3,079 research outputs found
Some issues related to simulation of the tracking and communications computer network
The Communications Performance and Integration branch of the Tracking and Communications Division has an ongoing involvement in the simulation of its flight hardware for Space Station Freedom. Specifically, the communication process between central processor(s) and orbital replaceable units (ORU's) is simulated with varying degrees of fidelity. The results of investigations into three aspects of this simulation effort are given. The most general area involves the use of computer assisted software engineering (CASE) tools for this particular simulation. The second area of interest is simulation methods for systems of mixed hardware and software. The final area investigated is the application of simulation methods to one of the proposed computer network protocols for space station, specifically IEEE 802.4
Distributed Real-Time Emulation of Formally-Defined Patterns for Safe Medical Device Control
Safety of medical devices and of their interoperation is an unresolved issue
causing severe and sometimes deadly accidents for patients with shocking
frequency. Formal methods, particularly in support of highly reusable and
provably safe patterns which can be instantiated to many device instances can
help in this regard. However, this still leaves open the issue of how to pass
from their formal specifications in logical time to executable emulations that
can interoperate in physical time with other devices and with simulations of
patient and/or doctor behaviors. This work presents a specification-based
methodology in which virtual emulation environments can be easily developed
from formal specifications in Real-Time Maude, and can support interactions
with other real devices and with simulation models. This general methodology is
explained in detail and is illustrated with two concrete scenarios which are
both instances of a common safe formal pattern: one scenario involves the
interaction of a provably safe pacemaker with a simulated heart; the other
involves the interaction of a safe controller for patient-induced analgesia
with a real syringe pump.Comment: In Proceedings RTRTS 2010, arXiv:1009.398
Context sensitive user interfaces
This paper presents a conceptual design model for user interfaces (MASS1) and a general formalism for dialogue specification (Interaction Scripts) which are the most important components of an approach to the methodological, iterative design of Interactive Systems from formal, model-based specification of both the application and the User Interface (UI).
This approach allows the integration of both dialogue and application semantics from the beginning of the design process, by using prototypes derived from both specifications. Assuming that all the application semantics is available at early design stages, the MASS model defines a set of guidelines that will enforce the designer to create user interfaces that will present a prophylactic instead of the usual therapeutic behaviour. By a prophylactic behaviour it is meant, metaphorically, that the UI will exhibit a behaviour that prevents and avoids both syntactic and semantic user errors, in contrast with the most usual therapeutic, or error recovery, behaviour.
The dialogue specification formalism(Interaction Scripts) despite being general, in the sense that it may be applied to the specification of any kind of dialogue, is specially suited to the specification of UIs with the behaviour prescribed by the MASS design model. In addition, it is independent from concrete environment details, therefore allowing for different implementations of the same specification, that is, different looks and feels. The operational semantics of the Interaction Script notation is also presented in terms of Petri-Nets that are automatically generated from the Interaction Script specification of the dialogue controller
Interactive Music and Synchronous Reactive Programming
This paper presents Skini, a programming methodology and an execution
environment for interactive structured music. With this system, the composer
programs his scores in the HipHop.js synchronous reactive language. They are
then executed, or played, in live concerts, in interaction with the audience.
The system aims at helping composers to find a good balance between the
determinism of the compositions and the nondeterminism of the interactions with
the public. Each execution of a Skini score yields to a different but
aesthetically consistent interpretation. This work raises many questions in the
musical fields. How to combine composition and interaction? How to control the
musical style when the audience influences what is to play next? What are the
possible connections with generative music? These are important questions for
the Skini system but they are out of the scope of this paper that focuses
exclusively on the computer science aspects of the system. From that
perspective, the main questions are how to program the scores and in which
language? General purpose languages are inappropriate because their elementary
constructs (i.e., variables, functions, loops, etc.) do not match the
constructions needed to express music and musical constraints. We show that
synchronous programming languages are a much better fit because they rely on
temporal constructs that can be directly used to represent musical scores and
because their malleability enables composers to experiment easily with artistic
variations of their initial scores. The paper mostly focuses on scores
programming. It exposes the process a composer should follow from his very
first musical intuitions up to the generation of a musical artifact. The paper
presents some excerpts of the programming of a classical music composition that
it then precisely relates to an actual recording. Examples of techno music and
jazz are also presented, with audio artifact, to demonstrate the versatility of
the system. Finally, brief presentations of past live concerts are presented as
an evidence of viability of the system
Time At Your Service: Schedulability Analysis of Real-Time and Distributed Services
The software today is distributed over several processing units. At a large scale this may span over the globe via the internet, or at the micro scale, a software may be distributed on several small processing units embedded in one device. Real-time distributed software and services need to be timely and respond to the requests in time. The Quality of Service of real time software depends on how it schedules its tasks to be executed. The state of the art in programming distributed software, like in Java, the scheduling is left to the underlying infrastructure and in particular the operating system, which is not anymore in the control of the applications. In this thesis, we introduce a software paradigm based on object orientation in which real-time concurrent objects are enabled to specify their own scheduling strategy. We developed high-level formal models for specifying distributed software based on this paradigm in which the quality of service requirements are specified as deadlines on performing and finishing tasks. At this level we developed techniques to verify that these requirements are satisfied. This research has opened the way to a new approach to modeling and analysis of a range of applications such as continuous planning in the context of logistics software in a dynamic environment as well as developing software for multi-core systems. Industrial companies (DEAL services) and research centers (the Uppsala Programming for Multicore Architectures Resrearch Center UPMARC) have already shown interest in the results of this thesis.LEI Universiteit LeidenFoundations of Software Technolog
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