Industrial demands for higher productivity rates and more stringent part tolerances require faster production machines that can produce, assemble, or manipulate parts at higher speeds and with better accuracy than ever before. In a majority of production machines, such as machine tools, ball screw drives are used as the primary motion delivery mechanism due to their reasonably high accuracy, high mechanical stiffness, and low cost. This brings the motivation for the research in this thesis, which has been to develop new control techniques that can achieve high bandwidths near the structural frequencies of ball screw drives, and also compensate for various imperfections in their motion delivery, so that better tool positioning accuracy can be achieved at high speeds. A precision ball screw drive has been designed and built for this study. Detailed dynamic modeling and identification has been performed, considering rigid body dynamics, nonlinear friction, torque ripples, axial and torsional vibrations, lead errors, and elastic deformations. Adaptive Sliding Mode Controller (ASMC) is designed based on the rigid body dynamics and notch filters are used to attenuate the effect of structural resonances. Feedforward friction compensation is also added to improve the tracking accuracy at velocity reversals. A bandwidth of 223 Hz was achieved while controlling the rotational motion of the ball screw, leading to a servo error equivalent to 1.6 um of translational motion. The motor and mechanical torque ripples were also modeled and compensated in the control law. This improved the motion smoothness and accuracy, especially at low speeds and low control bandwidths. The performance improvement was also noticeable when higher speeds and control bandwidths were used. By adding on the torque ripple compensation, the rotational tracking accuracy was improved to 0.95 um while executing feed motions with 1 m/sec velocity and 1 g acceleration. As one of the main contributions in this thesis, the dynamics of the 1st axial mode (at 132 Hz) were actively compensated using ASMC, which resulted in a command tracking bandwidth of 208 Hz. The mode compensating ASMC (MC-ASMC) was also shown to improve the dynamic stiffness of the drive system, around the axial resonance, by injecting additional damping at this mode. After compensating for the lead errors as well, a translational tracking accuracy of 2.6 um was realized while executing 1 m/sec feed motions with 0.5 g acceleration transients. In terms of bandwidth, speed, and accuracy, these results surpass the performance of most ball screw driven machine tools by 4-5 times. As the second main contribution in this thesis, the elastic deformations (ED) of the ball screw drive were modeled and compensated using a robust strategy. The robustness originates from using the real-time feedback control signal to monitor the effect of any potential perturbations on the load side, such as mass variations or cutting forces, which can lead to additional elastic deformations. In experimental results, it is shown that this compensation scheme can accurately estimate and correct for the elastic deformation, even when there is 130% variation in the translating table mass. The ED compensation strategy has resulted in 4.1 um of translational accuracy while executing at 1 m/sec feed motion with 0.5 g acceleration transients, without using a linear encoder. This result is especially significant for low-cost CNC (Computer Numerically Controlled) machine tools that have only rotary encoders on their motors. Such machines can benefit from the significant accuracy improvement provided by this compensation scheme, without the need for an additional linear encoder.

The current study sought to prospectively explore the potential main effects and interactive relations among drive for thinness, life event stress, and harm avoidance in the prediction of disordered eating in an ethnically diverse sample of women (N = 58). During the initial and follow-up assessments, standardized questionnaires were utilized to assess drive for thinness, life event stress, and a harm avoidant temperament. Additionally, semi-structured diagnostic interviews were administered to assess disordered eating. Results revealed a significant interaction between drive for thinness and life event stress in the prediction of eating pathology. Neither the two-way life event stress x harm avoidance interaction nor the three-way drive for thinness x life event stress x harm avoidance interaction were significant predictors of eating pathology. These findings suggest that the previously suggested relation between drive for thinness and pathological eating is dependent upon the degree of life event stress experienced.

This study examined relationships among self-esteem, media internalization, sexual orientation, and ethnicity in predicting drive for muscularity in a diverse group of men (N = 217) who work out in gyms. Investigations examined media internalization and sexual orientation as moderators of the relationship between self-esteem and drive for muscularity. Additional analyses examined media internalization as a moderator of the relationships between a) sexual orientation and drive for muscularity and b) ethnicity and drive for muscularity. Standardized questionnaires were utilized to assess drive for muscularity, media internalization, self-esteem, sexual orientation, and ethnicity. While lower self-esteem predicted greater drive for muscularity, neither media internalization nor sexual orientation were significant moderators of this relationship. However, media internalization mediated the relationships between sexual orientation and drive for muscularity and between ethnicity and drive for muscularity. Findings suggest that the internalization of ideal muscularized images explain demographic differences in the drive to be more muscular.

This thesis looked at three encryption applications that all use the symmetric encryption algorithms AES, Twofish and Serpent but differ in their implementation and how this difference would illustrate itself in performance benchmarks depending on the type of storage device that they were used on. Three mechanical hard drives and one solid state drive were used in the performance benchmarks which measured a variety of different disk operations across the three encryption applications and their algorithms. From the benchmarks performance charts were produced which showed that DiskCryptor had the best performance when using a solid state drive and that TrueCrypt had the best performance when using mechanical hard drives. By choosing DiskCryptor as the encryption application when using a solid state drive a performance increase of 38.9% compared to BestCrypt and 28.4% compared to TrueCrypt was achieve when using the AES algorithm. It was also shown that Twofish was overall the best performing algorithm. The primary conclusion that can be drawn from this thesis is that it is important to choose the right encryption application depending on the type of storage device used in order to get the best performance possible.

