Search results for "Probability density function"
showing 10 items of 183 documents
A novel active contour model for unsupervised low-key image segmentation
2013
Published version of an article in the journal: Central European Journal of Engineering. Also available from the publisher at: http://dx.doi.org/10.2478/s13531-012-0050-0 Unsupervised image segmentation is greatly useful in many vision-based applications. In this paper, we aim at the unsupervised low-key image segmentation. In low-key images, dark tone dominates the background, and gray level distribution of the foreground is heterogeneous. They widely exist in the areas of space exploration, machine vision, medical imaging, etc. In our algorithm, a novel active contour model with the probability density function of gamma distribution is proposed. The flexible gamma distribution gives a bet…
The Riemann sum method for the design of sum-of-cisoids simulators for Rayleigh fading channels in non-isotropic scattering environments
2009
©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Article also available from publisher: http://dx.doi.org/10.1109/ICUMT.2009.5345371 In this paper, we introduce the Riemann sum method (RSM) as an effective tool for the design of sum-of-cisoids (SOC) simulators for narrowband mobile Rayleigh fading channels under non-isotropic scattering conditions. We show that the RSM results in an excellent approximation of…
A Study of the Influence of Shadowing on the Statistical Properties of the Capacity of Mobile Radio Channels
2008
Article from the journal: Wireless Personal Communications The original publication is available at www.springerlink.com : http://dx.doi.org/10.1007/s11277-008-9545-7 This paper studies the influence of shadowing on the statistical properties of the channel capacity. The problem is addressed by using a Suzuki process as an appropriate statistical channel model for land mobile terrestrial channels. Using this model, exact solutions for the probability density function (PDF), cumulative distribution function (CDF), level-crossing rate (LCR), and average duration of fades (ADF) of the channel capacity are derived. The results are studied for different levels of shadowing, corresponding to diff…
Nonstationary response envelope probability densities of nonlinear oscillators
2006
The nonstationary random response of a class of lightly damped nonlinear oscillators subjected to Gaussian white noise is considered. An approximate analytical method for determining the response envelope statistics is presented. Within the framework of stochastic averaging, the procedure relies on the Markovian modeling of the response envelope process through the definition of an equivalent linear system with response-dependent parameters. An approximate solution of the associated Fokker-Planck equation is derived by resorting to a Galerkin scheme. Specifically, the nonstationary probability density function of the response envelope is expressed as the sum of a time-dependent Rayleigh dis…
Simplified Hybrid PD Model in Voids
2011
In this paper a novel approach to model partial discharges (PD) activity taking place inside a spherical void in epoxy resin system has been traced. The approach is based on a time varying conductance of the inner void, subjected to multistress conditions: voltage, temperature and pressure. A simple lumped circuit macro-model simulates the global effects of PD activity: the different parameters influencing the discharge phenomenon in the void are taking into account by using a physical approach resulting in a time varying conductance inside the circuit. The evaluated PD activity has been compared with experimental and simulated one for the accessible and inaccessible part of the system. A d…
Simplified hybrid PD model in voids: Pattern validation
2013
The purpose of the present work is to show the validation of a new model to simulate the physical phenomenon of partial discharge (PD) produced in air voids inside insulating epoxy resin. The model has been developed on the basis of a new approach that combines the known circuit model of three capacitors with a model used to describe the behavior of the ionized channel inside of the inclusion during the discharge phenomenon, short-circuiting the capacity that represents the void. The approach is based on time-variable conductance of the void, subjected to multistress conditions: voltage, temperature and pressure. The new approach has been developed from a time variable conductivity model us…
A BMA Analysis to Assess the Urbanization and Climate Change Impact on Urban Watershed Runoff
2016
Abstract A reliable planning of urban drainage systems aimed at the mitigation of flooding, should take into account the possible change over time of impervious cover in the urban watershed and of the climate features. The present study proposes a methodology to analyze the changing in runoff response for a urban watershed accounting several plausible future states of new urbanization and climate. To this aim, several models simulating the evolution scenario of impervious watershed area and of climate change were adopted. However, it is known that an evolution scenario represents only one of all possible occurrence and it is not necessary the true future state, therefore it is needed to fin…
Joint probability distributions for wind speed and direction. A case study in Sicily
2015
In this study we analyze data of hourly average wind speed and direction measured at three different sampling stations located in Sicily (Italy) and provide a statistical model for their joint probability density function. Singly truncated from below Normal Weibull mixture distribution and a linear combination of von Mises distributions are used to model wind speed and direction. Sites with heterogeneous local conditions (prevailing wind direction and/or elevation) have been considered in order to investigate the reliability of the model here taken into consideration.
Solving chance constrained optimal control problems in aerospace via Kernel Density Estimation
2017
International audience; The goal of this paper is to show how non-parametric statistics can be used to solve some chance constrained optimization and optimal control problems. We use the Kernel Density Estimation method to approximate the probability density function of a random variable with unknown distribution , from a relatively small sample. We then show how this technique can be applied and implemented for a class of problems including the God-dard problem and the trajectory optimization of an Ariane 5-like launcher.
Psychophysical response to electrocutaneous stimulation.
1984
A method is presented to determine a reliable stimulus-sensation relationship particularly suitable for electrocutaneous stimulation. An experimental intensity-discrimination curve was obtained through simple psychophysical comparison tasks, and sensory response was inferred from integration of a JND's density function. The psychophysical response resembles a power law, although departures cannot be described in terms of a unique exponent. An estimate of binary information capacity per electrode is also given as a feature of a stimulation procedure that preserves a low value of the size-intensity product.