bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Study of the Velocity Profiles in an Incompressible Laminar Flow With Particles Between Two Parallel Plates
Authors: Marín B. Julio C. , Amaya C. Carlos J. , Ayala H. Orlando M. , Ayala Orlando F. , Ayala Manuel
Published: February 2024

This paper presents a two-dimensional numerical study of the velocity profiles of an incompressible laminar flow with particles between two parallel plates. The model is developed using COMSOL Multiphysics 6.0 software based on the finite element method. A laminar water flow is used for the continuous phase, and fluid-particle interaction is established through a bidirectional coupling under a temporal configuration. This study aims at analyzing the fluid-particle interaction dependency on parameters such as the Stokes number (St), the volumetric fraction (αp), and the relative size of particles (RSp), and how varying them affects the development of the boundary layer with particles. Two types of velocity profile graphs are presented, one along lines parallel to the plates and another along lines perpendicular to the plates, both to study how the velocity is affected while varying the parameters mentioned before. Graphs of the velocity difference cases of fluid with particles to the case of fluid alone were developed. Three zones are observed: an acceleration zone, in which velocity increases up to a maximum point (peak); a transition zone, where it starts to decrease and progressively stabilize; and finally, a stable zone, where the fluid flow with particles eventually has the same behavior as the fluid alone flow as the boundary layer with particles develops completely and the interaction of particles with the fluid diminishes. It was observed that particles interfere with the development of the boundary layer, and that the interference increases proportionally with the volumetric fraction of particles (αp), while inversely proportional with the relative particle size (RSp). It was found that the volumetric fraction (αp) and the relative particle size (RSp) have a linear proportionality with fluid velocity difference. It is also shown that as the Stokes number increases, particles react more slowly to the fluid flow, further delaying the boundary layer development. In the velocity difference graph and peak was observed and its location in the channel tends to shift as the Stokes number varies. This peak shift was not observed when varying the volume fractions and/or relative particle size.
Characterizing Drop-Wall Interactions of Engine Fuels at Engine-Relevant Conditions Using Smoothed Particle Hydrodynamics
Authors: Patwary Mohammad F. F. , Isik Doruk , Kong Song-Charng , Mayhew Eric , Kim Kenneth S. , Kweon Chol-Bum M.
Published: February 2024

In an internal combustion engine, interactions of fuel droplets and heated walls can significantly affect the combustion process and engine performance. The formation and characteristics of secondary droplets from drop-wall interactions are functions of various factors such as fuel properties, impact velocity, ambient conditions, and wall temperature. Understanding the impact behavior is of great importance to optimize the distribution of the fuel-air mixture for efficient and clean combustion and to develop a comprehensive spray-wall interaction model. In this study, three-dimensional smoothed particle hydrodynamics (SPH) simulations are performed to investigate the interactions of n-heptane and F-24 droplets with a super-heated surface at atmospheric and elevated pressures over a range of Weber numbers (We). The SPH model is validated using available experimental data. Secondary atomization is characterized by using size distributions of secondary droplets for all cases. In contrast to n-heptane, F-24 results in a narrower droplet size distribution where secondary droplets are mainly clustered in the range of 0 to 7μm, resulting in a smaller mean secondary droplet size. Following these cases, this paper presents qualitative description of the impact process and proposes empirical correlations relating mean secondary droplet size to ambient pressure in the film-boiling regime. Post-impingement vaporization characteristics are also analyzed.
Numerical Investigation on Laminar Forced Convection in Triangular Cross Section Mini Ducts With Nanofluids and Rectangular Ribs
Authors: Buonomo Bernardo , Manca Oronzio , Nardini Sergio
Published: February 2024

In this paper a numerical investigation on laminar forced convection flow of a nanofluid, water-alumina nanoparticles, in a mini duct with triangular cross section is accomplished with the lower heated surface with transversal ribs. A constant and uniform heat flux on the bottom surface of the heat sink is applied and a mixture model approach is employed to simulate the nanofluid flow. The analysis is performed for a three-dimensional combined conductive-convective heat transfer in a square section with triangular duct, at steady state regime. The CFD commercial code Fluent is employed to solve the three-dimensional numerical model by means of a finite volume technique. The investigation is carried out for Reynolds number in the range from 100 to 2000, volumetric concentration of nanoparticles equal to 0% 4% and 6%. Results are presented in terms of temperature and velocity distributions, surface shear stress and heat transfer convective coefficient, Nusselt number and required pumping power profiles for different nanoparticle volume fractions. Comparison with results related to the fluid dynamic and thermal behaviors highlights the enhancement in heat transfer, with respect to the base fluid, due to the presence of nanoparticles.
Numerical Investigation of the Effect of the Inclusion of Turbulators in an Evacuated Tube Solar Collector Air Heat Exchanger
Authors: Olukeye Tiwaloluwa , Gaye Samba , Alshweiki Ali , Tyagi Pawan
Published: February 2024

