5,741 research outputs found
Application of logistic regression to simulate the influence of rainfall genesis on storm overflow operations: a probabilistic approach
Abstract. One of the key parameters constituting the basis for the
operational assessment of stormwater systems is the annual number of storm
overflows. Since uncontrolled overflows are a source of pollution washed
away from the surface of the catchment area, which leads to imbalanced
receiving waters, there is a need for their prognosis and potential
reduction. The paper presents a probabilistic model for simulating the
annual number of storm overflows. In this model, an innovative solution is
to use the logistic regression method to analyze the impact of rainfall
genesis on the functioning of a storm overflow (OV) in the example of a catchment
located in the city of Kielce (central Poland). The developed model consists of two independent elements. The first element
of the model is a synthetic precipitation generator, in which the simulation
of rainfall takes into account its genesis resulting from various processes
and phenomena occurring in the troposphere. This approach makes it possible
to account for the stochastic nature of rainfall in relation to the annual
number of events. The second element is the model of logistic regression,
which can be used to model the storm overflow resulting from the occurrence
of a single rainfall event. The paper confirmed that storm overflow can be
modeled based on data on the total rainfall and its duration. An
alternative approach was also proposed, providing the possibility of
predicting storm overflow only based on the average rainfall intensity.
Substantial simplification in the simulation of the phenomenon under study
was achieved compared with the works published in this area to date. It is
worth noting that the coefficients determined in the logit models have a
physical interpretation, and the universal character of these models
facilitates their easy adaptation to other examined catchment areas. The calculations made in the paper using the example of the examined
catchment allowed for an assessment of the influence of rainfall characteristics
(depth, intensity, and duration) of different genesis on the probability of
storm overflow. Based on the obtained results, the range of the variability
of the average rainfall intensity, which determines the storm overflow, and
the annual number of overflows resulting from the occurrence of rain of
different genesis were defined. The results are suited for the
implementation in the assessment of storm overflows only based on the
genetic type of rainfall. The results may be used to develop warning systems
in which information about the predicted rainfall genesis is an element of
the assessment of the rainwater system and its facilities. This approach is
an original solution that has not yet been considered by other researchers.
On the other hand, it represents an important simplification and an
opportunity to reduce the amount of data to be measured
Real estate appraisals with Bayesian approach and Markov Chain Hybrid Monte Carlo Method: An application to a central urban area of Naples
This paper experiments an artificial neural networks model with Bayesian approach on a small real estate sample. The output distribution has been calculated operating a numerical integration on the weights space with the Markov Chain Hybrid Monte Carlo Method (MCHMCM). On the same real estate sample, MCHMCM has been compared with a neural networks model (NNs), traditional multiple regression analysis (MRA) and the Penalized Spline Semiparametric Method (PSSM). All four methods have been developed for testing the forecasting capacity and reliability of MCHMCM in the real estate field. The Markov Chain Hybrid Monte Carlo Method has proved to be the best model with an absolute average percentage error of 6.61%
On the Parity Problem in One-Dimensional Cellular Automata
We consider the parity problem in one-dimensional, binary, circular cellular
automata: if the initial configuration contains an odd number of 1s, the
lattice should converge to all 1s; otherwise, it should converge to all 0s. It
is easy to see that the problem is ill-defined for even-sized lattices (which,
by definition, would never be able to converge to 1). We then consider only odd
lattices.
We are interested in determining the minimal neighbourhood that allows the
problem to be solvable for any initial configuration. On the one hand, we show
that radius 2 is not sufficient, proving that there exists no radius 2 rule
that can possibly solve the parity problem from arbitrary initial
configurations. On the other hand, we design a radius 4 rule that converges
correctly for any initial configuration and we formally prove its correctness.
Whether or not there exists a radius 3 rule that solves the parity problem
remains an open problem.Comment: In Proceedings AUTOMATA&JAC 2012, arXiv:1208.249
Mesoscopic Casimir forces from effects of discrete particle number in the quantum vacuum
Traditionally it is assumed that the Casimir vacuum pressure does not depend
on the ultraviolet cut-off. There are, however, some arguments that the effect
actually depends on the regularization procedure and thus on the
trans-Planckian physics. We provide the condensed matter example where the
Casimir forces do explicitly depend on the microscopic (correspondingly
trans-Planckian) physics due to the mesoscopic finite-N effects, where N is the
number of bare particles in condensed matter (or correspondingly the number of
the elements comprising the quantum vacuum). The finite-N effects lead to
mesoscopic fluctuations of the vacuum pressure. The amplitude of the mesoscopic
flustuations of the Casimir force in a system with linear dimension L is larger
by the factor N^{1/3}\sim L/a than the traditional value of the Casimir force
given by effective theory, where a is the interatomic distance which plays the
role of the Planck length.Comment: LaTeX file, 13 pages, no figures, submitted to JETP Letter
Accelerated detectors in Dirac vacuum: the effects of horizon fluctuations
We consider an Unruh-DeWitt detector interacting with a massless Dirac field.
Assuming that the detector is moving along an hyperbolic trajectory, we modeled
the effects of fluctuations in the event horizon using a Dirac equation with
random coefficients. First, we develop the perturbation theory for the
fermionic field in a random media. Further we evaluate corrections due to the
randomness in the response function associated to different model detectors.Comment: 19 pages, 1 figur
Ordering Quantiles through Confidence Statements
Ranking variables according to their relevance to predict an outcome is an important task in biomedicine. For instance, such ranking can be used for selecting a smaller number of genes for then applying other sophisticated experiments only on genes identified as important. A nonparametric method called Quor is designed to provide a confidence value for the order of arbitrary quantiles of different populations using independent samples. This confidence may provide insights about possible differences among groups and yields a ranking of importance for the variables. Computations are efficient and use exact distributions with no need for asymptotic considerations. Experiments with simulated data and with multiple real -omics data sets are performed, and they show advantages and disadvantages of the method. Quor has no assumptions but independence of samples, thus it might be a better option when assumptions of other methods cannot be asserted. The software is publicly available on CRAN
Light-cone fluctuations and the renormalized stress tensor of a massless scalar field
We investigate the effects of light-cone fluctuations over the renormalized
vacuum expectation value of the stress-energy tensor of a real massless
minimally coupled scalar field defined in a ()-dimensional flat space-time
with topology . For modeling the influence of
light-cone fluctuations over the quantum field, we consider a random
Klein-Gordon equation. We study the case of centered Gaussian processes. After
taking into account all the realizations of the random processes, we present
the correction caused by random fluctuations. The averaged renormalized vacuum
expectation value of the stress-energy associated with the scalar field is
presented
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