城郊耕层土壤养分的空间变异特征

以广州郊区岑村为例,采用G IS与地统计学相结合的方法对城郊耕层土壤(0~20cm)的有机质、全N、全P和全K4种土壤养分要素的空间变异特征进行了分析。结果表明:有机质、全N和全K变异函数曲线的最优理论模型为指数模型;全P为球状模型。几种土壤养分具有很强的空间相关性,异质性特征。各土壤养分由随机因素引起的空间变异占空间总变异的比例小,其值分别为9.90%、8.80%、0.26%和17.10%。说明受母质、地形、土壤类型等自然的结构性因素影响较大。土壤特性的相关距变化范围为139.00~750.00m。该成果可为城郊农业的定位施肥、灌溉以及其它的农田精细管理提供依据。     

黑龙江省双城市土壤有机质和速效养分的空间变异特征

采用地理信息系统(G IS)和地统计学相结合的方法研究了黑龙江省双城市土壤表层(0~20 cm)有机质、速效氮、速效磷、速效钾这4种土壤养分指标的空间变异性。结果表明:土壤有机质、速效氮、速效钾的理论模型均为球状模型;速效磷的理论模型为指数模型。速效钾含量的C0/(C0 C)为49.96%,存在中等的空间相关性,说明其空间变异是由随机性因素和结构性因素共同作用的结果;速效氮、有机质、速效磷含量的C0/(C0 C)变化范围是8.10%~14.39%,均表现出强的空间相关性,说明其空间变异均受结构性因素的影响。从总体分布趋势来看,4项养分指标均呈现出由西向东、由西南向东北升高的趋势。     

宁夏不同地区农田土壤磷素养分的空间变异特征

在宁夏灌区和旱区30块农田分别采集了0~120 cm深土壤剖面样品,测定了土壤全磷和速效磷含量,分析了土壤磷素养分含量的空间变异性。结果表明,在0~120 cm深土壤剖面中的全磷和速效磷含量,灌区土壤显著高于旱区土壤,在剖面点之间和土壤层次之间存在极显著差异,而且在土层间还存在着正相关。其变异系数总体上是旱区土壤大于灌区土壤,速效磷大于全磷。从地区来看,旱区土壤全磷和速效磷含量的变异系数随剖面深度的增加而增大,灌区土壤全磷量的变异系数在剖面层次之间差别不大,而速效磷的变异系数随剖面深度的增加而呈降低趋势。在0~120 cm深土壤剖面中,土壤全磷和速效磷的累积量灌区较旱区分别高出26.8%和65.0%,在土类间也存在较大差异。     

河南开封土壤养分变化特征及其持续利用途径研究

通过 1 984～ 1 998年河南开封不同土壤耕层有机质与氮磷钾养分分析 ,论述了不同农业利用方式和农田管理措施下不同土壤耕层养分的时空变化特征和硝态氮累积特性 .由于“重氮磷 ,轻有机肥 ,忽视钾素补给” ,土壤养分变化的总趋势以下降 ,钾素耗竭性明显 .土壤养分空间变化较为复杂 ,但不同土壤间耕层养分为普通淡色潮湿雏形土 >底锈干润雏形土 >石灰淡色潮湿雏形土 >灌淤旱耕人为土 >简育干润雏形土 >干润砂质新成土 .硝态氮累积表现为由上至下递减或由上至下递增和相对积累于土体某一深度 .最后研究提出了土壤持续利用的有效技术途径 .     

西安市郊区日光温室大棚番茄施肥现状及土壤养分累积特性

调查了西安市郊区100余个日光温室栽培番茄的施肥现状,并采集了60个日光温室土壤剖面样品,测定了土壤养分及盐分含量。结果表明,当地番茄的氮磷钾化肥的平均施用量分别为N 600 kg hm-2,623 kg P2O5hm-2和497 kgK2O hm-2。过量施肥特别是过量施用磷肥比较普遍。日光温室土壤0~20 cm和20~40 cm土层有机质、有效磷、速效钾含量均明显高于露地。不同地点日光温室土壤0~100 cm土层硝态氮含量及土壤电导率存在差别,但其含量均高于露地土壤,其中日光温室土壤0~100 cm土层硝态氮含量较露地的增加幅度在127%~433%之间。由于研究地区土壤多发育在河流冲积物上,地下水位埋藏浅,土壤质地相对较粗,因此,不合理施肥引起的土壤养分累积及损失,以及由此带来的环境问题值得关注。     

