National Technical University of Athens

Displaying 1-40 of 60 results

  • White Papers // Jan 2014

    A Synthesis Postprocessor for Fully Morphable RTL Datapaths

    Reconfigurable computing is intended to fill the gap between hardware and software, achieving potentially much higher performance than software, while maintaining a higher level of flexibility than hardware. In this paper, a special type of course grain reconfigurable RTL components, called morphable multipliers, are involved in high-level synthesis in the...

    Provided By National Technical University of Athens

  • White Papers // Jan 2014

    Run-Time Reconfigurable Solutions for Adaptive Control Applications

    The requirement for short time-to-market has made FPGA devices very popular for the implementation of general purpose electronic devices. Modern FPGA architectures offer the advantage of partial reconfiguration, which allows an algorithm to be partially mapped into a small and fixed FPGA device that can be reconfigured at run time,...

    Provided By National Technical University of Athens

  • White Papers // Jan 2014

    Exploring the Performance Limits of Simultaneous Multithreading for Scientific Codes

    Simultaneous Multi-Threading (SMT) has been proposed to improve system throughput by overlapping instructions from multiple threads on a single wide-issue processor. The speedup of a single application that is parallelized into multiple threads, is often sensitive to its inherent Instruction Level Parallelism (ILP), as well as the efficiency of synchronization...

    Provided By National Technical University of Athens

  • White Papers // Dec 2013

    Voltage Island Management in Near Threshold Manycore Architectures to Mitigate Dark Silicon

    The power-wall problem driven by the stagnation of supply voltages in deep-submicron technology nodes, is now the major scaling barrier for moving towards the manycore era. Although the technology scaling enables extreme volumes of computational power, power budget violations will permit only a limited portion to be actually exploited, leading...

    Provided By National Technical University of Athens

  • White Papers // Dec 2013

    Scheduling MapReduce Jobs on Unrelated Processors

    Scheduling in MapReduce environments has become increasingly important during the last years, as MapReduce has been established as the standard programming model to implement massive parallelism in large data centers. Applications of MapReduce such as search indexing, web analytics and data mining, involve the concurrent execution of several MapReduce jobs...

    Provided By National Technical University of Athens

  • White Papers // Aug 2013

    H2RDF+: High-Performance Distributed Joins Over Large-Scale RDF Graphs

    The proliferation of data in RDF format calls for efficient and scalable solutions for their management. While scalability in the era of big data is a hard requirement, modern systems fail to adapt based on the complexity of the query. Current approaches do not scale well when faced with substantially...

    Provided By National Technical University of Athens

  • White Papers // Jul 2013

    The Methodological Tools of Innovativeness, Proactiveness, and Internationalisation Towards the Prosperity of Global Small and Medium Sized Enterprises (Global SMEs) in an Epoch of Economic Recession

    The international entrepreneurship field has been predominately focused on the speed or pace of the firm to the international market. International entrepreneurial firms are considered to be typically smaller firms that from inception go abroad; contrarily, incremental internationalizes spend significant time in the domestic market prior to their initial internationalisation...

    Provided By National Technical University of Athens

  • White Papers // Mar 2013

    Automated, Elastic Resource Provisioning for NoSQL Clusters Using TIRAMOLA

    In this paper, the authors present TIRAMOLA, a cloud-enabled, open-source framework to perform automatic resizing of NoSQL clusters according to user-defined policies. Decisions on adding or removing worker VMs from a cluster are modeled as a Markov Decision Process and taken in real-time. The system automatically decides on the most...

    Provided By National Technical University of Athens

  • White Papers // Feb 2013

    A Framework for Supporting Parallel Application Placement onto Reconfigurable Platforms

    Placement is an essential step in Electronic Design Automation (EDA). An inferior placement will not only affect the performance of digital applications mapped onto the FPGA, but might also make the circuit unroutable by producing excessive wirelength, which is beyond the available fabricated routing resources. Throughout this paper, the authors...

    Provided By National Technical University of Athens

  • White Papers // Jan 2013

    On the Optimal Allocation of Virtual Resources in Cloud Computing Networks

    Cloud computing builds upon advances on virtualization and distributed computing to support cost-efficient usage of computing resources, emphasizing on resource scalability and on demand services. Moving away from traditional data-center oriented models, distributed clouds extend over a loosely coupled federated substrate, offering enhanced communication and computational services to target end-users...

