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1
Naftali, Verena Kashikuka. "Implementation of a reverberation chamber for electro-magnetic compatibility measurements". Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2566.
Testo completoAbstract (sommario):
Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2017.This research project focuses on the implementation of a Reverberation Chamber (RC) by the transformation of an existing electromagnetically shielded room. The reverberation chamber is a kind of shielded room designed to create a statistically random internal electromagnetic environment. The reverberating environment makes it possible to obtain high field strengths from a relatively low input power. The electric fields in the chamber have to be stirred to achieve a statistically uniform field. The first part of this thesis presents an overview of reverberation chamber principles and preliminary calculations are done: the lowest usable frequency is estimated to be close to 300 MHz from empirical criteria. Modelling of the statistical environment is then presented, where electromagnetic quantities are characterised by probability density functions (Gaussian, Rayleigh and exponential); correlation issues are also presented. Measurements are performed in the frequency range of 800 MHz – 4 GHz, dictated by the antennas available for this research study. An investigation of cable losses is conducted, followed by a discussion on measurement accuracy. Mechanical stirrers are designed and manufactured. Electromechanical components are selected based on the literature study. Measurements are obtained through an automated setup using MATLAB®. To verify that the RC, with its in-house designed mechanical stirrers, is well-operated, the stirring ratio is experimentally determined. After this first test, an exhaustive investigation of probability density functions is conducted, taking into account correlation issues. Measurements show that the quality factor of the chamber is close to 2000 at 3 GHz, and that 60 independent stirrer positions at 4 GHz can be used for statistical analyses. Finally, the uniformity test is performed with an improved accuracy using frequency stirring. In conclusion, the CPUT RC passes the validation procedure according to the IEC 61000-4-21 standard by generating the required field uniformity within the accepted uncertainty level.
2
Johnstone, Sherri. "Electromagnetic measurements of steel phase transformations". Thesis, Durham University, 2002. http://etheses.dur.ac.uk/3982/.
Testo completoAbstract (sommario):
This thesis describes the development of electromagnetic sensors to measure the phase transformation in steel as it cools from the hot austenite phase to colder ferritic based phases. The work initially involved investigating a variety of sensing configurations including ac excited coils, C-core arrangements and the adaptation of commercial eddy current proximity sensors. Finally, two prototype designs were built and tested on a hot strip mill. The first of these, the T-meter was based on a C-shaped permanent magnet with a Gaussmeter measuring the magnetic field at the pole ends. Laboratory tests indicated that it could reliably detect the onset of transformation. However, the sensor was sensitive to both the steel properties and the position of the steel. To overcome this, an eddy current sensor was incorporated into the final measurement head. The instrument gave results which were consistent with material property variations, provided the lift off variations were below 3Hz. The results indicated that for a grade 1916 carbon- manganese steel, the signal variation was reduced from 37% to 2%, and the resulting output was related to the steel property variations. The second of these prototypes was based on a dc electromagnetic E-core, with Hall probes in each of the three poles. 'Cold' calibration tests were used to decouple the steel and the lift-off. The results indicated that there was an error of 3-4% ferrite/mm at high ferrite fractions. At lower fractions the error was higher due to the instrument’s insensitivity to lift-off. The resulting output again showed a relationship with varying steel strip properties. ft was also shown that a finite element model could be calibrated to experimental results for a simple C-core geometry such that the output was sensitive to 0.2% of the range. This is required to simulate the sensor to resolve to 10% ferrite.
3
Freeman, Larry. "PREDICTION AND MEASUREMENT OF RADIATED EMISSIONS BASED ON EMPIRICAL TIME DOMAIN CONDUCTED MEASUREMENTS". Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4232.
Testo completoAbstract (sommario):
This thesis develops a novel method to predict radiated emissions measurements. The techniques used are based on standard Electromagnetic Compatibility (EMC) qualification test methods. The empirical data used to formulate the final results was restricted to pertinent data protocol waveforms however the entire method may be applied to any waveforms for which empirical radiated emissions have been measured. The method provides a concise means for predicting worst case radiated emissions profiles based on empirical measured data.M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
4
Azpúrua, Marco A. "Full time-domain electromagnetic interference measurements and applications". Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/587194.
Testo completoAbstract (sommario):
This thesis presents a technology that has been called the Full Time-Domain Electromagnetic Interference measurement systems and its applications. Full TDEMI measurement systems are an implementation of an FFT-based receiver that enables the usage of oscilloscopes for EMI measurements. They follow the virtual instrumentation approach for transforming oscilloscopes into a compliant CISPR 16-1-1 receiver.
Full TDEMI measurement systems have been assessed for characterizing their performance using waveform oriented calibration procedures that bridge the gap between direct measurements in the time domain and the processed frequency domain magnitudes. As a result, the conformity of Full TDEMI receivers is attested with respect to the requirements defined in the standards.
Full TDEMI systems have advantages over the conventional swept receivers for performing challenging measurements typical of EMI assessments. Time-domain captures enable full spectrum measurements that allow analyzing transient phenomena. The number of channels available in most oscilloscopes enable synchronous measurements that allow recording the EMI using a combination of transducers. Some of the applications of the multichannel EMI measurements are the single stage evaluation of the conducted EMI of all the EUT mains lines, the instantaneous measurement of the common-mode and the differential mode voltage noise, the concurrent conducted and radiated EMI measurements, and the parallelization of multi-antenna radiated emissions testing.
Such alternative test methods, have improved the EMC testing process in a variety of industries by reducing the time and the efforts required for performing a complete EMI evaluation due to the following reasons. First, Full TDEMI measurements deliver faster results because the interferences' spectrum is simultaneously estimated for all the weighting detectors. Second, the number of measurement iterations is reduced because of the multichannel possibilities and also because of an agile identification of the worst case emissions. Thirdly, Full TDEMI measurement system are a cost-effective alternative to the real-time spectrum analysers.
Full TDEMI measurement systems have extended the state-of-the-art with the expected maximum detector and the empirical interference decomposition. The expected maximum detector is a statistical measure of the most probable level of the peak emissions that is based on a time-frequency modelling of the measured EMI using the extreme value theory. Using the variability information of the EMI level at each frequency bin, the expected maximum detector estimates the equivalent max hold value of a random EMI. The expected maximum detector also provides a model for quantifying the uncertainty of peak detector measurement of stochastic EMI.
