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Dissertations / Theses on the topic 'Optics – Testing – Mathematical models'

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Published: 4 June 2021

Last updated: 14 February 2022

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1

CHENG, YEOU-YEN. "MULTIPLE-WAVELENGTH PHASE SHIFTING INTERFEROMETRY (OPTICAL-TESTING, ASPHERIC SURFACE)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/187928.

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The problems of combining ideas of phase shifting interferometry (PSI) and synthetic-wavelength techniques to extend the phase measurement range of conventional single-wavelength PSI are investigated. This combination of PSI and synthetic-wavelengths gives multiple-wavelength phase-shifting interferometry the advantages of: (1) larger phase measurement range and (2) higher accuracy of phase measurement. Advantages, error sources, and limitations of single-wavelength PSI are discussed. Some practical methods to calibrate the piezoelectric transducer (PZT), used to phase shift the reference beam, are presented with experimental results. Two methods of two-wavelength PSI are used to solve the 2π ambiguity problem of single-wavelength PSI. For the first method, two sets of phase data (with 2π ambiguities) for shorter wavelengths are calculated and stored in the computer which calculates the new phase data for the equivalent-wavelength λ(eq). The "error magnification effect," which reduces the measurement precision of the first method, is then investigated. The second, more accurate method, uses the results of the first method as a reference to correct the 2π ambiguities in the single-wavelength phase data. Experimental results are included to confirm theoretical predictions. The enhancement of two-wavelength PSI is investigated, and requires the phase data of a third wavelength. Experiments are performed to verify the capability of multiple-wavelength PSI. For the wavefront being measured, the difference of the optical-path-difference (OPD) between adjacent pixels is as large as 3.3 waves. After temporal averaging of five sets of data, the repeatability of the measurement is better than 2.5 nm (0.0025%) rms (λ = 632.8 nm). This work concludes with recommendations for future work that should make the MWLPSI a more practical technique for the testing of steep aspheric surfaces.

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2

Caccavano, Adam. "Optics and Spectroscopy in Massive Electrodynamic Theory." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1485.

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The kinematics and dynamics for plane wave optics are derived for a massive electrodynamic field by utilizing Proca's theory. Atomic spectroscopy is also examined, with the focus on the 21 cm radiation due to the hyperfine structure of hydrogen. The modifications to Snell's Law, the Fresnel formulas, and the 21 cm radiation are shown to reduce to the familiar expressions in the limit of zero photon mass.

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3

Tsang, Suk-chong, and 曾淑莊. "A numerical study of coupled nonlinear Schrödinger equations arising in hydrodynamics and optics." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B26652651.

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4

Seid, Hamid Jemila. "New residuals in multivariate bilinear models : testing hypotheses, diagnosing models and validating model assumptions /." Uppsala : Dept. of Biometry and Engineering, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200583.pdf.

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5

Alluri, Chandra M. "Testing calculation engines using input space partitioning and automation." Fairfax, VA : George Mason University, 2008. http://hdl.handle.net/1920/3228.

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Thesis (M.S.)--George Mason University, 2008.<br>Vita: p. 158. Thesis director: Jeff Offutt. Submitted in partial fulfillment of the requirements for the degree of Master of Science in Software Engineering. Title from PDF t.p. (viewed Aug. 27, 2008). Includes bibliographical references (p. 156-157). Also issued in print.

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6

Banan, Roshan Aerospace Civil &amp Mechanical Engineering Australian Defence Force Academy UNSW. "An engineering approach to modelling ballistic impact on hybrid polymer laminates." Publisher:University of New South Wales - Australian Defence Force Academy. Information Technology & Electrical Engineering, 2009. http://handle.unsw.edu.au/1959.4/44094.

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Hybrid polymer laminates of polycarbonate and PMMA have generated considerable interest among researchers as an alternative to traditional glass armours because of their potential for reduced cost and weight. Generally, the development of ballistic armour is carried out experimentally which is an expensive task in terms of time and cost. Numerical simulation provides a much greater facility to understand the phenomenon of ballistic impact and the effects of various parameters on the response to such impact. In addition it provides an easy means of comparing the impact performance of different materials as well as combination of materials forming hybrid laminates. The aim of this research was to develop a numerical modelling capability to simulate the ballistic response of hybrid polymer laminates, specifically polycarbonate and PMMA, using a commercially available finite element code LS-DYNA. The challenge was to work within the limitations of the material models and the failure algorithms available within LS-DYNA, and still try to reproduce the behaviour observed experimentally by previous researchers, initially on monolithic plates of polycarbonate and PMMA and then on hybrid laminates. The first part of the study focuses on a detailed literature survey on mechanical and dynamic characterisation of polycarbonate and PMMA as well as experimental and numerical studies previously conducted on ballistic behaviour of these materials as well as their combinations. The material properties of the polymers compiled from this literature survey were used as input for the selected LS-DYNA material model. Impact simulations were carried on monolithic and laminated media of polycarbonate and PMMA and where possible these were compared to experimental results. It was observed that the results agreed with the experimental data qualitatively. Quantitatively the results showed some discrepancies which were attributed to the limitations faced in simulating the exact test conditions numerically. Numerical simulations were carried out to study the effects of variations in laminate thickness and plate support diameters as well as to examine the influence of the bond between the layers. Finally the impact response of four different combinations of polycarbonate and PMMA are compared to each other for different laminate thicknesses.

