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Development of a Boiling Surface Effectiveness Parameter by Modeling and Quantifying the Net Coolant Flow Rate
Get PDFBoiling dynamics and related heat transfer mechanisms have been widely studied for several decades. During that time, incredible progress has been made on quantifying bubble departure phenomena including growth rate, departure frequency, associated natural and forced convection, and radiation additions to the overall heat transfer rate. With this, the thermal community has been able to fully characterize the boiling curve throughout its distinct regimes; natural convection, isolated bubble, fully developed nucleate boiling, transition, and film boiling. Previous work has primarily been focused on what heat transfer coefficients are achievable, how to reduce incipience overshoot, and increasing the Critical Heat Flux (CHF). These findings have proven critical in developing analytical solutions to predict boiling characteristics without performing time intensive and high cost experiments. Even with these models, they tend to only be accurate for specific fluid/surface combinations, and they have been extensively studied. As new surfaces emerge and claims of incredible thermal performance arise, there has been no consistent way to substantiate those claims. The community does not have a standard test for boiling heat transfer effectiveness. The best way to determine the effectiveness of a two-phase heat transfer surface is to extract as much heat from it while using as little quenching coolant as possible. This study quantifies that value, the net coolant flow rate to a boiling surface, for a plain, microfinned, and microstructured copper surface. Particle Image Velocimetry (PIV) is used to quantify the requisite quenching fluid flow rate needed to sustain nucleate boiling without onset of the catastrophic CHF event. By comparing the net coolant flow rate of one standard/bare/plain surface to an enhanced one, a boiling surface effectiveness parameter is developed. This would be similar to that of a fin effectiveness parameter as this quantifies the utility of adding fins to an otherwise bare surface. The experimental data presented in this work was also compared to an analytical model showing that this coolant flow rate to the surface can be predicted to within 4% and 30% error at low and high heat fluxes, respectively
Customizable Visual Traces for Program Explanations
Get PDFCorrectness and efficiency are important properties of programs. However, to support maintenance and debugging, the programs should also be understandable. Program explanations also play a vital role in educational settings, enhancing the understanding of programs among students.
Proof trees provide a sound basis for generating dynamic explanations of programs. But these proof trees can grow huge very quickly, even for simple programs. In this thesis, I present (1) a new notation for traces that aims towards their succinct representation, (2) a new variant of the Call-By-Value semantics to generate small traces, and (3) a query language that can be used to adapt traces to individual needs.
I will also present an evaluation of our approach on 21 well-known examples that shows reduction in the overall size of traces by at least 79% using the transformations provided by the query language
The Experiences of Women in First-Term Calculus: Factors Affecting Mathematical Confidence
Get PDFAs industries relating to science, technology, engineering, and mathematics in America continue to grow, employers will need more mathematicians and mathematically able workers than are currently graduating. Women are an underrepresented portion of these graduates, and researches say that this could be due to the difference between women’s and men’s mathematical confidence. Calculus I is a required course for all STEM majors, and this course has proven to be a leaky point in the pipeline, a point at which women leave STEM degree programs at significantly higher rates than men. The purpose of this study is to explore what factors in Calculus I most affect the mathematical confidence of women in STEM-related majors. I share how I analyzed data that I collected during focus group interviews, and what patterns emerged in my analysis. I also offer an insight into the experiences of a few of my participants; these act as case studies. I explore how identity plays a key role in the experiences of these women enrolled in calculus I. Finally, I offer suggestions as to what universities and professors can do in their classrooms in order to improve the retention rates and experiences of women in their courses
Determination of Total Nucleotides, Nitrogenous Bases and Degradation By-Products with Respect to Various Processing and Preservation Techniques for Alaska Pollock (Gadus chalcogrammus) and Yellowfin Sole (Limanada aspera)
