bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study of the Nano-Fin Effect (nFE) During Thin Film Evaporation From Nanopores in Anodic Aluminum Oxide (AAO) Membrane Substrates Integrated With Nano-Thermocouple / Thin Film Thermocouple (TFT) Array
Authors: Shafer Julie , Lee Jonghyun , Thyagarajan Ashok , Banerjee Debjyoti
Published: February 2023

Recent advances in micro/nano-fabrication has enabled the deployment of nanostructured surfaces, nanochannels, and nanoporous membranes for development of new generation thermal management devices with remarkable potential for heat transfer enhancement. Anomalous heat transfer has been reported in studies involving heaters with nanostructured surfaces. For example, nanofins with lower thermal conductivity values can cause higher levels of enhancement in heat flux values, especially during phase change (such as for boiling on heaters with nanostructured surfaces). In addition, confinement of fluid in nanopores can also result in anomalous properties. This is manifest in anomalous production curves during hydraulic fracturing operations in oil and gas applications. A transport model that resolves these conundrums is termed as the “nanoFin Effect (nFE)”.

nFE is governed by interfacial phenomena, i.e., the formation of thermal impedances in parallel circuit configuration, consisting of: (a) interfacial thermal resistance (also known as “Kapitza resistance”); (b) thermal capacitor; and (c) thermal diode (that form at the interface between each nanoparticle and the surface adsorbed thin-film of solvent molecules). nFE (i.e., primarily the interfacial thermal diode effect) also leads to preferential trapping of ions on the surface adsorbed thin film of solvent molecules leading to very high concentration gradients causing drastic reduction in corrosion.

The motivation of this study was to explore nFE during thin film evaporation from nanopores. The methods used in this study include mounting a nano-thermocouple array (also termed as Thin Film Thermocouples or “TFT”) on a hot plate and observing the transient response recorded by the TFT array when a small liquid droplet (of fixed mass or volume) is dispensed on to an anisotropic AAO membrane containing nanopores. In this study, two different pore sizes were explored: 200 nm and 10 nm. The experiments were performed using isopropyl alcohol (IPA) droplets for four different temperature settings of the heated membrane (containing the nanopores).
Introducing Integral Engineering Skillsets to the Diverse Population of Underrepresented Students at the University of the District of Columbia via the NASA Human Exploration Rover Challenge
Authors: Harrigan Voss , Xu Jiajun , Haghani Sasan
Published: February 2023

The University of the District of Columbia (UDC), the only public university in the nation’s capital and a land-grant university, has been participating in the NASA Human Exploration Rover Challenge for the past several years. The teams are asked to design and fabricate a two-person human-powered rover capable of traversing a course designed by NASA to simulate various terrain. The rover requires a significant redesign each year; therefore, these disciplinary benefits and opportunities encouraged the students to form a team in 2022. The team leveraged UDC’s new NASA-funded Center for Advanced Manufacturing in Space Technology & Applied Research (CAM-STAR) and its research facilities to design the rover. This paper introduces the rover competition for 2022 and the UDC team’s new designs using advanced and additive manufacturing. Also, the skill sets learned by the diverse population of the team members are discussed, along with critical engineering techniques using various forms of engineering.
Shape Modeling of Potential Sink Marks for Aesthetic Design of Plastic Parts
Authors: Inui Masatomo , Umezu Nobuyuki
Published: February 2023

Shallow depressions, called sink marks, may form on the surface of plastic parts produced by injection molding. These depressions are caused by partial differences in the amount of shrinkage of plastic parts during the solidification process. The appearance of such depressions in the exterior of the product degrade its aesthetic quality. In this study, we propose a shape modeling technique of possible sink marks. The input data of the method is a polyhedral model of a part. This model is transformed to another polyhedral model of the same shape and whose surface polygons have a sufficiently small size. For each vertex of the part, the amount of shrinkage is determined using the result of the thickness analysis at the vertex of the model. The position of the vertex is then modified according to the shrinkage value to obtain a solid model with shallow depressions on its surface. By properly visualizing the model using the computer graphics technique, it becomes possible for the designer to evaluate the influence of sink marks on the part appearance.
A Closed Loop Pressure Assisted Boiling Point (PABP) Control System for Thermal Fusion Bonding of Thermoplastics
Authors: Dathathreya Kavya , Park Daniel S. , Park Taehyun , Soper Steven A. , Murphy Michael C.
Published: February 2023

