Implementing a zooming User Interface: experience building Pad++

We are investigating a novel user interface paradigm based on zooming, in which users are presented with a zooming view of a huge planar information surface. We have developed a system called Pad++ to explore this approach. The implementation of Pad++ is related to real-time 3D graphics systems and to 2D windowing systems. However, the zooming nature of Pad++ requires new approaches to rendering, screen management, and spatial indexing. In this paper, we describe the design and implementation of the Pad++ engine, focusing in particular on rendering and data structure issues. Our goal is to present useful techniques that can be adopted in other real-time graphical systems, and also to discuss how 2D zooming systems differ from other graphical systems. © 1998 John Wiley & Sons, Ltd.     

Improving the controllability of tilt interaction for mobile map-based applications

This article proposes enhanced techniques for improving the controllability of tilt interaction. Tilt interaction offers an intuitive, one-handed form of interaction for mobile applications. Tilt interaction is particularly well-suited to mobile map-based applications, where traditional mobile interaction techniques suffer from several shortcomings. Current implementations of tilt interaction, however, suffer from several shortcomings. Existing zooming techniques used in conjunction with tilt interaction are often difficult to control. Tilt-controlled panning can also be difficult to control in a mobile context of use, where the user's walking motion affects the accuracy of tilt interaction. The use of rate-controlled tilt interaction to perform zooming is proposed. Two different approaches to sensitivity adaptation are investigated, where the sensitivity of tilt-controlled panning is automatically adjusted to compensate for the user's current context of use. A usability study was conducted with thirty participants to evaluate the proposed techniques. The results of the usability study showed that tilt zooming offered better efficiency, user satisfaction and perceived workload than gesture zooming. The use of a static dampening factor to compensate for walking motion was found to provide actual and perceived controllability improvements.     

The design, implementation, and performance evaluation of BERMUDA

We describe the design and implementation of BERMUDA, which is a loosely coupled system interfacing Prolog to the Britton-Lee Intelligent Database Machine (IDM-500). BERMUDA allows multiple concurrent Prolog processes, possibly running on different machines, to share a database. In addition, it preserves the semantics of Prolog programs and makes the use of the database system transparent to the user. We discuss several architectural issues faced by such systems and the approach adopted for each one in BERMUDA. We also present the performance results of a variety of experiments with the system. These include single-user benchmarks of BERMUDA against stand-alone Prolog and stand-alone IDM, detailed profiling of the costs of the modules of BERMUDA that shows the overhead imposed by the interface, and multiuser benchmarks of BERMUDA that show how the system behaves under heavier load. These experiments demonstrate the effectiveness of loosely coupled systems in general and of BERMUDA specifically. They also help in the identification of some aspects of the design and implementation of BERMUDA that could be improved     

The role of models@run.time in supporting on-the-fly interoperability

Models at runtime can be defined as abstract representations of a system, including its structure and behaviour, which exist in tandem with the given system during the actual execution time of that system. Furthermore, these models should be causally connected to the system being modelled, offering a reflective capability. Significant advances have been made in recent years in applying this concept, most notably in adaptive systems. In this paper we argue that a similar approach can also be used to support the dynamic generation of software artefacts at execution time. An important area where this is relevant is the generation of software mediators to tackle the crucial problem of interoperability in distributed systems. We refer to this approach as emergent middleware, representing a fundamentally new approach to resolving interoperability problems in the complex distributed systems of today. In this context, the runtime models are used to capture meta-information about the underlying networked systems that need to interoperate, including their interfaces and additional knowledge about their associated behaviour. This is supplemented by ontological information to enable semantic reasoning. This paper focuses on this novel use of models at runtime, examining in detail the nature of such runtime models coupled with consideration of the supportive algorithms and tools that extract this knowledge and use it to synthesise the appropriate emergent middleware.     

