Livres sur le sujet « Deformation assessment »

This article discusses the importance of assessing and estimating the risk of earthquakes. It begins with an overview of earthquake prediction and relevant terms, namely: earthquake hazard, maximum credible earthquake magnitude, exposure time, earthquake risk, and return time. It then considers data sources for estimating seismic hazard, including catalogs of historic earthquakes, measurements of crustal deformation, and world population data. It also examines ways of estimating seismic risk, such as the use of probabilistic estimates, deterministic estimates, and the concepts of characteristic earthquake, seismic gap, and maximum rupture length. A loss scenario for a possible future earthquake is presented, and the notion of imminent seismic risk is explained. Finally, the chapter addresses errors in seismic risk estimates and how to reduce seismic risk, ethical and moral aspects of seismic risk assessment, and the outlook concerning seismic risk assessment.

This article discusses the importance of assessing and estimating the risk of earthquakes. It begins with an overview of earthquake prediction and relevant terms, namely: earthquake hazard, maximum credible earthquake magnitude, exposure time, earthquake risk, and return time. It then considers data sources for estimating seismic hazard, including catalogs of historic earthquakes, measurements of crustal deformation, and world population data. It also examines ways of estimating seismic risk, such as the use of probabilistic estimates, deterministic estimates, and the concepts of characteristic earthquake, seismic gap, and maximum rupture length. A loss scenario for a possible future earthquake is presented, and the notion of imminent seismic risk is explained. Finally, the chapter addresses errors in seismic risk estimates and how to reduce seismic risk, ethical and moral aspects of seismic risk assessment, and the outlook concerning seismic risk assessment.

The left atrium (LA) plays an important role in cardiovascular performance, not only as a mechanical contributor, elastic reservoir, and a primer for left ventricular filling, but also as a participant in the regulation of intravascular volume through the production of atrial natriuretic peptide.Although LA diameter in the parasternal long-axis view has been routinely employed, LA volume is a more robust marker for predicting events than LA areas or diameters. The assessment of LA performance based on two-dimensional volumetrics, Doppler evaluation of mitral, pulmonary vein flow, and annular tissue Doppler, as well as deformation imaging techniques, may provide incremental information for prognostic purposes and for the evaluation of severity and duration of conditions associated with LA overload.The aims of this chapter are to explain the basics of LA function, and to describe the role of Doppler echocardiography techniques, and how to implement them, for the non-invasive evaluation of LA in clinical practice.

The complexity of left ventricular (LV) function(s) assessment in heart failure patients is related to the complexity of heart anatomy, but also to the complexity of electromechanical interaction, and to the load dependency of all the parameters that could be applied in clinical practice. Three perpendicular axes orienting the global geometry of the LV define the local cardiac coordinate system: radial, circumferential, and longitudinal. Speckle tracking is the technique of choice for quantifying myocardial deformation (regional and global). Longitudinal LV deformation, which is predominantly governed by the subendocardial region, is the most vulnerable component of LV mechanics and therefore most sensitive to the presence of myocardial disease.

Modern echocardiographic systems allow the quantitative and qualitative assessment of regional myocardial function by measuring velocity, motion, deformation, and other parameters of myocardial function.Both colour Doppler (CD) and spectral Doppler modes provide one-dimensional estimates of velocity. From CD data only, further parameters can be derived. Tracking techniques have recently been introduced which provide all parameters two-dimensionally, but at the cost of lower temporal resolution.Several clinical applications have been proposed, including regional and global systolic function assessment, evaluation of diastolic cardiac properties, and assessment of ventricular dyssynchrony.This chapter provides an introduction to the method of Doppler- and tracking-based function assessment and provides a basis for understanding its different clinical applications.

Assessing the right ventricle by any imaging modality is a challenge because of the thin wall and crescent shape that wraps around the left ventricle. Structured echocardiographic examination using two-dimensional imaging provides a detailed regional and global qualitative assessment for routine evaluation. Quantitation is possible using one or more methods including tricuspid annulus plane systolic excursion, fractional area change, and myocardial performance index but speckle tracking deformation imaging and three-dimensional echocardiography are emerging as more robust quantitative methods. Right ventricular pressures should also be estimated routinely as long as a clear tricuspid regurgitant jet is identified.