Homes relying on traditional heating systems such as furnaces, stoves, boilers, and similar mechanisms typically have a common requirement: the use of fossil fuels. Since fossil fuel prices are prone to fluctuations, it is crucial to explore alternative options. In the ongoing transition towards more sustainable solutions, solar energy emerges as an environmentally friendly choice due to its renewable nature. A pivotal device in harnessing solar energy for heating purposes is the solar air heater. This study presents a numerical analysis conducted using the CFD simulation software ANSYS, focusing on the performance characteristics of a pumpless solar room air heater that incorporates sectioning. The aim was to optimize the dimensions, specifically the pitch or distance between the turbulator features, and predict the heat exchanger’s thermal performance by measuring the associated head loss. To validate their findings, the researchers compared the predicted results from the CFD simulation with the calculated results using an Excel solver. Throughout the calculations, the impact of design variations (sectioning the pipe at different lengths relative to head loss) and the Reynolds number on stream aerodynamics and heat exchange processes were considered. The findings revealed a linear relationship between temperature and distance between the turbulators, with the heat-transfer measurements increasing alongside this distance.
Synthesis of Poly-Lactic Acid by Ring Open Polymerization for Biomedical Applications
Authors: Vakati Snehal Reddy , Gacura Matthew , Vanderlaan Gary , Ji Xiaoxu , Chen Longyan , Saber Christine A. , Piovesan Davide
Published: February 2024

Poly-lactic acid (PLA) is a synthetic polymer that has gained popularity as a scaffold due to well-established manufacturing processes, predictable biomaterial properties, and sustained therapeutic release rates. However, it has some drawbacks such as weak mechanical parameters and reduced medicinal delivery efficacy after PLA degradation. The development of synthetic polymers that can release antibiotics and other medicines remains a top research priority. This study proposes a novel approach to produce PLA by converting Brewer’s spent grain (BSG) into lactic acid by bacterial fermentation followed by lactide ring polymerization with a metal catalyst. The elution properties of the PLA polymer are evaluated using modified Kirby-Bauer assays involving the antimicrobial chemotherapeutical, trimethoprim (TMP). Molded PLA polymer disks are impregnated with a known killing concentration of TMP, and the PLA is evaluated as a drug vehicle against TMP-sensitive Escherichia coli. This approach provides a practical means of assessing the polymer’s ability to release antimicrobials, which could be beneficial in exploring new drug-eluting synthetic polymer strategies. Overall, this study highlights the potential of using BSG waste materials to produce valuable biomaterials of medical value with the promise of expanded versatility of synthetic PLA polymers in the field of drug-impregnated tissue grafts.
Cost-Effective Method Using Force Sensors for Chiropractic Teaching
Authors: Shah Iti , Butler Carolyn , Salman Muhammad
Published: February 2024

The popularity of chiropractic medicine has increased in recent times, but the tools required for this field can be expensive, bulky, and impractical. To assist students in this field, various equipment such as pressure-sensing tables and actuators are utilized. However, some of these tools can be ineffective despite indicating the amount and location of pressure applied. To address this issue, a new glove design has been proposed in this paper, which utilizes Force Sensitive Resistor Sensors (FRSs), Raspberry Pi Pico W (Pico), Thonny (IDE) software, and an Analog to Digital converter (ADC) to achieve cost-effectiveness without compromising on efficiency. This research has significant benefits for the teaching of chiropractic mechanisms, improving accuracy and reducing costs. The device can also be used by different species in specific fields, potentially preventing workplace injuries, and enhancing teaching quality in this rapidly growing field.
Applying Heat Shrinking to Minimize Pillow Effect During Incremental Sheet Forming
Authors: Schmaltz Kevin
Published: February 2024