An innovative method of thermal fusion bonding (TFB) using a pressure assisted boiling point (PABP) control system was characterized to determine the optimum parameters for bonding thermoplastic components containing microchannels and thin cover sheets. The PABP TFB system enables precise control of the temperature and the pressure boundary conditions by immersing a bag containing the components being bonded in boiling water and varying the vapor pressure. The original system used a human operator to manually adjust a pressure relief valve and maintain the system temperature, which introduces time delays. A closed loop control system was developed to automatically control the temperature in the pressure vessel. Test structure geometries containing microchannels of two depths, 5μm and 10μm, and four different aspect ratios were designed: 1:10, 1:50, 1:100, and 1:200. Microchannels were hot embossed in polymethyl methacrylate (PMMA) using micro-milled brass mold inserts. Results of bonding with the closed loop systems were evaluated. Mean rupture pressures decreased with increasing AR and were higher for shallower channels for the automated closed loop system. For a given aspect ratio, the rupture pressures ranged from 5%–19% higher for 5 mm channels and increased by 5%–10% in 10 mm channels with the automated closed loop system.
Actively Controlled Magnetic Bearing System Using Compliant Mechanism
Authors: Chaudhary Vivek , Pandey Sameer , Khatait Jitendra P. , Mukherjee Sudipto
Published: February 2023

Rotors with speeds more than 20000 rpm, like Flywheel Energy Storage System (FESS), are fully or partially evacuated to reduce drag but have to be geometrically constrained except in the rotation axis. Magnetic bearings are preferred over a rolling element or journal bearings. The high-speed rotor is supported on active magnetic bearings. Though magnetic bearings with multi-axis support are possible, we look at building the support using desired passive compliance along five DOFs and one contactless support using a magnetic field with high stiffness at the set gap. A single DOF active magnetic bearing system is designed to precisely position a shaft along the longitudinal direction. The shaft is supported on a pair of compliant ortho-planar mechanisms at the two ends. The compliant structure is designed to provide bearing support along the radial directions. The position of the shaft along the longitudinal direction is actively controlled using the magnetic bearing system. A two-unit system based on magnetic attraction, one at either end, is designed. A candidate compliant ortho-planar mechanism is designed to support the shaft and fabricated using rapid prototyping. Stresses and bearing stiffness along different axes are calculated and analyzed using FEM. The 3D printed part was used for visualization and tested for compliance in the active magnetic bearing direction. The active magnetic bearing system is modeled. The controller will be optimized for disturbance rejection and minimize excursion around a desired axial location. The developed setup can be used to study and develop multi-axis AMB for high-speed rotating applications.
Assessment of LIDAR Imaging Systems for Autonomous Vehicles in Adverse Weather and Under Dynamic Conditions
Authors: Abdo Jamil , Russell Luke N. , Mills James , Frailey Taylor D. , Chen Genshe
Published: February 2023

One of the main challenges for the safety validation of autonomous driving vehicles lies in the influence of weather phenomena. As each of the main sensors, namely LIDAR, radar, and cameras increases its sensitivity to detect smaller objects faster and hence be able to drive autonomously at higher speeds, the possible influence of environmental perturbations on their perception increases. Those perturbations could cause false positives, confuse self-calibration algorithms and reduce the sensor range. On the other hand, they could constitute a source of valuable information if the dependencies are known and properly characterized to better evaluate and predict road conditions or adapt its operation mode. The main purpose of this work is to evaluate the impact of adverse weather conditions mainly heavy snow on LIDAR sensor performance in dynamic conditions, i.e. moving sensors and moving-target scenarios.
A Dynamic Mode Decomposition Method for Modal Analysis of Human Brain Diagnosis
Authors: Fereydoonpour Mehran , Mclean Jayse , Ziejewski Mariusz , Karami Ghodrat
Published: February 2023

Modal analysis is a strong tool of mechanical diagnosis and behavior of bodies and structures. The method can be employed for human head as a body to recognize its natural frequencies. Brain injury can be destructive around the brain’s resonant frequencies with the external applied loading and motion. Vibrations due to an assault on the head are sent throughout the brain under impacts or high motions. These waves propagate and attenuate at different rates within the brain depending on the magnitude and direction of the impact loading or motion. By conducting modal analysis of the brain and identifying its resonant frequencies we can measure the risk of injury and reduce or possibly even eliminate vibrations in these frequency ranges. This paper employs a finite elements method to simulate the impacts for different impact angles on a human head. A numerical technique based on dynamic mode decomposition (DMD) will be used to extract the modal properties for the brain tissue in regions near the corpus callosum and brain stem. The study aims to identify a frequency range in which the brain is more susceptible to vibration with the end goal of better understanding the brain in the frequency domain and preventing future TBIs. Three modal frequencies were identified with frequency ranges of 44–68Hz, 68–155Hz, and 114–299Hz. It is found that the impact angle, displacement direction, and region of the brain have a significant impact on the modal response of brain tissue during any impact. The study also provides insight into the effects of impact angle, displacement direction, and different regions of the brain.
Physics-Based Filament Adhesion Modeling in Fused Filament Fabrication
Authors: Aniyambeth Shreyas , Malekar Deepak , Özel Tuğrul
Published: February 2023