The Empirical Interference Decomposition is a modified implementation of the Hilbert-Huang transform with time-gating capabilities that allow a heuristic determination of characteristic oscillatory patterns without neither domain transformation nor a predefined set of basis function. The EID has been used successfully for ambient noise cancellation purposes during outdoor EMI measurements, obtaining more than 20 dB of attenuation of the usual broadcasting signals. The fundamentals of the ANC by means of EID is the identification, in the time and in the frequency domain, of intrinsic modes of emissions that area attributable to the EUT while subtracting the residual modes from the measurement results.
Applications of the Full TDEMI measurement systems have been published in recognized conferences and journal.
From the reasons mentioned before, the Full TDEMI measurement technology has advantages for EMI testing, analyzing and troubleshooting. It provides a complementary approach to the typical measurements entirely focused in the frequency domain and it exhibits a level of maturity that could allow it to be standardized in forthcoming years.Esta Tesis comprende un compendio de contribuciones hechas por el autor al campo de la tecnología de medición de radiofrecuencia para la compatibilidad electromagnética. En particular, esta Tesis presenta una tecnología de sistemas medición de interferencias electromagnéticas completamente basado en dominio del tiempo (Full TDEMI) y algunas de sus aplicaciones más relevantes. Los sistemas de medición Full TDEMI son una implementación de un receptor de medida basado en FFT que permite el uso de osciloscopios para mediciones de interferencias electromagnéticas. Los sistemas de medición Full TDEMI siguen el enfoque de instrumentación virtual para transformar los osciloscopios de propósito general en un receptor de medida completamente funcional y conforme con la norma CISPR 16-1-1. Por un lado, esto es factible debido a las técnicas específicas de procesamiento de señales aplicadas sobre las adquisiciones en el dominio del tiempo utilizando una capa de software dedicada. Por otro lado, los sistemas de medida Full TDEMI se han evaluado exhaustivamente para caracterizar su rendimiento utilizando procedimientos novedosos de calibración orientados a formas de onda que acortan la brecha entre las magnitudes medidas en el dominio del tiempo y las aquellas procesadas en el dominio de frecuencia. Como resultado, se certifica la conformidad de los sistemas completos de medición TDEMI con respecto a los requisitos definidos en los estándares internacionales paramediciones EMI. Además, se ha demostrado que los sistemas de medición Full TDEMI ofrecen ventajas en comparación con los receptores de barrido convencionales para realizar varias medidas desafiantes típicas de las evaluaciones de emisiones electromagnéticas. Por ejemplo, las capturas de dominio de tiempo posibilitan mediciones de espectro completo que permiten un análisis adecuado de fenómenos transitorios. Del mismo modo, la cantidad de canales disponibles en la mayoría de los osciloscopios hace viables múltiples mediciones síncronas que para registrar las perturbaciones interferentes mediante una combinación de transductores. Algunas de las aplicaciones de la medición EMI multicanal son la evaluación de etapa única de la EMI conducida de todas las líneas de alimentación de los equipos bajo prueba (EUT), la medición instantánea del voltaje del ruido en modo común y en modo diferencial, las mediciones concurrentes de la EMI conducida y radiada y la paralelización de los ensayos de emisiones radiadas con múltiples antenas. Tales métodos de prueba alternativos, han mejorado significativamente el proceso de prueba de EMC en una variedad de industrias al reducir la cantidad de tiempo y los esfuerzos necesarios para realizar una evaluación completa del sistema principalmente debido a las siguientes razones. En primer lugar, las mediciones de EMI en el dominio del tiempo arrojan resultados más rápidos porque el espectro de interferencias se estima simultáneamente para todos los detectores de ponderación estándar necesarios para determinar el cumplimiento de los límites máximos de emisiones definidos en las respectivas normas de producto. En segundo lugar, el número de iteraciones de medición se reduce debido a las posibilidades multicanal y también debido a una identificación ágil del peor caso de las emisiones de un EUT que tiene diferentes modos de funcionamiento. En tercer lugar, el sistema Full TDEMI es una alternativa económica y versátil a los analizadores de espectro en tiempo real más avanzados en lo concerniente a mediciones EMI en el rango de pocos gigahertzios. Desde el punto de vista teórico, los sistemas de medición Full TDEMI han extendido el estado del arte, como en el caso de un par de contribuciones denominadas el detector de máximo esperado y la descomposición empírica de interferencias. El detector de máximo esperado es una medida estadística del nivel más probable de las emisiones pico que se basa en un modelado tiempo-frecuencia de las interferencias medidas utilizando la teoría del valor extremo. Usando la información de variabilidad del nivel de interferencia en cada componente de frecuencia, el detector de máximo esperado se puede usar para estimar el valor de retención máximo (max-hold) equivalente de una interferencia aleatoria. El detector demáximo esperado también proporciona un modelo que cuantifica la incertidumbre de lamedición del detector de picos ante interferencias estocásticas. La descomposición de interferencia empírica (EID) es una implementación modificada de la transformada de Hilbert-Huang con capacidades de sincronización de tiempo que permiten una determinación heurística de patrones oscilatorios característicos sin requerir transformación de dominio ni un conjunto predefinido de funciones base. La descomposición de la interferencia empírica se ha utilizado con éxito para la cancelación del ruido ambiental durante prueba de concepto de mediciones de EMI de al aire libre, obteniendo más de 20 dB de atenuación de las señales habituales de radiodifusión. El fundamento de la cancelación del ruido ambiental mediante EID es la identificación, en el tiempo y en el dominio de la frecuencia, de los modos de emisión intrínsecos que son atribuibles al EUT al restar los modos residuales (ruido ambiental) de los resultados de medición. Las contribuciones mencionadas se distribuyen en cuatro artículos de revista. Los resultados de medición complementarios y las aplicaciones de los sistemas de medición Full TDEMI también se han publicado en conferencias notables en el área. Por los motivos antes mencionados, la tecnología Full TDEMI tiene ventajas significativas para los ensayos, el análisis y la resolución de problemas de EMI. Asimismo, proporciona un enfoque complementario a las mediciones típicas completamente enfocadas en el dominio de la frecuencia y exhibe un nivel de madurez que podría permitir su estandarización en los próximos años.
5
Mansoor, Hadi. "Microfabricated electromagnetic actuators for confocal measurements and imaging". Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44146.
Testo completoAbstract (sommario):
Various optical microscopy techniques have been developed for micrometer level imaging of biological tissue samples. Among those techniques, confocal imaging provides superior image contrast and high resolution with a modest system cost. Confocal microscopy allows vertical optical sectioning (imaging a section perpendicular to the surface of tissue) or horizontal optical sectioning (imaging a section parallel to the surface of tissue) and provides high-resolution tissue morphology that is analogous to conventional histopathology images. This has brought up a tremendous potential for guiding surgical biopsies and in vivo non-invasive diagnosis of diseases such as cancer. The challenge in moving microscopic imaging modalities into clinical applications is miniaturization into a form of hand-held devices or catheters for endoscopic applications.
