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1
Tsan, Derek. "Zinc oxide nanowires for dynamic strain sensing." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44269.
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A dynamic strain sensor using piezoelectric zinc oxide nanowires was demonstrated for potential application in structural health monitoring. Simulations and reviews of literature determined that strain of the nanowires by uniaxial compression yields the largest piezoelectric potential and that the piezoelectric coefficient of zinc oxide nanowires is enhanced due to nanoscale size effects. The fabrication of zinc oxide nanowires on various substrates was investigated in order to determine the ideal materials and seed layer deposition methods to yield high quality vertically-aligned nanowires. Nanowires were grown on indium tin oxide-coated glass slides. The tips of the nanowires were electrically connected using poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) conductive polymer, which formed a Schottky barrier with zinc oxide allowing for the separation of charge across the nanowire-electrode junction. The piezoelectric coefficients of several fabricated devices were measured by applying pressure to the top of the nanowires and measuring the charge. Variations in performance between the different sensors were observed due to differences in the fabrication of each sensor. The highest coefficient measured was 11.5 pC/N, which is 16% higher than the bulk value for zinc oxide. The charge and voltage sensitivity to quasistatic pressure loading of the best performing sensor was calculated to be 1.32 pC/kPa and 16.7 mV/kPa. The response to clamped pressure stimulation from 1-90 kHz was evaluated using a piezoelectric stack actuator coupled with the zinc oxide nanowire sensor. The sensor showed excellent linearity to different amplitude vibrations at 1 kHz, and reasonably constant magnitude of charge output over the 1-90 kHz range for a constant vibration amplitude. The resonant frequency of the sensor and the response to free vibration could not be measured due to limitations in the available measuring equipment. The fabrication process for the nanowire sensor was found to be simple but inconsistent and could be improved by using repeatable processes such as photolithography for precisely defining electrode and seed layer geometries. The as-fabricated nanowire sensor shows promise as a dynamic strain sensor for structural health monitoring applications or pressure sensing but requires further characterization and optimization through modeling in order to compete with commercial sensors.
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Ye, Yuxian. "Study of Sensing Issues in Dynamic Spectrum Access." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/90184.
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Dynamic Spectrum Access (DSA) is now a commonly used spectrum sharing paradigm to mitigate the spectrum shortage problem. DSA technology allows unlicensed secondary users to access the unused frequency bands without interfering with the incumbent users. The key technical challenges in DSA systems lie in spectrum allocation problems and spectrum user's security issues. This thesis mainly focuses on spectrum monitoring technology in spectrum allocation and incumbent users' (IU) privacy issue.
Spectrum monitoring is a powerful tool in DSA to help commercial users to access the unused bands. We proposed a crowdsourcing-based unknown IU pattern monitoring scheme that leverages the power of masses of portable mobile devices to reduce the cost of the spectrum monitoring and demonstrate the ability of our system to capture not only the existing spectrum access patterns but also the unknown patterns where no historical spectrum information exist. Due to the energy limit of the battery-based system, we then leverage solar energy harvesting and develop an energy management scheme to support our spectrum monitoring system. We also provide best privacy-protection strategies for both static and mobile IUs in terms of hiding their true location under the detection of Environmental Sensing Capabilities system. In this thesis, the heuristic approach for our mathematical formulations and simulation results are described in detail. The simulation results show our spectrum monitoring system can obtain a high spectrum monitoring coverage and low energy consumption. Our IU privacy scheme provides great protection for IU's location privacy.<br>Master of Science<br>Spectrum relates to the radio frequencies allocated to the federal users and commercial users for communication over the airwaves. It is a sovereign asset that is overseen by the government in each country to manage the radio spectrum and issue spectrum licenses. In addition, spectrum bands are utilized for various purposes because different bands have different characteristics. However, the overly crowded US frequency allocation chart shows the scarcity of usable radio frequencies. The actual spectrum usage measurements reflect that multiple prized spectrum bands lay idle at most time and location, which indicates that the spectrum shortage is caused by the spectrum management policies rather than the physical scarcity of available frequencies. Dynamic spectrum access (DSA) was proposed as a new paradigm of spectrum sharing that allows commercial users to access the abundant white spaces in the licensed spectrum bands to mitigate the spectrum shortage problem and increase spectrum utilization. In DSA, two of the key technical challenges lie in how to dynamically allocate the spectrum and how to protect spectrum users’ security. This thesis focuses on the development of two types of mechanisms for addressing the above two challenges: (1) developing efficient spectrum monitoring schemes to help secondary users (SU) to accurately and dynamically access the white space in spectrum allocation and (2) developing privacy preservation schemes for incumbent users (IU) to protect their location privacy. Specifically, we proposed an unknown IU pattern monitoring scheme that leverages the power of masses of portable mobile devices to reduce the cost of common spectrum monitoring systems. We demonstrate that our system can track not only the existing IU spectrum access patterns but also the unknown patterns where no historical spectrum information exists. We then leverage the solar energy harvesting and design energy management scheme to support our spectrum monitoring system. Finally, we provide a strategy for both static and mobile IUs to hide their true location under the monitoring of Environmental Sensing Capabilities systems.
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Ward, Christopher Charles. "Terrain sensing and estimation for dynamic outdoor mobile robots." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42419.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.<br>Includes bibliographical references (p. 120-125).<br>In many applications, mobile robots are required to travel on outdoor terrain at high speed. Compared to traditional low-speed, laboratory-based robots, outdoor scenarios pose increased perception and mobility challenges which must be considered to achieve high performance. Additionally, high-speed driving produces dynamic robot-terrain interactions which are normally negligible in low speed driving. This thesis presents algorithms for estimating wheel slip and detecting robot immobilization on outdoor terrain, and for estimating traversed terrain profile and classifying terrain type. Both sets of algorithms utilize common onboard sensors. Two methods are presented for robot immobilization detection. The first method utilizes a dynamic vehicle model to estimate robot velocity and explicitly estimate longitudinal wheel slip. The vehicle model utilizes a novel simplified tire traction/braking force model in addition to estimating external resistive disturbance forces acting on the robot. The dynamic model is combined with sensor measurements in an extended Kalman filter framework. A preliminary algorithm for adapting the tire model parameters is presented. The second, model-free method takes a signal recognition-based approach to analyze inertial measurements to detect robot immobilization. Both approaches are experimentally validated on a robotic platform traveling on a variety of outdoor terrains. Two detector fusion techniques are proposed and experimentally validated which combine multiple detectors to increase detection speed and accuracy. An algorithm is presented to classify outdoor terrain for high-speed mobile robots using a suspension mounted accelerometer. The algorithm utilizes a dynamic vehicle model to estimate the terrain profile and classifies the terrain based on spatial frequency components of the estimated profile. The classification algorithm is validated using experimental results collected with a commercial automobile driving in real-world conditions.<br>by Christopher Charles Ward.<br>S.M.
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Goupil, Marc Y. "Dynamic Pressure Sensing for the Flight Test Data System." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2115.
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This thesis describes the design, assembly, and test of the FTDS-K, a new device in the Boundary Layer Data System (BLDS) family of flight data acquisition systems. The FTDS-K provides high-frequency, high-gain data acquisition capability for up to two pressure sensors and an additional three low-frequency pressure sensors. Development of the FTDS-K was separated into a core module, specialized analog subsystem, and practical testing of the FTDS-K in a flow measurement mission. The core module combines an nRF52840-based microcontroller module, switching regulator, microSD card, real-time clock, temperature sensor, and trio of pressure sensors to provide the same capabilities as previous-generation BLDS-P devices. An expansion header is included in the core module to allow additional functionality to be added via daughter boards. An analog signal chain comprised of two-stage amplification and fourth-order active antialiasing filters was implemented as a daughter board to provide an AC-coupled end-to-end gain of 7,500 and a DC-coupled end-to-end gain of 50. This arrangement was tested in a wind tunnel to demonstrate that sensors with a full-scale range of 103 kPa can be used to reliably discriminate between laminar and turbulent flows based on pressure fluctuation differences on the order of tens of Pa. A combination of wind-off correction and band-filtering was used to reduce the effect of inherent and induced electrical noise, while two-sensor correlation was tested and shown to be effective at removing certain types of noise. Total power consumption for the FTDS-K in a representative mission is 208 mW, which translates to an operational endurance of 9 hours with 2 AAA LiFeS2 cells at -40°C.
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Valieva, Inna. "Spectrum Sensing for Dynamic Spectrum Access in Cognitive Radio." Licentiate thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-52881.
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Abstract. The number of mobile devices is constantly growing, and the exclusivestatic spectrum allocation approach is leading to the spectrum scarcity problem whensome of the licensed bands are heavily occupied and others are nearly unused.Spectrum sharing and opportunistic spectrum access allow achieving more efficientspectrum utilization. Radio scene analysis is a first step in the cognitive radiooperation required to employ opportunistic spectrum access scenarios such as thedynamic spectrum access or frequency hopping spread spectrum. The objective of thiswork is to develop and virtual prototype the subset of radio scene analysis algorithmsintended to be used for deployment of opportunistic spectrum access in our targetapplication: a cognitive radio network consisting of multiple software-defined radionodes BitSDR. The proposed radio scene analysis algorithms are devoted to solvingtwo radio scene analysis problems: 1. detection of vacant frequency channels toimplement spectrum sharing scenarios; 2. waveform estimation including modulationtype, symbol rate, and central frequency estimation. From the subset of two radioscene analysis problems two hypotheses are formulated: the first is related to thevacant band identification and the second to waveform estimation. Then sevenresearch questions related to the trade-off between the sensing accuracy and real-time operation requirement for the proposed radio scene analysis algorithms, the nature of the noise, and assumptions used to model the radio scene environment such as the AWGN channel. In the scope of this work, Hypothesis 1, dedicated to vacant frequency band detection, has been proven. Research questions related to the selection of the observation bandwidth, vacant channels detection threshold, and the optimal algorithm have been answered. We have proposed, prototyped, and tested a vacant frequency channels detection algorithm based on wavelet transform performing multichannel detection in the wide band of 56 MHz based on the received signal observed during500 microseconds. Detection accuracy of 91 % has been demonstrated. Detection has been modeled as a binary hypothesis testing problem. Also, energy detection and cyclostationary feature extraction algorithms have been prototyped and tested, however, they have shown lower classification accuracy than wavelets. Answering research question 7 revealed the advantage of using wavelets due to the potential of the results of wavelet transform to be applied for solving the waveform estimation problem including symbol rate and modulation type. Test data samples have been generated during the controlled experiment by the hardware signal generator and received by proprietary hardware based on AD9364 Analog Devices transceiver. To test Hypothesis 2 research questions related to the waveform estimation have been elaborated. We could not fully prove Hypothesis 2 in the scope of this work. The algorithm and features that have been chosen for modulation type classification have not met the required classification accuracy to classify between five studied modulation classes 2FSK, BPSK, QPSK, 8PSK, and 16PSK. To capture more of the fine differences between the received signal modulated into different linear modulations it has been suggested to use the spectral features derived from the time-series signal observed during 500 microseconds or less observation time in the scope of the future work. However, the binary classification between 2FSK and BPSKpresented in Paper 1 could be performed based on instantaneous values and SNRinput: ensemble boosted trees and decision trees have shown an average classification accuracy of 86.3 % and 86.0 % respectively and classification speed of 1200000objects per second, what is faster than required 2000 objects per second.3The prototyping and testing of the proposed algorithm for symbol rate estimation based on deep learning have been performed to answer research question 2. Wavelet transform feature extraction has been proposed to be applied as a preprocessing step for deep learning-based estimation of the symbol rate for 2FSK modulated signals. This algorithm has shown an improvement in the accuracy of the symbol rate estimation in comparison with cyclostationary based detection. The validation accuracy of the symbol rate classification has reached 99.7 %. During testing, the highest average classification accuracy of 100 % has been observed for the signals with SNR levels 25-30 dB, while for signals with SNR 20-25 dB it was 96.3 %.