Material extrusion processes such as fused filament fabrication (FFF) are among the most widely used additive manufacturing (AM) technologies. The fused filament fabrication process consists of simultaneously feeding and melting a filament of polymer material through a computer-controlled liquefier. The material then flows through the nozzle under pressure, which must fully solidify while remaining in extruded shape. Deposited layers are fused together as the melted material quickly solidifies to form layers of a solid 3-D object. The key elements are material feed mechanism, liquefier, print nozzle, build surface and environment. The general applications are production of prototypes during product development phase, short series production runs where tooling cost is high, and parts with high geometrical complexity which cannot be produced by means of conventional manufacturing. Often, time evolution of temperature as recorded by thermography and adhesion behavior of filament are investigated by considering main process parameters, such as filament dimensions and material, sequence of deposition and environment temperature. In this paper, thermal behavior of material extrusion and filament adhesion is analyzed.
Further Insights Into the Timoshenko-Ehrenfest Beam Theory
Authors: Banerjee J. Ranjan , Kennedy David , Elishakoff Isaac
Published: February 2023

In this paper, the theory of a Timoshenko-Ehrenfest beam is revisited and given a new perspective with particular emphasis on the relative significances of the parameters underlying the theory. The investigation is intended to broaden the scope and applicability of the theory. It has been shown that the two parameters that characterise the Timoshenko-Ehrenfest beam theory, namely the rotary inertia and the shear deformation, can be related and hence they can be combined into one parameter when predicting the beam’s free vibration behaviour. A theoretical proof is given that explains why the effect of the shear deformation on the free vibration behaviour of a Timoshenko-Ehrenfest beam for any boundary condition will be always more pronounced than that of the rotary inertia. The range of applicability of the Timoshenko-Ehrenfest beam theory for realistic problems is demonstrated by a set of new curves, which provide considerable insights into the theory.
Review of Thermal-Hydraulic Modeling Methods of Printed Circuit Steam Generators for Small Modular Reactors
Authors: Cho So-Bin , Wang Chengqi , Allen Todd , Sun Xiaodong
Published: February 2023

Small Modular Reactors (SMRs) are promising to address a wide range of energy needs. Steam generator (SG) is usually one of the largest and most expensive components in a nuclear energy system. Therefore, the overall economics of an SMR plant employing a steam Rankine cycle is strongly influenced by its SG selection. Previous case studies conducted at the Idaho National Laboratory, assessing the techno-economic performance of advanced reactors for water desalination and hydrogen production, have mostly focused on reactor system options with conventional U-tube SGs or helical-coil SGs. Incorporating a two-phase Printed Circuit Heat Exchanger (PCHE) as a SG, termed a Printed Circuit Steam Generator (PCSG), has the potential to further improve the plant economics by significantly reducing the system volume through its enhanced compactness. This paper summarizes an ongoing effort to access the thermal-hydraulic performance of a PCSG for SMRs and establishes a reference model using the correlations that have been adopted and benchmarked by the latest PCSG modeling study. Our results suggest that using a one-dimensional (1-D) code for outlet temperature calculations (i.e., the hot and cold sides) and a pressure drop calculation for the single-phase flow (i.e., the hot side) can be as accurate as those in the three-dimensional (3-D) code used in Ocampo’s study in 2020 (typically less than 0.5 % and 7 % differences, respectively). However, it is noted that the calculated pressure drop for the cold side shows as high as 4 % and 25 % of discrepancies between the correlations and the dimension of simulation (i.e., 1-D and 3-D), respectively. The identified ranges of the uncertainties from this inter-model comparison would support the development of PCSG designs for SMRs while urging researchers to develop validated thermal-hydraulic models for PCSG.
Adsorption of Hydrogen Isotopes on Novel Nanomaterials
Authors: Polat Suheyl , Stinebaugh Aaron , Park Jungkyu
Published: February 2023

We investigated the possibility of using various novel nanostructured carbon for control of hydrogen isotopes by exploring the adsorption, reflection, and penetration of hydrogen isotopes using molecular dynamics. Nanometer sized allotropes of nano-carbons have completely changed the research trend in carbon materials, and opened numerous exciting possibilities in many applications. Researchers started to pay attention to carbon nanomaterials when Fullerene C60 was discovered in 1985. The discovery of carbon nanotubes in 1991 and the first isolation of single layer of graphene from graphite in 2004 have encouraged researchers to measure the exciting thermal, electrical, and mechanical properties of these carbon nanomaterials computationally and experimentally. In the present research, we investigate graphene layers and nanostructured carbons with random configurations. The REBO and AIREBO potential are used alongside LAMMPS to simulate tritium interactions with sheets of graphene. Custom MATLAB codes were used to create the graphene structure as well as randomly distribute 100 tritium atoms along a plane above and parallel to the graphene sheet. The tritium atoms are held in place while the graphene sheets undergo multiple stages of equilibration. The velocities of tritium atoms are selected so that incident energies may be 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 eV during a single simulation. Reflection is shown to be the dominant interaction at low incident energy. Adsorption rates increase with increasing incident energy until energies reach 5 eV. After 5 eV, adsorption rates decrease as incident energy increases. At incident energies greater than 5 eV, adsorption rates increase with the number of graphene layers. At low incident energies (< 1 eV), no isotopic effects on interactions are observed since the predominant interaction is derived from the force of π electrons. Simulations were performed with different incident angles of tritium. Adsorption rates are always the highest when tritium atoms travel vertically towards graphene (θ = 0°) while they are the lowest when the angle is the largest (θ = 60°) with only a few exceptions (5 eV and 10 eV). AIREBO potential shows a significant difference in adsorption of tritium on graphene from REBO potential. AIREBO potential consistently showed lower adsorption rates and higher reflection rates when compared to REBO potential. The results obtained in this research study will be used to develop novel nanomaterials that can be employed for tritium control.
Fast and Robust Damage Imaging With a Cascaded Deep Learning Technique
Authors: Tong Junkai , Lin Min , Li Jian , Wang Xiaocen , Chu Guoan , Liu Yang
Published: February 2023

