DSpace at MIT
(35.359 recursos)
This site is a university repository providing access to the publication output of the institution. Registered users can set up email alerts to notify them of newly added relevant content. A certain level of encryption and security is embedded in the site which may cause some users accessibility problems.
Mostrando recursos 1 - 20 de 107
1.
Bit-Packing Optimization for StreamIt - Agrawal, Kunal; Amarasinghe, Saman P.; Wong, Weng Fai
StreamIt is a language specifically designed for modern streaming applications. A certain important class of these applications operates on streams of bits. This paper presents the motivation for a bit-packing optimization to be implemented in the StreamIt compiler for the RAW Architecture. This technique aims to pack bits into integers so that operations can be performed on multiple bits at once thus increasing the performance of these applications considerably. This paper gives some simple example applications to illustrate the various conditions where this technique can be applied and also analyses some of its limitations.
2.
Credible Compilation * - Rinard, Martin C.
This paper presents an approach to compiler correctness in which the compiler generates a proof that the transformed program correctly implements the input program. A simple proof checker can then verify that the program was compiled correctly. We call a compiler that produces such proofs a credible compiler, because it produces verifiable evidence that it is operating correctly.
3.
On the Detection of Retinal Vessels in Fundus Images - Fang, Bin; Hsu, Wynne; Lee, Mong Li
Ocular fundus image can provide information on pathological changes caused by local ocular diseases and early signs of certain systemic diseases. Automated analysis and interpretation of fundus images has become a necessary and important diagnostic procedure in ophthalmology. Among the features in ocular fundus image are the optic disc, fovea (central vision area), lesions, and retinal vessels. These features are useful in revealing the states of diseases in the form of measurable abnormalities such as length of diameter, change in color, and degree of tortuosity in the vessels. In addition, retinal vessels can also serve as landmarks for image-guided laser...
4.
Discovering Network Neighborhoods Using Peer-to-Peer Lookups - Lehman, Li-wei; Lerman, Steven
In many distributed applications, end hosts need to know the network locations of other nearby participating hosts in order to enhance overall performance. Potential applications that can benefit from the location information include automatic selection of nearby Web servers, proximity routing in a peer-to-peer system, and loss recovery in reliable multicasting. We focus in this paper on the network neighborhood discovery problem in large-scale distributed systems. In these systems, the number of participating nodes can be very large, and the membership can dynamically change. Our goal is for each node to discover other "nearby" participating nodes in a completely decentralized...
5.
A Dynamically Partitionable Compressed Cache - Chen, David; Peserico, Enoch; Rudolph, Larry
The effective size of an L2 cache can be increased by using a dictionary-based compression scheme. Naive application of this idea performs poorly since the data values in a cache greatly vary in their â??compressibility.â?? The novelty of this paper is a scheme that dynamically partitions the cache into sections of different compressibilities. While compression is often researched in the context of a large stream, in this work it is applied repeatedly on smaller cache-line sized blocks so as to preserve the random access requirement of a cache. When a cache-line is brought into the L2 cache or the cache-line...
6.
Encryption Key Search using Java-based ALiCE Grid - Virkar, Ameya
Encryption Key Search is a compute-intensive operation that consists of a brute-force search of a particular key in a given key space. Sequential execution time for a 56-bit encryption key search is approximately 200,000 years and therefore it is ideal to execute such operation in a grid environment. ALiCE (Adaptive and scaLable internet-based Computing Engine) is a grid middleware that offers a portable software technology for developing and deploying grid applications and systems. This paper discusses the development of the Encryption Key Search application on ALiCE and also presents the performance evaluation of ALiCE using this application.
7.
Global Comparison Aggregation Services - Zhu, Hongwei; Madnick, Stuart E.; Siegel, Michael D.
