Heuristic usability evaluation on games: a modular approach

Heuristic evaluation is the preferred method to assess usability in games when experts conduct this evaluation. Many heuristics guidelines have been proposed attending to specificities of games but they only focus on specific subsets of games or platforms. In fact, to date the most used guideline to evaluate games usability is still Nielsen’s proposal, which is focused on generic software. As a result, most evaluations do not cover important aspects in games such as mobility, multiplayer interactions, enjoyability and playability, etc. To promote the usage of new heuristics adapted to different game and platform aspects we propose a modular approach based on the classification of existing game heuristics using metadata and a tool, MUSE (Meta-heUristics uSability Evaluation tool) for games, which allows a rebuild of heuristic guidelines based on metadata selection in order to obtain a customized list for every real evaluation case. The usage of these new rebuilt heuristic guidelines allows an explicit attendance to a wide range of usability aspects in games and a better detection of usability issues. We preliminarily evaluate MUSE with an analysis of two different games, using both the Nielsen’s heuristics and the customized heuristic lists generated by our tool.Unión Europea PI055-15/E0

Academic methods for usability evaluation of serious games: a systematic review

In the last years, there has been an increasing interest in the design of video games as a tool for education, training, health promotion, socialization, etc. Usability, which is a key factor in any video game, becomes even more important in these so-called Bserious games^, where the users’ special characteristics should be considered, and the game efficacy depends on the users’ adherence and engagement. However, evaluation of the usability of this kind of games requires a redefinition of techniques, methods and even terminology. In this paper, we elicit six research questions and conduct a systematic review of the scientific literature, which resulted in the selection of 187 papers that contained the most relevant responses. The conclusions of this systematic review illustrate the general status of current academic usability evaluations of these games and the main trends in the selection of methodologies and how are they applied. This view may be a very valuable foundation for future researchMinisterio de Ciencia e Innovación PROCUR@-IPT-2011-1038-90000

An experimental evaluation of server performance in Networked Virtual Environments

Several works in the literature have recently addressed the study of different Networked Virtual Environments (NVE) due to their increasing popularity and widespread use in fields ranging from entertainment to e-Health. Open Wonderland is one of these NVEs which has been the subject of several studies mainly focused on the client side. This paper aims to cover the server-side performance issues to provide complementary results that can be useful for properly sizing Open Wonderland systems according to the number of expected users. An experimental testbed is used, which provides real data that shows that CPU and outgoing bandwidth are the most critical parameters when the number of clients increase.Ministerio de Ciencia e Innovación PROCUR@-IPT-2011-1038-900000Ministerio de Ciencia e Innovación TEC2009-10639-C04-0

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.Ministerio de Educación y Ciencia TIN2006-15617-C[01,02,03

A Dynamic Equilibrium View of Caching Systems

In this paper, we present a simple analytical study of caching systems based on the idea of dynamic equilibrium of cache blocks, assuming the Independent Reference Model (IRM) of references. This method allows us to obtain simple closedform expressions for parameters that are usually excluded from cache studies, such as the mean number of reads or writes per cache block while in the cache. We finally present some simulation results in order to validate the analysis.Ministerio de Educación y Ciencia TIN2006-15617- C03-03Junta de Andalucía P06-TIC-229

An analytical model of inter-channel interference in Bluetooth-based systems

One of the main advantages of the Bluetooth standard is that it provides a way to support ad-hoc connectivity between a variable number of devices at low cost. However, in situations with many Bluetooth devices that coexist in the same area the problem of channel interference may become of high importance. In this paper, we present an analysis that provides some expressions for the channel throughput and the delay that packets suffer due to possible collisions with other Bluetooth devices. The model includes the different effects of new and retransmitted packets. Both synchronized and unsynchronized systems are considered. Furthermore, although the effect of propagation losses are not explicitly considered, we show how they could be included in our model.Ministerio de Ciencia y Tecnología TIC2001-1868-C03-02Ministerio de Ciencia y Tecnología TIC2000-0087-P4-0

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.Ministerio de Educación y Ciencia TIN2006-15617- C03-03Junta de Andalucía P06-TIC-229

Inter-spike-intervals analysis of AER Poisson-like generator hardware

Address–Event–Representation (AER) is a communication protocol for transferring images between chips, originally developed for bio-inspired image-processing systems. Such systems may consist of a complicated hierarchical structure with many chips that transmit images among them in real time, while performing some processing (for example, convolutions). In developing AER-based systems it is very convenient to have available some means of generating AER streams from on-computer stored images. Rank order coding (ROC) and Poisson rate coding are the extremes of spikes coding. In this paper, we present a pseudo-random hardware method for generating AER streams in real time from a sequence of images stored in a computer’s memory. The Kolmogorov–Smirnov test has been applied to quantify that this method follows a Poisson distribution of the spikes. A USB–AER board, developed by our RTCAR group, have been used for the measurements. An example scenario of use under the EU CAVIAR project is presented.European Commission IST-2001-34124Ministerio de Ciencia y Tecnología TIC-2003-08164-C03-0

Poisson AER generator: Inter-Spike-Intervals Analysis

Address-event-representation (AER) is a communication protocol for transferring asynchronous events between VLSI chips, originally developed for bio-inspired processing systems (for example, image processing). Such systems may consist of a complicated hierarchical structure with many chips that transmit data among them in real time, while performing some processing (for example, convolutions). To develop AER based systems for image processing it is very convenient to have available some kind of tool for generating AER streams from on-computer stored images. In this paper we present a hardware method for generating AER streams with Poisson statistics in real time from a sequence of images stored in a computer's memory. We quantify that the events generated follow a Poisson distribution using the Kolmogorov-Smirnov test. We have developed a USB-AER board, based on the Xilinx Spartan II FPGA and the Cygnal 8051 microcontroller, developed by our RTCAR group have been used for the analysisEuropean Commission IST-2001-34124Ministerio de Ciencia y Tecnología TIC-2003-08164-C03-0

Time-Recovering PCI-AER interface for Bio-inspired Spiking Systems

Address Event Representation (AER) is an emergent neuromorphic interchip communication protocol that allows for real-time virtual massive connectivity between huge number neurons located on different chips. By exploiting high speed digital communication circuits (with nano-seconds timings), synaptic neural connections can be time multiplexed, while neural activity signals (with mili-seconds timings) are sampled at low frequencies. Also, neurons generate ‘events’ according to their activity levels. More active neurons generate more events per unit time, and access the interchip communication channel more frequently, while neurons with low activity consume less communication bandwidth. 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 into the computer and visualize it on screen, and (b) inject a sequence of events at some point of the AER structure. This is necessary for testing and debugging complex AER systems. This paper presents a PCI to AER interface, that dispatches a sequence of events received from the PCI bus with embedded timing information to establish when each event will be delivered. A set of specialized states machines has been introduced to recovery the possible time delays introduced by the asynchronous AER bus. On the input channel, the interface capture events assigning a timestamp and delivers them through the PCI bus to MATLAB applications. It has been implemented in real time hardware using VHDL and it has been tested in a PCI-AER board, developed by authors, that includes a Spartan II 200 FPGA. The demonstration hardware is currently capable to send and receive events at a peak rate of 8,3 Mev/sec, and a typical rate of 1 Mev/sec.European Commission IST-2001-34124Ministerio de Educación y Ciencia TIC-2000-0406-P