Volunteer computing
Computers continue to get faster exponentially, but the computational demands of science are growing even faster. Extreme requirements arise in at least three areas.
By David P. Anderson, March 2010
Articles Tagged: Performance
Articles & Features
Volunteer computing
Computers continue to get faster exponentially, but the computational demands of science are growing even faster. Extreme requirements arise in at least three areas.
By David P. Anderson, March 2010
Clouds at the crossroads
Despite its promise, most cloud computing innovations have been almost exclusively driven by a few industry leaders, such as Google, Amazon, Yahoo!, Microsoft, and IBM. The involvement of a wider research community, both in academia and industrial labs, has so far been patchy without a clear agenda. In our opinion, the limited participation stems from the prevalent view that clouds are mostly an engineering and business-oriented phenomenon based on stitching together existing technologies and tools.
By Ymir Vigfusson, Gregory Chockler, March 2010
Clouds at the crossroads
Despite its promise, most cloud computing innovations have been almost exclusively driven by a few industry leaders, such as Google, Amazon, Yahoo!, Microsoft, and IBM. The involvement of a wider research community, both in academia and industrial labs, has so far been patchy without a clear agenda. In our opinion, the limited participation stems from the prevalent view that clouds are mostly an engineering and business-oriented phenomenon based on stitching together existing technologies and tools.
By Ymir Vigfusson, Gregory Chockler, March 2010
Scientific workflows and clouds
In recent years, empirical science has been evolving from physical experimentation to computation-based research. In astronomy, researchers seldom spend time at a telescope, but instead access the large number of image databases that are created and curated by the community [42]. In bioinformatics, data repositories hosted by entities such as the National Institutes of Health [29] provide the data gathered by Genome-Wide Association Studies and enable researchers to link particular genotypes to a variety of diseases.
By Gideon Juve, Ewa Deelman, March 2010
Are your friends who they say they are?
How sure are you that your friends are who they say they are? In real life, unless you are the target of some form of espionage, you can usually be fairly certain that you know whom your friends are because you have a history of shared interests and experiences. Likewise, most people can tell, just by using common sense, if someone is trying to sell them on a product, idea, or candidate. When we interact with people face-to-face, we reevaluate continuously whether something just seems off based on body language and other social and cultural cues.
By Roya Feizy, Ian Wakeman, Dan Chalmers, December 2009
Towards a user-friendly semantic formalism for natural language generation
Computational semantics has become an interesting and important branch of computational linguistics. Born from the fusion of formal semantics and computer science, it is concerned with the automated processing of meaning associated with natural language expressions [2]. Systems of semantic representation, hereafter referred to as semantic formalisms, exist to describe meaning underlying natural language expressions. To date, several formalisms have been defined by researchers from a number of diverse disciplines including philosophy, logic, psychology and linguistics. These formalisms have a number of different applications in the realm of computer science. For example, in machine translation a sentence could be parsed and translated into a series of semantic expressions, which could then be used to generate an utterance with the same meaning in a different language [14]. This paper presents two existing formalisms and examines their user-friendliness. Additionally, a new form of semantic representation is proposed with wide coverage and user-friendliness suitable for a computational linguist.
By Craig Thomas, December 2008
Geometric and path tracing methods for simulating light transport through volumes of water particles
The visual appearance of volumes of water particles, such as clouds, waterfalls, and fog, depends both on microscopic interactions between light rays and individual droplets of water, and also on macroscopic interactions between multiple droplets and paths of light rays. This paper presents a model that builds upon a typical single-scattering volume renderer to correctly account for these effects. To accurately simulate the visual appearance of a surface or a volume of particles in a computer-generated image, the properties of the material or particle must be specified using a Bidirectional Reflectance Distribution Function (BRDF), which describes how light reflects off of a material, and the Bidirectional Transmittance Distribution Function (BTDF), which describes how light refracts into a material. This paper describes an optimized BRDF and BTDF for volumes of water droplets, which takes their geometry into account in order to produce well-known effects, such as rainbows and halos. It also describes how a multiple-scattering path tracing volume integrator can be used to more accurately simulate macroscopic light transport through a volume of water, creating a more "cloudlike" appearance than a single-scattered volume integrator. This paper focuses on replicating the visual appearance of volumes of water particles, and although it makes use of physical models, the techniques presented are not intended to be physically accurate.
