Diffusion of vanadium,chromium, and manganese in copper

The diffusion coefficients of vanadium, chromium and manaanese in copper have been determined by the residual activity method with radioactive tracers V⁴⁸, Cr⁵¹ and Mn⁵⁴ in the temperature ranges between 955 and 1342 K, between 999 and 1338 K and between 971 and 1253 K, respectively. The temperature dependence of the diffusion coefficients is expressed by the following Arrhenius equations along with the probable errors:D _V/Cu = (2.48 _-0.44 ^+0.53 ) x 10⁻⁴ exp [-(215 ± 2) kJ mol⁻¹/RT] m² per s,D _Cr/Cu = (0.337 _-0.090 ^+0.124 ) x 10⁻⁴ exp [-(195 ± 3) kJ mol⁻¹/RT] m² per s,D _Mn/Cu = (1.02 _-0.18 ^+0.22 ) x 10⁻⁴ exp [-(200 ± 2) kJ mol⁻¹/RT] m² per s. Anomalous penetration profiles for the diffusion of Cr⁵¹ and Mn⁵⁴ in the present results suggest that experimental results onD _Cr/Cu andD _Mn/Cu in the past have been influenced by oxidation and evaporation of the chemically active radiotracers during annealing for diffusion. formerly Graduate Student, Tohoku University     

Capturing of transition by the RNG based algebraic turbulence model

This paper concerns the RNG based algebraic turbulence model. This model has characteristics to capture transitional process from laminar to turbulent flow. This is determined by the argument of the Heaviside function, which becomes a threshold for the occurrence of turbulence. It is supposed that proper modeling of this argument will lead to correctly capture transition location. In the present paper, this argument is modeled in such a way that the form of cubic equation for the turbulent kinematic viscosity be maintained. Moreover, the length scale which is required to calculate the turbulent kinematic viscosity is newly proposed, taking into account the freestream pressure gradient. The validation is performed by comparing the calculated results with the empirical expressions as well as the experimental data. This model can simulate the streamwise intermittency effect, by which a sudden increase of skin friction is prevented. Moreover, the transition location can be predicted within reasonable accuracy compared with the experimental data.     

Studies on syntheses and permeabilities of special polymer membranes. 40. Formation conditions of finger-like cavities of cellulose nitrate membranes

The permeation characteristics for polymer aqueous solution and asymmetric structure of cellulose nitrate membranes, in particular the finger-like cavity in the back sponge layer of these membranes, were investigated by changing the preparation conditions of the membranes— the casting solvent, evaporation period, and gelation medium. The formation of the finger-like cavity was dependent on absorption of a water molecule into the casting mixture from the atmosphere during the solvent evaporation process and the exchange velocity between the casting solvent and the gelation medium. The mechanism and conditions for the formation of a finger-like cavity in cellulose nitrate membranes were discussed.     

A primitive study of a fire detection method controlled by artificial neural net

Various fire detection methods have been proposed worldwide, but it is quite difficult for them to discriminate between real fire in its incipient stage and nongenuine fire phenomena which often occur.

Lately, extensive studies on neural nets which imitate neural circuits of the human brain and work in computers like brains have been made in many fields. These neural nets are capable of handling pattern-matching of analogue input and output which has so far been said to be difficult. Furthermore, more precise fire discrimination can be expected if they are adapted to the process of fire detection judgement.

For evaluation of performance of the neural net formed with three layers, i.e. the input, hidden and output layers, analogue input data and results were given to the net which in turn learnt the relation by a back-propagation method. The definitions of input and output were stored as strength of strings between two layers of the net. Thus, the net can obtain results very close to expectation from what has been learnt even with an undefined combination of input values. Unlike a conventional pattern-matching method, it is capable of giving answers to any inputs without fail. In addition, the learned neural net does not give such answers as would differ so much from the practical use, even if there aren't a sufficient number of patterns in the definition table. It also requires less memory size and time to make decisions. Therefore, it will be easy to put this neural net into practice in the future.     

Modeling an international co-operative global complementary production system

This paper aims to design a production planning and control system to realize high productivity and low inventory in the international cooperative global complementary production system for mutual country's development.     

Computer analysis of random and channeled backscattering spectra

Three types of computer codes are described which simulate random and channeled backscattering spectra from: (1) multielemental, multilayered structures, (2) specimens with inhomogneously distributed impurities and (3) single crystals damaged by ion implantation. Both effects of energy fluctuation and isotopic shifts from each constituent element are taken into account in the simulation. The elemental compositions and layer thicknesses of multielemental, multilayered films and the damage distributions induced by ion implantation are determined by fitting the simulated spectrum to the corresponding experimental one. The effect of surface and interface roughness on the spectrum shape is also discussed.     

Research and development of inelastic analysis procedures for reactor component design in Japan

The paper presents a survey of the activities taken by the JSME Subcommittee on Research and Development of Methods for Inelastic Structural Analysis to promote inelastic analysis procedures for high temperature reactor component design. An overview of benchmark test problems for the qualification of computer programs is given.     

Emissivity of chlorinated polyethylene

The emissivity of chlorinated polyethylene containing varying amounts of combined chlorine has been investigated. It was found that the emissivity of these compounds increases significantly with increase in chlorination.