Showing papers by "Braunschweig University of Technology published in 1972"
TL;DR: In this article, it is shown how the analytical relations can be satisfied in a stabilized manner in order to improve the numerical accuracy of the solution of the differential equations, which leads to a modified differential system which is often stable in the sense of Ljapunov.
1,429 citations
TL;DR: In this article, a stabilization of the classical equations of two-body motion is offered, characterized by the use of the regularizing independent variable (eccentric anomaly) and by the addition of a control-term to the differential equations.
Abstract: A stabilization of the classical equations of two-body motion is offered. It is characterized by the use of the regularizing independent variable (eccentric anomaly) and by the addition of a control-term to the differential equations. This method is related to the KS-theory (Stiefel, 1970) which performed for the first time a stabilization of the Kepler motion. But in contrast to the KS-theory our method does not transform the coordinates of the particle. As far as the theory of stability and the numerical experiments are concerned we restrict ourselves to thepure Kepler motion. But, of course, the stabilizing devices will also improve the accuracy of the computation of perturbed orbits. We list, therefore, also the equations of the perturbed motion.
81 citations
TL;DR: In this paper, the optical constants n and k of magnetite have been determined in the photon energy region between 1 and 3 eV for temperatures between 77 and 300 K using reflectivity measurements.
65 citations
TL;DR: The question whether there exists a first row in such a way that half of all signs of the triangle is positive, is answered in the affirmative.
37 citations
TL;DR: In this paper, chemical analyses of some 406 widely scattered samples of Archean shale from the Superior province of the Canadian Shield have been performed and it was shown that mobile elements were removed by weathering during the Archean in approximately the same relative proportion as during later periods; and that the calcium thus liberated has not been redeposited with the shales.
27 citations
TL;DR: In this paper, a trap model for the gallium-arsenide surface region is proposed and the frequency dependence of the derived small-signal capacitance and conductance is verified by measurements.
Abstract: Capacitance/voltage characteristics of metal-insulator-semiconductor n type gallium arsenide differ considerably from the normal behaviour as observed with silicon. A trap model for the gallium-arsenide-surface region is proposed. The frequency dependence of the derived small-signal capacitance and conductance is verified by measurements.
18 citations
TL;DR: The Meggen Reef as discussed by the authors is a bioherm-like table reef which is completely surrounded by basinal sediments and formed by stromatoporoids and crinoids.
Abstract: In the course of an exploration program in 1965 in the subsurface of the southeastern Elspe Syncline (Sauerland, Rhenish Schiefergebirge) was discovered a Middle Devonian reef, unknown up to now. The foundation is not yet drilled. The Meggen Reef forms a bioherm-like table reef which is completely surrounded by basinal sediments. According to organisms, matrix and primary voids within the reef limestones 7 facies types can be distinguished. The reef core is built of stromatoporoids and crinoids, the reef flank types are characterized by corals and crinoids. The subsided reef is covered with thin, partly condensed pelagic limestones. At the same time in the adjacent basin the stratiform pyrite-sphalerite-barite ore of Meggen is deposited. At the end of Middle Devonian time the Meggen reef and the overlying pelagic limestones are brecciated and transected by numerous sedimentary dikes. As in the sedimentary dikes the same acid tuffs are occurring, which follow immediately above the pyrite-sphalerite-barite ore of Meggen, there is a close connection between submarine destruction of the Meggen Reef, acid tuff eruptions and ascent of metall-bearing hydrothermal solutions. The Meggen Reef is due to the compression while the Variscan orogeny is deformed to an overturned and thrusted anticline and itself is thrusted over from the adjacent basin facies. With respect to the development of diagenetic processes, the following stages are distinguished: (1) during reef growth, (2) between reef growth and sedimentary dike formation, (3) between sedimentary dike formation and Variscan deformation and (4) during Variscan deformation.
17 citations
TL;DR: In this article, the automatische CHNO-Mikroelementaranalyse mittels des neuen Analysators Modell 1102 (Erba, Mailand), der elektronischen Waage 4125 (Sartorius, Gottingen) und des Kleincomputers combitron =S=S= 10/10 (Diehl, Nurnberg) wird berichtet.