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7

Kleinow, Torsten. "Testing continuous time models in financial markets." Doctoral thesis, [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965412091.

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8

Azadeh, Mohammad. "Reflection and Refraction of Light from Nonlinear Boundaries." PDXScholar, 1994. https://pdxscholar.library.pdx.edu/open_access_etds/4715.

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This thesis deals with the topic of reflection and refraction of light from the boundary of nonlinear materials in general, and saturating amplifiers in particular. We first study some of the basic properties of the light waves in nonlinear materials. We then develop a general formalism to model the reflection and refraction of light with an arbitrary angle of incidence from the boundary of a nonlinear medium. This general formalism is then applied to the case of reflection and refraction from the boundary of linear dielectrics. It will be shown that in this limit, it reduces to the well known Fresnel and Snell's formulas. We also study the interface of a saturating amplifier. The wave equation we use for this purpose is approximate, in the sense that it assumes the amplitude of the wave does not vary significantly in a distance of a wave length. The limits and implications of this approximation are also investigated. We derive expressions for electric field and intensity reflection and transmission coefficients for such materials. In doing so, we make sure that the above mentioned approximation is not violated. These results are compared with the case of reflection and refraction from the interface of a linear dielectric.

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9

Carroll, James M. "The psychometrics of a bipolar valence activation model of self-reported affect." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ56520.pdf.

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10

Scholey, Kenneth Erwin. "Heat tranfser and crack formation in water-cooled zinc fuming furnace jackets." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30078.

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In the zinc slag fuming process, zinc is extracted from lead blast furnace slag by reduction with a coal/air mixture injected into the slag through submerged tuyeres. The furnace is constructed of water-cooled jackets to contain the molten bath and freeze a protective slag layer. The slag layer greatly reduces vessel wear caused by the corrosive and violently agitated bath. However, the jackets are known to develop cracks in the working face panel that initiate on the slag face and propagate towards the water cavity. If the cracks reach the water cavity explosions may result should the molten slag come into contact with the water. In this study an analysis of heat transfer in the jacket has been carried out using in-plant measurements and mathematical modelling. The working face of a water jacket was instrumented with thermocouples and positioned in a fuming furnace at the Trail smelter of Cominco Ltd. Measurements revealed the presence of large thermal transients or temperature "spikes" in the panel approximately 20 cm above the tuyeres. The transients were observed during charging and tapping of the furnace and are likely associated with slag fall-off due to surface wave action and gas injection effects when the bath level is low. Temperatures at the mid-thickness were seen to rise by as much as 180 °C above the steady-state level. Under these conditions large compressive stresses are produced in the panel that are sufficient to cause yielding. Over time, the transients lead to low-cycle fatigue of the working face panel with crack formation initiating at pre-existing surface flaws. A mathematical modelling analysis of the transient freezing phenomena has been carried out using the finite element method. The results indicate that the temperature spikes are associated with the sudden removal of patches of slag and molten slag coming into direct contact with the jacket. The temperature spikes are large enough to generate compressive stresses that cause yielding of the material in the exposed area. In order to reduce the damage caused by the removal of the slag shell an increased number of anchoring studs should be used in critical areas and a higher water circulation velocity should be employed to increase the size of the frozen slag layer and its strength.<br>Applied Science, Faculty of<br>Materials Engineering, Department of<br>Graduate

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11

Leung, Hugh, and 梁修賢. "Analysis of natural and hybrid ventilation in simple buildings." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B26663107.

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12

Furness, Charles Zachary. "Parameter identification of a flexible beam using a modal domain optical fiber sensor." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42058.

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<p>An optical fiber sensor is used for identification of a cantilevered beam under conditions of various concentrated mass loadings. A model of the sensor as well as the dynamic system is developed and used to test the reliability of the identification. Input/output data from an experiment is gathered and used in the identification. A survey of the existing areas of damage detection and parameter identification is included, along with suggestions for incorporating fiber optic sensors into existing techniques. The goal of this research was to show that the fiber sensor can be used for identification purposes, and that it is sensitive to parameter changes within the system (in this case concentrated mass changes).</p><br>Master of Science

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13

Reller, Susan R. "Reliability diagnostic strategies for series systems under imperfect testing." Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/45926.