Incremental sheet forming (ISF) is a die-less sheet-forming process that forms the desired final shape by incrementally deforming portions of sheet metal. One of the well-known quality problems with the ISF process is the pillow effect. The pillow effect refers to the undesired deformation of the unformed flat part of the sheet under the compressive residual stresses arising from the surrounding formed parts of the sheet which causes the bumping or buckling of the unformed flat surfaces. While the pillow effect is unavoidable in the ISF process, the formed pillow can be flattened by the shrinking of the material at the buckled area. Shrinkage can eliminate compression and provide a slight tension to regain the flatness of the surface. Among all different metal shrinking methods, heat shrinking has been used effectively by metal workers to shrink and flatten stretched areas on sheet metals. The method can be applied to different metals including steel and aluminum.

This project is an undergraduate ME capstone senior project involving four students in support of the Manufacturing Engineering Technology program: Adrianna Burchett, Talon Harmon, Ashley Kobylinski and Afton Schraml. The goal of this research is to study the effectiveness of the heat-shrinking methods in reversing the pillow effect and increasing the geometrical accuracy of ISF formed products. The value of the work towards the engineering education community lies in the integration of a variety of methods used by the students to study this innovative, real-world problem. The student team had to become familiar with the operation of a FANUC R-2000ic 165F robot to create the ISF parts that heat shrinking would be applied to. The team had to identify a suitable scanner to characterize the surface of the untreated and the heat-treated parts to quantify improvements. The team modeled the deformed original ISF part and created FEA models adding heat stress to numerically predict heat shrinking benefits. The team investigated the analytical equations for the ISF part to guide their experimental investigation of ISF heat shrinking.

This project forced the senior team to locate real-world uses of heat shrinking, to educate themselves in the use of a robotic cell to make the ISF parts, guided by numerical simulations and analytical experimental practices, the team investigated the ability of heat shrinking to minimize the undesirable phenomenon of the pillow effect. Their work provides an example of a successful ME student capstone project and has the potential to contribute to future efforts to improve the ISF process.
The Ultrasonic Testing Approach for In-Situ Monitoring of the Fused Deposition Modeling Process
Authors: Pozhanka Mariya , Flores Celeste , Crosswhite Caleb , Stevens Zane , Vig Aidan , Trudell Noah , Zagrai Andrei
Published: February 2024

Additive manufacturing (AM) is a modern fast-growing technology which allows for the fabrication of parts not possible to fabricate with conventional machining techniques. However, in contrast to conventional manufacturing, AM process often results in products with broad variation of properties. Individual parameters of the printing process and their combinations influence final mechanical properties of the printed material and may result in the internal defects. Therefore, inadequate selection of printing parameters may lead to defects formation, undesirable material properties or to a failure during AM process, and hence wasting time and materials.

Nondestructive evaluation (NDE) techniques could be used to improve the trustworthiness and reliability of the manufacturing process. In this contribution, the approach for enabling real-time NDE for monitoring the material properties of the printed part is suggested. The approach is based on adjustment of the printing process parameters depending on elastic properties monitoring of the material printed. There approach requires collecting the database of dependencies of printing process parameters and elastic properties of the material. Three printing parameters were chosen for this purpose: layer thickness, nozzle temperature, and nozzle speed. Virtual engineering workbench with a visual programming language LabVIEW was proposed. The approach allows for capturing the real-time in-situ sensor data and comparing it to the reference data arrays reflecting the influence of the printing process parameters. Consequently, a direct modification of the parameters during the printing process could be achieved based on the real-time sensor data.
Developing a Low-Cost Instrumented Heat Transfer Apparatus for Measuring Thermal Conductivity Using Steady-State Methods
Authors: Bunt Brandon , Wright Kamau , Davis Benjamin
Published: February 2024

In the present study, a linear heat conduction module (LHCM) was developed and used to measure the thermal conductivity of brass at steady-state. Off-the-shelf components were used to keep costs significantly lower than commercially available LHCM’s. Initial tests show that the present apparatus can be used to accurately measure the thermal conductivity of Brass 360 within 3.79% of literature values. The system is intended for operation to test a range of materials, including solid and porous samples of thermally conductive materials, such as aluminum and brass, as well as less conductive materials. Models and supporting tests help to establish appropriate operating ranges for the LHCM system, while facilitating comparisons and recommendations for future testing of porous and composite media and lower conductivity materials.
The Role of Meditation in Stress Recovery and Performance: An EEG Study
Authors: Ahmed Mohammad H. , Kaya Mehmet , Taebi Amirtaha , Thibbotuwawa Gamage Peshala
Published: February 2024

