Global ETD Search

131	Detecting Structural Defects Using Novel Smart Sensory and Sensor-less Approaches Baghalian, Amin 17 October 2017 (has links) Monitoring the mechanical integrity of critical structures is extremely important, as mechanical defects can potentially have adverse impacts on their safe operability throughout their service life. Structural defects can be detected by using active structural health monitoring (SHM) approaches, in which a given structure is excited with harmonic mechanical waves generated by actuators. The response of the structure is then collected using sensor(s) and is analyzed for possible defects, with various active SHM approaches available for analyzing the response of a structure to single- or multi-frequency harmonic excitations. In order to identify the appropriate excitation frequency, however, the majority of such methods require a priori knowledge of the characteristics of the defects under consideration. This makes the whole enterprise of detecting structural defects logically circular, as there is usually limited a priori information about the characteristics and the locations of defects that are yet to be detected. Furthermore, the majority of SHM techniques rely on sensors for response collection, with the very same sensors also prone to structural damage. The Surface Response to Excitation (SuRE) method is a broadband frequency method that has high sensitivity to different types of defects, but it requires a baseline. In this study, initially, theoretical justification was provided for the validity of the SuRE method and it was implemented for detection of internal and external defects in pipes. Then, the Comprehensive Heterodyne Effect Based Inspection (CHEBI) method was developed based on the SuRE method to eliminate the need for any baseline. Unlike traditional approaches, the CHEBI method requires no a priori knowledge of defect characteristics for the selection of the excitation frequency. In addition, the proposed heterodyne effect-based approach constitutes the very first sensor-less smart monitoring technique, in which the emergence of mechanical defect(s) triggers an audible alarm in the structure with the defect. Finally, a novel compact phased array (CPA) method was developed for locating defects using only three transducers. The CPA approach provides an image of most probable defected areas in the structure in three steps. The techniques developed in this study were used to detect and/or locate different types of mechanical damages in structures with various geometries. Structural Health Monitoring SHM Sensor-less SHM SSHM Sensor-free SHM Heterodyning Effect Guided Waves Defect Detection Loose Bolt Detection Crack Detection Beam Forming Phased Array Monitoring of Pipes Nonlinear Guided Waves Nonlinear Wave Modulation Spectroscopy NWMS Surface Response to Excitation SuRE Acoustics, Dynamics, and Controls Electro-Mechanical Systems Signal Processing
132	Binary Arithmetic for Finite-Word-Length Linear Controllers : MEMS Applications / Intégration sur électronique dédiée et embarquée du traitement du signal et de la commande pour les microsystemes appliqués à la microrobotique Oudjida, Abdelkrim Kamel 20 January 2014 (has links) Cette thèse traite le problème d'intégration hardware optimale de contrôleurs linéaires à taille de mot finie, dédiés aux applications MEMS. Le plus grand défi est d'assurer des performances de contrôle satisfaisantes avec un minimum de ressources logiques. Afin d'y parvenir, deux optimisations distinctes mais complémentaires peuvent être entreprises: en théorie de contrôle et en arithmétique binaire. Seule cette dernière est considérée dans ce travail.Comme cette arithmétique cible des applications MEMS, elle doit faire preuve de vitesse afin de prendre en charge la dynamique rapide des MEMS, à faible consommation de puissance pour un contrôle intégré, hautement re-configurabe pour un ajustement facile des performances de contrôle, et facilement prédictible pour fournir une idée précise sur les ressources logiques nécessaires avant l'implémentation même.L'exploration d'un certain nombre d'arithmétiques binaires a montré que l'arithmétique radix-2r est celle qui répond au mieux aux exigences précitées. Elle a été pleinement exploitée afin de concevoir des circuits de multiplication efficaces, qui sont au fait, le véritable moteur des systèmes linéaires.L'arithmétique radix-2r a été appliquée à l'intégration hardware de deux structures linéaires à taille de mot finie: un contrôleur PID variant dans le temps et à un contrôleur LQG invariant dans le temps,avec un filtre de Kalman. Le contrôleur PID a montré une nette supériorité sur ses homologues existants. Quant au contrôleur LQG, une réduction très importante des ressources logiques a été obtenue par rapport à sa forme initiale non optimisée / This thesis addresses the problem of optimal hardware-realization of finite-word-length(FWL) linear controllers dedicated to MEMS applications. The biggest challenge is to ensuresatisfactory control performances with a minimal hardware. To come up, two distinct butcomplementary optimizations can be undertaken: in control theory and in binary arithmetic. Only thelatter is involved in this work.Because MEMS applications are targeted, the binary arithmetic must be fast enough to cope withthe rapid dynamic of MEMS; power-efficient for an embedded control; highly scalable for an easyadjustment of the control performances; and easily predictable to provide a precise idea on therequired logic resources before the implementation.The exploration of a number of binary arithmetics showed that radix-2r is the best candidate that fitsthe aforementioned requirements. It has been fully exploited to designing efficient multiplier cores,which are the real engine of the linear systems.The radix-2r arithmetic was applied to the hardware integration of two FWL structures: a linear timevariant PID controller and a linear time invariant LQG controller with a Kalman filter. Both controllersshowed a clear superiority over their existing counterparts, or in comparison to their initial forms. Systemes linéaires Arithmétique Radix-2 Contrôleurs à Taille de Mot Finie Systemes Micro Electro Mécanique Multiplication by a variable Multiplication by a constant Linear systems Radix-2r arithmetic High-Speed and Low-Power Design Finite-Word-Length Controllers Micro Electro Mechanical Systems 629.8
