231 research outputs found
A patient with abnormalities of the coronary arteries and non-compaction of the left ventricular myocardium resulting in ischaemic heart disease symptoms
Left ventricular non-compaction (LVNC) is a rare cardiomyopathy that results from unsettled embryogenesis of myocardium. It is morphologically characterised by the presence of non-compacted, this is hypertrabeculated, myocardium of the left ventricle with deep endocardial recesses. The clinical spectrum of symptoms is very wide — from asymptomatic patients through the cases of heart failure to the patients requiring heart transplantation. The diagnosis is most frequently based on the echocardiography. LVNC is often coexisted with other heart defects and coronary artery abnormalities. We described a case of a 58-year-old man with LVNC and coronary artery anomalies
Optimization of the plasma electrostatic filter using Taguchi method
We investigated the flow of carbon and metal vacuum arc plasma, produced in DC discharge with superimposed
high-current arc pulses, through the electrostatic filter. The dependence of the filtering efficiency and the ion current of
the plasma flow on the filter current, gas pressure, distance and tilt angle of the filter blinds was determined. The plan of
the experiment was developed using Taguchi method and the conditions, which guarantee maximal cleaning efficiency
at maximal plasma transmission through the filter were determined.Досліджували проходження вуглецевої та металевої вакуумно-дугової плазми, яка генерується джерелом постійного струму з накладанням сильнострумних імпульсів на струм дуги крізь електростатичний фільтр. Було визначено залежності іонного струми та ефективність фільтрації плазмового потоку від струму на фільтрі, тиску газу, відстані та кута нахилу жалюзій фільтру. План експерименту був розроблений з використанням метода Тагучі, та були визначенні умови, які гарантують максимальному ефективність очищення при максимальному коефіцієнті пропускання плазми крізь фільтр.Исследовали прохождения углеродной и металлической вакуумно-дуговой плазмы, генерируемой источником постоянного тока с наложением сильноточных импульсов на ток дуги через электростатический фильтр. Были определены зависимости ионного токи и эффективность фильтрации плазменного потока от тока на фильтре, давления газа, расстояния и угла наклона жалюзей фильтра. План эксперимента был разработан с использованием метода Тагучи, и были определены условия, которые гарантируют максимальную эффективность очистки при максимальном коэффициенте пропускания плазмы через фильтр
The effect of unintentional oxygen incorporation into Cr-CrN-DLC coatings deposited by MePIIID method using filtered cathodic vacuum arc carbon and metal plasma
The multilayer Cr-CrN-DLC coatings deposited by MePIIID method on substrates made of high speed steel HS 6-5-2 were studied. The streams of filtered carbon and metal arc plasma were used in both ion implantation and deposition phases. Investigation of the chemical composition of Cr-CrN-DLC coatings revealed considerable amount of oxygen in deposited DLC film. Additional alloying of DLC films with chromium reduced the concentration of oxygen. The presence of oxygen affects the properties of DLC coatings, which was confirmed by the investigation of the hardness and adhesion.Изучаются многослойные покрытия Cr-CrN-DLC, осажденные методом MePIIID, на подложках из быстрорежущей стали HS 6-5-2. Отфильтрованные потоки углеродной и металлической плазмы использовались в ионной имплантации и осаждении покрытий. Исследование химического состава Cr-CrN-DLC-покрытий показало значительное количество кислорода в осажденных DLC-пленках. Дополнительное легирование пленок DLC хромом сократило концентрацию кислорода. Присутствие кислорода влияет на свойства покрытий DLC, которые были подвержены исследованиям на твердость и адгезию.Вивчаються багатошарові покриття Cr-CrN-DLC, осадженні методом MePIIID, на підкладках з швидкорізальної сталі HS 6-5-2. Відфільтровані потоки вуглецевої та металевої плазми використовувались в іонній імплантації та осадженні покриттів. Дослідження хімічного складу Cr-CrN-DLC-покриттів виявило значну кількість кисню в осаджених DLC-плівках. Додаткове легування плівок DLC хромом зменшило концентрацію кисню. Присутність кисню впливає на властивості покриттів DLC, які були досліджені на твердість та адгезію
White-light flares on cool stars in the Kepler Quarter 1 Data
We present the results of a search for white light flares on the ~23,000 cool
dwarfs in the Kepler Quarter 1 long cadence data. We have identified 373
flaring stars, some of which flare multiple times during the observation
