Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 49 for “"Specific absorption rate"”.
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Modeling and calculation of the specific absorption rate for multi-antenna mobile devices
… the human exposure to the RF radiation, the specific absorption rate (SAR) is introduced as a measure. Regulatory agencies have standards limiting the maximum SAR to ensure safety. In order to comply with the regulations, the SAR induced in the human head and body should be evaluated by …
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Fast simulation of E1, B1 and Specific Absorption Rate for 7T MRI with the use of graphical processors
Specific Absorption Rate (SAR) is a dominant constraint in high field MR, and has been a topic of much recent interest with developments of parallel transmission systems (pTx). While real-time estimates of local SAR over large volumes as well as SAR-constrained pTx RF design are highly desirable …
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IMAGING SPECIFIC ABSORPTION RATE WITH MR THERMOMETRY USING PARAMAGNETIC LANTHANIDE COMPLEXES AND IN VIVO GABA MR SPECTROSCOPY IN MOVEMENT DISORDERS
… in vivo (MRS). This dissertation focuses separately on the development, application and quantitation issues of these two aspects of MRI.
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Balanced antennas for mobile handset applications. Simulation and Measurement of Balanced Antennas for Mobile Handsets, investigating Specific Absorption Rate when operated near the human body, and a Coplanar Waveguide alternative to the Balanced Feed.
… on the mobile phone ground plane. The specific absorption rate (SAR) performance of the antenna is also studied experimentally by measuring antenna near field exposure. The measurement results are correlated with the calculated ones. A new dual-band balanced antenna using coplanar …
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Investigation, design and implementation of circular-polarised antennas for satellite mobile handset and wireless communications. Simulation and measurement of microstrip patch and wire antennas for handheld satellite mobile handsets and investigations of polarization polarity, specific absorption rate, and antenna design optimization using genetic algorithms.
… antennas are investigated and discussed to operate at L band (1.61-1.6214GHz) and ISM band (2.4835-2.5GHz) A substantial size reduction was achieved compared to conventional designs by introducing special modifications to the antenna geometries. Most of the antennas are designed to produce …
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IDENTIFICATION OF Cav 3.2 T-TYPE VOLTAGE GATED CALCIUM CHANNELS AS KEY MEDIATORS OF TARGETED INHIBITION OF HEPATOCELLULAR CARCINOMA BY AMPLITUDE-MODULATED RADIOFREQUENCY ELECTROMAGNETIC FIELDS
… mechanism of action w e have a ssessed the Specific Absorption Rate (SAR) level and dis tribution inside the human body . Additionally, we performed various i n vitro and in vivo experiments that were exposed to HCC - specific AM RF EMF using systems replicating human exposure levels and …
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Evaluation of nanoparticles-based thermotherapy for cancer
… iron oxide nanoparticles can be used to generate heat for the treatment of cancer. With suitable coating, these nanoparticles are biocompatible, stable in solution, and absorbed by tumor cells in good contrast. The mechanism of heating is mainly due to Neel relaxation process and a quantity …
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Experimental methodology for non-thermal effects of electromagnetic radiation on biologics
… we document a method for determining specific absorption rate (S.A.R.) using vials containing 1.5 cc of saline to represent biological samples. This methodology yielded S.A.R. values of approximately 30 W kg-1(-9 dBm) and 150 W kg-1(-6.5 dBm) for 915 MHz and 320 W kg-1 (-9 dBm) and 450 …
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Influência do tamanho de nanopartículas em suas propriedades de hipertermia magnética
… de campo magnético AC, para o cálculo do Specific Absorption Rate (SAR). Foi observado que existe um limite para o diâmetro da nanopartícula, no qual a relaxação de Neél deixa de ser o mecanismo principal ao aquecimento e a histerese passa a contribuir
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Compact planar wearable ultra wideband antenna for on-body applications
… have been reported in this thesis. The substrates of the proposed antennas have been made of jeans while radiators were made of copper tapes. Simulated and measured performances of the antennas in terms of return loss and radiation patterns have been discussed in this work. Recorded results …
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Comportamento térmico em regime não-adiabático de nanopartículas superparamagnéticas sob ação de um campo magnético oscilante
… and FeO:F e2O3 superparamagnetic nanoparticles. Specifically, we aim to fully understand the influence of the composition, nanoparticle size, as well as amplitude and frequency of the field on the specific absorption rate of the samples. Here, we propose a theoretical model to describe the …
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Radio frequency heating of magnetic perovskite nanoparticles in solution for biomedical applications
… magnetic resonant imaging. Our research concentrates on the magnetic susceptibility of MNPs and the effect on heat generation applications for use in biomedical applications as an alternative to invasive treatments such as chemotherapy. In this thesis we have studied the response of clusters and …
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Coil performance evaluation based on electrodynamics : tools for hardware design and validation in magnetic resonance imaging
… are shown, and coil performance maps are generated based on the ratio of experimentally measured SNR to this ultimate intrinsic SNR. Parallel excitation, which involves independent transmission with multiple RF coils distributed around the body, can be used to improve the homogeneity of RF …
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Parallel transmission for magnetic resonance imaging on a 9.4 Tesla Human System.
… in actual experiments. In this thesis, we demonstrate the first successful implementation of parallel transmission at an ultrahigh field of 9.4 Tesla (T) in the human brain with an eight-channel transmit system, using accelerated (x 4) RF pulses designed to create arbitrarily shaped excitation …
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Numerical field simulation for parallel transmission in MRI at 7 tesla
… improvement to coil design that has been demonstrated to mitigate B1* inhomogeneity, manifest as center brightening, for high-field magnetic resonance imaging (MRI). Parallel transmission achieves spatially-tailored pulses through multiple radiofrequency (RF) excitation coils that can be …
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Mitigating Inhomogeneity in High-Field MRI Excitations: Arbitrary Waveform Optimization and Multiphoton Parallel Transmission (MP-pTx)
… (and ultimately heating), quantified as the specific absorption rate (SAR). To address these challenges, we introduce a method for optimizing patient-specific pulses using a global waveform (Ritz) approach, enabling rapid, in-scanner optimization. While pTx effectively addresses flip angle …
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Enhanced Microwave Hyperthermia using Nanoparticles
… the nanoparticles allow the electromagnetic absorption to be focused in the tumor and can be used to treat deep tumors in organs, such as the liver. Iron oxide magnetic nanoparticles were considered for this study as they are non-toxic and bio-compatible. For the case of breast cancer, the …
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The Tissue-reduced Virtual Family Models for RF-induced Heating Evaluation of Passive Medical Implants at 1.5 T and 3 T
… by the ASTM standard. The simulated results of specific absorption rate averaged to 1 gram (SAR1g) near the device at 1.5 T and 3 T in the human models and ASTM phantom were extracted for comparison.
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Low-power dual-band on-body antenna for wireless body sensor networks
… the optimum design of the on-body antenna to operate as a central antenna for WBAN. Five types of helical antennas are proposed in the present thesishaving a dual-frequency operation at 2.45 GHz and 5.8 GHz. The proposed antennas are optimized to maximize the Signal-to-Noise-Ratio (SNR) and, …
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