Abstract
Summary form only given. Shock waves have been extensively investigated in diverse areas of physics. However, their occurrence in optics is rather rare and thus far no such optical structures have been experimentally observed. In this paper we report a new family of kink-antikink shock waves that is possible in unbiased photorefactive media via the two wave mixing process. These waves move together as locked states, and have the interesting property of moving outside their initial ±? sector of propagation. The apparent direction of propagation and the spatial widths of these shock wave beams are directly related to their relative intensity. We provide a detailed analysis of these waves, and we illustrate their behavior with pertinent examples. © 2001 Optical Soc. Of America.

Abstract
Reducing the area overhead required by BIST structures can be achieved by reconfiguring existing hardware to perform test related control and processing functions. This work shows how the resources required for these operations can be implemented in-circuit, taking advantage of programmable logic available in the system. Structural and functional tests are performed using correlation to obtain iDD and uOUT cross-correlation signatures, and to measure gain, phase, and total harmonic distortion. © 2000 IEEE.

Abstract
Communications in high-speed wireless mobile networks have to deal with large varying transmission and service requirement conditions, often needing complex radio modulatians and concatenated error control functions. For the latter, it is usual to implement Forward Error Correction and Automatic Repeat reQuest (ARQ) mechanisms in, respectively, the Physical (PHY) and the Data Link Control (DLC) layers. Even so, the communication requirements of medium/high quality real-time services may be hard to meet under hostile transmission conditions. In this paper an analysis on some improvements over current ARQ error control schemes is presented, envisaging more efficient communications in high-speed wireless LANs. It will be shown that high performance ARQ schemes can be used at the DLC layer of wireless LANs by carrying critical control information in more robust physical modes. performance comparisons for current and proposed ARQ schemes, and some protocol implementation aspects, are the main focuses of analysis.

Abstract
In this paper we present an experimental approach for QoS-aware and bandwidth-efficient transmission of multimedia sources over ATM networks. VBR video sources are statistically multiplexed at the application level and the UPC parameters of a single connection for the aggregate traffic are dynamically renegotiated with the network during the session lifetime. A statistical multiplexer computes the required bandwidth for the aggregate traffic and dynamically assigns bandwidth according to the performances requested and network resources availability. A dynamic UPC manager using feedback information sent by the network, may initiate a renegotiation of traffic parameters upon receiving a request from the statistical multiplexer. Performing the connection admission control procedures for the aggregate traffic, allows significant reductions in the value of the total peak rate when compared to the sum of peak rates of individual connections. It also reduces the burstiness of the flow submitted to the network, thus increasing the lifetime of each set of UPC parameters. © Springer-Verlag Berlin Heidelberg 2000.

Abstract
In this paper we present an experimental approach for QoS-aware and bandwidth-efficient transmission of multimedia sources over ATM networks. VER video sources are statistically multiplexed at the application level and the UPC parameters of a single connection for the aggregate traffic are dynamically renegotiated with the network during the session lifetime, A statistical multiplexer computes the required bandwidth for the aggregate traffic and dynamically assigns bandwidth according to the performances requested and network resources availability. A dynamic UPC manager using feedback information sent by the network, may initiate a renegotiation of traffic parameters upon receiving a request from the statistical multiplexer. Performing the connection admission control procedures for the aggregate traffic, allows significant reductions in the value of the total peak rate when compared to the sum of peak rates of individual connections. It also reduces the burstiness of the flow submitted to the network, thus increasing the lifetime of each set of UPC parameters.

Abstract