This research provides the original work on the geometry factors selection for single crystal sapphire optical fiber (SCSF) to improve the optical property in sensing applications. Single crystal sapphire fibers were fabricated with a Laser Heated Pedestal Growth (LHPG) system, which was constructed in-house at Virginia Tech. The cost effective, high efficiency and fully operational Laser-heated Pedestal Growth (LHPG) system as well as the fiber fabrication process were also demonstrated in this research. The results indicated the windmill single crystal sapphire optical fiber (SCSF) will readily improve the performance of current fiber optic sensors in the harsh environment and potentially enable those that are limited by the optical property of unclad single crystal sapphire optical fiber (SCSF). / Ph. D.

This study aims to understand how beauty ideals that are formed in the Swedish society and implemented in clothing stores in the form of exclusionary fashion, affect and shape women's thinking about their appearance and life as well as how they approach and apply this to their social and private life. The target group of this study are women who are affected by the exclusionary fashion where there is a lack of diversity and inclusion for different sizes and culturally coded clothes, like hijabs in clothing stores. This study has thus had the following three questions: How do women who do not fit into the beauty ideal and the norm in terms of their body size and culturally coded clothes relate to clothing stores' exclusionary fashion?  What internalized self-image and self-esteem do those who are excluded because of their appearance have, and in what way do they deal with it?  How does it affect women's sense of belonging to society?  This study has been conducted with qualitative interviews supported by theories concerning stigma, the ideal, internalization of the ideal female body and habitus. The conclusions of this study have revealed that the beauty ideal not only affects the interviewed women physically but also mentally. It also affects both their social life with family and friends and their private life and how they view themselves and their weight in connection to it. This concludes to the beauty ideal having a strong and prominent presence in the interviewees' lives and their sense of belonging into society. Furthermore, the study concluded that the beauty ideal affected both the self-image and self-esteem of the women in this study and to be able to handle this the women had developed different strategies that they used to be able to live with the strain they felt from the impact of the beauty ideal. These strategies were viewed by the interviewees as a positive impact and was a sign of liberation for them. Despite having some form of positivity, the overall agreement for the interviewees was that their bodily and clothing differences from the norm society led to a feeling of being unwanted and to them alienating themselves from society because of it. This study shows that, for some women, a difference in appearance from the majority means a loss of integration and self-confidence in their everyday lives.

Bandwidth enhancement of low-profile omnidirectional, electrically-small antennas has evolved from the design and construction of AM transmitter towers eighty years ago to current market demand for battery-powered personal communication devices. Electrically-small antenna theory developed with well-known approximations for characterizing radiation properties of antenna structures that are fractions of the radiansphere. Current state-of-the-art wideband small antennas near kaH1 have achieved multiple-octave impedance bandwidths when utilizing volume-efficient designs. Significant advances in both the power and miniaturization of microelectronics have created a second possible approach to enhance bandwidth. Frequency agility, via switch tuning of reconfigurable structures, offers the possibility of the direct integration of high-speed electronics to the antenna structure. The potential result would provide a means to translate a narrow instantaneous bandwidth across a wider operating bandwidth. One objective of the research was to create a direct comparison of the passive- multi-resonant and active-reconfigurable approaches to enhance bandwidth. Typically, volume-efficient, wideband antennas are unattractive candidates for low-profile applications and conversely, active electronics integrated directly antenna elements continue to introduce problematic loss mechanisms at the proof-of-concept level The dissertation presents an analysis method for wide bandwidth self-resonant antennas that exist in the 0.5dkad1.0 range. The combined approach utilizes the quality factor extracted directly from impedance response data in addition to near-and-far field modal analyses. Examples from several classes of antennas investigated are presented with practical boundary conditions. The resultant radiation properties of these antenna-finite ground plane systems are characterized by an appreciable percentage of radiated power outside the lowest-order mode. Volume-efficient structures and non-omnidirectional radiation characteristics are generally not viable for portable devices. Several examples of passive structures, representing different antenna classes are investigated. A PIN diode, switch-tuned low-profile antenna prototype was also developed for the comparison which demonstrated excessive loss in the physical prototype. Lastly, a passive, low-profile multi-resonant antenna element with monopole radiation is introduced. The structure is an extension of the planar inverted-F antenna with the addition of a capacitance-coupled parasitic to enhance reliable operation in unknown environments. / Ph. D.

