Currently, NCHRP Report 356 has published an equation to estimate the ultimate strength of the local zone in normal weight concrete. The local zone is the area of concrete directly ahead of the bearing plate. The equation can be broken into two distinct parts: unconfined bearing strength of concrete enhanced by the A/A_b ratio and the enhancement of strength due to the presence of confining. Research has shown that the strength enhancement of the A/Ab ratio and confining reinforcing is less in lightweight concrete than in normal weight concrete. To determine the strength of the local zone in lightweight concrete 30 reinforced prisms, 2 unreinforced prisms, and concrete cylinders were tested. The dimensions of the prisms were 8 in. x 8 in. x 16 in. and the cylinders were 4 in. x 8 in. cylinders. The simulated reinforcing in the prisms extended only through the top 8 in. of the prism and consisted of either ties or spirals with different spacing or pitch, respectively. To determine the effect of the A/A_b ratio for each spacing or pitch arrangement of the reinforcing, one of two different size bearing plates were used. From the testing performed in this research and other research, it is apparent that the NCHRP equation is unconservative when estimating the ultimate strength of the local zone in lightweight concrete. By modifying both parts of the NCHRP equation it is possible to conservatively predict the ultimate strength of the local zone in lightweight concrete. Also investigated in this thesis are equations to predict the splitting cylinder strength and modulus of elasticity of lightweight concrete. For a sand-lightweight concrete, as defined by ACI 318-05 Building code and Commentary, the splitting tensile strength can be accurately predicted by multiplying the square root of the compressive strength by 5.7. / Master of Science

Some equations of linear elasticity are developed, including those specific to certain actuator structures considered in formation theory. The invariance of the strain-energy under the transformation from rectangular to spherical coordinates is then established for use in two specific formation problems. The first problem, involving an elastic structure with a cylindrical equilibrium configuration, is formulated in two dimensions using polar coordinates. It is shown that L² controls suffice to obtain boundary displacements in H^1/2. The second problem has a spherical equilibrium configuration and utilizes the elastic equations in spherical coordinates. Results similar to those obtained in the two dimensional case are indicated for the three dimensional problem. / Ph. D.

This paper presents a translog model designed to estimate the elasticity of substitution between capital, non-production workers, and production workers using U.S. manufacturing data for the period 1988 to 1997. The elasticity of substitution estimates derived from the translog model suggest that production workers and capital are substitutes, as well as non-production and production workers. Although the estimates do not provide conclusive evidence regarding the degree of substitutability between non-production workers and capital, they do indicate that the degree of substitutability between production workers and capital is greater than it is between non-production workers and capital. / Master of Arts

Cancer is arguably one of the most dangerous diseases and the major causes of death in the modern day. It becomes increasingly harder to treat and cure the disease as it makes progress. Detecting cancer at an early stage can help in preventing it from affecting an organism. However, it is very hard to detect at an early stage. The best possible way to tackle this disease is to first study it at a cellular level. This study aims at identifying various phenotypic traits of these cells in the Dielectrophoresis (DEP) based microfluidic device experimental setup and subsequently classifying the cells from the rest. A general framework for automatic labeling, identifying and classifying the malignant from the dead cells is developed in this work. The framework shows a top-down approach starting from static background subtraction, tracking, automatic labeling, feature extraction and finally classification. The data used in this work are videos of live and dead human prostate cancer (PC-3) cells flowing through the microfluidic device. Previous studies have shown that there are significant differences in morphological attributes between cancerous and non-cancerous cells. We focus mainly on shape, texture and geometry as the prominent attribute in our work and subsequently use them for classification. In this work we obtain good tracking results through optical flow as compared to previous work. For classification, linear classifiers such as logistic regression and linear Support Vector Machine (SVM) showed decent results. The machine learning algorithms use Histogram of Oriented Gradient (HOG) features plus the elliptical features as a combined feature vector. The elliptic features branch out this study to another direction that is useful in calculation of physical properties such as the cell elasticity through video processing and we propose a model for the same for the given setup. Currently, the elasticity of a single cell is calculated using expensive and time consuming procedures such as the atomic force microscopy (AFM). Using our framework, we can potentially obtain elasticity for a batch of cells in much less time. Also, our cell classification algorithm procedure is suitable for real time applications and can be a proposed futuristic concept for selective killing of cells. / Master of Science / Cancer is one of the most dangerous disease and a major cause of death in the modern day. It becomes increasingly harder to treat and cure the disease as it makes progress. Detecting cancer at an early stage can help in preventing it from affecting an organism. However, it is very hard to detect at an early stage. The best possible way to tackle this disease is to first study it at the cellular scale. Our study aims at identifying various characteristics of these cells from videos recorded in a dielectrophoresis (DEP) based cell sorting setup. A general framework for identifying and classifying the malignant from the dead cells is developed in this work. We use computer vision algorithms for detection, tracking and analyzing characteristics of the cells. We use these characteristics to classify the cells into live and dead with an accuracy of 95% using standard classification algorithms used in machine learning such as support vector machine and logistic regression. The study of such properties of the cells also enables us to propose a model to estimate Young’s modulus of elasticity of the cells. Currently, time consuming techniques such as the atomic force microscopy (AFM) are being used to determine the elasticity of a single cell at a time. Using our work, we can potentially obtain elasticity for a batch of cells in much less time. Our cell classification algorithm procedure is suitable for real time applications and can be a proposed futuristic concept for selective killing of cells.

