15021995
Maintaining High-Bandwidth Under Dynamic Network Conditions
The need to distribute large files across multiple wide-area sites is becoming increasingly common, for instance, in support of scientific computing, configuring distributed systems, distributing software updates such as open source ISOs or Windows patches, or disseminating multimedia content. Recently a number of techniques have been proposed for simultaneously retrieving portions of a file from multiple remote sites with the twin goals of filling the client's pipe and overcoming any performance bottlenecks between the client and any individual server. While there are a number of interesting tradeoffs in locating appropriate download sites in the face of dynamically changing network conditions, to date there has been no systematic evaluation of the merits of different protocols. This paper explores the design space of file distribution protocols and conducts a detailed performance evaluation of a number of competing systems running in both controlled emulation environments and live across the Internet. Based on our experience with these systems under a variety of conditions, we propose, implement and evaluate Bullet' (Bullet prime), a mesh based high bandwidth data dissemination system that outperforms previous techniques under both static and dynamic conditions.
13037682
Gigabit routing on a software-exposed tiled-microprocessor
This paper investigates the suitability of emerging tiled-architectures, equipped with low-latency on-chip networks, for high-performance network routing. In this paper, we present the design, implementation and evaluation of a continuum of software-based routers on the MIT RAW microprocessor. The routers presented in this paper explore 1) several design choices for mapping the routing functions to the RAW tiles, 2) the role and behavior of RAW on-chip interconnects for transporting and switching packets, and 3) the placement of packet buffers and their interaction with the RAW on-chip networks. Our experiments evaluate the performance benefit of streaming on-chip networks for transporting packet payloads, effect of buffering on the linecards, and the cost of scal ing our design. Our software-based routers on RAW can achieve a throughput of 15Gb/sec - an order of magnitude improvement over previous software routers on traditional general-purpose architectures and at least four times faster than Intel's XP1200 Network Processor.
8794180
The generality/specificity of expertise in scientific reasoning
Previous research on scientific reasoning has shown that it involves a diverse set of skills. Yet, little is known about generality or domain specificity of those skills, an important issue in theories of expertise and in attempts to automate scientific reasoning skills. We present a study designed to test what kinds of skills psychologists actually use in designing and interpreting experiments and contrast expertise within a particular research area with general expertise at designing and interpreting experiments. The results suggest that psychologists use many domain-general skills in their experimentation and that bright and motivated Carnegie Mellon undergraduates are missing many of these skills. We believe that these results have important implications for psychological and artificial intelligence models of expertise, as well as educational implications in the domain of science instruction.
5342280
Intelligent gaze-added interfaces
We discuss a novel type of interface, the intelligent gaze-added interface, and describe the design and evaluation of a sample gaze-added operating-system interface. Gaze-added interfaces, like current gaze-based systems, allow users to execute commands using their eyes. However, while most gaze-based systems replace the functionality of other inputs with that of gaze, gaze-added interfaces simply add gaze functionality that the user can employ if and when desired. Intelligent gaze-added interfaces utilize a probabilistic algorithm and user model to interpret gaze focus and alleviate typical problems with eye-taking data. We extended a standard WIMP operating-system interface into a new interface, IGO, that incorporates intelligent gaze-added input. In a user study, we found that users quickly adapted to the new interface and utilized gaze effectively both alone and with other inputs.
37746133
The Transfer of Text-Editing Skill
Abstract Computer-naive subjects were taught to use either one or two line editors and then a screen editor. Positive transfer was observed both between the line editors and from the line editors to the screen editor. Transfer expressed itself in terms of reductions in total time, keystrokes, residual errors, and seconds per keystroke. A simple two-component model of transfer is proposed that allows for the differential practice of general and specific components when learning a skill.
29133778
Toward a real-time model-based training system
This article describes the development of a real-time model-based training system that provides adaptive ''over-the-shoulder'' (OTS) instructions to trainees as they learn to perform an Anti-Air Warfare Coordinator (AAWC) task. The long-term goal is to develop a system that will provide real-time instructional materials based on learners' actions, so that eventually the initial set of instructions on a task can be strengthened, complemented, or overridden at different stages of training. The training system is based on the ACT-R architecture, which serves as the theoretical background for the cognitive model that monitors the learning process of the trainee. An experiment was designed to study the impact of OTS instructions on learning. Results showed that while OTS instructions facilitated short-term learning, (a) they took time away from the processing of current information, (b) their effects tended to decay rapidly in initial stages of training, and (c) their effects on training diminished when the OTS instructions were proceduralized in later stages of training. A cognitive model that learned from both the upfront and OTS instructions was created and provided good fits to the learning and performance data collected from human participants. Our results suggest that to fully capture the symbiotic performance between humans and intelligent training systems, it is important to closely monitor the learning process of the trainee so that instructional interventions can be delivered effectively at different stages of training. We proposed that such a flexible system can be developed based on an adaptive cognitive model that provides real-time predictions on learning and performance.
46723192
On the role of metaphor and language in design of third party payments in eBanking: Usability and quality
This paper describes results of a usability study of contrasting user-interface designs for Internet Banking (eBanking). Two specific interface metaphors were compared in the first experiment, linear form filling and array editing interaction modes. Terminology in the interaction dialogue was compared in the second experiment, using typical banking language and a generic, plain language interface. This research aimed to perform usability evaluation and comparison of the alternative interface designs to illuminate the development of new eBanking services. This research involved sixty-one participants (Internet users and customers of the involved Bank) exploring the designs in controlled experiments involving hands-on experience. Banks are interested in ensuring their eBanking services are highly customer-centric and that the interface matches customer expectations in order to drive customers towards this lower cost channel. The results of the first experiment (N=32, where N indicates the number of participants in the cohort) concluded that the simple form-filling metaphor, taken from the traditional paper-based procedure, was generally more usable than a Spreadsheet metaphor. In the second experiment (N=29), it was found that although banking terminology was not completely understood across the cohort, the instructional language changes did not impact significantly on usability.