Micromachined microphones with diffraction-based optical displacement detection are presented. A compliant membrane is made part of a phase sensitive diffraction grating, and the deflection resulting from external acoustic pressure alters the intensities of the diffracted orders which are monitored with integrated photodiodes. The scheme provides the displacement sensitivity of a Michelson interferometer and can be integrated without beam splitters or critical alignment problems into volumes on the order of 1mm³. The method is implemented and characterized using microphone membranes with integrated diffraction grating back electrodes fabricated on silicon using Sandia National Laboratories' dedicated processing platform. Detailed response characterization in both air and vacuum environments is performed to extract the diaphragm properties and high frequency cutoff frequencies of the microphone. Results from a finite element model of the microphone structure are in good agreement with measured data. The sensor's internal noise is characterized with measurements performed in the anechoic acoustic test facility at Georgia Tech. While utilizing 2.4mW of laser power, an (A) weighted displacement resolution of 6×10⁻⁴Å/√Hz is measured which is limited by thermal acoustic noise caused by the microphone's back-plate flow resistance.

This dissertation explores high-speed silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) bipolar complementary metal oxide semiconductor (BiCMOS) circuits for next-generation ground- and space-based millimeter-wave (MMW >= 30 GHz) communication front-ends and X-band (8 to 12 GHz) radar (radio detection and ranging) modules. The requirements of next-generation transceivers, for both radar and communication applications, are low power, small size, light weight, low cost, high performance, and high reliability. For this purpose, the high-speed circuits that satisfy the demanding specifications of next-generation transceivers are implemented in SiGe HBT BiCMOS technology, and the device-circuit interactions of SiGe HBTs to transceiver building blocks for performance optimization and radiation tolerance are investigated. For X-band radar module components, the dissertation covers: (1) The design of an ultra-low-noise X-band SiGe HBT low-noise-amplifier (LNA). (2) The design of low-loss shunt and series/shunt X-band Si CMOS single-pole double-throw (SPDT) switches. (3) The design of a low-power X-band SiGe HBT LNA for near-space radar applications. For MMW communication front-end circuits, the dissertation covers: (4) The design of an inductorless SiGe HBT ring oscillator for MMW operation. (5) The study of emitter scaling and device biasing on MMW SiGe HBT voltage-controlled oscillator (VCO) performance. (6) The study of proton radiation on MMW SiGe HBT transceiver building blocks.

No description available.

Thesis (M.S.)--Brigham Young University. Dept. of Electrical and Computer Engineering, 2004. / Includes bibliographical references (p. 65-69).

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Cunefare, Kenneth A.; Committee Member: Qu, Jianmin; Committee Member: Ryherd, Erica. Part of the SMARTech Electronic Thesis and Dissertation Collection.

No description available.

Η διπλωματική εργασία μου ασχολείται με την αφαίρεση θορύβου από Ηλεκτροκαρδιογράφημα(ΗΚΓ), με σκοπό τη καθαρότερη λήψη του σήματος για διαγνωστικούς σκοπούς. Ο θόρυβος στο ΗΚΓ προέρχεται από διάφορες πηγές, είτε τεχνικές, είτε φυσιολογικές. Η αφαίρεσή του είναι ουσιαστικής σημασίας. Στόχος της εργασίας αυτής είναι η παράθεση των κυρίων μεθόδων αφαίρεσης θορύβου από ΗΚΓ και του τρόπου λειτουργίας τους, καθώς και η παράθεση παραδειγμάτων από την πρόσφατη βιβλιογραφία. / --

Hospital sound environments are complex and hard to understand. One of the most important factors in these environments is the effective communication between staff members in regards to patient care and successful communication depends in part on the hospital’s sound environment. In this study, objective sound measurements as well as occupant perceptive data were collected at three hospitals. Sound pressure levels; including maximum, peak, minimum and equivalent levels were recorded in these hospitals, in addition to active impulse response measurements. Acoustic descriptors of the sound environment such as spectral content, level distributions, energy decay and temporal patterns were examined. The perception of the hospital soundscape (sound environment) was evaluated through surveys of the staff, patients and visitors to units. It was found that noise levels in all patient rooms and work areas were significantly higher than guidelines laid out in previous literature and by professional organizations. This work contributes to the field by broadening the metrics used to quantify hospital acoustic environments. In addition, this work added to the field by providing the most rigorous acoustic field measurement set published to date. This was done to create an accurate portrayal of the hospital soundscape environment.

Baigiamajame darbe nagrinėjamas konvejerių keliamas triukšmas bei galimybės, kaip jį sumažinti. Apžvelgiama dažniausiai maisto pramonėje naudojamų konvejerių tipai, veikimo principai. Aprašomos pagrindinės triukšmo kilimo priežastys grandininiuose konvejeriuose bei kaip galima sumažinti kylantį triukšmą. Atlikti trys eksperimentiniai tyrimai. Aprašyta tyrimų eiga ir sąlygos, pateikti gauti rezultatai. Darbo pabaigoje surašytos išvados, pateiktas literatūros sąrašas. Darbo apimtis 60 A4 formato lapai bei 4 A4 formato lapai priedų. Baigiamasis darbas parašytas remiantis 36 bibliografiniais šaltiniais. / In this graduation thesis Conveyor noise and possibilities to reduce it are investigated. Common conveyors in food industry, their types and operating principles are reviewed. Main factors causing noise in chain conveyors and ways of reducing them are described. Three experimental investigations were completed. Investigation process, conveyoring line conditions are described, results presented. There are conclusion and used literature list written down at the end of thesis. Thesis includes 60 A4 format pages and 4 A4 format pages of supplement. 36 bibliographical sources are used.

No description available.