基于C-D模型的土地整治效果实证研究

土地整治各生产要素投入关系着土地整治效果。运用因子分析法,确定总耕地面积、农业机械化投入、农业劳动力投入及水利设施投入4项生产要素,构建关于农业总产值的C-D生产模型,并以河北省阜平县为例,采用eviews7.2软件测算生产要素贡献率。结果表明采用因子分析法选取有效生产要素构建的C-D生产模型,可以简单直观测算土地整治生产要素的弹性系数和贡献率,测算结果可以为土地整治效果评定提供参考依据。     

A recessive gene controlling male sterility sensitive to short daylength/low temperature in wheat (Triticum aestivum L.)

Utilization of a two-line breeding system via photoperiod-thermo sensitive male sterility has a great potential for hybrid production in wheat (Triticum aestivum L.). 337S is a novel wheat male sterile line sensitive to both short daylength/low temperature and long daylength/high temperature. Five F₂ populations derived from the crosses between 337S and five common wheat varieties were developed for genetic analysis. All F₁’s were highly fertile while segregation occurred in the F₂ populations with a ratio of 3 fertile:1 sterile under short daylength/low temperature. It is shown that male sterility in 337S was controlled by a single recessive gene, temporarily designated as wptms3. Bulked segregant analysis (BSA) coupled with simple sequence repeat (SSR) markers was applied to map the sterile gene using one mapping population. The wptms3 gene was mapped to chromosome arm 1BS and flanked by Xgwm413 and Xgwm182 at a genetic distance of 3.2 and 23.5 cM, respectively. The accuracy and efficiency of marker-assisted selection were evaluated and proved essential for identifying homozygous recessive male sterile genotypes of the wptms3 gene in F₂ generation.     

低压三级放大器的密勒——前馈频率补偿

论文将极点分离、前馈补偿和密勒支路补偿技术相结合,采用0.5um工艺设计CMOS放大器,Miller-Feedthrough Compensation(MFC),分别驱动120pF/25KΩ和1200pF/25KΩ负载,实现增益带宽积14.7MHz和3.3MHz。     

旅游城市发展低碳旅游物流路径探讨

在当今低碳经济大背景下,旅游城市物流现状并不容乐观,能源消耗大、碳排放超标,旅游景观遭受污染、破坏,政府缺乏统一规划,物流企业动力不足等等,因此,旅游城市如何将旅游与低碳物流融合为一体,实现旅游、经济、资源、环境共赢的可持续发展无疑具有重要意义。在分析当前旅游物流现状和发展意义的基础上,提出构建低碳旅游物流系统、建立多方共赢的低碳管理体系、加强信息化等可行性路径。     

Revisiting the occupational aspirations and destinations of Anglo-Australian and Chinese-Australian high school students

Evidence from Australia lends support to the “Asian high achieving syndrome” in Chinese-Australian students and “self-deprivation syndrome” in Anglo-Australian students. Applying ethnographic case studies approach for doctoral thesis the author collected data on a longitudinal basis from homes and school of these students. All of these students attended the same school located in a predominantly middle class suburb of Perth Metropolitan area in Western Australia. Chinese-Australian families had settled in Perth from Malaysia, Singapore and Hong Kong, whereas Anglo-Australian families had been residing in Perth for three generations. Impetus to revisit these students (now young adults with their own families) 10 years later came from an urge to test the validity of the prediction the author had made in the concluding chapter of his doctoral thesis. The author had claimed that “if Anglo-Australian parents keep on dwelling in the era of 1950s and 1960s and do not change their laid-back attitude about education, their children could eventually be under-privileged in their own country”. Ten years later, the author undertook a follow-up study on these young adults from six of the eight original families in order to find out their occupational destinations and future aspirations. Data for the follow-up study were collected from these young adults and their parents. These research cases were interviewed twice, each time approximately for two hours and their parents were interviewed once for two to three hours. The purpose of this paper is to report the findings of the follow-up study which reveals a remarkable relationship between the attitude towards schooling and academic performance with their subsequent occupational destination.     

基于随机舍弃邻域的低照度图像去噪算法

场景中的光照条件对数字图像的质量具有决定性影响,当光照强度较弱时,获取的低照度图像对比度低,信噪比较差,给后续图像处理工作带来困难。经典基于邻域的图像去噪算法依据图像相邻像素之间的灰度连续性,往往在去除噪声的同时导致图像边沿模糊。文章介绍一种基于邻域像素随机舍弃的低照度图像去噪算法。算法首先根据像素邻域的拉普拉斯算子自适应地调节舍弃概率,并对邻域内各像素进行随机舍弃估计;然后以邻域的方差最小化为目标函数并添加偏差项进行约束,通过协调方差项与偏差项获取保留像素的权重估计;最后根据邻域像素的权重迭代估计图像像素值。实验仿真结果显示该算法能够在低照度条件下有效去除图像噪声,恢复原始图像信息。     

某低品位磁铁矿钛铁矿选矿试验研究

某低品位磁铁矿钛铁矿矿石含铁13.66%、钛3.01%,磁铁矿、钛铁矿为回收目的矿物。试验进行了＂弱磁选—强磁选＂和＂弱磁选—摇床重选＂两方案的对比,研究结果表明,＂弱磁选—摇床重选＂方案选矿效果较好,最终可获得铁品位60.25%、铁回收率35.57%的铁精矿和钛品位38.57%、钛回收率37.48%的钛铁矿精矿。     

10kV低压配电系统励磁涌流问题分析及解决方案

变压器励磁涌流是低压配电线路电流保护误动的主要原因之一,通过对某地区电网10kV低压配电系统中两起因配电变压器励磁涌流引起配电线路电流保护误动事故进行分析,结合励磁涌流的产生原理和特点及10kV配电网的特点和实际运行需要,提出防止励磁涌流引起电流保护误动的继电保护整定解决方案。     

低渗透性硬煤层注水方法探讨

矿井粉尘能够引起瓦斯粉尘爆炸以及矿山工作人员的尘肺、矽肺职业病,严重影响煤矿的安全生产和工人的健康。经实践证明煤层注水是降低粉尘的最根本、最有效的方法。针对我国存在的大量低渗透性硬煤层注水效果差这一事实,本文以提高低渗透性硬煤层注水效果为目的对低渗透性硬煤层注水方法进行总结。     

基于iBeacon的智能导览系统的设计与实现

运行在移动互联网设备上的传统智能导览系统体验性不佳。文中介绍了一种使用iBeacon技术的智能导览系统。该技术能让移动互联网设备靠近iBeacon设备时进行响应。iBeacon设备使用低功耗蓝牙技术与移动互联设备进行数据传输。