<p>Vizz3D is a graph visualization tool developed at Växjö University. It is used to visualize different aspects of software systems in 3D, based on the static analysis of source code. It can optionally use Java3D or OpenGL as a graphics library.</p><p>In order to visualize huge 3D structures performance is very important. This comes from the fact that the structures must be redrawn with no delay when a user interacts with the system. If there were a delay the user would loose the cognitive orientation because his interaction and the feedback would not fit. Vizz3D was not capable to run huge visualizations fast enough, and therefore careful optimisation was essential. Additionally, the Vizz3D tool is just at the beginning of its software life cycle.</p><p>For optimisation, JOGL (Java Bindings for OpenGL) was chosen. The extension with a JOGL version was necessary since the GL4Java (OpenGL for Java) wrapper used for the implementation of Vizz3D is no longer supported. JOGL was therefore needed for assuring future maintainability.</p><p>The JOGL version of Vizz3D was optimised to be able to visualize huge graphs with acceptable performance. To determine what areas of Vizz3D that consumed most of its resources, the process of profiling were used. The system performance was improved according to several aspects: Computational performance, Scalability, Perceived performance, RAM footprint and Start-up time. The results were then evaluated by using benchmarking techniques. After optimisation, the performance of Vizz3D was improved a lot which led to that huge graphs now could be visualized with acceptable performance.</p>

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 125-133). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 125-133). Also available on the Internet.

With the ever expanding utility of transition metal catalysis, there has been a thrust both to develop catalysts with unique selectivites or activites, and to understand the factors which govern these characteristics at both a fundamental and practical level. Olefin metathesis has become an essential reaction for the synthesis of small molecules in addition to polymeric materials. We have pursued two distinct ligand classes based on diaminocarbenes with novel architectures to address specific limitations within this useful class of reactions: 1) limited access to polymeric materials with controlled microstructures and 2) poor stereoselectivity in Ru-catalyzed cross-metathesis (CM) reactions. Numerous phosphines and N-heterocyclic carbenes (NHCs) have been used as ligands for Ru metathesis catalysts, and the resulting activity is very sensitive to their steric and electronic nature. We envisioned that we could take advantage of this dependence by developing a catalyst with tunable ligand donicity. Redox-switchable ligands can lead to catalysts whose selectivity and/or activity are dependent upon the ligand oxidation state. Towards this purpose, we have developed a ligand which incorporates a 1,1’-disubstituted ferrocene moiety into the backbone of a diaminocarbene (FcDAC). Upon ligation of FcDAC to various transition metals, we were able to use cyclic voltammetry and a spectroelectrochemical FT-IR experiment to show electronic communication between FcDAC and the coordinated metal. We then pursued Ru metathesis catalysts incorporating these ligands. The ring-opening metathesis polymerization of 1,5-cyclooctadiene was studied using [(FcDAC)(PPh₃)Cl₂Ru=(3-phenylindenylid-2-ene)] as the catalyst. Chemical redox reactions were used to establish the ability of FcDAC to impart redox-tunable properties to Ru metathesis catalysts. A new ligand class pioneered in our group, N-aryl,N-alkyl acyclic diaminocarbenes (ADCs), was also studied in various Ru metathesis catalysts. To our delight, these catalysts showed lower E : Z ratios than analogous NHC ligands in two representative CM reactions. We also investigated the conformational diversity of these differentially substituted ADCs given their ability to rotate about their C–N bonds, in particular, to determine how this might influence their donicity. Complexes of the type [(ADC)Ir(COD)Cl] and [(ADC)Ir(CO)₂Cl] were studied, given the wealth of structural and spectral data available for analogous compounds incorporating related ligand classes. Different conformations resulted depending on the N-substituents and the nature of the metal complex. Interestingly, the electron donating ability of ADC ligands was found to depend on their conformation, as evidenced by FT-IR and cyclic voltammetry. This established a new avenue for tuning the donor properties of differentially substituted ADC ligands. The unique properties of these novel ligand classes were demonstrated in Ru metathesis catalysts. However, on a broader level, these ligands are expected to have utility in diverse catalytic applications. / text