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Wafula, Alfred Brian. "Dynamic Monitoring of Cytotoxicity Using Electric Cell Substrate Impendence Sensing." Scholar Commons, 2006. http://scholarcommons.usf.edu/etd/3800.
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Electric cell-substrate impedance sensing (ECIS) pioneered by Giaever and Keese is suitable for continuous, automatic and real-time cell attachment analysis. ECIS is a novel electrical method to study, in real time, many of the activities of animal cells when grown in tissue culture. These include morphological changes, cell locomotion, and other behaviors directed by the cell's cytoskeleton. One of the most direct ECIS measurements is that of the attachment and spreading behaviors of cells. These measurements allow one to study and quantify the interaction of cultured cells with extracellular matrix (ECM) proteins and other macromolecules continuously and in real time. Traditionally, cell attachment and spreading measurements are labor intensive, requiring many manipulations of the cultures for microscopic evaluation of cell behavior. With ECIS, these same measurements can be made in an automated approach without opening the door of the incubator. The ECIS core technology is based on a technique of measuring the change in impedance of a small electrode to AC current flow. The heart of the measurement is a specialized slide that has 8 individual wells for cell culturing. The base of the device has an array of gold film electrodes that connect to the ECIS electronics to each of the 8 wells.
In our work we used ECIS to study the attachment and spread of HUVEC and 3T3 cells. The curve of HUVEC showed higher resistances than that of 3T3 cells. This was due to the fact we used gelatin to aid in attachment of HUVECs which accounted for the high resistances. 3T3 cells attached easily without help of gelatin. We also studied the cytotoxicity of HUVEC and 3T3 cells. The drugs that we used were CB, H7 and CdCl2. We found that the best drug was CB since it affected the cells even at low concentrations. H7 effects were mild while CdCl2 only worked at high concentrations. HUVEC cells make loose contact on electrodes and are easily detached by drugs. 3T3 makes firm at tachment to the electrodes and are not easily detached from the electrodes.
Electrical impedance measurements on multiple electrodes are highly attractive in this application because of the potential for direct computer control.
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Purohit, Aveek. "Controlled-mobile Sensor Networks for Dynamic Sensing and Monitoring Applications." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/357.
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Many potential indoor sensing and monitoring applications are characterized by hazardous and constantly-changing operating environments. For example, consider emergency response scenarios such as urban fire rescue. Traditionally, first responders have little access to situational information. In-situ information about the conditions, such as the extent and evolution of the indoor fire, can augment rescue efforts and reduce risk to emergency personnel. Static sensor networks that are pre-deployed or manually deployed have been proposed for such applications, but are less practical due to need for large infrastructure, lack of adaptivity and limited coverage. The main hypothesis of this thesis is that controlled-mobile networked sensing – the capability of nodes to move as per network needs, is a novel, feasible, and beneficial approach to monitoring dynamic and hazardous environments. Controlled-mobility in sensor networks can provide the desired autonomy and adaptability to overcome the limitations of static sensors. The research focuses on four of the major challenges in realizing controlled-mobile sensor networking systems: Understanding the trade-off between cost, weight, and sensing and actuation capabilities in designing a hardware platform for controlled-mobile sensing together with a complementary firmware architecture. Designing simulation environments for controlled-mobile sensing platforms that adequately incorporate both the cyber (network, processing, planning) and physical (motion, environment) components of such systems. Investigating the effects of controlled-mobility on network group discovery and maintenance protocols and designing approaches that meet the mobility, latency and energy constraints. Exploring novel low-overhead infrastructure-less mechanisms for collaborative coverage, deployment and navigation of resource-constrained controlled-mobile nodes in previously unseen environments. The thesis validates and evaluates the presented architecture, tools, and algorithms for controlled-mobile sensing systems through extensive simulations and a real-system test-bed implementation. The results show that controlled-mobility is feasible and can enable new class of sensing and monitoring applications.
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Naeli, Kianoush. "Optimization of piezoresistive cantilevers for static and dynamic sensing applications." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28247.
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Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.<br>Committee Chair: Brand, Oliver; Committee Member: Adibi, Ali; Committee Member: Allen, Mark G.; Committee Member: Bottomley, Lawrence A.; Committee Member: Degertekin, F. Levent.
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Jackson, Cornelius Christiaan. "Tactile force-sensing for dynamic gripping using piezoelectric force- sensors." Thesis, Bloemfontein : Central University of Technology, Free State, 2009. http://hdl.handle.net/11462/34.
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Oxborrow, Joseph B. "Dynamic Nanochannels for Biosensing Applications." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4261.
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Inexpensive label-free detection of biomarker panels in serum could revolutionize earlycancer diagnosis and treatment. Such detection capabilities may be possible with dynamicnanochannels in conjunction with electrical impedance measurement. In Dr. Greg Nordin's lab I designed, fabricated and tested several iterations of these sensors with polydimethyl-siloxane microfluidics. The final design yielded a dynamic nanochannel array sensor thatshowed a 140% impedance change when exposed to 14µM bovine serum albumin in phos-phate buffered saline. For the geometry and noise limits of the tested device, simulationsindicated that a minimum detectable concentration of 20pM with specifically bound strep-tavidin should be possible. However, the polydimethylsiloxane approach is also shown to beproblematic in meeting the trade-offs required for a practical device. Consequently, alter-native materials and designs are suggested to reduce the minimum detectable concentrationto the high femtomolar range, which would be attractive for detection of many medicalbiomarkers.
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Asif, Muhammad Salman. "Dynamic compressive sensing: sparse recovery algorithms for streaming signals and video." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49106.
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This thesis presents compressive sensing algorithms that utilize system dynamics in the sparse signal recovery process. These dynamics may arise due to a time-varying signal, streaming measurements, or an adaptive signal transform. Compressive sensing theory has shown that under certain conditions, a sparse signal can be recovered from a small number of linear, incoherent measurements. The recovery algorithms, however, for the most part are static: they focus on finding the solution for a fixed set of measurements, assuming a fixed (sparse) structure of the signal.
In this thesis, we present a suite of sparse recovery algorithms that cater to various dynamical settings. The main contributions of this research can be classified into the following two categories: 1) Efficient algorithms for fast updating of L1-norm minimization problems in dynamical settings. 2) Efficient modeling of the signal dynamics to improve the reconstruction quality; in particular, we use inter-frame motion in videos to improve their reconstruction from compressed measurements.
Dynamic L1 updating: We present homotopy-based algorithms for quickly updating the solution for various L1 problems whenever the system changes slightly. Our objective is to avoid solving an L1-norm minimization program from scratch; instead, we use information from an already solved L1 problem to quickly update the solution for a modified system. Our proposed updating schemes can incorporate time-varying signals, streaming measurements, iterative reweighting, and data-adaptive transforms. Classical signal processing methods, such as recursive least squares and the Kalman filters provide solutions for similar problems in the least squares framework, where each solution update requires a simple low-rank update. We use homotopy continuation for updating L1 problems, which requires a series of rank-one updates along the so-called homotopy path.
Dynamic models in video: We present a compressive-sensing based framework for the recovery of a video sequence from incomplete, non-adaptive measurements. We use a linear dynamical system to describe the measurements and the temporal variations of the video sequence, where adjacent images are related to each other via inter-frame motion. Our goal is to recover a quality video sequence from the available set of compressed measurements, for which we exploit the spatial structure using sparse representations of individual images in a spatial transform and the temporal structure, exhibited by dependencies among neighboring images, using inter-frame motion. We discuss two problems in this work: low-complexity video compression and accelerated dynamic MRI. Even though the processes for recording compressed measurements are quite different in these two problems, the procedure for reconstructing the videos is very similar.
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Wafula, Alfred Brian. "Dynamic monitoring of cytotoxicity by using electric cell substrate impedance sensing." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001562.
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Li, Yan. "An integrated water quality monitoring system with dynamic remote sensing feedback /." Online version of thesis, 2007. http://hdl.handle.net/1850/5834.
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Breckner, Robert [Verfasser], and Stefania [Akademischer Betreuer] Petra. "Compressed Motion Sensing and Dynamic Tomography / Robert Breckner ; Betreuer: Stefania Petra." Heidelberg : Universitätsbibliothek Heidelberg, 2018. http://d-nb.info/1177386046/34.
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Rodrigues, Quemel e. Assis Santana Pedro Henrique de. "Dynamic execution of temporal plans with sensing actions and bounded risk." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107049.
