860 research outputs found
Exploiting robustness in asynchronous circuits to design fine-tunable systems
PhD ThesisRobustness property in a circuit defines its tolerance to the effects of process, voltage and
temperature variations. The mode signaling and event communication between computing
units in a asynchronous circuits makes them inherently robust. The level of robustness
depends on the type of delay assumptions used in the design and specification process.
In this thesis, two approaches to exploiting robustness in asynchronous circuits to design
self-adapting and fine-tunable systems are investigated. In the first investigation, a Digitally
Controllable Oscillator (DCO) and a computing unit are integrated such that the operating
conditions of the computing unit modulated the operation of the DCO. In this investigation,
the computing unit which is a self-timed counter interacts with the DCO in a four-phase
handshake protocol. This mode of interaction ensures a DCO and computing unit system
that can fine-tune its operation to adapt to the effects of variations. In this investigation, it
is shown that such a system will operate correctly in wide range of voltage supply. In the
second investigation, a Digital Pulse-Width Modulator (DPWM) with coarse and fine-tune
controls is designed using two Kessels counters. The coarse control of the DPWM tuned the
pulse ratio and pulse frequency while the fine-tune control exploited the robustness property
of asynchronous circuits in an addition-based delay system to add or subtract delay(s) to
the pulse width while maintaining a constant pulse frequency. The DPWM realized gave
constant duty ratio regardless of the operating voltage. This type of DPWM has practical
application in a DC-DC converter circuit to tune the output voltage of the converter in high
resolution. The Kessels counter is a loadable self-timed modulo−n counter, which is realized
by decomposition using Horner’s method, specified and verified using formal asynchronous
design techniques. The decomposition method used introduced parallelism in the system by
dividing the counter into a systolic array of cells, with each cell further decomposed into
two parts that have distinct defined operations. Specification of the decomposed counter cell
parts operation was in three stages. The first stage employed high-level specification using
Labelled Petri nets (LPN). In this form, functional correctness of the decomposed counter is
modelled and verified. In the second stage, a cell part is specified by combing all possible
operations for that cell part in high-level form. With this approach, a combination of inputs
from a defined control block activated the correct operation for a cell part. In the final stage,
the LPNs were converted to Signal Transition Graphs, from which the logic circuits of the
cells were synthesized using the WorkCraft Tool. In this thesis, the Kessels counter was
implemented and fabricated in 350 nm CMOS Technology.Niger Delta Development Commission (NDD
Formal techniques for the procedural control of industrial processes
Imperial Users onl
Tools and Algorithms for the Construction and Analysis of Systems
This open access two-volume set constitutes the proceedings of the 27th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2021, which was held during March 27 – April 1, 2021, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2021. The conference was planned to take place in Luxembourg and changed to an online format due to the COVID-19 pandemic. The total of 41 full papers presented in the proceedings was carefully reviewed and selected from 141 submissions. The volume also contains 7 tool papers; 6 Tool Demo papers, 9 SV-Comp Competition Papers. The papers are organized in topical sections as follows: Part I: Game Theory; SMT Verification; Probabilities; Timed Systems; Neural Networks; Analysis of Network Communication. Part II: Verification Techniques (not SMT); Case Studies; Proof Generation/Validation; Tool Papers; Tool Demo Papers; SV-Comp Tool Competition Papers
Actes des Sixièmes journées nationales du Groupement De Recherche CNRS du Génie de la Programmation et du Logiciel
National audienceCe document contient les actes des Sixièmes journées nationales du Groupement De Recherche CNRS du Génie de la Programmation et du Logiciel (GDR GPL) s'étant déroulées au CNAM à Paris du 11 au 13 juin 2014. Les contributions présentées dans ce document ont été sélectionnées par les différents groupes de travail du GDR. Il s'agit de résumés, de nouvelles versions, de posters et de démonstrations qui correspondent à des travaux qui ont déjà été validés par les comités de programmes d'autres conférences et revues et dont les droits appartiennent exclusivement à leurs auteurs
Distributed multimedia systems
A distributed multimedia system (DMS) is an integrated communication, computing, and information system that enables the processing, management, delivery, and presentation of synchronized multimedia information with quality-of-service guarantees. Multimedia information may include discrete media data, such as text, data, and images, and continuous media data, such as video and audio. Such a system enhances human communications by exploiting both visual and aural senses and provides the ultimate flexibility in work and entertainment, allowing one to collaborate with remote participants, view movies on demand, access on-line digital libraries from the desktop, and so forth. In this paper, we present a technical survey of a DMS. We give an overview of distributed multimedia systems, examine the fundamental concept of digital media, identify the applications, and survey the important enabling technologies.published_or_final_versio
Tools and Algorithms for the Construction and Analysis of Systems
This open access book constitutes the proceedings of the 28th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2022, which was held during April 2-7, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 46 full papers and 4 short papers presented in this volume were carefully reviewed and selected from 159 submissions. The proceedings also contain 16 tool papers of the affiliated competition SV-Comp and 1 paper consisting of the competition report. TACAS is a forum for researchers, developers, and users interested in rigorously based tools and algorithms for the construction and analysis of systems. The conference aims to bridge the gaps between different communities with this common interest and to support them in their quest to improve the utility, reliability, exibility, and efficiency of tools and algorithms for building computer-controlled systems
A Petri net-occam based methodology for the development of dependable distributed control software.
Analysis of flexible manufacturing cells (FMCs) shows their requirement for flexible, correct, reliable, safe and distributed control. A comparison of the state of the art in software engineering for parallel systems, and an examination of safety related systems, reveal a need for formal and rigorous techniques at all stages in the software life cycle. However, parallel software, safety related software and formal techniques are complex. It is better to avoid faults rather than eliminate or tolerate them, and although less flexible, avoidance is often simpler to implement. There is a need for a tool which overcomes many of these complexities, and this thesis discusses and defines such a tool in the form of a methodology. The novelty of the work is in the combination of the core goals to manage these issues, and how the strategies guide the user to a solution which will not deadlock and which is comprehensible. Place-transition Petri nets are an ideal representation for designing and modelling the interaction of concurrent (and distributed) processes. Occam is a high level real time parallel language designed to execute on one or a network of transputers. Transputers are processing, memory and communication building blocks, and, together with occam, are shown to be suitable for controlling and communicating the control as the DCS in FMCs. The methodology developed in this thesis adopts the mathematically based tools of Petri nets, occam and transputers, and, by exploiting their structural similarities, incorporates them in a steps and tasks to improve the development of correct, reliable and hence safe occam code. The four steps: identify concurrent and sequential operations, produce Petri net graphs for all controllers, combine controller Petri net graphs and translate Petri net graphs into occam; are structured around three core goals: Petri net/occam equivalence, comprehensibility and pro-activity; which are manifest in four strategies: output-work-backwards, concurrent and sequential actions, structuralise and modularise, and deadlock avoidance. The methodology assists in all stages of the software development life cycle, and is applicable to small DCSs such as an FMC. The methodology begins by assisting in the creation of DCS requirements from the manufacturing requirements of the FMC, and guides the user to the production of dependable occam code. Petri nets allow the requirements to be specified as they are created, and the methodology's imposed restrictions enable the final Petri net design to be translated directly into occam. Thus the mathematics behind the formal tools is hidden from the user, which should be attractive to industry.The methodology is successfully applied to the example FMC, and occam code to simulate the FMC is produced. Due to the novelty of the research, many suggestions for further work are given
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