PTN新型渠道接缝材料研制

在分析探讨渠道接缝材料在渠道输配水工程中的重要作用的基础上,针对我国目前现有渠道接缝材料的不足,提出了新型渠道接缝材料PTN,论述了其方案筛选、配方及制作工艺过程,并将新型渠道接缝材料PTN的主要性能与国内外同类产品作了比较,认为PTN为一种适于我国国情的性能优越的新型渠道接缝材料。     

现浇混凝土衬砌渠道的施工工艺及流程

主要介绍混凝土衬砌渠道的施工方法、步骤及新工艺的运用;聚苯乙烯泡沫塑料板(简称苯板)防冻胀措施的采用,避免了混凝土衬砌板的冻胀破坏,大大延长了渠道的使用寿命;聚胺脂苯板伸缩缝的设置,由于在混凝土伸缩缝中镶嵌了弹性圆柱条,使聚胺脂的粘合性和延展特性得到充分发挥,既保证了混凝土板有足够的伸缩变形,又避免了聚胺脂的撕裂,减少了渠道水的渗漏损失.     

基于陶粒纤维混凝土的衬砌渠道抗冻胀性能研究

为改善北方寒区预制混凝土衬砌渠道存在衬砌板件自重大、尺寸小、装配效率低等问题,探讨将陶粒纤维混凝土用于衬砌渠道。基于正交试验法开展9组陶粒纤维混凝土和1组C35普通混凝土冻融前后力学性能试验,并结合冻胀数值模拟分析衬砌渠道抗冻胀性能变化。结果表明：陶粒纤维混凝土抗压强度因素影响次序为页岩陶粒体积取代率>聚丙烯纤维（PP）掺量>陶粒预湿时间,抗拉强度因素影响次序为PP掺量>页岩陶粒体积取代率>陶粒预湿时间,冻融后陶粒纤维混凝土抗压、抗拉强度损失率低于普通混凝土;衬砌渠道数值模拟的抗冻胀性能变化与材料性能变化趋势一致,陶粒纤维混凝土衬砌渠道抗冻胀性能损失小于普通混凝土衬砌渠道,最优抗冻胀性能损失减小4.68%,同时衬砌板重量减小18.47%;陶粒纤维混凝土作为渠道衬砌材料具有明显质轻的装配化优势。     

新型混凝土渠道接缝材料抗冻性能研究

对一种新型混凝土渠道接缝材料的抗冻性能进行了研究。经过200次冻融循环,发现不同处理的材料拉伸强度均有下降趋势,添加0%,10%,35%,55%粉煤灰的材料拉伸强度与对照比较分别下降了29%,5%,30%,25%,在材料中添加适量填料可改善材料性能,拉伸强度下降最小的材料与对照比较只下降了5%;同时材料的断裂拉伸率也有下降趋势;冻融处理后材料表面的孔隙明显变大、增多。该材料的抗冻性能优良,在我国北方地区推广应用尤为适宜。     

MgO混凝土自生体积变形过程线优

MgO微膨胀混凝土由于自生体积变形具有良好的延迟性而被工程界广泛应用，其膨胀量、膨胀时间、膨胀速率以及膨胀过程线的形态对补偿收缩的效果起着十分关键作用。通过对MgO混凝土自生体积变形的模型参数进行优化从而得到变形过程的最优曲线，达到了进一步降低拉应力的效果，为微膨胀混凝土材料的研制提供了一条目标曲线。还对自生体积变形过程线优化的初始可行点的选取进行了探讨。     

高寒地区混凝土防渗渠道伸缩缝填

高寒地区伸缩缝是砼防渗渠道的薄弱环节，漏水很容易形成集中渗流通道危及渠道安全。结合当地常用的沥青砂浆、焦油塑料胶泥、塑料油膏、聚氨酯、聚氨酯砂浆伸缩缝填料，通过对材料性能、加工方法、施工工艺、防渗效果优缺点及经济分析，总结得出适宜高寒地区不同型式不同规模防渗渠道伸缩缝填料选择，提出聚胺脂砂浆嵌缝＋苯板填充料型式，在高寒地区防渗渠道中是值得推广的填缝材料。     

高寒干旱区大型干渠伸缩缝止水材料现场试验研究

以新疆克拉玛依引水工程的风克干渠为试验依托工程,分别对PVC油膏、聚氨酯密封胶两种渠道伸缩缝止水材料的工作性能进行了现场试验。研究结果表明:聚氨酯密封胶的工作性能要远好于PVC油膏,并且在低温环境下,聚氨酯密封胶具有更好的弹塑性能和适应变形的能力;通过现场进行闭水试验和拉拔试验,可以反映出不同止水材料与混凝土的黏接性能,同时,也可间接评价止水材料适应变形的能力。     

混凝土渠道衬砌形式防渗效果试验与分析

通过对河北省石津灌区混凝土渠道的衬砌形式、结构形式、伸缩缝填充形式等采用动水法测量渠道输水损失分析,从防渗效果与投资二方面综合考虑,确定"现浇混凝土+保温板,树脂油膏砂浆填缝"形式是适合石津灌区的渠道防渗形式,为灌区节水改造工程提供理论依据。     

复合土工膜与纳米混凝土衬砌渠道冻胀模拟

兼顾材料和结构的防渗抗冻胀技术受到广泛共识,复合土工膜具有防渗性能好,适应变形能力强等优点,混凝土加入纳米微粉可大幅提高其抗渗、抗冻性能且经济合理.为了研究这两种防渗技术的有效性,以甘肃靖会总干的梯形渠道为例,采用有限元分析软件ADINA,对其进行温度场、变形场及应力场仿真分析,研究了衬砌板的冻胀变形及其法向冻胀力和切向冻胀力分布规律,并分析衬砌板的应力及破坏规律;通过与普通混凝土衬砌对比分析,指出采用纳米微粉高性能混凝土、复合土工膜柔性防渗抗冻胀技术措施不仅能使衬砌板的冻胀量及冻胀力更加均匀,而且通过柔性释放变形,可使其法向及切向冻胀力减小30%～48%,可有效控制衬砌渠道冻胀破坏,为进一步优化结构与材料组合提供借鉴.     

现浇混凝土防渗渠道施工技术探讨

目前在各地农业节水灌溉工程建设中，混凝土防渗渠道技术得到了广泛的应用，为了保证现浇混凝土防渗渠道的防渗效果和耐久性，除了正确合理地设计以外，必须严格提高施工技术水平，保证施工质量，做到优质、经济、安全。在文中，笔者根据实践经验，对现浇混凝土防渗渠道施工技术中的施工准备、混凝土的拌制运输、浇筑、伸缩缝施工、冬季施工以及施工管理等各个环节作了介绍和探讨。     

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。     

农村信息化服务的现状及建设措施

分析当前我国农村信息化服务的现状,提出加强农村信息化服务的新举措。     

车辆ABS控制算法的研究及探讨

对现代汽车的ABS控制算法作了一些简单的介绍,同时指出了它们的一些缺陷,相应地提出了几种对ABS的其它控制方法并加以探讨,其中着重论述了ABS门限值控制算法中参考车速的确定方法和基于附着系数的控制算法。