MFA, Kent State University, 2023, College of Communication and Information

The combination of variable fonts and digital signage presents a unique and practical solution to the various challenges wayfinding systems face. These challenges include issues with readability, monolingual signage, low visibility, minimal readership, material waste, and limited adaptability to environmental conditions and space functionality. Variable fonts, on the other hand, are incredibly versatile and adaptive. They can be easily modified, and their display methods can be customized for any resolution or medium, static or digital. With new infrastructures and spaces emerging, typographic and display technologies are continually evolving. Designers must capitalize on and leverage these advancements to instill a better experience for those interacting with them. This investigation examines the directional attributes of a partially formed typeface to ascertain whether typography alone can aid users in navigating a given space. The findings of this investigation set the foundation for shaping the future of environmental graphic design and type design.

Committee: David Middleton (Advisor); Aoife Mooney (Committee Member); Jessica Barness (Committee Member) Subjects: Communication; Design; Instructional Design; Technology

Doctor of Philosophy (PhD), Ohio University, 2023, Mechanical and Systems Engineering (Engineering and Technology)

The science of organic Rankine cycle (ORC) waste heat recovery is advanced through a demonstration system including a scroll expander-generator, zeotropic mixture working fluid, low approach temperature counterflow heat exchangers, and regenerative-turbine liquid pump. A warm-water cooled information and communication technology high performance computing rack consuming 30kW electricity is the focus system. Viability of ultra-low waste heat recovery is improved by maximizing electricity production and minimizing both heat transfer inefficiencies and parasitic losses. Peak scroll expander isentropic efficiency exceeds 60% but falls precipitously in off-design conditions. The selected working fluid complies with environmental, health, and safety requirements and exhibits optimum thermal performance but built environment use rules of A2L fluids are in process of being formalized. Liquid pump limitations create space challenges for heat rejection to ambient equipment. The ORC is a net consumer of electricity but can significantly improve power usage effectiveness (PUE). However, TH to TL difference with typical maximum CPU temperature and maximum data center ambient temperature create a flow instability regime in the expander. Year-round ORC operation is thus precluded.

Committee: Greg Kremer (Committee Chair) Subjects: Experiments; Mechanical Engineering

Master of Science, The Ohio State University, 2020, Mechanical Engineering

In this study, an experimental investigation on the influence of tensile mean stress on gear tooth bending fatigue life is performed. A newly developed single-tooth bending test machine is utilized to perform gear tooth bending fatigue experiments under various loading conditions. A new single-tooth bending test fixture is developed for a chosen test gear. A detailed experimental methodology is presented on dynamic and static strain measurements of the chosen test gear root fillet profile in order to (i) quantify any dynamic loading effects at high loading frequencies, and (ii) validate maximum root stress predictions. Two sets of fatigue tests are performed at load levels of R = 0.05 and R = 0.5 whose results are analyzed statistically to generate L50 and L10 curves for each loading case. Utilizing the L50 stress-life curves, a map of constant life is obtained, showing a straight-line relationships between mean stress and alternating stress. It is shown that an increase in the tensile mean stress reduces the fatigue lives of gear teeth.

Committee: Ahmet Kahraman Dr. (Advisor); Talbot David Dr. (Committee Member) Subjects: Engineering; Materials Science; Mechanical Engineering; Statistics

MS, University of Cincinnati, 2013, Engineering and Applied Science: Mechanical Engineering

ABSTRACT An experimental study of normal impact of pure liquid droplets on a dry horizontal substrate and their spread-recoil behavior is presented in this thesis. Measurement of the drop spread diameter and liquid film height variaitons during the post-impact spreading process were carried out using a high speed camera (2000 fps) and image processing. To understand the influence of drop size/weight on the spread process, experiments were conducted for a range of drop sizes (0.8lc < D < 2lc) for water, ethylene glycol and propylene glycol for low to moderate Weber numbers (We < 160). A hydrophilic substrate (glass) as well a hydrophobic substrate (PFTE) were employed as the test surfaces. Eight test liquids encompassing a wide range of physical properties are utilized to understand the effect of liquid property on the maximum spread factors. To understand the effect of surface tension, maximum spread factors for liquids with similar viscosity but varying surface tensions are compared. Similarly, the effect of viscosity on maximum spread factors is also presented. For the range of impact velocities, liquid properties and nature of the substrates studied, the influence of drop size on the temporal variations are found to be similar. For the same Weber number, the larger drop size results in higher spread factors and maximum spread values, while no marked variations are observed in terms of the flattening factor. A scaling factor based as a function of the Bond number is shown to capture the effect of dop size on the maximum spread factor. Furthermore, it is observed that the maximum spread factors for all liquids exhibit a power law behavior of the form, ßmax = c1 * We p for We > 10, with each liquid possessing a different slope, p, and c1 value based on its properties. The slope values are found to be a linear function of the adhesive force between the liquid and the hydrophilic surface, while the sessile drop spread and the c1 v (open full item for complete abstract)

