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SiO2气凝胶常压干燥工艺与隔热应用进展

宇航材料工艺 2010年第6期40卷 10-15页

作者：陈晓红胡子君宋怀河王非北京化工大学化工资源有效利用国家重点实验室北京100029 航天材料及工艺研究所先进功能复合材料技术国防科技重点实验室北京100076

综述了SiO2气凝胶常压制备技术及其复合隔热材料的最新研究进展。着重介绍了提高凝胶网络基架强度、添加干燥控制化学添加剂、表面改性、降低毛细管力等几种SiO2气凝胶常压干燥工艺,并回顾了几种SiO2气凝胶复合隔热材料的应用现状。

关键词： SiO2气凝胶常压干燥工艺复合隔热材料应用进展 Thermal insulation Application Ambient Pressure Silica 干燥控制化学添加剂制备技术应用现状研究进展凝胶网络毛细管力表面改性强度

Design of infrared camouflage cloak for underground silos

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Defence Technology（防务技术） 2020年第1期16卷 43-49页

作者： Luo Zhang Qiang Zhang Hong Ye Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefei 230027PR China

The temperature difference between the exposed surface of an underground silo and the surrounding soil surface is significant,which means a silo can be easily found by infrared *** designed an infrared camouflage cloak consisting of an imitative layer and an insulation layer for the *** imitative layer is used to imitate the thermal response of the soil to the surrounding *** insulation layer is used to weaken the impact of the internal temperature field of the silo on the lower boundary of the imitative layer.A silo model including surrounding soil and a soil model without silo were established,and the influences of the material and thickness of each layer on the infrared camouflage effect were *** results show that when using a silicone rubber containing alumina powder with a volume fraction of 3.18% as the imitative material,its thermal inertia is in consistent with that of the ***,it was found that the thickness of the imitative layer doesn't need to be greater than its thermal penetration depth to achieve the infrared camouflage,and the absence of the insulation layer will cause hot spots on the silo surface in winter to weaken the camouflage *** optimized thicknesses of the imitative layer and the insulation layer are 22 cm and 4 cm re *** simulations indicate that with the application of the cloak,the maximum value of the absolute values of the temperature differences between the average temperatures of the silo surface and the surrounding soil surface temperatures drops from 1,59℃ to 0.31℃ in summer and from 1.92℃ to 0.21℃ in *** designed cloak can achieve an all-weather and full-time passive infrared camouflage.

关键词： Underground silo Infrared camouflage cloak Imitative layer insulation layer

Experimental study on dynamic response characteristics of isolated-span transmission lines after ice-shedding

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High Voltage 2023年第1期8卷 196-208页

作者： Guizao Huang Bo Yan Yujun Guo Bo Zhang Guangning Wu School of Electrical Engineering Southwest Jiaotong UniversityChengduChina College of Aerospace Engineering Chongqing UniversityChongqingChina State Grid Henan Electric Power Research Institute ZhengzhouChina

The dynamic response characteristics,including maximum jump height and unbalanced tension,of isolated-span transmission lines after ice-shedding are investigated by means of experiments.A reduced-scale modelling method for ice-shedding from conductor lines is presented and verified with numerical simulations and full-scale test results in the literature.A parameter study on dynamic responses of isolated-span conductors under three ice-shedding scenarios,including whole span ice-shedding,partial ice-shedding and unzipping ice-shedding,is carried out by means of reduced-scale modelling *** effects of these parameters on the maximum jump height at typical positions and unbalanced tension in the tension tower are *** is observed that the partial iceshedding scenario may be the worst situation for electrical insulation clearance rather than the whole span ice-shedding ***,the position of maximum jump height along the span of isolated-span transmission lines after ice-shedding could be at around 2/5 of span length,which is different from the conventional opinion that the position is at the *** results may provide a foundation for the defining of the insulation clearance for an isolated-span transmission line and the structure design of tension tower arms in an iced zone.

关键词： dynamic characteristics insulation

Inorganic Nanometer Transparent Heatinsulation Coatings for Glass

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China Chemical Reporter 2007年第18期18卷 12-12页

Beijing Guobang Technology Development Center has developed aninorganic nanometer transparent and heat-insulation coatings thatcan be used in *** new coatings have selectivity to *** it forms coating layers on glass s... 详细信息

关键词： insulation nanometer Transparent selectivity trans

Behaviour and mechanisms of molecular vibrations induced by a pulsed voltage in a silicone elastomer used for device encapsulation

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High Voltage 2023年第5期8卷 1020-1029页

作者： Junyu Wei Dongxin He Teng Gao Lin Zhu Haochen Wang Qingquan Li Gilbert Teyssedre Shandong Provincial Key Laboratory of UHV Transmission Technology and Equipment School of Electrical Engineering Shandong UniversityJinanChina School of Materials Science and Engineering Shandong UniversityJinanChina UPS INPTCNRSLAPLACE(Laboratoire Plasma et Conversion d’Energie)University of ToulouseToulouseFrance

Silicone elastomers are widely used to encapsulate power electronic ***,such devices may be subjected to square‐wave pulsed voltages with a high rate of change,which can create significant challenges for encapsulation *** this article,the molecular vibration of silicon elastomer at the edge of pulsed electric field is ***,the relationship between the intensity of molecular vibration and the parameters of pulsed electric field is *** experimental results show that the amplitude of the vibrations decreases as the pulse‐edge time increases,and it increases linearly as the pulseedge slope ***,the amplitude of the vibrations is proportional to the square of the amplitude of the pulsed electric field,and it increases as the space charge density ***,the force analysis of charged molecule at the pulse edges is calculated,and the theoretical change law of molecular vibration intensity with pulse edge slope is *** the theoretical results with the experimental results,it is found that they are highly ***,electrically induced mechanical stress caused by molecular vibration was shown to be an important factor in insulation failure.