贵州省植烟区土壤pH值和养分空间变异特征的研究

应用地统计学的方法结合GIS空间分析技术,对贵州省植烟区土壤pH值和速效养分区域采集了3309个耕层(0～20cm)土壤样本进行了数据处理,并对其pH值、有机质、速效氮、速效磷和速效钾含量的空间分异特征进行了研究和探讨。结果表明,贵州省土壤养分pH值、有机质、速效氮、速效磷和速效钾半方差函数曲线的理论模型中,pH值和速效磷为球形(Spherical),有机质、速效氮和速效钾为高斯(Gaussion)。pH值、速效氮和速效磷具有强烈的空间相关性,块金值/基台值小于25%,其变化主要受结构性因子的影响;有机质空间相关性也较强,速效钾具有中等的空间相关性,块金值/基台值在25%～75%之间,其变化主要受随机性因子的影响。利用地统计学分析的方法,对贵州省烟叶种植具有重要的意义。     

黄土区村级农田土壤养分空间变异特征研究

本研究选择黄土高原地区陕西省新集村为研究对象。在219hm2耕地上用网格法采集364个表层(0~20 cm)土壤,研究了该村土壤pH,有机质和速效养分(N,P,K,Ca,Mg,S)空间变异性。结果表明:该村98.9%耕地缺N,缺K,缺P比例占11.5%和4.4%。地统计学分析结果表明:土壤有机质、有效N、P、K、Mg、Ca、S具有中等的空间相关性,空间变异程度依次为:OM>P>Ca>K>Mg>N>S,土壤pH的空间相关性很弱。有机质、有效N、S最大相关距离大,达到1853m,pH值最小,为148m,K、Ca、P、Mg最大相关距离分别为717m、720m、1032m和1344m。施肥是导致该村土壤养分空间变异性的主要原因。基于土壤养分状况和空间分布特征,目前仅需要考虑对该村土壤K,P进行分区管理。     

土壤团聚体形成与稳定机制及影响因素

土壤团聚体是土壤的重要组成部分、土壤结构的基本单位,其形成和稳定主要是通过土壤中各种胶结物质的胶结作用实现的。土壤团聚体的形成和稳定过程是十分复杂的,不仅是自然条件的影响,而且还受到人为活动的严重影响,主要有土壤有机质、土壤微生物、土地利用方式变化和耕作干扰。土壤团聚体还影响土壤养分,尤其是碳氮磷。     

海伦县土壤重金属含量的空间变异性研究

兼顾土壤类型和相对均匀性的前提下,在黑龙江省海伦县中部地区采集黑土土壤样品60个(0-20cm),在GIS的支持下,采用经典统计学与地统计学相结合的方法研究了土壤铜、铬、铅、镉、汞、砷含量的空间变异性及分异规律。结果表明,就空间相关域而言,铜含量的空间变异性比铬要大;铅、镉、汞、砷含量存在很好的空间结构性,趋势项可用一次趋势面方程分离,一次趋势面方程代表了这四种元素的宏观分布趋势;铜、铬、铅含量的空间分异表现为起伏变化较大,岛状区域分布较多;铅、镉、汞含量以靠近海伦县县城处相对较高,砷含量不同空间位置上变化相对比较平缓。     

盐碱地稻田旱作后土壤肥力变化及其对作物生长的影响

研究了盐碱地稻田旱作后土壤肥力变化及其对作物生长的影响。结果表明,滨海滩涂盐碱地在水田改旱后土壤盐分呈现上升趋势,而土壤pH呈现下降趋势;不同培肥方法对水田改旱后土壤盐分、pH、土壤速效养分及有机质的影响作用不同,石膏处理能明显降低土壤pH值;绿肥处理能增加土壤速效养分和有机质含量;有机肥能抑制和延缓土壤盐分上升、降低土壤pH值、明显增加土壤速效养分和有机质含量,最终促进作物生长,增加作物产量。     

Recent trends of the total column ozone: implications for the Mediterranean region

The daily ozone column amounts during the 14-year period (1979–1992), which are inferred from measurements made with both the Total Ozone Mapping Spectrometer (TOMS) mounted on board the Nimbus-7 satellite have been used to study longitudinal trends at mid-latitudes. The main findings are: (1) There is a large longitudinal variation of the monthly trend in total ozone over the northern mid-latitudes ranging from 1.5 to 8.5 per cent per year with a large standard error, (2) The trend in the total ozone content over the Mediterranean area varies in a similar way with the zonal average total ozone trend over mid-latitudes. Also, the trend of the total ozone over Athens, Greece, is representative of the whole Mediterranean region and so it is representative of the zonal average total ozone trend over the northern mid-latitudes, and (3) The interannual variability of the amplitude of the annual wave in the total ozone amount over the Mediterranean region compares extremely well with the interannual variability of the total ozone amount over this location.     

