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Sensitivity studies of a high accuracy surface modeling method

Science China Earth Sciences 2014年第10期57卷 2386-2396页

作者： ZHAO Na YUE TianXiang ZHAO MingWei DU ZhengPing FAN ZeMeng CHEN ChuanFa State key laboratory of Resources and Environmental Information system Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Geomatics College Shandong University of Science and Technology

The sensitivities of the initial value and the sampling information to the accuracy of a high accuracy surface modeling(HASM) are investigated and the implementations of this new modeling method are modified and enhanced. Based on the fundamental theorem of surface theory, HASM is developed to correct the error produced in geographical information system and ecological modeling process. However, the earlier version of HASM is theoretically incomplete and its initial value must be produced by other surface modeling methods, such as spline, which limit its promotion. In other words, we must use other interpolators to drive HASM. According to the fundamental theorem of surface theory, we modify HASM, namely ***, by adding another important nonlinear equation to make it independent of other methods and, at the same time, have a complete and solid theory foundation. Two mathematic surfaces and monthly mean temperature of 1951–2010 are used to validate the effectiveness of the new method. Experiments show that the modified version of HASM is insensitive to the selection of initial value which is particular important for HASM. We analyze the sensitivities of sampling error and sampling ratio to the simulation accuracy of ***. It is found that sampling information plays an important role in the simulation accuracy of ***. Another feature of the modified version of HASM is that it is theoretically perfect as it considers the third equation of the surface theory which reflects the local warping of the surface. The modified HASM may be useful with a wide range of spatial interpolation as it would no longer rely on other interpolation methods.

关键词： HASM spatial interpolation initial value sensitivity accuracy temperature

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Large-scale plasma grafts voltage stabilizer on hexagonal boron nitride for improving electrical insulation and thermal conductivity of epoxy composite

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High Voltage 2023年第3期8卷 550-559页

作者： Penghao Zhang Chenguo Yao Liang Yu Xuetong Zhao Lisheng Zhao Linghan Lan Shoulong Dong State key laboratory of Power Transmission Equipment and system Security and New technology School of Electrical EngineeringChongqing UniversityChongqingChina School of Energy and Power Engineering Chongqing UniversityChongqingChina

Better electrical insulation and thermal management are both urgently required in integrated power *** insulation epoxy encapsulation suffers from poor heat conduction,which has increasingly become a bottleneck of power semiconductors *** incorporating high thermal conductivity ceramics,such as hexagonal boron nitride(hBN),aluminium nitride *** epoxy promotes the thermal conductivity,the eco-friendly scalable fabrication of these composites with sufficient electrical breakdown strength remains a formidable *** voltage stabilizers are known to provide additional benefits to breakdown ***,a highthroughput approach combining plasma with roll-to-roll was *** voltage stabilizer(acetophenone)was grafted on interfaces between hBN and epoxy matrix through *** high-energy electrons are consumed by the grafted interface,which leads to the significant suppression of partial discharge in Epoxy/***,interfacial phonon scattering is repaired by ***,the epoxy composite concurrently exhibits improved breakdown strength(by 27.4%)and thermal conductivity(by 142.9%)at about 11.9 wt.%filler content,outperforming the pure ***,a promising modification strategy for mass production is provided for the encapsulation materials in various high-power-density semiconductor devices.

关键词： composite conductivity insulation

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Evaluation on the Two Filling Functions for the Recovery of Forest Information in Mountainous Shadows on Landsat ETM + Image

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Journal of Mountain Science 2011年第3期8卷 414-426页

作者： SHAHTAHMASSEBI Amir reza MOORE Nathan Institute of Agriculture Remote Sensing and Information technology Zhejiang University key laboratory of Agricultural Remote Sensing and Information system of Zhejiang Province Department of Geography Michigan State University

