Performance predictions from a new optical amplifier model

We present results of a new model of semiconductor laser amplifiers which differs from previous analyses in that it includes the spectral dependence of material gain and spontaneous emission. The implications of low facet reflectivities are explored in some detail. For reflectivities below about 1 percent, the increased spontaneous emission imposes more stringent limits on current density than realized hitherto. If thermal runaway is to be avoided and gains in the range of 20-30 dB are to be achieved without excessive currents, then facet reflectivities on the order of 0.1-1 percent are probably optimal. Another consequence of including the spectral dependence is that wavelengths longer than that corresponding to the unsaturated gain peak are predicted to experience enhanced amplification at high input powers by comparison to shorter wavelengths.     

Einfaches und schnelles Verfahren zur Abschätzung der Festigkeit kaltgezogener Drähte

Schlagbiegeversuche an gezogenen Stahldrähten. Berechnung der elastischen und plastischen Biegearbeit und der Reibarbeit. Ermittlung der Festigkeit aus der gemessenen Schlagarbeit. Grenzen des Verfahrens.     

An environmental management model for the upper Nile lake system

This paper presents an ecological model which provides detailed and accurate information about the important variables governing water quality in the Upper Nile basin. Four management issues — urbanization, copper mining, the use of DDT and increased fishing activity — are explored using the model.     

Author index

There are conflicting reports in the literature as to whether epitaxial films can be grown over intermediate thin continuous carbon layers. A series of experiments was carried out on the NaClAu system in which the effect of intermediate carbon films on the epitaxy of the gold was studied. For a very limited thickness range of carbon intermediate layers, good epitaxial gold films were formed. The corresponding carbon films were stripped, and examination in the electron microscope showed that the films were continuous and free from holes greater than 10 Å in diameter. A model based on “pseudomorphic islands” in the carbon film is proposed to account for the observations.     

Eine einfache Methode zum Vergleich der Emulsionen-stabilisierenden Wirkung aufgeschlossener Milcheiwei?e

Zusammenfassung Emulsionen von reinem Speiseöl in Wasser wurden mit aufgeschlossenen Milcheiweißen als Emulgatoren unter definierten Bedingungen bei verschiedenen Temperaturen (35, 50, 70 °C) hergestellt. Das Ölbindungsvermögen und die nach Zentrifugation gemessene Stabilität der Emulsionen erwiesen sich als gute Qualitätskriterien für die Milcheiweiße, wobei insbesondere die bei hoher Temperatur hergestellten Emulsionen Aussagen ermöglichten, die mit Erfahrungen aus der Fleischerpraxis übereinstimmten.

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A simple method to compare the emulsion stabilizing capacity of caseinates

Summary Caseinates are used as emulsifiers in emulsions of pure edible oil and water prepared under standarized conditions at different temperatures (35, 50, 70 °C). The volumes of emulsified oil and the stability of the emulsions, measured after centrifugation, are good indicators for the application potential of caseinates in meat processing. The volumes from high temperature emulsions correspond particularly well with results obtained in sausage production.

     

The role of substrate accommodation in the (111)- to (100)-state transition of gold particles on alkali halides

Annealing experiments on Au particles formed by vapour diffusion into shielded regions above air-cleaved NaCl and KCl substrates and subsequent nucleation has revealed significant differences in the ability of the substrates to cause reorientation of small crystallites by migration (causing (111)-azimuthal alignment) or internal atomic relaxation to the (100) epitaxial configuration. The observed phenomena support a recent theory governing epitaxial behaviour in the vacuum-deposited f.c.c. metal-alkali halide system. Strong evidence is obtained that secondary twinning on a {111}-based Au crystallite with 〈110〉_Au//〈100〉_subst is an intermediate stage in the atomic relaxation process encountered in the (111)- to (100)-state transition.     

Thermische Simulation des Einflusses der Ziehgeschwindigkeit auf die mechanischen Eigenschaften gezogener Stahldrähte

Laboratoriumsversuche an einem Einzelzug mit 3 m/s Ziehgeschwindigkeit. Simulation des Einflusses hoher Geschwindigkeiten bis zu 20 m/s durch Erwärmung des Ziehsteins von außen. Messung der mechanischen Eigenschaften der Drähte mit 0,3 bis 0,8% C nach dem Ziehen.