明沟排水条件下盐碱地改良优化配水模式

分析了盐碱地改良传统冲洗模式的弊端,对土壤水的盐分运动进行了活塞流简化。取对称半田面,建立了基于淡化时间的分区灌水数学模型,通过室内试验对冲洗条件下的土壤水盐运动进行了模拟分析,最后利用试验数据求解分区灌水模型得到了盐碱地改良优化配水方案。结果表明,较之传统模式,分区灌水模式下水资源用量明显减少,二分区和三分区模式比较合理,并分别确定了这二种方案最佳的分区位置。     

不同冲洗措施下迷宫流道灌水器泥沙运行分布机理研究

评估了3种冲洗流速（0.25、0.50、0.75m/s）和5种冲洗频率（2d冲洗1次、4d冲洗1次、7d冲洗1次、10d冲洗1次和无冲洗对照组）对内嵌式齿形迷宫流道灌水器抗堵塞性能的影响,利用激光粒度仪对水源泥沙、滴头排出泥沙、滴头内滞留泥沙进行级配对比和粒径分析,并对不同冲洗处理下灌水器的相对流量和灌水均匀度进行拟合。结果表明：冲洗处理对齿形迷宫流道灌水器抗堵塞性能有显著影响,12种冲洗处理提高了内嵌式齿形迷宫流道灌水器的输沙能力,使滴头使用年限平均提高了39.58%;在冲洗作用下,泥沙凝聚沉降的机会降低,流道内小颗粒泥沙及时排出,没有形成体积较大的团聚体,滴头堵塞形成缓慢,灌水均匀度和流量系数下降缓慢;冲洗处理能有效减少毛管内泥沙堆积,降低大颗粒泥沙进入迷宫流道的机率,从而提高了齿形迷宫流道灌水器的抗堵塞性能。     

冲洗压力及周期对滴灌灌水器堵塞性能的影响

为了探究不同冲洗压力及周期对灌水器堵塞性能的影响,以提高滴灌系统对含砂率较高的地表水源的适应性,采用室内短周期间歇性浑水滴灌试验,配置浑水的含砂率为3.0 g/L,研究了3种冲洗压力(0.003,0.006,0.012 MPa)和3种冲洗周期(1,4,7 d及无冲洗组)对滴头堵塞性能、管道内泥沙分布及滴头内滞留泥沙的影...     

不同排污方式下微压过滤冲洗池的泥沙处理能力研究

针对过滤器水头损失大和造价高的问题,提出了微压过滤冲洗池。对微压过滤冲洗池进行了定时冲洗和连续冲洗两种形式下的泥沙处理能力研究,试验结果表明:当含沙量范围为3.1~3.6 kg/m3时,微压过滤冲洗池的泥沙去除率都在81%以上,泥沙粒径范围为0.15~1 mm时,级效率都达到100%,中值粒径D50和粗端粒径D98由0.23、0.97 mm处理为0.058、0.125 mm左右,说明两种排沙方式下微压过滤冲洗池的泥沙处理能力相当;但微压过滤冲洗池在定时冲洗时的过滤时间为420 min,而连续冲洗式的过滤时间则为1 470 min。并分析了连续冲洗式过滤时间比定时冲洗式长的原因,提出了这两种排污方式在实际工程中应用的建议。     

二维翻转附着振动冲洗机试验控制系统设计

本位提出了附着振动和二维翻转冲洗机控制方案,选用SIMATIC S7-200PLC为核心控制器,以Weinview MT6103i P触摸屏作为人机界面设计了二维翻转附着振动冲洗机的硬件电路和软件系统,并自主研发数据采集系统实时记录压力过程值。该型冲洗机装备成功应用于生产,方案运行稳定,冲洗效果大大提升,在异形零件冲洗方面有很大地推广价值。     

滤池反冲洗技术评析

针对国内外现阶段滤池反冲洗技术的主要工艺情况，介绍了传统的水反冲洗技术及气水反冲洗技术的机理、工艺设计、存在问题和改进方式等，并对这两种技术进行了对比分析。结论认为：气水反冲洗技术具有节水、节能、反冲洗彻底及自动控制易于实现等特点，冲洗效果明显优于传统的水反冲洗技术。     