Formal models for user interface design artefacts

There are many different ways of building software applications and of tackling the problems of understanding the system to be built, designing that system and finally implementing the design. One approach is to use formal methods, which we can generalise as meaning we follow a process which uses some formal language to specify the behaviour of the intended system, techniques such as theorem proving or model-checking to ensure the specification is valid (i.e., meets the requirements and has been shown, perhaps by proof or other means of inspection, to have the properties the client requires of it) and a refinement process to transform the specification into an implementation. Conversely, the approach we take may be less structured and rely on informal techniques. The design stage may involve jotting down ideas on paper, brainstorming with users etc. We may use prototyping to transform these ideas into working software and get users to test the implementation to find problems. Formal methods have been shown to be beneficial in describing the functionality of systems, what we may call application logic, and underlying system behaviour. Informal techniques, however, have also been shown to be useful in the design of the user interface to systems. Given that both styles of development are beneficial to different parts of the system we would like to be able to use both approaches in one integrated software development process. Their differences, however, make this a challenging objective. In this paper we describe models and techniques which allow us to incorporate informal design artefacts into a formal software development process.     

Exploring Issues of User Model Transparency and Proactive Behaviour in an Office Environment Control System

It is important that systems that exhibit proactive behaviour do so in a way that does not surprise or frustrate the user. Consequently, it is desirable for such systems to be both personalised and designed in such a way as to enable the user to scrutinise her user model (part of which should hold the rules describing the behaviour of the system). This article describes on-going work to investigate the design of a prototype system that can learn a given user’s behaviour in an office environment in order to use the inferred rules to populate a user model and support appropriate proactive behaviour (e.g. turning on the user’s fan under appropriate conditions). We explore the tension between user control and proactive services and consider issues related to the design of appropriate transparency with a view to supporting user comprehensibility of system behaviour. To this end, our system enables the user to scrutinise and possibly over-ride the ‘IF-THEN’ rules held in her user model. The system infers these rules from the context history (effectively a data set generated using a variety of sensors) associated with the user by using a fuzzy-decision-tree-based algorithm that can provide a confidence level for each rule in the user model. The evolution of the system has been guided by feedback from a number of real-life users in a university department. A questionnaire study has yielded supplementary results concerning the extent to which the approach taken meets users’ expectations and requirements.     

Dialogue modelling of graphical user interfaces with a production system

In systems development it is essential for a piece of software to be able effectively to incorporate the requirements of the particular task domain that it is intended to address. This paper describes an approach that uses dialogue modelling to carry the requirements derived from task analysis through to the implementation phase of development. A notation based on production systems is used to develop an abstract specification of user and system behaviour which can subsequently be used as the basis for the implementation. The requirements for a computer-based tool are also discussed, with particular attention being given to ways in which the communication and reasoning about such a dialogue design can be supported.     

Input-to-State Stabilization of Linear Systems With Quantized State Measurements

We consider the problem of achieving input-to-state stability (ISS) with respect to external disturbances for control systems with linear dynamics and quantized state measurements. Quantizers considered in this paper take finitely many values and have an adjustable "zoom" parameter. Building on an approach applied previously to systems with no disturbances, we develop a control methodology that counteracts an unknown disturbance by switching repeatedly between "zooming out" and "zooming in." Two specific control strategies that yield ISS are presented. The first one is implemented in continuous time and analyzed with the help of a Lyapunov function, similarly to earlier work. The second strategy incorporates time sampling, and its analysis is novel in that it is completely trajectory-based and utilizes a cascade structure of the closed-loop hybrid system. We discover that in the presence of disturbances, time-sampling implementation requires an additional modification which has not been considered in previous work     

Personalising live zooming using the ePlayer

An innovative Internet streaming video player, called ePlayer, oriented to live events, has been researched, developed and evaluated. ePlayer supports a personalised zoomable user interface which enables a new user view experience. The main novelty of the system is first that it is designed to optimise the zoomed video quality when viewing life events, via adaptation of the streamed video quality, across multi-video streams with a variable network quality of service. Second, it also personalises the live video zooming with respect to users’ zooming preferences, easing the user interaction needed for the zooming task. The experimental results indicate that the system is not only able to zoom effectively, but that it can also maintain the visual quality of the video at the same time. The ePlayer is also able to infer a user’s zooming preferences via dynamically clustering a user’s zooming regions of interest when viewing live sports video content.     

