基于相干布局囚禁(CPT)现象研制的原子钟与传统原子钟相比,能够提供更高的时间精度,且有利于原子钟向微型化、低功耗方向发展。在不同种类的CPT原子钟中,铷原子钟应用最为广泛,而其性能的优劣很大一部分取决于自身内部的用于提供微波信...基于相干布局囚禁(CPT)现象研制的原子钟与传统原子钟相比,能够提供更高的时间精度,且有利于原子钟向微型化、低功耗方向发展。在不同种类的CPT原子钟中,铷原子钟应用最为广泛,而其性能的优劣很大一部分取决于自身内部的用于提供微波信号源的压控振荡器(VCO)。基于此,利用高品质因数的同轴谐振器和Clapp振荡电路,首先根据负阻分析法使电路快速起振,并结合虚拟地技术对电路参数进行优化,完成了一个小体积、低相位噪声的3.035 GHz压控振荡器的设计。其相位噪声为-60.49 d Bc/Hz@300 Hz、-73.08 d Bc/Hz@1 k Hz和-97.48 d Bc/Hz@10 k Hz,压控调节灵敏度为12 MHz/V,输出信号的功率为-1.13 d Bm,满足铷原子钟的应用需求。展开更多
Aim To study wind tunnel test data interpolation methods for flight vehicle with aerodynamic axial asymmetry. Methods For different body aerodynamic roll angles, proper wind tunnel test schemes were selected and ...Aim To study wind tunnel test data interpolation methods for flight vehicle with aerodynamic axial asymmetry. Methods For different body aerodynamic roll angles, proper wind tunnel test schemes were selected and trigonometric series were used for aerodynamic interpolation. Results and Conclusion A simple and effective scheme for wind tunnel test and an accurate aerodynamic interpolation method are developed with satisfactory results.展开更多
A class of plateaued functions has been got by using the Maiorana-McFarland construction. A variety of desirable criteria for functions with cryptographic application eouht be satisfied： balancedness, high nonlineari...A class of plateaued functions has been got by using the Maiorana-McFarland construction. A variety of desirable criteria for functions with cryptographic application eouht be satisfied： balancedness, high nonlinearity, correlation immunity of reasonably high order, strict avalanche criterion, non-existence of non-zero linear struetures, good glnbal avalanche characteristics, etc.展开更多
The altitudinal pattern of vegetation is usually identified by field surveys,however,these can only provide discrete data on a local mountain.Few studies identifying and analyzing the altitudinal vegetation pattern on...The altitudinal pattern of vegetation is usually identified by field surveys,however,these can only provide discrete data on a local mountain.Few studies identifying and analyzing the altitudinal vegetation pattern on a regional scale are available.This study selected central Inner Mongolia as the study area,presented a method for extracting vegetation patterns in altitudinal and horizontal directions.The data included a vegetation map at a 1∶1 000 000 scale and a digital elevation model at a 1∶250 000 scale.The three-dimensional vegetation pattern indicated the distribution probability for each vegetation type and the transition zones between different vegetation landscapes.From low to high elevations,there were five vegetation types in the southern mountain flanks,including the montane steppe,broad-leaved forest,coniferous mixed forest,montane dwarf-scrub and sub-alpine shrub-meadow.Correspondingly,only four vegetation types were found in the northern flanks,except for the montane steppe.This study could provide a general model for understanding the complexity and diversity of mountain environment and landscape.展开更多
Existing quantitative migration studies are mainly at the inter-region or inter-province level for lacking of detailed geo-referenced migration data.Meanwhile,few of them integrate explorative spatial data analysis an...Existing quantitative migration studies are mainly at the inter-region or inter-province level for lacking of detailed geo-referenced migration data.Meanwhile,few of them integrate explorative spatial data analysis and spatial regression model into migration analysis.Based on aggregated registered floating population data from 2005 to 2008,the phenomena that population floating to Yiwu City in Zhejiang Province is analyzed at the provincial and county levels.The spatial layout of Yiwu's pull forces is proved as a V-shaped pattern excluding Sichuan Province based on map visualization method.Using the migration ratio in 2007 as an explanatory variable,two models are compared using ordinary least square,spatial error model and spatial lag model methods for county-level data in Jiangxi and Anhui provinces.The model with migration stock provides an improved fitting over the model without migration stock according to the model fitting results.The floating population flocking into Yiwu City from Jiangxi is determined mostly by migration stock while the determinant factors are migration stock and distance to Yiwu City for Anhui.The distance-decay effect is true for migration flow from Anhui to Yiwu City while the distance rule is not confirmed in Jiangxi with the best fitting model.The correlation between per capita net income of rural labor forces and migration ratio is not significant in Jiangxi and significant but at the 0.1 level only in Anhui.Further analysis shows that the distance,income and man-land ratio are important factors to explain population floating at earlier stage.However,as the dynamic population floating process evolves,the determinant factor would be migration stock.展开更多