Quantitatively measuring the health status of mechanical structures is a long-standing challenge in industrial fields. For plate structure inspection in tank and pressure vessels, traditional techniques using point by point scan with probes are tedious and time-consuming. Although algorithms like full waveform inversion (FWI) and diffraction tomography (DT) provide solutions to the problems, those methods are slow and suffer from convergence problems. In this article, we provided an effective damage imaging technique using dispersive A0 mode Lamb guided wave and an inversion algorithm called DLIS. The proposed algorithm adopts convolutional neural network (CNN) as first iteration to provide a fast and low-resolution background, and further optimizes the inversion results with descent direction matrix. In this way, the nonlinearity of the problem is effectively decomposed and yields better results. To test the robustness of the proposed method, we generated 1000 samples consists of corrosion defects with various sizes and shapes using 2D acoustic wave modeling. The inversion results prove the feasibility of our approach in plate heath monitoring and inspections. Note that this method also has full potential to be applied in the fast inspection of plates made of composite materials, pipes, geophysical prospecting and medical imaging because all these inverse problems share similar physics.
The Potential and Limitations of Using Geothermal-Sourced Chiller Plants to Eliminate Cooling Towers
Authors: Farag Ahmed , Ahmed Mahmoud , Ookawara Shinichi , Emam Mohamed
Published: February 2023

The purpose of this research is to evaluate the feasibility and performance of a vertical ground source refrigeration system for cooling a typical 7300 m2 office building after replacing cooling towers used for condenser cooling with three different designs of ground heat exchangers. To that end, a three-dimensional, transient, and conjugated finite volume model is developed and simulated to compare the thermo-hydraulic performance of the traditional single U-tube with that of double U-shaped, and spiral-shaped ground heat exchangers at different flow rates. Based on the results, spiral shaped ground heat exchangers outperform other designs, as seen by better heat exchange rates between the fluid and the soil, which translates to a greater temperature reduction of the cooling water. This improvement not only allows for using smaller number of boreholes which saves the construction costs compared to other designs, but it also improves the coefficient of performance of the system by significantly lowering the cooling water temperature flowing back to the condenser when compared to the conventional cooling tower. This approach also eliminates cooling tower water consumption (saves about 14,500 L/day), tower noise, annual maintenance expenses, and costs for periodical cooling tower replacement. The presented findings make a significant contribution to society by offering innovative and sustainable solutions for cost reduction, environmental conservation, and energy efficiency.
Reduced Theories for Thick Shells
Authors: De Rosa Maria Anna , Lippiello Maria , Elishakoff Isaac
Published: February 2023

The present paper is part of a previous research, started in [1] with the proposal to neglect an energetic term in the dynamic analysis of Timoshenko-Ehrenfest beams. The resulting reduced theory turned out to be both simpler and more reliable than the complete, classical, approach. Whereas the original idea was heuristically justified, a sounder variationally consistent theory has been proposed in [2] and, later on, in [3]. Following the suggestion offered in [1–3], we initially describe the classical theory, and subsequently we propose two alternative hypotheses that lead to two differences aspects of the energy terms. Applying the variational approach, two new different boundary problems are deduced, which are direct generalizations of what was done previously. Both theories can be easily specialized for beams and plates. In addition, the theory is also specialized for the case of cylindrical shell.
Investigation of Water Effects on Surface Acoustic Wave Transmission
Authors: Bo Luyu , Li Jiali , Zhang Xinyu , Li Teng , Tian Zhenhua
Published: February 2023

Corrosion is a typical damage type in metallic structures. Free water on metallic structures can gradually lead to corrosion damage. In this study, we investigated free water sensing based on surface acoustic waves (SAWs). The fabricated SAW device consists of two interdigital transducers (IDTs) in a pitch-catch configuration on a lithium niobate (LiNbO3) piezoelectric substrate. Finite element simulations of SAWs generated by IDTs and SAW-droplet interaction were performed. To unveil the effects of a water droplet on SAWs and understand the mechanism of our SAW device, we simulated multiple cases with different volumes of water droplets. The simulation results show that the transmission amplitude gradually decreases with the water volume increase. A proof-of-concept experiment was performed by using a fabricated SAW device to detect a water droplet on the substrate surface. The experimental results show a similar trend as that of the finite element simulations.
Sparse Data Recovery Algorithm Based on BP Neural Network for Ultrasonic Guided Wave Imaging
Authors: Wang Xiaocen , Lin Min , Li Jian , Wang Dingpeng , Liu Yang
Published: February 2023

