机压微灌管网系统布置与管径同步优化设计

微灌管网系统由轮灌管网(支毛管)和续灌管网(干管)组成,以往的研究没有将其作为一个系统,且不能实现布置与管径组合的同步优化,研究成果对坡度均匀的大型灌区机压微灌独立管网系统的优化也不适用。因此,提出了机压微灌管网系统优化的方法,并建立了优化设计数学模型,采取整数及实数编码的混合编码方法,通过遗传算法求解,同时实现轮灌管网及续灌管网的布置优化及管径组合优化,得出的管径为标准商用管径,无需调整。实例计算结果表明,该模型与算法在求解机压微灌管网系统优化设计问题上具有良好的优化性能和求解精度。与传统设计方案相比较,轮灌管网和续灌管网的优化设计方案单位面积年费用分别降低了14. 85%～35. 59%和4. 12%～12. 99%,节省投资效果明显。     

喷灌管网系统的管径优化设计

本文提出了在喷灌系统中树状管网管径优化设计的数学模型,并对该问题采用动态规划法求解,考虑到决策变量的不同有如下两种情况:1.以管径连续变化为前提;2.以标准管径为依据。此外,作者还提出了第三种解法——枚举法。比较上述三种计算方法的结果,可以看出:第二、三种解法算得的最优方案基本相同,较第一种算法为优。     

基于遗传算法的山地自压管网干管优化设计

针对目前山地自压滴灌管网工程中管径选择的难题,建立了以管网造价为目标函数,标准管径为决策变量,满足灌溉水量、水压、流速等约束条件的树状灌溉管网优化数学模型,在管网布置确定的情况下寻求使管网投资最小、可靠性最高的管径组合方案。采用基于整数编码的遗传算法来求解,用模拟退火罚函数法处理约束条件,将模拟退火的良好局部寻优能力和遗传算法的全局搜索能力有机地结合在一起,实现算法的改进。优化结果与经济流速法的计算结果相比较,管网投资减少了27 280元,仅占优化前的86.84%,管段水头利用率由65.38%提高到了97.61%。结果表明:改进遗传算法在经济性和重力水头利用率上都优于经济流速法,且该模型算法操作简单,易于实现,具有良好的优化性能和求解效率,可用于实际生产。     

给水管网优化设计的多目标遗传算法

为兼顾给水管网优化设计中的经济性和可靠性问题,以管网年费用和管网系统可靠性为目标函数建立给水管网优化设计的多目标遗传算法数学模型;并将系统可靠性定义为"节点富余水头加权平均值"和"管网恢复力",进而对多目标遗传算法模型求解过程进行分析。最后以一个典型的工程案例加以验证,结果表明,多目标遗传算法所得到的目标函数值和管网水力性能明显优于传统设计方法,充分说明了多目标遗传算法用于管网优化设计的实用性和有效性。     

基于不可行度的机压树状管网退火遗传算法优化

规定管网中每一管段最多只能由两种管径的管道组成,提出一种以管网年费用为目标函数,以水泵扬程、管长和标准管径为决策变量的机压树状输水管网优化数学模型.定义种群中个体的不可行度函数,采用基于解的不可行度退火算法处理约束条件.应用模拟退火算法,对解的不可行度进行局部优化,使其逐步逼近可行解.将遗传算法全局优化和模拟退火的良好局部搜索能力有机结合,构造出一种退火遗传算法用于机压树状管网优化设计.仿真结果表明,该模型与算法在求解机压树状输水管网优化问题上,具有良好的优化性能和求解效率.     

用基于整数编码的改进遗传算法进行环状管网优化设计

应用基于整数编码的改进遗传算法进行环状管网管径优化设计 ,既可避免编码冗余问题 ,又可提高算法的实用性和计算效率 ,并能在较大解空间范围内获得最优管径组合方案以实现尽可能大的管网投资     

自压喷灌干管管网的优化计算

结合自压喷灌的特点，以干管管网投资之和最小为目标函数，以标准（商用）管径，管长为优化变量，建立了自压喷灌干管网优化计算的线性规划模型，在管网布置方案确定后，利用这一方法，可进行了干管管网的优化设计。     

基于加速遗传算法的多孔变径管优化设计

将基于实数编码的加速遗传算法（RAGA）应用于多孔变径管优化设计中，解决了设计中多维参数寻优问题，避免了传统方法早熟、提前收敛以及易陷入局部最优等弊端。在固定管道式喷灌系统优化设计中应用，求解出多孔变径管的最优管径、管长等多维参数，效果较好，为该方面研究提供了一种新的优化求解方法。     

利用正交表优化设计自压式低压管灌系统

在渠灌区,研究充分利用地形落差情况下自压式低压管灌树状管网的优化设计,对降低投资有重要意义。管网优化设计应将管网布置优化和管径优化结合进行设计。本文利用正交表及其优化分析原理,同时结合应用非线性数学规划法优化管径,不仅可得到所有管网布置组合中的最优方案,还可视实际需要得到若干次优方案。该优化设计法计算工作量较小,简单可靠且实用。     

