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Beams are among the most commonly used structural members that are encountered in virtually all systems of structural design at various scales. Mathematical models used to determine the response of beams under external loads are deduced from the three-dimensional elasticity theory through a series of assumptions concerning the kinematics of deformation and constitutive behavior. The kinematic assumptions exploit the fact that such structures do not experience significant trans- verse normal and shear strains and stresses. For example, the solution of the three- dimensional elasticity problem associated with a straight beam is reformulated as a one-dimensional problem in terms of displacements whose form is presumed on the basis of an educated guess concerning the nature of the deformation. In many cases beam structures are subjected to compressive in-plane loads that may cause out-of-plane buckling of the beam. Typically, before buckling and during compression, the beam develops internal axial force that makes the beam stiffer. In the linear buckling analysis of beams, this internal force is not considered. As a result the buckling loads predicted by the linear analysis are not accurate. The present study is motivated by lack of suitable theory and analysis that considers the nonlinear effects on the buckling response of beams. This thesis contains three new developments: (1) the conventional beam theories are generalized by accounting for nonlinear terms arising from εzz and εxz that are of the same magnitude as the von K´arm´an nonlinear strains appearing in εxx. The equations of motion associated with the generalized Euler–Bernoulli and Timoshenko beam theories with the von K´arm´an type geometric nonlinear strains are derived using Hamilton’s principle. These equations form the basis of investigations to determine certain microstructural length scales on the bending, vibration and buckling response of beams used in micro- and nano-devices. (2) Analytical solutions of the conventional Timoshenko beam theory with the von K´arm´an nonlinearity are de- veloped for the case where the inplane inertia is negligible when compared to other terms in the equations of motion. Numerical results are presented to bring out the effect of transverse shear deformation on the buckling response. (3) The development of a nonlinear finite element model for post-buckling behavior of beams.

The primary objective of this study was to develop an empirical model that accounts for factors affecting the demand for international tourist hotels, and that enables demand estimation and projection of demand, in the context of the metropolitan Seoul area. Models were hypothesized to explain market behavior of selected segments of the hotel industry. Demand Model I accounted for international hotel demand incorporating such explanatory variables as price, trade volume and events. Both demand and price were treated as endogenous variables and the time-dependent error processes were all examined. Demand Model I was further expanded by incorporating segmentation variables. The inclusion of segmentation variables into the model in Demand Model II enabled the analysis of the interdependence of market segments that affects demand. Along with the incorporation of a time series structure, a system of equations was employed for Demand Model II. The results indicated that the explanatory variables, which were own price, the number of events and the volume of trade, had a significant impact on international hotel demand. The results from the demand equations also revealed that the demand for a segment is significantly influenced by price and demand for other segments. A cross-segment substitution effect on the demand side is quite relevant for the international lodging market in Seoul and demand for a market segment fluctuates in the same direction as the total market demand changes. From the price equations, the market price of lodging services was found to be related to demand and supply influences simultaneously. The results also indicated that seasonality and economic factors, such as exchange rates and consumer price index, have significant influence directly on international lodging prices. Such factors also were found to have indirect effects on the demand level. / Ph. D.

