Ozone production

Results from the Intergovernmental Panel on Climatic Change (IPCC) tropospheric photochemical model intercomparison (PhotoComp) are presented with a brief discussion of the factors that may contribute to differences in the modeled behaviors of HOx cycling and the accompanying O3 tendencies. PhotoComp was a tightly controlled model experiment in which the IPCC 1994 assessment sought to determine the consistency among models that are used to predict changes in tropospheric ozone, an important greenhouse gas. Calculated tropospheric photodissociation rates displayed significant differences, with a root‐mean‐square (rms) error of the reported model results ranging from about ±6–9% of the mean (for O3 and NO2) to up to ±15% (H2O2 and CH2O). Models using multistream methods in radiative transfer calculations showed distinctly higher rates for photodissociation of NO2 and CH2O compared to models using two‐stream methods, and this difference accounted for up to one third of the rms error fo...

An extensive set of measurements was made in and around Mexico City as part of the MILAGRO (Megacity Initiative: Local and Global Research Observations) experiments in March 2006. Simulations with the Model for Ozone and Related Chemical Tracers, version 4 (MOZART-4), a global chemical transport model, have been used to provide a regional context for these observations and assist in their interpretation. These MOZART-4 simulations reproduce the aircraft observations generally well, but some differences in the modeled volatile organic compounds (VOCs) from the observations result from incorrect VOC speciation assumed for the emission inventories. The different types of CO sources represented in the model have been "tagged" to quantify the contributions of regions outside Mexico, as well as the various emissions sectors within Mexico, to the regional air quality of Mexico. This analysis indicates open fires have some, but not a dominant, impact on the atmospheric composition in the region around Mexico City, when averaged over the month. However, considerable variation in the fire contribution (2-15% of total CO) is seen during the month. The transport and photochemical aging of Mexico City emissions were studied using tags of CO emissions for each day, showing that typically the air near Mexico City was a combination of many ages. Ozone production in MOZART-4 is shown to agree well with the net production rates from box model calculations constrained by the MILAGRO aircraft measurements. Ozone production efficiency derived from the ratio of O x to NO z is higher in MOZART-4 than in the observations for moderately polluted air. OH reactivity determined from the MOZART-4 results shows the same increase in relative importance of oxygenated VOCs downwind of Mexico City as the reactivity inferred from the observations. The amount of ozone produced by emissions from Mexico City and surrounding areas has been quantified in the model by tracking NO emissions, showing little influence beyond Mexico's borders, and also relatively minor influence from fire emissions on the monthly average tropospheric ozone column.

La science actuelle poursuit depuis un siècle un grand espoir : unifier les quatre grandes interactions de la nature découvertes successivement : la gravitation de mécanisme indéterminé, l'électromagnétique que nous croyons bien connue, la forte qui soude les composants nucléaires, la faible comme dans la désintégration du neutron. Leurs mécanismes profonds échappent encore à la science, malgré les nombreux modèles, expérimentations et formulations mathématiques. L’intelligence de toute l’Humanité me semble insuffisante pour comprendre ou mettre clairement en évidence toutes les lois fonctionnant dans la Nature.
Après 45 ans d'approches soutenues, une méthode m'est apparue efficace : introduire, moi aussi, des nouveaux et faux modèles très simplificateurs. En cet ouvrage, comme base de départ, nous rapprocherons principalement l'électromagnétisme et la gravitation.

The back discharge takes place in an industrial electrostatic precipitation process, especially in coal-fired power plants whose operation is based on low-sulfur coal. This type of discharge occurs simultaneously with corona discharge on an electrode covered with a high-resistivity dust layer. The charge that accumulates on the dielectric layer surface is responsible for an increase in the magnitude of electric field within the dielectric layer and a decrease in the magnitude of electric field between the electrodes. The breakdown of dielectric layer increases the discharge current and the reentraining of dust particles from collecting electrode into the flowing gas. The motion of dust particles emitted from the collecting electrode and an air flow pattern were investigated. Additionally, acrylic powder layer placed between a mica plate with a small pinhole and the plate electrode was also used in the experiments in order to generate a repeatable back discharge.

Приведены результаты исследований состояния гирлянд фарфоровых изоляторов по характеристикам частичных разрядов. Разработана методика выявления гирлянд, содержащих дефектный изолятор, без отключения приложенного напряжения. Разработан новый метод оценки состояния фарфоровых изоляторов воздушных линий электропередачи напряжением 6/10 кВ и их гирлянд, основанный на анализе характеристик частичных разрядов.

