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Field-Driven Quantum Criticality in the Spinel Magnet ZnCr2Se4

Physical Review Letters 2018年第14期120卷 147204-147204页

作者： C. C. Gu Z. Y. Zhao X. L. Chen M. Lee E. S. Choi Y. Y. Han L. S. Ling L. Pi Y. H. Zhang G. Chen Z. R. Yang H. D. Zhou X. F. Sun Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field Laboratory Chinese Academy of Sciences Hefei Anhui 230031 People’s Republic of China Department of Physics Hefei National Laboratory for Physical Sciences at Microscale and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS) University of Science and Technology of China Hefei Anhui 230026 People’s Republic of China Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 People’s Republic of China National High Magnetic Field Laboratory Florida State University Tallahassee Florida 32306-4005 USA Department of Physics Florida State University Tallahassee Florida 32306-3016 USA Collaborative Innovation Center of Advanced Microstructures Nanjing Jiangsu 210093 People’s Republic of China State Key Laboratory of Surface Physics and Department of Physics Center for Field Theory and Particle Physics Fudan University Shanghai 200433 China Institute of Physical Science and Information Technology Anhui University Hefei Anhui 230601 People’s Republic of China Key laboratory of Artificial Structures and Quantum Control (Ministry of Education) School of Physics and Astronomy Shanghai JiaoTong University Shanghai 200240 China Department of Physics and Astronomy University of Tennessee Knoxville Tennessee 37996-1200 USA

We report detailed dc and ac magnetic susceptibilities, specific heat, and thermal conductivity measurements on the frustrated magnet ZnCr2Se4. At low temperatures, with an increasing magnetic field, this spinel material goes through a series of spin state transitions from the helix spin state to the spiral spin state and then to the fully polarized state. Our results indicate a direct quantum phase transition from the spiral spin state to the fully polarized state. As the system approaches the quantum criticality, we find strong quantum fluctuations of the spins with behaviors such as an unconventional T2-dependent specific heat and temperature-independent mean free path for the thermal transport. We complete the full phase diagram of ZnCr2Se4 under the external magnetic field and propose the possibility of frustrated quantum criticality with extended densities of critical modes to account for the unusual low-energy excitations in the vicinity of the criticality. Our results reveal that ZnCr2Se4 is a rare example of a 3D magnet exhibiting a field-driven quantum criticality with unconventional properties.

关键词： Frustrated magnetism Magnetism

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Experimental of cathode plasma electrodeposition of nickel

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Chemical Engineering Transactions 2017年 62卷 199-204页

作者： Chen, Jinsong Guo, Jian Qiu, Mingbo Jianming, Yang Jiangsu Key Laboratory of Function Control Technology for Advanced Materials Huaihai Institute of Technology Lianyungang222005 China Lianyungang Shenyu Petrochemical Machinery Equipment Co. Ltd. Lianyungang222005 China Nanjing University of Aeronautics and Astronautics Nanjing222005 China

ISBN: (纸本)9788895608600

Experiment was designed to conduct cathode plasma electrodeposition. In the experimental cathode plasma electrodeposition of nickel, ethanol and citric acid at various concentrations along with different electrolytes were adopted to study the effect of electrolyte composition on the deposition rate and surface appearance of a nickel electrodeposition layer. The results revealed that, as the ethanol concentration of an electrolyte increased, the deposition layer of nickel gradually exhibited smoother surfaces as well as uniform, fine structures thereon. In addition, the concentration enrichment of the;in the electrolytes visibly improved the deposition rate of nickel and decreased the particle size of the deposition layer. Besides, when nickel chloride or nickel sulphate were used as the main salts, the deposition rate of nickel was higher, while it was lower when nickel aminosulphonate was used as the main salt. Additionally, the differences in the three types of main salts exerted a slight influence on the surface appearance of nickel electrodeposition layers. Copyright © 2017, AIDIC Servizi S.r.l.