period. We calculate relative flare energies, flare rates and durations, and
compare these with the quiescent photometric variability of our sample. We find
that M dwarfs tend to flare more frequently but for shorter durations than K
dwarfs, and that they emit more energy relative to their quiescent luminosity
in a given flare than K dwarfs. Stars that are more photometrically variable in
quiescence tend to emit relatively more energy during flares, but variability
is only weakly correlated with flare frequency. We estimate distances for our
sample of flare stars and find that the flaring fraction agrees well with other
observations of flare statistics for stars within 300 pc above the Galactic
Plane. These observations provide a more rounded view of stellar flares by
sampling stars that have not been pre-selected by their activity, and are
informative for understanding the influence of these flares on planetary
habitability.Comment: 42 pages, 10 figures, 2 tables; Accepted for publication in the
Astronomical Journa
Photometric Variability in Kepler Target Stars: The Sun Among Stars -- A First Look
The Kepler mission provides an exciting opportunity to study the lightcurves
of stars with unprecedented precision and continuity of coverage. This is the
first look at a large sample of stars with photometric data of a quality that
has heretofore been only available for our Sun. It provides the first
opportunity to compare the irradiance variations of our Sun to a large cohort
of stars ranging from vary similar to rather different stellar properties, at a
wide variety of ages. Although Kepler data is in an early phase of maturity,
and we only analyze the first month of coverage, it is sufficient to garner the
first meaningful measurements of our Sun's variability in the context of a
large cohort of main sequence stars in the solar neighborhood. We find that
nearly half of the full sample is more active than the active Sun, although
most of them are not more than twice as active. The active fraction is closer
to a third for the stars most similar to the Sun, and rises to well more than
half for stars cooler than mid K spectral types.Comment: 13 pages, 4 figures, accepted to ApJ Letter
In-Use and Vehicle Dynamometer Evaluation and Comparison of Class 7 Hybrid Electric and Conventional Diesel Delivery Trucks
This study compared fuel economy and emissions between heavy-duty hybrid electric vehicles (HEVs) and equivalent conventional diesel vehicles. In-use field data were collected from daily fleet operations carried out at a FedEx facility in California on six HEV and six conventional 2010 Freightliner M2-106 straight box trucks. Field data collection primarily focused on route assessment and vehicle fuel consumption over a six-month period. Chassis dynamometer testing was also carried out on one conventional vehicle and one HEV to determine differences in fuel consumption and emissions. Route data from the field study was analyzed to determine the selection of dynamometer test cycles. From this analysis, the New York Composite (NYComp), Hybrid Truck Users Forum Class 6 (HTUF 6), and California Air Resource Board (CARB) Heavy Heavy-Duty Diesel Truck (HHDDT) drive cycles were chosen. The HEV showed 31% better fuel economy on the NYComp cycle, 25% better on the HTUF 6 cycle and 4% worse on the CARB HHDDT cycle when compared to the conventional vehicle. The in-use field data indicates that the HEVs had around 16% better fuel economy than the conventional vehicles. Dynamometer testing also showed that the HEV generally emitted higher levels of nitric oxides than the conventional vehicle over the drive cycles, up to 77% higher on the NYComp cycle (though this may at least in part be attributed to the different engine certification levels in the vehicles tested). The conventional vehicle was found to accelerate up to freeway speeds over ten seconds faster than the HEV
Development of arc suppression technique for reactive magnetron sputtering
The technique of arc suppression on the target surface of magnetron sputtering system during reactive
deposition of Al₂O₃ coatings has been developed. Damping of arcs is achieved by transient
polarity change of the magnetron voltage by means of a simple circuit consisting of a capacitor and
an inductive coil. Practically 100% arc inhibition probability is achieved during 5 - 20 мS after its
ignition. The energy input into arc before its disappearance is about 50-100 mJ. Results of experimental
and theoretical investigations of the arc suppression phenomenon are presented. Process of
the magnetron discharge transition to stationary state after the arc suppression has been studied too.
