Experimental investigation on the wake interference among wind turbines sited in atmospheric boundary layer winds

We examined experimentally the effects of incom-ing surface wind on the turbine wake and the wake interfer-ence among upstream and downstream wind turbines sited in atmospheric boundary layer (ABL) winds. The experi-ment was conducted in a large-scale ABL wind tunnel with scaled wind turbine models mounted in different incom-ing surface winds simulating the ABL winds over typical offshore/onshore wind farms. Power outputs and dynamic loadings acting on the turbine models and the wake flow char-acteristics behind the turbine models were quantified. The results revealed that the incoming surface winds significantly affect the turbine wake characteristics and wake interference between the upstream and downstream turbines. The velocity deficits in the turbine wakes recover faster in the incoming surface winds with relatively high turbulence levels. Varia-tions of the power outputs and dynamic wind loadings acting on the downstream turbines sited in the wakes of upstream turbines are correlated well with the turbine wakes charac-teristics. At the same downstream locations, the downstream turbines have higher power outputs and experience greater static and fatigue loadings in the inflow with relatively high turbulence level, suggesting a smaller effect of wake inter-ference for the turbines sited in onshore wind farms.     

Efficiency and sustainability assessment for a group of farmers in the Brazilian Amazon

The aim of this paper is to use DEA models to evaluate sustainability in agriculture. Several variables are taken into account and the resulting efficiency is measured by comparison. The performance of family farms is analysed here (variables: farmed area, work force, and production). As agricultural sustainability depends on the maintenance of systems of production for long periods of time, the models were run for the years of 1986 and 2002. Tiered DEA models were used to group farmers in sustainability categories. Non-parametric regression models were used to identify the factors affecting the efficiency measurements. All the results indicate that the majority of the farmers increased their efficiency along the time. These improvements may support the existence of sustainability.     

A mixed-method optimisation and simulation framework for supporting logistical decisions during offshore wind farm installations

With a typical investment in excess of £100 million for each project, the installation phase of offshore wind farms (OWFs) is an area where substantial cost-reductions can be achieved; however, to-date there have been relatively few studies exploring this. In this paper, we develop a mixed-method framework which exploits the complementary strengths of two decision-support methods: discrete-event simulation and robust optimisation. The simulation component allows developers to estimate the impact of user-defined asset selections on the likely cost and duration of the full or partial completion of the installation process. The optimisation component provides developers with an installation schedule that is robust to changes in operation durations due to weather uncertainties. The combined framework provides a decision-support tool which enhances the individual capability of both models by feedback channels between the two, and provides a mechanism to address current OWF installation projects. The combined framework, verified and validated by external experts, was applied to an installation case study to illustrate the application of the combined approach. An installation schedule was identified which accounted for seasonal uncertainties and optimised the ordering of activities.     

基于模糊AHP建构休闲农业营销绩效评价模式之研究

目的是以台湾地区休闲农场为研究对象,首先以德尔菲法,结合许多专家意见来建立休闲农业在营销评价指针项目,并以平衡计分卡观点,建构休闲农业绩效评估因素,接着利用模糊层级分析法分析出休闲农场在营销服务方面相关因素及权重比,并推导各因素构面重要性及大小顺序,提供业者作为一有效经营参考指标.研究结果显示:休闲农业营销绩效评价指标有3项一级指标(主构面),14项二级指标(次构面).在一级评价指标当中,依序为游客满意度(0.564)、游客贡献度(0.247)、休闲农场对游客吸引力(0.189).在对应于一级指标中,各二级指针最重要项目分别为:年度游客量(0.086)、服务满意度(0.116)、年净利润(0.154).而依两层级串联后权重值×100得知,14项指标中最重要的前三项分别为:游客对休闲农场人员服务满意度(6.543)、整体环境满意度(4.738)、餐饮满意度(5.584).     

Research progress on interference in the detection of pollutant gases and improving technology in livestock farms: A review

With the intensive development of large-scale livestock industry, the gas emissions from livestock farms were identified as a major problem. Many greenhouse gases and odorous gases are generated from animal exhalation, ruminant fermentation, livestock waste, and other factors. Considering the environmental impact brought by pollutant gas emissions, it is important to determine how it contributes to total emissions accurately in order to minimize it. This article gives a comprehensive overview over the non-spectroscopic techniques and spectroscopic techniques applied to air quality assessment in livestock. In addition, this review summarizes interferences in the detection process, emphasizing different interference reduction approaches for improving the performance of current detection technologies used in livestock farms.