Phenomenology of high-ozone episodes in NE Spain

Ground-level and vertical measurements (performed using tethered and non-tethered balloons), coupled with modelling, of ozone (O3), other gaseous pollutants (NO, NO2, CO, SO2) and aerosols were carried out in the plains (Vic Plain) and valleys of the northern region of the Barcelona metropolitan area (BMA) in July 2015, an area typically recording the highest O3 episodes in Spain. Our results suggest that these very high O3 episodes were originated by three main contributions: (i) the surface fumigation from high O3 reservoir layers located at 1500-3000 m a.g.l. (according to modelling and non-tethered balloon measurements), and originated during the previous day(s) injections of polluted air masses at high altitude; (ii) local/regional photochemical production and transport (at lower heights) from the BMA and the surrounding coastal settlements, into the inland valleys; and (iii) external (to the study area) contributions of both O3 and precursors. These processes gave rise to maximal O3 levels in the inland plains and valleys northwards from the BMA when compared to the higher mountain sites. Thus, a maximum O3 concentration was observed within the lower tropospheric layer, characterised by an upward increase of O3 and black carbon (BC) up to around 100-200 m a.g.l. (reaching up to 300 µg m−3 of O3 as a 10 s average), followed by a decrease of both pollutants at higher altitudes, where BC and O3 concentrations alternate in layers with parallel variations, probably as a consequence of the atmospheric transport from the BMA and the return flows (to the sea) of strata injected at certain heights the previous day(s). At the highest altitudes reached in this study with the tethered balloons (900-1000 m a.g.l.) during the campaign, BC and O3 were often anti-correlated or unrelated, possibly due to a prevailing regional or even hemispheric contribution of O3 at those altitudes. In the central hours of the days a homogeneous O3 distribution was evidenced for the lowest 1 km of the atmosphere, although probably important variations could be expected at higher levels, where the high O3 return strata are injected according to the modelling results and non-tethered balloon data. Relatively low concentrations of ultrafine particles (UFPs) were found during the study, and nucleation episodes were only detected in the boundary layer. Two types of O3 episodes were identified: type A with major exceedances of the O3 information threshold (180 µg m−3 on an hourly basis) caused by a clear daily concatenation of local/regional production with accumulation (at upper levels), fumigation and direct transport from the BMA (closed circulation); and type B with regional O3 production without major recirculation (or fumigation) of the polluted BMA/regional air masses (open circulation), and relatively lower O3 levels, but still exceeding the 8 h averaged health target. To implement potential O3 control and abatement strategies two major key tasks are proposed: (i) meteorological forecasting, from June to August, to predict recirculation episodes so that NOx and VOC abatement measures can be applied before these episodes start; (ii) sensitivity analysis with high-resolution modelling to evaluate the effectiveness of these potential abatement measures of precursors for O3 reduction

The test of railway steel bridge with defects using acoustic emission method

Konstrukcje mostowe eksploatowane są w warunkach działania zmiennego środowiska atmosferycznego, co powoduje stałą degradację materiałów wykorzystanych do ich budowy. Istotne niebezpieczeństwo awarii w eksploatacji konstrukcji mostowych powoduje potrzebę usystematyzowania i rozszerzania stosowanych procedur oceny związanych z postępem owoczesnych metod badawczych. Dla wdrożenia nowego skutecznego sposobu opartego o system procedur wykorzystujących metodę emisji akustycznej (acousticemission - AE), a opracowanych dla monitorowania i określenia bezpiecznych warunków eksploatacji nośnych elementów mostów z uszkodzeniem, zorganizowane zostało konsorcjum złożone z Politechniki Krakowskiej oraz właściciela linii i mostów kolejowych, przedsiębiorstwo PKP Polskie Linie Kolejowe S.A. Konsorcjum to realizuje wspólnie projekt w ramach Programu Badań Stosowanych finansowany przez Narodowe Centrum Badań i Rozwoju. Jednym z etapów realizacji projektu były badania na konstrukcji mostowej z uszkodzeniem o różnej wielkości ubytku materiału. Dla przedmiotowej konstrukcji kratownicowej wykonano obliczenia numeryczne oraz szereg pomiarów z rejestracją sygnałów emisji akustycznej. Badania wykonano przy kontrolowanym ruchu zestawów kolejowych o różnym obciążeniu i różnej prędkości przejazdu zestawu kolejowego. Wyniki obliczeń, analiz, korelacji sygnałów AE i obciążenia, a także badań laboratoryjnych niezbędnych dla przeprowadzonych analiz zostały przedstawione w artykule.Currently a significant part of operated railway steel bridges in Poland is exploited from the beginning of 20th century. The technical condition of them is very often bad and these objects require the appropriate diagnostics. Mostly the visual diagnostics is used, and in exceptional cases in some places of objects the other non-destructive testing are performed. Therefore the opinion about condition of bridge is non completed and it is necessary to study the effective method, which will enable to more exact diagnostics of steel bridges. The Cracow University of Technology together with PKP PLK realize the project to the work out of diagnostic method for steel railway bridges with use of acoustic emission method (AE). During project realization, the laboratory tests on material from railway steel bridge for collection data were performed. These measurements were done on standard specimens and on samples with corrosion products. The AE measurements on real object with different crack size were also performed. The tests were carried out at a controlled moving train at different speeds and for various weight of railway carriages. The results of acoustic emission tests and analysis with standard and additional parameters have been presented in the paper. The results of metallography and numerical analysis of bridge and defected element have also been presented

Application of acoustic emission method in the studies of steel node in railway bridge