Committee: Raj Manglik Ph.D. (Committee Chair); Milind Jog Ph.D. (Committee Member); Seetha Ramaiah Mannava Ph.D. (Committee Member) Subjects: Mechanics

Master of Science (MS), Ohio University, 2004, Civil Engineering (Engineering)

Experimental and numerical investigation of a deeply buried corrugated steel multi plate pipe

Committee: Shad Sargand (Advisor) Subjects: Engineering, Civil

Doctor of Philosophy, Case Western Reserve University, 1993, Electrical Engineering

The recent discovery of high temperature superconductors (HTS) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS results in narrow bandwidths and high patch edge impedances of such antennas. To investigate the performance of superconducting microstrip antennas, three antenna architectures at K and Ka-band frequencies are examined. Super-conducting microstrip antennas that are directly coupled, gap coupled, and electromagnetically coupled to a microstrip transmission line have been designed and fabricated on lanthanum aluminate substrates using YBa2Cu3O7 super-conducting thin films. For each architecture, a single patch antenna and a four element array were fabricated. Measurements from these antennas, including input impedance, bandwidth, patterns, efficiency, and gain are presented. The measured results show useable antennas can be constructed using any of the architectures. All architectures show excellent gain characteristics, with less than 2 dB of total loss in the four element arrays. Although the direct and gap coupled antennas are the simplest antennas to design and fabricate, they suffer from narrow bandwidths. The electromagnetically coupled antenna, on the ot her hand, allows the flexibility of using a low permittivity substrate for the patch radiator while using HTS for the feed network, thus increasing the bandwidth while effectively utilizing the low loss properties of HTS. Each antenna investigated in this research is the first of its kind reported.

Committee: Paul Claspy (Advisor) Subjects:

Master of Science in Mechanical Engineering, University of Toledo, 2013, College of Engineering

Auxetic materials are defined as a structure or material possessing a negative Poisson's ratio where it expands in tension instead of contracts in area. This type of material is pursued in research because such a material has attractive properties including increased indentation and impact resistances along with the ability to conform to a dome-like shape, known as synclastic curvature. Auxetic structures and materials, whether man-made or natural, are usually porous with a low stiffness, such as foam. Though these have potential applications, there are no practical uses, especially in a structural application. One way to utilize the auxetic properties is through either a laminate or a composite in which one of the components, such as the fiber, is auxetic, thus the composite possesses the auxetic behavior. Structurally, sandwich panels can be exploited with an extruded auxetic core. Sandwich structures, or panels, are comprised of two thin skins known as face sheets and a light weight core. The face sheets increase the core's bending stiffness, for the core is usually made of foam or a cellular structure. Recently, folded cores have been examined. Using a cellular core allows water to condense within the cells and makes the sandwich structure heavier; this contradicts the idea of a light weight core. Folded cores were created with channels to allow this condensed liquid to escape the sandwich structure. Also, these cores are easier to manufacture since they are created from folding a single sheet of material instead of having to assemble a cellular structure. The pursuit of composites, mainly sandwich structures, is of high interest, for it is the best route to structurally utilize auxetic behavior. The main approach of this is by using two dimensional extrusions to create cellular cores. This research explores an alternative approach to the auxetic core designs through an examination of origami folded cores. Many folded patterns in origami exhibit auxetic behavio (open full item for complete abstract)

Committee: Lesley Berhan Dr. (Advisor); Matthew Franchetti Dr. (Committee Member); Mohammad Elahinia Dr. (Committee Member); Maria Coleman Dr. (Committee Member) Subjects: Mechanical Engineering