关键词： Electrolytes

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Lattice distortion effects on the frustrated spin-1 triangular-antiferromagnet A3NiNb2O9 (A = Ba, Sr and Ca)

arXiv

引用

arXiv 2018年

作者： Lu, Z. Ge, L. Wang, G. Russina, M. Guenther, G. dela Cruz, C.R. Sinclair, R. Zhou, H.D. Ma, J. Helmholtz-Zentrum Berlin für Materialien und Energie BerlinD-14109 Germany School of Physics Georgia Institute of Technology AtlantaGA30332 United States Key Laboratory of Artificial Structures and Quantum Control School of Physics Astronomy Shanghai Jiao Tong University Shanghai200240 China Neutron Scattering Division Oak Ridge National Laboratory Oak RidgeTN37831 United States Department of Physics and Astronomy University of Tennessee KnoxvilleTN37996 United States Collaborative Innovation Center of Advanced Microstructures Nanjing Jiangsu210093 China

In the geometrically frustrated materials with the low-dimensional and small spin moment, the quantum fluctuation could interfere with the complicated interplay of the spin, electron, lattice and orbital interactions, and host exotic ground states such as nematic spin-state and chiral liquid phase. While the quantum phases of the one-dimensional chain and S - ½ two-dimensional triangular-lattice antiferromagnet (TLAF) had been more thoroughly investigated by both theorists and experimentalists, the work on S = 1 TLAF has been limited. We induced the lattice distortion into the TLAFs, A3NiNb2O9 (A = Ba, Sr, and Ca) with S (Ni2+) = 1, and applied the thermodynamic, magnetic and neutron scattering measurements. Although A3NiNb2O9 kept the non-collinear 120°antiferromagnetic phase as the ground state, the Ni2+-lattice changed from the equilateral triangle (A = Ba) into isosceles triangle (A = Sr and Ca). The inelastic neutron scattering data were simulated by the linear spin-wave theory, and the competition between the single-ion anisotropy and the exchange anisotropy from the distorted lattice was discussed. Copyright © 2018, The Authors. All rights reserved.

关键词： Ground state

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Light-Weight Design of CRH Wind Deflector Panels based on Woven Textile Sandwich Composites

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Acta Mechanica Solida Sinica 2016年第2期29卷 208-220页

作者： Hualin Fan Jianfeng Ouyang Fangfang Sun Peishi Yu Ning Kuang Yang Hu College of Mechanics and Materials Hohai University Nanjing 210098 China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing 210016 China Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment& Technology School of Mechanical Engineering Jiangnan University Wuxi 214122 China Nanjing Fiberglass Research & Design Institute Nanjing 210012 China

The woven textile sandwich composite（WTSC） is a promising lightweight *** bending,two competing core shearing failure modes reduce the strength;deflection induced by the core shearing deformation reduces the flexural *** replace a solid composite laminate,the span of WTSC panel must be greater than a critical value,which was deduced on the condition that the load capacity and flexural rigidity of the WTSC panel are equal to those of the composite *** WTSC panels were tested in bending,so that the failure modes were observed,and the critical spans were *** the alternative design method,the WTSC based wind deflector with reduced weight has been fabricated and mounted on the CRH（China Railway High-speed）.

关键词： sandwich CRH wind deflector light-weight design mechanical testing

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Learning robust and discriminative low-rank representations for face recognition with occlusion

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Pattern Recognition 2017年 66卷 129-143页

作者： Guangwei Gao Jian Yang Xiao-Yuan Jing Fumin Shen Wankou Yang Dong Yue Institute of Advanced Technology Nanjing University of Posts and Telecommunications Nanjing China Jiangsu Engineering Laboratory of Big Data Analysis and Control for active distribution network Nanjing University of Posts and Telecommunications Nanjing China Fujian Provincial Key Laboratory of Information Processing and Intelligent Control (Minjiang University) Fuzhou China School of Computer Science and Engineering Nanjing University of Science and Technology Nanjing China School of Automation Nanjing University of Posts and Telecommunications Nanjing China School of Computer Science and Engineering University of Electronic Science and Technology of China Chengdu China School of Automation Southeast University Nanjing China

For robust face recognition tasks, we particularly focus on the ubiquitous scenarios where both training and testing images are corrupted due to occlusions. Previous low-rank based methods stacked each error image into a vector and then used L 1 or L 2 norm to measure the error matrix. However, in the stacking step, the structure information of the error image can be lost. Depart from the previous methods, in this paper, we propose a novel method by exploiting the low-rankness of both the data representation and each occlusion-induced error image simultaneously, by which the global structure of data together with the error images can be well captured. In order to learn more discriminative low-rank representations, we formulate our objective such that the learned representations are optimal for classification with the available supervised information and close to an ideal-code regularization term. With strong structure information preserving and discrimination capabilities, the learned robust and discriminative low-rank representation (RDLRR) works very well on face recognition problems, especially with face images corrupted by continuous occlusions. Together with a simple linear classifier, the proposed approach is shown to outperform several other state-of-the-art face recognition methods on databases with a variety of face variations.

