Theoretical aspects of technological mechanics. 5. Extremal principles and verification of theories regarding the machining of metals. Part 1

The conventional understanding of extremal principles is shown to be imprecise. The many assumptions made in theories regarding the machining of metals are shown to have a considerable effect on their reliability. The need for thorough experimental verification of theoretical conclusions is established.     

Theoretical aspects of technological mechanics. 4. The plasticity condition, strengthening, and the stress-strain relationship

It is shown that preferences cannot be unambiguously assigned to different plasticity conditions. Strengthening is described, and relations between the stress and strain are established.     

Theoretical aspects of technological mechanics: 1. Fundamentals of continuum mechanics

Fundamental principles of continuum mechanics are outlined and its basic subdisciplines are identified.     

Modeling of prebreakdown stage of gaseous discharge

A mathematical model of electron cascade transfer is presented. It is developed for studying the prebreakdown stage of gaseous discharge based on the kinetic equation for electrons in a self-consistent electromagnetic field. An elastic scattering of electrons, excitation of molecules by electron impact, and impact ionization are taken into account. A natural ionization background is used as the initial distribution of free electrons. The results of the computational experiment are compared to the data of measurements of drift velocity and the average energy of electrons of discharge, as well as the Townsend coefficient in a flat charged condensor filled with diluted xenon. The comparison showed that the model is not in contrast with the experiment. In order to contract the volume of the discharge’s full current calculation, a transport approximation is built. It is based on the averaging of angular scattering. The applicability of the transport approximation for modeling the full current of the capillary discharge is studied.     

Comparison Studies of Hydrogen Flame in Cocurrent Supersonic Air Flow during Registration of Radiation in Different Spectral Ranges

Results of the experiments are given in which optical methods are used to investigate the pattern of hydrogen burnout in the case of burning in a cocurrent supersonic off-design (overexpanded) air jet. The images of flames are compared during the registration of hydrogen–air flame radiation in the ultraviolet, visible, and infrared wavelength ranges. Analysis of the obtained data reveals that the radiation of OH radical in the ultraviolet range allows the most accurate determination of the structure of heat release zones, the flame boundaries, and the completeness of combustion in the given conditions. Conclusions are drawn about the possibilities of obtaining quality information about the combustion zones by registering the flame radiation in the visible spectrum and excited H₂O molecules in the infrared region.     

Comparative characteristics of steroidogenesis and its biorhythm in the hyperfunctioning adrenal cortex

The paper summarizes the results od several studies of the daily rhythms of steroid hormones in patients with ACTH-dependent Itsenko-Cushing's disease (CD) and congenital adrenal hyperplasia (late-onset forms) (CAH). Normal daily rhythms of adrenal C21- and C19-steroids and ACTH were observed in 23.5% of CD patients. CAH patients had the marked daily rhythms of adrenal androgens and testosterone which were typical of those of cortisole. The ratios of steroid hormones to its precursors provide evidence for enhanced activities of 17-, 11 beta- and 18-hydroxylases in CD patients and normal enzymatic activities in CAH patients, whereas 21-hydroxylase being an exception.     

Resistive Switching in Memristors Based on Ge/Si(001) Epitaxial Layers

Semiconductors - The Ag/Ge/Si(001) stacks with threading dislocations growing through the Ge epitaxial layers (ELs) manifested bipolar resistive switching (RS) between two metastable resistance...     

A formally based parallelization of data mining algorithms for multi-core systems

We describe a novel, systematic approach to efficiently parallelizing data mining algorithms: starting with the representation of an algorithm as a sequential composition of functions, we formally transform it into a parallel form using higher-order functions for specifying parallelism. We implement the approach as an extension of the industrial-strength Java-based library Xelopes, and we illustrate its use by developing a multi-threaded Java program for the popular naive Bayes classification algorithm. In comparison with the popular MapReduce programming model, our resulting programs enable not only data-parallel, but also task-parallel implementation and a combination of both. Our experiments demonstrate an efficient parallelization and good scalability on multi-core processors.

     

Congratulations from the central committee of the communist party of the Soviet Union and USSR Council of Ministers to builders,assemblers, designers,mechanical engineers,and all participants in the construction of the Zeya hydroelectric station

Papers

Congratulations from the central committee of the communist party of the Soviet Union and USSR Council of Ministers to builders, assemblers, designers, mechanical engineers, and all participants in the construction of the Zeya hydroelectric station