Get PDFThe primary goal of this research was to determine the concentration and composition of nucleotides, as nucleoside monophosphates and nucleobases, in the underutilized reproductive organs (milt and roe) of Alaska pollock (Gadus chalcogrammus) and yellowfin sole (Limanda aspera). Changes in concentrations of these nucleotides and nucleotide analogs were observed with respect to various storage and processing techniques. Samples were freeze-dried (-40°C), dessicated (70°C) and oven dried in laboratory ovens at two temperatures (100°C and 120°C). Several extraction/digestion techniques were employed to evaluate total nucleotides present. DNA extracts were analyzed for total nucleotide monophosphates and nucleotide composition of the DNA extract. Methods for extracting total DNA from reproductive tissues from pollock were evaluated using various chemical techniques including acid digestion, phenol-chloroform extraction and QIAGEN® extractions kits. Once extracted, DNA was digested into nucleotide monomers (deoxyadenosine monophosphate (dAMP), deoxyguanosine monophosphate (dGMP), deoxycytidine monophosphate (dCMP) and thymidine monophosphate (TMP)) using an enzymatic (endonuclease) digestion. In a different analysis, total nucleobases and nucleobase composition as purine and pyrimidine bases (cytosine, guanine, thymine, adenine, uracil, hypoxanthine and xanthine) were also determined; these results were used to assess total DNA, RNA and free nucleotides in dried milt meal. Quantification of the nucleotides was achieved using a reverse-phase high performance liquid chromatography (RP-HPLC) system. Degradation by-products of adenosine monophosphate (as adenosine monophosphate (AMP), inosine monophosphate (IMP), inosine and hypoxanthine) were also determined via HPLC after perchloric acid digestion. This knowledge will serve as a basis of determining the feasibility of creating a consistent, cost-effective source of nucleotide or nucleotide analogs for potential use in the formulation of aquaculture feed, nutraceuticals (e.g. baby formula and nucleotide complexes) and other potential products
A Preliminary Methodology For Automating Functional Modeling
Get PDFThis thesis is the combination of two research publications working towards automating functional modeling. Functional modeling is an underutilized yet critical tool for concept generation and product design. Understanding the difficulty both novice and expert designers have in implementing functional modeling in their design process, this research sets out to streamline the process of functional decomposition and help designers include functionality in their designs. Using existing consumer product data from a Design Repository database, we developed an algorithm to find correlations between component and function and flow, returning component-function-flow (CFF) combinations. The automation process organizes these connections by component-function-flow frequency (CFF frequency), thus allowing the creation of linear functional chains.
The first publication explores a preliminary method to automate the generation of linear functional chains using an Automated Frequency Calculation and Thresholding (AFCT) Algorithm. We use datasets of various scale and specificity to find correlations between functions and flows for components of products in the Design Repository. We use the results to predict the most likely functions and flows for a component, and then verify the accuracy of our algorithm by cross-validating a subsection of the data against the automation results. We then apply existing grammar rules to order the functions and flows in a linear functional chain.
The second publication describes the methodology used to develop a new metric, which we refer to as weighted confidence, to provide insight on the fidelity of the data returned by the above AFCT algorithm. In the previous publication, we found that CFF frequency is the best metric in formulating the linear functional chain for an individual component; however, we found that this metric did not account for prevalence and consistency in the Design Repository data. The weighted confidence metric is calculated by taking the harmonic mean of two metrics we extracted from our data, prevalence, and consistency.
Improving these automation results, allows us to further our ultimate objective of this research, which is to enable designers to automatically generate functional models for a product given constituent components
Design of Compact Passive Components and Circuits for RF and Millimeter-Wave Integrated Circuit in Silicon
No full textEmerging fifth generation (5G) and beyond 5G communication networks are stimulating the design of radio-frequency (RF) and millimeter-wave (mmWave) integrated circuits for wireless transceivers systems. While co-integration of active circuits and diverse passive components becomes feasible at these high operating frequencies, circuit design is faced with significant challenges due to the complicated electromagnetic coupling between components and to interconnects in close proximity. The conventional coupling reduction approach requiring large separation distances wastes valuable silicon area and, hence, increases cost. Furthermore, the long interconnections needed because of the large separation of components introduce additional electromagnetic parasitic which may degrade circuit performance. Therefore, innovative designs of highly compact passive components and circuits while maintaining low coupling are needed for viable on-chip integration.
This dissertation proposes a general inductor layout design methodology achieving compact footprints with negligible magnetic coupling between inductors without sacrificing individual inductor performance. The innovative design approach is based on the principle of magnetic flux cancellation. A comprehensive study of the coupling characteristics between two partially overlapped inductors is presented along with full-wave electromagnetic (EM) simulation and on-wafer measurements.
