746 research outputs found
On the structure of a class of operators
In this dissertation we study certain classes of operators on a separable, complex,
in??nite dimensional Hilbert space H, speci??cally from the point of view of properties
of the hyperlattice (i.e., lattice of hyperinvariant subspaces) for such operators. We
show that every (BCP)-operator in C00 is hyperquasisimilar to a quasidiagonal (BCP)-
operator in C00. Moreover we show that there exists a ??xed block diagonal (BCP)-
operator Bu with the property that if every compact perturbation Bu + K of Bu in
(BCP) and C00 with kKk < " has a nontrivial hyperinvariant subspace, then every
nonscalar operator on H has a nontrivial hyperinvariant subspace. This shows that
the study of the structure of the hyperlattice of an arbitrary operator on Hilbert
space is essentially equivalent to the study of the hyperlattice structure of some much
smaller, special classes of operators, and it is these on which we concentrate.
Moreover, we study some special subclasses (B??) and (S??) of the class of in-
vertible (BCP)-operators with a view of obtaining some insight into the problem of
determining the structure of operators in these classes
Un modeĢle eĢleĢments finis geĢneĢral pour la preĢdiction des deĢfauts de planeĢiteĢ en laminage des toĢles fines
Titre du rĆ©sumĆ© en anglais joint : Manifested flatness predictions in thin strip cold rolling using a general rolling FEM modelNational audienceL'objectif du preĢsent travail est de deĢvelopper un modeĢle de laminage capable de preĢdire avec preĢcision les deĢfauts de planeĢiteĢ des toĢles lamineĢes. Ainsi, on a coupleĢ iteĢrativement un modeĢle eĢleĢments finis 3D de calcul de l'eĢcrasement de la toĢle dans l'emprise, un modeĢle semi-analytique de calcul de la deĢformation des cylindres de la cage et un modeĢle eĢleĢments finis de flambement de coques donnant les deĢfauts de planeĢiteĢ. Le modeĢle de laminage obtenu preĢdit des champs de contraintes en bon accord avec les mesures expeĢrimentales et est capable de simuler les deĢfauts de planeĢiteĢ en laminage des toĢles.See http://hal.archives-ouvertes.fr/docs/00/59/26/08/ANNEX/r_690NC59B.pd
Psychometric Evaluation of Dietary Habits Questionnaire for Type 2 Diabetes Mellitus
This research evaluated the psychometric properties of English version of dietary habits questionnaires developed for type 2 diabetic patients. There is scarcity of literature about availability of standardized questionnaires for assessing dietary habits of type 2 diabetics in
Saudi Arabia. As dietary habits vary from country to country, therefore, this was an attempt to develop questionnaires that can serve as a baseline. Through intensive literature review, four questionnaires were developed / modified and subsequently tested for psychometric properties. Prior to pilot study, a pre-test was conducted to evaluate the face validity and content validity. The pilot study was conducted from 23 October ā 22 November, 2016 to evaluate the questionnairesā reliability and validity. Systematic random sampling technique was used to collect the data from 132 patients by direct investigation method. Questionnaires assessing diabetes mellitus knowledge (0.891), dietary knowledge (0.869), dietary attitude (0.841) and dietary practices (0.874) had good internal consistency reliability. Factor analysis conducted on dietary attitude questionnaire showed a valid 5 factor solution. Directions of loadings were positive and free from factorial complexity. Relying on the data obtained from type 2 diabetics, these questionnaires can be considered as reliable and valid for the assessment of dietary habits in Saudi Arabia and neighbouring Gulf countries population
Effect of Diet on Type 2 Diabetes Mellitus: A Review
Globally, type 2 diabetes mellitus (T2DM) is considered as one of the most common diseases. The etiology of T2DM is complex and is associated with irreversible risk factors such as age, genetic, race, and ethnicity and reversible factors such as diet, physical activity and smoking. The objectives of this review are to examine various studies to explore relationship of T2DM with different dietary habits/patterns and practices and its complications. Dietary habits and sedentary lifestyle are the major factors for rapidly rising incidence of DM among developing countries. In type 2 diabetics, recently, elevated HbA1c level has also been considered as one of the leading risk factors for developing microvascular and macrovascular complications. Improvement in the elevated HbA1c level can be achieved through diet management; thus, the patients could be prevented from developing the diabetes complications. Awareness about diabetes complications and consequent improvement in dietary knowledge, attitude, and practices lead to better control of the disease. The stakeholders (health-care providers, health facilities, agencies involved in diabetes care, etc.) should encourage patients to understand the importance of diet which may help in disease management, appropriate self-care and better quality of life
Latent and Manifested flatness predictions in thin strip cold rolling using a general rolling FEM model
International audienceFlatness defects in thin strip cold rolling are a consequence of roll thermo-elastic deformation and the resulting heterogeneous strip plastic deformation. But in the case of on-line, manifested flatness defects, buckling reorganizes the stress field in the pre- and post-bite areas, which might impact strain and stress fields in the bite or at its ends. Such effects have always been neglected in the past. The purpose of the present paper is to present two coupled approaches to examine to what extent such potential in-bite / out-of-bite feedback determines the in-bite fields and the flatness of the strip. Using both methods and comparing with the standard case where buckling is not accounted for, it has been shown that (i) taking buckling into account results in completely different stress fields and fits correctly the measured on-line residual stresses under tension ("stress-meter rolls"); (ii) coupling buckling in the post-bite area and the rolling model, whatever the technique, changes little the in-bite fields; differences, if any, concentrate in the immediate vicinity of the bite exit; (iii) but in the case where manifested flatness defects occur, these tiny interactions (namely, through the exit velocity transverse profile) are essential for the precise description of the residual stresses and for accurate flatness prediction
- ā¦