Summary Power is becoming an increasingly important concern for large supercomputer centers. However, to date, there have been a dearth of studies of power usage ‘in the wild’—on production supercomputers running production workloads. In this paper, we present the initial results of a project to characterize the power usage of the three Top500 supercomputers at Los Alamos National Laboratory: Cielo, Roadrunner, and Luna (#15, #19, and #47, respectively, on the June 2012 Top500 list). Power measurements taken both at the switchboard level and within the compute racks are presented and discussed. Some noteworthy results of this study are that (1) variability in power consumption differs across architectures, even when running a similar workload and (2) Los Alamos National Laboratory's scientific workload draws, on average, only 70–75% of LINPACK power and only 40–55% of nameplate power, implying that power capping may enable a substantial reduction in power and cooling infrastructure while impacting comparatively few applications. Copyright © 2013 John Wiley & Sons, Ltd.

Sensemaking is described as the process of comprehension, finding meaning and gaining insight from information, producing new knowledge and informing further action. Understanding the sensemaking process allows building effective visual analytics tools to make sense of large and complex datasets. Currently, it is often a manual and time-consuming undertaking to comprehend this: researchers collect observation data, transcribe screen capture videos and think-aloud recordings, identify recurring patterns, and eventually abstract the sensemaking process into a general model. In this paper, we propose a general approach to facilitate such a qualitative analysis process, and introduce a prototype, SensePath, to demonstrate the application of this approach with a focus on browser-based online sensemaking. The approach is based on a study of a number of qualitative research sessions including observations of users performing sensemaking tasks and post hoc analyses to uncover their sensemaking processes. Based on the study results and a follow-up participatory design session with HCI researchers, we decided to focus on the transcription and coding stages of thematic analysis. SensePath automatically captures user's sensemaking actions, i.e., analytic provenance, and provides multi-linked views to support their further analysis. A number of other requirements elicited from the design session are also implemented in SensePath, such as easy integration with existing qualitative analysis workflow and non-intrusive for participants. The tool was used by an experienced HCI researcher to analyze two sensemaking sessions. The researcher found the tool intuitive and considerably reduced analysis time, allowing better understanding of the sensemaking process.

Interactive tabletops are an exiting new platform for supporting children's collaboration. With design guidelines and standardized interaction principles still immature, there is a considerable need for iterative prototyping to define the task and interface. Lo-fi prototypes---using cardboard, paper, etc.---are easy to develop, flexible to adjust during design sessions, and intuitive for users to manipulate. Using them can be a valuable step in designing tabletop applications.

Many authors have argued the need for abroader understanding of context and the situatedness of activity when approaching the evaluation of systems. However, prevailing practice often still tends t...

In recent years, there has been great interest in scenario-based design and other forms of user-centred design. However, there are many design processes that, often for good reason, remain technology-centred. We present a case study of introducing scenarios into two digital library development processes. This was found to disrupt established patterns of working and to bring together conflicting value systems. In particular, the human factors approach of identifying users and anticipating what they are likely to do with a system (and what problems they might encounter) did not sit well with a development culture in which the rapid generation and informal evaluation of possible solutions (that are technically feasible and compatible with stable system components) is the norm. We found that developers tended to think in terms of two kinds of user: one who was exploring the system with no particular goal in mind and one who knew as much as the developer; scenarios typically work with richer user descriptions that challenge that thinking. In addition, the development practice of breaking down the design problem into discrete functions to make it manageable does not fit well with a scenario-based approach to thinking about user behaviour and interactions. The compromise reached was scenario-informed design, whereby scenarios were generated to support reasoning about the use of selected functions within the system. These scenarios helped create productive common ground between perspectives.

One of the long-standing challenges in human-computer interaction has been the integration of usability evaluation methods within design practice. In the work reported here, the question of how to include user concerns within an unstructured, system-focused development process was investigated. The project looked into the use of Claims Analysis as a method for assessing the effects of design decisions on users' experience. Claims Analysis was found to be more difficult than expected to learn, to communicate to systems developers, and to apply effectively in practice. The work has highlighted a tension between user-centered and function-oriented design approaches and differences in values and perspectives between the human factors specialists and traditional developers involved in the study.

In this article we present a new approach to interaction modeling based on the concept of information resources. The approach is inspired by recent distributed cognition (DC) literature but develops a model that applies specifically to human-computer interaction (HCI) modeling. Of course, there are many approaches to modeling HCI, and the motivation of this article is not to offer yet another approach. Rather, our motivation is that the recent developments in DC are so obviously relevant to HCI modeling and design, yet the ideas have lacked visibility in the HCI community. By providing a model whose concepts are rooted in DC concepts, we hope to achieve this visibility. DC research identifies resources for action as central to the interaction between people and technologies, but it stops short of providing a definition of such resources at a level that could be used to analyze interaction. The resources model described in this article defines a limited number of resource types as abstract information structures that can be used to analyze interaction. We demonstrate how these abstract types can be represented differently in an interface. The resources model uses the concept of interaction strategy to describe the way in which different configurations of resources can differently shape users' actions. These 2 components of the resources model (information structures and interaction strategies), through the process of coordination and integration, provide a link among devices, representations, and actions that is not well articulated in the DC literature.

Abstract. There is considerable interest within the Human Computer Interaction (HCI) community in the use of media spaces to enhance awareness and interaction between workers in offices or other spatially distributed environments. In addition to the technical challenges of providing reliable and efficient audio-visual communication, there are important social questions, in particular how users are able to control access to their personal environments, and how to advise other users about their level of availability. Within AMODEUS-2 1 , an ESPRIT Basic Research Action concerned with the development, transfer and assessment of techniques for modelling human-computer interaction, a prototype media space has been analysed by various user and system oriented modelling techniques. This paper describes how formal specification can be used to express requirements on the interfaces needed to control access and availability in a media space. Beyond its obvious use in clarifying the subtle relationship between these concerns, the paper describes how the specification assists in assessing design options originating from other modelling disciplines.

In this article we present a method for evaluating and comparing design options for allocating communication media. The method pays particular attention to how such options support cooperation in an interactive safety-critical system. The comparison is performed using three sets of criteria based on task performance, analysis of user deviations and consequent hazards, and coordination. The explicit emphasis on hazards and communication issues, using actual tasks to guide the evaluation, ensures that designers attention is focused on the interactions where problems are likely to occur. We describe an application of the method to the design of access to new communication technology in an air traffic control environment.

We put forward an approach to deriving and applying human error tolerance requirements. Such requirements are concerned with the response of a system to errors introduced by human operators. The approach provides a means by which operators' tasks can be described and analysed for likely errors and the impact of these errors on system safety can be explored. The approach, based on previous work by the same authors (P. Wright et al., 1994), uses a software engineering notation to provide the bridge between operator models and systems engineering concerns. The approach is extended to include a more refined understanding of the processes that contribute to human error. The operators' process in achieving goals is understood in terms of structured tasks. With this additional apparatus we are able to capture a more complex set of human error forms.

The application of an interactive theorem-proving assistant and specification support tool called mural in the specification and verification of a small Vienna development method (VDM) development is described. It is the authors' intention to give a feel for how mural works and of mural's applicability as a tool in specifying and verifying software.>