Search results for "Sampling"

An improved sampling strategy based on trajectory design for application of the Morris method to systems with many input factors

2012

[EN] In this paper, a revised version of the Morris approach, which includes an improved sampling strategy based on trajectory design, has been adapted to the screening of the most influential parameters of a fuzzy controller applied to WWTPs. Due to the high number of parameters, a systematic approach has been proposed to apply this improved sampling strategy with low computational demand. In order to find out the proper repetition number of elementary effects of each input factor on model output (EEi) calculations, an iterative and automatic procedure has been applied. The results show that the sampling strategy has a significant effect on the parameter significance ranking and that rando…

Cross-entropy-based adaptive optimization of simulation parameters for Markovian-driven service systems

2005

Abstract Markov fluid models represent a general description of the process of service request arrivals to service systems. The solution of performance analysis problems incorporating them often calls for a simulation approach, for which a reference methodology is Importance Sampling. However, in this case the appropriate choice of the biasing conditions is a problem in itself. In this paper an iterative method based on the cross-entropy is proposed for this choice. The equations are given that allow to derive the biasing conditions from the simulation itself. The application of the proposed method to three different sample cases, referring to one transient scenario (finite time horizon and…

A Quick Simulation Technique for a Fluid Information Storage Problem

2001

Summary In this paper we present an application of Importance Sampling (IS) for quick simulation of buffer overflow probability in a statistical multiplexer loaded with a number of independent Markov modulated fluid sources. Runtime improvement is deducible from NMCσ2(p) and NISσ2(p*) that characterize the trade-offs between sample size and variance of the estimators of buffer overflow probability experienced in Monte Carlo (MC) and Importance Sampling simulations. By assuming that the same precision is achieved for the two kinds of simulations if σ2(p)=σ2(p*), an approximate closed form expression for the ratio NIS/NMC is derived, and it is minimized with respect to the load of the multipl…

Anti-tempered Layered Adaptive Importance Sampling

2017

Monte Carlo (MC) methods are widely used for Bayesian inference in signal processing, machine learning and statistics. In this work, we introduce an adaptive importance sampler which mixes together the benefits of the Importance Sampling (IS) and Markov Chain Monte Carlo (MCMC) approaches. Different parallel MCMC chains provide the location parameters of the proposal probability density functions (pdfs) used in an IS method. The MCMC algorithms consider a tempered version of the posterior distribution as invariant density. We also provide an exhaustive theoretical support explaining why, in the presented technique, even an anti-tempering strategy (reducing the scaling of the posterior) can …

A New Reference Material and Safe Sampling of Terrorists Peroxide Explosives by a Non-Volatile Matrix

2015

Stabilization of discrete-time systems with stochastic sampling

2012

This paper is concerned with the stabilization problem of discrete-time systems with stochastic sampling. It is assumed that there are a single-rate sampling in the plant input and two stochastic sampling rates in the controller input whose occurrence probabilities are given constants and satisfy a Bernoulli distribution. By Lyapunov function approach, a new sufficient condition is presented for the mean square asymptotic stability of the system. Based on this, the design procedure for stabilization controllers is proposed. Finally, an example is given to demonstrate the effectiveness of the proposed techniques.

<p>Preoperative Anemia and Iron Deficiency Screening, Evaluation and Management: Barrier Identification and Implementation Strategy Mapping<…

2020

Introduction and aims: Patients undergoing major surgery risk significant blood loss and transfusion, which increases substantially if they have pre-existing anemia. Preoperative Anemia and Iron Deficiency Screening, Evaluation and Management Pathways (PAIDSEM-P) outline recommended blood tests and treatment to optimize patients before surgery. Documented success using PAIDSEM-P to reduce transfusions and improve patient outcomes exists, but the reporting quality of such studies is suboptimal. It remains unclear what implementation strategies best support the implementation of PAIDSEM-P. Method: Maximum variation, purposive sampling was used to recruit a total of 15 partici-pants, including…

Comparing cetacean abundance estimates derived from spatial models and design-based line transect methods

2007

Spatial modelling is increasingly being used as an alternative to conventional design- based line transect sampling to estimate cetacean abundance. This new method combines line transect sampling with spatial analysis to predict animal abundance based on the relationship of ani- mals observed to environmental factors. It presents several advantages including: (1) the ability to use data collected from 'platforms of opportunity', (2) the ability to estimate abundance for any defined subarea within the study area, and (3) the possibility for increased precision if covariates explain sufficient variability in the data. One study has been conducted to compare spatial modelling with conventional…

Comparing different methods to determine soil physical quality in a mediterranean forest and pasture land

2016

Soil physical quality (SPQ) can be assessed by different experimental methodologies and criteria and the optimal/critical values or ranges for SPQ indicators are still approximate. Sampling soils with minimal anthropic pressures should allow improvements in SPQ assessment. Different experimental methodologies and criteria were applied to sample a Mediterranean oak forest (Quercus ilex L.) and pasture land, in Sicily, with a varying degree of anthropic disturbance. Soil water retention was determined in the laboratory and the field, using the BEST (Beerkan Estimation of Soil Transfer parameters) procedure of soil hydraulic characterization. Capacity-based indicators, the S index, and locatio…

FIR Kramers–Kronig transformers for relaxation data conversion

2006

It is shown that relaxation data conversion by the Kramers-Kronig (KK) relations can be treated as a filtering problem of band-unlimited relaxation signals in the Mellin transform domain. Based on this concept, KK relations are implemented in the form of FIR filters with the logarithmic sampling. It is demonstrated that KK transformers have sampling rate dependent impulse and frequency responses and only calculation of the imaginary part from the real part can be implemented by a computationally realisable filter. The performance of different types of transformers is studied.Approximately inversely proportional relationship is established between the error and the frequency range of input s…