the indexes of motion/force transmissibility and constraint shows that this PM has transmission singular-ity,constraint singularity,mixed singularity and limb *** solve these singular problems,the quantifiable redundancy transmission index(RTI)and the redundancy constraint index(RCI)are proposed for optimum seeking of redundant actuators for this *** the appropriate redundant actuators are selected and the working scheme for redundant actuators near the corresponding singular configuration are given to help the PM passes through the *** research proposes a quantitative criterion to optimum seeking of redundant actuators for the parallel mechanism to solve its singularity.

关键词： Parallel mechanism 2R1T RCM Singularity Redundant actuation

A Hybrid Compression Method for Compound Power Quality Disturbance Signals in Active Distribution Networks

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Journal of Modern Power Systems and Clean Energy 2023年第6期11卷 1902-1911页

作者： Xiangui Xiao Kaicheng Li chen zhao State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China College of Mechanical and Electrical Engineering Fujian Agriculture and Forest UniversityFuzhou 350002China

In the compression of massive compound power quality disturbance(PQD) signals in active distribution networks, the compression ratio(CR) and reconstruction error(RE) act as a pair of contradictory indicators, and traditional compression algorithms have difficulties in simultaneously satisfying a high CR and low RE. To improve the CR and reduce the RE, a hybrid compression method that combines a strong tracking Kalman filter(STKF), sparse decomposition, Huffman coding, and run-length coding is proposed in this study. This study first uses a sparse decomposition algorithm based on a joint dictionary to separate the transient component(TC) and the steady-state component(SSC) in the PQD. The TC is then compressed by wavelet analysis and by Huffman and runlength coding algorithms. For the SSC, values that are greater than the threshold are reserved, and the compression is finally completed. In addition, the threshold of the wavelet depends on the fading factor of the STKF to obtain a high CR. Experimental results of real-life signals measured by fault recorders in a dynamic simulation laboratory show that the CR of the proposed method reaches as high as 50 and the RE is approximately 1.6%, which are better than those of competing methods. These results demonstrate the immunity of the proposed method to the interference of Gaussian noise and sampling frequency.

关键词： Signal compression power quality disturbance Huffman coding run-length coding wavelet analysis sparse decomposition