微压过滤冲洗池的污物处理能力研究

针对目前处理地表水中污物难的问题,提出了微压过滤冲洗池,并进行了动水试验。试验结果表明:微压过滤冲洗池可以处理泥沙、锯末、树叶、草籽等污物;当含沙量范围为3.1~3.6、13.9~14.4及20.6~21.1 kg/m3时,微压过滤冲洗池的过滤时间分别达到420、60、10 min时开始排污;微压过滤冲洗池的泥沙去除率在80%以上,泥沙粒径范围为0.15~1 mm时,级效率达到100%,中值粒径D50由0.23 mm变为0.058 mm左右,粗端粒径D98由0.97 mm变为0.13 mm左右,从泥沙去除率、级效率、过滤前后的泥沙粒径变化可知,微压过滤冲洗池的污物处理能力很高,过滤后的水满足灌溉需水和水质要求;水箱中的水深随过滤时间的变化规律包含3个阶段,即水深恒定、水深快速增加和水深急速增加阶段。并在试验结果的基础上,对过滤网不易堵塞的机理进行了初步分析。     

叠片式自动反冲洗过滤器的研制

对叠片式自动反冲洗过滤器的结构设计、性能测试进行了详细的阐述，该种叠片式自动反冲洗过滤器，结构设计独特，外形美观，拆装方便。性能测试表明：水头损失小，反冲洗压力低，冲洗效果好，可替代进口产品。可广泛适用于微灌系统的水质过滤，也可与自动化系统配套使用，实现过滤器的自动反冲洗。     

微灌用砂过滤器的过滤与反冲洗

对节水灌溉工程中使用的砂过滤器的过滤与反冲洗性能进行理论分析和试验研究，提出了新的过滤阻力系数与雷诺数的关系式，给出了新的计算初始水头损失公式。分析了过滤和堵塞的规律，并根据反冲洗试验结果，提出了最佳反冲洗强度和最佳膨胀率，为正确设计和使用砂过滤器提供了理论依据。     

冬暖式塑料大棚保温被整体收/放方案的尝试

对冬暖式塑料大棚的保温被进行了整体收 /放方案的尝试 ,最终实现了保温被的整体收 /放     

实物期权评价中波动率全阶段估算研究

针对现行投资评价方法的局限,建立投资项目实物期权评价模型和评判标准。分析实物期权模型中波动率参数估算方法的局限性,以净现值法为基础,提出基于蒙特卡洛模拟的全阶段波动率估算方法,解决实物期权评价投资决策难题。     

Introducing greenhouse gas mitigation as a development objective in rice-based agriculture: I. Generation of technical coefficients

