It is demonstrated that the method for locating a velocity profile origin, or plane of zero velocity, by fitting log profiles to streamwise velocity measurements is applicable to a larger range of roughness scales than previously expected. Five different sets of detailed, experimental velocity measurements were analyzed encompassing sediment-scale roughness elements, roughness caused by rigid vegetation, and large-scale roughness elements comprised of mobile bedforms. The method resulted in similar values of normalized zero-plane displacement for all roughness types considered. The ratios of zero-plane displacement, dh, to roughness height, ks, were 0.20 and 0.26 for the sediment- and vegetation-scale experiments, respectively. The results for the two experiments with bedform dominated roughness were 0.34 and 0.41. An estimate of dh/ks ranging from 0.2 to 0.4 is therefore recommended for a range of roughness types with the higher end of the range being more appropriate for the larger, bedform-scale roughness elements, and the lower end for the sediment-scale roughness elements. In addition, it is demonstrated that the location of the plane of zero velocity is temporally constant even when the bed height is not. The effects of roughness element packing density were also examined with the identification of a possible threshold at 4%, above which zero-plane displacement is independent of packing density. The findings can be applied to field velocity measurements under mobile bed conditions, facilitating the calculation of turbulence parameters such as shear velocity, by using point measurements and providing guidelines for the estimation of an appropriate value for zero-plane displacement. / Master of Science

Supersonic hot jet noise causes significant hearing impairment to the military workforce and results in substantial cost for medical care and treatment. Detailed insight into the turbulence structure of high-speed jets is central to understanding and controlling jet noise. For this purpose a new instrument based on the Doppler global velocimetry technique has been developed. This instrument is capable of measuring three-component velocity vectors over ex-tended periods of time at mean data-rates of 100 kHz. As a demonstration of the applicability of the time-resolved Doppler global velocimetry (TR-DGV) measurement technique, statistics of three-component velocity measurements, full Reynolds stress tensors and spectra along the stream-wise direction in a cold, supersonic jet at exit Mach number Mj = 1.4 (design Mach number Md = 1.65) are presented. In pursuance of extending the instrument to planar op- eration, a rapid response photomultiplier tube, 64-channel camera is developed. Integrating field programmable gate array-based data acquisition with two-stage amplifiers enables high-speed flow velocimetry at up to 10 MHz. Incor- porating this camera technology into the TR-DGV instrument, an investigation of the perfectly expanded supersonic jet at two total temperature ratios (TTR = 1.6 and TTR = 2.0) was conducted. Fourth-order correlations which have direct impact on the intensity of the acoustic far-field noise as well as convective velocities on the lip line at several stream-wise locations were obtained. Comprehensive maps of the convective velocity and the acoustic Mach number were determined. The spatial and frequency scaling of the eddy convective velocities within the developing shear layer were also investigated. It was found that differences in the radial diffusion of the mean velocity field and the integral eddy convective velocity creates regions of locally high convective Mach numbers after the potential core. This, according to acoustic analogies, leads to high noise radiation efficiency. The spectral scaling of the eddy convec- tive velocity indicates intermittent presence of large-scale turbulence structures, which, coupled with the emergence of Mach wave radiation, may be one of the main driving factors of noise emission observed in heated supersonic jets. / Ph. D.

My thesis is a human intervention into the tranquil and natural environment of Pandapas Pond and the Jefferson National Forest. Although the form of the intervention embraces the landscape and natural land formations, its purpose is to take the visitor along a path that translates the experience from one of participation to that of observation of the parkâ s surroundings. This is both an investigation of an architectural integration with the site and a partial separation of the inhabiter from his/her natural surroundings. / Master of Architecture

This thesis is an attempt to explore post industrial society and how modern industry can become part of the urban experience. Through the design of a nanotechnology research laboratory, I was able to discover a connection between modern architecture and nanotechnology which revolved around the topics of scale, layering and revealing. / Master of Architecture

The principle notion of this thesis has been to propel ideas derived through architecture, experience, intuition, and program in order to transform idea into form. The attempts to understand gallery as a place where people can show their work for a short amount of time, allowing for a continual engagement between works and viewers. / Master of Architecture

The articulation of frame and skin forms the space concertedly. The project, stemming from this assertion, searches, explores and articulates the intricate relationship between structure, skin and space as prominent elements of architecture. / Master of Architecture

what is architecture? what defines space? how do you define separation and integration of spaces? what is the relationship of human scale to space elements? how can architecture be studied? Architecture is an combination of science and art to make spaces for human needs and activities. What can an architect do to make a project, a building, not only serve its purpose but to go beyond that? A space supports human desire and imagination. Architecture provides the means and methods to make the spaces. The elements of the structure, column, wall, beam, and floor, play a very important role in defining and/or dividing a space. A room can be defined by four walls, columns or even beams. The material of the floor also outlines space. Walls, a series of columns, or ceiling beams can define an edge or enclose space and differentiate its meaning and function. The understanding of these elements and their relationship with each other and with people is the purpose of this study. In an urban situation often there is a need to design buildings with spaces for multiple activities. Separation of spaces and functions, as well as integration of different parts, is vital in such a design. Columns and walls enclose the space and characterize privacy. Their material and its characteristics make the edges of space opaque, transparent or semitransparent. The dimensions of columns and beams show the scale of the space, constraining the relationship of the people to the structural elements. / Master of Architecture

