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Item An exact analytical solution for dynamic loads generated by imperfect lubricated journal bearings in multibody systems(Springer Science and Business Media B.V., 2024) Alshaer, Bassam J.; Lankarani, Hamid M.This work presents a precise analytical solution of the Reynolds equation governing the lubrication of journal bearings, this solution is valid for either an infinitely long or an infinitely short bearing, based on the side leakage condition applied. The pressure distribution solution is analytically integrated to obtain the forces generated by the lubricant in supporting external dynamic loads in imperfect journal bearings joints. The analytical solution for both the pressure distribution and the forces generated by the lubricant has been corroborated through numerical validation. This solution was implemented on two distinct multibody mechanical systems: one comprising two bodies interconnected via a lubricated imperfect journal bearing, and the other being the conventional crank-slider mechanism with a lubricated imperfect joint. The outcomes are demonstrated for both long and short journal bearings. The results indicate that an increase in side leakage diminishes the pressure at the ends of the joints and amplifies the axial pressure gradient, which, in turn, elevates the eccentricity required to generate sufficient hydrodynamic forces from the lubricant to support the external load. When exposed to identical external dynamic loading, the central axis of a short journal bearing delineates a trajectory that manifests a pronounced lubricant force overshoot. This phenomenon arises from the diminished viscous damping in short journal bearings, attributable to increased side leakage, in contrast to their long journal bearing counterparts. © The Author(s), under exclusive licence to Springer Nature B.V. 2024.Item Fast and affordable detection of PKU disease using iron (III) chloride-based solutions and porous PCL biosensors at higher prediction rates(Springer Nature, 2024) Gattu, Dileep Kumar Reddy; Kaybal, Halil Burak; Asmatulu, RamazanPhenylketonuria (PKU), a prevalent genetic metabolic disorder, poses substantial diagnostic and treatment challenges globally. Current treatments primarily revolve around strict dietary management, necessitating lifelong commitment and frequent monitoring of phenylalanine (Phe) levels in the body. This study introduces an innovative diagnostic approach utilizing iron (III) chloride solution and highly porous polycaprolactone (PCL)-based solid biosensors for cost-effective, user-friendly detection of L-phenylalanine (L-Phe) in urine, which reflects systemic Phe levels. These biosensors operate through colorimetric changes, quantified using red, green, and blue (RGB), hue, saturation, and lightness (HSL), and cyan, magenta, yellow and black (CMYK) color models, to determine the concentrations of Phe in urine when incorporated with iron (III) chloride. Laboratory tests confirmed that the proposed iron chloride-based liquid and solid sensors are fast, sensitive, specific, and reliable depending on the Phe concentrations. This method promises to simplify home-based monitoring, providing a real-time, low-cost alternative to traditional blood tests, thereby potentially improving patient compliance and outcomes in managing PKU disease. The findings emphasize the potential use of the liquid and PCL-based biosensors in bridging gaps in access to essential diagnostic services for PKU patients. © This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply 2024.Item Experimental demonstration and characterization of a ceramic sintered wick heat pipe evaporator(American Institute of Aeronautics and Astronautics Inc, AIAA, 2023) Sixel, William R.; Kaviany, Massoud; Hwang, Gisuk; Kelvin Egbo, MunonyediAs electrified aircraft propulsion (EAP) matures and power electronics, electric machines, and batteries achieve higher power density, the thermal management of these devices becomes ever more critical. In this paper, a heat pipe made from a dielectric ceramic material is proposed, which enables its use in the thermal management of a high frequency filter inductor for an EAP power electronics application. The manufacturing process for the sintered powder wick was developed and its performance characterized. The heat pipe is further experimentally demonstrated via an open evaporator test and shown to behave analogous to a constant conductance heat pipe. © 2023, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.Item Machine learning applications for electrospun nanofibers: A review(Springer, 2024) Subeshan, Balakrishnan; Atayo, Asonganyi; Asmatulu, EylemElectrospun nanofibers have gained prominence as a versatile material, with applications spanning tissue engineering, drug delivery, energy storage, filtration, sensors, and textiles. Their unique properties, including high surface area, permeability, tunable porosity, low basic weight, and mechanical flexibility, alongside adjustable fiber diameter distribution and modifiable wettability, make them highly desirable across diverse fields. However, optimizing the properties of electrospun nanofibers to meet specific requirements has proven to be a challenging endeavor. The electrospinning process is inherently complex and influenced by numerous variables, including applied voltage, polymer concentration, solution concentration, solution flow rate, molecular weight of the polymer, and needle-to-collector distance. This complexity often results in variations in the properties of electrospun nanofibers, making it difficult to achieve the desired characteristics consistently. Traditional trial-and-error approaches to parameter optimization have been time-consuming and costly, and they lack the precision necessary to address these challenges effectively. In recent years, the convergence of materials science and machine learning (ML) has offered a transformative approach to electrospinning. By harnessing the power of ML algorithms, scientists and researchers can navigate the intricate parameter space of electrospinning more efficiently, bypassing the need for extensive trial-and-error experimentation. This transformative approach holds the potential to significantly reduce the time and resources invested in producing electrospun nanofibers with specific properties for a wide range of applications. Herein, we provide an in-depth analysis of current work that leverages ML to obtain the target properties of electrospun nanofibers. By examining current work, we explore the intersection of electrospinning and ML, shedding light on advancements, challenges, and future directions. This comprehensive analysis not only highlights the potential of ML in optimizing electrospinning processes but also provides valuable insights into the evolving landscape, paving the way for innovative and precisely engineered electrospun nanofibers to meet the target properties for various applications. Graphical abstract: (Figure presented.) © The Author(s) 2024.Item Enhancing the coating durability and electrical stability of fiber composites with SPEEK/PEDOT:PSS permanent coatings: A novel approach(Elsevier Ltd, 2024) Duzcukoglu, Hayrettin; Kaybal, Halil Burak; Asmatulu, RamazanThis study focuses for the first time on the investigation of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) permanent coatings on composite surfaces to enhance the electrical and surface properties of fiber-reinforced composite materials, particularly those commonly used in the aerospace sector, such as Kevlar® (aramid), carbon (C), and glass fiber-reinforced composites. One significant challenge encountered is the weak adhesion property between PEDOT:PSS and the composite surface, which poses some difficulties in coating durability in harsh environmental conditions. The resulting material comprises a three-component structure, consisting of composite surface modifications, PEDOT:PSS coating, and sulfonated poly(ether ketone) (SPEEK) primer. To address the primary issues of adhesion, delamination, stability, and electrical conductivity, this study adopts a novel approach to improve the permanence of PEDOT:PSS coatings on composite surfaces by utilizing a SPEEK primer under ultraviolet (UV) light exposure, deionized (DI) water, saltwater, and acidic environments. Tape-peeling and cross-cut adhesion tape tests were employed to evaluate the coating durability, while optical microscopic observations, water contact angle (WCA), and Fourier-transform infrared (FTIR) spectroscopy analyses assess physical, chemical, and physicochemical property changes. Test results indicated that the SPEEK/PEDOT:PSS-coated composite surfaces exhibited enhanced electrical conductivity, stability, and permanent adhesion properties. Overall, this study contributes to the development of next-generation materials for various industries (aviation, defense, energy, and manufacturing) by offering a promising solution to improve electrical, adhesion, and other surface properties in composite materials. © 2024