This study presents a modeling tool to assess emission of greenhouse gases (GHG) from the agricultural sector as affected by land-use and residue utilization options. The overall purpose of this tool is twofold: (i) a spreadsheet model for comprehensive compilation of the direct and indirect emissions from land management, residue-burning and fossil fuel consumption through on-farm and off-farm operations and (ii) a decision support tool to explore economically viable mitigation options through detailed cost–benefit analysis of different technological options. We developed TechnoGAS (technical coefficient generator for mitigation technologies of greenhouse gas emissions from agricultural sectors), which integrates analytical and expert knowledge with regional databases on bio-physical, agronomic and socio-economic features to establish input–output relationships (‘Technical Coefficients’) related to GHG emissions in agriculture. The approach includes emissions of methane (CH₄) from rice fields, rice straw burning and cattle; carbon dioxide (CO₂) from fossil fuel and soil organic carbon decline as well as nitrous oxide (N₂O) from soil, rice straw burning and fertilizer use. To illustrate the approach of the spreadsheet model for comprehensive compilation of emissions, we applied TechnoGAS for an entire rice–wheat cropping cycle in the state of Haryana in northern India as a case study. Twenty technologies of rice production, which can be adopted by farmers, are analysed for their operation-specific emissions including their global warming potential (GWP). The technologies differ in terms of water regime, residue management/utilization, soil management and additives, which represent different mitigation options for GHG emissions. With the current farmers’ practice in various districts in Haryana, soil-borne emissions are the major source of GHG contributing 53% of the average GWP (3288 kg CO₂ equivalent ha⁻¹) in rice followed by burning of rice straw (13% of the GWP). Cattle, farm operations, off-farm and inorganic fertilizer contributes 12%, 10%, 10% and 2% of the GWP, respectively. Emissions from wheat are relatively low (1204 kg CO₂ equivalent ha⁻¹) as there is no CH₄ emission and wheat straw is not burnt. Different mitigation technologies show pronounced effects on the GWP of the rice crop and varied between 1715 kg CO₂ equivalent ha⁻¹ with continuous flooding, urea and rice straw used for building materials and 10,020 kg CO₂ equivalent ha⁻¹ with continuous flooding, and application of nutrients through organic manure. Compared to current farmers’ practice, 13 technologies are found to have the potential to reduce the GWP by 8–51%, but they also reduce the net income of farmers. Upscaling of the estimates to the entire state of Haryana shows that the GWP with the current farmers’ practice in rice is 2617 Gg CO₂ equivalent. Modification of water management from continuous flooding to alternate flooding or application of urea alone instead of urea plus FYM will reduce the GWP by 15% and 29%, respectively, while feeding of rice straw to cattle and supplying N through urea will reduce it by 41% compared to the current practice of burning rice straw and use of FYM. The study shows that the TechnoGAS tool can be used for estimating GHG emission from various land-use types and for identifying promising mitigation options. A detailed cost/benefit analysis is supplied by Wassmann and Pathak [Wassmann, R., Pathak, H., this volume. Introducing greenhouse gas mitigation as a development objective in rice-based agriculture: II. Cost–benefit assessment for different technologies, regions and scales.].     

Examining traditional irrigation methods,irrigation scheduling and alternate furrows irrigation on vertisols in northern Ethiopia

In northern Ethiopia, where traditional (farmers) irrigation management on Vertisols is widely practiced, sustainable food security has always been a challenge. The reasons for this are multi-dimensional, but of utmost importance is, low-tech irrigation water management. The main objective of the present study is, therefore, to examine technologies of irrigation water management that might enable farmers to increase water productivity (WP) on vertisols.A comparative study has been undertaken between the traditional irrigation management (every furrow-traditional scheduling) and alternative water management options on maize plots in northern Ethiopia. The options include alternate furrows-scientific scheduling and every furrow-scientific scheduling. A field experiment was undertaken over two irrigation seasons (1998/1999 and 1999/2000). Results were compared on the basis of yield, WP and economic productivity concepts.Yield-based comparison has shown that every furrow-scientific scheduling generates the highest yield levels followed by alternate furrows-scientific scheduling. The yield increase (by every furrow-scientific scheduling) over the traditional management was found to be 54%.WP-based comparison has shown that alternate furrows-scientific scheduling generates the highest WP values followed by every furrow-scientific scheduling. The increase (by alternate furrow irrigation, scientific scheduling) over the traditional irrigation management was 58%.Economic productivity-based comparison has shown that the highest economic return was obtained from every furrow-scientific scheduling followed by alternate furrows-scientific scheduling. The increase in income (by every furrow-scientific scheduling) over the traditional irrigation management was 54%.The overall observation is that depending on the availability of water and labour resources, one can decide to use either of the alternate management options to obtain economically reasonable yield. In northern Ethiopia, where water is limiting (and not labour), every furrow-scientific scheduling can be an option.     

Application of a hydraulic model for testing management decisions at distributary level

Summary This study was conducted on the Lagar Distributary of Gugera Branch of Lower Chenab Canal, Punjab, Pakistan. A computer model MISTRAL was adopted for evaluating management options. The study showed that the model can be used as a decision support tool for prioritizing management options. The model suggests that under current physical conditions of this distributary the combination of rotation between the distributaries and along the distributary canals can improve the equity of water discharge. For example, in case of Lagar Distributary the discharge of tail outlets can be increased threefold by introducing rotation between the tail of the distributary and an offtaking minor canal. A small decrease in the discharge of the minor would result from adopting this option. A combination of rotations between this and neighboring distributaries and along the Lagar itself can increase the discharge of tail outlets up to seven times. The results of the model indicate that operational changes can improve the discharge of tail outlets to some extent, but the improvement of physical conditions of the distributary is needed to achieve equity conditions, as specified in the design.     

