| 1. |
- Antonini, Giulio, et al.
(author)
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A comparative study of PEEC circuit elements computation
- 2003
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In: IEEE International Symposium on Electromagnetic Compatibility. - Piscataway, NJ : IEEE Communications Society. - 0780377796 ; , s. 810-813
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Conference paper (peer-reviewed)abstract
- A key use of the PEEC method is the solution of combined electromagnetic and circuit problems as they occur in many situations in todays very large scale integrated circuits (VLSI) and systems. An important aspect of this approach is the fast and accurate computation of PEEC circuit matrix elements, the partial inductances and normalized coefficients of potential. Recently, fast multipole methods (FMM) have been applied to the PEEC method in the frequency domain as a way to speed up the solution. In this paper, we consider the fast evaluation of the PEEC circuit matrix elements by two different methods, a matrix version of the (FMM) PEEC method and a method, which we call the fast multi-function (FMF) PEEC approach. In this technique, the matrix coefficients are evaluated using analytical functions approximation of the coefficients in combination with a proper choice of numerical quadrature formulas.
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| 3. |
- Bergquist, Jonas, et al.
(author)
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Future aspects of psychoneuroimmunology - lymphocyte peptides reflecting psychiatric disorders studied by mass spectrometry
- 2001
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In: Archives of Physiology and Biochemistry. - 1381-3455 .- 1744-4160. ; 109:4, s. 369-371
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Journal article (peer-reviewed)abstract
- We have investigated whether cytoplasmatic and nuclear extracts of human peripheral blood lymphocytes contain arginine vasopressin (AVP), of importance for memory functions, in samples from healthy controls and patients diagnosed as depressed. It is the first time as AVP, AVP-fragments and chemically modified AVP-forms have been demonstrated in lymphocyte/nuclear extracts. This was performed by an HPLC-purification step, followed by a second immunoprecipitation step before identification by mass spectrometry. We are developing new methods using a combination of high-resolution mass spectrometry and separation techniques such as capillary electrophoresis and nano liquid chromatography. We have named this methodological approach when studying endogenous peptides -Peptidomics.
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| 4. |
- Ekman, Jonas, et al.
(author)
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3D PEEC capacitance calculations
- 2003
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In: 2003 IEEE International Symposium on Electromagnetic Compatibility. - Piscataway, NJ : IEEE Communications Society. - 0780378350 ; , s. 630-635
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Conference paper (peer-reviewed)abstract
- The partial element equivalent circuit (PEEC) method has shown to be useful in mixed circuit and electromagnetic analysis. In PEECs, the extensions from two to three dimensional modeling are mainly in the calculation of the partial self and mutual capacitive couplings. The considerable increase in problem size for 3D PEEC models results in a larger number of partial elements that has to be calculated. This results in excessive calculation times if the capacitive calculation routines are poorly constructed. In this paper it is shown that by using local reduction matrices for the capacitive calculations, the calculation time for PEEC model capacitance matrices can be decreased while keeping the accuracy.
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| 5. |
- Ekman, Jonas
(author)
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Aktivitet: Svenska Nationalkommittén för Radiovetenskap (SNRV) - Sektion E
- 2004
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Other publication (pop. science, debate, etc.)abstract
- Huvudman för Svenska Nationalkommittén för radiovetenskap (SNRV) är Kungliga Vetenskapsakademien, KVA. SNRV bildades som en nationalkommitté inom KVA genom ett Kungligt brev år 1931. De av akademien fastställda stadgarna anger att SNRV är en expertkommitté under Kungliga Vetenskapsakademiens huvudmannaskap med uppgift att:- främja forskning och utbildning inom det radiovetenskapliga området och att därvid representera Sverige i den internationella radiovetenskapliga unionen, Union Radio-Scientifique Internationale (URSI).- stödja planmässigt samarbete med besläktade vetenskapsgrenar.- stå till förfogande som rådgivande organ åt universiteten och andra delar av utbildningssystemet.- verka som expertorgan åt Vetenskapsakademien.