This study aimed to investigate the effects of meditation on recovery time following a stressor and cognitive performance. Two sessions were performed in this study, one as a control without participants meditating prior to the stress task and one with meditation. EEG signals were recorded from 24 channels and processed using frequency domain analysis to measure power in various frequency bands. Participants for this pilot study were 10 healthy adults between the ages of 18 and 35. Reaction time and response accuracy were used as performance measures during the stressor with slower reaction times indicating lower levels of alertness. Brain activity prior to the stressor was compared with activity following the stress task, and the time needed to return to baseline was observed. The effect of meditation on recovery time and performance was analyzed and a gradual return to baseline values was observed. Recovery time varied among participants, with some taking longer than others to recover but no significant change was observed with meditation. Performance-wise, participants who meditated prior to the stressor had improved reaction time and accuracy when compared to the control group. The results suggest that interventions such as meditation or mindfulness practices may help individuals improve performance, but further research is needed to confirm these findings.
Printability Study of Short Electrospun Nanofiber-Hydrogel Composites
Authors: Yan Karen Chang , Desai Raahi , Griffin Tyler , Sood Taniya
Published: February 2024

Microfluidic devices have been developed for many biomedical applications owning to inherent advantages of miniaturization, integration, cost-effectiveness and high efficiency. Microfabrication-free technology has been used to fabricate microfluidic devices. Our group has developed a hydrogel printing system based on 3D printing technology that enables forming microchannels, which has a potential of incorporating electrospun (ES) fiber in the microchannel via the developed hydrogel printing system. Specifically, polycaprolactone (PCL) was selected owning to biocompatibility, low cost, and suitability of electrospinning. Gelatin was selected as the hydrogel material based on our previous study. Produced ES fiber membranes were plasma treated to increase hydrophilicity, and then shortened via cutting and blending. Microscopic image analysis was conducted to characterize the length and morphology of the short fibers. The shortened fibers subsequently were suspended in absolute ethanol and mixed with gelatin solution to form composite materials for printing. An initial screening method was applied to identify potential composites with varying concentration.
Characterization of Macromolecule Diffusion of Electrospun (ES) Fibers Embedded in Microfluidic Devices
Authors: Yan Karen Chang , Sood Taniya , Desai Raahi , Merritt Michael
Published: February 2024

Electrospun (ES) fibers made of biocompatible polymers have been used as scaffolds in tissue engineering to mimic the fibrous environment found in the extracellular matrix (ECM) of biological tissues. Bioactive macromolecules such as growth factors can be incorporated in the ES fibers via encapsulation and/or surface adsorption, and then released to the surrounding environment gradually via diffusion process. As the release rate is influenced by multitude parameters, it is of great importance to understand how macromolecules diffuse under static and dynamic conditions. Our group has developed a 3D printing based method to embed short fibers in microfluidic devices via hydrogel molding (HGM). Furthermore, fluorescence imaging techniques were developed to study and quantify the molecular transport phenomena. Image analysis was utilized to characterize diffusion behavior of macromolecules adsorbed on the surface of ES short fibers. 10w/v% polycaprolactone (PCL) acetone solution is used to electrospun fibers. The ES fibers are then processed and plasma treated to increase hydrophilicity. Fluourescieneisothiocyanate dextrane (FITC-dextran) with a molecular weight of 70kDa (FD70) is used as a model macromolecule. Samples of short ES fibers are submerged into 0.20 mg/ml FD70 solution for 24 hours and dried subsequently. Submersion studies are conducted for the fiber samples with FD70 adsorbed on the surface. Based on the relationship between the light intensity and the FD70 concentration, the FD70 concentration of submersion fluid is determined as a function of. Static submersion study was conducted for both PCL fiber membrane and short fibers. Experimental data suggested that short fiber samples showed faster diffusion and the FD70 concentration in the submersion fluid reached 0.05mg/ml at 15hours, while the results from the membrane sample showed 0 hours were needed. A dynamic test set up was also developed, which allows further study under various flow conditions.
Design and Fabrication of a Modular, Lightweight, and Portable Upper Limb Exoskeleton for Shoulder and Elbow
Authors: Lacuata Nathanael , O’Dell Brandon , John Anthony , Pelletier Cameron , Jefferson David , Lineberger Richard , Sharifi Mojtaba
Published: February 2024

