Página 13 dos resultados de 3715 itens digitais encontrados em 0.067 segundos

A novel strategy for building interoperable MPI environment in heterogeneous high performance systems

Massetto, Francisco Isidro; Sato, Liria Matsumoto; Li, Kuan-Ching
Fonte: SPRINGER; DORDRECHT Publicador: SPRINGER; DORDRECHT
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.441406%
Breakthrough advances in microprocessor technology and efficient power management have altered the course of development of processors with the emergence of multi-core processor technology, in order to bring higher level of processing. The utilization of many-core technology has boosted computing power provided by cluster of workstations or SMPs, providing large computational power at an affordable cost using solely commodity components. Different implementations of message-passing libraries and system softwares (including Operating Systems) are installed in such cluster and multi-cluster computing systems. In order to guarantee correct execution of message-passing parallel applications in a computing environment other than that originally the parallel application was developed, review of the application code is needed. In this paper, a hybrid communication interfacing strategy is proposed, to execute a parallel application in a group of computing nodes belonging to different clusters or multi-clusters (computing systems may be running different operating systems and MPI implementations), interconnected with public or private IP addresses, and responding interchangeably to user execution requests. Experimental results demonstrate the feasibility of this proposed strategy and its effectiveness...

Architecting Information Centric ETSI-M2M systems

Grieco, Luigi Alfredo; Alaya, Mahdi Ben; Monteil, Thierry; Drira, Khalil
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 06/03/2014 Português
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47.445195%
The European Telecommunications Standards Institute (ETSI) released a set of specifications to define a restful architecture for enabling seamless service provisioning across heterogeneous Machine-to-Machine (M2M) systems. The current version of this architecture is strongly centralized, thus requiring new enhancements to its scalability, fault tolerance, and flexibility. To bridge this gap, herein it is presented an Overlay Service Capability Layer, based on Information Centric Networking design. Key features, example use cases and preliminary performance assessments are also discussed to highlight the potential of our approach.

Performance Analysis of a Network of Event-based Systems

Ramesh, Chithrupa; Sandberg, Henrik; Johansson, Karl H.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 20/01/2014 Português
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47.45142%
We consider a scenario where multiple event-based systems use a wireless network to communicate with their respective controllers. These systems use a contention resolution mechanism (CRM) to arbitrate access to the network. We present a Markov model for the network interactions between the event-based systems. Using this model, we obtain an analytical expression for the reliability, or the probability of successfully transmitting a packet, in this network. There are two important aspects to our model. Firstly, our model captures the joint interactions of the event-triggering policy and the CRM. This is required because event-triggering policies typically adapt to the CRM outcome. Secondly, the model is obtained by decoupling interactions between the different systems in the network, drawing inspiration from Bianchi's analysis of IEEE 802.11. This is required because the network interactions introduce a correlation between the system variables. We present Monte-Carlo simulations that validate our model under various network configurations, and verify our performance analysis as well.

Measuring the Complexity of Ultra-Large-Scale Adaptive Systems

Amoretti, Michele; Gershenson, Carlos
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
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47.441406%
Ultra-large scale (ULS) systems are becoming pervasive. They are inherently complex, which makes their design and control a challenge for traditional methods. Here we propose the design and analysis of ULS systems using measures of complexity, emergence, self-organization, and homeostasis based on information theory. These measures allow the evaluation of ULS systems and thus can be used to guide their design. We evaluate the proposal with a ULS computing system provided with adaptation mechanisms. We show the evolution of the system with stable and also changing workload, using different fitness functions. When the adaptive plan forces the system to converge to a predefined performance level, the nodes may result in highly unstable configurations, that correspond to a high variance in time of the measured complexity. Conversely, if the adaptive plan is less "aggressive", the system may be more stable, but the optimal performance may not be achieved.; Comment: highly extended version, 28 pages, 11 figures

Designing Rating Systems to Promote Mutual Security for Interconnected Networks

Xu, Jie; Zhang, Yu; van der Schaar, Mihaela
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/11/2012 Português
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47.44253%
Interconnected autonomous systems often share security risks. However, an autonomous system lacks the incentive to make (sufficient) security investments if the cost exceeds its own benefit even though doing that would be socially beneficial. In this paper, we develop a systematic and rigorous framework for analyzing and significantly improving the mutual security of a collection of ASs that interact frequently over a long period of time. Using this framework, we show that simple incentive schemes based on rating systems can be designed to encourage the autonomous systems' security investments, thereby significantly improving their mutual security.

