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谈雷过压击穿与电子设备保护电路 被引量:1
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作者 王德常 《黄山学院学报》 2005年第6期27-28,共2页
防雷系统不完备地区楼房,频遭感应雷危害,经勘察,排除隐患,检修线路和电子设备,加强防雷措施。另介绍制作雷过压多级保护电路,将低通滤波器元件和限幅器件组合在一起,分析并调试元件参数,抑制雷过压高频大脉冲效果较好,且能净化电源,滤... 防雷系统不完备地区楼房,频遭感应雷危害,经勘察,排除隐患,检修线路和电子设备,加强防雷措施。另介绍制作雷过压多级保护电路,将低通滤波器元件和限幅器件组合在一起,分析并调试元件参数,抑制雷过压高频大脉冲效果较好,且能净化电源,滤除3次以上谐波。 展开更多
关键词 防雷措施 雷过 多级保护 低通滤波 限幅器
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先进的固态三坐标目标指示雷达
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作者 孙宪章 《现代雷达》 CSCD 1990年第5期1-8,49,共9页
我国首部全固态相控阵雷达已设计定型并投入使用。本文扼要介绍了系统功能、系统设计特点、主要性能和工作过程。较详细地介绍了系统的工作方式和主要子系统的结构。文中还介绍了外场设计定型试验的结果。最后是一个简单的展望。
关键词 雷过 三座标 目标指示雷达 固态
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Work up for the clopidogrel hypersensitivity that led to recognising the undi- agnosed myelodysplastic syndrome
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作者 Yoo Sang Baek Jung Woo Lee Jiehyun Jeon 《Journal of Geriatric Cardiology》 SCIE CAS CSCD 2016年第3期274-276,共3页
Antiplatelet therapy with clopidogrel is widely used as a preventive strategy in patients with acute coronary syn- drome, particularly after stent implantation.Diverse mani- festations of clopidogrel hypersensitivity ... Antiplatelet therapy with clopidogrel is widely used as a preventive strategy in patients with acute coronary syn- drome, particularly after stent implantation.Diverse mani- festations of clopidogrel hypersensitivity reaction have been reported including cutaneous,and hematologic symp- toms[31 as well as fatal reactions including thrombotic throm- bocytopenic purpura (TTP). 展开更多
关键词 CLOPIDOGREL HYPERSENSITIVITY Myelodysplastic syndrome
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Mechanism of mine water-inrush through a fault from the floor 被引量:9
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作者 HAN Jin SHI Long-qing +2 位作者 YU Xiao-ge WEI Jiu-chuan LI Shu-cai 《Mining Science and Technology》 EI CAS 2009年第3期276-281,共6页
The mechanism of mine water inrushes in coal mines in China differs considerably from that in other countries.In China, most water inrushes occur from floor strata, where the water-inrush sources are karstic limestone... The mechanism of mine water inrushes in coal mines in China differs considerably from that in other countries.In China, most water inrushes occur from floor strata, where the water-inrush sources are karstic limestone aquifers.Our study describes the mechanism of mine water inrushes through a fault in the mine floor using principles of strata mechanics and the path of water inrush from an aquifer to the working face.A criterion to judge whether a ground water inrush will occur through a fault or not is also described, together with a case history of water inflow in the Feicheng coalfield, China. 展开更多
关键词 FAULT water-inrush MECHANISM Feicheng coalfield
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Microphysical characteristics of precipitating cumulus cloud based on airborne Ka-band cloud radar and droplet measurements 被引量:1
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作者 Lei Wei Mengyu Huang +6 位作者 Rong Zhang Yuhuan Lü Tuanjie Hou Hengchi Lei Delong Zhao Wei Zhou Yuan Fu 《Atmospheric and Oceanic Science Letters》 CSCD 2022年第2期65-70,共6页
Based on cloud-probe data and airborne Ka-band cloud radar data collected in Baoding on 5 August 2018,the microphysical structural characteristics of cumulus(Cu)cloud at the precipitation stage were investigated.The c... Based on cloud-probe data and airborne Ka-band cloud radar data collected in Baoding on 5 August 2018,the microphysical structural characteristics of cumulus(Cu)cloud at the precipitation stage were investigated.The cloud droplets in the Cu cloud were found to be significantly larger than those in stratiform(STF)cloud.In the Cu cloud,most cloud particles were between 7 and 10μm in diameter,while in the STF cloud the majority of cloud particles grew no larger than 2μm.The sensitivity of cloud properties to aerosols varied with height.The cloud droplet effective radius showed a negative relationship with the aerosol number concentration(Na)in the cloud planetary boundary layer(PBL)and upper layer above the PBL.However,the cloud droplet concentration(Nc)varied little with