Remarks on stability of inverted pendula

Using linearization principle and tools from chronological calculus one establishes a criteria for stabilization of, usually unstable, equilibrium position of Double Inverted Pendula when subject an arbitrary fast oscillation. Both, planar and spherical cases are considered.Fundação para a Ciência e a Tecnologia (FCT)Dipartimento di Matematica per le Decisione, Università di Firenze, Itali

Gravitational orientation of the orbital complex, Salyut-6--Soyuz

A simple mathematical model is proposed for the Salyut-6-Soyuz orbital complex motion with respect to the center of mass under the one-axis gravity-gradient orientation regime. This model was used for processing the measurements of the orbital complex motion parameters when the above orientation region was implemented. Some actual satellite motions are simulated and the satellite's aerodynamic parameters are determined. Estimates are obtained for the accuracy of measurements as well as that of the mathematical model

Hardware and software installation for the research of luminescent processes in the temperature range 4-500 K

In paper the description of the apparatus and software complex intended for researches radiation and thermally stimulated of processes in solids at 4-500 К is resulted. Hardware-software complex is applicable for laboratory works at the rate of solid state physics, as well as for scientific research. Working capacity of a complex is illustrated by the data of measurements of spectra thermoluminescence (TL), energized X-ray or an ultraviolet radiation at 8 К and phototransfered luminescence (PTTL) crystals an anion-defective corundum. The gained results in comparison with the literary data have shown working capacity of a complex and possibility of reception with its help of new resultВ статье описан аппаратурно-программный комплекс для исследования радиационно- и термостимулированных люминесцентных явлений в диапазоне температур 4-500К. Данный комплекс применяется для проведения лабораторных работ по курсу физики твердого тела и проведения научных исследований магистрантами и аспирантами. На базе комплекса возможно проведение учебных работ по созданию автоматизированных систем научных исследований и систем автоматического управления технологическими процессами. Для апробации установки проведены исследования анион-дефектного корунда. Полученные результаты в сравнении с литературными данными показали работоспособность комплекса и возможность получения с его помощью новых данны

Technology of ultrasonic control of gas-shielded welding process

A new approach to implementation of electrode metal transfer control under MAG, MIG welding is suggested. The process ensures control of thermal and crystallization processes, stabilizes the time of electrode metal drop formation. The results of the research allow formulating the basic criteria of electrode metal transfer control via ultrasonic exposure, determining the conditions of producing a more equilibrium structure of deposit metal

Numerical adiabatic potentials of orthorhombic Jahn-Teller effects retrieved from ultrasound attenuation experiments. Application to the SrF2:Cr crystal

A methodology is worked out to retrieve the numerical values of all the main parameters of the six-dimensional adiabatic potential energy surface (APES) of a polyatomic system with a quadratic T-term Jahn-Teller effect (JTE) from ultrasound experiments. The method is based on a verified assumption that ultrasound attenuation and speed encounter anomalies when the direction of propa- gation and polarization of its wave of strain coincides with the characteristic directions of symmetry breaking in the JTE. For the SrF2:Cr crystal, employed as a basic example, we observed anomaly peaks in the temperature dependence of attenuation of ultrasound at frequencies of 50-160 MHz in the temperature interval of 40-60 K for the wave propagating along the [110] direction, for both the longitudinal and shear modes, the latter with two polarizations along the [001] and [110] axes, respectively. We show that these anomalies are due to the ultrasound relaxation by the system of non-interacting Cr2+ JT centers with orthorhombic local distortions. The interpretation of the ex- perimental findings is based on the T2g (eg +t2g) JTE problem including the linear and quadratic terms of vibronic interactions in the Hamiltonian and the same-symmetry modes reduced to one interaction mode. Combining the experimental results with a theoretical analysis we show that on the complicated six-dimensional APES of this system with three tetragonal, four trigonal, and six orthorhombic extrema points, the latter are global minima, while the former are saddle points, and we estimate numerically all the main parameters of this surface, including the linear and quadratic vibronic coupling constants, the primary force constants, the coordinates of all the extrema points and their energies, the energy barrier between the orthorhombic minima, and the tunneling splitting of the ground vibrational states.Comment: 8 pages, 3 figure