143,345 research outputs found
Correction. Brownian models of open processing networks: canonical representation of workload
Due to a printing error the above mentioned article [Annals of Applied
Probability 10 (2000) 75--103, doi:10.1214/aoap/1019737665] had numerous
equations appearing incorrectly in the print version of this paper. The entire
article follows as it should have appeared. IMS apologizes to the author and
the readers for this error. A recent paper by Harrison and Van Mieghem
explained in general mathematical terms how one forms an ``equivalent workload
formulation'' of a Brownian network model. Denoting by the state vector
of the original Brownian network, one has a lower dimensional state descriptor
in the equivalent workload formulation, where can be chosen as
any basis matrix for a particular linear space. This paper considers Brownian
models for a very general class of open processing networks, and in that
context develops a more extensive interpretation of the equivalent workload
formulation, thus extending earlier work by Laws on alternate routing problems.
A linear program called the static planning problem is introduced to articulate
the notion of ``heavy traffic'' for a general open network, and the dual of
that linear program is used to define a canonical choice of the basis matrix
. To be specific, rows of the canonical are alternative basic optimal
solutions of the dual linear program. If the network data satisfy a natural
monotonicity condition, the canonical matrix is shown to be nonnegative,
and another natural condition is identified which ensures that admits a
factorization related to the notion of resource pooling.Comment: Published at http://dx.doi.org/10.1214/105051606000000583 in the
Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute
of Mathematical Statistics (http://www.imstat.org
View Selection in Semantic Web Databases
We consider the setting of a Semantic Web database, containing both explicit
data encoded in RDF triples, and implicit data, implied by the RDF semantics.
Based on a query workload, we address the problem of selecting a set of views
to be materialized in the database, minimizing a combination of query
processing, view storage, and view maintenance costs. Starting from an existing
relational view selection method, we devise new algorithms for recommending
view sets, and show that they scale significantly beyond the existing
relational ones when adapted to the RDF context. To account for implicit
triples in query answers, we propose a novel RDF query reformulation algorithm
and an innovative way of incorporating it into view selection in order to avoid
a combinatorial explosion in the complexity of the selection process. The
interest of our techniques is demonstrated through a set of experiments.Comment: VLDB201
Scheduling of data-intensive workloads in a brokered virtualized environment
Providing performance predictability guarantees is increasingly important in cloud platforms, especially for data-intensive applications, for which performance depends greatly on the available rates of data transfer between the various computing/storage hosts underlying the virtualized resources assigned to the application. With the increased prevalence of brokerage services in cloud platforms, there is a need for resource management solutions that consider the brokered nature of these workloads, as well as the special demands of their intra-dependent components. In this paper, we present an offline mechanism for scheduling batches of brokered data-intensive workloads, which can be extended to an online setting. The objective of the mechanism is to decide on a packing of the workloads in a batch that minimizes the broker's incurred costs, Moreover, considering the brokered nature of such workloads, we define a payment model that provides incentives to these workloads to be scheduled as part of a batch, which we analyze theoretically. Finally, we evaluate the proposed scheduling algorithm, and exemplify the fairness of the payment model in practical settings via trace-based experiments
Evaluation of the organisation and delivery of patient-centred acute nursing care
In 2002, a team of researchers from the School of Nursing, University of Salford were commissioned by Bolton Hospitals NHS Trust to evaluate the delivery and organisation of patient-centred nursing care across the acute nursing wards within the Royal Bolton Hospital.
The key driver for the commissioning of this study arose from two serious untoward incidents that occurred in the year 2000. Following investigation of both these events the Director of Nursing in post at that time believed that poor organisation and delivery of care may have been a contributory factor. Senior nurses in the Trust had also expressed their concern that care may not be organised in a way that made best use of the skills available
Enabling Quality Control for Entity Resolution: A Human and Machine Cooperation Framework
Even though many machine algorithms have been proposed for entity resolution,
it remains very challenging to find a solution with quality guarantees. In this
paper, we propose a novel HUman and Machine cOoperation (HUMO) framework for
entity resolution (ER), which divides an ER workload between the machine and
the human. HUMO enables a mechanism for quality control that can flexibly
enforce both precision and recall levels. We introduce the optimization problem
of HUMO, minimizing human cost given a quality requirement, and then present
three optimization approaches: a conservative baseline one purely based on the
monotonicity assumption of precision, a more aggressive one based on sampling
and a hybrid one that can take advantage of the strengths of both previous
approaches. Finally, we demonstrate by extensive experiments on real and
synthetic datasets that HUMO can achieve high-quality results with reasonable
return on investment (ROI) in terms of human cost, and it performs considerably
better than the state-of-the-art alternatives in quality control.Comment: 12 pages, 11 figures. Camera-ready version of the paper submitted to
ICDE 2018, In Proceedings of the 34th IEEE International Conference on Data
Engineering (ICDE 2018
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