10,580 research outputs found
Automating Fine Concurrency Control in Object-Oriented Databases
Several propositions were done to provide adapted concurrency control to
object-oriented databases. However, most of these proposals miss the fact that
considering solely read and write access modes on instances may lead to less
parallelism than in relational databases! This paper cope with that issue, and
advantages are numerous: (1) commutativity of methods is determined a priori
and automatically by the compiler, without measurable overhead, (2) run-time
checking of commutativity is as efficient as for compatibility, (3) inverse
operations need not be specified for recovery, (4) this scheme does not
preclude more sophisticated approaches, and, last but not least, (5) relational
and object-oriented concurrency control schemes with read and write access
modes are subsumed under this proposition
CSL model checking of Deterministic and Stochastic Petri Nets
Deterministic and Stochastic Petri Nets (DSPNs) are a widely used high-level formalism for modeling discrete-event systems where events may occur either without consuming time, after a deterministic time, or after an exponentially distributed time. The underlying process dened by DSPNs, under certain restrictions, corresponds to a class of Markov Regenerative Stochastic Processes (MRGP). In this paper, we investigate the use of CSL (Continuous Stochastic Logic) to express probabilistic properties, such a time-bounded until and time-bounded next, at the DSPN level. The verication of such properties requires the solution of the steady-state and transient probabilities of the underlying MRGP. We also address a number of semantic issues regarding the application of CSL on MRGP and provide numerical model checking algorithms for this logic. A prototype model checker, based on SPNica, is also described
MathMC: A mathematica-based tool for CSL model checking of deterministic and stochastic Petri nets
Deterministic and Stochastic Petri Nets (DSPNs) are a widely used high-level formalism for modeling discreteevent systems where events may occur either without consuming time, after a deterministic time, or after an exponentially distributed time. CSL (Continuous Stochastic Logic) is a (branching) temporal logic developed to express probabilistic properties in continuous time Markov chains (CTMCs). In this paper we present a Mathematica-based tool that implements recent developments for model checking CSL style properties on DSPNs. Furthermore, as a consequence of the type of process underlying DSPNs (a superset of Markovian processes), we are also able to check CSL properties of Generalized Stochastic Petri Nets (GSPNs) and labeled CTMCs
Software Engineering Timeline: major areas of interest and multidisciplinary trends
Ingeniería del software. EvolucionSociety today cannot run without software and by extension, without Software Engineering. Since this discipline emerged in 1968, practitioners have learned valuable lessons that have contributed to current practices. Some have become outdated but many are still relevant and widely used. From the personal and incomplete perspective of the authors, this paper not only reviews the major milestones and areas of interest in the Software Engineering timeline helping software engineers to appreciate the state of things, but also tries to give some insights into the trends that this complex engineering will see in the near future
Iceberg transport technologies in spatial competition. Hotelling reborn
Transport costs in address models of differentiation are usually modeled as separable of the consumption commodity and with a parametric price. However, there are many sectors in an economy where such modeling is not satisfactory either because transportation is supplied under oligopolistic conditions or because there is a difference (loss) between the amount delivered at the point of production and the amount received at the point of consumption. This paper is a first attempt to tackle these issues proposing to study competition in spatial models using an iceberg-like transport cost technology allowing for concave and convex melting functions.Spatial Competition, Iceberg transport costs
Investigations of the Surface Dielectric Function by Means of the Scanning Ellipsometry and Transition Radiation Methods
This paper was supported by the Project CPBP 01.08.We describe the scanning ellipsometry and transition radiation methods as well as their
applications to surface dielectric function measurements. In particular, we present the results for
a gadolinium sample in the visible and ultraviolet spectral ranges. We compare our experimental
results obtained by both methods.Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 zostało dofinansowane ze środków MNiSW w ramach działalności upowszechniającej naukę
Unscented Bayesian Optimization for Safe Robot Grasping
We address the robot grasp optimization problem of unknown objects
considering uncertainty in the input space. Grasping unknown objects can be
achieved by using a trial and error exploration strategy. Bayesian optimization
is a sample efficient optimization algorithm that is especially suitable for
this setups as it actively reduces the number of trials for learning about the
function to optimize. In fact, this active object exploration is the same
