47143488
The Evaluation of User Interface Notations
Over the last decade a wide range of graphical, tabular and textual notations have been proposed to support the design of human-computer interfaces. These notations are intended to strip away the clutter of implementation details that frequently obscure interaction properties. Unfortunately, relatively little work has been done to evaluate the usability of these notations for ‘real-world’ interfaces. We have, therefore, conducted an empirical evaluation of the User Action Notation (UAN), State Transition Networks (STN) and temporal logic ‘in the wild’. By this we mean that our subjects were drawn from realistic samples of users and designers. We also presented our subjects with realistic descriptions of two user interfaces. This avoids a weakness of previous investigations that have used ‘toy examples’. The results of our investigation show a strong preference amongst our subjects for the use of natural language descriptions. More surprisingly, our results also suggest a link between the frequency of comprehension errors and positive attitude statements towards particular notations. In other words, our subjects made most errors with the notations that they liked the best. This suggests that while graphical notations, such as state transition networks, have a strong intuitive appeal they may also create significant problems for real-world development tasks.
39389167
Software Support for Incident Reporting Systems in Safety-Critical Applications
Incident reporting systems are playing an increasingly important role in the development and maintenance of safety-critical applications. The perceived success of the FAA's Aviation Safety Reporting System (ASRS) and the FDA's MedWatch has led to the establishment of similar national and international schemes. These enable individuals and groups to report their safety concerns in a confidential or anonymous manner. Unfortunately, many of these systems are becoming victims of their own success. The ASRS and MedWatch have both now received over 500,000 submissions. In the past, these systems have relied upon conventional database technology to support the indexing and retrieval of individual reports. However, there are several reasons why this technology is inadequate for many large-scale reporting schemes. In particular, the problems of query formation often result in poor precision and recall. This, in turn, has profound implications for safety-critical applications. Users may fail to identify similar incidents within national or international collections. This paper, therefore, shows how several alternative software architectures support incident report systems in safety-critical applications.
5064563
Using "Accident Fault Trees" in Conjunction With Traditional Accident Reports
Accident reports help to ensure that operator ‘error’ and system ’failure’ do not threaten other applications. Unfortunately, a number of usability problems limit the effectiveness of these documents. Each section is, typically, drafted by a different expert; forensic scientists follow metallurgists, human factors experts follow meteorologists. In consequence, it can be difficult for readers to form a coherent account of an accident. This paper argues that fault trees can be used to present a clear and concise overview of major failures. Unfortunately, fault trees have a number of limitations. For instance, they do not represent time. This is significant because temporal properties have a profound impact upon the course of human-machine interaction. Similarly, they do not represent the criticality or severity of a failure. We have, therefore, extended the fault tree notation to represent human-machine interaction during major failures. The resulting Accident Fault Tree diagrams can be used in conjunction with an official accident report to better visualise the course of an accident. The Clapham Junction railway disaster (Department of Transport, 1989) is used to illustrate our argument.
14968728
Using Temporal Logic to Support the Specification and Prototyping of Interactive Control Systems
Abstract Accidents at Flixborough, Seveso, Bhopal, Three Mile Island, Windscale and Chernobyl have led to increasing concern over the safety and reliability of control systems. Human factors specialists have responded to this concern and have proposed a number of techniques which support the operator of such applications. Unfortunately, this work has not been accompanied by the provision of adequate tools which might enable a designer to carry it beyond the “laboratory bench” and on to the “shop floor”. The following paper exploits formal, mathematically based specification techniques to provide such a tool. Previous weaknesses of abstract specifications are identified and resolved. In particular, they have failed to capture the temporal properties which human factors specialists identify as crucial to the success or failure of interactive control systems. They also provide the non-formalist with an extremely poor impression of what it would be to like to interact with potential implementations. Temporal logic avoids these deficiencies. It can make explicit the sequential information which may be implicit within a design. Executable subsets of this formalization support prototyping and this provides a means of assessing the qualitative “look and feel” of potential implementations. A variety of presentation strategies, including structural decomposition and dialogue cycles, have been specified and incorporated directly into prototypes using temporal logic. Prelog, a tool for the Presentation and REndering of LOGic specifications, has been developed and its implementation is described.
37787829
The epistemics of accidents
Human intervention has played a critical role in the causes of many major accidents. At Three Mile Island, the operators isolated a reactor from its heat sink. The pilots of the Boeing 737 at Kegworth managed to shut down their one functioning engine. Staff continued to allow trains to deposit passengers in Kings? Cross after the fire had started. In retrospect, it seems impossible to predict all of the ways that human intervention might threaten safety. It is, therefore, important that we learn as much as possible from those accidents that do occur. This task is complicated because conventional accident reports contain many hundreds of pages of prose. They present findings drawn from many different disciplines: metallurgy; systems engineering; human factors; meterology. These findings are, typically, separated into a number of distinct chapters. Each section focuses upon a different aspect of the accident. This makes it difficult for designers to recognize the ways in which operator intervention and system failure combine during major failures. The following pages use formal methods to address these concerns. It is argued that mathematical specification techniques can represent human factors and system failures. Unfortunately, formal methods have not previously been used to analyse the factors that motivate operator intervention. This paper, therefore, argues that epistemic extensions of mathematical notations must be recruited in order to support the formal analysis of major accidents.