Indiana University-Purdue University Indianapolis (IUPUI) / The main motivation for nearly all empirical economic research is to provide scientific evidence that can be used to assess causal relationships of interest. Essential to such assessments is the rigorous specification and accurate estimation of parameters that characterize the causal relationship between a presumed causal variable of interest, whose value is to be set and altered in the context of a relevant counterfactual and a designated outcome of interest. Relationships of this type are typically characterized by an effect parameter (EP) and estimation of the EP is the objective of the empirical analysis. The present research focuses on cases in which the regression outcome of interest is a vector that has count-valued elements (i.e., the model under consideration comprises a multi-equation system of equations). This research examines the importance of account for nonlinearity and cross-equation correlations in correlated count regression systems from the perspective of causal estimation and inference. We evaluate the efficiency and accuracy gains of estimating bivariate count valued systems-of-equations models by comparing three pairs of models: (1) Zellner’s Seemingly Unrelated Regression (SUR) versus Count-Outcome SUR - Conway Maxwell Poisson (CMP); (2) CMP SUR versus Single-Equation CMP Approach; (3) CMP SUR versus Poisson SUR. We show via simulation studies that it is more efficient to estimate jointly than equation-by-equation, it is more efficient to account for nonlinearity. We also apply our model and estimation method to real-world health care utilization data, where the dependent variables are correlated counts: count of physician office-visits, and count of non-physician health professional office-visits. The presumed causal variable is private health insurance status. Our model results in a reduction of at least 30% in standard errors for key policy EP (e.g., Average Incremental Effect). Our results are enabled by our development of a Stata program for approximating two-dimensional integrals via Gauss-Legendre Quadrature.

Vienas iš svarbiausių šiuolaikinės kriptografijos uždavinių yra saugių vienkrypčių funkcijų paieška. Dabartiniai mokslininkai skiria šiam klausimui ypatingą demėsį. Šiame darbe yra nagrinėjama viena iš naujausių vienkrypčių funkcijų – matricinio laipsnio funkcija. Ši funkcija yra panaudota netiesinės algebrinės lygčių sistemos sudarymui. Pagrindinis demėsys darbe yra skirtas šios lygčių sistemos analizei bei jos praktiniam taikymui. Nustatysime ar matricinio laipsnio funkcija gali būti panaudota kriptografijoje. Taip pat nustatysime lygčių sistemos sprendinių skaičiaus priklausomybę nuo jos parametrų: matricų eilės m bei grupės Z_p parametro p. / Since the introduction of Diffie-Hellman key agreement protocol in 1976 computer technology has made a giant step forward. Nowadays there is not much time left before quantum computers will be in every home. However it was theoretically proven that discrete logarithm problem which is the basis for Diffie-Hellman protocol could be solved in polynomial time using such computers. Such possibility would make D-H protocol insecure. Thus cryptologists are searching for different ways to improve the security of the protocol by using hard problems. One of the ways to do so is to introduce secure one-way functions (OWF). In this paper a new kind of OWF called the matrix power function will be analyzed. Professor Eligijus Sakalauskas introduced this function in 2007 and later used this function to construct a Diffie-Hellman type key agreement protocol using square matrices. This protocol is not only based on matrix power function but also on commutative matrices which are defined in finite fields or rings. Thus an algebraic non-linear system of equations is formed. The security of this system will be analyzed. It will be shown that we can use matrix power function in cryptography. We will also be analyzing how does the solution of the system depend on system parameters: the order of matrices and a parameter p which defines a finite group Z_p. We will also briefly discuss the usage of this system in real life and the algebraic properties of the suggested OWF.

Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-10-01T10:43:24Z No. of bitstreams: 2 TCC 30_06_2013 Marco Aurélio PROFMAT.pdf: 3494241 bytes, checksum: 199c5af10fd068461af3db98f96eaf49 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Cláudia Bueno (claudiamoura18@gmail.com) on 2014-10-31T19:45:56Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) TCC 30_06_2013 Marco Aurélio PROFMAT.pdf: 3494241 bytes, checksum: 199c5af10fd068461af3db98f96eaf49 (MD5) / Made available in DSpace on 2014-10-31T19:45:56Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) TCC 30_06_2013 Marco Aurélio PROFMAT.pdf: 3494241 bytes, checksum: 199c5af10fd068461af3db98f96eaf49 (MD5) Previous issue date: 2013-04-12 / In this thesis we study linear transformations, eigenvalues and eigenvectors with the objective of solve a system of linear ordinary differential equations with constant coefficients. / Nesta dissertação estudamos transformações lineares, autovalores e autovetores com o intuito de resolvermos um sistema de equações diferenciais ordinárias lineares com coeficientes constantes.

