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This case study is an investigation into the ways a powerful professional education organization, the National Association for the Education of Young Children (NAEYC), historically constructed and promoted pedagogical discourses about social identities, social problems, and social change. The purpose of the study was to critically analyze a dominant early childhood pedagogical discourse that is constituted by public position statements published by the NAEYC between 1991 and 2014. Using a critical, intersectional, and sustainable framework, this study revealed a complex, detailed narrative of the ways the NAEYC position statements constructed images of social identities and social groups in relation to social issues relevant to early childhood education practice and policy, particularly those that the NAEYC identified as eliciting “controversial or critical opinions” for the purposes of “promoting broad-based dialogue on these issues” (naeyc.org). This study worked to reveal the ways that the NAEYC position statements promoted harmful discourses about historically and multiply minoritized social identity groups and supremacist discourses about white and affluent children. This study also emphasized the significance of positionality and reflexivity in educational research about equity, justice, and sustainability for recognizing the potential for both harm and healing throughout the research process. The findings of the study highlight the need for layers of reflexivity at the institutional level, the disruption of deficit narratives in education, and the need for re-mediation of traditional signifiers of quality and professional development in the early childhood profession.

Switched reluctance motors (SRMs) are promising candidates for electric vehicles due to lower manufacturing costs, higher efficiency, and robustness operation in a harsh envi-ronment. For accurate control of the SRM, the real-time rotor position is needed for phase computation. To obtain position information, position-sensorless control techniques have been developed to take the role of position sensors in commercial SRM drives for cost reduction or sensor-fault tolerance capability. Nowadays, the position-sensorless control of SRMs still suffers from a technical problem: the dependence on magnetic characteris-tics. Existing position estimation algorithms often require time-consuming offline meas-urement of magnetic parameters, limiting the broad applications due to the low generality. It is therefore of great significance to develop universal position-sensorless control tech-niques with less magnetic parameter dependence. Zero- and low-speed position-sensorless control of the SRM needs high-frequency in-jection into the idle phase to measure the stator inductance. Rotor position is often esti-mated from the prestored inductance lookup table but is replaced by a new regional phase-locked loop (RPLL) with a self-commissioning process in this thesis. The modeling of the unsaturated stator inductance can be established automatically via the pulse voltage injection at the initial stage without offline testing. The RPLL embedded with a three-phase heterodyne design can estimate the full-cycle rotor position from the idle-phase in-ductance based on the unsaturated inductance model. The proposed low-speed position estimator can also realize robust sensorless control in four-quadrant operation and magnet-ic saturation conditions without complicated magnetic characteristics. Besides, local sta-bility of the position estimator is proved, and an optimized parameter design scheme is given. Although pulse voltage injection offers accurate position estimation in low-speed op-eration, the induced pulse current results in additional copper loss and torque ripples. This problem is overcome in the thesis by regulating the magnitude of induced current at a minimal level. The induced current regulator is designed as a terminal sliding-mode con-troller that adjusts the injection voltage online over the whole idle-phase period. Proper control parameter selection based on the convergence analysis and stability proof ensures robust control performance against parameter uncertainties. The proposed pulse injection scheme combined with the RPLL can guarantee accurate position estimation while reduc-ing copper losses and torque ripples significantly. Due to the shortened idle-phase duration when the rotor speed increases, pulse injec-tion methods are infeasible for high-speed position estimation. To solve the problem, this thesis proposes a nonlinear observer based on feature position estimation in conduction phases for high-speed sensorless control. A self-commissioning method is adopted to cap-ture a two-dimensional flux linkage curve at a feature position, which avoids offline measurement of the complete three-dimensional characteristics. However, the estimated feature position has low resolution, and its estimation accuracy is degraded by nonideal flux linkage errors. To improve the sensorless control performance, a nonlinear state ob-server using online Fourier series is then designed to eliminate disturbances in position es-timation. Parameter design based on a small-signal analysis is also given to guarantee ac-curate position and speed estimation. High-speed position-sensorless control is further simplified using a new quadrature flux estimator without using any flux linkage characteristics. The method requires neither offline measurement nor online self-commissioning. This advantage is realized by adopt-ing a speed-adaptive bandpass filter to extract the fundamental flux linkage. A three-phase phase-locked loop is then used to estimate the rotor position from the orthogonal flux linkage signals without a priori knowledge of the SRM magnetic characteristics. The magnetic-parameter-free position estimation can facilitate the application of sensorless control in a general-purpose SRM converter. A wide-speed range position estimation scheme is realized by combining both the low-speed and high-speed position estimation approaches. Consequently, a universal posi-tion-sensorless control scheme is proposed in the thesis, covering the full-speed range and not requiring offline measurement effort. The proposed position estimation schemes are verified on a 5.5 kW 12/8 SRM test bench. / Thesis / Doctor of Philosophy (PhD)

