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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
441

Pro-Drop and Word-Order Variation in Brazilian Portuguese: A Corpus Study

Smith, Stewart Daniel 03 July 2013 (has links) (PDF)
The present study examines certain syntactic properties of the Brazilian variety of Portuguese (BP): 1) BP is a pro-drop language with instances of both null subjects and covert objects, and 2) BP exhibits several possible word orders. To determine the frequency of pro-drop and word-order variations, the CDP (The Portuguese Corpus) was used to provide samples of transitive, main clauses, which were then categorized based on whether or not they had null subjects and covert objects. The clauses were also categorized according to word order. In addition to providing samples, the corpus allowed for the comparison of four different registers of BP: academic, newspaper, fiction, and oral. The results of the present study demonstrated that null subjects are much more common than covert objects (29.4% and 2.3% respectively) and that register did significantly affect the frequency of pro-drop, with oral having the highest rate of pro-drop and newspaper the lowest. For word order, SVO was most common at 95.1% with the occurrences of other variations being too rare to reliably determine statistical significance. Different from pro-drop, register did not affect the frequency of different word orders. Word-order variations were not random, however, but were determined by topic and focus with old information (topic) generally occurring preverbally, and new information (focus) generally occurring in the most embedded position. The fact that this study effectively examined these syntactic features is significant, as most of the Portuguese syntactic research previous to the present study was specific to European Portuguese. The present study demonstrated a new methodology being successfully applied to a different dialect, but more than that, it demonstrated that a more empirical, data-driven approach to syntactic research is both possible and valuable, justifying the creation and use of large corpora for this type of research.
442

Towards omnimaterial printing : Expanding the material palette of acoustophoretic printing

Kjellman, Jacob January 2019 (has links)
Dropp-genereringstekniker är viktiga för industrier som läkemedelsindustrin, livsmedelsindustrin, kosmetikindustrin etc. Traditionella droppgenereringstekniker är dock begränsade i mängden av material som kan processas till droppform. Ett exempel inkjet som är en väletablerad teknik för att generera droppar med hög hastighet (1-10 kHz) och precision (10-20 μm), men kan bara stöta ut vätskor med låga viskositet, ungefär 10-100 gånger viskositeten av vattnet. Akustophoretisk utskrift motiv är att övervinna denna materialbegränsning och har framgångsrikt avkopplat dropputstötning från bläckviskositet. Metoden utnyttjar ickelinjära akustiska krafter för att skriva ut en stor mängd av material med hög kontroll, med viskositet som sträcker sig över fyra storleksordningar (0,5 mPa · s till 25 000 mPa · s). Emellertid är utstötningen baserad på bildandet av en hängande droppe, och i den aktuella prototypen begränsas materialpaletten av akustophoretisk utskrift genom sprider sig över munstycket, vilket begränsar den minsta tillåtnas ytspänningen till ungefär 60 mN / m. I detta arbete införs en munstycksbeläggningsteknik för att expandera mängden av utskrivbara material, med tillåtna ytspänningar så låga som 25 mN / m. Genom att utnyttja generera nanostrukturer med låg ytenergi på munstyckspetsen, tillverkas superavstötande beläggning. Grunden för nanostrukturerna genererades med hjälp av sot från ett paraffin-vaxljus. Ett robust tillverkningsprotokoll har etablerats, och beläggningen fysikaliska egenskaper och prestanda har karaktäriserats. Tre nya tillämpningsområden undersöktes, vilket demonstrerade noviteten hos denna nya metod. Detta arbete banar vägen för en ny uppsättning material som ska behandlas i en droppe-per droppe metodik. / Droplet generation techniques are essential for industries such as the pharmaceutical, food industry, cosmetic industry, etc. However, traditional droplet generation techniques are limited in the palette of materials that can processed in a droplet form. For example, inkjet which is a well-established technology to generate droplets of high speed (1-10 kHz) and precision (10-20 μm), but can only eject fluids with low viscosities, roughly 10-100 folds the one of water. Acoustophoretic printing aims to overcome this material limitation and have successfully decoupled droplet ejection from ink viscosity. The method harnesses nonlinear acoustic forces to print a wide range of materials on demand, spanning over four orders of magnitudes (0.5 mPa·sto 25,000 mPa·s). However, the ejection is based on the formation of a pendant drop, and in the current prototype, the material palette of acoustophoretic printing is limited by nozzle wetting, limiting the allowable minimum surface tension to about 60 mN/m. In this work, a nozzle coating technique is introduced in order to expand the material window by processing fluid with a surface tension as low as 25 mN/m. By leveraging self-assembling of nanostructures on the nozzle tip, superamphiphobic coating is successfully manufactured by using a candle soot template.A robust manufacturing protocol has been established, and the coating characterized in its physics and performance.
443

Pressure Losses Experienced By Liquid Flow Through Pdms Microchannels With Abrupt Area Changes

