The Eect of Mechanical Loading on the Frequency of an Oscillator Circuit

We investigate the effect of mechanical strain on the frequency of an electronic oscillator embedded in an integrated circuit. This analysis is aimed at explaining a 1% inaccuracy in the oscillator frequency under test conditions prescribed by a leading supplier of semi-conductor devices. During the test the package containing the oscillator was clamped to a circuit board by mechanical pressure. By considering the nature of the oscillator we show that tensile strains of the order of 10^-4 could explain the observations via the piezoresistance effect. Both a simple one-dimensional analysis based on the beam equation and an elastic finite element simulation show that strains of this magnitude can be generated during the test

Identification of time-varying nonlinear systems using Chebyshev polynomials

AbstractThis paper is devoted to an identification of time-varying nonlinear systems using Chebyshev polynomials of the first kind. For systems being linear relatively unknown functional parameters, a method of approximate determination of these parameters has been worked out. As the identification problems are ill-posed to solve the obtained redefinite system of linear algebraic equations, a regularization method is used

Development of sers substrates based on nanoparticles obtained by pulsed laser ablation

SERS spectroscopy is an effective method for the determination of organic and biological compounds, which finds its place in many areas of human life: the analysis of works of art and food 24 YOUNG SCIENTISTS SESSION SESSION Y products, the identification of drugs and drugs, the study of biological structures, incl. at the cellular level. The creation of simple and effective SERS substrates is an urgent task in the development of this method. This paper presents the results of a study of SERS substrates based on gold nanoparticles (NPs). Gold NPs were obtained by pulsed laser ablation of an Au metal target in alcohol using a Nd:YAG laser (1064 nm, 7 ns, 150 mJ). The resulting colloidal solution was applied onto glass substrates by the drop method, varying the number of layers. The SERS characteristics were studied using a model dye rhodamine 6G using Renishaw inVia Basis Raman microscope. The samples were excited in the region of surface plasmon resonance of gold by laser radiation of 532 nm. The results of the study showed that with an increase in the number of deposited layers up to 5, the intensity of the Raman scattering of the dye increases linearly. With a further increase in the number of layers, the signal saturates. This data correlates with SEM data. At the beginning, an increase in the packing density of NPs in the plane of the substrate is observed. Accordingly, the number of "hot spots" increases, which contribute to the amplification of the signal. Further, the homogeneity of the NP layer deteriorates, and large bulk agglomerates appear. Thus, we have developed a simple method for obtaining SERS substrates, which made it possible to increase the signal intensity up to three orders of magnitude

The stabilization of unstable detonation waves for the mixture of nitromethane/methanol

Mass velocity profiles of detonation waves in mixtures of nitromethane with acetone and methanol with added diethylenetriamine sensitizer were measured using a VISAR laser interferometer. It was found that even small, about 1%, concentrations of acetone and methanol, inert diluents, led to instability of the one-dimensional detonation front in nitromethane. The results of the experiment show that the use of the sensitizer is an effective method of flow stabilization and if the concentration of the inert diluent does not exceed 10%, the detonation front becomes stable with the addition of 1% diethylenetriamine. At a higher diluent concentration, the sensitizer does not suppress the instability but decreases the oscillation amplitude by several times. The addition of diethylenetriamine to the mixture has been found to increase the detonation velocity

The concentration of cadmium and lead in the solid and finely dispersed phases of snow and hair of the population of Gorny Altai

To create a systematic database on the presence of metals in the environment and the human body, it is necessary to conduct local studies in different regions of the Russian Federation. A comprehensive analysis of the content of cadmium and lead in different coenotic links, including the human body, has not been carried out in the Altai Republic. The aim of the study was to reveal the level of lead and cadmium accumulation in the solid and finely dispersed phases of snow and hair of the population of Gorno-Altaisk. Material and methods. The content of lead and cadmium in the snow and hair of the population of Gorno-Altaisk was estimated by the atomic absorption method. Snow samples were taken in the areas of 10 central coal boilers, hair samples were taken from 122 volunteers permanently residing in the city. Results. The concentration of metals in snow water exceeded the maximum allowable concentrations: for cadmium (0.004–0.008 mg/kg) by 3.8–8.2 times; for lead (0.008–0.469 mg/kg) by 2–15.6 times. In the solid phases of snow, the content of metals exceeded the permissible level by about 3 times. The average value of the concentration of cadmium in the hair of the population was 0.16 mg/kg, which did not exceed the all-Russian reference value (0.25 mg/kg), the proportion of excess among the population was 6.5 %. The lead content (3.18 mg/kg) approximately corresponded to the all-Russian values (3.0 mg/kg), the excess was found among 43 % of the population. Conclusion. As a result of the widespread use of solid fuels, the presence of cadmium and lead in the environment increases, which is confirmed by the accumulation of these metals in the snow cover and the accumulation of the analyzed microelements in the hair of the population of Gorno-Altaisk