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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1021

Isometric Force Production Symmetry and Jumping Performance in Collegiate Athletes

Bailey, Chris A., Sato, Kimitake, Alexander, Ryan, Chiang, Chieh-Ying, Stone, Michael H. 01 January 2013 (has links)
Objectives: The purpose of this study was to identify the relationship between isometric force production symmetry and jumping performance in weighted and un-weighted static and countermovement jumps (SJ and CMJ). Design: Bivariate correlation between isometric force production symmetry and vertical jump performance variables. Methods: Collegiate athletes were evaluated for this study (n=36). Subjects performed SJ, CMJ, and isometric mid-thigh pulls (IMTP). Jumps were analyzed for jump height (JH) and peak power (PP). IMTP was analyzed for peak force (PF) for left and right sides, and values were calculated to produce a peak force symmetry index (PF-SI) score. Correlational statistics were performed examining the relationship between PF-SI and jump variables. Results: Moderate statistically significant negative correlations were observed between PF-SI and all jump variables, indicating that as asymmetry increases jump performance decreases. SJ correlations weakened in weighted conditions (JH r=-0.52 @ 0 kg/r=-0.39 @ 20 kg, PP r=-0.43 @ 0 kg/r=-0.34 @ 20 kg), but CMJ produced similar correlations for both conditions (JH r=-0.47 @ 0 kg/r=-0.49 @ 20 kg, PP r=-0.28 @ 0 kg/r=-0.34 @ 20 kg). Unlike the SJ, which only contains the propulsive or concentric portion of the jump, the CMJ also contains the eccentric portion and performance contributions of the stretch-shortening cycle (SSC). The addition of the SSC may play a role in the maintaining the magnitude of asymmetry in the CMJ weighted condition. Conclusions: The results indicate that force production asymmetry may be detrimental to bilateral vertical jumping performance. The findings should be considered for further investigation on sport-specific tasks.
1022

The Use of an Optical Measurement System to Monitor Sports Performance

Magrum, Eric D., Wagle, John P., DeWeese, Brad H., Sato, Kimitake, Stone, Michael H. 01 January 2018 (has links)
The purpose of this study was to compare ground contact time between an optical measurement system and a force platform. Participants in this study included six collegiate level athletes who performed drop jumps and sprint strike steps for a total of 15 repetitions each. Ground contact data was simultaneously collected from an optical measurement system and a force platform, at a sampling frequency of 1000 Hz. Data was then analyzed with Pearson’s correlation and paired sample t-tests. The measures from the optical measurement system were found to be significantly higher (p < 0.001) than measures from the force platform in both conditions. Although significantly different, the extremely large relationships (0.979, 0.993) found between the two devices suggest the optical sensor is able to detect similar changes in performance to that of a force platform. Practitioners may continue to utilize optical sensors to monitor performance as it may provide a superior user-friendly alternative to more traditional based monitoring procedures, but must comprehend the inherent limitations due to the design of the optical sensors.
1023

A New Approach to Determining Net Impulse and Identification of Its Characteristics in Countermovement Jumping: Reliability and Validity

Mizuguchi, Satoshi, Sands, William A., Wassinger, Craig A., Lamont, Hugh S., Stone, Michael H. 26 June 2015 (has links)
Examining a countermovement jump (CMJ) force-time curve related to net impulse might be useful in monitoring athletes' performance. This study aimed to investigate the reliability of alternative net impulse calculation and net impulse characteristics (height, width, rate of force development, shape factor, and proportion) and validate against the traditional calculation in the CMJ. Twelve participants performed the CMJ in two sessions (48 hours apart) for test–retest reliability. Twenty participants were involved for the validity assessment. Results indicated intra-class correlation coefficient (ICC) of ≥ 0.89 and coefficient of variation (CV) of ≤ 5.1% for all of the variables except for rate of force development (ICC = 0.78 and CV = 22.3%). The relationship between the criterion and alternative calculations was r = 1.00. While the difference between them was statistically significant (245.96 ± 63.83 vs. 247.14 ± 64.08 N s, p < 0.0001), the effect size was trivial and deemed practically minimal (d = 0.02). In conclusion, variability of rate of force development will pose a greater challenge in detecting performance changes. Also, the alternative calculation can be used practically in place of the traditional calculation to identify net impulse characteristics and monitor and study athletes' performance in greater depth.
1024

