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Benedik, ChristopherModeling and Minimization of Integrated Circuit Packaging Parasitics at Radio Frequencies
Doctor of Philosophy (PhD), Wright State University, 2013, Engineering PhD
Many integrated circuits are connected to their packaging pins through bondwires. Due to the low cost of bondwires, there is interest in extending operating frequencies or negating their effects in order to keep the price of packaged integrated circuits as low as possible. Bondwires function as lumped circuits consisting of inductors, capacitors, and resistors which can be modeled based on wire geometry. Knowing this, models can be created which approximate the effects of bondwires. With the knowledge of these models, compensation techniques can be implemented which will match the bondwire impedance to the signal line impedance. The effects of these elements on circuit operation is apparent on both signal and power lines to devices. This dissertation is going to present 1. A bondwire model based on physical characteristics of interconnections including neighboring wires. The model is tested against data from fabricated test fixtures, and results compared to those produced by current software. 2. A compensation method for performance degradation caused by bondwires at radio frequencies. Test fixtures implementing these methods are fabricated and checked with results compared to predictions. 3. A method of component stacking which can be used to attach passive components directly to IC die. -Use of above method to improve power distribution network (PDN) performance. Theoretical results are compared to measured test fixture results. -Use of above method to improve performance of off device filters through Q-factor improvement. Improvement verified through test and analysis of a physical test fixture.

Committee:

Saiyu Ren, Ph.D. (Advisor); Raymond Siferd, Ph.D. (Committee Member); Marty Emmert, Ph.D. (Committee Member); Marian Kazimierczuk, Ph.D. (Committee Member); Ronald Coutu, Ph.D. (Committee Member)

Subjects:

Electrical Engineering; Engineering

Keywords:

integrated circuit packaging; bondwire; power distribution network; scattering parameters; transmission line; transmission parameters; passive circuit modeling; radio frequency circuit modeling; impedance measurement; power supply decoupling

Goswami, IshanInfluence of geometric and flow variations on coronary diagnostic parameters: An in-vitro study
MS, University of Cincinnati, 2013, Engineering and Applied Science: Mechanical Engineering
In current practice, diagnostic parameters, such as fractional flow reserve (FFR) and coronary flow reserve (CFR), are used to determine the severity of a coronary artery stenosis. These parameters are evaluated from pressure and/or flow information, using sensor-tipped guidewire advanced into an artery at maximal vasodilation (hyperemia) condition. FFR is defined as the ratio of hyperemic pressures distal and proximal to a stenosis. CFR is the ratio of flow at hyperemic and basal (resting) condition. In addition to these, new diagnostic parameters have been suggested to overcome the shortcomings of the conventional parameters. Three such parameters assessed in this study are pressure drop coefficient (CDP), lesion flow coefficient (LFC), and stenotic resistance index (Rs). CDP is defined as the ratio of the pressure drop across the stenosis to the upstream dynamic pressure. LFC is the ratio of pressure drop coefficient at high Reynolds number to the pressure drop coefficient based on pressure drop across stenosis and throat dynamic pressure. The Rs is assessed by taking the ratio of hyperemic pressure drop to flow rate. These parameters may be influenced by variations in geometric and flow conditions. This study investigated whether the newly developed parameters had an advantage in areas where FFR failed to diagnose stenosis severity. Four major issues were addressed. Firstly, the influence of native arterial diameter was investigated, followed by an assessment with variation in vasculature status. The latter is an important comparison, since it is a topic of current debate, and this analysis adds to the pool of data currently available. The impact of a newly designed guidewire on the diagnostic parameters was also tested. Another important aspect of this study was to present a proof-of-concept analysis for basal based parameters. In-vitro experiment coupled with pressure-flow relationships from human clinical data was used to simulate pathophysiologic conditions in two representative arterial diameters, 2.5 mm (N1) and 3 mm (N2). With a 0.014' and newly designed 0.022' guidewire inserted separately, diagnostic parameters were evaluated for mild (~ 64% area stenosis (AS)), intermediate (~80% AS), and severe (~ 90%AS) stenosis for both N1 and N2 arteries, and between two conditions: with and without myocardial infarction (MI). From the obtained experimental data, diagnostic parameters were assessed at basal condition of 42 ml/min and 50 ml/min, for N1 and N2 respectively. Arterial and guidewire diameter did not influence FFR for clinically relevant cases of mild and intermediate stenosis (difference< 5%). Newer parameters varied considerably, but had distinctive increasing trend, which allowed stenosis delineation. However, FFR was overestimated (mild: ~9%, intermediate: ~20%, severe: ~30%) for MI. Overestimation of FFR may affect clinical decision making. CDP had variation with vascular condition (mild: ~35%, intermediate: ~14%, severe: ~9%). The value of Rs also showed similar variation (mild: ~30%, intermediate: ~25%, severe: ~14%). LFC varied somewhat (<8%) for intermediate and severe stenosis. All parameters delineated stenosis in presence of MI, overcoming the disadvantage of FFR. Of the three new parameters, CDP's wide range allowed better delineation of stenosis severities irrespective of hyperemic or basal conditions.

Committee:

Rupak Banerjee, Ph.D. P.E. (Committee Chair); Hongdao Huang, Ph.D. (Committee Member); Sundaram Murali Meenakshi, Ph.D. (Committee Member)

Subjects:

Mechanics

Keywords:

Stenosis;Coronary diagnostic parameters;Native arterial diameter;Myocardial infarction;Basal based parameters;Pressure drop coefficient;

Babu, SaileshA material based approach to creating wear resistant surfaces for hot forging
Doctor of Philosophy, The Ohio State University, 2004, Industrial and Systems Engineering

Tools and dies used in metal forming are characterized by extremely high temperatures at the interface, high local pressures and large metal to metal sliding. These harsh conditions result in accelerated wear of tooling. This phenomenon becomes a serious issue when parts forged at complex and are expected to meet tight tolerances.

