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 15 of 15 for “"R-ratio"”.
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Required force level and isometric tracking
… task was used to investigated the effects of alterations in the speed of target movement and the control/response ratio (C/R ratio) on human tracking performance. The speed of target movement was varied through different frequency sine-wave forcing functions. The C/R ratio was controlled by …
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Fatigue Crack Growth Analysis with Finite Element Methods and a Monte Carlo Simulation
… C.M. Hudson in a 1969 NASA report studying the R-ratio effects on crack growth in 7075-T6 aluminum alloy. The Paris, Walker, and Forman fatigue crack growth models were fit the experimental data. The Walker equation best fit the data since it incorporated R-ratio effects and had a similar Root …
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Optimization of Rib-To-Deck Welds for Steel Orthotropic Bridge Decks
… need to be fabricated as one-sided partial penetration welds with minimum penetration of 80% into the rib wall thickness. However considering the thin rib plate thickness, it is very difficult to achieve this penetration without a "melt-through" or "blow-through" defect. Large cost has been …
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Harmonic emissions assessment for common DC and AC electric vehicle charging station architectures
… of charging and PQ, and the star-delta configuration of Distribution Transformer (DT) connections provides lower harmonics. • Comparison of two control strategies for the VSC using UTC and dq-SRF control strategies: - results show that UTC strategy performs better than dq-SRF method for control …
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Quasi-Static Tensile and Fatigue Behavior of Extrusion Additive Manufactured ULTEM 9085
… and 20% of the ultimate tensile stress with an R-ratio of 0.1 for the build orientation XZY. The contour thickness and raster thickness were increased to 0.030 in. to determine the effect of those two build parameters on tension-tension fatigue life. Next, the modified Goodman approach was used to …
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Long Term Durability of Glass Reinforced Composites
… discusses the effects that mean stress and R-ratio have on the fatigue performance of the same material. Qualitative and quantitative differences are seen in the performance as a function of the loading ratio. A residual strength based life prediction model developed at Virginia Tech is …
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Predicting drying times of some Burmese woods for two types of solar kilns
… = average daily solar insolation in Btu/ft² R = ratio of total solar energy incident on the collector cover to total energy available to the system V = green volume of lumber in ft³ SG = green specific gravity of lumber Ti = average initial temperature inside the kiln in °F A comparison of the …
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MECHANISTIC STUDY OF CRACK INITIATION AND PROPAGATION IN CROSSLINKED ULTRA HIGH MOLECULAR WEIGHT POLYETHYLENES (UHMWPE) SUBJECTED TO STATIC AND CYCLIC LOADING
… crack propagation. Frequency, waveform and R-ratio were varied between test conditions to determine the governing factor for fatigue crack propagation. It was found that the crack propagation velocity in crosslinked UHMWPE is driven by peak stress intensity (Kmax) in a loading cycle. The …
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Intelligent and Robust Control Strategy for Improving Microgrids Operation and Stability
… caused dispersed installation of distributed generation (DG) units in power systems. Microgrid (MG) concept is considered as the best solution to address the resiliency issue of future modern power systems, which are expected to receive a considerable amount of power through inverter-interfaced DG …
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Investigation of thermal effects on fatigue crack closure using multiscale digital image correlation experiments
… throughout the experiments along with an R ratio of 0.05. Isothermal experiments were performed at room temperature (RT), 300 °C, and 550 °C. It was found through the microscale experiments that the level of measured crack closure increased as the crack tip was approached, as has been seen …
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Dynamic Model Based Novel Findings in Power Systems Analysis and Frequency Measurement Verification
… usefulness using the simulation. In the study on ratio of the equivalent reactance and resistance of the bulk power systems, the simulation results give us the more correct value of X/R of the bulk power system, which can explain why the active power compensation is also important in voltage …
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Assessment of oxygen sources and sinks in the northern Gulf of Mexico using stable oxygen isotopes
… oxygen dynamics. Yet, based on oxygen concentration measurements alone, it is difficult to separate the effects of biological factors from physical factors. To address this problem, I used a dual budget approach to assess the importance of oxygen sources and sinks on the Louisiana continental …
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Creep and Fatigue Crack Growth in Incoloy Alloy 800H
Made available in DSpace on 2017-07-06T18:48:35Z (GMT). No. of bitstreams: 3 Hour_Kai-Youarn_MS.pdf: 68542035 bytes, checksum: 18c25c093de49ccf4c5fdd0090c5d1e5 (MD5) Hour_Kai-Youarn_MS_ABS.pdf: 914057 bytes, checksum: be05bed33a78bbb0e1e7ea54f2cdc406 (MD5) license.txt: 4813 bytes, checksum: …
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The Plasma, Whole Blood and Intracellular Concentrations of Antiretroviral Agents in South African Children Receiving Combination Antiretroviral Therapy with and without Concomitant Antitubercular Treatment
… indicated. Efavirenz and lopinavir/ritonavir (ratio 1:1) as part of antiretroviral therapy are used in combination with rifampicin-based antitubercular treatment in South African TB/HIV co-infected children. Adult studies show that concomitant rifampicin significantly reduces efavirenz and …
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Assessing water quality in Sultanate of Oman using a newly developed dynamic speciation technique
… 1 day, 2 days, 4 days and 6 days) and oil concentrations (1, 3, 5, 7, 25 OWR% (oil water ratio), w/v). It was demonstrated that organic ligands from crude oil influenced the lability of trace metals. The combination of five types of DGT devices (OP-DGT, RG-DGT, (dialysis 1000Da)-DG, (dialysis …