Internal R&D
From time to time, it has been possible for P O Risman to pursue projects of personal interest to himself. Some of these studies are of a basic nature and have no immediate industrial use, while others (mainly on mode theory, diffraction, and surface waves) form a basis for competitive consulting and inventions.
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During 2008, four chapters were authored for a forthcoming book to be published in 2009 by Woodhead Publishing Ltd: Development of packaging and products for use in microwave ovens. edited by M.W Lorence and P.S.Pesheck. The chapters deal with dielectric measuremenst methods, dielectric data including mixture formulas, mocdelling of susceptors and ameliorators – and advanced topics on heating unevenness. In that chapter, two cavity-bound and twelve (!) load-dependent factors are described. One of these is the very interesting burnt stripe effect..
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In 2005 and 2006 interest was focussed on new systems for accurate dielectric measurements. The dual-frequency measurement applicator (shown to the right on the main page) is commercially available and includes instruction sheets for various purposes. Algorithms for calculations of permittivities and permeabilities in certain property ranges are also available. An example of instruction sheet is given here (290kB).
The project on improved data for pure liquid water was concluded in 2006. Data from –15 °C to +40 °C were presented at the 6th ISEMA conference in Weimar May-June 2005 (see MFPA) and were later extended to +90 °C Results were presented at the IMPI symposium in Boston in August, and a full paper was published in the April, 2007 issue of the IOP journal. Algorithms are given in the section Technical References. Selections of suitable reference liquids were also made, and three of them were measured with high precision. Data are given in the same section.
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In 2003, a presentation dealing with the disparate "states-of-the-art" in cavity/applicator mode theory was given at the AMPERE conference. There were some typographical errors; these are now corrected and figures in colour are introduced in the version that can be downloaded here (PDF, 300 dpi; 5 MB) or from here (TIF in 7z compression, 400 dpi; 3 MB – there are also a 7z software installation exe file and a practical 7z icon; the 7z website is here) .
At the same conference, a poster with a description of some of the complex cavity theory and practically relevant examples was also given and is available here (1,2 MB); it is an excerpt from an unpublished text by P O Risman.
In 1999, some
important aspects of microwave oven cavity modes
and on the concept of microwave penetration
depths in presentations by P O Risman at an IMPI
course. They have
astonishingly not yet been brought up in the technical or
scientific literature in the subject area. Click
on the bolded text
above to download a copy.
Many papers authored by P O Risman have been published in the Journal of Microwave Power (and Electromagnetic Energy). There is currently a major effort by he journal to provide internet access to all published journal issues since 1966. P O Risman participates in this. He has for example recently scanned and provided all the 1966–67 issues, and several others. See the JMPEE website! If any particular article by P O Risman is not found, please send an email message.
Information on patents: Click on Patents.