Probabilistic Wind Farms Generation Model for Reliability Studies Applied to Brazilian Sites

This paper presents a computer model for the probabilistic representation of wind farms generation for reliability studies, which can provide an annual estimation of energy production and calculate several performance indexes. The model combines the stochastic characteristics of wind speed with the operational information of the turbines, such as the failure and repair rates, representing the wind farm by a Markov process. The simulations are made with real time series of wind speed of several Brazilian regions and actual turbine models. The influence of some wind farm and installation site characteristics on the results are evaluated, such as the wind speed statistical clustering technique, the number and type of the turbines, and the failure and repair rates. The results obtained reproduce successfully the behavior of the components considered in the model     

Electric arcing burn hazards

The paper presents recent results in the area of high-power testing aimed at improving the safety of electrical staff working on live equipment. The driver for this work is the American Guide (IEEE 1584) on such exposure hazards, which has the potential for international adoption and, in the authors' opinion, does not provide a suitable methodology for assessing the hazard. A selection of results is presented, obtained in a high-power-system-supplied commercial test laboratory, using the latest charge-coupled device (CCD)-based high-speed video-recording methods. Results are reported for 415-V currents in the range of 1000-70 000 prospective root mean square (rms) amperes and for tests at 5000 V in the range of 1000-27 000 A. The impact of conventional protective devices is included together with some disturbing video results for circuit-breaker-protected systems. The major part of the material in this paper was first presented at the 7th International Conference on Electric Fuses and Their Applications, Jurata, Poland, in 2003.     

Point/Counterpoint

POINT: AOP Will See Widespread Adoption Adrian Colyer, Rob Harrop, Rod Johnson, and Alexandre Vasseur AOP offers both the short--and long-term return on investment needed to ensure its widespread adoption. COUNTERPOINT: AOP Has Yet to Prove Its Value Danio Beuche and Cédric Beust Where is the proof that nonhierarchical modularization into aspects makes systems development cheaper or better?     

Software architecture-centric methods and agile development

The agile software development paradigm and plan-driven approaches each have their strengths and shortcomings. The former emphasizes rapid, flexible development, while the latter emphasizes project and process infrastructure. Many practitioners, particularly of agile methods, tend-to view software architecture in light of the plan-driven side of the spectrum. They think that architecture-centric methods are too much work, equating them with high-ceremony processes emphasizing document production. But many elements make up a successful development approach, including process, product, technology, people, and tools. Software architecture is part of product quality and isn't tied to a particular process, technology, culture, or tool. This article explores the relationship and synergies between architecture-centric design and analysis methods and the extreme programming framework. We chose to focus on XP because it's one of the most mature and best-known agile practices.     

Long-term testing and applications of high-stress MV EPR cables

High-stress design 35-kV ethylene propylene rubber (EPR)-insulated cables with 1.14-mm (45-mil) wall reduction have been in service for more than ten years. In the mid 1990s, an extensive cable testing program was initiated to demonstrate that high-stress designs up to 4 kV/mm (101.6 V/mil) exhibit a significant electrical and mechanical safety margin to operate on typical utility network systems. Investigations were also undertaken to demonstrate the suitability of accessories for high-stress designs. This paper will present the results of six-year, long-term wet electrical testing conducted to demonstrate that with proper design, the aging performance of standard wall and high-stress design cables provide satisfactory results and suitable performance for the intended application. Additionally, utility field experience is presented on 35- and 15-kV cables operating at high stress. The experience for these 15-kV medium-voltage EPR cable designs employ the highest recommended stress for cables of this class, as well as taking into account the complete system performance.     

The herbicide propachlor--14 C synthesis, toxicologic problems and methodology studies on the determination of residues in corn, potatoes, water and soil

Using the synthesized agent propachlor (N-isopropyl-2-chloroacetanilid) labelled with 14C, methodical investigations revealed an extremely high steam volatility not being assumed before because of the low vapour pressure. The method of steam distillation basing on this fact is of universal application to the processing of maize, potatoes, water, and soil, in which propachlor could be quantitatively determined by gas chromatography with a detection sensitivity of 0.02 ppm. Furthermore, this methods allows a simple purification of the raw product of synthesis containing impurities up to 20%. Propachlor codistilled with steam had a purity of more than 99%. Possibly, the high steam volatility of propachlor could have economic and toxicological consequences as to its application (volatilization in the open air with a high atmospheric humidity along with high temperatures). Therefore, an investigation of the steam volatility in the general screening programme for new agents is to be recommended in addition to the usual investigations of steam pressure.