n the single feedbac

t output voltage when the load changes are within its normal range.solid oxide fuel cell(SOFC),automatic control technology,output voltage control,feedforward-feedback cont     

名利场宠儿 Execs and the city

宝马3系向来是小型行政车型追随者的唯一选择。不过，新款奥迪A3三厢版和奔驰CLA将与宝马3系一起角逐小型行政车市场，其中，奔驰CLA拥有如跑车一般圆润的流线型外观，而奥迪A3则在售价方面占有优势。新款雷克萨斯IS采用油电混动系统，能够输出更大动力，并且二氧化碳排量比其他竞争车型更低。     

各显神通 500 hits the big time

对于一款优秀的MPV而言，实用性固然重要，但操控感、舒适性和较低的用车成本同样必不可少.     

Bad for the environment, good for the farmer? Urban sanitation and nutrient flows

Due to poor urban sanitation farmers in and around most cities in developing countries face highly polluted surface water. While the sanitation challenge has obvious implications for environmental pollution and food safety it can also provide ‘free’ nutrients for irrigating farmers. To understand the related dimensions, a box-flow model was used to identify the most important water and nutrient flows for the Ghanaian city of Kumasi, a rapidly growing African city with significant irrigation in its direct vicinity. The analysis focused on nitrogen and phosphorus and was supplemented by a farm based nutrient balance assessment. Results show that the city constitutes a vast nutrient sink that releases considerable nutrients loads in its passing streams, contributing to the eutrophication of downstream waters. However, farmers have for various practical reasons little means and motivation in using this resource of nutrients. This might change under increasing fertilizer prices as the nutrient load will continue to increase by 40% till 2015 assuming a widening gap between population growth and investments in water supply on one side and investments in sanitation on the other. However, even a strong investment into flushing toilets would not reduce environmental pollution due to the dominance of on-site sanitation systems, but instead strongly increase water competition. Key options to reduce the nutrient load would be via optimized waste collection and investment in dry or low-flush toilets. The latter seems also appropriate for the city to meet the water and sanitation Millennium Development Goals (MDGs) without increasing water shortages in toilet connected households.     

Survival of the fittest—genetic algorithms versus evolution strategies in the optimization of systems models

The use of numerical optimization techniques on simulation models is a developing field. Many of the available algorithms are not well suited to the types of problems posed by models of agricultural systems. Coming from different historical and developmental backgrounds, both genetic algorithms and evolution strategies have proven to be thorough and efficient methods in identifying the global optimum of such systems. A challenging herd dynamics model is used to test and compare optimizations using binary and real-value genetic algorithms, as well as evolution strategies. All proved successful in identifying the global optimum of this model, but evolution strategies were notably slower in achieving this. As the more successful innovations of each of these methods are being commonly adopted by all, the boundaries between them are becoming less clear-cut. They are effectively merging into one general class of optimization methods now termed evolutionary algorithms.     

How does research address the design of innovative agricultural production systems at the farm level? A review

In trying to respond to societal demands for sustainable development, farming systems worldwide face a range of environmental, technical and economic challenges. These challenges call for renewed methodologies that can be used to support farmers in designing innovative agricultural production systems at the farm level. This paper aims to analyze the various methods described in scientific literature. The review is based on the analysis of 80 reference papers published in international scientific journals between 1999 and 2010. We focused in particular on the purpose of the research, which fell into two broad categories: “design” and “design support”. We also examined the use of models to represent production systems and to evaluate ex-ante the impact of innovations on these systems’ functioning and performance. In so doing, we developed a classification system to organize the studies into five sub-categories according to the type of methodology followed, namely: prototyping and design modelling for design orientated studies; participation, support modelling and advisory for design-support orientated studies. We found that very few studies attempt to address the three main components of an innovation process in agricultural production systems (biotechnical processes, farm management, and advisory services) within a single research framework. We therefore developed such a framework by connecting the design and design support orientations together with biotechnical research and conducting integrated research both at farm and advisory service levels.     

Factors influencing the stability of salt affected soils in the UK—criteria for identifying appropriate management options

Changes in agricultural practices that brought about deflocculation problems on salt affected alluvial soils in eastern England are outlined. The spatial variation in the occurrence of problems is discussed. Exchangeable sodium percentage (ESP) was found to be the factor having greatest influence on soil stability as measured by the dispersion ratio. Changes in ESP had similar effects on the stability of soils from Essex and Kent. Threshold ESP of 5% for topsoils and 10% for subsoils are suggested, above which deflocculation problems can be expected. The use of these thresholds as part of the process for identifying future management options is discussed.     

Social capital and farming at the rural–urban interface: the importance of nonfarmer and farmer relations

Because of growth and development in agricultural areas at the rural–urban interface, a variety of farmer adaptations have been identified. While exiting from farming or entrepreneurial adaptations that tap urban markets are frequently identified responses, farmers might also attempt to develop social capital, or neighborly relations, with nonfarm neighbors to mitigate social constraints created by nonfarmer concerns at the rural–urban interface. In a case study of an agricultural region within a large metropolitan area, this research reports data from a survey of farm and nonfarm residents (N=620). The analysis operationalizes the concept of social capital, nonfarmer trust of farmers and frequency of nonfarmer interaction with farmers, to determine whether these social relations have a discernable impact on nonfarmer support or tolerance of agriculture. Results reveal a relationship, indicating that support and tolerance of agriculture is stronger when nonfarmers report the existence of social capital with farmers. These findings have implications for farm operator adaptations as well as community capacity to preserve or develop local agriculture.     

