Thesis (Ph.D.)--Mathematics, Georgia Institute of Technology, 2008. / Committee Chair: Yang Wang; Committee Member: Christopher Heil; Committee Member: Doron Lubinsky; Committee Member: Guillermo Goldsztein; Committee Member: Steven W. McLaughlin

Thesis (M.S. in Applied Physics)--Naval Postgraduate School, Dec. 2004. / Thesis Advisor(s): Christopher Olsen. Includes bibliographical references (p. 83-84). Also available online.

Skiriūtė D. Transporto triukšmo tyrimai Tauragėje: Aplinkos inžinerijos bakalauro darbas/mokslinis vadovas lekt. R. Klimas; Šiaulių universitetas, Technologijos fakultetas, Statybos inžinerijos katedra. – Šiauliai, 2011. Didžiąją miesto triukšmo dalį (apie 80%) sukelia transportas. Transporto priemonės yra toks specifinis triukšmo šaltinis, kad jis įsiskverbia į bet kurią miesto teritoriją – gyvenamuosius ir pramonės rajonus, ligoninių ir sanatorijų zonas, miestų centrus, poilsio zonas. Transporto triukšmas sukelia diskomfortą ne tik gyventojams, bet ir įvairių įstaigų darbuotojams, vaikams, moksleiviams, gyvūnams. Tokio triukšmo padariniai žmonėms yra įvairios sveikatos problemos. Atliekant transporto triukšmo tyrimus Tauragės mieste pasirinkta 15 vietų: mokyklų, darželių–lopšelių, viešųjų tyliųjų miesto zonų, parkų, ligoninės, gyvenamųjų namų teritorijose. Gauti rezultatai lyginami su higienos norma, ir tai suteikia galimybę parašyti išvadas ir pateikti pasiūlymus triukšmo mažinimui. Mažinant transporto triukšmo sklaidą Tauragės mieste būtina taikyti triukšmo mažinimo priemones: mažinti automobilių eismą miesto centrinėje dalyje, įrengiant aplinkelį; riboti eismą gatvėse; įrengti dviračių ir pėsčiųjų takus; organizuoti viešojo transporto maršrutus ir dažniau juo naudotis; skatinti biotransporto naudojimą; plėsti dviračių takų tinklą. / Transport makes the major part (60-80%) of the city noise. The vehicle is the specific source of noise that it penetrates into any area – in residential and industrial areas, in hospitals and sanatoriums areas, in urban centers, and recreation areas. Traffic noise causes discomfort, not only residents but also the employees of the different companies, children, school children and animals. A range of health problems is effects of such noises to people. Performing the research of the traffic noise in Tauragė town 15 places were selected following: in the areas of schools, kindergartens, nurseries, public silent areas of the city, hospitals, and residential areas. The obtained results are compared with standards of hygiene, and this provides an opportunity to write conclusions and to make proposals for the prevention of noise. Reducing traffic noise in the dissemination in Tauragė town the noise reducing measures must be applied: to reduce automobile traffic in the central part of the town installing a bypass; to limit traffic on the streets; to install the bicycle and pedestrian paths; to organize public transport routes, and to use it more frequently; to construct the noise protection barriers.

Feedforward is known to be one of the best methods for power amplifier linearization due to its superior linearization performance and broadband stable operation. However feedforward systems have relatively poor power efficiency and are complicated due to the presence of two nonlinear amplifiers and the requirements of amplitude, phase and delay matching within two different loops. In this thesis stochastic characterization of a simple feedforward system with autocorrelation analysis has been presented for Code Division Multiple Access (CDMA) applications taking the amplitude and delay mismatches into consideration. It has been assumed that, the input signal can be represented as Gaussian noise, main and error amplifiers can be modeled with third order AM/AM nonlinearities and there exists no phase mismatch within the loops. Hence closed form expressions, which relate the main channel and distorted adjacent channel power at any point in the feedforward circuitry to the system parameters, have been obtained. Consequently, a mathematical handy tool is achieved towards specifying the circuit parameters rapidly for optimum linearity performance and efficiency. The developed analytical model has been verified by Radio Frequency (RF) and system simulations. An alternative approach towards modeling feedforward systems for arbitrary signals has also been brought into consideration and has been verified with system simulations.

This master thesis is focused on the diagnostics of vibrations and noise of an internal combustion engine. The work also includes a summary of the current state of knowledge in which the quantities used, transmission paths, measuring devices and the possibilities of performing frequency analysis are analysed. As part of the technical experiment on which this work is based, vibrations and noise on the tractor engine are measured. The obtained data are then further processed using the BK Connect program. Subsequently, a frequency analysis is performed, specifically an order analysis. The conclusion of the analysis consists of an evaluation of individual orders that cause excitation that occur in the investigated motor.

The thesis deals with the design of the experimental testing rig. Test rig is designed to measure NVH transmission parameters. First, basic knowledge of vibro-acoustic measurement is discussed. This is followed by an evaluation of the most commonly used power devices to derive real loads on measured gearboxes. In more detail, a back-to-back test rig is disassembled among other things. In the thesis are described two main components, which are composed of a connecting element and a test bench. Both components were optimized during the design due to their modal properties. Numerical modal analysis was performed in ANSYS Workbench software. The thesis also includes strength calculations performed using both numerical and analytical approaches. The indispensable result of the design work is the complete drawing documentation. Finally, measurements of vibrations and noise on the physically made connecting element assembly have been performed and subsequently evaluated.

We often have to face the fact that several signals are mixed together in unknown environment. The signals must be first extracted from the mixture in order to interpret them correctly. This problem is in signal processing society called blind source separation. This dissertation thesis deals with multi-channel separation of audio signals in real environment, when the source signals outnumber the sensors. An introduction to blind source separation is presented in the first part of the thesis. The present state of separation methods is then analyzed. Based on this knowledge, the separation systems implementing fuzzy time-frequency mask are introduced. However these methods are still introducing nonlinear changes in the signal spectra, which can yield in musical noise. In order to reduce musical noise, novel methods combining time-frequency binary masking and beamforming are introduced. The new separation system performs linear spatial filtering even if the source signals outnumber the sensors. Finally, the separation systems are evaluated by objective and subjective tests in the last part of the thesis.

reducing noise, noise in railway transport, management of application of products for modification of adhesion