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An expected cost model was developed for failure detection in series systems under imperfect testing. Type I and type II error probabilities are included and single-pass sample paths are required. The model accounts for the expected costs of testing components, false positive termination, and no-defect-found outcomes. Based on the model, a heuristic was developed to construct the cost minimizing testing sequence. The heuristic algorithm utilizes elementary arithmetic computations and has been successfully applied to a variety of problems. Furthermore, the algorithm appears to be globally convergent. Choice of a starting solution affects the rate of convergence, and guidelines for selecting the starting solution were discussed. Implementation of the heuristic was illustrated by numerical example.<br>Master of Science

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14

Chin, Victor B. L. "The dynamic response of pile-soil interfaces during pile driving and dynamic testing events." Monash University, Dept. of Civil Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/9421.

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15

Welch, Gisele Sawaya. "Application of coherence theory to enhanced backscatter and superresovling optical imaging systems." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/13705.

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16

Rios-Estepa, Rigoberto. "Unraveling the regulation of mint monoterpene biosynthesis development and experimental testing of kinetic mathematical models /." Pullman, Wash. : Washington State University, 2008. http://www.dissertations.wsu.edu/Dissertations/Fall2008/r_rios-estepa_111008.pdf.

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Thesis (Ph. D.)--Washington State University, December 2008.<br>Title from PDF title page (viewed on Jan. 15, 2009). "The Gene and Linda Voiland School of Chemical Engineering and Bioengineering." Includes bibliographical references.

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17

Craig, Bruce A. "Comparison of creep/duration of load performance in bending of Parallam® parallel strand lumber to machine stress rated lumber." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26194.

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A comparison of the creep/duration of load (DOL) performance of a new structural wood composite material called Parallam® parallel strand lumber (PSL) to two grades of machine-stress-rated (HSR) Douglas-fir lumber is presented in this thesis. Evaluation of the creep/DOL performance was made on nominal 2x4 members under constant bending stress at three stress levels. A total of 306 test specimens were evaluated for a 15-1/2 month time period. The analysis suggests that the duration of load effect for Parallam PSL was consistent with the Madison curve for the time period studied while the MSR Douglas-fir lumber was consistent with recent duration of load models developed for structural lumber. The analysis also indicates that the current duration of load adjustment factors can be applied to develop working stresses for Parallam. The creep behaviour of the Parallam PSL was found to be equivalent or better than the two MSR lumber grades under dry-service conditions. Furthermore, evidence of linear viscoelastic behaviour was found for all test materials within the range of applied stresses evaluated. Two mathematical models of creep were fitted to the creep data and compared. A '4-parameter linear viscoelastic' model fitted the creep data better than an empirical 'power curve' model. The model parameters developed provide a basis for estimating the mean creep behaviour and variability in creep response for these materials under in-service load conditions for dry-service environments.<br>Forestry, Faculty of<br>Graduate

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18

Greiner, Daniel Joseph. "Influence of fluorine versus hydroxzyl content on the optics of the amblygonite-montebrasite series." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/50060.

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For 11 crystals of the amblygonite-montebrasite series LiAlPO₄(F,OH) ranging in composition from 4.0 to 91.8 mole percent fluorine with only two containing significant sodium, 2V and principal refractive indices were determined to 0.5° and 0.0005, respectively, by spindle-stage methods. If F < 60 mole percent, as is true for the vast majority of natural specimens, fluorine can usually be estimated to within 2 mole percent from the equation F = -66.3 + 1.08 * 2V<sub>Z</sub> as well as from similar regression equations involving the refractive indices α, β, and γ. Above 60 mole percent F, the optical properties are less sensitively (and non-linearly) related to fluorine content. Estimates of F proved feasible despite significant substitution of Na for Li. By contrast, this substitution may introduce significant errors when estimating F by methods involving lattice parameters. Progressive substitution of (OH), a natural dipole involving a covalent bond, for the relatively non-polarizable F anion caused all three principal refractive indices to increase; γ increases more than α or ß because its corresponding principal vibration direction Z becomes sub-parallel to the O···H vector in the structure as (OH) content increases.<br>Master of Science<br>incomplete_metadata

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19

Yamashita, Tsuyoshi. "Unraveling photonic bands : characterization of self-collimation in two-dimensional photonic crystals." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-06072005-104606/.

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Thesis (Ph. D.)--School of Materials Science and Engineering, Georgia Institute of Technology, 2006.<br>Summers, Christopher, Committee Chair ; Chang, Gee-Kung, Committee Member ; Carter, Brent, Committee Member ; Wang, Zhong Lin, Committee Member ; Meindl, James, Committee Member ; Li, Mo, Committee Member.

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20

Wong, Chun-mei May, and 王春美. "The statistical tests on mean reversion properties in financial markets." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31211975.

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21

Li, Feng Engineering &amp Information Technology Australian Defence Force Academy UNSW. "Development of super resolution techniques for finer scale remote sensing image mapping." Awarded by:University of New South Wales - Australian Defence Force Academy. Engineering & Information Technology, 2009. http://handle.unsw.edu.au/1959.4/44098.

