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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
391

Experimental And Theoretical Studies Towards The Development Of A Direct 3-D Diffuse Optical Tomographic Imaging System

Biswas, Samir Kumar 01 1900 (has links) (PDF)
Diffuse Optical Tomography is a diagnostic imaging modality where optical parameters such as absorption coefficient, scattering coefficient and refractive index distributions are recovered to form the internal tissue metabolic image. Near-infrared (NIR) light has the potential to be used as a noninvasive means of diagnostic imaging within the human breast. Due to the diffusive nature of light in tissue, computational model-based methods are required for functional imaging. The main goal is to recover the spatial variation of optical properties which shed light on the different metabolic states of tissue and tissue like media. This thesis addresses the issue of quantitative recovery of optical properties of tissue-mimicking phantom and pork tissue using diffuse optical tomography (DOT). The main contribution of the present work is the development of robust, efficient and fast optical property reconstruction algorithms for a direct 3-D DOT imaging system. There are both theoretical and experimental contributions towards the development of an imaging system and procedures to minimize accurate data collection time, overall system automation as well as development of computational algorithms. In nurturing the idea of imaging using NIR light into a fully developed direct 3-D imaging system, challenges from the theoretical and computational aspects have to be met. The recovery of the optical property distribution in the interior of the object from the often noisy boundary measurements on light, is an ill-posed ( and nonlinear) problem. This is particularly true, when one is interested in a direct 3-D image reconstruction instead of the often employed stacking of 2-D cross-sections obtained from solving a set of 2-D DOT problems. In order to render the DOT, a useful diagnostic imaging tool and a robust reconstruction procedure giving accurate and reliable parameter recovery in the scenario, where the number of unknowns far outnumbers the number of independent data sets that can be gathered (for example, the direct 3-D recovery mentioned earlier) is essential. Here, the inversion problem is often solved through iterative methods based on nonlinear optimization for the minimization of a data-model misfit function. An interesting development in this direction has been the development of Broyden’ s and adjoint Broyden’ s methods that avoids direct Jacobian computation in each iteration thereby making the full 3-D a reality. Conventional model based iterative image reconstruction (MoBIIR) algorithm uses Newton’ s and it’s variant methods, where it required repeated evaluation of whole Jacobian, which consumes bulk time in reconstruction process. The explicit secant and adjoint information based fast 2-D/3-D image reconstruction algorithms without repeated evaluation of the Jacobian is proposed in diffuse optical tomography, where the computational time has been decreased many folds by updating the Jacobian successively through low rank update. An alternative route to the iterative solution is attempted by introducing an artificial dynamics in the system and treating the steady-state response of the artificially evolving dynamical system as a solution. The objective is to consider a novel family of pseudo-dynamical 2-D and 3-D systems whose numerical integration in time provides an asymptotic solution to the inverse problem at hand. We convert Gauss-Newton’ s equation for updates into a pseudo-dynamical (PD) form by explicitly adding a time derivative term. As the pseudo-time integration schemes do not need such explicit matrix inversion and depending on the pseudo-time step size, provides for a layer of regularization that in turn helps in superior quality of 2-D and 3-D image reconstruction. A cost effective frequency domain Matlab based 2-D/3-D automated imaging system is designed and built. The complete instrumentation (including PC-based control software) has been developed using a single modulated laser source (wavelength 830nm) and a photo-multiplier tube (PMT). The source and detector fiber change their positions dynamically allowing us to gather data at multiple source and detector locations. The fiber positions are adjusted on the phantom surface automatically for scanning variable size phantoms. A heterodyning scheme was used for reading out the measurement using a lock-in-amplifier. The Matlab program carries out sequence of actions such as instrument control, data acquisition, data organization, data calibration and reconstruction of image. The Gauss-Newton’ s, Broyden’ s, adjoint Broyden’ s and pseudo-time integration algorithms are evaluated using the simulation data as well as data from the experimental DOT system. Validation of the system and the reconstruction algorithms were carried out on a real tissue, a pork tissue with an embedded fat inhomogeneity. The results were found to match the known parameters closely.
392