Individuals with physical disabilities or chronic conditions resulting from afflictions such as strokes or spinal cord injuries are advised to use assistive devices to perform daily activities in everyday life for mobility assistance. Focusing on upper extremity assistance, this work aims to develop an upper limb exoskeleton for shoulder and elbow joints that is lightweight and cost-effective. Accordingly, this assistive device is comfortable and easy to operate in home settings, allowing these individuals to regain independence and making their daily lives and physical rehabilitation easier. This exoskeleton is designed to have adjustable dimensions for all body types and various disabilities or conditions. The proposed design ensures the user’s comfort with the capability of performing different movements within a wide range of motion. The structure of this upper limb exoskeleton was fabricated using lightweight materials such as polyethylene terephthalate glycol (PETG), thermoplastic polyurethane (TPU), aluminum, and carbon fiber sheets. High-torque DC motors (AK80-9 model from T-Motor) have been employed on the back of the trunk segment for actuating the exoskeleton joints. In this configuration, a cable-driven system (including Bowden cables and pulleys) has been used to minimize the inertia and weight of the moving parts. To reduce the overall cost and weight of this upper-limb exoskeleton further, each of the shoulder and elbow joints is only operated by one motor. To accommodate this limitation, a full range of motion is achieved for joints such as the shoulder by utilizing a gimbal-style mechanism, where the actuated joint can be repositioned and locked about a common center of rotation. This design decision makes it possible for the user to perform many different motions with the exoskeleton.
Comparison of Machine Learning Models and Analytical Scaling Law for Predicting Melt-Pool Depth in Laser Powder Bed Fusion (LPBF) Additive Manufacturing
Authors: Bai Feiyang , Arikatla Siva Surya Prakash Reddy , Zhang Nian , Gebre Fisseha L. , Xu Jiajun
Published: February 2024

Laser powder bed fusion (LPBF) is a widely used Additive Manufacturing (AM) process involving a high-powered laser to fuse metal powder and build up successive layers to create complex structures. Process parameter selection significantly impacts the dimensional characteristics of the melt pool morphology, including its depth and width, which is vital to the final print quality. Accurately predicting the melt-pool depth is critical for ensuring the quality of the final product. Various methods for different materials have been investigated, for example, thermal image analysis, analytical methods like scaling law, machine learning, and so on. However, most of the promising results are only studies for one material, and it is not necessarily fully applied to another material.

In this paper, our study involves utilizing machine learning models to make predictions of melt-pool depth in the LPBF process and compare their performance to an analytical approach based on scaling law with Nickel alloys IN625 and IN718. We trained three different machine learning models which are Gaussian Process Regression (GPR), Support Vector Machines (SVM), and Neural Networks (NN), and evaluated their performance using R-squared error and Root Mean Squared Error (RMSE) against the performance of the analytical scaling law. Our results show that the machine learning models outperform the scaling law approach significantly.

This study demonstrates the potential of machine learning for improving the accuracy of melt-pool depth prediction in LPBF and provides insights into the strengths and limitations of different machine learning models for this task.
Design and Development of Low-Temperature Ni Coating Without Plasma Using Atomic Layer Deposition
Authors: Box Garcia David , Brown Hayden , Gebre Fisseha , Dwivedi Vivek , Xu Jiajun
Published: February 2024

