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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.
1

Correlating Responses of Portable Field Instruments Used for Testing Aggregate and Soil Pavement Layers

Thompson, Wendy Melissa 16 March 2009 (has links) (PDF)
This research examined correlations among the responses of five portable aggregate and soil testing devices, including the nuclear density gauge (NDG), dynamic cone penetrometer (DCP), heavy Clegg impact soil tester (CIST), soil stiffness gauge (SSG), and portable falling-weight deflectometer (PFWD). Readings were analyzed from 41 project sites on treated and untreated base, subbase, and subgrade layers representing 15 different material types in Iowa, Louisiana, Utah, and Wyoming. Analyses of the data revealed statistically significant correlations for all six of the possible two-way comparisons involving the DCP, CIST, SSG, and PFWD, and a nomograph was developed for correlating responses among these different devices. No statistically significant correlations between data from the NDG and that of any other instrument were identified, however. The correlations developed in this research will be useful to pavement engineers needing to compare different types of strength and/or stiffness measurements for quality control/quality assurance purposes. Additionally, repeatability with respect to operator effects was additionally investigated for the CIST and SSG at 27 sites on treated and untreated base layers in Utah. Analyses of these data indicated that the CIST data exhibited a significant operator effect at 7.4 percent of the test sites, whereas no operator effects were detected at any test site for the SSG data. Thus, the SSG data appear to be less susceptible to operator effects than the CIST data.
2

Caracterização da elevação do Rio Grande a partir de elementos do campo de gravidade terrestre / Characterization of the Rio Grande Rise from elements of the terrestrial gravity field

Dicezare, Marília Takaguti 05 February 2018 (has links)
Dados de altimetria por satélite contêm informações importantes para o mapeamento de estruturas tectônicas em regiões oceânicas, como falhas, zonas de fratura e montes submarinos. A grande disponibilidade e densidade desses dados permitem a identificação de feições do assoalho oceânico com boa precisão. Este trabalho tem como objetivo investigar as características estruturais da Elevação do Rio Grande, no Atlântico Sul, através de elementos do campo de gravidade terrestre. Para isso, são utilizados dados de altura da superfície do mar (SSH) provenientes dos satélites das missões ERS1-GM, Geosat-GM e Seasat. Com o cálculo da derivada direcional da SSH ao longo das trilhas ascendentes e descendentes dos satélites, foram obtidos os gradientes de superfície do mar (SSG), que ressaltam os curtos comprimentos de ondas associados às importantes feições oceânicas estudadas. Também foram calculados os gradientes da altura geoidal (desvio da vertical) para auxiliar na interpretação do sinal da SSG. Através da SSH foi possível identificar estruturas de maior porte, como o rift da elevação, e algumas fraturas e montes submarinos maiores. Por outro lado, a SSG forneceu maiores detalhes sobre as feições já caracterizadas pela SSH e de toda a região, revelando também diversas outras estruturas de menor dimensão. O posicionamento das feições identificadas por ambas as grandezas, SSH e SSG, é bastante preciso. Entretanto, fatores como a direção e a orientação das trilhas dos satélites e a presença de estruturas adjacentes podem influenciar a resposta da SSG para uma determinada feição tectônica, por isso, as trilhas ascendentes e descendentes dos três satélites podem apresentar respostas diferenciadas. Sendo assim, recomenda-se analisar os dois conjuntos de trilhas de várias missões altimétricas para obter maiores informações das características estruturais das feições investigadas. O estudo também permitiu identificar possíveis estruturas com uma resposta característica de montes submarinos, nas trilhas descendentes de SSH, que não foram caracterizados anteriormente na literatura e não possuem correspondente nos modelos topográficos/batimétricos. / Satellite altimetry data contain important information for mapping tectonic structures in oceanic regions, such as faults, fracture zones and seamounts. The great availability and spatial density of these data allow one to identify ocean floor features with good accuracy. This work aims to investigate structural characteristics of the Rio Grande Rise, in South Atlantic, through elements of the terrestrial gravity field. We used sea surface height (SSH) data from satellite missions ERS1-GM, Geosat-GM and Seasat to calculate sea surface gradients (SSG), which are the SSH directional derivative along the ascending and descending satellite tracks. SSG emphasize the short wavelengths associated with the important oceanic features studied. Geoid gradients (deflection of the vertical) were also calculated to assist in the interpretation of the SSG signal. By analyzing sea surface heights, it is possible to identify larger structures, such as the rift of the rise, some fractures and large seamounts. In contrast, sea surface gradients provide greater details of the features characterized by the SSH and the entire area, also revealing several smaller seamounts. The positioning of the structures identified by both SSH and SSG is fairly accurate. However, factors such as direction and orientation of the satellite tracks and the presence of adjacent structures may influence the SSG response to a given tectonic feature. For this reason, the ascending and descending tracks of the three satellites may have different responses. Therefore, it is recommended that one analyzes the two sets of tracks from the several altimetric missions to obtain more information on the structural characteristics of the features. The study also allowed us to identify possible structures with a characteristic response of seamounts on SSH descending tracks, which were not previously characterized in the literature and do not have a similar correspondent in topographic/bathymetric models.
3