PERFORMANCE OF TWO TIEBACK WALLS AND ROCK ANCHORS IN A SHALE STRATUM

Romana Giraldo, Jorge Octavio 01 January 2018 (has links)
Tieback walls are typically design based on predetermined pressure distribution; however, these pressures were proposed based on performance of excavations. For retaining walls used in slope remediation, the application of these pressures might not be adequate; the construction procedure; therefore, a different response of the wall is expected. This document, presents the performance of two tieback walls installed in a shale stratum. Monitored responses is correlated with construction activities; these activates implied excavation and backfilling in both of the tieback walls. In addition, this research shows a numerical procedure to evaluate the anchor capacity based on the t- z approach. Finally, this study introduces an empirical method to estimate lateral wall deformation profiles and internal bending moments along a retaining wall installed in a clay stratum.
1025

STUDY ON THE PATTERN RECOGNITION ENHANCEMENT FOR MATRIX FACTORIZATIONS WITH AUTOMATIC RELEVANCE DETERMINATION

tao, hau 01 December 2018 (has links)
Learning the parts of objects have drawn more attentions in computer science recently, and they have been playing the important role in computer applications such as object recognition, self-driving cars, and image processing, etc… However, the existing research such as traditional non-negative matrix factorization (NMF), principal component analysis (PCA), and vector quantitation (VQ) has not been discovering the ground-truth bases which are basic components representing objects. On this thesis, I am proposed to study on pattern recognition enhancement combined non-negative matrix factorization (NMF) with automatic relevance determination (ARD). The main point of this research is to propose a new technique combining the algorithm Expectation Maximization (EM) with Automatic Relevance Determination (ARD) to discover the ground truth basis of datasets, and then to compare my new proposed technique to the others such as: traditional NMF, sparseness constraint and graph embedding in pattern recognition problems to verify if my method has over performance in accuracy rate than the others. Particularly, the new technique will be tested on variety of datasets from simple to complex one, from synthetic datasets to real ones. To compare the performance, I split these datasets into 10 random partitions as the training and the testing sets called 10-fold cross validation, and then use the technique called Euclidean algorithm to classify them and test their accuracy. As the result, my proposed method has higher accuracy than the others, and it is good to use in pattern recognition problems with missing data.
1026

DETERMINING TIDAL CHARACTERISTICS IN A RESTORED TIDAL WETLAND USING UNMANNED AERIAL VEHICLES AND DERIVED DATA

Thornton, Victor 01 January 2018 (has links)
Unmanned aerial vehicle (UAV) technology was used to determine tidal extent in Kimages Creek, a restored tidal wetland located in Charles City County, Virginia. A Sensefly eBee Real-Time Kinematic UAV equipped with the Sensor Optimized for Drone Applications (SODA) camera (20-megapixel RGB sensor) was flown during a single high and low tide event in Summer 2017. Collectively, over 1,300 images were captured and processed using Pix4D. Horizontal and vertical accuracy of models created using ground control points (GCP) ranged from 0.176 m to 0.363 m. The high tide elevation model was subtracted from the low tide using the ArcMap 10.5.1 raster calculator. The positive difference was displayed to show the portion of high tide that was above the low tide. These results show that UAVs offer numerous spatial and temporal advantages, but further research is needed to determine the best method of GCP placement in areas of similar forest structure.
1027

Use of Ground Penetrating Radar (GPR) in a Study on Beach Morphodynamics at Red Reef Beach, Boca Raton, Florida