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Thesis: Ph. D. in Aerospace Engineering, Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 289-306).<br>A special report on the cover of the June 2016 issue of the IEEE Spectrum magazine reads: "can we trust robots?" In a world that has been experiencing a seemingly irreversible process by which autonomous systems have been given increasingly more space in strategic areas such as transportation, manufacturing, energy supply, planetary exploration, and even medical surgeries, it is natural that we start asking ourselves if these systems could be held at the same or even higher levels of safety than we expect from humans. In an effort to make a contribution towards a world of autonomy that we can trust, this thesis argues that one necessary step in this direction is the endowment of autonomous agents with the ability to dynamically adapt to their environment while meeting strict safety guarantees. From a technical standpoint, we propose that autonomous agents in safety-critical applications be able to execute conditional plans (or policies) within risk bounds (also referred to as chance constraints). By being conditional, the plan allows the autonomous agent to adapt to its environment in real-time by conditioning the choice of activity to be executed on the agent's current level of knowledge, or belief, about the true state of world. This belief state is, in turn, a function of the history of potentially noisy sensor observations gathered by the agent from the environment. With respect to bounded risk, it refers to the fact that executing such conditional plans should guarantee to keep the agent "safe" - as defined by sets of state constraints - with high probability, while moving away from the conservatism of minimum risk approaches. In this thesis, we propose Chance-Constrained Partially Observable Markov Decision Processes (CC-POMDP's) as a formalism for conditional risk-bounded planning under uncertainty. Moreover, we present Risk-bounded AO* (RAO*), a heuristic forward search-based algorithm that searches for solutions to a CC-POMDP by leveraging admissible utility and risk heuristics to simultaneously guide the search and perform early pruning of overly-risky policy branches. In an effort to facilitate the specification of risk-bounded behavior by human modelers, we also present the Chance-constrained Reactive Model-based Programming Language (cRMPL), a novel variant of RMPL that incorporates chance constraints as part of its syntax. Finally, in support of the temporal planning applications with duration uncertainty that this thesis is concerned about, we present the Polynomial-time Algorithm for Risk-aware Scheduling (PARIS) and its extension to conditional scheduling of Probabilistic Temporal Plan Networks (PTPN's). The different tools and algorithms developed in the context of this thesis are combined to form the Conditional Planning for Autonomy with Risk (CLARK) system, a risk-aware conditional planning system that can generate chance-constrained, dynamic temporal plans for autonomous agents that must operate under uncertainty. With respect to our empirical validation, each component of CLARK is benchmarked against the relevant state of the art throughout the chapters, followed by several demonstrations of the whole CLARK system working in tandem with other building blocks of an architecture for autonomy.<br>by Pedro Henrique de Rodrigues Quemel e Assis Santana.<br>Ph. D. in Aerospace Engineering
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Montaño-Gutierrez, Luis Fernando. "Dynamic signal processing by the glucose sensing network of Saccharomyces cerevisiae." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/28973.
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Organisms must constantly face and adapt to environmental change. Although unpredictable events may inevitably impose threats, temporally correlated changes may also provide opportunities from which an organism can profit. An evolutionarily successful microbe must collect enough information to distinguish threats from opportunities. Indeed, for nutrient transport, it is not clear how organisms distinguish one from the other. Fluctuations in nutrient levels can quickly render any transporter's capabilities obsolete. Identifying the environment's dynamic identity is therefore a highly valuable asset for a cell to elicit an accurate physiological response. Recent evidence suggests that the baker's yeast Saccharomyces cerevisiae can exert anticipatory responses to environmental shifts. Nevertheless, the mechanisms by which cells are able to incorporate information from the environment's dynamic features is not understood. A potential source of complex information processing is a highly intricate biochemical network that controls glucose transport. The understanding of this network, however, has revolved around its ability to adjust expression of 17 hexose transporter genes (HXT) to glucose levels. In this thesis, I postulate that instead the glucose sensing network is dynamically controlling the 7 major hexose transporters. By studying transporter dynamics in several scenarios, I provide substantial evidence for this hypothesis. I find that hexose transporters with similar reported affinities (Hxt2 and Hxt4) are robustly allocated to separate stages of growth for multiple initial glucose concentrations. Using single-cell studies, I show that Hxt4 expresses exclusively during glucose downshifts, in contrast with Hxt2. From multiple approaches, I demonstrate that Mig1 is mostly responsible for reporting on the time derivative of glucose, and harnessing it to differentially regulate both transporters. I also provide evidence for the roles of Rgt2 and Std1 in modulating long-term glucose repression of Hxt4. This work extends our ideas on the functionality of transport and gene regulation beyond the established steady-state models. The ability to decode environmental dynamics is likely to be present in other signaling systems and may impact a cell's decision to use fermentation - a decision which is of fundamental interest both for cancer research and for biotechnology.
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Lin, Likun. "SDN-Enabled Dynamic Feedback Control and Sensing in Agile Optical Networks." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/613595.
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Fiber optic networks are no longer just pipelines for transporting data in the long haul backbone. Exponential growth in traffic in metro-regional areas has pushed higher capacity fiber toward the edge of the network, and highly dynamic patterns of heterogeneous traffic have emerged that are often bursty, severely stressing the historical "fat and dumb pipe" static optical network, which would need to be massively over-provisioned to deal with these loads. What is required is a more intelligent network with a span of control over the optical as well as electrical transport mechanisms which enables handling of service requests in a fast and efficient way that guarantees quality of service (QoS) while optimizing capacity efficiency. An "agile" optical network is a reconfigurable optical network comprised of high speed intelligent control system fed by real-time in situ network sensing. It provides fast response in the control and switching of optical signals in response to changing traffic demands and network conditions. This agile control of optical signals is enabled by pushing switching decisions downward in the network stack to the physical layer. Implementing such agility is challenging due to the response dynamics and interactions of signals in the physical layer. Control schemes must deal with issues such as dynamic power equalization, EDFA transients and cascaded noise effects, impairments due to self-phase modulation and dispersion, and channel-to-channel cross talk. If these issues are not properly predicted and mitigated, attempts at dynamic control can drive the optical network into an unstable state. In order to enable high speed actuation of signal modulators and switches, the network controller must be able to make decisions based on predictive models. In this thesis, we consider how to take advantage of Software Defined Networking (SDN) capabilities for network reconfiguration, combined with embedded models that access updates from deployed network monitoring sensors. In order to maintain signal quality while optimizing network resources, we find that it is essential to model and update estimates of the physical link impairments in real-time. In this thesis, we consider the key elements required to enable an agile optical network, with contributions as follows: *Control Framework: extended the SDN concept to include the optical transport network through extensions to the OpenFlow (OF) protocol. A unified SDN control plane is built to facilitate control and management capability across the electrical/packet-switched and optical/circuit-switched portions of the network seamlessly. The SDN control plane serves as a platform to abstract the resources of multilayer/multivendor networks. Through this platform, applications can dynamically request the network resources to meet their service requirements. *Use of In-situ Monitors: enabled real-time physical impairment sensing in the control plane using in-situ Optical Performance Monitoring (OPM) and bit error rate (BER) analyzers. OPM and BER values are used as quantitative indicators of the link status and are fed to the control plane through a high-speed data collection interface to form a closed-loop feedback system to enable adaptive resource allocation. *Predictive Network Model: used a network model embedded in the control layer to study the link status. The estimated results of network status is fed into the control decisions to precompute the network resources. The performance of the network model can be enhanced by the sensing results. *Real-Time Control Algorithms: investigated various dynamic resource allocation mechanisms supporting an agile optical network. Intelligent routing and wavelength switching for recovering from traffic impairments is achieved experimentally in the agile optical network within one second. A distance-adaptive spectrum allocation scheme to address transmission impairments caused by cascaded Wavelength Selective Switches (WSS) is proposed and evaluated for improving network spectral efficiency.
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Bhardwaj, Ananya. "Biomimetic Detection of Dynamic Signatures in Foliage Echoes." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/102299.
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Horseshoe bats (family Rhinolophidae) are among the bat species that dynamically deform
their reception baffles (pinnae) and emission baffles (noseleaves) during signal reception and
emissions, respectively. These dynamics are a focus of prior studies that demonstrated that
these effects could introduce time-variance within emitted and received signals. Recent lab based
experiments with biomimetic hardware have shown that these dynamics can also inject
time-variant signatures into echoes from simple targets. However, complex foliage echoes,
which comprise a large portion of the received echoes and contain useful information for
these bats, have not been studied in prior research. We used a biomimetic sonarhead which
replicated these dynamics, to collect a large dataset of foliage echoes (>55,000). To generate
a neuromorphic representation of echoes that was representative of the neural spikes in bat
brains, we developed an auditory processing model based on Horseshoe bat physiological
data. Then, machine learning classifiers were employed to classify these spike representations
of echoes into distinct groups, based on the presence or absence of dynamics' effects.
Our results showed that classification with up to 80% accuracy was possible, indicating the
presence of these effects in foliage echoes, and their persistence through the auditory processing.
These results suggest that these dynamics' effects might be present in bat brains, and
therefore have the potential to inform behavioral decisions. Our results also indicated that
potential benefits from these effects might be location specific, as our classifier was more
effective in classifying echoes from the same physical location, compared to a dataset with
significant variation in recording locations. This result suggested that advantages of these
effects may be limited to the context of particular surroundings if the bat brain similarly
fails to generalize over variation in locations.<br>Master of Science<br>Horseshoe bats (family Rhinolophidae) are an echolocating bat species, i.e., they emit sound
waves and use the corresponding echoes received from the environment to gather information
for navigation. This species of bats demonstrate the behavior of deforming their emitter
(noseleaf), and ears (pinna), while emitting or receiving echolocation signals. Horseshoe
bats are adept at navigating in the dark through dense foliage. Their impressive navigational
abilities are of interest to researchers, as their biology can inspire solutions for autonomous
drone navigation in foliage and underwater. Prior research, through numerical studies and
experimental reproductions, has found that these deformations can introduce time-dependent
changes in the emitted and received signals. Furthermore, recent research using a biomimetic
robot has found that echoes received from simple shapes, such as cube and sphere, also
contain time-dependent changes. However, prior studies have not used foliage echoes in
their analysis, which are more complex, since they include a large number of randomly
distributed targets (leaves). Foliage echoes also constitute a large share of echoes from the
bats' habitats, hence an understanding of the effects of the dynamic deformations on these
foliage echoes is of interest. Since echolocation signals exist within bat brains as neural spikes,
it is also important to understand if these dynamic effects can be identified within such signal
representations, as that would indicate that these effects are available to the bats' brains. In
this study, a biomimetic robot that mimicked the dynamic pinna and noseleaf deformation
was used to collect a large dataset (>55,000) of echoes from foliage. A signal processing model
that mimicked the auditory processing of these bats and generated simulated spike responses
was also developed. Supervised machine learning was used to classify these simulated spike
responses into two groups based on the presence or absence of these dynamics' effects. The
success of the machine learning classifiers of up to 80% accuracy suggested that the dynamic
effects exist within foliage echoes and also spike-based representations. The machine learning
classifier was more accurate when classifying echoes from a small confined area, as compared
to echoes distributed over a larger area with varying foliage. This result suggests that any
potential benefits from these effects might be location-specific if the bat brain similarly fails
to generalize over the variation in echoes from different locations.
