Performance analysis of CAR: Centralized adaptive reservation

A centralized adaptive reservation (CAR) protocol has been proposed in [1] for supporting constant bit rate (CBR), variable bit rate (VBR) and unspecified bit rate (UBR) services in a starconfigured network. This protocol has two main features. First, both the access probability and the bandwidth for reservation requests are varied dynamically to enhance efficiency. Second, by using a request-mini-slot method, UBR traffic can only utilize the residual bandwidth of the other traffic. In this paper, we derive a Markov chain model for analyzing the performance of the CAR protocol by means of a bi-state traffic source. The focus is to analyze the performance of the VBR stations when both the access probability and the bandwidth for reservation requests are changed dynamically.published_or_final_versio

Genesis and emplacement of felsic Variscan plutons within a deep crustal lineation, the Penacova-Regua-Verin fault: An integrated geophysics and geochemical study (NW Iberian Peninsula)

Multidisciplinary studies integrating, U-Pb geochronology, whole-rock geochemical data, isotope geochemistry, anisotropy of magnetic susceptibility (AMS) studies and gravimetry were carried out on the Vila Pouca de Aguiar and the Aguas Frias-Chaves porphyritic biotite granite plutons. Both plutons occur independently in a distance of about 20 km. The Vila Pouca de Aguiar and Aguas Frias-Chaves plutons are examples of late to post-orogenic felsic Variscan granites in northern Portugal (NW Iberian Peninsula). The U-Pb zircon analyses yield a consistent age of 299 +/- 3 Ma which is considered to be the emplacement age of the two plutons. These granites are weakly peraluminous, show high HREE and Y (and low P) contents which are consistent with them being I-type. This is also supported by their weakly evolved isotopic compositions, (87)Sr/(86)Sr(i) = 0.7044-0.7077 and epsilon Nd = - 2.0 to - 2.6, as well as by the whole rock oxygen isotope (delta(18)O VSMOW) ranging from + 9.7 parts per thousand to + 11.0 parts per thousand. The emplacement of granite magma took place after the third Variscan deformation phase (D(3)) in an extensional tectonic regime, large scale uplift and crustal thinning. The integration of different data suggests that both plutons have the same feeding zone aligned within the Penacova-Regua-Verin fault (PRVF) and that both have the same structure which is related to late Variscan phases. The thicker shape for the Aguas Frias-Chaves pluton comparing to that of the Vila Pouca de Aguiar pluton is compatible with different depths of PRVF sectors. The available data led us to propose a model of partial melting of a meta-igneous lower crustal source rather than an open-system of mantle-crust interaction. The interaction between the continental crust and invading malfic magmas could have been limited to mere heat transfer and, perhaps, local intermingling

Active routing service for the next-generation network/ISDN3

In recent years, a new routing method, known as active routing, has been emerging. This involves using active packets to configure customized network paths. Based on a Markov decision model, this paper presents an active routing service for active networks in general and the next generation network, called ISDN3, in particular. Our aim is to determine the active routing policy so as to minimize the network cost. Theoretical analysis is presented to show the advantages of our proposal as compared with three other approaches.published_or_final_versio

ISDN3: The next generation networks

Two generations of Integrated Services Digital Network (ISDN), namely ISDN1 and ISDN2, have been developed in the last century. In our view, the convergence of ATM, Internet and active networks will form the basis for the next generation networks called ISDN3. In this paper, we first review ISDN1 and ISDN2 as well as the Internet and active networks. We then discuss some fundamental questions related to the design of ISDN3. Finally, we compare ISDN3 with ISDN1 and ISDN2, and outline what ISDN3 might look like.published_or_final_versio