Institute for Systems Research Technical Reports
Permanent URI for this collectionhttp://hdl.handle.net/1903/4376
This archive contains a collection of reports generated by the faculty and students of the Institute for Systems Research (ISR), a permanent, interdisciplinary research unit in the A. James Clark School of Engineering at the University of Maryland. ISR-based projects are conducted through partnerships with industry and government, bringing together faculty and students from multiple academic departments and colleges across the university.
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Item An Object-Oriented Programming Approach to Implement Global Spectral Methods: Application to Dynamic Simulation of a Chemical Infiltration Process(2000) Huang, Jiefei; Adomaitis, Raymond A.; ISRBoundary-value problems (BVPs) in relatively simple geometriescan be solved using global spectral methods. These discretizationmethods are applicable to a wide range of problems and are suitablefor a "rapid prototyping" approach to simulator development forcomplex systems.Object-Oriented Programming techniques for solvingBVPs are introduced in this work. Object classes are created toencapsulate trial function sequences, discretized differential andquadrature operators, and other data structures used for spectraldiscretization and projection operations. Operator/functionoverloading subsequently is used to numerically implement theGalerkin projection method. Emphasis is placed on developingnumerical methods suitable for discretizing 2- and 3-dimensionalproblems, integrating the resulting ODE/AE systems in time, andreconstructing the solutions in the physical space. A detailed model of anisothermal carbon-carbon chemical vapor infiltration (CVI) systemwas studied as a true test of the ability of the numerical methods.
Item REU Report: Designing a Universal Robotics Platform(1999) Wojtkowski, Stephanie; Krishnaprasad, P.S.; ISRIn this paper, I describe Motion Description Language extended (MDLe), a computer platform designed to communicate with any robot. This platform will integrate the hierarchical ease of behavior-based programming and the mathematics of control theory. The path of a robot is broken down into smaller and smaller pieces, from plans to behaviors to atoms to controls, until it can finally be described by the speeds of the two wheels. A planner will later be added to perform path planning. All possible paths will be calculated using control theory, then some will be ruled out due to the non-holonomic constraint. The rest will then be considered to find the optimum path to complete the task. The ultimate goal of this research is to create a system that can autonomously navigate the robot through unfamiliar surroundings.Item Temporal Databases in Network Management(1998) Gupta, Ajay; Baras, John S.; ISR; CSHCNComputer networks are becoming a crucial part of a business' lifeline,therefore, managing these networks, and ensuring they remain operational, is an increasingly important task. This thesis discusses issues involvedwith performing network management, specifically with means of reducing and storing the large quantity of data that networks management tools and systems generate.The value of the network management data collected diminishes as the data ages. The value that remains is in the trend that the data outlinesof the macroscopic behavior of the network. This thesis proposes an algorithm which highlight these trends and, in the process, causes a significant data reduction. The proposed algorithm's reductionmethodology is compared with standard data reduction techniques. It isfurther shown that the processed data is suited for storage in a temporaldatabase. The benefits of storing time series data, such as the networkmanagement data discussed (i.e., Link Utilization, CPU Load, and DeviceReachability), in a temporal database is demonstrated by storing the data in both a rational Oracle 7 and a temporal TIGER database, and examining results of queries against both databases.
Item Wireless Services for Telemedicine via AIN(1998) Bisain, Abhijeet S.; Baras, John S.; ISR; CSHCNThis thesis proposes an architecture for wireless services in telemedicine.The scenario visualized is of an ambulance carrying a traumapatient and sending medical data (video, ultrasound, ECG) to itscorresponding hospital. It needs to know in advance the approximatebandwidth available to it after every handoff.This thesis attempts to solve this problem with Intelligent Network signalling which aids fast implementation of new services. It isassumed that the ambulance uses a TDMA(GSM/PACS) based phone with multiple slotconnection capability. New signalling procedures are suggested whichattempt to provide this service with minimum delay and load.Some slot allocation schemes implemented at the base stations aredesigned and evaluated. Buffer management schemesat the mobile to manage packets from various data streams are proposed andcompared. All queuing systems are simulated in Opnet.Item AVIS: An Advanced Video Information System(1997) Adali, Sibel; Candan, K. Selcuk; Erol, Kutluhan; Subrahmanian, V.S.; ISRDuring the last few years, the advent of the CD-Rom, and the introduction of high bandwidth communications networks has caused a spectacular explosion in the availability of large video- libraries. While a great deal of effort has been invested in problems of how to effectively utilize bandwidth to communicate large bodies of data across the network, relatively little effort has gone into how to organize, and access, video databases. In this paper, we describe how video data may be organized and structured so as to facilitate queries. We develop a formal model of video data and show how spatial data structures, suitably modified, provide an elegant way of storing such data. We develop algorithms to process various kinds of video queries and show that in most cases, the complexity of these algorithms is linear. We develop algorithms to update these video databases. A prototype system called AVIS ("Advanced Video Information System") has been designed at the University of Maryland based on these concepts.Item Integration of a Manufacturing