U形渠道圆柱形量水槽的试验研究

选择了3种收缩比,分别为0.701、0.636和0.476,在U形渠道上对圆柱形量水槽进行了一系列的试验。试验结果表明,圆柱形量水槽的行近断面总水头H1与驻点水头Hs存在很好的相关性,相关系数等于0.9984。圆柱形量水槽的流量系数Cd不仅与相对水头Hs/L有关,与收缩比ε大小也有明显的关系,Cd随着Hs/L和ε的增大而增大。根据试验数据拟合的流量计算公式简明实用,自由出流时的流量计算平均误差不超过3.92%。     

梯形渠道机翼形量水槽试验

基于Hager对圆锥筒及圆柱体量水槽测流原理分析,推求出梯形渠道机翼形量水槽在自由出流时的流量理论计算公式,指出流量校正系数可由相对水头确定.选择6种收缩比进行了一系列室内模型试验,并根据试验数据建立了相对流量与相对水头的无量纲关系式.结果表明,相对流量与相对水头具有良好的相关关系,流量计算最大相对误差为±3.5%,该量水槽临界淹没度可达0.90,控制断面收缩比为0.372～0.585时可得到较好的量水效果.     

翼柱型量水槽在3种常用渠道上的应用性能对比试验研究

翼柱型量水槽是一种新型量水槽,其应用在灌区具有成本低、便于修建、量水精度高的特点。【目的】探讨翼柱型量水槽在矩形渠道、梯形渠道、U形渠道上的适用范围。【方法】试验在矩形渠道、梯形渠道、U形渠道上分别设计3种收缩比的量水槽,在不同流量工况下进行试验,并对测流精度、佛汝德数、水头损失、壅水高度等进行比较分析。【结果】拟合出矩形渠道、梯形渠道、U形渠道不同收缩比量水槽的流量公式,平均误差分别为0.42%、1.34%、1.65%,均满足规范误差小于5%的要求;翼柱型量水槽在3种渠道上游佛汝德数Fr均小于0.4,在U形渠道上游Fr最小;翼柱型量水槽在3种渠道上最大临界淹没度均大于0.85,应用于U形渠道的最大临界淹没度最高;矩形渠道修筑翼柱型量水槽产生的水头损失占上游总水头比例最小。【结论】翼柱型量水槽可用于灌区节水续建配套,同一比降条件下,矩形渠道与U形渠道衔接位置应用翼柱型量水槽效果最佳。     

U形渠道半圆柱形量水槽水力特性研究

对D60和D40 U形渠道半圆柱形量水槽水力特性进行了试验,共设计8种收缩比进行组合试验。结果表明:该量水槽过流顺畅,水头损失小,试验数据资料呈现极好的相关性,相关系数R2=0.998 4。应用量纲分析法建立的流量公式具有量纲和谐性,拟合的流量计算公式形式简明实用,流量计算平均误差为3.55%,淹没度可达0.93,上游断面佛汝德数Fr≤0.45。     

翼柱型量水槽应用于梯形渠道性能试验研究

为探究翼柱型量水槽在梯形渠道量水的性能,在梯形渠道上通过4种不同量水槽收缩比进行水力性能试验。通过对上游水位、流量和收缩比等进行分析,拟合了流量公式;并对测流精度、上游佛汝德数、临界淹没度以及水头损失进行了分析。试验结果表明:翼柱型量水槽在梯形渠道量水性能良好,水位～流量相关度极高,相关系数的平方R~2达0.997 1,推求的流量公式简易,测流平均误差为2.41%,上游佛汝德数小于0.4,临界淹没度达0.85以上,满足《灌溉渠道系统量水规范》(GB/T 21303-2017)相应要求。     

梯形渠道翼柱型量水槽试验研究与数值模拟

【目的】探究翼柱型量水槽在梯形渠道量水的适用性。【方法】对4种不同收缩比的翼柱型量水槽进行水力性能模型试验,并运用Fluent 17.1软件对其中2种收缩比的量水槽进行了数值模拟。通过对上游水位、流量和收缩比等进行分析,拟合得到了量水槽流量公式,并从测流精度、佛汝德数、临界淹没度以及水头损失等方面对其量水性能进行了分析。【结果】翼柱型量水槽在梯形渠道量水性能优良,水位-流量相关度极好,R2可达0.997 1以上,拟合的流量公式简明易用,测流平均误差为2.41%,上游佛汝德数均小于0.4,临界淹没度达0.85以上,通过数值模拟对量水槽水面线和流量进行误差分析,将实测值与模拟值进行比较,二者平均误差分别为3.80%和3.72%,与试验结果高度吻合,模拟结果准确可靠。【结论】翼柱型量水槽可用于梯形渠道量水,且量水精度满足明渠测流规范相关要求。Fluent软件可用于翼柱型量水槽数值模拟。     

巴歇尔量水槽水力特性试验研究

巴歇尔量水槽是一种通过明渠收缩段来量水的量水槽.试验在底宽0.3 m、深0.5 m、边坡系数为1的梯形渠道中设计了喉道宽0.25m的标准巴歇尔量水槽进行.试验完成了14组不同流量下的水位、水面线和量水槽上下游16个断面的流速量测.拟合出自由流和淹没流条件下水深-流量公式及上游水深与巴歇尔槽水头损失关系,对不同流量下佛汝德数沿渠身各控制断面的变化情况做了分析,从而可确定出临界水深断面位置,最后对大、中、小三个流量下的冲沙情况做了介绍.     