The objective of this dissertation is to develop a computer-based methodology for analyzing the requirements hot forging tooling to resist wear and plastic deformation and to create wear resistant surfaces to overcome these failure mode, to increase hot forging tool life.

The approach proposed and tested in the dissertation involves development of a FEM based approach to model material degradation caused by heat, load and sliding. This approach uses tempering parameters proposed by Holloman and Jaffe and published thermal softening behavior of tool steels to predict the drop in hardness of tool steels during service. Using a modified Archard’s model for wear that takes into account effect of temperature on hardness, this drop in hardness is then used to more accurately predict wear in hot forging tools, that are dominated by thermal softening.

Dissertation outlines development of a new cyclic contact test design to recreate intermittent tempering seen in hot forging. This test has been used to validate the use of tempering parameters in modeling of in-service softening of tool steel surfaces. The dissertation also outlines an industrial case study, conducted at a forging company, to validate the wear model. This dissertation also outlines efforts at Ohio State University, to deposit Nickel Aluminide on AISI H13 substrate, using Laser Engineered Net Shaping (LENS). Dissertation reports results from an array of experiments conducted using LENS 750 machine, at various power levels, table speeds and hatch spacing. Results pertaining to bond quality, surface finish, compositional gradients and hardness are provided. Also, a thermal – based finite element numerical model that was used to simulate the LENS process is presented, along with some demonstrated results.

Committee:

Rajiv Shivpuri (Advisor)

Keywords:

Hot forging; Die wear; Thermal softening; In-service tempering; Tempering parameters; Laser engineered net shaping (LENS); Nickel aluminide; AISI H13 tool steel; Cladding

Dangarwala, Gaurav A.A model of the change in viscosity of polyimide PMR-15 during cure
Master of Science (MS), Ohio University, 1993, Chemical Engineering (Engineering)

A model of the change in viscosity of polyimide PMR-15 during cure

Committee:

Daniel Gulino (Advisor)

Subjects:

Engineering, Chemical

Keywords:

viscosity; polyimide PMR-15; Diels-Alder Rection; non-linear parameters

Cooper, RickThe effects of a nearby biological body on the parameters of a small hand-held radio operating in the H.F. band (3 MHz-30 MHz)
Master of Science (MS), Ohio University, 1992, Electrical Engineering & Computer Science (Engineering and Technology)

The effects of a nearby biological body on the parameters of a small hand-held radio operating in the H.F. band (3 MHz-30 MHz)

Committee:

Roger Radcliff (Advisor)

Keywords:

Biological body Parameters; hand-held radio; H.F. band (3 MHz-30 MHz)

Perrin, Christopher J.FURTHER ANALYSIS OF VARIABLES THAT AFFECT SELF-CONTROL WITH AVERSIVE EVENTS
Doctor of Philosophy, The Ohio State University, 2010, EDU Physical Activity and Educational Services
The purpose of this study was to examine variables that affect self-control within the context of academic task completion by elementary school children diagnosed with autism. In the pre-assessment of study 1, mathematics problem completion was shown to be an aversive event, and sensitivity to task magnitude, task difficulty, and delay to task completion was measured. The self-control assessment assessed the effects of manipulating values of those parameters on self-control. For all participants, self-control increased as a function of one or more changes in task parameter values. In study 2, the effects of a commitment response on self-control was assessed. Results indicated that for all participants, levels of self-control were higher when the opportunity to commit to the immediate aversive event was available.

Committee:

Nancy Neef, PhD (Advisor); Ralph Gardner, PhD (Committee Member); Helen Malone, PhD (Committee Member)

Keywords:

self-control; aversive events; concurrent schedules; task parameters; magnitude; response effort; task difficulty; delay; commitment

Schnell, ThomasLegibility optimization of uppercase alphanumeric text for displaying messages in traffic applications
Doctor of Philosophy (PhD), Ohio University, 1998, Industrial and Manufacturing Systems Engineering (Engineering)

This dissertation research investigated the legibility of uppercase, single line sets of characters/numerals or single words made up by standard highway fonts. A series of carefully controlled laboratory legibility experiments were conducted to determine the effects of letter height H, letter width-to-height ratio (W/H), stroke width-to-height ratio (SW/H), inter character spacing-to-height ratio (S/H), on the legibility of single line sets of characters/numerals or single words made up by standard highway fonts. Legibility was investigated in terms of threshold contrast for achromatic positive and negative contrast polarity and for typical highway sign color combinations. This research involved four experimental phases: 1. A pilot experiment to determine the feasible range for the independent variables (H, W/H, SW/H, background luminance, only simple, straight line letters E,F, and L used as stimuli), 2. A full factorial experiment to investigate the legibility effects of H, W/H, SW/H, S/H for positive achromatic contrast (typical street names used as stimuli), 3. A full factorial experiment to investigate the legibility effects of H, W/H, SW/H, S/H for negative achromatic contrast (typical license plate alphanumeric legends used as stimuli), 4. Two combined full factorial experiments to investigate the legibility effects of H, W/H, SW/H, S/H for chromatic stimuli for typical highway sign color combinations (positive contrast: white on green, negative contrast: black on yellow, black on orange, and blue on white). The threshold contrast data that was obtained, served as the basis for the development of a legibility optimization software package entitled OptFont. This program consists of a numerical minimization algorithm that determines the threshold contrast of a large number of combinations (specified by the user) of typographical parameters, and then ranks all typographical alternatives that satisfy the sign size constraints. OptFont is useful both for optimizing sub-optimal signs, and for confirming the superior performance of optimal or near optimal signs over other typographical alternatives. It is conceivable, that an automated legibility optimization algorithm like OpFont may become an integral part of sign- drafting packages. Continuously scaled and automatically optimized alphabets could, over time, replace the standard highway alphabets with their discrete typographical parameters. Future research is indicated.