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Girard, Léa. "Quorum Sensing in Vibrio spp. : AHL diversity, temporal dynamic and niche partitioning." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066650/document.
Full textAbstract:
Chez les Vibrio spp., le QS est impliqué dans de nombreuses fonctions comme la colonisation de niche écologiques, les stratégies de survie ou encore la virulence. Cependant, pour la majorité des espèces de Vibrio, la diversité des AHLs produites reste largement sous-estimée et l'étude du QS est encore limitée à quelques espèces modèles ou pathogènes. Toutefois, dans les environnements aquatiques, ces espèces sont minoritaires et les espèces les plus abondantes ne sont que très peu étudiées. Nos résultats ont révélé une importante diversité d'AHLs mais aussi, de façon surprenante, une hétérogénéité dans les phénotypes de production d'AHL au sein d'une même espèce de Vibrio. Pour la première fois, nous avons mis en évidence qu'une même souche de Vibrio pouvait présenter des phénotypes de production d'AHLs différent au cours du temps et une approche statistique a révélé l'implication de certains déterminants biotiques et abiotiques dans ces variations temporelles. Par ailleurs, une approche à micro-échelle a révélé une structuration des populations de Vibrio en unités fonctionnelles constituées de souches phylogénétiquement proches qui partagent des niches écologiques spécifiques et des comportements sociaux. Nos résultats ont mis en évidence que les modalités de communication pouvaient être hétérogènes suggérant l'absence d'un langage commun au sein de ces unités fonctionnelles. En conclusion, ce travail de thèse a permis d'apporter de nouvelles connaissances sur le QS chez les Vibrio dans l'environnement marin, de la souche à la population, et propose une vision intégrée des mécanismes de régulation de la production d'AHLs dans l'environnement<br>Quorum sensing is an important mechanism among Vibrio species and is involved in many vital functions such as niche colonization, survival strategies or virulence. However, AHL diversity still largely underestimated for the majority of Vibrio species and the current knowledge on AHL-mediated QS is limited to a few pathogenic or bioluminescent species. Nonetheless, these species are weakly abundant in seawater while dominant species in the environment are poorly studied. Our results revealed a unexpected diversity of AHL molecules but also a quite surprising intra-species diversity of AHL production phenotypes. For the first time, we showed that different isolates of a single genotype switched between different AHL production phenotypes among time and we revealed the potential involvement of abiotic and biotic parameters in these variations. However, it appears that when studied at a microscale, Vibrio populations are showing a functional structuration in ecological units consisting of phylogenetically close strains sharing habitat and social traits. In this context, it was necessary to determine if these different AHL production phenotypes were associated to different micro-habitats in the water column. We did not demonstrate that a common language was spoken within ecological populations. This thesis work provide new insights on AHL-mediated QS among a broader range of species and among Vibrio populations and depicts the potential impact of multiple aspects of marine environments on AHL production
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Ma, Yuan. "Sub-Nyquist wideband spectrum sensing and sharing." Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/30716.
Full textAbstract:
The rising popularity of wireless services resulting in spectrum shortage has motivated dynamic spectrum sharing to facilitate e cient usage of the underutilized spectrum. Wideband spectrum sensing is a critical functionality to enable dynamic spectrum access by enhancing the opportunities of exploring spectral holes, but entails a major implemen- tation challenge in compact commodity radios that have limited energy and computation capabilities. The sampling rates speci ed by the Shannon-Nyquist theorem impose great challenges both on the acquisition hardware and the subsequent storage and digital sig- nal processors. Sub-Nyquist sampling was thus motivated to sample wideband signals at rates far lower than the Nyquist rate, while still retaining the essential information in the underlying signals. This thesis proposes several algorithms for invoking sub-Nyquist sampling in wideband spectrum sensing. Speci cally, a sub-Nyquist wideband spectrum sensing algorithm is proposed that achieves wideband sensing independent of signal sparsity without sampling at full bandwidth by using the low-speed analog-to-digital converters based on sparse Fast Fourier Transform. To lower signal spectrum sparsity while maintaining the channel state information, the received signal is pre-processed through a proposed permutation and ltering algorithm. Additionally, a low-complexity sub-Nyquist wideband spectrum sensing scheme is proposed that locates occupied channels blindly by recovering the sig- nal support, based on the jointly sparse nature of multiband signals. Exploiting the common signal support shared among multiple secondary users, an e cient coopera- tive spectrum sensing scheme is developed, in which the energy consumption on signal acquisition, processing, and transmission is reduced with the detection performance guar- antee. To further reduce the computation complexity of wideband spectrum sensing, a hybrid framework of sub-Nyquist wideband spectrum sensing with geolocation database is explored. Prior channel information from geolocation database is utilized in the sens- ing process to reduce the processing requirements on the sensor nodes. The models of the proposed algorithms are derived and veri ed by numerical analyses and tested on both real-world and simulated TV white space signals.
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Kim, T. "Development of PVDF tactile dynamic sensing in a behaviour-based assembly robot." Thesis, University of Edinburgh, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.653404.
Full textAbstract:
The research presented in this thesis focuses on the development of tactile event signature sensors and their application, especially in reactive behaviour-based robotic assembly systems. In pursuit of practical and economic sensors for detecting part contact, the application of PVDF (polyvinylidene fluoride) film, a mechanical vibration sensitive piezo material, is investigated. A <I>Clunk Sensor</I> is developed which remotely detects impact vibrations, and a <I>Push Sensor</I> is developed which senses small changes in the deformation of a compliant finger surface. The <I>Push Sensor</I> is further developed to provide some force direction and force pattern sensing capability. By being able to detect changes of state in an assembly, such as a change of contact force, an assembly robot can be well informed of current conditions. The complex structure of assembly tasks provides a rich context within which to interpret changes of state, so simple binary sensors can conveniently supply a lot more information than in the domain of mobile robots. Guarded motions, for example, which require sensing a change of state, have long been recognised as very useful in part mating tasks. Guarded motions are particularly well suited to be components of assembly behavioural modules. In behaviour-based robotic assembly systems, the high level planner is endowed with as little complexity as possible while the low level planning execution agent deals with actual sensing and action. Highly reactive execution agents can provide advantages by encapsulating low level sensing and action, hiding the details of sensori-motor complexity from the higher levels. Because behaviour-based assembly systems emphasise the utility of this kind of qualitative state-change sensor (as opposed to sensors which measure physical quantities), the robustness and utility of the <I>Push Sensor</I> was tested in an experimental behaviour-based system. An experimental task of pushing a ring along a convoluted stiff wire is chosen, in which the tactile sensors developed here are aided by vision. Three different methods of combining these different sensors within the general behaviour-based paradigm are implemented and compared. This exercise confirms the robustness and utility of the PVDF-based tactile sensors. We argue that the comparison suggests that for behaviour-based assembly systems using multiple concurrent sensor systems, bottom-level motor control in terms of force or velocity would be more appropriate than positional control. Behaviour-based systems have traditionally tried to avoid symbolic knowledge. Considering this in the light of the above work, it was found useful to develop a taxonomy of type of knowledge and refine the prohibition.
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Gao, Jian. "Dynamic position sensing for parallel kinematic machine and new generation machine tool." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268479.
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Crews, Mark Conrad. "Dynamic sensing and signaling over the packet radio network multiple access channel." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/14940.
Full textAbstract:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1987.<br>MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.<br>Bibliography: leaves 129-130.<br>by Mark Conrad Crews.<br>M.S.
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Zhang, Guangtao S. B. Massachusetts Institute of Technology. "Design, development, and dynamic characterization of multi-axis force sensing composite footpad." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92686.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 79-80).<br>Accurate ground reaction force measurements are important for the development, implementation, and control of high speed legged locomotion robots. From previous research studies, a composite force sensing footpad has been developed, tested, and characterized statically at the MIT Biomimetics Lab. The developed footpad sensor must also be characterized dynamically prior to its implementation with the MIT Cheetah robot. This study includes the design, development, and dynamic characterization of the footpad sensor. In order to characterize the developed footpad sensor dynamically, a custom impact tester has been designed, fabricated, characterized, and verified. The developed impact tester was shown to satisfy all the specified functional requirements and is capable of producing a range of impact conditions to cover the possible operational modes of the MIT Cheetah robot such as running, walking, galloping, or hopping. The previously developed static ANN model was shown to be highly imprecise and a dynamic ANN model was developed to better predicate the force profile during impact. The dynamic ANN model was shown to perform 400% better at predicting peak impact force.It was also verified with additional dynamic testings of the footpad sensor, and RMSE = 3.17% for a maximum reference force reading of 3000N was achieved for the developed dynamic ANN model. The footpad sensor was redesigned and fabricated to integrate with the MIT Cheetah robot. Numerous Cheetah robot hopping experiments were carried out, and the footpad sensor was able to detect ground contact accurately and precisely. 'No damage nor performance degrading of the developed footpad sensor was observed at the end of the experimentation. Though further testing and optimization of the composite footpad sensor is required, the developed prototype has shown promising results under both static and dynamic conditions, which suggests that a composite footpad force sensor is not only a viable approach for force sensing but also likely to take place of the rigid force sensing devices in the high speed locomotion robots' arena.<br>by Guangtao Zhang.<br>S.B.
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Green, Michael A. "Improving Identification of Subtle Changes in Wide-Area Sensing through Dynamic Zoom." Thesis, Delaware State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10794023.
Full textAbstract:
<p> The past decade has seen an abundance of applications that utilize sensors to collect data. One such example is a gigapixel image, which combines a multitude of high-quality images into a panorama capable of viewing hundreds of acres. The resulting datasets can be quite large, making analysis time consuming and resource intensive. Moreover, coverage of such broad environments can mean numerous sensor feeds to which one must attend. A suitable approach for analysis and sense-making of such data is to focus on “interesting” samples of data, namely regions of interest, or ROI. ROIs are especially useful in wide-area sensing situations that return datasets that are largely similar from one instance to the next, but also possess small differences. Identifying subtle changes is relevant to certain scenarios in surveillance, such as the evidence of human activity. Several ROI detection techniques exist in the research literature. My work focuses on ROI detection tuned to subtle differences for images at varying zoom levels. My thesis consists of developing a method that identifies regions of interest for subtle changes in images. In this pursuit, my contributions will address key questions including the characterization of image information dynamics through introduction of dynamic zoom, the definition and measurement of subtlety, and an approach for scoring and selecting ROIs. This work will provide an automated attention mechanism for zoomed images, but is also applicable to domains include satellite imagery and cyber security. </p><p>
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Honda, Maya. "New Parameters of Ultrafast Dynamic Contrast‐Enhanced Breast MRI Using Compressed Sensing." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263534.
