<div> <div> <p>Due to the large volumes of spatial data, data is stored on clusters of machines that inter-communicate to achieve a task. In such distributed environment; communicating intermediate results among computing nodes dominates execution time. Communication overhead is even more dominant if processing is in memory. Moreover, the way spatial data is partitioned affects overall processing cost. Various partitioning strategies influence the size of the intermediate results. Spatial data poses the following additional challenges: 1)Storage load balancing because of the skewed distribution of spatial data over the underlying space, 2)Query load imbalance due to skewed query workload and query hotspots over both time and space, and 3)Lack of effective utilization of the computing resources. We introduce a new kNN query evaluation technique, termed BCDB, for evaluating nearest-neighbor queries (NN-queries, for short). In contrast to clustered partitioning of spatial data, BCDB explores the use of declustered partitioning of data to address data and query skew. BCDB uses summaries of the underling data and a coarse-grained index to localize processing of the NN-query on each local node as much as possible. The coarse-grained index is locally traversed using a new uncertain version of classical distance browsing resulting in minimal O( √k) elements to be communicated across all processing nodes.</p> </div> </div>

The increasing availability of Web services and grid computing has made easier the access and reuse of different types of services. Web services provide network accessible interfaces to application functionality in a platform-independent manner. Developments in grid computing have led to the efficient distribution of computing resources and power through the use of stateful web services. At the same time, mobile devices as a platform of computing have become a ubiquitous, inexpensive, and powerful computing resource. Concepts such as cloud computing has pushed the trend towards using grid concepts in the internet domain and are ideally suited for internet-supported mobile devices. Currently, there are a few complete implementations that leverage mobile devices as a member of a grid or virtual organization. This thesis presents a framework that enables the use of mobile devices to access stateful Web services on a Globus-based grid. To illustrate the presented framework, a user-friendly mobile application has been created that utilizes the framework libraries do to demonstrate the various functionalities that are accessible from any mobile device that supports Java ME. / by Jan Christian Mangs. / Thesis (M.S.C.S.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2008. Mode of access: World Wide Web.

Web services have become increasingly important over the past decades. Versatility and platform independence are just some of their advantages. On the other hand, grid computing enables the efficient distribution of computing resources. Together, they provide a great source of computing power that can be particularly leveraged by mobile devices. Mobile computing enables information creation, processing, storage and communication without location constraints [63], not only improving business' operational efficiency [63] but actually changing a way of life. However, the convenience of anytime and anywhere communication is counterbalanced by small screens, limited computing power and battery life. Despite these limitations, mobile devices can extend grid functionality by bringing to the mix not only mobile access but sensing capabilities as well, gathering information from their surroundings through built in mechanisms, such as microphone, camera, GPS and even accelerometers. Prior work has already demonstrated the possibility of enabling Web Services Resource Framework (WSRF) access to grid resources from mobile device clients in the WSRF-ME project [39], where a representative Nokia S60 Smartphone application was created on a framework, which extends the JSR-172 functionality to achieve WSRF compliance. In light of today's mobile phone market diversity, this thesis extends the solution proposed by WSRF-ME to non-Java ME phones and to Android devices in particular. Android-based device numbers have grown considerably over the past couple of years despite its recent creation and reduced availability of mature software tools. / Therefore, Android's web service capabilities are studied and the original framework is analyzed in order to propose a modified framework version that achieves and documents WSRF compliant communication form Android for the first time. As a case study, an illustrative mobile File Explorer application is developed to match the mod framework' functionality to the original WSRF-ME's use case. An additional case study, the LIGO Monitor application, shows the viability of mobile web services for monitoring purposes in the Laser Interferometer Gravitational Observatory (LIGO) grid environment for the first time. The context that an actual application implementation such as LIGO provides, allows some of the challenges of real mobile grid clients to surface. As a result, the observations made during this development give way to the drafting of a preliminary set of guidelines for Globus service implementation suitable for Android consumption that still remain open for proof in future works. / by Adriana Garcia-Kunzel. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

H.264/AVC encoder complexity is mainly due to variable size in Intra and Inter frames. This makes H.264/AVC very difficult to implement, especially for real time applications and mobile devices. The current technological challenge is to conserve the compression capacity and quality that H.264 offers but reduce the encoding time and, therefore, the processing complexity. This thesis applies machine learning technique for video encoding mode decisions and investigates ways to improve the process of generating more general low complexity H.264/AVC video encoders. The proposed H.264 encoding method decreases the complexity in the mode decision inside the Inter frames. Results show, at least, a 150% average reduction of complexity and, at most, 0.6 average increases in PSNR for different kinds of videos and formats. / by Paula Carrillo. / Thesis (M.S.C.S.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2008. Mode of access: World Wide Web.

Neste trabalho estudamos problemas relacionados com a busca de pontos e segmentos em janelas retangulares com os lados paralelos aos eixos. É dado um conjunto de segmentos (ou pontos) no plano. Em uma primeira fase estes segmentos são organizados em estruturas de dados de tal forma a tornar buscas por aqueles que estão contidos em janelas retangulares mais eficiente. Na segunda fase são dadas as janelas de maneira online. Várias destas estruturas de dados são baseadas em árvores balanceadas, tais como, árvore limite, árvore de busca com prioridade, árvore de intervalos e árvore de segmentos. Na dissertação mostramos detalhadamente estas estruturas de dados e os algoritmos para resolver este problema para conjuntos de pontos (versão unidimensional do problema) e para segmentos no plano, tanto horizontais e verticais como com qualquer orientação (sem cruzamentos). Os algoritmos são analisados de forma rigorosa quanto ao seu uso de espaço e de tempo. Implementamos também os vários algoritmos estudados, construindo uma biblioteca destas estruturas de dados. Apresentamos, finalmente os resultados de experimentos computacionais com instâncias do problema. / In this work we study problems about point and segment query in rectangular windows whose edges are parallel to the axis. Given a set of segments (or points) in the plane. In a first phase these segments are organized in data structures such that queries for segments in windows are done more efficiently. In the second phase windows are given online. The data structures are balanced trees as range tree, priority search tree, interval tree and segment tree. In this master\'s thesis we show in details data structures and algorithms for solving windowing queries to sets of points (unidimensional version of the problem) and of segments in the plane, as horizontal and vertical as any orientation (without crossings). The algorithms are analysed rigorously regarding their space and time used. We implement the algorithms studied, building a library of these data structures. Finally, we present, the results of computational experiments with instances of the problem.

