Search results for "Multivariable"
showing 10 items of 39 documents
Control zeros and nonminimum phase LTI mimo systems
1999
Abstract The paper presents a new, general, inverse-model/output-zeroing approach to zeros of LTI discrete-time multivariable, possibly nonsquare systems. It is shown on simple examples that the existing definitions of multivariable zeros fail to detect certain important zeros which contribute to zeroing the system output. As a result, a concept of ‘control zeros’ is introduced, followed by a general redefinition of minimum/nonminimum phase systems, both new contributions being based on the notion of (generalized) inverse systems. Output-zeroing/inverse-model/minimum-variance control-related justifications of the new approach are presented.
Transforming RNA-Seq Data to Improve the Performance of Prognostic Gene Signatures
2014
Gene expression measurements have successfully been used for building prognostic signatures, i.e for identifying a short list of important genes that can predict patient outcome. Mostly microarray measurements have been considered, and there is little advice available for building multivariable risk prediction models from RNA-Seq data. We specifically consider penalized regression techniques, such as the lasso and componentwise boosting, which can simultaneously consider all measurements and provide both, multivariable regression models for prediction and automated variable selection. However, they might be affected by the typical skewness, mean-variance-dependency or extreme values of RNA-…
The Association between Loneliness and Health Related Quality of Life (HR-QoL) among Community-Dwelling Older Citizens
2020
Background: This study aimed to assess the association between loneliness and Health-Related Quality of Life (HR-QoL) among community-dwelling older citizens in five European countries. We characterize loneliness broadly from an emotional and social perspective. Methods: This cross-sectional study measured loneliness with the 6-item De Jong Gierveld Loneliness Scale and HR-QoL with the 12-Item Short-Form Health Survey. The association between loneliness and HR-QoL was examined using multivariable linear regression models. Results: Data of 2169 citizens of at least 70 years of age and living independently (mean age = 79.6 ±
Sedentary behavior and perceived stress among adults aged ≥50 years in six low- and middle-income countries.
2018
Background:\ud Sedentary behavior and perceived stress are both negatively associated with physical and mental health. Little is known about the association between sedentary behavior and \ud perceived stress, and there is a particular paucity of data on people aged ≥50 years from low- and middle-income countries (LMICs). \ud Methods:\ud We analyzed cross-sectional, community-based data from 34,129 individuals aged ≥50 years [mean age 62.4 (SD=16.0) years, 52% females] from six LMICs. Perceived stress was assessed using the Perceived Stress Scale and time spent sedentary per day was self-reported. Multivariable linear regression analyses were conducted, adjusting for important socio economi…
Empirical study of the dependence of the results of multivariable flexible survival analyses on model selection strategy
2008
Flexible survival models, which avoid assumptions about hazards proportionality (PH) or linearity of continuous covariates effects, bring the issues of model selection to a new level of complexity. Each ‘candidate covariate’ requires inter-dependent decisions regarding (i) its inclusion in the model, and representation of its effects on the log hazard as (ii) either constant over time or time-dependent (TD) and, for continuous covariates, (iii) either loglinear or non-loglinear (NL). Moreover, ‘optimal’ decisions for one covariate depend on the decisions regarding others. Thus, some efficient model-building strategy is necessary. We carried out an empirical study of the impact of the model …
Studying students ́satisfaction at music schools in the Valencian Region
2017
[EN] Satisfaction is a key construct but complex to be measured. Within the cultural context and from the discipline of marketing, satisfaction consists of assessing some experiences without considering consumers ́ expectations. From this approach, this paper deals with an empirical research aiming at analyzing satisfaction among students of music conservatoires and schools. The research, qualitative and quantitative in nature, allowed to know users ́ assessment of different variables: studies, teaching staff, information technologies, premises and administration procedures. To do so, a self-administered survey was conducted using a structured questionnaire. Univariate and multivariate anal…
Multivariate Exploratory Comparative Analysis of LaLiga Teams: Principal Component Analysis
2021
The use of principal component analysis (PCA) provides information about the main characteristics of teams, based on a set of indicators, instead of displaying individualized information for each of these indicators. In this work we have considered reducing an extensive data matrix to improve interpretation, using PCA. Subsequently, with new components and with multiple linear regression, we have carried out a comparative analysis between the best and bottom teams of LaLiga. The sample consisted of the matches corresponding to the 2015/16, 2016/17 and 2017/18 seasons. The results showed that the best teams were characterized and differentiated from bottom teams in the realization of a great…
Robust regulation with an H<inf>&#x221E;</inf> constrain for linear two-time scale systems
2010
In this paper, the problem of robust multi-objective control design with an H ∞ constrain is studied for a class of linear two-time scale systems. The design is based on a new modelling approach under the assumption of norm-boundedness of the fast dynamics. In this method, a portion of the fast dynamics is treated as a norm-bounded perturbation in the design by its maximum possible gain. In this view, the problem of robust multi-objective control design is performed only for the certain dynamics of the two-time scale system, whose order is less than that of the original system. One illustrative example is used to demonstrate the validity of the proposed approach.
A physical approach to the connection between fractal geometry and fractional calculus
2014
Our goal is to prove the existence of a connection between fractal geometries and fractional calculus. We show that such a connection exists and has to be sought in the physical origins of the power laws ruling the evolution of most of the natural phenomena, and that are the characteristic feature of fractional differential operators. We show, with the aid of a relevant example, that a power law comes up every time we deal with physical phenomena occurring on a underlying fractal geometry. The order of the power law depends on the anomalous dimension of the geometry, and on the mathematical model used to describe the physics. In the assumption of linear regime, by taking advantage of the Bo…
Development of the microwave transduction applied to ammonia detection : from nanomaterials to broadband sensor, understanding of the mechanisms and …
2017
The main objective of this thesis is to propose an analysis of the microwave transduction specificities in the framework of ammonia sensing applications. The two main features of this transduction are its broadband characterization (1 to 8 GHz) as well as its sensitive materials (dielectrics). This transduction method is based on the interaction between a polluting gas and a sensitive material deposited on the surface of a microwave-specific propagating structure. The response of the sensor is not directly induced by the dielectric properties of the gaseous target molecule, but rather by those of the target species adsorbed on the surface of the sensitive material. This adsorption causes a …