Projectile fragmentation of Kr-86 at 64 MeV/nucleon

We measured fragmentation cross sections produced using the primary beam of Kr-86 at 64 MeV/nucleon on Be-9 and Ta-181 targets. The cross sections were obtained by integrating the momentum distributions of isotopes with 25 <= Z <= 36 measured using the RIPS fragment separator at RIKEN. The cross-section ratios obtained with the Ta-181 and Be-9 targets depend on the fragment masses, contrary to the simple geometrical models. We compared the extracted cross sections to EPAX; an empirical parametrization of fragmentation cross sections. Predictions from current EPAX parametrization severely overestimate the production cross sections of very neutron-rich isotopes. Attempts to obtain another set of EPAX parameters specific to the reaction studied here to extrapolate the neutron-rich nuclei more accurately have not been very successful, suggesting that accurate predictions of production cross sections of nuclei far from the valley of stability require information of nuclear properties that are not present in EPAX.

64通道一维位置灵敏电流分布探测器及其数据获取系统；A 64-Channel Position Sensitive Current Distribution Detector with Data Acquisition System

针对高流强粒子束与绝缘毛细管相互作用的特点,设计制作了一套64通道一维位置灵敏电流分布探测器及其配套的数据获取系统,该探测器可分辨最小直径为1mm的束斑,通过数据获取系统可实现可视化自动数据采集。用2nA和200—2000eV电子对探测器进行了定标,并用10μA和2000eV的电子束穿越锥形毛细管后的出射电子,对探测器及数据获取系统进行测试,获得了出射粒子的位置分布谱及能量信息。

（一）兰州重离子加速器束流能量、能散测量（二）中能~(12)C + ~(64)Ni, ~(58)Ni碎裂反应的实验研究

本论文通过讨论选择了简单易行的弹性散射法来测量兰州重离子加速器流能量、能散，描述了整个实验的准备、进行及数据处理，并讨论、修正了所得的实验结果，得到了~(12)C束流能散为(2.74 ± 0.14) * 10~(-2)，能量经刻度为每核子46.4MeV/u。本工作还拟采用飞行时间法来测量束流能量的绝对值，以检验弹性散射法测得的能量值，而且已设计制作了用作起始探测器的微道板（MCP）零时探测器，上器进行了必要的高调试，用MCP零时探测器作为起始探测器，Si半导体探测器作为终止探测器，对于10MeV/uα粒子，得到了好于560ps的总时间分辩，完全可用于中能重离子实验探测

GIS支持下岷江上游土壤侵蚀动态研究

利用TM数据,采用3S技术和通用土壤侵蚀方程(RUSLE)研究岷江上游地区3个典型时期的土壤侵蚀动态,并对影响侵蚀的主要因子进行初步分析.结果表明,研究区3个时期侵蚀面积分别占研究区总面积的1.28%、1.84%和1.70%;年平均侵蚀模数分别为832.64、1048.74和1362.11t.km-2,以微度侵蚀、轻度侵蚀为主,伴有少量的中度侵蚀.侵蚀面积比较小,侵蚀程度比较轻.侵蚀与坡度呈显著正相关,侵蚀大多发生在>25°的区域,1986年占总侵蚀量的93.65%,1995年为93.81%,2000年为92.71%;在海拔上,中山、亚高山、高山以及干旱河谷是侵蚀发生的主要地带,1986年占总侵蚀量的98.21%,1995年为97.63%,2000年为99.27%;不同类型的植被直接影响到侵蚀的发生,灌木林地以及新退耕的疏林地是3个时期侵蚀的主要发生地,过度放牧导致草场退化,也产生了微度侵蚀;侵蚀的发生和土壤类型密切相关,燥褐土、石灰性褐土最易发生侵蚀,是控制侵蚀的重点区域;人口的增长、户数的增加是侵蚀发生的驱动因子,人口与户数增长导致资源需求压力的增大,侵蚀呈线性增加.

基于TM的渤海海岸带1988~2000年生态环境变化

海岸带作为海陆之间的过渡地带,是全球生态环境最为复杂和特殊之处。研究海岸带土地利用变化对于了解该区域生态环境演变具有重要意义。利用1988和2000年的Landsat-TM数据,在GIS技术支持下,通过一系列空间分析,得到渤海海岸带土地利用/土地覆盖变化,结合社会经济统计资料分析该区域生态环境的动态变化情况及其驱动因素。结果表明,1988~2000年,由于渤海海岸带社会经济的快速发展,海岸带土地利用格局发生了巨大的变化。耕地大面积减少,城乡工矿用地、养殖池塘、盐田急剧扩张;林地、湿地等具有重要生态价值的土地类型面积显著下降。表明强烈的人类活动已经使自然生态系统受到破坏,渤海海岸带生态环境质量总体上呈现下降趋势。

基于TM影像的表层土壤有机碳空间格局

土壤有机碳是土壤肥力的核心指标之一,理解其空间分布格局对促进精准农业的发展和科学施肥具有重要意义。本研究旨在检验TM影像结合地面采样数据分析黑龙江省黑土分布区表层土壤有机碳空间分布格局的可行性。结果表明:1)表层土壤有机碳浓度与TM5波段呈显著正相关(r=0.553,P<0.01),与TM4、TM5波段影像像素值之间满足二次多项式回归关系(R2=0.6791,P<0.05);2)回归模型对表层土壤有机碳空间分布格局具有较好的预测效果(R2=0.7097,P<0.05);3)海拔高于200m的地区表层土壤有机碳浓度显著高于海拔低于200m的地区(P<0.05)。

