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Reliability of DC-link capacitor in pulsed power supply for accelerator magnet

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Nuclear Science and Techniques 2024年第9期35卷 28-40页

作者： Jie Wang da-Qing Gao Wan-Zeng shen Hong-Bin Yan Li-jun Mao Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China

Capacitors are widely used in pulsed magnet power supplies to reduce ripple voltage,store energy,and decrease power *** this study,DC-link capacitors in pulsed power supplies were *** deriving an analytical method for the capacitor current on the H-bridge topology side,the root-mean-square value of the capacitor current was calculated,which helps in selecting the DC-link *** proposed method solves this problem quickly and with high *** current reconstruction of the DC-link capacitor is proposed to avoid structural damage in the capacitor’s current measurement,and the capacitor’s hotspot temperature and temperature rise are calculated using the FFT *** test results showed that the error between the calculated and measured temperature increases was within 1.5℃.Finally,the lifetime of DC-link capacitors was predicted based on Monte Carlo *** proposed method can evaluate the reliability of DC-link capacitors in a non-isolated switching pulsed power supply for accelerators and is also applicable to film capacitors.

关键词： Aluminum electrolytic capacitor DC-link current DC–DC power converter Hotspot temperature

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水资源费征收的理论依据及定价方法

水利学报 2006年第1期37卷 120-125页

作者：沈大军中国水利水电科学研究院水资源研究所北京100044

水资源费是我国水资源管理的重要经济手段。本文分析了水资源费征收的理论依据,论证了水资源的产权、稀缺性及投入补偿特性,并以此为水资源费的征收依据,建立了以成本费用为基础的水资源费计算方法和以市场供需为基础的水资源费计算方... 详细信息

水资源费是我国水资源管理的重要经济手段。本文分析了水资源费征收的理论依据,论证了水资源的产权、稀缺性及投入补偿特性,并以此为水资源费的征收依据,建立了以成本费用为基础的水资源费计算方法和以市场供需为基础的水资源费计算方法。这两种方法为基于行政管理配置和市场配置的水资源管理体制提供了计算依据。

关键词：水资源费征收依据以成本费用为基础的定价方法以市场供需为基础的定价方法

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中国水管理中的公正问题

水利学报 2005年第1期36卷 95-99页

作者：沈大军中国水利水电科学研究院水资源研究所北京100044

水管理中的公正问题是我国水资源可持续开发利用所亟待解决的重大问题。本文分析了我国水管理中存在的许多程序不公正、结果不公正以及代际不公正等各种问题,如基本生活用水没有完全保障,农业用水被挤占,水环境恶化,以及缺乏利害相关者... 详细信息

水管理中的公正问题是我国水资源可持续开发利用所亟待解决的重大问题。本文分析了我国水管理中存在的许多程序不公正、结果不公正以及代际不公正等各种问题,如基本生活用水没有完全保障,农业用水被挤占,水环境恶化,以及缺乏利害相关者的参与和决策透明度等等。提出了实现水管理公正的途径,即正确处理效率和公平的关系,促进参与,加强信息披露,加强弱势群体的能力建设,合理界定和规范政府的职能等。

关键词：公正水管理程序公正结果公正代际公正参与能力建设信息披露

Mechanism of microarc oxidation on AZ91D Mg alloy induced byβ-Mg_(17)Al_(12) phase

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International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 712-724页

作者： dajun Zhai Xiaoping Li jun shen College of Materials Science and Engineering Chongqing UniversityChongqing 400044China

This work proposed a strategy of indirectly inducing uniform microarc discharge by controlling the content and distribution ofβ-Mg_(17)Al_(12)phase in AZ91D Mg *** kinds of nano-particles(ZrO_(2)and TiO_(2))were designed to be added into the substrate of Mg alloy by friction stir processing(FSP).Then,Mg alloy sample designed with different precipitated morphology ofβ-Mg_(17)Al_(12)phase was treated by microarc oxidation(MAO)in Na_(3)PO_(4)/*** characteristics and performance of the MAO coating was analyzed using scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),contact angle meter,and potentiodynamic *** was found that the coarseα-Mg grains in extruded AZ91D Mg alloy were refined by FSP,and theβ-Mg_(17)Al_(12)phase with reticular structure was broken and *** nano-ZrO_(2)particles were pinned at the grain boundary by FSP,which refined theα-Mg grain and promoted the precipitation ofβ-Mg_(17)Al_(12)phase in *** effectively inhibited the“cascade”phenomenon of microarcs,which induced the uniform distribution of discharge *** MAO coating on Zr-FSP sample had good wettability and corrosion ***,TiO_(2)particles were hardly detected in the coating on TiFSP sample.

