180 research outputs found
Die Metallographie im Dienste der Hüttenkunde
No full textСканировала Верещак Т. Б.RUS: RUS: Содержание этой книжки было предметом доклада, сделанного Фридрихом Эмилем Гейном (Emil Heyn) в Берлине на V международном съезде прикладной химии, по секции металлургии. Благоприятный прием, оказанный докладу, побудил автора сделать его доступным в форме книги для более широких кругов. Автор надеялся, что эта книжка будет полезна при преподавании в высших технических училищах. Он не претендовал на то, чтобы дать полный обзор металлографии, а лишь хотел пробудить интерес к ней.UKR: Зміст цієї книжки був предметом доповіді, зробленої Фрідріхом Емілєм Гейном (Emil Heyn) у Берліні на V міжнародному з'їзді прикладної хімії, по секції металургії. Сприятливий прийом, наданий доповіді, спонукав автора зробити її доступною у формі книжки для ширших кіл. Автор сподівався, що ця книжка буде корисна під час викладання у вищих технічних училищах. Він не претендував на те, щоб дати повний огляд металографії, а лише хотів пробудити інтерес до неї.ENG: The contents of this book were the subject of a paper delivered by Fridrich Emil Heyn in Berlin at the Fifth International Congress of Applied Chemistry, Metallurgy Section. The favourable reception given to the paper prompted the author to make it available in book form to a wider audience. The author hoped that this little book would be useful in teaching at higher technical schools. He did not pretend to give a complete review of metallography, but only wanted to arouse interest in it
X-Ray Diffraction Studies of the Crystalline Structure of the Avian Egg Shell
No full textFrom x-ray studies, it is concluded that the avian egg shell is composed of calcium carbonate in the calcite modification. In the main portion (crystalline layer) the calcite occurs in large crystalline areas oriented with the hexagonal axis (17.6 A) inclined at 28 to 16° from the normal of the shell surface. With respect to the other areas, orientation is present over limited areas. The mammilla layer contains crystallites in entirely random orientation.The findings agree with the electron microscope observations by the second author (Heyn, 1936 a and b) according to whom large oriented crystals, spherulites, or dendrites would compose the main layer and small unoriented crystals the mammilla layer
Stootspanningen op transformatoren
No full textElectrical Engineering, Mathematics and Computer Scienc
Detection and location of discharges: In partuicular in plastic-insulated high-voltage cables
No full textElectrical Engineering, Mathematics and Computer Scienc
Beam control in a proton synchroton
No full textElectrical Engineering, Mathematics and Computer Scienc
Dynamic and static measurements of strongly inhomogeneous magnetic fields
No full textApplied Science
De lange weg naar snelle protonen
No full textBijna twintig jaar lang werkte een team van meer dan vijftig mensen van de Afdeling Elektrotechniek onder de bezielende leiding van prof. F.A. Heyn aan de bouw van het Delftse proton-synchrotron.Innovation SystemsTechnology, Policy and Managemen
Geodynamics of Earth's Large Low Shear Velocity Provinces. Interaction with mantle flow, plume formation, and core-mantle boundary deformation
No full textCongruent evaporation temperature of molecular beam epitaxy grown GaAs (001) determined by local droplet etching
No full textThe congruent evaporation temperature Tc of GaAs (001) is critical for many technological processes and is fundamental to the control and stability of Ga droplets for quantum structure fabrication. We apply the technique of local droplet etching (LDE) to measure Tc for technologically important molecular beam epitaxy (MBE) grown GaAs (001). Below Tc, Ga droplets deposited on the surface shrink and form nanoholes via LDE and thermal widening. Above Tc, droplets grow by capturing excess Ga. From the transition between both regimes, we determine Tc = 680 ± 10 °C. Additionally, we find that the nanohole/droplet densities follow an Arrhenius-type temperature dependence with an activation energy of 1.31 eV. The method probes the stability of pre-existing droplets formed by deposition and so avoids the complication of nucleation barriers and readily allows the measurement of Tc for technologically important planar GaAs surfaces in any standard MBE system.
The authors thank S. Schnüll for MBE growth and the Deutsche Forschungsgemeinschaft for financial support via HA 2042/6-1. D.E.J. acknowledges the support from a Marie Curie International Incoming Fellowship
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