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Sang, Alexander Kipkosgei. "Distributed Vibration Sensing using Rayleigh Backscatter in Optical Fibers." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77274.
Full textAbstract:
Sensing has been essential for the investigation, understanding, exploitation, and utilization of physical phenomena. Traditional single-point sensing methods are being challenged by the multi-point or distributed sensing capabilities afforded by optical fiber sensors. A powerful technique available for distributed sensing involves the use of the Optical Frequency Domain Reflectometry (OFDR).
This work focuses on using OFDR as a means of obtaining distributed vibration measurements using the Rayleigh scatter along a single-mode optical fiber. The effort begins by discussing various distributed measurement techniques currently in use before discussing the OFDR technique. Next, a thorough discussion on how high spatially resolved Rayleigh measurements are acquired and how such measurements can be used to make static strain measurements is presented. A new algorithm to resolve strain at regions of high spatial gradient is developed. This results in enhanced measurement performance of systems using the Rayleigh scatter to determine static strain or temperature measurements by improving measurement fidelity at the high gradient locations.
Next, discussions on how dynamic strain (vibration) couples to optical fiber in a single point and in a distributed setting are presented. Lessons learned are then used to develop a new and unique distributed vibration measurement algorithm. Various consequential benefits are then reviewed before concluding remarks are stated.
A simulation model was developed and used to supplement this investigation in every step of the discussion. The model was used to gain insight on how various physical phenomena interact with the optical fiber. The simulation was also used to develop and optimize the high gradient and vibration algorithms developed herein. Simple experiments were then used to validate the theory and the simulation models.<br>Ph. D.
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Kreuder, Andreas. "Dynamische Dehnungsmessung mit Faser-Bragg-Gittern - Dynamic strain sensing with Fiber-Bragg-Gratings." Gerhard-Mercator-Universitaet Duisburg, 2001. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-07172001-100829/.
Full textAbstract:
The design of heavy load manipulators, robots, vehicles and aeroplanes is based on linear statics. Therefore the information about the type of stress and the stress vector (stress direction and stress factor) is needed. Modern development strategies demand a reduction of material, so a dimensional constraints with security supplement is no longer possible. To fulfil the requirements for sufficient lifetime and safety the online monitoring of stresses during operation is essential. The discovery by Robert Hooke in 1678 concerning the relation between mechanical stress and strain builds the basis for the experimental measurement of stress via strain sensing. Due to the fine characteristics like the high multiplexibility, the high reliability and small failures optical Fiber-Bragg-Grating (FBG) strain sensors have the potential to substitute conventional strain gauges. In this thesis the design and realisation of FBG sensor networks for online-monitoring of dynamic stresses is observed.
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Wu, Xing. "Exploitation of noncovalent/dynamic covalent interactions in sensing, self-assembly and membrane transport." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/398005/.
Full textAbstract:
This thesis reports the development of several novel chemical sensing systems, self-assembled aggregates, and membrane transporters in which noncovalent and/or dynamic covalent interactions operate. Perylenebisimide dyes functionalized with boronic acid groups were designed as effective chirality sensors for [alpha]-hydroxy carboxylates. Binding of chiral ?-hydroxy carboxylate guests via boronate ester linkage leads to formation of optically active helical stacks of perylenebisimide dyes in water, giving diagnostic induced circular dichroism signals in the perylene absorption region. A boronic acid-functionalized pyrene fluorophore forms excimer-emissive stacks upon cooperative binding of fluoride ion and catechol to the boron centre, allowing sensitive sensing of fluoride at ppm levels in aqueous solution which was unprecedented for boronic acids. The stabilization of boron-fluoride adduct in the aggregate and increase of Lewis acidity via catechol binding were proposed responsible for the unprecedented affinity, as supported by control experiments. A dynamic covalent amphiphile comprised of 4-formylphenylboronic acid and octylamine forms vesicular aggregates selectively with glucose which can bind two boronic acids thus forming “Gemini-type” amphiphiles. The aggregates feature stabilization of imine bond and boronate ester linkage, with the two dynamic covalent bonds working in synergy promoting the formation of each other despite the spatial separation. The system allows selective sensing of glucose against the interference of fructose, for the first time without resorting to any synthesis. A dynamic covalent approach was employed to transmembrane transport of amino acids by the formation of a three-component assembly. A mixture of a squaramide and a lipophilic and electrophilic aldehyde is shown to synergistically transport glycine across phospholipid vesicle membranes. The transport is proposed to occur via a hydrogen-bonded anionic glycine hemiaminal/imine, with control experiments supporting the role of hemiaminal/imine in the observed facilitated glycine transport Finally, the issue of electrogenic/electroneutral transport mechanisms and potential proton or hydroxide transport for synthetic anionophores were examined. It is shown that depending on acidity, many synthetic anionophores can facilitate electrogenic proton or hydroxide transport. However, two newly-developed small molecules are shown to promote chloride transport without significant proton/hydroxide transport (pH gradient dissipation) at low concentrations, essentially mimicking the electrogenic cationophore valinomycin. The chloride > proton/hydroxide selective anionophores feature encapsulation of chloride ion via weak hydrogen or halogen bonds.
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Sherwood, Thomas Walworth. "Dynamic Modulation of Acid-Sensing Ion Channels: Critical Factors in Acidotoxic Neuronal Death." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1291048378.
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Ting, Samuel T. "An Efficient Framework for Compressed Sensing Reconstruction of Highly Accelerated Dynamic Cardiac MRI." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1452164320.
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Keir, Matthew Stuart. "Robust Dynamic Orientation Sensing Using Accelerometers: Model-based Methods for Head Tracking in AR." Thesis, University of Canterbury. Mechanical Engineering, 2008. http://hdl.handle.net/10092/1640.
Full textAbstract:
Augmented reality (AR) systems that use head mounted displays to overlay synthetic imagery on the user's view of the real world require accurate viewpoint tracking for quality applications. However, achieving accurate registration is one of the most significant unsolved problems within AR systems, particularly during dynamic motions in unprepared environments. As a result, registration error is a major issue hindering the more widespread growth of AR applications.
The main objective for this thesis was to improve dynamic orientation tracking of the head using low-cost inertial sensors. The approach taken within this thesis was to extend the excellent static orientation sensing abilities of accelerometers to a dynamic case by utilising a model of head motion.
Head motion is modelled by an inverted pendulum, initially for one degree of rotational freedom, but later this is extended to a more general two dimensional case by including a translational freedom of the centre of rotation. However, the inverted pendulum model consists of an unstable coupled set of differential equations which cannot be solved by conventional solution approaches.
A unique method is developed which consists of a highly accurate approximated analytical solution to the full non linear tangential ODE. The major advantage of the analytical solution is that it allows a separation of the unstable transient part of the solution from the stable solution. The analytical solution is written directly in terms of the unknown initial conditions. Optimal initial conditions are found that remove the unstable transient part completely by utilising the independent radial ODE. Thus, leaving the required orientation.
The methods are validated experimentally with data collected using accelerometers and a physical inverted pendulum apparatus. A range of tests were performed demonstrating the stability of the methods and solution over time and the robust performance to increasing signal frequency, over the range expected for head motion.
The key advantage of this accelerometer model-based method is that the orientation remains registered to the gravitational vector, providing a drift free solution that outperforms existing, state of the art, gyroscope based methods. This proof of concept, uses low-cost accelerometer sensors to show significant potential to improve head tracking in dynamic AR environments, such as outdoors.
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Radhakrishnan, Aravind. "Android Phone Controlled Beagle Board Based PSCR in a Dynamic Spectrum Access Environment." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/35046.
Full textAbstract:
Public Safety Cognitive Radio (PSCR) is a Software Defined Radio(SDR) developed
by the Center for Wireless Telecommunications (CWT) at Virginia Tech. PSCR can
configure itself to interoperate with any public safety waveform it finds during the
scan procedure. It also offers users the capability to scan/classify both analog and
digital waveforms.
The current PSCR architecture can only run on a general purpose processor and
hence is not deployable to the public safety personnel. In the first part of this thesis
an Android based control application for the PSCR on a Beagle Board(BB) and the
GUI for the control application are developed. The Beagle Board is a low-cost, fan-
less single board computer that unleashes laptop-like performance and expandability.
The Android based Nexus One connected to the Beagle Board via USB is used to
control the Beagle Board and enable operations like scan, classify, talk, gateway etc.
In addition to the features that exist in the current PSCR a new feature that enables
interoperation with P25 (CPFSK modulation) protocol based radios is added. In this
effort of porting the PSCR to Beagle Board my contributions are the following (i)
communication protocol between the Beagle Board and the Nexus One (ii) PSCR
control application on the Android based Nexus One (iii) detection/classification of
P25 protocol based radios.
In the second part of this thesis, a prototype testbed of a Dynamic Spectrum Access
(DSA) broker that uses the Beagle Board PSCR based sensor/classifier is developed.
DSA in simple terms is a concept that lets the user without license (secondary user)
to a particular frequency access that frequency, when the licensed user (primary
user) is not using it. In the proposed testbed we have two Beagle Board based sen-
sor/classifiers that cooperatively scan the spectrum and report the results to the
central DSA broker. The DSA broker then identifies the frequency spectrum with-
out primary users and informs the secondary users about the free spectrum. The
secondary users can then communicate among each other using the frequency band
allocated by the DSA broker. When the primary user enters the spectrum occupied
by the secondary user, the DSA broker instructs the secondary user to use a different
spectrum. Based on the experiments conducted on the testbed setup in the CWT
lab environment, the average time taken by the DSA broker to detect the presence of
primary user is 0.636 secs and the average time taken for the secondary user to leave the frequency band that interferes with the primary user is 0.653 secs.<br>Master of Science
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Sease, Bradley Jason. "Data Reduction for Diverse Optical Observers through Fundamental Dynamic and Geometric Analysis." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/70923.