    Provided By National Technical University of Athens

  • White Papers // Jan 2013

    Detecting DDoS Attacks With Passive Measurement Based Heuristics

    Network traffic anomalies such as Distributed Denial of Service attacks or the propagation of a new worm are hard to detect on non-congested ISP backbone links. The research community hasn't managed to offer reliable detection metrics that can be implemented with the current technology constraints to network administrators yet. In...

    Provided By National Technical University of Athens

  • White Papers // Dec 2012

    Self-Stabilizing Balancing Algorithm for Containment-Based Trees

    Containment-based trees encompass various handy structures such as B+-trees, R-trees and M-trees. They are widely used to build data indexes, range-queryable overlays, publish/subscribe systems both in centralized and distributed contexts. In addition to their versatility, their balanced shape ensures an overall satisfactory performance. Recently, it has been shown that their...

    Provided By National Technical University of Athens

  • White Papers // Dec 2012

    Characteristics of Video Traffic From Videoconference Applications: From H.261 to H.264

    This paper presents modeling results for H.26x video traffic generated by popular videoconference software applications. The analysis of videoconference data that were measured during realistic point-point videoconference sessions led users to the general conclusion that the traffic can be distinguished into two categories: unconstrained and con-strained. In the unconstrained traffic,...

    Provided By National Technical University of Athens

  • White Papers // Jul 2012

    On the Hardness of Network Design for Bottleneck Routing Games

    In routing games, the selfish behavior of the players may lead to a degradation of the network performance at equilibrium. In more than a few cases however, the equilibrium performance can be significantly improved if the authors remove some edges from the network. This counterintuitive fact, widely known as Braess's...

    Provided By National Technical University of Athens

  • White Papers // Jun 2012

    Publish/Subscribe Over Information Centric Networks: A Standardized Approach in CONVERGENCE

    Originally conceived as a "Network of hosts", the Internet is evolving into an Internet of services, an Internet of media, an Internet of people and an Internet of "Things". This implies a strategic shift from "Host-centric" to "Content-centric" and "Data-centric" networking. CONVERGENCE proposes to enhance the Internet with a novel,...

    Provided By National Technical University of Athens

  • White Papers // Jan 2012

    Clustering XML Documents by Structure

    This paper explores the application of clustering methods for grouping structurally similar XML documents. Modeling the XML documents as rooted ordered labeled trees, they apply clustering algorithms using distances that estimate the similarity between those trees in terms of the hierarchical relationships of their nodes. They suggest the usage of...

    Provided By National Technical University of Athens

  • White Papers // Oct 2011

    A Cloud Environment for Data-intensive Storage Services

    The emergence of cloud environments has made feasible the delivery of Internet-scale services by addressing a number of challenges such as live migration, fault tolerance and quality of service. However, current approaches do not tackle key issues related to cloud storage, which are of increasing importance given the enormous amount...

    Provided By National Technical University of Athens

  • White Papers // Jun 2011

    Query Answering Over SROIQ Knowledge Bases With SPARQL

    W3C currently extends the SPARQL query language with so-called entailment regimes, which define how queries are evaluated using logical entailment relations. The authors describe a sound and complete algorithm for the OWL Direct Semantics entailment regime. Since OWL's Direct Semantics is based on Description Logics (DLs), this results in an...

    Provided By National Technical University of Athens

  • White Papers // Jun 2011

    Parallel Paradigms and Run-Time Management Techniques for Many-Core Architectures: The 2PARMA Approach

    The current trend in computing architectures is to replace complex superscalar architectures with meshes of small homogeneous processing units connected by an on-chip network. This trend is mostly dictated by inherent silicon technology frontiers, which are getting as closer as the process densities levels increase. The number of cores to...

    Provided By National Technical University of Athens

  • White Papers // May 2011

    Thermal Optimization for Micro-Architectures Through Selective Block Replication

    Increased power densities result to higher on-chip temperatures, which in turn creates numerous problems tightly firmed to reliability issues. This problem is expected to become even more severe for deep-submicron technologies. In this paper, the authors propose a thermal-aware exploration framework at the micro-architecture level for temperature hotspots elimination through...

