中国美利奴羊品种结构体系构建的研究

中国美利奴羊是当代中国细毛羊中最优秀的品种资源，培养成功后已建立了毛密品系。本研究根据群体遗传学原理，通过市场分析，采用系统地介体选择，集群建系方法又建立了体大品系和综合优品系。丰富了品种结构，有效地防止了小群体随机交配可能产生的遗传漂变和优良基因丢失，保持了群体基因的良好结构，为推动吉林型中国美利奴羊品种发展打下了较稳固的基础。     

应用微机技术实现水库水位遥测

本文介绍一种应用微机技术实现水库水位遥测的方法及仪器,它使用了“智能消除零点漂移”、“传感器特性分段处理”、“数字滤波”等,取得显著效果,在很宽的量程范围内可获得较高的精密度。     

温度对粳稻光温敏感雄性核不育系育性影响

粳稻光温敏感雄性核不育系(简称“二系不育系”)的繁种是二系杂交稻繁殖的重要环节,影响不育系育性的两大因素为光周期与温度,光周期是基本不变的因素,温度在气候环境影响下为可变因素。通过6个不同类型的不育系在上海地区晚播和海南短日照下,观察不同温度对各不育系的育性影响,了解不育系育性随温度的变化规律与发展趋势,确定二系不育系的最佳繁种地点、时间、方法,为二系杂粳组合在生产上应用提供繁种科学依据。     

喷雾参数与飘移相关性分析

飘移是评价液体农药喷洒质量的重要指标。在影响喷雾飘移的因素中，喷头类型、喷头的大小(流量)和风速都有重要影响。分析它们对飘移的影响对于合理选择喷头和喷雾条件有重要意义。该文在试验的基础上，应用数学建模方法分析不同喷雾参数与飘移量之间的相关关系，并通过回归分析，确定它们对飘移量的作用程度，从而分离主要参数，为参数优化提供依据。研究结果说明，喷头类型、喷头大小和风速都对飘移有显著的影响，但作用强度不同，由强到弱依次为风速、喷头类型和大小。     

Electrophoretic variation among and within strains of ‘kharkof’ wheat maintained at 11 locations

Summary The hard red winter wheat (Triticum aestivum L.) cultivar Kharkof was introduced to the United States at the turn of the century and has been included as the long-term check for the Southern and Northern Regional Performance Nurseries since 1930. Seed of Kharkof is typically maintained at each site at which the nurseries are grown. We obtained samples of Kharkof from 10 sites and the USDA Small Grains Collection in Beltsville, MD. Up to 54 individual kernels per strain were ground and evaluated for gliadin electrophoretic patterns. Strains from Beltsville, MD and Aberdeen, ID were completely uniform for gliadin patterns; they differed from each other and from all other strains. Seven strains were highly polymorphic, with 7 to 14 gliadin patterns occurring in each. However, there were large differences in pattern frequencies among strains, with the Ft. Collins, CO and Columbia, MO strains at one extreme, the Manhattan, KS and Lincoln, NE strains at the other, and the St. Paul, MN; York, NE; and Clovis, NM strains intermediate. Strains from Dallas and Chillicothe, TX were completely uniform for a pattern that also occurred in all of the polymorphic strains. The two Texas strains also had esterase and -amylase isoelectric focusing patterns different from the others, and the Beltsville strain had a different -amylase pattern. We concluded that the strains from Beltsville and Aberdeen were not Kharkof, that the Texas strains were derived from a single-plant selection out of Kharkof, and that the remaining strans have diverged through natural selection possibly operating in conjunction with genetic drift, outcrossing, and seed mixtures.     

植保无人机施药数值建模关键技术与验证方法研究进展

随着植保无人机在精细农业上的应用日益增长,目前在植保无人机下洗风场演化及其作用下的雾滴沉积飘移过程的数值模拟方法取得了快速多样化发展,但对各方法的优势、缺陷、适用范围及验证手段仍缺乏系统的梳理。本文针对无粘模型、计算流体力学模型及格子玻尔兹曼模型分别开展论述。基于涡元法的无粘尾涡模型优势在于计算过程简单,但由于缺乏粘性和湍流模型,其雾滴沉积飘移模拟精度较低。计算流体力学模型又分为有限体积法与有限差分法。其中,有限体积法鲁棒性高,可适用于各种复杂环境的模拟,但格式精度有限,其模拟的翼尖涡耗散速度远快于实际情况;有限差分法能够实现对翼尖涡演化的高时空精度模拟,但其存在网格结构化要求高,算力要求过大等问题。格子玻尔兹曼方法在计算具有复杂边界条件和非平稳运动物体的三维流场问题中具备优势,但其在功能多样性和完备性上还存在不足。上述数值模型精度还需综合运用田间实验及室内实验,如高速粒子图像测速（Particle Image Velocimetry,PIV）或相位多普勒测速（Phase Doppler Interferometry,PDI）方法进行验证和优化。最后,本文提出了未来植保无人机施药模拟及验证方法发展方向。     

Genetic drift in a hatchery and the maintenance of genetic diversity in hatchery-wild systems

ABSTRACT:   Loss of within-population genetic diversity by genetic drift is related to stocking. In order to reduce it, selective use of wild-born individuals for hatchery broodstock is proposed. Its effectiveness is evaluated by the analytical method and numerical simulation. Results indicated that it is effective, especially when the ratio of released hatchery-produced individuals is high in the natural population. Loss of within-population genetic diversity by a few other strategies of broodstock preparation is also analyzed by numerical simulation and the effectiveness of these is also discussed.     

Modeling the transport and survival of Japanese sardine larvae in and around the Kuroshio Current

We have numerically modeled the advection and diffusion of sardine eggs and larvae to investigate the larval transport processes of Japanese sardine from the spawning grounds by the Kuroshio.
The results indicated that the offshore drift current induced by the winter monsoon and the location of the spawning ground have significant effects on the survival of the Japanese sardine. The contribution of the drift current, the distance of the spawning ground from the Kuroshio axis, and the eddy diffusivity to the larval retention in the coastal area is approximately expressed by the following equation: where R is the retention rate in the coastal area, a the variance of initial distribution of eggs, T the time after the eggs were spawned, – V₀ the velocity of the wind-induced offshore current, y₀ the distance of the center of the spawning area from the Kuroshio axis, and K the coefficient of horizontal eddy diffusivity.
The year-to-year variation in larval survival rates stimulated by the two-dimensional model are consistent with those estimated previously by using field data of egg and larval abundance during 1978–1988.     

ZY-2摇臂式喷头组合喷灌技术参数田间试验研究

采用承雨筒测量法,对目前市场上常用的ZY-2摇臂式喷头采用18 m×18 m布置方式在不同气象条件下的组合喷灌主要技术参数开展田间试验研究.结果表明,组合喷灌均匀系数、喷洒水利用系数均在0.8以上,蒸发漂移损失的测试值为0.8%～14.28%.主要集中在4%～10%.构建了组合喷灌主要技术参数与主要气象因素、工作压力的...     

CSAMT法在包神铁路地基勘查中的应用

CSAMT法是在MT和AMT的基础上发展起来的一种人工源频率域测深方法,勘探深度适中、分辨率高、抗干扰能力强、工效高成本低廉,在工程物探中是一种行之有效的方法。讨论了基于V8系统的CSAMT法的原理、工作方法和资料解释处理,并应用于包神铁路复线乌兰木伦段地基勘查中,成功地解释了地基采空区的位置、埋深、范围,为包神铁路复线建设提供了依据。