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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.
221

Motion Design and Control of a Snake Robot in Complex Environments Based on a Continuous Curve Model / 複雑環境におけるヘビ型ロボットの連続曲線モデルを用いた動作設計と制御

Takemori, Tatsuya 24 September 2021 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第23505号 / 工博第4917号 / 新制||工||1768(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 松野 文俊, 教授 泉田 啓, 教授 小森 雅晴 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
222

A Study of Freemont Snake Valley Black-on-gray Ceramics from Sites in Northern Utah and the Parowan Valley

Abo, Stephanie K.Y. 14 December 2020 (has links)
Archaeologists widely argue that Fremont potters from the Parowan Valley, in southwestern Utah, manufactured Snake Valley pottery. For my thesis, I examined Snake Valley Black-on-gray rim sherds using neutron activation analysis, oxidation analysis, metric data, and statistical methods. I compared my results on Snake Valley Black-on-gray sherds from three archaeological sites within the Parowan Valley (Paragonah, Parowan, and Evans Mound) to my results on Snake Valley Black-on-gray sherds recovered from three archaeological sites over 250 kilometers to the north (South Temple, Block 49, and Wolf Village). I argue that the Snake Valley Black-on-gray ceramics from the northern sites are tradewares selected from the Parowan Valley sites. My research expands on the limited knowledge of the painted variety of Snake Valley pottery; as well as provides insight into the overall understanding of Snake Valley Black-on-gray distribution among different geographical regions within the Fremont culture.
223

