Value-based transmission planning and the effects of network models

A value-based automated transmission system planning model is presented in this paper and the impact of the various network representations on the results of the model is discussed. Value-based integrated resource planning provides a “societal cost” (utility operation and investment costs plus customer outage costs) minimizing composite generation-transmission system expansion plan. The model trades-off and compares the costs and benefits of alternative generation and transmission resources using a consistent economic and engineering criterion in order to determine an “optimal” resource expansion plan. The generalized Benders decomposition algorithm with “importance sampling” used to solve the problem enables the model to estimate certain average information about scenarios or contingencies by examining only a very small fraction of all the scenarios or contingencies. The impacts of system resources upon both real and reactive power can be analyzed when using the AC power flow equations. It is concluded that for transmission system planning where reactive power flows and voltage constraints are important, it is imperative that an AC power flow model be used. The combination of AC power flow and linearized power flow models, with linearization about the solution of the AC power flow model, was found to be a promising compromise between accuracy and computation time     

Design and simulation of waveguide electrooptic beam deflectors

Numerical simulation based on the scalar beam propagation method, was used to investigate the performance of waveguide electrooptic beam deflectors. The deflectors under investigation consist of a stack of electrooptically controlled prisms in a waveguide. The results were compared to earlier simplified analysis. It was found that for given overall device dimensions, the number of interfaces between prisms in a prism-type electrooptic deflector has significant influence on the device performance when it is small. To avoid wavefront distortion, unwanted reflection from the interfaces, and asymmetry in the deflection angles caused by small number of interfaces, one should use more than about ten interfaces in a typical deflector. Additional insights of device operation and design issues are discussed     

Synthesis of silicon carbide whiskers using the vapour-liquid-solid mechanism in a silicon-rich droplet

SiC whiskers can be produced from 1350–1500 °C by carbothermal reduction of the silica in a fixed bed percolated by a hydrogen flow. At 1450 °C and above, the addition of iron to the silica-carbon mixture leads to the formation of submicrometre whiskers in the bed, ending with a silicon-rich droplet. The iron has evaporated and condensed at a lower temperature, a few centimetres downstream from the bed, allowing the formation of silicon carbide whiskers ending with an iron droplet according to the vapour-liquid-solid (VLS) mechanism. Submicrometre whiskers are also obtained without iron over a broader range of temperatures. Silicon carbide whisker production in a fixed bed is then possible using a (VLS) mechanism in a silicon-rich droplet and may be controlled without the addition of transition metals, thus improving the purity.Supported by Pechiney Electrometallurgie and the European Communities, Brite project RIIB.A267C.     

Portosystemic shunt in Budd-Chiari syndrome: long-term survival and factors affecting shunt patency in 25 patients in Western countries

BACKGROUND: In Budd-Chiari syndrome (BCS) treated by portosystemic shunt, postoperative shunt thrombosis is associated with high morbidity and mortality rates. The aim of this study was to determine factors associated with shunt thrombosis. METHODS: From 1985 to 1991, 25 patients underwent portosystemic shunt for BCS. According to the patency of the shunt during the postoperative period and follow-up, patients were divided into two groups including 17 patients with patent shunt and 8 (32%) with shunt thrombosis. RESULTS: In patients with patent shunt, actuarial survival rate at 5 years was 87% versus 38% in patients with shunt thrombosis (p < 0.05). Duration of symptoms before operation was higher in patients with shunt thrombosis than in patients with patent shunt (315 +/- 483 vs 109 +/- 168 days, p < 0.05). In patients with patent shunt, extensive fibrosis or cirrhosis was observed in 3 of 17 (18%) versus in 5 of 8 (63%) of patients with shunt thrombosis (p < 0.05). Shunt thrombosis was observed in 3 of 3 patients (100%) with the combination of myeloproliferative disorder, duration of symptoms more than 100 days, and cirrhosis versus 0 of 6 (0%) patients without this combination (p < 0.05). CONCLUSIONS: In acute form of BCS (with short history of the disease and absence of extensive fibrosis or cirrhosis), early portal decompression is mandatory, with low risk of shunt thrombosis and good long-term results. In chronic form of BCS, the risk of shunt thrombosis is high and long-term results are bad; in these patients, orthotopic liver transplantation must be considered.     

Chemical activation of the SHS process in the Nb−C system

The phenomenon of chemical activation is investigated using combustion of the Nb–C system in the presence of an activating additive, namely, polytetrafluoroethylene, as an example. Regions of the parameters of the process are found where the interaction occurs by two different mechanisms. The characteristic features of the process are established and the role of the activating additive in each region is determined.Institute of Chemical Physics, Academy of Sciences of Armenia, Yerevan. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No.5, pp.590–593, November, 1993.     

Facilitating communications

How often have you felt that the person you were talking to was speaking another language? How often have others seemed bewildered when you described something? We may attribute this to technical jargon or new terminology, but the problem more likely stems from basic communication failure. Since effective communication is essential to a project's success, learning to communicate successfully should be a top priority for anyone in a technical field. The author discusses the Myers-Briggs Temperament Indicator (MBTI) which can help us understand how natural preferences for gathering information and making decisions shape communication styles. All personalities have value in every organization. Building and maintaining information systems requires many distinct and specialized skills and roles, and each tends to attract a certain personality. To create a comfortable setting for all personality types, you must foster good communication among them     

New theoretical concept of thin electromagnetic wave absorber usingresonant and scattering effect of dielectric and magnetic materials

Thin electromagnetic absorber such as less than 2~3 mm will be required for wireless LAN for domestic and business use together with millimeter wave broadcasting in the future. To make a thin construction, many resonators with lossy material were used. This paper present theoretical results that are useful for absorber designs     

Regional differentiation of blood group frequencies in the Polish population

The paper presents frequency distributions of alleles of eight blood group systems (ABO, MN, Rh, Hp, Gm(a), AcP, PGM1, EsD) in the Polish population. The blood group determinations concerning 10521 individuals (were carried out during paternity testing in regional serological laboratories throughout the country). Detailed information on the place of residence for all the subjects was also available. Blood group frequencies of subjects living in five regions of Poland were compared with historical date. The analysis has shown an almost complete disappearance of genetic variability in respect of the analysed traits between local populations inhabiting various regions of Poland.