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224 Uppsatser om Curvature estimation - Sida 1 av 15
Uppskattning av Ytkurvatur och CFD-simuleringar i Mänskliga Bukaortor
By applying a segmentation procedure to two different sets of computed tomography scans, two geometrical models of the abdominal aorta, containing one inlet and two outlets have been constructed. One of these depicts a healthy blood vessel while the other displays one afflicted with a Abdominal Aortic Aneurysm. After inputting these geometries into the computational dynamics software FLUENT, six simulations of laminar, stationary flow of a fluid that was assumed to be Newtonian were performed. The mass flow rate across the model outlet boundaries was varied for the different simulations to produce a basis for a parameter analysis study. The segmentation data was also used as input data to a surface description procedure which produced not only the surface itself, but also the first and second directional derivatives in every one of its defining spatial data points.
Elevers värderingar av föräldramedverkan i grundskolan. : En enkätundersökning
AbstractParental participation is something that is included in school either we like it or not. Several studies have been done about this phenomena but not many of them have examined the pupils estimation about parental participation. Therefore did we get interested about the pupils situation because why haven?t almost anyone asked the pupils about this phenomena when it?s constructed fore them? To learn more about the pupils estimation did we a questionnaire in twelve different classes with children in the ages between 10-16 years. The results we got from the questionnaire concerning the pupils estimation about parental participation were both expected and unexpected.Keywords: Parental participationQuestionnairePupil estimation.
Axial- och gradientkrympning hos golv på mark enligt Eurokod 2 : Sprickbredders beroende av betongkvalité, tvångseffekter och armeringshalt
AbstractConcrete foundation slabs are usually exposed to unilateral drying during the curing process. The unilateral drying causes an axial shrinkage and a concave curvature of the construction. The curvature results from the fact that the upper part of the slab is drying and shrinking faster than the lower part. This is called gradient shrinkage.A problem occurs when the slab is considered fully restrained by adjoining structural parts. The deformations caused by axial contraction due to the constant part of the shrinkage and the curvature caused by gradient shrinkage of the slab are then prevented by the fact that the slab is fully restrained.
Effektiv betong för småhusproduktion : Betong med högt luftinnehåll för platta på mark
This Masters thesis work describes a comparison between two different methods for estimation of the down channel (base station to mobile subscriber) in Wide-band Code Division Multiple Access (WCDMA). The first estimation method, Optimal Feed-forward Channel Estimation (OFCE), is a conventional method that bases the estimates on data that is known to both sender and receiver, so called pilots. The second method, Decision Directed Channel Estimation (DDCE), is an elaboration of OFCE. It also uses user data for estimation. Simulations show that DDCE, in comparison to OFCE, does not attain an improvement in signal-to-noise-ratio (SNR) for high bit error rates (BER).
Utvärdering av en beslutsåterkopplad kanalestimator för tredje generationens mobiltelefonisystem
This Masters thesis work describes a comparison between two different methods for estimation of the down channel (base station to mobile subscriber) in Wide-band Code Division Multiple Access (WCDMA). The first estimation method, Optimal Feed-forward Channel Estimation (OFCE), is a conventional method that bases the estimates on data that is known to both sender and receiver, so called pilots. The second method, Decision Directed Channel Estimation (DDCE), is an elaboration of OFCE. It also uses user data for estimation. Simulations show that DDCE, in comparison to OFCE, does not attain an improvement in signal-to-noise-ratio (SNR) for high bit error rates (BER).
Utvärdering av en beslutsåterkopplad kanalestimator för tredje generationens mobiltelefonisystem
This Masters thesis work describes a comparison between two different methods
for estimation of the down channel (base station to mobile subscriber) in
Wide-band Code Division Multiple Access (WCDMA).
The first estimation method, Optimal Feed-forward Channel Estimation (OFCE), is
a conventional method that bases the estimates on data that is known to both
sender and receiver, so called pilots. The second method, Decision Directed
Channel Estimation (DDCE), is an elaboration of OFCE. It also uses user data
for estimation.
Simulations show that DDCE, in comparison to OFCE, does not attain an
improvement in signal-to-noise-ratio (SNR) for high bit error rates (BER). An
improvement is only seen when the BER becomes much lower than what is common in
real situations.
In conclusion DDCE is complicated, involves many mathematical operations and
gives insignificant improvement of SNR when BER takes common values. It is
legitimate to question if it is possible to use the method in a real mobile
phone system..
Betongbjälklag med limmad matta : olika behandlingars effekt på alkalitet, fukthalt och emissionsbildning
This Masters thesis work describes a comparison between two different methods for estimation of the down channel (base station to mobile subscriber) in Wide-band Code Division Multiple Access (WCDMA). The first estimation method, Optimal Feed-forward Channel Estimation (OFCE), is a conventional method that bases the estimates on data that is known to both sender and receiver, so called pilots. The second method, Decision Directed Channel Estimation (DDCE), is an elaboration of OFCE. It also uses user data for estimation. Simulations show that DDCE, in comparison to OFCE, does not attain an improvement in signal-to-noise-ratio (SNR) for high bit error rates (BER).