Snake Grid och andra objektanpassade projektioner för svensk infrastruktur

Jonsson, Tobias January 2015 (has links)
I detta examensarbete undersöks tillämpligheten av speciellt anpassade kartprojektioner för projektering, byggnation, drift och underhåll av långsträcka objekt inom svensk infrastruktur. Speciellt intresse ägnas åt Snake Grid-projektionen som utvecklats av University College London i samarbete med Network Rail, som bygger och underhåller det brittiska järnvägsnätet. I samband med att man i Sverige satsar på utbyggnad och uppgradering av järnvägsnätet med höghastighetsspår, uppstår även ny mätningstekniska utmaningar då anläggningarna blir allt mer komplicerade, och toleranserna allt snävare. Projekteringen av anläggningarna utförs oftast i programvaror som antar att bygget kommer att utföras i ett tredimensionellt rum med rätvinkliga axlar, med norr och öst i ett plan och lodriktningen vinkelrätt mot detta plan. Problem uppstår när detta antagande om en platt jord möter verkligheten med en krökt jordyta och kuperad terräng. Den klassiska lösningen på problemet är att arbeta med kartprojektioner, för att på så sätt lokalt eller regionalt approximera en platt jord vid kartering och projektering. Storleken på det område som kartprojektionen är giltig för och lokala höjdförhållanden bestämmer hur stora avbildningsfelen, i form av skalförskjutningar, som mest blir i kartan. Vid rent geodetiska tillämpningar såsom kartering eller stommätning kan korrektioner påföras de insamlade mätvärdena för att justera dem till det projicerade kartplanet, men det blir mer komplicerat när det kommer till projekteringen av anläggningar, där måttsättningen ska vara korrekt och en meter på ritningen ska motsvara en meter i vekligheten. För vissa anläggningar blir de skalförskjutningar som de officiella projektionszonerna i SWEREF 99 medför alltför stora. Ett sätt att hantera det är att istället arbeta med en för den aktuella anläggningen speciellt framtagen projektion, som minimerar avbildningsfelet längsmed anläggningens geografiska utsträckning. I Storbritannien har Network Rail övergått till att hantera sina järnvägsanläggningar enligt denna princip, och har i samarbete med University College London låtit ta fram en speciell typ av projektion för ändamålet, kallad Snake Grid. Snake Grid bygger på att justera skalförskjutningarna till noll längs med en trendlinje som löper längs med anläggningen, och justerar både för avbildningsfel beroende på projektion och på höjd över ellipsoiden. Varje stambana har på så sätt tilldelats sitt eget plana referenssystem, med skalförskjutningar i närområdet reducerade till försumbar nivå. Projektörer och utsättare kan därför arbeta enligt ovan nämnda antagande om en platt jord. De frågor som utreds i detta examensarbete är dels om Snake Grid medför signifikanta fördelar jämfört med alternativa projektionsmetoder som kan objektanpassas, exempelvis Transversal Mercator, Oblik Mercator eller Konform Lambert, och dels om det finns några avgörande skillnader i arbetssätt eller organisation mellan Sverige och Storbritannien som kan påverka lämpligheten i att arbeta på detta sätt., och om fördelarna är större än nackdelarna med avseende på ökad administration och datautbyte med tredje man. För att introducera konceptet mer i detalj för svenska läsare beskrivs teorin bakom Snake Grid relativt ingående i denna rapport. Den innehåller även kortfattade beskrivningar av ett litet urval av alternativa metoder. Därefter görs en jämförande analys i form av beräkningar, av några infrastrukturprojekt med syfte att belysa vilka styrkor och svagheter de olika metoderna har och vilka nivåer av skalförskjutningar de medför. De objekt som undersökts är West Coast och East Coast Main Line, Öresundsförbindelsen, Förbifart Stockholm, Göteborg-Borås, Ostlänken och Sundsvall-Trondheim. Resultatet av beräkningarna indikerar att traditionella projektioner som Transversal och Oblik Mercator i de flesta fall kan objektanpassas med resultat på jämförbar nivå med rapporterade resultat för Snake Grid. Anpassningen av dessa traditionella metoder kräver dock specialkompetens, och även den vardagliga tillämpningen skulle ställa vissa krav på användarna. En av fördelarna med Snake Grid är att det är en färdig paketlösning med tillgång till support för användarna. I rapporten beskrivs även Network Rails uppdrag, och vilka myndigheter som är inblandade i arbetet med investeringar och underhåll för järnvägarna på den brittiska huvudön. Den befintliga geodetiska infrastrukturen i Storbritannien, i form av referenssystem, stomnät och nätverks-RTK utvärderas också. Utöver detta har också en undersökning gjorts av hur användandet av objektanpassade projektioner passar in i gällande svenska regelverk. Syftet med dessa undersökningar har varit att avgöra om det finns några avgörande skillnader mellan Sverige och Storbritannien när det gäller förutsättningarna för användandet av objektanpassade projektioner. Resultatet av denna jämförelse mellan de två länderna är att det inte finns några avgörande skillnader som skulle göra användandet av Snake Grid eller andra objektanpassade projektioner mindre lämpligt i Sverige. För att objektanpassade projektioner ska kunna användas för järnvägsprojekt i Sverige krävs dock dispenser eller justeringar av Trafikverkets gällande regelverk. / This thesis investigates the applicability of tailored map projections for the design, construction and maintenance of long objects, such as roads and railways, in Swedish infrastructure. Special emphasis is on the Snake Grid projection, developed by University College London in collaboration with Network Rail, the organization responsible for construction and maintenance of the railway network in Great Britain. The ongoing Swedish investments in expansion and upgrades of the country’s railway network poses new challenges for surveyors, as the constructions are becoming increasingly complex and tolerances more narrow. Track design is usually carried out with software with the built-in assumption that the construction will be made in a three-dimensional space with coordinate axes pointing to the north and the east, and with a vertical axis perpendicular to those. Problems arise when this flat-Earth assumption meets the reality of a curved surface and hilly terrain. The classical solution of this dilemma is to work with map projections, in order to make a local or regional approximation of a flat Earth for mapping and design purposes. The size of the projection zone and the local topography decides the maximum distortions that will be in the map. For purely geodetic purposes, such as topographic surveying or establishment of control point networks, corrections can be applied to the measurements to fit them to the projected map, but when it comes to construction design, where dimensions should be correct and one meter in the blueprint should correspond to one meter in reality, things get more complicated. For some constructions, the scale distortions on the outskirts of the official projection zones for the Swedish national grid SWEREF 99 are too large. One way to deal with that is to instead tailor a map projection, specific for that construction object, which will minimize scale distortions along the object. In Great Britain, Network Rail has adopted this approach to managing their railway network, and together with University College London developed a special kind of map projection for this purpose, known as Snake Grid. The principle of Snake grid is to force the scale to unity along a sinuous trend line, following the track geometry, and in the process adjust for scale distortions due to both projection and height above the ellipsoid. Each main line has been assigned its own horizontal coordinate system in that way, minimizing scale distortions in proximity to the tracks to a negligible level. As a result, construction designers and surveyors can work from a flat Earth assumption. This thesis deals with the questions whether the benefits of using Snake Grid are significant compared to tailoring other map projections, like Transversal Mercator, Oblique Mercator or Lambert Conformal Conic, and whether there are any large differences in methods or organization between Sweden and the UK that might influence the suitability of this approach and whether the pros outweigh the cons such as increased administration and risks in communication. To give Swedish readers a more detailed introduction to the concept, the theoretical description of Snake Grid is relatively comprehensive in this thesis. It also contains short descriptions of a small selection of alternative methods. After that, a comparative analysis of the methods is made by way of calculation, testing a few infrastructure projects to see which strengths and weaknesses the different map projections possess, and what magnitude of scale distortions can be expected. The examined projects are the West Coast and East Coast Main Lines, the Øresund bridge, the Stockholm Bypass, the Gothenburg-Borås railway, the Eastern link railway (Ostlänken) and the railway between Sundsvall and Trondheim. The results of the calculations indicate that, in most cases, traditional map projections such as Transversal or Oblique Mercator can be tailored to a project, with results comparable to reported results for the Snake Grid method. The tailoring, however, requires specialist competence that is hard to come by, and in the practical daily application it will also put some requirements on the competence of the end user. One of the advantages of Snake Grid is that it is a package solution with user support available. The thesis also describes the responsibilities of Network Rail, and which government bodies are involved in the maintenance of the British railway network. The existing geodetic infrastructure in Great Britain, in the form of reference systems, and control point networks is also described. An evaluation has also been made, whether tailored map projections can be used in accordance with current Swedish rules and regulations for road and railway construction. The purpose of these investigations has been to determine if there are any decisive differences between Sweden and the UK with regard to the regulatory circumstances surrounding the use of object specific map projections. The result of this comparison is that there are no substantial differences that would make the use of Snake Grid or other object specific map projections less suitable in Sweden. The usage of object specific projections in railway projects would however require exemptions from or changes to the current Swedish railway regulations.
224