Unknown Date (has links)
The internal architecture of a beach system can provide clues into the processes involved in its formation, including depositional processes, and/or driving mechanisms (Billy et al., 2014). Several unique events such as cold fronts or Hurricane Irma caused conditions that resulted in erosion and accretion changes in Red Reef Beach - Boca Raton, throughout the year of 2017. Since the lateral extent of these changes is difficult to evaluate using traditional methods such as coring, a Ground Penetrating Radar (GPR) was tested, which allows for a good lateral resolution (cm scale), to image the distribution and evolution of these sediments. The objectives of this study were to 1) explore the lateral variability in the internal architecture of sediments in Red Reef beach in Boca Raton (FL) using an array of ground penetrating radar (GPR) measurements constrained with coring and sediment analysis; 2) explore how dynamics of erosion and accretion induced by changes in wave activity and related to tide variation and storm events, may affect surface topography and the sedimentary internal architecture of beach deposits, using RTK GPS and GPR time-lapse measurements; 3) to explore changes in the lateral extent of the freshsaltwater interface along the beach profile in relation to tide variation and storm events. Reflectors identified in the GPR images showed some evidence of erosional and accretionary surfaces preserved in Red Reef beach. These measurements were repeated over time coinciding with certain events (such as Hurricane Irma) to explore their effects in terms of sediment erosion and accretion as reflected in changes in topography (using time-lapse GPS-RTK measurements), and changes in the internal sedimentary architecture (using time-lapse GPR measurements). The datasets collected also revealed the temporal evolution of the salt-freshwater interface, showing how the lateral extent of saltwater saturated sediment (inferred from areas of GPR signal attenuation along the profiles) evolved over time. This study shows the potential of GPR to provide information about beach sediment processes and dynamics at resolutions beyond traditional measurements (such as coring). It also shows the importance of combining methods that are complementary, such as the use of RTK GPS to explore changes in topography, and GPR that provides information on subsurface sedimentary architecture and the mechanism of change such as post-storm recovery. This study has implications for better understanding changes in coastal sedimentary deposits and processes, both at the subsurface, particularly after high-energy events, such as hurricanes, that result in rapid changes in erosion and/or accretion of sediments. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection
1028

The Influence of the Ready Intelligence Program on Crewmembers' Perception of Proficiency in an Air Force Weapon System

Bane, James Martin 01 January 2015 (has links)
A lack of evaluation and evidence of effectiveness prompted this study of the Distributed Common Ground System's (DCGS) proficiency maintenance tool, Ready Intelligence Program (RIP). The goal was to close the gap between research and practice and inform stakeholders at the local Distributed Ground Station (DGS) of evaluation results. Guided by a logic model as the theoretical foundation, this study examined how proficiency is perceived by DCGS crewmembers because of RIP at a military installation with intelligence, surveillance, and reconnaissance missions. This qualitative study used an outcomes-based program evaluation report based on interviews with 5 crewmembers, observations of program participant activities, and reviews of training documents and program reports. Data were transcribed into NVivo 10 for organization, and inductive code words and categories were applied. Data interpretations were confirmed via triangulation and then sent to the participants for member-checking. An external evaluator reviewed the study's methodology, data, and findings for veracity. The project that resulted from the study was a program evaluation report that identified 4 overarching themes. It was concluded that (a) there was a lack of awareness of RIP, (b) RIP had minimal impact on perception of proficiency, (c) the program was occasionally applied ineffectively, and (d) management of the program was insufficient. It is recommended that existing RIP training be emphasized to crewmembers to increase awareness. Additionally, an ongoing program evaluation is recommended with a quantitative measure of proficiency achievement. This study promotes social change by improving attitudes toward positional proficiency and RIP as a maintenance tool, improving program maintenance, and facilitating regular program evaluations.
1029