Does the adoption of zero tillage reduce greenhouse gas emissions? An assessment for the grains industry in Australia

The Australian Government has recommended that farmers move from cultivation-based dryland farming to reduced or zero tillage systems. The private benefits could include improvements in yields and a decrease in costs while the public benefits could include a reduction in greenhouse gas (GHG) emissions due to a diminution in the use of heavy machinery. The aim of this study is to estimate and compare total on-farm GHG emissions from conventional and zero tillage systems based on selected grain crop rotations in the Darling Downs region of Queensland, Australia. The value chain was identified, including all inputs, and emissions. In addition, studies of soil carbon sequestration and nitrous oxide emissions under the different cropping systems were reviewed.The value chain analysis revealed that the net effect on GHG emissions by switching to zero tillage is positive but relatively small. In addition though, the review of the sequestration studies suggests that there might be soil-based emissions that result from zero tillage that are being under-estimated. Therefore, zero tillage may not necessarily reduce overall GHG emissions. This could have major implication on current carbon credits offered from volunteer carbon markets for converting conventional tillage to reduced tillage system.     

Agricultural intensification in the Sahel – The ladder approach

Agricultural intensification in the Sahel can be described as climbing a ladder. The capital, labour, management and institutional requirements increase when farmers climb the ladder, but the potential gains are also higher. The first step on this ladder are agricultural practices without any financial outlay but with increasing labour demand, such as organic fertilizer use, seed priming, water harvesting and harvesting grains at physiological maturity to improve fodder quality. The next step on the ladder is the use of micro-fertilising, popularly known as microdose, at the rate of 0.3 g NPK fertilizer per pocket in sorghum and millet. The following step is the development of improved crop/livestock systems characterized by use of higher rates of mineral fertilisers and manure, increasing cowpea density and improved animal fattening. The last step presented on the ladder is the development of more commercially orientated agriculture characterized by development of cash crops, milk production and/or agroforestry systems. Evidences from the field support the observation that farmers intensify their production in a sequential manner similar to the way described in this paper. The technologies presented can facilitate agricultural intensification by reducing the risks and minimising the cost in agricultural production.     

Vibration analysis of the fluid-structure  interaction in water hammer

In consideration of the problem that the effect of conduit structure on water hammer has been ignored in the classical theory, the Poisson coupling between the fluid and the pipeline was stu died and a fourteen equation mathematical model of fluid-structure interaction (FSI) was developed in this paper. Then, the transfer matrix method (TMM) was used to calculate the modal frequency, modal shape and frequency response. The results were compared with that in experiment to verify the correctness of the TMM and the results show that the fluid-structure coupling has a greater impact on the modal frequencies than the modal shape. Finally, the influence on the response spectrum of diffe rent damping ratios was studied and the results showed that the natural frequency under different dam ping ratios has changed little but there is a big difference for the pressure spectrum. With the decrease of damping ratio, the damping of the system on frequency spectrum is more and more significant and the dispersion and dissipation is more and more apparent. So the appropriate damping ratio should be selected to minimize the effects of the vibration of the FSI.     

Introduction to the Faculty of Agricultural Engineering,Northeast Agricultural University

The predecessor of the Faculty of Agricultural Engineering is the former Department ofAgricultural Mechanization founded in 1 948.Itconsists of four departments,including DepartmentofMechanization Engineering,Department of Electronic Engineering,Department of Computer Scienceand Technology and Department of Engineering Technology.The Faculty offers Bachelor Degree in Agricultural Mechanization and Automation,MachineDesign,Production and Automation,Agricultural Electronic Engineerin…     

Asset Management for Irrigation Systems – Addressing the Issue of Serviceability

This paper advocates the need for defining criteria for level of service provision for irrigation networks and outlines a proposed Irrigation Serviceability Matrix to be used in the preparation of asset management plans and investment strategies for irrigation infrastructure. The development of the Irrigation Serviceability Matrix is based on experienced gained in the UK by the privatised water industry where the level of service provision to customers has become a key determinant for investment in infrastructure. The paper describes the evolution of this process within the UK water industry and its application to the irrigation sector.     

