Network-based Differential GPS (DGPS), regardless of its global, regional or local scales, is enabling technology to improve GPS positioning accuracy from tens of meters, to the levels of meters, decimetres and centimetres level in real time, depending on geographical coverage of the network and measurement types. The method is to use the data from a permanent network of reference stations to model errors due to inaccurate GPS satellite orbit ephemeris and clock data, ionospheric and tropospheric effects as well as other GPS satellite and receiver biases. Then error correction messages can be sent to users via any communication link in real time. This PhD research involves algorithm development for generating satellite orbit and tropospheric delay corrections using a regional or local reference network, especially tropospheric grid corrections, which have not been included in the existing DGPS correction vector messages, for the next generation of regional GNSS positioning services. Contributions of the research are made in the following three areas: First of all, research has been undertaken to test orbit interpolation methods, in order to represent GPS orbits and orbital corrections accurately and efficiently for (near) real-time GPS applications. For precise and predicted GPS orbits given in SP3 format and orbital corrections with respect to the broadcast ephemeris, numerical tests were conducted using different terms of Lagrange, Chebyshev and trigonometric polynomial functions. Secondly, this research has implemented a short-arc (9-hour) sliding-window orbit monitoring strategy to identify larger orbit errors in the predicted part of IGS ultra-rapid orbit solutions in near real time, using GPS tracking data from a regional network around Australia. The strategy is to predict the uncertainty estimates of each orbit over a short orbit arc in near real time, which allows users to down-weight the problematic satellites and reduces the effects of orbital errors for improved near real time ZTD estimation. Unlike long-arc orbit determination, we only estimate 6 orbital elements for each satellite. Finally, this research has proposed a new tropospheric delay correction model, which uses the Ordinary Kriging (OK) method to interpolate the residual ZTD within a regional area GPS network to improve the positioning accuracy. ZTD estimates from 129 EUREF Permanent Network (EPN) stations across Europe for over 3 months and from 17 GPSnet reference stations (Victoria, Australia) for one week were collected and processed for this study, respectively. It is concluded that interpolating residual ZTD is an efficient way to improve regional area differential GPS positioning.

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ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / Network-based telemetry systems are increasingly being used to improve the flexibility and longevity of flight test systems. Modern network-based flight test systems utilize large numbers of devices including high-speed network switches, data acquisition devices, recorders, and telemetry interfaces, all of which must be managed in a coordinated fashion. The move to network-based testing provides the ability to build a standards-based System Management interface which can status and control a diverse set of devices. The benefits include the ability to easily tailor System Management tools to support many different styles of user interactions and to quickly integrate new types of devices. While the new capabilities presented by System Management are exciting, the very openness of the system presents challenges to ensure that future growth will be seamlessly supported. This paper will discuss issues encountered while implementing flight test System Management tools for a network-based telemetry system.

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / The Integrated Network Enhanced Telemetry (iNET) Project established a standards working group to address the integrated management of telemetry network systems and to ensure interoperability among various pieces of equipment. The group has been studying the benefits and drawbacks of various system management technologies with the goal of identifying a set of management interfaces which will provide long-range benefit to a large and diverse telemetry test system. This paper discusses control, configuration, status, performance, and fault management. It addresses these from several viewpoints such as multi-test articles, multi-ranges, and dynamic test environments.

