Performance Simulation of EHE for 300MW CFB

With the development of circulating fluidized bed boiler(CFB),the study field of external heat exchanger(EHE) is greater in extent and degree.In order to research the working process of EHE,the model which deals with flow and heat transfer of EHE for 300MW CFB of Dong Fang Boiler Grou PCo.Ltd.is presented.Based on the cell modeling theory,the EHE is divided into several chamber by heating surfaces.The mass and energy conservation equations of each cell have been developed according to some reasonable assumption.The complete mathematical model has been compiled by Fortran and solved by classical Algorithm of Runge-Kutta.The static test and perturbation experiment of simulating model has been performed.The simulation results show that the model has been reached the steady state rapidly,the dynamic responses are reasonable and the modeling presented in the paper is reliable and appropriate.     

用于直流传动控制系统的串行通讯

介绍了用Visual Basic提供的串行通讯控件，通过编程实现了PC机与应用单片机触发电路的直流传动系统的通信。     

Water Pricing and Sustainability of Self-Governing Irrigation Schemes

The sustainability of self-governingirrigation schemes is currently underpressure in many countries as publicfinancial support is decreasing.Furthermore, growing global concernregarding water scarcity means thatefficient water use is essential.Theoretically the choice and implementationof a water-pricing system should play acentral role in achieving this objective,both by recovering water costs and byencouraging farmers to adopt more efficientbehaviour. In the Senegal River Delta newlyestablished water users associations (WUAs)have chosen low water charges, which areaffordable for the majority of farmers butwhich underestimate long-term maintenancecosts. Combined with the difficulty ofcollecting and managing farmers' fees, thischoice has drawn them into a vicious circleleading to scheme deterioration and poorwater service. New alternatives have beendiscussed with them using a simulation toolthat takes into account both the watercosts and the farmers' incomes. Comparedwith the present fixed water charge basedonly on cultivated land, a two-part optionbased both on equipped and irrigated areasensures the recovery of fixed expenses suchas maintenance, while encouraging farmersto intensify their farming systems byadopting double cropping. Neverthelesschoosing a relevant water charge does notensure by itself the sustainability of anirrigation scheme. Combined supportproviding WUAS and farmers with efficientadvice regarding management andorganisational skills should alsocontribute significantly to achieve thisprime objective.     

Farmers' perception on self created water management rules in a pioneer scheme: The mula irrigation scheme, India

During the past two decades with farmer participation in irrigation management moving to center stage, the traditional view of having a centralized control over the water resources for better management has changed. Nevertheless, success of irrigation management transfer depend on a whole set of institutional arrangements or the rules-in-use and the willingness of the users to comply and enforce and/or change the rules in the light of changing circumstances. There are many institutional analyses of water sector, much of them touch on law, policy and administration, and characteristics of the users. The present paper is based on the study carried out to examine the institutional arrangements in one of the water users association that was first in the Maharashtra state. It focuses on the institutional arrangements governing water use and distribution and attempts to elicit the perceptions of the members regarding the rules-in-use. The findings reveal that the WUA has been successful in devising and enforcing the rules for water distribution, fee collection and conflict resolution for over a decade. However, current socio-economic developments such as political heterogeneity have required explicit conflict resolution mechanisms. These issues have now become issues demanding immediate attention and may be use of existing courts or legal institutions to help the WUA sustain in future.     

初乳真空冷冻干燥传热传质系数测定与分析

应用准稳态传热传质理论，在考虑水蒸气扩散对传热作用情况下，分别建立了奶牛初乳在真空冷冻干燥中多孔干燥层有效导热系数，冻结层导热系数和水蒸气扩散系数的测试模型，利用在冻干机上测取的试验数据，回归得到初乳的传热系数与水蒸气扩散系数，分析了压力与系数间的关系，结果表明，在１０Ｐａ～１２０Ｐａ范围内，干燥层有效导热系数随压力增大而增加，尤其在１０Ｐａ～６０Ｐａ范围内更为明显，而水蒸气扩散系数随压力的改变变     

Creating and Consolidating Locally Managed Irrigation in Turkey: the National Perspective

The Turkish program of irrigationmanagement transfer has gained worldwidecelebrity for its speed and effectiveness. This paper describes the program brieflyand assesses its effectiveness from anational perspective. The assessmentincludes changes in staffing levels,operational costs, service fee levels, andcost recovery from farmers. A companionpaper examines impacts at the local leveland looks specifically at changes in systemperformance.     

Performance of agency-managed and farmer-managed irrigation systems: A comparative case study at Chitwan, Nepal

Management reforms are considered one of the best alternatives in increasing efficiency of the irrigation systems. Transfer of day-to-day operation and maintenance to farmers is not a new concept. However due to lags, even now it is a hot issue in developing countries and Nepal is not an exception. In this context of growing argument about the transfer of management of public irrigation systems to the Water Users' Group, this paper examines the comparative performance of farmer-managed and agency-managed irrigation systems. Khageri Irrigation System in the Chitwan district of Nepal was taken as the study site where complete management transfer has been done in 1996. The situations before and after complete transfer were compared. Intensive case studies of the selected farmers showed that equity in distribution of water and leakage had significantly improved after management transfer. Logit analysis revealed that age and education level of the household head, distance from main canal, leakage of the canal and equity in distribution are significantly related to the satisfaction level of the beneficiary farmers from FMIS compared to AMIS. However, landholding size of the respondent farmer has no significant effect. Similarly results from t-test revealed that rice productivity and overall profits from agriculture has also increased significantly due to irrigation management transfer.