Prediction of Meltpool Depth in Laser Powder Bed Fusion Using In-Process Sensor Data, Part-Level Thermal Simulations, and Machine Learning

The goal of this thesis is the prevention of flaw formation in laser powder bed fusion additive manufacturing process. As a step towards this goal, the objective of this work is to predict meltpool depth as a function of in-process sensor data, part-level thermal simulations, and machine learning. As motivated in NASA\u27s Marshall Space Flight Center specification 3716, prediction of meltpool depth is important because: (1) it can serve as a surrogate to estimate process status without the need for expensive post-process characterization, and (2) the meltpool depth provides an avenue for rapid qualification of microstructure evolution. To achieve the aforementioned objective, twenty-one Inconel 718 samples were designed and built with a variety of processing parameters ranging from a power of 200 W to 370 W and a scan speed of 670 mm/s to 1250 mm/s. These parts were characterized and the meltpool depth was measured through optical microscopy. A combination of part-level thermal simulations from a spectral graph theory method and in-process sensor data from infrared thermal camera and a meltpool imaging pyrometer were used as inputs to simple machine learning models to predict the meltpool depth. The meltpool depth was correctly predicted with an accuracy of F-Score 85.9%. This exploratory work provided an avenue for rapid prediction of microstructure evolution in metal additive manufacturing. Advisors: Jeffrey Shield and Prahalada Ra

Spatio-temporal influence of tundra snow properties on Ku-band (17.2 GHz) backscatter

During the 2010/11 boreal winter, a distributed set of backscatter measurements was collected using a ground-based Ku-band (17.2 GHz) scatterometer system at 26 open tundra sites. A standard snow-sampling procedure was completed after each scan to evaluate local variability in snow layering, depth, density and water equivalent (SWE) within the scatterometer field of view. The shallow depths and large basal depth hoar encountered presented an opportunity to evaluate backscatter under a set of previously untested conditions. Strong Ku-band response was found with increasing snow depth and snow water equivalent (SWE). In particular, co-polarized vertical backscatter increased by 0.82 dB for every 1 cm increase in SWE (R2 = 0.62). While the result indicated strong potential for Ku-band retrieval of shallow snow properties, it did not characterize the influence of sub-scan variability. An enhanced snow-sampling procedure was introduced to generate detailed characterizations of stratigraphy within the scatterometer field of view using near-infrared photography along the length of a 5m trench. Changes in snow properties along the trench were used to discuss variations in the collocated backscatter response. A pair of contrasting observation sites was used to highlight uncertainties in backscatter response related to short length scale spatial variability in the observed tundra environment

Meiotic cellular rejuvenation is coupled to nuclear remodeling in budding yeast.

Production of healthy gametes in meiosis relies on the quality control and proper distribution of both nuclear and cytoplasmic contents. Meiotic differentiation naturally eliminates age-induced cellular damage by an unknown mechanism. Using time-lapse fluorescence microscopy in budding yeast, we found that nuclear senescence factors - including protein aggregates, extrachromosomal ribosomal DNA circles, and abnormal nucleolar material - are sequestered away from chromosomes during meiosis II and subsequently eliminated. A similar sequestration and elimination process occurs for the core subunits of the nuclear pore complex in both young and aged cells. Nuclear envelope remodeling drives the formation of a membranous compartment containing the sequestered material. Importantly, de novo generation of plasma membrane is required for the sequestration event, preventing the inheritance of long-lived nucleoporins and senescence factors into the newly formed gametes. Our study uncovers a new mechanism of nuclear quality control and provides insight into its function in meiotic cellular rejuvenation

Intention to Pursue a Sales Career: A Dyadic Study of Students and Parents Extended Abstract

Typical career choice selection studies generally have been one sided focusing on students or parents independently. This dyadic study aims to analyze student and their parent influencers to determine what will be the strongest influencer of a student to pursue a career in sales. “Because the dyad is arguable the fundamental unit of interpersonal interaction and relations, family relations such as a parent and their child/student have a powerful dyadic component” (Kenny et al., 2006, p1). Therefore, understanding the influencers of this career choice selection may lead to interventions for increasing the number of students to pursue a career in sales

EXTENDED SCREENS FOR AN ONLINE MEETING BY GROUPING NEIGHBORS

An online meeting typically includes some number of participants or users. Techniques are presented herein that significantly enhance the user experience of users who join an online meeting from the same physical location and sit next to each other. Aspects of the presented techniques take the best advantage of neighboring screens in an extended screen manner, which can significantly improve user experience. For example, all of the duplicated local and remote video grids may be removed and all of the remote video grids may be shown in as large a fashion as possible. Broadly, aspects of the techniques presented herein include three steps – a local group initiator finding their neighbors, selecting some of the found neighbors for grouping, and setting the layout for the selected neighbors

Leisure and recreation in New Zealand: A research register (1974-1991)