    Provided By National Technical University of Athens

  • White Papers // May 2011

    A Novel Methodology for Architecture-Level Exploration of 3D SoCs

    Three-Dimensional (3D) integration is an emerging technology that is expected to lead to tremendous benefits in terms of power, delay and silicon area. Moreover, 3D technology continues interconnect advances beyond the CMOS scaling predicted by Moore's Law, which enable new capabilities not available in 2D ICs. This paper proposes a...

    Provided By National Technical University of Athens

  • White Papers // Apr 2011

    Translation of Application-Level Terms to Resource-Level Attributes Across the Cloud Stack Layers

    The emergence of new environments such as Cloud computing highlighted new challenges in traditional fields like performance estimation. Most of the current cloud environments follow the Software, Platform, Infrastructure service model in order to map discrete roles/providers according to the offering in each "Layer." However, the limited amount of information...

    Provided By National Technical University of Athens

  • White Papers // Mar 2011

    Exploring the Benefits of Randomized Instruction Scheduling

    With the advent of the manycore era, processors are expected to comprise of simple cores, lacking sophisticated optimization capabilities such as out-of-order execution. Therefore, compiler optimizations such as instruction scheduling become relevant once more. At the same time, the increased diversity of processor architectures imposes the requirement of architecture independence...

    Provided By National Technical University of Athens

  • White Papers // Feb 2011

    Custom Microcoded Dynamic Memory Management for Distributed On-Chip Memory Organizations

    Multi-Processor System-on-Chip (MPSoCs) have attracted significant attention since they are recognized as a scalable paradigm to interconnect and organize a high number of cores. Current multi-core embedded systems exhibit increased levels of dynamic behavior, leading to unexpected memory footprint variations unknown at design time. Dynamic Memory Management (DMM) is a...

    Provided By National Technical University of Athens

  • White Papers // Feb 2011

    Redesigning the Open Mobile Alliance License Choice Algorithm

    Open Mobile Alliance (OMA) is an organization that is responsible for the creation of standards (among others) for the Mobile DRM systems and consists of some of most major mobile phone manufacturers, mobile system manufacturers, mobile network operators, as well as information technology companies. The proposed standards for the DRM...

    Provided By National Technical University of Athens

  • White Papers // Jan 2011

    Trading Fault-Masking With Performance Overhead for FPGAs

    Reliability issues become an important design concern with technology scaling. This paper introduces a novel methodology for balancing the desired fault masking and the consequence delay and power overheads due to redundancy. Experimental results shown that the authors' solution outperforms similar approaches since it achieves average delay and power savings...

    Provided By National Technical University of Athens

  • White Papers // Jan 2011

    Quick Hotspot: A Software Supported Methodology for Supporting Run-Time Thermal Analysis at MPSoC Designs

    Detailed thermal analysis and exploration has recently received significant attention since it is straightforward-related to numerous reliability issues. Furthermore, thermal profiling is a critical challenge for supporting efficient power management, especially to Multi-Processor System-on-Chips (MPSoCs). This problem becomes even more important if the authors take into account the computational complexity...

    Provided By National Technical University of Athens

  • White Papers // Dec 2010

    A Methodology and Tool Framework for Supporting Rapid Exploration of Memory Hierarchies in FPGAs

    This paper introduces a novel methodology for enabling rapid exploration of memory hierarchies onto FPGA devices. The methodology is software supported by a new open-source tool framework, named NAROUTO. Among others, the proposed framework enables critical tasks during architecture's design, such as memory hierarchy and floor-planning. Furthermore, NAROUTO framework is...

    Provided By National Technical University of Athens

  • White Papers // Dec 2010

    Runtime Tuning of Dynamic Memory Management for Mitigating Footprint-Fragmentation Variations

    In this paper, the authors explore the opportunities of effectively tuning at runtime the Dynamic Memory Management (DMM) mechanisms for mitigating memory variations in fragmentation-footprint constrained Multi-Processor Systems-on-Chip (MPSoCs). They focus their study on memory fragmentation due to its dependency on the runtime system behavior, which cannot be easily captured...

