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Zhang, HuaijianBoundary Integral Techniques in Three Dimensions for Deep Water Waves
Doctor of Philosophy, The Ohio State University, 2011, Mathematics

The motion of deep water waves is a long-existing problem in fluid dynamics. Because it has many applications in academics and industries, numerous scientists have done much research to tackle this problem. The evolution of deep water wave is governed by Euler equations. Because of its nonlinearity, there are few available analytical expressions to fully describe the evolution of the deep water waves. Thus efficient numerical approximation becomes very critical to understand the properties of water wave motion.

An improved boundary integral technique is presented in this thesis to simulate the motion of deep water waves. One difficulty is the singularity in the Green’s function. Two methods to treat this singularity are discussed. One is blob regularization with third-order accuracy, and the other is based on polar coordinates with spectral accuracy. In the blob regularization, we replace the Green’s function by a regularized smooth Green’s function, which provides a good approximation to the original integral. For the other approach, integral identities are applied to reduce the strength of the singularity and then a polar coordinate transformation is applied to obtain a nonsingular integrand. The results from these two methods will be examined.

Another challenge is that the integrands are integrated over an infinite surface. For a doubly periodic water wave, we have to sum the images of Green’s function over the free-surface of the water. Ewald summation technique is used to expedite the calculation. Three-dimensional interpolation technique is suggested to reduce the time spent even further.

The numerical method is tested with several examples and then applied to the motion of a perturbed Stokes wave. The perturbation grows until the resolution fails.

Committee:

Gregory Baker, Dr. (Advisor); Chiu-Yen Kao, Dr. (Committee Member); Ed Overman, Dr. (Committee Member)

Subjects:

Applied Mathematics; Fluid Dynamics; Mathematics

Keywords:

Three Dimensions Deep Water Wave; Singularity; Blob Regularization; Exponetially Accurate Method; Polar Coordinate Transformation; Third-Order Accurate Method; Ewald Summation; Green's function; Simulation of Perturbed Stokes Wave

AYYALASOMAYAJULA, HARITHAHIGHER-ORDER ACCURATE SOLUTION FOR FLOW THROUGH A TURBINE LINEAR CASCADE
MS, University of Cincinnati, 2003, Engineering : Mechanical Engineering
Low-pressure turbines (LPT) in aircraft engines undergo tremendous losses at cruise conditions. The flow Reynolds number at cruise is lower than the take-off Reynolds number by a factor of almost two. At low Reynolds numbers, the flow is largely laminar, and tends to separate easily on the suction surface of the turbine blade when an adverse pressure gradient is encountered. Therefore, accurate prediction of flow separation is crucial for an effective design of LPT blade; and is achieved in the present work using a high-order accurate numerical solution procedure. The three-dimensional, unsteady, full Navier-Stokes equations are solved to analyze the flow. A MPI-based higher-order, parallel, chimera version of the FDL3DI flow solver, is extended for use with this turbomachinery application. A sixth-order accurate compact-difference scheme is used for the spatial discretization, along with second-order accurate temporal discretization. Tenth-order filtering is used to minimize the numerical oscillations in the flow solution and maintain numerical stability. The objective of the present study is to show the ability of higher-order accurate compact-difference scheme to predict the flow separation that occurs inside an LPT cascade at Re C = 25,000 (based on axial chord and inlet velocity). A new set of subsonic inflow/outflow boundary conditions that account for upstream influence (BC2) are derived by specifying stagnation quantities at the inlet, and a static quantity at the exit of the flow domain, and maintaining the inflow angle constant. For inflow/outflow boundary conditions that do not account for upstream influence, fixed inflow with extrapolated outflow (BC1) has been utilized. The effect of the two different sets of inflow/outflow boundary conditions on the flow solution is studied, for second-order, fourth-order and sixth-order accurate schemes. The computed Cp distribution for the LPT flow shows good agreement with the existing experimental data. The location of the onset of separation matches with an available LES simulation result and with the available experimental data. The performance of high-order compact difference schemes has been assessed via simulation of laminar flow over a circular cylinder at Re D = 250 (based on free-stream velocity and cylinder diameter). The sixth-order accurate compact difference scheme with tenth-order filtering on a coarser mesh preserves the vortex structure better than possible with the second-order accurate scheme on a finer mesh. This demonstrates the efficiency of the higher-order accurate compact difference scheme.

Committee:

Dr. Urmila Ghia (Advisor)

Subjects:

Engineering, Mechanical

Keywords:

low-pressure turbine; high-order accurate method; filtering; flow separation; Navier-stokes equations

Clarke, Laura ShippUse of Picture Response Cards in the General Education Classroom to Increase Participation of Students with Mild Mental Disabilities
EdD, University of Cincinnati, 2010, Education : Special Education
The passage of IDEA and No Child Left Behind have highlighted the importance of all students having access to the general curriculum, and to learning in the least restrictive environment. Prior to IDEA and No Child Left Behind, students with intellectual disabilities were often excluded from instruction in the general education classroom, and were provided separate instruction. Research-based strategies are needed to support education of students with intellectual disabilities in the general education classroom. This study used an ABAB design to investigate the effects of using response cards to increase student participation, accuracy and test performance in the general education classroom. Results of this study suggest that response cards are an effective instructional strategy to increase in on-task behavior, accurate responding, and test scores for students with intellectual disabilities in the general education classroom. Study demonstrated a high degree of social validity for teachers and students. Results from this study extend earlier research in which authors found that response cards increase the participation of students with intellectual disabilities in the resource setting.

