Experimental study of the Ca–Mg–Zn system using diffusion couples and key alloys

Nine diffusion couples and 32 key samples were prepared to map the phase diagram of the Ca–Mg–Zn system. Phase relations and solubility limits were determined for binary and ternary compounds using scanning electron microscopy, electron probe microanalysis and x-ray diffraction (XRD). The crystal structure of the ternary compounds was studied by XRD and electron backscatter diffraction. Four ternary intermetallic (IM) compounds were identified in this system: Ca3MgxZn15−x (4.6≤x≤12 at 335 °C, IM1), Ca14.5Mg15.8Zn69.7 (IM2), Ca2Mg5Zn13 (IM3) and Ca1.5Mg55.3Zn43.2 (IM4). Three binary compounds were found to have extended solid solubility into ternary systems: CaZn11, CaZn13 and Mg2Ca form substitutional solid solutions where Mg substitutes for Zn atoms in the first two compounds, and Zn substitutes for both Ca and Mg atoms in Mg2Ca. The isothermal section of the Ca–Mg–Zn phase diagram at 335 °C was constructed on the basis of the obtained experimental results. The morphologies of the diffusion couples in the Ca–Mg–Zn phase diagram at 335 °C were studied. Depending on the terminal compositions of the diffusion couples, the two-phase regions in the diffusion zone have either a tooth-like morphology or contain a matrix phase with isolated and/or dendritic precipitates

Water Impingement Erosion of Deep-Rolled Ti64

In this work, the Liquid Impingement Erosion (LIE) performances of deep-rolling (DR) treated and non-treated Ti64 were investigated. Various erosion stages, from the incubation to the terminal erosion stages, could be observed. A full factorial design of experiments was used to study the effect of DR process parameters (Feed Rate, Spindle Velocity, Number of Passes, Pressure) on the residual stress distribution, microhardness and surface roughness of the treated Ti64 specimens. The DR-treated Ti64 specimens exhibited improved surface microhardness, surface roughness, and large magnitude of compressive residual stresses, which were attributed to the amount of cold work induced by the DR process. Although DR improved the mechanical properties of the Ti64, the results showed that the treatment has little or no effect on the LIE performance of Ti64 but different damage modes were observed in these two cases. Evolution of the erosion stages was described based on water-hammer pressure, stress waves, radial wall jetting, and hydraulic penetration modes. The initial erosion stages were mainly influenced by water-hammer pressure and stress waves, whereas the intermediate erosion stages were influenced by the combination of the four modes together. The final erosion stages contain the four modes, however the erosion was greatly driven by the radial jetting and hydraulic penetration modes, where more material was removed. The failure mechanism of the final stages of the LIE test of both DR-treated and non-treated Ti64 was characterized as fatigue fracture. However, a brittle fracture behavior was observed in the initial and intermediate erosion stages of the DR-treated Ti64, whereas a ductile fracture behavior was observed in the non-treated Ti64. This was concluded from the micrographs of the LIE damage through different erosion stages