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This paper presents a decision theory model of the perceptual processes by which an observer compares two visual stimuli presented at different points in time and at different locations in the visual field. The model specifies how information about the first stimulus is lost during the interstimulus delay and over the spatial translation required for the comparison. Emphasis is placed on the manner in which the effect of temporal separation combines with the effect of spatial separation in determining the observer's sensitivity. Two experiments are reported. The observer was required to discriminate a difference in vertical position between two laterally separated points of light presented successively in the dark. The progressive loss in sensitivity with increasing temporal and spatial separations is consistent with the predictions of the model. / Thesis / Doctor of Philosophy (PhD)

Research on eye movement control during first language (L1) reading has long since established that (i) words are read most efficiently when the first saccade into the word lands near its center, (ii) words are refixated more often when landing positions deviate from the center of the word, and (iii) relatively proficient readers' saccades land closer to this center position. Eye-tracking studies of second language (L2) reading tend to compare participant groups based on their language background (L1 vs L2) rather than L2 proficiency. As of yet, there has been no comparison of these approaches. This study reports a comparative analysis of the Multilingual Eye-movement COrpus (MECO), which contains data on English text reading and its component skills from 543 participants representing 12 different L1s. Analyses of the distributions of initial landing positions and refixation probabilities establish that the gradient measure of proficiency in English (as L1 or L2) has a greater explanatory power than categorical contrasts between language backgrounds. We also found that English proficiency has a gradient effect on efficiency of saccadic targeting: more proficient readers landed their initial saccades closer to the word's center. However, more proficient readers of English were also less accurate in their saccadic targeting, showing greater dispersion of initial landing positions. We link this puzzling finding to the observation that landing in a suboptimal position comes with a much higher processing cost (refixation probability) for less proficient readers. This study discusses theoretical and methodological implications of the novel findings for reading research. / Thesis / Master of Science (MSc) / When we read text, we do not continuously move our eyes across it, but we make a series of rapid eye fixations on different parts of the text. Scientists know that if we fixate our eyes on a center of a word rather than on its beginning or end, we will understand that word the fastest. Highly skilled readers make the first fixation on any word in a more optimal place compared to less skilled readers. Making such optimal fixations allows highly skilled readers to understand each word they encounter faster, which makes them better readers and leads to more successful outcomes later in life. In this research project we were interested in how reader's proficiency in reading related skills affects the efficiency of their eye-movements during reading English as a first and second language. The results found that more proficient readers were found to have a lighter penalty to the speed of their reading when fixating their eyes farther away from the optimal position in words. Additionally, the results demonstrated that proficiency in reading related skills is a better indicator of the efficient eye-movement behavior than native language of the reader.

The stability and maneuverability of aircraft are some key factors for selecting the locations of wings or canards on the fuselage. Another important variable that is considered in the design of an aircraft is drag force which impacts fuel efficiency. This research investigates how drag force of a surrogate aircraft is affected by the placement of the wing or canard along the fuselage. Unique for this study is the placement of the canard in the fuselage nose region, with the leading edge upstream of the nose, resembling the shape of a hammerhead shark's head. When the leading edge of all considered wing configurations was located 20% or more from the fuselage nose, the platforms produced the least amount of drag force. When the wing was placed in the nose region of the fuselage, the wings with small chords produced less drag when their leading edge was ahead of the nose.

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Impulse-based Ultrawideband (UWB) is a form of signaling which uses streams of pulses of very short duration, typically on the order of a nanosecond. Impulse-based UWB systems possess the ability to fuse accurate position-location with low-data rate communication, and provide covertness for tactical applications and robustness in dense multipath propagation environments. These features can be leveraged in the design wireless ad hoc position-location networks (PoLoNets) for accurate location tracking and monitoring where GPS is not available, especially indoors. Location information is sequentially propagated through a network of reference nodes in order to create a framework for the tracking of mobile nodes, as well as a multi-hop message-passing infrastructure between mobile nodes and control nodes located outside the area of deployment. The applications of such networks include the location and command-and-control of fire-fighters in emergency scenarios, the location of military personnel deployed in urban or indoor environments, and the guidance of robots through large multi-room indoor environments. The main objective of this dissertation is to derive design principles, techniques and analytical models for UWB PoLoNets that are useful in the development of practical solutions. Some of the fundamental obstacles to obtaining accurate location information in indoor environments are non-line-of-sight (NLOS) signal propagation, limited connectivity between nodes, and the propagation of localization inaccuracies when using sequential estimation approaches in ad hoc scenarios. Several techniques and algorithms that mitigate these effects, thereby allowing the design of PoLoNets with requisite localization accuracy, are presented. Although these techniques are developed from the perspective of a UWB physical layer, the majority are applicable to generic PoLoNets. / Ph. D.