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In this thesis, methods for achieving finer scale multi-spectral classification through the use of super resolution (SR) techniques are investigated. A new super resolution algorithm Maximum a Posteriori based on the universal hidden Markov tree model (MAP-uHMT) is developed which can be applied successfully to super-resolve each multi-spectral channel before classification by standard methods. It is believed that this is the first time that a true super resolution algorithm has been applied to multi-spectral classification, and results are shown to be excellent. Image registration is an important step for SR in which misalignment can be measured for each of many low resolution images; therefore, a new and computationally efficient image registration is developed for this particular application. This improved elastic image registration method can deal with a global affine warping and local shift translations based on coarse to fine pyramid levels. The experimental results show that it can provide good registration accuracy in less computational time than comparable methods. Maximum a posteriori (MAP) is adopted to deal with the ill-conditioned problem of super resolution, wherein a prior is constructed based on the universal hidden Markov tree (uHMT) model in the wavelet domain. In order to test this prior for MAP estimation, it is first tested in the simpler and typically ill-conditioned problem of image denoising. Experimental results illustrate that this new image denoising method achieves good performance for the test images. The new prior is then extended to SR. By combining with the new elastic image registration algorithm, MAP-uHMT can super resolve both some natural video frames and remote sensing images. Test results with both synthetic data and real data show that this method achieves super resolution both visually and quantitatively. In order to show that MAPuHMT is also applicable more widely, it is tested on a sequence of long-range surveillance images captured under conditions of atmospheric turbulence distortion. The results suggest that super resolution may have been achieved in this application also.

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22

Sidwall, Thygesen Signe, Astrid Berghult, and Camilla Öhman. "Prediction of elastic properties of nanofibrillated cellulose and microcrystalline cellulose : by mathematical models and tensile testing." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-177367.

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23

王偉洪 and Wai-hung Wong. "A study of constitutive models on engineering properties of Hong Kong marine clay." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31214745.

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24

Wong, Man-kie, and 黃文基. "A study of capacity predictions for driven piles by dynamic pile testing." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37106120.

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25

Tan, Falong. "Projected adaptive-to-model tests for regression models." HKBU Institutional Repository, 2017. https://repository.hkbu.edu.hk/etd_oa/390.

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This thesis investigates Goodness-of-Fit tests for parametric regression models. With the help of sufficient dimension reduction techniques, we develop adaptive-to-model tests using projection in both the fixed dimension settings and the diverging dimension settings. The first part of the thesis develops a globally smoothing test in the fixed dimension settings for a parametric single index model. When the dimension p of covariates is larger than 1, existing empirical process-based tests either have non-tractable limiting null distributions or are not omnibus. To attack this problem, we propose a projected adaptive-to-model approach. If the null hypothesis is a parametric single index model, our method can fully utilize the dimension reduction structure under the null as if the regressors were one-dimensional. Then a martingale transformation proposed by Stute, Thies, and Zhu (1998) leads our test to be asymptotically distribution-free. Moreover, our test can automatically adapt to the underlying alternative models such that it can be omnibus and thus detect all alternative models departing from the null at the fastest possible convergence rate in hypothesis testing. A comparative simulation is conducted to check the performance of our test. We also apply our test to a self-noise mechanisms data set for illustration. The second part of the thesis proposes a globally smoothing test for parametric single-index models in the diverging dimension settings. In high dimensional data analysis, the dimension p of covariates is often large even though it may be still small compared with the sample size n. Thus we should regard p as a diverging number as n goes to infinity. With this in mind, we develop an adaptive-to-model empirical process as the basis of our test statistic, when the dimension p of covariates diverges to infinity as the sample size n tends to infinity. We also show that the martingale transformation proposed by Stute, Thies, and Zhu (1998) still work in the diverging dimension settings. The limiting distributions of the adaptive-to-model empirical process under both the null and the alternative are discussed in this new situation. Simulation examples are conducted to show the performance of this test when p grows with the sample size n. The last Chapter of the thesis considers the same problem as in the second part. Bierens's (1982) first constructed tests based on projection pursuit techniques and obtained an integrated conditional moment (ICM) test. We notice that Bierens's (1982) test performs very badly for large p, although it may be viewed as a globally smoothing test. With the help of sufficient dimension techniques, we propose an adaptive-to-model integrated conditional moment test for regression models in the diverging dimension setting. We also give the asymptotic properties of the new tests under both the null and alternative hypotheses in this new situation. When p grows with the sample size n, simulation studies show that our new tests perform much better than Bierens's (1982) original test.

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Zhu, Xuehu. "Model-adaptive tests for regressions." HKBU Institutional Repository, 2015. https://repository.hkbu.edu.hk/etd_oa/189.