    Provided By National Technical University of Athens

  • White Papers // Dec 2010

    A Heterogeneous Multicore System on Chip With Run-Time Reconfigurable Virtual FPGA Architecture

    System design, especially for low power embedded applications often profit from a heterogeneous target hardware platform. The application can be partitioned into modules with specific requirements, e.g. parallelism or performance in relation to the provided hardware blocks on the multi-core hardware. The result is an optimized application mapping and a...

    Provided By National Technical University of Athens

  • White Papers // Oct 2010

    Minimizing Technical Complexities in Emerging Cloud Computing Platforms

    Cloud Computing is considered nowadays as the future of ICT systems leveraging new methodologies for developing, providing and consuming services. Even though many people believe that Cloud is just another buzzword for utility computing, this new computing paradigm is not only changing the design of modern computing plat-forms in technical...

    Provided By National Technical University of Athens

  • White Papers // Oct 2010

    A Real-Time Service Oriented Infrastructure

    The advancements in distributed computing have driven the emergence of service-based infrastructures that allow for on-demand provision of ICT assets. Taking into consideration the complexity of distributed environments, significant challenges exist in providing and managing the offered on-demand resources with the required level of Quality of Service (QoS), especially for...

    Provided By National Technical University of Athens

  • White Papers // Apr 2010

    Towards Supporting Fault-Tolerance in FPGAs

    This paper proposes a novel methodology for improving reliability of FPGAs without requiring special purpose hardware. In contrast to related approaches that are applied uniformly over the target architecture, the proposed one insert redundancy only the critical for failure resources. Such an approach leads to reasonable performance improvement. Last years,...

    Provided By National Technical University of Athens

  • White Papers // Apr 2010

    A High-Level Mapping Algorithm Targeting 3D NoC Architectures With Multiple Vdd

    The communication problem in modern ICs becomes a challenge issue. This paper introduces a high-level mapping algorithm targeting to low-power 3D NoC devices. By appropriately assigning application's functionalities to layers with different supply voltages the authors achieve reasonable energy savings and temperature reduction. Additionally, their methodology supports real-time adaption on...

    Provided By National Technical University of Athens

  • White Papers // Dec 2009

    A Framework for Enabling Fault Tolerance in Reconfigurable Architectures

    Fault tolerance is a pre-request not only for safety critical systems, but almost for the majority of applications. However, the additional hardware elements impose performance degradation. In this paper, the authors propose a software-supported methodology for protecting reconfigurable architectures against Single Event Upsets (SEUs), even if the target device is...

    Provided By National Technical University of Athens

  • White Papers // Nov 2009

    Ontology-Driven Conceptual Design of ETL Processes Using Graph Transformations

    One of the main tasks during the early steps of a data warehouse project is the identification of the appropriate transformations and the specification of inter-schema mappings from the source to the target data stores. This is a challenging task, requiring firstly the semantic and secondly the structural reconciliation of...

    Provided By National Technical University of Athens

  • White Papers // Nov 2009

    Policy-Regulated Management of ETL Evolution

    In this paper, the authors discuss the problem of performing impact prediction for changes that occur in the schema/structure of the data warehouse sources. They abstract Extract-Transform-Load (ETL) activities as queries and sequences of views. ETL activities and its sources are uniformly modeled as a graph that is annotated with...

    Provided By National Technical University of Athens

  • White Papers // Nov 2009

    Fault-Free: A Framework for Supporting Fault Tolerance in FPGAs

    In this paper, the authors propose a novel methodology for supporting application mapping onto FPGAs with fault tolerance even if this feature is not supported by the target platform. For the purposes of this paper they incorporate three techniques for error correction. The introduced fault tolerance can be implemented either...

    Provided By National Technical University of Athens

  • White Papers // Oct 2009

    Visualizing Multidimensional Data Through Granularity-Dependent Spatialization

    Spatialization is a special kind of visualization that projects multidimensional data into low-dimensional representational spaces by making use of spatial metaphors. Spatialization methods face a dual challenge: on the one hand, to apply dimension reduction techniques in order to overcome the limitations of the representational space, and on the other...

    Provided By National Technical University of Athens

  • White Papers // Oct 2009

    Rule-Based Management of Schema Changes at ETL Sources

    In this paper, the authors visit the problem of the management of inconsistencies emerging on ETL processes as results of evolution operations occurring at their sources. They abstract Extract-Transform-Load (ETL) activities as queries and sequences of views. ETL activities and its sources are uniformly modeled as a graph that is...

