Modified full-sib selection and best linear unbiased prediction of progeny performance in a European F2 maize population

Four cycles of modified recurrent full‐sib (FS) selection were conducted in an intermated F₂ population of European flint maize. The objectives of our study were to monitor trends across selection cycles in the estimates of population mean, inbreeding coefficients and variance components, and to investigate the usefulness of best linear unbiased prediction (BLUP) of progeny performance under the recurrent FS selection scheme applied. We used a selection rate of 25% for a selection index, based on grain yield and dry matter content. A pseudo‐factorial mating scheme was used for recombination. In this scheme, the selected FS families were divided into an upper‐ranking group of parents mated to the lower‐ranking group. Variance components were estimated with restricted maximum likelihood (REML). Average grain yield increased 1.2 t/ha per cycle, average grain moisture decreased 20.1 g/kg per cycle, and the selection index relative to the F₂ check entries decreased 0.3% per cycle. For a more precise calculation of selection response, the four cycles should be tested together in multi‐environmental trials. We observed a significant decrease in additive variance in the selection index, suggesting smaller future selection response. Predictions of FS family performance in Cn + 1 based on mean performance of parental FS families in Cn were of equal precision as those based on the mean additive genetic BLUP of their parents, and corresponding correlations were of moderate size for grain moisture and selection index.     

土地利用和地形因子影响下的西藏农业产值空间化模拟

农业产值空间化模拟是客观评价农业生产效率的基础，是科学制定农业发展政策的依据。该文综合运用地统计学方法和地理信息系统空间分析功能，根据海拔高度与农业产值不同的拟合关系将西藏划分为Ⅰ型和Ⅱ型地区，分析了两类区域土地利用和地形因子与农业产值的关系。在此基础上，以土地利用为指示性因子，综合考虑地形因子对农业产值空间分布的影响，运用因子相乘的方法实现了多源数据的融合，建立了西藏农业产值空间化模拟模型。分析模拟结果：Ⅰ、Ⅱ型12个检验样本中共有8个县相对误差小于30%，模拟结果比较理想。同时，该模拟结果能够较好地反映西藏农业整体发展水平低，80%以上的农业用地每平方公里产值低于5400元， “一江两河”流域和昌都地区农业产值相对较高的实际情况。这有助于正确认识西藏的农业发展状况，为区域可持续发展服务。     

利用MODIS数据反演森林生物量的方法研究

以东北三省为试验区,利用MOD IS时间序列上的植被指数NDVI,结合森林资源清查样地数据测算的林分生物量,以及年均降水量、年均蒸散量、年均湿润度、年均积温、经度、纬度等地理环境因子,采用多元线性回归的方法构建森林生物量遥感估测模型。通过样本检验,该模型对东北三省的森林生物量密度估测精度较高,与检验样本的平均每公顷生物量平均相差1.30%;通过样本定位检验,平均相差21.87%。该模型适宜在宏观尺度上估测森林生物量。     

Interaction analysis between slenderness ratio and resin content on mechanical properties of particleboard

The interaction between particle size and resin content is one of the most important structural parameters that can influence the accuracy of predictions about wood-composite properties. We developed three kinds of equation (linear, quadratic, and exponential) for each mechanical property of particleboard based on slenderness ratio and resin content at a constant density (0.7g cm -3 ). Results from SHAZAM software (version 9) suggested that the quadratic function was not significant, but the linear and exponential functions were significant. The interaction between particle size and resin content was analyzed by Maple 9 software. The results indicated that an exponential function can better describe the simultaneous effect of slenderness and resin content than a linear equation. Under constant resin content, particles with higher slenderness ratios increased more in modulus of rupture (MOR) and modulus of elasticity (MOE) than did particles with lower slenderness ratios. Edge withdrawal resistance (SWRe) values did not increase with increasing slenderness ratio.     

重大线性工程建设下山区乡村聚落空间演变

区域重大线性工程建设对传统山区乡村聚落的发展带来深刻的影响，乡村聚落发展步伐被打断或加快，驱动乡村聚落发展演变与重构，对这一影响和演变过程研究，有助于进一步理解区域重大线性工程与社会经济对传统山区乡村发展产生的外部性，为山区乡村振兴政策制定与发展策略选择提供参考。该研究以河北省赤城县大海陀乡为研究对象，基于1999、2009、2019年3期遥感影像数据，结合空间分析、景观格局指数、Voronoi图及Logistic回归模型，科学识别重大线性工程驱动下乡村聚落空间格局演变规律。结果表明：1）大海陀乡的乡村聚落在高速公路建设前后两个阶段表现出散乱式的斑块数量增长型扩张、集聚式的斑块面积增大型扩张的空间格局演变特征，重大线性工程建设加快了乡村聚落的扩张速度，促进了村庄聚落的内部集聚。2）重大线性工程的建设为构建聚落环境提供社会经济支撑，具有瞬时性与外界强干扰性，驱使大海陀乡乡村聚落从自然资源依附到经济社会依附的演变，形成跨域式的影响效应。3）大海陀乡乡村聚落呈现出"要素-结构-功能"的循环演变机制，内外因素的作用下主体行为的多元模式、自然发展演变与外界力量冲击下三生系统的耦合关系是乡村聚落演变的主要驱动力。京津冀一体化背景下，重大线性工程建设是加强城乡要素流通与转变村民生产生活观念的基石，需统筹城乡资源，加强规划引导与整治措施，促进村镇体系重构。     

约束优化问题的遗传算法求解

应用遗传算法基本原理,采用锦标赛选择、算术交叉、均匀交叉、均匀变异和非均匀变异算子,设计了一般非线性规划和整数规划问题的通用求解算法,应用Matlab6.0编制了相应的求解软件。实例测试结果表明,该算法可以应用于一般的非线性规划和整数规划问题。     

等差线性程序涂渍色谱柱的研究

设计了等差线性程序柱，从理论上推导出等差线性程序柱中组分的保留时间与各操作参数之间的数学关系式，并对其色谱特性及应用了探讨。     

扩展二次规划在电力系统无功优化中的应用

Based on the Simplex and Gradient method, a new algorithm (EBM) is presented for solving the quadratic programming with upper and lower bounds. Firstly the ideas of Beale''s method and extended LP are analysed, and then an extended Beale''s method (EBM) is     

大庆地区草地退化驱动机制分析

为探讨资源型城市大庆市草地退化驱动机制,找出驱动草地退化的主导因素,为科学保护现有草地资源和有效治理退化草地提供依据和参考.该文在定性描述大庆地区草地退化驱动因素的基础上,运用主成分分析和多元线性回归的方法,选取与草地退化密切相关并比较容易获取的数据作为变量,对大庆地区草地退化的主要影响因素进行了定量分析.根据对草地退化的影响程度,影响因子排序为:畜牧业产值>人口密度>油井个数>总人口>大牲畜存栏>人均居住面积>GDP>工业产值>盐碱、沙化.并且根据大庆地区1988—2001年不同退化程度草地的面积与驱动因子建立多元线性回归模型,对不同退化程度草地面积变化的驱动机制进行了分析.结果表明,不合理的人类活动与石油开采加工的工业化进程占用大量草场是大庆地区草地退化的主要驱动因素,决定着草地生态系统逆向演替的总体趋势.最后根据以上分析提出大庆地区草地退化的防治措施.     

特征向量的零输入解定理及其证法探讨

在研究线性状态方程的特征向量与零输入解二者关系的基础上,推导出一个适用于线性定常连续系统的定理;给出了各种证明方法,并举例验证了定理的正确性。