Increased land use change near fragile ecosystems can affect the ecosystem energy balance leading to increased global warming. One component of surface energy balance is soil storage heat flux. In past work, a complex thermal behavior was noticed in the shrink-swell sediment of the upper Nueces Delta (upper Rincon) during summer months as it dried. Soil storage heat flux was found to first increase, then decrease, as the soil dried. It was suggested that the complex behavior was due to the relationship between thermal diffusivity and soil moisture, where thermal diffusivity increases to a local maximum before decreasing with respect to decreasing soil moisture. This study explores the observed phenomenon in a controlled laboratory environment by relating the sediment shrinkage curve to changing heat transfer properties. Due to the complicated nature of the drying-shrinking sediment, it was necessary to measure the sediment shrinkage curve and heat transfer properties in separate experiments. The shrinkage curve was found by correlating measured sample volume with gravimetric moisture content. Heat transfer properties were found using a single needle heat pulse probe. A normalized gravimetric moisture content was used as a common variable to relate the shrinkage curve and heat transfer data. Data suggests that the shrink-swell Rincon sediment portrays different behavior in drying than that which occurs for a non-shrink-swell soil. For the shrink-swell Rincon sediment, thermal conductivity is seen to increase with decreasing moisture, the suggested mechanism being increased surface area contact between particles as the shrinking sediment dries.

This dissertation presents an experimental and theoretical study of subsynchronous rotordynamic instability in rotors caused by interference and shrink fit interfaces. The experimental studies show the presence of strong unstable subsynchronous vibrations in two different rotor setups with interference and shrink fit interfaces that were operated above their first critical speeds. The unstable vibrations occur at the first natural frequency of the rotor-bearing system. The instability caused complete wreckage of the test rig in one of the setups showing that these vibrations are potentially dangerous to the safe operation of rotating machines. The two different rotor setups that are studied are a single-disk rotor mounted on a uniform diameter shaft and a two-disk rotor with an aluminum sleeve shrink fitted to it at the outer surface of the two disks. In the single-disk rotor, an adjustable interference arrangement between the disk and the shaft is obtained through a tapered sleeve arrangement, which acts as the interference fit joint. The unstable sub-synchronous vibrations originate from slippage in the shrink fit and the interference fit interfaces that develop friction forces, which act as destabilizing cross-coupled moments when the rotor is operated above its first critical speed. The unique contribution offered through this work is the experimental validation of a physically correct model of internal friction which models the destabilizing mechanism as a system of cross-coupled internal moments at the shrink fit interface. The dissertation describes stability simulations of various test rotor setups using the correct internal moments model. A commercial finite-element based software called XLTRCTM is used to perform rotordynamic simulations for stability studies. The method of stability study is the computation of eigenvalues of the rotor-bearing system. A negative real part of the eigenvalue indicates instability. The simulations include the test rotors that were experimentally observed as stable and unstable with shrink and interference fit interfaces in their assemblies. The dissertation also describes the simulations of various imagined rotor configurations with shrink fit interfaces, and seeks to explain how configurations differ on rotordynamic stability depending upon several rotor-bearing parameters such as geometry and elastic properties, as well as upon the amount of internal friction parameters, which differ from configuration to configuration.

Estimation of the covariance matrix of asset returns is a key component of portfolio optimization. Inherent in any estimation technique is the capacity to inaccurately reflect current market conditions. Typical of Markowitz portfolio optimization theory, which we use as the basis for our analysis, is to assume that asset returns are stationary. This assumption inevitably causes an optimized portfolio to fail during a market crash since estimates of covariance matrices of asset returns no longer reflect current conditions. We use the market crash of 2008 to exemplify this fact. A current industry-standard benchmark for estimation is the Ledoit covariance matrix, which attempts to adjust a portfolio’s aggressiveness during varying market conditions. We test this technique against the CALM (Covariance Adjustment for Liability Management Method), which incorporates forward-looking signals for market volatility to reduce portfolio variance, and assess under certain criteria how well each model performs during recent market crash. We show that CALM should be preferred against the sample convariance matrix and Ledoit covariance matrix under some reasonable weight constraints.