Web aggregation has been available regionally for several years, but this service has not been offered globally. As an example, using multiple regional comparison aggregators, we analyze the global prices for a Sony camcorder, which differ by more than three times. We further explain that lack of global comparison aggregation services partially contribute to such huge price dispersion. We also discuss difficulties encountered in the manual integration of global web sources. Motivated by this example, we propose a context mediation architecture for global aggregation to address semantic disparities of global information sources. Global aggregation services can bring efficiency to the...
8.
Financial Information Integration In the Presence of Equational Ontological Conflicts - Firat, Aykut; Madnick, Stuart E.; Grosof, Benjamin
While there are efforts to establish a single international accounting standard, there are strong current and future needs to handle heterogeneous accounting methods and systems. We advocate a context-based approach to dealing with multiple accounting standards and equational ontological conflicts. In this paper we first define what we mean by equational ontological conflicts and then describe a new approach, using Constraint Logic Programming and abductive reasoning, to reconcile such conflicts among disparate information systems. In particular, we focus on the use of Constraint Handling Rules as a simultaneous symbolic equation solver, which is a powerful way to combine, invert and...
9.
Hierarchical Multi-Bottleneck Classification Method And Its Application to DNA Microarray Expression Data - Xiong, Xuejian; Wong, Weng Fai; Hsu, Wen Jing
The recent development of DNA microarray technology is creating a wealth of gene expression data. Typically these datasets have high dimensionality and a lot of varieties. Analysis of DNA microarray expression data is a fast growing research area that interfaces various disciplines such as biology, biochemistry, computer science and statistics. It is concluded that clustering and classification techniques can be successfully employed to group genes based on the similarity of their expression patterns. In this paper, a hierarchical multi-bottleneck classification method is proposed, and it is applied to classify a publicly available gene microarray expression data of budding yeast Saccharomyces...
10.
The Interplay of Web Aggregation and Regulation - Zhu, Hongwei; Madnick, Stuart E.; Siegel, Michael D.
The development of web technology has led to the emergence of web aggregation, a service that collects existing web data and turns them into more useful information. We review the development of both comparison and relationship aggregation and discuss their impacts on various stakeholders. The aggregatorâ??s capability of transparently extracting web data has raised challenging issues in database and privacy protection. Consequently, new regulations are introduced or being proposed. We analyze the interactions between aggregation and related policies and provide our insights about the implications of new policies on the development of web aggregation.
11.
Knowledge Integration to Overcome Ontological Heterogeneity: Challenges from Financial Information Systems - Firat, Aykut; Madnick, Stuart E.; Grosof, Benjamin
The shift towards global networking brings with it many opportunities and challenges. In this paper, we discuss key technologies in achieving global semantic interoperability among heterogeneous information systems, including both traditional and web data sources. In particular, we focus on the importance of this capability and technologies we have designed to overcome ontological heterogeneity, a common type of disparity in financial information systems. Our approach to representing and reasoning with ontological heterogeneities in data sources is an extension of the Context Interchange (COIN) framework, a mediator-based approach for achieving semantic interoperability among heterogeneous sources and receivers. We also analyze the...
13.
Solving a Class of Higher-Order Equations over a Group Structure - Andrei, Å?tefan; Chin, Wei Ngan
In recent years, symbolic and constraint-solving techniques have been making major advances and are continually being deployed in new business and engineering applications. A major push behind this trend has been the development and deployment of sophisticated methods that are able to comprehend and evaluate important sub-classes of symbolic problems (such as those in polynomial, linear inequality and finite domains). However, relatively little has been explored in higher-order domains, such as equations with unknown functions. This paper proposes a new symbolic method for solving a class of higher-order equations with an unknown function over the complex domain. Our method exploits...
14.
Learning object boundary detection from motion data - Ross, Michael G.; Kaelbling, Leslie P.
A significant barrier to applying the techniques of machine learning to the domain of object boundary detection is the need to obtain a large database of correctly labeled examples. Inspired by developmental psychology, this paper proposes that boundary detection can be learned from the output of a motion tracking algorithm that separates moving objects from their static surroundings. Motion segmentation solves the database problem by providing cheap, unlimited, labeled training data. A probabilistic model of the textural and shape properties of object boundaries can be trained from this data and then used to efficiently detect boundaries in novel images via...
