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Publications

Publications by HASLab

2013

Automated theorem proving for the systematic analysis of an infusion pump

Authors
Harrison, MD; Masci, P; Campos, JC; Curzon, P;

Publication
Electron. Commun. Eur. Assoc. Softw. Sci. Technol.

Abstract
This paper describes the use of an automated theorem prover to analyse properties of interactive behaviour. It offers an alternative to model checking for the analysis of interactive systems. There are situations, for example when demonstrating safety, in which alternative complementary analyses provide assurance to the regulator. The rigour and detail offered by theorem proving makes it possible to explore features of the design of the interactive system, as modelled, beyond those that would be revealed using model checking. Theorem proving can also speed up proof in some circumstances. The paper illustrates how a theory generated as a basis for theorem proving (using PVS) was developed systematically from a MAL model used to model check the same properties. It also shows how the CTL properties used to check the original model can be translated into theorems.

2013

The Mobile Context Framework: Providing Context to Mobile Applications

Authors
Oliveira, L; Ribeiro, AN; Campos, JC;

Publication
HCI (25)

Abstract
The spread of mobile devices in modern societies has forced the industry to create software paradigms to meet the new challenges it faces. Some of these challenges are the huge heterogeneity of devices or the quick changes of users' context. In this scenario, context becomes a key element, enabling mobile applications to be user centric and adapt to user requirements. The Mobile Context Framework, proposed in this paper, is a contribution to solve some of these challenges. Using Web servers running on the devices, context data can be provided to web applications. Besides the framework's architecture, a prototype is presented as proof of concept of the platform's potential. © 2013 Springer-Verlag Berlin Heidelberg.

2013

Depth Cues and Perceived Audiovisual Synchrony of Biological Motion

Authors
Silva, CC; Mendonca, C; Mouta, S; Silva, R; Campos, JC; Santos, J;

Publication
PLOS ONE

Abstract
Background: Due to their different propagation times, visual and auditory signals from external events arrive at the human sensory receptors with a disparate delay. This delay consistently varies with distance, but, despite such variability, most events are perceived as synchronic. There is, however, contradictory data and claims regarding the existence of compensatory mechanisms for distance in simultaneity judgments. Principal Findings: In this paper we have used familiar audiovisual events - a visual walker and footstep sounds and manipulated the number of depth cues. In a simultaneity judgment task we presented a large range of stimulus onset asynchronies corresponding to distances of up to 35 meters. We found an effect of distance over the simultaneity estimates, with greater distances requiring larger stimulus onset asynchronies, and vision always leading. This effect was stronger when both visual and auditory cues were present but was interestingly not found when depth cues were impoverished. Significance: These findings reveal that there should be an internal mechanism to compensate for audiovisual delays, which critically depends on the depth information available.

2013

An Empirical Study on Immersive Prototyping Dimensions

Authors
Moreira, S; José, R; Campos, JC;

Publication
HCI (1)

Abstract
Many aspects of the human experience of ubiquitous computing in built environments must be explored in the context of the target environment. However, delaying evaluation until a version of the system can be deployed can make redesign too costly. Prototypes have the potential to solve this problem by enabling evaluation before actual deployment. This paper presents a study of the design space of immersive prototyping for ubiquitous computing. It provides a framework to guide the alignment between specific evaluation goals and specific prototype properties. The goal is to understand the potential added-value of 3D simulation as a prototyping tool in the development process of ubiquitous computing environments. © 2013 Springer-Verlag.

2013

Combining static and dynamic analysis for the reverse engineering of web applications

Authors
Silva, CE; Campos, JC;

Publication
EICS

Abstract
Software has become so complex that it is increasingly hard to have a complete understanding of how a particular system will behave. Web applications, their user interfaces in particular, are built with a wide variety of technologies making them particularly hard to debug and maintain. Reverse engineering techniques, either through static analysis of the code or dynamic analysis of the running application, can be used to help gain this understanding. Each type of technique has its limitations. With static analysis it is difficult to have good coverage of highly dynamic applications, while dynamic analysis faces problems with guaranteeing that generated models fully capture the behavior of the system. This paper proposes a new hybrid approach for the reverse engineering of web applications' user interfaces. The approach combines dynamic analyzes of the application at runtime, with static analyzes of the source code of the event handlers found during interaction. Information derived from the source code is both directly added to the generated models, and used to guide the dynamic analysis. Copyright 2013 ACM.

2013

A Specification Patterns System for Discrete Event Systems Analysis

Authors
Campos, JC; Machado, J;

Publication
INTERNATIONAL JOURNAL OF ADVANCED ROBOTIC SYSTEMS

Abstract
As formal verification tools gain popularity, the problem arises of making them more accessible to engineers. A correct understanding of the logics used to express the properties of a system's behaviour is needed in order to guarantee that properties correctly encode the intent of the verification process. Writing appropriate properties, in a logic suitable for verification, is a skilful process. Errors in this step of the process can create serious problems since a false sense of safety is gained from the analysis. However, when compared to the effort put into developing and applying modelling languages, little attention has been devoted to the process of writing properties that accurately capture verification requirements. In this paper we illustrate how a collection of property patterns can help in simplifying the process of generating logical formulae from informally expressed requirements.

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