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Articles 1 - 30 of 36
Full-Text Articles in Engineering
Work In Progress: Automating Proportion/Period Scheduling, David Steere, Jonathan Walpole, Calton Pu
Work In Progress: Automating Proportion/Period Scheduling, David Steere, Jonathan Walpole, Calton Pu
Computer Science Faculty Publications and Presentations
The recent effort to define middleware capable of supporting real-time applications creates the opportunity to raise the level of abstraction presented to the programmer. We propose that proportion/period is a better abstraction for specifying resource needs and allocation than priorities. We are currently investigating techniques to address some issues that are restricting use of proportion/period scheduling to research real-time prototypes. In particular, we are investigating techniques to automate the task of selecting proportion and period, and that allow proportion/period to incorporate job importance under overload conditions.
Investigation Of Image Feature Extraction By A Genetic Algorithm, Steven P. Brumby, James P. Theiler, Simon J. Perkins, Neal R. Harvey, John J. Szymanski, Jeffrey J. Bloch, Melanie Mitchell
Investigation Of Image Feature Extraction By A Genetic Algorithm, Steven P. Brumby, James P. Theiler, Simon J. Perkins, Neal R. Harvey, John J. Szymanski, Jeffrey J. Bloch, Melanie Mitchell
Computer Science Faculty Publications and Presentations
We describe the implementation and performance of a genetic algorithm which generates image feature extraction algorithms for remote sensing applications. We describe our basis set of primitive image operators and present our chromosomal representation of a complete algorithm. Our initial application has been geospatial feature extraction using publicly available multi-spectral aerial-photography data sets. We present the preliminary results of our analysis of the efficiency of the classic genetic operations of crossover and mutation for our application, and discuss our choice of evolutionary control parameters. We exhibit some of our evolved algorithms, and discuss possible avenues for future progress.
Qos Scalability For Streamed Media Delivery, Charles Krasic, Jonathan Walpole
Qos Scalability For Streamed Media Delivery, Charles Krasic, Jonathan Walpole
Computer Science Faculty Publications and Presentations
Applications with real-rate progress requirements, such as mediastreaming systems, are difficult to deploy in shared heterogenous environments such as the Internet. On the Internet, mediastreaming systems must be capable of trading off resource requirements against the quality of the media streams they deliver, in order to match wide-ranging dynamic variations in bandwidth between servers and clients. Since quality requirements tend to be user- and task-specific, mechanisms for capturing quality of service requirements and mapping them to appropriate resource-level adaptation policies are required. In this paper, we describe a general approach for automatically mapping user-level quality of service specifications onto resource …
Fine-Grain Period Adaptation In Soft Real-Time Environments, David Steere, Joshua Gruenberg, Dylan Mcnamee, Calton Pu, Jonathan Walpole
Fine-Grain Period Adaptation In Soft Real-Time Environments, David Steere, Joshua Gruenberg, Dylan Mcnamee, Calton Pu, Jonathan Walpole
Computer Science Faculty Publications and Presentations
Reservation-based scheduling delivers a proportion of the CPU to jobs over a period of time. In this paper we argue that automatically determining and assigning this period is both possible and useful in general purpose soft real-time environments such as personal computers and information appliances. The goal of period adaptation is to select the period over which a job is guaranteed to receive its portion of the CPU dynamically and automatically. The choice of period represents a trade-off between the amount of jitter observed by the job and the overall efficiency of the system. Secondary effects of period include quantization …
Bargaining With Deadlines, Tuomas Sandholm, Nir Vulkan
Bargaining With Deadlines, Tuomas Sandholm, Nir Vulkan
All Computer Science and Engineering Research
This paper analyzes automated distributive negotiation where agents have firm deadlines that are private information. The agents are allowed to make and accept offers in any order in continuous time. We show that the only sequential equilibrum outcome is the one where the agents wait until the first deadline, at which point that agent concedes everything to the other. This holds for pure and mixed strategies. So, interestingly, rational agents can never agree to a nontrivial split because offers signal enough weakness of bargaining power (early deadline) so that the recipient should never accept. Similarly, the offerer knows that it …
