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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

Refraction effects in precise surveying measurements

Davison, M. January 1987 (has links)
No description available.
2

A study of the possibility to connect local levelling networks to the Swedish height system RH 2000 using GNSS

Liu, Ke January 2011 (has links)
In this study, the connection of a local levelling network to the national height system in Sweden, RH 2000, with GNSS-techniques is investigated. The SWEN 08 is applied as geoid model. Essentially, the method is precise normal height determination with GNSS. The accuracy, repeatability and the affecting elements are tested. According to the statistics,the proposed method achieves 1-cm accuracy level. Suggestions on the general methodology and settings of several elements are proposed based on the statistics for the future application.
3

Intelligent Headlamp Levelling : Thesis work at Scania CV AB

Palm Lamerstedt, Peder, Fingalsson, Christopher January 2023 (has links)
Illumination of the road environment plays an important role for the night-time vision of the driver and in general road safety. The purpose of this thesis is to develop a proof of concept that can measure the vertical angular displacement of a truck headlamp relative to the road. This was achieved by gathering customer needs and establishing a target specification. Two concepts were considered to have the potential to satisfy the target requirement values and were selected for further development, one based on accelerometers and the second based on an Inertial Measurement Unit. Prototypes were developed and built to test and evaluate the concept against the target values. Once a concept was chosen, a reference plane was introduced to complete the concept which enabled testing and simulations of a variety of scenarios that a truck faces when operating on roads. The final product is based on digital accelerometers controlled via a microcontroller. The result of the final testing and simulation shows that the developed concept can measure an angular displacement with a mean inaccuracy of ±0.051◦ regardless of the slope of the road. This inaccuracy corresponds to ∼ 14% of the required tolerance according to a proposed revision of the current UNECE-48 regulations, which gives a tolerance leeway of ∼ 86% for the rest of the control system.
4

Accent levelling in the regional French of Alsace

Pipe, Katharine Joanna January 2014 (has links)
The aim of this study is to investigate the process of accent levelling in the Regional French of Alsace and its relationship with the social variables of age, gender, social class, urban or rural origin of speakers and feelings of regional attachment. Accent levelling, which can be defined as the process of speakers abandoning local phonological forms in favour of supralocal variants, has been the focus of much recent sociolinguistic research on British English, French and other languages. Since knowledge of Alsatian (a Germanic language spoken in Alsace) is decreasing, it is possible that the resulting lack of interference between Alsatian and French is leading to levelling of the traditional accent features of Alsatian Regional French. In order to provide data for this research project, sociolinguistic interviews were conducted and written questionnaires used in Strasbourg and in the village of Helsheim (a fictional name used for reasons of confidentiality) with 56 informants. The data obtained were then subjected to quantitative analysis with regard to the linguistic variables of aspirate h (which can be realised as a supralocal zero variant or as a regional [h] variant) and the devoicing of canonically voiced plosives and fricatives (for example, sage pronounced [saʃ]). The results of the data analysis revealed that the regional variants of both linguistic variables are used more frequently by older than younger, working class than middle class, rural than urban speakers and that level of regional attachment correlates with use of the linguistic variables, as predicted in the research hypotheses. However, the relationship between levelling and gender proved to be more unexpected, with no clear pattern emerging for the (h) variable and a complex one involving the acquisition of supralocal patterns of sociolinguistic variation as well as the supralocal phonological variant in the case of consonant devoicing.
5

Line levelling for high variant low volume mix

Thomas, Githin, Nidhin Chacko, Regi January 2017 (has links)
No description available.
6

Finite Element Analysis of the Residual Stress Distribution in Rolled Aluminum Plates after Tension Levelling

Lin, Jing-yu 09 September 2012 (has links)
When an aluminum alloy plate after rolling, non-uniform residual stress distributions existed inside the plate and defects, such as edge wave, middle wave, of the plate will be induced. Usually, a levelling process will be adopted to modify the plate flatness. By numerically simulating the tension levelling process, the purpose of this thesis is to understand the final dimensions and the residual stress distribution of the aluminum plate subjected to the tension levelling process. This study used the finite element method as the basic theory of the numerical simulation. A 3-D model of a cold-rolled plate with a side wave, subjected to tension levelling process was constructed. Then, the effects of the variations of the tensile ratio and residual stress distribution after rolled on the residual stress distribution after levelling and the improvement of flatness were studied. The simulation results showed that in the wave region, the tension levelling process could eliminate more than 90% of the residual stress, in the flat region was up to 80%.Also, after leveling, the residual stress distribution in the flat region was more uniform than the wave region. After-rolled residual stresses at the wave region affected the final peak position of the wave and the stress eliminated ratio of the wave region, but showed no significant effect on the final plate width and the residual strains. After-rolled residual stresses at the flat region affected the stress elimination ratio of the flat region only. The tensile ratio would affect the plate flatness, the plate width, stress elimination ratio, and the maximum residual stress. The higher of the tensile ratio, the more flatness of the plate would be obtained, but the higher residual strain would be induced and caused the lesser range of available plate.
7