The climate modeling community has been challenged to develop a method for improving the simulation of the Pacific-North America （PNA） teleconnection pattern in climate models. The accuracy of PNA teleconnection sim...The climate modeling community has been challenged to develop a method for improving the simulation of the Pacific-North America （PNA） teleconnection pattern in climate models. The accuracy of PNA teleconnection simulation is significantly improved by considering mesoscale convection contributions to sea surface fluxes. The variation in the PNA over the past 22 years was simulated by the Grid Atmospheric Model of lAP LASG version 1.0 （GAMIL1.0）, which was guided by observational SST from January 1979 to December 2000. Results show that heating in the tropical central-eastern Pacific is simulated more realistically, and sea surface latent heat flux and precipitation anomalies are more similar to the reanalysis data when mesoscale enhancement is considered during the parameterization scheme of sea surface turbulent fluxes in GAMIL1.0. Realistic heating in the tropical central-eastern Pacific in turn significantly improves the simulation of interannual variation and spatial patterns of PNA.展开更多
We determi：ned a suitable gate road layout in slice mining in an ultra-thick unstable coal seam, using theoretical anallysis and numerical calculations. Based on plasticity theory in terms of limiting equilibrium, th...We determi：ned a suitable gate road layout in slice mining in an ultra-thick unstable coal seam, using theoretical anallysis and numerical calculations. Based on plasticity theory in terms of limiting equilibrium, the width of chain pillar in the upper slice was calculated to be 18 m. The stress distribution in the chain pillar after the upper slice was mined out was described with numerical simulation. The extent of the effect of stress on the upper chain pillar on the lower solid coal was obtained on the basis of an elastic solution of a distributed force loaded on a half-plane. Three layout designs for lower gate roads were pro- posed and a stability factor was introduced to analyze the stability of the lower pillar with numerical calculation. Gate road translation was determined as the most suitable layout method, which maximizes the extraction rate on the basis of the pillar stability.展开更多
文摘基于相干布局囚禁(CPT)现象研制的原子钟与传统原子钟相比,能够提供更高的时间精度,且有利于原子钟向微型化、低功耗方向发展。在不同种类的CPT原子钟中,铷原子钟应用最为广泛,而其性能的优劣很大一部分取决于自身内部的用于提供微波信号源的压控振荡器(VCO)。基于此,利用高品质因数的同轴谐振器和Clapp振荡电路,首先根据负阻分析法使电路快速起振,并结合虚拟地技术对电路参数进行优化,完成了一个小体积、低相位噪声的3.035 GHz压控振荡器的设计。其相位噪声为-60.49 d Bc/Hz@300 Hz、-73.08 d Bc/Hz@1 k Hz和-97.48 d Bc/Hz@10 k Hz,压控调节灵敏度为12 MHz/V,输出信号的功率为-1.13 d Bm,满足铷原子钟的应用需求。
文摘Aim To study wind tunnel test data interpolation methods for flight vehicle with aerodynamic axial asymmetry. Methods For different body aerodynamic roll angles, proper wind tunnel test schemes were selected and trigonometric series were used for aerodynamic interpolation. Results and Conclusion A simple and effective scheme for wind tunnel test and an accurate aerodynamic interpolation method are developed with satisfactory results.
基金the National Natural Science Foundation of China，Foundation of National Laboratory for Modern Communications
文摘A class of plateaued functions has been got by using the Maiorana-McFarland construction. A variety of desirable criteria for functions with cryptographic application eouht be satisfied： balancedness, high nonlinearity, correlation immunity of reasonably high order, strict avalanche criterion, non-existence of non-zero linear struetures, good glnbal avalanche characteristics, etc.
基金Under the auspices of National Natural Science Foundation of China(No.41001111,41030528)
文摘The altitudinal pattern of vegetation is usually identified by field surveys,however,these can only provide discrete data on a local mountain.Few studies identifying and analyzing the altitudinal vegetation pattern on a regional scale are available.This study selected central Inner Mongolia as the study area,presented a method for extracting vegetation patterns in altitudinal and horizontal directions.The data included a vegetation map at a 1∶1 000 000 scale and a digital elevation model at a 1∶250 000 scale.The three-dimensional vegetation pattern indicated the distribution probability for each vegetation type and the transition zones between different vegetation landscapes.From low to high elevations,there were five vegetation types in the southern mountain flanks,including the montane steppe,broad-leaved forest,coniferous mixed forest,montane dwarf-scrub and sub-alpine shrub-meadow.Correspondingly,only four vegetation types were found in the northern flanks,except for the montane steppe.This study could provide a general model for understanding the complexity and diversity of mountain environment and landscape.