关键词： AZ91D Mg alloy microarc oxidation friction stir processing ZrO_(2) TiO_(2) β-Mg_(17)Al_(12)

Study of primordial deuterium abundance in Big Bang nucleosynthesis

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Nuclear Science and Techniques 2024年第3期35卷 208-215页

作者： Zhi-Lin shen Jian-jun He Key Laboratory of Beam Technology of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Institute of Radiation Technology Beijing Academy of Science and TechnologyBeijing 100875China

Big Bang nucleosynthesis(BBN)theory predicts the primordial abundances of the light elements^(2) H(referred to as deuterium,or D for short),^(3)He,^(4)He,and^(7) Li produced in the early *** these,deuterium,the first nuclide produced by BBN,is a key primordial material for subsequent *** date,the uncertainty in predicted deuterium abundance(D/H)remains larger than the observational *** this study,the Monte Carlo simulation code PRIMAT was used to investigate the sensitivity of 11 important BBN reactions to deuterium *** found that the reaction rate uncertainties of the four reactions d(d,n)^(3)He,d(d,p)t,d(p,γ)^(3)He,and p(n,γ)d had the largest influence on the calculated D/H ***,the calculated D/H uncertainty cannot reach observational precision even with the recent LUNA precise d(p,γ)^(3) He *** the nuclear physics aspect,there is still room to largely reduce the reaction-rate uncertainties;hence,further measurements of the important reactions involved in BBN are still necessary.A photodisintegration experiment will be conducted at the Shanghai Laser Electron Gamma Source Facility to precisely study the deuterium production reaction of p(n,γ)d.

关键词： Big Bang nucleosynthesis Abundance of deuterium Reaction cross section Reaction rate Monte Carlo method

Physics of cavitation near particles

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Journal of Hydrodynamics 2024年第1期36卷 102-118页

作者： Jia-xin Yu Xiao-yu Wang jun-wei shen Jin-sen Hu Xiang-qing Zhang da-qing He Yu-ning Zhang Key Laboratory of Power Station Energy Transfer Conversion and System(Ministry of Education) School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China

The combined effect of cavitation and silt abrasion presents a great challenge and threat to secure the operation and the efficiency of hydraulic machineries working in sediment-laden *** present paper critically reviews the current research progress on the interaction mechanisms of the bubbles and the ***,the analytical models including boundary treatment methods for predicting the jet dynamics of the bubble collapse near particles are ***,the bubble collapsing dynamics,jet dynamics and shock wave characteristics near particles are revealed both experimentally and ***,the bubble-particle-wall system is investigated with a focus on microjets.

关键词： Cavitation bubble particle jet shock wave

Theory and classification of mass extinction causation

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National Science Review 2024年第1期11卷 16-36页

作者： Thomas J.Algeo jun shen State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences—Wuhan State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences—Wuhan Department of Geosciences University of Cincinnati

Theory regarding the causation of mass extinctions is in need of systematization, which is the focus of this contribution. Every mass extinction has both an ultimate cause, i.e. the trigger that leads to various climato-environmental changes, and one or more proximate cause(s), i.e. the specific climato-environmental changes that result in elevated biotic mortality. With regard to ultimate causes, strong cases can be made that bolide(i.e. meteor) impacts, large igneous province(LIP) eruptions and bioevolutionary events have each triggered one or more of the Phanerozoic Big Five mass extinctions, and that tectono-oceanic changes have triggered some second-order extinction events. Apart from bolide impacts, other astronomical triggers(*** flares, gamma bursts and supernova explosions) remain entirely in the realm of speculation. With regard to proximate mechanisms, most extinctions are related to either carbon-release or carbon-burial processes, the former being associated with climatic warming, ocean acidification, reduced marine productivity and lower carbonate δ13C values, and the latter with climatic cooling, increased marine productivity and higher carbonate δ13C values. Environmental parameters such as marine redox conditions and terrestrial weathering intensity do not show consistent relationships with carbon-cycle *** this context, mass extinction causation can be usefully classified using a matrix of ultimate and proximate factors. Among the Big Five mass extinctions, the end-Cretaceous biocrisis is an example of a bolide-triggered carbon-release event, the end-Permian and end-Triassic biocrises are examples of LIP-triggered carbon-release events, and the Late Ordovician and Late Devonian biocrises are examples of bioevolution-triggered carbon-burial events. Whereas the bolide-impact and LIP-eruption mechanisms appear to invariably cause carbon release, bioevolutionary triggers can result in variable carbon-cycle changes, e.g. carbon burial durin