133	MICROFLUIDIC DEVICES FOR NEMATODE-BASED BEHAVIOURAL ASSAYS USING ELECTROTAXIS Rezai, Pouya 04 1900 (has links) <p>Small nematode model organisms such as <em>Caenorhabditis elegans</em> are widely used in the fields of neurobiology, toxicology, drug discovery, etc. They are advantageous due to their fully characterized genomic and cellular system. Traditional screening methods involve the exposure of animals to chemicals/drugs inside multiwell-plates while its effects on growth, movement and other cellular/sub-cellular processes are monitored by visual inspection. Yet, these methods are time-consuming, low-throughput, expensive, tedious, difficult to control, hard to modulate instantaneously, prone to subjectivity and not suitable for movement-based behavioural assays. Hence, a method to induce and to quantify movement on-demand in a rapid, sensitive, precise and reversible manner would greatly facilitate biological studies. In this thesis, microfluidic engineering approaches have been utilized in nematode-based assays due to their potential to obtain high precision measurements in a low-cost, rapid and automated manner. Movement response of worms to a diverse range of electric signals has been quantitatively characterized. DC and pulse-DC electric fields have been shown to stimulate worms’ swimming towards the negative electrode inside a microchannel (electrotaxis). AC electric fields were used to inhibit movement on-demand. Animals’ movement has been characterized in terms of speed and range of motion, body-bend frequency and turning time. Electrotaxis was shown to be mediated by neuronal activities and correlations between animal’s behaviour and neuronal signalling has also been demonstrated. Using this basic understanding, multiple microfluidic components such as position sensors and electric immobilizers have been developed. Electrotaxis has then been applied as a technique to sort worms in accordance to their size/age and phenotype as well as to perform drug screening at a single-animal level. Integration of the techniques and components developed during this research is expected to have a significant impact on the development of an integrated microfluidic platform for high throughput automated behavioural screening of nematodes with applications in drug discovery, toxicology, neurobiology and genetics.</p> / Doctor of Philosophy (PhD) Nematode C. elegans Electrotaxis Microfluidic Movement Assay Drug Screening Immobilization Sorting Detection Localization Animal Sciences Behavioral Neurobiology Bioelectrical and neuroengineering Biological Engineering Biomechanical Engineering Biomechanics and biotransport Biomedical devices and instrumentation Biotechnology Electro-Mechanical Systems Animal Sciences
134	Hypoxic Incubator: Improving Robustness/Reliability and Demonstrating Physiological Efficacy Tan, Damon Dennis 01 November 2024 (has links) (PDF) The Microphysiological Systems Laboratory aims to develop colorectal cancer tumor models under a hypoxic environment to assess model response to pharmaceutical compounds in vitro. To perform relevant studies, researchers have attempted to use different hypoxic inducing strategies such as a nitrogen pod and hypoxic incubator to recreate in vivo physiological responses to hypoxia. However, studies would be interrupted due to incubator functionality failure. To ensure successful and physiologically relevant studies, I improved and verified the robustness and reliability of a hypoxic incubator previously designed and manufactured in the lab. Through the testing and iterating design processes, I engineered and implemented solutions for the problems identified and validated these solutions through a series of functionality and reliability tests. PCB design on EAGLE software, outsourced manufacturing, and integration through component soldering and wire reconfiguration ensured permanent, robust, and reliable device electrical circuity. Sensor component replacement allowed for a more accurate hypoxic environment. Functionality and reliability tests were conducted to ensure the device was able to meet threshold values in startup phase, maintain these values throughout chronic hypoxia experiments, and sufficiently recover threshold conditions from interferences caused by chamber door opening. Improvements in user experience, device usability, and operator repeatability and reproducibility were made through the design and implementation of a simple and effective user interface. To assess the physiological efficacy of a hypoxic incubator an experiment was conducted using the designed incubator. The goal of the study was to observe the Warburg effect, a physiological phenomenon in cancer cells under hypoxia. 