Non-destructive beam cross-section detector at the MMFL LEBT

The maiden outcomes of a television application for monitoring on the MMFL Proton Injector beam parameters are adduced. In the basis of a system it is non-interrupted ionization detector reshaping the beam cross-section image. The system provides rendition of cross-section and storage information, allows controlling the density distribution, its vertical and horizontal profiles and their width as well as position of the beam main point. The capability of temporary parameters diagnostics are beam structure shape and extension is simultaneously afforded.Приведено перші результати застосування ТВ контролю параметрів пучка протонного інжектора ЛП ММФ. В основі системи – непорушуючий іонізаційний датчик, що формує зображення перетину пучка. Система забезпечує візуалізацію перетину й архівацію вимірів, дозволяє контролювати розподіл щільностіпучка по перетині, його вертикального і горизонтального профілів, їхньої ширини і положення центра ваги пучка. Одночасно надається можливість діагностики часових параметрів – форми і довжини структури пучка.Приведены первые результаты применения ТВ контроля параметров пучка протонного инжектора ЛУ ММФ. В основе системы – ненарушающий ионизационный датчик, формирующий изображение сечения пучка. Система обеспечивает визуализацию сечения и архивацию измерений, позволяет контролировать распределение плотности пучка по сечению, его вертикального и горизонтального профилей, их ширины и положения центра тяжести пучка. Одновременно предоставляется возможность диагностики временных параметров – формы и протяжённости структуры пучка

Modelling spectral and timing properties of accreting black holes: the hybrid hot flow paradigm

The general picture that emerged by the end of 1990s from a large set of optical and X-ray, spectral and timing data was that the X-rays are produced in the innermost hot part of the accretion flow, while the optical/infrared (OIR) emission is mainly produced by the irradiated outer thin accretion disc. Recent multiwavelength observations of Galactic black hole transients show that the situation is not so simple. Fast variability in the OIR band, OIR excesses above the thermal emission and a complicated interplay between the X-ray and the OIR light curves imply that the OIR emitting region is much more compact. One of the popular hypotheses is that the jet contributes to the OIR emission and even is responsible for the bulk of the X-rays. However, this scenario is largely ad hoc and is in contradiction with many previously established facts. Alternatively, the hot accretion flow, known to be consistent with the X-ray spectral and timing data, is also a viable candidate to produce the OIR radiation. The hot-flow scenario naturally explains the power-law like OIR spectra, fast OIR variability and its complex relation to the X-rays if the hot flow contains non-thermal electrons (even in energetically negligible quantities), which are required by the presence of the MeV tail in Cyg X-1. The presence of non-thermal electrons also lowers the equilibrium electron temperature in the hot flow model to <100 keV, making it more consistent with observations. Here we argue that any viable model should simultaneously explain a large set of spectral and timing data and show that the hybrid (thermal/non-thermal) hot flow model satisfies most of the constraints.Comment: 26 pages, 13 figures. To be published in the Space Science Reviews and as hard cover in the Space Sciences Series of ISSI - The Physics of Accretion on to Black Holes (Springer Publisher