关键词： biocrisis ultimate cause proximate cause bolide large igneous province bioevolutionary event

Large reversible magnetocaloric effect in antiferromagnetic Er_(3)Si_(2)C_(2) compound

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Journal of Rare Earths 2024年第8期42卷 1555-1559,I0005页

作者： Hao Sun Lu Tian Xinqiang Gao Zhaojun Mo jun shen Baogen shen School of Rare Earths University of Science and Technology of ChinaHefei230026China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou341000China Department of Energy and Power Engineering School of Mechanical EngineeringBeijing Institute of TechnologyBeijing100081China

The magnetic properties,magnetic phase transition and magnetocaloric effects(MCE) of Er_(3)Si_(2)C_(2) compound were investigated based on theoretical calculations and experimental *** on the first principles calculations,the antiferromagnetic(AFM) ground state type in Er_(3)Si_(2)C_(2) compound was predicted and its electronic structure was *** experimental results show that Ei_(3)Si_(2)C_(2) compound is an AFM compound with the Neel temperature(T_(N) of 7 K and undergoes a field-induced firstorder magnetic phase transition from AFM to ferromagnetic(FM) under magnetic fields exceeding 0.6 T at 2 *** magnetic transition process of Er_(3)Si_(2)C_(2) compound was investigated and *** values of the maximum magnetic entropy change(-ΔS_(M)^(max)) and the refrigeration capacity(RC) are 17 J/(kg·K)and 193 J/kg under changing magnetic fields of 0-5 T,*** a potential cryogenic magnetic refrigerant,the Er_(3)Si_(2)C_(2) compound also provides an interesting research medium to study the magnetic phase transition process.

关键词： Magnetic materials Magnetocaloric Metamagnetic transitions Magnetic phase transition Rare earths

Regulatory Expression of Peroxisome Proliferator Activated Receptors Genes During Fatty Liver Formation in Geese

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Agricultural Sciences in China 2010年第1期9卷 113-120页

作者： LUO Jin-biao TIAN Yong TAO Zheng-rong YUAN Qing-yan LI Guo-qin YUAN Ai-ping ZOU Li-li LU Li-zhi shen jun-da SHI Fang-xiong Institute of Animal Husbandry & Veterinary Medicine Zhejiang Academy of Agricultural Sciences Hangzhou 310021 P.R.China College of Animal Science and Technology Nanjing Agricultural University Nanjing 210095 P.R.China

In order to investigate the expression pattern of peroxisome proliferator activated receptor （PPAR） genes before and after overfeeding, and estimate the effect of expressed PPAR levels on weights of fatty liver and abdominal fat in geese, the RT-PCR products of PPAR genes in heart, liver, spleen, lung, kidney, stomach, small intestine, brain, breast muscle, leg muscle, and abdominal fat were determined before and after overfeeding. RT-PCR was used to determine the expression levels of PPAR genes. Quantity one software was used to analyze absorbency, and the expression level of GAPDH gene was used as contrast. Expression levels of PPAR-α were relatively high in most of detected tissues but undetectable in abdominal fat tissue before overfeeding, and the level was evidently increased in lung, appeared in abdominal fat tissue, and reduced in the other tissues after overfeeding. Expressed PPAR-γ levels were relatively high in liver, spleen, lung, small intestine, and abdominal fat, and relatively low in the other tissues before overfeeding. Expressed PPAR-γ levels were enhanced in liver, spleen, lung, stomach, and kidney but decreased in abdominal fat and without obvious changes in the other tissues. Expression patterns of PPAR genes show tissue-specific manner. In addition, expression patterns of PPAR-α are different from PPAR-γ after overfeeding. It might suggest that different functions of PPAR subtypes are responsive to overfeeding.

关键词： PPAR gene RT-PCR goose fatty liver