Full textAbstract:
Typical algorithms for processing unresolved space imagery from optical systems make broad assumptions about the expected behavior of the sensors during collection. While these techniques are often successful at data reduction for a particular mission, they rarely extend to sensors in different operating modes. Such specialized techniques therefore reduce the number of sensors able to contribute imagery. By approaching this problem with analysis of the fundamental dynamic equations and geometry at play, we can gain a deeper understanding into the behavior of both stars and space objects viewed through optical sensors. This type of analysis has the potential to enable data collection from a wider variety of sensors, increasing both the quantity and quality of data available for space object catalog maintenance. This dissertation will explore the implications of this approach to unresolved data processing. Sensor-level motion descriptions will be derived and applied to the problem of space object discrimination and tracking. Results of this processing pipeline as applied to both simulated and real optical data will be presented.<br>Ph. D.
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Fourie, Daniel Andries. "The dynamic modelling and control system of a tethered aerostat for remote sensing applications." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2984.
Full textAbstract:
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.<br>ENGLISH ABSTRACT: Aerostats and Stratolites could play a major role in expanding current satellite and other technologies
in the near future. A study was made on the development of aerostat platforms and the current
state of Stratolite development.
The aim was to develop an airship system that is capable of maintaining a specific position
regardless of the presence of wind. The various applications of such a geostationary platform are
discussed.
A dynamic model of an airship was developed and a simulation was implemented in software.
This was done to study the possibility of developing aerostats like these.
A tethered airship system was developed and built to demonstrate that it is possible to control
the position of an airship. The airship system uses current technology in an unique combination to
fulfil the requirement of remaining stationary despite the influence of wind.
Various control system design techniques were used to implement the controllers. Linear models
of the airship system were identified practically and used to design the controllers.
The controllers were tested in simulation as well as practically and the results of these tests
are given. It was concluded that there exists potential for the development of Stratolite systems,
although there exists a fair amount of challenges and obstacles that would need to be overcome
before this technology could be implemented.<br>AFRIKAANSE OPSOMMING: Aerostats en Stratolites kan ’n besondere rol speel in die uitbreiding van huidige sateliet- en ander
aardwaarnemingstoepassings. ’n Studie is gemaak oor die ontwikkeling van Aerostat platforms en
die huidige stand van Stratolite ontwikkeling.
Die mikpunt was om ’n lugskipstelsel te ontwikkel wat in staat is om ’n spesifieke posisie te
handhaaf ten spyte van die invloed van wind. Die verskeidenheid van toepassings, waarvoor so ’n
geostasionêre platform gebruik kan word, word genoem.
’n Dinamiese model van ’n lugskip is ontwikkel en die stelsel is in sagteware gesimuleer. Dit is
gedoen om die moontlikheid te ondersoek om sulke Aerostats in die toekoms te ontwikkel.
’n Lugskipstelsel, wat aan die grond geanker word met ’n kabel, is ontwerp en gebou. Die stelsel
is gedemonstreer en daar is bewys dat dit moontlik is om die posisie van die lugskip te beheer. Die
lugskip gebruik huidige tegnologie wat in ’n unieke kombinasie saamgevoeg is om te illustreer dat
dit moontlik is vir die lugskip om stasionêr te bly ten spyte van wind.
Verskeie beheerstelsels ontwerptegnieke is gebruik om die beheerders mee te implementeer. Lineêre
modelle van die lugskip is prakties geïdentifiseer en is gebruik om die beheerders te ontwerp.
Die lugskip se beheerders is in simulasie sowel as prakties getoets en die resultate van hierdie
toetse word gegee. Die projek bevestig dat daar ’n potensiaal bestaan vir die praktiese ontwikkeling
van Stratolite stelsels. Daar is egter ’n hele paar uitdagings en probleme wat eers uit die weg geruim
sal moet word, voordat hierdie tegnologie ’n alledaagse werklikheid sal word.
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Huang, Mengjun 1977. "Numerical methods for estimation of linear, discrete-time, dynamic systems in the block-angular form and applications in GPS." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82254.
Full textAbstract:
The objective of this thesis is to design numerical algorithms for estimation of linear discrete-time dynamic system models, which can be written in the block-angular form. These models arise in some applications, such as navigation or communication. The estimation problem for the standard linear discrete-time dynamic systems usually can be solved by using the Kalman filter. However, we realize that for our specific models applying the conventional Kalman filter algorithms is not efficient or may cause numerical instability. In this thesis, we present an approach of using the recursive least squares technique to compute the estimates of the system states. Our approach is computationally efficient because we take full account of the structures of the models and is numerically reliable because we use orthogonal transformations in the computation.<br>The general approach is then extended to positioning problem. We mainly consider the short-baseline relative positioning with combined code and carrier-phase measurements in global positioning system. Because of much more special structures existing in the mathematical models for positioning; we modify the general approach to further utilize these structures for efficiency. Fixing the integer ambiguity vector and handling its dimension change are also discussed. Finally, the real data tests are given to demonstrate the effectiveness of our algorithm.
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Rahimi, Fatemeh. "Selective Sensing in Hybrid Imagers with Vertically Integrated Perovskite Pixels." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7704.
Full textAbstract:
The rise of organometal halide perovskite materials with extremely intriguing properties have opened a new horizon in the design of high speed and low price optoelectronic devices. The bandgap in the crystalline structure of these materials can be easily tuned for various applications and their dominant non-excitonic dynamics eliminate the requirement of a bulk or heterostructure for charge carrier separation. These unique properties increase the photo-sensitivity of perovskite-based optoelectronics and provide them with a low time constant, resulting in high precision fast devices. Realization of perovskite-based devices translates directly to inexpensive and simplified architectures of optoelectronic systems.
In perovskite-based devices, costly silicon or wide bandgap semiconductor fabrication technology is largely replaced by solution processable methods. Their bandgap tunability allows the reduction of the required optical accessories and interconnects in optoelectronic components. For instance, a tuned perovskite-based detector can substitute a narrowband detecting system consisting of a conventional detector and its required optical accessories such as lenses and color filters. These properties of perovskite-based devices lead to the realization of inexpensive, low power and high-performance optoelectronic systems. In this work, the design of a narrowband, low noise, high performance and stable photodetector based on organic-inorganic hybrid perovskite structure is proposed. The full width at half maximum (FWHM) of the device would be in the nanometer range. The response of the device can be tuned using either different ratios of the lead salts or synthetic dyes (macromolecules) in the crystalline structure for color discrimination in machine vision and imaging applications.
Non-excitonic photocarrier generation, tunability of the optical bandgap and low voltage requirements for charge carrier generation are the keys to the utility of this optoelectronic device. The goals of this project were to identify the required functional materials (lead salts and synthetic dyes based on their molecular structures) and optimize their performance; the study of their effect on the charge collection narrowing mechanism and bandwidth specifications defined for detectivity, linear dynamic range (LDR) and photoresponse speed. To achieve these goals, it was proposed to study the light detection properties as well as spectroscopic and semiconductor parameter characteristics of fabricated devices. The design considerations of such devices are versatile and may be modulated for different applications.
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Komarov, Alexander. "New methods for detecting dynamic and thermodynamic characteristics of sea ice from radar remote sensing." Institute of Electrical and Electronics Engineers, 2014. http://hdl.handle.net/1993/30225.
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This dissertation presents new methods for detecting dynamic and thermodynamic characteristics of Arctic sea ice using radar remote sensing.
A new technique for sea ice motion detection from sequential satellite synthetic aperture radar (SAR) images was developed and thoroughly validated. The accuracy of the system is 0.43 km obtained from a comparison between SAR-derived ice motion vectors and in-situ sea ice beacon trajectories. For the first time, we evaluated ice motion tracking results derived from co-polarization (HH) and cross-polarization (HV) channels of RADARSAT-2 ScanSAR imagery and formulated a condition where the HV channel is more reliable than the HH channel for ice motion tracking. Sea ice motion is substantially controlled by surface winds. Two new models for ocean surface wind speed retrieval from C-band SAR data have been developed and validated based on a large body of statistics on buoy observations collocated and coincided with RADARSAT-1 and -2 ScanSAR images. The proposed models without wind direction input demonstrated a better accuracy than conventionally used algorithms. As a combination of the developed methods we designed a wind speed-ice motion product which can be a useful tool for studying sea ice dynamics processes in the marginal ice zone.
To effectively asses the thermodynamic properties of sea ice advanced tools for modeling electromagnetic (EM) wave scattering from rough natural surfaces are required. In this dissertation we present a new analytical formulation for EM wave scattering from rough boundaries interfacing inhomogeneous media based on the first-order approximation of the small perturbation method. Available solutions in the literature represent special cases of our general solution. The developed scattering theory was applied to experimental data collected at three stations (with different snow thicknesses) in the Beaufort Sea from the research icebreaker Amundsen during the Circumpolar Flaw Lead system study. Good agreement between the model and experimental data were observed for all three case studies. Both model and experimental radar backscatter coefficients were considerably higher for thin snow cover (4 cm) compared to the thick snow cover case (16 cm). Our findings suggest that, winter snow thickness retrieval may be possible from radar observations under particular scattering conditions.
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Hamshere, Marian Lindsay. "Statistical aspects of objects generated by dynamic processes at sea, detected by remote sensing techniques." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269655.
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Mekala, Murali. "A NOVEL DYNAMIC SPECTRUM SENSING APPROACH USING CROWDSOURCING FOR MULTI-RAT COEXISTENCE IN 5G NETWORKS." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/theses/2517.
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With ushering of 5G networks, dynamic spectrum sensing and allocation has become major area of research in recent times. There are some approaches-based on leveraging mobile users for spectrum sensing. However, none of the existing solution in literature takes into account both energy-efficient operations of sensing devices and their hardware limitations while allocating sensing task to mobile users. As spectrum sensing is a time-consuming and computation-intensive task, a practical crowdsensing based spectrum usage map creation strategy needs to consider the trade-off between execution time and completeness defined in terms of coverage of geographical/service area as well as spectrum bands. In this approach, we are going to create a spectrum usage database for each location with each sensed channel marked as idle, busy or undermined. An algorithm is proposed based on energy and hardware limitation of sensing devices for allocation of crowdsensing tasks.
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Velasco, Ivann Civi Lomas-E. "Dynamic Body Armor Shape Sensing Using Fiber Bragg Gratings and Photoassisted Silicon Wire-EDM Machining." BYU ScholarsArchive, 2021. https://scholarsarchive.byu.edu/etd/9201.