Abstract: Uber die automatische CHNO-Mikroelementaranalyse mittels des neuen Analysators Modell 1102 (Erba, Mailand), der elektronischen Waage 4125 (Sartorius, Gottingen) und des Kleincomputers combitron =S= 10/10 (Diehl, Nurnberg) wird berichtet. Die gesamte Anlage in Verbindung mit einem Lochstreifenstanzer, einem Lochstreifenleser und einem Interface gestattet eine in diesem Mase bisher nicht bekannte, vollautomatische Off-on-line-Mikroelementaranalyse von Kohlenstoff, Wasserstoff, Stickstoff und Sauerstoff in 23 Verbindungen.
14 citations
TL;DR: In this paper, a band theory based on Goodenough pair states is given for magnetite below the Verwey temperature, and the resulting energy gap and conduction anisotropy agree quantitatively with experiment.
11 citations
10 citations
TL;DR: In this article, a definition of cold pressure welding is given and different forming processes applied for cold pressure weldings are described, factors influencing the quality of joints are discussed and several examples for the practical use of the process are given.
Abstract: Fur das Kaltpresschweisen wird eine Begriffsbestimmung gegeben. Zum Kaltpresschweisen herangezogene Umformverfahren werden beschrieben und Einflusgrosen besprochen, die die Gute der Schweisverbindung beeinflussen. Den Abschlus bildet eine Zusammenstellung zahlreicher Anwendungsbeispiele aus der Praxis.
Recent Progress in cold pressure welding technology and its application. A definition of cold pressure welding is given and different forming processes applied for cold pressure welding are described. The factors influencing the quality of joints are discussed and several examples for the practical use of the process are given.
TL;DR: In this paper, a power output of 14 mW at 10.6 GHz has been obtained, at low modulating frequencies, the f.m. noise consists of unconverted current fluctuations.
Abstract: Fabrication of silicon Pd-n-p+ X band punchthrough transit-time diodes is described. A power output of 14 mW at 10.6 GHz has been obtained. Measurements of the f.m.-noise spectrum at maximum power output and the short-circuit-current noise are presented. At low modulating frequencies, the f.m. noise consists of unconverted current fluctuations. The f.m. single-sideband noise, 500 kHz off the carrier, is 21.5 dB.
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TL;DR: In this paper, the decay scheme of 40min 121 Xe has been investigated using isotopically separated samples produced by the ISOLDE facility at CERN, and a total number of 244 γ-transitions have been observed in this decay; 217 of them have been placed in a level scheme involving 56 excited states in 121 I.
TL;DR: In this paper, it was shown that the diffusion coefficient depends strongly on potetial: the more positive the oxidation potential is, the slower does the oxidation proceed, and the smaller is diffusion coefficient.
TL;DR: The porous nickel layers of oxygen-DSK-cathodes in alkaline fuel cells are oxidized to volumins α-Ni(OH) 2 at elevated temperatures and in this way the pores of the electrode are growing together as discussed by the authors.
TL;DR: In this article, the frequency-modulation sensitivity, frequency-pushing factor and f.m. noise were measured at bias currents with maximum microwave-power output where amplitude modulation is very small.
Abstract: Measurements of the frequency-modulation sensitivity, the frequency-pushing factor and f.m. noise are reported. At bias currents with maximum microwave-power output where amplitude modulation is very small, both the pushing factor and the f.m. noise reach low levels, which is of particular interest for practical applications.
TL;DR: In this article, the design of spring-restrained mechanisms to keep their natural frequency of oscillation constant for a large range of amplitudes is considered, and general principles and methods for approximate synthesis are developed.
TL;DR: In this paper, a method for determining the optical constants of heavily doped semiconductors in the infrared and free carrier parameters is described, which requires one reflectivity measurement only and is based upon an analysis of the reflectivity spectrum in the region of the plasma resonance frequency.
Abstract: A method for determining the optical constants of heavily doped semiconductors in the infrared and free carrier parameters is described, which requires one reflectivity measurement only. The method is based upon an analysis of the reflectivity spectrum in the region of the plasma resonance frequency. The analysis takes account of the energy dependence of the relaxation time. This method allows an accurate determination of the index of absorption even for k<0.2 in spite of the simple experimental setup. m* and τ data and optical constants so determined are presented for n- and p-type silicon.
In der vorliegenden Arbeit wird eine Methode zur Bestimmung der optischen Konstanten im infraroten Spektralbereich (bzw. der Parameter der freien Ladungstrager) von Halbleitern mit hoher Ladungstragerdichte beschrieben, die nur eine Reflexionsmessung erfordert und auf einer Analyse des Reflexionsspektrums in der Nahe der Plasmaresonanz-frequenz beruht. Die Analyse berucksichtigt die Energieabhangigkeit der Relaxationszeit der freien Ladungstrager. Mit dieser Methode kann trotz des geringen experimentellen Aufwandes der Absorptionsindex auch fur k<0,2 mit befriedigender Genauigkeit bestimmt werden. Die so bestimmten m*-und τ-Werte und die Wellenlangenabhangigkeit der optischen Konstanten von n- und p-leitendem Silizium werden angegeben.