Potential of Geothermal Energy in India

Sharma, Prajesh January 2019 (has links)
In this research paper, review of world geothermal energy production and their capacity is shown. Here, a research is conducted to know the potential and possibility of geothermal energy in India. All the geothermal province with their geographical locations are shown and a brief calculation is conducted in order to show the potential of the particular province. As India is having the low temperature geothermal fields, binary geothermal plants are used for this analysis and results are calculated by using R134a as a working fluid at different temperatures. The results are sufficient to prove the potential of geothermal energy in India.  Importance of Ground Source Heat Pump (GSHP) and power savings by its contribution over traditional heating and cooling methods is shown statistically. 9 different states of India are divided by their climatic condition, severe winter and moderate winter to calculate the heat demand in those states. Also, for the cold demands these states are considered to be same as per the climatic situation in summer. Then, comparison is done between GSHP and the traditional heating and cooling systems. The result shows the drastic power saving by using GSHP for space heating as well as cooling, over electric heater and air conditioner respectively.
1030

Nonlinear analysis of pile driving and ground vibrations in saturated cohesive soils using the finite element method

Serdaroglu, Mehmet Serdar 01 December 2010 (has links)
In urban areas, vibrations generated by pile driving often affect the neighboring properties vulnerable to ground shaking. These vibrations may cause damage to surrounding structures either by shaking the ground or by causing settlement of the soil beneath foundations in the proximity of pile driving. It is important to distinguish between the conditions under which the vibrations will cause damage and those under which vibrations are tolerable. The numerical studies on the analysis of pile driving have mostly focused on assessing the driving efficiency and the bearing capacity of dynamically loaded piles. A limited number of studies included the study of ground vibrations due to pile driving and its effects on adjacent structures. However, the factors affecting the ground vibrations in soils such as the nonlinear constitutive behavior of soil, soil-pile interaction and penetration depth of the pile have not been clearly identified. The objective of this research is to implement a numerical method to simulate dynamic loading of a single pile, and study the factors influencing the stress wave propagation in the soil surrounding the pile. The thesis is comprised of two main analyses: (1) the static analysis of a pile in which the phenomenon of static consolidation is studied, and (2) the dynamic analysis of a pile in which pile driving and ground vibrations are studied. In the static analysis, the load capacity of a single pile is investigated. The results from the finite element method are compared with widely recognized theoretical methods. The theoretical methods that are used to estimate the end bearing capacities are: (1) General Formula, (2) Vesic's Method, (3) Janbu's Method, (4) Meyerhof's Method, and (5) Coyle & Castello's Method. The estimation of skin friction resistance (shaft capacity) of single piles is performed using the (1) Alpha method, (2) Beta method, and (3) Lambda method. Two numerical applications are performed to predict the load capacity of single piles in normally consolidated clays. It is observed that the model with no slippage at the interface predicts almost twice as much load capacity as the model with interface. In regards with the end bearing capacities, Coyle & Castello's method is found to be most conservative followed by the finite element method, the Janbu's method, the Meyerhof's method, and finally the Vesic's method. In respect to skin friction resistance, the finite element is found to be the most conservative method, followed by the Beta, the Lambda, and the Alpha method. In the dynamic analysis, the amplitudes of ground vibrations are investigated based on the variation of: (1) the soil type, (2) the pile embedment length and (3) the released hammer energy. In the first analysis, five types of soils - loose and dense sands and, soft, medium stiff, and stiff clays - are modeled. The highest vibration amplitude is calculated for the loose sand with a peak particle velocity (PPV) of 10.0 mm/s followed by the dense sand with a PPV of around 4.0 mm/s. Among the clay types, the vibrations are higher for the stiffer clay in the near field, which is 9 m (half a pile length) or less away from the pile. In the second analysis, three different embedment lengths - full, half, and quarter pile length - are modeled. It is found that the quarter embedded piles produce greater vibration amplitudes as compared to the half and fully embedded piles. Larger amplitudes of vibrations are encountered on the ground surface for shorter pile embedment lengths. In the third analysis, three different impact forces consisting of 2,000 kN (F), 6,000 kN (3F) and 10,000 kN (5F) are applied on the pile head. It is concluded that increase in hammer energy causes increase in the peak particle velocities.

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