    Provided By National Technical University of Athens

  • White Papers // Apr 2010

    Towards Supporting Fault-Tolerance in FPGAs

    This paper proposes a novel methodology for improving reliability of FPGAs without requiring special purpose hardware. In contrast to related approaches that are applied uniformly over the target architecture, the proposed one insert redundancy only the critical for failure resources. Such an approach leads to reasonable performance improvement. Last years,...

    Provided By National Technical University of Athens

  • White Papers // Dec 2009

    A Framework for Enabling Fault Tolerance in Reconfigurable Architectures

    Fault tolerance is a pre-request not only for safety critical systems, but almost for the majority of applications. However, the additional hardware elements impose performance degradation. In this paper, the authors propose a software-supported methodology for protecting reconfigurable architectures against Single Event Upsets (SEUs), even if the target device is...

    Provided By National Technical University of Athens

  • White Papers // Jan 2011

    Trading Fault-Masking With Performance Overhead for FPGAs

    Reliability issues become an important design concern with technology scaling. This paper introduces a novel methodology for balancing the desired fault masking and the consequence delay and power overheads due to redundancy. Experimental results shown that the authors' solution outperforms similar approaches since it achieves average delay and power savings...

    Provided By National Technical University of Athens

  • White Papers // May 2011

    Thermal Optimization for Micro-Architectures Through Selective Block Replication

    Increased power densities result to higher on-chip temperatures, which in turn creates numerous problems tightly firmed to reliability issues. This problem is expected to become even more severe for deep-submicron technologies. In this paper, the authors propose a thermal-aware exploration framework at the micro-architecture level for temperature hotspots elimination through...

    Provided By National Technical University of Athens

  • White Papers // Jan 2011

    Quick Hotspot: A Software Supported Methodology for Supporting Run-Time Thermal Analysis at MPSoC Designs

    Detailed thermal analysis and exploration has recently received significant attention since it is straightforward-related to numerous reliability issues. Furthermore, thermal profiling is a critical challenge for supporting efficient power management, especially to Multi-Processor System-on-Chips (MPSoCs). This problem becomes even more important if the authors take into account the computational complexity...

    Provided By National Technical University of Athens

  • White Papers // Dec 2010

    A Methodology and Tool Framework for Supporting Rapid Exploration of Memory Hierarchies in FPGAs

    This paper introduces a novel methodology for enabling rapid exploration of memory hierarchies onto FPGA devices. The methodology is software supported by a new open-source tool framework, named NAROUTO. Among others, the proposed framework enables critical tasks during architecture's design, such as memory hierarchy and floor-planning. Furthermore, NAROUTO framework is...

    Provided By National Technical University of Athens

  • White Papers // Dec 2010

    A Heterogeneous Multicore System on Chip With Run-Time Reconfigurable Virtual FPGA Architecture

    System design, especially for low power embedded applications often profit from a heterogeneous target hardware platform. The application can be partitioned into modules with specific requirements, e.g. parallelism or performance in relation to the provided hardware blocks on the multi-core hardware. The result is an optimized application mapping and a...

    Provided By National Technical University of Athens

  • White Papers // Apr 2010

    A High-Level Mapping Algorithm Targeting 3D NoC Architectures With Multiple Vdd

    The communication problem in modern ICs becomes a challenge issue. This paper introduces a high-level mapping algorithm targeting to low-power 3D NoC devices. By appropriately assigning application's functionalities to layers with different supply voltages the authors achieve reasonable energy savings and temperature reduction. Additionally, their methodology supports real-time adaption on...

    Provided By National Technical University of Athens

  • White Papers // Jun 2012

    Publish/Subscribe Over Information Centric Networks: A Standardized Approach in CONVERGENCE

    Originally conceived as a "Network of hosts", the Internet is evolving into an Internet of services, an Internet of media, an Internet of people and an Internet of "Things". This implies a strategic shift from "Host-centric" to "Content-centric" and "Data-centric" networking. CONVERGENCE proposes to enhance the Internet with a novel,...