In this thesis, micro-fabrication techniques such as Microelectromechanical Systems (MEMS) fabrication process and laser micromachining have been employed to develop magnetic actuators. The actuators are then used to move lenses and optical fibers in order to scan a laser beam across a sample. Lens and fiber actuators are integrated in catheter and hand-held devices for confocal thickness measurement and optical sectioning imaging of biological samples.
Thickness measurement is performed by scanning the focal point of a microlens across the thickness of thin films or layered biological tissues and collecting the intensity signal of the single scattering light reflected back from the samples as a function of lens position. A catheter was developed and thickness measurements of polymer layers and biological tissues were demonstrated. The device has optical resolution of 32 µm with expanded uncertainty of measurement of 11.86 µm.
Lens and fiber optic actuators have been coupled to form two-dimensional imaging devices. Direct and real-time vertical and horizontal cross-sectional imaging of biological samples has been demonstrated. Vertical imaging is performed by transverse (X-axis) and axial (Z-axis) scanning of a focused laser beam using an optical fiber and a microlens actuator respectively. Horizontal imaging is done by a 2-axis fiber optic scanner. All the developed actuators are driven by electromagnetic forces and require low driving voltages. Confocal imaging of biological samples, with lateral resolution of 1.55 µm, has been demonstrated.
6
McAughey, Kevin L. "High precision measurements for NDE using electromagnetic sensors". Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/72801/.
Testo completo
7
Kim, Jerry. "Through-the-wall imaging from electromagnetic scattered field measurements". Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion.exe/07Mar%5FKim%5FJerry.pdf.
Testo completoAbstract (sommario):
Thesis (M.S. in Physics)--Naval Postgraduate School, March 2007.Thesis Advisor(s): Brett Borden, Gamani Karunasiri. "March 2007." Includes bibliographical references (p. 97-99). Also available in print.
8
Karlsson, Roger. "Theory and Applications of Tri-Axial Electromagnetic Field Measurements". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5916.
Testo completo
9
Bukowski, Edward F., T. Gordon Brown, Tim Brosseau e Fred J. Brandon. "In-Bore Acceleration Measurements of an Electromagnetic Gun Launcher". International Foundation for Telemetering, 2008. http://hdl.handle.net/10150/606161.
Testo completoAbstract (sommario):
ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, CaliforniaThe US Army Research Laboratory has been involved in the design and implementation of electromagnetic gun technology for the past several years. One of the primary factors of this research is an accurate assessment of in-bore structural loads on the launch projectiles. This assessment is essential for the design of mass-efficient launch packages for electromagnetic guns. If not properly accounted for, projectile failure can result. In order to better understand the magnitude of the in-bore loads, a data-recorder was integrated with an armature and on-board payload that included tri-directional accelerometers and magnetic field sensors. Several packages were launched from an electromagnetic railgun located at Aberdeen Proving Ground, MD. Substantial effort was placed on soft-catching the rounds in order to facilitate data recovery. Analysis of the recovered data provided acceleration and magnetic field data acquired during the launch event.
10
Dorai, Sriram. "Electromagnetic modelling of UTP cables for non-contact measurements". Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.706081.
Testo completo
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Thunehed, Hans. "Two topics related to interpretation of transient electromagnetic measurements". Licentiate thesis, Luleå tekniska universitet, 1997. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26657.
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Kasturi, Vijay. "The influence of printed circuit board design on TEM cell measurements". Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.mst.edu/thesis/pdf/Kasturi_09007dcc8048d628.pdf.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of Missouri--Rolla, 2007.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed March 24, 2008) Includes bibliographical references (p. 105-106).
13
Côté, Alain C. "Density fluctuation measurements with laser scattering". Thesis, University of Oxford, 1989. http://ora.ox.ac.uk/objects/uuid:2580d8c1-32f7-40c6-afe1-14ebde9641f3.
Testo completoAbstract (sommario):
-2 power law. The average phase velocities are around 4.5 km/sec and are slightly larger than the electron diamagnetic drift velocity. The waves are tentatively identified with the electron drift mode. Coherent signals due to long wavelength MHD modes are detected. Results from a Langmuir probe corroborate most of these data.
14
Al-Mahdawi, Tareef Ibrahim. "Electromagnetic radiator characterization and modeling through planar near-field measurements". Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70327.
Testo completoAbstract (sommario):
This thesis deals with the use of planar near-field measurements for characterizing and modeling general electromagnetic radiators, particularly non-directive ones.Relationships between the measured field on a plane and the equivalent currents on the radiator plane were established. These were used to determine the resolution with which these currents can be mapped. The equivalent currents then serve as a model from which the radiator external field can be calculated. It was shown that significant filtering of measurement errors results from the utilization of such a model. The consequent reduction in errors was estimated.
The behavior of the measurement probe was studied in depth. The two general probe types, wire and aperture, were analyzed, and field extraction formulation and procedure were established.
The techniques developed were applied to the experimental study of three different radiators leading to new information about their behavior. Results show close agreement between the calculated field values from the model and those measured directly.
15
Theodoridis, John Apostolis 1972. "Borehole electromagnetic prospecting for weak conductors". Monash University, School of Geosciences, 2004. http://arrow.monash.edu.au/hdl/1959.1/5225.
Testo completo
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Klein, Katherine. "Electromagnetic properties of high specific surface minerals". Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/20699.
Testo completo
17
Shemuly, Dana. "Design and measurements of novel electromagnetic properties in spiral transmission fibers". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76118.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 92-96).