Echocardiographic techniques have revolutionized the practice of congenital cardiology over the last three decades. Due to its non-invasive nature and high temporal resolution, echocardiography enables cardiac structures to be imaged as early as the 14th gestational week and it remains the superior diagnostic modality in small children. While transoesophageal (TOE) two-dimensional echocardiography has become an integral part of almost all cardiac interventions, real-time three-dimensional TOE used in older children and adults may help surgeons to understand dynamic spatial relationships of intracardiac structures, enabling them to achieve the best result of an operation. Post bypass, two- and three-dimensional TOE studies significantly reduce the number of reoperations, unnecessary bypass procedures, and general anaesthetics. A developing technique known as tissue deformation imaging enables the assessment of global and regional myocardial systolic and diastolic function even in small hearts. Although mainly used for research, in some specific situations these techniques may modify further diagnostic management, optimize medication, or even change clinical management. Despite its known limitations, echocardiography remains a routine imaging modality for all patients with congenital heart disease, being a definitive imaging modality prior to intervention for many children and screening imaging for older children and adults with congenital heart disease.

Echocardiography is a key diagnostic method in the management of patients with cardiomyopathies.The main echocardiographic findings of hypertrophic cardiomyopathy are asymmetric hypertrophy of the septum, increased echogenicity of the myocardium, systolic anterior motion, turbulent left ventricular (LV) outflow tract blood flow, intracavitary gradient of dynamic nature, mid-systolic closure of the aortic valve and mitral regurgitation. The degree of hypertrophy and the magnitude of the obstruction have prognostic meaning. Echocardiography plays a fundamental role not only in diagnostic process, but also in management of patients, prognostic stratification, and evaluation of therapeutic intervention effects.In idiopathic dilated cardiomyopathy, echocardiography reveals dilation and impaired contraction of the LV or both ventricles. The biplane Simpson’s method incorporates much of the shape of the LV in calculation of volume; currently, three-dimensional echocardiography accurately evaluates LV volumes. Deformation parameters might be used for detection of early ventricular involvement. Stress echocardiography using dobutamine or dipyridamole may contribute to risk stratification, evaluating contractile reserve and left anterior descending flow reserve. LV dyssynchrony assessment is challenging and in patients with biventricular pacing already applied, optimization of atrio-interventricular delays should be done. Specific characteristics of right ventricular dysplasia and isolated LV non-compaction can be recognized, resulting in an increasing frequency of their prevalence. Rare forms of cardiomyopathy related with neuromuscular disorders can be studied at an earlier stage of ventricular involvement.Restrictive and infiltrative cardiomyopathies are characterized by an increase in ventricular stiffness with ensuing diastolic dysfunction and heart failure. A variety of entities may produce this pathological disturbance with amyloidosis being the most prevalent. Storage diseases (Fabry, Gaucher, Hurler) are currently treatable and early detection of ventricular involvement is of paramount importance for successful treatment. Traditional differentiation between constrictive pericarditis (surgically manageable) and the rare cases of restrictive cardiomyopathy should be properly performed.

