José Luis Sevillano

Heuristic Evaluation on Mobile Interfaces: A New Checklist

The rapid evolution and adoption of mobile devices raise new usability challenges, given their limitations (in screen size, battery life, etc.) as well as the specific requirements of this new interaction. Traditional evaluation techniques need to be adapted in order for these requirements to be met. Heuristic evaluation (HE), an Inspection Method based on evaluation conducted by experts over a real system or prototype, is based on checklists which are desktop-centred and do not adequately detect mobile-specific usability issues. In this paper, we propose a compilation of heuristic evaluation checklists taken from the existing bibliography but readapted to new mobile interfaces. Selecting and rearranging these heuristic guidelines offer a tool which works well not just for evaluation but also as a best-practices checklist. The result is a comprehensive checklist which is experimentally evaluated as a design tool. This experimental evaluation involved two software engineers without any specific knowledge about usability, a group of ten users who compared the usability of a first prototype designed without our heuristics, and a second one after applying the proposed checklist. The results of this experiment show the usefulness of the proposed checklist for avoiding usability gaps even with nontrained developers.

Energy efficient wireless sensor network communications based on computational intelligent data fusion for environmental monitoring

The study presents a novel computational intelligence algorithm designed to optimise energy consumption in an environmental monitoring process: specifically, water level measurements in flooded areas. This algorithm aims to obtain a trade-off between accuracy and power consumption. The implementation constitutes a data aggregation and fusion in itself. A harsh environment can make the direct measurement of flood levels a difficult task. This study proposes a flood level estimation, inferred through the measurement of other common environmental variables. The benefit of this algorithm is tested both with simulations and real experiments conducted in Donana, a national park in southern Spain where flood level measurements have traditionally been done manually.

Analysis of source code metrics from ns-2 and ns-3 network simulators

Abstract Ns-2 and its successor ns-3 are discrete-event simulators which are closely related to each other as they share common background, concepts and similar aims. Ns-3 is still under development, but it offers some interesting characteristics for developers while ns-2 still has a large user base. While other studies have compared different network simulators, focusing on performance measurements, in this paper we adopted a different approach by focusing on technical characteristics and using software metrics to obtain useful conclusions. We chose ns-2 and ns-3 for our case study because of the popularity of the former in research and the increasing use of the latter. This reflects the current situation where ns-3 has emerged as a viable alternative to ns-2 due to its features and design. The paper assesses the current state of both projects and their respective evolution supported by the measurements obtained from a broad set of software metrics. By considering other qualitative characteristics we obtained a summary of technical features of both simulators including, architectural design, software dependencies or documentation policies.

Architecture, design and source code comparison of ns-2 and ns-3 network simulators

Ns-2 and its successor ns-3 are discrete-event simulators. Ns-3 is still under development, but offers some interesting characteristics for developers while ns-2 still has a big user base. This paper remarks current differences between both tools from developers point of view. Leaving performance and resources consumption aside, technical issues described in the present paper might help to choose one or another alternative depending of simulation and project management requirements.

A generalization of path following for mobile robots

Several authors have proposed some methods for applying path following in specific cases to mobile robots. When we try to extend the path following approach to the general problem several difficulties arise. We present a generalized technique to apply path following to a mobile robot with nonholonomic constraints. As an application example, we expose the case of mobile robots with a higher degree of manoeuvrability than the typical car-like robots. In particular we consider a robot that can turn around itself making a zero-radius turn; a case still not resolved as far as we know. Finally we propose a suitable control law for this example that ensures asymptotical convergence.

Towards an intelligent and supportive environment for people with physical or cognitive restrictions

AmbienNet environment has been developed with the aim of demonstrating the feasibility of accessible intelligent environments designed to support people with disabilities and older persons living independently. Its main purpose is to examine in depth the advantages and disadvantages of pervasive supporting systems based on the paradigm of Ambient Intelligence for people with sensory, physical or cognitive limitations. Hence diverse supporting technologies and applications have been designed in order to test their accessibility, ease of use and validity. This paper presents the architecture of AmbienNet intelligent environment and an intelligent application to support indoors navigation for smart wheelchairs designed for validation purposes.

PCI-AER interface for neuro-inspired spiking systems

Address event representation (AER) is a neuromorphic interchip communication protocol that allows for real-time connectivity between huge number neurons located on different chips. By exploiting high speed digital communication circuits (nano-seconds), synaptic neural connections can be time multiplexed (mili-seconds). When building multi-chip muti-layered AER systems it is absolutely necessary to have a computer interface that allows: (a) to read AER interchip traffic; and (b) inject a sequence of events to the AER structure. This paper presents a PCI to AER interface, that dispatches a sequence of events with timing information. It is able to recovery the possible delays introduced by AER bus. It has been implemented in real time hardware using VHDL and tested in a PCI-AER board, developed by authors, that currently capable to send and receive events at a peak rate of 16 Mev/sec, and a typical rate of 10 Mev/sec

A real-time wireless sensor network for wheelchair navigation

Today, the availability of inexpensive, low power hardware including CMOS cameras and wireless devices make it possible to deploy a wireless sensor network (WSN) with nodes equipped with cameras for a variety of applications. In this paper, we discuss the use of one of these WSNs as a navigation aid for wheelchairs. Instead of having complicated wheelchairs with lots of on-board sensors, we argue that a viable alternative is to have simpler wheelchairs that are able to interact with an intelligent environment so that the wheelchair bases its navigation on its software intelligence, supported by the information sent by external sensors. Many questions have to be investigated, for instance how sensors should be deployed or whether the wireless links would be able to meet our temporal requirements. We describe some of the solutions we adopted, particularly how to implement with Zigbee devices a polling mechanism that allows us to guarantee a real-time secure navigation.

SIRIUS: improving the maneuverability of powered wheelchairs

The indoor maneuverability of powered wheelchairs may be difficult or bothersome in several circumstances. In this paper, we describe an experimental powered wheelchair named SIRIUS, developed at the University of Seville, which introduces some simple but effective navigation aids. Special emphasis is placed on the implementation of recorded trajectory playback and in the shared control modes, i.e., the chairs guiding where both the user and the computer collaborate. Furthermore, SIRIUS is an open platform to essay another kinds of functional or navigational aids, because its hardware architecture is based on a commercial PC. This would permit many devices that are frequently needed by the chair driver to be integrated smoothly into the chair controller.

Analysis of channel utilization for controller area networks

In this paper, a model for the analysis of the CAN protocol is presented, extending the analysis already developed for fixed priority multiprocessors. Two cases are considered, which correspond to the main commercial devices. The model allows us to obtain some useful results for the design of CAN-based systems. The main conclusions are those regarding bus utilization, both total and per priority level. The results are validated using simulation. Finally, the real-time behavior is also briefly discussed.