Thermal characterisation of micro-hotplates used in sensor structures

Micro-hotplates operated at elevated temperature form the basic element in several sensor devices, such as integrated calorimetric or Taguchi-type gas sensors and flow-rate sensors. In all of these applications thermal properties of the sensing elements play a determining role in functional operation, therefore, their accurate characterisation is essential. The micro-hotplates investigated were developed by one side porous silicon micro-machining technology, forming Pt micro-filaments embedded in non-stoichiometric silicon nitride, and suspended across a cavity. This work is dealing with the accurate temperature detection in the micro-scale by different measurement methods for the deduction of steady state and transient thermal properties from the results. Transient properties of the structure were investigated by application of a simplified thermal equivalent circuit model.     

Recording and reading of intense optical pulses based on the induced transparency

The effect of spatial localization of the atomic (Raman) coherence in the forbidden transition of a three-level atom is studied for two intense optical pulses with comparable Rabi frequencies. We propose to use this effect for coherent recording of intense optical pulses. Various schemes of reading of the recorded pulse are considered.     

Dynamics of a CW single-mode Nd:YAG laser with a Cs2 narrow-band saturable absorber

We present the results of experiments with a CW single-mode Nd:YAG laser, tunable in the vicinity of 1064 nm, with an intracavity narrow-band Cs ₂ vapor saturable absorber. It is shown that the laser dynamics is determined by both the pump level and detuning of the laser frequency from the absorption-line center.     

Characterisation of adsorbed layers on sulphide minerals by photoelectron spectroscopy

The systems galena/2-mercaptobenzothiazole (MBT) and pyrite/MBT have been studied using synchrotron radiation excited photoelectron spectroscopy (SRXPS). The chemisorption of MBT and the multilayer formation of 2,2′-dithiobis(benzothiazole) (BBTD) are evidenced by additional structures, observed beside the substrate signals, in the S2p-spectra of cleaved mineral surfaces after adsorption of MBT. The amount of the complex remains constant at concentrations as high as 10^–5 mol/L whereas the amount of BBTD increases. From the dependence of the adsorbate intensities on the excitation energy the conclusion can be drawn that an overlayer of BBTD on a chemisorbed layer of MBT is formed. The very weak adsorption of MBT on pyrite in alkaline solutions may explain the selective flotation of galena from pyrite in alkaline media.     

Interaction of soliton-like light beamsin second-order non-linear materials

We investigate numerically the interaction between two light beams, initially monochromatic, during the excitation of solitary waves in quadratically non-linear media. We show that the result of the interaction is strongly dependent on soliton oscillations occurring during excitation, generating a new class of threshold phenomena.     

A method for wave decomposition in computations for nonlinear dynamical three-dimensional towing systems

We propose a new method for computing multimode wave interactions in towing systems; our method is based on wave splitting of the equations of a model in such a way that each computational step requires computation for only one mode. The efficiency of the method is demonstrated by analysis of a concrete towing system with a turning towboat. Translated fromDinamicheskic Sistermy. Vol. 12, pp. 55–64, 1993.     

Nonhomogeneous Rankin convolutions

The properties of the Rankin convolutions of two eigenfunctions of different parities from the discrete part of the spectrum of the Laplace operator are studied. Analytical continuability of these convolutions into the left half-plane is proved and a functional equation of Riemann type is obtained. Applications to arithmetical convolutions are given. In particular the asymptotics of such convolutions is obtained by using the nonhomogeneous Rankin convolutions. Bibliography: 4 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 226, 1996, pp. 37–51.