Design and Characterization of 15nm FinFET Standard Cell Library

Sadhu, Phanindra Datta 01 June 2021 (has links)
The processors and digital circuits designed today contain billions of transistors on a small piece of silicon. As devices are becoming smaller, slimmer, faster, and more efficient, the transistors also have to keep up with the demands and needs of the daily user. Unfortunately, the CMOS technology has reached its limit and cannot be used to scale down due to the breakdown of the transistor caused by short channel effects. Alternative solution to this is the FinFET transistor technology where the gate of the transistor is a 3D fin which surrounds the transistor and prevents the breakdown caused by scaling and short channel effects. FinFET devices are reported to have excellent control over short channel effects, high On/Off Ratio, extremely low gate leakage current and relative immunization over gate edge line roughness. Sub 20 nm is perceived to the limit of scaling the CMOS transistors but FinFETs can be scaled down further due the above-mentioned reasons. Due to these advantages the VLSI industry have now shifted to FinFET in their designs. Although these transistors have not been completely opened to academia. Analyzing and observing the effects of these devices can be pivotal in gaining an in depth understanding of them. This thesis explores the application of FinFETs using a standard cell library developed using these transistors and are analyzed and compared with CMOS transistors. The FinFET package files used to develop these cell is a 15nm FinFET technology file developed by NCSU in collaboration with Cadence and Mentor Graphics. Post design the cells were characterized and then the results were compared to through various CMOS packages to understand and extrapolate conclusions on the FinFET devices.
393

Hodnocení morfologie obličeje pacientů s orofaciálními rozštěpy v návaznosti na terapeutické postupy. / Assessment of facial morphology in patients with orofacial clefts in relation to surgical protocols

Moslerová, Veronika January 2018 (has links)
The presented thesis summarizes the results of research on craniofacial morphology in patients with facial cleft defects in relation to therapeutic approaches (Caganova et al., 2014; Dadáková et al., 2016; Hoffmannova et al., 2016; Hoffmannova et al., 2018; Moslerová et al., 2018). The effect of therapy in individuals with pathological growth disorders cannot be evaluated without detailed auxological studies of control subjects whose facial morphology, longitudinal changes, or manifestations of sexual dimorphism were evaluated upon similar methodology (Koudelová et al. 2015). Therefore, the thesis was conceived as a volume of six publications complemented with a general synthetic introduction into the area of study. Together, the thesis includes probands in a broad age spectrum from birth to 15 years with a total of 294 facial 3D scans, 36 tele-X-ray face images, 3D scans of 112 gypsum palate castings. The methods of geometric morphometry and multidimensional statistics prevail in the assessment. The main clinical part of the thesis deals with the influence of two types of surgery on the facial growth and development of patients with cleft palate, namely secondary spongioplasty (SS) and neonatal cheiloplasty (NCH). Neonatal cheiloplasty (NCH) is the surgery whose effects were studied from several...
394