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In this thesis, we firstly develop a model-adaptive checking method for partially parametric single-index models, which combines the advantages of both dimension reduction technique and global smoothing tests. Besides, we propose a dimension reduction-based model adaptive test of heteroscedasticity checks for nonparametric and semi-parametric regression models. Finally, to extend our testing approaches to nonparametric regressions with some restrictions, we consider significance testing under a nonparametric framework. In Chapter 2, “Model Checking for Partially Parametric Single-index Models: A Model-adaptive Approach", we consider the model checking problems for more general parametric models which include generalized linear models and generalized nonlinear models. We develop a model-adaptive dimension reduction test procedure by extending an existing directional test. Compared with traditional smoothing model checking methodologies, the procedure of this test not only avoids the curse of dimensionality but also is an omnibus test. The resulting test is omnibus adapting the null and alternative models to fully utilize the dimension-reduction structure under the null hypothesis and can detect fully nonparametric global alternatives, and local alternatives distinct from the null model at a convergence rate as close to square root of the sample size as possible. Finally, both Monte Carlo simulation studies and real data analysis are conducted to compare with existing tests and illustrate the finite sample performance of the new test. In Chapter 3,Heteroscedasticity Checks for Nonparametric and Semi-parametric Regression Model: A Dimension Reduction Approach", we consider heteroscedasticity checks for nonparametric and semi-parametric regression models. Existing local smoothing tests suffer severely from the curse of dimensionality even when the number of covariates is moderate because of use of nonparametric estimation. In this chapter, we propose a dimension reduction-based model adaptive test that behaves like a local smoothing test as if the number of covariates is equal to the number of their linear combinations in the mean regression function, in particular, equal to 1 when the mean function contains a single index. The test statistic is asymptotically normal under the null hypothesis such that critical values are easily determined. The finite sample performances of the test are examined by simulations and a real data analysis. In Chapter 4，Dimension Reduction-based Significance Testing in Nonparametric Regression", as nonparametric techniques need much less restrictive conditions than those required for parametric approaches, we consider to check nonparametric regressions with some restrictions under sufficient dimension reduction structure. A dimension-reduction-based model-adaptive test is proposed for significance of a subset of covariates in the context of a nonparametric regression model. Unlike existing local smoothing significance tests, the new test behaves like a local smoothing test as if the number of covariates is just that under the null hypothesis and it can detect local alternative hypotheses distinct from the null hypothesis at the rate that is only related to the number of covariates under the null hypothesis. Thus, the curse of dimensionality is largely alleviated when nonparametric estimation is inevitably required. In the cases where there are many insignificant covariates, the improvement of the new test is very significant over existing local smoothing tests on the significance level maintenance and power enhancement. Simulation studies and a real data analysis are conducted to examine the finite sample performance of the proposed test. Finally, we conclude the main results and discuss future research directions in Chapter 5. Keywords: Model checking; Partially parametric single-index models; Central mean subspace; Central subspace; Partial central subspace; Dimension reduction; Ridge-type eigenvalue ratio estimate; Model-adaption; Heteroscedasticity checks; Significance testing.

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Uliana, David A. "The effects of earthquake excitations on reticulated domes." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/45667.

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<p>Comparisons were made on the behavior of two full-sized reticulated domes subjected to uniform static loads only and uniform static loads with earthquake excitations. Space truss elements were used in the dome models. The stiffness matrix of the space truss element allows for the nonlinear strain-displacement behavior and the stress-strain behavior of the material is modeled with a bilinear approximation. The nonlinear solution technique is the Newton-Raphson method while the direct integration technique is the Newmark- Beta method.</p> <p>The joint displacements for the static and the dynamic analyses were compared for both domes along with the axial stresses in all members. The percentage increases in the axial stresses of the dynamic analyses as compared to those of the static analyses were determined.</p> <p> The reticulated domes used in the study were found to bet capable of withstanding the earthquake excitations when subjected to various uniform loads without failure.</p><br>Master of Science

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28

Robertson, Scott James. "Hawking radiation in dispersive media." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/1900.

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Hawking radiation, despite its presence in theoretical physics for over thirty years, remains elusive and undetected. It also suffers, in its original context of gravitational black holes, from conceptual difficulties. Of particular note is the trans-Planckian problem, which is concerned with the apparent origin of the radiation in absurdly high frequencies. In order to gain better theoretical understanding and, it is hoped, experimental verification of Hawking radiation, much study is being devoted to systems which model the spacetime geometry of black holes, and which, by analogy, are also thought to emit Hawking radiation. These analogue systems typically exhibit dispersion, which regularizes the wave behaviour at the horizon but does not lend itself well to analytic treatment, thus rendering Hawking’s prediction less secure. A general analytic method for dealing with Hawking radiation in dispersive systems has proved difficult to find. This thesis presents new numerical and analytic results for Hawking emission spectra in dispersive systems. It examines two black-hole analogue systems: it begins by introducing the well-known acoustic model, presenting some original results in that context; then, through analogy with the acoustic model, goes on to develop the lesser-known fibre-optical model. The following original results are presented in the context of both of these models: • an analytic expression for the low-frequency temperature is found for a hyperbolic tangent background profile, valid in the entire parameter space; it is well-known that the spectrum is approximately thermal at low frequencies, but a universally valid expression for the corresponding temperature is an original development; • an analytic expression for the spectrum, valid over almost the entire frequency range, when the velocity profile parameters lie in the regime where the low-frequency temperature is given by the Hawking prediction; previous work has focused on the low-frequency thermal spectrum and the characterization of the deviations from thermality, rather than a single analytic expression; and • a new unexplored regime where no group-velocity horizon exists is examined; the Hawking spectra are found to be non-zero here, but also highly non-thermal, and are found, in the limit of small deviations, to vary with the square of the maximum deviation; the analytic expression for the case with a horizon is found to carry over to this new regime, with appropriate modifications. Furthermore, the thesis examines the results of a classical frequency-shifting experiment in the context of fibre-optical horizons. The theory of this process is presented for both a constant-velocity and a constantly-decelerating pulse, the latter case taking account of the Raman effect. The resulting spectra are at least qualititively explained, but there is a discrepancy between theory and experiment that has not yet been accounted for.

