Reconfigurable Systems

From the above the importance of advances in electronic hardware, in particular ASICs, on the development of intelligent sensors is clearly evident. The role of software drivers is equally essential, as these control and perform the necessary tasks in test, calibration and operating modes [16]. Additionally, the software is responsible for ensuring correct coimnunication between 

The switch configuration is stored as a vector of noughts and ones in two, 8-bit bytes. Each configuration is therefore represented by a unique 16-bit word which is stored in the memory space of the controlling digital processor. The sub-system can be switched into a specific self-check or auto-calibration mode with only a few control instructions [17]. 

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Multifunction, reconfigurable system High-level functions tasks of daily life (working, grooming, recreation, etc.) Functional assessment scales Single-number global index Level of indep. estimates... 

Due to the dynamic behavior of reconfigurable fault-tolerant systems, the creation of stochastic dependability models is a difficult task. Traditional techniques like fault trees or rehabdity block diagrams are no longer sufficient in many cases, because they assume all components to be of a Boolean nature. However, in today s adaptable and reconfigurable systems, components must be described by more than the states active and failed in order to reflect the different roles of a component in a reconfigurable system. Moreover, often the system itself is not considered to be Boolean, but different failure classes are discriminated. Finally, the basic events (component failures and repairs) cannot be assumed to be independent, but common cause failure, failure propagation, limited repair capacities etc. must be taken into account. 

In general, the behavior of a module is composed of different aspects (also called behaviors or traits). As an example, one behavior could be the level of operation of the system (with states fully functional, degraded and failed), and another aspect could be the way in which the module is used as a spare within the overall, reconfigurable system (with states idle, used by subsysl, used by subsys2). Each such behavior corresponds to one dimension of the module s state space, and a possible combined state would be the tuple (degraded, used by subsys2). 

In this paper we have introduced the LARES formalism for the specification of dependability models of reconfigurable systems. The formalism follows a structured hierarchical approach and includes features that allow the user to describe arbitrarily complex dynamic behavior. The paper described the textual user interface, concretized by two examples from the literature. Next steps will include the definition of a formal semantics for LARES. Based on this semantics, we will develop model transformations in order to automatically convert different application-specific modeling formalisms to the LARES formalism, and implement interfaces to existing analysis engines, which will be used to perform the quantitative analysis of the specified models. 

The average PFD for the reconfigured system can simply be approximated by the time-weighted PFD of the 2oo3 and the loo2 systems given by equations 2 and 3, respectively ... 

Touba, D. N. A. (1999), A low cost approach to detecting, locating and avoiding interconnect faults in (FPGAj-based reconfigurable systems. Proceedings of the International conference VLSI design. 

The general purpose is to develop a common body of interdisciplinary knowledge to understand issues and problems related to reconfigurable systems. 

The general problems in reconfigurable systems can be classified as related to the system s environment, availability of appropriate modeling tools, interconnectedness of decisions at various levels of supply chain, and availability of common knowledge throughout the system. These can be fisted as follows ... 

These comments apply immediately to fault injection experiments for reconfigurable systems. 

Markov and semi-Markov models are convenient tools for dynamic (reconfigurable) systems because the states in the model correspond to system states and the transition between states in the model correspond to physical processes (fault occurrence or system recovery). Because of this correspondence, they have become very popular, especially for electronic systems where the devices can be assumed to have a constant failure rate. Their disadvantages stem from their successes. Because of their convenience, they are apphed to large and complex systems, and the models have become hard to generate and compute because of their size (state-space explosion). Markov models assume that transitions between states do not depend on the time spent in the state. (The transitions are memoryless.) Semi-Markov models are more general and let the transition distributions depend on the time spent in the state. This survey dedicates a special section to Markov models. 

Competing events arise naturally in redundant and reconfigurable systems. An important example is the competition between the arrival of a second fault and system recovery from a first fault. 

Sequential events also arise naturally in redundant and reconfigurable systems. A component failure is followed by system recovery. Another component failure is followed by another system recovery. 

Global/composite Height Multifunction, reconfigurable system No single-number direct Subjective self- and family reports... 

Miyazaki, T. (1998). Reconfigurable systems. InProceed-ings of the Design Automation Conference, ASP-DAC 1998, (pp. 447-452). IEEE Press. 

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