Committee:

Anne Bauer, EdD (Committee Chair); Stephen Kroeger, EdD (Committee Member); Todd Haydon, PhD (Committee Member); David Barnett, PhD (Committee Member)

Subjects:

Special Education

Keywords:

intellectual disabilities;response cards;accurate responding;on-task behavior;instructional strategy

Zhang, HanRepresentations of Chinese Culture and History in Picture Books of the Westerville Public Library: Educational Quality And Accuracy Of Children Literature About China And Chinese Culture
MAE, Otterbein University, 2011, Education
In order to learn about the educational quality and accuracy of most children's picture literature accessible to readers of Westerville area, which aim to illustrate and introduce the content of Chinese culture and history, the author of this paper examines whether children's picture books in the Westerville Public Library serve American readers as authentic and accurate representations of Chinese culture and its history. Based on the ardent debates of former researcher, the author discusses frequent mistakes existing in most picture books. Later, the author collects data and uses estimation and hypothesis testing to prove the error rate of the whole pictures population and the hypothesis of comparing quality of books of past and present.

Committee:

Susan Constable (Advisor); Daniel Cho (Committee Member); Kristin Reninger (Committee Member)

Subjects:

Asian American Studies; Asian Literature; Asian Studies; Cultural Anthropology; Education; Ethnic Studies; History; Literature

Keywords:

Chinese Culture and History; children's picture literature; Picture Books; Westerville Public Library; Educational Quality And Accuracy;authentic and accurate representations;

Fonseca, James ErnestAccurate treatment of interface roughness in nanoscale double-gate metal oxide semiconductor field effect transistors using non-equilibrium green's functions
Master of Science (MS), Ohio University, 2004, Electrical Engineering & Computer Science (Engineering and Technology)

In the sub-50nm scale, the aggressive scaling of MOSFETs is expected to culminate in dual-gate (DG) architectures on SOI substrates. DG MOSFETs are widely accepted to be the ultimate design that silicon can deliver in terms of on and off currents. So far, the design efforts on these novel structures have concentrated on ideal geometries and doping profiles. However, at nanometer scale, devices fabricated with lithography and etching techniques cannot deliver perfect reproductions of the ideal design and suffer significantly from fluctuation effects associated with random doping and interfaces. While the former is less important in undoped, thin-body architecture, the interface roughness is a crucial factor in DGMOSFET performance, as indicated by the International Technology Roadmap for Semiconductors [1].

This work investigates, qualitatively and quantitatively, the effects of interface roughness of device operation of DGMOSFETs. Statistical ensembles of devices are simulated to examine device characteristic variations owing to the random element of interface roughness. The effect of roughness parameter changes on device operation is also investigated. Three transport models, namely drift-diffusion, quantum ballistic and non-equilibrium Green's function, are compared. Both device electrostatics and carrier transport are affected by interface roughness, and quantum mechanical tunneling plays a significant role in the latter.

Committee:

Savaş Kaya (Advisor)

Keywords:

Accurate Treatment; Interface Roughness; Nanoscale Double-Gate Metal Oxide; Semiconductor Field; Effect Transistors; Non-Equilibrium Green's Functions

Chen, LinMEASUREMENTS OF AUTOCORRELATION FUNCTIONS USING A COMBINATION OF INTRA- AND INTER-PULSES
Master of Science, Miami University, 2015, Computational Science and Engineering
Incoherent scatter radar (ISR) is a versatile tool to study the ionosphere by measuring the autocorrelation function (ACF). Accurate ACF in the E-region is difficult to obtain because the relative short range limits the length of a pulse. The short correlation time of the ionosphere renders the correlation using the pulse-to-pulse technique useless. In the thesis, we study a method that combines intra-pulse and inter-pulse techniques and apply it to the data taken at Arecibo Observatory. We show simultaneously measured ACF’s at short and long lags and summarize the merits of ACF. Applications of ACF and its advantages are discussed. The technique used here will make the derivation of ionosphere parameters more accurate.

Committee:

Qihou Zhou (Advisor); Chi-Hao Cheng (Committee Member); Dmitriy Garmatyuk (Committee Member)

Subjects:

Aeronomy; Aerospace Engineering; Computer Engineering; Computer Science; Earth; Radiology

Keywords:

Incoherent scatter radar; ionosphere; E-region; parameters; autocorrelation function; accurate

Stubbs, Elizabeth ChristineEmotional Intelligence Competencies in the Team and Team Leader: a Multi-level Examination of the Impact of Emotional Intelligence on Group Performance
Doctor of Philosophy, Case Western Reserve University, 2005, Organizational Behavior
This research examines the relationship between team leader emotional intelligence competencies, team level emotional intelligence, and team performance. It is argued here that team leader’s emotional intelligence (EI) will influence the development of group level emotional intelligence, which was measured by a teams emotionally competent group norms (ECGN). Secondly, it is hypothesized that the presence of ECGNs will positively influence group effectiveness. Data were collected from 422 respondents representing 81 teams in a military organization. Results show that team leader emotional intelligence is significantly related to the presence of emotionally competent group norms on the teams they lead, and that emotionally competent group norms are related to team performance. This research contributes to the field by offering support for the affects team leaders emotional intelligence has on the teams they lead as well as by showing team level emotional intelligence affects team performance. Propositions for future research and practice are offered.

Committee:

Richard Boyatzis (Advisor)

Keywords:

Emotional Intelligence; Emotional Competencies; Emotionally Competent Group Norms; Team; Team Performance; Team Effectiveness; Leader Behavior; Team emotional intelligence; Emotional self-awareness; Accurate self-assessment; Self-Confidence