一种基于地磁总场梯度的匹配定位算法

水下载体地磁导航技术是近年来研究的热点问题.为提高匹配导航定位的精度,提出了利用地磁总场梯度作为特征量进行地磁匹配定位.通过与地磁总场基准图的性能指标对比,分析了地磁总场梯度作为匹配特征量的优势.阐述了经典MSD(Mean Square Deviation)匹配算法的原理和缺陷,提出一种基于旋转变换的改进算法.仿真结果验证了地磁总场梯度匹配的优势和可行性;改进后的算法的定位精度相比经典MSD算法提高了26.57%,证明了改进算法的有效性.     

Using GA to dispatch the obtaining quantity for minimizing the total cost based on consideration of patient safety in HSCM

The objective of this paper is to study how to minimize the total system cost (TSC) when patient safety is considered in the hospital’s supply chain management (HSCM). Owing to the HSCM explored in material flow, service level (S.L) is used as the index of patient safety level in this paper. HSCM includes three hospitals and a centralized purchasing center (CPC). A genetic algorithm (GA) is applied in the CPC to compute the dispatched quantity for each hospital. The results show that the CPC coordinates the total obtaining quantity for each hospital and assists the hospital’s decision makers to estimate the total cost for each hospital. Also, the sensitivity analysis shows that to increase the same S.L for each hospital, these three hospitals should have almost the same incremental total cost when one unit quantity is dispatched.     

Mapping the potential annual total nitrogen load in the river basins of Japan with remotely sensed imagery

The increase of nutrient loads such as nitrogen and phosphorus to a river due to land cover changes in surrounding areas has been one of the major sources of water pollution or eutrophication. Monitoring the influent nutrient load from river basins to rivers is now crucial in the management of river basin environments. The monitoring is not easy, however, because it requires spatial and temporal measurement tools for land cover changes in the river basin and water qualities, and also it requires models relating them.In this study, we first analyzed the relation between the land cover types estimated from monthly maximum Normalized Difference Vegetation Index (NDVI) imagery calculated from NOAA Advanced Very High Resolution Radiometer (AVHRR) imagery and the annual total nitrogen load discharged from river basins. We found that the runoff load factor from urban areas is higher than those of forested areas. We also found that the impacts of land cover such as plantation and field weed communities on the total nitrogen load of each river are higher than the impacts of other land cover types such as Beech and Camellia japonica community type.Finally, we produced two advanced maps of the potential annual total nitrogen load (PTNL) index and the potential annual total nitrogen load for each river basin area (PTNL/area) index by considering the relationship between the land cover types and the annual total nitrogen load discharged from river basins in Japan. The PTNL map will be useful for the risk assessment of total nitrogen load impact on lakes and the sea through rivers from each basin. The PTNL/area index, which considers the effects of river basin areas, will allow evaluation of the state of river basins.     

在水分胁迫下棉花冠层叶片全氮含量的高光谱遥感估算模型研究

研究利用美国产ASD地物光谱仪,获取新疆北部地区棉花冠层关键生育时期的高光谱数据,采用红边积分面积变量估测棉花冠层叶片的全氮含量,对反射光谱进行一阶微分,应用一阶微分光谱数据,衍生出基于光谱位置变量的分析方法,以红边积分面积(SDr)为自变量,冠层全氮(TN)含量为因变量,做相关分析与处理,构建新陆早6号红边积分面积与冠层叶片TN含量的相关数学模型。研究在不同水处理条件下,对棉花冠层单叶叶绿素含量和单叶全氮含量做相关分析,结果表明:叶绿素含量与TN含量呈显著的正相关(R=0.8723,n=39),叶绿素含量能有效的估计棉花单叶TN含量;红边积分面积变量与冠层TN含量呈显著的相关性,相关系数是0.7394(n=40),利用构建的相关模型可以较为精确地估测棉花两个品种新陆早6号与8号冠层叶片的全氮含量,RMSE分别为0.3859和0.4272。研究认为红边积分面积变量具有预测棉花冠层全氮含量的应用潜力,研究得出利用3边面积变量构造的数学模型对反演作物冠层TN含量有较高应用价值。研究认为,红边位移现象结合红边幅度的变化的研究,用于诊断棉花水分胁迫也是可行的,关键是建立相应合理的诊断指标体系。研究结果证明:①随着棉花的生长发育,叶片的生理生化参数发生变化,冠层的生理生化参数随之发生变化;②.棉花叶片叶绿素含量与叶片的全氮含量相关性显著(R=0.8723,n=38),通过建立数学模型,可以估测叶片中全氮的含量;③由一阶微分光谱衍生出基于光谱“红边”位置变量的分析方法,使我们认识到“红边”的变幅、形状和面积包含了各个波段的信息,这些波段综合产生的变量所构造的模型,为棉花氮素营养参数的估计提供了预测能力;④如果棉花叶绿素含量高,说明水分充足、氮代谢旺盛,植株处于生长旺盛时期,红边向蓝光方向发生了位移。利用红边位移现象结合红边幅度的变化的研究,用于诊断棉花水分胁迫也是可行的,关键是建立相应合理的诊断指标体系。     

