Mehr und mehr werden neue und dabei zunehmend multimediale Anwendungen fuer das Internet entwickelt und eingesetzt. In gleichem Masze wachsen auch die Qualitaetsanforderungen an diese Dienste. So gibt sich heute niemand mehr mit reiner ASCII--Text--Uebertragung von Informationen zufrieden. E-Mails werden mit MIME--Attachments versendet, Web--Seiten mit unzaehligen Grafiken ansehnlicher gemacht, und Konferenzen in Datennetzen erheben den Anspruch auf Audio-- und Video--Uebertragung in Echtzeit. Fuer Provider stellt sich hier nun das Problem der Finanzierung. Gegenstand dieser Arbeit ist es, anhand des Szenarios des Internet--Service--Providers ¨Freie Presse Online¨ ein Tarifmodell zu entwickeln, welches mittels Ressourcensteuerung arbeitet. Es soll ein Anreizsystem etabliert werden, um eine effizientere Ausnutzung der Ressourcen zu erzielen. Die finanzielle Grundlage bildet Prepayment. Die Einflusznahme geschieht nicht mittels veraenderlicher Entgelte, sondern direkt auf die dem Nutzer zur Verfuegung gestellten Ressourcen (Bandbreite, Verzoegerungszeit). Fuer den Entwurf des Modells werden Anleihen bei artverwandten Modellen genommen, so zum Beispiel bei der Tarifierung von elektrischer Energie, da die beiden Ressourcen Bandbreite (in Datennetzen) und Energie (in Stromnetzen) markante Aehnlichkeiten aufweisen. Weiterhin wird eine Analyse des Verhaltens der Nutzer im Bezug auf die Dauer und Tageszeit der Nutzung, Datenvolumen und Lastkurven durchgefuehrt. Die Analyse und das Accounting werden mittels der von der Real Time Flow Measurement Group vorgeschlagenen Architektur realisiert. Konkret kommt die Referenz-- Implementation NeTraMet zum Einsatz.

Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--University of California, Riverside, 2008. / Includes abstract. Title from first page of PDF file (viewed March 10, 2010). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 93-98). Also issued in print.

Thesis (Ph.D.)--University of Western Sydney, 2009. / A thesis presented to the University of Western Sydney, College of Health and Science, School of Computing and Mathematics, in fulfilment of the requirements for the degree of Doctor of Philosophy. Includes bibliographies.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (p. 98-104).

Internet applications have been extended to various aspects of everyday life and offer services of high reliability and security. In the Academia, Internet applications offer useful tools for the remote creation of simulation models and real-time conduction of control experiments. The aim of this study was the design of a reliable, safe and secure software system for real time operation of a remote aero gas turbine, with the use of standard Internet technology at very low cost. The gas turbine used in this application was an AMT Netherlands Olympus micro gas turbine. The project presented three prototypes: operation from an adjacent computer station, operation within the Local Area Netwok (LAN) of Cranfield University and finally, remotely through the Internet. The gas turbine is a safety critical component, thus the project was driven by risk assessment at all the stages of the software process, which adhered to the Spiral Model. Elements of safety critical systems design were applied, with risk assessment present in every round of the software process. For the implementation, various software tools were used, with the majority to be open source API’s. LabVIEW with compatible hardware from National Instruments was used to interface the gas turbine with an adjacent computer work station. The main interaction has been established between the computer and the ECU of the engine, with additional instrumentation installed, wherever required. The Internet user interface web page implements AJAX technology in order to facilitate asynchronous update of the individual fields that present the indications of the operating gas turbine. The parameters of the gas turbine were acquired with high accuracy, with most attention given to the most critical indications, exhaust gas temperature (EGT) and rotational speed (RPM). These are provided to a designed real-time monitoring application, which automatically triggers actions when necessary. The acceptance validation was accomplished with a formal validation method – Model Checking. The final web application was inspired by the RESTful architecture and allows the user to operate the remote gas turbine through a standard browser, without requiring any additional downloading or local data processing. The web application was designed with provisions for generic applications. It can be configured to function with multiple different gas turbines and also integrated with external performance simulation or diagnostics Internet platforms. Also, an analytical proposal is presented, to integrate this application with the TURBOMATCH WebEngine web application, for gas turbine performance simulation, developed by Cranfield University.

