Capacity factor of wind power realized values vs. estimates

For two decades now, the capacity factor of wind power measuring the average energy delivered has been assumed in the 30–35% range of the name plate capacity. Yet, the mean realized value for Europe over the last five years is below 21%; accordingly private cost is two-third higher and the reduction of carbon emissions is 40% less than previously expected. We document this discrepancy and offer rationalizations that emphasize the long term variations of wind speeds, the behavior of the wind power industry, political interference and the mode of finance. We conclude with the consequences of the capacity factor miscalculation and some policy recommendations.     

SKD61钢的热处理工艺和性能研究

热作模具钢SKD61通常用作铝、镁合金压铸模。采用不同工艺对这种钢进行淬火、回火,然后测定不同组织状态的硬度和冲击韧度,用扫描电镜分析冲击断口的形貌。结果表明,淬火温度对钢的硬度影响较大,当淬火温度高于1100℃时,钢的组织粗大,晶界粗化,冲击韧度明显降低。经1040℃淬火和590℃回火的SKD61钢具有较好的冲击韧度和较高的硬度。     

自孕育法制备AZ61镁合金的微观组织

采用AZ91D镁合金母液与纯Mg熔体混合的自孕育法制备AZ61镁合金半固态坯料,研究了液-液熔体混合和导流.器角度改变对AZ61镁合金组织的影响.试验结果表明:液-液混合熔体经导流器浇注到铸型中后,可以使AZ61镁合金组织明显细化.相比未混合制备的AZ61,熔体混合有利于能量起伏、结构起伏、浓度起伏,增加有效形核,使晶粒细化;经倾斜导流器激冷、冲刷进一步细化晶粒,同时熔体流经导流器产生的二次混合又促进了有效形核,使平均晶粒尺寸大幅减小(约50％).随导流器角度增加,组织有粗化的趋势,但影响不大.     

基奇CXA1191和SHT11的无线温湿度监测系统

为降低设计成本,利用CXA1191和SHT11实现了一个无线温湿度监测系统。在CXA1191原有的广播接收功能的基础上,巧妙结合编码技术,成功实现了数据无线传输功能,并选择SHT11实现高性能的温湿度采集。系统的特色在于将成熟的广播接收技术与数字技术相融合,具有较高的性价比,很好地满足了无线温湿度数据采集需求。     

A bi-level programming model for the land use – network design problem

A sketch map in urban planning roughly lays out a physical plan. However, the process of generating sketches has long been viewed as a “black box”. The sketch layout model (SLM) was developed in 1999 to improve the efficiency and quality of layout tasks. This model is a nonlinear and multi-objective programming, for analyzing the integrated layouts of land uses, transport network and public facilities. Although the SLM had been developed for three phases and can be applied to real cases, the method still does not distinguish the types of roads in the transport network. This study develops the SLM-IV, a bi-level programming, by integrating the SLM-III and the combined trip distribution/assignment model, to generate a hierarchical network. This improved model can analyze travel demands, and then decide the link type of the network in SLM. A numerical example with relevant sensitivity analysis is presented to verify the operational feasibility and identify the model's characteristics. Received: June 2001/Accepted: June 2002 The authors would like to thank the referees and the editor for their helpful suggestions and assistance on the earlier version of the paper. This study was financially supported by the National Science Council in Taiwan (project no: NSC89-2415-H-009-001-SSS).     

A multiple gap approach to spatial economics

In previous work investment and regional location have been analysed in terms of gaps or thresholds that should be closed or passed in order to produce operational results (growth, local development).  The topic is taken up again using a min-algebra which, at least to the knowledge of the author, has not yet be applied to (theoretical) spatial economics, though max-plus algebra has been used to tackle scheduling problems.  Examples of multiple gap situations will be given, together with their econometric implications; min-algebra will be defined, and examples of its applications worked out; topics for further research will be presented in conclusion. Received: October 2000/Accepted: September 2001     

Consumer choice and optimal locations models: Formulations and heuristics

A new direction of research in competitive location theory incorporates theories of consumer choice behavior in its models. Following this direction, the present article studies the importance of consumer behavior with respect to distance or transportation costs in the optimality of locations obtained by traditional competitive location models. We consider various ways of defining a key parameter in the basic maximum capture model (MAXCAP). This parameter will indicate a number of ways to take distance into account based on several consumer choice behavior theories. The optimal locations and the deviation in demand – captured when the optimal locations of the other models are used instead of the true ones – are computed for each model. We present a metaheuristic based on GRASP and the tabu search procedure to solve all the models. Computational experience and an application to a 55-node network are also presented. Received: 12 June 1998 / Accepted: 29 July 1999