3T3 mouse fibroblast and SW620 colorectal cancer cells were cultured under three environmental conditions: nitrogen induced hypoxia pod, hypoxia with CO2 control, and normoxia incubation. Cell count was analyzed through inverted microscope fluorescent imaging and ImageJ processing to quantify cell proliferation activity. Data was analyzed using JMP to determine statistical significance in study results. The incubator maintained hypoxic conditions throughout the 7-day testing period as well as passed all functionality tests. The hypoxic incubator efficacy study resulted in a successful recreation of the Warburg effect observing the maintained proliferation ability of cancer cells under hypoxia which negatively impacted 3T3 cell proliferation. These results verified a robust, reliable, and effective hypoxic incubator for use in the MPS Lab to develop accurate tumor models and conduct relevant cancer research. Hypoxic Incubator Hypoxia PCB Warburg Effect SW620 3T3 Bioimaging and Biomedical Optics Biological Engineering Biomedical Biomedical Devices and Instrumentation Computer-Aided Engineering and Design Controls and Control Theory Electro-Mechanical Systems Systems and Integrative Engineering
135	3D Printed Microfluidic Fabrication Methodology, Characterization, Mechanical Design, and Applications in Electrostatic Artificial Muscles and Benthic Microbial Fuel Cells Hornik, Terak B 01 November 2024 (has links) (PDF) The fabrication of microfluidic devices often requires specialized methods. The development of these methods requires careful characterization and understanding of the processes involved. Using primarily PolyJet 3D printing technology, microfluidics offers a wide scope of applications such as microfluidic benthic microbial fuel cells (MBMFCs) and electrostatic artificial muscles. MBMFCs benefit from the confinement of the microbes resulting in close proximity between the electrode and the organisms. Using a modular design called the Sponge, assembly and upscaling is possible. Electrostatic artificial muscles benefit from a microfluidic approach due to the non-linearity of electrostatic attraction creating disproportionate benefits when miniaturized. When designed with the proper architectures, these muscles offer great promise. 3D printing these MBMFCs and artificial muscles allows for mass producibility and scalability. An approach combining 3D printing and microfluidics facilitates the further development and implementation of these technologies. Microfluidic 3D-Printing Benthic microbial fuel cell Muscle Self-assembly Actuator Applied Mechanics Biological Engineering Biomechanical Engineering Dynamics and Dynamical Systems Electrical and Electronics Electro-Mechanical Systems Energy Systems Engineering Mechanics Marine Biology Mechanics of Materials Other Engineering Power and Energy Systems and Integrative Engineering
136	Vision Beyond Optics: Standardization, Evaluation and Innovation for Fluorescence Microscopy in Life Sciences Huisman, Maximiliaan 01 April 2019 (has links) Fluorescence microscopy is an essential tool in biomedical sciences that allows specific molecules to be visualized in the complex and crowded environment of cells. The continuous introduction of new imaging techniques makes microscopes more powerful and versatile, but there is more than meets the eye. In addition to develop- ing new methods, we can work towards getting the most out of existing data and technologies. By harnessing unused potential, this work aims to increase the richness, reliability, and power of fluorescence microscopy data in three key ways: through standardization, evaluation and innovation. A universal standard makes it easier to assess, compare and analyze imaging data – from the level of a single laboratory to the broader life sciences community. We propose a data-standard for fluorescence microscopy that can increase the confidence in experimental results, facilitate the exchange of data, and maximize compatibility with current and future data analysis techniques. Cutting-edge imaging technologies often rely on sophisticated hardware and multi-layered algorithms for reconstruction and analysis. Consequently, the trustworthiness of new methods can be difficult to assess. To evaluate the reliability and limitations of complex methods, quantitative analyses – such as the one present here for the 3D SPEED method – are paramount. The limited resolution of optical microscopes prevents direct observation of macro- molecules like DNA and RNA. We present a multi-color, achromatic, cryogenic fluorescence microscope that has the potential to produce multi-color images with sub-nanometer precision. This innovation would move fluorescence imaging beyond the limitations of optics and into the world of molecular resolution. microscopy nanoscopy fluorescence cryogenic cryo-fluorescence cryoFM FM 3DSPEED SPEED standardization PSF PSF engineering achromatic dichroic multi-color super-resolution imaging imaging standard optics adaptive optics meta-data meta MetaMax calibration characterization back-projection image reconstruction pseudo-tomography model-based reconstruction chromatic aberrations cryogenic imaging 4D-PSF calibration tool Bioimaging and Biomedical Optics Biological Engineering Biomedical Devices and Instrumentation Biophysics Computer-Aided Engineering and Design Electrical and Electronics Electromagnetics and Photonics Electro-Mechanical Systems Engineering Physics Molecular Biology Nanoscience and Nanotechnology Numerical Analysis and Computation Optics Other Engineering Systems and Integrative Engineering

Page generated in 0.1439 seconds