Caracterização da elevação do Rio Grande a partir de elementos do campo de gravidade terrestre / Characterization of the Rio Grande Rise from elements of the terrestrial gravity field

Marília Takaguti Dicezare 05 February 2018 (has links)
Dados de altimetria por satélite contêm informações importantes para o mapeamento de estruturas tectônicas em regiões oceânicas, como falhas, zonas de fratura e montes submarinos. A grande disponibilidade e densidade desses dados permitem a identificação de feições do assoalho oceânico com boa precisão. Este trabalho tem como objetivo investigar as características estruturais da Elevação do Rio Grande, no Atlântico Sul, através de elementos do campo de gravidade terrestre. Para isso, são utilizados dados de altura da superfície do mar (SSH) provenientes dos satélites das missões ERS1-GM, Geosat-GM e Seasat. Com o cálculo da derivada direcional da SSH ao longo das trilhas ascendentes e descendentes dos satélites, foram obtidos os gradientes de superfície do mar (SSG), que ressaltam os curtos comprimentos de ondas associados às importantes feições oceânicas estudadas. Também foram calculados os gradientes da altura geoidal (desvio da vertical) para auxiliar na interpretação do sinal da SSG. Através da SSH foi possível identificar estruturas de maior porte, como o rift da elevação, e algumas fraturas e montes submarinos maiores. Por outro lado, a SSG forneceu maiores detalhes sobre as feições já caracterizadas pela SSH e de toda a região, revelando também diversas outras estruturas de menor dimensão. O posicionamento das feições identificadas por ambas as grandezas, SSH e SSG, é bastante preciso. Entretanto, fatores como a direção e a orientação das trilhas dos satélites e a presença de estruturas adjacentes podem influenciar a resposta da SSG para uma determinada feição tectônica, por isso, as trilhas ascendentes e descendentes dos três satélites podem apresentar respostas diferenciadas. Sendo assim, recomenda-se analisar os dois conjuntos de trilhas de várias missões altimétricas para obter maiores informações das características estruturais das feições investigadas. O estudo também permitiu identificar possíveis estruturas com uma resposta característica de montes submarinos, nas trilhas descendentes de SSH, que não foram caracterizados anteriormente na literatura e não possuem correspondente nos modelos topográficos/batimétricos. / Satellite altimetry data contain important information for mapping tectonic structures in oceanic regions, such as faults, fracture zones and seamounts. The great availability and spatial density of these data allow one to identify ocean floor features with good accuracy. This work aims to investigate structural characteristics of the Rio Grande Rise, in South Atlantic, through elements of the terrestrial gravity field. We used sea surface height (SSH) data from satellite missions ERS1-GM, Geosat-GM and Seasat to calculate sea surface gradients (SSG), which are the SSH directional derivative along the ascending and descending satellite tracks. SSG emphasize the short wavelengths associated with the important oceanic features studied. Geoid gradients (deflection of the vertical) were also calculated to assist in the interpretation of the SSG signal. By analyzing sea surface heights, it is possible to identify larger structures, such as the rift of the rise, some fractures and large seamounts. In contrast, sea surface gradients provide greater details of the features characterized by the SSH and the entire area, also revealing several smaller seamounts. The positioning of the structures identified by both SSH and SSG is fairly accurate. However, factors such as direction and orientation of the satellite tracks and the presence of adjacent structures may influence the SSG response to a given tectonic feature. For this reason, the ascending and descending tracks of the three satellites may have different responses. Therefore, it is recommended that one analyzes the two sets of tracks from the several altimetric missions to obtain more information on the structural characteristics of the features. The study also allowed us to identify possible structures with a characteristic response of seamounts on SSH descending tracks, which were not previously characterized in the literature and do not have a similar correspondent in topographic/bathymetric models.
4

Spelpositionens effekt på riktningsförändring och löphastighet i samband med smålagspel. : En observationsstudie på svenska manliga elitfotbollsspelare. / Effects of playing position on change of direction and running speed during small sided games. : An observational study of Swedish male elite soccer players.