One dimensional photonic band gap fibers have proven to be fascinating and versatile devices, as demonstrated by many applications. The ability to control and design these fibers to achieve specific functionalities will enable us to advance the research done with these fibers and to gain new applications. In this work we explore our ability to control different fabrication parameters to design a fiber according to certain requirements. We use these capabilities to design and fabricate a near IR fiber for high peak power laser transmission. Since a multimode fiber supports many modes one can gain further control over fiber properties by controlling modal content in the fiber. We developed two techniques for controlled coupling and demonstrated them using one dimensional photonic band gap fibers. Using a spatial light modulator, one can dynamically control the modal content in the fiber, including superposition of more than one mode. We experimentally demonstrate this capability by coupling to one of two modes and superposition of the two. Using a static technique, we experimentally demonstrate a single-mode transmission of the azimuthally polarized mode (TEoi) in a highly multimode cylindrical photonic band gap fiber. Theoretical calculations verify the validity of this technique and accurately predict the coupling efficiency. Single-mode propagation in a large hollow core fiber can enable numerous applications, especially in control of particles along the entire length of the fiber. Finally, we examined the effects of the spiral cross-section of the fiber on its optical properties. The fiber's chiral symmetry combined with its infinite translational symmetry creates a truly planar chiral structure, similar to many artificial chiral structures recently studied. The low-symmetry geometry of the fiber, which lacks any rotational and mirror symmetries, exclusively supports modes with angular momentum greater than zero and shows in-principle directional optical activity and asymmetric propagation. We use general symmetry arguments to provide qualitative analysis of the waveguide's modes and numerically corroborate this using finite element simulation. We also demonstrated these properties experimentally using spiral fibers.
by Dana Shemuly.
Ph.D.
18
Niska, Stefan. "Measurements and analysis of electromagnetic interferences in the Swedish railway systems /". Luleå : Division of Operation and Maintenance Luleå Railway Research Center, Luleå University of Technology, 2008. http://epubl.ltu.se/1402-1544/2008/76/.
Testo completo
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Khan, Zulfiqar A. "EMI/EMC analysis of electronic systems subject to near zone illuminations". Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1196207323.
Testo completo
20
Mogren, Simon. "Electromagnetic Shielding of Fine Wires for Electrophysiological Sensing". Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291457.
Testo completoAbstract (sommario):
Tests have been performed to determine whether electromagnetic shielding of fine wires for electrophysiological sensing is a possible way to reduce the external noise in recording of nervous signals. By shielding the wires with a layer of silver, forming a coaxial cable, a reduction of the received power on the lead of 11.8-33 dBm was shown over the 10 – 10 000 Hz range when the test wire was subject to an electromagnetic field from an injection cable. When putting the performance on the interval 50-100 Hz aside the same performance was measured to 25-33 dBm lower received power, which can be explained by 50 Hz noise from the electrical grid interfering with the measurements. However, when the shield was not grounded or grounded through a resistor worse performance was shown. The difference in received power between the unshielded and shielded configuration without grounding the shield was close to 0 dBm. Following this, the type of shielding investigated in this project has the potential to substantially shield thin wires from external interference under the condition that sufficient grounding is provided.
21
Chen, Ming. "Electromagnetic radiation calorimetry of thermoplastics, elastomers and composites systems". Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54780.
Testo completoAbstract (sommario):
The application of microwave radiation for processing of glassy and semicrystalline thermoplastics, elastomeric polymers and composites was investigated. The goal of this research was to reveal the relationship between polymer structure and microwave absorptivity, and hence processability. The specimens were subjected to an electric field at 2.45 GHz either inside a rectangular waveguide or in a cylindrical resonant cavity applicator with less than 100 watts applied power. Both travelling wave modes and standing wave modes were examined. Temperatures, powers and times were recorded, leading to the concept of "microwave calorimetry." Low frequency dynamic mechanical and dielectric frequency-temperature spectra were obtained on the materials and combined to conveniently extrapolate structure-property relationships into the GHz region. A correlation was found between the dielectric properties of various polymers and the dipole moments of small molecule analogues. Evaluating heatability was most accurately found to be determined by the magnitude of (εS - ε∞), the oscillator strength. The value of (εS - ε∞) should be used together with the distribution of relaxation times and the activation energies of dipolar dispersion to predict heatability for microwave processing. The critical temperatures, TC, of dielectric loss were obtained from the intercepts of positive slope tangents of heating rate versus temperature plots at 2.45 GHz for polymers. Microwave processing was rapid above the critical temperature where the maximum dielectric loss fell in the 2.45 GHz frequency domain for efficient coupling of energy to the polymers. Shifting the dielectric relaxation spectrum into the microwave region by directly or indirectly increasing the temperature of each sample was unique and of key importance to processability. A schematic model was proposed to explain the behavior of two-phase materials subjected to microwave heating. Combining the heatability, (εS - ε∞), and the dielectric relaxation spectral response was found to be helpful in evaluating formulations of two-phase materials for electromagnetic radiation processing at high frequencies.Ph. D.
22
Habermehl, Florian [Verfasser], e G. [Akademischer Betreuer] Drexling. "Electromagnetic Measurements with the KATRIN Pre-Spectrometer / Florian Habermehl. Betreuer: G. Drexling". Karlsruhe : KIT-Bibliothek, 2009. http://d-nb.info/1014223032/34.
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Waugh, Anthony. "A parameterised fast simulation of electromagnetic cascades across a non-uniform geometry". Thesis, The University of Sydney, 2009. https://hdl.handle.net/2123/28235.
Testo completoAbstract (sommario):
In late 2009, the Large Hadron Collider (LHC) will begin operation at the European Organisation
for Nuclear Research (CERN). At this time, the ATLAS experiment will begin collecting
data from LHC collisions. The experiment aims to discover new physics at an energy scale as
yet unexplored by experiments of this kind. In order to fully understand the processes occurring,
experiments such as ATLAS employ a detailed Monte Carlo simulation, which models all of the
detector components at the microscopic level. Despite access to a global network of computing
resources, the ATLAS Monte Carlo simulation is statistically limited, due to the time required to
simulate the large number of events needed to fully model the detector response. The complexity
of the ATLAS detector geometry makes many of the faster simulation models, which have been
used on previous experiments, unsuitable.
In response to this limitation, the Fast G4 Simulation package was developed, applying fast
simulation techniques only to the time limiting process of electromagnetic cascades. It is based
upon an existing parameterisation model, which was found to be inadequate due to excessive
preshowering of electrons. This model was extensively tested, and extended to incorporate the
full energy range of incident particles; scaling the amount of detail applied to the simulation, with
respect to energy. The shower parameterisation component of the model was then extended to
incorporate the dead material directly in front of the calorimeters, which causes the preshowering.
Fast G4 Simulation was implemented into the ATLAS Monte Carlo software and compared to
full simulation for single electrons at the level of simulation hits and at the level of analysis objects
with good agreement observed for the energy resolution and shower shape parameters. A small
sample of Z —> 66 events was simulated and a comparison of the invariant mass distribution for full
and fast simulation was made. Again good agreement was observed. On average, a factor of 3 — 4
improvement was observed in CPU time required for simulation. No appreciable difference was
observed between the reconstructed Z boson invariant mass distributions of fast and full simulated
events.