Terabit Burst Switching Progress Report (12/98-6-99), Jonathan S. Turner
Terabit Burst Switching Progress Report (12/98-6-99), Jonathan S. Turner
All Computer Science and Engineering Research
This report summarizes progress on Washington University's Terabit Burst Switching Project, supported by DARPA and Rome Air Force Laboratory. This project seeks to demonstrate the feasibility of Burst Switching, a new data communication service which can more effectively exploit the large bandwidths becoming available in WDM transmission systems, than conventional communication technologies like ATM and IP-based packet switching. Burst switching systems dynamically assign data bursts to channels in optical data links, using routing information carried in parallel control channels. The project will lead to the construction of a demonstration switch with throughput exceeding 200 Gb/s and scalable to over 10 …
Constructing Speculative Demand Functions In Equilibrium Markets, Tuomas Sandholm, Fredrik Ygge
Constructing Speculative Demand Functions In Equilibrium Markets, Tuomas Sandholm, Fredrik Ygge
All Computer Science and Engineering Research
In computational markets utilizing algorithms that establish a general equilibrium, competitive behavior is usually assumed: each agent makes its demand (supply) decisions so as to maximize its utility (profit) assuming that it has no impact on market prices. However, there is a potential gain from strategic behavior via speculating about others because an agent does affect the market prices, which affect the supply/demand decisions of others, which again affect the market prices that the agent faces. Determining the optimal strategy when the speculator has perfect knowledge about the other agents is a well known problem which has been studied in …
Multiple Stochastic Learning Automata For Vehicle Path Control In An Automated Highway System, Cem Unsal, Pushkin Kachroo, John S. Bay
Multiple Stochastic Learning Automata For Vehicle Path Control In An Automated Highway System, Cem Unsal, Pushkin Kachroo, John S. Bay
Electrical & Computer Engineering Faculty Research
This paper suggests an intelligent controller for an automated vehicle planning its own trajectory based on sensor and communication data. The intelligent controller is designed using the learning stochastic automata theory. Using the data received from on-board sensors, two automata (one for lateral actions, one for longitudinal actions) can learn the best possible action to avoid collisions. The system has the advantage of being able to work in unmodeled stochastic environments, unlike adaptive control methods or expert systems. Simulations for simultaneous lateral and longitudinal control of a vehicle provide encouraging results
Adaptive Resource Management Via Modular Feedback Control, Ashvin Goel, David Steere, Calton Pu, Jonathan Walpole
Adaptive Resource Management Via Modular Feedback Control, Ashvin Goel, David Steere, Calton Pu, Jonathan Walpole
Computer Science Faculty Publications and Presentations
A key feature of tomorrow’s operating systems and runtime environments is their ability to adapt. Current state of the art uses an ad-hoc approach to building adaptive software, resulting in systems that can be complex, unpredictable and brittle. We advocate a modular and methodical approach for building adaptive system software based on feedback control. The use of feedback allows a system to automatically adapt to dynamically varying environments and loads, and allows the system designer to utilize the substantial body of knowledge in other engineering disciplines for building adaptive systems. We have developed a toolkit called SWiFT that embodies this …
Feedback Based Dynamic Proportion Allocation For Disk I/O, Dan Revel, Dylan Mcnamee, Calton Pu, David Steere, Jonathan Walpole
Feedback Based Dynamic Proportion Allocation For Disk I/O, Dan Revel, Dylan Mcnamee, Calton Pu, David Steere, Jonathan Walpole
Computer Science Faculty Publications and Presentations
In this paper we propose to use feedback control to automatically allocate disk bandwidth in order to match the rate of disk I/O to the real-rate needs of applications. We describe a model for adaptive resource management based on measuring the relative progress of stages in a producer-consumer pipeline. We show how to use prefetching to transform a passive disk into an active data producer whose progress can be controlled via feedback. Our progress-based framework allows the integrated control of multiple resources. The resulting system automatically adapts to varying application rates as well as to varying device latencies.