decreased Na in the high liquid water content region above 1500 m.High Na values of between 300 and 1853 cm-3 were found in the PBL,and the maximum Na was sampled near the surface in August in the Hebei region,which was lower than that in autumn and winter.High radar reflectivity corresponded to large FCDP(fast cloud droplet probe)particle concentrations and small aerosol particle concentrations,and vice versa for low radar reflectivity.Strong updrafts in the Cu cloud increased the peak radius and Nc,and broadened cloud droplet spectrum;lower air temperature was favorable for particle condensational growth and produced larger droplets. 展开更多
关键词 Airplane observation Microphysical processes Ka-band cloud radar CUMULUS
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A STUDY ON VARIABLE QUANTITATIVE PRECIPITATION ESTIMATION USING DOPPLER RADAR DATA
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作者 冀春晓 陈联寿 +2 位作者 徐祥德 赵放 吴孟春 《Journal of Tropical Meteorology》 SCIE 2008年第2期109-112,共4页
With the pros and cons of the traditional optimization and probability pairing methods thoroughly considered, an improved optimal pairing window probability technique is developed using a dynamic relationship between ... With the pros and cons of the traditional optimization and probability pairing methods thoroughly considered, an improved optimal pairing window probability technique is developed using a dynamic relationship between the base reflectivity Z observed by radar and real time precipitation I by rain gauge. Then, the Doppler radar observations of base reflectivity for typhoons Haitang and Matsa in Wenzhou are employed to establish various Z-I relationships, which are subsequently used to estimate hourly precipitation of the two typhoons. Such estimations are calibrated by variational techniques. The results show that there exist significant differences in the Z-I relationships for the typhoons, leading to different typhoon precipitation efficiencies. The typhoon precipitation estimated by applying radar base reflectivity is capable of exhibiting clearly the spiral rain belts and mesoscale cells, and well matches the observed rainfall. Error statistical analyses indicate that the estimated typhoon precipitation is better with variational calibration than the one without. The variational calibration technique is able to maintain the characteristics of the distribution of radar-estimated typhoon precipitation, and to significantly reduce the error of the estimated precipitation in comparison with the observed rainfall. 展开更多
关键词 TYPHOON radar quantitative precipitation estimation variational calibration verification
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The Influence of Surge Arrester Location on Over-Voltages Caused by Direct Lightning Strikes to MV Lines
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作者 Alexandre Piantini Thais O. de Carvalho +3 位作者 Paulo F. Obase Jorge M. Janiszewski Gilnei J. G. Santos Donorvan R. Fagundes 《Journal of Energy and Power Engineering》 2014年第3期508-514,共7页
In the period 2003-2011, lightning over-voltages accounted for about 47% of the total number of distribution transformer failures observed in the service area ofAES Sul, a power company that operates in the state of R... In the period 2003-2011, lightning over-voltages accounted for about 47% of the total number of distribution transformer failures observed in the service area ofAES Sul, a power company that operates in the state of Rio Grande doSul, in South Brazil. This paper presents the results of an investigation on the influence of the distance between transformer and MV arresters on the surges at the transformer windings caused by direct strikes to the MV network. The analysis, performed through simulations using the Alternative Transients Program, shows that in general higher voltages are produced by subsequent strokes. Although in relation to the primary side the surges transferred to the secondary are much less affected by the distance between transformers and primary arresters, such distance should always be kept as short as possible in order to reduce the probability of occurrence of transformer failures due to over-voltages at the MV bushings. 展开更多
关键词 Distribution transformer lightning surges overvoltages.