Полевые исследования электронных тахеометров

This article presents the results of field research of two total stations (the park of geodetic instruments of the experimentally-technological laboratory of remote sensing and land resources moni-toring of the Agrarian Technological Institute of the RUDN University. This article was written based on the research practices which the authors were in the Scientific and Educational Center of the Agrari-an Technological Institute of the RUDN University. Electronic total stations, along with the receivers of the Global Navigation Satellite Systems (GNSS) currently is one of the most popular tools for the produc-tion of topographic and geodetic works. One of the important requirements of users for these surveying instruments — the accuracy of the measurement, which determines the accuracy of determining the co-ordinates of the turning points and the land area. The studies were conducted at a specialized reference geodetic network, authorized to carry out such tests, and is a benchmark tool for metrological certification of surveying instruments. For testing were chosen total stations that are most in demand in the production of topographic and cadastral surveys. The studies included a comparative analysis of the length and height of the reference sections of a linear basis, the measured electronic total stations; comparing passport data accuracy performance total station with the actual values obtained from measurements on the reference basis; Comparative analysis of the results of measurements of the lengths of sections and elevations of the reference line basis, with the reference values. The results of field studies have shown that the actual accu-racy of the measurements performed by the subjects geodetic instruments generally corresponds to the values indicated in their passport characteristics. This led to the conclusion of the suitability of total stations for precise positioning required for receipt of geospatial data ensuring land surveying and cadastral works. Analysis of the results of geodetic measurements of the reference base segments showed the discrepancy between the increase of the increase of the measured distance. Fixed deterioration of the measurement accuracy in areas where there may be potentially interfere with the precision-guided sighting axis on the reflector.В данной статье представлены результаты проведенных полевых исследований двух электронных тахеометров, входящих в парк геодезических приборов Экспериментально-технологической лаборатории дистанционного зондирования и мониторинга земельных ресурсов Аграрно-технологического института Российского университета дружбы народов. Статья написана по материалам научно-исследовательской практики, которую ее авторы проходили в Научно-образовательном центре Аграрно-технологического института РУДН. Электронные тахеометры наряду с приемниками Глобальных навигационных спутниковых систем (ГНСС) в настоящее время являются одними из самых востребованных инструментов для производства топографо-геодезических работ. Одним из важных требований, предъявляемых пользователями к этим геодезическим инструментам, - точность их измерений, от которой зависит точность определения координат поворотных точек и площадей земельных участков. Исследования проводились на специализированной эталонной геодезической сети, допущенной к проведению подобных испытаний и являющейся эталонным средством для метрологической аттестации геодезических приборов. Для испытаний были выбраны тахеометры, являющиеся наиболее востребованными при производстве топографических и кадастровых съемок. Исследования включали сравнительный анализ длин и превышений отрезков эталонного линейного базиса, измеренного электронными тахеометрами; сравнение паспортных данных точностных характеристик электронных тахеометров с фактическими значениями, полученными по результатам измерений на эталонном базисе; сравнительный анализ результатов измерений длин и превышений отрезков эталонного линейного базиса, с эталонными значениями. Результаты полевых исследований показали, что фактическая точность измерений, выполненных испытуемыми геодезическими приборами, в целом соответствует значениям, указанным в их паспортных характеристиках. Это позволило сделать вывод о пригодности исследуемых электронных тахеометров для точного определения координат, необходимых для обеспечения геопросранственными данными землеустроительных и кадастровых работ. Анализ результатов геодезических измерений отрезков эталонного базиса показал зависимость увеличения невязки от увеличения измеряемого расстояния. Зафиксировано ухудшение точности измерений в местах, где потенциально могут быть помехи для точного наведения визирной оси на отражатель

Assessment techniques, database design and software facilities for thermodynamics and diffusion

The purpose of this article is to give a set of recommendations to producers of assessed thermodynamic data, who may be involved in either the critical evaluation of limited chemical systems or the creation and dissemination of larger thermodynamic databases. Also, it is hoped that reviewers and editors of scientific publications in this field will find some of the information useful. Good practice in the assessment process is essential, particularly as datasets from many different sources may be combined together into a single database. With this in mind, we highlight some problems that can arise during the assessment process and we propose a quality assurance procedure. It is worth mentioning at this point, that the provision of reliable assessed thermodynamic data relies heavily on the availability of high quality experimental information. The different software packages for thermodynamics and diffusion are described here only briefly

Experimental study of the Al-Mg-Sr phase diagram at 400°C

TheAl-Mg-Sr systemis experimentally studied at 400∘C using EPMA and XRD techniques. It was determined that the intermetallic phases in the Al-Mg-Sr system have a tendency to form extended substitutional solid solutions. Two ternary phases were found in this system. Solubility limits of binary and ternary phases were determined and the phase equilibria among phases were established. The isothermal section of the Al-Mg-Sr system at 400∘C has been constructed using results of the phase analysis and experimental literature data

Dynamics of Non-Invasive Risk Factors of Sudden Cardiac Death after Myocardial Revascularization