8317114
Decision theory and safety-critical interfaces
Risk assessment techniques are being used to support the engineering of complex, safety-critical systems. They help to identify those situations that pose the greatest threat to an application. They can also be used to inform interface development. For example, operators must be presented with additional contextual information during infrequent, high-cost failures. Many risk assessment techniques cannot represent the temporal properties that affect usability. Few techniques provide means of reasoning about user input or output. This paper presents means of overcoming these limitations. It is argued that temporal logic can be used to represent sequential and concurrent properties of interaction. The same notation can also be used to specify presentation requirements. Temporal logic does not, however, provide means of representing risk. Decision theory is recruited to introduce probability and cost into the notation. The logic is then applied to reason about the different effects that low frequency, high cost failures have upon a user interface. A limitation of this approach is that the extended logic provides little impression of what it would be like to interact with a stochastic application. Simulation tools have been developed to avoid this limitation.
16043224
Journeys in non-classical computation II: initial journeys and waypoints
†University of York, Heslington, York YO1 5DD, UK‡University of the West of England, Frenchay Campus, Coldharbourlane, Bristol BS16 1QY, UK{University of Portsmouth, Buckingham Building, Lion Terrace, Portsmouth PO1 3WE, UK§University of Kent, Canterbury, Kent CT2 7NZ, UKkUniversity of Cambridge, Madingley Road, Cambridge CB3 OHE, UK#University of Exeter, North Cote House, The Queen’s Drive, Exeter E4 4QJ, UK
15670
Display of vector fields using a reaction-diffusion model
Effective visualization of vector fields relies on the ability to control the size and density of the underlying mapping to visual cues used to represent the field. In this paper we introduce the use of a reaction-diffusion model, already well known for its ability to form irregular spatio-temporal patters, to control the size, density, and placement of the vector field representation. We demonstrate that it is possible to encode vector field information (orientation and magnitude) into the parameters governing a reaction-diffusion model to form a spot pattern with the correct orientation, size, and density, creating an effective visualization. To encode direction we texture the spots using a light to dark fading texture. We also show that it is possible to use the reaction-diffusion model to visualize an additional scalar value, such as the uncertainty in the orientation of the vector field. An additional benefit of the reaction-diffusion visualization technique arises from its automatic density distribution. This benefit suggests using the technique to augment other vector visualization techniques. We demonstrate this utility by augmenting a LIC visualization with a reaction-diffusion visualization. Finally, the reaction-diffusion visualization method provides a technique that can be used for streamline and glyph placement.
18085576
Semantic errors - diagnosis and repair
In compiler technology, semantic error handling has too often used ad hoc techniques and terse messages of fixed content. In contrast, we present general models of diagnosis and repair of semantic errors and illustrate their use in the York Ada Workbench Compiler. The diagnostic model focuses upon the problem of selecting suitable information from which the programmer can locate and correct an error; following a brief discussion of an approach in which <underline>filters</underline> are applied to reports, and we give a more extensive account of a new approach using an <underline>interactive diagnostic interpreter</underline>. The repair model is based upon the idea of <underline>plastic</underline> nodes which are introduced into the compiler's internal representation of a program to replace <underline>normal</underline> nodes which are missing or erroneous.
12725153
Computational Engineering and Science Program at the University of Utah
The grand computational challenges in engineering and science require for their resolution a new scientific approach. As one report points out, “The use of modern computers in scientific and engineering research and development over the last three decades has led to the inescapable conclusion that a third branch of scientific methodology has been created. It is now widely acknowledged that, along with traditional experimental and theoretical methodologies, advanced work in all areas of science and technology has come to rely critically on the computational approach.” This methodology represents a new intellectual paradigm for scientific exploration and visualization of scientific phenomena. It permits a new approach to the solution of problems that were previously inaccessible.
2382274
Synthesising Timbres and Timbre-Changes from Adjectives/Adverbs
Synthesising timbres and changes to timbres from natural language descriptions is an interesting challenge for computer music. This paper describes the current state of an ongoing project which takes a machine learning approach to this problem. We discuss the challenges that are presented by this, discuss various strategies for tackling this problem, and explain some experimental work. In particular our approach is focused on the creation of a system that uses an analysis-synthesis cycle to learn and then produce such timbre changes.