An Algorithm For Optimal Winner Determination In Combinatorial Auctions, Tuomas Sandholm
An Algorithm For Optimal Winner Determination In Combinatorial Auctions, Tuomas Sandholm
All Computer Science and Engineering Research
Combinatorial auctions, i.e. auctions where bidders can bid on combinations of items, tend to lead to more efficient allocations than traditional auctions in multi-item auctions where the agents' valuations of the items are not additive. However, determining the winners so as to maximize revenue is NP-complete. First, existing approaches for tackling this problem are reviewed: exhaustive enumeration, dynamic programming, approximation algorithms, and restricting the alloable combinations. Then we present our search algorithm for optimal winner determination. Experiments are shown on several bid distributions. The algorithm allows combinatorial auctions to scale up to significantly larger numbers of items and bids than …
Revenue Equivalence Of Leveled Commitment Contracts, Tuomas Sandholm, Yunhong Zhou
Revenue Equivalence Of Leveled Commitment Contracts, Tuomas Sandholm, Yunhong Zhou
All Computer Science and Engineering Research
In automated negotiation systems consisting of self-interested agents, contracts have traditionally been binding. Leveled commitment contracts - i.e. contracts where each party can decommit by paying a predetermined penalty - were recently shown to improve expected social welfare even if agents decommit insincerely in Nash equilibrium. Such contracts differ based on whether agents have to declare their decommitting decisions sequentially or simultaneously, and whether or not agents have to pay the penalties if both decommit. For a given contract, these protocols lead to different decommitting thresholds and probabilities. However, this paper shows that, surprisingly, each protocol leads to the same …
A Proposal For A High-Performance Active Hardware Architecture, Tilman Wolf
A Proposal For A High-Performance Active Hardware Architecture, Tilman Wolf
All Computer Science and Engineering Research
Current research in Active Networking is focused on developing software architectures and defining funtionality of Execution Environments. While active network systems show superior functionality compared to traditional networks, they only operate at substantially lower link speeds. To increase the acceptance of Active Network in environments where link speeds of several Gb/s are common, we propose a hardware architecture that performs high-speed packet handling while providing the same flexibility as a common software system. The design exploits the independence between data streams for parallel processing. To measure the impact of different design decisions on the performance of the system, we also …
Assembly And Analysis Of Extended Human Genomic Contig Regions, Eric C. Rouchka, David J. States
Assembly And Analysis Of Extended Human Genomic Contig Regions, Eric C. Rouchka, David J. States
All Computer Science and Engineering Research
The Human Genome Project (HGP) has led to the deposit of human genomic sequence in the form of sequenced clones into various databases such as the DNA Data Bank of Japan (DDBJ) (Tateno and Gojobori, 1997), the European Molecular Biology Laboratory (EMBL) Nucleotide Sequence Database (Stoesser, et. al., 1999), and GenBank (Benson, et. al., 1998). Many of these sequenced clones occur in regions where sequencing has taken place either within the same sequencing center or other centers throughout the world. The assembly of extended segments of genomic sequence by looking at overlapping end segments is desired and is currently availabel …
The Design And Performance Of A Pluggable Protocols Framework For Object Request Broker Middleware, Fred Kuhns, Carlos O'Ryan, Douglas C. Schmidt, Jeff Parsons
The Design And Performance Of A Pluggable Protocols Framework For Object Request Broker Middleware, Fred Kuhns, Carlos O'Ryan, Douglas C. Schmidt, Jeff Parsons
All Computer Science and Engineering Research
To be an effective platform for performance-sensitive real-time and embedded applications, off-the-shelf OO middleware like CORBA, DCOM, and Java RMI must preserve communication-layer quality of service (QoS) properties to applications end-to-end. However, conventional OO middleware interoperability protocols, such as CORBA's GIOP/IIOP or DCOM's MS-RPC, are not well suited for applications that cannot tolerate the message footprint size, latency, and jitter associated with general-purpose messaging and transport protocols. It is essential, therefore, to develop standard plugable protocols frameworks that allow custom messaging and transport protocols to be configured flexibly and used transparently by applications. This paper provides three contributions to research …