Integrating best effort and fixed priority scheduling

Adaptive and dynamic behaviour is seen as one of the key characteristics of next generation hard real-time systems. Whilst fixed priority pre-emptive scheduling is becoming a de facto standard in real-time system implementation, it remains inflexible in its purest form. One approach to countering this criticism is to allow optional components, not guaranteed offline, to be executed at run-time. Optional components may be guaranteed a minimum set of resources at run-time, with competing resource requests scheduled according to the best-effort approach. This allows increased dynamic behaviour and improves the utility of the system. In this paper, we discuss this integration of fixed priority and best-effort scheduling.     

Design and implementation of a video browsing system for the Internet

Recent advances in multimedia processing technologies, internet‐working technologies, and the World Wide Web phenomenon have resulted in a vast creation and use of digital videos. Due to this reason, an efficient technique to locate and retrieve a desired video from a remote video archive is needed. A trial‐and‐error approach popularly used in current Web search engines is not applicable for searching for a desired video segment since the technique incurs intolerable delays. In this paper, we present the design and implementation of a video browsing system that lets the user view a summary of a selected video and search within the video while being downloaded so that the user can determine the relevance of the video as early as possible. The system is inexpensive and scalable, making it suitable for large‐scale distributed systems such as the Internet. The browsing system consists of two major software components: a video server, and a video browser and player called VideoCenter implemented using Microsoft DirectShow multimedia development kit. The implementation of VideoCenter enables us to assess the ease of use of DirectShow as well as its drawbacks in developing multimedia applications. Copyright © 2001 John Wiley & Sons, Ltd.     

Data-driven models for timing feedback responses in a Map Task dialogue system

Traditional dialogue systems use a fixed silence threshold to detect the end of users’ turns. Such a simplistic model can result in system behaviour that is both interruptive and unresponsive, which in turn affects user experience. Various studies have observed that human interlocutors take cues from speaker behaviour, such as prosody, syntax, and gestures, to coordinate smooth exchange of speaking turns. However, little effort has been made towards implementing these models in dialogue systems and verifying how well they model the turn-taking behaviour in human–computer interactions. We present a data-driven approach to building models for online detection of suitable feedback response locations in the user's speech. We first collected human–computer interaction data using a spoken dialogue system that can perform the Map Task with users (albeit using a trick). On this data, we trained various models that use automatically extractable prosodic, contextual and lexico-syntactic features for detecting response locations. Next, we implemented a trained model in the same dialogue system and evaluated it in interactions with users. The subjective and objective measures from the user evaluation confirm that a model trained on speaker behavioural cues offers both smoother turn-transitions and more responsive system behaviour.     

Local-network database

The architecture of the Microbe distributed database management system is described, with particular emphasis on the distributed execution of user requests controlled in a fully decentralized manner by a distributed execution monitor (SER). The monitor is based on the results of a dynamic and decentralized query decomposition algorithm known as Dopage. Microbe is now being implemented on a local broadcasting network of LSI-11 machines developed at Laboratoire IMAG for scientific and administrative applications. It was designed to be used for research in the distributed data processing field particularly concerning the implementation of the ISO open systems interconnection model levels 5 and 7 (session and application layers) for a loosely coupled distributed database system.     

基于X—WINDOW的用户接口生成和管理系统X—UIGMS

本文介绍了一种建立在UNIX系统X—WINDOW环境上的通用图形式用户接口生成和管理系统X—UIGMS,描述了它的原理,实现方法,功能和特点。该系统可用于各种复杂的应用系统,可以让用户选择理想的用户接口和交互方式,所设计的用户接口可以具有丰富的多层次的提示和出错检测恢复功能,可以满足各种类型的用户需要。     

基于Petri网的动态访问控制模型

访问控制是保障信息系统安全的一种主要机制,通过限定主体对客体的访问权限,确保对信息资源访问的合法性,达到保证信息的机密性、完整性和可用性的目的。通常,这种机制主要通过静态的访问控制矩阵实现,不随信息系统处理的任务变换而调整。利用Petri网的基本原理,提出了一种适合于信息系统的访问控制模型,随着信息系统的状态变化动态授予访问控制权限,实现对信息系统资源安全的动态保护。     

