Spelling suggestions: "subject:"radio frequency."" "subject:"sadio frequency.""
491 |
Segmentation en imagerie échocardiographique par ensembles de niveaux paramétriques évoluant à partir des statistiques du signal radiofréquence gmentation in echocardiographic imaging using parametric level set model driving by the statistics of the radiofrequency signal /Bernard, Olivier Friboulet, Denis. January 2007 (has links)
Thèse doctorat : Images & Systèmes : Villeurbanne, INSA : 2006. / Thèse rédigée en anglais. Titre provenant de l'écran-titre. Bibliogr. p. 177-189.
|
492 |
Complementary metal-oxide-semiconductor frequency conversion techniques for wideband code division multiple access /Fang, Sher Jiun. January 2003 (has links)
Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 163-176).
|
493 |
A CMOS tunable transmission line phase shifter and voltage-controlled oscillator for wireless communications /Kim, Taeik. January 2004 (has links)
Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 102-109).
|
494 |
A ray-based investigation of the statistical characteristics and efficient representation of multi-antenna communication channels /German, Gus R. January 2004 (has links) (PDF)
Thesis (M.S.)--Brigham Young University. Dept. of Electrical and Computer Engineering, 2004. / Includes bibliographical references (p. 145-154).
|
495 |
Parasitic-aware design and optimization of CMOS RF power amplifier /Choi, Kiyong. January 2003 (has links)
Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 146-149).
|
496 |
Photonic microwave processor based on fiber optical parametric amplifierLi, Jia, January 2009 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references. Also available in print.
|
497 |
RF integrated circuit design options : from technology to layout /Zhang, Xibo. January 2003 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 59-61). Also available in electronic version. Access restricted to campus users.
|
498 |
RF characterization and modeling of MOSFET power amplifier in wireless communication /Tsui, Kenneth Kin Pun. January 2003 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references. Also available in electronic version. Access restricted to campus users.
|
499 |
Ultrasound Current Source Density Imaging in Live Rabbit Hearts Using Clinical Intracardiac CatheterLi, Qian January 2015 (has links)
Ultrasound Current Source Density Imaging (UCSDI) is a noninvasive modality for mapping electrical activities in the body (brain and heart) in 4-dimensions (space + time). Conventional cardiac mapping technologies for guiding the radiofrequency ablation procedure for treatment of cardiac arrhythmias have certain limitations. UCSDI can potentially overcome these limitations and enhance the electrophysiology mapping of the heart. UCSDI exploits the acoustoelectric (AE) effect, an interaction between ultrasound pressure and electrical resistivity. When an ultrasound beam intersects a current path in a material, the local resistivity of the material is modulated by the ultrasonic pressure, and a change in voltage signal can be detected based on Ohm's Law. The degree of modulation is determined by the AE interaction constant K. K is a fundamental property of any type of material, and directly affects the amplitude of the AE signal detected in UCSDI. UCSDI requires detecting a small AE signal associated with electrocardiogram. So sensitivity becomes a major challenge for transferring UCSDI to the clinic. This dissertation will determine the limits of sensitivity and resolution for UCSDI, balancing the tradeoff between them by finding the optimal parameters for electrical cardiac mapping, and finally test the optimized system in a realistic setting. This work begins by describing a technique for measuring K, the AE interaction constant, in ionic solution and biological tissue, and reporting the value of K in excised rabbit cardiac tissue for the first time. K was found to be strongly dependent on concentration for the divalent salt CuSO₄, but not for the monovalent salt NaCl, consistent with their different chemical properties. In the rabbit heart tissue, K was determined to be 0.041 ± 0.012 %/MPa, similar to the measurement of K in physiologic saline: 0.034 ± 0.003 %/MPa. Next, this dissertation investigates the sensitivity limit of UCSDI by quantifying the relation between the recording electrode distance and the measured AE signal amplitude in gel phantoms and excised porcine heart tissue using a clinical intracardiac catheter. Sensitivity of UCSDI with catheter was 4.7 μV/mA (R² = 0.999) in cylindrical gel (0.9% NaCl), and 3.2 μV/mA (R² = 0.92) in porcine heart tissue. The AE signal was detectable more than 25 mm away from the source in cylindrical gel (0.9% NaCl). Effect of transducer properties on UCSDI sensitivity is also investigated using simulation. The optimal ultrasound transducer parameters chosen for cardiac imaging are center frequency = 0.5 MHz and f/number = 1.4. Last but not least, this dissertation shows the result of implementing the optimized ultrasound parameters in live rabbit heart preparation, the comparison of different recording electrode configuration and multichannel UCSDI recording and reconstruction. The AE signal detected using the 0.5 MHz transducer was much stronger (2.99 μV/MPa) than the 1.0 MHz transducer (0.42 μV/MPa). The clinical lasso catheter placed on the epicardium exhibited excellent sensitivity without being too invasive. 3-dimensional cardiac activation maps of the live rabbit heart using only one pair of recording electrodes were also demonstrated for the first time. Cardiac conduction velocity for atrial (1.31 m/s) and apical (0.67 m/s) pacing were calculated based on the activation maps. The future outlook of this dissertation includes integrating UCSDI with 2-dimensional ultrasound transducer array for fast imaging, and developing a multi-modality catheter with 4-dimensional UCSDI, multi-electrode recording and echocardiography capacity.
|
500 |
Η τεχνολογία RFID στο χώρο της υγείαςΠαγκράτης, Παναγιώτης 18 December 2008 (has links)
- / -
|
Page generated in 0.0356 seconds