关键词： pulsed insulation vibrations

High-temperature infrared camouflage with efficient thermal management

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Light(Science & Applications) 2020年第1期9卷 1430-1437页

作者： Huanzheng Zhu Qiang Li Chunqi Zheng Yu Hong Ziquan Xu HanWang Weidong Shen Sandeep Kaur Pintu Ghosh Min Qiu State Key Laboratory of Modern Optical Instrumentation College of Optical Science and EngineeringZhejiang UniversityHangzhou 310027China Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province School of EngineeringWestlake University18 Shilongshan RoadHangzhou 310024China Institute of Advanced Technology Westlake Institute for Advanced Study18 Shilongshan RoadHangzhou 310024China

High-temperature infrared(IR)camouflage is crucial to the effective concealment of high-temperature objects but remains a challenging issue,as the thermal radiation of an object is proportional to the fourth power of temperature(T4).Here,we experimentally demonstrate high-temperature IR camouflage with efficient thermal *** combining a silica aerogel for thermal insulation and a Ge/ZnS multilayer wavelength-selective emitter for simultaneous radiative cooling(high emittance in the 5-8μm non-atmospheric window)and IR camouflage(low emittance in the 8-14μm atmospheric window),the surface temperature of an object is reduced from 873 to 410 *** IR camouflage is demonstrated by indoor/outdoor(with/without earthshine)radiation temperatures of 310/248 K for an object at 873/623 K and a 78% reduction in with-earthshine lock-on *** scheme may introduce opportunities for high-temperature thermal management and infrared signal processing.

关键词： thermal earth insulation

A new approach to the design of surface subsystems of polymeric insulators for HV and MV apparatus under AC voltage

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High Voltage 2023年第4期8卷 651-658页

作者： Gian Carlo Montanari Debasish Nath Pasquale Cambareri Center for Advanced Power Systems Florida State UniversityTallahasseeFloridaUSA Dipartimento di Elettronica Informazione e BioingegneriaPolitecnico di MilanoMilanoItaly

The design of high voltage and medium voltage AC and DC standoff insulators,and,in general,of insulation systems where surface and interface properties are predominant factors,is based on specifications and standards that rely upon long-term experiences and lab *** insulating properties depend on electrical and thermal stresses,besides environmental factors,and the inception of extrinsic ageing phenomena,such as partial discharges,can be already a cause of reduced reliability and premature failure(for organic insulating materials).An innovative approach,based on field simulation,discharge modelling,and partial discharge inception measurements is presented by the authors,which can establish a solid basis to optimise insulation design for any type of supply voltage *** method,the three-leg approach,is applied here to a cable system under AC sinusoidal voltage,but it can work for any type of insulation system,such as bushings,switch gears,transformers,rotating machines,and power electronics boards.

关键词： insulation approach insulator

Comparative study of tribological properties of insulated and conductive polyimide composites

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Friction 2020年第3期8卷 507-516页

作者： Jingfu SONG Yuanhao YU Gai ZHAO Jinhao QIU Qingjun DING College of Material Science and Technology Narijing Universiy of Aeronautics andAstronauticsNanjing 210016China Slate Key Laboratory of Mechanics and Control of Mechanical Sructures Nanjing University of Aeronauties and AstronauticsNanjing 210016China

Insulated polyimide(PI)composites filled with short glass fibers(SGF),polytetrafluoroethylene(PTFE),SiO2,and polyphenylene(PPL)are specially designed,prepared,and the tribological properties are systematically investigated with references to the special requirements for frictional materials used in ultrasonic *** hardness and thermal decomposition temperature of the insulated PI composites are comparable to that of conductive PI ***,these insulated materials present excellent friction and wear performance,especially under high loads and *** electron microscopy(SEM)analysis of the worn surface indicates that adhesive and fatigue wear dominate the wear mechanisms.

关键词： polyimide composites insulation friction wear

Residual charge effects on partial discharges'response to varying sub-kHz voltage frequencies

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High Voltage 2023年第3期8卷 622-629页

作者： Cuthbert Nyamupangedengu Tapiwa Venge School of Electrical and Information Engineering University of the WitwatersrandJohannesburgSouth Africa

Partial discharges(PD)are the‘cancer’of electrical *** design and mitigation of PD-induced degradation should be based on good knowledge of PD *** that regard,a significant body of knowledge has been built up from concerted research across the world in past decades and on various aspects of PD phenomena under various ***,the work is far from being complete as new challenges *** such challenge is that electric power equipment insulation is becoming more exposed to non-power frequency *** are the proliferation of invertor-based grid-tied renewable energy sources and other technologies such as high-frequency power electronic *** that are driving continued research in this regard include the reasons for lack of consensus on the findings on how PD characteristics respond to variations in the voltage *** paper presents results of how residual charge influences PD characteristics'response to voltage frequency changes from 1 to 200 *** study approach is implementing the extended 3-capacitor PD model in MATLAB®Simulink®and validating the findings using the relevant experimental results that are available in *** PD type studied is that of an air cavity encapsulated in a polyethylene *** of the findings are that the extent of the influence of residual charge on PD characteristics depends on the relative magnitude of the residual charge as well as the voltage *** relationships however exhibit non-monotonous *** results further confirm similar findings and conclusions by other researchers and could be signalling the establishment of a more solid knowledge base for design of insulations that operate at non-power frequencies.

关键词： charge insulation finding