Wehking, Jonathan 01 January 2008 (has links)
Given the surmounting disagreement amongst researchers in the area of liquid flow behavior at the microscale for the past thirty years, this work presents a fundamental approach to analyzing the pressure losses experienced by the laminar flow of water (Re = 7 to Re = 130) through both rectangular straight duct microchannels (of widths ranging from 50 to 130 micrometers), and microchannels with sudden expansions and contractions (with area ratios ranging from 0.4 to 1.0) all with a constant depth of 104 micrometers. The simplified Bernoulli equations for uniform, steady, incompressible, internal duct flow were used to compare flow through these microchannels to macroscale theory predictions for pressure drop. One major advantage of the channel design (and subsequent experimental set-up) was that pressure measurements could be taken locally, directly before and after the test section of interest, instead of globally which requires extensive corrections to the pressure measurements before an accurate result can be obtained. Bernoulli's equation adjusted for major head loses (using Darcy friction factors) and minor head losses (using appropriate K values) was found to predict the flow behavior within the calculated theoretical uncertainty (~12%) for all 150+ microchannels tested, except for sizes that pushed the aspect ratio limits of the manufacturing process capabilities (microchannels fabricated via soft lithography using PDMS). The analysis produced conclusive evidence that liquid flow through microchannels at these relative channel sizes and Reynolds numbers follow macroscale predictions without experiencing any of the reported anomalies expressed in other microfluidics research. This work also perfected the delicate technique required to pierce through the PDMS material and into the microchannel inlets, exit and pressure ports without damaging the microchannel. Finally, two verified explanations for why prior researchers have obtained poor agreement between macroscale theory predictions and tests at the microscale were due to the presence of bubbles in the microchannel test section (producing higher than expected pressure drops), and the occurrence of localized separation between the PDMS slabs and thus, the microchannel itself (producing lower than expected pressure drops).
444

Biomechanical Study of Jumping & Landing Techniques: Ballet vs Non-ballet Athletes

Tornio, Ashley 01 December 2019 (has links) (PDF)
INTRODUCTION: The prevalence of ACL injuries is increasing in previous years. One of the most common studied kinematic risk factors related to ACL injuries is a resultant weak, leg axis alignment known as the dynamic knee valgus angle presented during a vertical drop jump [8, 14, 15]. Hewett et. al. concluded that a knee valgus angle was a primary predictor of the mechanism that leads to an ACL rupture [8]. By increasing the excessive knee valgus angle during a two-legged DVJ, an athlete is in turn increasing the possibility of a high knee valgus moment, which can increase the anterior tibial translation as well as the load on the ACL several-fold and the chances for an ACL tear [4]. METHODS: In our study, ten collegiate female participants, including ballet and non-ballet athletes performed two-legged DVJs for 6 different flexor and extensor muscles while digital recordings of knee valgus angle were captured at initial contact and push off with simultaneous collection of EMG data. RESULTS: Results displayed statistical significance for the average valgus angle to estimated GRF ratio for the non-dominant leg at push-off between the ballet and non-ballet athletes (0.8 ± 0.43 vs. 1.8 ± 0.33 degrees/N, p < 0.05). In addition, we also found that the hip extensor activity significantly increased for the non-ballet group and that the lateral thigh CCI noticeably increased for the non-dominant leg for the non-ballet group, which could be indicative of the noticeable difference in the biceps femoris muscle activation for the non-ballet group when comparing sports type. In addition, statistically significant interactions between sports type and leg type for vastus medialis and gluteus maximus were produced. Observed results also indicated that there was an increase in overall variability for the dominant leg of the non-ballet athletes amongst all studied muscles and for the non-dominant leg for the ballet group specifically studying the gluteus maximus muscle activity. DISCUSSION: Relatively, the non-ballet group could be at a higher risk for increase in femoral adduction, hip adduction, and tibial external rotation, and overall predict a larger knee valgus moment; therefore, the non-ballet group could potentially be at a higher risk for an ACL injury than the ballet group. In addition, there is potential in continued research of neuromuscular differences between ballet and non-ballet athletes to further investigate the vastus medialis and the gluteus maximus muscle activations as well as to investigate the knee valgus moment values.
445

The Effect of Drop Size Distribution, Feed Concentration, and Volume Split on the Separation of Two Immiscible Liquids in a Hydrocyclone.

Burrill, Kenneth A. 05 1900 (has links)
<p> The separation of a mixture of carbon tetrachloride in water was studied in a 2 inch diameter glass hydrocyclone. First, the effect of a mixing valve and of oil/water ratio on the volume/surface diameter of the dispersion in the feed to the hydrocyclone was studied using a statistical experiment design. Secondly, the effect of feed drop size distribution, oil/water ratio, and overflow/underflow split on the separation in the hydrocyclone was determined, again using a statistical experiment design. In both designs, five levels of each variable were studied. Flow rate, design shape, and temperature were kept constant. The range of variables was: </p> <p> 1. Mixing Value Pressure Drop 17.95 to 88.25 mm. Hg </p> <p> 2. Oil/Water Ratio 0.132 to 0.211 </p> <p> 3. Overflow/Underflow Split 4/1 to 8/1 </p> <p> From the first part of the work it was found that oil/water ratio had no significant effect on the volume/surface diameter, and that there was a linear relationship between the volume/surface diameter and mixing valve pressure drop. </p> <p> From the second part of the work it was found that volume split had most significant effect on hydrocyclone separation for the range of variables studied. The oil/water ratio had the next most significant effect on separation, and finally, drop size distribution was also found to be significant, but was the least important of the three variables. The interactions of the variables were no significant. The hydrocyclone separation could be predicted. The prediction of the overflow drop-size distribution agreed very well with the distribution observed photographically. Both predictions required assumptions that short-circuit flow and drop-drop coalescence was negligible. </p> / Thesis / Master of Engineering (ME)
446

