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Analysis of Eddy-Current Loss and its Reduction in a Conduction-Cooled HTS Magnet

IOP Conference Series: Earth and Environmental science 2019年第4期300卷

作者： Kai Ji Wenfeng Long Jinping He Jun Zheng National Key Laboratory of Science and Technology on Vessel Integrated Power System Wuhan Institute of Marine Electric Propulsion Wuhan China

Since conduction cooling system is environmental friendly and easy operating, the conduction-cooled method is widely used in cryogenic cooling system of high-temperature superconducting (HTS) magnet. The eddy-current losses are generated in the cooling structures when HTS magnet is charging and discharging or the current in the magnet is alternating. In this paper, a 3D model of analyzing the eddy-current loss was built. The eddy-current losses of a HTS magnet with different cooling structures were calculated. Thermal analysis of the HTS magnet was carried out together with the electromagnetic analysis. The effect of the cooling structures' geometric parameters on the eddy-current losses was discussed. The methods of reducing the eddy-current loss were proposed. The analysis results demonstrate that the optimization of the geometric parameters would greatly benefit the reduction of the eddy-current losses.

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Improved Production and Antitumor Properties of Triterpene Acids from Submerged Culture of Ganoderma lingzhi

Improved Production and Antitumor Properties of Triterpene A...

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中国菌物学会2018年学术年会

作者： Xiao-Ling Wang Zhong-Yang Ding Gao-Qiang Liu Hailong Yang Guo-Ying Zhou Hunan Provincial Key Laboratory for Forestry Biotechnology Central South University of Forestry and Technology Hunan Provincial Key Laboratory for Control of Forest Diseases and Pests College of Life Science and TechnologyCentral South University of Forestry & Technology National Engineering Laboratory for Cereal Fermentation Technology Jiannan University College of Life and Environmental Science Wenzhou University

Triterpene acids(TAs) are the major bioactive constituents in the medicinal fungus Ganoderma ***, fermentative production of TAs has not been optimized for commercial use, and whether the TAs isolated from submerged culture G. lingzhi mycelia possess antitumor activity needs to be further proven. In this study, enhanced TA yield and productivity were attained with G. lingzhi using response surface methodology. The interactions of three variables were studied, i.e., initial pH, dissolved oxygen(DO) and fermentation temperature,using the Box-Benhnken design. The optimum conditions were an initial pH of 5.9, 20.0 % DO and 28.6°C. These conditions resulted in a TA yield of 308.1 mg/L in a 5-L stirred bioreactor. Furthermore, the optimized conditions were then successfully scaled up to a production scale of 200 L, and maximum TA production and productivity of295.3 mg/L and 49.2 mg/L per day were achieved, which represented 80.9% and 111.5% increases compared with the non-optimized conditions, respectively. Additionally, the triterpene acid extract(TAE) from G. lingzhi mycelia was first found to be cytotoxic to the SMMC-7721 and SW620 cell lines in vitro, and the TAE exhibited dose-dependent antitumor activity against the solid tumor sarcoma 180 in vivo. Chemical analysis revealed that the key active triterpene compounds, ganoderic acid T and ganoderic acid Me, dominantly existed in the extract.

关键词： Ganoderma lingzhi Triterpene acids Submerged culture Antitumor activity

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Topological phase transition between distinct Weyl semimetal states in MoTe2

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Physical Review B 2019年第20期100卷 201107(R)-201107(R)页

作者： Anmin Zhang Xiaoli Ma Changle Liu Rui Lou Yimeng Wang Qiaohe Yu Yiyan Wang Tian-long Xia Shancai Wang Lei Zhang Xiaoqun Wang Changfeng Chen Qingming Zhang School of Physical Science and Technology Lanzhou University Lanzhou 730000 China Department of Physics Renmin University of China Beijing 100872 China Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field Laboratory Chinese Academy of Sciences Hefei 230031 China Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education) School of Physics and Astronomy Tsung-Dao Lee Institute Shanghai Jiao Tong University Shanghai 200240 China Department of Physics and Astronomy University of Nevada Las Vegas Nevada 89154 USA Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China

We present experimental evidence of an intriguing phase transition between distinct topological states in the type-II Weyl semimetal MoTe2. We observe anomalies in the Raman phonon frequencies and linewidths as well as electronic quasielastic peaks around 70 K, which, together with structural, thermodynamic measurements, and electron-phonon coupling calculations, demonstrate a temperature-induced transition between two topological phases previously identified by contrasting spectroscopic measurements. An analysis of experimental data suggests electron-phonon coupling as the main driving mechanism for the change of key topological characters in the electronic structure of MoTe2. We also find the phase transition to be sensitive to sample conditions distinguished by synthesis methods. These discoveries of temperature and material condition-dependent topological phase evolutions and transitions in MoTe2 advance the fundamental understanding of the underlying physics and enable an effective approach to tuning Weyl semimetal states for technological applications.

