Theoretical description of hydrogen bonding in oxalic acid dimer and trimer based on the combined extended-transition-state energy decomposition analysis and natural orbitals for chemical valence (ETS-NOCV)

In the present study we have analyzed hydrogen bonding in dimer and trimer of oxalic acid, based on a recently proposed charge and energy decomposition scheme (ETS-NOCV). In the case of a dimer, two conformations, α and β, were considered. The deformation density contributions originating from NOCV’s revealed that the formation of hydrogen bonding is associated with the electronic charge deformation in both the σ—(Δρσ) and π-networks (Δρπ). It was demonstrated that σ-donation is realized by electron transfer from the lone pair of oxygen on one monomer into the empty \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\rho_{H - O}^*$$\end{document} orbital of the second oxalic acid fragment. In addition, a covalent contribution is observed by the density transfer from hydrogen of H-O group in one oxalic acid monomer to the oxygen atom of the second fragment. The resonance assisted component (Δρπ), is based on the transfer of electron density from the π—orbital localized on the oxygen of OH on one oxalic acid monomer to the oxygen atom of the other fragment. ETS-NOCV allowed to conclude that the σ(O---HO) component is roughly eight times as important as π (RAHB) contribution in terms of energetic estimation. The electrostatic factor (ΔEelstat) is equally as important as orbital interaction term (ΔEorb). Finally, comparing β-dimer of oxalic acid with trimer we found practically no difference concerning each of the O---HO bonds, neither qualitative nor quantitative

An exceptional horizontal gene transfer in plastids: gene replacement by a distant bacterial paralog and evidence that haptophyte and cryptophyte plastids are sisters

BACKGROUND: Horizontal gene transfer (HGT) to the plant mitochondrial genome has recently been shown to occur at a surprisingly high rate; however, little evidence has been found for HGT to the plastid genome, despite extensive sequencing. In this study, we analyzed all genes from sequenced plastid genomes to unearth any neglected cases of HGT and to obtain a measure of the overall extent of HGT to the plastid. RESULTS: Although several genes gave strongly supported conflicting trees under certain conditions, we are confident of HGT in only a single case beyond the rubisco HGT already reported. Most of the conflicts involved near neighbors connected by long branches (e.g. red algae and their secondary hosts), where phylogenetic methods are prone to mislead. However, three genes – clpP, ycf2, and rpl36 – provided strong support for taxa moving far from their organismal position. Further taxon sampling of clpP and ycf2 resulted in rejection of HGT due to long-branch attraction and a serious error in the published plastid genome sequence of Oenothera elata, respectively. A single new case, a bacterial rpl36 gene transferred into the ancestor of the cryptophyte and haptophyte plastids, appears to be a true HGT event. Interestingly, this rpl36 gene is a distantly related paralog of the rpl36 type found in other plastids and most eubacteria. Moreover, the transferred gene has physically replaced the native rpl36 gene, yet flanking genes and intergenic regions show no sign of HGT. This suggests that gene replacement somehow occurred by recombination at the very ends of rpl36, without the level and length of similarity normally expected to support recombination. CONCLUSION: The rpl36 HGT discovered in this study is of considerable interest in terms of both molecular mechanism and phylogeny. The plastid acquisition of a bacterial rpl36 gene via HGT provides the first strong evidence for a sister-group relationship between haptophyte and cryptophyte plastids to the exclusion of heterokont and alveolate plastids. Moreover, the bacterial gene has replaced the native plastid rpl36 gene by an uncertain mechanism that appears inconsistent with existing models for the recombinational basis of gene conversion

Application of the MUSIC analysis for evaluation of the signals interfering diagnostic measurements of insulation systems using acoustic emission method

W artykule zostaną przedstawione wyniki analizy pseudospektralnej (Pseudo-Spectral Analysis) uzyskane dla akustycznych sygnałów zakłócających. Analizowane będą źródła zakłóceń, które mogą występować podczas pomiarów diagnostycznych układów izolacyjnych wykonywanych on-line metodą emisji akustycznej podczas normalnej eksploatacji transformatorów elektroenergetycznych. Uzyskane wyniki zostaną porównane z rezultatami otrzymanymi przy zastosowaniu transformaty Fouriera (Fast Fourier Transform).This paper discusses the problems connected with frequency analysis and multiple signal classification (MUSIC) of disturbances that can accompany the measurements of partial discharges in industrial conditions using the acoustic emission method. It presents different kinds of interfering signals that can deform the measured acoustic emission signals generated by partial discharges in electric power devices. In addition, it includes the results of the measurements and frequency and MUSIC analyses of interfering signals in the form of power density spectra and of pseudo-spectrum

Evaluation of the influence of weather conditions on the efficiency of wind turbines