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Identifying soil structure along headwater hillslopes using ground penetrating radar based technique 被引量:7
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作者 HAN Xiao-le LIU Jin-tao +1 位作者 ZHANG Jun ZHANG Zhi-cai 《Journal of Mountain Science》 SCIE CSCD 2016年第3期405-415,共11页
Soil structure plays an important role in understanding soil attributes as well as hydrological processes. Effective method to obtain high quality soil map is therefore important for both soil science research and soi... Soil structure plays an important role in understanding soil attributes as well as hydrological processes. Effective method to obtain high quality soil map is therefore important for both soil science research and soil work ability improvement. However,traditional method such as digging soil pits is destructive and time-consuming. In this study, the structure of headwater hillslopes from Hemuqiao catchment(Taihu Basin, China) have been analyzed both by indirect(ground penetrating radar, GPR) and direct(excavation or soil auger) methods. Four transects at different locations of hillslopes in the catchment were selected for GPR survey. Three of them(#1, #2, and #3) were excavated to obtain fullscale soil information for interpreting radar images.We found that the most distinct boundary that can be detected by GPR is the boundary between soil and underlain bedrock. In some cases(e.g., 8-17 m in transect #2), in which the in situ soil was scarcely affected by colluvial process, different soil layers can be identified. This identification process utilized the sensitive of GPR to capture abrupt changes of soil characteristics in layer boundaries, e.g., surface organic layer(layer #1) and bamboo roots layer(layer#2, contain stone fragments), illuvial deposits layer(layer #3) and regolith layer(layer #4). However, in areas where stone fragments were irregularly distributed in the soil profile(highly affected bycolluvial and/or fluvial process), it was possible to distinguish which part contains more stone fragments in soil profile on the basis of reflection density(transect #3). Transect #4(unexcavated) was used to justify the GPR method for soil survey based on experiences from former transects. After that, O horizon thickness was compared by a hand auger.This work has demonstrated that GPR images can be of a potential data source for hydrological predictions. 展开更多
关键词 Ground Penetrating Radar(GPR) Hillslope Soil structure
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Simulation Study on SAR Images of the Oceanic Internal Waves
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作者 种劲松 李飞 欧阳越 《Journal of Measurement Science and Instrumentation》 CAS 2010年第1期37-40,共4页
Based on the research of Lynett and Liu, the horizontal fully two-dimensional, depth-integrated model for the internal wave propagation is re-deduced. By combining this model with the M4S model, the propagation proces... Based on the research of Lynett and Liu, the horizontal fully two-dimensional, depth-integrated model for the internal wave propagation is re-deduced. By combining this model with the M4S model, the propagation process of the internal waves is simulated in Synthetic Aperture Radar (SAR) images. The simulation results clearly show the bottom effects during the propagation such as fission and isobaths-parallelized propagation direction. This simulation procedure can lay the foundation for the quantitative interpretation of internal waves from fully two-dimensional SAR images. 展开更多
关键词 SAR image simulation internal waves
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A Reynolds mass flux model for gas separation process simulation:Ⅰ. Modeling and validation 被引量:2
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作者 李文彬 余国琮 +1 位作者 袁希钢 刘伯潭 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第7期1085-1094,共10页
Separation process undertaken in packed columns often displays anisotropic turbulent mass diffusion. The anisotropic turbulent mass diffusion can be characterized rigorously by using the Reynolds mass flux(RMF) model.... Separation process undertaken in packed columns often displays anisotropic turbulent mass diffusion. The anisotropic turbulent mass diffusion can be characterized rigorously by using the Reynolds mass flux(RMF) model.With the RMF model, the concentration and temperature as well as the velocity distributions can be simulated numerically. The modeled Reynolds mass flux equation is adopted to close the turbulent mass transfer equation,while the modeled Reynolds heat flux and Reynolds stress equations are used to close the turbulent heat and momentum transfer equations, so that the Boussinesq postulate and the isotropic assumption are abandoned. To validate the presented RMF model, simulation is carried out for CO2 absorption into aqueous Na OH solutions in a packed column(0.1 m id, packed with 12.7 mm Berl saddles up to a height of 6.55 m). The simulated results are compared with the experimental data and satisfactory agreement is found both in concentration and temperature distributions. The sequel Part II extends the model application to the simulation of an unsteady state adsorption process in a packed column. 展开更多
关键词 Mathematical modelingComputational fluid dynamics (CFD)Computational mass transfer (CMT)Anisotropic turbulent mass diffusionPacked bedAbsorption
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A Reynolds mass flux model for gas separation process simulation:Ⅱ.Application to adsorption on activated carbon in a packed column 被引量:2
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作者 李文彬 余国琮 +1 位作者 袁希钢 刘伯潭 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第8期1245-1255,共11页
Simulations of adsorption process using the Reynolds mass flux model described in Part I of these serial articles are presented. The object of the simulation is the methylene chloride adsorption in a packed column(0.0... Simulations of adsorption process using the Reynolds mass flux model described in Part I of these serial articles are presented. The object of the simulation is the methylene chloride adsorption in a packed column(0.041 m id,packed with spherical activated carbon up to a length of 0.2 m). With the Reynolds mass flux model,breakthrough/regeneration curves, concentration and temperature as well as the velocity distributions can be obtained. The simulated results are compared with the experimental data reported in the literature and satisfactory agreement is found both in breakthrough/regeneration curves and temperature curves. Moreover,the anisotropic turbulent mass diffusion is characterized and discussed. 展开更多