弧底梯形渠道无喉道量水槽水力性能影响因素研究

为了研究不同因素对弧底梯形渠道无喉道量水槽水力性能的影响,基于Fluent6.3大型流体计算软件,采用RNGk-ε湍流模型和VOF方法相耦合,对弧底梯形渠道无喉道量水槽进行了三维数值模拟,并将模拟流量与渠道流量进行对比分析,结果表明二者吻合度较好,该数值模拟方法有效可靠。在确定模拟准确性的前提下,分析了该量水设施在不同喉口收缩比和底坡下的水位流量关系,上游断面弗劳德数,壅水高度,水头损失等水力特性,为量水槽的进一步研究及其优化推广提供了新思路。     

末级渠道机翼形量水槽标准化试验研究

结合机翼形量水槽在末级渠道上的实际应用经验,提出了适应于末级渠道上的一种量水槽的标准化模式.试验中渠道采用矩形和U形相结合的形式,用机翼形量水槽衔接,通过4种量水槽收缩比进行了系统的组合试验.试验结果表明:该量水槽过流顺畅,水头损失较小,试验数据资料表现出极好的相关性,相关系数为0.996 1.拟合的具有量纲和谐性的指数形式的流量计算公式简明实用,流量计算平均误差为2.78%,临界淹没度可达0.88.     

U形渠道半圆柱形量水槽的数值模拟

通过室内试验,利用Flow-3D软件,采用True VOF法和RNGk-ε紊流模型对U形D40渠道半圆柱形量水槽进行了三维数值模拟。试验设置了4种不同收缩比(ε=0.27、ε=0.32、ε=0.36、ε=0.52)的半圆柱形量水槽,获得了18种工况下量水槽内的水面线及流量等水力要素,与实测值进行对比分析,得出了水位与流量曲线,并拟合出了其流量公式。结果表明,数值模拟的自由水面线与试验结果基本一致,模拟值与实测值最大相对误差均小于5%。因此,采用数值模拟方法能够有效模拟半圆柱形量水槽的三维水流特性。     

灌区量水设施分析研究

对国内外灌区量水设施进行了综述，比较了各种量水设施的应用范围和优缺点，从骨干渠系的水工建筑牧师是水、灌溉渠系水量流量自动化实时调控技术、低水头损失多功能量水设备技术及田间配不系统量水设施的装配式和标准化等方面，研究了量水设施及技术的发展趋势，提出了适合我国灌区研究推广量水设施的几点设想。     

新型超声波方形量水槽测流误差试验研究

为提高新型超声波方形量水槽在非淹没出流条件下的测流量精度,加强新型超声波方形量水槽在明渠量测水中的适应性,进而推进灌区信息化建设,在超声波方形量水槽前后加设水力收缩段,并引入水力学公式辅助测流,最后与三角堰进行流量误差对比试验研究.研究结果表明:无收缩段的方形量水槽在淹没出流条件下测流误差低于8％;有收缩段方形量水槽在...     

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.     

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。     

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。     

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.     

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。     

A European irrigation map for spatially distributed agricultural modelling

We present a pan-European irrigation map based on regional European statistics, a European land use map and a global irrigation map. The map provides spatial information on the distribution of irrigated areas per crop type which allows determining irrigated areas at the level of spatial modelling units. The map is a requirement for a European scale assessment of the impacts of irrigated agriculture on water resources based on spatially distributed modelling of crop growth and water balance. The irrigation map was compiled in a two step procedure. First, irrigated areas were distributed to potentially irrigated crops at a regional level (European statistical regions NUTS3), combining Farm Structure Survey (FSS) data on irrigated area, crop-specific irrigated area for crops whenever available, and total crop area. Second, crop-specific irrigated area was distributed within each statistical region based on the crop distribution given in our land use map. A global map of irrigated areas with a 5′ resolution was used to further constrain the distribution within each NUTS3 based on the density of irrigated areas. The constrained distribution of irrigated areas as taken from statistics to a high resolution dataset enables us to estimate irrigated areas for various spatial entities, including administrative, natural and artificial units, providing a reasonable input scenario for large-scale distributed modelling applications. The dataset bridges a gap between global datasets and detailed regional data on the distribution of irrigated areas and provides information for various assessments and modelling applications.     

粉质仪和拉伸仪在面粉生产中的应用

在介绍粉质仪和拉伸仪结构和原理的基础上,探讨了粉质曲线中吸水率、形成时间、稳定时间、弱化度和评价值等指标与面粉品质的关系,以及如何根据拉伸曲线中面团最大拉伸阻力、延伸度和拉伸曲线面积等指标来评价面团品质,并结合生产实际,概述了粉质仪和拉伸仪在面粉生产中的作用。