Calculation of settlements for a strip foundation

A solution is presented for calculation of the total settlement of a strip foundation with allowance for additional stresses, which develop in the region under consideration due to displacement of the loaded section of the boundary, and can be determined by solving the second basic boundary problem of the plane theory of elasticity for a half plane. Expressions for the strain components of the second basic boundary problem are presented in closed form, and formulas are derived for calculation of settlement due to a uniformly distributed load. Settlements of the bed, which is composed of sandy and clayey soils, are calculated.     

Systems concept and components of fractal radio electronics: Part I. Development stages and the state of the art

A systemization is performed for the results of theoretical and experimental investigations that were obtained in radio physics and radio engineering with the help of fractal theory and the mathematical theory of fractional dimension and fractional operators with consideration for the scaling effects of real radio signals and electromagnetic fields. Classification and the analysis and synthesis methods of the components of fractal radio electronics (resistive-capacitive components with distributed parameters) with prescribed frequency characteristics, as well as the fields of application of such components, are considered. It is shown that non-linear, parametric, and other properties of simulated objects can be considered with the use of vectors of electrophysical parameters of layers and design parameters. New promising design versions of components with fractal dimensions, namely, fractal impedances, which can be used in various devices of fractal radio electronics, are proposed.     

High-voltage autotransformer frequency converters for electric drives

The application of autotransformers in high-voltage ac electric drives with transistor frequency converters is considered. Circuit designs based on independent inverters of lower voltage, which are intended for increasing the power of electric drives, are demonstrated.     

60Co content in the spent graphite masonry of commercial reactors at the siberian chemical combine

Some results of comprehensive investigations of the radioactive contamination of graphite masonry from shutdown commercial uranium-graphite reactors at the Siberian Chemical Combine are reported. The objective of the investigations was to study the distribution of radionuclides and to determine the contamination level. In the present paper information about⁶⁰Co in the gaphite of the I-1 and él-2 reactors is reported. Its content in the samples was measured by γ-spectrometry. There were about 250 graphite samples from the I-1 reactor and 200 from él-2. According to the data obtained, the surface contamination level of the blocks can be taken as the same for the entire core within the limits of the errors presented. The average⁶⁰Co contamination of the graphite in the surface of blocks from the I-1 core is 5600 ₋₅₀₀ ⁺⁵⁵⁰ Bq/g and 8400 ₋₁₀₀₀ ⁺¹²⁰⁰ Bq/g for the él-2 core. The⁶⁰Co content in the interior volume of the graphite blocks of a I-1 reactor is now 1100 ₋₁₆₀ ⁺²⁰⁰ Bq/g and 2000 ₋₃₀₀ ⁺¹³⁵⁰ Bq/g in éI-2. The⁶⁰Co activity in all blocks from the I-1 core is 1.22·10¹² Bq, and for éI-1 the figure is 2.16·10¹² Bq. 4 figures, 3 tables, 7 references. Translated from Atomnaya énergiya, Vol. 86, No. 3, pp. 183–188, March, 1999.     

Strength Analysis and Process Simulation of Subway Contact Rail Support Bracket of Composite Materials

An application of composites for construction of subway brackets is a very effective approach to extend their lifetime. However, this approach involves the necessity to prevent process-induced distortions of the bracket due to thermal deformation and chemical shrinkage. At present study, a process simulation has been carried out to support the design of the production tooling. The simulation was based on the application of viscoelastic model for the resin. Simulation results were verified by comparison with results of manufacturing experiments. To optimize the bracket structure the strength analysis was carried out as well.     

The Conjugacy Search Problem in Public Key Cryptography: Unnecessary and Insufficient

The conjugacy search problem in a group G is the problem of recovering an from given and h = x ⁻¹ gx. This problem is in the core of several recently suggested public key exchange protocols, most notably the one due to Anshel, Anshel, and Goldfeld, and the one due to Ko, Lee et al. In this note, we make two observations that seem to have eluded most people’s attention. The first observation is that solving the conjugacy search problem is not necessary for an adversary to get the common secret key in the Ko–Lee protocol. It is sufficient to solve an apparently easier problem of finding such that h = ygx for given . Another observation is that solving the conjugacy search problem is not sufficient for an adversary to get the common secret key in the Anshel–Anshel–Goldfeld protocol.     

Effect of Gas Pressure on the Properties of Electric-Arc Titanium Nitride Powders

Ultrafine titanium nitride powder is prepared by evaporating titanium in a high-current low-pressure arc discharge in a mixture of 20% N₂ and 80% Ar. It is shown that increasing the gas pressure to 32 Pa sharply reduces the particle size and improves the uniformity of the powder in particle size. The possible reasons for the markedly reduced lattice parameter of ultrafine titanium nitride are discussed.