While the model was implemented specifically for the ATLAS experiment, it is applicable to
any electromagnetic calorimeter and particularly useful for those with a non continuous geometry.
24
Eason, Kwaku. "Numerical investigation of micro-macro coupling in magneto-impedance sensors for weak field measurements". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26589.
Testo completoAbstract (sommario):
Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Lee, Kok-Meng; Committee Member: Allen, Mark; Committee Member: Hesketh, Peter; Committee Member: May, Gary; Committee Member: Sitaraman, Suresh. Part of the SMARTech Electronic Thesis and Dissertation Collection.
25
Chen, Ming. "Characterization of Pedestrian Electromagnetic Scattering at 76-77GHz". The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1385579499.
Testo completo
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Guo, Baojian Overfelt Ruel A. "Measurements of the thermal expansion and heat capacity of metals by electromagnetic levitation". Auburn, Ala., 2006. http://hdl.handle.net/10415/1328.
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Pirttijärvi, M. (Markku). "Numerical modeling and inversion of geophysical electromagnetic measurements using a thin plate model". Doctoral thesis, University of Oulu, 2003. http://urn.fi/urn:isbn:951427119X.
Testo completoAbstract (sommario):
Abstract
The thesis deals with numerical methods designed for the modeling and inversion of geophysical electromagnetic (EM) measurements using a conductive thin plate model. The main objectives are to study the EM induction problem in general and to develop practical interpretation tools for mineral prospecting in particular.
The starting point is a linearized inversion method based on the singular value decomposition and a new adaptive damping method. The inversion method is introduced to the interpretation of time-domain EM (TEM) measurements using a thin plate in free-space. The central part of the thesis is a new approximate modeling method, which is based on an integral equation approach and a special lattice model. At first the modeling method is applied to the interpretation of frequency-domain EM (FEM) data using a thin plate in conductive two-layered earth. After this time-domain responses are modeled applying a Fourier-sine transform of broadband FEM computations.
The results demonstrate that the approximate computational method can model the geophysical frequency and time-domain EM responses of a thin conductor in conductive host medium with sufficient accuracy, and that the inversion method can provide reliable estimates for the model parameters. The fast forward computation enables interactive interpretation of FEM data and feasible forward modeling of TEM responses. The misfit function mapping and analysis of the singular value decomposition have provided additional information about the sensitivity, resolution, and the correlation behavior of the thin plate parameters.
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Rousseau, Moshe. "A broad-band compact range for radio frequency electromagnetic susceptibility and emission measurements". Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254199.
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Boykov, Nikolay D. "Measurements of the electrical properties of coal measure rocks". Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4715.
Testo completoAbstract (sommario):
Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains xi, 89 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 88-89).
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Mackenzie, Anne I. Rao S. M. "Paired pulse basis functions and triangular patch modeling for the method of moments calculation of electromagnetic scattering from three-dimensional, arbitrarily-shaped bodies". Auburn, Ala., 2008. http://hdl.handle.net/10415/1447.
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Law, Glenn W. (Glenn Woodrow). "Measurements of ocular counterrolling during linear accelerations using an electromagnetic scleral search coil system". Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/43236.
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Puckett, Andrew James Ruehe. "Recoil polarization measurements of the proton electromagnetic form factor ratio to high momentum transfer". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/63019.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 305-313).
The electromagnetic form factors of the nucleon characterize the effect of its internal structure on its response to an electromagnetic probe as studied in elastic electronnucleon scattering. These form factors are functions of the squared four-momentum transfer Q2 between the electron and the proton. The two main classes of observables of this reaction are the scattering cross section and polarization asymmetries, both of which are sensitive to the form factors in different ways. When considering large momentum transfers, double-polarization observables offer superior sensitivity to the electric form factor. This thesis reports the results of a new measurement of the ratio of the electric and magnetic form factors of the proton at high momentum transfer using the recoil polarization technique. A polarized electron beam was scattered from a liquid hydrogen target, transferring polarization to the recoiling protons. These protons were detected in a magnetic spectrometer which was used to reconstruct their kinematics, including their scattering angles and momenta, and the position of the interaction vertex. A proton polarimeter measured the polarization of the recoiling protons by measuring the azimuthal asymmetry in the angular distribution of protons scattered in CH2 analyzers. The scattered electron was detected in a large-acceptance electromagnetic calorimeter in order to suppress inelastic backgrounds. The measured ratio of the transverse and longitudinal polarization components of the scattered proton is directly proportional to the ratio of form factors GE/Gpm. The measurements reported in this thesis took place at Q2 =5.2, 6.7, and 8.5 GeV 2, and represent the most accurate measurements of G' in this Q2 region to date.
by Andrew James Ruehe Puckett.
Ph.D.
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Emelyanenko, Artyom. "Measurements and interpretation of lateral electromagnetic waves on the surface of low conductivity media". Thesis, Griffith University, 2020. http://hdl.handle.net/10072/393637.
Testo completoAbstract (sommario):
Measurements of electromagnetic fields are used for a wide range of applications. Often such measurements provide a non-destructive and non-intrusive way of obtaining information about the internal structure and other properties of the medium. Observations may be conducted across a very broad frequency range. Depending on the application domain, the frequency bands may range from the UHF band in biomedical engineering to the ULF band in geophysics.
This thesis reports on several experiments where the electric and magnetic fields were measured on the surface of different media for the purpose of determining the electric properties of the material (electric conductivity and relative permittivity).
A series of interference nulls were observed while measuring the electric field at UHF frequencies on the surface of a large, uniform sand dune. The source of the field was a transmitter buried in sand. The same pattern was observed after substituting the active transmitter with a passive scatterer exposed to a surface located electromagnetic transmitter. The scatterer then became a source of the electromagnetic field producing the interference pattern identical to the pattern observed in case of the active transmitter. Modelling of the surface electric field was done using known closed-form solutions for a uniform halfspace and by using an FDTD EM solver. Both approaches showed a close match with the measured fields. By varying the resistivity and the electric permittivity in the constructed models, it is demonstrated that the observed pattern (position of the nulls, nulls depth) depend on these electric properties. The inverse problem is posed with the goal of determining the electric properties of the material using the observed field. The inverse problem was solved, and the conductivity and relative permittivity of sand were determined. Two experiments conducted in different conditions showed the following results: conductivity 1×10-6 S/m and relative permittivity of 2.13 in dry conditions and conductivity 3×10-3 S/m and relative permittivity of 2.86 in wet conditions.
Another experiment reports the measurements of the surface electric field on the top surface of a small three-dimensional concrete block at microwave frequencies (1 – 5 GHz). A copper rod was placed in concrete during sample manufacturing to serve as a scatterer. The FDTD solver was used for modelling and determining the inverse problem solution.