Ultrasonic guided wave (UGW) imaging quality is limited by the large number of sensors. In this paper, a sparse data recovery algorithm based on back forward (BP) neural network is proposed to solve the problem that the image quality deteriorates with the decrease of the number of sensors. The sparse data from sparse sensor array is up-sampled preprocessing by compressive sensing and then input to the BP neural network to further reduce the recovery error. Numerical results show that the recovery errors reduce from 10−3 and 10−2 to 10−6 for 32 and 16 sensors. After sparse data recovery, the recovered dense data is used for imaging. The average correlation coefficient related to the imaging quality of 32 sensors is improved to the level with 64 sensors. For 16 sensors imaging, the average correlation coefficient is also improved, but the image quality is still slightly reduced compared with 64 sensors.
Evaluation of Fuel Rod Response Using Principal Component Analysis
Authors: Gad-el-Hak Ibrahim , Mureithi Njuki , Karazis Kostas
Published: February 2023

This study pertains to an experimental analysis on the effects of the transverse jet flow geometry on the stability of a 6 × 6 square rod bundle. The experimental work represents a reduced scale fuel assembly subjected to localized cross flow conditions. This type of complex system is typically found in the nuclear industry (pressurized water reactor cores). The goal of the experimental study is to investigate the onset and characterize rod instability as it relates to the intensity and diameter of the jet cross-flow. The rod response was recorded using a high-speed camera in the vibration plane. From image processing, rod vibration amplitudes, and power spectral densities are acquired in both stream-wise and transverse directions. The results indicate that by increasing the jet nozzle diameter ratio, the critical flow velocity is reduced, however, the maximum vibration amplitude in the bundle decreases as the jet diameter ratio increases.

The experimental datasets produced by all three sets of experiments were analyzed by Principal Component Analysis (PCA). The method obtained the orbit plots of the rod bundle undergoing fluid-elastic instability due to the transverse jet flow penetration for each set of experiments. A significant outcome of this research is the relation of acceleration ratio when the nozzle diameter is increased.
Heart Rate Monitoring Using Heart Acoustics
Authors: Mann Aysha , Cook Jadyn , Umar Muneebah , Khalili Fardin , Taebi Amirtahà
Published: February 2023

Cardiovascular diseases (CVDs) are the leading cause of death in the United States. In many cases, CVDs go unnoticed or are diagnosed late, contributing to the high death rate of such diseases. To address this issue, new methods for the early diagnosis of CVDs should be developed. In many medical conditions, heart rate can play an important role as an early indicator of heart diseases. In this pilot study, a heart rate monitoring method based on cardiovascular-induced sounds is investigated. For this purpose, phonocardiography (PCG) signals are measured noninvasively on the body surface of five healthy subjects (21–24 years) using an electronic stethoscope. In addition, electrocardiography (ECG) was used as a gold-standard method of cardiac monitoring. The PCG signals were then post-processed using custom-built algorithms to estimate the subject heart rate. These estimated heart rates were then compared with the heart rate calculated from the ECG signal using the well-known Pan-Tompkins algorithm. Results showed that the heart rate estimations from the acoustic modalities were consistent with those calculated from the gold-standard ECG.
Research on Testing Method and Device of Sensitivity Consistency of Acoustic Emission Sensors
Authors: Zhang Junjiao , Shen Gongtian , Chen Daqing , Yuan Yilin , Shen Yongna
Published: February 2023

The good consistency of acoustic emission sensor sensitivity is the premise to ensure accurate and reliable acoustic emission detection. To facilitate the sensitivity consistency test of acoustic emission sensors, a set of acoustic emission sensor sensitivity consistency test platform was built in this paper. The key parameters of the test device and test conditions are studied through simulation analysis and actual test. The research results show that the pulse signal excitation of the transducer can provide a stable excitation source for the test. The propagation of the acoustic signal in the test block is affected by its diameter and thickness. The acoustic signal propagation is relatively stable in a steel plate with a diameter of 600 mm and a thickness of 8 mm. The test position is related to the size of the test block. This study provides a convenient device and specific method for the sensitivity consistency test of acoustic emission sensors.
Seismic Vibration Attenuation in Shear Buildings Using Nonlinear Energy Sink With Asymmetric Bi-Linear Element
Authors: Motato Eliot
Published: February 2023