Dry deposition is a key process for surface ozone (O3) removal. Stomatal resistance is a major component of O3 dry deposition, which is parameterized differently in current land surface models and chemical transport models. We developed and used a standalone terrestrial biosphere model, driven by a unified set of prescribed meteorology, to evaluate two widely used dry deposition modeling frameworks, Wesely (1989) and Zhang et al. (2003), with different configurations of stomatal resistance: 1) the default multiplicative method in each deposition scheme; 2) the traditional photosynthesis-based Farquhar-Ball-Berry (FBB) stomatal algorithm; 3) the Medlyn stomatal algorithm based on an optimization theory. We found that using the FBB stomatal approach that captures ecophysiological responses to environmental factors, especially to water stress, can generally improve the simulated dry deposition velocities compared with multiplicative schemes. The Medlyn stomatal approach produces higher stomatal conductance (reverse of stomatal resistance) than FBB and is likely to overestimate dry deposition velocities for major vegetation types, but its performance is greatly improved when spatially varying slope parameters based on annual mean precipitation are used. Large discrepancies were also found in simulated stomatal responses to rising CO2 levels, and that multiplicative stomatal method with an empirical CO2 response function produces reduction (-35%) in global stomatal conductance, which is much larger than that with photosynthesis-based stomatal method (-14-19%) when atmospheric CO2 level increases from 390 ppm to 550 ppm. Our results show the potential biases in O3 sink caused by errors in model structure especially in the Wesely dry deposition scheme, and the importance of using photosynthesis-based representation of stomatal resistance in dry deposition schemes under a changing climate and rising CO2 concentration.

The chemical composition of submicron aerosol particles was characterized using an aerosol chemical speciation monitor (ACSM) at a mixed-mature forest site at the Aukštaitija Integrated Monitoring Station in the eastern part of Lithuania. Four organic aerosol (OA) factors were determined by positive matrix factorization (PMF) analysis applied for the ACSM data: semi-volatile oxygenated OA (SVOOA, the contribution to the total OA mass concentration was 33%), low-volatile oxygenated OA (LVOOA, 39%), cooking related OA (COA, 15%) and biomass burning OA (BBOA, 13%). In our study secondary organic aerosol (SOA) has been identified as one of the most important contributors to the submicron particle (PM 1) mass concentration. A comparison between SVOOA and submicron forest organic aerosol mass (SFOM) was performed, and a good correlation of 0.75 between them was found. In our study the SOA concentration dependence on temperature was explored in 3 means: firstly, by investigating aerosol mass spectra measured during hot and cold days. It has been found that during hot days events signal intensities of m/z 42, 43, 45, 53 and 59 were about 2.1-2.7 times higher compared to those during cold days. Secondly, by investigating the temperature dependence of SVOOA and estimated SFOM. It has been found that SFOM and SVOOA concentrations increase with temperature. Thirdly, by assessing the

В рамках гибридной теоретической модели наносекундного разряда высокого давления с убегающими электронами продемонстрирована сильная зависимость амплитуды, длительности и энергетического спектра электронного пучка от условий предварительной ионизации газа в промежутке. Смоделированы ситуации с однородным и резко неоднородными распределениями инициирующих электронов в коаксиальном диоде, заполненном гексафторидом серы атмосферного давления. Показано, что амплитуда и профиль импульса тока электронного пучка существенно изменяются при вариации начального распределения электронов в промежутке. DOI: 10.21883/PJTF.2017.17.44947.16848

Экспериментально зафиксировано, что во время зажигания разряда в атмосфере азота и гелия при низком напряжении на газовом диоде (-25 кВ) происходит генерация пучка убегающих электронов, причем режимы генерации могут быть различными, и зависят от давления газа. Запаздывание момента начала генерации электронного пучка относительно начала спада напряжения на промежутке составляло менее 1 нс. На основе влияния поперечного магнитного поля 0,016 Тл на поведение электронного пучка предполагается, что наносекундный электронный пучок при низких давлениях генерируется у катода. Показано влияние подсветки на генерацию электронного пучка

