Universal Mobile Telecommunications Systems (UMTS) is the preferred third generation (3G) communication standard for mobile communications and will provide worldwide coverage, a convenient software technology and very high data rate. The high data rate, especially, requires the use of bandwidth-efficient modulation schemes such as Quadrature Phase Shift Keying (QPSK). But modulation schemes such as QPSK need, in turn, a very linear power from the output of the transmitter power amplifier in order to meet the spectral requirements. A linear power amplifier, traditionally, has very low energy efficiency. Poor energy efficiency directly affects operational costs and causes thermal heating issues in base station transmitters. Thus the power amplifier designer is forced to trade-off between linearity and efficiency. As a result of this trade-off a Class-AB power amplifier is most often used in QPSK based systems. Class-AB power amplifiers provide acceptable linearity at efficiency values around 45-50% typically. This compromise is not a satisfactory solution but is inevitable while using traditional power amplifier design techniques. This thesis details the use of a Class-F amplifier with carefully chosen bias points and harmonic traps to overcome this problem. Class-F amplifiers are usually considered as very high efficiency (80% or more power-added efficiency) amplifiers where the high efficiency is obtained through the use of harmonic traps (L-C filters or quarter-wavelength transmission lines), which provide suitable terminations (either open or short) for the harmonics generated. By doing this, a square wave drain voltage and a peaked half-sinusoidal drain current out-of-phase by 180 are produced. Since only a drain voltage or a drain current exists at any given time, the power dissipation is ideally zero resulting in 100% theoretical efficiency. These very high efficiency values are usually associated with poor linearity. However the linearity can be improved to meet the design standards but compromising on efficiency. Even after this is done, efficiencies are usually 10 to 15% greater than a traditional Class AB power amplifier with similar linearity performance. Thus efficiency can be improved without affecting linearity by the use of Class-F power amplifiers. In order to verify this theory, a Class-AB and a Class-F power amplifier are designed using Motorola's high voltage laterally diffused metal oxide semiconductor (LDMOS) transistor. The choice of bias points and the design of the harmonic traps are very critical for the Class-F performance and hence were designed after careful consideration. The designs were simulated on Agilent's Advanced Design System (ADS) and the simulated results were compared for three different power levels namely, the peak power, 3 dB below peak power and 6 dB below peak power. At all of these power levels it was noted that the Class-F and Class-AB power amplifiers have very similar linearity performance whereas the Class-F power amplifiers show about 10% improvement in efficiency in comparison to the Class-AB power amplifiers. / Master of Science

An innovative experimental facility was developed for testing flush-mounted, diffusing serpentine inlets intended for use on blended-wing-body aircraft. The static ground test facility was able to simulate the boundary layer profile expected to be ingested by inlets mounted on the aft sections of these aircraft. It generated Mach numbers ranging from 0.19 to 0.4 and boundary layer thicknesses between 36% and 45%. The circumferential distortions at the aerodynamic interface plane of the serpentine inlet were also calculated, and ranged between 0.0042 for the lowest Mach number, to 0.0098 for the highest Mach number. Reynolds numbers for the tests ranged between 1.2 million and 2.4 million depending on engine speed and Mach number. The results of the experiment were compared to a previous NASA report, and showed close agreement in distortion patterns and pressure losses at a Mach number of 0.25. / Master of Science

Total pressure non-uniformities in an axial flow compressor can contribute to losses in aerodynamic operability through a reduction in stall margin, pressure rise and mass flow, and to loss of structural integrity through means of high cycle fatigue (HCF). HCF is a primary mechanism of blade failure caused by vibrations at levels exceeding material endurance limits. Previous research has shown total pressure distortions to be the dominant HCF driver in aero engines, and has demonstrated the damaging results of total pressure distortion induced HCF on first stage fan and compressor blade rows [Manwaring et al., 1997]. It is, however, also of interest to know how these distortion patterns propagate through a rotor stage and impact subsequent downstream stages and engine components. With current modeling techniques, total pressure distortion magnitudes can be directly correlated to induced blade vibratory levels and modes. The ability to predict downstream distortion patterns then allows for the inference of blade vibratory response of downstream blades to inlet distortion patterns. Given a total pressure distortion excitation entering a blade row, the nonlinear Volterra series can serve as a predictor of the downstream total pressure profile and therefore provide insight into the potential for HCF in downstream blade rows. This report presents the adaption of nonlinear Volterra theory to the prediction of the transport of non-uniform total pressure distortions through an axial flow compressor. The use of Volterra theory in nonlinear system modeling relies on the knowledge of Volterra kernels, which capture the behavior of a system's response characteristics. Here an empirical method is illustrated for identifying these kernels based on total pressure distortion patterns measured both upstream and downstream of a transonic rotor of modern design. A Volterra model based on these kernels has been applied to the prediction of distortion transfer at new operating points of the same rotor with promising results. Methods for improving Volterra predictions by training Volterra kernels along individual streamlines and normalizing total pressure data sets by physics-based parameters are also investigated. / Master of Science

Research suggests a relationship between time distortion and mental health disorders, and the present study sought to examine this proposition. Prior research suggests that negative emotions are associated with the slowing down of time. Because mental health disorder symptomology is associated with more negative emotions, it was predicted that negative emotions would mediate the relationship between mental health disorder symptomology and time distortion. A survey was administered to university students that contained measures of anxiety, depression, emotional experiences, and time perception. Mental health disorder symptomology was found to be related to negative emotions. However, negative emotions and mental health disorder symptomology were not related to time distortion. Thus, the proposed mediation model was not supported. The primary reason for these results likely lies in the challenges of measuring time distortion. Despite the lack of effects found in the present study, investigating this topic is crucial for understanding the perceptual experiences of those with mental health disorders.