By James Hegarty, September 2008
Comparison of input devices and displays for protein visualization
By Elke Moritz, Thomas Wischgoll, Joerg Meyer, December 2005
Introduction
By William Stevenson, October 2005
Introduction to programming shared-memory and distributed-memory parallel computers
By Cory Quammen, October 2005
Introduction to programming shared-memory and distributed-memory parallel computers
By Cory Quammen, October 2005
Game-state fidelity across distributed interactive games
By Aaron McCoy, Declan Delaney, Tomas Ward, October 2005
Game-state fidelity across distributed interactive games
By Aaron McCoy, Declan Delaney, Tomas Ward, October 2005
Introduction
By William Stevenson, August 2005
An interaction model for mobile agent services using social networks
By Vishakh, Nicholas Urrea, Tadashi Nakano, Tatsuya Suda, August 2005
Overcoming misbehavior in mobile ad hoc networks
By George Athanasiou, Leandros Tassiulas, Gregory S. Yovanof, August 2005
Overcoming misbehavior in mobile ad hoc networks
By George Athanasiou, Leandros Tassiulas, Gregory S. Yovanof, August 2005
Experimental mobile gateways
By Premshree Pillai, August 2005
Experimental mobile gateways
By Premshree Pillai, August 2005
Game-state fidelity across distributed interactive games
By Aaron McCoy, Declan Delaney, Tomas Ward, June 2003
Q2ADPZ* an open source, multi-platform system for distributed computing
By Zoran Constantinescu, Pavel Petrovic, December 2002
Building an MPI cluster
By Donald C. Bergen, Boise P. Miller, August 2002
Optimizing application performance
By M. Tyler Maxwell, Kirk W. Cameron, August 2002
Evolutionary learning in mobile robot navigation
By Cory Quammen, December 2001
Connector
By Kostas Pentikousis, July 2001
Connector
By Kostas Pentikousis, July 2001
Introduction to mobile computing
By Sandeep Jain, December 2000
Can TCP be the transport protocol of the 21st century?
By Kostas Pentikousis, December 2000
Macromedia director as a prototyping and usability testing tool
By Stephanie Ludi, July 2000
Graphic libraries for Windows programming
By M. Carmen Juan Lizandra, June 2000
The many dimensions of the software process
By Sebastián Tyrrell, June 2000
The world of data compression
By Eric Scheirer, March 2000
In memory of David Huffman
By Kevin Fu, March 2000
Objective viewpoint
By Matt Tucker, March 2000
Design of an interactive tutorial for logic and logical circuits
By Jeremy Kindy, John Shuping, Patricia Yali Underhill, David John, March 2000
Image compression—from DCT to wavelets
By Subhasis Saha, March 2000
Prefix compression of sparse binary strings
Note from ACM Crossroads: Due to errors in the layout process for printing on paper, the version of this article in the printed magazine contained several errors (mostly related to superscripts). This HTML version is the accurate version. Please refer to this HTML version instead of the printed version and accept our apologies for any inconvenience.
By David Salomon, March 2000
A hierarchical error controlled octree data structure for large-scale visualization
By Dmitriy V. Pinskiy, Joerg Meyer, Bernd Hamann, Kenneth I. Joy, Eric Brugger, Mark Duchaineau, March 2000
Ask Jack
By Jack Wilson, March 2000
Introduction
By Kevin Fu, September 1999
Objective viewpoint
By George Crawford, September 1999
Choosing a Ph.D. program in computer science
By Rachel Pottinger, September 1999
Linux DSP shell
By Michael Stricklen, Bob Cummings, Brandon Bonner, September 1999
Introduction to Linux networking and security
By Wei-Mei Shyr, Brian Borowski, September 1999
Parallel computing with Linux
By Forrest Hoffman, William Hargrove, September 1999
The Texas Tech tornado cluster
By Per Andersen, September 1999
Introduction
By Alessio Lomusico, June 1999
Where do intelligent agents come from?
By Cristobal Baray, Kyle Wagner, June 1999
Protecting the integrity of agents
By Michael J. Grimley, Brian D. Monroe, June 1999
Towards a standardization of multi-agent system framework
By Roberto A. Flores-Mendez, June 1999
Web hunting
By G. Michael Youngblood, June 1999
Re-configurable computing
By Richard Swan, Anthony Wyatt, Richard Cant, Caroline Langensiepen, April 1999
The processor-memory bottleneck
The rate of improvement in microprocessor speed exceeds the rate of improvement in DRAM (Dynamic Random Access Memory) speed. So although the disparity between processor and memory speed is already an issue, downstream someplace it will be a much bigger one. Hence computer designers are faced with an increasing Processor - Memory Performance Gap [1], which now is the primary obstacle to improved computer system performance. This article examines this problem as well as its various solutions.