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| 6. |
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| 7. |
- Ekman, Jonas
(author)
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Electromagnetic modeling using the partial element equivalent circuit method
- 2003
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Doctoral thesis (other academic/artistic)abstract
- This thesis presents contributions within the field of numerical simulations of electromagnetic properties using the Partial Element Equivalent Circuit (PEEC) method. Numerical simulations of electromagnetic properties are of high industrial interest. The two major fields of use are to ensure compliance with electromagnetic compatibility (EMC) regulations and to verify functionality in electronic designs. International EMC regulations bounds companies that develop or assemble electric products to market products that are electromagnetic compatible with other products in their environment. Failure to comply with regulations can result in products withdrawal and fines. To avoid incompatibility, numerical simulations can be used to improve EMC characteristics in the development and assembly stage in a cost efficient way. Functionality of today's compact high-performance electronic systems can be affected by unwanted internal electromagnetic effects. The result can be degradation of performance, malfunction, and product damage. Numerical simulations are used to predict electromagnetic effects at the design phase, thus minimizing the need for post-production actions delaying product releases and increasing product cost. At the Embedded Internet System Laboratory (EISLAB), Luleå University of Technology, a project concerning numerical simulations of electromagnetic properties in electric systems using the PEEC method is in progress. This thesis focuses on the development of the PEEC method for practical use, thus demanding optimal performance of the basic sections within a PEEC based electromagnetic solver in terms of speed and accuracy. In the PEEC method, the two most demanding sections are the partial element calculations and the solution of the final equation system. The latter problem is a pure mathematical problem with continuous progress while the partial coefficient calculations require further research. This thesis proposes several techniques for efficient partial element calculations. First, a discretization strategy is used for one-layer structures to enable the use of fast analytic formulas and the resulting simplified PEEC models are solved using a freeware version of SPICE, exemplifying the accessibility of the PEEC method. Second, a fast multi- function method is proposed in which different order of numerical integration is used, in the calculation of the partial elements, depending on a predefined coupling factor. Third, the fast multi-function method is further developed and compared to a fast multipole method applied to partial element calculations. Fourth, the calculation of the three- dimensional node coefficients of potential is addressed and three novel approaches are presented and evaluated in terms of speed and accuracy. The thesis includes a paper dealing with nonorthogonal PEEC models. This model extension allows the use of nonorthogonal volume and surface cells in the discretization of objects. This facilitates the modeling of realistic complex structures, improves accuracy by reducing the use of staircase- approximations, and reduces the number of cells in the PEEC model discretizations. The nonorthogonal formulation excludes the use of analytical formulas thus make topical the use of fast multi-function- and multipole-methods. The fundamentals of the PEEC method makes free-space radiation analysis computationally efficient. Radiated field characterization is important in EMC processes and therefore of great interest. One paper in this thesis explore different possibilities to use PEEC model simulations to determine the electric field emissions from objects.
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| 8. |
- Ekman, Jonas, et al.
(author)
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Electromagnetic shielding capabilities of conductive thermoplastic materials and three measurement methods for evaluation
- 2002
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Reports (other academic/artistic)abstract
- This report summarizes the work to compare 12 conductive thermoplastics using three measurement methods. The 12 thermoplastic materials were chosen to observe the influence of variation of base polymer, variation of additives, different mechanical properties and processing and mouldability properties. Test samples were manufactured to be useful in fixtures for far field insertion loss measurements, and to load a coaxial transmission line. Boxes were made to make an enclosure for an electric field source, this arrangement was used for simple application-like near field insertion loss measurements. With all three methods data was obtained in the frequency range from 100 MHz to 1000 MHz for- far field shielding effectiveness- near field shielding effectiveness- complex permeability- complex permittivityResults were obtained showing that variations in the manufacturing process where extra heated thermoplastics or yeast additive was tested, did not improve the shielding efficiency for the particular compounds that was used. The mesurements indicates that a higher amount of additive improves both the near field SE and the far field SE. Measured far field SE is in good agreement with the numerical simulations based on the measured material data.
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| 9. |
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| 10. |
- Ekman, Jonas
(author)
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Experimental verification of PEEC based electric field simulations
- 2001
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In: 2001 IEEE EMC International Symposium. - Piscataway, NJ : IEEE Communications Society. - 0780365690 ; , s. 351-355
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Conference paper (peer-reviewed)abstract
- Different ways to simulate the measured radiated electric field for printed circuit boards using partial element equivalent circuit (PEEC) models has been investigated. Full and simplified PEEC models have been used with post-processing algorithms and an electric field sensor directly incorporated in the PEEC simulations. Calculated and simulated field strengths for a simple PCB are compared to measurements taken in an anechoic EMC chamber. It is shown that the post-processing equations compare better to measurements then the electric field sensor
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