Search results for "probability"
showing 10 items of 3417 documents
Legri Instrument Health. A Historical Review
2001
LEGRI has been operating successfully on MINISAT-01 since its switch-on the 22nd of May 1997. HouseKeeping (HK) data have been continuously received for nearly two years by LEGRI SOC in Valencia, and subsequently checked on a daily basis and then stored for long term monitoring analysis. LEGRI HouseKeeping data include three critical operating parameters: temperature, power and polarisation voltages. Six temperature sensors are spread over the different LEGRI units: Detector Unit, Data Processing Unit, High Voltage Unit and Star Sensor. Voltages are measured at eight different points. Detector Unit temperature and polarisation voltage are the critical parameters for LEGRI operation. Solid s…
A Bayesian Learning Automaton for Solving Two-Armed Bernoulli Bandit Problems
2008
The two-armed Bernoulli bandit (TABB) problem is a classical optimization problem where an agent sequentially pulls one of two arms attached to a gambling machine, with each pull resulting either in a reward or a penalty. The reward probabilities of each arm are unknown, and thus one must balance between exploiting existing knowledge about the arms, and obtaining new information. In the last decades, several computationally efficient algorithms for tackling this problem have emerged, with learning automata (LA) being known for their ?-optimality, and confidence interval based for logarithmically growing regret. Applications include treatment selection in clinical trials, route selection in …
Search for the Rare Leptonic Decay B+→μ+νμ
2004
A search for the rare leptonic decay with data collected at the resonance by the BABAR experiment was carried out. The decay rate was sensitive to the product of the Cabibbo Kobayashi Maskawa matrix element (Vub and the B decay constant fb, which was propotional to the wave function for zero separation between the quarks. The data used in the analysis was collectd with BABAR detector at the PEP-II storage ring and the sample consisted of an integrity luminosity of 81.4 fb-1. The systematic uncertainty in the signal efficiency was evaluated which included the muon candidate selection and the reconstruction efficiency of the companion B.
Search for flavor-changing neutral current and lepton-flavor violating decays of D-0 -> l(+)l(-)
2004
We report on a search for the flavor-changing neutral current decays $\Dz\to e^+e^-$ and $\Dz\to\mu^+\mu^-$, and the lepton-flavor violating decay $\Dz\to e^\pm\mu^\mp$. The measurement is based on $122 {fb}^{-1}$ of data collected by the \babar detector at the PEP-II asymmetric $e^+e^-$ collider. No evidence is found for any of the decays. The upper limits on the branching fractions, at the 90 % confidence level, are $1.2\times 10^{-6}$ for $\Dz\to e^+e^-$, $1.3\times 10^{-6}$ for $\Dz\to\mu^+\mu^-$, and $8.1\times 10^{-7}$ for $\Dz\to e^\pm\mu^\mp$.
Comparing Boosting and Bagging for Decision Trees of Rankings
2021
AbstractDecision tree learning is among the most popular and most traditional families of machine learning algorithms. While these techniques excel in being quite intuitive and interpretable, they also suffer from instability: small perturbations in the training data may result in big changes in the predictions. The so-called ensemble methods combine the output of multiple trees, which makes the decision more reliable and stable. They have been primarily applied to numeric prediction problems and to classification tasks. In the last years, some attempts to extend the ensemble methods to ordinal data can be found in the literature, but no concrete methodology has been provided for preference…
Multicriteria Decision Analysis for Choosing the Remediation Method for a Landfill Based on Mixed Ordinal and Cardinal Information
2009
We describe a real-life application of a multicriteria method in the context of remediating a landfill in Finland. The landfill was used for dumping industrial waste during the years 1950 to 1965. During that time many harmful chemicals were stored in landfills among other waste. Therefore, this—and possibly several other—landfills have to be remediated. In this application, seven different remediation options were evaluated based on 13 criteria. For some criteria, cardinal measures with associated uncertainties were obtained. For other criteria, only ordinal (ranking) information was available. The problem was analyzed using the Stochastic Multicriteria Acceptability Analysis with Ordinal …
Correlation, hierarchies, and networks in financial markets
2010
We discuss some methods to quantitatively investigate the properties of correlation matrices. Correlation matrices play an important role in portfolio optimization and in several other quantitative descriptions of asset price dynamics in financial markets. Specifically, we discuss how to define and obtain hierarchical trees, correlation based trees and networks from a correlation matrix. The hierarchical clustering and other procedures performed on the correlation matrix to detect statistically reliable aspects of the correlation matrix are seen as filtering procedures of the correlation matrix. We also discuss a method to associate a hierarchically nested factor model to a hierarchical tre…
Sense of coherence and work characteristics: A cross-lagged structural equation model among managers
2004
This study investigated the dominance of predictive relationships between Sense of Coherence (SOC) and work characteristics (organizational climate and job control) in cross-lagged longitudinal data with two measurement points and a time lag of 3 years. The sample consisted of 615 (587 men and 28 women) managers, aged between 27 and 64 years. The cross-lagged longitudinal analysis was done by the use of Structural Equation Modelling (SEM) within the framework by LISREL. The results of the chi-square difference tests indicated that the model where SOC at Time 1 predicted work characteristics at Time 2 better accounted for the data than the competitive models. However, the only significant pa…
Probabilistic Fuzzy Approach to Evaluation of Logistics Service Effectiveness
2014
Received: 9 September 2014 Abstract Accepted: 11 October 2014 Logistics service providers offer a whole or partial logistics business service over a certain time period. Between such companies, the effectiveness of specific logistics services can vary. Logistics service providers seek the effective performance of logistics service. The purpose of this paper is to present a new approach for the evaluation of logistics service effectiveness, along with a specific computer system implementing the proposed approach – a sophisticated inference system, an extension of the Mamdani probabilistic fuzzy system. The paper presents specific knowledge concerning the relationships between effectiveness i…
Multi-wave, multi-variable models of job insecurity: applying different scales in studying the stability of job insecurity
2001
The study had two specific targets: first, to examine the stability of job insecurity by utilizing three-year longitudinal data (n = 109) collected in Finland and, second, to clarify psychometric properties of four job insecurity scales, i.e., the global scale, the importance scale, the probability scale and the powerlessness scale. The study was carried out by means of questionnaires, which were answered on three occasions. Analyses were conducted using multi-wave, multi-variable models which were estimated and tested via the LISREL program. Generally, the results showed that job insecurity remained relatively stable during the follow-up period, although there were some variations in the s…