At VLF frequencies, several experiments were conducted using surface impedance measurement equipment TranSIM. TranSIM allows registering amplitude of the electric and magnetic field in the time domain in the frequency range between 100 Hz – 50 kHz. The equipment was used to measure the EM fields produced by lightning strikes. Data collection was conducted on a site where the geology is known. The short-time Fourier transform was used to obtain the spectra of the electric and magnetic fields and the surface impedance was determined in the frequency range 0.5-20 kHz. Frequency sections of apparent resistivity were constructed along the measurement profiles and can be interpreted in terms of the geological sections.
These experiments and subsequent data interpretation techniques represent a novel approach of determining electric properties of the material by observing the electromagnetic field on the surface of the media.
Experiments conducted at UHF and microwave (S-band) frequencies utilize the innovative approach of using the field reradiated by a passive scatterer embedded in the material. Potential applications allow using that approach for non-intrusive data collection when a passive conductor is already present or can be put in the material during manufacturing.
Experiments conducted at VLF frequency range utilize the data collection equipment developed at Griffith University by Mogensen and Thiel. Novel data collection and data processing approach of registering solitary short samples of electric and magnetic fields produced by lightning strikes is discussed. It is shown that the EM field observed in that way can be used consistently for creating a reliable geoelectric model of the media.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
Full Text
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Crockett, Dean D. "Direct measurement of parallel plate heat sink bypass flow". Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/Fall2006/d_crockett_121206.pdf.
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White, Ashley. "Novel High Frequency Electromagnetic Shielding Measurements Within Functional Geometries Using Non-Metal and Fatigued Conductors". University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1501765571693941.
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Zhao, Yulong [Verfasser]. "Numerical modeling of electromagnetic coupling effects for phase correction in borehole EIT measurements / Yulong Zhao". Bonn : Universitäts- und Landesbibliothek Bonn, 2017. http://d-nb.info/1132711487/34.
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Ribbenfjärd, David. "Electromagnetic transformer modelling including the ferromagnetic core". Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-13080.
Testo completoAbstract (sommario):
In order to design a power transformer it is important to understand its internal electromagnetic behaviour. That can be obtained by measurements on physical transformers, analytical expressions and computer simulations. One benefit with simulations is that the transformer can be studied before it is built physically and that the consequences of changing dimensions and parameters easily can be assessed. In this thesis a time-domain transformer model is presented. The model includes core phenomena as magnetic static hysteresis, eddy current and excess losses. Moreover, the model comprises winding phenomena as eddy currents, capacitive effects and leakage flux. The core and windings are first modelled separately and then connected together in a composite transformer model. This results in a detailed transformer model. One important result of the thesis is the feasibility to simulate dynamic magnetization including the inhomogeneous field distribution due to eddy currents in the magnetic core material. This is achieved by using a Cauer circuit combined with models for static and dynamic magnetization. Thereby, all magnetic loss components in the material can be simulated accurately. This composite dynamic magnetization model is verified through experiments showing very good correspondence with measurements. Furthermore, the composite transformer model is verified through measurements. The model is shown to yield good correspondence with measurements in normal operation and non-normal operations like no-load, inrush current and DC-magnetization.QC20100708
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Hodge, Duncan. "Deformation of 113Cs from proton-emission and electromagnetic transition rates". Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/deformation-of-113cs-from-protonemission-and-electromagnetic-transition-rates(4120984a-29b6-498c-8f05-2fe1946fd661).html.
Testo completoAbstract (sommario):
Studying nuclei beyond the proton dripline can provide valuable information on the structure of nuclei at the limits of stability, where the strong nuclear force starts to be overcome by Coulomb repulsion between protons. Simple experimental observables, such as excitation energies and lifetimes of excited states in these proton-unbound nuclei can provide information on the nuclear wave function. Experimental data, such as that presented in this work, can then be used to improve models of nuclear structure at the proton dripline. This thesis presents data from a recoil-decay tagged differential plunger experiment undertaken at the University of Jyvaskyla in 2014. A fusion-evaporation reaction was used to populate excited states in the deformed ground-state proton emitter 113Cs. The JUROGAM-RITU-GREAT experimental setup was used to correlate gamma rays emitted from these excited states with protons emitted from 113Cs and the differential plunger for unbound nuclear states (DPUNS) was placed at the target position to measure the excited state lifetimes. The lifetime of the (11/2+) state in the most intense rotational band of 113Cs was measured to be tau = 24(6) ps, while a limit of tau is less than or equal to 5 ps was found for the lifetime of the higher energy (15/2+) state. The lifetime of proton emission was measured to be tau = 24.2(2) microseconds. The experimental data were used to test the predictions of a non adiabatic quasi-particle model for proton-emitting nuclei, which was employed to deduce the deformation of the states in 113Cs. Wave functions from the non adiabatic quasi-particle model were used to independently calculate proton-emission rates, gamma-ray transition rates and excited state energies as functions of deformation. The deformation of 113Cs could then be extracted from the intersection of the different theoretical values and experimental observables. A deformation of beta2 = 0.22(6)was extracted from the (11/2+) excitation energy and lifetime. The deformation values taken from the proton-emission rate and the lifetime limit of the (15/2+) state were also consistent with this value. The consistency of the different deformations calculated shows the effectiveness of the non adiabatic quasi-particle method when used to calculate the properties of deformed ground-state proton-emitters.
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Wiid, P. Gideon. "Investigating cost-effective EMC methods". Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/1520.
Testo completoAbstract (sommario):
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005.Due to the expensive nature of high frequency measurements in the EMC (Electromagnetic Compatability) field, more affordable methods of measurement instrumentation and environments are investigated. Different calibration methods for an Automatic Network Analyser (ANA) are evaluated against each other to determine the most cost-effective method of calibration. The mathematics for all the calibration methods are used in MATLAB programs which perform the error-calculation and correction which is usually done by the ANA software. These programs can be used to develop a simplified homebuilt ANA at reduced cost. The MATLAB program calibrations are compared to actual ANA calibrations to determine accuracy. Different measurement environments are considered as well to decide on a best compromise between cost and accuracy. To achieve this a reverberation chamber was built in which measurements were done and compared to measurements done on an Open Area Test Site. The Device Under Test was a standard radiator constructed specifically for such measurements. The development of both the radiator and the reverberation chamber are discussed and all the measurement results are considered in this thesis.
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Otto, Tobias. "Propagation effects influencing polarimetric weather radar measurements". Doctoral thesis, Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-71125.
