1,721,364 research outputs found
The effects of hydroxyethyl starch solution in critically ill patients.
No full textPalumbo D, Servillo G, D'Amato L, Volpe ML, Capogrosso G, De Robertis E,
Piazza O, Tufano R.
The effects of hydroxyethyl starch solution in critically ill patients.
Minerva Anestesiol. 2006 Jul-Aug;72(7-8):655-6
Controversial issues in current definitions of mental health
No full textThe concept of mental health is still widely discussed among philosophers and scientists. The emphasis on positive emotions and functional aspects of the World Health Organization definition has sometimes been called into question. This paper will focus on recently proposed mental health definitions, and in particular on mental health normative criteria involved in each of them. The criteria are divided in two broad categories: biomedical and cultural criteria. Strengths and weaknesses of each definition are illustrated in order to highlight research needs likely to support further progress
Analisi termomeccanica di giunti in acciaio saldato Fe 360
No full textNonostante il gran numero di proposte nel campo della previsione a fatica dei giunti saldati, una teoria unificata e di validità globale, applicabile con facilità in qualsiasi condizione, ancora non esiste. Tuttavia, è frequente che i componenti da dimensionare differiscano per geometria e/o per tipo di carico dai particolari costruttivi considerati dalla normativa; in questo caso si ricorre usualmente a coefficienti di sicurezza parecchio cautelativi che portano a sottostimare l'effettiva durata a fatica del giunto e che determinano un notevole scostamento tra i risultati calcolati e quelli reali. La termografia ad infrarosso ha grandi potenzialità in questo campo, sia da un punto di vista di misura di sollecitazione, che da un punto di vista termomeccanico: permette infatti di condurre analisi di campo con una risoluzione spaziale sufficiente per cogliere la complessità dello stato tensionale ai piedi del cordone di saldatura e di seguire l'evoluzione temporale delle stesse evidenziando chiaramente anomalie che possano preludere a cedimenti strutturali. In questo articolo è presentato un nuovo metodo per la valutazione del limite di fatica dei materiali. Risultati interessanti derivano dall'analisi dell'evoluzione del segnale termoelastico di fase. Variazioni nel valore della fase indicano un comportamento non elastico e dissipazioni plastiche nel materiale.Despite the large number of proposals in the field of fatigue prediction of welded joints, a globally accepted and unified theory, which applies easily to any load condition, does not exist. Real life components, indeed, differ in geometry and/or type of load from the structural design for which they are regarded by Standards, so that a lot of precautionary safety factors are used that lead to an underestimation of the actual fatigue life of joints. Infrared thermography has a great potential in this field, both from structural and thermomechanical points of view. It enables a full field stress analysis with a sufficient spatial resolution so that the complexity of the stress state at the weld toe and its time evolution are taken into account, emphasizing anomalies that may predict structural failure. A new methods for evaluation fatigue limit damage is presented in this paper and in particular interesting results derived from analysis of the evolution of thermoelastic signal phase. Variations in the value of signal phase indicate a not elastic behaviour and plastic dissipation in the material
Characterisation of steel welded joints by infrared thermographic methods
No full textDespite the large number of proposals in the field of fatigue prediction of welded joints, there is no worldwide accepted and unified theory which can be easily applicable to any load condition. Real life components, in fact, differ in geometry and/or type of load from the structural design considered by the Standards, hence a lot of precautionary safety factors are used, leading to an underestimation of the actual fatigue life of joints. Infrared thermography has a great potential in this field. In fact, it enables a full-field stress analysis with an adequate spatial resolution so that the complexity of the stress state at the weld toe and its time evolution are taken into account, emphasising anomalies that may predict structural failure. This paper presents a new method for the evaluation of the fatigue limit, focusing on interesting results derived from the analysis of thermoelastic signal phase evolution. Variations in the value of signal phase indicate a non-elastic behaviour and plastic dissipation in the material
Thermoelastic stress analysis of titanium components and simultaneous assessment of residual stress
Full text linkThe thermoelastic effect describes a linear relationship between change in body temperature and state of stress in the presence of adiabatic conditions. This approach considers the material properties constant with temperature, which is not correct for all materials. Experimental results and a review of the theory, especially for the titanium and some alloys of aluminium, have shown that the thermoelastic signal is also dependent of mean stress of the material. The use of titanium in various fields of application makes interesting use of thermoelastic technique as full field stress analysis technique. However, it is necessary to make a correction of the measure in relation to the mean stress. The possibility to measure the mean stress allows also an evaluation of residual stresses on the surface of titanium components
Estimation of the dissipative heat sources related to the total energy input of a cfrp composite by using the second amplitude harmonic of the thermal signal
Full text linkTheories for predicting the fatigue behaviour of composite laminates often make strong assumptions on the damage mechanisms that strongly depend on the designed laminate lay-up. In this regard, several physical and empirical models were proposed in the literature that generally require experimental validations. The experimental techniques, such as thermography, also provide useful tools for monitoring the behaviour of the specific material so, that they can be used to support the study of the damage mechanisms of materials. In this research, the second amplitude harmonic of the thermal signal has been investigated and used to assess the relationship with the total energy input in order to estimate the fatigue strength of the material. A thermal index was assessed by monitoring the constant amplitude tests (S/N curve) that were performed on a quasi-isotropic carbon fibre reinforced polymer (CFRP) laminate obtained by the automated fibre placement process. The obtained results demonstrated the capability of the second amplitude harmonic of the thermal signal to describe and monitor the fatigue damage
New thermographic technique for assessment of residual stress in titanium components
No full textThe thermoelastic effect describes a linear relationship between change in body temperature and state of stress in the presence of
adiabatic conditions. This approach considers the material properties constant with temperature, which is not correct for all materials.
Experimental results and a review of the theory, especially for the titanium and some alloys of aluminium, have shown that the
thermoelastic signal is also dependent of mean stress of the material. The use of titanium in various fields of application makes
interesting use of thermoelastic technique as full field stress analysis technique. However, it is necessary to make a correction of the
measure in relation to the mean stress. The possibility to measure the mean stress allows also an evaluation of residual stresses on the
surface of titanium components
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Application of thermal methods for characterization of steel welded joints
No full textDespite the large number of proposals in the field of fatigue prediction of welded joints, a globally accepted and unified theory, which applies easily to any load condition, does not exist. Real life components, indeed, differ in geometry and/or type of load from the structural design for which they are regarded by Standards, so that a lot of precautionary safety factors are used that lead to an underestimation of the actual fatigue life of joints. Infrared thermography has a great potential in this field, both from structural and thermomechanical points of view. It enables a full field stress analysis with a sufficient spatial resolution so that the complexity of the stress state at the weld toe and its time evolution are taken into account, emphasizing anomalies that may predict structural failure. A new methods for evaluation fatigue limit damage is presented in this paper and in particular interesting results derived from analysis of the evolution of thermoelastic signal phase. Variations in the value of signal phase indicate a not elastic behaviour and plastic dissipation in the material
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