In general,topographic shadow may reduce performance of forest mapping over mountainous regions in remotely sensed *** this paper,information in shadow was synthesized by using two filling techniques,namely,roifill and imfill,in order to improve the accuracy of forest mapping over mountainous *** two methods were applied to Landsat Enhanced Thematic Mapper (ETM +) multispectral image from Dong Yang County,Zhejiang Province,*** performance of these methods was compared with two conventional techniques,including cosine correction and multisource *** results showed that by applying filling approaches,average overall accuracy of classification was improved by 14 ***,through conventional methods this value increased only by 9 *** results also revealed that estimated forest area on the basis of shadow-corrected images by 'roifill' technique was much closer to the survey data compared to traditional *** from this finding,our finding indicated that topographic shadow was an accentuated problem in medium resolution images such as Landsat ETM+ over mountainous regions.

关键词： Shadow Imfill: Roifill: Landsat ETM+

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Analysis of aerobic granular sludge formation based on grey system theory

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Journal of Environmental Sciences 2013年第4期25卷 710-716页

作者： Cuiya Zhang Hanmin Zhang key laboratory of Industrial Ecology and Environmental Engineering School of Environmental Science and TechnologyDalian University of Technology

Based on grey entropy analysis, the relational grade of operational parameters with aerobic granular sludge＇s granulation indicators was studied. The former consisted of settling time （ST）, aeration time （AT）, superficial gas velocity （SGV）, height/diameter （H/D） ratio and organic loading rates （OLR）, the latter included sludge volume index （SVI） and set-up time. The calculated result showed that for SVI and set-up time, the influence orders and the corresponding grey entropy relational grades （GERG） were： SGV （0.9935）〉 AT （0.9921）〉 OLR （0.9894）〉 ST （0.9876）〉 H/D （0.9857） and SGV （0.9928）〉 H/D （0.9914）〉 AT （0.9909）〉 OLR （0.9897）〉 ST （0.9878）. The chosen parameters were all key impact factors as each GERG was larger than 0.98. SGV played an important role in improving SVI transformation and facilitating the set-up process. The influence of ST on SVI and set-up time was relatively low due to its dual functions. SVI transformation and rapid set-up demanded different optimal I-I/D ratio scopes （10-20 and 16-20）. Meanwhile, different functions could be obtained through adjusting certain factors＇ scope.

关键词： aerobic granular sludge grey system theory operational impact factor granulation process

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Influence of reaction parameters on the luminescence properties of monodisperse NaGd((1-x-y))(WO4)2:xEu3+,yTb3+ phosphor by molten salt synthesis

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Journal of Rare Earths 2018年第1期36卷 49-57页

作者： Weiqin Xiao Luqiao Yin Jipeng Zhou Fang Lei Ying Shi Jianjun Xie Lei Zhang School of Materials Science and Engineering Shanghai University key laboratory of Advanced Display and system Applications Ministry of Education (Shanghai University)

Eu3+activated and Eu3+, Tb3+co-activated monodisperse sodium double tungstates NaGd(WO4)2 phosphors were prepared by molten salt method at 750 ℃ for 10 h using NaCl as a flux. The crystal structure and morphology of the as-synthesized phosphors were measured by XRD and SEM, respectively. The photoluminescence properties were characterized by PL spectra, decay lifetime and CIE. The presence of NaCl plays an important role in the morphology and luminescence properties. In this work,NaCl and one of the raw material Na2CO3in a certain proportion will form a low eutectic salt to decrease the reaction temperature and benefit the formation of monodisperse NaGd(WO4)2crystals. The color of Eu3+and Tb3+co-doped NaGd(WO4)2phosphors can be tuned from creamy white to orange, red and green by adjusting the doping concentration of rare earth ions, since the emission contain the broad blue-green emission origin from NaGd(WO4)2host and characteristic red and green emission origin from Eu3+and Tb3+ions. The electroluminescent spectra and CIE measurement shows that the LED device with NaGd((1-x))(WO4)2:xEu3+(x = 0.24) phosphor can be excited by 365 nm and 380 nm LED chip, and their CIE coordinate is(x = 0.45, y = 0.45) and(x = 0.36, y = 0.37), Ra is 80.3 and 86.3, Tcis 3196 and4556 K, respectively. As a single-component phosphor, NaGd(WO4)2:Eu3+,Tb3+have potential application in UV-pumped WLEDs.