The insect respiratory system serves as a model for both robust microfluidic transport and mate- rial design. In the system, the convective flow of gas is driven through local deformations of the tracheal network, a phenomenon that is dependent on the unique structure and material properties of the tracheal tissue. To understand the underlying mechanics of this method of gas transport, we studied the microstructure and material properties of the primary thoracic tracheal tubes of the American cockroach (Periplaneta americana). We performed quasi-static uniaxial tests on the tissue which revealed a nonlinear stress-strain response even under small deformations. A detailed analysis of the tissue's microstructural arrangement using both light and electron mi- croscopy revealed the primary sources of reinforcement for the tissue as well as heterogeneity on the meso-scale that may contribute to the physiological function of the tracheae during respi- ration. Finally, a custom mechanical testing system was developed with which inflation-extension tests on the tracheae were used to gather data on the biaxial elastic response of the tissue over a wide range of physiologically relevant loading conditions. From information gathered about the material microstructure, a robust constitutive model was chosen to quantify the biaxial response of the tracheae. This model will provide a basis from which to simulate the behavior of tracheal net- works in future computational studies. This study gives the first description of the elastic response of the tracheae which is essential for understanding the mechanics of respiration in insects. Thus it brings us closer to the realization of novel bio-inspired microfluidic systems and materials that utilize mechanical principles from the insect respiratory system. / Ph. D.

The objective of this laboratory research was to investigate the effects of a higher water-cementitious materials ratio on selected properties of concrete mixtures comprising natural pozzolans. The scope of work included testing of six concrete mixtures, including one for each of three natural pozzolans at two water-cementitious materials ratios of 0.44 and 0.48 and one concrete mixture without pozzolan at a water-cementitious materials ratio of 0.44, which was treated as a baseline in this research. The stiffness and strength of each concrete mixture were measured at 1, 3, and 7 days using concrete specimens that were cast immediately after mixing. Additionally, to investigate the effects of delayed casting time, slump was measured at 0, 15, 30, 45, and 60 minutes after mixing, and cylinders were cast at 15, 30, 45, and 60 minutes for stiffness and strength testing at 7 days. Two mixtures comprising natural pozzolan experienced greater slump loss, on average, than the baseline mixture, while all of the other mixtures experienced less slump loss, on average, than the baseline mixture. Overall, the slump losses of mixtures comprising natural pozzolans were 121% and 71% of that of the baseline mixture for water-cementitious materials ratios of 0.44 and 0.48, respectively. Modulus of elasticity values ranged from 1692 ksi to 1794 ksi for mixtures comprising natural pozzolan compared to a value of 1791 ksi for the baseline mixture at 7 days. Compressive strength values ranged from 4087 psi to 4152 psi for mixtures comprising natural pozzolan compared to a value of 4795 psi for the baseline mixture at 7 days. The modulus of elasticity values of mixtures comprising pozzolans were 97% and 94% of that of the baseline mixture for water-cementitious materials ratios of 0.44 and 0.48, respectively, at 7 days. Similarly, the compressive strength values of mixtures comprising pozzolans were 86% and 71% of that of the baseline mixture for water-cementitious materials ratios of 0.44 and 0.48, respectively, at 7 days. Comparisons of the 7-day stiffness and strength results associated with casting delay time for mixtures comprising natural pozzolan with those of the baseline mixture indicate that all mixtures comprising natural pozzolan exhibited lower modulus of elasticity and compressive strength than the baseline mixture. Overall, the modulus of elasticity values of mixtures comprising natural pozzolans were 94% and 84% of that of the baseline mixture for water-cementitious materials ratios of 0.44 and 0.48, respectively, for a casting delay time of an hour. Similarly, the compressive strength values of mixtures comprising natural pozzolans were 85% and 64% of that of the baseline mixture for water-cementitious materials ratios of 0.44 and 0.48, respectively, for a casting delay time of an hour.

