Multiscale Biomechanics and Tribology of Inorganic and Organic Systems

This open access book gathers authoritative contributions concerning multiscale problems in biomechanics, geomechanics, materials science and tribology. It is written in memory of Sergey Grigorievich Psakhie to feature various aspects of his multifaceted research interests, ranging from theoretical physics, computer modeling of materials and material characterization at the atomic scale, to applications in space industry, medicine and geotectonics, and including organizational, psychological and philosophical aspects of scientific research and teaching as well. This book covers new advances relating to orthopedic implants, concerning the physiological, tribological and materials aspects of their behavior; medical and geological applications of permeable fluid-saturated materials; earthquake dynamics together with aspects relating to their managed and gentle release; lubrication, wear and material transfer in natural and artificial joints; material research in manufacturing processes; hard-soft matter interaction, including adhesive and capillary effects; using nanostructures for influencing living cells and for cancer treatment; manufacturing of surfaces with desired properties; self-organization of hierarchical structures during plastic deformation and thermal treatment; mechanics of composites and coatings; and many more. Covering established knowledge as well as new models and methods, this book provides readers with a comprehensive overview of the field, yet also with extensive details on each single topic

A constraint-based methodology for product design with virtual reality

This paper presents a constraint-based methodology for product design with advanced virtual reality technologies. A hierarchically structured and constraint-based data model is developed to support product design from features to parts and further to assemblies in a VR environment. Product design in the VR environment is performed in an intuitive manner through precise constraint-based manipulations. Constraint-based manipulations are accompanied with automatic constraint recognition and precise constraint satisfaction to establish constraints between objects, and are further realized by allowable motions for precise 3D interactions in the VR environment. The allowable motions are represented as a mathematical matrix and derived from constraints between objects by constraint solving. A procedure-based degrees-of-freedom combination approach is presented for 3D constraint solving. A rule-based constraint recognition engine is developed for both constraint-based manipulations and implicitly incorporating constraints into the VR environment. An intuitive method is presented for recognizing pairs of mating features between assembly components. Examples are presented to demonstrate the efficacy of the proposed methodology

Nanofluid Flow in Porous Media

Studies of fluid flow and heat transfer in a porous medium have been the subject of continuous interest for the past several decades because of the wide range of applications, such as geothermal systems, drying technologies, production of thermal isolators, control of pollutant spread in groundwater, insulation of buildings, solar power collectors, design of nuclear reactors, and compact heat exchangers, etc. There are several models for simulating porous media such as the Darcy model, Non-Darcy model, and non-equilibrium model. In porous media applications, such as the environmental impact of buried nuclear heat-generating waste, chemical reactors, thermal energy transport/storage systems, the cooling of electronic devices, etc., a temperature discrepancy between the solid matrix and the saturating fluid has been observed and recognized

Multiscale biomechanics and tribology of inorganic and organic systems : In memory of Professor Sergey Psakhie

This open access book gathers authoritative contributions concerning multiscale problems in biomechanics, geomechanics, materials science and tribology. It is written in memory of Sergey Grigorievich Psakhie to feature various aspects of his multifaceted research interests, ranging from theoretical physics, computer modeling of materials and material characterization at the atomic scale, to applications in space industry, medicine and geotectonics, and including organizational, psychological and philosophical aspects of scientific research and teaching as well. This book covers new advances relating to orthopedic implants, concerning the physiological, tribological and materials aspects of their behavior; medical and geological applications of permeable fluid-saturated materials; earthquake dynamics together with aspects relating to their managed and gentle release; lubrication, wear and material transfer in natural and artificial joints; material research in manufacturing processes; hard-soft matter interaction, including adhesive and capillary effects; using nanostructures for influencing living cells and for cancer treatment; manufacturing of surfaces with desired properties; self-organization of hierarchical structures during plastic deformation and thermal treatment; mechanics of composites and coatings; and many more. Covering established knowledge as well as new models and methods, this book provides readers with a comprehensive overview of the field, yet also with extensive details on each single topic.TU Berlin, Open-Access-Mittel – 202

Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018

The First Conference on materials science and engineering, including physics, physical chemistry, condensed matter chemistry, and technology in general, was held in September 1995, in Herceg Novi. An initiative to establish Yugoslav Materials Research Society was born at the conference and, similar to other MR societies in the world, the programme was made and objectives determined. The Yugoslav Materials Research Society (Yu-MRS), a nongovernment and non-profit scientific association, was founded in 1997 to promote multidisciplinary goal-oriented research in materials science and engineering. The main task and objective of the Society has been to encourage creativity in materials research and engineering to reach a harmonic coordination between achievements in this field in our country and analogous activities in the world with an aim to include our country into global international projects. Until 2003, Conferences were held every second year and then they grew into Annual Conferences that were traditionally held in Herceg Novi in September of every year. In 2007 Yu-MRS formed two new MRS: MRS-Serbia (official successor of Yu-MRS) and MRS-Montenegro (in founding). In 2008, MRS – Serbia became a member of FEMS (Federation of European Materials Societies)

The use of the lattice Boltzmann method in thrombosis modelling.