Anmac: A Novel Architectural Framework For Network Management And Control Using Active Networks, Samphel Norden
Anmac: A Novel Architectural Framework For Network Management And Control Using Active Networks, Samphel Norden
All Computer Science and Engineering Research
In this paper, we propose a new framework called Active Network Management and Control (ANMAC) for the management and control of high speed networks. The software architecture in ANMAC allows routers to execute dynamically loadable kernel plug-in modules which perform diagnostic functions for network management. ANMAC uses mobile probe packets to perform efficient resource reservation (using our novel reservation scheme), facilitate feedback-based congestion control, and to provide "distributed debugging" of complex anomalous network behavior. ANMAC also provides security measures against IP spoofing, and other security attacks. The network manager has the flexibility to install custom scripts in routers for tracking …
Emediator: A Next Generation Electronic Commerce Server, Tuomas Sandholm
Emediator: A Next Generation Electronic Commerce Server, Tuomas Sandholm
All Computer Science and Engineering Research
This paper presents eMediator, a next generation electronic commerce server that demonstrates some ways in which AI, algorithmic support, and game theoretic incentive engineering can jointly improve the efficiency of ecommerce. First, its configurable auction house includes a variety of generalized combinatorial auctions, price setting mechanism, novel bid types, mobile agents, and user support for choosing an auction type. Second, its leveled commitment contract optimizer determines the optimal contract price and decommitting penalties for a variety of leveled commitment contracting protocols, taking into account that rational agents will decommit insincerely in taking into account that rational agents will decommit insincerely …
Algorithms For Optimizing Leveled Commitment Contracts, Thomas Sandholm, Sandeep Sikka, Samphel Norden
Algorithms For Optimizing Leveled Commitment Contracts, Thomas Sandholm, Sandeep Sikka, Samphel Norden
All Computer Science and Engineering Research
In automated negotiation systems consisting of self-interested agents, contracts have traditionally been binding. Leveled commitment contracts - i.e. contracts where each party can decommit by paying a predetermined penalty - were recently shown to improve Pareto efficiency even if agents rationally decommit in Nash equilibrium using inflated thresholds on how good their outside offers must be before they decommit. This paper operationalizes the four leveled commitment contracting protocols by presenting algorithms for using them. Algorithms are presented for computing the Nash equilibrium decomitting thresholds and decommitting probabilities given the contract price and the penalties. Existence and uniqueness of the equilibrium …
Optimal Flow Aggregation, Subhash Suri, Tuomas Sandholm, Priyank Warkhede
Optimal Flow Aggregation, Subhash Suri, Tuomas Sandholm, Priyank Warkhede
All Computer Science and Engineering Research
Current IP routers are stateless: they forward individual packets based on the destination address contained in the packet header, but maintain no information about the application or flow to which a packet belongs. This stateless service model works well for best effort datagram delivery, but is grossly inadequate for applications that require quality of service guarantees, such as audio, video, or IP telephony. Maintaining state for each flow is expensive because the number of concurrent flows at a router can be in the hundreds of thousands. Thus, stateful solutions such as Intserv (integrated services) have not been adopted for their …
Multiway Range Trees: Scalable Ip Lookup With Fast Updates, Subhash Suri, George Varghese, Piryank Ramesh Warkhede
Multiway Range Trees: Scalable Ip Lookup With Fast Updates, Subhash Suri, George Varghese, Piryank Ramesh Warkhede
All Computer Science and Engineering Research