Links Between Eruptive Styles, Magmatic Evolution, and Morphology of Low-Shield Volcanoes: Snake River Plain, Idaho

Barton, Katelyn J. 10 July 2020 (has links)
In this study, connections between chemical composition, eruption style, and topographic features of two shield volcanoes on the Snake River Plain, Idaho are examined. These relationships may then be applied to understanding silicate volcanic features throughout the inner solar system. Despite their similar ages and geographic locations, two young basaltic shield volcanoes—Kimama Butte (87 Ka) and Rocky Butte (95 Ka)—have strikingly different topographic profiles. The Kimama Butte shield has a diameter of 9 km and a height of 210 m. In contrast, Rocky Butte has a broad 36 km topographic shield that rises 140 m with less than 1° slopes. The vent crater at Rocky Butte developed as a large lava blister inflated and then collapsed forming a crater in which a lava lake developed. Little spatter accumulated throughout the eruption. In contrast, high spatter mounds and spatter-fed flows flank the main summit crater at Kimama Butte. Major- and trace-element compositions of the basaltic lavas are similar at the two shields, but distinct in Ni and Al2O3. The lavas range in TiO2 concentrations from 2.6–4.5 wt.% for Kimama Butte and 2.6–4.3 wt.% for Rocky Butte. These ranges can be related to magma evolution by fractional crystallization involving plagioclase and olivine without clinopyroxene. Compositions of the pre-eruptive phenocrysts are also similar at both shields but show variation with evolution. Olivine cores in the more primitive lavas are more Mg-rich (Fo80-72) than those in the evolved rocks (Fo65-55). Plagioclase cores are similarly more calcic in the more primitive flows (An78-68) than in the evolved ones (An65-52). Like other olivine-tholeiites on the Snake River Plain, the fO2 and fH2O were probably low with fO2 at -2△QFM and 0.1 wt.% H2O. Pressure of crystallization estimated from MELTS models is less than 3 kbar (~10 km deep). Calculated temperatures and magma viscosities overlap at both Kimama Butte (1226 to1147°C and 158 to14 Pa·s) and Rocky Butte (1251 to 1145°C and 75 to 8 Pa·s). However, Kimama Butte magma viscosities extend ~80 Pa·s higher than those for Rocky Butte lavas. The higher magma viscosities are the result of higher phenocryst proportions in spatter and spatter-fed lavas concentrated near the vent. Because lava temperature, volatile content, and chemical composition overlap at the two volcanoes, they are probably not important controls of shield-volcano morphology. This suggests that steep-capped shields are not created as a simple function of having more silicic lavas. Melt viscosities are also similar, but Rocky Butte lacks the phenocryst-rich (>30 vol %), higher magma viscosity lavas and the high spatter ramparts that form the cap at Kimama Butte. Thus, we conclude that eruption style and phenocryst content play the most important role in developing a low-shield volcano summit. Where eruptions shifted from lava lake overflow and tube development to late fountaining with short spatter-fed phenocryst-rich flows, steeper, higher shields develop.
225