基于混合蛙跳算法的自压微灌管网系统优化设计

【目的】解决自压微灌管网系统布置与管径优化设计的问题,节省工程投资造价。【方法】以新疆某灌区一微灌工程为研究对象,以微灌系统中各级管道的管段长度、管径为决策变量,支毛管允许水头差、工作压力、管径、流速等为约束条件,以管网总投资最小为目标,分别建立了双向毛管布置和单向毛管布置的自压微灌管网数学模型,并采用混合蛙跳算法进行求解,优化管网的布置及各级管道的管径。【结果】该优化设计方法对自压微灌管网系统能够实现管网系统布置与管径的同步优化,优化设计后的方案干管段数减少,干管每一段的长度和每条支管长度增加,部分管段管径减小,所需总投资为469 129.3元,与依据相关规范和经验进行设计的原方案相比,管网投资降低了21.5%。【结论】该优化设计方法所得的优化结果节省投资明显,混合蛙跳算法收敛性能稳定,计算速度较快,具有较高的计算精度,对水源有保证、地面坡度不大且较为均匀的自压微灌管网系统的优化设计具有一定的应用价值。     

Overland water and salt flows in a set of rice paddies

Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31 ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5 dS m⁻¹) and an infiltration rate of 5.8 mm day⁻¹. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731 mm (5.1 mm day⁻¹), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874 mm, deep percolation was 830 mm and surface runoff was 372 mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2 mm day⁻¹ was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration.     

车用发动机润滑油失效规律与更换周期研究

研究在正常使用条件下１０Ｗ／３０－ＱＣ级润滑油用于某型车用发动机时所表现的失效规律,确认期服从两参数Ｗｅｉｂｕｌｌ分布,并给出分布的尺度参数η和形状参数ｍ之最佳线性无偏估计（ＢＬＵＥ）同时,还为定量分析,计算车用发动机润滑油的使用可靠性和合理确定其更换周期提供了一套可供借鉴的方法,并给出了具体的计算实例。     

农村剩余劳动力就业问题的探讨

论述了我国农村剩余劳动力就业的意义,并针对我国农村剩余劳动力的现状,提出多渠道促进农村剩余劳动力就业的途径和办法。     

金谷子耐旱TG118引种试种及推广应用

对引进的谷子新品种金谷子耐旱TG118进行品种比较试验和多点试种。结果表明：该品种抗旱、耐瘠、适应性强,稳产、高产、抗病抗风抗倒伏强,品质优良,粮草兼用,种植简单,省工易管;一般产量在6000kg/hm2以上,比当地主栽品种增产20%以上。最高产量达9450kg/hm2,适于在辽西北地区推广应用。     

对《种子法》存在问题的探讨

《种子法》是我国种植业第一部法律。自实施以来,为依法加强种子管理提供了有力的法律支撑,促进我国种子产业发生翻天覆地的变化。但随着依法管理工作的深入和种子产业的快速发展,《种子法》及配套规章的一些问题逐步显现出来。对《种子法》及配套规章存在的问题进行深入分析,对需要进一步补充的章节以及需要调整的内容进行深入探讨,以求更加完善和明确。     

瓦房店市水果生产标准化发展研究

瓦房店市是我国重要的水果生产基地,在国内水果生产领域占有重要地位。随着水果市场化的不断深入,如何满足和适应国内外市场需求成为瓦房店市水果生产的关键问题。从瓦房店市水果生产实际出发,阐述了实施水果生产标准化的必要性,提出了发展水果生产标准化的具体措施。     

乡（镇）农业技术推广体系存在的问题及对策

乡（镇）农技推广体系是农业发展的关键。介绍朝阳市农业技术推广体系的现状,针对目前体制及运行机制、服务手段等方面存在的问题,提出适合朝阳市乡（镇）农技推广体系改革与发展的对策,以期对全省农技推广体系改革和发展起到一些借鉴作用。     

草莓的采收与贮藏

草莓果味酸甜爽口,营养价值高,为人们所喜爱的应市鲜果之一。由于草莓易受损伤和微生物侵染,因此其采收、贮藏过程极为重要。介绍草莓采收过程中的注意事项以及11种贮藏保鲜技术的实施步骤和操作方法,推介9种加工方式,为草莓产业化提供技术支持。     

和谐社会理论建设的几点哲学思考

在新世纪,面对机遇和挑战,党的十六大把“社会更加和谐”作为全面建设更高水平的小康社会的一个重要目标。中国人素有社会和谐的理想;西方人自古也向往社会和谐;借鉴东西方两种和谐社会思想的经验、教训,构建社会主义和谐社会理论。     

Review of the Egyptian experience in implementing land drainage projects

About 30 years have passed since the Government of Egypt embarked on implementing a series of large scale drainage projects. At present, about 3.8 million acres have been provided with drainage systems on the basis of systematic pre-drainage investigations and designs. The target is to provide drains in approximately 6.4 million acres in the Nile Valley and Delta.The implementation of the subsurface drainage system is carried out by the public sector and private contractors under direct supervision of governmental regional departments. The implementation process depends on many factors related to the drainage material, machinery, manpower, site requirements, farmers and organizations involved. Problems and constraints are sometimes challenging, however, the annual rate of implementation has gradually increased to 170,000 acre/year.This paper discusses the different aspects involved in the implementation process of drainage systems. The development in materials, machinery and construction technologies will be reviewed. Institutional and management factors are going to be also considered.