Application performance continues to be an issue even with increased Internet bandwidth. There are many reasons for poor application performance including unpredictable network conditions, long round trip times, inadequate transmission mechanisms, or less than optimal application designs. In this work, we propose to exploit flow relationships as a general means to improve Internet application performance. We define a relationship to exist between two flows if the flows exhibit temporal proximity within the same scope, where a scope may either be between two hosts or between two clusters of hosts. Temporal proximity can either be in parallel or near-term sequential. As part of this work, we first observe that flow relationships are plentiful and they can be exploited to improve application performance. Second, we establish a framework on possible techniques to exploit flow relationships. In this framework, we summarize the improvements that can be brought by these techniques into several types and also use a taxonomy to break Internet applications into different categories based on their traffic characteristics and performance concerns. This approach allows us to investigate how a technique helps a group of applications rather than a particular one. Finally, we investigate several specific techniques under the framework and use them to illustrate how flow relationships are exploited to achieve a variety of improvements. We propose and evaluate a list of techniques including piggybacking related domain names, data piggybacking, enhanced TCP ACKs, packet aggregation, and critical packet piggybacking. We use them as examples to show how particular flow relationships can be used to improve applications in different ways such as reducing round trips, providing better quality of information, reducing the total number of packets, and avoiding timeouts. Results show that the technique of piggybacking related domain names can significantly reduce local cache misses and also reduce the same number of domain name messages. The data piggybacking technique can provide packet-efficient throughput in the reverse direction of a TCP connection without sacrificing forward throughput. The enhanced ACK approach provides more detailed and complete information about the state of the forward direction that could be used by a TCP implementation to obtain better throughput under different network conditions. Results for packet aggregation show only a marginal gain of packet savings due to the current traffic patterns. Finally, results for critical packet piggybacking demonstrate a big potential in using related flows to send duplicate copies to protect performance-critical packets from loss.

"Change is inevitable even for persistent information. Effectively managing change of persistent information, which includes the specification, execution and the maintenance of any derived information, is critical and must be addressed by all database systems. Today, for every data model there exists a well-defined set of change primitives that can alter both the structure (the schema) and the data. Several proposals also exist for incrementally propagating a primitive change to any derived information (or view). However, existing support is lacking in two ways. First, change primitives as presented in literature are very limiting in terms of their capabilities allowing users to simply add or remove schema elements. More complex types of changes such the merging or splitting of schema elements are not supported in a principled manner. Second, algorithms for maintaining derived information often do not account for the potential heterogeneity between the source and the target. The goal of this dissertation is to provide solutions that address these two key issues. The first part of this dissertation addresses the challenge of expressing a rich complex set of changes. We propose the SERF (Schema Evolution through an Extensible, Re-usable and Flexible) framework that allows users to perform a wide range of complex user-defined schema transformations. Our approach combines existing schema evolution primitives using OQL (object query language) as the glue logic. Within the context of this work, we look at the different domains in which SERF can be applied, including web site management. To further enrich our framework, we also investigate the optimization and verification of SERF transformations. The second part of this dissertation addresses the problem of maintaining views in the face of source changes when the source and the view are not in the same data model. With today's increasing heterogeneity in information structure, it is critical that maintenance of views addresses the data model boundaries. However, view definitions that go across data models are limited to hard-coded algorithms, thereby making it difficult to develop general maintenance algorithms. We provide a two-step solution for this problem. We have developed a cross algebra, that defines views such that there is no restriction that forces the view and the source data models to be the same. We then define update propagation algorithms that can propagate changes from source to target irrespective of the exact translation and the data models. We validate our ideas by applying them to translation and change propagation between the XML and relational data models."

<p>Ova doktorska teza se bavi proučavanjem i razvojem paralelnih<br />algoritama za transponovanje distribuiranih trodimenzionalnih<br />struktura podataka, kao i implementacijom ovih algoritama u okviru<br />C/OpenMP/MPI programske paradigme. Razvijena implementacija je<br />primenjena na rešavanje nelinearne parcijalne diferencijealne<br />jednačine Šredingerovog tipa (Gros-Pitaevski jednačina) korišćenjem<br />Krenk-Nikolson metoda, a u okviru teze je predstavljen ciklus razvoja<br />odgovarajućeg softvera, kao i rezultati testova validnosti i merenja<br />performansi dobijenih na računarskom klasteru.</p> / <p>This thesis studies and develops parallel algorithms for transposing<br />distributed three-dimensional data structures, and describes their technical<br />implementation in C/OpenMP/MPI programing paradigm. The developed<br />implementation is applied for solving of nonlinear partial differential equation<br />of the Schroedinger type (Gross-Pitaevskii equation) using Crank-Nicolson<br />method. The thesis presents the corresponding software development cycle,<br />as well as results of validity tests and performance measurements obtained<br />on a computer cluster.</p>

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Vita. / Bibliography: leaves 98-102. / by Brad Allen Myers. / M.S.

Abstract not available