    Provided By National Technical University of Athens

  • White Papers // Jul 2012

    On the Hardness of Network Design for Bottleneck Routing Games

    In routing games, the selfish behavior of the players may lead to a degradation of the network performance at equilibrium. In more than a few cases however, the equilibrium performance can be significantly improved if the authors remove some edges from the network. This counterintuitive fact, widely known as Braess's...

    Provided By National Technical University of Athens

  • White Papers // Dec 2012

    Self-Stabilizing Balancing Algorithm for Containment-Based Trees

    Containment-based trees encompass various handy structures such as B+-trees, R-trees and M-trees. They are widely used to build data indexes, range-queryable overlays, publish/subscribe systems both in centralized and distributed contexts. In addition to their versatility, their balanced shape ensures an overall satisfactory performance. Recently, it has been shown that their...

    Provided By National Technical University of Athens

  • White Papers // Dec 2008

    Paving The Way To eGovernment Transformation: Interoperability Registry Infrastructure Development

    During the last decades eGovernment has been a vivid, dynamic research and development area. As services are being transformed, electronic documents and web services appear every day in many countries, the involved stakeholders are in urgent need for an instrument to structure governmental administration processes, service composition and provision -...

    Provided By National Technical University of Athens

  • White Papers // Oct 2008

    Dynamic Capabilities And Their Indirect Impact On Firm Performance

    This paper investigates the relationship between dynamic capabilities and firm performance. In particular it addresses the question of whether dynamic capabilities impact directly or indirectly on performance. Using data from manufacturing firms, the paper articulates and measures dynamic capabilities as a multi-dimensional construct with three underlying factors: coordination, learning and...

    Provided By National Technical University of Athens

  • White Papers // Feb 2011

    Redesigning the Open Mobile Alliance License Choice Algorithm

    Open Mobile Alliance (OMA) is an organization that is responsible for the creation of standards (among others) for the Mobile DRM systems and consists of some of most major mobile phone manufacturers, mobile system manufacturers, mobile network operators, as well as information technology companies. The proposed standards for the DRM...

    Provided By National Technical University of Athens

  • White Papers // Jun 2009

    A Model Predictive Control and Time Series Forecasting Framework for Supply Chain Management

    Model Predictive Control has been previously applied to supply chain problems with promising results; however hitherto proposed systems possessed no information on future demand. A forecasting methodology will surely promote the efficiency of control actions by providing insight on the future. A complete supply chain management framework that is based...

    Provided By National Technical University of Athens

  • White Papers // Feb 2011

    Custom Microcoded Dynamic Memory Management for Distributed On-Chip Memory Organizations

    Multi-Processor System-on-Chip (MPSoCs) have attracted significant attention since they are recognized as a scalable paradigm to interconnect and organize a high number of cores. Current multi-core embedded systems exhibit increased levels of dynamic behavior, leading to unexpected memory footprint variations unknown at design time. Dynamic Memory Management (DMM) is a...

    Provided By National Technical University of Athens

  • White Papers // Apr 2009

    A Framework for Preserving User Privacy and Ensuring QoS in Location Based Services Using Non-Irreversible Algorithm

    In this paper, the authors address the issue of preserving user privacy in location based services provisioning. This issue includes two controversial requirements, namely the protection of user's location privacy, and the location based services QoS. In this paper, they propose a framework that implements a non-irreversible algorithm, meaning that...

    Provided By National Technical University of Athens

  • White Papers // Dec 2008

    Performance Evaluation of an Enhanced Uplink 3.5G System for Mobile Healthcare Applications

    The present paper studies the prospective and the performance of a forthcoming high-speed third generation (3.5G) networking technology, called enhanced uplink, for delivering mobile health (m-health) applications. The performance of 3.5G networks is a critical factor for successful development of m-health services perceived by end users. In this paper, the...

    Provided By National Technical University of Athens

  • White Papers // Apr 2011

    Translation of Application-Level Terms to Resource-Level Attributes Across the Cloud Stack Layers

    The emergence of new environments such as Cloud computing highlighted new challenges in traditional fields like performance estimation. Most of the current cloud environments follow the Software, Platform, Infrastructure service model in order to map discrete roles/providers according to the offering in each "Layer." However, the limited amount of information...

