Демпфирование электромеханических колебаний в многомашинной энергосистеме с разнотипными регуляторами возбуждения

The paper cites investigation results of electromechanical oscillations in the power system where synchronous generators are equipped with various types of excitation controllers in the presence or absence of system stabilizers. Influence of every controller types on oscillation processes in the power system has been shown in the paper. The paper proposes an approach of optimum selection of setup excitation controller parameters while having system stabilizers. A complete scheme of the «Azerenergy» system has been taken as an example for an analysis of electromechanical oscillations and an influence of excitation controllers on them. Synchronous generators of the system are using excitation controllers of dramatic effect and СДП1- and UNITROL-types having a system stabilizer. Приводятся результаты исследований электромеханических колебаний в энергосистеме, синхронные генераторы которой оснащены разнотипными регуляторами возбуждения, при наличии и отсутствии системных стабилизаторов. Показано влияние каждого типа регулятора на колебательные процессы в энергосистеме. В целях усиления демпфирования колебаний предлагается подход оптимального выбора настроечных параметров регуляторов возбуждения при наличии системных стабилизаторов. Анализ электромеханических колебаний и влияния на них регуляторов возбуждения проведен на примере полной схемы системы «Азерэнержи», синхронные генераторы которой используют регуляторы возбуждения сильного действия типов СДП1 и UNITROL, содержащих системный стабилизатор.

Large-scale wind structures in OB supergiants: a search for rotationally modulated H\alpha variability

We present the results of a long-term monitoring campaign of the H\alpha line in a sample of bright OB-supergiants (O7.5-B9) that aims at detecting rotationally modulated changes potentially related to the existence of large-scale wind structures. A total of 22 objects were monitor ed during 36 nights spread over 6 months in 2001-2002. Coordinated broad-band photometric observations were also obtained for some targets. Conspicuous evidence for variability in H\alpha is found for the stars displaying a feature contaminated by wind emission. Most changes take place on a daily time-scale, although hourly variations are also occasionally detected. Convincing evidence for a cyclical pattern of variability in H\alpha has been found in 2 stars: HD 14134 and HD 42087 (periodic signals are also detected in other stars, but independent confirmation is required). Rotational modulation is suggested from the similarity between the observed recurrence time-scales (in the range 13-25 days) and estimated periods of stellar rotation. We call attention to the atypical case of HD 14134 which exhibits a clear 12.8-d periodicity both in the photometric and in the spectroscopic data sets. This places this object among a handful of early-type stars where one may observe a clear link between extended wind structures and photospheric disturbances. Further modelling may test the hypothesis that azimuthally-extended wind streams are responsible for the patterns of spectral variability in our target stars.Comment: 18 pages, accepted for publication in MNRA

The superimposed photospheric and stellar wind variability of the O-type supergiant alpha Cam

(Abridged) We provide empirical constraints on the different physical components that can act to yield temporal variability in predominantly or partially wind-formed optical lines of luminous OB stars, and thus potentially affect the reliable determination of fundamental parameters, including mass-loss rates via clumped winds. Using time-series spectroscopy from epochs spread over $\sim$ 4 years, a case study of the O9.5 supergiant $\alpha$ Cam is presented. We demonstrate that the He I 5876 (2$^3$P$^0$--3$^3$D) line is an important diagnostic for photospheric and wind variability in this star. The optical line profiles of $\alpha$ Cam are affected by (i) deep-seated fluctuations close to, or at, the photosphere, (ii) atmospheric velocity gradients, and (iii) large-scale stellar wind structure. This study provides new empirical perspectives on accurate line-synthesis modelling of stellar wind signatures in massive luminous stars. Using a pure Halpha line-synthesis code we interpret maximum changes in the red-ward and peak emission of $\alpha$ Cam in terms of mass-loss rate differences in the range $\sim$ 5.1 $\times$ 10$^{-6}$ to 6.5 $\times$ 10$^{-6}$ M$_\odot$ yr$^{-1}$. However, the models generally fail to reproduce the morphology of blueward (possibly absorptive) regions of the profiles.Comment: Accepted for pulication in A&A; 9 pages and 8 figure

Light emitting diodes (LEDs) applied to microalgal production.

Light-emitting diodes (LEDs) will become one of the world's most important light sources and their integration in microalgal production systems (photobioreactors) needs to be considered. LEDs can improve the quality and quantity of microalgal biomass when applied during specific growth phases. However, microalgae need a balanced mix of wavelengths for normal growth, and respond to light differently according to the pigments acquired or lost during their evolutionary history. This review highlights recently published results on the effect of LEDs on microalgal physiology and biochemistry and how this knowledge can be applied in selecting different LEDs with specific technical properties for regulating biomass production by microalgae belonging to diverse taxonomic groups

ЭФФЕКТИВНОСТЬ ЗОЛЕДРОНОВОЙ КИСЛОТЫ В ПРОФИЛАКТИКЕ КОСТНЫХ МЕТАСТАЗОВ У ПАЦИЕНТОВ С МЕСТНО-РАСПРОСТРАНЕННЫМ РАКОМ ПРЕДСТАТЕЛЬНОЙ ЖЕЛЕЗЫ

The analysis of the performed study has established that zoledronic acid is an effective agent in multimodality therapy for locally advanced prostate cancer (PC) and allows long-term stabilization of bone tissue. In addition, there is evidence for the efficacy of zoledronic acid in preventing bone metastases (BM) and increasing the time to the first BM. The currently accumulated experience with zoledronic acid used in PC permits one to consider its use as standard concomitant therapy.На основании анализа проведенного исследования установлено, что золедроновая кислота является эффективным препаратом в комплексной терапии местно-распространенного рака предстательной железы (РПЖ) и позволяет стабилизировать в течение длительного времени состояние костной ткани. Кроме того, подтверждена эффективность золедроновой кислоты в профилактике костных метастазов (КМ), а также в увеличении времени до появления первого КМ. Накопленный к настоящему времени опыт использования золедроновой кислоты при РПЖ позволяет рассматривать ее назначение как стандартную сопроводительную терапию