Nonlinear Energy Sinks (NES) have gained popularity as passive vibration palliatives because have no preferred natural frequency and can resonate with any mode of the primary structure to which they are attached. Unfortunately, NESs are energy-dependent devices, characterized by energy thresholds where optimal NES design regions can be very close to low effective ones. It is then frequent that even negligible changes in the level of the exciting energy can significantly reduce the performance of previously tuned NES designs. Preliminary studies have shown that NES sensitivity to energy variations can be reduced by adding negative linear stiffness or bistable characteristics. In this work, the robustness of a tuned cubic NES is improved by adding an asymmetric bilinear element. This proposed modified NES is composed by a common cubic NES and a non-constant bilinear stiffness which includes a rope and two linear springs. In this numerical study, the vibration reduction performance of a cubic NESs and a Bilinear NES (BNES) is compared when the absorbers are attached to a three-story shear building structure. The building structure is excited using numerically generated seismic excitations characterized by different energy intensities while the vibration reduction performance of both absorbers are quantified using a specific index.
Investigation of Adsorption, Dissociation, and Hydrogen Diffusion Through V-Ni-Zr Alloys Surface for Hydrogen Purification: First Principle Method
Authors: Opetubo Oriyomi , Oyinbo Sunday Temitope , Oviroh Peter Ozaveshe , Ayotunde Ibitoye , Jen Tien-Chien
Published: February 2023

Hydrogen is an alternative source of fuel to replace fossil fuels. Its byproduct is water, and it is environmentally friendly. To meet the United Nations goal of zero greenhouse gas emissions by 2050, hydrogen generation and purification must be capable of meeting the annual demand for fossil fuel. Vanadium (V) is a potential material to replace Pd-based metals due to its high diffusion. However, due to its high solubility, it suffers severe hydrogen embrittlement. Moreso, alloying with vanadium, such as Nickel (Ni), has lowered its solubility. Hence, this study used the first principle calculation technique based on density functional theory (DFT) to investigate the Hydrogen (H) atom’s adsorption, diffusion, and permeability characteristics on the V-Ni-Zr alloy surface. The hydrogen diffusion path from the hollow site (HS) through the bridge site (BS) to the tetrahedral interstitial site (TS) was investigated. Because of its low activation energy, the material may be employed for H2 storage and purification by changing the alloy composition. Before hydrogen embrittlement occurs, we also look at the diffusion rate over time. This research can be used as a starting point for the experiment.
Motion Capture of the Temporomandibular Joint
Authors: Ahmed Ishfaq , Tiwari Anubhav , Gupta Vijay Kumar
Published: February 2023

Creating a system to analyse human jaw motion is required for people affected with Temporomandibular Disorder. A guiding system is required for creating the rehabilitation steps in such cases. Currently, capturing and estimating the kinematics for the Temporomandibular Joint (TMJ) is difficult due to its intricate position. The capture of the motion by using the stationary camera is a common practice in the available market and gives a reasonable output; However, the setup cost of this instrument setup is too high. Hence, there is a need for a sensor system that is cost-effective and portable in nature. A sensory system is required which can record the kinematics of the motion of the jaw system with the required accuracy. In this paper, a simple system is proposed to capture the required information. The system would require a computer in close vicinity and would rely on a few software for post-processing of the signals obtained from the system. This could be used to reproduce the findings in 3D space and estimate the motion of the Mandible with respect to the skull (temporal bone) in real-time using a microprocessor. The results can also be used for carrying out the dynamic analysis on the TMJ for designing the implant or creating a guiding system for rehabilitation purposes. Benefits of the proposed system over the currently available sensor systems and limitations of the sensor system are discussed in the paper.
Research on the Attenuation Characteristics of Acoustic Emission From Corrosion of Tank Bottom Plate
Authors: Shen Yongna , Shen Gongtian , Gan Pengcheng , Zhang Junjiao , Yuan Yilin
Published: February 2023

In order to clarify the detection range of acoustic emission technology for the tank bottom plate inspection, the attenuation characteristics of AE signal from lead-break on the tank bottom plate are investigated in this work. First the attenuation of AE signals from the lead-break on the upper surface of the tank bottom plate and that from the lead-break on the lower surface of the tank bottom plate are studied and compared when the tank is empty, which indicates that the upper surface corrosion of the tank bottom plate is much easier to detect than the lower surface corrosion. The weld perpendicular to the AE transport direction contributed much to the attenuation of the AE signals from tank floor. Then, the influence of liquid level on the attenuation and transport path of AE signals from tank bottom plate are investigated when water is added into the tank with a level of 10cm and 70cm, respectively. The liquid changes both the attenuation trend and the transport path of AE signals.
Study on the Flow Characteristics of Immiscible Mixtures on Vertical Wall
Authors: Zhang Weilong , Chen Yuxuan , Huang Ying , Ding Yudong , Liao Qiang , Cheng Min
Published: February 2023