Рассмотрены два случая создания плазмы из микрогетерогенной малоплотной полимерной среды, применяемой для решения двух различных практических задач. Первый случай-лайнер для самосжатого разряда, Z-пинча, в экспериментах по инерциальному термоядерному синтезу. Другой случай-пористый матрикс для создания биомедицинских имплантатов в клеточных технологиях. Описаны методики приготовления пористых сред с нанометровой структурой волокон из агар-агара, полиуретана и полиоксибутирата. В опытах по сжатию Z-пинчей нарастающий мегаамперный ток через полимерный лайнер филаментирован. При этом разрядный ток переключается на редкую плазму филамент, а плазмообразование основной части вещества лайнера оказывается затянутым во времени. В опытах по плазменной обработке пористых матриксов использованы несамостоятельный объемный разряд, поддерживаемый импульсным релятивистским электронным пучком в двухфазной гетерогенной среде, и частотно-импульсный наносекундный диэлектрический барьерный разряд. Оба вида разрядов применены для данной задачи впервые. Ключевые слова: малоплотная полимерная среда, лайнер, инерциальный термоядерный синтез, пористый матрикс, клеточные технологии, электронный пучок, несамостоятельный объемный разряд, наносекундный барьерный разряд.

Local ozone production and loss rates for the arctic free troposphere (58-85 • N, 1-6 km, February-May) during the Tropospheric Ozone Production about the Spring Equinox (TOPSE) campaign were calculated using a constrained photochemical box model. Estimates were made to assess the importance of local photochemical ozone production relative to transport in accounting for the springtime maximum in arctic free tropospheric ozone. Ozone production and loss rates from our diel steady-state box model constrained by median observations were first compared to two point box models, one run to instantaneous steady-state and the other run to diel steady-state. A consistent picture of local ozone photochemistry was derived by all three box models suggesting that differences between the approaches were not critical. Our model-derived ozone production rates increased by a factor of 28 in the 1-3 km layer and a factor of 7 in the 3-6 km layer between February and May. The arctic ozone budget required net import of ozone into the arctic free troposphere throughout the campaign; however, the transport term exceeded the photochemical production only in the lower free troposphere (1-3 km) between February and March. Gross ozone production rates were calculated to increase linearly with NO x mixing ratios up to ∼300 pptv in February and for NO x mixing ratios up to ∼500 pptv in May. These NO x limits are an order of magnitude higher than median NO x levels observed, illustrating the strong dependence of gross ozone production rates on NO x mixing ratios for the majority of the observations. The threshold NO x mixing ratio needed for net positive ozone production was also calculated to increase from NO x ∼ 10 pptv in February to ∼25 pptv in May, suggesting that the NO x levels needed to sustain net ozone production are lower in winter than spring. This lower NO x threshold explains how wintertime photochemical ozone production can impact the build-up of ozone over winter and early spring. There is also an altitude dependence as the threshold NO x needed to produce net ozone shifts to higher values at lower altitudes. This partly

В элегазе (SF6) при давлениях 0,1...2,5 ата исследовано формирование сверхкороткого (100...200 пс) лавинного электронного пучка. За AlBe фольгой толщиной 45 мкм электронный пучок получен при давлении элегаза в газовом диоде до 2 ата. Показано, что при повышенных давлениях (>1 ата) и подаче от генератора наносекундных импульсов высокого напряжения (-270 кВ) длительность импульса сверхкороткого лавинного электронного пучка на полувысоте увеличивается до 150 пс

Поверхностные свойства композиционных материалов на основе полилактида и гидроксиапатита, обработанных потоками низкотемпературной плазмы Изучены физико-химические свойства полилактида и композита на основе полилактида с гидроксиапатитом в массовом соотношении компонентов 70/30, модифицированных потоками низкотемпературной атмосферной плазмы тлеющего разряда в потоке аргона с длительностями импульса 1 и 5 мкс. Методом РФА показано, что при воздействии плазменных потоков степень кристалличности и размеры кристаллитов материалов повышаются. Установлено снижение краевого угла смачивания при контакте с водой, глицерином и этиленгликолем, а также увеличение свободной поверхностной энергии материалов после плазменной обработки.