A bio-economic model of small-ruminant production in the semi-arid tropics of the Northeast region of Brazil: Part 2—Linear programming applications and results

Survey data covering production systems for mixed farms in the Northeast region of Brazil has been synthesized within a linear programming (LP) framework. The resulting model contains activities covering the production of cattle, sheep and goats, and a vector of alternative cropping activities. Farm resources include two categories of grazing land, planted forages, family labour, two categories of hired labour, and working capital. The major livestock activities represented in the region were included as production options.Initial results did not discriminate between categories of available grazing resources. Therefore, cattle, by virtue of their higher dressing percentages and higher price per kilogram, were the optimal livestock species. A series of adjustments was then carried out to reflect types of feed resources and patterns of animal species selectivity. Optimal farm solutions for a representative traditional-production unit found objective function levels close to those found by farm surveys, but discrepancies between model results and the actual farm situations for sheep and goat activities. Model results excluded small-ruminant breeding activities because of the low net offtake at weaning levels assumed in the model. Data that became available after these initial model runs showed a higher net offtake level, and these revised coefficients resulted in optimal LP results very close to those actually found on farms.The model was then used to simulate the response of activities and farm economic performance to ‘good’ and ‘bad’ years defined by ± half standard deviation from mean annual levels of precipitation. Model results indicated much higher variability of farm income in response to weather than that found with changes in levels of technical efficiency of sheep and goat production.     

Introduction to the College of Engineering and Technology,Huazhong Agricultural University

The College of Engineering and Technology at Huazhong Agricultural University was set up on thebasis of the former Departmentof Agricultural Engineering in1 997under the ratification ofthe Ministry ofAgriculture.The college now has 71 staff members including 6professors,2 3associate professors,and 2senior engineers.Two of them won the award of the young and middle aged experts with outstandingachievements and1 2 were awarded the special allowance.Among all the academic staff,5 1 % ( 2 3) h…     

Introduction to the College of Vehicle & Motive Power Engineering,HUST

Henan University of Science & Technology(HUST) is located in the fam ous ancientcity of L uoyang,an ancient Chinesecapital of nine dynasties with a lot of historic and cultural m onum ents.L uoyang is also a m odern industrial city.HU STpossesses a variety of disciplines and covers 8fields including engineering,economics,law,liberal arts,m anagem ent,naturalscience,medicine and agronomy. Its scale and overall capabilities rank at the forefront am ong the universities in Henanprovince. HU…     

Is IWRM achievable in practice? Attempts to break disciplinary and sectoral walls through a science-policy interfacing framework in the context of the EU Water Framework Directive

The word ‘integrated’ is prone to different interpretations in relation to various disciplines and sectors. When approaching operational water management, one would dream that integration would encompass effective links between scientific disciplines and technical features, with a good knowledge of interactions among different environmental compartments (land/water, terrestrial/coastal, surface/groundwater etc.), of pollution pathways, of various pressures and impacts (including from climate change) etc. The world of management effectively involves many different actors, representing different economic sectors (e.g. agriculture, industry), the civil society, stakeholder organisations, including the representation of citizens, and it is often (wrongly) thought that any kind of decision-making is carried out in an agreed and harmonious way. The theory is at least paved through IWRM principles as they are conceived within the framework of the EU Water Framework Directive (WFD), so we might say that we have actually no choice but to make it work!! But what is the reality in practice? The difficulty is to consider mandatory policy obligations on the one side, technical feasibility and scientific knowledge on the other side, and reflect whether and how these can be properly interfaced. This has been the subject of dynamic discussions within the past 6 years in the framework of EU-funded research projects aiming to support policy WFD developments and implementation. One of the key conclusions of these discussions among scientists, policy-makers and stakeholders underlined the need to develop a conceptual framework for a science-policy interface related to water, which would enable to gather various initiatives and knowledge. This paper discusses on-going developments in this field with an European perspective.     

面向全生命周期的信息化项目管理系统设计探究Research on the Design of Information Project Management System for the Whole Life Cycle 北京市数字农业农村促进中心

信息化项目的全生命周期包含从信息化规划、项目申报、立项、实施到最终验收以及后续运维等一系列过程,随着信息化项目的日趋复杂,对信息化项目管理的内容和形式也都提出了更高的要求。本文阐述了系统的设计原则、需求分析及技术体系架构等方面的内容,系统满足农业信息化项目过程管理、项目文档管理的业务需求和功能需求,提高了市农业农村局信息化项目的管理效率。     

Grapevine cv. ‘Riesling’ water use in the northeastern United States

Vine water use was measured in a Vitis vinifera cv. Riesling vineyard located in New York. Vines were fully irrigated and were trained via vertical shoot positioning giving a narrow curtain intercepting about 30% of the incident light during the sunlight hours. Vine water use was estimated on six vines by sap flow gauges directly calibrated with whole canopy transpiration measurements. The regression analysis between estimates of transpiration showed that there were large differences between vines in the calibration values obtained. Sap flow monitoring started late in June, about 2 weeks after bloom, when the canopy already filled the trellis system, and continued until October. Results showed that vine water use during most of the summer days was between 1.0 and 2.0 mm day⁻¹, with peak values around 2.5 mm. The basal (e.g. vine transpiration/reference evapotranspiration) crop coefficient (K _cb) varied somewhat between days, but it was quite stable during the whole season. Averaged over the entire experimental period, the K _cb was 0.49. Some of the day-to-day variation in the K _cb was negatively related with daily average air vapour pressure deficit. This suggests that reference evapotranspiration models on grass may not be fully accurate for vines under these experimental conditions.