Problems associated with shrink-swell soils are well known geotechnical problems that have been studied and researched by many geotechnical researchers for many decades. Potentially shrink-swell soils can be found almost anywhere in the world especially in the semi-arid regions of the tropical and temperate climate. Foundation slabs on grade on shrink-swell soils are one of the most efficient and inexpensive solutions for this kind of problematic soil. It is commonly used in residential foundations or any light weight structure on shrink-swell soils. Many design methods have been established for this specific problem such as Building Research Advisory Board (BRAB), Wire Reinforcement Institute (WRI), Post- Tensioning Institute (PTI), and Australian Standards (AS 2870) design methods. This research investigates most of these methods, and then, proposes a moisture diffusion soil volume change model, a soil-weather interaction model, and a soil-structure interaction model. The proposed moisture diffusion soil volume change model starts with proposing a new laboratory test to determine the coefficient of unsaturated diffusivity for intact soils. Then, it introduces the development of a cracked soil diffusion factor, provides a chart for it, and explains a large scale laboratory test that verifies the proposed moisture diffusion soil volume change model. The proposed soil-weather interaction model uses the FAO 56-PM method to simulate a weightless cover performance for six cities in the US that suffer significantly from shallow foundation problems on shrink-swell soils due to seasonal weather variations. These simulations provide more accurate weather site-specific parameters such as the range of surface suction variations. The proposed weather-site specific parameters will be input parameters to the soil structure models. The proposed soil-structure interaction model uses Mitchell (1979) equations for moisture diffusion under covered soil to develop a new closed form solution for the soil mound shape under the foundation slab. Then, it presents a parametric study by carrying out several 2D finite elements plane strain simulations for plates resting on a semiinfinite elastic continuum and resting on different soil mounds. The parametric study outcomes are then presented in design charts that end with a new design procedure for foundation slabs on shrink-swell soils. Finally, based on the developed weather-soil-structure interaction models, this research details two procedures of a proposed new design method for foundation slabs on grade on shrink-swell soils: a suction based design procedure and a water content based design procedure.

abstract: While scan-based trading (SBT) is a growing trend in the retail industry, evidence suggests that many SBT initiatives have contributed only to the retailers’ bottom line at the suppliers’ expense. This research attempts to disclose some of the causes of SBT failure as a collaborative inventory management initiative and identify SBT’s integrative potential using both positivistic and normative research methodologies. In the first chapter, SBT contracts are analyzed through the lens of Agency Theory. By focusing on unique inventory ownership and risks considerations resulting from retailers managing supplier-owned inventory without bearing the cost of inventory shrinkage, the effect of SBT on inventory shrinkage is examined empirically using a data set from a packaged bakery manufacturer. The results show that inventory shrinkage tends to be higher under SBT contracts compared to traditional vendor-managed inventory (VMI) contracts. The study highlights a potential loss in efficiency in food supply chains reflected in higher shrinkage under SBT contracts. The second chapter aims to identify conditions under which SBT contracts could be mutually beneficial for retailers and suppliers. Using stylized game theoretic models involving a retailer and a supplier of a product with limited shelf life, the study finds that, while inventory shrinkage may be amplified under SBT contracts compared to VMI contracts due to the decreased retailer’s incentive to manage inventory at the store, SBT could help suppliers minimize inventory overage and underage under high demand uncertainty. The integrative potential for SBT contracts, thus, lies in the trade-off between inventory shrinkage and forecasting accuracy. In the third paper, the role of bargaining power on the performance of SBT contracts is examined. Based on the bargaining literature, it is hypothesized that perceptions of bargaining power can be reshaped in the bargaining process through concession tactics. The results of a negotiation experiment show that, while powerful retailers do tend to have the upper hand in negotiating SBT contracts, weak suppliers could ameliorate or even overcome retailer power by offering services as a concession in a way that the product-service bundle improves the value of their offerings in the eyes of the retailers. / Dissertation/Thesis / Doctoral Dissertation Business Administration 2016

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Old ideas about how parents might access mental health services for their children are fading and some exciting new prospects are beginning to emerge! The facilitators of this webinar have expertise in mental health service delivery and social environmental barriers to service seeking and have been funded by the National Institute of Health for their research in these areas. They will discuss current research on why parent’s don’t seek help as well as some new ideas about how to “get them in” including offering services in new settings like schools and integrated care. Building on this new information, the focus will be on exploring cutting edge ideas on service provision. Discussion will focus on how schools, parents, physicians, and mental health service providers might work together to develop provocative strategies for getting help where it’s needed and improving child outcomes.