Committee:

Helmut Zwahlen (Advisor)

Subjects:

Engineering, Industrial

Keywords:

Legibility optimization; alphanumeric text; traffic applications; discrete typographical parameters; stroke width-to-height ratio; letter width-to-height ratio

Fang, YuguangStability analysis of linear control systems with uncertain parameters
Doctor of Philosophy, Case Western Reserve University, 1994, Systems and Control Engineering
In this dissertation, we study stochastic stability of linear systems whose parameters are randomly varying in a certain sense. In particular, we present a new approach to stochastic stability analysis of systems whose system structure is randomly changing among a finite set of possibilities which capture the abrupt changes in systems parameters or sudden failures of system components. These types of systems are referred to as jump linear systems with a finite state Markov chain form process. We first investigate the properties of various types of moment stability for stochastic jump linear systems, and use large deviation theory to study the relationship between "lower moment" stability and almost sure stability. In particular, we have proved that the region for δ-moment stability is monotonically increasing as δ is decreasing to zero and asymptotically converges to the region for almost sure stability. Roughly speaking, this is equivalent to saying that almost sure stability is equivalent to δ-moment stability for sufficiently small δ > 0. Furthermore, we prove that although the top δ-moment Lyapunov exponent is, in general, not differentiable at zero, it is differentiable at zero from the right and its right derivative at zero is equal to the top Lyapunov exponent. This answers a long standing question in this area. Based on this analysis, a new Lyapunov function is constructed to obtain a very general sufficient condition for almost sure stability, and this condition is also conjectured to be a necessary condition for almost sure stability. Moreover, a few new approaches for the study of almost sure stability are proposed and some easily-testable conditions for both moment stability and almost sure stability are obtained. Based on the results on almost sure stability and moment stability, the stochastic stabilization problem is also considered and a few future research topics are identified. This dissertation is the first research work in the current literature to use large deviation theory to study stochastic stability and further represents a systematic study of almost sure stability of jump linear systems with a finite state Markov chain form process. It is our high hope that this work will pave the way for further studies on the almost sure (sample path) stability for stochastic systems.

Committee:

Kenneth Loparo (Advisor)

Keywords:

Stability analysis; linear control systems; uncertain parameters

Yovichin , Richard DHyperbolic Representation of Force Versus Displacement Relationship for Lateral Pipe Movement in Dry Soil
Master of Science in Engineering, Youngstown State University, 2018, Department of Civil/Environmental and Chemical Engineering
Research and engineering practices for an earthquake response of underground pipelines has focused on permanent and transient ground deformation (PGD and TGD) effects, with the recognition that PGD often causes the most serious local damage in buried pipeline networks. The effects of permanent ground deformation not only apply to earthquakes, but also occur in response to floods, landslides, tunneling, deep excavations, and subsidence caused by dewatering or the withdrawal of minerals and fluids during mining and oil production. Such loading conditions are becoming more important as the needs for technology development increase to combat issues regarding natural hazards, human threats, and construction in congested urban environments. Of key importance in this research is the soil and pipeline interaction with respect to PGD below subsurface. This response is typically highlighted by force vs. displacement relationship and is primarily a function of soil density, depth, and diameter of pipe. The force vs. displacement relationships for transverse horizontal force on pipelines subjected to lateral ground movement are represented by a hyperbola. Transforming such hyperbola into a linear representation can make analysis of soil-pipe interaction much easier. This process allows for the development of a simplistic model representing a wide range of soil characteristics. The development of this simplified, yet practical, nonlinear force vs. displacement relationship for lateral pipe movement, using hyperbolic parameters, is useful to engineers. This approach is convenient for modeling the soil-pipe interaction and is critical for addressing the complexities of soil and pipe performance, consistent with real world soil-pipe behavior, by illustrating the minimum soil control design and the maximum soil resistance.

Committee:

Jai Jung, PhD (Advisor); AKM Islam, P.E., PhD (Committee Member); Richard Deschenes, PhD (Committee Member)

Subjects:

Civil Engineering; Geotechnology

Keywords:

Lateral Displacement; Hyperbolic Representation; Dimensionless Force versus Displacement;Varying soil unit weights; A and B parameters