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29

Ngan, Yuk-tung Henry, and 顏旭東. "Motif-based method for patterned texture defect detection." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40203608.

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30

Conners, Terrance E. "The effect of moisture gradients on the stiffness and strength of yellow-poplar." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/74713.

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Wood with a uniform moisture distribution is known to have different mechanical properties compared to wood with a non-uniform moisture distribution. Moisture gradients are likely to develop in full-size members tested in the In-Grade Testing Program and might therefore affect the test results. The purpose of this study was to mathematically model the effect of desorption moisture gradients on the stiffness and strength of yellow-poplar beams. An additional objective was to experimentally determine gradient effects in yellow-poplar beams. Three-dimensional finite-element modeling was employed and several subsidiary models were developed. Among these was a three-parameter segmented model for fitting digitized tension and compression stress-strain curves. Unlike previous models (such as the Ramberg-Osgood model), this model has a linear slope up to the point approximately corresponding to the proportional limit. A methodology was also devised whereby most hardwood and softwood elastic constants can be estimated at any moisture content. Data are required at one moisture content. Equilibrated uniaxial testing was conducted at four moisture contents to acquire data for the finite-element model. It was found that the longitudinal Young's moduli in tension and compression were approximately equal at 6% and 18% moisture content; the compression modulus was greater at 12%, but the tension modulus was greater for green specimens. Intersection points for tension and compression mechanical properties may be different. Tests of small clear yellow-poplar beams indicated that moisture gradients induced at 12% equilibrium moisture content had little effect on the modulus of rupture up to 19% average moisture content. At higher moisture contents, gradient-containing beams were significantly stronger than equilibrated beams when comparisons were made at identical moisture contents. Modulus of elasticity data exhibited a similar trend, although differences between equilibrated and non-equilibrated beams were observed below 19% moisture content. The finite-element program was moderately successful in predicting the effects of moisture gradients on the strength and stiffness of yellow-poplar beams. Computer time and storage constraints limited the accuracy of the solutions. Predicted trends were verified by the experimental data. Modeling of full-size lumber indicated that significant moisture gradients will likely influence the stiffness and strength of higher quality lumber.<br>Ph. D.

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31

Darmenov, Anton. "Developing and testing a coupled regional modeling system for establishing an integrated modeling and observational framework for dust aerosol." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28217.

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Thesis (M. S.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2009.<br>Committee Chair: Sokolik, Irina; Committee Member: Curry, Judith; Committee Member: Kalashnikova, Olga; Committee Member: Nenes, Athanasios; Committee Member: Stieglitz, Marc.

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32

Pearce, Annie R. "Sustainability and the built environment : a metric and process for prioritizing improvement opportunities." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19611.

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33

Beller, Douglas K. "Alternate Computer Models of Fire Convection Phenomena for the Harvard Computer Fire Code." Digital WPI, 2000. https://digitalcommons.wpi.edu/etd-theses/892.

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"Alternate models for extended ceiling convection heat transfer and ceiling vent mass flow for use in the Harvard Computer fire Code are developed. These models differ from current subroutines in that they explicitly consider the ceiling jet resulting from the fire plume of a burning object. The Harvard Computer fire Code (CFC) was used to compare the alternate models against the models currently used in CFC at Worcester Polytechnic Institute and with other available data. The results indicate that convection heat transfer to the ceiling of the enclosure containing the fire may have been previously underestimated at times early in the fire. Also, the results of the ceiling vent model provide new insight into ceiling vent phenomena and how ceiling vents can be modeled given sufficient experimental data. this effort serves as a qualitative verification of the models as implemented; complete quantitative verification requires further experimentation. Recommendations are also included so that these alternate models may be enhanced further. "

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34

沈維祥 and Weixiang Shen. "Advanced battery capacity estimation approaches for electric vehicles." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31243575.

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Dogan, Deniz. "Numerical optimization for mixed logit models and an application." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/28190.

