When using timber for construction purposes it is important to know its strength. One way to do this is by sorting the boards into strength classes that are defined by European standards.  A commonly used method for strength grading is based on dynamic excitation in the longitudinal direction of the board to obtain an average dynamic longitudinal modulus of elasticity (MOE). This in turn correlates with the bending strength of the board in such a way that it can be used as an indicating property (IP) to bending strength. The use of MOE as an IP has proven to give the highest coefficient of determination (R2) to both bending and tensile strength in boards. Through the research described in this thesis, one might find that both reducing the length of a board to half its initial length and by removing the part containing the lowest local MOE in edgewise bending provided similar results, the axial dynamic MOE remaining within a 1% tolerance whereas the lowest IP based on local MOE in edgewise bending increased by 6–7%.

The High Occupancy Vehicle (HOV) lanes on Atlanta, Georgia’s radial I-85 had long been providing sub-optimal throughput in the peak traffic hours, as the two-person occupancy requirement allowed the lanes to become heavily congested. The Georgia Department of Transportation converted 15.5 miles of HOV 2+ lanes to High Occupancy Toll (HOT) lanes, one in each direction on I-85. The lanes use dynamic value pricing to set toll levels based on the volume and average speed of traffic in the lanes. The goal of this research was to investigate the responses to toll lane pricing and the factors that appear to inform lane choice decisions, as well as examining values of travel time savings and toll price elasticity for users of the Express Lanes. This study of the metropolitan Atlanta I-85 Express Lanes operates at the microscopic level to examine the impact of demographic characteristics, congestion levels, and pricing on users’ decisions to use or not use the I-85 Express Lanes. The dissertation examined the value of travel time savings distributions across income segments. The differences in these distributions among lower, medium, and higher income households were marginal at best. The results did not indicate that higher income households had the highest value of travel time savings results, as may have been expected. The modeling work performed here provided a number of insights into toll lane use. The determinants of lane choice decision-making in the morning peak had notable differences from the determinants of the afternoon peak. The initial analysis involved models which were estimated across three different income segments to examine differences in decision making between low, medium, and higher income households. The results indicated that the parameters were largely consistent across the three segments. Further segmenting the households showed that lane choice determinants varied more within the ‘Higher’ income segment than across the original three-segment structure. In particular, the five-segment models illustrated lower elasticities with regard to corridor segment counts and toll levels for the highest-income households in the sample, as well as higher household income level elasticities for afternoon trips by that same cohort. The research was among the first in the available literature to use revealed preference lane use data for both the toll lane users and the unpriced general purpose lane users. The use of household level marketing data, rather than census or survey data, was another unique characteristic of this research. The analysis of value of travel time savings with a demographic component that looks at household income has not yet been seen in the literature; similarly, the findings regarding differing behavior among very high income households appear to be unseen in the existing literature. The results from this analysis, such as willingness-to-pay values for different population segments, will be useful inputs to the decisions surrounding future HOT implementations in the Atlanta region. The use of new data sources, the evaluation of those types of data sources, and the application of methods that have previously been unused in this field make up the primary contributions of this dissertation.

published_or_final_version / Economics and Finance / Master / Master of Economics

The thermomechanical properties of monolayer graphene and the interfacial interactions between graphene and an SiO₂ substrate are investigated in this dissertation using a multiscale approach. The temperature dependent mechanical behavior of graphene with thermal fluctuations is studied by statistical mechanics analysis under harmonic approximation, which is then compared to molecular dynamics simulations. It is found that the amplitude of thermal fluctuation depends nonlinearly on the graphene size due to anharmonic interactions between bending and stretching modes, but a small positive pre-strain could suppress fluctuation amplitude considerably and results in very different scaling behavior. The thermal expansion of graphene depends on two competing effects: positive expansion due to in-plane modes and negative expansion due to out-of-plane fluctuations. The in-plane stress-strain relation of graphene becomes nonlinear even at infinitesimal strain due to the entropic contribution. Consequently, the modulus of graphene depends on strain non-monotonically, with strain stiffening followed by intrinsic softening. Moreover, it is found that the thermomechnical behavior of graphene is dependent on its interactions with environment such as supporting substrate. The interfacial interactions between graphene and SiO₂ substrate is investigated in terms of three perspectives. Firstly, the interaction mechanisms between graphene and SiO₂ substrate are studied by density functional theory (DFT). The dispersion interaction is found to be the predominant mechanism, and the interaction strength is strongly influenced by changes of SiO₂ surface structures due to surface reactions with water. The adhesion energy is reduced when the reconstructed SiO₂ surface is hydroxylated, and further reduced when covered by a monolayer of adsorbed water molecules. Next, we study the interfacial interactions between graphene and a wet substrate that is covered by a liquid-like water film. During the separation of graphene from the wet substrate, MD simulations show evolution of the water from a continuous film to discrete islands. The water bridging effects are further described by continuum models. Finally, a continuum model is developed to predict how the surface roughness may affect the adhesion between graphene membranes and their substrate. / text