Podstawowym celem przeprowadzonych badań było określenie wpływu zmian gęstości powietrza atmosferycznego na wyniki obliczeń wskaźników charakteryzujących sprawność elektrowni wiatrowych. W części wynikowej przedstawiono wykresy obrazujące wpływ zarejestrowanych parametrów atmosferycznych na przebiegi krzywej mocy i wartości sprawności. Zależności zostały wyznaczone na podstawie rejestracji temperatury, ciśnienia i wilgotności powietrza atmosferycznego, które wykonano dla dwóch turbin wiatrowych Tacke Tw 600.The main objective of the studies whose results are presented in this paper was to determine the impact of air density changes on the calculation results of indicators characterizing the efficiency of a wind power plant. It was assumed that the efficiency is described by the amount of electricity generated in a specified period of time, under existing weather conditions for the given location and when taking into account the generated energy quality and the real efficiency of components of the wind turbine generators and their control systems. The equipment used for measuring purposes, location of measuring instruments and their calibration methods are characterized in the descriptive part of the paper. Additionally, basic recommendations on the methodology of measuring the ambient air temperature, pressure and humidity in order to determine the wind turbine efficiency are given. In the part of the paper presenting the results there are shown the graphs illustrating the impact of the recorded atmospheric parameters on the courses of the empirical power curve and the real efficiency value. The dependencies were determined on the basis of the recorded ambient air values of temperature, pressure and humidity in summer, autumn and winter periods for the two Tacke Tw 600 wind turbines. Respectively, Figs. 2-5 show the graphs presenting the impact of changes of the recorded air temperature, atmospheric pressure, relative humidity and air density on the course of the empirical power curve and the real efficiency value (Fig. 6) of the wind turbines being studied

Research studies on the efficiency of wind turbine generators

Podstawowym celem przeprowadzonych badań, było określenie wpływu zmian gęstości powietrza atmosferycznego na wyniki obliczeń wskaźników charakteryzujących efektywność elektrowni wiatrowych. Przy czy założono, że efektywność opisuje wielkość energii elektrycznej wyprodukowanej w określonym przedziale czasowym, przy istniejących warunkach atmosferycznych dla danej lokalizacji i przy uwzględnieniu jakości wyprodukowanej energii oraz rzeczywistej sprawności podzespołów prądotwórczych instalacji wiatrowych i ich układów sterowania. W części opisowej scharakte-ryzowano zastosowane urządzenia pomiarowe, usytuowanie mierników i sposób ich kalibracji oraz podstawowe zalecenia dotyczące metodyki wykonywania pomiarów wartości temperatury, ciśnienia oraz wilgotności powietrza atmosferycznego. Natomiast w części wynikowej przedstawiono wykresy obrazujące wpływ zarejestrowanych parametrów atmosferycznych i obliczonej na ich podstawie gęstości powietrza na przebiegi empirycznej krzywej mocy oraz na wartości rzeczywistej sprawności.The primary objective of the research studies was to determine the impact of the air density changes on the calculation results of indicators characterizing the efficiency of a wind power plant. The equipment used for measuring purposes, location of metres and their calibration methods were characterized in the descriptive part of the article. Additionally, basic recommendations on the methodology of measuring the ambient air values of temperature, pressure and humidity. Wherein, it was assumed that the efficiency is being described by the electric force generated in a specified period of time, under existing weather conditions for the given location, taking into account the quality of the generated energy and the real efficiency of components of the wind turbine generators and their control systems. In the part of the describing the results, graphs showing the impact of the recorded atmospheric parameters on the courses of empirical power curve and the real efficiency value were presented

Present possibilities and prospects of the acoustic method application in diagnostics of insulation systems

W artykule zostały scharakteryzowane prowadzone obecnie przez autorów artykuły prace związane z doskonaleniem akustycznej metody pomiaru wyładowań elektrycznych, jakie mogą występować w układach izolacyjnych urządzeń elektroenergetycznych. Szczególną uwagę zwrócono na ekspercki system diagnostyczny wykorzystujący metodę emisji akustycznej do oceny stanu mierzonej izolacji transformatorów energetycznych.The paper characterizes the research work on the improvement of the acoustic method of the measurements of electrical discharges that can occur in insulation systems of power appliances. The utmost attention was directed to the expert diagnostic system using the acoustic emission method for the evaluation of the condition of the power transformer insulation measured

Analysis of AE signals generated by piezoelectric transducer in transformer tank model

W artykule przedstawiono wyniki analizy sygnałów emisji akustycznej (EA) generowanej przez przetwornik piezoelektryczny umieszczony w modelu kadzi transformatorowej wypełnionej olejem elektroizolacyjnym. Przetwornik pobudzano napięciem o charakterze impulsowym o wartości napięcia od 3 V do 12 V, a rejestrowane sygnały EA analizowano w dziedzinie czasu. Podano postać funkcji regresji, która opisuje serię fal EA docierających bezpośrednio od przetwornika generującego do przetwornika rejestrującego. Ponadto przedstawiono wyniki procesu identyfikacji funkcji przejścia dla rozpatrywanego układu pomiarowego.Analysis results of acoustic emission (AE) signals generated by a piezoelectric transducer mounted inside a transformer tank model that was filled with electro insulation oil are presented. The transducer was stimulated by an impulse voltage signal of amplitude from 3 V to 12 V. The gathered signal was analyzed in the time domain. A regression function model which describe AE wave coming from the generating transducer to the measuring transducer directly is presented in the paper. Furthermore, results of an identification process of transfer function for the regarded measurement setup are presented

The Application of the Correlative Analysis and the Regression Function for Determining Correlations οf the Measurement Results of Acoustic Emission Generated by Partial Discharges

The subject matter of this paper is connected with development of the assessment methods of results obtained at measurements of partial discharges occurring in insulation systems of power transformers using the acoustic emission method. The paper presents the results connected with determining correlation between partial discharge generation voltage and selected descriptors characterizing the emitted signals of acoustic emission in the frequency domain. Authors use the selected descriptors as comparative criteria for recognition of the basic partial discharge forms that may occur in paper-oil insulation of power transformers. The correlation coefficient and regression function were used to determine the correlation degree between the variables under study