Furthermore, systematic design guidelines have been developed to enable efficient implementation of the compact inductor layout strategy in different applications. Compact designs/redesigns of various RF and mmWave integrated lumped-element passive circuits including a power amplifier (PA) matching network, RF and mmWave bandpass filters (BPFs), and a single-pole-double-throw (SPDT) switch are presented, demonstrating the practicality and reliability of the proposed compact layout design approach in RF and mmWave applications
Effects of Stage 0 Stream Restoration on Aquatic Macroinvertebrate Production
Get PDFContemporary stream restoration efforts increasingly prioritize restoring natural stream processes to regain lost ecosystem functions. Stage 0 stream restoration resets disturbed, channelized streams to a theoretical pre-disturbance state (“stage zero”). It is assumed that this valley-scale restoration/disturbance will restore natural abiotic and biotic processes, leading to greater primary and secondary biological productivity, maximizing potential ecosystem services such as the abundance of desirable fish species. As stage 0 restoration projects have been implemented in Oregon and across North America, post-restoration studies have not fully assessed this assumption. In this study, I seasonally sampled aquatic macroinvertebrate communities and fish diets on the South Fork McKenzie River, OR in a reach that underwent stage 0 restoration in 2018, as well as two upstream, unrestored control reaches. I estimated total annual secondary macroinvertebrate production on the benthos and submerged wood surfaces, and constructed food webs from the dominant taxa found in fish diets. Contrary to expectations, annual production estimates were ~5-times lower on a per-meter-squared basis in the restored reach than in upstream unrestored reaches. However, because there was ~4.5-times greater wetted area available in the restored reach, overall macroinvertebrate production per-unit of valley length was 1.5-times higher than in unrestored reaches. Fish diet assemblages were also more complex in the treatment reach than in the control reaches. Additionally, a greater diversity of macroinvertebrate community assemblages was observed in the restored reach, suggesting that stage 0 restoration may produce a heterogeneous mosaic of fine-scale habitat patches and associated metapopulations. These findings suggest that stage 0 restoration may increase overall macroinvertebrate productivity, as well as creating a more diverse assembly of prey items, resulting in more consistent prey availability and greater overall habitat and foraging opportunities for fishes
The physiological response of larval Pacific lamprey to chronic heat stress
Get PDFPacific lamprey is an important cultural and ecological species to freshwater ecosystems of the Pacific Northwest. Lamprey often rear in low gradient portions of watersheds that have high exposure to climate warming, yet very little is known about their thermal physiology in comparison with other anadromous fishes such as Pacific salmon. Our goal was to characterize the response of larval Pacific lamprey to chronic
heat stress to learn how changing stream temperatures could affect this life stage. Lamprey exposed in the laboratory to temperatures reflective of current summer water temperatures in the Willamette River, OR (20-25°C) did not suffer increased mortality. These animals did not feed substantially in captivity, inadvertently adding a starvation stressor to the experiment. Lamprey held at 22.5-25°C had standard
metabolic rates approximately four times that of lamprey held at 13-25°C, which was associated with greater loss in both body mass and length. Additionally, the results of a differential gene expression (DE) analysis and functional enrichment analysis indicate pathways involved with starvation made up a significant proportion of the deferentially expressed genes at elevated temperatures. These results suggest that larval lamprey are able to resist multiple stressors for extended periods of time but likely at the cost of long term fitness and survival
Explanations and Processes to Enable Humans to Assess AI with Respect to Manipulable Properties
Get PDFAssessing AI systems is difficult. Humans rely on AI systems in increasing ways, both visible and invisible, meaning a variety of stakeholders need a variety of assessment tools (e.g., a professional auditor, a developer, and an end user all have different needs). We posit that it is possible to provide explanations and assessment processes that enable AI non-experts observing multiple intelligent agents in sequential domains to differentiate the agents with respect to a property (e.g., quality or fairness), as well as articulate justification for their differentiation. Further, we hypothesize that if the property can be manipulated in a highly controllable fashion, then it is possible to measure the quality of an explanation and/or assessment process by its ability to expose that such manipulation has occurred. This dissertation presents our contributions in explanations, processes, and manipulations for assessment. Specifically, we present our investigations into explanations to judge fairness of a classifier, the After-Action Review for AI process to structure explanation consumption, the Ranking task for explanation evaluation, and the Mutant Agent Generation approach for introducing controllable variation. By improving explainability of AI in all these phases, we seek to empower assessors to calibrate trust in the system appropriately
Functional Characterization and Classification of Genes Essential to Flower Induction, Flower Development, and Seed Development in Populus and Eucalyptus
Get PDFThis dissertation consists of four studies of Populus and Eucalyptus biotechnology and genomic science: 1) induction of floral sterility by tapetal expression of the ribonuclease Barnase in Populus; 2) CRISPR Cas9-mediated gene editing targeting LEAFY (LFY) and AGAMOUS (AG) homologs in Populus; 3) induction of floral sterility by CRISPR Cas9 mutagenesis of the LEAFY (LFY) gene homolog in hybrid Eucalyptus; and 4) Gene expression analysis using RNASeq during flowering and seed capsule development in Eucalyptus grandis (E. grandis).