This thesis contributes to the literature on the consumption-portfolio choice under uncertainty and is motivated by several empirical failures of the standard consumption-based capital asset pricing model (CCAPM). This canonical model has proven disappointing empirically and has even been questioned whether it is theoretically valuable and practically useful even if it is in some sense the only model we have. The frustration is due to that the model performs no better in practice and generates some well-known consumption puzzles and asset pricing puzzles. The purpose of the thesis is to reexamine these puzzles and then to resolve them. After the debate of Hansen and Singleton (1983) and Hall (1988), the estimates of the elasticity of intertemporal substitution (EIS) of consumption in a representative agent model have not resulted in any consensus. Based on this observation, the first chapter of this thesis is focused on resolving the elasticity puzzle or the unresponsiveness to interest rates. We propose a new theoretical and empirical perspective on the relationship between consumption growth and asset returns. In the spirit of Hansen and Singleton (1983), we demonstrate that observed growth rate of consumption responds not only to a specific asset return but also to other asset returns. Empirically, US postwar quarterly data are used to fit the regression model derived in the chapter, and the sample period is 1953Q2-2001Q2. Empirical results show that the EIS is greater than 0.1, the maximum value considered possible by Hall (1988). Accordingly, we argue that there is no elasticity puzzle in the standard representative agent model. The second chapter provides an explanation for the puzzle of excess sensitivity of consumption to expected income proposed by Flavin (1981). We exploit consumer's superior information (i.e., windfalls in investments and in income) to integrate the consumption Euler equations into a generalized Euler equation. The implications emerging from the equation can refute much of the empirical evidence against the permanent income hypothesis (PIH). In short, we conclude that consumption growth is sensitive to windfalls in income, but not to expected income. Thus, Friedman's prescient insight is being formally corroborated in standard utility theory. The equation also provides an alternative approach permitting one more precisely to estimate the preference parameters and much easier to identify the time-series properties of labor income. Empirical results based on U.S. postwar quarterly data show that the EIS is significantly positive and the labor income should follow a nonstationary second-order autoregressive process. The last chapter of the thesis, chapter three, attempts to address the equity premium puzzle, proposed by Mehra and Prescott (1985), and the risk-free rate puzzle, proposed by Weil (1989). These two asset pricing puzzles have troubled financial economists for nearly two decades. To date, there is still no convincing solution for the equity premium puzzle. The CCAPM is apparently inconsistent with the data, especially the annual data in the 1889-1978 period used by Mehra and Prescott (1985). This has led many economists to question whether the model should be abandoned. The purpose of the chapter is to resolve the two puzzles, and then to consolidate the Lucas-Breeden paradigm embedded in the standard CCAPM. We demonstrate that the equity premium puzzle is resulted from the gaps between the expected asset returns and the actual ones. These gaps have conventionally been regarded as regression disturbances, and explained as good luck or unexpected windfalls. We introduce an alternative way that, using other good luck to explain a given good luck, can help fill in the specific gap. Results of numerical calculations and parametric estimation show that, the gap has been significantly narrowed down and hence the equity premium and risk-free rate puzzles are successfully resolved.

