Joao Orvalho | Instituto Politécnico de Coimbra (original) (raw)

Papers by Joao Orvalho

A “interacao baseada no toque” por utilizadores cegos em dispositivos moveis depreende um esforco... more A “interacao baseada no toque” por utilizadores cegos em dispositivos moveis depreende um esforco cognitivo suplementar. Como objeto de analise, a partir de um conjunto de tarefas, o registo dos tempos e dos erros das praticas de interacao e as observacoes dos utilizadores foi possivel constatar a diferenca na interacao entre os sistemas operativos Android e iOS. Existem diferencas significativas entre estes dois sistemas, os resultados permitiram identificar qual a interface e as tecnicas de interacao mais acessiveis, assim como a obtencao de informacao relevante para a concecao de produtos que correspondam as necessidades destes utilizadores.

Lecture Notes in Computer Science, 2002

This book constitutes the refereed proceedings of the Joint International Workshops on Interactiv... more This book constitutes the refereed proceedings of the Joint International Workshops on Interactive Distributed Multimedia Systems and Protocols for Multimedia Systems, IDMS/PROMS 2002, held in Coimbra, Portugal in November 2002. The 30 revised full papers presented were carefully reviewed and selected from 112 submissions. The papers are organized in topical sections on performance of protocols and applications, mobile multimedia systems, standards and related issues, quality of service, video systems and ...

J. Orvalho

Tese de doutoramento em Engenharia Informática apresentada à Fac. de Ciências e Tecnologia da Uni... more Tese de doutoramento em Engenharia Informática apresentada à Fac. de Ciências e Tecnologia da Univ. de Coimbr

ci.uc.pt

Sumário As aplicações de conferência requerem um eficiente serviço de controlo de conferências. O... more Sumário As aplicações de conferência requerem um eficiente serviço de controlo de conferências. O presente artigo introduz as principais características de um serviço de controlo de conferências baseado no CORBA Event Service, usando a plataforma Java. O ...

Citeseer

Conference applications rely on groups of geographically dispersed linked nodes that are capable ... more Conference applications rely on groups of geographically dispersed linked nodes that are capable of exchanging audio-graphical and audio-visual information, through different types of communication networks. At present, conference applications play a key role in ...

niee.ufrgs.br

... sentido de se fazer um estudo sobre a aplicabilidade do b-learning no contexto de uma ... sim... more ... sentido de se fazer um estudo sobre a aplicabilidade do b-learning no contexto de uma ... simulações, webseminars, avaliação e ferramentas de comunicação (email ... comunidade, que se pretendia fazer emergir através da metodologia da aprendizagem colaborativa. ...

Advances in Computational Intelligence and Robotics, 2019

As reported by the World Health Organization, an estimated 253 million live with visual impairmen... more As reported by the World Health Organization, an estimated 253 million live with visual impairment that cannot be corrected with glasses or contact lenses. It's necessary to bring awareness and understanding of the challenges blind people face and help to motivate research into new technology to answer those questions. This chapter starts to identify the challenges people with visual disabilities face in their life. The problem of navigation and orientation as well as the different possibilities to deal with the locomotion situation is also addressed. It describes the traditional navigational solutions as well as other which involves more sophisticated technological devices and their multimodal interfaces. The chapter ends with the description of the BlueEyes project, consisting in a solution using beacons to help blind people moving in a city. The phases of the project are described, and the actual research situations is also slightly explained.

World Academy of Science, Engineering and Technology, International Journal of Industrial and Manufacturing Engineering, 2016

Advances in Business Information Systems and Analytics

The study presents an adaptation of the Mastermind game for blind users called MasterBlind. The g... more The study presents an adaptation of the Mastermind game for blind users called MasterBlind. The game mechanics were simplified and auditory feedback introduced. The research object was to understand what kind of sounds would work better to help blind people play the game. Three versions were presented to the subjects-pentatonic notes, animal sounds and vowels-to help users recall previous steps in the game. The main hypothesis predicted that blind users would consciously benefit from the auditory feedback provided. The second hypothesis predicted that users would benefit less from the feedback that doesn't provide semantic information-auditory icons versus earcons. The results were congruent with the hypothesis. MasterBlind can be a usable, enjoyable and a challenging experience for blind users as long as it provides semantically significant feedback. However, new developments are in progress to prove our ideas having in mind the inclusion of blind people.