在水分胁迫下棉花冠层叶片全氮含量的高光谱遥感估算模型研究

研究利用美国产ASD地物光谱仪,获取新疆北部地区棉花冠层关键生育时期的高光谱数据,采用红边积分面积变量估测棉花冠层叶片的全氮含量,对反射光谱进行一阶微分,应用一阶微分光谱数据,衍生出基于光谱位置变量的分析方法,以红边积分面积(SDr)为自变量,冠层全氮(TN)含量为因变量,做相关分析与处理,构建新陆早6号红边积分面积与冠层叶片TN含量的相关数学模型。研究在不同水处理条件下,对棉花冠层单叶叶绿素含量和单叶全氮含量做相关分析,结果表明:叶绿素含量与TN含量呈显著的正相关(R=0.8723,n=39),叶绿素含量能有效的估计棉花单叶TN含量;红边积分面积变量与冠层TN含量呈显著的相关性,相关系数是0.7394(n=40),利用构建的相关模型可以较为精确地估测棉花两个品种新陆早6号与8号冠层叶片的全氮含量,RMSE分别为0.3859和0.4272。研究认为红边积分面积变量具有预测棉花冠层全氮含量的应用潜力,研究得出利用3边面积变量构造的数学模型对反演作物冠层TN含量有较高应用价值。研究认为,红边位移现象结合红边幅度的变化的研究,用于诊断棉花水分胁迫也是可行的,关键是建立相应合理的诊断指标体系。研究结果证明:①随着棉花的生长发育,叶片的生理生化参数发生变化,冠层的生理生化参数随之发生变化;②.棉花叶片叶绿素含量与叶片的全氮含量相关性显著(R=0.8723,n=38),通过建立数学模型,可以估测叶片中全氮的含量;③由一阶微分光谱衍生出基于光谱“红边”位置变量的分析方法,使我们认识到“红边”的变幅、形状和面积包含了各个波段的信息,这些波段综合产生的变量所构造的模型,为棉花氮素营养参数的估计提供了预测能力;④如果棉花叶绿素含量高,说明水分充足、氮代谢旺盛,植株处于生长旺盛时期,红边向蓝光方向发生了位移。利用红边位移现象结合红边幅度的变化的研究,用于诊断棉花水分胁迫也是可行的,关键是建立相应合理的诊断指标体系。     

ACCESS的总计查询及其解题浅析

总计查询作为计算机等级考试(ACCESS二级)中的难点,其包含了选择查询的全部语法。该文从总计查询的概念入手,分析了其类型、给出了具体解题的思路及其注意要点。     

On the correction of the total ozone content over Athens,Greece as deduced from satellite observations

The observations with the Total Ozone Mapping Spectrometer ( TOMS) mounted aboard the Nimbus-7 satellite have previously been used to determine the trends of the total ozone amount over Athens, Greece ( 38° N, 24° E), since 1979, for various months ( Varotsos, C. A., and Cracknell, A. P., 1993, International Journal of Remote Sensing, 14, 2053–2059). The total ozone depletion over the 13-year time period showed a strong seasonal variation of the trend from more than 7 per cent in winter to about 2·5 per cent in summer. However, the TOMS instrument measures the back-scattered ultraviolet radiation in order to determine ozone content and is limited to observations above the cloud level. ln the presence of thick cloud the column ozone content is generally underestimated. This underestimation of the total ozone amount is quantitatively examined, especially in the synoptic cases where ozone-rich air has been transported into the lower troposphere. The influence of this underestimation on the total ozone depletion over Athens, Greece, deduced from TOMS observations, is finally attempted.     

样本依赖与连接依赖的等价性

以抽象代数为工具,探索了全样本依赖与全连接依赖之间的关系.首先,分别在全样本依赖集和全连接依赖集上建立等价关系,这两种等价关系都将作用相同的依赖视为等价依赖. 然后证明了在这两个等价关系下的商集分别构成么半群,并且这两个么半群是同构的.这就等于证明了全样本依赖类本质上等同于全连接依赖类.最后给出了一个关于全无环连接依赖的有趣结果.有关结果可以在关系数据库的设计中发挥积极作用.     

Bidirectional reflectance of crops and the soil contribution

Spectra of cereals, grasses, and corn were measured repeatedly from preflowering to early maturity. The bidirectional and angular aspects were more pronounced for a standing crop such as cereals (oats) than for a clipped sod. The contribution of the soil to the total radiance and the amount of the total radiance were reduced by a greater percentage of ground cover. The effect of angular scattering on radiance decreased with maturity.