关键词： Face recognition Low-rank matrix recovery Nuclear norm

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Solving dynamic optimization problems based on an improved clustering quantum-behaved particle swarm optimizer

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Journal of Computational and Theoretical Nanoscience 2016年第6期13卷 3540-3547页

作者： Fang, Wei Wang, Mengmei Li, Chaofeng Key Laboratory of Advanced Process Control for Light Industry Department of Computer Science and Technology School of IoT Engineering Jiangnan University Wuxi Jiangsu214122 China

Solving dynamic optimization problems (DOPs) has become a hot research area in recent years. In this paper, an improved Quantum-behaved particle swarm optimizer (QPSO) with hierarchical clustering technique is proposed to solve DOPs in terms of the dynamics and complexity. By studying the trajectory of particles and the effect of local attractor in QPSO, Gaussian distribution is used to sample the local attractor in order to alleviate premature convergence and enhance the global search ability. Two variants of the proposed Gaussian distributed are also studied in this paper. For the hierarchical clustering technique, each particle is regarded as one cluster in the initial stage. With the evolutionary procedure, the clusters merge into new sub-swarms when the distances between them are less than a threshold, which is used for tracking the movement of peaks. The convergence check, overcrowding check, and overlapping check are appointed during the clustering procedure in order to keep swarm diversity. The performance of the improved QPSO with gaussian sampling and clustering technique is evaluated on a set of benchmark functions and compared with some state-of-art algorithms. Experimental results show the efficiency of the proposed approach. Copyright © 2016 American Scientific Publishers. All rights reserved.

关键词： Gaussian distribution

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An energy-efficient bandwidth allocation method for single-chip heterogeneous processor 7

An energy-efficient bandwidth allocation method for single-c...

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7th International Green and Sustainable Computing Conference, IGSC 2016

作者： Zhu, Yatao Zhang, Shuai Ye, Xiaochun Wang, Da Tan, Xu Fan, Dongrui Zhang, Zhimin Li, Hongliang State Key Laboratory of Computer Architecture Institute of Computing Technology Chinese Academy of Sciences Beijing China School of Computer and Control Engineering University of Chinese Academy of Sciences Beijing China National Computer Network Emergency Response Technical Team/Coordination Center of China Beijing China State Key Laboratory of Mathematical Engineering and Advanced Computing Wuxi Jiangsu China

ISBN: (纸本)9781509051175

In recent years, many studies on optimization of energy consumption have focused on heterogeneous processor architectures. Heterogeneous computing model composed of CPU and GPU has developed from co-processing between the chips to CPU and GPU integration on the same die. On the one hand, because GPU can work under low voltage and ultra-low frequency, heterogeneous multi-core processors exhibit better energy efficiency compared to traditional CPU;On the other hand, because GPU usually has little or no shared cache, its memory bandwidth demand will be several times more than that of CPU for the same performance. Considering the constraints of power consumption and memory bandwidth, the contention problems of power and bandwidth among CPU and GPU in heterogeneous processor will inevitably occur. In this paper, energy-efficient bandwidth allocation method for heterogeneous processors allocates bandwidth to CPU and GPU and increases the overall throughput of CPU and GPU. Meanwhile the efficiency of energy consumption of heterogeneous processors is improved. The queuing delay is introduced to build a performance-energy model for heterogeneous processors. According to experience parameters, we analyze how the memory bandwidth allocation of off-chip affects the total throughput and energy efficiency. This paper also explores the change of performance-energy gains with the cache miss ratio of processors and the degree of scarce of available peak bandwidth. Based on the above research, the analytical solution of energy-efficient bandwidth allocation for optimal performance is obtained, and the solution can get more performance-energy gains compared with natural bandwidth allocation. © 2016 IEEE.