Поверхностные свойства композиционных материалов на основе полилактида и гидроксиапатита, обработанных потоками низкотемпературной плазмы Изучены физико-химические свойства полилактида и композита на основе полилактида с гидроксиапатитом в массовом соотношении компонентов 70/30, модифицированных потоками низкотемпературной атмосферной плазмы тлеющего разряда в потоке аргона с длительностями импульса 1 и 5 мкс. Методом РФА показано, что при воздействии плазменных потоков степень кристалличности и размеры кристаллитов материалов повышаются. Установлено снижение краевого угла смачивания при контакте с водой, глицерином и этиленгликолем, а также увеличение свободной поверхностной энергии материалов после плазменной обработки.

Results from the Intergovernmental Panel on Climatic Change (IPCC) tropospheric photochemical model intercomparison (PhotoComp) are presented with a brief discussion of the factors that may contribute to differences in the modeled behaviors of HO x cycling and the accompanying 03 tendencies. PhotoComp was a tightly controlled model experiment in which the IPCC 1994 assessment sought to determine the consistency among models that are used to predict changes in tropospheric ozone, an important greenhouse gas. Calculated tropospheric photodissociation rates displayed significant differences, with a root-mean-square (nns) error of the reported model results ranging from about _+6-9% of the mean (for 03 and NO2) to up to +15% (H202 and CH20). Models using multistream methods in radiative transfer calculations showed distinctly higher rates for photodissociation of NO 2 and CH20 compared to models using two-stream methods, and this difference accounted for up to one third of the rms error for these two rates. In general, some small but systematic differences between models were noted for the predicted chemical tendencies in cases that did not include reactions of nonmethane hydrocarbons (NMHC). These differences in modeled 03 tendencies in some cases could be identified, for example, as being due to differences in photodissociation rates, but in others they could not and must be ascribed to unidentified errors. 03 tendencies showed nns errors of about___10% in the moist, surface level cases with NO x concentrations equal to a few tens of parts per trillion by volume. Most of these model to model differences can be traced to differences in the destruction of 03 due to reaction with HO 2. Differences in HO 2, in turn, are likely due to (1) inconsistent reaction rates used by the models for the conversion of HO 2 to H202 and (2) differences in the model-calculated photolysis of H202 and CH20. In the middle tropospheric "polluted" scenario with NO x concentrations larger than a few parts per billion by volume, 03 tendencies showed nns errors of _+10-30%. These model to model differences most likely stem from differences in the calculated rates of 03 photolysis to O(•D), which provides about 80% of the HO x source under these conditions. The introduction of hydrocarbons dramatically increased both the rate of NO x loss and its model to model differences, which, in turn, are reflected in an increased spread of predicted 03. Including NMHC in the simulation approximately doubled the rms error for 03 concentration.

В статье приводятся результаты экспериментов по очистке сточных вод от пестицидов на примере имидаклоприда, системного инсектицида нового поколения, принадлежащего к химическому классу азотсодержащих гетероциклических пестицидов. Исследовалось: обработка пероксидом водорода в присутствии катализаторов; прямое озонирование; ультрафиолетовое облучение. Наибольшая эффективность деструкции имидаклоприда наблюдалась в результате ультрафиолетового облучения. При интенсивности излучения 35 мДж/см, продолжительности обработки 90 секунд, эффект деструкции ИМД составил 97%

Local ozone production and loss rates for the arctic free troposphere (58-85 • N, 1-6 km, February-May) during the Tropospheric Ozone Production about the Spring Equinox (TOPSE) campaign were calculated using a constrained photochemical box model. Estimates were made to assess the importance of local photochemical ozone production relative to transport in accounting for the springtime maximum in arctic free tropospheric ozone. Ozone production and loss rates from our diel steady-state box model constrained by median observations were first compared to two point box models, one run to instantaneous steady-state and the other run to diel steady-state. A consistent picture of local ozone photochemistry was derived by all three box models suggesting that differences between the approaches were not critical. Our model-derived ozone production rates increased by a factor of 28 in the 1-3 km layer and a factor of 7 in the 3-6 km layer between February and May. The arctic ozone budget required net import of ozone into the arctic free troposphere throughout the campaign; however, the transport term exceeded the photochemical production only in the lower free troposphere (1-3 km) between February and March. Gross ozone production rates were calculated to increase linearly with NO x mixing ratios up to ∼300 pptv in February and for NO x mixing ratios up to ∼500 pptv in May. These NO x limits are an order of magnitude higher than median NO x levels observed, illustrating the strong dependence of gross ozone production rates on NO x mixing ratios for the majority of the observations. The threshold NO x mixing ratio needed for net positive ozone production was also calculated to increase from NO x ∼ 10 pptv in February to ∼25 pptv in May, suggesting that the NO x levels needed to sustain net ozone production are lower in winter than spring. This lower NO x threshold explains how wintertime photochemical ozone production can impact the build-up of ozone over winter and early spring. There is also an altitude dependence as the threshold NO x needed to produce net ozone shifts to higher values at lower altitudes. This partly

