Temperature distribution measurement in polymer composite pipes during their heat treatment with the use of microwave radiation
A method is proposed for constructing radial type microwave devices forming a uniform temperature distribution throughout the volume of pipes made of polymer composite materials The results of theoretical and experimental investigations of the temperature distribution across the thickness of the pipe material are given. The advantages of microwave technologies for curing polymer composite aterials compared to traditional methods are shown.
The experimental research results of the basalt cardboard thermal treatment with the microwave electromagnetic energy application are presented in the article. The weight change diagrams of the basalt cardboard samples during the drying process are given. Changes in the temperature behaviour are analyzed on the surface and inside the samples depending on coupling medium. An advice on the drying process parameters improvement is given.
Theoretical and experimental research results in the field of highperformance microwave technologies of sheet materials' with small dielectric losses thermal treatment are presented. To increase the electric field decay constant amplitude in the material with small dielectric losses sections of twodimensional periodic slowwave systems are used as heating elements. The microwave construction is based on a module, which consists of two identical in design and parameters microwave heating sections, positioned one above the other, and the electromagnetic field energy propagates along these sections in opposite directions. Processed material is positioned between two sections. Each heating section consists of the twodimensional periodic slowwave system, which on the one hand conditions with the microwave energy source, and on the other hand conditions with the water load, in which there is a sensor of passing power for the control of technological process. The long line with given boundary conditions was used as a model of microwave devices with the processed material. Special design of filters that impede microwave radiation from a working setup were used to reduce the level of a side radiation at the input and output of the processed material. Divergence of theoretical and experimental temperature distribution characteristics in the sheet material (ebonite) with small dielectric losses does not exceed 4%, and the temperature deviation in the material from the nominal temperature value does not exceed 7%. To materials with low dielectric losses in particular, relate: polystyrene, polypropylene and polyethylene with different fillings, for example, in the form of 10% carbon black or other dyes, plexiglass, ebonite and other plastics. Heat treatment of such materials by gas or by other known methods does not lead to the whole volume uniformity of heating due to the low plastics' heat conductivity and in subsequent operations, such as pressing or stamping, cracking or other unwanted defects arise.
The method of calculation of the temperature distribution in the dielectric material for the traveling wave microwave devices is presented. The basic equations for the temperature distribution in the direction of the electromagnetic field energy propagation with considering the dependence of the dielectric parameters of a material on the temperature changes and taking into account the heat transfer to the environment for the arbitrary design of the electrodynamic system are obtained. The results of calculation and measurements of the temperature distribution of the material in the direction of the traveling wave propagationat the electromagnetic field frequency oscillations of 2450 MHz are given. The discrepancy of calculated and measured characteristics of the temperature distribution in the material does not exceed 10%.
The computational model of the temperature sensors integrated on the IC chip with power transistors is developed. The 2D/3D problem of sensor placement is mathematically described by the classic heat transfer equation coupled with the equation for current density distribution. It is shown that parasitic effects of sensor current displacement and thermo-emf generation resulting from a temperature gradients (Seebeck effect) must be taken into account. For this purpose the special differential equation is introduced. The examples of point- and strip-like temperature sensors modeling for power BJTs and ICs are demonstrated.
Questions of the even temperature distribution creation in the volumetric materials with different dielectric losses placed in the beam-type microwave device are examined. The volumetric material was irradiated by two types of antennas which provided perpendicular and parallel flux direction of the electric-field vector relatively to the material's surface. Experimental data on the temperature field distribution in the volume of material is presented. It is shown that the total temperature dispersion is less than 5ºC inside the material heated up to 80ºC.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.