基金Under the auspices of National Natural Science Foundation of China(No.41001314)Youth Science Funds of State Key Laboratory of Resources and Environmental Information System,Chinese Academy of Sciences(No.KA11040101)National Key Technology R&D Program of China(No.2012BAI32B07)
文摘Existing quantitative migration studies are mainly at the inter-region or inter-province level for lacking of detailed geo-referenced migration data.Meanwhile,few of them integrate explorative spatial data analysis and spatial regression model into migration analysis.Based on aggregated registered floating population data from 2005 to 2008,the phenomena that population floating to Yiwu City in Zhejiang Province is analyzed at the provincial and county levels.The spatial layout of Yiwu's pull forces is proved as a V-shaped pattern excluding Sichuan Province based on map visualization method.Using the migration ratio in 2007 as an explanatory variable,two models are compared using ordinary least square,spatial error model and spatial lag model methods for county-level data in Jiangxi and Anhui provinces.The model with migration stock provides an improved fitting over the model without migration stock according to the model fitting results.The floating population flocking into Yiwu City from Jiangxi is determined mostly by migration stock while the determinant factors are migration stock and distance to Yiwu City for Anhui.The distance-decay effect is true for migration flow from Anhui to Yiwu City while the distance rule is not confirmed in Jiangxi with the best fitting model.The correlation between per capita net income of rural labor forces and migration ratio is not significant in Jiangxi and significant but at the 0.1 level only in Anhui.Further analysis shows that the distance,income and man-land ratio are important factors to explain population floating at earlier stage.However,as the dynamic population floating process evolves,the determinant factor would be migration stock.
基金jointly supported by the National Natural Science Foundation of China under Grants 40905045 and 40821092the Open Project for LASG-IAP-CAS+2 种基金the Study Project of Jiangsu Provincial 333 High-level Talents Cultivation Programmethe Foundation of Key Laboratory of Meteorological Disaster of Ministry of Education under Grant KLME05001the Project Funded by the Priority Academic Programme Development of Jiangsu Higher Education Institutions
文摘The climate modeling community has been challenged to develop a method for improving the simulation of the Pacific-North America （PNA） teleconnection pattern in climate models. The accuracy of PNA teleconnection simulation is significantly improved by considering mesoscale convection contributions to sea surface fluxes. The variation in the PNA over the past 22 years was simulated by the Grid Atmospheric Model of lAP LASG version 1.0 （GAMIL1.0）, which was guided by observational SST from January 1979 to December 2000. Results show that heating in the tropical central-eastern Pacific is simulated more realistically, and sea surface latent heat flux and precipitation anomalies are more similar to the reanalysis data when mesoscale enhancement is considered during the parameterization scheme of sea surface turbulent fluxes in GAMIL1.0. Realistic heating in the tropical central-eastern Pacific in turn significantly improves the simulation of interannual variation and spatial patterns of PNA.
基金provided by the Research Fund of the Fundamental Research Funds for the Central Universities of China University of Mining & Technology (No. 2010ZDP02B02)the State Key Laboratory of Coal Resources and Mine Safety (No.SKLCRSM08X2)+2 种基金the Jiangsu "333"High Qualified Talentsthe National Natural Science Foundation of China (Nos. 50904063 and51004101)the Scientific Research Foundation of China University of Mining & Technology (Nos. 2008A003 and 2009A001)
文摘We determi：ned a suitable gate road layout in slice mining in an ultra-thick unstable coal seam, using theoretical anallysis and numerical calculations. Based on plasticity theory in terms of limiting equilibrium, the width of chain pillar in the upper slice was calculated to be 18 m. The stress distribution in the chain pillar after the upper slice was mined out was described with numerical simulation. The extent of the effect of stress on the upper chain pillar on the lower solid coal was obtained on the basis of an elastic solution of a distributed force loaded on a half-plane. Three layout designs for lower gate roads were pro- posed and a stability factor was introduced to analyze the stability of the lower pillar with numerical calculation. Gate road translation was determined as the most suitable layout method, which maximizes the extraction rate on the basis of the pillar stability.