可用性测试评估方法在车载人机界面评价上的应用研究

消费者对车内复杂功能和简单操作的需求矛盾造成车载人机界面产品普遍存在可用性问题。科学的可用性测试评估体系能帮助车载人机界面进行更人性化的设计和改进。本文研究了界面的可用性相关理论及多种可用性测试评估方法,结合车载人机界面本身特点,将可用性测试评估方法适当应用到车载人机界面的设计和改进流程中去,并针对目前市场上两类流行的车载人机界面设计进行评估,了解目前国内用户的需求与偏好。该测试评估可以帮助研发团队设计更为人性化、更符合市场需求的车载人机界面类产品。     

4YS-600型树木移栽机切铲的有限元分析

在使用中发现树木移栽机的主要工作部件切土铲会发生局部断裂的现象.为此,运用三维建模软件(Pro/E)结合有限元分析软件(ANSYS), 对其进行有限元分析,计算出切土铲的应力与变形,提出了结构改进措施.同时,对改进结构后的切土铲进行有限元分析,结果表明改进方法有效.     

Accounting for slow drainage and hysteresis in irrigation scheduling

Summary Soils continue to drain for several days following irrigation. Water budgeting predictions can be improved by accounting for this, provided hysteresis is recognized in the field capacity condition. Uncertainty in this condition was evident in experiments comparing predicted soil water depletions with neutron probe measurements. Comparisons were made for potato, lettuce and calabrese crops, irrigated by hose-reel machine. Best agreement between measurements and predictions was obtained when excess water storage above a lower field capacity condition was allowed for; corresponding to minimum root mean square errors of 3.2 mm–6.2 mm. These were comparable to the practical limits of uncertainty associated with field depletion measurements.     

农机制造业战略投资决策的实物期权分析

农业机械化是实现农业现代化的根本保证,"三农"对农机制造业产品的需求具有较大的不确定性.为此,运用实物期权方法研究不确定条件下农机制造业的战略投资决策最佳投资时点选择问题,利用案例说明在净现值大于零时立刻执行投资决策未必是最优的,投资者具有延迟期权等,克服了传统的折现现金流投资估价方法的不足.同时,对影响投资阈值的相关影响因素与多项目条件下的实物期权决策进行了分析,对投资决策具有指导意义.     

12V190发动机四气门驱动机构的设计改进与应用

分析12V190发动机,特别是以含有腐蚀性可燃气体为燃料时,其气缸盖上的四个气门驱动系统中拨叉与横桥之间易产生偏磨及机油变质、消耗过大等问题。针对以上问题,我们设计了12V190发动机四气门驱动机构的三种改进方案。通过试验比较,证明改进效果明显。三种改进方案各有优缺点,但综合比较后确定了一种改进方案,即利用一个固定导向柱和一个气门导管为定位点,限制横桥左右摆动。此方案不仅解决了12V190发动机以前存在的上述问题,而且在制造和使用方面具有良好的经济性。     

On-demand canal operation: Optimally designed

The design of most canal systems requires that they be operated under rigid schedules, rather thanon-demand. Rigid schedule operation results in water wastage through spillage, or users taking their turn even when the water cannot be efficiently used. This paper develops a two step method for optimally designing a canal system so it can be operated effectively under user on-demand requests for water. The first step determines the cross-sectional dimensions of the canal to provide storage capabilities while minimizing costs, by solving an appropriate nonlinear optimization problem. In the second step a hydraulic simulation model finds a near-optimal storage capacity based on construction and right-of-way costs, penalties due to operational water losses, water over supplied to users and supply shortages. The performance is evaluated by a quality index that is defined as the ratio of volume of satisfied demands to total volume of water requested. Results of regression equations from hundreds of computer sensitivity analyses relating variables are summarized in tables.