Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 218 for “"Duty Cycle"”.
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Circuits and protocols for low duty cycle wireless systems
… efficiency is needed. Additionally, aggressive duty cycling is needed to operate these IoT devices in severely energy-constrained applications. Wireless communication, which consumes a large fraction of the power in these devices, is the primary focus of this thesis. We present circuit (active …
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Dynamic duty cycle mechnism for mobility in wirless sensor networks
… The aim of this project is to design a dynamic duty cycle mechanism for mobility as well as fixed nodes within wireless sensor networks through a Contiki simulator through which power consumption, Packet Delivery Ratio (PDR) and duty cycle aremeasured by nodes under the mobility and fixed …
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The Effects of Vortex Generator Jet Frequency, Duty Cycle, and Phase on Separation Bubble Dynamics
… with different frequencies, jet durations, and duty cycles. The mechanisms responsible for boundary layer separation control were shown to be a combination of boundary layer transition and streamwise vortical structures. Jet duration and relaxation time were important VGJ characteristics in …
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The role of echolocation in communication in a high duty cycle echolocating bat, Rhinolophus clivosus (Chiroptera: Rhinolophidae): an experimental approach
Acoustic communication plays a pivotal role in species recognition across a number of taxa. Species must therefore maintain discrete acoustic signatures to facilitate communication and avoid misidentification. The Acoustic Communication Hypothesis (ACH) thus proposes that in multispecies …
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Behavioural evidence for the perception of individual identity and gender via the echolocation calls of a high duty cycle bat, Rhinolophus clivosus
… habituation-dishabituation experiments, a high duty cycle echolocating bat, Rhinolophus clivosus, dishabituated significantly when echolocation calls of a different gender or individual were played to the habituation. Strong individual and gender signatures but weak geographic signatures were …
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Benefits of battery-uItracapacitor hybrid energy storage systems
… load profiles: 1. 436 ms pulse period, 10% duty cycle, 8 A pulse amplitude 2. 436 ms pulse period, 25% duty cycle, 8 A pulse amplitude 3. 436 ms pulse period, 10% duty cycle, 16 A pulse amplitude 4. 436 ms pulse period, 25% duty cycle, 16 A pulse amplitude Circuit models are created to …
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Chemical And Biological Treatment Of Mature Landfill Leachate
… voltage is needed. This decrease causes small duty cycle that is accompanied by critical problems which impairs the efficiency. Therefore, these problems need to be addressed. Transformer-based non-isolated topologies are not new approaches to extend the duty cycle and avoid the associated …
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Photoexcited hypersonic surface acoustic waves propagating under periodic metal grating
… fabricated on them for varying periods and duty cycles of the grating (coverage ratio of Al on Si). Modeling the optical absorption of the laser and the resultant thermoelastic strain reveals requirements on the elastic and the thermal properties of the grating and the substrate for …
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Some design consideration of switching regulator using current-injected control
… a power stage, an error processor and a duty cycle pulse modulator. Two design constraints and the effects of various critical control circuit parameters are pinpointed and the analysis-based design guidelines are established in order to optimize the switching regulator performances. In …
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Longissimus muscle fatigue and injury response due to electrical stimulation with varied work/rest ratios
… that the lack of adequate rest within a work cycle may contribute to muscle fatigue and ultimately injury. The aim of the current study is to determine the duty cycle and cycle time combinations that contribute to muscle fatigue and injury.</p> <p>Stimulating and recording electrodes were …
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Power Converter Design for Maximum Power Transfer and Battery Management for Vibration-Based Energy Harvesting on Commercial Railcars
… to maintain a constant input impedance, the duty cycle of the power converter must be fixed. Conversely, output regulation requires the duty cycle to change dynamically. Consequently, there is a tradeoff between extracting maximum power and prolonging the battery life cycle. The proposed …
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The reduction of supersonic jet noise using pulsed microjet injection
… water, at frequencies of 1, 5 and 10 Hz and at duty cycles of 50 and 75%. For comparison, acoustic data were also collected from the jet while the microjets were injecting steadily at a constant pressure. The results led to the following two conclusions: for injection at a given mass flow rate, …
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Design and analysis of energy-efficient media access control protocols in wireless sensor networks. Design and analysis of MAC layer protocols using low duty cycle technique to improve energy efficient and enhance communication performance in wireless sensor networks.
… under different traffic loads and varying duty cycle values. Results have shown that the proposed solutions are able to significantly enhance the performance of WSNs by improving the energy efficiency, increasing the system throughput and reducing the communication delay.
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New Methods for the Detection and Interception of Unknown, Frequency-Hopped Waveforms
… suboptimal scheme is developed that trades off duty cycle for performance, and a technique for estimating hop frequency is developed. The performance of the optimal and suboptimal detectors is quantified. For the suboptimal scheme, the trade-off with duty cycle is studied. The reliability of the …
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Cluster based jamming and countermeasures for wireless sensor network MAC protocols
… vulnerabilities. In particular, a regular duty cycle makes a node vulnerable to periodic jamming attacks. This vulnerability limits the use of use of a WSN in applications requiring high levels of security. We present a new WSN MAC protocol, RSMAC (Random Sleep MAC) that is designed to …
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Modeling and Stability Analysis for Multiphase Constant On-Time Control With Phase Overlapping
… overlapping becomes inevitable in the practical duty range. However, currently, there is no good small-signal model to analyze stability and design high-bandwidth control loops for multiphase COT buck converters operating under phase-overlapping conditions. To address this issue, this …
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An Exploration of Secondary Fuel Injection as Actuation for Control of Combustion Instabilities in a Laminar Premixed Tube Combustor
… the innovative fuel injection technique is a duty cycle modulation technique that was a prime contributor to the success of the control system. This method enabled the system to be controlled at conditions that were uncontrollable with a fixed duty cycle. The overall result was a 35 dB …
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Cosmology with Velocity Dispersion based Counts of Groups and the Effect of AGN Feedback on Host Galaxy Morphology
… galaxies maintain this condition is the duty cycle hypothesis. This hypothesis invokes AGN feedback from low luminosity radio-loud AGN (LERGs) to deposit mechanical heating into the intergalactic medium, thus preventing star formation. I test this hypothesis by comparing the half-light …
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Development of novel nano-coating applied on metal stencils used in the manufacture of printed circuit boards and similar products
… is performed. The physical parameters, duty cycle and current density of Ni-Co coating are varied in order to obtain the optimum properties. The duty cycle is varied from 20% to 100% with 20% increment and current density 3 A/dm2 to 9 A/dm2 with an increment of 3 A/dm2. The other …
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Acoustical characterization of glacierized fjords
… in Disenchantment Bay. The effect of recording duty cycle on sampling the spectral and temporal variability of the acoustic field was analyzed by comparing clustered spectral shapes and observations from full and reduced duty cycle recordings of varying length from 1% to 99% of the full …
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