På IKEA går produktionsflödet för en produktbild i dagsläget från konstruktionsritning till fotografering via tillverkning och montering. En produkt som är färdig för tillverkning definieras av sin mekaniska konstruktion och sina ytegenskaper. Ledtiden och kostnaden för bildproduktionen skulle kunna minskas betydligt om produkten kunde avbildas redan i detta stadium, utan att finnas tillverkad. För detta ändamål såg IKEA en möjlighet i att introducera ett nytt produktionsflöde där avancerad datorgrafik, grafisk teknik och bildbehandling omvandlar konstruktionsritningen till produktbild. Ambitionen är att från ritningen ta ut en 3D-modell, placera den i en omgivning, ljussätta och belägga den med material och av detta skapa en tryckbar produktbild som uppfyller företagets höga kvalitetskrav. Syftet med examensarbetet var att ta fram förslag på ett konkret sådant flöde genom att undersöka olika programvaror som skulle kunna användas samt att identifiera problemområden och komma med lösningsförslag på dessa. Flödet delades upp i de fem problemområdena konvertering, modellering, ljussättning, material och rendering som bearbetades parallellt. Fokus har under hela projektet legat på färghantering och upplevd bildkvalitet genom att korrekt färg- och detaljåtergivning i bilderna varit pekpinne och ledsagare. Konstruktionsritningarna som görs i SolidWorks har konverterats till 3D-modeller med programvaran PolyTrans. I 3ds max har produktmodellerna satts in i en miljö som liknar den verkliga fotostudion, belysts och belagts med material. Efter en studie av olika programvaror för rendering beslutades det att mental ray skulle användas varpå alla bilder skapats med denna. mental ray är en komplex renderare som beräknar ljussättning fysikaliskt riktigt vilket bidrar till fotorealistiska bilder. Examensarbetet handlade till mångt och mycket om att köra olika produkter genom flödet och testa med olika inställningar i de olika stegen. Flödet utvärderades kontinuerligt genom att bilderna som kom ut bedömdes visuellt. Dessutom genomfördes några tester för att undersöka inblandade programvarors eventuella brister vad gäller färghantering och upplevd bildkvalitet. Det slutliga resultatet av examensarbetet blev ett flöde som i stor utsträckning liknar arbetsflödet vid nuvarande bildproduktion. Med minimal insats från retuschavdelningen uppfyller bilderna de krav som ställs för att de skall kunna tryckas i IKEA katalogen.

The overall purpose of this research is to develop a real-time ultrasound based system for controlling robotic weld quality by monitoring the weld pool. The concept of real-time weld quality control is quite broad, and this work focuses on weld penetration depth monitoring and control with laser ultrasonics. The weld penetration depth is one of the most important geometric parameters that define the weld quality, hence remains a key control quantity. This research focuses on the implementation and optimization of the laser phased array generation unit and the development of signal analysis algorithms to extract the weld penetration depth information from the received ultrasonic signals. The system developed is based on using the phased array technique to generate ultrasound, and an Electro-Magnetic Acoustic Transducer (EMAT) as a receiver. The generated ultrasound propagates through the weld pool and is picked up by the EMAT. A transient FE model is built to predict the temperature distribution during welding. An analytical model is developed to understand the propagation of ultrasound during real-time welding and the curved rays are numerically traced. The cross-correlation technique has been applied to estimate the Time-of-Flight (ToF) of the ultrasound. The ToF is then correlated to the measured weld penetration depth. The analytical relationship between the ToF and penetration depth, obtained by a ray-tracing algorithm and geometric analysis, matches the experimental results. The real-time weld sensing technique developed is efficient and can readily be deployed for commercial applications. The successful completion of this research will remove the major obstacle to a fully automated robotic welding process. An on-line welding monitoring and control system will facilitate mass production characterized by consistency, high quality, and low costs. Such a system will increase the precision of the welding process, resulting in quality control of the weld beads. Moreover, in-process control will relieve human operators of tedious, repetitive, and hazardous welding tasks, thus reducing welding-related injures.

The ¡§Congestion Management¡¨ (CM) always has been an outstanding and major problem in power system operation. To solve this problem, experts compose solutions in a wide variety. This thesis, based on the equivalent current, applies the Equivalent Current Injection (ECI) concept and circuit parameters to derive the Power Flow Tracing Method (PFTM) . By means of this method we can get a Sensitive Matrix (SM), which is also called the Contribution Matrix (CM), to show the linear relationship between the input power and tidal current discharge of each generator set, with the linear relationship we can derive the mathematic model of treating the congestion problem discussed in this thesis. Combining the Predictor-Corrector Interior Point Algorithm (PCIPA), we can manipulate the change of each generator set in the prospective of solving the congestion problem resulting from the system contingency (SC). The thesis performed various simulations for the IEEE 30 Bus system. Regarding the power contingencies, the solutions of the power-congestion problems can be resulted from the following incidents: heavy load addition, transmission line tripped, generator malfunction as well as the multi-contingencies, etc., which can all be solved with solutions within reasonably restricted domains. We can thus verify the effectiveness of the method .