W ramach realizowanego wspólnie przez Politechnikę Karkowską i PKP Polskie Linie Kolejowe projektu finansowanego przez NCBiR (Narodowe Centrum Badań i Rozwoju) przeprowadzono badania na elementach konstrukcji mostowej. W pierwszym etapie określono własności materiału konstrukcji, wykonano obliczenia i modelowanie węzła będącego przedmiotem badań. W kolejnym etapie węzeł poddano cyklicznemu obciążaniu w próbie obciążeniowej odwzorowującej rzeczywiste warunki jego pracy na przygotowanym stanowisku badawczym z rejestracją sygnałów emisji akustycznej (AE). Przeprowadzono analizy zarejestrowanych danych pomiarowych w celu określenia charakterystyk emisyjnych sygnałów, wyznaczenia parametrów sygnałów wykorzystywanych w ocenie uszkodzenia oraz określenia najskuteczniejszego układu do lokalizacji sygnałów AE.In the field of project, where Cracow University of Technology cooperates with PKP Polskie Linie Kolejowe and the project is financed by NCBiR () the studies elements of bridge construction have been carried out. In the first stage of the study, construction material properties have been defined, calculations have been made and the node being researched has been modelled. In the next stage, the node has been subjected to cycle load in loading test mapping the actual conditions of its work on the prepared test bench with the registration of acoustic emission signals (AE). The analyses of the recorded measurement data have been carried out to determine the characteristics of the emission of signals, the signal parameters used in assessing the damage and the most effective system for locating signals AE

Recognition of conductive objects based on the characteristics of reflected electromagnetic wave

The problem of electromagnetic wave diffraction by the metal objects has been solved using integral equation technique. The diagrams of backward scattering have been plotted for four different objects. Based on the feature vector, which has been constructed by applying wavelet packet signal decomposition, a neural network has been trained. We have performed the testing of ability of the neural network to recognize the object depending on the noise level. Various methods of the feature vector forming have been considered

Solving diffraction problems in a step waveguide transition

Using method on integral equation on the base of cross region by using tensor Green function the decision of three-dimensional diffraction problems in a step waveguide transition is considered. It is shown that a step transition allows effectively matching different transmission lines

АКУСТИКО-ЕМІСІЙНЕ ІДЕНТИФІКУВАННЯ ДЖЕРЕЛ РУЙНУВАННЯ АЛЮМІНІЄВОГО СПЛАВУ

The features of acoustic emission generation by static fracture of thermostrengthened aluminum alloy 1201-T were considered. With the help of metallographic and fractographical studies it was found that the alloy is destroyed by brittle-ductile fracture mechanism, where the brittle component corresponds to intermetallic cracking Al2Cu and ductile – to solid solution. Analysis of wave representation and their continuous wavelet transformation allows us to recognize clearly the aluminum alloy fracture mechanisms using acoustic emission signals.Рассмотрены особенности генерирования акустической эмиссии при статическом разрушении термически упрочненного алюминиевого сплава 1201-Т. По металлографическим и фрактографическим исследованиям установлено, что механизм их разрушения хрупко-вязкий, где хрупкая составляющая соответствует растрескиванию интерметаллидов Al2Сu, а вязкая – -твердого раствора. Анализ волновых отображений и их непрерывных вейвлет-преобразований позволяет распознавать по сигналам акустической эмиссии механизмы разрушения алюминиевого сплава.Розглянуто особливості генерування акустичної емісії за статичного руйнування термічно зміцненого алюмінієвого сплаву 1201-Т. Металографічними та фрактографічними дослідженнями встановлено, що сплав руйнується за крихко-в’язким механізмом, де крихка складова відповідає розтріскуванню інтерметалідів Al2Сu, а в’язка – -твердому розчину. Аналіз хвильових відображень та їх неперервних вейвлет перет-ворень дає змогу чітко розпізнати за сигналами акустичної емісії механізми руйнування алюмінієвого сплаву

Recognition of conductive objects based on the characteristics of reflected electromagnetic wave

Полный текст доступен на сайте издания по подписке: http://radio.kpi.ua/article/view/S0021347016070025The problem of electromagnetic wave diffraction by the metal objects has been solved using integral equation technique. The diagrams of backward scattering have been plotted for four different objects. Based on the feature vector, which has been constructed by applying wavelet packet signal decomposition, a neural network has been trained. We have performed the testing of ability of the neural network to recognize the object depending on the noise level. Various methods of the feature vector forming have been considered.Методом интегрального уравнения решена задача дифракции электромагнитной волны на металлических телах. Построены диаграммы обратного рассеивания для четырех различных объектов. На основании вектора признаков, построенного с помощью применения вейвлет-пакетного разложения сигнала, обучена нейронная сеть. Произведено тестирование способности нейронной сети к распознаванию объекта в зависимости от уровня шума. Рассмотрены различные способы формирования вектора признаков

ОЦІНКА РОЗВИТКУ ВТОМНОГО РУЙНУВАННЯ В’ЯЗКИХ КОНСТРУКЦІЙНИХ СТАЛЕЙ

The procedure for testing the prismatic steel specimens of heavy constructions to build the kinetic diagrams of fatigue fracture is described in the paper. The kinetic diagrams obtained have been approximated by analytical dependences with unknown parameters, which were found using least squares method.В работе описано методику испытаний призматических образцов стали крупногабаритных конструкций для построения кинетических диаграмм усталостного разрушения этих материалов. Полученные кинетические диаграммы аппроксимировано аналитическими зависимостями с неизвестными параметрами, найденными методом наименьших квадратов.В роботі описано методику випробувань призматичних зразків сталі великогабаритних конструкцій для побудови кінетичних діаграм втомного руйнування цих матеріалів. Отримані кінетичні діаграми апроксимовано аналітичними залежностями із невідомими параметрами, які знайдено методом найменших квадратів