关键词： NaGd(1-x-y)(WO4)2:xEu3+ yTb3+ Molten salt method Single component WLEDs White light

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SYNTHESIS AND PROPERTIES OF ORGANO-FLY ASH/POLY ANILINE WITH CORE/SHELL STRUCTURE BASED ON EMULSION POLYMERIZATION

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Chinese Journal of Polymer Science 2012年第6期30卷 808-814页

作者：雷西萍 key laboratory of Western Architecture and technology School of Materials Science and EngineeringXi'an University of Architecture and Technology

Organo-fly ash （OFA） was prepared with pretreated fly ash （FA） and hexadecyltrimethyl ammonium bromide （HDTMAB）, and the composites composed of OFA and polyaniline were obtained by emulsion polymerization at different OFA weight ratios （2.0 wt%, 5.0 wt%, 10.0 wt%, 15.0 wt% and 20.0 wt%） in the presence of dodecylbenzenesulfonic acid as dopant and emulsifier. A polymerization procedure was supposed. The electrical conductivities of the composites were tested by the four-probe technique. The chemical structure and crystallinity of the composites were confirmed by FT-IR and X-ray diffraction, respectively. Morphologies of FA, OFA and the composites were observed by SEM. The element analysis was performed by energy dispersive spectrometry. The thermal stability of the composites was analyzed by TGA. The results showed that the electrical conductivity of the composites decreased with increasing the feed weight ratio of OFA, and the lowest value was 0.62 S/cm. HDTMAB and PAn were just adsorbed on the surface of FA and OFA, respectively according to the physical adsorption without destroying the crystalline structure of FA or OFA. The surface became smoother after organification of FA by using HDTMAB, and its content on FA surfaces was about 26.9 wt%. The core/shell structure of the composite was observed by SEM analysis. The composites showed a higher thermal stability than pure PAn by introduction of OFA into this polymerization system, the heat stability of PAn was increased by decreasing 31.8 wt% of weight loss after introducing 20 wt% of OFA.

关键词： Fly ash Polyaniline Hexadecyltrimethyl ammonium bromide Core/shell Emulsion polymerization.

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Optimization of the S-band side-coupled cavities for proton acceleration

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Nuclear Science and Techniques 2020年第3期31卷 1-9页

作者： Hao-Yun Li Xin-Miao Wan Wei Chen Chen-Hui Shi Zhi-Hui Li The key laboratory of Radiation Physics and technology of Ministry of Education Institute of Nuclear Science and Technology Sichuan University

The proton beam with energy around 100 MeV has seen wide applications in modern scientific research and in various ***,proton sources in China fall short for meeting experimental needs owing to the vast size and expensive traditional proton *** Institute of Nuclear Science and technology of Sichuan University proposed to build a 3 GHz side-coupled cavity linac(SCL)for re-accelerating a 26 MeV proton beam extracted from a CS-30 cyclotron to 120 *** carried out investigations into several vital factors of S-band SCL for proton acceleration,such as optimization of SCL cavity geometry,end cell tuning,and bridge coupler *** demonstrated that the effective shunt impedance per unit length ranged from 22.5 to 59.8 MX/m throughout the acceleration process,and the acceleration gradient changed from 11.5 to 15.7 MV/m when the maximum surface electric field was equivalent to Kilpatrick electric *** obtained equivalent circuit parameters of the biperiodic structures and applied them to the end cell tuning;results of the theoretical analysis agreed well with the 3D *** designed and optimized a bridge coupler based on the previously obtained biperiodic structure parameters,and the field distribution un-uniformness was\1.5%for a two-tank *** radio frequency power distribution system of the linac was obtained based on the preliminary beam dynamics design.