The objective of this study was to evaluate the effect of commodity promotion activities on the United States' hazelnut farmer's economic welfare. Commodity promotion activities, such as generic advertising and research, are the responsibilities of government mandated commodity commissions, such as the Hazelnut Marketing Board (HMB). The HMB is a state mandated cartel, organized under the Agricultural Marketing Agreement Act of 1937 (i.e. the Marketing Order) and amended in 1981, 1986, and 1989 (7 CFR Part 982, FR Doc. 81-14045 FR Doc. 86-18438, FR Doc. 89-26187). HMB promotion activities are funded by taxes levied on U.S. hazelnut farmers. To ensure that promotion provides a net benefit to these farmers this research uses Cost-Benefit Analysis (CBA) of the assessments under various assumptions about the market's conditions. A non-linear system of equations (SEM) with Monte Carlo simulation was utilized to produce these estimates. / Graduation date: 2013

We describe heterogeneous multi-CPU and multi-GPU implementations of Jacobi's iterative method for the 2-D Poisson equation on a structured grid, in both single- and double-precision. Properly tuned, our best implementation achieves 98% of the empirical streaming GPU bandwidth (66% of peak) on a NVIDIA C1060. Motivated to find a still faster implementation, we further consider "wildly asynchronous" implementations that can reduce or even eliminate the synchronization bottleneck between iterations. In these versions, which are based on the principle of a chaotic relaxation (Chazan and Miranker, 1969), we simply remove or delay synchronization between iterations, thereby potentially trading off more flops (via more iterations to converge) for a higher degree of asynchronous parallelism. Our relaxed-synchronization implementations on a GPU can be 1.2-2.5x faster than our best synchronized GPU implementation while achieving the same accuracy. Looking forward, this result suggests research on similarly "fast-and-loose" algorithms in the coming era of increasingly massive concurrency and relatively high synchronization or communication costs.

The work describes techniques for solving systems of linear and differential equations. It explains the definition of conversion from system of linear to system of differential equations. The method of the elementary transmission and the transform algorithm are presented. Both of methods are demonstrated on simply examples and properties of conversion are shown. The work compares fast and accurate solutions of methods and algorithm. For computing examples and solving experiments following programs were used: TKSL and TKSL/C. The program TKSL/C was enriched with the graphic user interface which makes the conversion of systems and computing results easier.

<p>Hyperspectral reflectance data are utilised in many applications, where measured data are processed and converted into physical, chemical and/or biological properties of the target objects and/or processes being studied. It has been proven that crop reflectance data can be used to detect, characterise and quantify disease severity and plant density.</p><p>In this thesis, various methods were proposed and used for detection, characterisation and quantification of disease severity and plant density utilising data acquired by hand-held spectrometers. Following this direction, hyperspectral images provide both spatial and spectral information opening for more efficient analysis.</p><p>Hence, in this thesis, various surface water quality parameters of inland waters have been monitored using hyperspectral images acquired by airborne systems. After processing the images to obtain ground reflectance data, the analysis was performed using similar methods to those of the previous case. Hence, these methods may also find application in future satellite based hyperspectral imaging systems.</p><p>However, the large size of these images raises the need for efficient data reduction. Self organising and learning neural networks, that can follow and preserve the topology of the data, have been shown to be efficient for data reduction. More advanced variants of these neural networks, referred to as the weighted neural networks (WNN), were proposed in this thesis, such as the weighted incremental neural network (WINN), which can be used for efficient reduction, mapping and clustering of large high-dimensional data sets, such as hyperspectral images.</p><p>Finally, the analysis can be reversed to generate spectra from simpler measurements using multiple colour-filter mosaics, as suggested in the thesis. The acquired instantaneous single image, including the mosaic effects, is demosaicked to generate a multi-band image that can finally be transformed into a hyperspectral image.</p>