Využití permanentních sítí GNSS pro určování výšek / The Using of GNSS Permanent Networks for Height Determination

Kuruc, Michal Unknown Date (has links)
This Thesis deals with the evaluation of height accuracy of GNSS point positioning. Many experimental measurements aimed on GNSS and heights issues was realised within this work. The ellipsoidal heights were measured together with the orthometric heights and then the local Quasigeoid model was created. The network of height points was built to realisation of proposed measurements on the territory of the city Brno. The model of Quasigeoid from experimental measurement was compared with any other models of Quasigeoid and with local astronomical model. The partial aim of this Thesis is the proposal of methodology of height determination by GNSS technology and levelling measurement together. We can determine or verify the orthometric heights by using GNSS measurement and this methodology.
8

Possibilities to make measurements of ground subsidence more effective, using dInSAR, GNSS and levelling

Östblom, Evelina January 2017 (has links)
Ground subsidence is today very common. It can occur due to man-made or natural causes. Today, it is most common that subsidence occurs in urban areas, and there the causes are almost exclusively man-made, including groundwater extraction, construction under or above ground. This can lead to damage of buildings or other constructions and lead to large costs for reparation. To avoid this, subsidence must be detected in an early stage. Therefore, this thesis work will study the most effective way to detect and measure subsidence using dInSAR, GNSS and levelling. The thesis work will contain a literature study, a compilation of cases comparing the methods and a quantitative comparison of data, called case Stockholm. The main focus of case Stockholm is to compare the RMS error for the datasets and to determine how well the linear regression of the datasets cohere. The literature study and the case compilation presents the strengths and weaknesses of the different methods, where dInSAR’s strength is the ability to measure large areas at once while the weakness is the inability to detect small movements within a large movement. The possibility to measure individual points of interest is the strength of both GNSS and levelling, where the most time-consuming method, levelling, also has the highest accuracy. In case Stockholm, the linear regression for dInSAR mostly follows the linear regression for GNSS and levelling. However, irregular levelling measurements that do not follow the general ground subsidence is missed by dInSAR and the amplitude of the dInSAR measurements differ from both GNSS and levelling measurements. This confirms the strengths and weaknesses mentioned in the literature study. The conclusion that can be drawn from this is that the most effective way of using dInSAR, GNSS and levelling is to first screen large areas for any movement using dInSAR. Later only the areas that display movement of any sort is measured with either GNSS or levelling depending on demands on accuracy. / Sättningar i mark är något som idag är väldigt vanligt. De sker antingen av naturliga orsaker eller skapas av människans påverkan på marken. Idag är den vanligaste förekomsten av sättningar i eller i närheten av stora städer där upptagning av grundvatten samt konstruktion ovan och under mark påverkar marken i så stor utsträckning att skador på byggnader och konstruktioner kan uppstå. För att undvika stora reparationskostnader så är det nödvändigt att upptäcka sättningarna i ett så tidigt skede som möjligt. Denna studie kommer därför behandla möjligheten att på ett så effektivt sätt som möjligt upptäcka och mäta sättningar med hjälp av dInSAR, GNSS och avvägning. Detta kommer göras genom en litteraturstudie, en sammanställning av andra praktiska fall där de tidigare nämnda metoderna jämförts med varandra samt en kvantitativ jämförelse av data över Stockholm. I den kvantitativa jämförelsen kommer vikten ligga på att jämföra metoderna baserat på RMS fel samt hur väl de linjära approximationerna följer varandra för de olika metoderna. Litteraturstudien tillsammans med sammanställningen av de praktiska fallen ger en bred bild av metodernas styrkor och svagheter, där dInSARs styrka ligger i förmågan att läsa av stora områden men dess svaghet är att små individuella rörelser inom en stor rörelse inte kan fångas upp. Styrkan för GNSS och avvägning är punktinmätning, där avvägning har den högsta noggrannheten, men också är mest tidskrävande. Den kvantitativa jämförelsen av data bekräftar styrkorna och svagheterna för metoderna då det var tydligt att dInSAR till största del fångar upp samma markrörelse som både GNSS och avvägning. Det som skiljer dInSAR från GNSS och avvägning är amplituden av mätningarna samt det faktum att vissa avvägda mätningar som visar en annan rörelse än den generella inte fångas upp av dInSAR. Slutsatsen som kan dras från detta är att det mest effektiva sätt att upptäcka och mäta sättningar är att till en början grovt granska stora områden för eventuell rörelse med användning av dInSAR och att sedan, där rörelse uppmäts, göra noggrannare punktmätningar med antingen GNSS eller avvägning, beroende på önskad noggrannhet.
9