Testo completoAbstract (sommario):
Ground-based weather radars provide information on the temporal evolution and the spatial distribution of precipitation on a macroscopic scale over a large area. However, the echoes measured by weather radars are always a superposition of forward and backward scattering effects which complicates their interpretation. The use of polarisation diversity enhances the number of independent observables measured simultaneously. This allows an effective separation of forward and backward scattering effects. Furthermore, it extends the capability of weather radars to retrieve also microphysical information about the precipitation. The dissertation at hand introduces new aspects in the field of polarimetric, ground-based, monostatic weather radars at S-, C-, and X-band. Relations are provided to change the polarisation basis of reflectivities. A fully polarimetric weather radar measurement at circular polarisation basis is analysed. Methods to check operationally the polarimetric calibration of weather radars operating at circular polarisation basis are introduced. Moreover, attenuation correction methods for weather radar measurements at linear horizontal / vertical polarisation basis are compared to each other, and the robustly working methods are identifiedBodengebundene Wetterradare bieten Informationen über die zeitliche Entwicklung und die räumliche Verteilung von Niederschlag in einer makroskopischen Skala über eine große Fläche. Die Interpretation der Wetterradarechos wird erschwert, da sie sich aus einer Überlagerung von Vorwärts- und Rückwärtsstreueffekten ergeben. Die Anzahl der unabhängigen Wetterradarmessgrößen kann durch den Einsatz von Polarisationsdiversität erhöht werden. Dies ermöglicht eine effektive Trennung von Vorwärts- und Rückwärtsstreueffekten. Desweiteren erlaubt es die Bestimmung von mikrophysikalischen Niederschlagsparametern. Die vorliegende Dissertation betrachtet neue Aspekte für polarimetrische, bodengebundene, monostatische Wetterradare im S-, C- und X-Band. Gleichungen zur Polarisationsbasistransformation von Reflektivitätsmessungen werden eingeführt. Eine vollpolarimetrische Wetterradarmessung in zirkularer Polarisationsbasis wird analysiert. Neue Methoden, die eine Überprüfung der polarimetrischen Kalibrierung von Wetterradarmessungen in zirkularer Polarisationsbasis erlauben, werden betrachtet. Weiterhin werden Methoden zur Dämpfungskorrektur von Wetterradarmessungen in linearer horizontaler / vertikaler Polarisationsbasis miteinander verglichen und Empfehlungen von zuverlässigen Methoden gegeben
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Saeed, Usman. "Adaptive numerical techniques for the solution of electromagnetic integral equations". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41173.
Testo completoAbstract (sommario):
Various error estimation and adaptive refinement techniques for the solution of electromagnetic integral equations were developed. Residual based error estimators and h-refinement implementations were done for the Method of Moments (MoM) solution of electromagnetic integral equations for a number of different problems. Due to high computational cost associated with the MoM, a cheaper solution technique known as the Locally-Corrected Nyström (LCN) method was explored. Several explicit and implicit techniques for error estimation in the LCN solution of electromagnetic integral equations were proposed and implemented for different geometries to successfully identify high-error regions. A simple p-refinement algorithm was developed and implemented for a number of prototype problems using the proposed estimators. Numerical error was found to significantly reduce in the high-error regions after the refinement. A simple computational cost analysis was also presented for the proposed error estimation schemes. Various cost-accuracy trade-offs and problem-specific limitations of different techniques for error estimation were discussed. Finally, a very important problem of slope-mismatch in the global error rates of the solution and the residual was identified. A few methods to compensate for that mismatch using scale factors based on matrix norms were developed.
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Hasar, Ugur Cem. "Microwave nondestructive testing and evaluation of electrical properties of lossy materials". Diss., Online access via UMI:, 2008.
Cerca il testo completoAbstract (sommario):
Thesis (Ph. D.)--State University of New York at Binghamton, Department of Electrical and Computer Engineering, Thomas J. Watson School of Engineering and Applied Science, 2008.Includes bibliographical references.
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Krishnamoorthy, Seshagiri. "Interference Measurements and Throughput Analysis for 2.4 GHz Wireless Devices in Hospital Environments". Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31821.
Testo completoAbstract (sommario):
In recent years, advancements in the field of wireless communication have led to more innovative consumer products at reduced cost. Over the next 2 to 5 years, short-range wireless devices such as Bluetooth and Wireless Local Area Networks (WLANs) are expected to become widespread throughout hospital environments for various applications. Consequently the medical community views wireless applications as ineludible and necessary. However, currently there exist regulations on the use of wireless devices in hospitals, and with the ever increasing wireless personal applications, there will be more unconscious wireless devices entering and operating in hospitals. It is feared that these wireless devices may cause electromagnetic interference that could alter the operation of medical equipment and negatively impact patient care. Additionally, unintentional electromagnetic radiation from medical equipment may have a detrimental effect on the quality of service (QoS) of these short-range wireless devices.
Unfortunately, little is known about the impact of these short-range wireless devices on medical equipment and in turn the interference caused to these wireless devices by the hospital environment. The objective of this research was to design and develop an automated software reconfigurable measurement system (PRISM) to characterize the electromagnetic environment (EME) in hospitals. The portable measurement system has the flexibility to characterize a wide range of non-contiguous frequency bands and can be monitored from a remote location via the internet. In this work electromagnetic interference (EMI) measurements in the 2.4 GHz ISM band were performed in two hospitals. These measurements are considered to be very first effort to analyze the 2.4 GHz ISM band in hospitals.
Though the recorded EMI levels were well within the immunity level recommended by the FDA, it can be expected that Bluetooth devices will undergo a throughput reduction in the presence of major interferers such as WLANs and microwave ovens. A Bluetooth throughput simulator using semi-analytic results was developed as part of this work. PRISM and the Bluetooth simulator were used to predict the throughput for six Bluetooth Asynchronous Connectionless (ACL) transmissions as a function of piconet size and interferer distance.Master of Science
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Carlsson, Joel. "Water Hammer Phenomenon Analysis using the Method of Characteristics and Direct Measurements using a "stripped" Electromagnetic Flow Meter". Thesis, KTH, Fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193125.
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Boyer, Laura L. "Carrier-phase wrap-up caused by rotating a global positioning system antenna and its effect on measurements". Ohio : Ohio University, 1999. http://www.ohiolink.edu/etd/view.cgi?ohiou1175890688.
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Thunell, Rasmus. "Groundwater flow paths in fractured crystalline bedrock : Electromagnetic VLF measurements and modelling of a groundwater basin in Svanberga, Sweden". Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231983.