Using faecal DNA to investigate the diet of the snakes, Psammophis crucifer and Psammophylax rhombeatus

Scholtz, Kim Jennilee January 2022 (has links)
>Magister Scientiae - MSc / Knowledge of the feeding ecology of an organism helps us to better understand predator-prey relationships and aspects of species biology, ecology and life-history traits. Understanding the feeding ecologies of snakes is challenging because snakes are generally secretive and often difficult to observe when foraging in the wild. Traditionally, studies attempting to quantify the diets of snakes relied on observing direct predation events, dissecting dead specimens, or microscopy of gut and stomach contents to identify prey species. However, investigations using traditional methods can result in an incomplete understanding of prey utilised by particular snakes. Analysis of prey DNA in snake faeces is a useful method to obtain accurate information on diet.
226

Sources and Timing of Calcium Mobilization During Embryonic Development of the Corn Snake, Pantherophis guttatus

Stewart, James R., Ecay, Tom W., Blackburn, Daniel G. 01 January 2004 (has links)
Embryos of oviparous Reptilia (=turtles, lepidosaurs, crocodilians and birds) extract calcium for growth and development from reserves in the yolk and eggshell. Yolk provides most of the calcium to embryos of lizards and snakes. In contrast, the eggshell supplies most of the calcium for embryonic development of turtles, crocodilians and birds. The yolk sac and chorioallantoic membrane of birds recover and transport calcium from the yolk and eggshell and homologous membranes of squamates (lizards and snakes) probably transport calcium from these two sources as well. We studied calcium mobilization by embryos of the snake Pantherophis guttatus during the interval of greatest embryonic growth and found that the pattern of calcium transfer was similar to other snakes. Calcium recovery from the yolk is relatively low until the penultimate embryonic stage. Calcium removal from the eggshell begins during the same embryonic stage and total eggshell calcium drops in each of the final 2 weeks prior to hatching. The eggshell supplies 28% of the calcium of hatchlings. The timing of calcium transport from the yolk and eggshell is coincident with the timing of growth of the yolk sac and chorioallantoic membrane and expression of the calcium binding protein, calbindin-D28K, in these tissues as reported in previous studies. In the context of earlier work, our findings suggest that the timing and mechanism of calcium transport from the yolk sac of P. guttatus is similar to birds, but that both the timing and mechanism of calcium transport by the chorioallantoic membrane differs. Based on the coincident timing of eggshell calcium loss and embryonic calcium accumulation, we also conclude that recovery of eggshell calcium in P. guttatus is regulated by the embryo.
227

A Study of Fremont Snake Valley Black-on-gray Ceramics from Sites in Northern Utah and the Parowan Valley

Abo, Stephanie K.Y. 14 December 2020 (has links)
Archaeologists widely argue that Fremont potters from the Parowan Valley, in southwestern Utah, manufactured Snake Valley pottery. For my thesis, I examined Snake Valley Black-on-gray rim sherds using neutron activation analysis, oxidation analysis, metric data, and statistical methods. I compared my results on Snake Valley Black-on-gray sherds from three archaeological sites within the Parowan Valley (Paragonah, Parowan, and Evans Mound) to my results on Snake Valley Black-on-gray sherds recovered from three archaeological sites over 250 kilometers to the north (South Temple, Block 49, and Wolf Village). I argue that the Snake Valley Black-on-gray ceramics from the northern sites are tradewares selected from the Parowan Valley sites. My research expands on the limited knowledge of the painted variety of Snake Valley pottery; as well as provides insight into the overall understanding of Snake Valley Black-on-gray distribution among different geographical regions within the Fremont culture.
228

Mineral chemistry of basalts recovered from Hotspot Snake River Scientific Drilling Project, Idaho: Source and crystallization characteristics

