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IRCCS - Istituto di Ricerche Farmacologiche “Mario Negri”
Transitional Flow in Patient-Specific Arteriovenous Fistulae for Hemodialysis
Bogdan Ene-Iordache, IRCCS - Istituto di Ricerche Farmacologiche “Mario Negri”
Andrea Remuzzi, IRCCS - Istituto di Ricerche Farmacologiche “Mario Negri”, Italy
Arteriovenous fistula (AVF) is the vascular access of choice for hemodialysis patients. The AVFs have high failure rates, primarily due to development of neointimal hyperplasia (NH) in the juxta-anastomotic vein (JAV). The aim of this study was to investigate the blood flow in patient-specific AVF, in order to characterize local wall shear stress (WSS) acting on the AVF walls.
We reconstructed the 3D model of AVF from contrast-free magnetic resonance images and then performed high-resolution CFD simulations, using a mesh of 1,278,000 cells. We also used patient-specific blood rheology and flow boundary conditions. We then characterized the flow field and categorized disturbed flow areas using established hemodynamic wall parameters.
We observed transitional laminar to turbulent flow developing in the JAV and damping towards the venous outflow. High-frequency fluctuations of velocity result in eddies that induce similar oscillations and rotations of the WSS vector. This condition may impair the physiological response of endothelial cells and trigger NH formation.
Fluid-structure interaction analysis of polymeric membrane
The focus of the study is to reproduce real stress and deformation fields into a polymeric membrane that works inside complex industrial filling valve. In the first part a CFD model has been developed in order to estimate loads distribution that acts over membrane during the closure procedure of valve its lf: strong and hard unsteady phenomena are generated during this phase (water hammer effect).
Following the first step, loads calculated from CFD analysis are directly shared and applied into structural solver. Structural FEM of membrane is created using real characterization data and loads from CFD: generated model allows to reproduce 1 way fluid structure interaction analysis. Finally, after identification of critical issues, an optimization of the geometry has been developed in order to reach desired performances.
Real neurons-nanoelectronics Architecture with Memristive Plasticity
Marco Fanciulli, Università Milano Bicocca, Italy
Giacomo Indiveri, INI Zurich, Switzerland
Christian Mayr, University of Dresden, Germany
Themis Prodromakis, University of Southampton, United Kingdom
Sabina Spiga, MDM-CNR, Italy
Grazia Tallarida, MDM-CNR, Italy
Ralf Zeitler, Venneos GmbH, Germany
Information processing in classical ‘von Neumann’ architectures is less efficient compared to biological counterparts when dealing with ill-posed problems and noisy data. The reason is that the biological brain is configured differently and the key is its evolving structure, where connectivity elements between individual neurons, the synapses, undergo ‘birth’ and ‘death’ as well as strengthening and weakening through a selection process, reconfiguring neuronal
connectivity in a self-organizing manner and allowing the networked population of neuronal processors to adapt motor and behavioural responses to the ever changing environment. Artificial neural networks in the form of software run on conventional ‘von Neumann’ computers appear incomparable to the biological systems in terms of speed, energy efficiency, adaptability and robustness. The challenge is to propose a ‘physical’ neural network where elements overcome this deficiency by merging data storage and processing into single electronic devices and by self-organizing and reconfiguring connectivity. Along this route, we report on a new biohybrid architecture of natural and artificial neurons. Communication between artificial and natural worlds is established through new nano- and microtransducers allowing direct electrical interfacing of a network of neurons in culture to an artificial CMOS-based counterpart. Furthermore, preliminary results show how adaptation properties of the artificial network can rely on
memristive nanoelectronic devices with synaptic-like plasticity. As such, the biohybrid system will provide new and unique adaptive, self-organizing and evolving properties deriving from the fusion of natural and artificial neuronal elements into a new plastic entity and will represent a fundamental step towards the development of novel
brain-inspired computing architectures as well as ‘intelligent’ autonomous systems and prostheses
The role of numerical simulation in product development: examples from bicycle industry
The use of numerical simulation is becoming increasingly important in the product development cycle. From early concept design, through detailed design, industrialization and production, every industrial phase can take benefit from CAE. Nevertheless there are some pitfalls to avoid and good practises to follow. Here some structural analysis examples are presented from the bike components industry.
Impact simulations on home appliances to optimize packaging protection: a case study
F. Lampitelli, Electrolux
Numerical simulations were used to investigate the impact behavior of complex products such as home appliances. LS-DYNA® is a powerful tool for performing repeated analysis of large assembled parts of the final product, including the packaging. The main goals of the project were to support designers in choosing the best configuration both in the oven structure and in the packaging shape. The studies were carried out to guarantee the integrity of the product from factory to customer and therefore to reduce customers service calls.
In particular, impact simulations on an oven and its packaging were performed using LS-DYNA®. The FE model reproduced the testing conditions defined by internal Electrolux regulations. Edge drop tests and inclined planes were studied and results used to improve overall performances.
The paper will present the current methodology developed to speed up the product development and to reduce the time to market (TTM). Experimental and numerical results will be compared.
Evaporation and Condensation Analysis through an Innovative Model in a Domestic Dish-Washer
Nasser Ghassembaglou, EnginSoft Turkey
Hasan Avşar, EnginSoft Turkey, Turkey
Uğur Kan, Arçelik/R&D/Ankara, Turkey
Levent Kavurmacıoğlu, Istanbul Technical University, Turkey
In this study, evaporation and condensation processes have been analyzed and investigated in a domestic dish-washer through different CFD methods. At first the dish-washer contains 4 liters of 58oC water which will be heated to 65oC by an 1800 Watt/m2 heat-flux source at the bottom-center of water volume.
The heating surface has an area of 0.03 m2 and automatically shuts down when the water reaches to 65oC. The analyze goes through natural cooling process for about 15 minutes to see the condensation procedure in different sections of dish washer. The whole volume of dish-washer, including felts, inner and outer cabinets have been considered in these analyses which have been run for both cases either with dishes or without dishes conditions. There are two holes with the names of water pocket and condensation shells at the left and right sides of inner cabinet which lets the water vapor to reach outside of it. Condensation occurs on different surfaces of dish-washer such as outer cabinet, inner cabinet, dishes, etc. which has been taken into account in all analyses. Also there is a very narrow gap at the front of dish-washer with a width of 0.002 m to allow the condensed or evaporated water to leak out of dish-washer. Finally, the amount of liquid and vapor which infiltrates out of dish-washer has been calculated and considered as a parameter showing the design success. 256 cores of a High Performance Computing (HPC) cluster have been used in the sake of calculation for 2 months. The results were written and post-processed as videos and images of evaporation and condensation processes for either with dish or without dish analyses which are presented in this research study.