The Populus genus includes species and hybrids that are favored in commercial and research settings because of their fast growth and their relative ease of transformation and regeneration. The Eucalyptus genus is the most planted genus of hardwood trees in the world. Eucalyptus species and hybrids are grown for wood, pulp, essential oils, and honey. Regardless of their value, the genes and genomes of trees are not as well-studied as those of other plant and crop species, including Arabidopsis, Antirrhinum, maize, and tobacco. We conducted four studies to address research needs associated with tree floral biology and genetic containment.
In study 1, we performed a four-year field trial of transgenic male poplars that expressed the ribonuclease Barnase in the tapetal layer of their anthers. The purpose was to test the efficiency of this RNAse at disrupting pollen development and determine whether growth was affected. During the trial, 17 of 18 transgenic barnase-expressing trees grew on average 40% slower than the WT control trees (i.e., no transformation). The 18 Barnase-expressing trees did not have detectable production of viable pollen
In study 2, we evaluated the mutation efficiency and mutation spectra induced by four CRISPR Cas9 nucleases targeting two different sites in three essential flowering genes, LFY and the two AG homologs in Populus. The average mutation rate was 77.5%; a higher mutation rate than observed before the advent of CRISPR. No undesirable mutations were seen in 310 potential “off-target” loci, and no mutations were seen at any of the target sites in the empty-vector (“Cas9-only” plus markers) control population.
In study 3, we analyzed the mutation efficiency and efficacy of CRISPR Cas9 nucleases at inducing knockout mutations in the LFY ortholog in Eucalyptus. In 68 transgenic lines, the average mutation rate was 98.5%. After evaluating the floral morphology of 32 lines in the greenhouse, we calculated the average loss-of-function (LOF) rate to be 91%. Lines with LOF mutations failed to produce flowers and viable gametes. Meanwhile, the LOF mutations did not affect growth. The expression of genes upstream and downstream of LFY in the floral development pathway suggest that the mutant flowers were not transitioning adequately between inflorescences and flowers. However, occasional sterile and underdeveloped floral organs were seen. Further long-term research is necessary to determine whether mutation of LFY is a fully reliable containment technology.
In study 4, we examined the gene expression of 20 samples corresponding to seven different floral and vegetative tissues during late flowering and early seed capsule development in E. grandis. Expression libraries were created for flowers and seed capsules at five time points between anthesis and early seed development. Libraries were also constructed for mature pollen and mature leaf (i.e., the vegetative control). We identified differentially expressed genes by comparing the expression of all reproductive tissues to mature flower and also by comparing expression among reproductive tissues. In total we identified 27,450 unique transcripts, and identified 11,438 differentially expressed transcripts (false discovery rate of 0.05, filtered to genes with at least double the expression if positive change, or half the expression if negative change). We found that genes involved in the biosynthesis of phenylpropanoids were important and differentially expressed during anther and seed capsule maturation. Flower development genes were expressed in tissues homologous to those of other flowers previously characterized, e.g. Arabidopsis and Anthirihum. The transcriptome data provides a rich resource to support studies of floral evolution in the Myrtales, and will inform efforts to breed or genetically engineer sexual development in Eucalyptus