比例估计中样本大小的设计方法

设具有规定属性单元在总体中所占比例为Ｐ,本文讨论了比例估计的几种统计量的性质,证明了逆抽样方法所得的一个Ｐ的无偏统计量,给出了对比例的置信限正态近似时样本大小的计算公式。     

一类相似逆变换矩阵的构造

证明并给出一种构造可以对角化矩阵的相似逆变换矩阵的新方法．     

相关逆阵主对角负元析

利用电子计算机对试验资料作多元相关分析,偶尔会遇到相关逆阵主对角出现负元的现象,因而使分析陷入困境。本文分析了这种反常现象的产生原因,并提出了一种行之有效的处理方法。从而使统计分析臻于完善。     

Remote sensing to detect plant stress induced by Heterodera schachtii and Rhizoctonia solani in sugar beet fields

The characteristically clustered occurrence and low level of mobility of Heterodera schachtii and Rhizoctonia solani in the soil and the induction of stress symptoms in the sugar beet canopy make them ideal targets for site-specific arrangements with precision agriculture tools. A field site infested with H. schachtii and R. solani was investigated in 2009 with near-range and aerial hyperspectral sensors during the growing season. At 31 sample points ground truth data for incidence and severity of the two organisms were collected and geo-referenced. Spectral vegetation indices computed from reflectance measurements obtained from two flight campaigns (AISA, 17th of June; HyMap, 28th of August) and the near-range spectroradiometers were significantly correlated (P < 0.01) with symptoms caused by the nematode or Rhizoctonia crown and root rot. A supervised classification with Spectral Angle Mapper of leaf symptoms induced by the organisms resulted in a classification accuracy of 72 and 64% for the AISA and HyMap data, respectively. The results demonstrated that remote sensing in combination with geographic information system technologies can be used effectively for the detection and mapping of symptoms caused by beet cyst nematode and Rhizoctonia crown and root rot.     

Simulation of chromium transport in the unsaturated zone for predicting contaminant entries into the groundwater

Heavy metal contaminations in the top‐soil layers can impose serious threats to groundwater quality. A seepage water prognosis of probable future contaminant entries at the groundwater surface has to take into account the emission characteristics of the source zone and the reactive transport of the contaminated leachate through the unsaturated zone. Here, a possible approach is presented, exemplarily for a site contaminated with chromium, encompassing batch elution experiments, unsaturated soil column leaching experiments with flow interruption, soil monolith lysimeter experiments, and numerical modeling of non‐equilibrium solute transport. The prognosis provides a long‐term prediction of Cr concentrations at the groundwater surface. It must be emphasized, that the modeling results are uncertain, because several of the parameters in the simulations can be determined only with significant errors. Additionally, the approach is not applicable routinely for every hazardous waste site. Our study reveals, however, that reactive contaminants can possibly reach the groundwater at hazardous concentrations within very short time.     

The filtered back-projection algorithm of magnetic induction tomography with uniform magnetic excitation

Helmholtz coils produce uniform sinusoidal magnetic field in the center region, and the direction of magnetic field is approximate straight line, to help simplify the complexity of inverse problems. The simulation models of an 8-channel magnetic induction tomography measurement system are built, reconstructing conductivity distribution with filtered back projection algorithm. In the filtered back projection algorithm, the detected data is supplemented by the linear interpolation first, and then filtered by the Hamming filter, while adding a window filter to reduce the impact of around the coil from the divergence of the magnetic field. The different noise ratio of noise is added in the detected data to test noise suppression ability of the algorithm. The experiment results show that this filtered back projection algorithm can reconstruct the conductivity distribution under this model.     

猪精氨酸-丝氨酸蛋白激酶1(SRPK1)克隆表达及功能初步分析

本研究旨在阐明猪SRPK1基因的分子特点和表达谱。以大白猪为研究对象,利用RT-PCR技术克隆SRPK1基因CDS区域,同时利用反向PCR(inverse PCR,I-PCR)技术得到猪部分SRPK1的5′UTR序列;利用生物信息学方法分析SRPK1基因核苷酸序列及编码蛋白序列的结构特点;利用荧光定量PCR(real-time PCR)检测SRPK1在1和30日龄大白猪及杜洛克的心脏、肌肉、脾脏、肝脏、肾脏、肺脏、胃、小肠、大肠、脑的表达情况;构建猪骨骼肌损伤模型,研究在骨骼肌发育过程中SRPK1基因的表达特性。结果,将克隆片段拼接得到长2499bp的大白猪SRPK1基因序列,包含了1968bp完整CDS区域,分析表明其编码含656个氨基酸的蛋白质;包括2个P_Kc结构域,猪SRPK1蛋白序列与人和黑猩猩的相似性较高。通过生物信息学方法预测所得5′UTR含有多个转录结合位点:HSF1、HSF2、Ik-1、IK-2、SRY、SP1MyoD、USF、E47、p300、CP2、RREB-1、E2F和AP-1。利用荧光定量PCR研究发现,表达结果显示猪该基因表达具有组织和种间特异性,主要都是在胃、大肠和小肠中表达。SR-PK1基因在整个损伤修复过程中的表达反复出现升高和降低。5′UTR处有多个和肌肉生长相关蛋白的转录结合位点,主要在消化系统组织表达,在骨骼肌修复中表达上调,推测其可能与骨骼肌细胞发育或其他肌肉生长相关因子的表达有关。     

激光致等离子体及其对激光加工的影响

论述了激光致等离子体机理和激光致等离子体在光束一工件能量耦合过程中的作用。对等离子体振荡与逆韧致副射吸收作了物理讨论，导出了等离子振荡频率和吸收系数公式。     

子阵约束下实矩阵反问题有解的条件

讨论了如下两类问题 :问题 :给定 X∈ Rn× k,B∈ Rm× k,A0 ∈ Rp× q,求 A=A1 1 　 A1 2A2 1 　 A2 2∈ Rm× n使得 AX=B,A1 1 =A0 .问题 :给定 A*∈ Rm× n ,求 A∈ SA使得‖ A* - A‖ =minA∈ SA‖A* - A‖ .其中 SA是问题 的解集合 .给出了问题 有解的充分必要条件及解集合 SA 的一般形式 .对于问题 2 ,给出了解的表达式及一个数值算法与数值例子 .     

渭-库绿洲耕层土壤水盐空间分异特征研究

探索干旱区绿洲耕层土壤水盐空间分异规律对土壤盐渍化防治具有十分重要的意义。以渭干河-库车河三角洲绿洲为研究区,采用反距离加权、局部多项式、径向基函数和普通克里金插值方法进行土壤水盐含量的空间插值,并利用均方根误差、平均相对误差、平均绝对误差以及决定系数对4种插值结果进行精度验证,并分析不同海拔和土地利用类型下的土壤水盐空间分异特征。结果表明:1）研究区耕层土壤水盐空间变异程度由大到小依次为土壤总盐＞电导率＞含水量＞pH值,pH值属于弱空间变异,电导率和土壤总盐属于强空间变异,土壤含水量为中度空间变异。2）对比4种插值方法的精度,由高到低依次为反距离加权>径向基函数>普通克里金>局部多项式,反距离加权模型的决定系数最高,均方根误差、平均相对误差和平均绝对误差均最小。3）研究区耕层土壤含水量由东向西递增,而pH值、电导率和土壤总盐由东向西递减,均呈现出较为明显的条带状分布规律。在不同海拔高度和土地利用类型下,土壤水盐含量呈现出显著的空间差异（P<0.05）。