Zhang, YuleiComputer Experiments with Both Quantitative and Qualitative Inputs
Doctor of Philosophy, The Ohio State University, 2014, Statistics
Physical experiments play an important role in agriculture, industry, and medical research. However, physical experiments can sometimes be difficult or even impossible to run. In these situations, computer experiments are becoming desirable surrogates for physical experiments. This dissertation considers designs and the predictive models for computer experiments with both quantitative and qualitative input variables. The existing framework for building Gaussian stochastic process (GaSP) models with quantitative and qualitative inputs is to treat a given set of values of the qualitative inputs as determining a response surface in the qualitative inputs. A GaSP model is assumed for each of these response surfaces and the same covariance structure is used for each response surface. A cross-correlation parameter is introduced for each pair of sets of values of the qualitative variables in order to "capture" correlations between response surfaces. To guarantee that one has a legitimate overall covariance structure, certain conditions are imposed on the cross-correlation parameters. In the first part of this dissertation, we introduce two indicator-based GaSP models by transforming the qualitative inputs into quantitative variables and then use traditional correlation functions for quantitative inputs. We also show the equivalence properties between these new models and the existing model. The second part of this dissertation is about the experimental designs with both quantitative and qualitative inputs. The special data structure requires that a "good" design not only capture the cross-correlation information but also spread observations out over the entire quantitative inputs space. We propose two types of designs, the partial SLHD and partial CSLHD, which are modifications of existing designs in the literature, and compare their prediction accuracy with all the other existing designs for quantitative and qualitative. By examining several examples, we find that what constitutes a "good" design may vary from case to case. We summarize these findings with a "guideline" for selecting initial designs. Furthermore, when the initial design does not perform well, we also propose a sequential design algorithm to interpolate or extrapolate the target response levels in a GaSP model with mixed inputs. Inspired by factor analysis, in the last part of this dissertation, we build a more general composite covariance structure by converting the GaSP model with several qualitative levels into a linear combination of independent stochastic processes with fewer constraints on the variance and correlation functions. Furthermore, this composite covariance structure can be extended to the case with multiple qualitative inputs. In these cases, we introduced the Kronecker product form of the composite covariance function, which can not only reduce the number of the parameters, but also capture the similarity between different qualitative inputs with some identical components. In addition, we propose an ANOVA decomposition form of the Gaussian processes, which imposes a factorial structure on the response outputs. Finally, we extend the sequential design algorithm to the composite GaSP model.

Committee:

William Notz (Advisor); Peter Craigmile (Committee Member); Matthew Pratola (Committee Member)

Subjects:

Statistics

Keywords:

Computer Experiments; Physical Experiments; Gaussian Stochastic Process Model; Quantitative and Qualitative Inputs; Cross-Correlation Parameters; Experimental Designs; Composite GaSP Model; Factor Analysis; Kronecker Product; ANOVA Decomposition

Borrero, Antonio J.Assessing Kalman filter in the identification of synchronous machine stability parameters
Master of Science (MS), Ohio University, 1983, Electrical Engineering & Computer Science (Engineering and Technology)

Assessing Kalman filter in the identification of synchronous machine stability parameters

Committee:

Nasser Jaleeli (Advisor)

Keywords:

Kalman Filter; Synchronous Machine Stability Parameters; Synchronous Machine Equations

SUBRAMANIAN, ANANDDESIGN FOR DISASSEMBLY - QUANTITATIVE ANALYSIS SOFTWARE: BASED ON THE PARAMETERS AFFECTING DISASSEMBLY
MS, University of Cincinnati, 2004, Engineering : Industrial Engineering
Design is the creative process by which our understanding of logic and science is joined with our understanding of human needs and wants to conceive and refine artifacts that serve specific human purposes. Quality Design is that process and activity that needs to be carried out to enable the manufacture of a product that fully meets customer requirements. The ultimate aim of design is essentially to satisfy all the direct and indirect needs of the internal, intermediate and final users. Hence, designing process forms the crux of all the operations in any organization. With strong competition from all over the world and strong customer awareness for quality, manufacturers have to look hard at how they can achieve a competitive edge that will keep them alive and hopefully take them into a leadership position. Much has been done in production to reduce the workforce, speed up production lines and generally address the quality of the manufactured product. The role of design in the product delivery process seems to have had much less emphasis applied to it and it may be in this area that we can now begin to make the most significant gains in product quality. But, not only is it necessary that the organization take steps to solve this problem on-hand but also, it is very much important that the steps in the direction be taken at earnest because the users needs are dynamic in nature and more often than not it has been researched that his wants and needs change by the time a solution is developed.It is here that the role of Information-technology plays a very important part. The advantages of the integration of technology with the design process cannot be neglected. The use of programs to develop an optimal design has increased the efficiency and the quality of manufacturing. The implementation of a software interface to design for disassembly will facilitate not only in determining accurately the existing times for disassembly and identifying anomalies in the product design from the disassembly perspective but also gives it a more professional, organized and logical approach. However, the final decision regarding design alteration would be a human one and would be based on the technical, economic and operational feasibility.

Committee:

Dr. Anil Mital (Advisor)

Subjects:

Engineering, Industrial

Keywords:

Design for Disassembly; Quantitative disassembly parameters.

BALASUBRAMANIAN, SHYAM SUNDARA NOVEL METHODOLOGY FOR MODELING PERFORMANCE PARAMETERS OF ANALOG CIRCUITS
MS, University of Cincinnati, 2004, Engineering : Computer Engineering
The need to explore large design spaces and the large computational overhead in full circuit simulations has been the driving factor for the use of performance estimation techniques in automated synthesis of analog and mixed-signal circuits. One such technique called Macromodeling has been used extensively nowadays owing to their accuracy (comparable to the simulators) and speed. The smaller evaluation time and comparable accuracy of these models to the simulators like HSPICE have made them quite popular for use in synthesis algorithms (which optimize a cost function based on performance constraints). Traditional Macromodeling approaches involve the generation and use of a separate macromodel for each performance parameter and consequently, does not support the dynamic addition of performance parameters. The addition of a new performance constraint necessitates charactarization data regeneration and model development phase and consequently, a large time overhead. In this thesis, we present a new approach wherein we develop a model for producing the entire AC response curve rather than separate models for each performance parameter. The model consists of a set of regressors (which have been implemented using polynomials followed by regression on the polynomial coefficients using neural networks) which take in the design variables as input and produce the AC response as output very quickly. Thus, the addition of a performance parameter requires the evaluation of that parameter from the calculated response and thus, eliminates the data re-generation and model development time overhead. In essence, the proposed approach supports and requires very minimal overhead for the dynamic addition of performance parameters. The performance parameters, calculated from the evaluated response, are then used for the cost function optimization in the synthesis loop.