    Provided By National Technical University of Athens

  • White Papers // Jan 2012

    Clustering XML Documents by Structure

    This paper explores the application of clustering methods for grouping structurally similar XML documents. Modeling the XML documents as rooted ordered labeled trees, they apply clustering algorithms using distances that estimate the similarity between those trees in terms of the hierarchical relationships of their nodes. They suggest the usage of...

    Provided By National Technical University of Athens

  • White Papers // Nov 2009

    Ontology-Driven Conceptual Design of ETL Processes Using Graph Transformations

    One of the main tasks during the early steps of a data warehouse project is the identification of the appropriate transformations and the specification of inter-schema mappings from the source to the target data stores. This is a challenging task, requiring firstly the semantic and secondly the structural reconciliation of...

    Provided By National Technical University of Athens

  • White Papers // Nov 2009

    Policy-Regulated Management of ETL Evolution

    In this paper, the authors discuss the problem of performing impact prediction for changes that occur in the schema/structure of the data warehouse sources. They abstract Extract-Transform-Load (ETL) activities as queries and sequences of views. ETL activities and its sources are uniformly modeled as a graph that is annotated with...

    Provided By National Technical University of Athens

  • White Papers // Oct 2009

    Rule-Based Management of Schema Changes at ETL Sources

    In this paper, the authors visit the problem of the management of inconsistencies emerging on ETL processes as results of evolution operations occurring at their sources. They abstract Extract-Transform-Load (ETL) activities as queries and sequences of views. ETL activities and its sources are uniformly modeled as a graph that is...

    Provided By National Technical University of Athens

  • White Papers // Apr 2009

    Evaluating Reachability Queries Over Path Collections

    Several applications in areas such as biochemistry, GIS, involve storing and querying large volumes of sequential data stored as path collections. There is a number of interesting queries that can be posed on such data. This work focuses on reachability queries: given a path collection and two nodes vs, vt,...

    Provided By National Technical University of Athens

  • White Papers // Nov 2008

    Topologically Sorted Skylines for Partially Ordered Domains

    The vast majority of work on skyline queries considers totally ordered domains, whereas in many applications some attributes are partially ordered, as for instance, domains of set values, hierarchies, intervals and preferences. The only work addressing this issue has limited progressiveness and pruning ability, and it is only applicable to...

    Provided By National Technical University of Athens

  • White Papers // Jun 2011

    Query Answering Over SROIQ Knowledge Bases With SPARQL

    W3C currently extends the SPARQL query language with so-called entailment regimes, which define how queries are evaluated using logical entailment relations. The authors describe a sound and complete algorithm for the OWL Direct Semantics entailment regime. Since OWL's Direct Semantics is based on Description Logics (DLs), this results in an...

    Provided By National Technical University of Athens

  • White Papers // May 2011

    A Novel Methodology for Architecture-Level Exploration of 3D SoCs

    Three-Dimensional (3D) integration is an emerging technology that is expected to lead to tremendous benefits in terms of power, delay and silicon area. Moreover, 3D technology continues interconnect advances beyond the CMOS scaling predicted by Moore's Law, which enable new capabilities not available in 2D ICs. This paper proposes a...

    Provided By National Technical University of Athens

  • White Papers // Jan 2009

    A Software-Supported Methodology for Exploring Interconnection Architectures Targeting 3-D FPGAs

    Interconnect structures significantly contribute to the delay, power consumption, and silicon area of modern reconfigurable architectures. The demand for higher clock frequencies and logic densities is also important for the Field-Programmable Gate Array (FPGA) paradigm. Three-Dimensional (3-D) integration can alleviate such performance limitations by accommodating a number of additional silicon...

    Provided By National Technical University of Athens

  • White Papers // Nov 2008

    System-Level Exploration of 3-D Interconnection Schemes

    3-D chip stacking is the big next step in system integration. Even though the process technology is maturing, many issues related to system implementation are not fully understood yet. Furthermore, this 3-D integration comes in many different flavors. Adoption in mainstream industrial design flows requires the availability of tools that...

    Provided By National Technical University of Athens

  • White Papers // Dec 2008

    A Novel Methodology for Exploring Interconnection Architectures Targeting 3-D FPGAs

    In current reconfigurable architectures the interconnection structures increasingly contribute more to the delay and power consumption. The demand for increased clock frequencies and logic density (smaller area footprint) makes the problem even more important. Three-Dimensional (3-D) integration can alleviate these problems by vertically stacking multiple physical layers. In this paper,...