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In this thesis, a method to improve survivability is developed for fiber Bragg gratings under high velocity impact in dynamic body armor shape sensing applications by encasing the fiber in silicone. Utilizing the slipping of the fiber within the silicone channel, a proportionality relationship between the strain of the fiber to the acceleration of the impacting projectile is found and is used to obtain the rate of the back-face deformation. A hybrid model is developed to handle errors caused by the stick-slip of the fiber by fitting an inverse exponential to stuck sections found in a captured strain profile and double integrated to transform the stuck section to its equivalent slipping. Displacement errors below 10% was achieved using the hybrid model. A graphical user interface with a step-by-step walkthrough and a fiber Bragg grating interrogation system was designed for test engineers to utilize this technology. Test engineers from the Army Test Center in Aberdeen, MD were trained on this technology and successfully captured and processed shots using this technology. A method for cutting Silicon through wire-EDM machining is developed by utilizing the photoconductive properties of Silicon. Cut rates for unilluminated and illuminated Silicon was compared and a 3x faster cut was achieved on the illuminated cuts.
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Fu, Gen. "Full Field Reconstruction Enhanced With Operational Modal Analysis and Compressed Sensing for General Dynamic Loading." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/103741.
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In most applications, the structure components have to be tested under different loading conditions before being placed in operation. A reliable and low cost measuring technique is desirable. However, most currently employed measuring approaches can only provide the structural response at several discrete locations. The accuracy of the measurements varies with the location and orientation of the sensors. Practically, it is not possible to place sensors at all the critical locations for different excitations. Therefore, an approach that derives the full field response using a limited set of measured data is desirable. In contrast to experimental full field measurement techniques, the expansion approach involves analytically expanding the limited measurements to all the degrees of freedom of the structure. Among all the analytical methods, the modal expansion method is computationally efficient and thus more suitable for real time expansion of measured data. In this method, the full-field response is approximated by the linear combination of mode shapes. In previous studies, the modal expansion method is limited by errors from mode aliasing, inaccuracy of the calculated mode shapes and the noise in measurements.
In order to overcome these limitations, the modal expansion method is enhanced by mode selection and error compensation in this study. First, the key parameters used in modal expansion method were analyzed using a cantilever beam model and a method for optimal placement of sensors was developed. A mode selection method and error compensation method based on operation modal analysis and adaptive compressed sensing techniques were then developed to reduce the effects of mode aliasing, mode shape inaccuracy and measurement noise. The developed approach was further tested virtually using a numerical model of rotor 67. The numerical model was created using a two-way coupled fluid structure interaction technique. By developing these methods, the enhanced modal expansion approach can provide full field response for structures under different load conditions. Compared to the traditional modal expansion method, it can expand the data with high noise and under general dynamic loading.<br>Doctor of Philosophy<br>Accurate knowledge of the strain and stress at critical locations of a given structure is crucial when assessing its integrity. However, currently employed measuring approaches can only provide the structural response at several discrete locations. Practically, it is not possible to place sensors at all the critical locations for different excitations. Therefore, an approach that derives the full field response using a limited set of measured data is desirable. Compared to experimental full field measurement techniques, the expansion approach is focused on analytically expanding the limited measurements to all the degrees of freedom of the structure. Among all the analytical methods, the modal expansion method is computationally efficient and thus more suitable for real-time expansion of measured data. The current modal expansion method is limited by errors from mode aliasing, inaccuracy of the mode shapes, and the noise in measurements. Therefore, an enhanced method is proposed to overcome these shortcomings of the modal expansion. The following objectives are accomplished in this study: 1) Develop a method for optimal placement of sensors for modal expansion; 2) Eliminate the mode aliasing effects by determining the significance of participated modes using operational modal analysis techniques; 3) Compensate for the noise in measurements and computational model by implementing the compressed sensing approach. After accomplishing these goals, the developed approach is able to provide full field response for structures under different load conditions. Compared to the traditional modal expansion method, it can expand the data under dynamic loading; it also shows promise in reducing the effects of noise and errors. The developed approach is numerically tested using fluid-structure interaction model of rotor 67 fan blade.
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Simpson, Oluyomi. "Optimal cooperative spectrum sensing for cognitive radio." Thesis, University of Hertfordshire, 2016. http://hdl.handle.net/2299/17246.
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The rapid increasing interest in wireless communication has led to the continuous development of wireless devices and technologies. The modern convergence and interoperability of wireless technologies has further increased the amount of services that can be provided, leading to the substantial demand for access to the radio frequency spectrum in an efficient manner. Cognitive radio (CR) an innovative concept of reusing licensed spectrum in an opportunistic manner promises to overcome the evident spectrum underutilization caused by the inflexible spectrum allocation. Spectrum sensing in an unswerving and proficient manner is essential to CR. Cooperation amongst spectrum sensing devices are vital when CR systems are experiencing deep shadowing and in a fading environment. In this thesis, cooperative spectrum sensing (CSS) schemes have been designed to optimize detection performance in an efficient and implementable manner taking into consideration: diversity performance, detection accuracy, low complexity, and reporting channel bandwidth reduction. The thesis first investigates state of the art spectrums sensing algorithms in CR. Comparative analysis and simulation results highlights the different pros, cons and performance criteria of a practical CSS scheme leading to the problem formulation of the thesis. Motivated by the problem of diversity performance in a CR network, the thesis then focuses on designing a novel relay based CSS architecture for CR. A major cooperative transmission protocol with low complexity and overhead - Amplify and Forward (AF) cooperative protocol and an improved double energy detection scheme in a single relay and multiple cognitive relay networks are designed. Simulation results demonstrated that the developed algorithm is capable of reducing the error of missed detection and improving detection probability of a primary user (PU). To improve spectrum sensing reliability while increasing agility, a CSS scheme based on evidence theory is next considered in this thesis. This focuses on a data fusion combination rule. The combination of conflicting evidences from secondary users (SUs) with the classical Dempster Shafter (DS) theory rule may produce counter-intuitive results when combining SUs sensing data leading to poor CSS performance. In order to overcome and minimise the effect of the counter-intuitive results, and to enhance performance of the CSS system, a novel state of the art evidence based decision fusion scheme is developed. The proposed approach is based on the credibility of evidence and a dissociability degree measure of the SUs sensing data evidence. Simulation results illustrate the proposed scheme improves detection performance and reduces error probability when compared to other related evidence based schemes under robust practcial scenarios. Finally, motivated by the need for a low complexity and minmum bandwidth reporting channels which can be significant in high data rate applications, novel CSS quantization schemes are proposed. Quantization methods are considered for a maximum likelihood estimation (MLE) and an evidence based CSS scheme. For the MLE based CSS, a novel uniform and optimal output entropy quantization scheme is proposed to provide fewer overhead complexities and improved throughput. While for the Evidence based CSS scheme, a scheme that quantizes the basic probability Assignment (BPA) data at each SU before being sent to the FC is designed. The proposed scheme takes into consideration the characteristics of the hypothesis distribution under diverse signal-to-noise ratio (SNR) of the PU signal based on the optimal output entropy. Simulation results demonstrate that the proposed quantization CSS scheme improves sensing performance with minimum number of quantized bits when compared to other related approaches.
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Evangelisti, Linn, and Johan Sundell. "Playing the Innovation Game : Developing the Community Sensing Capability." Thesis, Uppsala universitet, Företagsekonomiska institutionen, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355298.
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The remarkable growth of the video game industry has triggered an interest for the capabilities that video game companies need in order to seize opportunities in the market. Companies that continuously provide product innovations are arguably better equipped to succeed in the dynamic, digitized video game landscape. Market sensing capabilities have been brought forward as particularly useful in environments with these characteristics and research suggests that user communities could be critical sources of external knowledge for video game companies. Hence, the aim of this study is to provide a framework where these concepts are combined into a unified dynamic capability, Community Sensing Capability, and to quantitatively test its effect on product innovativeness. An interview-administered questionnaire was used to gather data, resulting in a sample of 72 observations. The capability builds on three different sub-processes; sensing, sensemaking and response. Reliable measurements were developed for Community Sensing Capability, sensing and response respectively. The regression analysis indicate that sensing and response are positively related to product innovativeness, while Community Sensing Capability is not significantly related. This study contributes to literature by shedding light on a new phenomenon and giving initial insights to how the Community Sensing Capability can be exploited in innovation processes.
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Medina, Medina Esunly. "An approach to pervasive monitoring in dynamic learning contexts : data sensing, communication support and awareness provision." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/387553.
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It is within the capabilities of current technology to support the emerging learning paradigms. These paradigms suggest that today’s learning activities and environments are pervas ive and require a higher level of dynamism than the traditional learning contexts. Therefore, we have to rethink our approach to learning and use technology not only as a digital information support, but also as an instrument to reinforce knowledge, foster collaboration, promote creativity and provide richer learning experiences.
Particularly, this thesis was motivated by the rapidly growing number of smartphone users and the fact that these devices are increasingly becoming more and more resource-rich, in terms of their communication and sensing technologies, display capabilities battery autonomy, etc. Hence, this dissertation benefits from the ubiquity and development of mobile technology, aiming to bridge the gap between the challenges posed by modern learning requirements and the capabilities of current technology.
The sensors embedded in smartphones can be used to capture diverse behavioural and social aspects of the users. For example, using microphone and Bluetooth is possible to identify conversation patterns, discover users in proximity and detect face-to-face meetings. This fact opens up exciting possibilities to monitor the behaviour of the user and to provide meaningful feedback. This feedback offers useful information that can help people be aware of and reflect on their behaviour and its effects, and take the necessary actions to improve them.
Consequently, we propose a pervasive monitoring system that take advantage of the capabilities of modern smartphones, us ing them to s upport the awarenes s provis ion about as pects of the activities that take place in today’s pervas ive learning environments. This pervasive monitoring system provides (i) an autonomous sensing platform to capture complex information about processes and interactions that take place across multiple learning environments, (ii) an on-demand and s elf-m anaged communication infras tructure, and (ii) a dis play facility to provide “awarenes s inform ation” to the s tudents and/or lecturers.
For the proposed system, we followed a research approach that have three main components. First, the description of a generalized framework for pervasive sensing that enables collaborative sensing interactions between smartphones and other types of devices. By allowing complex data capture interactions with diverse remote sensors, devices and data sources, this framework allows to improve the information quality while saving energy in the local device. Second, the evaluation, through a real-world deployment, of the suitability of ad hoc networks to support the diverse communication processes required for pervasive monitoring. This component also includes a method to improve the scalability and reduce the costs of these networks. Third, the design of two awareness mechanisms to allow flexible provision of information in dynamic and heterogeneous learning contexts. These mechanisms rely on the use of smartphones as adaptable devices that can be used directly as awareness displays or as communication bridges to enable interaction with other remote displays available in the environment.