Committee:

Dr. Ranga Vemuri (Advisor)

Keywords:

Analog Macromodeling; Modeling Performance Parameters

Brown, Stephen W.The Reasonable Score
MA, University of Cincinnati, 2009, Arts and Sciences : Philosophy
Current research in contextualist semantics has not adequately dealt with cases where parties to a conversation unwittingly disagree about certain contextual parameters. David Lewis has suggested that there is a set of values for various contextual parameters in all conversations called a conversational score, where the course of the conversation affects what enters into the conversational score, and in turn, the conversational score affects the course of the conversation. The question remains, however: what enters into the conversational score, and how? I propose to answer this question by appeal to a notion of “reasonable score”: A value for a given contextual parameter enters the score if a reasonably prudent person would say that that value enters the score. I draw on Anglo-America common law as source to clarify this seemingly vague concept of reasonableness.

Committee:

Christopher Gauker, PhD (Advisor); Jenefer Robinson, PhD (Committee Member); Robert Skipper, PhD (Committee Member)

Keywords:

Descartes; contextual parameters; utterances

Gazawi, AymanEVALUATING COSMO-RS FOR VAPOR LIQUID EQUILIBRIUM AND TURBOMOLE FOR IDEAL GAS PROPERTIES
Master of Science, University of Akron, 2007, Chemical Engineering
The focus of this study is to evaluate the COSMO-RS approach as a mainstream engineering property methodology. Particular emphasis was placed on the VLE and vapor pressure predictions. We used Turbomole software package version 5.8 with DFT/TZVP ab initio method for; sigma profile, ideal gas heat capacity and ideal gas absolute entropy computation of 71 pure compounds. We used Cosmotherm program version 2.1 for VLE calculation of 104 binary systems based on COSMORS-E and COSMORS-gamma approach. Also, the Cosmotherm program was used for vapor pressure computation of 71 pure compounds. For the VLE predictions; the %AADbp for COSMORS-E results were in the 29 to 55% range with an overall average of 35%, while the %AADbp for COSMORS-gamma results were in the 4 to 16% range with an overall average of 8.8%. The % AADP for COSMO-RS vapor pressure results; were in the 3 to 142% range with an overall average of 35%. The %CpERROR; was in the 0 to 21% range with an overall average of 7%. The %SabsERROR; was in the range of 0 to 13 % with an overall average of 4 %. The average deviation in Hf was 138 kcal/mole, and included errors in sign.

Committee:

Richard Jr Elliott (Advisor)

Keywords:

COSMO-RS; VLE; Ideal Gas: Heat Capacity; Absolute Entropy and Enthalpy of Formation; Sigma Profile; Binary Interaction Parameters

Dalqamouni, Ahmad YousefDevelopment of a Landslide Hazard Rating System for Selected Counties in Northeastern Ohio
PHD, Kent State University, 2011, College of Arts and Sciences / Department of Geology

The northeastern portion of Ohio is categorized as a region of high landslide susceptibility and hazard potential. The areas that are most susceptible to landslides are located along steep-sided valleys and along roads cuts through weak glacio-lacustrine silts and clays. Landslide hazard includes any direct or indirect hazard posed to humans and properties because of landslide activity. In order to identify slopes exhibiting varying degrees of hazard potential, and to help engineers prioritize their remediation efforts, this dissertation proposes a new landslide hazard rating system for Northeastern Ohio.

Forty nine slopes with different hazardous levels (low, moderate, high) were selected for development of the hazard rating system. The slopes were selected so that they were representative of the variations of geometric, geologic, hydrologic, and traffic conditions in the study area. Twelve parameters were initially considered for developing the landslide hazard rating system. These parameters were divided into three groups: the soil-related and hydrologic group, the slope-geometry related group, and the traffic-related group. Univariate, bivariate, and cluster analyses were performed on the collected data to identify parameters that were most significant in distinguishing between slopes of varying hazard potential. The statistical analysis identified six of the twelve parameters as statistically significant. These six parameters were included in the final rating system. In addition, three other parameters that were not found to be statistically significant but have been shown to be important by the existing rating system were retained in the final rating system.

The nine parameters used in the final landslide hazard rating system for northeast Ohio include liquidity index, recharge area, slope height, slope length, slope angle, average daily traffic, decision sight distance, degree of vehicle risk, and length of roadway affected. Based on site condition, each parameter in the system was assigned scores using an exponential scale (3, 9, 27, 81), with the total score for a given slope being the sum of the scores for individual parameter.

According to the rating scale, the minimum scores should not be less than 27 and the maximum scores could not exceed 729. The lowest score a site in the study area scored is 87 and the highest score is 567. Based on hazard criteria discussed in the dissertation and field observations of hazard potential, sites with scores < 200 were categorized as low hazard potential sites, those with scores between 200 and 300 as moderate hazard potential sites, and those with scores > 300 as high hazard potential. The final system rated 23 sites as low hazard potential sites, 15 sites as moderate hazard potential sites, and 11 sites as high hazard potential sites whereas field observations at the start of the study categorized 26, 13, and 10 sites belonging to the low, moderate, and high hazard potential categories, respectively.

