Interaction Histories and Short-Term Memory: Enactive Development of Turn-Taking Behaviours in a Childlike Humanoid Robot

In this article, an enactive architecture is described that allows a humanoid robot to learn to compose simple actions into turn-taking behaviours while playing interaction games with a human partner. The robot’s action choices are reinforced by social feedback from the human in the form of visual attention and measures of behavioural synchronisation. We demonstrate that the system can acquire and switch between behaviours learned through interaction based on social feedback from the human partner. The role of reinforcement based on a short-term memory of the interaction was experimentally investigated. Results indicate that feedback based only on the immediate experience was insufficient to learn longer, more complex turn-taking behaviours. Therefore, some history of the interaction must be considered in the acquisition of turn-taking, which can be efficiently handled through the use of short-term memory.Peer reviewedFinal Published versio

A architecture for MHEG objects

Hypermedia applications are one of the most recent and most demanding computer uses. It is accepted that one of the main impediments to their widespread use is the lack of standards, and the lack of Open Systems with the possibility of having documents interchangeable between different hardware and software platforms. Several standards are emerging, one of which is the one being developed by the ISO/IEC WG12 known as the Multimedia and Hypermedia Information Coding Expert Group (MHEG). As desktop systems become more powerful, one of the main users of hypermedia applications is the home market. Therefore it is important to have standards and applications suitable for those platforms. This work reviews existing proposals for hypermedia architectures and interchange standards. It then assesses the suitability of the MHEG standard for use in open, distributed, and extensible hypermedia systems. An architecture for the implementa­tion of MHEG objects taking into account the limitations imposed by current desktop computers is also proposed. To assess the suitability of the proposed architecture, a prototype has been imple­mented. An analysis of the performance obtained in the prototype is presented and conclusions on the requirements for future implementations drawn. Finally, some suggestions to improve the MHEG standard are made

BCI2000Web and WebFM: Browser-Based Tools for Brain Computer Interfaces and Functional Brain Mapping

BCI2000 has been a popular platform for development of real-time brain computer interfaces (BCIs). Since BCI2000's initial release, web browsers have evolved considerably, enabling rapid development of internet-enabled applications and interactive visualizations. Linking the amplifier abstraction and signal processing native to BCI2000 with the host of technologies and ease of development afforded by modern web browsers could enable a new generation of browser-based BCIs and visualizations. We developed a server and filter module called BCI2000Web providing an HTTP connection capable of escalation into an RFC6455 WebSocket, which enables direct communication between a browser and a BCI2000 distribution in real-time, facilitating a number of novel applications. We also present a JavaScript module, bci2k.js, that allows web developers to create paradigms and visualizations using this interface in an easy-to-use and intuitive manner. To illustrate the utility of BCI2000Web, we demonstrate a browser-based implementation of a real-time electrocorticographic (ECoG) functional mapping suite called WebFM. We also explore how the unique characteristics of our browser-based framework make BCI2000Web an attractive tool for future BCI applications. BCI2000Web leverages the advances of BCI2000 to provide real-time browser-based interactions with human neurophysiological recordings, allowing for web-based BCIs and other applications, including real-time functional brain mapping. Both BCI2000 and WebFM are provided under open source licenses. Enabling a powerful BCI suite to communicate with today's most technologically progressive software empowers a new cohort of developers to engage with BCI technology, and could serve as a platform for internet-enabled BCIs

Effective memory management for mobile environments

Smartphones, tablets, and other mobile devices exhibit vastly different constraints compared to regular or classic computing environments like desktops, laptops, or servers. Mobile devices run dozens of so-called “apps” hosted by independent virtual machines (VM). All these VMs run concurrently and each VM deploys purely local heuristics to organize resources like memory, performance, and power. Such a design causes conflicts across all layers of the software stack, calling for the evaluation of VMs and the optimization techniques specific for mobile frameworks. In this dissertation, we study the design of managed runtime systems for mobile platforms. More specifically, we deepen the understanding of interactions between garbage collection (GC) and system layers. We develop tools to monitor the memory behavior of Android-based apps and to characterize GC performance, leading to the development of new techniques for memory management that address energy constraints, time performance, and responsiveness. We implement a GC-aware frequency scaling governor for Android devices. We also explore the tradeoffs of power and performance in vivo for a range of realistic GC variants, with established benchmarks and real applications running on Android virtual machines. We control for variation due to dynamic voltage and frequency scaling (DVFS), Just-in-time (JIT) compilation, and across established dimensions of heap memory size and concurrency. Finally, we provision GC as a global service that collects statistics from all running VMs and then makes an informed decision that optimizes across all them (and not just locally), and across all layers of the stack. Our evaluation illustrates the power of such a central coordination service and garbage collection mechanism in improving memory utilization, throughput, and adaptability to user activities. In fact, our techniques aim at a sweet spot, where total on-chip energy is reduced (20–30%) with minimal impact on throughput and responsiveness (5–10%). The simplicity and efficacy of our approach reaches well beyond the usual optimization techniques

The annotation of continuous media

In principle, the presentation of continuous media is time-dependent. Examples of con­tinuous media are audio, video and graphics animation. This work is on the support for the annotation of continuous media, or the integration of voice comments with continuous- media documents like music and video clips. This application has strict synchronisation requirements, both with respect to the media involved and to user interaction. The applica­tion involves functions such as storage, management, control of GUIs, and of continuous- medium devices. These are realised by components which can be distributed across a network. New models and architectures have been defined to enable open distributed processing of applications, that is, distributed processing independent of operating systems. Abstractions are provided, which facilitate the development of applications, and these execute supported by platforms that implement such open architectures. These architectures have been based on an object-based client/server model. Our work aims at exploring object-orientation, open distributed processing and some characteristics of continuous media, through the development and use of the proposed application. The application is designed as a set of objects with well-defined functions and which interact between themselves. A distinguishing feature of the application is that it involves reusable components and mechanisms. For example, a mechanism, which enables components to control logical clocks and synchronise them, is incorporated in the application in response to its synchronisation requirements. The implementation is based on ANSAware, a platform that supports open distributed processing and allows distributed objects to bind to each other, to interact with one another, and to exhibit concurrent activities. The performance of the implementation is examined with respect to the application’s response to user requests. Response times of operations such as play, pause, etc., are measured, and the final results are better than a defined maximum tolerance. An analysis of the development approach is made with respect to support for real-time activities in the application, and to software reuse in the model proposed. This thesis concludes by reviewing the suitability of the object-oriented approach for the development of distributed continuous media applications

An Architecture for distributed multimedia database systems

In the past few years considerable demand for user oriented multimedia information systems has developed. These systems must provide a rich set of functionality so that new, complex, and interesting applications can be addressed. This places considerable importance on the management of diverse data types including text, images, audio and video. These requirements generate the need for a new generation of distributed heterogeneous multimedia database systems. In this paper we identify a set of functional requirements for a multimedia server considering database management, object synchronization and integration, and multimedia query processing. A generalization of the requirements to a distributed system is presented, and some of our current research and developing activities are discussed

A Practical Comparison of Scheduling Algorithms for Mixed Criticality Embedded Systems

With the consolidation of automotive control processes onto single highperformance ECUs the issue of running, and thus scheduling, processes of varying criticality on a single CPU has moved to the fore. This has resulted in a number of new algorithms for scheduling such systems, for example Adaptive Mixed Criticality (AMC). This project attempts to measure the performance of some of these algorithms on a singlecore embedded system CPU and compares them in order to shed some light on their different advantages and disadvantages