<p>Boundary-contact problems (BCPs) are studied within the frames of</p><p>classical mathematical theory of elasticity and plasticity</p><p>elaborated by Landau, Kupradze, Timoshenko, Goodier, Fichera and</p><p>many others on the basis of analysis of two- and three-dimensional</p><p>boundary value problems for linear partial differential equations.</p><p>A great attention is traditionally paid both to theoretical</p><p>investigations using variational methods and boundary singular</p><p>integral equations (Muskhelishvili) and construction of solutions</p><p>in the form that admit efficient numerical evaluation (Kupradze).</p><p>A special family of BCPs considered by Shtaerman, Vorovich,</p><p>Alblas, Nowell, and others arises within the frames of the models</p><p>of squeezing thin multilayer elastic sheets. We show that</p><p>mathematical models based on the analysis of BCPs can be also</p><p>applied to modeling of the clich\'{e}-surface printing contacts</p><p>and paper surface compressibility in flexographic printing.</p><p>The main result of this work is formulation and complete</p><p>investigation of BCPs in layered structures, which includes both</p><p>the theoretical (statement of the problems, solvability and</p><p>uniqueness) and applied parts (approximate and numerical</p><p>solutions, codes, simulation).</p><p>We elaborate a mathematical model of squeezing a thin elastic</p><p>sheet placed on a stiff base without friction by weak loads</p><p>through several openings on one of its boundary surfaces. We</p><p>formulate and consider the corresponding BCPs in two- and</p><p>three-dimensional bands, prove the existence and uniqueness of</p><p>solutions, and investigate their smoothness including the behavior</p><p>at infinity and in the vicinity of critical points. The BCP in a</p><p>two-dimensional band is reduced to a Fredholm integral equation</p><p>(IE) with a logarithmic singularity of the kernel. The theory of</p><p>logarithmic IEs developed in the study includes the analysis of</p><p>solvability and development of solution techniques when the set of</p><p>integration consists of several intervals. The IE associated with</p><p>the BCP is solved by three methods based on the use of</p><p>Fourier-Chebyshev series, matrix-algebraic determination of the</p><p>entries in the resulting infinite system matrix, and</p><p>semi-inversion. An asymptotic theory for the BCP is developed and</p><p>the solutions are obtained as asymptotic series in powers of the</p><p>characteristic small parameter.</p><p>We propose and justify a technique for the solution of BCPs and</p><p>boundary value problems with boundary conditions of mixed type</p><p>called the approximate decomposition method (ADM). The main idea</p><p>of ADM is simplifying general BCPs and reducing them to a chain</p><p>of auxiliary problems for 'shifted' Laplacian in long rectangles</p><p>or parallelepipeds and then to a sequence of iterative problems</p><p>such that each of them can be solved (explicitly) by the Fourier</p><p>method. The solution to the initial BCP is then obtained as a</p><p>limit using a contraction operator, which constitutes in</p><p>particular an independent proof of the BCP unique solvability.</p><p>We elaborate a numerical method and algorithms based on the</p><p>approximate decomposition and the computer codes and perform</p><p>comprehensive numerical analysis of the BCPs including the</p><p>simulation for problems of practical interest. A variety of</p><p>computational results are presented and discussed which form the</p><p>basis for further applications for the modeling and simulation of</p><p>printing-plate contact systems and other structures of</p><p>flexographic printing. A comparison with finite-element solution</p><p>is performed.</p>

<p>In this thesis, material properties have been examined under extreme conditions in computer-based calculations.</p><p>The research on iron (Fe), nickel (Ni), and ferropericlase (Mg_1-xFe_xO) are not only important for our understanding of the Earth, but also for an improved knowledge of these materials <i>per se</i>.</p><p>An embedded-atom model for Fe demonstrated to reproduce properties such as structure factors, densities and diffusion constants, and was employed to evaluate temperature gradients at Earth core conditions. A similar interaction together with a two-temperature method was applied for the analysis of shock-induced melting of Ni. For Mg_1-xFe_xO, the magnetic transition pressure was shown to increase with iron content. Furthermore, the C₄₄ softening with pressure and iron composition supports the experimentally observed phase transition for Mg_0.8Fe_0.2O at 35 GPa.</p><p>The properties of high density helium (He) is of great interest as the gas is one of the most abundant elements in the solar system. Furthermore, He and neon (Ne) are often used as pressure media in diamond anvil cells. The melting of He showed a possible fcc-bcc-liquid transition starting at T=340 K, P=22 GPa with a Buckingham potential, whereas the bcc phase was not seen with the Aziz form. For Ne, Monte Carlo calculations at ambient pressure showed very accurate results when extrapolating the melting temperatures to an infinite cluster limit. At high pressure, a one-phase <i>ab initio</i> melting curve showed a match with one-phase L-J potential results, which could imply a correspondence between <i>ab initio</i>/classical one-phase/two-phase calculations.</p><p>In the search for hard materials, <i>ab initio</i> calculations for four TiO₂ phases were compared. Just as imposed by experiment, the cotunnite phase was found to be very hard. The anomalous elastic behavior of the superconducting group-<i>V</i> metals V, Nb, Ta was found to be related to shrinking nesting vectors and the electronic topological transition (ETT).</p>

No description available.