Committee:

Abdul Shakoor, PhD (Advisor); Daniel Holm, PhD (Committee Member); Joseph Ortiz, PhD (Committee Member); Mandy Munro-Stasiuk, PhD (Committee Member); Mark Seeman, PhD (Committee Member)

Subjects:

Geology; Geomorphology; Geotechnology

Keywords:

engineering geology; landslides; hazard rating system; northeastern ohio; traffic parameters; liquidity index; slope geometry; cluster analysis; glacial geology; exponential scale; high hazard potential; quantitative system

Yadlapati, Sai AvinashInfluence Of FDM Build Parameters On Tensile And Compression Behaviors Of 3D Printed Polymer Lattice Structures
Master of Science in Mechanical Engineering (MSME), Wright State University, 2018, Mechanical Engineering
This research focuses on the compression and tensile behavior of three-dimensional printed polymer lattice structures with different printing parameters such as build orientation, infill density, and layer thickness. The body-centered cubic (BCC) lattice unit cell, which has been extensively investigated for energy absorption applications, is considered here to create compression and tensile specimens. Special test fixture was designed and developed to perform the tensile tests. The specimens were printed using Acrylonitrile Butadiene Styrene (ABS) polymer material on a Stratasys uPrint 3D printer. The printing parameters considered in this case are: (a) Three different build orientations (0, 45 and 90 degrees); (b) Two different infill densities (Sparse High and Solid); and (c)Two different layer thicknesses (0.010 and 0.013 inch). Once fabricated, the specimens were imaged using an optical microscope (OM) to capture their surface characteristics. Strut dimensions of all specimens are measured to understand their build accuracy. In addition, fabrication time for each configuration were recorded for comparison. The specimens were then tested under quasi-static compression and tension to determine the stiffness, failure loads, and energy absorption behaviors. Specific properties were also calculated by dividing the test properties by the specimen mass. All the test data obtained from OM and mechanical tests were then compared and interpreted with respect to all the three build parameters.

Committee:

Ahsan Mian, Ph.D. (Advisor); Zifeng Yang, Ph.D. (Committee Member); Joy Gockel, Ph.D. (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

compression behavior; tensile behavior; three-dimensional printed polymer lattice; build orientation; infill density; layer thickness; body-centered cubic lattice; FDM build parameters; 3D printed polymer lattice

Roman, Abdeel J.Studies of Horizontal Two-Phase Flow Using Electrical Capacitance Tomography and R-134a
Doctor of Philosophy (Ph.D.), University of Dayton, 2017, Aerospace Engineering
Future high performance aircraft will need non-conventional thermal management systems to remove challenging heat loads. Historically, aircraft thermal management systems have relied on a combination of air cycle machine and fuel for cooling heat sinks. Next generation tactical aircraft may rely on a vapor compression system as a method to manage thermal loads. Vapor compression systems (VCS) offer higher coefficient of performance (COP) values than aircraft cycle system (ACS). However, the design of a VCS system is more complex since two phases (liquid-vapor) are used to remove heat. In order to incorporate a VCS system in future tactical aircraft design, an understanding of two-phase flow behavior is needed. This experimental dissertation seeks to increase the understanding of two-phase flow behavior and is divided into three segments. In the first segment of this dissertation, electrical capacitance tomography and neural networks were used to identify two-phase flow patterns for refrigerant R-134a flowing in a horizontal tube. In laboratory experiments, high-speed images were recorded for human visual classification of liquid–vapor flow patterns. The corresponding permittivity data obtained from tomograms was then used to train feed-forward neural networks to recognize flow patterns. An objective was to determine which subsets of data derived from tomograms could be used as input data by a neural network to classify nine liquid–vapor flow patterns. Another objective was to determine which subsets of input data provide high identification success when analyzed by a neural network. Transitional flow patterns associated with common horizontal flow patterns were considered. A unique feature of this research was the use of the vertical center of mass coordinate in pattern classification. The highest classification success rates occurred using neural network input which included the probability density functions (in time) for both spatially averaged permittivity and center of mass location in addition to the four statistical moments (in time) for spatially averaged permittivity data. The combination of these input data resulted in an average success rate of 98.1% for nine flow patterns. In addition, 99% of the experimental runs were either correctly classified or misclassified by only one flow pattern. In the second segment, electrical capacitance tomography was used to measure the void fraction and maximum dry angle for refrigerant R-134a flowing in a horizontal tube. These parameters are used for predicting heat transfer coefficients and pressure drop. A new calibration approach was used that accounted for the changes in the dielectric constant of both the liquid and vapor phases due to temperature variations. The capability of the ECT system to measure the void fraction was assessed in static and dynamic experiments. Time-averaged void fractions compared well with correlations found in the literature. Further, a new technique using tomographic images to determine the maximum dry angle was introduced in this dissertation. It was shown that this technique can be used to measure the maximum dry angle for stratified to partially dry out annular flows when compared to existing correlations. In the third segment, electrical capacitance tomography was used to measure the changes in void fraction upstream, downstream, and immediately after a horizontal sudden expansion for refrigerant R-134a. The two-phase flow behavior occurring in the sudden expansion was also analyzed using a high speed camera. An analysis of the effects of selecting a void fraction parameter upstream, downstream, and immediately after a sudden expansion was studied to determine how this parameter affects correlations for pressure losses. Several void fraction correlations found from the literature were applied upstream, downstream, and immediately after a sudden expansion using experimental data. It was found that none of the correlations could model the behavior of the void fraction occurring immediately after a sudden expansion. A modified void fraction correlation was proposed to model the behavior of void fraction occurring right after the expansion. This new void fraction model was able to predict the void fraction immediately after a sudden expansion within 20% or better when compared with experimental data at mass velocities of 150, 200, and 250 kg/m2s.