关键词 Simulation Adsorption Mass transfer Anisotropic turbulent mass diffusion Packed bed
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The first time observations of low-latitude ionospheric irregularities by VHF radar in Hainan 被引量:16
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作者 NING BaiQi HU LianHuan +2 位作者 LI GuoZhu LIU LiBo WAN WeiXing 《Science China(Technological Sciences)》 SCIE EI CAS 2012年第5期1189-1197,共9页
Sanya VHF radar (18.4°N, 109.6°E, dip latitude 12.8°N) at Hainan Island is the first coherent backscatter radar for sounding low-latitude ionospheric irregularities in the mainland of China. In this p... Sanya VHF radar (18.4°N, 109.6°E, dip latitude 12.8°N) at Hainan Island is the first coherent backscatter radar for sounding low-latitude ionospheric irregularities in the mainland of China. In this paper, we present the first results of low-latitude iono- spheric E and F region irregularities using the radar data during the period from February 2009 to March 2010. The Doppler velocity of radar echoes from E region field aligned irregularities (FAIs) was about several tens of meters per second, while the Doppler spectral width was appreciably larger than the velocity, and could reach one hundred meters per second, indicating that the observed E region FAls belonged to type 2 irregularities. The observations of range time intensity (RTI) maps of FAIs showed that E region irregularities most often occurred at night within the altitude range 85-115 kin, and were rarely observed at afternoon hours. The percentage occurrence of E region FAIs maximized during spring months (Feb.-May) with a peak value over 80%. The heights at which the strongest echo related FAIs occurred were mainly around 100 kin, lower than h'Es and the difference is mostly 10-20 km. December solstice seemed to be the minimum period of occurrence when the FA! ech- oes were commonly detected at a narrow altitude range 90-100 km. Moreover, simultaneous radar and GPS observations dur- ing spread F events in the pre-midnight hours of solar minimum revealed that significant GPS L band scintillations coincided with the appearance of F region plasma plume structures, which extended up to 450 km in altitude. 展开更多
关键词 low-latitude ionosphere ionospheric irregularities VHF radar
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Interspecific comparison of the flight performance between sparrowhawks and common buzzards migrating at the Falsterbo peninsula: A radar study 被引量:4
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作者 Gintaras MALMIGA Cecilia NILSSON Johan BACKMAN Thomas ALERSTAM 《Current Zoology》 SCIE CAS CSCD 2014年第5期670-679,共10页
In order to compare the two species' flight performance over the exposed and windy Falsterbo Peninsula, where thermal conditions seldomly are very favorable, we used tracking radar to study flight parameters of sparr... In order to compare the two species' flight performance over the exposed and windy Falsterbo Peninsula, where thermal conditions seldomly are very favorable, we used tracking radar to study flight parameters of sparrowhawks Accipiter ni- sus and common buzzards Buteo buteo during autumn migration. The results showed a clear difference between sparrowhawks and common buzzards in their flight altitudes and speeds, and in the wind conditions they encountered. Common buzzards had higher flight altitudes and were more selective of wind. Flight altitude was negatively related to the wind speed, which was most pronounced for common buzzards. Sparrowhawks had higher mean air- and cross-country speeds than common buzzards. Air- speed was negatively related, whereas ground and cross-country speeds were positively related to the tailwind component for both raptors. The differences between sparrowhawks and buzzards could to a large degree be explained by a larger dependence on thermal soaring among the common buzzards; a strategy associated with selectivity for favourable thermal and wind conditions during migratory flight. An additional important explanation for the interspecific differences was the habit of the sparrowhawks to combine migratory flight with hunting for prey, which makes it prone to fly at lower altitudes and use flapping flight to a much larger degree than common buzzards which do not forage during their migratory passage of the Falsterbo Peninsula [Current Zoo- logy 60(5): 670-679, 2014]. 展开更多
关键词 Tracking radar Raptor migration Sparrowhawk Common buzzard Flight performance Interspecific comparison Falsterbo peninsula
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Effects of Freestream Turbulence on Bypass Transition of Separated Boundary Layer on Low-Pressure Turbine Airfoils
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作者 Hideo Taniguchi Hiroshi Sakai Ken-ichi Funazaki 《Journal of Thermal Science》 SCIE EI CAS CSCD 2012年第3期230-235,共6页
This paper presents experimental studies on bypass transition of separated boundary layer on low-pressure turbine airfoils,focusing on the effects of freestream turbulence on the transition process.Hot-wire probe meas... This paper presents experimental studies on bypass transition of separated boundary layer on low-pressure turbine airfoils,focusing on the effects of freestream turbulence on the transition process.Hot-wire probe measurements are performed on the suction side of an airfoil in the low-pressure linear turbine cascade at several Reynolds number conditions.Freestream turbulence is enhanced by use of turbulence grid located upstream of the cascade.The results of this experimental study show that the location of boundary layer separation does not strongly de-pend on the freestream turbulence level.However,as the freestream turbulence level increases,the size of separa-tion bubble becomes small and the location of turbulent transition moves upstream.The size of separation bubble becomes small as the Reynolds number increases.At low freestream turbulence intensity,the velocity fluctuation due to Kelvin-Helmholtz instability is observed clearly in the shear layer of the separation bubble.At high frees-tream turbulence intensity,the streak structures appear upstream of the separation location,indicating bypass transition of attached boundary layer occurs at high Reynolds number. 展开更多
关键词 AEROENGINE Low-Pressure Turbine Bypass Transition Separation Bubble
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