Utveckling av en metod och en utrustning för mätning av bränslesprayers rörelsemängd
A new type of device for measuring thev m& ?rate of fuel sprays from a diesel fuel injector has been developed and the various steps in the development are described. The device works by deflecting all of the sprays from the injector at the same time by using a bell shaped deflector. A load cell consisting of a machined steel part with strain gauges mounted on it measures the resulting force. The shape of the curvature in the deflector bell shape has been evaluated by photographing the flow in a 2D?version of the curve shape.
Bestämning av osäkerheten hos skattningar av tyngdaccelerationen
In this master's thesis the problem of determining the uncertainty for an estimator of an unknown parameter is considered. The case we study is the estimation of gravity using a reversible pendulum. This involves the estimation of the point where two regression lines intersect. The estimated gravity is a function the coordinates of this point. One way to determine the uncertainty of this estimator is to use bootstrap methods.
Segmentering och klassificering av LiDAR-data
With numerous applications in both military and civilian life, the demand for accurate 3D models of real world environments increases rapidly. Using an airborne laser scanner for the raw data acquisition and robust methods for data processing, the researchers at the Swedish Defence Research Agency (FOI) in Linköping hope to fully automate the modeling process.The work of this thesis has mainly been focused on three areas: ground estimation, image segmentation and classification. Procedures have in each of these areas been developed, leading to a new algorithm for ground estimation, a number of segmentation methods as well as a full comparison of various decision values for an object based classification. The ground estimation algorithm developed has yielded good results compared to the method based on active contours previously elaborated at FOI. The computational effort needed by the new method has been greatly reduced compared to the former, as performance, particularly in urban areas, has been improved.
Tillståndsskattning i robotmodell med accelerometrar
The purpose of this report is to evaluate different methods for identifying states in robot models. Both linear and non-linear filters exist among these methods and are compared to each other. Advantages, disadvantages and problems that can occur during tuning and running are presented. Additional measurements from accelerometers are added and their use with above mentioned methods for state estimation is evaluated. The evaluation of methods in this report is mainly based on simulations in Matlab, even though some experiments have been performed on laboratory equipment.The conclusion indicates that simple non-linear models with few states can be more accurately estimated with a Kalman filter than with an extended Kalman filter, as long as only linear measurements are used.
Skattning av fordonsmassa med driftstatistik
In the automatic manual transmission system, Opticruise, the choice of gear is based on several parameters such as road incline, driving resistance and vehicle mass. Many different mass estimations are made during driving. A final vehicle mass is then used to determine the current gear. Construction vehicles are often not equipped with air suspension and can therefore not estimate the vehicle mass when standing still. If that sort of vehicle is reloaded while standing still an incorrect mass estimation will be used and as an effect of that also a wrong gear.
Estimation of reindeer lichen biomass by image analysis
During consultation procedures between forest owners and the Sámi, data on, e.g., reindeer lichen biomass on the current site is needed. Hitherto, the existing methods of measuring lichen cover and biomass has been either objective methods such as the Point Intercept method, which is time consuming, or some sort of subjective visual estimation, which is faster but less accurate. However, both these methods are sensitive to different observers and/or to different inventories. This paper addresses the further development and evaluation of a photographical inventory method that uses colour distribution in images to estimate lichen biomass. During the autumn of 2011 six different locations, with different grazing pressure and lichen cover, in Norrbotten county were inventoried using both the Point Intercept method and the photographical method, complemented with collection of biomass samples.
Vad bidrar till valet av precision i produktkalkylen?: En fallstudie om diskrepansen mellan teori och praktik inom produktkalkylering
Studies show that activity based costing (ABC) is not widespread in practice even though it has been present in the academic world since the 80's. This thesis examines the reasons for the discrepancy between theory and practice through a case study of a Swedish manufacturing company. The intension is to answer the question of what contributes to the choice of precision in product costing.We found arguments for increasing precision in product costing but not to the extent of a full-scale ABC implementation. The company's estimation of the value of increased precision. In the study three company unique factors were isolated that affected the company's estimation of value; drifting purpose of product costing, historical use of product costing and knowledge about product costing..
Automatisk mätning och detektering av röjande signaler
This master thesis has been performed at Sectra Communications AB in Linköping where they manufacture electronic encryption devices. In cryptology it is essential that an eavesdropper cannot find the plain text. To assure that a system is safe, all devices are thoroughly examined so that they don?t emit any secret information, so called Compromising Emanations (CE). This is done by comparing the secret signal with measured signals on the screen of an oscilloscope, a process that is very time consuming and furthermore, the risk of missing compromising emanations is high.