Recent developments in functional magnetic resonance imaging (fMRI) methods at high magnetic field strengths (≥7 T) promise the non-invasive indirect measurement of neural activation at the spatial scale of cortical columns and layers. However, the achievable spatial specificity of fMRI, which is ultimately limited by the spatio-temporal properties of the hemodynamic response, is still waiting to be fully characterized. To examine the spatial specificity of the blood oxygenation level dependent (BOLD) contrast exploited by fMRI, the spatial point spread function (PSF) of the gradient echo (GE) and the spin echo (SE) BOLD signal tangential to the cortical surface was determined at different cortical depths. Both GE- and SE-BOLD showed a loss in spatial specificity toward the pial surface, demonstrating the impact of unspecific macrovascular contributions to both contrasts and only a minor advantage of the SE-BOLD signal for high-resolution fMRI applications. However, unidirectional draining of deoxygenated blood mainly limits spatial specificity in the radial direction. To examine the discriminability of laminar information, ocular dominance columns (ODCs) in the primary visual cortex (V1) were mapped using fMRI sensitive to either the BOLD contrast or cerebral blood volume (CBV) changes, and the stimulated eye was decoded using a machine learning classifier at different cortical depths. Only CBV-fMRI showed increased prediction accuracies at the cortical depth that matched neurophysiological expectations, showing its improved spatial specificity and potential for layer-specific fMRI in humans. Furthermore, the thin-thick-pale stripe pattern in the secondary visual cortex (V2) was targeted, exploiting the sensitivity to color and binocular disparity of thin and thick stripes, respectively. The structure-function relationship of the stripe architecture to cortical myelin was studied, which so far has shown inconsistent findings in multiple histological experiments. High-resolution quantitative MRI (qMRI) parameter maps of the longitudinal relaxation rate (R1) were used as a proxy for cortical myelin content. The comparison of fMRI and qMRI maps showed that both thin and thick stripes have lower R1 than surrounding cortical tissue, pointing toward higher myelin content of pale stripes. While macrovascular contributions in fMRI must be considered cautiously, the thesis demonstrates the capabilities to study structure-function relationships and retrieval of laminar information at the spatial scale of cortical columns with high-resolution fMRI at 7 T.:List of figures List of tables List of acronyms 1 Introduction 1.1 Imaging the human brain 1.2 The visual cortex 1.3 Vascular supply of the cerebral cortex 1.4 Thesis outline 2 Background 2.1 Nuclear magnetic resonance 2.1.1 Nuclear magnetic moment 2.1.2 Zeeman effect 2.1.3 Bulk magnetization 2.1.4 Excitation 2.1.5 Relaxation 2.1.6 Refocusing 2.1.7 Detection 2.2 Magnetic resonance imaging 2.2.1 Gradients 2.2.2 Spatial encoding 2.2.3 Echo-planar imaging 2.3 Functional magnetic resonance imaging 2.3.1 Blood 2.3.2 Hemodynamic response 2.3.3 BOLD-fMRI 2.3.4 CBV-fMRI 2.4 Spatial specificity 2.4.1 Point spread function 2.4.2 Imaging PSF 2.4.3 Physiological PSF 3 Cortical depth-dependent spatial specificity of GE- and SE-BOLD 3.1 Introduction 3.2 Theory 3.3 Materials and methods 3.3.1 Participants 3.3.2 General procedure 3.3.3 Visual stimulation 3.3.4 Imaging 3.3.5 Data preprocessing 3.3.6 MTF model fitting using MCMC 3.4 Results 3.4.1 GE- and SE-BOLD maps 3.4.2 Percent signal changes across cortical depth 3.4.3 Cortical distances along iso-eccentricity lines 3.4.4 MCMC diagnostics 3.4.5 Estimated MTF parameters 3.4.6 MTF within veins 3.5 Discussion 4 Laminar profile of human ocular dominance columns 4.1 Introduction 4.2 Materials and methods 4.2.1 Participants 4.2.2 General procedure 4.2.3 Visual stimulation 4.2.4 Imaging 4.2.5 Data preprocessing 4.2.6 Pattern classification 4.3 Results 4.3.1 Topography of ocular dominance columns 4.3.2 Reproducibility of ocular dominance maps 4.3.3 Univariate contrasts across cortical depth 4.3.4 Decoding accuracies across cortical depth 4.4 Discussion 5 Cortical myelination of the secondary visual cortex (V2) 5.1 Introduction 5.2 Materials and methods 5.2.1 Participants 5.2.2 General procedure 5.2.3 Visual stimulation 5.2.4 Imaging 5.2.5 Data analysis 5.3 Results 5.3.1 Functional mapping of color-selective and disparity-selective stripes 5.3.2 Consistent qMRI maps across cortical regions and cortical depth 5.3.3 Higher myelination of pale stripes 5.4 Discussion 6 General discussion A Gradient-based boundary registration B Construction of anaglyph spectacles C Supplementary data for chapter 3 D Supplementary data for chapter 4 E Supplementary data for chapter 5 F Analysis of registration accuracy Acknowledgements Bibliography Curriculum vitae Declaration of authorship