The human auditory system can become an active agent in the production of sound when stimulated with specific tone combinations. The resulting auditory distortion products can be amplified and drawn attention to by employing certain just intonation practices – a compositional technique that may serve as a powerful catalyst for reaching different states of mind in listeners. In this thesis, those psychoacoustic phenomena critical to the act of tuning are explored. An experiential tuning protocol is introduced and supported by insights from physiology and neuroscience research. Based on the tuneability of musical intervals, a harmonic framework involving harmonic and subharmonic relationships is analyzed and exemplified via the accompanying composition XV XXVII III XXI IX: Variations. From a phenomenological perspective, the research extends to broader contexts, investigating potential social, ethical, cultural, and political implications of such a practice. / <p><em>XV XXVII III XXI IX: Variations</em> by Luka Aron is a work in 5 parts in which a selected acoustic instrumentation, consisting of bass clarinet, contrabass, euphonium, foghorn organ, harpsichord, serpent, shō, and trumpet coalesces with analog as well as digital synthesis, into one unified mass of sound. By tuning sustained tones towards precision upon occupying the same pitch space, the various timbresare as much canceled out as reinforced, resulting in flux states of spectral fusion. This effect is further achieved through traversing a labyrinth of multiple closely related overtone series, serving as a harmonic framework for the piece’s ever-shifting bedrock. A careful selection of partials is presented, stimulating additional tones in the perception of the listener, making use of a psychoacoustic phenomenon, commonly referred to as otoacoustic emissions, or combination tones. Heavy distortion is then applied to the source signal, allowing the combination tones to materialize in the physical space. Through this, a secondary structure (that, in fact, exposes theundertone series) is gradually unveiled: like light rays meeting the surface of water, partially reflecting back to air, and refracting at once, as they pass from one medium to the other. On a structural plane, the piece stems from complex multi-layered golden mean relationships that permeate to all levels of the composition, ranging from the overall arc to the formal as well as rhythmical aspects of each individual variation, where every sound event is spiraling out of the previous one, and the endpoint is determined right at the initial stroke, before ever unfolding over the total playtime of 43 minutes. With Aron operating the Buchla 200 and EMS VCS3 synthesizers, in addition to the SuperCollider andPure Data coding environments, the cast of musicians includes an array of Stockholm-based artists, such as Mattias Hållsten on shō–a japanese mouth organ–and Susana Santos Silva on trumpet (both members of CC Hennix’ Kamigaku ensemble), just intonation contrabassist Vilhelm Bromander, along with Amina Hocine and her unique self-built foghorn organ. Frequent collaborators Fabian Willmann on bass clarinet and Raphaël Rossé on serpent and euphonium join from the electroacoustic group MINUA, which Aron co-founded. For this occasion, the piece will be diffused on an arrangement of 31 speakers.</p><p><strong>Den klingande delen är arkiverad.</strong></p><p><strong>Luka Aron är artistnam för Luca Aaron Pusch.</strong></p>

Yes / RF power amplifiers in mobile WiMAX transceivers operate in an inherently nonlinear manner. It is possible to amplify the signal in the linear region, and avoid distortion, using output power back-off; however, this approach may suffer significant reduction in efficiency and power output. This paper investigates the use of Doherty techniques instead of back-off, to simultaneously achieve good efficiency and acceptable linearity. A 3.5 GHz Doherty RFPA has been designed and optimized using a large signal model simulation of the active device, and performance analysis under different drive levels. However, the Doherty EVM is generally poor for mobile WiMAX. Linearity may be improved by further digital pre-distortion, and a simple pre-distortion method using forward and reverse AM-AM and AM-PM modeling. Measurements on the realized amplifier show that this approach satisfies the EVM requirements for WiMAX base stations. It exhibits a PAE over 60%, and increases the maximum linear output power to 43 dBm, whilst improving the EVM.

This thesis describes a novel approach that utilizes a special property of the Hanning window to accurately detect the fundamental frequency of the data signal in the presence of harmonic and interharmonic interference. After obtaining the fundamental frequency, the same procedure is applied to all possible harmonics to be filtered for further analysis of the interharmonics. The proposed approach is validated using numerical tests. In the literature, different authors have shown the difficulty of extracting a synchronized sampling frequency from the analyzed signal and discussed the effect of deviation of the fundamental in the presence of harmonics. This thesis suggests a new approach to overcome the difficulties, even if the interharmonics present are in frequency bins near the fundamental. In order to perform the interharmonic analysis, the author followed the IEC standard draft signal processing recommendations, with the exception of using a weighted Hanning window instead of a rectangular window in order to minimize the effect of the spectral leakage, and to minimize the effect of interharmonics on the main harmonics.

The current research investigates the use of solid-embedded thermocouples for determining accurate transient temperature measurements within a solid medium, with emphasis on measurements intended for use in inverse heat conduction problems. Metal casting experiments have been conducted to collect internal mold temperatures to be used, through inverse conduction methods, to estimate the heat exchange between a casting and mold. Inverse conduction methods require accurate temperature measurements for valid boundary estimates. Therefore, various sources of thermocouple measurement uncertainty are examined and some suggestions for uncertainty reduction are presented. Thermocouple installation induced bias uncertainties in experimental temperature data are dynamically corrected through the development and implementation of an embedded thermocouple correction (ETC) transfer function. Comparisons of experimental data to dynamically adjusted data, as well as the inverse conduction estimates for heat flux from each data set, are presented and discussed.

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