Bradshaw, Richard W. 13 July 2012 (has links) (PDF)
Mineral chemistry and petrography of basalts from the Kimama drill core recovered by Hotspot: Snake River Scientific Drilling Project, Idaho establish crystallization conditions of these lavas. Twenty-three basalt samples, from 20 individual lava flows were sampled from the upper 1000 m (of the 1912 m drilled) core drilled on the axis of the Snake River Plain, and represent approximately 3 m.y. of volcanism (rocks at the bottom of the hole are ~6 Ma). Rock from the upper 1000 m are typically fresh, while those lower in the core are more altered and are less likely to preserve fresh phenocrysts to analyze. Intratelluric phenocrysts (pre-eruption) are: olivine, plagioclase and Cr-spinel inclusions in olivine and plagioclase; groundmass phases (post-eruption) are: olivine, plagioclase, clinopyroxene, magnetite and ilmenite. Olivine core compositions range from Fo84-68, plagioclase cores range from An80-62, clinopyroxene ranges in composition from Wo47-34, En47-28, Fs30-15, spinel inclusions are Cr (up to 20 wt % Cr2O3) and Al-rich (up to 35 wt % Al2O3) and evolve to lower concentrations of Cr and Al and higher Fe and Ti, chromian titanomagnetite to magnetite, and ilmenite are groundmass oxide phases. Thermobarometry of Kimama core basalts indicates that the phenocryst phases crystallized at temperatures of 1155 to 1255°C at depths of 7 to 17 km, which is within or near the seismically imaged mid-crustal sill. Plagioclase hygrometry suggests that these lavas are relatively anhydrous with less than 0.4 wt % H2O. Groundmass phases crystallized at lower temperatures (<1140°C) after eruption. Oxygen fugacity inferred from Fe-Ti oxide equilibria is at or just below the QFM buffer. The origin of the basaltic rocks of the Snake River Plain has been attributed to a mantle plume or to other, shallow mantle processes. Mineral and whole rock major and trace element geochemistry of the olivine tholeiites from the Kimama core are used to distinguish between these two sources (deep or shallow mantle). Whole rock compositions were corrected for plagioclase and olivine fractionation to calculate primary liquids to estimate mantle potential temperatures. Olivine phenocrysts have the pyroxenite source characteristics of low Mn and Ca, but a peridotite source characteristic of low Ni. Thus, trace element models were used to test whether there is pyroxenite in the source of the Snake River Plain basalts, as hypothesized for Hawaii and other plume-related hotspots (e.g., Sobolev et al., 2005; Herzberg, 2011). Olivine chemistry and trace element models establish that the basalt source is a spinel peridotite, not a pyroxenite. The average mantle potential temperature obtained for these samples is 1577°C, 177°C hotter than ambient mantle, suggesting that the basaltic liquids were derived from a thermal plume. Silica activity barometry shows that melt segregation occurs between 80 and 110 km depth, which is within or very near the spinel stability field, and suggests that the lithosphere has been eroded by the plume to a maximum depth of 80 km, and recent mantle tomography suggests that it may be even thinner.
229

Parowan Valley Potting Communities: Examining Technological Style in Fremont Snake Valley Corrugated Pottery

Ure, Scott M. 05 July 2013 (has links) (PDF)
Defining the Fremont archaeological culture has challenged archaeologists for decades. There is still considerable debate about the origins of the Fremont, their eventual demise, their genetic relationship to modern Native American tribes, and myriad other issues. In nearly a century of Fremont research, socio-political, economic, and religious complexity remain elusive subjects. Examining technological style, the manifestation of socially influenced choices during each step of production as a means of passive communication, is one useful avenue to examine Fremont material culture to uncover the social patterns they may, or may not contain. I examine whether or not technological style in Fremont Snake Valley corrugated pottery hold traces of social identity produced by Fremont potters living in the Parowan Valley, Utah.
230

Fremont Ceramic Designs and Their Implications

Richards, Katie Kristina 03 July 2014 (has links) (PDF)
Although Fremont ceramic design styles have the potential to tell archaeologists a great deal about Fremont social interaction and boundaries, they have never been studied in detail. In the Fremont world, painted designs appear almost exclusively on the inside of bowls produced in two different regions of Utah. The firstis the Snake Valley production zone in southwestern Utah where Snake Valley Black-on-gray was produced; the second is the Emery production zone in central Utah where white-slipped Ivie Creek Black-on-white bowls were produced. The similarities in designs on the two main types of Fremont painted bowls indicates regional interaction and exchange of both materials and ideas between the two production zones, while the differences suggest regional distinctions existed within a larger Fremont complex.

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