The condensation heat transfer phenomenon of immiscible mixed vapors often occurs in industrial environments, such as the waste heat recovery process of raw coal gas, biomass gasification gas and other high-temperature gas. The immiscible mixed vapors can be condensed outside the heat exchange wall and generate an immiscible condensate film attached to the wall, so the flow characteristics of immiscible mixtures condensate have significant effect on the heat transfer performance of the heat exchanger. However, there is currently a lack of research on the flow mechanism of immiscible mixtures outside the wall, and there is no effective ways to control the flow pattern on the wall. Therefore, it is necessary to study the flow characteristics of immiscible mixtures outside the wall. In this work, silicone oil and water were used as immiscible mixtures, and the flow characteristics of immiscible mixtures on the vertical wall under different inlet flow velocities were studied by numerical simulations. The results showed that when the immiscible mixtures flowed to a stable state within all the range of study conditions, the silicone oil phase adhered to the wall in the form of a liquid film, while the water phase existed on the oil film. However, the difference of inlet velocity of immiscible mixtures could affect flow patterns. The immiscible mixtures presented a Film-drop flow pattern on the wall at a low inlet flow velocity, that is the water phase existed on the oil film in the form of droplets. As the inlet flow velocity of the mixtures increased, the immiscible mixtures presented a Film-drop and Channel flow pattern, and water existed on the oil film in the form of droplets and channels. During the flow process of the oil-water immiscible mixtures on the wall, the flow velocity of the oil film was always lower than that of the water phase under the different flow patterns. The oil phase dominated the overall flow velocity of the mixtures, and the overall fluidity of the mixtures liquid film could be increased by improving the flow velocity of oil phase. In addition, the flow of the water phase on the oil film could improve the flow velocity of the oil film, increased the shear stress of the oil-phase interface and disturbed the thickness of the oil film. The results can provide reference for the flow characteristics of immiscible condensate film on the wall surface.
Electrically Assisted Stamping
Authors: Garde Shubham , Patil Ranveer , Grimm Tyler , Mears Laine
Published: February 2023

The conventional stamping manufacturing process has certain limitations that need to be considered throughout the product design process, including the thickness of the blank, geometry of the product, and the drawing force. If the limitations are not considered during the design and manufacturing, they become defects such as wrinkles, excessive thinning, rupture, and spring back. The outcome of the defects is an increase in costs, rework, pre-processing of material (Heat Treatment), and the most important factor, time. To overcome defects, standard alternatives are changing the material composition, blank thickness, or the product design. This research aims to reduce the defects by keeping the design and the material the same as considered during the design phase. Electrically assisted manufacturing is used in the stamping process to eliminate defects. Electrically Assisted Manufacturing has been proven successful in increasing the workability of the workpiece. In this method, controlled electricity passes through the workpiece, blank holder, or the dies during the manufacturing process, which heat the blank. 5052-H32 Aluminium with a thickness of 0.5 mm was used for this study. Previous research indicates that this EAM technique can be used in forging, which is called Electrically Assisted Forging, to improve the formability of the workpiece. This research provides insights into the implementation of Electrically Assisted Forging in the stamping process. In the Electrically Assisted Stamping process, the heat produced due to electricity will temporarily change the material properties and increase its elasticity. Once the temporary elastic limit is achieved, the stamping process will begin. The current flow in pulses will continue until the stamping is completed. The method proposed in this paper considered three important parameters; the amplitude of the current, current holding time, and feed rate of the stamping machine. These parameters were used with different combinations during the testing. Using the data generated of drawing force from the Instron machine was used to plot different types of comparison graphs, which ultimately resulted in direct relation between current and drawing force.
Microstructure and Mechanical Properties of Inconel 718 / Yttria-Stabilized Zirconia (YSZ) Metal Matrix Composite Coating Produced by Laser Directed Energy Deposition Technique
Authors: Ghosh Gourhari , Jain Prakhar , Saigal Anil , Singh Ramesh
Published: February 2023

Metal matrix composites (MMCs) possess a favorable combinations of mechanical, thermal, physical and metallurgical properties which can be engineered by controlling composition, concentration, size and dispersion of the ceramic particles in the metallic matrix. Laser directed energy deposition (DED) technique has the ability to fabricate MMC coatings with good mechanical properties and sound metallurgical bonding. Owing to those beneficial aspects, LDED has become one of the most important fabrication techniques of MMC. Despite of immense applications of MMCs, there has been very limited research work reported in the literature regarding the development of MMC coatings. In the present study, Inconel 718/Yttria-stabilized zirconia (YSZ) MMC coating is deposited on the H13 steel substrate via laser DED process. This MMC can find its application as ultra-high strength thermal barrier coatings in aerospace, power generation, defense equipment manufacturing and die/mold making industries. Three types of MMCs, Inconel-1 wt. % YSZ, Inconel-2 wt. % YSZ, and Inconel-3 wt. % YSZ are fabricated in order to assess the effect of YSZ weight percentage on the microstructure and mechanical properties (i.e., micro-hardness and porosity) of the MMC. Based on the mechanical properties and microstructural study, the optimum amount of YSZ in MMC is determined and it is observed that Inconel-1 wt. % YSZ composite coating exhibits better mechanical (i.e., hardness = 495 ± 7 HV, and porosity = 4 %) and metallurgical properties.
Exergy Analysis of Photovoltaics Coupled With Electrochemical Energy Storage for Lunar Power Applications
Authors: Dyer Phillip , Smith Griffin , Nelson George
Published: February 2023

Any inhabited base on the moon would require significant resources and power. Due to the high cost of delivering materials to the lunar surface, care must be taken to optimize energy storage and delivery systems. An exergy-based analysis of power generation systems based on a photovoltaic (PV) array coupled with energy storage is conducted. Exergy destruction rates are calculated through quasi-steady state energy and exergy balances, while exergy efficiencies for systems and subsystems are also quantified.