Internet routers forward packets based on the destination address of a packet. A packet's address is matched against the destination prefixes stored in the router's forwarding table, and the packet is sent to the output interface determined by the longest matching prefix. While some existing schemes work well for IPv4 addresses, we believe that none of the current schemes scales well to IPv6, especially when fast updates are required. As the Internet evolves into a global communication medium, requiring multiple addresses per user, the switch to longer addresses (e.g. IPv6) seems inevitable despite temporary measures such as network addres translation …
Pattern Matching Techniques And Their Applications To Computational Molecular Biology - A Review, Eric C. Rouchka
Pattern Matching Techniques And Their Applications To Computational Molecular Biology - A Review, Eric C. Rouchka
All Computer Science and Engineering Research
Pattern matching techniques have been useful in solving many problems associated with computer science, including data compression (Chrochemore and Lecroq, 1996), data encryption (RSA Laboratories, 1993), and computer vision (Grimson and Huttenlocher, 1990). In recent years, developments in molecular biology have led to large scale sequencing of genomic DNA. Since this data is being produced in such rapid fasion, tools to analyze DNA segments are desired. The goal here is to discuss various techniques and tools for solving various pattern matching questions in computational biology, including optimal sequence alignment, multiple sequence alignment, and buidling models to describe sequence families using …
Design Issues For High Performance Active Routers, Tilman Wolf, Jonathan Turner
Design Issues For High Performance Active Routers, Tilman Wolf, Jonathan Turner
All Computer Science and Engineering Research
Active networking is a general approach to incorporating general-purpose computational capabilities within the communications infrastructure of data networks. This paper proposes a design of a scalable, high performance active router. This is used as a vehicle for studying the key design issues that must be resolved to allow active networking to become a mainstream technology.
Commbench - A Telecommunications Benchmark For Network Processors, Tilman Wolf, Mark Franklin
Commbench - A Telecommunications Benchmark For Network Processors, Tilman Wolf, Mark Franklin
All Computer Science and Engineering Research
This paper presents a benchmark, CommBench, for use in evaluating and designing telecommunications network processors. The benchmark applications focus on small, computationally intense program kernels typical of the network processor environment. The benchmark is composed of eight programs, four of them oriented towards packet header processing and four oriented towards data stream procesing. The benchmark is defined and various characteristics of the benchmark are presented. These include instruction frequencies, computational complexity, and cache performance. These measured characteristics are compared to the SPEC benchmark which has traditionally been used in evaluating workstation processors. Three examples are presented indicating how CommBench can …
Tracking Mobile Units For Dependable Message Delivery, Amy L. Murphy, Gruia-Catalin Roman, George Varghese
Tracking Mobile Units For Dependable Message Delivery, Amy L. Murphy, Gruia-Catalin Roman, George Varghese
All Computer Science and Engineering Research
As computing components get smaller and people become accustomed to having computational power at their disposal at any time, mobile computing is developing as an important research area. One of the fundamental problems in mobility is maintaining connectivity through message passing as the user moves through the network. An approach to this is to have a single home node constantly track the current location of the mobile unit and forward messages to this location. One problem with this approach is that during the update to the home agent after movement, messages are often dropped, especially in the case of frequent …
Smart Objects, Dumb Archives: A User-Centric, Layered Digital Library Framework, Kurt Maly, Michael L. Nelson, Mohammad Zubair
Smart Objects, Dumb Archives: A User-Centric, Layered Digital Library Framework, Kurt Maly, Michael L. Nelson, Mohammad Zubair
Computer Science Faculty Publications
Discusses digital libraries, interoperability, and interfaces to access them, and proposes one universal protocol for communication for simple archives based on the hypertext transfer protocol (http). Describes the creation of a special class of digital objects called buckets, archives based on a NASA collection, and a set of digital library services. (Author/LRW)
