Distributed System

Distributed Systems Course Project: Consensus with Failure Detector

by Mattia Avancini

CORBA, DCOM E JAVARMI - Uma Análise Comparativa

by Vitor Roque

ROQUE, Vitor Manuel Gomes ;  OLIVEIRA, José Luís  - CORBA, DCOM E JAVARMI - UMA ANÁLISE COMPARATIVA . Ingenium . , vol. , n.º 46  (Mar. 2000) . p. 87-91. Portuguese text.

Muliware database: A distributed object database system for multimedia support

by Ivan Ricarte

Co-authored with Carlos Tobar. Published in ICODP'1995.

This paper describes the Multiware Database, a database capable to store and manage complex multimedia documents using... more This paper describes the Multiware Database, a database capable to store and manage complex multimedia documents using the features of both object management systems and open distributed systems.

Towards an architecture for distributed multimedia databases

by Ivan Ricarte

Co-authored with Carlos Tobar. Published in ICIIS'1996.

The widespread use of multimedia resources has been demanding the reengineering of a broad class of supporting... more The widespread use of multimedia resources has been demanding the reengineering of a broad class of supporting software in order to ease the implementation of multimedia applications. In this paper, we address the features a database system should provide in order to support multimedia applications, with emphasis on its integration to distributed platforms. The architecture of a prototype multimedia database, the Multiware Database, is presented.

Working with Remote VRML Scenes through Low-Bandwidth Connections

by Ivan Ricarte

Co-authored with Alberto Raposo and Léo Magalhães. Published in SIBGRAPI 1997.

We have developed a Web-based application to accelerate the visualization of VRML scenes located in a remote server.... more We have developed a Web-based application to accelerate the visualization of VRML scenes located in a remote server. This application enables the user to extract only the parts of a scene that are of actual interest. The extracted parts represent one or more sub-trees of the hierarchical structure of the VRML scene, and only these parts will be rendered and visualized in the local computer. By reducing the complexity (size) of the remote scene, less data are transmitted from the remote server and the rendering process becomes faster in the local computer. The application is written in Java and is executed as an applet embedded in an HTML page.

SGPOM: A multimedia object persistence management service under a distributed environment

by Ivan Ricarte

Co-authored with Andre LV Coelho. SBMEDIA 2000.

This paper presents a well-dimensioned distributed framework for supporting persistent multimedia data management. This paper presents a well-dimensioned distributed framework for supporting persistent multimedia data management.

Distributed multimedia persistence support for educational activities

by Ivan Ricarte

Co-authored with André Coelho. Published in SCI'2000.

Under most of the new technological-focusing learning approaches, one of the primal objectives is that of the... more Under most of the new technological-focusing learning approaches, one of the primal objectives is that of the incremental design and construction of an instructional environment more centered upon the learners’ particular necessities and profiles. In such respect, multimedia tools and services have already been proposed and customized as the underpinnings to a broader range of more adequate educational and training software applications. In order to augment and extend this support over larger domains, there is now such a tendency to integrate these mechanisms with those obtained within the Distributed Systems arena. In this paper, a distributed multimedia persistence layer, which enables the seamless integration of multimedia databases with media dedicated storage servers, is evaluated as such an underlying service bringing support to customary educational activities. With this purpose, some computational requirements commonly associated with the handling of learning materials are first presented, assessing their impact on the assisting middleware systems. Finally, three scenarios of study are investigated emphasizing the new service functionalities.

A CORBA-based distributed multimedia database management layer: design and implementation aspects

by Ivan Ricarte

Co-authored with Andre L V Coelho. Published in Intern. Symp. on Computers and Communications, 2000

Multimedia applications executing on distributed environments lack a seamless approach to handle their components'... more Multimedia applications executing on distributed environments lack a seamless approach to handle their components' persistent contents. A persistence middleware layer that allows the integration of multimedia databases with media-dedicated storage servers is presented. The design of SGPOM follows the philosophy of RM-ODP and CORBA persistent object service, thus enabling a clean integration with this distributed object platform. The main aspects related to the service implementation using the Java programming language are also described.

Benchmarking Issues of a Distributed Multimedia Database Management Service

by Ivan Ricarte

Co-authored with Andre L V Coelho. Published in Managing QoS in Multimedia Networks and Services, 2000

One of the most compelling yet still not properly accomplished tasks inside the distributed multimedia database arena... more One of the most compelling yet still not properly accomplished tasks inside the distributed multimedia database arena is that of suitably fulfilling the disparate temporal requirements commonly imposed by the different types of persistent multimedia information. In such regard, an object-based multimedia management layer has already been conceived and implemented as a CORBA service towards the seamless integration of multimedia databases with net-hidden media dedicated storage repositories. The goal of this paper is to present some quantitative results obtained through measurement sessions over a developed prototype of this distributed service in order to qualitatively assess the adequacy of its architectural proposal.