关键词： Topological phase transition Transition metal dichalcogenides Inelastic light scattering Resistivity measurements Specific heat measurements X-ray powder diffraction

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Indirect Vector control for Stand-alone Operation Brushless Doubly Fed Induction Generator Employing Power Winding Stator Flux Orientated Approach

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IOP Conference Series: Materials science and Engineering 2019年第4期612卷

作者： Kai Ji Wenfeng Long Jinping He National Key Laboratory of Science and Technology on Vessel Integrated Power System Wuhan Institute of Marine Electric Propulsion Wuhan China

The brushless doubly-fed induction generator (BDFIG) provides an interesting alternative to the commonly applied conventional doubly-fed induction generator in wind turbines. In this paper, a novel voltage control strategy of stand-alone operation BDFIG for variable speed constant frequency wind energy conversion systems was presented. Based on the model of the generator, the power winding stator voltage and flux for stand-alone operation BDFIG are only determined by the equivalent PW stator magnetizing current which are independent of load, but PW stator terminal output power is only determined by load. An indirect PW stator flux orientated vector control scheme is employed to control the BDFIG by regulating the amplitude and frequency of the control winding stator current appropriately, and this results in constant generator terminal voltage and frequency for variations in both load and wind speed. In addition, simulation results prove the feasibility and validity of the proposed scheme, and excellent steady and dynamic state performance is achieved.

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Systems metabolic engineering strategies for the production of amino acids

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Synthetic and Systems Biotechnology 2017年第2期2卷 87-96页

作者： Qian Ma Quanwei Zhang Qingyang Xu Chenglin Zhang Yanjun Li Xiaoguang Fan Xixian Xie Ning Chen National and Local United Engineering Lab of Metabolic Control Fermentation Technology Tianjin University of Science and TechnologyTianjin300457China Key Laboratory of Industrial Fermentation Microbiology Ministry of EducationTianjin University of Science and TechnologyTianjin300457China College of Biotechnology Tianjin University of Science and TechnologyTianjin300457China

Systems metabolic engineering is a multidisciplinary area that integrates systems biology,synthetic biology and evolutionary *** is an efficient approach for strain improvement and process optimization,and has been successfully applied in the microbial production of various chemicals including amino *** this review,systems metabolic engineering strategies including pathwayfocused approaches,systems biology-based approaches,evolutionary approaches and their applications in two major amino acid producing microorganisms:Corynebacterium glutamicum and Escherichia coli,are summarized.

关键词： Systems metabolic engineering Amino acid Corynebacterium glutamicum Escherichia coli

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Distributed and coordinated control for large scale spacecraft swarm using sliding mode control and artificial bifurcating potential field

Distributed and coordinated control for large scale spacecra...

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AIAA Guidance, Navigation, and control Conference, 2018

作者： Chen, Haibing Ning, Guodong Sun, Jinfeng Li, Kang Zhang, Shuguang Airworthiness Technologies Research Center School of Transportation Science and Engineering Beihang University Beijing100191 China Aircraft/Engine Integrated System Safety Beijing Key Laboratory Beijing100191 China Aerospace Technology Institute Beijing10007 China School of Transportation Science and Engineering Beihang University Beijing100191 China Beijing Institute of Control Engineering Beijing100080 China

ISBN: (数字)9781624105265

ISBN: (纸本)9781624105265

Spacecraft swarm poses great advantages in various fields that are rapidly evolving with the demands for fulfilling multi-purpose space exploration missions, such as flight observations, environmental awareness, and data transmission. In the paper, a new distributed autonomous control method for spacecraft swarm formation flying is developed based on the theory of artificial potential field and sliding mode control method. Inspired by the dynamic system theory, artificial potential velocity field of the spacecraft swarm is designed by using the nonlinear bifurcation theory to generate desired motion path. The artificial velocity field is mainly used to generate the velocity command, which can set planning path in real time. Each agent in the swarm can be driven to reach some corresponding desired position without external command, which greatly reduces the complexity of the planning algorithm. Sliding mode control is used to ensure the precise tracking control for members and system robustness to eliminate external disturbance and uncertainties. Numerical simulations are presented to show the feasibility of the proposed control strategy, which can achieve various desired swarm formation flying configurations and accomplish formation capture, maintenance and reconstruction successfully. © 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All right reserved.