By Nihar R. Mahapatra, Balakrishna Venkatrao, April 1999
Introduction
By Scott Lewandowski, March 1999
Objective viewpoint
By George Crawford, March 1999
Making a careers presentation
By Jack Wilson, March 1999
PiSMA
By Dimitris Lioupis, Andreas Pipis, Maria Smirli, Michael Stefanidakis, March 1999
Architectures and compilers to support reconfigurable computing
By João M. P. Cardoso, Mário P. Vestístias, March 1999
Architectures and compilers to support reconfigurable computing
By João M. P. Cardoso, Mário P. Vestístias, March 1999
Computing in the former Soviet Union and eastern Europe
By Shane Hart, March 1999
Parallel processing in heterogeneous cluster architechtures using JavaPorts
By Demetris G. Galatopoullos, Elias S. Manolakos, March 1999
Parallel processing in heterogeneous cluster architechtures using JavaPorts
By Demetris G. Galatopoullos, Elias S. Manolakos, March 1999
Networks and distributed systems: introduction
By Kevin Fu, November 1998
Web site review: ADSL forum
By Shawn Brown, November 1998
Creating a 3D universe in Java3D
By George Crawford, November 1998
Ask Jack: making a careers presentation
By Jack Wilson, November 1998
AgentOS
By Larry Chen, November 1998
Design and implementation of a digital library
By James Richvalsky, David Watkins, November 1998
Confidentially using authentication
By Robert Schlaff, November 1998
Knowledge discovery in databases
By Peggy Wright, November 1998
The Damocles Sword of Academic Publishing
Doctoral students often find it hard to understand at what level of productivity they should be. Through an analysis of resums of doctoral students in the Management Information Systems (MIS) field, a better understanding of what is expected of current students as compared to former students is achieved. Both conference presentations and publications in journals are examined. Finally, there is an examination of whether the quantity of publications can be related to the ranking of the school that a student attends.
By Kai Larsen, November 1998
Introduction
By Lynellen D. S. Perry, September 1998
Objective viewpoint: Java AWT layout management 101
This article provides a brief summary of basic layout management in the Java Abstract Window Toolkit (AWT) and is intended to serve as a foundation for more sophisticated AWT programming.
By George Crawford, September 1998
Ask Jack: careerline Q & A
By Jack Wilson, September 1998
A formative evaluation of scenario-based tools for learning object-oriented design
Advances in computing have awakened a century old teaching philosophy: learner-centered education. This philosophy is founded on the premise that people learn best when engrossed in the topic, participating in activities that motivate learning and help them to synthesize their own understanding. We consider how the object-oriented design (OOD) learning tools developed by Rosson and Carroll [5] facilitate active learning of this sort. We observed sixteen students as they worked through a set of user interaction scenarios about a blackjack game. We discuss how the features of these learning tools influenced the students' efforts to learn the basic constructs of OOD.
By Hope D. Harley, Cheryl D. Seals, Mary Beth Rosson, September 1998
Much ado about patterns
By Robert Zubek, September 1998
Explanation component of software system
Explanation is an important feature that needs to be integrated into software products. Early software that filled the horizontal software market (such as word processors) contained help systems. More specialized systems, known as expert systems, were developed to produce solutions that required specific domain knowledge of the problem being solved. The expert systems initially produced results that were consistent with the results produced by experts, but the expert systems only mimicked the rules the experts outlined. The decisions provided by expert systems include no justification, thus causing users to doubt the results reported by the system. If the user was dealing with a human expert, he could ask for a line of reasoning used to draw the conclusion. The line of reasoning provided by the human expert could then be inspected for discrepancies by another expert or verified in some other manner. Software systems need better explanations of how to use them and how they produce results. This will allow the users to take advantage of the numerous features being provided and increase their trust in the software product.
