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401.
朝鲜人口统计数据空间化是解决朝鲜统计数据与自然要素数据融合分析的重要途径。基于朝鲜市郡级人口普查数据,将GIS空间分析技术与统计学方法相结合,分析了朝鲜人口密度与空间因子的关系,采用多元回归的方法建立了朝鲜人口密度空间化模型,在GIS平台中实现了朝鲜人口密度的空间格网化模拟,并利用地理探测器对影响朝鲜人口密度空间分布因素的决定力进行了有效探测。结果表明,多元回归模型拟合精度达到0.769,生成的栅格人口密度数据与朝鲜三级行政区人口统计数据保持一致。同时,影响该地区人口密度的因子依次为道路网密度、居民点密度、居民地指数、海拔、坡度和耕地指数。 相似文献
402.
Ezio Caroli Rui M. Curado da Silva Alessandro Pisa John B. Stephen Filippo Frontera Matilde T. D. Castanheira Stefano del Sordo 《Experimental Astronomy》2005,20(1-3):353-364
Polarimetry is an area of high energy astrophysics which is still relatively unexplored, even though it is recognized that this type of measurement could drastically increase our knowledge of the physics and geometry of high energy sources. For this reason, in the context of the design of a Gamma-Ray Imager based on new hard-X and soft gamma ray focusing optics for the next ESA Cosmic Vision call for proposals (Cosmic Vision 2015-2025), it is important that this capability should be implemented in the principal on-board instrumentation. For the particular case of wide band-pass Laue optics we propose a focal plane based on a thick pixelated CdTe detector operating with high efficiency between 60–600keV. The high segmentation of this type of detector (1–2mm pixel size) and the good energy resolution (a few keV FWHM at 500keV) will allow high sensitivity polarisation measurements (a few % for a 10mCrab source in 106s) to be performed. We have evaluated the modulation Q factors and minimum detectable polarisation through the use of Monte Carlo simulations (based on the GEANT 4 toolkit) for on and off-axis sources with power law emission spectra using the point spread function of a Laue lens in a feasible configuration. 相似文献
403.
研究在鱼鲜酱油的酿制中 ,采用鱼肉液体制曲提高蛋白利用率并利用制曲过程去除鱼腥味。探讨了制曲温度、制曲时间、种曲添加量对鱼肉液体制曲的影响 ,分析了液体曲的蛋白酶活力和制曲过程对鱼腥物质三甲胺 (TMA)的消除情况。结果表明 ,制曲温度为 40℃ ,制曲时间为 2 4h ,种曲添加量 0 4%为最佳制曲条件 ,此时 ,液体曲的蛋白酶活力为 2 45Iu/mL ,制曲过程对三甲胺的去除率可达 74 7%。 相似文献
404.
405.
We calculated the expected neutrino signal in Borexino from a typical Type II supernova at a distance of 10 kpc. A burst of around 110 events would appear in Borexino within a time interval of about 10 s. Most of these events would come from the reaction channel
, while about 30 events would be induced by the interaction of the supernova neutrino flux on 12C in the liquid scintillator. Borexino can clearly distinguish between the neutral-current excitations 12C(ν,ν′)12C* (15.11 MeV) and the charged-current reactions 12C(νe,e−)12N and
, via their distinctive event signatures. The ratio of the charged-current to neutral-current neutrino event rates and their time profiles with respect to each other can provide a handle on supernova and non-standard neutrino physics (mass and flavor oscillations). 相似文献
406.
P.K. Lightfoot N.J.C. Spooner T.B. Lawson S. Aune I. Giomataris 《Astroparticle Physics》2007,27(6):490-499
A bulk micromegas micropattern charge readout device has, for the first time, been operated at room temperature in low pressure carbon disulphide vapour. This is a key step opening prospects for use of micromegas readout for large volume negative ion time projection chambers (TPCs) without magnets, such as proposed for directional dark matter detectors and other rare event applications. The dependence of the gain on the amplification field, pressure and drift field has been evaluated. For the available gap size of 75 μm a maximum gain of 1300 ± 120 was achieved in 40 torr vapour with an energy resolution of 22% for 5.9 keV 55Fe X-rays. From a fit to the data, the Townsend coefficient gas parameters A and B have been derived. Operation has also been successfully achieved in xenon:carbon disulphide blends over a range of partial and total pressures. A gain of 890 ± 130 at an energy resolution of 35% has been recorded for a 1:1 blend at a total pressure of 80 torr. Possible improvements are discussed in the context of operation in directional dark matter TPCs as a replacement for multi-wire proportional counters. 相似文献
407.