Resource Planning System with a Manufacturing Information Repository(1996) Rush, D.W.; Harhalakis, G.; Minis, I.; ISRThis work employs a Systems Engineering approach to integrate two heterogeneous databases systems in a chemical manufacturing facility. The first system is a Manufacturing Resource Planning system (MRPII) which supports production planning and control. The second system is a Manufacturing Information Repository (MIR) that manages and stores information concerning processes, equipment and materials. Phase I of this project compared the data structures of the two systems for common data fields. With very little commonality found, Phase II focused on the interrelationships and intra relationships of the data structures of the two systems and yielded the following results: 1) Detailed data models of the two systems that showed the MIR system to be hierarchical and the MRPII system to be relational; 2) A set of mapping conventions between the corresponding data fields of the two systems; 3) An algorithm and a computer program to upload information from the MIR to the MRPII system. To demonstrate the computer program, a case study was performed using sample MIR data.Item A Planning Approach to Declarer Play in Contract Bridge(1995) Smith, S.J.J.; Nau, D.S.; Throop, T.A.; ISRAlthough game-tree search works well in perfect-information games, it is less suitable for imperfect-information games such as contract bridge. The lack of knowledge about the opponents' possible moves gives the game tree a very large branching factor, making it impossible to search a significant portion of this tree in a reasonable amount of time.This paper describes our approach for overcoming this problem. We represent information about bridge in a task network that is extended to represent multi-agency and uncertainty. Our game-playing procedure uses this task network to generate game trees in which the set of alternative choices is determined not by the set of possible actions, but by the set of available tactical and strategic schemes.
We have tested this approach on declarer play in the game of bridge, in an implementation called Tignum 2. On 5,000 randomly generated no-trump deals, Tignum 2 beat the strongest commercially available program by 1394 to 1302, with 2304 ties. These results are statistically significant at the a = 0.05 level. Tignum 2 searched an average of only 8745.6 moves per deal in an average time of only 27.5 seconds per deal on a Sun SPARCstation 10. Further enhancements to Tignum 2 are currently underway.
Item Similarity Searching in Large Image DataBases(1994) Petrakis, E.G.M.; Faloutsos, Christos; ISRWe propose a method to handle approximate searching by image content in large image databases. Image content is represented by attributed relational graphs holding features of objects and relationships between objects. The method relies on the assumption that a fixed number of ﲬabeled or ﲥxpected objects (e.g. ﲨeart lungs etc.) are common in all images of a given application domain in addition to a variable number of ﲵnexpected or ﲵnlabeled objects (e.g. ﲴumor , hematoma etc.). The method can answer queries by example such as ﲦind all X-rays that are similar to Smith's X-ray . The stored images are mapped to points in a multidimentional space ad are indexed using state- of-the-art database methods (R-trees). The proposed method has several desirable desirable properties: (a) Database search is approximate so that all images up to a pre-specified degree of similarity (tolerance) are retrieved, (b) it has no ﲦalse dismissals (i.e., all images qualifying query selection criteria are retrieved) and (c) it scales-up well as the database grows. We implemented the method and ran experiments on a database of synthetic (but realistic) medical images. The experiments showed that our method significantly outperforms sequential scanning by up to an order of magnitude.Item The TV-tree -- an Index Structure for High-Dimensional Data(1994) Lin, King-Ip D.; Jagadish, H.V.; Faloutsos, Christos; ISRWe propose a file structure to index high-dimensionality data, typically, points in some feature space. The idea is to use only a few of the features, utilizing additional features whenever the additional discriminatory power is absolutely necessary. We present in detail the design of our tree structure and the associated algorithms that handle such 'varying length' feature vectors. Finally we report simulation results, comparing the proposed structure with the R*-tree, which is one of the most successful methods for low-dimensionality spaces. The results illustrate the superiority of our method, with up to 80% savings in disk accesses.Item Declustering R-Tree on Multi-Computer Architectures(1994) Koudas, N.; Faloutsos, Christos; Kamel, Ibrahim; ISRWe study a method to decluster a spatial access method (and specifically an R-tree) on a shared-nothing multi-computer architecture [9]. Our first step is to propose a software architecture, with the top levels of the R-tree on the 'master'server' and the leaf nodes distributed across the servers. Nest, we study the optimal capacity of leaf nodes, or 'chunk size'. We express the response time on range queries as a function of the 'chunk size', and we show how to optimize it. This formula assumes that the 'chunks' are perfectly declustered. We propose to use the Hilbert curve to achieve such a good declustering.Finally, we implemented our method on a network of workstations and we compared the experimental and the theoretical results. The conclusions are that (a) our formula for the response time is accurate (the maximum relative error was 30%; the typical error was in the vicinity of 10-15%) (b) the Hilbert-based declustering consistently outperforms a random declustering (c) most importantly, although the optimal chunk size depends on several factors (database size, size of the query, speed of the network), a safe choice for it is 1 page (whichever is the page size of the operating system). We show analytically and experimentally that a chunk size of 1 page gives either optimal or close to optimal results, for a wide range of the parameters.
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