Sensitivity analysis of optimal operation of irrigation supply systems with water quality considerations     

Dani Cohen  Uri Shamir  Gideon Sinai 《Irrigation and Drainage Systems》2004,18(3):227-253

A model for optimal operation of water supply/irrigation systems of various water quality sources, with treatment plants, multiple water quality conservative factors, and dilution junctions is presented. The objective function includes water cost at the sources, water conveyance costs which account for the hydraulics of the network indirectly, water treatment cost, and yield reduction costs of irrigated crops due to irrigation with poor quality water. The model can be used for systems with supply by canals as well as pipes, which serve both drinking water demands of urban/rural consumers and field irrigation requirements. The general nonlinear optimization problem has been simplified by decomposing it to a problem with linear constraints and nonlinear objective function. This problem is solved using the projected gradient method. The method is demonstrated for a regional water supply system in southern Israel that contains 39 pipes, 37 nodes, 11 sources, 10 agricultural consumers, and 4 domestic consumers. The optimal operation solution is described by discharge and salinity values for all pipes of the network. Sensitivity of the optimal solution to changes in the parameters is examined. The solution was found to be sensitive to the upper limit on drinking water quality, with total cost being reduced by 5% as the upper limit increases from 260 to 600 mg Cl l^–1. The effect of income from unit crop yield is more pronounced. An increase of income by a factor of 20 results in an increase of the total cost by a factor of 3, thus encouraging more use of fresh water as long as the marginal cost of water supply is smaller than the marginal decrease in yield loss. The effect of conveyance cost becomes more pronounced as its cost increases. An increase by a factor of 100 results in an increase of the total cost by about 14%. The network studied has a long pipe that connects two distinct parts of the network and permits the supply of fresh water from one part to the other. Increasing the maximum permitted discharge in this pipe from 0 to 200 m³ h^–1 reduces the total cost by 11%. Increasing the maximum discharge at one of the sources from 90 to 300 m³ h^–1 reduces the total cost by about 8%.  相似文献   

基于Matlab的根系断层图像分割处理算法     

周志艳  周学成  罗锡文  李庆 《农业机械学报》2006,37(12):118-121

根据植物根系原位形态可视化研究的需要,利用Matlab提供的图像处理算法,编制了根系断层图像分割处理算法的优选整合程序,用多种不同算法组合对根系CT原位图像进行实例检验,采用最终测量精度法作为评价准则,对分割效果进行分析研究。研究结果表明,在90%的置信水平下,处理模块的不同组合顺序以及每个模块中不同算法的选择对最终分割效果有显著的影响,各因素对分割效果总变异贡献率的大小排序为分割(46.1%)、灰度调整(17.9%)、分割前滤波(4.5%)、分割后滤波(2.6%)、执行序列(0.5%)。根据所设计的实验例证,提出了处理流程及算法中的较优组合。  相似文献   

Assessing the options for upland livestock systems under CAP reform: Developing and applying a livestock systems model within whole-farm systems analysis     

K.B. Matthews  I.A. Wright  K. Buchan  D.A. Davies  G. Schwarz   《Agricultural Systems》2006,90(1-3):32-61

This paper presents a scenario-based analysis of the impacts of Common Agricultural Policy (CAP) reform for upland agriculture using a Welsh case-study. Specifically the paper examines the impacts of the introduction of the single-farm payment (SFP), the modulation of direct payments under Pillar I of the CAP and the increase in agri-environment payments under Pillar II. Three enterprises are examined, upland sheep rearing with lamb finishing, spring- and autumn-calving suckler-cattle with calf rearing. These enterprises are modelled under conditions in 2002/3, 2004/5 and for the reformed CAP in 2005/6. To support this analysis a livestock system model (LSM) was implemented. The model assesses alternative management regimen using a flexible state-transition approach. This simplifies the realisation and parameterisation of potentially complex management regimen. The model tracks fodder requirements to achieve targets based on defined diets. The LSM underpins whole-farm analyses of stocking-rates, labour and other resource requirements and net-farm income. From the case study the paper concludes that the impacts of the introduction of the CAP reform on the financial performance of the systems are small but negative (a net reduction of around 5% in support). The larger reduction in direct payments (15–18%) is partially offset by agri-environment measures. The paper concludes that while SFP encourages a more market-oriented outlook, the adaptive capacity within systems as they stand is very limited. There are a range of possible adaptation strategies, but for the uplands the extensification of cattle systems by reducing stock numbers and cutting back on labour seems most probable.  相似文献   

Towards sustainable farming systems: Effectiveness and deficiency of the French procedure of sustainable agriculture   总被引：2，自引：0，他引：2  

Mohamed Gafsi  Bruno Legagneux  Genevive Nguyen  Patrice Robin 《Agricultural Systems》2006,90(1-3):226-242