The effects of thrombosis greatly contribute to the incidence of mortality in the Western World. Understanding thrombosis is therefore crucial in providing the correct treatment for the underlying pathologies. Numerical methods have previously been used to investigate various factors associated with thrombosis, usually starting from solutions of the Navier-Stokes equations. This thesis presents the development and implementation of models of thrombosis using the lattice Boltzmann method, which is a relatively new technique for simulating fluid dynamics. The advantages and disadvantages of this methodology are critically reviewed and two major pathologies, atherosclerosis and deep vein thrombosis have been chosen to demonstrate principles of the application. The first part of the work concentrates on the simulation of flow and clotting in idealised stenotic occlusions representative of the geometry and flow conditions in a diseased human femoral artery. Simulations of unsteady flow are reported and comparisons are made to previous flow visualisation studies. Stability issues regarding the diffusion algorithm are investigated in detail. In the first instance, clotting is simulated with the use of an aging model with extensions including proximity and shear stress. Comparisons are made with experimental results obtained using milk as a blood analogue. )'he second part of the work focuses on increasing the complexity of the models to incorporate the representations of the actions and distribution of the platelets, proteins and enzymes involved in the coagulation cascade. The models are tested in 2D geometries to demonstrate their functionality. As an example of this work, a model of deep vein thrombosis was developed, based on a hypothesis supported by the clinical literature. The foundations laid in this project allow for future developments, which will incorporate further details of thrombotic processes, in the hope that a valuable predictor of thrombosis can be developed

Effect of Tissue Structure (and) Disease on Simulated Arrhythmias in the Human Heart

Ventricular Fibrillation (VF) is a severe cardiac arrhythmia. Early experiments provided evidence that the mechanism of VF is consistent with re-entry. In 3D the sources of re-entrant waves are lines of phase singularity called ‘filaments’. Filament interactions and filament numbers can be used to quantify the complexity of activation patterns in simulated VF. The aim of this thesis is to study the effect of tissue structure, shape, initial conditions, and region of scar on filament dynamics using computational modelling. Transmural heterogeneity in 3D slab tissue representing the ventricular wall did not show important difference in the number of filaments. Configuration of filaments were influenced by transmural heterogeneity. With transmural heterogeneity, clustering of filaments were observed near slow conducting border resulting in increase of filament life time. To study the effect on the shape of the tissue on filaments, filament dynamics in 3D slab tissue was compared with filament dynamics in an idealized human left ventricle (LV) with similar apex base dimension and wall thickness. The volume of idealized LV is about twice the volume of 3D slab. Results showed idealized LV had twice the number of filaments compared to slab geometry especially with steeper restitution dynamics. This thesis highlights non-linear behaviour of activation patterns during VF in 3D where small changes had a large influence on the number of filaments in both 3D slab and idealized LV especially with steeper restitution dynamics. Pre-existing scar tissue in VF patients can act as a source of anatomical re-entry and pin re-entrant filaments to the scar boundary. However, the interaction of scar with complex activation during VF is not well understood. This thesis investigated how simulated scars (circumferential, transmural and sub-endo transmural) with varying size and with either regular or with irregular scar boundary, influenced re-entrant filaments in simplified computational models of 3D slab and idealized LV. Circumferential scar did not show any influence on filament dynamics and clustering of filaments to scar boundary. Increased radius of transmural and sub-endocardial transmural scar had more clustering of filaments to the scar boundary especially with steeper restitution dynamics. Sub- endocardial transmural scar with increased radius had more clustering of filaments compared to transmural scar. Region of scar with irregular boundary had more clustering compared to scar with regular boundary. Generally transmural scar and sub-endocardial transmural scar with regular or irregular boundary did not increase the number of filaments much but increased the length and lifetime of filaments due to clustering of filaments to the scar boundary. Since filaments pin to the boundary of the scar region, it can be hard to remove them using defibrillation techniques. It might be necessary to measure the radius and the depth of pre-existing scar tissue accurately in VF patients, as the bigger scar is likely to have more complex activation in VF. In this way it might be easier to predict the strength of defibrillation to use, in order to stop VF