The aim of the paper was to determine the influence of root systems of chosen tree species found in the Polish Flysch Carpathians on the increase of soil shear strength (root cohesion) in terms of slope stability. The paper's goal was achieved through comprehensive tests on root systems of eight relatively common in the Polish Flysch Carpathians tree species. The tests that were carried out included field work, laboratory work and analytical calculations. As part of the field work, the root area ratio (A IA) of the roots was determined using the method of profiling the walls of the trench at a distance of about 1.0 m from the tree trunk. The width of the. trenches was about 1.0 m, and their depth depended on the ground conditions and ranged from 0.6 to 1.0 m below the ground level. After preparing the walls of the trench, the profile was divided into vertical layers with a height of 0.1 m, within which root diameters were measured. Roots with diameters from 1 to 10 mm were taken into consideration in root area ratio calculations in accordance with the generally accepted methodology for this type of tests. These measurements were made in Biegnik (silver fir), Ropica Polska (silver birch, black locust) and Szymbark (silver birch, European beech, European hornbeam, silver fir, sycamore maple, Scots pine, European spruce) located near Gorlice (The Low Beskids) in areas with unplanned forest management. In case of each tested tree species the samples of roots were taken, transported to the laboratory and then saturated with water for at least one day. Before testing the samples were obtained from the water and stretched in a. tensile testing machine in order to determine their tensile strength and flexibility. In general, over 2200 root samples were tested. The results of tests on root area ratio of root systems and their tensile strength were used to determine the value of increase in shear strength of the soils, called root cohesion. To this purpose a classic Wu-Waldron calculation model was used as well as two types of bundle models, the so called static model (Fiber Bundle Model — FIRM, FBM2, FBM3) and the deformation model (Root Bundle Model— RBM1, RBM2, mRBM1) that differ in terms of the assumptions concerning the way the tensile force is distributed to the roots as well as the range of parameters taken into account during calculations. The stability analysis of 8 landslides in forest areas of Cicikowicleie and Wignickie Foothills was a form of verification of relevance of the obtained calculation results. The results of tests on root area ratio in the profile showed that, as expected, the number of roots in the soil profile and their ApIA values are very variable. It was shown that the values of the root area ratio of the tested tree species with a diameter 1-10 ram are a maximum of 0.8% close to the surface of the ground and they decrease along with the depth reaching the values at least one order of magnitude lower than close to the surface at the depth 0.5-1.0 m below the ground level. Average values of the root area ratio within the soil profile were from 0.05 to 0.13% adequately for Scots pine and European beech. The measured values of the root area ratio are relatively low in relation to the values of this parameter given in literature, which is probably connected with great cohesiveness of the soils and the fact that there were a lot of rock fragments in the soil, where the tests were carried out. Calculation results of the Gale-Grigal function indicate that a distribution of roots in the soil profile is similar for the tested species, apart from the silver fir from Bie§nik and European hornbeam. Considering the number of roots, their distribution in the soil profile and the root area ratio it appears that — considering slope stability — the root systems of European beech and black locust are the most optimal, which coincides with tests results given in literature. The results of tensile strength tests showed that the roots of the tested tree species have different tensile strength. The roots of European beech and European hornbeam had high tensile strength, whereas the roots of conifers and silver birch in deciduous trees — low. The analysis of test results also showed that the roots of the studied tree species are characterized by high variability of mechanical properties. The values Of shear strength increase are mainly related to the number and size (diameter) of the roots in the soil profile as well as their tensile strength and pullout resistance, although they can also result from the used calculation method (calculation model). The tests showed that the distribution of roots in the soil and their tensile strength are characterized by large variability, which allows the conclusion that using typical geotechnical calculations, which take into consideration the role of root systems is exposed to a high risk of overestimating their influence on the soil reinforcement. hence, while determining or assuming the increase in shear strength of soil reinforced with roots (root cohesion) for design calculations, a conservative (careful) approach that includes the most unfavourable values of this parameter should be used. Tests showed that the values of shear strength increase of the soil reinforced with roots calculated using Wu-Waldron model in extreme cases are three times higher than the values calculated using bundle models. In general, the most conservative calculation results of the shear strength increase were obtained using deformation bundle models: RBM2 (RBMw) or mRBM1. RBM2 model considers the variability of strength characteristics of soils described by Weibull survival function and in most cases gives the lowest values of the shear strength increase, which usually constitute 50% of the values of shear strength increase determined using classic Wu-Waldron model. Whereas the second model (mRBM1.) considers averaged values of roots strength parameters as well as the possibility that two main mechanism of destruction of a root bundle - rupture and pulling out - can occur at the same. time. The values of shear strength increase calculated using this model were the lowest in case of beech and hornbeam roots, which had high tensile strength. It indicates that in the surface part of the profile (down to 0.2 m below the ground level), primarily in case of deciduous trees, the main mechanism of failure of the root bundle will be pulling out. However, this model requires the knowledge of a much greater number of geometrical parameters of roots and geotechnical parameters of soil, and additionally it is very sensitive to input data. Therefore, it seems practical to use the RBM2 model to assess the influence of roots on the soil shear strength increase, and in order to obtain safe results of calculations in the surface part of the profile, the Weibull shape coefficient equal to 1.0 can be assumed. On the other hand, the Wu-Waldron model can be used for the initial assessment of the shear strength increase of soil reinforced with roots in the situation, where the deformation properties of the root system and its interaction with the soil are not considered, although the values of the shear strength increase calculated using this model should be corrected and reduced by half. Test results indicate that in terms of slope stability the root systems of beech and hornbeam have the most favourable properties - their maximum effect of soil reinforcement in the profile to the depth of 0.5 m does not usually exceed 30 kPa, and to the depth of 1 m - 20 kPa. The root systems of conifers have the least impact on the slope reinforcement, usually increasing the soil shear strength by less than 5 kPa. These values coincide to a large extent with the range of shear strength increase obtained from the direct shear test as well as results of stability analysis given in literature and carried out as part of this work. The analysis of the literature indicates that the methods of measuring tree's root systems as well as their interpretation are very different, which often limits the possibilities of comparing test results. This indicates the need to systematize this type of tests and for this purpose a root distribution model (RDM) can be used, which can be integrated with any deformation bundle model (RBM). A combination of these two calculation models allows the range of soil reinforcement around trees to be determined and this information might be used in practice, while planning bioengineering procedures in areas exposed to surface mass movements. The functionality of this solution can be increased by considering the dynamics of plant develop¬ment in the calculations. This, however, requires conducting this type of research in order to obtain more data.