Approximation Algorithms for Determining Placement of Intrusion Detectors in a Distributed System

by Gaspar Modelo-Howard

The turning of the tide: Rethinking language, mind and world

by Dongping Zheng

Cowley, S. & Zheng, D. (2011). The turning of the tide: Rethinking language, mind and world [Review article of Linell, P. (2009), Rethinking language, mind, and world dialogically: Interactional and contextual theories of human sense-making]. Journal of Multicultural Discourses, 6(02), 197-210.

Cognitive and generative linguistics may lie at the high water mark of a tradition. They are the culmination of a... more Cognitive and generative linguistics may lie at the high water mark of a tradition. They are the culmination of a train of linguistic thought that arose in ancient Greece
when language was reduced to parts that could be analysed as constructions, words, propositions, and/or meanings. Human agents came to be seen as being caused to say
things about the world in which they live. The environment was separated from the mind or body which, in this tradition, became the ‘‘seat’’ of language (and languageuse).
Of course, such theories appear in many guises. For example, while generativists take a Cartesian view that separates a mind/brain from what is external, cognitive
linguists often follow Hume in placing a human body in an environment. In spite of their differences, however, the views are united in their individualism.Rethinking language, mind, and world dialogically (hereafter Rethinking) provides
an alternative to all such traditions. By taking an ecological approach, Per Linell provides a platform that offers much to both theorists and language teachers. His
general thesis is that dialogue can be used as the basis for reshaping the human sciences. By setting out this goal, Rethinking connects philosophy with empirical
studies in the social, cognitive, and behavioural sciences. Traditional focus on discourse, words, and grammar or what we dub yang linguistics can now be balanced
by their yin counterpart.1 This is needed, Linell argues, because sense-making prompts dialogue, mind, and selves to arise from social and collective living. As we act, feel, and think dialogically, sociodialogue constrains what we can (and
cannot) do. In terms of Sun Wu’s Strategies of Defence, our foe is neither Cartesian nor Humean traditions but, rather, how experience of literacy and silent thinking tempts us to ascribe minds to individual brains. Given what Linell (2005) calls written
language bias, these become stores of determinate items that constitute languagesystems. In the yang linguistics tradition, an individual (or mind/brain) is said to ‘‘possess’’ language. The dialogical perspective shows how turning to yin allows us to
avoid such metaphors. Rather, the focus turns to a ‘‘meta-theoretical framework’’ (22) in which we acknowledge the never-ending process of human becoming.

Energy-Aware Scheduling of Distributed Systems Using Cellular Automata

by Shrisha Rao

6th Annual IEEE International Systems Conference (IEEE SysCon 2012), Vancouver, Canada, March 2012.

In today’s world of large distributed systems, the need for energy efficiency of individual components is comple-... more In today’s world of large distributed systems, the need for energy efficiency of individual components is comple- mented by the need for energy awareness of the complete system. Hence, energy-aware scheduling of tasks on systems has become very important. Our work addresses the problem of finding an energy-aware schedule for a given system which also satisfies the precedence constraints between tasks to be performed by the system. We present a method which uses cellular automata to find a near-optimal schedule for the system. The rules for cellular automata are learned using a genetic algorithm. Though the work presented in this paper is not limited to scheduling in computing environments only, the work is validated with a sample simulation on distributed computing systems, and tested with some standard program graphs.

Distributed Cooperation in Wireless Sensor Networks

by Mihail Mihaylov

M. Mihaylov, Y.-A. Le Borgne, K. Tuyls, and A. Nowé, "Distributed Cooperation in Wireless Sensor Networks," in Proc. Proceedings of the 10th International Conference on Autonomous Agents and Multiagent Systems (AAMAS 2011), Taipei, Taiwan, 2011.

We present a game-theoretic self-organizing approach for scheduling the radio activity of wireless sensor nodes. Our... more We present a game-theoretic self-organizing approach for scheduling the radio activity of wireless sensor nodes. Our approach makes each node play a win-stay lose-shift (WSLS) strategy to choose when to schedule radio transmission, reception and sleeping periods. The proposed strategy relies only on local interactions with neighboring nodes, and is thus fully decentralized. This behavior results in shorter communication schedules, allowing to not only reduce energy consumption by reducing the wake-up cycles of sensor nodes, but also to decrease the data retrieval latency. We implement this WSLS approach in the OMNET++ sensor network simulator where nodes are organised in three topologies: line, grid and random. We compare the performance of our approach to two state-of-the-art scheduling protocols, namely S-MAC and D-MAC, and show that the WSLS strat- egy brings signifficant gains in terms of energy savings, while at the same time reduces communication delays. In addi- tion, we show that our approach performs particularly well in large, random topologies.

A New Approach to Power System Protection in Distribution Network with DG Units by Using Radial Basis Function Neural Network

by Hadi Zayandehroodi هادی زاینده رودی

International Journal of Engineering Intelligent Systems, Vol:19, Issue 2, pp. 1-15.