Committee:

Jamie Ervin, Ph.D. (Advisor); Rober Wilkens, Ph.D. (Committee Member); Larry Byrd, Ph.D. (Committee Member); Scott Stouffer, Ph.D. (Committee Member)

Subjects:

Aerospace Engineering; Engineering; Experiments

Keywords:

Horizontal Two Phase Flow; Electrical Capacitance Tomography; Neural Networks Characterization; Two-Phase Flow Dry Angle and Void Fraction Parameters; Sudden Expansion in Two-Phase Flow

El-Taleb, Ahmed SalemInvestigation of Mold Design and Process Parameters in Microinjection Molding to Fabricate a Deformable Membrane Mirror
Doctor of Philosophy, The Ohio State University, 2013, Industrial and Systems Engineering
Deformable membrane mirrors (DMMs) are often used for adaptive optics in the fields of astronomy, laser communication, medical imaging, and industrial high energy lasers. As light passes through an optical system (and a specimen), phase variations are introduced resulting in wavefront distortion from an ideal spherical form. In order to compensate for such phase variations, an equal but opposite phase change can be introduced by using a DMM. The shape of the DMM is typically altered via an applied electrostatic field, which controls the distortion of the mirror. The manufacture of DMM&#x2019;s today is a relatively expensive and time-consuming endeavor. The objective of this research is to evaluate the technical feasibility of a new DMM design using plastic materials, and the cost effective microinjection molding process. The proposed design consists of three distinctive regions in the cross section of the DMM. These three regions are the solid frame, microchannel, and mirror. The critical optical features of the proposed design include the flatness and flexibility of the circular mirror in the center of the DMM. This is accomplished by designing a thin ring microchannel around the mirror. The thickness and depth of this microchannel are critical for successful molding. This microchannel has 16 slots that are molded on the perimeter of the mirror to add more flexibility (for subsequent electrostatic distortion control) and serve as reservoirs where the air can escape the mold cavity during the microinjection molding manufacturing process. During this research, the technical feasibility of the design is demonstrated using both computer simulations as well as experiments. Specifically, a DMM with microfeatures has been designed with the aid of a computer-aided engineering (CAE) analysis program, Moldex3D. This was done, before any actual experiments were conducted, to understand the flow behavior of the polymer melt in the mold cavity with various processes and geometric parameters. For example, micro slots were investigated to serve the dual purposes of venting channels in the mold cavity, and also as the supporting mechanism for DMM mirror operation. The main concerns of microinjection molding of a DMM part include: failure to fill the cavity due to premature solidification (because of quick cooling due to small cavity thickness), air trapped in microinjection mold inserts (because of inadequate venting), and limitation of the machine capacity (clamping force and pressure). In this research, a design of experiment technique was used to study the effects of the controllable process variables of microinjection molding (such as packing pressure, packing time, and injection speed) on DMM mirror surface quality. The goal of this study was to identify the dominant processing parameters and the interactions among the parameters using a systematic approach. The response surface methodology (RSM) was used to approximate a stochastic function of input-output relations in a statistical model, toward the goal of identifying the best feasible settings of the microinjection molding parameters to minimize the DMM surface variation. Finally, the microinjection molded DMMs were tested using a Michelson interferometer to verify their optical performance. The main contribution of this research was to evaluate the technical feasibility of a new DMM design using thermoplastic materials, manufactured using the cost effective microinjection molding process. Experiments and simulated flow patterns for various DMM geometric parameters were compared, and different approaches for characterizing the dimensions and the performance of the DMMs were investigated. A further contribution of this research was the use of design of experiment techniques to determine the micro injection molding process parameters that minimize the DMM mirror surface variability.

Committee:

Jose Castro (Advisor); Allen Yi (Advisor)

Subjects:

Industrial Engineering; Polymers

Keywords:

Microinjection molding; mold design; microchannel; deformable membrane mirror; process parameters

Milliman, HenryREINFORCEMENT OF MELT-BLEND COMPOSITES; POLYMER-FILLER INTERACTIONS, PHASE BEHAVIOR, AND STRUCTURE-PROPERTY RELATIONSHIPS
Doctor of Philosophy, Case Western Reserve University, 2012, Macromolecular Science and Engineering
In recent years POSS (polyhedral oligomeric silsesquioxanes) has been incorporated into a number of polymers as a copolymer, graft or as a melt-blend. The advantages gained from using POSS come from its hybrid organic-inorganic nature whose inorganic core provides molecular reinforcement while its variety of functionalization schemes allow for reaction or other interactions with the host polymer. Previous work has shown the ability of POSS to reinforce polymers when incorporated through grafting or copolymerization, but there is a lack of understanding of how to obtain successful reinforcement when using POSS as a melt-blend additive. One hypothesis is that a high degree of POSS-polymer interactions are necessary which promote a pseudo-grafted structure yielding results similar to that of copolymer system. The first part of this thesis (Chapters 2 and 3) will address the role of POSS-polymer interaction in reinforcement. Specifically, Chapter 3 will discuss a new approach to predicting these interactions through the determination of Hansen solubility parameters. This approach however does not take into account the role of processing. Chapter 4 will address this by evaluating the structure-property relationships in melt-spun fiber composites. Finally, Chapter 5 will discuss a different field of polymer composites, polymer clay aerogels. In this work the use of these low-density composites as an oil absorbing media will be discussed.