Performance monitoring for multicore embedded computing systems on FPGAs

Shannon, Lesley; Matthews, Eric; Doyle, Nicholas; Fedorova, Alexandra
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 28/08/2015 Português
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47.43539%
When designing modern embedded computing systems, most software programmers choose to use multicore processors, possibly in combination with general-purpose graphics processing units (GPGPUs) and/or hardware accelerators. They also often use an embedded Linux O/S and run multi-application workloads that may even be multi-threaded. Modern FPGAs are large enough to combine multicore hard/soft processors with multiple hardware accelerators as custom compute units, enabling entire embedded compute systems to be implemented on a single FPGA. Furthermore, the large FPGA vendors also support embedded Linux kernels for both their soft and embedded processors. When combined with high-level synthesis to generate hardware accelerators using a C-to-gates flows, the necessary primitives for a framework that can enable software designers to use FPGAs as their custom compute platform now exist. However, in order to ensure that computing resources are integrated and shared effectively, software developers need to be able to monitor and debug the runtime performance of the applications in their workload. This paper describes ABACUS, a performance-monitoring framework that can be used to debug the execution behaviours and interactions of multi-application workloads on multicore systems. We also discuss how this framework is extensible for use with hardware accelerators in heterogeneous systems.; Comment: Presented at Second International Workshop on FPGAs for Software Programmers (FSP 2015) (arXiv:1508.06320)

An Implementation of Intrusion Detection System Using Genetic Algorithm

Hoque, Mohammad Sazzadul; Mukit, Md. Abdul; Bikas, Md. Abu Naser
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/04/2012 Português
Relevância na Pesquisa
47.444385%
Nowadays it is very important to maintain a high level security to ensure safe and trusted communication of information between various organizations. But secured data communication over internet and any other network is always under threat of intrusions and misuses. So Intrusion Detection Systems have become a needful component in terms of computer and network security. There are various approaches being utilized in intrusion detections, but unfortunately any of the systems so far is not completely flawless. So, the quest of betterment continues. In this progression, here we present an Intrusion Detection System (IDS), by applying genetic algorithm (GA) to efficiently detect various types of network intrusions. Parameters and evolution processes for GA are discussed in details and implemented. This approach uses evolution theory to information evolution in order to filter the traffic data and thus reduce the complexity. To implement and measure the performance of our system we used the KDD99 benchmark dataset and obtained reasonable detection rate.

Secure Vehicular Communication Systems: Implementation, Performance, and Research Challenges

Kargl, F.; Papadimitratos, P.; Buttyan, L.; Muter, M.; Wiedersheim, B.; Schoch, E.; Thong, T. -V.; Calandriello, G.; Held, A.; Kung, A.; Hubaux, J. -P.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 30/12/2009 Português
Relevância na Pesquisa
47.43093%
Vehicular Communication (VC) systems are on the verge of practical deployment. Nonetheless, their security and privacy protection is one of the problems that have been addressed only recently. In order to show the feasibility of secure VC, certain implementations are required. In [1] we discuss the design of a VC security system that has emerged as a result of the European SeVeCom project. In this second paper, we discuss various issues related to the implementation and deployment aspects of secure VC systems. Moreover, we provide an outlook on open security research issues that will arise as VC systems develop from today's simple prototypes to full-fledged systems.

Adaptive Domain Model: Dealing With Multiple Attributes of Self-Managing Distributed Object Systems

Motuzenko, Pavel
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 13/07/2003 Português
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47.42747%
Self-managing software has emerged as modern systems have become more complex. Some of the distributed object systems may contain thousands of objects deployed on tens or even hundreds hosts. Development and support of such systems often costs a lot. To solve this issue the systems, which are capable supporting multiple self-managing attributes, should be created. In the paper, the Adaptive domain concept is introduced as an extension to the basic domain concept to support a generic adaptation environment for building distributed object systems with multiple self-managing attributes.; Comment: 6 pages, 3 figures

Task swapping networks in distributed systems

Kim, Dohan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
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47.43341%
In this paper we propose task swapping networks for task reassignments by using task swappings in distributed systems. Some classes of task reassignments are achieved by using iterative local task swappings between software agents in distributed systems. We use group-theoretic methods to find a minimum-length sequence of adjacent task swappings needed from a source task assignment to a target task assignment in a task swapping network of several well-known topologies.; Comment: This is a preprint of a paper whose final and definite form is published in: Int. J. Comput. Math. 90 (2013), 2221-2243 (DOI: 10.1080/00207160.2013.772985)

Driver-Based Adaptation of Vehicular Ad Hoc Networks for Design of Active Safety Systems