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Thesis (M. S.)--Industrial and Systems Engineering, Georgia Institute of Technology, 2008.<br>Committee Chair: Anton Kleywegt; Committee Co-Chair: Alexander Shapiro; Committee Member: Charles Rosa; Committee Member: Shabbir Ahmed; Committee Member: Sigrun Andradottir.

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Meurer, Thomas. "Wave propagation in hysteretic media." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19090.

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37

Lanzas, Lourdes Eneida 1962. "A parametric study on the behavior of slender reinforced concrete frames." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/276945.

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By using a nonlinear computer analysis, a parametric study is developed in order to examine the accuracy of the Moment Magnifier Method of the American Concrete Institute Code (ACI 318-83). The variables used in the parametric study are: axial load intensity, P/Po; column reinforcement ratio, rho; slenderness ratio, klu; shape of column cross section, flexural stiffness ratio, and distribution of axial loads. In the parametric study, 216 cases of single bay fixed-base portal frames are examined. The higher moment for each one of these frames at failure are then compared with the design moment predicted by the Moment Magnifier Method of the American Concrete Institute Code (ACI 318-83). The Moment Magnifier Method proved to be very conservative when the columns are subjected to high level of axial loads and when the slenderness ratio is increased.

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Lam, Wai-yin, and 林慧賢. "Plate-reinforced composite coupling beams: experimental and numerical studies." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37311797.

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39

Chan, Ka-ho Enoch, and 陳家灝. "Experimental and numerical studies of concrete beams prestressed with unbonded tendons." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40988004.

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40

Jeyanayagam, Samuel S. "Engineering analysis of a Chinese-type anaerobic digester." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49800.

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41

Andrawis, Alfred S. "A new compound modulation technique for multi-channel analog video transmission on fiber." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/39877.

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Present analog optical fiber multi-channel video transmission systems are very sensitive to laser nonlinearities and are consequently limited in the optical modulation depth (OMD) that may be used. This, in turn limits the power budget achievable, signal-to-noise ratio, and the channel capacity. In this dissertation a new analog transmission technique for multi-channel TV transmission on fiber USIng frequency modulation/pulse amplitude modulation/time division multiplexing (FM/TDM) is described and compared with present digital and analog systems. Parameters for the proposed system are selected and the relationship between the performance and parameter values is discussed. Analysis and simulations indicate that the proposed system has a very low sensitivity to nonlinearities and is similar to that of digital systems, and much better than current Frequency Modulated/Frequency Division Multiplexed (FM/FDM) systems. This permits the use of higher OMD (as high as in digital systems), which results in achieving a high signal-to-noise ratio and a large power budget. Analysis of the number of channels as a function of adjacent channel intersymbol interference indicates that the proposed system has a better spectral efficiency than present analog systems. Simulations are also used to predict the performance of the proposed system with laser diodes poorer than the ones presently used for multi-channel analog systems. Considerably poorer lasers may be used while achieving acceptable transmission quality. Finally, carrier-to-noise penalty caused by timing errors and jitter effects are analyzed.<br>Ph. D.

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Kim, Hoan-Kee. "Multi-scale nonlinear constitutive models using artificial neural networks." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22613.

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Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008.<br>Committee Chair: Rami M Haj-Ali; Committee Member: Arash Yavari; Committee Member: Donald W. White; Committee Member: Erian Armanios; Committee Member: Kenneth M. Will.

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Jain, S. K. "Analysis of the pressuremeter test by FEM formulation of the elasto-plastic consolidation." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/53881.

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A decade has passed since the development of the self-boring pressuremeter (SBPM). Even though the device has been recognized by the geotechnical engineering profession as having high promise for evaluating in-situ stress-strain behavior of soils, its use is limited. In large part, this is due to the fact that there are important unanswered questions about the SBPM test. One of the major issues concerns the influence of drainage in the soil as it is sheared. In clays, the test is assumed to be undrained, but there is no way to control this other than by the rate of loading and no method has been put forth heretofore to define the required rate. This dissertation addresses the drainage issue by applying a numerical model capable of simulating the pressuremeter test under variety of conditions. To develop parameters for the soil model, a comprehensive laboratory testing effort was needed. The validity of the numerical model and the soil parameters is established by comparing it to SBPM tests performed in the field. The numerical model uses the finite element method in a special code capable of handling large strains, consolidation effects, and nonlinear soil behavior. Particular attention is addressed to the issue of pore pressure development and its dissipation. Relative influences of important soil parameters such as the permeability are checked against various rates of loading in the SBPM test. The results demonstrate that drainage likely occurs in most cases using conventional test procedures, and that this, in turn, leads to an error in interpretation of SBPM data. Based on the findings in the analyses, a procedure is proposed which should lead to a more rational method of performing the SBPM test where nearly undrained conditions are desired.<br>Ph. D.