Relaxation oscillations of current and voltage accompanying this process are described. A theoretical
model of the non-stationary magnetron discharge is developed featuring its dynamic properties.
Magnetron discharge dynamic impedance is found.Розроблено методику гасіння дуг на поверхні
мішені магнетронної розпилювальної системи в
процесі реактивного нанесення покриттів Al₂O₃. Подавлення дуг відбувається шляхом тимчасової
зміни полярності напруги на магнетроні, що досягається за допомогою простого електричного
ланцюга з конденсатора та катушки індуктивності. Досягається практично 100% імовірність подавлення дуг протягом 5 – 20 мкс після їх виникнення. Енергія, що вкладається в дугу до згасання, складає 50 – 100 мДж. Надані результати
експериментальних та теоретичних досліджень
процесу дугогасіння. Досліджений також процес
переходу магнетронного розряду до стаціонарного стану після зникнення дуги. Виявлено згасаючі коливання напруги та струму, що супроводжують цей процес. Побудовано теоретичну модель нестаціонарного магнетронного розряду, яка
описує його динамічні властивості. Знайдено динамічний імпеданс магнетронного розряду.Разработана методика гашения дуг на поверхности мишени магнетронной распылительной
системы в процессе реактивного нанесения покрытий Al₂O₃. Подавление дуг производится путем кратковременной смены полярности приложенного к магнетрону напряжения при по- мощи простой электрической цепи, состоящей из
конденсатора и катушки индуктивности. Достигается практически 100% вероятность подавления дуг в течение 5 – 20 мкс после их возникновения. Энергия, вкладываемая в дугу до ее
исчезновения составляет 50 – 100 мДж. Представлены результаты экспериментальных и теоретических исследований процесса дугогашения. Исследован также процесс перехода магнетронного разряда к стационарному состоянию
после подавления дуги. Обнаружены затухающие колебания тока и напряжения, сопровождающие этот процесс. Построена теоретическая
модель нестационарного магнетронного разряда,
описывающая его динамические свойства. Найден динамический импеданс магнетронного разряда
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King County Metro Transit: Allison Hybrid Electric Transit Bus Laboratory Testing
Paper summarizes chassis dynamometer testing of two 60-foot articulated transit buses, one conventional and one hybrid, at NREL's ReFUEL Laboratory. It includes experimental setup, test procedures, and results from vehicle testing performed at the NREL ReFUEL laboratory
Long-term chromospheric activity in southern M dwarfs: Gl 229 A and Gl 752 A
Several late-type stars present activity cycles similar to that of the Sun.
However, these cycles have been mostly studied in F to K stars. Due to their
small intrinsic brightness, M dwarfs are not usually the targets of long-term
observational studies of stellar activity, and their long-term variability is
generally not known. In this work, we study the long-term activity of two M
dwarf stars: Gl 229 A (M1/2) and Gl 752 A (M2.5). We employ medium resolution
echelle spectra obtained at the 2.15 m telescope at the Argentinian observatory
CASLEO between the years 2000 and 2010 and photometric observations obtained
from the ASAS database. We analyzed Ca \II K line-core fluxes and the mean V
magnitude with the Lomb-Scargle periodogram, and we obtain possible activity
cycles of 4 yr and 7 yr for Gl 229 A and Gl 752 A respectively.Comment: Accepted for publication by Astronomical Journal (AJ
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