[Abstract] The 6th International Workshop on Rock Physics (6IWRP) was held A Coruña, Spain, between 13th and 17th of June, 2022. This meeting follows the track of the five successful encounters held in Golden (USA, 2011), Southampton (UK, 2013), Perth (Australia, 2015), Trondheim (Norway, 2017) and Hong Kong (China, 2019). The aim of the workshop was to bring together experiences allowing to illustrate, discuss and exchange recent advances in the wide realm of rock physics, including theoretical developments, in situ and laboratory scale experiments as well as digital analysis. While rock physics is at the core of the oil & gas industry applications, it is also essential to enable the energy transition challenge (e.g. CO2 and H2 storage, geothermal), ensure a safe and adequate use of natural resources and develop efficient waste management strategies. The topics of 6IWRP covered a broad spectrum of rock physics-related research activities, including: • Experimental rock physics. New techniques, approaches and applications; Characterization of the static and dynamic properties of rocks and fluids; Multiphysics measurements (NMR, electrical resistivity…); Deep/crustal scale rock physics. • Modelling and multiscale applications: from the lab to the field. Numerical analysis and model development; Data science applications; Upscaling; Microseismicity and earthquakes; Subsurface stresses and tectonic deformations. • Coupled phenomena and rock properties: exploring interactions. Anisotropy; Flow and fractures; Temperature effects; Rock-fluid interaction; Fluid and pressure effects on geophysical signatures. • The energy transition challenge. Applications to energy storage (hydrogen storage in porous media), geothermal resources, energy production (gas hydrates), geological utilization and storage of CO2, nuclear waste disposal. • Rock physics templates: advances and applications. Quantitative assessment; Applications to reser voir characterization (role of seismic wave anisotropy and fracture networks). • Advanced rock physics tools. Machine learning; application of imaging (X-ray CT, X-ray μCT, FIB-SEM…) to obtain rock proper ties. This book compiles more than 50 abstracts, summarizing the works presented in the 6IWRP by rock physicists from all over the world, belonging to both academia and industry. This book means an updated overview of the rock physics research worldwide.