中国村庄空间分布特征及空间优化重组解析 总被引:18,自引:6,他引:12
以中国电子地图数据和分县经济社会数据为基础,利用最邻近距离R指数模型分析中国村庄分布模式格局,结合地理探测器的研究方法对影响因素进行探测识别,同时解析乡村空间优化重组背景和模式。研究得出以下主要结论:① 中国村庄空间分布呈现出聚集、随机、离散均匀分布的并存空间分布模式,村庄空间分布模式区域差异特征显著。东南半壁的村庄分布密度远大于西北半壁,不同地域类型区的村庄空间分布模式表现出各异的特征。平原地区的村庄空间分布密集,空间分布模式以随机、分散为主,村庄之间邻近距离较近。高寒山区、沙漠边缘地带,村庄空间分布密度极低,村庄之间邻近距离偏大,村庄空间分布相对聚集。丘陵、山地交汇过渡地带,村庄空间分布密度较大,空间分布模式偏向随机分布。② 村庄分布受到传统因素和经济发展双重因子的影响,传统影响因素依然在发挥作用,但经济发展的影响愈加明显。不同区域地形、水资源条件对村庄分布影响显著。交通条件、产业非农化、经济发展、农业现代化发展对乡村生活、生产空间的空间形态和分布模式产生剧烈影响。③ 伴随乡村各种生产要素非农化流失,村庄空间亟待优化重组,优化以镇区为依托的中心村-基层村体系空间组织结构应为乡村物质空间优化重组有效选择。④ 在不同地域类型区域,村镇格局的空间优化重组形态可以采用放射均衡、放射非均衡、多核心均衡、走廊式布局模式及混合模式。 相似文献
408.
We aim to relate the morphology of the pore network of finely porous claystones to their fluid transport properties. By using Focused Ion Beam in combination with Scanning Electron Microscopy (FIB/SEM), we image the pore network of COx claystone from 2D image stacks and as 3D reconstructed volumes. Our FIB/SEM samples are representative of the mesoscopic matrix clay. Porosity resolvable by this technique is in the range 1.7–5.9% with peak pore sizes of 50–90 nm. 3D pore network skeletonization provides connected pore volumes between end surfaces, tortuosity, density, and shortest pore paths with their pore size distribution. At higher resolution, 2D transmission electron microscopy (TEM) reveals large amounts of smaller pores (2–20 nm) between clay aggregates, associated to a local porosity of 14–25%, and peak sizes of 4–6 nm. Liquid permeability predictions with Katz–Thompson model, at the FIB/SEM volume scale and at the TEM surface scale, are in good agreement with macroscopic measurements (on the order of 10−20 m2), showing that both mesopore sizes (peaks at 50–90 nm and 4–6 nm), located within the clay matrix, contribute to liquid transport. 相似文献
409.
410.
Wang Yiming Zhang Yingying Wu Ning Wu Bingwei Liu Yan Cao Xuan Wang Qian 《中国海洋大学学报(英文版)》2015,14(3):471-474
To develop a Na I(Tl) detector for in situ radioactivity monitoring in the marine environment and enhance the confidence of the probability of the gamma-spectrum analysis, Monte Carlo simulations using the Monte Carlo N-Particle( MNCP) code were performed to provide the response spectra of some interested radionuclides and the background spectra originating from the natural radionuclides in seawater recorded by a Na I(Tl) detector. A newly developed 75 mm × 75 mm Na I(Tl) detector was calibrated using four reference radioactive sources 137 Cs, 60 Co, 40 K and 54 Mn in the laboratory before the field measurements in seawater. A simulation model was established for the detector immersed in seawater. The simulated spectra were all broadened with Gaussian pulses to reflect the statistical fluctuations and electrical noise in the real measurement. The simulated spectra show that the single-energy photons into the detector are mostly scattering low-energy photons and the high background in the low energy region mainly originates from the Compton effect of the high energy γ-rays of natural radionuclides in seawater. The simulated background spectrum was compared with the experimental one recorded in field measurement and they seem to be in good agreement. The simulation method and spectra can be used for the accurate analysis of the filed measurement results of low concentration radioactivity in seawater. 相似文献