Rakhshan, Ali; Pishro-Nik, Hossein; Nekoui, Mohammad
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 03/02/2015 Português
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47.45318%
This paper studies the need for individualizing vehicular communications in order to improve collision warning systems for an N-lane highway scenario. By relating the traffic-based and communications studies, we aim at reducing highway traffic accidents. To the best of our knowledge, this is the first paper that shows how to customize vehicular communications to driver's characteristics and traffic information. We propose to develop VANET protocols that selectively identify crash relevant information and customize the communications of that information based on each driver's assigned safety score. In this paper, first, we derive the packet success probability by accounting for multi-user interference, path loss, and fading. Then, by Monte carlo simulations, we demonstrate how appropriate channel access probabilities that satisfy the delay requirements of the safety application result in noticeable performance enhancement.; Comment: 3 pages Summary, CISS 2015, JOHNS HOPKINS University

Protocol Coding through Reordering of User Resources: Applications and Capacity Results

Popovski, Petar; Utkovski, Zoran
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
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47.438765%
While there are continuous efforts to introduce new communication systems and standards, it is legitimate to ask the question: how can one send additional bits by minimally changing the systems that are already operating? This is of a significant practical interest, since it has a potential to generate additional value of the systems through, for example, introduction of new devices and only a software update of the access points or base stations, without incurring additional cost for infrastructure hardware installation. The place to look for such an opportunity is the communication protocol and we use the term *protocol coding* to refer to strategies for sending information by using the degrees of freedom available when one needs to decide the actions taken by a particular communication protocol. In this paper we consider protocol coding that gives a rise to *secondary communication channels*, defined by combinatorial ordering of the user resources (packets, channels) in a primary (legacy) communication system. We introduce communication models that enable us to compute the capacity of such secondary channels under suitable restrictions imposed by the primary systems. We first show the relation to the capacity of channels with causal channel state information at the transmitter (CSIT)...

Comparison of Image Similarity Queries in P2P Systems

Mueller, Wolfgang; Boykin, P. Oscar; Sarshar, Nima; Roychowdhury, Vwani P.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 29/06/2006 Português
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47.446733%
Given some of the recent advances in Distributed Hash Table (DHT) based Peer-To-Peer (P2P) systems we ask the following questions: Are there applications where unstructured queries are still necessary (i.e., the underlying queries do not efficiently map onto any structured framework), and are there unstructured P2P systems that can deliver the high bandwidth and computing performance necessary to support such applications. Toward this end, we consider an image search application which supports queries based on image similarity metrics, such as color histogram intersection, and discuss why in this setting, standard DHT approaches are not directly applicable. We then study the feasibility of implementing such an image search system on two different unstructured P2P systems: power-law topology with percolation search, and an optimized super-node topology using structured broadcasts. We examine the average and maximum values for node bandwidth, storage and processing requirements in the percolation and super-node models, and show that current high-end computers and high-speed links have sufficient resources to enable deployments of large-scale complex image search systems.; Comment: To appear in IEEE P2P2006

EURETILE D7.3 - Dynamic DAL benchmark coding, measurements on MPI version of DPSNN-STDP (distributed plastic spiking neural net) and improvements to other DAL codes

Paolucci, Pier Stanislao; Bacivarov, Iuliana; Rai, Devendra; Schor, Lars; Thiele, Lothar; Yang, Hoeseok; Pastorelli, Elena; Ammendola, Roberto; Biagioni, Andrea; Frezza, Ottorino; Cicero, Francesca Lo; Lonardo, Alessandro; Simula, Francesco; Tosoratto, La
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 20/08/2014 Português
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47.437817%
The EURETILE project required the selection and coding of a set of dedicated benchmarks. The project is about the software and hardware architecture of future many-tile distributed fault-tolerant systems. We focus on dynamic workloads characterised by heavy numerical processing requirements. The ambition is to identify common techniques that could be applied to both the Embedded Systems and HPC domains. This document is the first public deliverable of Work Package 7: Challenging Tiled Applications.; Comment: 34 pages. arXiv admin note: substantial text overlap with arXiv:1310.8478

Joint Estimation and Localization in Sensor Networks

Atanasov, Nikolay A.; Tron, Roberto; Preciado, Victor M.; Pappas, George J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/04/2014 Português
Relevância na Pesquisa
47.435176%
This paper addresses the problem of collaborative tracking of dynamic targets in wireless sensor networks. A novel distributed linear estimator, which is a version of a distributed Kalman filter, is derived. We prove that the filter is mean square consistent in the case of static target estimation. When large sensor networks are deployed, it is common that the sensors do not have good knowledge of their locations, which affects the target estimation procedure. Unlike most existing approaches for target tracking, we investigate the performance of our filter when the sensor poses need to be estimated by an auxiliary localization procedure. The sensors are localized via a distributed Jacobi algorithm from noisy relative measurements. We prove strong convergence guarantees for the localization method and in turn for the joint localization and target estimation approach. The performance of our algorithms is demonstrated in simulation on environmental monitoring and target tracking tasks.; Comment: 9 pages (two-column); 5 figures; Manuscript submitted to the 2014 IEEE Conference on Decision and Control (CDC)