The presence of distributed generation (DG) units in a distribution system will greatly affect the configuration and... more The presence of distributed generation (DG) units in a distribution system will greatly affect the configuration and operation mode of the power system, especially with respect to the protection scheme. This paper presents a new approach to power system protection using radial basis function neural network (RBFNN) for a distribution system with DG units. In the proposed method, the fault type is determined first by normalizing the fault currents of the main source. For implementing fault location considering various types of faults, two staged RBFNNs have been developed. The first RBFNN is used for determining the fault distance from each power source and the second RBFNN is used for identifying the faulty line. To isolate the fault another RBFNN has been developed for determining which circuit breakers (CBs) that must be open or close. Several case studies have been made to verify the accuracy of the proposed method for fault diagnosis in a distribution system with DGs using aMATLAB based developed software and DIgSILENT Power Factory 14.0.524. The predicted results showed that the proposed RBFNN based protection method can accurately determine the location of faults and isolate the faulted line in the test power system.

Distributed Broadcast Minimum Spanning Tree (reliable version)

by Mohammad Kajbaf

CLINICAL SURFACES – Activity-Based Computing for Distributed Multi-Display Environments in Hospitals

by Afsaneh Doryab

A multi-display environment (MDE) is made up of co-located and networked personal and public devices that form an... more A multi-display environment (MDE) is made up of co-located and networked personal and public devices that form an integrated workspace enabling co-located group work. Traditionally, MDEs have, however, mainly been designed to support a single “smart room”, and have had little sense of the tasks and activities that the MDE is being used for. This paper presents a novel approach to support activity-based computing in distributed MDEs, where displays are physically distributed across a large building. CLINICAL SURFACES was designed for clinical work in hospitals, and enables context-sensitive  retrieval and browsing of patient data on public displays. We present the design and implementation of CLINICAL SURFACES, and report from an evaluation of the system at a large hospital. The evaluation shows that using distributed public displays to support activity-based computing inside a hospital is very useful for clinical work, and that the apparent contradiction between maintaining privacy of medical data in a public display environment can be mitigated by the use of CLINICAL SURFACES.

Relationships in the distribution channel of tourism: Conflicts between hoteliers and tour operators in the Mediterranean region,

by Professor Dimitrios Buhalis

Buhalis, D., 2000, Relationships in the distribution channel of tourism: Conflicts between hoteliers and tour... more Buhalis, D., 2000, Relationships in the distribution channel of tourism: Conflicts between hoteliers and tour operators in the Mediterranean region, International Hospitality, Leisure and Tourism Administration Journal, Vol.1(1) pp.113-139

Processing Large Data Sets using a Cluster Computing Framework

by Imran Sarwar Bajwa

Australian Journal of Basic and Applied Science, 5(6) pp:1614-1618

Increase in the scientific disciplines has caused large data collections as important community resources. The volume... more Increase in the scientific disciplines has caused large data collections as important community resources. The volume of interesting data is already measured in terabytes and will soon total in peta-bytes. This research proposal presents the issue of processing massive amount of satellite data. A single LEO satellite sends around 2 GB of data in 24 hours of a day. To process this huge amount of data, normal digital computers face constraints like processing time, recourses and cost. A solution is needed that can provide quick way of processing at low cost. Cluster computing is network based distributed environment that can be a solution for fast processing support for huge sized jobs. A middle-ware is typically required in cluster computing. In this proposal a middle-ware is proposed for handling the existing processing problems in distributed environments. In a typical heterogeneous computation, a middleware can be employed to provide incorporation and interoperability in the underlying applications and services.

Sensor Network Design for Smart Highways

by Shrisha Rao

Co-authored with Shyamakshi Ghosh and Balkrishnan Venkiteswaran. This paper is to appear in the IEEE Transactions on Systems, Man, and Cybernetics - Part A: Systems and Humans. A prior version appeared as doi:10.1109/COASE.2009.5234136 in the 5th Annual IEEE Conference on Automation Science and Engineering (IEEE CASE 2009), Bangalore, India, August 2009, pp. 353--360.

A unique and efficient system model is proposed for sensor networks to create sensor-smart highways. Our approach... more A unique and efficient system model is proposed for sensor networks to create sensor-smart highways. Our approach first considers various cell geometries encountered with two-dimensional roads, and then extends the same to three-dimensional roads. The mathematical relations describing each type of cell are derived, and the analyses indicate the numbers and positions of sensor nodes needed in each cell of a certain type. We then propose algorithms for computing the deployment positions of sensor nodes on roads by describing them as consisting of cells of different geometries. We also validate the approach by computing a sensor deployment using real geospatial data.

A Foundation of Demand-Side Resource Management in Distributed Systems

by Shrisha Rao

Transactions on Computational Science VIII, LNCS 6260, 2010, Springer, Heidelberg, pp. 114–126. doi:10.1007/978-3-642-16236-7_8.

The theoretical problems of demand-side management are examined in without regard to the type of resource whose demand... more The theoretical problems of demand-side management are examined in without regard to the type of resource whose demand is to be managed, and the Maximum Demand problem is identified and addressed in a system consisting of independent processes that consume the resource. It is shown that the Maximum Demand problem generalizes the Santa Fe Bar Problem of game theory, and the basic properties of Maintenance and Strong and Weak Recovery that are desirable of systems of processes where demand management is practiced are defined. Basic algorithms are given for solving the Maximum Demand problem in a general context, and in a system where the processes have priorities.