Shear mode coupling and tilted grain growth of A1N thin films in BAW resonators.

Polycrystalline A1N thin films were deposited by RF reactive magnetron sputtering on Pt(111)/Ti electrode films. The substrates were tilted by an angle ranging from 40 degrees to 70 degrees with respect to the target normal. A low deposition temperature and a high sputter gas pressure were found ideal for tilted growth. The resulting grain tilt angle amounts to about half the substrate tilt angle. For coupling evaluation, 5 GHz solidly mounted resonator structures have been realized. The tilted grain A1N films exhibited a permittivity in the 9.5-10.5 range and loss tangent of 0.3%. Two shear modes as well as the longitudinal mode could be clearly identified. The coupling coefficient k2(eff) of the fundamental thickness shear mode (TS0) was found to be about 0.5%, which is compatible with a c-axis tilt of about 6 degrees.     

Fluxing of a 359/SiC/10p composite with alkali chlorides: effect of inclusions

The effect of salt addition, in the form of a fluxing agent containing equivalent amounts of NaCl and KCl, on the microstructure and mechanical properties of 359/SiC/10p composite has been investigated. Both microstructure and properties are affected, with the removal of magnesium and strontium and the introduction of sodium and potassium being responsible for the degradation in properties. Thermodynamic calculations have been carried out to account for the effect of salt addition in terms of the surface adsorption of sodium and potassium impurities and the consequent changes in the surface-interface tension of their binary alloys. Mechanisms for the degradation of properties have been discussed.     

Bemerkungen zum Biot-Savartschen Gesetz

Übersicht Die folgende Arbeit verfolgt u. a. auch didaktische Absichten. Das Biot-Savartsche Gesetz wird oft falsch oder mindestens sehr mißverständlich dargestellt und auch auf unzulässige Weise benutzt. Ausgangspunkt der Mißverständnisse ist die auch in vielen Lehrbüchern anzutreffende unkorrekte Aussage, man könne einem von StromI durchflossenen Linienelement ds ein magnetostatisches Feld dB [entsprechend der Gleichung (32) des folgenden Beitrags] zuordnen. Im folgenden werden derartige Aussagen untersucht und in modifizierter Form korrekt dargestellt.

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Remarks concerning the Law of Biot-Savart

Contents The following paper is at least partly of a didactic nature. The Biot-Savart law of magnetostatics is often interpreted in an illegitimate manner and consequently applied incorrectly. The source of these misunderstandings and errors is the incorrect statement that a magnetic field dB [as given by equation (32) of this paper] is caused by an electric currentI flowing along a line element ds, a statement very popular also in many textbooks. Questions related to this problem are investigated and widespread misleading statements are replaced by correct ones.

     

Guaranteed inclusions for the complex generalized eigenproblem

A method is described which produces guaranteed bounds for a solution of the generalized complex eigenproblem. The method extends a similar approach for general systems of nonlinear equations to the special case of complex pencils, where under weaker assumptions stronger assertions can be proved.     

Solar duct for lighting and ventilation Santa Amalia building Barcelona -Spain

The Santa Amalia building in Barcelona is a block of six flats incorporating a duct by which ligth is sent to the kitchens - previously without natural ligthing- and also allows natural ventilation. Moreover, the passive solar gains obtained from the extensive glazed surfaces and the conservation of internal heat gains, along with a high degree of isulation, give energy saving of 68% for heating.     

Reactive energy measurement using frequency controlled analog-to-pulse-rate converter

Contents This paper analyzes a problem of phase shifting and deseribes a novel method for electronic reactive energy measurement. The proposed measurement structure, composed of an integrator as a phase shifting circuit and a frequency controlled analog-to-pulse-rate converter, provides for the measurement completely in accordance with IEC definition of reactive energy, which is performed with simple but high performance metering device.

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Die Blindverbrauchsmessung anhand eines netzsynchronisierten Analog-Frequenz-Wandlers

Übersicht In diesem Artikel wird das Problem der Phasenverschiebung analysiert und eine neue Meßmethode für elektronische Blindverbrauschsmessung aufgezeigt. Die vorgeschlagene Strucktur, bestehend aus einem Integrator als Phasenschieber und netzkontrolliertem Analog-Frequenz-Wandler, ermöglicht die Verwirklichung eines einfachen aber präzisen Elektrizitätszählers zur Messung der Blindenergie, dessen Arbeitsprinzip mit den IEC Empfehlungen vollkommen übereinstimmt.

     

Twisted axially loaded rod with shear and compressibility

Summary Stability of a twisted and axially compressed elastic rod is analysed using the Euler method of adjacent equilibrium configuration. The constitutive equations of the rod are assumed in the form that takes into account both shear of the cross-sections and compressibility of the rod axis. It is shown that bifurcation points of the non-linear system of equations describing equilibrium are determined from the linearized system of equations. The influence of shear and compressibility on the critical values of twisting couple and compressive force is obtained. Moreover, the bifurcation pattern is examined by using the Liapunov-Schmidt method.     

On simulation methods for solving the Boltamann equation

We will give an overview of the problem and then show how to modify an already present algorithm, so that it is also useful from a practical point of view. Further we will show that this algorithm is suitable for parallel computing and prove by means of an example that it can compete with the Bird algorithm, which is almost always applied by engineers but has only a heuristic base.