Åberg, Simon January 2018 (has links)
Högintensiva aktioner är tydliga markörer för bra prestationer i fotboll. Exempel på högintensiva aktioner med bevisad koppling till prestation är riktningsförändringar och sprinter. Det är dock fortfarande oklart hur de olika spelpositionerna påverkar kravbilden för spelarna. För att bättre förstå positionens kravprofil observerades under 6 veckor 24 svenska manliga elitfotbollspelare, från samma förening, i träning under den svenska försäsongen med hjälp av GPS utrustning. Träningstypen som utfördes var smålagsspel 3v3, 6v6 och 9v9. Syftet med observationen var att undersöka spelpositionens (back, mittfält eller anfall) påverkan på antal riktningsförändringar och dess kraft och distansen i olika hastighetszoner. Resultatet visar att anfallare utför färre riktningsförändringar av låg kraft oavsett speltyp (p=0,04). Ingen signifikant skillnad för distans i hastighetszoner mellan positioner i någon speltyp. Sammanfattningsvis rekommenderas ytterligare studier i mer kontrollerad miljö och med fler deltagare för att förstå hur spelarpositionen påverkar de fysiska kraven i smålagsspel för manliga elitfotbollsspelare. / Football today is all about high intensity actions with high intensity running and change of direction as two of the markers related to performance in football. What is still relatively unclear is the players position on the field and the demands that follows with that position. 24 swedish male elite footballplayers took part in a 6 week observation during the swedish pre-season. Using GPS equipment data was collected during small sided games (SSG) 3v3, 6v6 and 9v9 in the teams regular trainingschedule. The aim of this observation was to better understand the role of player position (defender, midfielder and forward) assosiated with the frequency and force produced in changes of direction and the distance in speedzones. The result showed that strikers performed fewer changes of direction in the lowest forcezone compared to both defenders and midfielders in all of the SSGs. No significant difference was observed regarding distance in the speedzones in any SSG. In conclusion further researsch is needed to better understand the role of player positioning during SSG in elite football.
5

An investigation into the grid compliance of the slip synchronous permanent magnet wind generator