By Bruce A. Wooley, September 1998
Multimedia systems: introduction
By Erika Dawn Gernand, May 1998
Towards usability evaluation of multimedia applications
By Marianne G. Petersen, May 1998
The use of Java as an introductory programming language
By Jason Hong, May 1998
Networking on the network
By Phil Agre, May 1998
The Turing test
By Lynellen D. S. Perry, May 1998
A simple SMTP framework for Java
By George Crawford, May 1998
Ask Jack: job search in cyberspace
By Jack Wilson, May 1998
Mars rover
By Sharon Lauback, April 1998
RoboCup
By Hiroaki Kitano, Minoru Asada, Itsuki Noda, Hitoshi Matsubara, April 1998
CMUnited
Robotic soccer is a challenging research domain involving multiple agents that need to collaborate in an adversarial environment to achieve specific objectives. This article describes CMUnited, the team of small robotic agents that we developed to enter the RoboCup-97 competition. We designed and built the robotic agents, devised the appropriate vision algorithm, and developed and implemented algorithms for strategic collaboration between the robots in an uncertain and dynamic environment. The robots can organize themselves in formations, hold specific roles, and pursue their goals. In game situations, they have demonstrated their collaborative behaviors on multiple occasions. The robots can also switch roles to maximize the overall performance of the team. We present an overview of the vision processing algorithm which successfully tracks multiple moving objects and predicts trajectories. The paper then focuses on the agents' behaviors ranging from low-level individual behaviors to coordinated, strategic team behaviors. CMUnited won the RoboCup-97 small-robot competition at IJCAI-97 in Nagoya, Japan.
By Manuela Veloso, Peter Stone, Kwun Han, Sorin Achim, April 1998
Evolutionary control via sensorimotor input and actuation
By Todd M. Schrider, April 1998
Protecting Java code via code obfuscation
The Java language is compiled into a platform independent bytecode format. Much of the information contained in the original source code remains in the bytecode, thus decompilation is easy. We will examine how code obfuscation can help protect Java bytecodes.
By Douglas Low, April 1998
The wonders of Java object serialization
By Brian T. Kurotsuchi, November 1997
Using the Java Native Interface
The Java Native Interface (JNI) comes with the standard Java Development Kit (JDK) from Sun Microsystems. It permits Java programmers to integrate native code (currently C and C++) into their Java applications. This article will focus on how to make use of the JNI and will provide a few examples illustrating the usefulness of this feature. Although a native method system was included with the JDK 1.0 release, this article is concerned with the JDK 1.1 JNI which has several new features, and is much cleaner than the previous release. Also, the examples given will be specific to JDK 1.1 installed on the Solaris Operating System.
By S. Fouzi Husaini, November 1997
Geographic information systems and problem solving environments
By Jinsoo Park, October 1997
A sustainable fishing simulation using mathematical modeling and database access through the World Wide Web
By Vineet Kapur, Douglas Troy, James Oris, October 1997
Ray tracing
By Paul Rademacher, May 1997
A human's eye view
Frameless Rendering (FR) is a rendering paradigm which performs stochastic temporal filtering by updating pixels in a random order, based on most recent available input data, and displaying them to the screen immediately [1]. This is a departure from frame-based approaches commonly experienced in interactive graphics. A typical interactive graphics session uses a single input state to compute an entire frame. This constrains the state to be known at the time the first pixel's value is computed. Frameless Rendering samples inputs many times during the interval which begins at the start of the first pixel's computation and ends with the last pixel's computation. Thus, Frameless Rendering performs temporal supersampling - it uses more samples over time. This results in an approximation to motion blur, both theoretically and perceptually.This paper explores this motion blur and its relationship to: camera open shutter time, current computer graphics motion-blur implementations, temporally anti-aliased images, and the Human Visual System's (HVS) motion smear quality (see 'quality' footnote) [2].Finally, we integrate existing research results to conjecture how Frameless Rendering can use knowledge of the Human Visual System's blurred retinal image to direct spatiotemporal sampling. In other words, we suggest importance sampling (see 'sampling' footnote) by prioritizing pixels for computation based on their importance to the visual system in discerning what is occurring in an interactive image sequence.
By Ellen J. Scher Zagier, May 1997
Levels of detail & polygonal simplification
This paper covers the techniques of Polygonal Simplification in order to produce Levels of Detail (LODs). The problem of creating LODs is a complex one: how can simpler versions of a model be created? How can the approximation error be measured? How can the visual degradation be estimated? Can all this be done automatically? After exposing the basic aims and principles of polygonal simplification, we compare recent algorithms and state their various qualities and weaknesses.