关键词： Spacecraft

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A light weight and broadband metamaterial absorber with 3D cube unit cells

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Applied Physics A 2018年第6期124卷 1-7页

作者： Guorui Zhang Li Wang Yang Zhou Peiheng Zhou Haiyan Chen Longjiang Deng National Engineering Research Center of Electromagnetic Radiation Control Materials University of Electronic Science and Technology of China Chengdu China Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education University of Electronic Science and Technology of China Chengdu China Kuang-Chi Institute of Advanced Technology Shenzhen China

Metamaterial absorber (MA) with lossless spacing substrate is accompanied by total reflection which is a defect for the broadband design. In this paper, a theoretical transmission-line study of the total reflection is presented to introduce a 3D structural solution: a MA with polyurethane foam inserted by lateral resistive sheets and sandwiched between surface-resistive sheets and grounded aluminum foil. By virtue of the effective parallel plate capacitors formed between the neighboring square-resistive sheets which are perpendicular to the incident electric field, electromagnetic loss is generated from the charges accumulate and ohmic loss on them. As a result, the original total reflection (at f = 10 GHz) can be eliminated and a broadband absorption (from 2.88 to 18 GHz) with absorbance more than 90% is obtained for the proposed light weight (5.64 × 10−5 g/mm3) 3D MA. The measurement result has a good agreement with simulation. This design opens up opportunities for the absorption bandwidth enhancement of MA and can be extended to infrared or optical region.

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Experimental Study on Chloride Ion Removal in High-Salt Wastewater System

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IOP Conference Series: Earth and Environmental science 2020年第1期495卷

作者： Jie Lu Mengdie Ma Dengxin Li Shihong Xu College of Environmental Science and Engineering Donghua University Shanghai 201620 National Environmental Protection Textile Pollution Prevention Engineering Technology Center Donghua University Shanghai 201620 State Key Laboratory of Pollution Control and Resource Research College of Environmental Science and Engineering Tongji University Shanghai 200082 Institute of Pollution Control and Ecological Security Shanghai 200082

Chlorine is usually present in the environment in an ionic state, is highly mobile and difficult to degrade. High-chlorine wastewater can corrode buildings and affect the growth of animals and plants. Therefore, how to solve the environmental problem of high concentration of chloride ions well and effectively has drawn the intensive attention of the society. In this paper, chloride ion is removed from wastewater with the method of coprous chloride precipitation, and investigation is made on the effects of pH, temperature, amount of precipitant, titration time and reaction time on the removal efficiency of chloride ions. The results show that: when nCuSO4:nNa2SO3:nNaCl: n(ascorbic acid) =1.3:1.1:1: 0.01, and reaction pH is 3, temperature is 80 °C, titration time of sodium sulfite is 20min, reaction time after titration is 30min, the chloride ion has the optimal removal efficiency. SEM method is used for the characterization of the precipitates formed by the reaction. The results show that the experimentally produced complex cuprous chloride is irregular polyhedron with uneven particle size.

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Accurate Insect Body Length Extraction Based on the Invariant Target Parameters

Accurate Insect Body Length Extraction Based on the Invarian...

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IEEE International Conference on Computational Electromagnetics (ICCEM)

作者： Cheng Hu Weidong Li Rui Wang Changjiang Liu Quan Yuan Peng Sun BIT Beijing Institute of Technology Beijing China Yueyang Meteorological Bureau of Hunan Province Yueyang China National Key Laboratory of Science and Technology on Aerospace Intelligent Control Beijing China

ISBN: (纸本)9781538612422

A novel insect body length extraction method is proposed based on the invariant target parameters of the insect polarization scattering matrix (PSM). Two eigenvalues of the insect Graves power matrix are invariant target parameters, which are related directly to the target's geometrical properties and independent of the target orientation and the type of radar illumination. In this paper, the physical meaning of the eigenvalues is first studied. Then, the relation between the insect body length and the eigenvalues is found based on the 168 insect specimens measured by the X-band rotating linear polarization radar. Finally, the empirical formula for extracting the insect body length is built, which can achieve high-accuracy body length extraction.

关键词： Insects Eigenvalues and eigenfunctions Radar cross-sections Scattering Length measurement Radar antennas

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Construction and the Second-order Nonlinear Optics of a New Chiral Coordination Network Based on Two Types of Homo-chiral Helices

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Chinese Journal of Structural Chemistry 2017年第7期36卷 1172-1178页

作者：黄永清王阳郭秉林刘承龙李宗阁赵越 State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology College of Chemical and Environmental Engineering Shandong University of Science and Technology Qingdao 266590 China Coordination Chemistry Institute State Key Laboratory of Coordination Chemistry School of Chemistry and Chemical Engineering Nanjing National Laboratory of Microstructures Nanjing University Nanjing 210093 China

A new 2D chiral cadmium coordination network [Cd（TCBA）2]？2EtOH （1） was prepared by the reaction of achiral angular asymmetric bridging ligand 2-（（3,5-dimethyl- 4H-1,2,4-triazol-4-yl）-carbamoyl）-benzoic acid （TCBA） with cadmium acetate, which was structurally characterized by IR, elemental analysis, thermogravimetric analysis and single-crystal X-ray diffraction. Complex 1 crystallizes in the chiral space group P21 and features a 2D chiral network consisting of two types of homo-chiral helices, which are further extended into a 3D chiral framework along the a-axis via hydrogen bonds. Moreover, powder second-order nonlinear optical （NLO） measurements reveal complex 1 has a modest second-harmonic-generation （SHG） efficiency at room temperature.

关键词： cadmium（Ⅱ） chiral helix SHG activity coordination network crystal structure

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