关键词： Bandwidth

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Visual tracking via adaptive observation weight

Visual tracking via adaptive observation weight

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International Conference on Machine Learning and Cybernetics (ICMLC)

作者： Xing Liu Ying Chen Chun-Jian Hua Key Laboratory of Advanced Process Control for Light Industry (Ministry of Education) Jiangnan University Wuxi Province China Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology Key Jiangnan University University Wuxi Province China

ISBN: (纸本)9781509003914

To solve the problem of poor robustness and low effectiveness of visual tracking in complex scenes, a novel target tracking algorithm based on adaptive observation weight is proposed in this paper. First of all, a weighted observation model is established by linear visual tracking representation. Then an iterative optimization algorithm is proposed to obtain the parameters of the model, and adaptively update the weight matrix to eliminate negative influences of observation outliers. Finally, an effective likelihood evaluation function is adopted to track the object accurately and robustly. Analyzing both qualitatively and quantitatively on several challenging video sequences demonstrate that the algorithm outperforms other state-of-the-art tracking algorithms in tracking accuracy and robustness.

关键词： Target tracking Adaptation models Optimization Visualization Algorithm design and analysis Encoding

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A New Optimization Method for Linear Parameter Varying Modeling of Wind Turbines 34

A New Optimization Method for Linear Parameter Varying Model...

引用

第三十四届中国控制会议

作者： WU Dinghui SONG Jin JI Zhicheng PAN Tinglong SHEN Yanxia Key Laboratory of Advanced Process Control for Light Industry Jiangnan University Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment & Technology

ISBN: (纸本)9781467374439

In this paper, a new modeling method of the variable speed variable pitch wind turbine is proposed. More specifically,the linear parameter varying model of wind turbines is optimized by utilizing the variable forgetting factor recursive least squares identification algorithm, which improves the accuracy of the online estimation of the aerodynamic parameters. As the power factor results in the nonlinear characteristics of the wind turbine, the nonlinear power factor is approximate to a polynomial function of the tip speed ratio and the pitch angle. Then the relationship between the aerodynamic parameters and the power factor can be deduced. Furthermore, the solving problem of aerodynamic parameters can be transformed into the identification of the power factor. It is depicted in the simulation results that the modeling method of wind turbines can be optimized from the proposed variable forgetting factor recursive least squares identification algorithm, and the controller obtained from the optimized model can improve stability.

关键词： Wind Turbines,Aerodynamic Parameter,Identification,Linear Parameter Varying

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Ferroelectricity of structural origin in the spin-chain compounds Ca3Co2−xMnxO6

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Physical Review B 2017年第6期96卷 064112-064112页

作者： J. Shi J. D. Song J. C. Wu X. Rao H. L. Che Z. Y. Zhao H. D. Zhou J. Ma R. R. Zhang L. Zhang X. G. Liu X. Zhao X. F. Sun Department of Physics University of Science and Technology of China Hefei Anhui 230026 People's Republic of China Hefei National Laboratory for Physical Sciences at Microscale University of Science and Technology of China Hefei Anhui 230026 People's Republic of China Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 People's Republic of China Department of Physics and Astronomy University of Tennessee Knoxville Tennessee 37996 USA National High Magnetic Field Laboratory Florida State University Tallahassee Florida 32306-4005 USA Collaborative Innovation Center of Advanced Microstructures Nanjing Jiangsu 210093 People's Republic of China Key Laboratory of Artificial Structures and Quantum Control Department of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 People's Republic of China High Magnetic Field Laboratory Chinese Academy of Sciences Hefei Anhui 230031 People's Republic of China School of Physical Sciences University of Science and Technology of China Hefei Anhui 230026 People's Republic of China Key Laboratory of Strongly-Coupled Quantum Matter Physics Chinese Academy of Sciences Hefei Anhui 230026 People's Republic of China

We report a systematic study of the structure, electric, and magnetic properties of Ca3Co2−xMnxO6 single crystals with x=0.72 and 0.26. The dc and ac magnetic susceptibilities display anomalies with characteristic of the spin freezing. The crystals show ferroelectric transition at 40 and 35 K (TFE) for x=0.72 and 0.26, respectively, with a large value of 1400μC/m2 at 8 K for the electric polarization (Pc) along the spin-chain (c-axis) direction. Interestingly, the electric polarization perpendicular to the chain direction (Pab) can also be detected and has the value of 450 and 500μC/m2 at 8 K for the x=0.72 and 0.26 samples, respectively. The specific heat and magnetic susceptibility show no anomaly around TFE, which means that the electric polarization of these samples has no direct relationship with the magnetism. The x-ray diffraction and the Raman spectroscopy indicate that these samples may undergo Jahn-Teller distortions that could be the reason of electric polarization.

关键词： Ferroelectricity Magnetism

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