By Mike Krus, Patrick Bourdot, Françoise Guisnel, Gullaume Thibault, May 1997
Faster 3D game graphics by not drawing what is not seen
The increasing demands of 3D game realism - in terms of both scene complexity and speed of animation - are placing excessive strain on the current low-level, computationally expensive graphics drawing operations. Despite these routines being highly optimized, specialized, and often being implemented in assembly language or even in hardware, the ever-increasing number of drawing requests for a single frame of animation causes even these systems to become overloaded, degrading the overall performance. To offset these demands and dramatically reduce the load on the graphics subsystem, we present a system that quickly and efficiently finds a large portion of the game world that is not visible to the viewer for each frame of animation, and simply prevents it from being sent to the graphics system. We build this searching mechanism for unseen parts from common and easily implemented graphics algorithms.
By Kenneth E. Hoff, May 1997
An introduction to the GIMP
By Matt Cutts, May 1997
Techniques & tools for using color in computer interface design
Contemporary computers predominantly employ graphical user interfaces (GUIS) and colour is a major componenet of the GUI. Every man-machine interface is composed of two major parts:the man and the machine [4]. Color interfaces are no different in that they are also based on two parts, the Human visual system (HVS) and a color display system. A theoretical examination of these two components establishes a foundation for developing practical guidelines for color interfaces. This paper will briefly examine theoretical aspects of both components and established techniques and tools for the effective use of color for software interface design.
By Peggy Wright, Diane Mosser-Wooley, Bruce Wooley, April 1997
User interface correctness
By Ian MacColl, David Carrington, April 1997
Human factors in haptic interfaces
By Christopher M. Smith, April 1997
Task integration in multimodal speech recognition environments
By Michael A. Grasso, Tim Finin, April 1997
An investigation of current virtual reality interfaces
Virtual Reality hype is becoming a large part of everyday life. This paper explores the components of actual virtual reality systems, critiquing each in terms of human factors. The hardware and software of visual, aural, and haptic input and feedback are considered. Technical and human factor difficulties are discussed and some potential solutions are offered.
By Lynellen D. S. Perry, Christopher M. Smith, Steven Yang, April 1997
The story of XPilot
By Bjorn Stabell, Ken Ronny Schouten, November 1996
The video game [R]evolution
By Sarah Elizabeth Burcham, November 1996
Computer game marketing bias
By Melissa Chaika, November 1996
Computer vision and artificial intelligence
By Christopher O. Jaynes, September 1996
Applications of AI in education
By Joseph Beck, Mia Stern, Erik Haugsjaa, September 1996
Reasoning about computational resource allocation
Anytime Algorithms are algorithms that exchange execution time for quality of results. Since many computational tasks are too complicated to be completed at real-time speeds, anytime algorithms allow systems to intelligently allocate computational time resources in the most effective way, depending on the current environment and the system's goals. This article briefly covers the motivations for creating anytime algorithms, the history of their development, a definition of anytime algorithms, and current research involving anytime algorithms.
By Joshua Grass, September 1996
An introduction to intrusion detection
By Aurobindo Sundaram, April 1996
Electronic voting
By Lorrie Faith Cranor, April 1996
Mutual authenticating protocol with key distribution in client/server environment
The explosive growth of networked and internetworked computer systems during the past decade has brought about a need for increased protection mechanisms. This paper discusses three authentication protocols that incorporate the use of methods that present effective user authentication. The first two protocols have been previously discussed in the literature; the third protocol draws from the first two and others to produce an authentication scheme that provides both mutual authentication and secure key distribution which is easy to use, is compatible with present operating systems, is transparent across systems, and provides password file protection.
By Charles Cavaiani, Jim Alves-Foss, April 1996
Facilitating abstraction and reuse with ExpectTK
By Navid Sabbaghi, February 1996
The Internet's history and development
By Scott Ruthfield, September 1995
Website review: Charles Babbage Institute
By Ben W. Brumfield, September 1995
The MBONE
By Jay A. Kreibich, September 1995
Network security, filters and firewalls
By Darren Bolding, September 1995
The Road Less Traveled: an alternative review of Doom II
By Lorrie Faith Cranor, February 1995
Software Review: my humble opinions on Windows NT vs. OS/2
By Ronald B. Krisko, February 1995
Book Reviews: serial communications books
By Saveen Reddy, September 1994
Software review: tie fighter
By Terry White, September 1994