TL;DR: In this paper, it has been shown that Al as an alloying addition accelerates hot salt corrosion of Ti by accelerating the formation of chlorine which not only destroys the passive layer on Ti but, through direct attack of grain boundaries and accumulated dislocations gives rise directly to stress corrosion cracking.
Abstract: Die Heissalz-SRK von legiertem Titan beruht, wie umfangreiche Untersuchungen gezeigt haben, masgeblich auf einer Werkstoffversprodung durch Wasserstoff, der durch intermediar gebildetes HC aufgenommen wird. Chlorwasserstoff entsteht vermutlich durch Pyrohydrolyse von AlCl3 · 6 H2O, mit dem bei der Korrosion allen aluminiumhaltigen Titanlegierungen zu rechnen ist und das einen Schmelzpunkt von 193 °C hat. Ferner scheint festzustehen, das durch den Legierungszusatz Aluminium die Entstehung von Chlor wahrend der Heissalzkorrosion von Titan beschleunigt wird. Chlor zerstort nicht nur die Passivschicht des Titans, sondern lost durch selektiven Angriff auf Korngrenzen und Versetzungsanhaufungen unmittelbar SRK aus. Um in dieser Beziehung korrosionsbestandingere Werkstoffe zu erhalten, wird man den Aluminiumgehalt reduzieren und weitere Legierungspartner, wie z. B. Mo, Zr und Si, wahlen mussen, die das Korrosionsverhalten des Titanwerkstoffs nicht oder nur wenig beeintrachtigen, zum anderen aber auch durch Verbesserung der Festigkeitseigenschaften und des Langzeitverhaltens den fehlenden Aluminiumgehalt beim Titan ausgleichen konnen.
The loss in ductility of tensile plate specimens of TA16V4 and TiA16V6Sn2 during the creep test with simultaneous attack by NaCl above 200 °C
A has been demonstrated by com prehensive research the hot salt corrosion of titanium is due to embrittlement by hydrogen absorbed via intermediarily formed HCl. HCl is probably formed by pyrohydrolysis of AlCl3 · 6 H2O the formation of which is highly probable in Al-bearing Ti alloys and which melts at 193 ° C. Beyond that it seems to be established that Al as an alloying addition accelerates hot salt corrosion of Ti by accelerating the formation of chlorine which not only destroys the passive layer on Ti but, through direct attack of grain boundaries and accumulated dislocations gives rise directly to stress corrosion cracking. In order to improve the stress corrosion resistance of Ti the Al content is reduced and other alloying elements such as e. g. Mo, Zr and Si are added; the latter have just little influence on the corrosion behaviour of Ti but, by improving the strength and the long-term stability amy compensate for the reduced Al-content.
TL;DR: In this article, the temperature dependence of the nuclear relaxation time T1 of 63Cu nuclei in the well-known Cu(Fe) Kondo alloy has been evaluated using a pulsed NMR spectrometer.
01 Jan 1972
TL;DR: In dem folgenden Abschnitt sollen einige besondere physikalische Eigenschaften des durch die Maschine stromenden Fluids beruckichtigt werden as discussed by the authors.
Abstract: In dem folgenden Abschnitt sollen einige besondere physikalische Eigenschaften des durch die Maschine stromenden Fluids berucksichtigt werden. Bei Wasser ist dies die Verdampfbarkeit, d. h. die Moglichkeit der Entstehung dampferfullter Hohlraume in der Stromung, bei Luft die Erreichung der Schallgeschwindigkeit und damit gleichfalls der Ubergang auf ein anderes Verhalten der Stromung, insbesondere die Inkaufnahme der Gefahr des Verdichtungsstoses.
TL;DR: In this article, the application of network invariants to the determination of the standing-wave ratio of unknown loads terminating uncalibrated but lossless 2-ports is discussed.
Abstract: The application of network invariants to the determination of the standing-wave ratio of unknown loads terminating uncalibrated but lossless 2-ports is discussed Two simple measurement procedures are given One requires a matched termination for the load port; the other that the load be phasable No short circuits are necessary