The principle of braking in road vehicles involves the conversion of kinetic energy into heat. This high energy conversion therefore demands an appropriate rate of heat dissipation if a reasonable temperature and performance stability are to be maintained. While the design, construction, and location features severely limit the heat dissipation function of the friction brake, electromagnetic brakes work in a relatively cool condition and avoid problems that friction brakes face by using a totally different working principle and installation location. By using the electromagnetic brake as supplementary retardation equipment, the friction brakes can be used less frequently and therefore practically never reach high temperatures. The brake linings thus have a longer life span, and the potential "brake fade" problem can be avoided. It is apparent that the electromagnetic brake is an essential complement to the safe braking of heavy vehicles. In this thesis, a new mathematical model for electromagnetic brakes is proposed to describe their static characteristics (angular speed versus brake torque). The performance of the new mathematical model is better than the other three models available in the literature in a least-square sense. Compared with old models that treat reluctance as a constant, our model treats reluctance as a function of speed. In this way, the model represents more precisely the aggregate effect of all side effects such as degree of saturation of the iron in the magnet, demagnetizing effects, and air gap. The software program written in Matlab can be used to code different brake characteristics (both static and dynamic) and evaluate their performance in different road scenarios. A controller is designed that achieves wheel-slip control for vehicle motion. The objective of this brake control system is to keep the wheel slip at an ideal value so that the tire can still generate lateral and steering forces as well as shorter stopping distances. In order to control the wheel slip, vehicle system dynamic equations are given in terms of wheel slip. The system shows the nonlinearities and uncertainties. Hence, a nonlinear control strategy based on sliding mode, which is a standard approach to tackle the parametric and modeling uncertainties of a nonlinear system, is chosen for slip control. Due to its robustness properties, the sliding mode controller can solve two major difficulties involved in the design of a braking control algorithm: 1) the vehicle system is highly nonlinear with time-varying parameters and uncertainties; 2) the performance of the system depends strongly on the knowledge of the tire/road surface condition. A nominal vehicle system model is simulated in software and a sliding mode controller is designed to maintain the wheel slip at a given value. The brake control system has desired performance in the simulation. It can be proven from this study that the electromagnetic brake is effective supplementary retardation equipment. The application and control of electromagnetic brakes might be integrated with the design of vehicles and their friction braking systems so that an ideal match of the complementary benefits of both systems might be obtained to increase safety to a maximum while reducing vehicle operating costs to a minimum. / Master of Science

The effect of major or minor mode in music on the free recall of materials presented in a multimedia setting was investigated. Seventy-seven students from Virginia Polytechnic Institute and State University voluntarily participated in the experiment. The experiment consisted of three Hypercard stacks, identical except for the introduction where participants heard either a major or a minor melody line or no music. Participants read an identical text passage and recalled as much information as they could about the passage afterwards. The results showed no significant difference between groups. / Master of Arts

In the past, radial-mode piezoelectric transformer (Transoner) design has been difficult due to the complex interaction between the physical and electrical circuit characteristics. Prior to a design procedure, experimental design by Face Electronics, LC led to a sample that could fit a ballast application enabling zero voltage switching (ZVS) for the semiconductors without the use of any external inductance. In the ballast circuit, the piezoelectric transformer is used to replace the conventional inductor-capacitor resonant tank saving valuable space and expense. With ballast in mind, a design process has been developed in this thesis to optimize radial mode transformers to fit specifically tailored applications. The graphical process described, allows the engineer to design in the capability of zero voltage switching for a half-bridge drive while simultaneously providing highly efficient performance. The problem of mounting a piezoelectric transformer to a circuit board has also been addressed in this thesis. A thermally conductive mounting technique has been developed which can enhance both the power capability and reliability of circuits utilizing these devices. / Master of Science

TRANSIMS is a disaggregate, behavioral transportation planning package developed under US DOT's and EPA funding at the Los Alamos National Laboratory (LANL). It is an integrated system of travel forecasting models designed to give transportation planners accurate, complete information on traffic impacts, congestion, and pollution by simulating second-by-second movements of every person and every vehicle through the transportation network of a large metropolitan area. There is no built-in module for travellers' mode choices In TRANSIMS. The modes going with the shortest path are always taken. In Portland Study, a mode choice methodology implemented by a series of feedback processes is proposed. However, it uses aggregate, deterministic mode choice model. There is little solid theoretic ground for the format and coefficients of the generalized costs used in the calibration process. The accessibility to a mode, especially to Transit, was also not included in the model. In the thesis, a disaggregate and deterministic mode choice methodology in TRANSIMS is developed. The accessibility to each mode is analyzed and included in the model. The methodology is then implemented on the Blacksburg transportation planning study, namely Blacksburg_Lite. The analysis of the result is based on the indicator of mode choice, mode split between Transit and Auto. The indicator is close to that in survey data and converged fast. Therefore, this mode choice methodology could be used within TRANSIMS framework. / Master of Science