Mobile IP is now the standard for supporting mobility in IP networks. It provides seamless mobili... more Mobile IP is now the standard for supporting mobility in IP networks. It provides seamless mobility by hiding the change of IP address when a mobile host moves between IP subnets. Nevertheless, Mobile IP is not designed to support fast handoff and seamless mobility in handoff-intensive environments. Several micro-mobility protocols have been proposed to support host mobility with frequent handoffs within a domain without interaction with the Mobile IP enabled internet. Cellular IP, HAWAII and HFA are some of the popular IP micro-mobility protocols. Cellular IP complements Mobile IP with support for fast, seamless and local handoff control, and IP paging. In this paper a modification to the existing indirect handoff mechanism in Cellular IP is proposed and subsequently assessed by simulation. The approach proposed in this paper, called Enhanced Indirect Handoff, constitutes a new way to handoff to the new base station where the handoff is initiated along the old base station, resulting in reduced handoff delay and hence reduced packet loss.

Proceedings IEEE INFOCOM 2006. 25TH IEEE International Conference on Computer Communications, 2006

In this paper we describe a Java middleware, the SENSACT API, which enables the construction - an... more In this paper we describe a Java middleware, the SENSACT API, which enables the construction - and connection through a Bluetooth network - of a network of sensors and actuators for the purpose of enabling its use in mobile pervasive augmented reality games. The system enables sensors and actuators to be deployed and subsequently connected to a central coordinating device,

Proceedings Third International Enterprise Distributed Object Computing. Conference (Cat. No.99EX366), 1999

The present paper proposes and evaluates some extensions to the CORBA Event Service, based on the... more The present paper proposes and evaluates some extensions to the CORBA Event Service, based on the use of the Lightweight Reliable Multicast Protocol (LRMP). These extensions address some limitations of the CORBA Event Service, namely multicasting, reliability and total ordering. The extensions were developed and tested in a prototype environment created for this purpose, and are transparent and fully compatible with the standard OMG Event Service, enabling the user to decide for the use of standard IIOP or IP multicasting.

2007 15th International Conference on Software, Telecommunications and Computer Networks, 2007

ABSTRACT Ubiquitous or pervasive computing is a new kind of computing, where specialized elements... more ABSTRACT Ubiquitous or pervasive computing is a new kind of computing, where specialized elements of hardware and software will have such high level of deployment that their use will be fully integrated with the environment. Augmented reality extends reality with virtual elements but tries to place the computer in a relatively unobtrusive, assistive role. In this paper we propose, test and analyse a security and privacy architecture for a previously proposed middleware architecture for mobile and pervasive large scale augmented reality games, which is the main contribution of this paper. The results show that the security features proposed in the scope of this work do not affect the overall performance of the system.

The 2007 International Conference on Next Generation Mobile Applications, Services and Technologies (NGMAST 2007), 2007

Ubiquitous or pervasive computing is a new kind of computing, where specialized elements of hardw... more Ubiquitous or pervasive computing is a new kind of computing, where specialized elements of hardware and software will have such a high level of deployment that their use will be fully integrated with the environment. Augmented reality extends reality with virtual elements but tries to place the computer in a relatively unobtrusive, assistive role. Specialized network middleware solutions for large scale mobile and pervasive augmented reality games are, to our knowledge, inexistent. The work presented in this paper focuses on the creation of such type of network middleware for mobile and pervasive entertainment, applied to the area of large scale augmented reality games. In this paper we propose and describe APIs and architecture for Quality of Service specification, negotiation and provision on the client side (using J2ME) and on the server side (using J2SE). The paper discusses architectural and implementation aspects.

Fifth Annual Conference on Communication Networks and Services Research (CNSR '07), 2007

IFIP International Federation for Information Processing

There has been a recent trend towards an all-IP network as it provides for costsavings together w... more There has been a recent trend towards an all-IP network as it provides for costsavings together with optimized network and ease of use. IP based networks are fully utilized, applications can share the same connection and QoS levels can still be guaranteed. But IP was designed for wired networks and wireless scenario was not envisioned. Owing to explosive growth of wireless users and growing demand of wireless services the internet body IETF has developed mobility management schemes to enhance IP in mobility scenarios for wireless subscribers. This trend has resulted in the development of Mobile IP to support node mobility. Mobile IP is only suitable for macro-mobility hence alternate protocols have been proposed in the literature to support seamless handoff in micro-mobile environments like cellular access networks where mobile nodes change their point of attachment frequently. Cellular IP is one of the popular solutions that support fast handoff with paging in a cellular access network. In this paper, we propose a Quality of Service model architecture based on IntServ for Cellular IP access network and describe the signaling mechanism RSVP integrated with the native protocol used to achieve the desired QoS.