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Communications of the ACM

101 - 110 of 167 for bentley

Evolving visually guided agents in an ambiguous virtual world

The fundamental challenge faced by any visual system within natural environments is the ambiguity caused by the fact that light that falls on the system's sensors conflates multiple attributes of the physical world. Understanding the computational principles by which natural systems overcome this challenge and generate useful behaviour remains the key objective in neuroscience and machine vision research. In this paper we introduce Mosaic World, an artificial life model that maintains the essential characteristics of natural visual ecologies, and which is populated by virtual agents that - through 'natural' selection - come to resolve stimulus ambiguity by adapting the functional structure of their visual networks according to the statistical structure of their ecological experience. Mosaic World therefore presents us with an important tool for exploring the computational principles by which vision can overcome stimulus ambiguity and usefully guide behaviour.


Implicit java array bounds checking on 64-bit architecture

Interest in using Java for high-performance parallel computing has increased in recent years. One obstacle that has inhibited Java from widespread acceptance in the scientific community is the language requirement that all array accesses must be checked to ensure they are within bounds. In practice, array bounds checking in scientific applications may increase execution time by more than a factor of 2. Previous research has explored optimizations to statically eliminate bounds checks, but the dynamic nature of many scientific codes makes this difficult or impossible.Our approach is instead to create a new Java implementation that does not generate explicit bounds checks. It instead places arrays inside of Index Confinement Regions (ICRs), which are large, isolated, mostly unmapped virtual memory regions. Any array reference outside of its bounds will cause a protection violation; this provides implicit bounds checking. Our results show that our new Java implementation reduces the overhead of bounds checking from an average of 63% to an average of 9% on our benchmarks.


Verification: what works and what doesn't

Today's leading chip and system companies are faced with ever increasing design verification challenges; industry studies reveal that as much as 50% of the total schedule is being spent in verification. Large companies, with almost infinite resources, have shown that throwing CPU cycles and people at the simulation problem still doesn't guarantee a level of coverage desired by the design team.


Marketing computer support services through relationship and training strategies

In 2002, Harvard University's Division of Continuing Education (DCE) expanded its computer lab facility. This expansion allowed DCE to change its previous policy of restricting computer services to a small percentage of students to its current policy of extending these services to all DCE students.This flexibility enabled DCE's Institute for English Language (IEL) to change its previous position of assuming that all students did not have access to computer technology to its new position of assuming all students have access to computer technology. This new position has expanded the way IEL courses can be taught and managed. Church Street Staff initiated the building of relationships with IEL instructors to empower them with the skills and knowledge to infuse more technology into their courses.Church Street Staff organized and hosted a colloquium for IEL instructors in which they showcased services focused on a Harvard-developed instructional development Instructor's Toolkit. Main contacts for future support constituted the colloquium organization team. Team members conducted various parts of the colloquium to begin the process of building relationships with the instructors.The lab staff arranged bi-monthly follow-up training in the Instructor's Toolkit to a targeted cohort of IEL instructors. These instructors would then serve as peer mentors to their colleagues. The bi-monthly training culminated in a launch week in which the lab staff focused their attention on one-on-one help for the IEL instructors to launch their course websites.The success of the campaign was determined by the percentage of full-time instructors using email, website, bulletin board, and announcement tool as management and pedagogical tools complementing the classroom instruction.


Outils de modélisation des tâches utilisateurs: exigences du point de vue utilisation

User task analysis is a critical step in the a design process of interactive systems. The large set of user task models available today may lead to assume that this step is well supported. However, these models are little or not tool-supported. This paper focuses on user requirements the user task analysis tools. These requirements are organized into three categories: description support, model data use and model data utilities. Each category is illustrated by examples coming from available tools: IMAD, Euterpe, CTTE and Tamot.


Pragmatic solutions for better integration of the visually impaired in virtual communities

This article introduces and discusses issues in the design of user interfaces for visually impaired people in the domain of virtual communities. We begin by pointing out that collaborative virtual environments provide additional means for visually impaired people which may help to accomplish a better integration into existing communities and social activities. We give a short introduction to the way visually impaired people usually work with a PC and show how their method of information access differs to sighted people. We then take a look at the advantages and disadvantages of existing adaptations to operating systems. Based on this analysis we describe some requirements for user interfaces the usability for visually impaired people without losing the attractiveness and intuitiveness for the sighted. We finally describe a prototype of a special IRC-Client, called BIRC, and discuss its advantages and limitations.


Getting some perspective: using process descriptions to index document history

Process descriptions are used in workflow and related systems to describe the flow of work and organisational responsibility in business processes, and to aid in coordination. However, the division of a working process into a sequence of steps provides only a partial view of the work involved. In many cases, the performance of individual tasks in a larger process may depend on interpretations and understandings of how other aspects of the work were conducted.We present an example from an ethnographic investigation of one particular organisation, and introduce a mechanism, which we call “Perspectives,” for dealing with it. A “Perspective” uses the process description to provide an index into the history of a document moving through a process. Perspectives allow workflow systems to manage and present information about the execution of specific process instances within the general frame of abstract process descriptions.


Supporting memory for spatial location while reading from small displays

Research has shown that when people read paper documents, they develop an incidental memory for the location of information within those documents. However, this kind of spatial memory is undermined in conventional on-line scrolling interfaces. We report on an experiment in which we show that careful design of the interface can reinstate memory for spatial location. As we will show, this has particular implications for the design of interfaces for small screen displays.


Object lessons learned from a distributed system for remote building monitoring and operation

In this paper we describe our experiences with the design, the deployment, and the initial operation of a distributed system for the remote monitoring and operation of multiple heterogeneous commercial buildings across the Internet from a single control center. Such systems can significantly reduce building energy usage.Our system is distinguished by its ability to interface to multiple heterogeneous legacy building Energy Management Control Systems (EMCSs), its use of the Common Object Request Broker Architecture (CORBA) standard communication protocols for the former task, development of a standardized naming system for monitoring points in buildings, the use of a relational DBMS to store and process time series data, automatic time and unit conversion, and a scripted time series visualization system.We describe our design choices and our experiences in development and operation. We note requirements for future distributed systems software for interoperability of heterogeneous real-time data acquisition and control systems.