A study of 12 expansive soils in four major physiographic provinces in Virginia was initiated to examine and quantify the relationship between shrink-swell potential, shrink-swell indices, and soil properties. The mineralogy classes, soil series, and (physiographic provinces, parent materials) examined include smectitic -- Jackland and Waxpool (Triassic, diabase), Iredell (Piedmont, hornblende); vermiculitic -- Kelly (Triassic, thermal shale); kaolinitic -- Cecil (Piedmont, granite gneiss), Davidson (Triassic, diabase); and mixed -- Carbo and Frederick (Valley and Ridge, limestone), Craven and Peawick (Coastal Plain, fluvial and marine sediments), and Mayodan and Creedmoor (Triassic, sandstones). Three sites in each of the 12 map units were described and major horizons sampled for physical, chemical, and mineralogical laboratory analysis. An expansive soil rating system, termed the Expansive Soil Index (ESI), was developed using the soil properties best correlated with shrink-swell potential. The sum of swelling 2:1 minerals, swell index, liquid limit, and CEC gave expansive soil potential ratings (ESI) for each soil series. The higher the ESI, the greater the shrink-swell potential. Smectite distributions within the soil profiles were investigated. Smectite concentration in the clay fraction increases with depth in soils formed from diabase and thermally altered shale. Smectite weathers to kaolinite and hydroxy-interlayered vermiculite with increasing proximity to the soil surface thus accounting for the observed decrease in smectite toward the soil surface. The highest amount of smectite from the granite gneiss, limestone, sandstones and shales, and Coastal Plain sediments were in the Bt2 horizon where maximum expression of the argillic horizon occurs. Smectite contents decrease away (upwards and downwards) from the maximum in the Bt2 horizon. A satellite study focused on locating and quantifying the variability within five map units in the Culpeper (Triassic) Basin in northern Virginia. Variability of the shrink-swell indices and related properties are high in all map units. Dissimilar inclusions could adversely affect foundations if a home is sited on both moderate and high shrink-swell soils. Although there is extreme variability in the map units, the variability occurs within the delineations of each map unit. Each delineation within an individual map unit contains similar levels of variability. / Ph. D.

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O objetivo deste trabalho é apresentar um novo método para a remoção do ruído Poisson em imagens de mamografia digital adquiridas com baixa dosagem de radiação. Sabe-se que a mamografia por raios X é o exame mais eficiente para a detecção precoce do câncer de mama, aumentando consideravelmente as chances de cura da doença. No entanto, a radiação absorvida pela paciente durante o exame ainda é um problema a ser tratado. Estudos indicam que a exposição à radiação pode induzir a formação do câncer em algumas mulheres radiografadas. Apesar desse número ser significativamente baixo em relação ao número de mulheres que são salvas pelo exame, existe a necessidade do desenvolvimento de meios que viabilizem a diminuição da dose de radiação empregada. No entanto, uma redução na dose de radiação piora a qualidade da imagem pela diminuição da relação sinal-ruído, prejudicando o diagnóstico médico e a detecção precoce da doença. Nesse sentido, a proposta deste trabalho é apresentar um método para a filtragem do ruído Poisson que é adicionado às das imagens mamográficas quando adquiridas com baixa dosagem de radiação, fazendo com que ela apresente qualidade equivalente àquela adquirida com a dose padrão de radiação. O algoritmo proposto foi desenvolvido baseado em adaptações de algoritmos bem estabelecidos na literatura, como a filtragem no domínio Wavelet, aqui usando o Shrink-thresholding (WTST), e o Block-matching and 3D Filtering (BM3D). Os resultados obtidos com imagens mamográficas adquiridas com phantom e também imagens clínicas, mostraram que o método proposto é capaz de filtrar o ruído adicional incorporado nas imagens sem perda aparente de informação. / The aim of this work is to present a novel method for removing the Poisson noise in digital mammography images acquired with reduced radiation dose. It is known that the X-ray mammography is the most effective exam for early detection of breast cancer, greatly increasing the chances of healing the disease. However, the radiation absorbed by the patient during the exam is still a problem to be treated. Some studies showed that mammography can induce breast cancer in a few women. Although this number is significantly low compared to the number of women who are saved by the exam, it is important to develop methods to enable the reduction of the radiation dose used in the exam. However, dose reduction led to a decrease in image quality by means of the signal to noise ratio, impairing medical diagnosis and the early detection of the disease. In this sense, the purpose of this study is to propose a new method to reduce Poisson noise in mammographic images acquired with low radiation dose, in order to achive the same quality as those acquired with the standard dose. The method is based on well established algorithms in the literature as the filtering in Wavelet domain, here using Shrink-thresholding (WTST) and the Block-matching and 3D Filtering (BM3D). Results using phantom and clinical images showed that the proposed algorithm is capable of filtering the additional noise in images without apparent loss of information.