Testo completoAbstract (sommario):
Sweden is a country with a relatively high number of private wells, where about 1.2 million inhabitants in permanent housing and an equal amount in summer housing relies on private wells as their drinking water supply. At the same time the market for drinking water treatment products is unregulated regarding quality and requirements are needed. A testing facility with the aim of providing quality certifications as well as sustainability- and efficiency- tests of small scale drinking water treatment techniques is under development and located in a decommissioned groundwater treatment plant in Svanberga, outside Norrtälje, Stockholm County, Sweden. The groundwater treatment plant has three operational bedrock wells connected to it and the groundwater system is rather unknown with only a few previous studies done in the region. Better understanding of the hydrogeological system would aid in further work of evaluating the risks of contaminant spread in the region. Trough fracture outcrop mapping, geophysical Very Low Frequency measurements and groundwater modelling using COMSOL Multiphysics this master thesis have identified several possible flow paths within the bedrock connected to the GWTP. The results indicates there are one or two approximately east-west striking fracture zones that could play a major role in transportation of contaminants related to road traffic and agriculture to the wells, while several north to south striking fracture zones most likely supplies the groundwater basin with water from the thicker soil layers in the northern part of the region. Recommendations of future studies includes conducting a detailed pumping test of the operational wells in Svanberga old GWTP as well as verification of the presumed most important identified fracture zones to the south east and north in the studied area by additional geophysical investigations or tracer tests.Testbädd dricksvatten är ett pågående projekt och testanläggning där tester och utveckling av filter och småskaliga tekniker för rening av dricksvatten samt kvalitetscertifiering för effektivitets och hållbarhetstester kommer utföras. Testanläggningen består av ett nedlagt grundvattenverk med tre tillhörande bergborrade brunnar i Svanberga utanför Norrtälje. Grundvattensystemet och flödesvägar för grundvattnet i området är relativt okända och bättre förståelse av hydrogeologin skulle kunna bidra till framtida arbete med att identifiera och bedöma risker för föroreningstransporter i området samt till grundvattenverkets brunnar. Detta examensarbete har genom beprövade metoder i form av sprick-kartering, geofysiska undersökningar (VLF) och grundvattenmodellering med COMSOL Multiphysics identifierat flera möjliga flödesvägar i berggrunden kopplade till grundvattenverket. Resultatet från studien visar att ett antal sprickzoner i öst-västlig riktning utgör en större risk för föroreningstransport av ämnen från trafik och jordbruk samt att en större del av det vatten som tillförs grundvattensystemet troligen har sitt ursprung från tjockare morän-lager i de norra delarna av området. Provpumpningar och verifiering av de identifierade sprick-zonerna genom spårämnestester och geofysiska undersökningar bör utföras för att stärka resultaten från detta arbete och möjligen utöka kunskapen om hydrogeologin i området kring Svanberga gamla grundvattenverk.
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Otto, Tobias. "Propagation effects influencing polarimetric weather radar measurements". Doctoral thesis, Universitätsverlag der Technischen Universität Chemnitz, 2010. https://monarch.qucosa.de/id/qucosa%3A19554.
Testo completoAbstract (sommario):
Ground-based weather radars provide information on the temporal evolution and the spatial distribution of precipitation on a macroscopic scale over a large area. However, the echoes measured by weather radars are always a superposition of forward and backward scattering effects which complicates their interpretation. The use of polarisation diversity enhances the number of independent observables measured simultaneously. This allows an effective separation of forward and backward scattering effects. Furthermore, it extends the capability of weather radars to retrieve also microphysical information about the precipitation. The dissertation at hand introduces new aspects in the field of polarimetric, ground-based, monostatic weather radars at S-, C-, and X-band. Relations are provided to change the polarisation basis of reflectivities. A fully polarimetric weather radar measurement at circular polarisation basis is analysed. Methods to check operationally the polarimetric calibration of weather radars operating at circular polarisation basis are introduced. Moreover, attenuation correction methods for weather radar measurements at linear horizontal / vertical polarisation basis are compared to each other, and the robustly working methods are identified.Bodengebundene Wetterradare bieten Informationen über die zeitliche Entwicklung und die räumliche Verteilung von Niederschlag in einer makroskopischen Skala über eine große Fläche. Die Interpretation der Wetterradarechos wird erschwert, da sie sich aus einer Überlagerung von Vorwärts- und Rückwärtsstreueffekten ergeben. Die Anzahl der unabhängigen Wetterradarmessgrößen kann durch den Einsatz von Polarisationsdiversität erhöht werden. Dies ermöglicht eine effektive Trennung von Vorwärts- und Rückwärtsstreueffekten. Desweiteren erlaubt es die Bestimmung von mikrophysikalischen Niederschlagsparametern. Die vorliegende Dissertation betrachtet neue Aspekte für polarimetrische, bodengebundene, monostatische Wetterradare im S-, C- und X-Band. Gleichungen zur Polarisationsbasistransformation von Reflektivitätsmessungen werden eingeführt. Eine vollpolarimetrische Wetterradarmessung in zirkularer Polarisationsbasis wird analysiert. Neue Methoden, die eine Überprüfung der polarimetrischen Kalibrierung von Wetterradarmessungen in zirkularer Polarisationsbasis erlauben, werden betrachtet. Weiterhin werden Methoden zur Dämpfungskorrektur von Wetterradarmessungen in linearer horizontaler / vertikaler Polarisationsbasis miteinander verglichen und Empfehlungen von zuverlässigen Methoden gegeben.
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Friberg, Carol Diane. "Preliminary processing and evaluation of radar measurements in satellite-path propagation research". Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/45722.
Testo completoAbstract (sommario):
Rain and other precipitation cause attenuation and depolarization of high frequency satellite signals. Some characteristics of rain can be measured by dual-polarized radar. These characteristics can then be used to predict the effects of the rain on satellite-path propagation.
This thesis describes briefly the theory of radar and satellite link measurements. Methods for calibrating the equipment and deriving actual experimental values from measured power are presented in detail. A set of computer programs to approximately predict radar and link values from measured rain rate are developed. Predicted and measured values may then be compared by a researcher to evaluate system operation and assess the importance of the event data. A discussion of the use of sampled data and these comparisons concludes the report.Master of Science
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Sun, Jian Sun. "Ground-Based GNSS-Reflectometry Sea Level and Lake Ice Thickness Measurements". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500992792329906.
Testo completo
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Yan, Bing. "A low cost planar near-field / far-field antenna measurement system /". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ34242.pdf.
Testo completo