Spies, Andries Theodorus 03 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The slip synchronous permanent magnet generator (SSG) is a direct-driven direct-grid connected generator developed to alleviate the need for expensive gearboxes and solid-state power converters on wind turbine generators. This study identifies certain key areas where the current wind turbine generator (WTG) system does not comply with the grid code for wind energy facilities (WEF) as specified by the National Energy Regulator of South Africa. The current WTG system does not have a reactive power compensation device. The main focus in this study is the development of an on-load tap changer (OLTC) transformer to control the terminal voltage of the generator. By controlling the terminal voltage of the generator the excitation-mode of the SSG can be changed allowing for control over the reactive power output of the SSG. An OLTC transformer utilising a solid-state assisted mechanical diverter circuit is built and tested to determine the viability of using an OLTC as a reactive power control device. Practical test results show that the OLTC can successfully control the terminal voltage of the SSG without interrupting the load current. The required accuracy regarding power factor control capability was not met due to the large change in reactive power output per tap change operation. A method of using small shunt capacitor banks to provide additional reactive power in between consecutive tap changes is evaluated in simulation. Simulation results show that the addition of these small shunt capacitor banks dramatically improves the reactive power control accuracy. Additionally the grid code specifies that a WEF must have the ability to curtail the active power output during frequency disturbances. The effects of frequency disturbances on the SSG output is simulated and it was found that the SSG will comply with the minimum connection requirements as specified in the grid code. A method of using an IGBT switched DC load to limit the active power output of the WEF is developed and simulated. From the simulation results it was found that the proposed active power curtailment device will meet the minimum power curtailment response time requirements as specified in the grid code. / AFRIKAANSE OPSOMMING: Die glip sinchroon permanente magneet generator (SSG) is ʼn direkte dryf, direkte netwerk gekoppelde wind generator wat ontwikkel is om behoefte aan duur ratkaste en drywing elektroniese omsetters te verlig. Hierdie studie identifiseer sekere sleutel areas waar die huidige wind generator opstelling nie aan die netwerk kode spesifikasie soos uiteengesit deur die Nasionale Energie Reguleerder van Suid-Afrika voldoen nie. Die wind turbine generator stelsel beskik nie oor ʼn reaktiewe drywing beheer meganisme nie. Die belangrikste fokus in hierdie studie is die ontwikkeling van ʼn transformator tap wisselaar wat gebruik sal word om die generator se terminale spanning te beheer. Deur die terminaal spanning te beheer kan die opwekking modus van die generator verander word om dan die uittree reaktiewe drywing te beheer. ʼn Tap wisselaar wat gebruik maak van ʼn drywingelektronies gesteunde meganiese skakelaar is ontwikkel en getoets om die lewensvatbaarheid van die tegniek te ondersoek. Praktiese toets resultate toon dat die tap wisselaar suksesvol beheer oor die generator se terminaal spanning kon uitvoer, sonder om die las-stroom te onderbreuk. Ongelukkig is die vereiste akkuraatheid ten opsigte van die reaktiewe drywing beheer nie gehaal nie. Die rede hiervoor is dat die verandering in uittree reaktiewe drywing baie groot is vir opeenvolgende tap verstellings. ʼn Metode waar twee klein kapasitor banke geskakel word om reaktiewe drywing te lewer, tussen opeenvolgende tap veranderinge, is deur middel van simulasie ondersoek. Die simulasie resultate toon aan dat die toevoeging van die kapasitors ʼn drastiese verbetering in die beheerbaarheid van die uittree reaktiewe drywing het. Verder spesifiseer die netwerk kode ook dat ʼn wind plaas oor die vermoë moet beskik om die aktiewe drywing te verminder tydens ʼn netwerk frekwensie versteuring. Die effek wat ʼn frekwensie versteuring op die SSG het, is deur middel van simulasie ondersoek en daar is gevind dat die SSG aan die netwerk verbinding spesifikasie sal voldoen. ʼn Metode waarby ʼn IGBT geskakelde GS las gebruik word om die aktiewe drywing van die wind generator te beperk is ondersoek en gesimuleer. Vanaf die simulasie resultate is daar gevind dat die drywing beperkings toestel aan die minimum drywing en reaksie tyd spesifikasies soos vereis sal voldoen.
6

Skiljer sig totala antalet tekniska aktioner i innebandy beroende på planstorlek för tjejer i olika åldersgrupper? : En kvantitativ och systematisk observationsstudie / Does the total number of technical actions in floorball depend on the rink size for girls in different age groups?

Celander, Sebastian, Cedervall, Jacob January 2023 (has links)
Aim The aim of the study was to investigate how different types of small-sided games (SSG) for girls in the ages between 12–21 years and how it affects the number of technical actions. How does the number of the total technical actions affect based on different types of small-sided games among girls in floorball and wich technical action differ? Method The Swedish floorball federation recruited one association with three different types of teams,younger red-level, older red-level and black level were the number of participants amounted to 39 outfield players and seven goalies with varied experience of exercise within the game of floorball. Data collection happened under respective teams ordinary training times where four different game forms of SSG were filmed. Each team was recorded one time in each gameform and each player got six shifts in each SSG and the shift length was one minute. Then the collected data from the video analysis was determined into an excel document and from that we put in the data in jamovi to analyze it and to see if there were any significance between the groups. Result There was no significant difference between the groups in the total amount of technical actions. The study shows that younger red has the most technical actions in 5 vs 5. The study also shows that red older has the most technical actions in 4 vs 4. In black level arose thegreatest number of technical actions in 3 vs 3. Conclusion The study will not be generalizable because of a low number of participants and no significance was reached which also previous research indicates. The conclusion of the study was that two age groups generated the most total number of technical actions in SSG while one age group generated the most total number of technical actions in a full-sized rink. The authors see trends on SSG produce more technical actions compared to a full-sized rink. More research is needed around SSG in floorball to see if this is the case. / <p>Jacob Cedervall är student på tränarprogrammet.</p><p>Sebastian Celander är student på ämneslärarprogrammet, specialidrott.</p>

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