Committee:

David Schiraldi, PhD (Committee Chair); Hatsuo Ishida, PhD (Committee Member); Joao Maia, PhD (Committee Member); Xiong Yu, PhD (Committee Member)

Subjects:

Chemistry; Materials Science; Polymers

Keywords:

POSS; composites; blends; structure-property relationships; phase behavior; Hansen solubility parameters

Bourawi, Mustafa S.Identification of synchronous machine stability parameters using a quasilinearization-least-square-error algorithm
Master of Science (MS), Ohio University, 1984, Electrical Engineering & Computer Science (Engineering and Technology)

Identification of synchronous machine stability parameters using a quasilinearization-least-square-error algorithm

Committee:

Nasser Jaleeli (Advisor)

Keywords:

Quasilinearization-Least-Square-Error Algorithm; Transition Matrix; Synchronous Machine Steady State Parameters

Vaidyanathan, AarthyAN EXPERIMENTAL INVESTIGATION OF HELICAL GEAR EFFICIENCY
Master of Science, The Ohio State University, 2009, Mechanical Engineering
In this study, a test methodology for measuring load-dependent (mechanical) and load-independent power losses of helical gear pairs is developed. A high-speed four-square type test machine is adapted for this purpose. Several sets of helical gears having varying module, pressure angle and helix angle are procured, and their power losses under jet-lubricated conditions are measured at various speed and torque levels. The experimental results are compared to a helical gear mechanical power loss model from a companion study to assess the accuracy of the power loss predictions. The validated model is then used to perform parameter sensitivity studies to quantify the impact of various key gear design parameters on mechanical power losses and to demonstrate the trade off that must take place to arrive at a gear design that is balanced in all essential aspects including noise, durability (bending and contact) and power loss.

Committee:

Ahmet Kahraman, PhD (Advisor); Donald Houser, PhD (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

Helical; gear; efficiency; gear design parameters;

Kalapati, Raga SAnalysis of Ozone Data Trends as an Effect of Meteorology and Development of Forecasting Models for Predicting Hourly Ozone Concentrations and Exceedances for Dayton, OH, Using MM5 Real-Time Forecasts
Master of Science, University of Toledo, 2004, Civil Engineering
The objective of this research was to develop and evaluate models for predicting hourly ozone concentrations, ozone exceedances and hourly air quality index (AQI) in Dayton, OH. As the hourly ozone concentrations are closely related to the meteorological conditions, three variables- temperature, wind speed, and dew point temperature- were chosen for this study. The ozone data were extracted from the EPA’s AIRS database for the period 1996-2003. The meteorological data was taken from the National Climatic Data Center (NCDC) for the same period. An analysis of variations in hourly ozone concentrations and ozone episode occurrences was carried out for the period Apr.-Oct. for the years 1996-1999. Also, analysis of the long-term trends in annual means of ozone concentrations, temperature, wind speed, and dew point temperature was performed using the same data set. Based on this analysis, the ozone data was divided into pre-summer (Apr.-Jul.) and post-summer (Aug.-Oct.) seasons, to account for seasonal variations, and each season was further divided into three regimes, namely, stable period (hours: 1-8), ascent period (hours: 9-16), and descent period (hours: 17-24). The KZ filter technique was used to reduce the scatter in the time series, and models were developed for the three regimes for each season by regression, using the corresponding independent parameter values. A total of twelve models were developed to predict ozone concentrations for pre-summer and post-summer periods. Six models considered temperature, wind speed, and dew point temperature as the independent variables (three-parameter models), and the other six considered temperature and wind speed as variables (two-parameter models). Also, three models each for pre-summer and post-summer season were developed for predicting the ozone exceedances. The performance of the models was evaluated in three ways: a) Initial evaluation (or validation) of the models was conducted using 2002 data. b) The effectiveness of these models was further evaluated using available MM5 (a mesoscale meteorological forecasting model) real-time forecasts from the Ohio State University for the months of Aug.-Oct., 2003. c) Finally, the performance of the three-parameter models was compared with that of the two-parameter models. All the evaluations were made using statistical evaluation parameters discussed later. The study shows that the forecasts of hourly ozone concentrations made by the models based on KZ filters are reliable only to a limited extent. However, the models performed well in predicting AQI values reported by the EPA. Also, the three-parameter models performed better in predicting the peak concentrations when compared to the two-parameter models.

Committee:

Ashok Kumar (Advisor)

Subjects:

Engineering, Environmental

Keywords:

hourly ozone concentrations;ozone exceedances;hourly air quality index;Ozone annual and seasonal trends;MM5 (a mesoscale meteorological forecasting model);KZ filter technique;regression analysis;statistical evaluation parameters

Adolf, James DavidFUNCTION OF ADDITIVES IN COPPER ELECTRODEPOSITION FOR SEMICONDUCTOR DEVICE METALLIZATION
Master of Sciences (Engineering), Case Western Reserve University, 2008, Chemical Engineering
The present research is aimed at improving the understanding, developing more accurate modeling tools and extending the capabilities of the bottom-up copper plating process - the current metalization technique of semiconductor interconnects. An analytical technique for extracting accurate transport and competitive adsorption parameters for a multi-component additives system, using relatively simple electrochemical polarization experiments, is presented and specifically applied to polyethylene glycol (PEG), a commonly used plating inhibitor. Further research focused on a second class of inhibitors, based on nitrogen containing additives ('levelers'). An unusual displacement hierarchy in systems containing PEG, bis-(3-sulfopropyl) disulfide, and the leveler Janus Green B was ascertained experimentally. The underlying principle behind using a very high molecular weight leveler to significantly increase bottom-up fill capabilities is presented and a semi-quantitative model of the process is developed.

Committee:

Uziel Landau, Dr. (Advisor); J. Adin Mann, Dr. (Committee Member); Heidi Martin, Dr. (Committee Member)

Subjects:

Chemical Engineering

Keywords:

leveler; bottom up fill; kinetic parameters; copper; JGB; PEG; SPS;

Patience, WilliamNoise analysis of multiport networks containing GaAs FETs based on measured data or physical FET parameters
Master of Science (MS), Ohio University, 1991, Electrical Engineering & Computer Science (Engineering and Technology)
Noise analysis of multiport networks containing GaAs FETs based on measured data or physical FET parameters

Committee:

Ebrahim Mokari (Advisor)

Keywords:

Noise Analysis; Multiport Networks; GaAs FETs based on Measured Data; Physical FET Parameters

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