КЛИНИКО-ФУНКЦИОНАЛЬНАЯ ОЦЕНКА БИОЛОГИЧЕСКОГО ПРОТЕЗА “ASPIRE” ПРИ ХИРУРГИЧЕСКОЙ КОРРЕКЦИИ МИТРАЛЬНЫХ КЛАПАННЫХ ПОРОКОВ

Aim: To assess clinical and functional efficacy of implanted biological prosthesis “ASPIRE” (manufactured by Vascutek) for correction of mitral valve disease.Materials and methods: From October 2008 to December 2013, biological prostheses “ASPIRE” (Vascutek) were implanted to 34 patients with mitral valve disease (mean age 63.59 ± 4.96 years, 79.4% female). From these, 24 patients had mitral stenosis and 10 patients had mitral insufficiency. 73.5% of all patients had heart failure Strazhesko-Vasilenko IIA grade and 85.3% of patients had chronic heart failure NYHA III. Isolated mitral valve replacement was performed only in 8 (23.5%) of patients. In 22 (64.7%) of cases mitral valve replacement was combined with tricuspid valvuloplasty in various modifications. Duration of cardiopulmonary bypass and of aortic clamping was 88.09 ± 25.95 and 65.68 ± 25.51 minutes, respectively. Before and after surgery all patients underwent echocardiographic assessment and clinical assessment of their general status.Results: In-hospital mortality was 5.88% (n = 2) and was related to multiorgan failure in the early postoperative period. All 32 (94.12%) surviving patients improved with decrease or complete disappearance of heart failure. Postoperative complications were typical for cardiac surgery. There were no episodes of embolism, structural dysfunction, thrombosis of the prosthesis and endocarditis of the prosthesis in the early postoperative period. Pressure gradients across prosthetic valves were not high and corresponded to good clinical and hemodynamic results in the early postoperative period.Conclusion: Taking into account good immediate results of mitral valve replacement, as well as no need in lifelong anticoagulation in patients with multiple concomitant disorders, implantation of the biological prosthesis “ASPIRE” (Vascutek) could become a procedure of choice for correction of valve abnormalities in patients above 65 years. For more comprehensive assessment of the implanted prosthesis, it is necessary to further assess long-term results of valve replacement.Цель – оценить клиническую и функциональную эффективность имплантации биологического протеза “ASPIRE” фирмы Vascutek при коррекции митральных клапанных пороков.Материал и методы. С октября 2008 г. по декабрь 2013 г. 34 пациентам (средний возраст 63,59 ± 4,96 года, женщин – 79,4%) с митральным пороком сердца выполнена имплантация биологического протеза “ASPIRE” фирмы Vascutek. Из них митральный стеноз был у 24 пациентов, недостаточность митрального клапана – у 10. Из 34 пациентов у 73,5% выявлена недостаточность кровообращения IIА стадии по Стражеско – Василенко, у 85,3% – хроническая сердечная недостаточность III функционального класса по классификации Нью-Йоркской кардиологической ассоциации (NYHA). Изолированное протезирование митрального клапана выполнялось только у 8 (23,5%) пациентов. В 22 (64,7%) случаях протезирование митрального клапана сочеталось с пластикой трехстворчатого клапана в различных модификациях. Время искусственного кровообращения и длительность пережатия аорты составили 88,09 ± 25,95 и 65,68 ± 25,51 минуты соответственно. В до- и послеоперационном периоде всем пациентам выполнялись эхокардиографическое исследование, клиническая оценка общего состояния.Результаты. Госпитальная летальность составила 5,88% (n = 2) и была связана с развитием полиорганной недостаточности в раннем послеоперационном периоде. У всех 32 (94,12%) выживших пациентов выявлено улучшение в виде уменьшения или полного исчезновения явлений недостаточности кровообращения. Послеоперационные осложнения носили общий для кардиохирургических операций характер. Тромбоэмболий, структурной дисфункции, тромбоза протеза и протезного эндокардита в раннем послеоперационном периоде выявлено не было. Невысокие транспротезные градиенты давления соответствовали хорошим клиническим и гемодинамическим результатам в раннем послеоперационном периоде.Заключение. Учитывая хорошие непосредственные результаты протезирования митрального клапана, а также отсутствие необходимости в пожизненной антикоагулянтной терапии у пациентов с большим количеством сопутствующих заболеваний, имплантация биологического протеза “ASPIRE” фирмы Vascutek может стать операцией выбора при коррекции клапанной патологии у пациентов старше 65 лет. Для более полной оценки имплантированного протеза необходимо дальнейшее изучение отдаленных результатов протезирования

Strength, fatigue strength and toughness of dissimilar Ti17–Ti64 linear friction welded joints: Effect of soft surface contamination and depletion of α precipitates

International audienceThe effect of microstructure of three dissimilar Ti17–Ti64 linear friction welded joints on the strength, fatigue strength and fracture toughness was studied. A special attention was paid to role of soft contaminants and α precipitate depletion. Three joints were produced: one in the as machined state after electrical discharge machining, one ground prior to welding, and one welded in the as machined state and post-weld heat treated. The microstructure of the weld centre zone (WCZ) exhibited an acicular entangled martensite with a Widmanstätten morphology on the Ti64 side and fine equiaxed distorted β grains on the Ti17 side. A depletion of the strengthening α precipitates was observed in the WCZ and the thermo-mechanically affected zone (TMAZ) on the Ti17 side. For the studied welding parameters, the LFW self-cleaning mechanism failed to extrude the contaminants in the weld interface of the joint welded in the as machined state. These contaminants were related to prior to welding machining and were denominated soft contaminants due to their relatively low melting point. A defect layer was formed that led to a pseudo-brittle fracture in at the WCZ during tensile testing, cyclic loading and fracture toughness testing. During tensile testing of the joint that was ground prior to welding, failure occurred after plastic deformation sometimes at the Ti64 parent material (PM) and sometimes at the Ti17 TMAZ. Fatigue cracks initiated at the latter weak zone with a reduced fatigue strength. Compared to the PM, fracture toughness of samples even without fatigue pre-crack was also reduced. Failure at the weak zone highlighted unexpected colonies of elongated dimples that nucleated on transgranular deformation lines

Precipitation-hardness map for Al–Cu–Mg alloy (AA2024-T3)

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Combined synchrotron X-ray diffraction, dilatometry and electrical resistivity in situ study of phase transformations in a Ti2AlNb alloy

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Composition dependence of tracer diffusion coefficients in Fe–Ga alloys: A case study by a tracer-diffusion couple method

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Modelling Distorins in induction heat treatment processes

International audienceThe purpose of this work is to present a computational model aimed at predicting distortions in surface induction heat treatment process followed by a quenching stage for complex 3-D parts. The work is based on a coupled experimental/numerical approach – with specific attention paid to accurate understanding of steel microstructural evolution during fast heating, as well as modelling of multiphysics couplings involved. We present here the main features of the numerical model. The model has been validated experimentally by comparisons with results obtained for the case of the induction heat treatment of a dumbbell sample. Numerical results are in good agreement with experimental ones for the hardness. We then show how this approach can be extended to the induction heat treatment of complex geometrical parts, such as crankshafts