Materials presented in the paper are the first stage of realization of methodology of ensuring the required level of protection of rocket space complexes from destabilizing action of lightning. The methodology is an obligatory element of ensuring a life cycle of the complexes and is logically integrated into the system of standards of IEC 61508 series. The presented first stage includes a calculated estimation of probability of lightning direct strike into elements of the complex. The estimation was carried out with using a method based on calculation of distribution of intensity of stationary electric field over the surface of objects of the complex. It is shown that it is sufficient to use only a variant of vertical, in relation to the ground surface, vector of intensity of electric field created by a thundercloud.Материалы, представленные в докладе являются первым этапом реализации методологии обеспечения требуемого уровня защиты ракетных космических комплексов от дестабилизирующ...

The chemical composition of submicron aerosol particles was characterized using an aerosol chemical speciation monitor (ACSM) at a mixed-mature forest site at the Aukštaitija Integrated Monitoring Station in the eastern part of Lithuania. Four organic aerosol (OA) factors were determined by positive matrix factorization (PMF) analysis applied for the ACSM data: semi-volatile oxygenated OA (SVOOA, the contribution to the total OA mass concentration was 33%), low-volatile oxygenated OA (LVOOA, 39%), cooking related OA (COA, 15%) and biomass burning OA (BBOA, 13%). In our study secondary organic aerosol (SOA) has been identified as one of the most important contributors to the submicron particle (PM 1) mass concentration. A comparison between SVOOA and submicron forest organic aerosol mass (SFOM) was performed, and a good correlation of 0.75 between them was found. In our study the SOA concentration dependence on temperature was explored in 3 means: firstly, by investigating aerosol mass spectra measured during hot and cold days. It has been found that during hot days events signal intensities of m/z 42, 43, 45, 53 and 59 were about 2.1-2.7 times higher compared to those during cold days. Secondly, by investigating the temperature dependence of SVOOA and estimated SFOM. It has been found that SFOM and SVOOA concentrations increase with temperature. Thirdly, by assessing the

Исследована реакция глубокого окисления токсичных органических соединений - фенола и его нитро- и хлорпроизводных в окислительной среде, генерированной электрохимически in situ. Определены кинетические параметры процесса и конечные продукты окисления. В качестве аналитического метода контроля разложения фенолов предложен стандартный метод определения химического потребления кислорода в пробе

Рассмотрены методы очистки воды от биологических и химических загрязнений, связанные с различными типами электрических разрядов и режимов работы. Обсуждаются достоинства и недостатки различных электроразрядных методов очистки применительно к конкретным видам загрязнений, их энергоэффективность и перспективы промышленного применения. Показано, что тип разряда в одной и той же системе может зависеть как от электротехнических параметров разрядной цепи, так и от геометрических, совокупность которых определяет характер развития разряда, что в свою очередь, влияет на особенности протекания реакций в жидкости. Обсуждается дальнейшая оптимизация этой технологии.This paper presents advanced water purification oxidative methods capable of decomposing toxic compounds into smaller molecules with possible full mineralization up to CO2 and H2O. Electrical discharge plasma contact with water occupies a promising position among the advanced oxidation methods, since such a mechanism allows the gener...

Electrostatic precipitators' problems and experimental results in point-to-plane or wire-to-cylinder systems indicate that the presence of a thin layer of porous dielectric material on the electrodes increases the discharge current for the same applied potential. This so-called Back-Corona effect, which generally reduces the sparking potential, depends on the active electrode polarity; nature, and thickness and porosity of the insulating layer; and position on the active or passive electrode of the deposited particles or insulating layer. In laboratory experiments in a point-to-plane device, with a dielectric porous layer on the plane, the current may be many times higher than its "normal" value (clean electrodes). In a DC negative wire-to-cylinder system, where the ozone concentration depends quasi directly on the discharge current, it appears possible to increase the ozone production, for the same running conditions (gas flow, electrical circuit, etc.).