Diverse aspects of the proposed system were evaluated through a number of simulations, real-world experiments, user studies and prototype evaluations. The experimental evaluation of the data capture and communication aspects of the system provided empirical evidence of the usefulness and suitability of the proposed approach to support the development of pervasive monitoring solutions. In addition, the proof-of-concept deployments of the proposed awareness mechanisms, performed in both laboratory and real-world learning environments, provided quantitative and qualitative indicators that such mechanisms improve the quality of the awareness information and the user experience<br>La tecnología moderna tiene capacidad de dar apoyo a los paradigmas de aprendizaje emergentes. Estos paradigmas sugieren que las actividades de aprendizaje actuales, caracterizadas por la ubicuidad de entornos, son más dinámicas y complejas que los contextos de aprendizaje tradicionales. Por tanto, tenemos que reformular nuestro acercamiento al aprendizaje, consiguiendo que la tecnología sirva no solo como mero soporte de información, sino como medio para reforzar el conocimiento, fomentar la colaboración, estimular la creatividad y proporcionar experiencias de aprendizaje enriquecedoras.
Esta tesis doctoral está motivada por el vertiginoso crecimiento de usuarios de smartphones y el hecho de que estos son cada vez más potentes en cuanto a tecnologías de comunicación, sensores, displays, autonomía energética, etc. Por tanto, esta tesis aprovecha la ubicuidad y el desarrollo de esta tecnología, con el objetivo de reducir la brecha entre los desafíos del aprendizaje moderno y las capacidades de la tecnología actual.
Los sensores integrados en los smartphones pueden ser utilizados para reconocer diversos aspectos del comportamiento individual y social de los usuarios. Por ejemplo, a través del micrófono y el Bluetooth, es posible determinar patrones de conversación, encontrar usuarios cercanos y detectar reuniones presenciales. Este hecho abre un interesante abanico de posibilidades, pudiendo monitorizar aspectos del comportamiento del usuario y proveer un feedback significativo. Dicho feedback, puede ayudar a los usuarios a reflexionar sobre su comportamiento y los efectos que provoca, con el fin de tomar medidas necesarias para mejorarlo.
Proponemos un sistema de monitorización generalizado que aproveche las capacidades de los smartphones para proporcionar información a los usuarios, ayudándolos a percibir y tomar conciencia sobre diversos aspectos de las actividades que se desarrollan en contextos de aprendizaje modernos. Este sistema ofrece: (i) una plataforma de detección autónoma, que captura información compleja sobre los procesos e interacciones de aprendizaje; (ii) una infraestructura de comunicación autogestionable y; (iii) un servicio de visualización que provee “información de percepción” a estudiantes y/o profesores.
Para la elaboración de este sistema nos hemos centrado en tres áreas de investigación. Primero, la descripción de una infraestructura de detección generalizada, que facilita interacciones entre smartphones y otros dispositivos. Al permitir interacciones complejas para la captura de datos entre diversos sensores, dispositivos y fuentes de datos remotos, esta infraestructura consigue mejorar la calidad de la información y ahorrar energía en el dispositivo local. Segundo, la evaluación, a través de pruebas reales, de la idoneidad de las redes ad hoc como apoyo de los diversos procesos de comunicación requeridos en la monitorización generalizada. Este área incluye un método que incrementa la escalabilidad y
reduce el coste de estas redes. Tercero, el diseño de dos mecanismos de percepción que permiten la provisión flexible de información en contextos de aprendizaje dinámicos y heterogéneos. Estos mecanismos descansan en la versatilidad de los smartphones, que pueden ser utilizados directamente como displays de percepción o como puentes de comunicación que habilitan la interacción con otros displays remotos del entorno.
Diferentes aspectos del sistema propuesto han sido evaluados a través de simulaciones, experimentos reales, estudios de usuarios y evaluaciones de prototipos. La evaluación experimental proporcionó evidencia empírica de la idoneidad del sistema para apoyar el desarrollo de soluciones de monitorización generalizadas. Además, las pruebas de concepto realizadas tanto en entornos de aprendizajes reales como en el laboratorio, aportaron indicadores cuantitativos y cualitativos de que estos mecanismos mejoran la calidad de la información de percepción y la experiencia del usuario.
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Cooper, Reginald Larenzo. "Sensing and Learning Channel State Information in a Dynamic Wireless Environment with Cognitive Radios and Networks." Research Showcase @ CMU, 2012. http://repository.cmu.edu/dissertations/211.
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Sensing and learning channel state information CSI in a dynamic wireless environment DWE has not been a focus of the cognitive radio and network research. The focus has been on obtaining spectral resource information about the spectrum availability i.e. spectrum sensing for dynamic spectrum access or how to adapt radios and networks in a way that improves the effectiveness of the radio networks, for example rate adaptation. In most of these cases it is assume that the CSI is already known or it is obtained from a method that directly measures the spectrum of interest through channel estimation, fading prediction or forecasting, blind estimation, and many others. In DWEs the wireless channel may change at high rates (i.e. fast fading), and methods that directly measure the channel will not provide accurate and timely CSI needed for a cognitive radio or network.
In this thesis a counterintuitive method is presented, indirect channel measurements. Indirect channel measuring is a technique used to determine the transfer function of a desired part of the RF spectrum, which spans several coherence bandwidths, without directly sending a signal through the spectrum of interest, but indirectly through adjacent spectrum. The indirect measuring of the channel has the ability to improve the timeliness and accuracy associated with the obtainment of the CSI in DWEs when using cognitive radios and networks.
This thesis will explain the indirect channel measurements ICM research and how it can be used in cognitive radio networks for SISO rate adaptation in dynamic wireless environments. Included will be an analytical and empirical analysis of the performance of the ICM technique and other comparable and contrasting techniques. This thesis will also show which technique is best suited for a particular set of parameters for a given dynamic wireless environment. A contextual explanation will also be given to provide a visual picture of a cognitive radio network that will be able to implement the ICM technique using rate adaptation, and its ability to be implemented in hardware.
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Lee, Junghyun Ph D. Massachusetts Institute of Technology. "Dynamic and geometric control of electronic spins in diamond for quantum sensing and quantum information science." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119108.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2018.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 163-172).<br>In recent years, the nitrogen-vacancy (NV) color center in diamond, electronic spin defects embedded in a solid-state system, has emerged as a promising platform for quantum sensing and quantum information science in ambient temperature. Its capability of robust but high-precision spin control allows the NV center to be not only a useful atomic-scale magnetic field sensor but also an attractive building block for quantum processors. In this dissertation, I present novel schemes to dynamically and geometrically control NV spins for improved magnetic field sensing and studies of spin dynamics. First, dynamic NV phase control is synchronized with an external oscillating magnetic field, enabling single and ensemble NV AC magnetometry spectral resolution approaching sub-mHz. This protocol allows NV spins to sense an AC field spectral resolution beyond the inverse of NV spin lifetime. Also, dynamic control via dressed states of the NV spin is shown to provide effective tuning of the dipolar coupling between spins. In strongly interacting NV spin ensembles, this robust tool can be used to change the interaction dynamics. Second, geometric phase control is used to sense an external static magnetic field, improving detection sensitivity and field range. Especially, geometric phase magnetometry provides a 100-fold improvement of field range compared to conventional Ramsey magnetometry. Moreover, geometric phase control is used to observe the change of a topological state via measuring the Chern number, showing that an NV spin can serve as a tool for simple quantum simulations. Finally, I discuss the possibilities of combining the presented schemes with other quantum techniques to realize further interesting applications in future work.<br>by Junghyun Lee.<br>Ph. D.
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Hamid, Mohamed. "On Finding Spectrum Opportunities in Cognitive Radios : Spectrum Sensing and Geo-locations Database." Licentiate thesis, KTH, Kommunikationssystem, CoS, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-110107.
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The spectacular growth in wireless services imposes scarcity in term of the available radio spectrum. A solution to overcome this scarcity is to adopt what so called cognitive radio based on dynamic spectrum access. With dynamic spectrum access, secondary (unlicensed) users can access spectrum owned by primary (licensed) users when it is temporally and/or geographically unused. This unused spectrum is termed as spectrum opportunity. Finding these spectrum opportunities related aspects are studied in this thesis where two approaches of finding spectrum opportunities, namely spectrum sensing and geo-locations databases are considered. In spectrum sensing arena, two topics are covered, blind spectrum sensing and sensing time and periodic sensing interval optimization. For blind spectrum sensing, a spectrum scanner based on maximum minimum eigenvalues detector and frequency domain rectangular filtering is developed. The measurements show that the proposed scanner outperforms the energy detector scanner in terms of the probability of detection. Continuing in blind spectrum sensing, a novel blind spectrum sensing technique based on discriminant analysis called spectrum discriminator has been developed in this thesis. Spectrum discriminator has been further developed to peel off multiple primary users with different transmission power from a wideband sensed spectrum. The spectrum discriminator performance is measured and compared with the maximum minimum eigenvalues detector in terms of the probability of false alarm, the probability of detection and the sensing time. For sensing time and periodic sensing interval optimization, a new approach that aims at maximizing the probability of right detection, the transmission efficiency and the captured opportunities is proposed and simulated. The proposed approach optimizes the sensing time and the periodic sensing interval iteratively. Additionally, the periodic sensing intervals for multiple channels are optimized to achieve as low sensing overhead and unexplored opportunities as possible for a multi channels system. The thesis considers radar bands and TV broadcasting bands to adopt geo-locations databases for spectrum opportunities. For radar bands, the possibility of spectrum sharing with secondary users in L, S and C bands is investigated. The simulation results show that band sharing is possible with more spectrum opportunities offered by C band than S and L band which comes as the least one. For the TV broadcasting bands, the thesis treats the power assignment for secondary users operate in Gävle area, Sweden. Furthermore, the interference that the TV transmitter would cause to the secondary users is measured in different locations in the same area.<br><p>QC 20130114</p><br>QUASAR
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Liu, Zhen. "Reconstruction and Control of Tip Position and Dynamic Sensing of Interaction Force for Micro-Cantilever to Enable High Speed and High Resolution Dynamic Atomic Force Microscopy." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1483629656167247.
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Sun, Fanping. "Piezoelectric active sensor and electric impedance approach for structural dynamic measurement." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-08292008-063023/.
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