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董旭東 and Xudong Dong. "Stress distribution and failure mode of dental ceramic structures under Hertzian indentation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31241621.

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Honeycutt, Robert Mahone. "Acoustic emission based control of wood drying." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/39781.

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Drying is one of the most critical process steps in converting trees to a marketable material for use in high value wood products. The primary reasons for drying wood are to prevent biological deterioration and to improve mechanical strength and dimensional stability. The purpose of this research study was to develop an approach to the control of drying red oak lumber that monitors acoustic emission as the basis for setting environmental conditions throughout the drying process. Northern red oak (Quercus sp.) was chosen for this study because it is one of the more difficult woods grown in the United States to dry without inducing defects. This study was limited to end drying of short lengths of full sized red oak lumber.<br>Ph. D.

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46

Archibald, Charles Mark. "Parametric spatial modal analysis of beams." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/37278.

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Modal analysis is the experimental characterization of the dynanlical behavior of a structure. Recent advances in laser velocimetery have made available to the experimentalist a rich, new source of vibration data. Data can now be obtained from many different spatial locations on a structure. A method is presented to use this new data for the analysis of beams. Two approaches are investigated: minimum residual methods and boundary condition methods. The minimum residual approaches include autoregressive methods and non-linear least squares techniques. Significant contributions to sample rate considerations for parametric sinusoidal estimation resulted from this research. The minimum residual methods provide a good connection between the measured data and the fitted model. However, they do not yield a true modal decomposition of the spatial data. The boundary condition approach provides a complete modal model that is based on the spatial data and is completely compatible with classical beam theory. All theoretical constraints are included in the procedure. Monte Carlo investigations describe the statistical characteristics of the methods. Experiments using beams validate the methods presented. Advantages and limitations of each approach are discussed.<br>Ph. D.

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47

Seward, Lori Welte. "A multiple stress, multiple component stress screening cost model." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/41578.

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<p>Environmental stress screening is used to enhance reliability by decreasing the number of failures experienced during customer use. It is suggested that added benefit can be gained by applying multiple stresses rather than a single stress, as is done presently. A further modification is to apply the stress at the assembly level, accelerating different types of components at the same time. Different component E A e acceleration effects must then be considered.</p> <p> The problem these modifications present is how to choose the appropriate stress levels and the time duration of the stress screen. A cost model is developed that trades off the cost of a field failure with the cost of applying a multiple stress, multiple component stress screen. The objective is to minimize this cost function in order to find an economical stress regimen.</p> <p> The problem is solved using the software package GINO. The interesting result is that if a stress is used at all during the stress screen, the maximum amount of stress is the economic choice. Either the cost of stressing is low enough to justify the use of a stress, in which case the maximum amount of stress is used, or the cost is too high and the stress is not used at all.</p><br>Master of Science

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Kumar, Neraj. "Detection of Variable Retention Time in DRAM." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/2103.

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This thesis investigates a test method to detect the presence of Variable Retention Time (VRT) bits in manufactured DRAM. The VRT bits retention time is modeled as a 2-state random telegraph process that includes miscorrelation between test and use. The VRT defect is particularly sensitive to test and use conditions. A new test method is proposed to screen the VRT bits by simulating the use conditions during manufacturing test. Evaluation of the proposed test method required a bit-level VRT model to be parameterized as a function of temperature and voltage conditions. The complete 2-state VRT bit model combines models for the time-in-state and for the retention-time including miscorrelation. A copula is used to model the eect of miscorrelation between test and use. The proposed VRT test algorithm runtime is estimated as a function of VRT test coverage, test temperature and test voltage.

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Xufen, Wu. "Numerical modeling of modified Newtonian dynamics in galaxies : testing the external field effects." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1706.

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Galaxies are natural laboratories for testing fundamental physics on the nature of the dark matter. MOdified Newtonian Dynamics (MOND) has been tested for over 20 years on small and large scales. While there are several versions of how MOND extrapolates to the large scales, and these versions are not yet fully successful, the original Bekenstein-Milgrom version of MOND is fully predictive and works very well on galaxy scales. However, little work has been done to explore this theory beyond fitting the rotation curves and Tully-Fisher relation of isolated disc galaxies. So far little is known of MONDian elliptical galaxies accelerating in any galaxy cluster. A defining feature of MOND is that internal dynamics of the galaxy depends on the overall acceleration of the galaxy. The existence of cuspy triaxial equilibria for elliptical galaxies is the minimal requirement to MOND. With the PhD project here, I constructed and then further studied the evolution and stability of gravitationally bound systems resembling like cuspy elliptical galaxies, both in isolation and when embedded in a uniform external field. I also studied the escape speeds from spiral galaxies, in particular by comparing the potentials of the Milky Way Galaxy in the Cold Dark Matter (CDM) and MOND frameworks.

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Spies, Ruben Daniel. "Mathematical modelling, finite dimensional approximations and sensitivity analysis for phase transitions in shape memory alloys." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-06062008-165948/.

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