Search results for "Computer network"
showing 10 items of 1634 documents
Randomized renaming in shared memory systems.
2021
Abstract Renaming is a task in distributed computing where n processes are assigned new names from a name space of size m . The problem is called tight if m = n , and loose if m > n . In recent years renaming came to the fore again and new algorithms were developed. For tight renaming in asynchronous shared memory systems, Alistarh et al. describe a construction based on the AKS network that assigns all names within O ( log n ) steps per process. They also show that, depending on the size of the name space, loose renaming can be done considerably faster. For m = ( 1 + ϵ ) ⋅ n and constant ϵ , they achieve a step complexity of O ( log log n ) . In this paper we consider tight as well as loos…
Estimating the length of minimal spanning trees in compression of files
1984
Compression of a formatted file by a minimal spanning tree (MST) is studied. Here the records of the file are considered as the nodes of a weighted undirected graph. Each record pair is connected in the graph and the corresponding arc is weighted by the sum of field lengths of those fields which differ in the two records. The actual compression is made by constructing an MST of the graph and by storing it in an economic way to preserve the information of the file. The length of the MST is a useful measure in the estimation of the power of the compression. In the paper we study upper bounds of this length, especially in the case where the field lengths of the different fields may vary. The u…
HybridS: A Scheme for Secure Distributed Data Storage in WSNs
2008
In unattended wireless sensor networks (WSNs), data is stored locally or at designated nodes upon sensing, and users can access it on demand. This paradigm can improve energy efficiency by making use of the upcoming cheap and large flash memory, as well as system robustness. Nevertheless, the security and dependability of distributed storage are critical for the applicability of such WSNs. In this paper, we propose a secure and dependable data storage scheme by taking advantages of secret sharing and Reed-Solomon code, which has computational security and yet maintains optimal data size. The extensive analysis verifies our scheme can provide secure and dependable data storage in WSNs in the…
A resilient distributed measurement system for smart grid application
2020
Since the production of energy from renewable energy sources is strongly increasing, the migration from the classical electric grid toward the smart grid is becoming a reality. Distribution System Operators, along with the control of the entire network and its stability, need to address the security and the reliability of the communication channels and the data itself. In this paper a solution is proposed to address these issues. It is based on a distributed measurement system that relies on a wireless network as well as a redundant Power Line communication system in order to transfer the electrical measures to a centralized SCADA server. The collected data are used to run a power flow algo…
Building Semantic Trees from XML Documents
2016
International audience; The distributed nature of the Web, as a decentralized system exchanging information between heterogeneous sources, has underlined the need to manage interoperability, i.e., the ability to automatically interpret information in Web documents exchanged between different sources, necessary for efficient information management and search applications. In this context, XML was introduced as a data representation standard that simplifies the tasks of interoperation and integration among heterogeneous data sources, allowing to represent data in (semi-) structured documents consisting of hierarchically nested elements and atomic attributes. However, while XML was shown most …
A novel XML document structure comparison framework based-on sub-tree commonalities and label semantics
2012
International audience; XML similarity evaluation has become a central issue in the database and information communities, its applications ranging over document clustering, version control, data integration and ranked retrieval. Various algorithms for comparing hierarchically structured data, XML documents in particular, have been proposed in the literature. Most of them make use of techniques for finding the edit distance between tree structures, XML documents being commonly modeled as Ordered Labeled Trees. Yet, a thorough investigation of current approaches led us to identify several similarity aspects, i.e., sub-tree related structural and semantic similarities, which are not sufficient…
A Life Cycle Model of XML Documents
2014
Electronic documents produced in business processes are valuable information resources for organizations. In many cases they have to be accessible long after the life of the business processes or information systems in connection with which they were created. To improve the management and preservation of documents, organizations are deploying Extensible Markup Language (XML) as a standardized format for documents. The goal of this paper is to increase understanding of XML document management and provide a framework to enable the analysis and description of the management of XML documents throughout their life. We followed the design science approach. We introduce a document life cycle model…
Programming languages for data-Intensive HPC applications: A systematic mapping study
2020
This work is a result of activities from COST Action 10406 High -Performance Modelling and Simulation for Big Data Applications (cHiPSet), funded by the European Cooperation in Science and Technology. FCT, Portugal for grants: NOVA LINCS Research Laboratory Ref. UID/ CEC/ 04516/ 2019); INESC-ID Ref. UID/CEC/50021/2019; BioISI Ref. UID/MULTI/04046/2103; LASIGE Research Unit Ref. UID/CEC/00408/ 2019. A major challenge in modelling and simulation is the need to combine expertise in both software technologies and a given scientific domain. When High-Performance Computing (HPC) is required to solve a scientific problem, software development becomes a problematic issue. Considering the complexity…
A novel methodology for accelerating bitstream relocation in partially reconfigurable systems
2012
International audience; Xilinx Virtex FPGAs offer the possibility of Partial Reconfiguration (PR). Arbitrary tasks can be allocated and de-allocated onto FPGA without system interruption. However, mapping a task to any available PR region requires a unique partial bitstream for each partition, hence reducing memory storage requirements. In recent years, an interest on overcoming this problem has lead to the concept of Partial Bitstream Relocation (PBR). The principle is to perform bitstream modification to map it to different regions. However, PBR consumes scarce resources in hardware implementations, and introduces a prohibitive time overhead when done in software. In order to find the bes…
A Novel Energy Model for MANETs based on Graphs with Activation Windows
2005
Energy usage optimization is still an important issue and a critical design factor for mobile ad hoc networks (MANETs). Only recently a few proposals appeared that consider energy-aware optimizations for routing protocols. In this paper we describe an analytical model for MANETs which is based on graphs with activation windows. The activation windows allow to model the on-off status of the network devices. Moreover, we propose an algorithm with pseudo-polynomial complexity, called STP algorithm (STPA), that based on the current position and state of the nodes determines the shortest time path between the source node and the destination node.