1. Problemstellung<br><br> Die Liberalisierung von Netzindustrien stellt eine volkswirtschaftliche Problematik dar, die einerseits eine Vielzahl theoretisch ungelöster Fragen aufwirft und für die andererseits nunmehr auch in Deutschland wirtschaftspolitische Erfahrungen vorliegen. Die Ursachen der ökonomischen Probleme sind dabei nicht nur in bestimmten Branchenbesonderheiten der Netzindustrien zu suchen, sondern auch in einer verfehlten ordnungspolitischen Sonderbehandlung der netzgebundenen Wirtschaftsbereiche in der Vergangenheit. Entgegen den für eine marktwirtschaftliche Ordnung charakteristischen Prinzipien Wettbewerb und Privateigentum wurden Netzindustrien traditionell als wettbewerbliche Ausnahmebereiche behandelt und zumeist in Form öffentlicher Unternehmen geführt. Die Folge dessen waren (staatliche) Monopole, die eine relativ hohe Ineffizienz aufwiesen. Die ordnungspolitische Konsequenz dieses Befundes lautete daher Liberalisierung von Netzindustrien durch Privatisierung und Marktöffnung, d. h. ein Abbau von Marktzutrittsschranken durch Deregulierung. Wettbewerb stößt in Netzindustrien jedoch an Grenzen, weil die zur Produktion netzgebundener Dienstleistungen erforderliche Infrastruktur typischerweise ein nicht-angreifbares, natürliches Monopol darstellt, das sich in der Hand eines im Markt eingesessenen, vertikal integrierten Anbieters befindet. Daraus ergeben sich weitreichende Möglichkeiten zur Diskriminierung von Konkurrenten, die wettbewerbspolitischen Handlungsbedarf nach sich ziehen. Diesen gilt es in der vorliegenden Arbeit zu analysieren und alternative Lösungsansätze der Diskriminierungsproblematik zu diskutieren.<br><br> 2. Besonderes Forschungsziel<br><br> Die vorliegende Dissertation widmet sich der Liberalisierung von Netzindustrien aus ökonomischer Sicht, wobei insbesondere die Interdependenzen zwischen der Eigentums- und der Diskriminierungsproblematik berücksichtigt werden. Gleichwohl bildet die wettbewerbliche Öffnung der Märkte für netzgebundene Dienstleistungen aus volkswirtschaftlicher Sicht das Kernproblem und somit auch den zentralen Untersuchungsgegenstand dieser Arbeit. Die theoretische Analyse bleibt dabei nicht auf einen Forschungsansatz beschränkt, sondern es werden mehrere Facetten der Liberalisierung von der Ordnungs- über die Netzökonomik bis hin zur politischen Ökonomie betrachtet. In empirischer Hinsicht haben die in Deutschland in verschiedenen Netzindustrien realisierten Marktöffnungen bislang zu unterschiedlich intensiven Wettbewerbsprozessen geführt. Daher wird ein problemorientierter, intersektoraler Vergleich der Reformen und eine wettbewerbs-politische Beurteilung anhand der drei Marktmerkmale Marktstruktur, Marktverhalten und Marktergebnis vorgenommen, um die Liberalisierung in einzelnen Netzindustrien zu bewerten. Die Telekommunikation gilt dabei als Musterbeispiel für eine erfolgreiche Liberalisierung, weil die Deregulierung hier durch eine sektorspezifische Marktmachtkontrolle begleitet wird, wofür eigens eine Regulierungsbehörde geschaffen wurde. Vor diesem Hintergrund wird der mangelnde Wettbewerb in der Strom- und vor allem in der Gasversorgung sowie im Schienenverkehr häufig auf das Fehlen solcher Institutionen zurückgeführt. Aufgrund dessen werden hier die Eisenbahn, die Telekommunikation im Festnetz und die leitungsgebundene Energieversorgung als empirische Analyseobjekte ausgewählt, um die im Laufe der Untersuchung gewonnenen theoretischen Erkenntnisse exemplarisch an diesen Netzindustrien aufzuzeigen und die im Folgenden formulierte Arbeitshypothese zu überprüfen.<br><br> 3. Methodik<br><br> Die Arbeit gliedert sich in einen theoretischen und einen empirischen Teil. Die theoretisch zu untersuchende Frage bei der Liberalisierung von Netzindustrien lautet: Welcher institutionellen Arrangements bedarf es in Netzindustrien, um vormals monopolistisch organisierte in kompetitive Märkte zu überführen und darin nachhaltig einen effektiven Wettbewerb zu etablieren? Auf der Grundlage der erarbeiteten ordnungs- und wettbewerbsökonomischen Erkenntnisse wird nach allgemeingültigen Kriterien gesucht, um daraus einen Bewertungsmaßstab für den intersektoralen Vergleich von Liberalisierungsprozessen in verschiedenen Netzindustrien zu entwickeln. Als Arbeitsthese der empirischen Überprüfung im zweiten Teil dient die aus verschiedenen ökonomischen Blickwinkeln gewonnene und theoretisch zu fundierende Vermutung, dass es zur wirksamen Marktöffnung in Netzindustrien einer materiellen Privatisierung sowie einer effektiven und effizienten Marktmachtkontrolle im Bereich des Zugangs zur Netzinfrastruktur bedarf. Anhand dieser These werden die Liberalisierungsprozesse in den Netzsektoren Schienenverkehr, Telekommunikation sowie Energieversorgung in der Bundesrepublik Deutschland aus volkswirtschaftlicher Sicht beurteilt, und es wird auf verbleibenden ordnungspolitischen Reformbedarf hingewiesen. Die theoretischen Ergebnisse sind indes auch auf ähnliche, hier nicht dargestellte Infrastruktursektoren übertragbar. / The liberalisation of network based industries represents an economic problem, which raises on the one hand a multiplicity of theoretically unresolved questions and for which exist now on the other hand experiences in economic policy in Germany. The causes of the economic problems are not only to be found thereby in certain industry characteristics of the network based industries, but also in a missed special treatment of the network based economic sectors in the past by the economic policy. However, competition pushes in network based industries at borders, because the infrastructure necessary for the production of network based services typically represents an non-open to attack, natural monopoly in the hand of an established, vertically integrated supplier. From it extensive possibilities for the discrimination of competitors result, the competition political action need draw. It applies to analyze these in the available work and to discuss alternative solutions of the discrimination problem.