Vývoj samonivelačních směsí ze směsného portlandského pojiva / The development of self-leveling mixture of mixed Portland binder

Kianička, Dalibor January 2015 (has links)
This thesis aims to optimize self-levelling floor screeds and thin layer screeds based on ternary binder system containing portland cement, calcium aluminate cement and gypsum with intentional ettringite formation. It also studies the influence of designed mixtures, chemical admixtures and aggregate granulometry on achieved technological characteristics required by standard.
10

Etablissement des nouveaux réseaux multi-observations géodésiques et gravimétriques, et détermination du géoïde en Iran / Establishment of multi-observations geodetic and gravimetric networks, and determination of geoid in Iran

Hatam Chavari, Yaghoub 08 December 2010 (has links)
Iran couvre une grande superficie en longitude entre les méridiens 44°E et 64°E et en latitude entre les parallèles 25°N et 40°N. la cartographie de champ de pesanteur sur l'Iran est de première importance pour des considérations d'ordre géodésique, géophysique et géodynamique. Dans cette thèse, les mesures de pesanteur sont utilisées pour déterminer le géoïde gravimétrique sur l'Iran. Ce géoïde est couplé à la mesure de hauteur GPS et d'altitude (nivellement) pour réaliser une surface verticale opérationnelle sur le territoire Iranien. La contribution aux principaux travaux géodésiques et gravimétriques réalisés ces dernières années porte sur l'établissement: 1) du réseau national de gravimétrique absolu de l'Iran (NAGNI09), 2) de la ligne nationale d'étalonnage de gravimétrique de l'Iran (NGCLI10), 3) du réseau multi- observations géodésiques et gravimétriques de l'Iran (MPGGNI10). Le réseau gravimétrique absolu, comporte 24 stations où la mesure de la pesanteur a été réalisée à l'aide de gravimètres FG5, avec une précision meilleure que 5 Gal. La répétition des observations sur deux sites entre 2000 et 2007 met en évidence des variations inter-annuelles de la pesanteur en relation avec l'évolution du contenu en eau du sous-sol et (ou) la déformation tectonique. Le réseau a servi de point d'appui pour la réalisation du réseau géodésique et gravimétrique MPGGNI10 de maille 55 km sur lequel a été mesuré la pesanteur à l'aide des gravimètres relatifs CG5 et CG-3/M, la hauteur de GPS et l'altitude avec une précision respectivement de 0.010 mGal, 0.03 m et . La technique de retrait- restauration couplée à la méthode de condensation de Helmert a permis de calculer un nouveau modèle de géoïde gravimétrique, IRGeoid10, avec une précision absolue et relatif respectivement de l'ordre de 0.26 m et 2.8 ppm. Ce géoïde est ajusté aux points GPS nivelés pour définir un nouveau référentiel des altitudes sur l'Iran. / Iran covers a large area limited in longitude by the meridians 44°E and 64°E and in latitude by the parallels 25°N and 40°N. Mapping a new gravity field over Iran is the first important data for geodetic, geophysical and geodynamical considerations. In this thesis, the gravity measurements are used to determine the gravimetric geoid over Iran. This geoid is coupled with the GPS height and altitude (levelling) to realize an operational vertical surface at the territory of Iran. The contribution of the principal geodetic and gravimetric works realized in recent years are the establishment of: 1) the national absolute gravity network of Iran (NAGNI09), 2) the national gravity calibration line of Iran (NGCLI10) and 3) the multi-observations geodetic and gravimetric network of Iran (MPGGNI10). The absolute gravity network consists in 24 stations where the gravity measurement has been realized with the help of gravimeters FG5, with a precision better than 5 Gal. The repetition of the observations at two stations between 2000 and 2007 makes obvious the inter-annual variations of gravity in relation of the amount of underground water changes and (or) tectonic deformation. The absolute gravity network has served the base stations for the realization of the MPGGNI10 geodetic and gravimetric network with a mesh of 55 km, at which the gravity is measured with the help of relative gravimeters CG-5 and CG-3/M, the GPS height and the altitude with a precision of 0.010 mGal, 0.03 m, and respectively. The remove-restore technique coupled with the Helmert's condensation method is chousen to compute a new gravimetric geoid model, IRGeoid10, with a absolute and relative precision of the order of 0.26 m and 2.8 ppm respectively. The gravimetric geoid is adjusted at the GPS/levelling points to define new vertical reference surface over Iran

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