Auto-tuning has become an important function in distributed control systems (DCS) and is especially appreciated in large industries that can have hundreds of controllers. In the DCS 800xA manufactured by ABB, there is an auto-tuning method implemented based on a relay experiment to determine the ultimate gain and the ultimate period, with which the PID parameters are obtained using the modified Ziegler-Nichols tuning rules. The tuning procedure can then proceed with a step identification experiment to get additional parameters for kappa-tau tuning. In the previous DCS, called Advant, there was another auto-tuning approach implemented. This method was based on dominant pole design, which included an identification of the process. The purpose of this thesis is to compare these auto-tuning methods, to investigate if the dominant pole placement method should be migrated to the 800xA system. / Automatisk trimning har blivit en viktig funktion i distribuerade styrsystem (DCS och är speciellt av intresse för stora industrier som kan ha flera hundra regulatorer. Den automatiska trimningen som idag är implementerad i ABB:s DCS 800xA är baserad på ett reläexperiment för att bestämma den ultimata förstärkningen och den ultimata periodtiden. Modifierade Ziegler-Nichols trimningsregler används sedan för att bestämma PID parametrarna. Vidare kan trimningen fortsätta med ett stegsvars-experiment för att erhålla ytterliggare parametrar och trimma med kappa-tau metoden. Den automatiska trimningsmetoden som var implementerad i tidigare DCS, Advant, var baserad på dominant polplacering med identifiering av processen. Syftet med detta examensarbete är att jämföra dessa automatiska trimningsmetoder för att undersöka om den tidigare trimningsmetoden baserad på dominant polplacering ska implementeras i 800xA systemet.

The internet revolution has led to the demand for high speed, low cost solutions for providing high bandwidth to the consumers. Cable and DSL systems address these requirements through sophisticated analog and digital signal processing schemes. A key element of the analog front end of such systems is the line driver which interfaces with the transmission medium such as co-axial cable or twisted pair. The line driver is an amplifier that provides the necessary output current to drive the low impedance of the line. The main requirements for design are high output swing, high linearity, matched impedance to the line and power efficiency. These requirements are addressed by a class AB amplifier whose output impedance can be controlled through feedback. The property of this topology is that when the gain is unity, the output resistance of the driver is matched to the line resistance. Unity gain is achieved for varying line conditions through a tuning loop consisting of peak-to-peak detectors and differential difference amplifier. The design is fabricated in 0.5 micron AMI CMOS process technology. For line variations from 65 to 170 ohms, the gain is unity with an error of 3 % and the impedance matching error is 20 % at the worst-case. The linearity is better than 50 dB for a 1.2 V peak-to-peak signal over the signal bandwidth from 10 kHz to 5 MHz and the line resitance range from 65 to 160 ohms.

Previously we have suggested the concept of tuning hydrate compositions which makes it possible to increase the gas storage capacity of binary hydrates. Herein, we report for the first time the existence of a critical guest concentration (CGC) and establish the complete tuning pattern that appears to exist in binary hydrates, including the water-soluble hydrate formers (promoters) and water insoluble guests,. The first attempt to verify the new features of clathrate hydrate compositions is executed on the binary hydrate of CH4 + THF and involves a detailed examination of the guest distribution by spectroscopic methods. THF molecules by themselves form sII hydrate from a completely miscible aqueous solution, and in this structure, because of their size, THF molecules occupy only the large 51264 cages. The CGC value appears to depend largely on the chemical nature of the liquid guest component participating in the binary hydrate formation. The present experimental findings on the existence of critical guest concentration and the complete tuning phenomenon can be expected to make a meaningful contribution to both inclusion chemistry and a variety of hydrate-based fields.

No description available.

No description available.

We review several nonparametric regression techniques and discuss their various strengths and weaknesses with an emphasis on derivative estimation and confidence band creation. We develop a generalized C(p) criterion for tuning parameter selection when interest lies in estimating one or more derivatives and the estimator is both linear in the observed responses and self-consistent. We propose a method for constructing simultaneous confidence bands for the mean response and one or more derivatives, where simultaneous now refers both to values of the covariate and to all derivatives under consideration. In addition we generalize the simultaneous confidence bands to account for heteroscedastic noise. Finally, we consider the characterization of nanoparticles and propose a method for identifying a proper subset of the covariate space that is most useful for characterization purposes.