基于TM影像和统计分析的林分参数估测研究(英文)

林业研究中的主要兴趣点之一在于通过经验或半经验模型建立林分参数与遥感影像数据间的相互关系来估测林分参数。基于覆盖美国佛罗里达州东北Duval县的遥感数据和两块样地清查数据,论文探讨了所选林分参数与TM影像光谱DN值间的相关性。相关性分析结果表明,单波段或植被指数对林分参数的解释能力低于50%,为此构建了林分参数与影像多波段间多元回归模型来估测林分参数。预测结果通过另一组数据验证,除林分密度外,其它参数估测可信度达75%以上。论文最后探讨了预测模型不足和需改进的地方,并指出该研究有助于更好地理解影像光谱值和林分参数间的关系。图1表2参9。

基于决策树的科尔沁沙地土地利用/覆盖变化监测

以科尔沁沙地西缘内蒙古翁牛特旗为对象,利用3个时相(1989、1999和2007年,分别表示三北防护林体系工程建设近10年、20年和30年)Landsat ETM/TM数据,采用决策树分类方法对该区土地利用/覆盖动态变化进行监测。结果表明:基于决策树分类方法进行遥感影像分类的总体精度能达到89.4%以上,Kappa系数达到0.84以上;近20年,草地和耕地是主要土地利用类型(两项合计占64%以上),林业用地比重为4.8%~5.3%,面积较少;各土地类型面积变化大小依次为耕地>未利用土地>林地>居民及建设用地>水域>草地。

Analysis of spatio-temporal dynamic pattern and driving forces of urban land in China in 1990s using TM images and GIS

China has witnessed fast urban growth in the recent decade. This study analyzes spatio-temporal characteristics of urban expansion in China using satellite images and regionalization methods. Landsat TM images at three time periods, 1990/1991, 1995/1996, and 1999/2000, are interpreted to get 1:100000 vector land use datasets. The study calculates the urban land percentage and urban land expansion index of every 1 km(2) cell throughout China. The study divides China into 27 urban regions to conceive dynamic patterns of urban land changes. Urban development was achieving momentum in the western region, expanding more noticeably than in the previous five years, and seeing an increased growth percentage. Land use dynamic changes reflect the strong impacts of economic growth environments and macro-urban development policies. The paper helps to distinguish the influences of newly market-oriented forces from traditional administrative controls on China's urban expansion. (c) 2005 Elsevier Ltd. All rights reserved.

Uncertainties in estimates of cropland area in China: a comparison between an AVHRR-derived dataset and a Landsat TM-derived dataset

The large uncertainties in estimates of cropland area in China may have significant implications for major cross-cutting themes of global environmental change-food production and trade, water resources, and the carbon and nitrogen cycles. Many earlier studies have indicated significant under-reporting of cropland area in China from official agricultural census statistics datasets. Space-borne remote sensing analyses provide an alternative and independent approach for estimating cropland area in China. In this study, we report estimates of cropland area from the National Land Cover Dataset (NLCD-96) at the 1:100,000 scale, which was generated by a multi-year National Land Cover Project in China through visual interpretation and digitization of Landsat TM images acquired mostly in 1995 and 1996. We compared the NLCD-96 dataset to another land cover dataset at I-km spatial resolution (the IGBP DIScover dataset version 2.0), which was generated from monthly Advanced Very High Resolution Radiometer (AVHRR)-derived Normalized Difference Vegetation Index (NDVI) from April, 1992 to March, 1993. The data comparison highlighted the limitation and uncertainty of cropland area estimates from the DIScover dataset. (C) 2003 Elsevier Science B.V. All rights reserved.

Synthesis and Luminescent Properties of LaAlO3:RE3+ (RE = Tm, Tb) Nanocrystalline Phosphors via a Sol-Gel Process

LaAlO3:Tm3+ and LaAlO3:Tb3+ phosphors were prepared through a Pechini-type sol-gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence, and cathodoluminescence (CL) spectra were utilized to characterize the synthesized phosphors. The XRD results reveal that the fully crystalline pure LaAlO3 Phase can be obtained at 800 degrees C. The FE-SEM image indicates that the phosphor samples are composed of aggregated spherical particles with sizes ranging from 40 to 80 nm. Under the excitation of ultraviolet light (230 nm) and low-voltage electron beams (1-3 kV), the LaAlO3:Tm3+ and LaAlO3:Tb3+ phosphors show the characteristic emissions of Tb3+ (D-1(2)-> H-3(6,4),F-3(4) transitions) and Tm3+ (D-5(3,4)-> F-7(6,5,4,3) transitions) respectively. The CL of the LaAlO3:Tm3+ phosphors have high color purity and comparable intensity to the Y2SiO5:Ce3+ commercial product, and the CL colors of Tb3+-doped LaAlO3 phosphors can be tuned from blue to green by changing the doping concentration of Tb3+ to some extent.