No / Representations for the stress fields created around an infinite row of collinear, antiplane shear cracks moving within one-dimensional hexagonal quasicrystals, and the resulting stress intensity factors and the J-integral, are determined in closed-form and discussed, using an extended method of dislocation layers. The solutions for a finite quasicrystalline plate containing a single moving crack and a plate with a moving edge crack are also provided by this analysis. (C) 2014 Elsevier Ltd. All rights reserved.

In-situ geotechnical testing of surficial sediment layers in areas of active sediment dynamics can provide essential information about physical and geotechnical variations of sediment properties with regards to active sediment remobilization processes. For example, portable free fall penetrometers (PFFPs) can assist with the detection of mobile sediment layers. They are easy to deploy, and can provide a large spatial coverage in a time- and cost-effective manner. However, they often struggle to provide more detailed information about the properties of mobile sediment layers due to a lack of calibration and validation in existing data sets. Currently, existing sediment samplers often disturb, or ignore the uppermost sediment layers. Simultaneous sediment sampling and geotechnical profiling is needed to fill this gap, and to drive data interpretation forward. A field investigation of surficial sediments was conducted in the wetland waterways of coastal Louisiana in 2014. In-situ tests were conducted using PFFP, and disturbed sediment samples were collected in selected locations. The results allowed us to map changes in sediment strength and stratification, and correlate the geotechnical results to local site characteristics. However, the need for high quality sediment samples for calibration and validation was emphasized by the results. Three different sediment sampler add-on units targeting mobile layers were designed and manufactured based on lessons-learned from the literature. The designs were tested in the laboratory and in the field (Yakutat, Alaska and York River, Virginia) in 2017. The samples were analyzed to understand the influence of different sampler characteristics on collected sample quality, and, to define mobile layer sampler characteristics that enable simultaneous geotechnical testing and the collection of high quality samples. Following field survey campaigns in the York River, Virginia in 2016 allowed to assess surficial sediment layer characteristics and behavior based on a coupled analysis of geotechnical data from in-situ PFFP tests and the sedimentological data collected using box cores and the novel sediment sampler. In summary, novel strategies and instrumentation to carry out simultaneous sediment sampling and geotechnical profiling of seabed surface layers were tested, and new pathways for geotechnical data analysis for the investigation of mobile seabed layers were presented. / PHD / Coastal erosion and evolution, marine slope stability, river bank stability, maintenance of navigable water depth, or the stability of offshore structures are some of the modern challenges impacted by subaqueous sediment dynamics. Although, numerous researchers have investigated this issue for decades, some gaps in knowledge still prevail due to its interdisciplinary and complex nature. One of the most intriguing questions related to seabed soil behavior is the characterization of the sediment layers and textures at the seafloor surface being directly involved in sediment transport processes and local geomorphodynamics. These layers are often characterized by a most recent sediment deposition history, and a loose particle arrangements. Accordingly, these sediment layers show almost no resistance to accommodate loads (the sediment strength), and are highly erodible. The strength of surficial layers can be evaluated using portable free fall penetrometers (PFFPs) which are rapid and economic geotechnical site investigation tools designed to geomechanically test seabed surface layers. Nevertheless, there is a lack of data from areas of active sediment dynamics leading to gaps in understanding regarding sediment strength variations affected by active sediment transport processes. This research widens the use of PFFPs into wetland waterways (e.g. channels, lakes, and strait). Moreover, first attempts to quantify the influence of wave forces on sediment beds were also made and promising results were obtained which can open paths to new interdisciplinary. However, the PFFPs are challenged by a lack of physical sediment samples to groundtruth and verify the collected data. Thus, the sampling of such sediment layers is a currently missing part in the framework of in-situ investigations. This dissertation aimed to develop a novel field sampling technology in terms of an add-on unit that can be attached to portable dynamic penetrometers for deployment in areas of active sediment dynamics. Thus, the data to measure sediment strength can be collected simultaneously with physical seabed samples. Different sampler designs were tested and evaluated, and new pathways for joint geotechnical and sedimentological data analysis demonstrated. The results of this research can therefore contribute to the current understanding of seabed sediment behavior.