Forest and fuel wood are fundamental as sources of energy in almost all developing economies. However there are a few empirical studies addressing the issue of fuelwood production and consumption for rural households. In this paper, household fuelwood use behavior is empirically assessed and policy implications are drawn. with specific reference to Nepal's tarai and mid-hills. Fuelwood production, supply and demand functions are estimated using market, forest and access, and demographic variables characteristic of each region. Both regional and district level supply and demand elasticities are also estimated with respect to opportunity cost of labor, fuelwood price, income, resource stock and access, and demographic variables. The results suggest that rural households produce and consume fuelwood according to the opportunity cost of their labor and market fuel wood prices. Market( economic) variables such as fuel wood price and opportunity costs of labor along with forest stock and its access can provide better insights for assessing household responsiveness to forestry and related development activities and for policy than mere resource stock size or its access. / Master of Science

Assuming that its deformation is both static and homogeneous, a method was devised within the framework of finite strain theory to calculate the elastic constants of a crystal at zero pressure as well as functions of pressure. As this method can be used for a crystal of any symmetry with a variety of potentials, elastic constant calculations were completed for both quartz and cristobalite using the potentials derived by Lasaga and Gibbs (1987, 1988), Tsuneyuki et al. (1988), van Beest et al. (1990) and Boisen and Gibbs (1993). Among the four theoretical potentials derived from force fields calculated for molecule H₆Si₂Q₇, two potentials associated with the SiO bond stretching as well as the OSiO and the SiOSi bond angle bending terms yield reasonable agreements with the experimental data, supporting the assumption that the binding forces in crystals are similar to those in small molecules (Gibbs 1982). Using the semi-empirical potentials, including the SQLOO potential derived with the covalent model (Boisen and Gibbs 1993) and two derived with the ionic model (Tsuneyuki et al. 1988; van Beest et al. 1990), calculations of the elastic constants reproduce the experimental results for both quartz and cristobalite. The pressure derivatives of the elastic constants calculated with these potentials also agree with the experimental results measured for quartz at low pressures and yield pressure derivatives of the bulk modulus that are in close agreement with that observed for quartz. Using the SQLOO potential, although the results of the calculations do not agree with the experimental data as well as those calculated using the two ionic potentials, the agreement of the calculations made with the theoretical potentials was improved significantly. Finally, using the three semi-empirical potentials, the elastic constants were calculated as functions of pressure for quartz and cristobalite up to their transitional pressures. Calculated for both quartz and cristobalite, different behaviors of the elastic constants were found using different potentials. For cristobalite, the variations of its elastic constants and bulk modulus are better modeled by the SQLOO potential as its structural behaviors calculated with the SQLOO potential are consistent with the X-ray diffraction studies. / Master of Science

The Swedish electricity market has seen a surge in demand over the past fifty years. Since the deregulation in 1996, both the demand and supply side of the market has evolved into a competitive space for market actors. This has resulted in unique conditions, characterizing the nordic electricity market as being very much dependent on demand predictability. Demand flexibility has been investigated frequently, but as certain sector developments constantly affect electricity consumption, such as price volatility and green technology development, the price- and temperature elasticities should be revised continuously. Hourly-price contracts specifically, are on the rise in price area SE1, with a rise from 6 percent to 8 percent during the middle of 2023, meaning consumption patterns are of interest for the future as the trend continues. This has, to the authors’ knowledge, not been investigated within the municipality of Luleå, which is the basis for this master’s thesis. Two methodologies were adopted to investigate the elasticities, (1) an ordinary least squares (OLS) regression model and (2) two weighted least squares (WLS) regression models. The results indicate that the price elasticity of demand in Luleå is still very inelastic, with temperature bearing the main explanatory power for household electricity consumption patterns.

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