Mechanics and biological function of nucleic acids are intimately coupled. The DNA double helix must be opened to allow base pairing of RNA during transcription; RNA must bend and fold in its many cellular functions. Presented in this dissertation are two investigations of mechanical deformations of nucleic acids, conducted with optical tweezers.In the introduction, the mechanical properties of DNA and RNA and their relevance to their cellular functions are introduced, to give the reader context for the results presented in the Chapters 2 and 3. This is followed by an introduction to the theory of semiflexible polymer elasticity. The optical tweezers instruments used in conducting these investigations are then presented, along with calibration procedures and a short introduction to optical trapping physics.Chapter 2 presents an investigation of the effect of downstream DNA tension on initiation by T7 RNA polymerase. A hidden Markov model is fit to force-dependent lifetimes obtained from optical tweezers experiments, allowing us to identify which steps in initiation are force-dependent and estimate rates and transition state distances. We find that 1-2 pN of tension is sufficient to turn o gene expression by causing transcription bubble collapse and destabilizing the bound state. Our force-dependence scheme and estimated transition distances provide independent supportfor the \scrunching" model of initiation.The effects of cation binding and screening on single-stranded helix formation in poly(A) RNA are presented in Chapter 3. Magnesium and calcium bind to poly(A), stabilize the helix, and change its mechanical properties. A new model of helix-coil transitions is presented and used to estimate energetics and mechanical properties.Chapter 4 presents the first fully objective algorithm for use in analyzing the noisy staircaselike data that is often produced by single-molecule fluorescence experiments. A test based on the SIC (BIC) statistic is used in conjunction with a progressive step-placement scheme to locate changepoints (steps) in noisy data. Its performance is compared to other step detection algorithms in use by biophysicists by repeating tests performed in a recent review.Experimental protocols and computer codes used in these investigations are presentedin detail in the appendices.

The objective of this study is to estimate advertising effects on international tourismdemand for the leading Swedish winter destination, Åre. The increasing share of foreigninbound tourists in this destination region creates a strong interest by shareholders toidentify the factors responsible for this trend. According to traditional micro-economictheory, economic factors, such as income and price, are considered as main determinantsfor tourism demand (Song and Witt 2000). However, according to advertising theories(Comanor and Wilson, 1974) and previous tourism research (Bhagwat and Debruine, 2008;Divisekera and Kulendran, 2006), this study additionally focuses on the brand awarenessof Åre as perceived by international tourists. More concretely, advertising theoriesdistinguish between the brand and the information function of advertising (Nelson, 1974).The former function follows the idea that advertising increases the level of productdifferentiation to build up a base of loyal customers. By contrast, the information functionimplies that advertising primarily provides information about products in order to increasethe market transparency. Accordingly, in order to estimate the impact of advertisingexpenditures for off- and online channels as well as promotional activities, furtherexplanatory variables, e.g. mega events, are considered in this study (Salman, 2003; Songet al., 2010). By applying ordinary least square (OLS) methods, demand elasticitycoefficients are estimated for each of the sending countries Norway, Finland, Russia,Denmark and the UK. Results show that advertising is the main significant driver oftourism demand from the UK, Russia and Finland, while a comparably weak advertisingleverage can be shown for Denmark and Norway. Interestingly, in contrast to microeconomictheories tested in previous research, income and tourism price levels reveal asbeing less significant drivers for demand in all analysed tourism markets. In turn, theresults provide evidence that the increased usage of online channels most significantlyaffects consumers’ buying behaviour. Finally, with respect to brand image perception,results reveal that the destination of Åre is perceived as a brand by tourists from Denmark.Moreover, for customers from the countries Norway and Finland, Åre indicates a weakbrand perception, while tourists from Russia and the UK don’t perceive Åre as a brand atall. The results gained by this research conducted at the level of the tourism destinationprovide useful hints about the factors influencing travel behaviour of tourists from maininternational markets. The study supports destination managers to appropriately adjustmarketing campaigns according to the predominant level of brand perception in respectivesending countries. / KK-Foundation project ‘Engineering the Knowledge Destination’ (no. 20100260; Stockholm, Sweden).