关键词： Proton beam Side-coupled cavity linac Accelerating cavity Biperiodic structure Bridge coupler

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Development of core fuel management code system for WWER-type reactors

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Nuclear Science and Techniques 2006年第5期17卷 308-313页

作者： XIA Bang-Yang WANG Tao XIE Zhong-Sheng National key laboratory for Reactor system Design technology Chengdu 610041 China Shanghai Jiaotong University Shanghai 200030 China Xi＇an Jiaotong University Xi＇an 710049 China

In this article, a core fuel management program for hexagonal pressurized water type WWER reactors (CFMHEX) has been developed, which is based on advanced three-dimensional nodal method and integrated with thermal hydraulic code to realize the coupling of neutronics and thermal-hydraulics. In CFMHEX, all these feedback effects such as burnup, power distribution, moderator density, and control rod insertion are considered. The verifica- tion and validation of the code system have been examined through the IAEA WWER-1000-type Kalinin NPP benchmark problem. The numerical results are in good agreement with measurements and are close to those of other international institutes.

关键词：核反应堆压水堆燃料管理三维节点法

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Dynamic simulation of a space gas-cooled reactor power system with a closed Brayton cycle

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Frontiers in Energy 2021年第4期15卷 916-929页

作者： Chenglong WANG Ran ZHANG Kailun GUO Dalin ZHANG Wenxi TIAN Suizheng QIU Guanghui SU Department of Nuclear Science and technology State Key Laboratory of Multiphase Flow in Power EngineeringShaanxi Key Laboratory of Advanced Nuclear Energy and TechnologyXi’an Jiaotong UniversityXi’an 710049China

Space nuclear reactor power(SNRP)using a gas-cooled reactor(GCR)and a closed Brayton cycle(CBC)is the ideal choice for future high-power space *** investigate the safety characteristics and develop the control strategies for gas-cooled SNRP,transient models for GCR,energy conversion unit,pipes,heat exchangers,pump and heat pipe radiator are established and a system analysis code is developed in this ***,analyses of several operation conditions are performed using this *** full-power steady-state operation,the core hot spot of 1293 K occurs near the upper part of the *** 0.4$reactivity is introduced into the core,the maximum temperature that the fuel can reach is 2059 K,which is 914 K lower than the fuel melting *** system finally has the ability to achieve a new steady-state with a higher reactor *** the GCR is shut down in an emergency,the residual heat of the reactor can be removed through the conduction of the core and radiation heat *** results indicate that the designed GCR is inherently safe owing to its negative reactivity feedback and passive decay heat *** paper may provide valuable references for safety design and analysis of the gas-cooled SNRP coupled with CBC.

关键词： gas-cooled space nuclear reactor power closed Brayton cycle system startup and shutdown positive reactivity insertion accident

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Magnetic levitation using diamagnetism:Mechanism,applications and prospects

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Science China(Technological Sciences) 2021年第1期64卷 44-58页

作者： GAO QiuHua YAN Han ZOU HongXiang LI WenBo PENG ZhiKe MENG Guang ZHANG WenMing State key laboratory of Mechanical system and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

As a typical contact-free manipulation technique that removes friction and contamination risk,levitation has gradually become a preferred candidate for various *** levitation using diamagnetism,beyond Earnshaw’s theorem,is a kind of passive stable levitation that can be achieved at normal temperatures with no energy ***,most seemingly nonmagnetic materials can be levitated in a magnetic field and can stabilize free levitation of magnetic *** review focuses on the fundamental principles of magnetic levitation using diamagnetism,with emphasis on its burgeoning *** theoretical basis associated with the magnetic levitation using diamagnetism is discussed by elucidating the characteristics of diamagnetic materials,and the key levitation mechanisms are ***,state-of-the-art applications in various aspects,including sensing and measurement,actuating and micromanipulation,energy harvesting and magnetic gravity compensation,are summarized and ***,the review concludes with a brief outlook on future perspectives.

关键词： magnetic levitation diamagnetism sensors actuators energy harvesters

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