轴流泵站经济运行方案的确定   总被引：1，自引：0，他引：1  

刘家春  张子贤  张慕飞  陈平龙  王志辉 《排灌机械》2006,24(6):20-23

轴流泵站建成后，灌排区域内作物组成、水文、气象等因素将发生变化，引起泵站进出水池水位、泵站扬程和流量发生变化，致使泵站运行效率低，能源消耗高．为保证泵站在原有设备的条件下经济合理地运行，达到提高泵站效率，降低能源消耗，减少运行费用的目的，提供了根据泵站的提水流量、进出水池水位和泵站扬程的变化。通过调节轴流泵的叶片安装角度，来提高泵站效率和降低能源消耗的技术措施，给出了用系统分析的方法确定轴流泵经济运行方案的数学模型、约束条件和求解方法．通过多座泵站的应用，并经泵站测试，泵站效率已得到提高，取得了良好的效果．为泵站的经济运行提供了依据．  相似文献   

基于硬件加速的真三维显示体素化算法     

谭皓  杨忠  李玉峰  沈春林 《勤云标准版测试》2006,(1):59-64

提出了一种新的体素化算法，利用显示硬件支持二维光栅化算法和新的可编程控制功能，提高了体素化算法的效率。该算法通过逐层处理的方式将三维数据离散成为一系列的切片，利用硬件渲染完成切片的光栅化操作，将最终的光栅化结果组合成为体数据表达。算法利用可编程图形处理单元（GPU）的大规模纹理、动态顶点数据和灵活的纹理数据操作等特性，有效地降低了系统压力，提高了算法效能。实验证明，该算法满足真三维显示技术的要求。  相似文献   

套作春玉米氮磷钾化肥和有机肥合理配比的生产函数分析   总被引：4，自引：0，他引：4  

李萍萍  卞新民 《南京农业大学学报》1995,18(4):19-24

采用田间试验的方法，对苏南地区麦玉米稻三热制中套作春玉米的合理施肥量肥料配比进行了研究。  相似文献   

充液管道振动特性研究     

曾国华  孔建益  李公法  杨金堂  熊禾根  蒋国璋 《长江大学学报》2006,(4)

充液管道振动特性研究具有广阔的工程背景,对推进基础学科理论进步和国民经济发展有着举足轻重的作用。结合充液管道的研究状况,从是否考虑固液耦合两方面划分了充液管道振动特性的研究内容,归纳了其研究方法并对各种方法的适用范围以及优缺点进行了研究,对目前研究中的典型模型进行了探讨,可为今后的研究工作提供一定的参考价值。  相似文献   

基于农业机械替代作用的农业劳动力需求预测模型   总被引：1，自引：1，他引：0  

刘清峰  刘金兰 《中国农机化》2006,(1):41-43

农业机械对农业劳动力具有替代作用,在不考虑其他因素对劳动力影响的前提下,我国农业劳动力占总人口的比重与农业机械拥有量呈反相的线性相关关系。检验结果表明,用最小二乘回归法建立的劳动力预测模型是可靠的。  相似文献   

气象条件对柑桔果实生长的影响     

高阳华  贾捷  王跃飞  易新民  陈天战 《中国南方果树》1995,(2)

本文研究了红桔、锦橙和普通甜橙果实各生长阶段果径增长规律，建立了果实生长与气象因子的关系方程，揭示了柑桔果实生长规律及影响柑桔果实生长的气候问题。  相似文献   

Quantification and Simulation of Grazing Impacts on Soil Water in Boreal Grasslands     

N. T. Donkor  R. J. Hudson  E. W. Bork  D. S. Chanasyk  M. A. Naeth 《Journal of Agronomy and Crop Science》2006,192(3):192-200

We conducted a 2‐year study in central Alberta to quantify and simulate the soil water status of boreal grasslands under three grazing systems using wapiti (Cervus elaphus Canadensis), viz. (1) ungrazed control (UNG), (2) high intensity [4.16 animal unit month per ha (AUM) ha^?1 ] short‐duration grazing (SDG) and (3) moderate intensity (2.08 AUM ha^?1) continuous grazing (CG). Soil water was measured from May 1997 to September 1998 to a depth of 15 cm. Total annual precipitation in 1997 and 1998 was 494 and 429 mm respectively. In both years grazing treatments reduced soil water. Soil water content under SDG was significantly (P < 0.05) lower than CG. Simulation of soil water on each grazing system was conducted using PASTURE, a simple compartmental system dynamics model. Evaluation of the model was conducted using statistical criteria that included calculation of average error, root mean square, coefficient of residual mass and modelling efficiency and comparing these statistics against optimal values. Although the model under‐predicted soil water, simulations of soil water for grazing treatments in both years were closest to measured values with modelling efficiency (how well observed values are close to simulated values) up to 68 %.  相似文献   

江苏营造林管理系统的研建与应用   总被引：2，自引：0，他引：2  

程小义  倪健忠 《江苏林业科技》2005,32(5):19-22

根据生产需要,用面向对象编程语言Delphi和数据库技术的设计思想和实现方法,开发出了江苏省营造林管理系统.实践表明：使用该系统可有效地减轻手工工作量,提高劳动生产力,把统计过程中的各种误差或错误降低到最小程度,大大提高了江苏营造林管理信息的标准化、自动化和科学化水平.  相似文献   

Discussion of Emergencies and Safety in Highway Transportation     

《保鲜与加工》2003,(9):126-129

  相似文献   

Movements and habitat use by pikeperch (Stizostedion lucioperca (L.)) in a hydropeaking reservoir     

T. Vehanen  M. Lahti 《Ecology of Freshwater Fish》2003,12(3):203-215

Abstract –  We used radio telemetry to measure the habitat use and movements of 20 tagged pikeperch (44–59 cm) in the hydropeaking Pyhäkoski Reservoir, Finland, during June 1999–2000. The hydrological conditions in the 8-km-long reservoir were measured and then modeled over eight discharge rates between 30 and 700 m³ · s⁻¹. Pikeperch preferred relatively low water velocities and deep water depths especially during the winter. During the summer, pikeperch moved actively in different parts of the reservoir. No relationship was found between hydroelectric plant operations and distances moved by pikeperch during the summer. Movements peaked in autumn but decreased during the winter to a restricted area. After 1 year of monitoring, 4 out of 20 tagged pikeperch remained in the Pyhäkoski Reservoir, three had died when descending from hydroelectric dams, 10 had descended downstream to other reservoirs or sea, two were captured by local fishermen, and one fish's signal was lost for unknown reasons.  相似文献