A Comparative Analysis of Haydn's Horn Concerto and Trumpet Concerto

Adamson, Daniel 08 1900 (has links)
Among the existing solo instrumental concertos of Joseph Haydn's oeuvre are two concertos for brass instruments. These are the Horn Concerto in D Major (Hob. VIId: 3) and Trumpet Concerto in E-flat Major (Hob. VIIe: 1). In addition to their standing as the only two concertos for solo brass instruments written by Haydn in existence, the two concertos provide a unique opportunity for insight into the history of the concerto genre and Haydn's change in compositional style. This is because of their chronological position within Haydn's oeuvre; the Horn Concerto was composed in 1762 during the early years of Haydn's employment with the Esterházy family and the Trumpet Concerto in 1796 as the last known concerto written by Haydn. Significant changes had occurred during that thirty four year time-span, not only in Haydn's life, but also within the field of music. This dissertation examines some of these changes and provides a comparative analysis of these two pieces. More specifically, it employs Schenkerian analysis of the voice-leading and structure of both concertos to examine the transformation in Haydn's compositional style and show the evolution of concerto form. This evolution in style between the Horn Concerto and Trumpet Concerto is most prominently marked by a loosening of compositional constraints, including freer formal procedures, instrumentation, harmonic structures, and an increase in chromaticism (aided by the new chromatic abilities of the trumpet). This document provides an in-depth comparative analysis within an often overlooked genre of music and gives insight into changes in Haydn's compositional style and the concerto genre.
395

Application of in situ shallow subsurface soil spectroscopy (S4) to archaeology and forensics

Lopa, Afrin Jahan 29 April 2021 (has links)
No description available.
396

Slab-Geometry Molecular Dynamics Simulations: Development and Application to Calculation of Activity Coefficients, Interfacial Electrochemistry, and Ion Channel Transport

Crozier, Paul S. 01 January 2002 (has links) (PDF)
Methods of slab-geometry molecular dynamics computer simulation were tested, compared, and applied to the prediction of activity coefficients, interfacial electrochemistry characterization, and ion transport through a model biological channel-membrane structure. The charged-sheets, 2-D Ewald, corrected 3-D Ewald, and corrected particle-particle-particle-mesh (P3M) methods were compared for efficiency and applicability to slab-geometry electrolyte systems with discrete water molecules. The P3M method was preferred for long-range force calculation in the problems of interest and was used throughout. The osmotic molecular dynamics method (OMD) was applied to the prediction of liquid mixture activity coefficients for six binary systems: methanol/n-hexane, n-hexane/n-pentane, methanol/water, chloroform/acetone, n-hexane/chloroform, methanol/ chloroform. OMD requires the establishment of chemical potential equilibrium across a semi-permeable membrane that divides the simulation cell between a pure solvent chamber and a chamber containing a mixture of solvent and solute molecules in order to predict the permeable component activity coefficient at the mixture side composition according to a thermodynamic identity. Chemical potential equilibrium is expedited by periodic adjustment of the mixture side chamber volume in response to the observed solvent flux. The method was validated and shown to be able to predict activity coefficients within the limitations of the simple models used. The electrochemical double layer characteristics for a simple electrolyte with discrete water molecules near a charged electrode were examined as a function of ion concentration, electrode charge, and ion size. The fluid structure and charge buildup near the electrode, the voltage drop across the double layer, and the double layer capacitance were studied and were found to be in reasonable agreement with experimental findings. Applied voltage non-equilibrium molecular dynamics was used to calculate the current-voltage relationship for a model biological pore. Ten 10-nanosecond trajectories were computed in each of 10 different conditions of concentration and applied voltage. The channel-membrane structure was bathed in electrolyte including discrete water molecules so that solvation, entry, and exit effects could be studied. Fluid structure, ion dynamics, channel selectivity, and potential gradients were examined. This work represents the first such channel study that does not neglect the vital contributions of discrete water molecules.
397

Ascending The Pagoda: A Ground-Up Exploration of The Ancient Construction Methods of Dayanta Using Virtual Reality

Yang, Fei 12 August 2022 (has links)
No description available.
398

Altering the Gag Reflex via a Palm Pressure Device: Effects of Hand Topology

Steiner, Samantha R. 05 May 2014 (has links)
No description available.
399

IDS---Intelligent Dougong System: A Knowledge-based and Graphical Simulation of Construction Processes of China’s Song-style Dougong System

Hao, Shilun January 2014 (has links)
No description available.
400

Examining the Conceptual Understandings of Geoscience Concepts of Students with Visual Impairments: Implications of 3-D Printing

Koehler, Karen E. 23 October 2017 (has links)
No description available.

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