For photographers to capture good pictures of their subjects, the lighting conditions must be taken into account and adjusted for accordingly. The same holds true for a satellite attempting to photograph another object in space: it must know the lighting conditions to adjust camera settings and position itself properly to take the best photograph. This thesis presents a photon mapping based algorithm to compute a physically accurate representation of the illumination of objects in orbit around the Earth, taking into account the effects that cause refraction in the atmosphere. I also discuss the assumptions that I have made to utilize the algorithm in an interactive 3D visualization tool, which I implemented to view the illumination on objects at arbitrary positions in space. Finally, I show that the photon mapping method offers improvements over simpler methods of computing illumination.

With the deregulation of power industry and the market competition, reliable power supply and secured system operation are major concerns of the independent system operator (ISO). Power system operation under deregulated environment is very complicated with various possibilities of decisions involved. A robust and fast network analysis tool is one of important functions of conventional EMS, and this function will be reserved for the on-line analysis to deal with varied behaviors of the new deregulated environment. Firstly, a multiple-frequency three-phase load flow model was developed in this dissertation. There are two new sub-models including the fundamental power flow (FPF) and harmonic frequency power flow (HPF) model. In FPF, models of electrical elements and injected power on buses were treated in the form of current injections in a transmission system. The standard Fourier analysis was used to deal with the harmonic loads to get injection currents. With harmonic currents as equivalent current sources, the HPF can be derived. Besides, the fast assumptive model and decoupled model of FPF and HPF, called AFPF, DFPF and DHPF, were also proposed to improve execution time of the load flow programs. Test results show that the proposed general-purpose methods are better performers than conventional power flow solutions and are very robust. Secondly, the novel method, Upstream Tracing Model (UTM) and Downstream Tracing Model (DTM), to trace the power flow in transmission systems based on the converged AC power flow solution was proposed. The method is formulated by using the transmission network structure, the equivalent current-injection and load-admittances from the engineering viewpoint. Four steps are used to trace the linear relationship between each line flow and generator injection power without any assumption and the counter flow can be traced out, then the power consumption on each load can be represented as generators¡¦ contribution. According to the result of tracing, the loss of each line can be allocated to each generator by using a fair line usage concept. This tracing algorithm can calculate each generator¡¦s contribution quickly and fairly, and can be integrated into the existent tariffs of charging for transmission losses and services.

In the last decade, computational power, memory bandwidth and programmability capabilities of graphics processing units (GPU) have rapidly evolved. Therefore, many researches have been performed to use GPUs in advanced graphics rendering. Because of its high degree of parallelism, ray tracing has been one of the rst algorithms studied on GPUs. However, the rendering of large scenes with ray tracing can easily exceed the GPU&#039 / s memory capacity. The algorithm proposed in this work uses a data parallel approach where the scene is partitioned and assigned to CPU-GPU couples in a cluster to overcome this problem. Our algorithm focuses on ray casting which is a special case of ray tracing mainly used in visualization of volumetric data. CPUs are pretty ecient in ow control and branching while GPUs are very fast performing intense oating point operations. Using these facts, the GPUs in the cluster are assigned the task of performing ray casting while the CPUs are responsible for traversing the rays. In the end, we were able to visualize large scenes successfully by utilizing CPU-GPU couples eectively and observed that the performance is highly dependent on the viewing angle as a result of load imbalance.

The purpose of this research is to examine the gender differences that exist when male and female participants complete the mirror-tracing task. This task was chosen because it requires both spatial and psychomotor abilities and is unusual in the sense that it has a far higher correlation with standard spatial ability measures than do most other psychomotor tests. This research will focus on looking at gender differences in speed, accuracy, and practice effects. It will also investigate two personality traits that correlate with performance on the task: introversion and anxiety. Data will be collected from three studies: Experiment 2 of Ackerman&Cianciolo's (1999) study, Experiment 3 of Ackerman&Cianciolo's (2000) study, and Experiment 1 of Field's (1998) study. The results are expected to show that males complete the mirror-tracing task quicker than females during initial, intermediate, and final assessments; however, females will exhibit greater practice effects than males. The results are also anticipated to show there is no significant gender difference in the number of errors made during initial, intermediate, or final assessment. Finally, the number of errors made during initial assessment on the mirror-tracing task is expected to be negatively correlated with introversion and positively correlated with anxiety.