Industrial demands for higher productivity rates and more stringent part tolerances require faster production machines that can produce, assemble, or manipulate parts at higher speeds and with better accuracy than ever before. In a majority of production machines, such as machine tools, ball screw drives are used as the primary motion delivery mechanism due to their reasonably high accuracy, high mechanical stiffness, and low cost. This brings the motivation for the research in this thesis, which has been to develop new control techniques that can achieve high bandwidths near the structural frequencies of ball screw drives, and also compensate for various imperfections in their motion delivery, so that better tool positioning accuracy can be achieved at high speeds. A precision ball screw drive has been designed and built for this study. Detailed dynamic modeling and identification has been performed, considering rigid body dynamics, nonlinear friction, torque ripples, axial and torsional vibrations, lead errors, and elastic deformations. Adaptive Sliding Mode Controller (ASMC) is designed based on the rigid body dynamics and notch filters are used to attenuate the effect of structural resonances. Feedforward friction compensation is also added to improve the tracking accuracy at velocity reversals. A bandwidth of 223 Hz was achieved while controlling the rotational motion of the ball screw, leading to a servo error equivalent to 1.6 um of translational motion. The motor and mechanical torque ripples were also modeled and compensated in the control law. This improved the motion smoothness and accuracy, especially at low speeds and low control bandwidths. The performance improvement was also noticeable when higher speeds and control bandwidths were used. By adding on the torque ripple compensation, the rotational tracking accuracy was improved to 0.95 um while executing feed motions with 1 m/sec velocity and 1 g acceleration. As one of the main contributions in this thesis, the dynamics of the 1st axial mode (at 132 Hz) were actively compensated using ASMC, which resulted in a command tracking bandwidth of 208 Hz. The mode compensating ASMC (MC-ASMC) was also shown to improve the dynamic stiffness of the drive system, around the axial resonance, by injecting additional damping at this mode. After compensating for the lead errors as well, a translational tracking accuracy of 2.6 um was realized while executing 1 m/sec feed motions with 0.5 g acceleration transients. In terms of bandwidth, speed, and accuracy, these results surpass the performance of most ball screw driven machine tools by 4-5 times. As the second main contribution in this thesis, the elastic deformations (ED) of the ball screw drive were modeled and compensated using a robust strategy. The robustness originates from using the real-time feedback control signal to monitor the effect of any potential perturbations on the load side, such as mass variations or cutting forces, which can lead to additional elastic deformations. In experimental results, it is shown that this compensation scheme can accurately estimate and correct for the elastic deformation, even when there is 130% variation in the translating table mass. The ED compensation strategy has resulted in 4.1 um of translational accuracy while executing at 1 m/sec feed motion with 0.5 g acceleration transients, without using a linear encoder. This result is especially significant for low-cost CNC (Computer Numerically Controlled) machine tools that have only rotary encoders on their motors. Such machines can benefit from the significant accuracy improvement provided by this compensation scheme, without the need for an additional linear encoder.

IEEE 802.11 PHY supports multiple transmission rates according to multiple different modulations and coding schemes. Each WiFi station selects its own transmission rate according to its own algorithm; in particular, the IEEE 802.11 standards do not specify the bit-rate selection method. Although many adaptive bit-rate selection algorithms have been proposed, there is limited research and evaluation on the performance of such algorithms for roadside networks, especially in cases with multi-vehicle roadside multi-vehicular WiFi networks. In this thesis we propose an opportunistic highest bit-rate algorithm, Opportunistic Highest Bit-Rate Multi-Vehicular WiFi Networks (OHBR-MVN), specifically for roadside multi-vehicular WiFi networks. Our proposal is based on three key characteristics of such networks: (1) vehicles will drive closer to, and eventually pass, the roadside WiFi station, experiencing a progressively better transmission environment; (2) the vast majority of data transmitted in single-vehicle drive-by downloading scenarios occurs at the maximum transmission rate; (3) vehicles that transmit at less than the maximum rate do so at the expense of those that could send more data at a higher transmission rate. We therefore believe that transmitting only at the highest possible bit-rate is the preferred algorithm for such networks. Further, this approach keeps the bit-rate selection extremely simple, avoiding the complexity and resulting problems of adaptive approaches. Through a series of experiments that compare the throughput of both fixed and adaptive bit-rate selection algorithms we show that our approach yields both higher throughput and better fairness characteristics, while being significantly simple, and thus more robust.