In March 1990 the Department of Parks, Recreation and Tourism at Lincoln University was commissioned and funded, in part, by the Hillary Commission for Recreation and Sport (now Sport, Fitness and Leisure) to compile a comprehensive register of research into leisure and recreation in New Zealand. The financial support of the Hillary Commission and Lincoln University must be recognised.A register of research on leisure and recreation is important to researchers, practitioners and students as well as to the generral public. The value of such a register is enhanced when it is assembled in concise format for easy reference and when it is an extension of similar projects from previous years. This register builds usefully on, and complements the earlier bibliographies of Jorgensen (1974), Neave (1977) and Middleton (1981), all of which are referenced in the present publication. The major aim of this project is to make available to researchers, and others interested in research, a listing of much of the research which has been conducted on this topic since 1974. The volume will assist researchers to locate reports or papers of interest and for their work. It provides a reasonably comprehensive picture of recreation research activity in New Zealand. Leisure and recreation research in New Zealand has been undertaken by a wide range of individuals and organisations, with much of this research not being readily accessible. Access to this infonnation was gained by researchers and practitioners drawing our attention to people and organisations involved in relevant research which otherwise might have been neglected. In addition the papers and reports held by libraries, unpublished material and research in progress is included in this volume. It is envisaged that the register, and in particular the researcher/practitioner listing, will have the useful outcome of putting researchers in touch with each other. Experience suggests that direct discourse between researchers is often as valuable as reading formal research reports. Leisure and recreation has been defined in the broadest terms. embracing recreational tourism and travel, sport and physical education, arts and cultural activities, outdoor recreation, home-based leisure, non-formal learning, and including those activities and experiences not always recognised as recreational, such as drinking, gambling and vandalism. Similarly, the settings and situations are many and varied, including leisure centres, sports fields, libraries, urban sub-divisions, rivers, ski-fields, national parks, beaches, hotels, restaurants, botanical gardens, zoos and shopping centres to name but a few. The disciplinary focus includes research relating to the social, natural and medical sciences, as well as the practical application of these. The nature of research has been interpreted widely, and includes not only empirical research, but also work which is conceptual and has a policy focus

response of canola to seed-placed liquid ammonium thiosulfate and ammonium

Non-Peer Reviewe

Effect of alcohol addition on the movement of petroleum hydrocarbon fuels in soil

Groundwater contamination by fuel spills from aboveground and underground storage tanks has been of growing concern in recent years. This problem has been magnified by the addition of oxygenates, such as ethanol and methyl-tertiary-butyl ether (MTBE) to fuels to reduce vehicular emissions to the atmosphere. These additives, although beneficial in reducing atmospheric pollution, may, however, increase groundwater contamination due to the co-solvency of petroleum hydrocarbons and by the provision of a preferential substrate for microbial utilisation. With the introduction of ethanol to diesel fuel imminent and the move away from MTBE use in many states of the USA, the environmental implications associated with ethanol additive fuels must be thoroughly investigated. Diesel fuel movement was followed in a 1-m soil column and the effect of ethanol addition to diesel fuel on this movement determined. The addition of 51% ethanol to diesel fuel was found to enhance the downward migration of the diesel fuel components, thus increasing the risk of groundwater contamination. A novel method using soil packcd HPLC columns allowed the influence of ethanol on individual aromatic hydrocarbon movement to be studied. The levels of ethanol addition investigated were at the current additive level (approx. 25%) for ethanol additive fuels in Brazil and values above (50%) and below (10%) this level. An aqueous ethanol concentration above 10% was required for any movement to occur. At 25% aqueous ethanol, the majority of hydrocarbons were mobilised and the retention behaviour of the soil column lessened. At 50% aqueous ethanol, all the hydrocarbons were found to move unimpeded through the columns. The retention behaviour of the soil was found to change significantly when both organic matter content and silt/clay content was reduced. Unexpectedly, sandy soil with low organic matter and low silt/clay was found to have a retentive behaviour similar to sandy subsoil with moderate silt/clay, but little organic matter. It was concluded that sand grains might have a more important role in the adsorption of petroleum hydrocarbons than first realised. This method has shown that soil packed HPLC columns can be used to provide a quick estimate of petroleum hydrocarbon, and possibly other organic contaminant, movement in a variety of different soil types

Drivers of Pasture Growth in Perennial Ryegrass Pastures in Northern New Zealand Dairy Pastures

The critical importance of pasture production to New Zealand’s economic performance has been widely recognised. However, a number of critical issues have been identified that limit dairy industry growth, including sub-optimal pasture condition and poor pasture persistence. Dairy farm systems in the Waikato and Bay of Plenty provinces in the upper North Island of New Zealand are predominantly pasture-based, with a temperate climate and they represent around 30% of New Zealand’s total number of dairy farms (LIC and DairyNZ, 2012). This project was established to quantify pasture performance and identify factors that drive that performance. We established a network of on-farm trials where case studies of pasture renewal practices and outcomes were developed. Ten farms in each province were monitored for three consecutive years – four paddocks from each province are considered here