15.
MATLAB*P 2.0: A unified parallel MATLAB - Choy, Ron; Edelman, Alan
MATLAB is one of the most widely used mathematical computing environments in technical computing. It is an interactive environment that provides high performance computational routines and an easy-to-use, C-like scripting language. Mathworks, the company that develops MATLAB, currently does not provide a version of MATLAB that can utilize parallel computing. This has led to academic and commercial efforts outside Mathworks to build a parallel MATLAB, using a variety of approaches. In a survey, 26 parallel MATLAB projects utilizing four different approaches have been identified. MATLAB*P is one of the 26 projects. It makes use of the backend support approach. This...
16.
Playing is believing: the role of beliefs in multi-agent learning - Chang, Yu-Han; Kaelbling, Leslie P.
We propose a new classification for multi-agent learning algorithms, with each league of players characterized by both their possible strategies and possible beliefs. Using this classification, we review the optimality of existing algorithms and discuss some insights that can be gained. We propose an incremental improvement to the existing algorithms that seems to achieve average payoffs that are at least the Nash equilibrium payoffs in the long-run against fair opponents.
17.
Real-time Mosaic for Multi-Camera Videoconferencing - Klechenov, Anton; Gupta, Aditya Kumar; Wong, Weng Fai; Ng, Teck Khim; Leow, Wee Kheng
This paper describes a system for high resolution video conferencing. A number of camcorders are used to capture the video, which are then mosaiced to generate a wide angle panoramic view. Furthermore this system is made â??real-timeâ?? by detecting changes and updating them on the mosaic. This system can be deployed on a single machine or on a cluster for better performance. It is also scalable and shows a good real-time performance. The main application for this system is videoconferencing for distance learning but it can be used for any high resolution broadcasting.
18.
StreamIt: A Language and Compiler for Communication-Exposed Architectures - Thies, William; Gordon, Michael I.; Karczmarek, Michal; Maze, David; Amarasinghe, Saman P.
With the increasing miniaturization of transistors, wire delays are becoming a dominant factor in microprocessor performance. To address this issue, a number of emerging architectures contain replicated processing units with software-exposed communication between one unit and another (e.g., Raw, SmartMemories, TRIPS). However, for their use to be widespread, it will be necesary to develop a common machine language to allow programmers to express an algorithm in a way that can be efficiently mapped across these architectures. We propose a new common machine language for grid-based software-exposed architectures: StreamIt. StreamIt is a high-level programming language with explicit support for streaming computation....
19.
Towards An Automated Approach to Hardware/Software Decomposition - Qin, Shengchao; He, Jifeng; Chin, Wei Ngan
We propose in this paper an algebraic approach to hard-ware/software partitioning in Verilog Hardware Description Language (HDL). We explore a collection of algebraic laws for Verilog programs, from which we design a set of syntax-based algebraic rules to conduct hardware/software partitioning. The co-specification language and the target hardware and software description languages are specific subsets of Verilog. Through this, we confirm successful verification for the correctness of the partitioning process by an algebra of Verilog. Facilitated by Verilogâ??s rich features, we have also successfully studied hw/sw partitioning for environment-driven systems.
20.
Transactions Everywhere - Kuszmaul, Bradley C.; Leiserson, Charles E.
Arguably, one of the biggest deterrants for software developers who might otherwise choose to write parallel code is that parallelism makes their lives more complicated. Perhaps the most basic problem inherent in the coordination of concurrent tasks is the enforcing of atomicity so that the partial results of one task do not inadvertently corrupt another task. Atomicity is typically enforced through locking protocols, but these protocols can introduce other complications, such as deadlock, unless restrictive methodologies in their use are adopted. We have recently begun a research project focusing on transactional memory [18] as an alternative mechanism for enforcing atomicity,...
1.
