Journal Articles on Category: Technology and Engineering

This paper deals with the application of phase change materials (PCM) for thermal management of integrated circuits as a viable alternative to active forced convection cooling systems. The paper presents an analytical description and solution of heat transfer, melting and freezing process in 1D which is applied to inorganic crystalline salts. There are also results of numerical simulation of a real 3D model. These results were obtained by means of the finite element method (FEM). Results of 3D numerical solutions were verified experimentally.

Issn:12102512

Keywords: Phase change ; FEM ; heat ; integrated circuit

Volume: 16

Pages: 50-55

Anticipated developments in the consumer energy market have led developers of nuclear energy concepts to consider how innovations in energy technology can be adapted to meet consumer needs. Properties of molten lead or lead-bismuth alloy coolants in lead-cooled fast reactor (LFR) systems offer potential advantages for reactors with passive safety characteristics, modular deployment, and fuel cycle flexibility. In addition to realizing those engineering objectives, the feasibility of such systems will rest on development or selection of fuels and materials suitable for use with corrosive lead or lead-bismuth. Three proposed LFR systems, with varying levels of concept maturity, are described to illustrate their associated fuels and materials challenges. Nitride fuels are generally favored for LFR use over metal or oxide fuels due to their compatibility with molten lead and lead-bismuth, in addition to their high atomic density and thermal conductivity. Ferritic/martensitic stainless steels, perhaps with silicon and/or oxide-dispersion additions for enhanced coolant compatibility and improved high-temperature strength, might prove sufficient for low-to-moderate-temperature LFRs, but it appears that ceramics or refractory metal alloys will be necessary for higher-temperature LFR systems intended for production of hydrogen energy carriers.

Issn:16876075

Keywords:

Volume: 2007

Pages:

The development of scintillating materials is believed to reach a new step by controlling their preparation on a nanometric level. Sol-Gel chemistry offers very unique tools for nanoscale mastering of the materials preparation. In particular, shaping of the materials as thin films or nanoparticles offers new application in medical imaging. The control of doping ions dispersion thanks to soft chemistry is also a great advantage of such synthetic routes. In this paper, we will review recent work devoted to the sol-gel preparation of inorganic scintillating materials. We will focus on the new possibilities and advantages offered by sol-gel chemistry for the preparation of new scintillators and improvement of existing ones.

Issn:16874110

Keywords:

Volume: 2007

Pages:

We have performed 3D simulations of complex effective permittivity and permeability for random binary mixtures of cubic particles below the percolation threshold. We compare two topological classes that correspond to different spatial particle arrangements: cermet topology and aggregate topology. At a low filling factor of f=10%, where most particles are surrounded by matrix material, the respective effective material parameters are indistinguishable. At higher concentrations, a systematic difference emerges: cermet topology is characterized by lower effective permittivity and permeability values. A distinction between topological classes might thus be a useful concept for the analysis of real systems, especially in cases where no exact effective-medium model is available.

Issn:16874110

Keywords:

Volume: 2007

Pages:

Issn:16874110

Keywords:

Volume: 2006

Pages:

Issn:05435846

Keywords:

Volume: 46

Pages: 3-8

The paper deals with a study and comparison between welding with several wires in different shielding atmospheres and single-wire welding. The first part treats the equipment for multiple-wire electrode welding and a comparison between single-wire welding and twin-wire welding. The second part deals with the melting rate as a basis for determining the productivity of welding processes, and the third one with the energy efficiency as a criterion of cost-effectiveness of welding. Some results obtained regarding strength of submerged arc welded joints are shown.

Issn:05435846

Keywords: arc welding ; multiple-wire electrode ; energy efficiency ; toughness

Volume: 46

Pages: 47-52

In conditions of market economy the supply has to achieve new challenges because the quality and efficiency of functioning in this area influences in a large degree all fields of enterprise activity and its results. The supply issue and the cost reduction should be one of the basic elements of the enterprise strategy. In the article the purchase policy and supply aspects of logistics in strategic materials in the metallurgical enterprise are discussed.

Issn:05435846

Keywords: strategic materials supply ; purchasing policy ; steel plant ; forecasting

Volume: 46

Pages: 141-144

The production of Cu-Zr-Y-Mo Finely-Dispersed (FD) microlayer composite materials for electrical contacts by the method of electron-beam evaporation and layer-by-layer condensation from the vapor phase is described and the chemical composition, structure, density, electrical conductivity, hardness, and main mechanical characteristics of the materials in the temperature range from 290 to 1070 K are studied.

Issn:05435846

Keywords: microlayer composite material ; electric contacts ; characteristics ; high-temperature strength and hardness

Volume: 46

Pages: 93-96

Efficiency of resources use is, in a large extent, determined by the organization of production flow and the way of their control. The optimization of materials flow in the production process requires the identification of physical flows of goods and it cost. In the article the physical flow process of materials stream in the production process in one of Polish rolling mill and also its logistics analysis and cost analysis are presented.

Issn:05435846

Keywords: flow of materials ; rolling mil ; associated costs ; production process

Volume: 46

Pages: 295-299