70,846 research outputs found
The Impact of Data Replicatino on Job Scheduling Performance in Hierarchical data Grid
In data-intensive applications data transfer is a primary cause of job
execution delay. Data access time depends on bandwidth. The major bottleneck to
supporting fast data access in Grids is the high latencies of Wide Area
Networks and Internet. Effective scheduling can reduce the amount of data
transferred across the internet by dispatching a job to where the needed data
are present. Another solution is to use a data replication mechanism. Objective
of dynamic replica strategies is reducing file access time which leads to
reducing job runtime. In this paper we develop a job scheduling policy and a
dynamic data replication strategy, called HRS (Hierarchical Replication
Strategy), to improve the data access efficiencies. We study our approach and
evaluate it through simulation. The results show that our algorithm has
improved 12% over the current strategies.Comment: 11 pages, 7 figure
Replicating smart cities: the city-to-city learning programme in the replicate EC-H2020-SCC project
This article addresses the problem of replication among smart cities in the European Commissionâs Horizon 2020: Smart Cities and Communities (EC-H2020-SCC) framework programme. This article initially sets the general policy context by conducting a benchmarking about the explicit replication strategies followed by each of the 17 ongoing EC-H2020-SCC lighthouse projects. This article aims to shed light on the following research question: Why might replication not be happening among smart cities as a unidirectional, hierarchical, mechanistic, solutionist, and technocratic process? Particularly, in asking so, it focuses on the EC-H2020-SCC Replicate project by examining in depth the fieldwork action research process implemented during 2019 through a knowledge exchange webinar series with participant stakeholders from six European citiesâthree lighthouse cities (St. Sebastian, Florence, and Bristol) and three follower-fellow cities (Essen, Lausanne, and NilĂŒfer). This process resulted in a City-to-City Learning Programme that reformulated the issue of replication by experimenting an alternative and an enhanced policy approach. Thus, stemming from the evidence-based policy outcomes of the City-to-City Learning Programme, this article reveals that a replication policy approach from the social innovation lenses might be enabled as a multidirectional, radial, dynamic, iterative, and democratic learning process, overcoming the given unidirectional, hierarchical, mechanistic, solutionist, and technocratic approach
Architecture for Mobile Heterogeneous Multi Domain Networks
Multi domain networks can be used in several scenarios including military, enterprize networks, emergency networks and many other cases. In such networks, each domain might be under its own administration. Therefore, the cooperation among domains is conditioned by individual domain policies regarding sharing information, such as network topology, connectivity, mobility, security, various service availability and so on. We propose a new architecture for Heterogeneous Multi Domain (HMD) networks, in which one the operations are subject to specific domain policies. We propose a hierarchical architecture, with an infrastructure of gateways at highest-control level that enables policy based interconnection, mobility and other services among domains. Gateways are responsible for translation among different communication protocols, including routing, signalling, and security. Besides the architecture, we discuss in more details the mobility and adaptive capacity of services in HMD. We discuss the HMD scalability and other advantages compared to existing architectural and mobility solutions. Furthermore, we analyze the dynamic availability at the control level of the hierarchy
The 2008 election: A preregistered replication analysis
We present an increasingly stringent set of replications of Ghitza & Gelman
(2013), a multilevel regression and poststratification analysis of polls from
the 2008 U.S. presidential election campaign, focusing on a set of plots
showing the estimated Republican vote share for whites and for all voters, as a
function of income level in each of the states.
We start with a nearly-exact duplication that uses the posted code and
changes only the model-fitting algorithm; we then replicate using
already-analyzed data from 2004; and finally we set up preregistered
replications using two surveys from 2008 that we had not previously looked at.
We have already learned from our preliminary, non-preregistered replication,
which has revealed a potential problem with the published analysis of Ghitza &
Gelman (2013); it appears that our model may not sufficiently account for
nonsampling error, and that some of the patterns presented in that earlier
paper may simply reflect noise.
In addition to the substantive interest in validating earlier findings about
demographics, geography, and voting, the present project serves as a
demonstration of preregistration in a setting where the subject matter is
historical (and thus the replication data exist before the preregistration plan
is written) and where the analysis is exploratory (and thus a replication
cannot be simply deemed successful or unsuccessful based on the statistical
significance of some particular comparison).Comment: This article is a review and preregistration plan. It will be
published, along with a new Section 5 describing the results of the
preregistered analysis, in Statistics and Public Polic
Toward a Formal Semantics for Autonomic Components
Autonomic management can improve the QoS provided by parallel/ distributed
applications. Within the CoreGRID Component Model, the autonomic management is
tailored to the automatic - monitoring-driven - alteration of the component
assembly and, therefore, is defined as the effect of (distributed) management
code. This work yields a semantics based on hypergraph rewriting suitable to
model the dynamic evolution and non-functional aspects of Service Oriented
Architectures and component-based autonomic applications. In this regard, our
main goal is to provide a formal description of adaptation operations that are
typically only informally specified. We contend that our approach makes easier
to raise the level of abstraction of management code in autonomic and adaptive
applications.Comment: 11 pages + cover pag
Object Distribution Networks for World-wide Document Circulation
This paper presents an Object Distribution System (ODS), a distributed system inspired by the ultra-large scale distribution models used in everyday life (e.g. food or newspapers distribution chains). Beyond traditional mechanisms of approaching information to readers (e.g. caching and mirroring), this system enables the publication, classification and subscription to volumes of objects (e.g. documents, events). Authors submit their contents to publication agents. Classification authorities provide classification schemes to classify objects. Readers subscribe to topics or authors, and retrieve contents from their local delivery agent (like a kiosk or library, with local copies of objects). Object distribution is an independent process where objects circulate asynchronously among distribution agents. ODS is designed to perform specially well in an increasingly populated, widespread and complex Internet jungle, using weak consistency replication by object distribution, asynchronous replication, and local access to objects by clients. ODS is based on two independent virtual networks, one dedicated to the distribution (replication) of objects and the other to calculate optimised distribution chains to be applied by the first network
A Taxonomy of Data Grids for Distributed Data Sharing, Management and Processing
Data Grids have been adopted as the platform for scientific communities that
need to share, access, transport, process and manage large data collections
distributed worldwide. They combine high-end computing technologies with
high-performance networking and wide-area storage management techniques. In
this paper, we discuss the key concepts behind Data Grids and compare them with
other data sharing and distribution paradigms such as content delivery
networks, peer-to-peer networks and distributed databases. We then provide
comprehensive taxonomies that cover various aspects of architecture, data
transportation, data replication and resource allocation and scheduling.
Finally, we map the proposed taxonomy to various Data Grid systems not only to
validate the taxonomy but also to identify areas for future exploration.
Through this taxonomy, we aim to categorise existing systems to better
understand their goals and their methodology. This would help evaluate their
applicability for solving similar problems. This taxonomy also provides a "gap
analysis" of this area through which researchers can potentially identify new
issues for investigation. Finally, we hope that the proposed taxonomy and
mapping also helps to provide an easy way for new practitioners to understand
this complex area of research.Comment: 46 pages, 16 figures, Technical Repor
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