Micromachined in-plane acoustic pressure gradient sensors

textThis work presents the fabrication, modeling, and characterization of two first-generation acoustic in-plane pressure gradient sensors. The first is a micromachined piezoelectric microphone. The microphone structure consists of a semi-rigid beam structure that rotates about torsional pivots in response to in-plane pressure gradients across the length of the beam. The rotation of the beam structure is transduced by piezoelectric cantilevers, which deflect when the beam structure rotates. Sensors with both 10 and 20-μm-thick beam structures are presented. An analytical model and multi-mode, multi-port network model utilizing finite-element analysis for parameter extraction are presented and compared to acoustic sensitivity measurements. Directivity measurements are interpreted in terms of the multi-mode model. A noise model for the sensor and readout electronics is presented and compared to measurements. The second sensor is a capacitive sensor which is comprised of two vacuum-sealed, pistons coupled to each other by a pivoting beam. The use of a pivoting beam can, in principle, enable high rotational compliance to in-plane small-signal acoustic pressure gradients, while resisting piston collapse against large background atmospheric pressure. A design path towards vacuum-sealed, surface micromachined broadband microphones is a motivation to explore the sensor concept. Fabrication of surface micromachined prototypes is presented, followed by finite element modeling and experimental confirmation of successful vacuum-sealing. Dynamic frequency response measurements are obtained using broadband electrostatic actuation and confirm a first fundamental rocking mode near 250 kHz. Successful reception of airborne ultrasound in air at 130 kHz is also demonstrated, and followed by a discussion of design paths toward improve signal-to-noise ratio beyond that of the initial prototypes presented. A method of localizing sound sources is demonstrated using the piezoelectric sensor. The localization method utilizes the multiple-port nature of the sensor to simultaneously extract the pressure gradient and pressure magnitude components of the incoming acoustic signal. An algorithm for calculating the sound source location from the pressure gradient and pressure magnitude measurement is developed. The method is verified by acoustic measurements performed at 2 kHz.Electrical and Computer Engineerin

Evaluation of safety-oriented two-version architectures

A Markov model taking into account physical and design faults for a two-version architecture oriented to safety-related applications is developed. Only a probabilistic knowledge of the initial state of the versions in relation to the presence of design faults is assumed. The model can be split into two submodels accounting separately for physical and design faults, and a closed form expression for the unsafety of the system is obtained. The parameter estimation problem is discussed and a method to predict the probability distribution of the number of related design faults at the beginning of the operational life of the system is proposed. The method uses a pool model to process fault-occurrence data collected during a “face-to-face” debugging of the two versions. It has by nature a limited capability for proving version diversity, but it is shown that the limit is of the order of the diversity reported by recent experiments on real software. Finally, the impact of version correction during operation is shown to be negligible for critical applications.Postprint (author’s final draft

Teaching as Analogous Personalization: A pragmatic inquiry into expert teachers' process for fostering synchrony in educational dialogs, in post-secondary writing

Descriptive understandings of what human learning is, and so normative expectations of what teachers can and should do as educational leaders, has shifted greatly in society over the past century. The learning metaphors have moved from mechanical transfer to organic transformation; the educational approaches have moved from behavioral response-training to social-emotional facilitating: encouraging students not merely to repeat experts but to think like members in those knowledge-based communities, not merely to mimic disciplines' methods but to participate personally in the ongoing discourse of those fields. In an immediate sense, this shift is progress. Yet, in a larger sense, it is merely cycling back to acknowledge an old and persistent thread of practical wisdom among educators: that people learn complexly as emotional-social-intellectual creatures, and so that a teacher's work is to entice interest and effort, to foster a sense of belonging and trust, and to persuade students toward personally connecting with and valuing those same integral parts of a subject-matter that the teacher has already beneficially personalized for themselves. This longstanding rhetorical and pragmatic view of a teacher's educational role is now being supported directly by empirical research that shows the sense-bound, neurologically integrated, socially attuned, identity-and-meaning motivated character of human feelings, thoughts, and dispositions. I introduce the term “analogous personalization” to capture this synthetic (experience-based, scientifically supported) understanding of teaching as complexly social-emotional, intellectual, persuasive work. I then focus on educational dialogs—specifically within post-secondary writing-based courses—as a means of exploring how expert teachers foster synchrony between their own and their students' personal connections to (i.e., emotional inclination toward, social affiliation with, intellectual/practical understanding of) subject-matter. First, this dissertation offers a synthetic overview of some emergent mind-brain-body findings, and points out the fundamental educational realities that those findings substantiate. On that foundation, it next overviews insights from the field of rhetoric-and-writing about how teachers can usefully conceptualize the learner-knowledge-environment relationship from a dialogic perspective, to achieve effective (intentional, situated, synchronous) educational exchanges. Building from those scientific and practical literatures, it offers a flexible research method for studying the pragmatic arc of an educational exchange (from teacher intention to student take-away): by using the teacher's own personal, practical, principled framework of educational ideals and approaches; comparing their stated intentions with students' stated learning experiences, and tracing the arc of that educational dialog through actual classroom recordings. Finally, it enlists this radically situated research method to analyze three expert university writing teachers' practices: their idiosyncratic understandings of a teacher's role (from their own perspective); their experience-based manner of forming learning-centered relationships with students (from my observing perspective); and their apparent, persuasive self-investment in the course's subject-matter and the students' learning (from students' perspectives). It concludes with observations about the role of a teacher's sincerity (both practiced and perceived) in developing professional expertise and achieving synchrony with students in educational exchanges

Acoustic sensor

A method of designing and manufacturing an acoustic sensor having a high degree of directivity is disclosed. The sensor includes a rotatable plate that is attached to a substrate with mounts. In one aspect the mounts are freely rotatable and the torque on the plate is measured using detectors disposed on springs that provide a resistance to rotation of the plate. In another aspect the plate is mounted to the substrate with mounts that torsionally deform during rotation of the plate. These detectors measure the torque on the plate according to the torsional deformation of the mounts. Methods of improving the signal to noise ratio of acoustic sensors having multiple detectors are also disclosed.Board of Regents, University of Texas Syste

Progressive stridor: extraintestinal airway manifestations in a pediatric patient with inflammatory bowel disease.

Airway manifestations of inflammatory bowel disease are rare in pediatrics. This case describes a nine-year-old female with ulcerative colitis (UC) with progressive stridor and dyspnea for two months. Severe upper airway obstruction was noted on spirometry. CatScan (CT) of the neck and chest revealed tracheal narrowing with circumferential, heterogeneous soft tissue thickening, and posterior wall nodularity. Bronchoscopy visualized the granulation tissue of the large airways and an ulcerative lesion to the right mainstem. Consultation and evaluation by gastroenterology, oncology, and rheumatology determined a diagnosis of extraintestinal manifestations of UC. Systemic steroids led to symptom resolution and improvement in lung function