A Klein Gordon Particle Captured by Embedded Curves

In the present work, a Klein Gordon particle with singular interactions supported on embedded curves on Riemannian manifolds is discussed from a more direct and physical perspective, via the heat kernel approach. It is shown that the renormalized problem is well-defined, and the ground state energy is unique and finite. The renormalization group invariance of the model is discussed, and it is observed that the model is asymptotically free.Comment: Published version, 13 pages, no figures. arXiv admin note: substantial text overlap with arXiv:1202.356

Nondestructive Methods for the Determination of Mechanical Properties of Materials

The nondestructive determination of mechanical properties of materials is desirable because of the rising cost of both materials and labor as well as safety concerns. In most alloys, changes in thermal and/or mechanical history results in microstructural changes and consequently different mechanical properties. Thermal or mechanical cycles may result from processing or occur in service. Therefore nondestructive detection of microstructure and mechanical properties would prove useful in all phases of metallurgical use. This paper reports on efforts to determine selected mechanical properties of structural materials by nondestructive means such as electrical, acoustic and magnetic techniques as well as hardness. Various thermal and mechanical conditions have been imposed on aluminum, titanium and ferrous alloys to arrive at a wide range of mechanical properties. It is concluded that the intimate knowledge of the microstructure and environmental effects are essential to select the nondestructive method that is most sensitive to property changes

Nondestructive Methods for Determination of Mechanical Properties of Aluminum and Titanium Alloys

In general, the mechanical properties of an alloy are determined by the microstructure that results from the alloy’s thermo-mechanical history. The thermo-mechanical path in alloy processing is chosen to take advantage of a least one of several strengthening mechanisms such as grain size, dispersion strengthening or dual phase structures. Optimization of an alloy’s strength is accomplished by control of the microstructure which determines the operative strengthening mechanism. Therefore NDE techniques sensitive to microstructural changes should prove useful in detecting mechanical property differences. In this work, various thermo-mechanical treatments have been used on aluminum and titanium alloys to provide a wide range of mechanical properties. From the results obtained it is concluded that selection of an NDE detection plan depends on the alloy’s thermo-mechanical history and will vary with alloy system.</p

Schroedinger operators with singular interactions: a model of tunneling resonances

We discuss a generalized Schr\"odinger operator in $L^2(\mathbb{R}^d), d=2,3$, with an attractive singular interaction supported by a $(d-1)$-dimensional hyperplane and a finite family of points. It can be regarded as a model of a leaky quantum wire and a family of quantum dots if $d=2$, or surface waves in presence of a finite number of impurities if $d=3$. We analyze the discrete spectrum, and furthermore, we show that the resonance problem in this setting can be explicitly solved; by Birman-Schwinger method it is cast into a form similar to the Friedrichs model.Comment: LaTeX2e, 34 page

Internal friction peaks due to interstitials in bcc alloys

Richter's and Snoek's original works established the existence of an anelastic relaxation produced by a stress-induced interstitial reorientation in bcc metals. This anelastic relaxation, now referred to as a Snoek peak, has been studied extensively and well characterized in the past for the interstitials carbon, nitrogen, and oxygen. The existence of a hydrogen Snoek peak in bcc metals has been a matter of some controversy, however. We have studied relaxation peaks in V, Nb, and V-Nb alloys recently. The alloys have complete mutual solubility and are of interest since they have an extremely high room temperature solid solubility for hydrogen. They also have, over a certain composition range, not shown any hydride phase precipitation at temperatures as low as 4K. Thus, if a hydrogen Snoek peak does exist, it should be found in such alloys. Indeed there is evidence now of a spectrum of hydrogen relaxation peaks below room temperature. Furthermore, there is a large misfit of V in Nb and Nb in V and, possibly, some chemical interaction such that trapping (or antitrapping) of the interstitials at the substitutional sites, causing solute-interstitial peaks, can be characterized. The present paper provides an overview of our observations regarding: the effect of hydrogen on the oxygen and nitrogen Snoek peaks in pure V and Nb, The oxygen relaxation peaks in V-Nb alloys, The hydrogen relaxation spectrum in V-Nb alloys, and the effect of oxygen on the hydrogen relaxation spectrum in V-Nb alloys. 52 refs., 13 figs., 3 tabs

Nondestructive Methods for the Determination of Mechanical Properties of Materials

The nondestructive determination of mechanical properties of materials is desirable because of the rising cost of both materials and labor as well as safety concerns. In most alloys, changes in thermal and/or mechanical history results in microstructural changes and consequently different mechanical properties. Thermal or mechanical cycles may result from processing or occur in service. Therefore nondestructive detection of microstructure and mechanical properties would prove useful in all phases of metallurgical use. This paper reports on efforts to determine selected mechanical properties of structural materials by nondestructive means such as electrical, acoustic and magnetic techniques as well as hardness. Various thermal and mechanical conditions have been imposed on aluminum, titanium and ferrous alloys to arrive at a wide range of mechanical properties. It is concluded that the intimate knowledge of the microstructure and environmental effects are essential to select the nondestructive method that is most sensitive to property changes.</p

Problem solving of low data throughput on mobile devices by artefacts prebuffering

The paper deals with a problem of low data throughput on wirelessly connected mobile devices and a possibility to solve this problem by prebuffering of selected artefacts. The basics are in determining the problem parts of a mobile device and solve the problem by a model of data prebuffering-based system enhancement for locating and tracking users inside the buildings. The framework uses a WiFi network infrastructure to allow the mobile device determine its indoor position. User location is used for data prebuffering and for pushing information from a server to PDAs. All server data are saved as artefacts with its indoor position information. Accessing prebuffered data on a mobile device can significantly improve a response time needed to view large multimedia data. The solution was tested on a facility management information system built on purpose with a testing collection of about hundred large size artefacts

Mikrosystemtechnik Aus- und Bewertung der indirekt-spezifischen Massnahme. Erster Erfahrungsbericht

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