Modern rendering systems require fast and efficient acceleration structures in order to compute visibility in real time. I present several novel data structures and algorithms for computing visibility with high performance. In particular, I present two algorithms for improving heuristic based acceleration structure build. These algorithms, when used in a demand driven way, have been shown to improve build performance by up to two orders of magnitude. Additionally, I introduce ray tracing in perspective transformed space. I demonstrate that ray tracing in this space can significantly improve visibility performance for near-common origin rays such as eye and shadow rays. I use these data structures and algorithms to support a key hypothesis of this dissertation: “There is no silver bullet for solving the visibility problem; many different acceleration structures will be required to achieve the highest performance.” Specialized acceleration structures provide significantly better performance than generic ones and building many specialized structures requires high performance build techniques. Additionally, I present an optimization-based taxonomy for classifying acceleration structures and algorithms in order to identify which optimizations provide the largest improvement in performance. This taxonomy also provides context for the algorithms I present. Finally, I present several novel cost metrics (and a correction to an existing cost metric) to improve visibility performance when using metric based acceleration structures. / text

Commuter rail systems, operating on unused or under-used railroad rights-of-way, are being introduced into many urban transportation systems. Since locations of available rail rights-of-way were typically chosen long ago to serve the needs of rail freight customers, these locations are not optimal for commuter rail users. The majority of commuter rail users do not live or work within walking distance of potential commuter rail stations, so provision of quick, convenient access to and from stations is a critical part of overall commuter decisions to use commuter rail. Minimizing access time to rail stations and final destinations is crucial if commuter rail is to be a viable option for commuters. Well-designed feeder routes or circulator systems are regarded as potential solutions to provide train station to ultimate destination access. Transit planning for main line or feeder routes relies upon static demand estimates describing a typical day. Daily and peak-hour demands change in response to the state of the transport system, as influenced by weather, incidents, holiday schedules and many other factors. Recent marketing successes of “smart phones” might provide an innovative means of obtaining real time data that could be used to identify optimal paths and stop locations for commuter rail circulator systems. Such advanced technology could allow commuter rail users to provide real-time final destination information that would enable real time optimization of feeder routes. This dissertation focuses on real time optimization of the Commuter Rail Circulator Route Network Design Problem (CRCNDP). The route configuration of the circulator system – where to stop and the route among the stops – is determined on a real-time basis by employing adaptive Tabu Search to timely solve an MIP problem with an objective to minimize total cost incurred to both transit users and transit operators. Numerical experiments are executed to find the threshold for the minimum fraction of travelers that would need to report their destinations via smart phone to guarantee the practical value of optimization based on real-time collected demand against a base case defined as the average performance of all possible routes. The adaptive Tabu Search Algorithm is also applied to three real-size networks abstracted from the Martin Luther King (MLK) station of the new MetroRail system in Austin, Texas. / text

The heat-affected zone (HAZ) is the most common region of weld failures. The weld failures are directly related to the microstructure. Microstructure control of the HAZ is crucial to weld quality and prevention of weld failures. However, publications on modeling the development of the HAZ are relatively limited. Moreover, no efforts have been made to predict the HAZ microstructures in real-time. The primary goal of this research is to present a methodology to enable real-time predictions of microstructure evolution in the HAZ and its mechanical properties. This goal was achieved by an approach based on materials science principles and real-time sensing techniques. In this study, the entire welding process was divided into a series of sub-processes. Real-time multiple measurements from multiple sensors were incorporated into the sub-processes. This resulted in an integrated welding system upon which the predictions for the final HAZ microstructure are based. As part of the integrated system, the microstructural model was used to predict the TTT curves, volume fractions of the decomposition products, and hardness numbers of the heat-affected zones of steel alloys. Actual welds were performed under two different sets of conditions, and the resulting experimental data were compared with predictions made using the microstructural model. The predicted and experimental microstructure and hardness are found to be in good agreement, indicating that the microstructural model can be used in real applications. This research can act as an important component of future research to enable physics-based flexible control of welding. / text

Real time information about traffic conditions is becoming widely available through various media, and the focus on Advanced Traveler Information Systems (ATIS) is gaining importance rapidly. In such conditions, travelers have better knowledge about the system and adapt as the system evolves dynamically during their travel. Drivers may change routes along their travel in order to optimize their own objective of travel, which can be characterized by disutility functions. The focus of this research is to study the behavior of travelers with multiple trip objectives, when provided with real time information. A web based experiment is carried out to simulate a traffic network with information provision and different travel objectives. The decision strategies of participants are analyzed and compared to the optimal policy, along with few other possible decision rules and a general model is calibrated to describe the travelers' decision strategy. This research is a step towards calibrating equilibrium models for adaptive behavior with multiple user classes. / text