strategy that infants do to learn optimal grasps. One problem that arises while
learning grasping policies is that some configurations of grasp parameters may
be very sensitive to error in the relative pose between the object and robot
end-effector. We call these configurations unsafe because small errors during
grasp execution may turn good grasps into bad grasps. Therefore, to reduce the
risk of grasp failure, grasps should be planned in safe areas. We propose a new
algorithm, Unscented Bayesian optimization that is able to perform sample
efficient optimization while taking into consideration input noise to find safe
optima. The contribution of Unscented Bayesian optimization is twofold as if
provides a new decision process that drives exploration to safe regions and a
new selection procedure that chooses the optimal in terms of its safety without
extra analysis or computational cost. Both contributions are rooted on the
strong theory behind the unscented transformation, a popular nonlinear
approximation method. We show its advantages with respect to the classical
Bayesian optimization both in synthetic problems and in realistic robot grasp
simulations. The results highlights that our method achieves optimal and robust
grasping policies after few trials while the selected grasps remain in safe
regions.Comment: conference pape
Resilient Distributed Energy Management for Systems of Interconnected Microgrids
In this paper, distributed energy management of interconnected microgrids,
which is stated as a dynamic economic dispatch problem, is studied. Since the
distributed approach requires cooperation of all local controllers, when some
of them do not comply with the distributed algorithm that is applied to the
system, the performance of the system might be compromised. Specifically, it is
considered that adversarial agents (microgrids with their controllers) might
implement control inputs that are different than the ones obtained from the
distributed algorithm. By performing such behavior, these agents might have
better performance at the expense of deteriorating the performance of the
regular agents. This paper proposes a methodology to deal with this type of
adversarial agents such that we can still guarantee that the regular agents can
still obtain feasible, though suboptimal, control inputs in the presence of
adversarial behaviors. The methodology consists of two steps: (i) the
robustification of the underlying optimization problem and (ii) the
identification of adversarial agents, which uses hypothesis testing with
Bayesian inference and requires to solve a local mixed-integer optimization
problem. Furthermore, the proposed methodology also prevents the regular agents
to be affected by the adversaries once the adversarial agents are identified.
In addition, we also provide a sub-optimality certificate of the proposed
methodology.Comment: 8 pages, Conference on Decision and Control (CDC) 201
Lexicographical and Translation Issues in the Inclusion of English
This is a crossroads time for dictionaries in print in general and for bilingual dictionaries of Economics in printin particular. A time when the prevalence of information technologies supposedly makes access to specializedlexicographical information easier and faster. The present study first reviews briefly the current situation of bilingual dictionaries of Economics on paper and their viability in a near future. It then examines, with more detail, the specific lexicographical issue of incorporating (i.e. translating) English financial neonyms, which appear practically everyday in print and internet media, into English-Spanish/Spanish-English Dictionaries of Economics on paper, normally published in the lapse of years. This gap between the immediacy of the Internet and the delay of printing, seems to cause serious problems to bilingual lexicographers specialized in Economics especially when questionable translations of such neonyms are already circulating on the web. This, in addition to the ample presence of electronic glossaries and dictionaries, easily accessible by translators and professionals, but whose reliability, on the other hand, is not always guaranteed. Finally, a more active role is recommended to bilingual lexicographers in Economics by taking advantage of internet information media services and by joining efforts with finance experts and professionals
Financial statement analysis. Eurona Wireless Telecom S.A.
Treball Final de Grau en Finances i Comptabilitat. Codi: FC1049The main expectation of the present work has been to study, analyze, interpret and evaluate the company EURONA WIRELESS TELECOM S.A. from the system of analysis of financial statements. The objective was to know the current status of the company. To achieve this, all the information provided through the sources that attended it: annual accounts, web pages, as well as specific manuals of the subject have been collected. With these tools, the necessary mathematical calculations have been carried out that have led to the interpretation of the required conclusions. In this way, we have been able to achieve the pretension of the writing, and also have been established some hypotheses that attended to its possible future state
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