Buffer Insertion for Bridges and Optimal Buffer Sizing for Communication Sub-System of Systems-on-Chip

Kallakuri, Sankalp S.; Doboli, Alex; Feinberg, Eugene A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 25/10/2007 Português
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47.454316%
We have presented an optimal buffer sizing and buffer insertion methodology which uses stochastic models of the architecture and Continuous Time Markov Decision Processes CTMDPs. Such a methodology is useful in managing the scarce buffer resources available on chip as compared to network based data communication which can have large buffer space. The modeling of this problem in terms of a CT-MDP framework lead to a nonlinear formulation due to usage of bridges in the bus architecture. We present a methodology to split the problem into several smaller though linear systems and we then solve these subsystems.; Comment: Submitted on behalf of EDAA (http://www.edaa.com/)

A Lightweight Approach for Improving the Lookup Performance in Kademlia-type Systems

Salah, Hani; Roos, Stefanie; Strufe, Thorsten
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 27/07/2014 Português
Relevância na Pesquisa
47.45142%
Discovery of nodes and content in large-scale distributed systems is generally based on Kademlia, today. Understanding Kademlia-type systems to improve their performance is essential for maintaining a high service quality for an increased number of participants, particularly when those systems are adopted by latency-sensitive applications. This paper contributes to the understanding of Kademlia by studying the impact of \emph{diversifying} neighbours' identifiers within each routing table bucket on the lookup performance. We propose a new, yet backward-compatible, neighbour selection scheme that attempts to maximize the aforementioned diversity. The scheme does not cause additional overhead except negligible computations for comparing the diversity of identifiers. We present a theoretical model for the actual impact of the new scheme on the lookup's hop count and validate it against simulations of three exemplary Kademlia-type systems. We also measure the performance gain enabled by a partial deployment for the scheme in the real KAD system. The results confirm the superiority of the systems that incorporate our scheme.; Comment: 13 pages, 8 figures, conference version 'Diversity Entails Improvement: A new Neighbour Selection Scheme for Kademlia-type Systems' at IEEE P2P 2014

The Projection Method for Reaching Consensus and the Regularized Power Limit of a Stochastic Matrix

Agaev, R. P.; Chebotarev, P. Yu.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.44871%
In the coordination/consensus problem for multi-agent systems, a well-known condition of achieving consensus is the presence of a spanning arborescence in the communication digraph. The paper deals with the discrete consensus problem in the case where this condition is not satisfied. A characterization of the subspace $T_P$ of initial opinions (where $P$ is the influence matrix) that \emph{ensure} consensus in the DeGroot model is given. We propose a method of coordination that consists of: (1) the transformation of the vector of initial opinions into a vector belonging to $T_P$ by orthogonal projection and (2) subsequent iterations of the transformation $P.$ The properties of this method are studied. It is shown that for any non-periodic stochastic matrix $P,$ the resulting matrix of the orthogonal projection method can be treated as a regularized power limit of $P.$; Comment: 19 pages, 2 figures

Proceedings of the DATE Friday Workshop on Heterogeneous Architectures and Design Methods for Embedded Image Systems (HIS 2015)

Hannig, Frank; Fey, Dietmar; Lokhmotov, Anton
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
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47.42734%
This volume contains the papers accepted at the DATE Friday Workshop on Heterogeneous Architectures and Design Methods for Embedded Image Systems (HIS 2015), held in Grenoble, France, March 13, 2015. HIS 2015 was co-located with the Conference on Design, Automation and Test in Europe (DATE).; Comment: Website of the workshop: https://www12.cs.fau.de/ws/his2015/

Comparing paedophile activity in different P2P systems

Fournier, Raphaël; Cholez, Thibault; Latapy, Matthieu; Magnien, Clémence; Chrisment, Isabelle; Daniloff, Ivan; Festor, Olivier
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/06/2012 Português
Relevância na Pesquisa
47.441406%
Peer-to-peer (P2P) systems are widely used to exchange content over the Internet. Knowledge on paedophile activity in such networks remains limited while it has important social consequences. Moreover, though there are different P2P systems in use, previous academic works on this topic focused on one system at a time and their results are not directly comparable. We design a methodology for comparing \kad and \edonkey, two P2P systems among the most prominent ones and with different anonymity levels. We monitor two \edonkey servers and the \kad network during several days and record hundreds of thousands of keyword-based queries. We detect paedophile-related queries with a previously validated tool and we propose, for the first time, a large-scale comparison of paedophile activity in two different P2P systems. We conclude that there are significantly fewer paedophile queries in \kad than in \edonkey (approximately 0.09% \vs 0.25%).; Comment: Submitted