The Transient Behavior of an Ethane Dehydrogenation Furnace

Li, Mou-Ching 09 1900 (has links)
This report deals with the mathematical model of the transient behaviour of an existing ethane dehydrogenation furnace which is composed of two main sections: a preheating convection section and a radiant-heated section. The correlation of pressure drop with time has been found from the available data. The fractional carbon deposition and the multiplier coefficient of a pressure drop equation have been determined by the direct search optimization technique of Hooke and Jeeves. An optimal policy for the cyclic operation of the furnace was determined by considering plant temperature profile and hydrocarbon/ steam ration as parameters for maximizing average ethylene produced per day. The effect of temperature profile on the distribution of carbon deposited along the reactor was also predicted and discussed. / Thesis / Master of Engineering (ME)
447

The Impact and Rebound of a Small Water Drop Striking a Hot Surface

Harvey, Denis 03 1900 (has links)
<p> Water drops at their boiling point were projected through a steam atmosphere to strike a surface which was varied in temperature from 300 to 900 degrees Fahrenheit. A high-speed motion picture study of the collision process showed that, except at low surface temperatures, the drop flattened out on impact and rebounded in a state of oscillation. Measurements of the change in drop diameter on collision indicated that the amount of evaporation due to heat transfer from the surface was extremely small except when the drop extensively wetted the surface. Solution of a mathematical model of the initial impact dynamics and models of heat transfer through a vapour film beneath the drop and by direct liquid-surface contact confirmed experimental observations. </p> / Thesis / Doctor of Philosophy (PhD)
448

Diagnostic Accuracy of Pressure-Drop Coefficient (CDP) for Functional Assessment of Coronary Artery Disease using Multicenter International ILIAS Registry Data

Manegaonkar, Shreyash 31 May 2023 (has links)
No description available.
449

Psychological Factors That Impact the Drop-Out Rate in Adolescent Sports

McClone, Nicole S. 01 December 2015 (has links)
Children are dropping out of sport at alarming rates. With the highest numbers of dropout occurring between the ages of ten and seventeen, the focus of this research is on the drop-out rates of adolescents from sport. Athletic participation has been linked to positive academic performance, key development of leadership skills, and increased engagement in the community. The research that has been conducted related to sport persistence has had a greater focus on examining factors related to the physical domain. Attention is now beginning to shift however, and researchers are looking outside the physical domain and analyzing sport attrition more through sociological and psychological domains. The purpose of this research is to conduct a literary analysis on the psychological factors that impact the drop-out rate of adolescents from sport with adolescents being defined as children between the ages of ten and seventeen. Research in this domain is fairly limited; however numerous psychological theories have recently emerged as framework for conducting research as it relates to participation and drop-out in adolescent sports. These include self-determination theory, basic needs theory, achievement goal theory, and leisure constraints theory. The developmental model of sport participation is also a tool that is widely used to study sport persistence and drop-out. Foundationally based on psychology, this literature analysis was constructed to explore drop-out factors related to adolescent sport with the intent to collect data that either supports or disputes the relational connections between sport attrition or persistence. These relationships include but are not limited to the athlete/athlete, athlete/coach, athlete/parent, and athlete/self.
450

A case study examining teachers' beliefs toward in-grade retention in a K-2 school

Smith, Charles Edward 13 December 2008 (has links)
The purpose of this mixed-methods case study was to examine teachers’ beliefs toward in-grade retention in a K-2 school. This study focused on how teachers acquire beliefs regarding grade retention, and their knowledge of research regarding the effectiveness of retention. Witmer, Hoffman and Nottis (2004) contend that teacher beliefs toward grade retention may not be based on research, but on peer influence, past practice, or administrative policy. Quantitative and qualitative data were collected to examine teacher beliefs in a K- 2 school. Quantitative data were collected through the Teacher Opinion Survey (TOS) and Personal Experiences and Retention Practices (PERP). A total of ten K-2 teachers volunteered to complete the survey instruments. Additionally, six K-2 teachers and the school principal were interviewed to collect qualitative data. Data were analyzed to triangulate the findings. This study concluded that teachers continue to retain students as a remedy for academic failure, contrary to what some researchers like Shepard and Smith (1989), who decried that schools were continuing the practice of retention despite research findings that indicated little or no academic achievement is gained though retention. Findings further indicated that teachers disagreed that retention failed to improve achievement, failed to inspire students to buckle down and behave better, and failed to develop students’ social adjustment and self-concept.

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