A review of nonlinear FFT-based computational homogenization methods

Since their inception, computational homogenization methods based on the fast Fourier transform (FFT) have grown in popularity, establishing themselves as a powerful tool applicable to complex, digitized microstructures. At the same time, the understanding of the underlying principles has grown, in terms of both discretization schemes and solution methods, leading to improvements of the original approach and extending the applications. This article provides a condensed overview of results scattered throughout the literature and guides the reader to the current state of the art in nonlinear computational homogenization methods using the fast Fourier transform

Efficient fast Fourier transform-based solvers for computing the thermomechanical behavior of applied materials

The mechanical behavior of many applied materials arises from their microstructure. Thus, to aid the design, development and industrialization of new materials, robust computational homogenization methods are indispensable. The present thesis is devoted to investigating and developing FFT-based micromechanics solvers for efficiently computing the (thermo)mechanical response of nonlinear composite materials with complex microstructures

Efficient fast Fourier transform-based solvers for computing the thermomechanical behavior of applied materials

The mechanical behavior of many applied materials arises from their microstructure. Thus, to aid the design, development and industrialization of new materials, robust computational homogenization methods are indispensable. The present thesis is devoted to investigating and developing FFT-based micromechanics solvers for efficiently computing the (thermo)mechanical response of nonlinear composite materials with complex microstructures

Computational Models of Dopamine Diffusion and Receptor Binding in the Striatum

The neuromodulator dopamine (DA) has complex effects on the activity of striatal neurons by changing their excitability and strength of synaptic inputs in the context of motor control, action-selection, reinforcement learning, and addiction. DA is volume transmitted, it leaves the synaptic cleft and diffuses through the extracellular space in the striatum. The spatial and temporal distribution of DA created by this diffusion have not been extensively studied yet. In this thesis a computational model based on diffusion in a porous medium was developed to study the spatiotemporal distribution of DA in the striatum. During the development of the model a second interesting problem was identified: DA receptors have slow kinetics. Due to these slow kinetics the DA receptors do not directly follow the DA concentration, but can integrate over longer timespans. Taking into account realistic kinetics it is shown that the different DA receptors do not have markedly different responses to different timescales of DA signals. The full model incorporates inhomogenous DA uptake, DA axonal tree morphologies, detailed receptor kinetics and spike trains based on rat cell recording. The thesis shows that spatiotemporal DA maps of a healthy striatum are highly variable in space and time but the death of dopaminergic axons, as seen in Parkinsons Disease, reduces the variability of the DA maps and makes them more homogenous. Furthermore, the DA receptor maps are shown to be correlated to anatomical features, synaptic positions and locations of reduced local DA uptake, and therefore have a component that is stable in time. The code of the full model has been made available at https://bitbucket.org/Narur/dope-amine/src/, so that others may also find out that dopamine is a dope amine

Aeronautical Engineering: A continuing bibliography with indexes

This bibliography lists 499 reports, articles and other documents introduced into the NASA scientific and technical information system in August 1985

Single particle, high temperature, gas-solid reactions in an electrodynamic balance

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1988.Includes bibliographical references.by David Robert Dudek.Sc.D

Basic Research Needs for Geosciences: Facilitating 21st Century Energy Systems

Executive Summary Serious challenges must be faced in this century as the world seeks to meet global energy needs and at the same time reduce emissions of greenhouse gases to the atmosphere. Even with a growing energy supply from alternative sources, fossil carbon resources will remain in heavy use and will generate large volumes of carbon dioxide (CO2). To reduce the atmospheric impact of this fossil energy use, it is necessary to capture and sequester a substantial fraction of the produced CO2. Subsurface geologic formations offer a potential location for long-term storage of the requisite large volumes of CO2. Nuclear energy resources could also reduce use of carbon-based fuels and CO2 generation, especially if nuclear energy capacity is greatly increased. Nuclear power generation results in spent nuclear fuel and other radioactive materials that also must be sequestered underground. Hence, regardless of technology choices, there will be major increases in the demand to store materials underground in large quantities, for long times, and with increasing efficiency and safety margins. Rock formations are composed of complex natural materials and were not designed by nature as storage vaults. If new energy technologies are to be developed in a timely fashion while ensuring public safety, fundamental improvements are needed in our understanding of how these rock formations will perform as storage systems. This report describes the scientific challenges associated with geologic sequestration of large volumes of carbon dioxide for hundreds of years, and also addresses the geoscientific aspects of safely storing nuclear waste materials for thousands to hundreds of thousands of years. The fundamental crosscutting challenge is to understand the properties and processes associated with complex and heterogeneous subsurface mineral assemblages comprising porous rock formations, and the equally complex fluids that may reside within and flow through those formations. The relevant physical and chemical interactions occur on spatial scales that range from those of atoms, molecules, and mineral surfaces, up to tens of kilometers, and time scales that range from picoseconds to millennia and longer. To predict with confidence the transport and fate of either CO2 or the various components of stored nuclear materials, we need to learn to better describe fundamental atomic, molecular, and biological processes, and to translate those microscale descriptions into macroscopic properties of materials and fluids. We also need fundamental advances in the ability to simulate multiscale systems as they are perturbed during sequestration activities and for very long times afterward, and to monitor those systems in real time with increasing spatial and temporal resolution. The ultimate objective is to predict accurately the performance of the subsurface fluid-rock storage systems, and to verify enough of the predicted performance with direct observations to build confidence that the systems will meet their design targets as well as environmental protection goals. The report summarizes the results and conclusions of a Workshop on Basic Research Needs for Geosciences held in February 2007. Five panels met, resulting in four Panel Reports, three Grand Challenges, six Priority Research Directions, and three Crosscutting Research Issues. The Grand Challenges differ from the Priority Research Directions in that the former describe broader, long-term objectives while the latter are more focused