Blod består av olika komponenter; erytrocyter, trombocyter, leukocyter och plasma.Plasma är en proteinrik vätska som bland annat innehåller koagulationsfaktorer. Vidberedning av donerat helblod kan dessa blodkomponenter separeras från varandra,för att sedan bearbetas vidare och-, eller användas för komponenten relevantaändamål. Plasma kan användas till transfusion vid bland annatkoagulationsrubbningar, alternativt användas som råvara förläkemedelsframställning. För att säkerställa kvaliteten på framställd plasma utförskomponentkontroller, som säkerställer att framställningsprocesser leder till önskvärtresultat. Plasma kontrolleras för innehåll av erytrocyter, trombocyter och leukocyter.Olika analysmetoder kan användas för detta, där BD Plasma Count Kit i dagslägetanvänds för att bestämma leukocytpartikelkoncentration (LPK),trombocytpartikelkoncentration (TPK) och erytrocytpartikelkoncentration (EPK).Sysmex XN Blood Bank mode (BB-mode) är en mjukvara som möjliggör analys avkomponentkontroller, och är i jämförelse en mindre resurskrävande (personal, tid,ekonomi) metod. Syftet med arbetet var därför att utvärdera denna metod;undersöka preanalytiska faktorer, verifiera provstabilitet och jämföra mednuvarande metod (BD Plasma Count Kit). Totalt 50 plasmakontroller analyseradesmed båda metoderna, till två av dessa kontroller tillsattes leukocyter.Reproducerbarhet för BB-mode mättes vid normal nivå och högre nivå, provernaanalyserades 10 gånger på varandra följda mätningar. Regressionsanalys förnuvarande metod och BB-mode utfördes för LPK, TPK och EPK. Svag korrelationförelåg för LPK (R2=0,8232), god korrelation för TPK (R2=0,9648) och dåligkorrelation för EPK (R2=0,5211). Analys av komponentkontroller (LPK, TPK ochEPK) med BB-mode gav inte samma resultat som BD Plasma Count Kit(signifikansnivå 0,05). BB-mode visar potential till förenklad analys avkomponentkontroller för plasma, men fler studier krävs. / Blood can be divided into different components: erythrocytes, thrombocytes,leucocytes, and plasma. Plasma is a fluid with proteins suspended in it. Some ofthese proteins Is coagulation factors, which makes plasma a viable treatment optionfor coagulation disorders. It could also be used for pharmaceutical production,where said coagulation factors is the main target. Quality controls (QC) of theproduced plasma ensure that the processes lead to the desired results. Residual cellsin plasma are used, and concentrations of erythrocytes, thrombocytes and leucocytesis measured in plasma. BD Plasma Count Kit is the method used today, but a newaddition to the haematology analysers Sysmex XN-series called Sysmex XN BloodBank mode (BB-mode) aims to analyse QC for blood products. The method wouldbe less resource consuming (time, personnel, economy) than the method used today.Therefore, the aim of this study is to evaluate analysis of quality controls for plasmaon BB-mode. This includes a comparison with BD Plasma Count Kit, as well asinvestigation of pre-analytical factors. A total of 50 samples were comparedbetween the methods, two of which were leucocyte spiked. Regression analysisshowed weak correlation between the methods for leucocyte concentration(R2=0,8232), good correlation for thrombocyte concentration (R2=0,9648), and poorcorrelation for erythrocyte concentration (R2=0,5211). However, the methods didnot show the same results for neither of the parameters (significance 0,05). BBmodeshow potential to use for QC on plasma, but further testing is needed.

Common mode (CM) electromagnetic interference (EMI) can compromise electronics systems, interfere with communication systems, and degrade mechanical systems. Multiple inverters can also generate excessive CM EMI that often exceeds individual inverter EMI standards. Due to their weight, volume, cost, and suboptimal performance, active and passive filters and chokes are inefficient as EMI mitigation options. By utilizing frequency modulation (FM) or spread spectrum frequency modulation (SSFM), EMI energy is dispersed. In spite of not requiring expensive, bulky, and heavy filters, these techniques produce significant ripples in output voltages and currents. This dissertation uses enhanced sinusoidal frequency modulation to reduce CM EMI output, bridging the gap between existing EMI solutions: 1) To reduce performance degradation, a state-of-the-art FM topology with duty cycle correction is proposed. Due to large output voltage and current ripples, FM techniques have limited bandwidth and utilization. Duty cycle correction allows for a wider FM bandwidth with better EMI attenuation while minimizing output ripple performance tradeoffs. 2) CM EMI accumulation is a growing concern in power converter networks. Even if each converter complies with EMI regulations, multiple converters may produce CM EMI that exceeds EMI standards in parallel operation. A novel algorithm is proposed to suppress CM EMI in a large-scale network using SFMCW frequency indexing. The algorithm minimizes aggregate EMI by minimizing switching frequency overlap among converters. 3) CM EMI noise in complex systems presents a critical challenge. Since standalone converters are rarely affected by CM EMI phases, they were usually overlooked in most studies until recently. CM currents generated by multiple converters can be added or subtracted based on phase differences. The CM currents in large systems with multiple inverters are distributed randomly, resulting in multiple peaks and nulls. In order to reduce network EMI, a sinusoidal FM technique with phase shift is proposed to attenuate CM EMI on multiple parallel inverters. This method overcomes conventional methods' critical disadvantages, including the need for accurate component characterization and modeling, and reducing CM EMI without additional passive components.

No / A sinusoidal grating can be viewed as a series of light and dark bars. Here we measure the contrast discrimination thresholds for light and dark bars individually, and find that the contrast discrimination thresholds for the whole sinusoid can be explained as ideal summation of the light and dark bar thresholds. We propose a model for light bar, dark bar, and sinusoidal contrast discrimination which involves local light adaptation and multiplicative noise. The model accounts for the data very well, and also accounts for contrast discrimination of light and dark edges.