Background: An attempt was made to study the effect of surgical myocardial revascularization on the processes of electrical myocardium instability underlying the occurrence of life-threatening ventricular arrhythmias, as well as the possibility of its non-invasive assessment by studying heart rate variability (HRV) and heart rate turbulence (HRT), as well as the duration and dispersion of the QT interval. Based only on the presence of viable myocardium, it is often impossible to predict the positive impact of revascularization on a patient’s prognosis, especially with reduced myocardial contractility. Moreover, given the well-studied relationship between myocardial remodeling and neurohormonal activation, non-invasive methods for assessing the autonomic regulation of cardiac activity can provide additional diagnostic information. Along with this, changes in these indicators and their prognostic role in patients with coronary artery disease after revascularization are subjects of discussion. Methods and Results: All patients underwent a comprehensive clinical and biochemical blood test, transthoracic echocardiography, tissue Doppler echocardiography, ultrasound examination of brachiocephalic arteries, selective coronary angio- and ventriculography, as well as Holter monitoring. Results show that a year after the coronary intervention, there was a significant positive trend in the frequency and structure of ventricular arrhythmias (VA). HRV indicators generally did not show significant dynamics. Only an increase in the values of the SDANN and low-frequency power (LFP) indices was noted, indicating a gradual increase in the activity of the sympathetic part of the autonomic nervous system. HRT indicators also did not show significant dynamics. A significant increase was found in the number of patients with no signs of impaired HRT. The average duration of the QT interval decreased significantly. There was also a tendency to shorten the corrected QT interval; however, it was insignificant. In terms of dispersion, both the QT interval and its corrected index, no significant dynamics were recorded in the general group of patients. Conclusion: Our study found that in patients with prior myocardial infarction, after revascularization, significant positive dynamics were recorded in life-threatening ventricular arrhythmias, but were unreliable for the indicators of autonomic regulation of cardiac activity, such as HRV and HRT

Sounding Rocket ExperimentElectronics – RTL Design and Validation

The Infrared Spectroscopy to Analyse the middle Atmosphere Composition (ISAAC) is an experimental module designed by KTH students. It consists of a Rocket Mounted Unit (RMU) and two Free-Falling Units (FFU) carried inside. The main objective of the experiment is to demonstrate ability of one FFU to track the other and to carry out measurements in cooperation. This Master’s thesis covers the development and implementation of the ejection system as well as data acquisition for the ISAAC experiment to have well-timed ejection of the FFUs and data for a post-flight analysis. Ejection control and communication is implemented in a Field-Programmable Gate Array (FPGA) using VHDL hardware description language. Newly developed firmware verification and the post-flight analysis results are also presented in the report. The ISAAC experiment was launched on May 29 from Esrange, Kiruna onboard the REXUS15 rocket.ISAAC (Infrared Spectroscopy to Analyse the Middle Atmosphere Composition) är en raketmonterad experimentmodul designad av studenter på KTH. Modulen består av en raketmonterad modul benämnd RMU (Rocket Mounted Module), i vilken två mindre fritt fallande enheter benämnda FFU (Free Falling Units) sitter monterade. Huvudmålet med experimentet är att demonstrera förmågan för den ena FFU:n att spåra den andra FFU:n samt förmågan att genomföra koordinerade mätningar. Detta examensarbete behandlar utvecklandet och implementationen av utskjutningssystemet samt datainsamlingen för ISAAC -experimentet. Dessa delar görs för att kunna genomföra utskjutningen vid en lämplig tidpunkt samt få data till efterbehandling. Utskjutningskontroll samt kommunikatio n är implementerade i en FPGA (Field Programmable Gate Array) i det hårdvarubeskrivande språket VHDL (VHSIC (Very High Speed Integrated Circuit) Hardware Description Language). Verifikation av nyutvecklad inbyggd programvara samt analysresultat av data från uppskjutningen presenteras också. Uppskjutningen av ISAAC-experimentet skedde den 29:e maj 2014 från rymdbasen Esrange i Kiruna ombord på raketen REXUS15