Compute As Fast As The Engineers Can Think! Utrafast Computing Team Final Report, Robert T. Biedron, P. Mehrotra, Michael L. Nelson, M. L. Preston, J. J. Rehder, J. L. Rogersm, D. H. Rudy, J. Sobieski, O. O. Storaasli
Compute As Fast As The Engineers Can Think! Utrafast Computing Team Final Report, Robert T. Biedron, P. Mehrotra, Michael L. Nelson, M. L. Preston, J. J. Rehder, J. L. Rogersm, D. H. Rudy, J. Sobieski, O. O. Storaasli
Computer Science Faculty Publications
This report documents findings and recommendations by the Ultrafast Computing Team (UCT). In the period 10-12/98, UCT reviewed design case scenarios for a supersonic transport and a reusable launch vehicle to derive computing requirements necessary for support of a design process with efficiency so radically improved that human thought rather than the computer paces the process. Assessment of the present computing capability against the above requirements indicated a need for further improvement in computing speed by several orders of magnitude to reduce time to solution from tens of hours to seconds in major applications. Evaluation of the trends in computer …
A Digital Library For The National Advisory Committee For Aeronautics, Michael L. Nelson
A Digital Library For The National Advisory Committee For Aeronautics, Michael L. Nelson
Computer Science Faculty Publications
We describe the digital library (DL) for the National Advisory Committee for Aeronautics (NACA), the NACA Technical Report Server (NACATRS). The predecessor organization for the National Aeronautics and Space Administration (NASA), NACA existed from 1915 until 1958. The primary manifestation of NACA's research was the NACA report series. We describe the process of converting this collection of reports to digital format and making it available on the World Wide Web (WWW) and is a node in the NASA Technical Report Server (NTRS). We describe the current state of the project, the resulting DL technology developed from the project, and the …
Auctions Without Common Knowledge, Sviatoslav B. Brainov, Tuomas W. Sandholm
Auctions Without Common Knowledge, Sviatoslav B. Brainov, Tuomas W. Sandholm
All Computer Science and Engineering Research
This paper proves that the revenue equivalence theorem ceases to hold for auctions without common knowledge about the agents' prior beliefs. That is, different auction forms yield different expected revenue. To prove this, an auction game is converted to a Bayesian decision problem with an infinite hierarchy of beliefs. A general solution for such Bayesian decision problems is proposed. The solution is a generalization of the standard Bayesian solution and coincides with it for finite belief trees and for trees representing common knowledge. It is shown how the solution generalizes the frequently used technique of backward induction for infinite belief …
A Fine-Grained Model For Code Mobility, Cecilia Mascolo, Gian Pietro Picco, Gruia-Catalin Roman
A Fine-Grained Model For Code Mobility, Cecilia Mascolo, Gian Pietro Picco, Gruia-Catalin Roman
All Computer Science and Engineering Research
In this paper, we take the extreme view that every line of code is potentially mobile, i.e., may be duplicated and/or moved from one program context to another on the same host or across the network. Our motivation is to gain a better understanding of the range of constructs and issues facing the designer of a mobile code system, in a setting that is abstract and unconstrained by compilation and performance considerations traditionally associated with programming language design. Incidental to our study is an evaluatoin of the expressive power of Mobile UNITY, a notation and proof logic for mobile computing.
Reliable Communication For Highly Mobile Agents, Amy L. Murphy, Gian Pietro Picco
Reliable Communication For Highly Mobile Agents, Amy L. Murphy, Gian Pietro Picco
All Computer Science and Engineering Research
The provision of a reliable communication infrastructure for mobile agents is still an open research issue. The challenge to reliability we address in this work does not come from the possibility of faults, but rather from the mere presence of mobility, which slightly complicates the problem of ensuring the delivery of information even in a fault-free network. For instance, the asynchronous nature of message passing and agent migration may cause situations where messages forever chase a mobile agent that moves frequently from one host to another. Current solutions rely on conventional technologies that either do not provide a solution for …