Stability analysis and non-linear behaviour of structural systems using the complex non-linear modal analysis (CNLMA)

Herein, a novel non-linear procedure for producing non-linear behaviour and stable limit cycle amplitudes of non-linear systems subjected to super-critical Hopf bifurcation point is presented. This approach, called Complex Non-Linear Modal Analysis (CNLMA), makes use of the non-linear unstable mode which governs the non-linear dynamic of structural systems in unstable areas. In this study, the computational methodology of CNLMA is presented for the systematic estimation of the non-linear behavior of structural system, and it is applied to a complex system with quadratic and cubic non-linearities. Results from this non-linear method are compared with results obtained by integrating the full original non-linear system. This procedure appears very interesting in regard to computational time, formulation, and also necessitates very few computer resources. Thus the CNLMA is suited to computational implementation for various complex non-linear system with many degrees-of-freedom.     

IDECAP Interactive Pictorial Information System for Demographic and Environmental Planning Applications

IDECAP is a database type information system. It is different from regular database systems as the information is mainly presented via thematic maps displayed on a graphics screen. Retrieval of information is usually achieved by means of graphical interaction with these images. The system utilizes interaction techniques and systems software from interactive computer graphics, using vector graphic and colour raster graphic stations for output. The present databank contains data based on grids and polygonal data. The system is being applied, but not restricted, to the Dutch 1971 Census data and the 1978 land use data. It allows the mapping of grid variables against a topographic background. Areas of interest can be investigated in detail by zooming in on a window drawn on the graphics screen by the user. Maps can be adjusted by user-definable class distributions shown in the form of histograms with standard deviations.     

A model of reaction for planning in dynamic environments

One shortcoming with most AI planning systems has been an inability to deal with execution-time discrepancies between actual and expected situations. Often, these exception situations jeopardize the immediate integrity and safety of the planning agent or its surroundings, with the only recourse being more time-consuming plan generation. In order to avoid such situations, potential exceptions must be predicted during plan execution. Since many application domains (particularly for autonomous systems) are inherently dynamic — in the sense that information is at best incomplete, perhaps erroneous, and changes over time independent of a planning agent's actions — managing action in the world becomes a difficult problem. Action and events in dynamic worlds must be monitored in order to coordinate an agent's actions with its surroundings. This allows the agent to predict and plan for potential future exception situations while acting in the present.This paper introduces an approach to autonomous reaction in dynamic environments. We have avoided the traditional distinction between generating and then executing plans through the use of a dynamic reaction system, which handles potential exception situations gracefully as it carries out assigned tasks. The reaction system manages constraints imposed by ongoing activity in the world, as well as those derived from long-term planning, to control observable behaviour. This approach provides the necessary stimulus/response behaviour required in dynamic situations, while using goal-directed constraints as heuristics for improved reactions.We present an overview of the salient features of dynamic worlds and their impact on traditional planning, introduce our model of dynamic reactivity, describe an implementation of the model and its performance in a dynamic simulation environment, and present an architecture incorporating long-term planning with short-term reactance suitable for autonomous systems applications.     

Model-Driven Interactive System Design for Therapy Robots

Physiotherapy using intelligent robots is emerging as a new approach to recovery for many stroke patients. Although therapy robots have a strong potential in dealing with therapeutic and other medical applications, they have not been fully utilized in everyday therapy activities due to concerns over safety and the lack of friendly robot user/patient interaction models. From the viewpoint of software engineering, a user-centred design based on UML (Unified Modelling Language) has been known to be one of the best solutions to satisfy usability since the design process relies heavily on the analysis of users and their tasks to reach their goals. Therefore, a model-driven approach to interactive system design via UML for therapy robots is needed to make them usable in the real world. This paper proposes such approach and introduces a new graphical notation that describes user interface elements and the methods of connection with hardware/software objects. With the proposed abstract interaction models, prototyping interactive systems can be made faster and allows for their evaluation by users and system developers before implementation in order to improve usability from the perspectives of users and system developers.