There is a widespread consensus about the importance of sustainable agriculture. In France, the Farming Orientation Law of July 1999 has set down a precise procedure for the implementation of sustainable agriculture: the contrat territorial d’exploitation – or territorial farm contract (TFC). This paper aims to analyse the TFC effectiveness. An analysis has been made of the TFCs signed in the Midi-Pyrenees Region in south-western France, using statistical analysis and qualitative surveys of a sample of farms. The results show that the most valuable effects have been mainly economic. Effects regarding social and environmental aspects were very limited. But from the point of view of an integrated approach, indirect effects of TFCs can be observed on social and environmental aspects. These results are explained, on the one hand, by farmers’ motivations guided by economic objectives, and on the other hand, by the dominance of professional farming organisations in the implementation of TFC’s procedure. Given these results, two ways of improving the elaboration procedure for TFCs are proposed. Firstly, technical improvements can be made to the diagnostic assessment of farms, and to the choice of actions addressed by the contract. Secondly, organisational improvements can be applied to TFCs elaboration and implementation process, in order to adopt a participatory approach which would involve all rural stakeholders.  相似文献   

Suitability of Multi-Agent Simulations to study irrigated system viability: application to case studies in the Senegal River Valley     

O. Barreteau  F. Bousquet  C. Millier  J. Weber 《Agricultural Systems》2004,80(3):255-275

It is assumed that Agent-Based Modeling is a useful technique for water management issues. In particular, it may provide a suitable framework for representing irrigated systems. The objective of this paper is to demonstrate its potential for a specific use: research on irrigated systems’ viability in the Senegal River Valley. The main assumption to be verified is that Multi-Agent Systems constitute a suitable architecture to study theoretically irrigated systems’ viability using simulations. By using Multi-Agent Systems, virtual irrigated systems can be designed that might then be used as virtual laboratories. These virtual labs constitute an alternative when real labs cannot exist for some reason.

In this paper we report on experiments we have conducted using such virtual labs for exploring an Agent-Based Model through the simulation of scenarios. A scenario is defined as a triplet: an environment, a set of individual rules, a set of collective rules. It is evaluated according to the longevity of the irrigated system. An index is defined, based on the ratio of long-enduring simulations among a set of repetitions of a given scenario. Even if simulation results display significant diversity for a given scenario due to random factors in the processes simulated, the ratio of long-enduring simulations is repeatable. This entails to explore the overall behavior of the virtual irrigated system and to build theories concerning the viability of Senegalese irrigated systems. An example is given showing the need for strong coherence for a given environment among individual rules and collective rules.  相似文献   

三阶开环控制系统根轨迹图形的研判     

王泽南  张鹏 《农机化研究》2002,(4):72-73

利用根轨迹极坐标方程对三阶系统根轨迹进行了研究，得出了三阶系统根轨迹的基本图形为双曲线的结论，并对图形的各种具体情况进行了进一步的讨论。  相似文献   

基于模糊评价的可重构制造系统生产计划制订方法   总被引：1，自引：0，他引：1  

金哲  杨将新  楼洪梁  宋执环 《农业机械学报》2006,37(9):123-127

为快速合理地确定可重构制造系统新构形的生产任务,提出了一种生产计划制订方法。首先建立适合可重构制造系统的产品评价指标体系,运用模糊数学的理论和方法,对市场上同时出现的多种新产品进行评价,以选出适合于制造系统新构形的生产对象。在此基础上,构建了可重构制造系统生产计划的目标规划模型,并采用序贯式算法进行求解,从而制订出可重构制造系统的最优生产计划。  相似文献   

基于VI技术的农用动平衡机测量系统   总被引：3，自引：1，他引：3  

杨健  贺世正  陈爱萍 《农业机械学报》2003,34(2):46-49

采用虚拟仪器（VI）技术设计了农用旋转机械动同测量系统，探讨了硬件和软件设计的核心技术，解决了现场可调和模块化设计、数据库管理及高速实时处理等综合问题，给出了农用碟片式胶乳分离机整机动平衡实验过程和结果。  相似文献   

Linking water market functioning, access to water resources and farm production strategies: example from Pakistan   总被引：3，自引：0，他引：3  

Jean-Daniel Rinaudo  Pierre Strosser  Thierry Rieu 《Irrigation and Drainage Systems》1997,11(3):261-280

As a response to inadequacy in canal water supplies, farmers in Pakistan have invested in private tubewells to control irrigation water resources. Also, they participate in surface water and groundwater markets that take place within tertiary units of the irrigation system.The present paper describes the functioning and organization of these water markets, using information collected in sample watercourses of the Fordwah Branch irrigation system, South-Punjab, Pakistan. The variability in type and intensity of water markets is investigated with regard to access to water resources and farm production strategies and constraints.  相似文献   

生活污水厌氧消化出水后处理技术研究进展     

夏邦寿  胡启春 《中国沼气》2007,25(1):23-26

本文综述了生活污水厌氧消化系统相关后处理技术的技术特点和研究进展,着重分析了好氧处理、稳定塘处理及土地处理三种后处理技术方法,简要介绍了户用一体化装置的研究及应用状况。  相似文献