Internet traffic engineering

The main goal of Internet traffic engineering is to efficiently optimize the performance of operational networks in order to avoid the well-known shortcomings of the typical destination-based IP routing. Traffic engineering attempts to reduce or even avoid congestion hot spots and to improve resource utilization across the backbone IP network. During the last years traffic engineering has become an inevitable tool concerning performance optimization in large Internet backbones. The core objective of this paper is to give an overview of the architectures and mechanisms for traffic engineering.     

Nichtlinearer digitaler Reibungsbeobachter zur adaptiven Reibungskompensation bei Bewegungsregelungen

Friction can deteriorate the tracking behavior of motion control. By use of a friction observer an estimated value of the friction can be determined and through adaptive compensation of the friction its influence can be weakened. The following article developes a new digital nonlinear friction observer on ground of an already known continuous nonlinear friction observer, which can easily be parametrized. A mechanical model is used to compare this nonlinear friction observer with a linear one during simulations and real time investigation. The investigation shows that the effect of deterioration of the tracking behavior through friction is less significant with the new digital nonlinear friction observer than with the linear friction observer.     

Die Lösung des feldtheoretischen Viermedienproblems ebener Schichten

Übersicht In der Praxis tritt häufig der Fall eines in ebene Materieschichten geteilten Raumes auf. Die so entstehenden Feldprobleme werden für vier Schichten analytisch gelöst, womit sich der numerische Rechenaufwand stark verringern läßt. Der Lösungsgang mit der Spiegelungsmethode erfolgt systematisch konstruktiv vom Zweimedienproblem über das Dreimedienproblem. Die Lösung ist unabhängig von der Form der feldverursachenden Quellen. Dadurch sind die Felder aller Quellenanordnungen, die im unbegrenzten homogenen Raum angebbar sind, nunmehr auch im vierfach geschichteten Raum bekannt. Die Spiegelquellen können darüber hinaus zur Berechnung von Kräften dienen. Als Anwendungsbeispiel werden Kapazitätsbeläge gekoppelter Mikrostripleitungen berechnet.

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Solving fourmedia problems of plane layers in field theory

Contents Arrangements with plane layers of material are quite common. The analytical solution of the four layers problem greatly facilitates subsequent numerical calculations. The procedure is based on the fundamental twomedia and threemedia arrangements. No restrictions must be imposed on the shapes of the field's sources. Thus, for arbitrary distributions of sources the field can be given, if it is available in unbounded homogenious material. The image sources also can serve for the calculation of forces. As an example the mutual capacities of microstrip lines are calculated.

     

50 Jahre Kybernetik in Österreich

The term “cybernetics” is very old, but in the middle of the last century it gained new importance as steering brought new aspects to the area of information technology. This paper deals with the general history of cybernetics and then describes the beginning of this field at Vienna University of Technology. In this context it was an important step, when the book “Cybernetics” by Norbert Wiener first came to Vienna; thus the interest in cybernetic models evolved. Originating from the interest in cybernetic models, three models were recreated (and refined):

1. the model of the conditioned reflex (artificial tortoise),
2. the model of orientation in a maze (mouse), and
3. the model of homeostasis (homeostat).

The third and final part of this paper illustrates the gradual transition to artificial intelligence (AI). Hopes that were tied up with this term are discussed. Apart from that the question of how much has been left of cybernetics and artificial intelligence today is raised. The mouse in the maze is very closely connected to our Emeritus: He built the Viennese version of it as part of his diploma thesis.     

IT-Security in der Energieautomatisierung

The increasing use of information technology in energy distribution and the wide interconnection of such systems bring security issues into the focus of interest. This contribution introduces the essential concepts and concentrates on specific security requirements and risks in energy automation. At the example of the two different data acquisition systems REMPLI and JEVis a possible implementation of security concepts is discussed.     

Switched beams versus beam pointing for boosting the downlink capacity of UMTS FDD

In this paper the switched beam method is compared with beam pointing. Using extensive system simulations it is shown that both methods achieve a capacity gain over a 3-sectored reference system of more than 170%. As the capacity achieved with the two systems is nearly the same but the complexity of beam pointing is significantly higher, I conclude that switched beams are the appropriate method for boosting the downlink capacity of UMTS FDD.     

Vier Jahre Selbstregulierung der Telekommunikation in österreich

The year 1998 marked the liberalization of the speech telephony market in the European Union. Regulatory bodies and operators were challenged to create a regulatory and technical environment in order to forge the emerging patchwork of infrastructure into a homogenous telecommunications network. In addition to regulatory proceedings it was essential to launch a multilateral forum for the discussion of administrative, operative and accounting problems. In March 1999 the Austrian Telecommunications Operator Forum (AK-TK) was formed. This article deals with the experience of four years operator’s negotiations in the emerging telecom market.     

Windenergieausbau als Teil der Ökostromentwicklung

The new law for the support of electricity produced by renewable sources in Austria (Ökostromgesetz) which came into force with the beginning of 2003, shows its impacts already after the first months. Investments into wind power have increased considerably. These will be accompanied by activities for electricity production by biomass and biogas. The 4%-target quota will probably be reached earlier than the 2008 target period of the law.     

Investitionsbedarf und zukünftige Bedeutung der Versorgungssicherheit in Europa und Österreich

Europe urgently needs an investment boom in the fields of power generation, transmission, and distribution. Until 2030 the current generation portfolio will de facto have to be replaced. Especially in the liberalized market environment, investors rely on a clear and uncompromising regulatory environment, which is still lacking today. The investments required will only happen, if political commitment results in easier and fast-track licensing procedures. Clearly formulated energy targets for Europe and uncompromising free market approaches at EU and national level are the key to guarantee trust in a sufficiently stable regulatory environment. They are also a prerequisite for ensuring that market signals for investments will be acted upon.