    Provided By National Technical University of Athens

  • White Papers // Nov 2009

    Fault-Free: A Framework for Supporting Fault Tolerance in FPGAs

    In this paper, the authors propose a novel methodology for supporting application mapping onto FPGAs with fault tolerance even if this feature is not supported by the target platform. For the purposes of this paper they incorporate three techniques for error correction. The introduced fault tolerance can be implemented either...

    Provided By National Technical University of Athens

  • White Papers // Jul 2009

    Applied Surveillance Using Biometrics on Agents Infrastructures

    The biometric identification of individuals has many safety and security applications in several fields of major interest. This can range from healthcare to commerce and from defense to banking systems. Current biometric technologies are hardly suitable for remote online massive use. This paper presents an innovative approach to design advanced...

    Provided By National Technical University of Athens

  • White Papers // May 2006

    Security as Immunity in Virtual Organizations

    The authors are addressing the class of virtual organizations where an entrepreneurial or other activity acts as an interface between a number of existing remote services or applications and a number of customers that should interact with them in complex ways. For example, such activities include private e-Government middle services...

    Provided By National Technical University of Athens

  • White Papers // Mar 2006

    Adaptive Query Formulation to Handle Database Evolution

    Databases are continuously evolving environments, where design constructs are added, removed or updated rather often. Research has extensively dealt with the problem of database evolution. Nevertheless, problems arise with existing queries and applications, mainly due to the fact that, in most cases, their role as integral parts of the environment...

    Provided By National Technical University of Athens

  • White Papers // Dec 2013

    Scheduling MapReduce Jobs on Unrelated Processors

    Scheduling in MapReduce environments has become increasingly important during the last years, as MapReduce has been established as the standard programming model to implement massive parallelism in large data centers. Applications of MapReduce such as search indexing, web analytics and data mining, involve the concurrent execution of several MapReduce jobs...

    Provided By National Technical University of Athens

  • White Papers // Feb 2013

    A Framework for Supporting Parallel Application Placement onto Reconfigurable Platforms

    Placement is an essential step in Electronic Design Automation (EDA). An inferior placement will not only affect the performance of digital applications mapped onto the FPGA, but might also make the circuit unroutable by producing excessive wirelength, which is beyond the available fabricated routing resources. Throughout this paper, the authors...

    Provided By National Technical University of Athens

  • White Papers // Dec 2010

    Runtime Tuning of Dynamic Memory Management for Mitigating Footprint-Fragmentation Variations

    In this paper, the authors explore the opportunities of effectively tuning at runtime the Dynamic Memory Management (DMM) mechanisms for mitigating memory variations in fragmentation-footprint constrained Multi-Processor Systems-on-Chip (MPSoCs). They focus their study on memory fragmentation due to its dependency on the runtime system behavior, which cannot be easily captured...

    Provided By National Technical University of Athens

  • White Papers // Jul 2008

    Joint Exploitation of Horizontal/Vertical Parallelism and Operation Chaining for Flexible DSP Synthesis

    In this paper, the authors present a new methodology for the synthesis of high performance flexible datapath, targeting the computationally intensive DSP kernels of modern embedded applications. The proposed methodology is based on a novel coarse-grained reconfigurable architectural template, which enables the combined exploitation of the horizontal/vertical parallelism along with...

    Provided By National Technical University of Athens

  • White Papers // Jan 2014

    A Synthesis Postprocessor for Fully Morphable RTL Datapaths

    Reconfigurable computing is intended to fill the gap between hardware and software, achieving potentially much higher performance than software, while maintaining a higher level of flexibility than hardware. In this paper, a special type of course grain reconfigurable RTL components, called morphable multipliers, are involved in high-level synthesis in the...

    Provided By National Technical University of Athens

  • White Papers // Aug 2008

    A Flexible Architecture for DSP Applications Combining High Performance Arithmetic with Small Scale Configurability

    As the VLSI fabrication technology continues to scale down the design of complex configurable hardware systems has became a reality. In contrast with the classical FPGA-like reconfigurable architectures, coarse-grained architectures have been proposed in the bibliography, which preserve flexibility and deliver high speed implementations along with low power consumption. This...

    Provided By National Technical University of Athens