Standardmäßig erfolgt die Datenaufbereitung der Neutronenwirkungsquerschnitte für Reaktorkernrechnungen mit 2D-Zellcodes. Ziel dieser Arbeit war es, einen 3D-Zellcode zu entwickeln, mit diesem Code 3D-Effekte zu untersuchen und die Notwendigkeit einer 3D-Datenaufbereitung der Neutronenwirkungsquerschnitte zu bewerten. Zur Berechnung des Neutronentransports wurde die Methode der Erststoßwahrscheinlichkeiten, die mit der Ray-Tracing-Methode berechnet werden, gewählt. Die mathematischen Algorithmen wurden in den 2D/3D-Zellcode TransRay umgesetzt. Für den Geometrieteil des Programms wurde das Geometriemodul eines Monte-Carlo-Codes genutzt. Das Ray-Tracing in 3D wurde auf Grund der hohen Rechenzeiten parallelisiert. Das Programm TransRay wurde an 2D-Testaufgaben verifiziert. Für einen Druckwasser-Referenzreaktor wurden folgende 3D-Probleme untersucht: Ein teilweise eingetauchter Regelstab und Void (Vakuum oder Dampf) um einen Brennstab als Modell einer Dampfblase. Alle Probleme wurden zum Vergleich auch mit den Programmen HELIOS (2D) und MCNP (3D) nachgerechnet. Die Abhängigkeit des Multiplikationsfaktors und der gemittelten Zweigruppenquerschnitte von der Eintauchtiefe des Regelstabes bzw. von der Höhe der Dampfblase wurden untersucht. Die 3D berechneten Zweigruppenquerschnitte wurden mit drei üblichen Näherungen verglichen: Lineare Interpolation, Interpolation mit Flusswichtung und Homogenisierung. Am 3D-Problem des Regelstabes zeigte sich, dass die Interpolation mit Flusswichtung eine gute Näherung ist. Demnach ist hier eine 3D-Datenaufbereitung nicht notwendig. Beim Testfall des einzelnen Brennstabs, der von Void umgeben ist, erwiesen sich die drei Näherungen für die Zweigruppenquerschnitte als unzureichend. Demnach ist eine 3D-Datenaufbereitung notwendig. Die einzelne Brennstabzelle mit Void kann als der Grenzfall eines Reaktors angesehen werden, in dem sich eine Phasengrenzfläche herausgebildet hat.

Standardmäßig erfolgt die Datenaufbereitung der Neutronenwirkungsquerschnitte für Reaktorkernrechnungen mit 2D-Zellcodes. Ziel dieser Arbeit war es, einen 3D-Zellcode zu entwickeln, mit diesem Code 3D-Effekte zu untersuchen und die Notwendigkeit einer 3D-Datenaufbereitung der Neutronenwirkungsquerschnitte zu bewerten. Zur Berechnung des Neutronentransports wurde die Methode der Erststoßwahrscheinlichkeiten, die mit der Ray-Tracing-Methode berechnet werden, gewählt. Die mathematischen Algorithmen wurden in den 2D/3D-Zellcode TransRay umgesetzt. Für den Geometrieteil des Programms wurde das Geometriemodul eines Monte-Carlo-Codes genutzt. Das Ray-Tracing wurde auf Grund der hohen Rechenzeiten parallelisiert. Das Programm TransRay wurde an 2D-Testaufgaben verifiziert. Für einen Druckwasser-Referenzreaktor wurden folgende 3D-Probleme untersucht: Ein teilweise eingetauchter Regelstab und Void (bzw. Moderator mit geringerer Dichte) um einen Brennstab als Modell einer Dampfblase. Alle Probleme wurden zum Vergleich auch mit den Programmen HELIOS (2D) und MCNP (3D) nachgerechnet. Die Abhängigkeit des Multiplikationsfaktors und der gemittelten Zweigruppenquerschnitte von der Eintauchtiefe des Regelstabes bzw. von der Höhe der Dampfblase wurden untersucht. Die 3D berechneten Zweigruppenquerschnitte wurden mit drei üblichen Näherungen verglichen: linearer Interpolation, Interpolation mit Flusswichtung und Homogenisierung. Am 3D-Problem des Regelstabes zeigte sich, dass die Interpolation mit Flusswichtung eine gute Näherung ist. Demnach ist hier eine 3D-Datenaufbereitung nicht notwendig. Beim Testfall des einzelnen Brennstabs, der von Void (bzw. Moderator geringerer Dichte) umgeben ist, erwiesen sich die drei Näherungen für die Zweigruppenquerschnitte als unzureichend. Demnach ist eine 3D-Datenaufbereitung notwendig. Die einzelne Brennstabzelle mit Void kann als der Grenzfall eines Reaktors angesehen werden, in dem sich eine Phasengrenzfläche herausgebildet hat.

The optical design of a LED illuminator and camera imaging system were studied for potential use in a small medical "robotic type" probe to be used for minimally invasive abdominal surgery. Beam shaping optical reflectors were studied to increase the intensity distribution of the LED beam directed toward a close-by target surface. A CMOS/CCD camera and lens was used to image the targeted area. In addition, extensive optical ray tracing simulations were made to predict the intensity patterns. The experimental measurements and ray tracing simulations were in good agreement, and indicated that 20 degree cone reflectors for the LED sources and appropriate micro-lens/CCD chip imaging optics should provide a useful image at a working distance of about 5 cm.