Forced simulation : a formal approach to component based development of embedded systems

Application specific digital systems, called embedded systems, touch almost every aspect of modern human life. As a result, there is considerable interest in automating the design (called synthesis) of these systems. Further, given the time-to-market pressures and increasing system complexities, component reuse during synthesis is being touted as a key to success. This thesis proposes a formal framework for reusing system-level components during synthesis. Within the framework for component reuse, component matching is a key problem that must be addressed. Given the specification of a design function, and a device stored as a component in a library, component matching addresses the question of whether the device can implement the function. Often system-level components are multi-functional and generic, and it is rarely the case that the function is directly realizable by a device. Hence, an important aspect of matching is to decide whether the device can be dynamically adapted to match the function. This thesis proposes a formalization of the matching problem using formal models of the function and device, denoted by F and D respectively. D matches F provided there exists an interface I that adapts D dynamically to produce the same behaviour as F. None of the existing implementation verification techniques within formal methods can be used to test for the existence of an I between arbitrary pairs of F and D. In this thesis, a new simulation relation called forced simulation is proposed between the states of F and D. It is then formally established that the existence of a forced simulation relation is a necessary and sufficient condition for the existence of I for a pair of F and d. Two kinds of forced simulation are proposed, one each for synchronous and asynchronous interactions with the environment. Based on forced simulation, a polynomial time algorithm for automatic matching of F and D is also developed. The distinguishing feature of the algorithm is that when successful, it generates an interface that automatically adapts the device to behave like the function. The algorithm is illustrated by reusing two rogrammable components from Intel and some typical embedded controllers

Consistent simulation of non-resonant diphoton production at hadron collisions with a custom-made parton shower

We have developed a Monte Carlo event generator for non-resonant diphoton ($\gamma\gamma$) production at hadron collisions in the framework of GR@PPA, which consistently includes additional one-jet production. The jet-matching method developed for initial-state jet production has been extended to the final state in order to regularize the final-state QED divergence in the $qg \rightarrow \gamma\gamma + q$ process. A QCD/QED-mixed parton shower (PS) has been developed to complete the matching. The PS has the capability of enforcing hard-photon radiation, and small-$Q^{2}$ photon radiations that are not covered by the PS are supplemented by using a fragmentation function. The generated events can be passed to general-purpose event generators in order to perform the simulations down to the hadron level. Thus, we can simulate the isolation requirements that must be applied in experiments at the hadron level. The simulation results are in reasonable agreement with the predictions from RESBOS and DIPHOX. The simulated hadron-level events can be further fed to detector simulations in order to investigate the detailed performance of experiments.Comment: 23 pages, 15 figure

A Framework for Dynamic Web Services Composition

Dynamic composition of web services is a promising approach and at the same time a challenging research area for the dissemination of service-oriented applications. It is widely recognised that service semantics is a key element for the dynamic composition of Web services, since it allows the unambiguous descriptions of a service's capabilities and parameters. This paper introduces a framework for performing dynamic service composition by exploiting the semantic matchmaking between service parameters (i.e., outputs and inputs) to enable their interconnection and interaction. The basic assumption of the framework is that matchmaking enables finding semantic compatibilities among independently defined service descriptions. We also developed a composition algorithm that follows a semantic graph-based approach, in which a graph represents service compositions and the nodes of this graph represent semantic connections between services. Moreover, functional and non-functional properties of services are considered, to enable the computation of relevant and most suitable service compositions for some service request. The suggested end-to-end functional level service composition framework is illustrated with a realistic application scenario from the IST SPICE project

Modeling Earthen Dike Stability: Sensitivity Analysis and Automatic Calibration of Diffusivities Based on Live Sensor Data

The paper describes concept and implementation details of integrating a finite element module for dike stability analysis Virtual Dike into an early warning system for flood protection. The module operates in real-time mode and includes fluid and structural sub-models for simulation of porous flow through the dike and for dike stability analysis. Real-time measurements obtained from pore pressure sensors are fed into the simulation module, to be compared with simulated pore pressure dynamics. Implementation of the module has been performed for a real-world test case - an earthen levee protecting a sea-port in Groningen, the Netherlands. Sensitivity analysis and calibration of diffusivities have been performed for tidal fluctuations. An algorithm for automatic diffusivities calibration for a heterogeneous dike is proposed and studied. Analytical solutions describing tidal propagation in one-dimensional saturated aquifer are employed in the algorithm to generate initial estimates of diffusivities

An effective AMS Top-Down Methodology Applied to the Design of a Mixed-SignalUWB System-on-Chip

The design of Ultra Wideband (UWB) mixed-signal SoC for localization applications in wireless personal area networks is currently investigated by several researchers. The complexity of the design claims for effective top-down methodologies. We propose a layered approach based on VHDL-AMS for the first design stages and on an intelligent use of a circuit-level simulator for the transistor-level phase. We apply the latter just to one block at a time and wrap it within the system-level VHDL-AMS description. This method allows to capture the impact of circuit-level design choices and non-idealities on system performance. To demonstrate the effectiveness of the methodology we show how the refinement of the design affects specific UWB system parameters such as bit-error rate and localization estimations