Thesis (Ed.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / This study is an historical analysis of Brown University and Massachusetts Institute of Technology faculty engagement with network-based courseware development between 1983 and 2003. Specifically, the research focused on how and why faculty engaging in work with Intermedia and Project Athena undertook their projects, what pedagogical models they employed, and what factors contributed to the success and longevity of their courseware. Data collection models included interviews with faculty, project coordinators and technical staff, review of the courseware applications, and examination of internal and external documentation about each project. The findings indicated that faculty tended to utilize the same pedagogical methods in software as they already did in regular teaching, turning to the computer primarily for areas that were difficult to teach or learn; that continued faculty commitment to expanding and updating the software was necessary for sustainability; that faculty perceived their projects as having been successful in increasing student learning and communication despite the fact that formal evaluation was rarely undertaken; and that faculty in the Humanities were more likely to use the network to foster communication and collaboration, while Science and Engineering faculty used the network as a means of disseminating modelling and simulation applications. / 2031-01-02

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ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / Networked based technologies (i.e. TCP/IP) have come to play an important role in the evolution of telemetry post processing services. A paramount issue when using networking to access/move telemetry data is security. In past years papers have focused on individual security technologies and how they could be used to secure telemetry data. This paper will review currently available network based security technologies, update readers on enhancements, and discuss their appropriate uses in the various phases of telemetry post-processing and analysis activities.

Intrusion Prevention Systems (IPSs) have long been proposed as a defense against attacks that propagate too fast for any manual response to be useful. While purely-network-based IPSs have the advantage of being easy to install and manage, research have shown that this class of systems are vulnerable to evasion [70, 65], and can be tricked into filtering normal traffic and create more harm than good [12, 13]. Based on these researches, we believe information about how the attacked hosts process the malicious input is essential to an effective and reliable IPS. In existing IPSs, honeypots are usually used to collect such information. The collected information will then be analyzed to generate countermeasures against the observed attack. Unfortunately, techniques that allow the honeypots in a network to be identified ([5, 71]) can render these IPSs useless. In particular, attacks can be designed to avoid targeting the identified honeypots. As a result, the IPSs will have no information about the attacks, and thus no countermeasure will ever be generated. The use of honeypots is also creating other practical issues which limit the usefulness/feasibility of many host-based IPSs. We propose to solve these problems by duplicating the detection and analysis capability on every protected system; i.e., turning every host into a honeypot. / text

An increased popularity in the learning of foreign languages has led to a rise in demand for language exchanges1. However, students learning foreign languages in their home countries often lack sufficient after-class opportunities to practice their newly acquired skills with native speakers. Language schools offer practice opportunities, but these are often limited, leaving students to seek out language exchange partners on their own, or do without the additional practice. Related to this situation and to this body of work are modern advancements in information technology (IT). Advancements in IT have made the exchange of information across networked platforms affordable and readily accessible to many. People use computers, mobile phones, personal communication devices and newer technologies like Skype phones and instant messenger programs to share data and voice almost anytime and anywhere. These developments, together with the needs foreign language students have for greater chances to practice, create opportunities for firms with the right assets and competencies to serve and prosper. The following business plan explores elements of a concept firm designed to fill unmet needs of language learners. Called NetSpeak!, the firm would leverage the power of IT to create systems that would enable people to practice newly acquired language skills with native speakers located in other parts the world via personal digital assistants (PDAs), personal computers, telephones and networked infrastructure. Thus, NetSpeak!’s principal business activity would be that of making 1 A language exchange is an informal meeting between people (usually two) of different tongues for the purpose of taking turns practicing and coaching language skill development. network-based language exchanges a viable alternative to face-to-face language exchanges. To estimate market attractiveness for such a venture, this body of work first describes elements of the firm and its business strategies, and then presents analyses of customers, markets, competition, as well as the overall general environment that such a firm would compete in. It was found that in a new market—one defined by the unique attributes of network-based language exchange services—where barriers to entry/exit are low, relatively low startup capitalization would lead to a large number of rival participants rendering an unattractive market. However, it was also found that for a first-mover, one that could successfully establish significant barriers to entry, the market attractiveness would be high.