Over the past decade, the study of male body image has increased considerably and substantial levels of body discontent among males have been reported. Accompanying this dissatisfaction is a rise in the documentation of the Drive for Muscularity (DFM), or the desire for increased lean muscle mass, in men. The current study had three objectives. The first was to identify theoretical variables associated with the DFM. The second was to examine body image evaluation and investment in relation to the DFM. The third was to explore the DFM and psychological well-being. Two-hundred fourteen men completed the study and multiple regressions were carried out to examine the various relations. Awareness and internalization of the male body ideal and universalistic social comparison accounted for 35% of the variance in the DFM. Body image investment, but not evaluation, accounted for 26% of the variance in the DFM. Regarding psychological well-being, the DFM accounted for an additional 23% of the variance in muscle pathology after controlling for levels of depression and self-esteem. Other notable findings included mens self-reported intentions to use potentially unhealthy body change strategies to increase size and musculature in the future, and statistically significant associations between the DFM and self-esteem, social physique anxiety, and general worry. These results contribute to the growing literature on male body image and the implications for clinical practice with men presenting with body dissatisfaction are discussed.

<p>Speciation has occurred countless times throughout history, and yet the genetic mechanisms that lead to speciation are still missing pieces. Here, we describe the genetics of two processes that can act alone or together to cause speciation: hybrid sterility and meiotic drive. We use the <italic>Drosophila pseudoobscura/D, persimilis</italic> species as a model system to study these processes. We expanded on a prior study and saw little variation in strength of previously known hybrid sterility alleles between distinct strains of <italic>D. persimilis</italic> and the Bogota subspecies of <italic>D. pseudoobscura</italic>. Introgression of an autosomal, noninverted hybrid sterility allele from the USA subspecies of <italic>D. pseudoobscura</italic> into <italic>D. persimilis</italic> demonstrated that the <italic>D. pseudoobscura</italic> copy of a <italic>D. persimilis</italic> hybrid sterility factor also causes hybrid male sterility in a <italic>D. pseudoobscura bogotana</italic> background. This allelism suggests that the introgressed allele is ancestral, but was lost in the Bogota lineage, or that gene flow between <italic>D. pseudoobscura</italic> USA and <italic>D. persimilis</italic> moved the sterility-conferring allele from <italic>D. persimilis</italic> into <italic>D. pseudoobscura</italic>. To further understand the genetic basis of speciation, we asked if meiotic drive in <italic>D. persimilis</italic> is associated with hybrid sterility seen in <italic>D. persimilis/D. pseudoobscura</italic> hybrids. QTL mapping of both traits along the right arm of the X chromosome, where both drive and hybrid sterility loci are found, suggest that some of the causal loci overlap and may be allelic.</p> / Dissertation

The transformation of Joint forces to be lighter, more lethal, and capable of deploying from multiple dispersed locations free of prepared landing zones requires a dedicated heavy lift VTOL aircraft capable of rapidly delivering large payloads, such as the 20 to 26 ton Future Combat System, at extended ranges in demanding terrain and environmental conditions. Current estimates for a single main rotor configuration place the design weight over 130,000 pounds with an installed power of approximately 30,000 horsepower. Helicopter drive systems capable of delivering torque of this magnitude succeeded in the Russian Mi-26 helicopters split-torque design and the Boeing VERTOL Heavy Lift Helicopter (HLH) prototypes traditional multi-stage planetary design. The square-cube law and historical trends show that the transmission stage weight varies approximately as the two-thirds power of torque; hence, as the size and weight of the vehicle grows, the transmissions weight becomes an ever-increasing portion of total gross weight. At this scale, optimal gearbox configuration and component design holds great potential to save significant weight and reduce the required installed power. The drive system design methodology creates a set of integrated tools to estimate system weight and rapidly model the preliminary design of drives system components. Tools are provided for gearbox weight estimation and efficiency, gearing, shafting, and cooling. Within the same architecture, the designer may add similar tools to model subcomponents such as support bearings, gearbox housing, freewheeling units, and rotor brakes. Measuring the relationships between key design variables and system performance metrics reveals insight into the performance and behavior of a heavy lift drive system. A parametric study of select design variables is accomplished through an intelligent Design of Experiments that utilizes Response Surface Methodology to build a multivariate regression weight model. The model permits visualization of the design space and assists in optimization of the drive system preliminary design. This methodology is applied to both the Boeing HLH and the Russian Mi-26 main gearboxes. This study applies the drive system design methodology to compare the Mi-26 split-torque gearbox over the Boeing HLH multi-stage planetary gearbox in a single main rotor heavy lift helicopter.

A method to find solutions to multi-objective design problems that involve poor information available was proposed. The method quantified the designers intuition in a systematic manner, and utilized it to approximate inaccurate and/or vague numbers. In the context of possibility theory, uncertain values were expressed through possibility distributions, i.e. fuzzy membership functions. Based on the membership functions of the value, levels of confidence of the solutions to multi-objective problems were defined through the notions of possibility and necessity. An evolutionary algorithm was modified to find sets of solutions that allow certain levels of confidence instead of the crisp sets of the solutions. The method was applied to a design problem of the gyrodyne configuration and sets of the solutions of the specified possibility and necessity were found. The results of the design problem and the suggestions for future research were discussed.