The power system configurations analyzed include a PV array coupled with lithium-ion battery (LIB) energy storage and a PV array coupled with regenerative fuel cell (RFC) energy storage. Influence of parameters such as lunar latitude, size, and transient power demand are discussed. In both cases considered, the PV array dominates exergy performance of the overall system. Compared to the RFC, the LIB exhibits a slightly higher system exergy efficiency. Higher system efficiencies are observed during nighttime operation due to efficient discharge of energy storage. Daytime system efficiencies are reduced significantly by radiative heat loss from the solar array. Both configurations experience slightly better exergy efficiencies at lower lunar latitudes, closer to the equator.
Exergy Analysis of Kilopower Nuclear Reactor Systems for Lunar Power Applications
Authors: Smith Griffin , Dyer Phillip , Nelson George
Published: February 2023

Extended human exploration of the Moon requires power and in situ resource utilization (ISRU) capabilities to sustain human life. Meeting this need entails a complex systems integration task that needs physics-based models to support decision making. Exergy analysis includes the effects of both the first and second law of thermodynamics, accounting for irreversible processes and quantifying the useful work that can be extracted from a system. It therefore provides a tool for assessing the performance of diverse systems with consistent metrics that facilitate systems integration. Lunar power and ISRU systems are examples of such complex systems. An exergy-based analysis of the Kilopower Reactor Using Stirling Technology (KRUSTY) power generation system is conducted to assess overall KRUSTY performance. KRUSTY, a part of the Kilopower project, is a nuclear fission and Stirling converter power generation system intended for use in space, with the primary focus on generating power for a lunar base.

Daytime exergy efficiency for the KRUSTY system is generally higher than nighttime efficiency due to coupling with the lunar surface temperature. The presented results show that the KRUSTY integrated system efficiency is greater than alternate photovoltaic-based power generation schemes for lunar exploration in most use cases analyzed. This improved performance is due to reduced surface area and radiative forcing of the KRUSTY system during daytime operation. Results also indicate higher exergy efficiency at colder ambient temperatures, allowing transient power draw cases to be created which maximize exergy efficiency by biasing towards nighttime operation.
Improving Self-Efficacy of Financially Disadvantaged Students via Autonomous Design and Build Project
Authors: Chumley Maxwell , Choudhuri Shabbir , Plotkowski Paul , Manoharan Sanjivan
Published: February 2023

The attrition rate at the undergraduate level for STEM fields is a disappointing 48%, and this is even higher for low-income students. Approximately only 11% of students who identify as low-income earn an undergraduate degree within six years, while 58% of students from higher income backgrounds earn their undergraduate degree within the same timeframe. The high attrition rates coupled with the already existing low enrollment is adversely affecting the country’s economy as the supply of degreed professionals is not keeping up with demand. The academic persistence of a student is a critical factor in determining if a student decides to remain in a certain major or not. Researchers have concluded that enhancing the self-efficacy of a student results improves academic persistence which may positively influence retention. This study investigates the effect of autonomous, project-based learning on self-efficacy for 15 financially disadvantaged students. The learning experience was constructed such that all four sources of self-efficacy viz. mastery experience, vicarious experience, social persuasions, and physiological states were incorporated. Results indicate that the experience had a positive effect on the students’ perceived self-efficacy. Each student believed that these played a major role in the success of the project and that their success was very much deserved.
An Experiential Design Thinking Course for Freshmen Mechanical Engineering Students
Authors: Condoor Sridhar S. , Gorlewicz Jenna L.
Published: February 2023

Design is at the core of engineering. Therefore, exposing students to design helps them realize the purpose of engineering, motivates them to see the relevance of learning, and pushes them to higher achievement levels. In addition, experiential learning practices, and new design methods, including design thinking, are reshaping design courses. After carefully considering trends in design theory and practice, we restructured our first-year design experience for mechanical engineering students at Saint Louis University. The paper outlines the overall structure of this innovative course. The course is structured around projects, while activity-based lectures provide the necessary background to execute them. In these projects, students identify customer needs and create, develop, test, and refine innovative concepts with a win-win value proposition for the stakeholders. This paper details the projects and lecture topics to help others develop and implement similar courses. Further, based on the survey of students and external evaluators, the value proposition is the most challenging aspect to learn and incorporate into the project.