Atomic Layer Deposition (ALD) is a promising method for the deposition of thin film coatings on a variety of substrates. ALD is a chemical vapor deposition technique where the film growth rate can be highly controlled. Thin film coatings are present in everyday life, having myriad applications in the optics industry such as anti-reflective coatings. Moreover, many other technological fields like decorative or biomedical coatings benefit from this technology. A novel deposition is proposed utilizing diethylzinc (DEZ) and H2O to form a ZnO adhesion layer, followed by Ni (bis(dimethylamino-2-methyl-2-butoxo) in a vapor state and H2 forming gas to deposit 1–2 nm of uniform Ni. Current methods for the deposition of Ni utilize powdered Ni which must be sublimed and deposited in a plasma environment. Although the precision deposition of nickel is possible with this technique, impurities can be present. The objective of the study is to deposit Ni without plasma, utilizing the lowest possible thermal activation energy. Thickness, surface roughness, and composition are critical to understanding the quality of deposition. By using ellipsometry, thin-film thickness was determined with angstrom-level resolution which showed a growth rate of ∼ 2.2 Å per cycle. Surface roughness utilizing atomic force microscopy (AFM) identified a conformal surface with an average Ra of 0.94266 nm. Scanning electron microscopy (SEM) is used to supplement thickness measurements, investigate the crystalline structure, and generate high-quality images of the deposition.
Experimental Demonstration of a Novel Elastohydrodynamic Seal Concept for sCO2 Turbomachinery
Authors: Hassan Mohammad Fuad , Xu Hanping , Islam Mohammad Towhidul , Cesmeci Sevki , Liu Shuangbiao , Harcrow Aaron , Topu Ali Akbor , Hasan Md Wasif , Henry Jonah , Bunting Joshua , Dewis David , Tang Jing
Published: February 2024

To unlock the maximum ability of supercritical carbon dioxide (sCO2) power cycles, technological readiness must be established on the scale of 10–600 MWe and at the sCO2 temperatures and pressures of 350–700 °C and 20–35 MPa for nuclear industries. One of the major challenges at the component level is the lack of suitable shaft seals in sCO2 operating conditions. So far, all conventional seals are incapable of handling sCO2 pressures and temperatures in one way or another. Hence, we propose an elastohydrodynamic (EHD) high-pressure, high-temperature, and scalable shaft seal for sCO2 cycles. The distinctive mechanism of such an EHD seal provides a self-regulated constriction effect to restrict the flow without significant material contact, thereby minimizing leakage and wear. In this study, we conducted an experimental study to prove the EHD seal concept on a 2” static shaft. The shaft was made from stainless steel, whereas the test seal was made from PTFE. The experiments were performed for 121.25 μm initial clearance, and the operating pressure was increased up to 1.50 MPa. It was observed that the EHD seal throttled the leakage rate successfully. The leakage rate increased to a maximum of 7.33 g/s at around 0.64 MPa before it started to decay to 2.72 g/s at the maximum operating pressure of 1.50 MPa. This unique behavior of the EHD seal could become advantageous for sCO2 turbomachinery, where lower leakage rates are required at high pressure and temperature values.
Stenotic Cervical Spinal Cord and Column Responses Under Whiplash Using a Finite Element Model
Authors: Yoganandan Narayan , Harinathan Balaji , Vedantam Aditya
Published: February 2024

Numerous finite element models of the cervical spine have been developed to study the biomechanics of the osteoligamentous column such as range of motion and vertebral stress; however, the spinal cord is often ignored. Spine degeneration is often attributed to the ageing process. It may lead to stenotic spines that concern clinicians and patients because of the decreased space in the canal and potential for elevated risk of cord and/or column injuries. Using a validated model of the subaxial spinal column, spinal cord was included, and different degrees of stenosis (mild, moderate, and severe) identified in the civilian populations were parametrized. Stenosis was simulated at the most common, C5-C6 level, seen in patients. The column-cord model was subjected to postero-anterior acceleration at the base of the T1 vertebra. Range of motion, disc pressure, and stress and strain within the spinal cord were obtained at the index and superior and inferior adjacent levels of the column and cord. The external metric representing the segmental range of motion were found to be insensitive while intrinsic disc and cord variables were more sensitive, and index level was more affected by stenosis. These findings may influence surgical planning and patient education in personalized medicine.
Impact of Prior Design Experiences on Undergraduate Design Success
Authors: Kado Corey , Murphy Alexander R. , Bohm Matt , Kames Elisabeth
Published: February 2024

Design experiences are a critical component of undergraduate STEM education, as they challenge students both academically and socially. The goal of this study is to investigate how previous design experiences and engineering design self-efficacy impact project outcomes for a Hackathon style design project. This early-phase exploratory study observes first-year students in STEM-focused disciplines as they complete a six-hour ‘Hackathon’ style event. The Hackathon serves as the final requirement for the students’ interdisciplinary cornerstone design course. In this study, student demographics, K-12 prior experiences, and engineering design self-efficacy, were collected to understand how these different factors may influence student success throughout the Hackathon. The project is deemed a ‘Hackathon’ due to the problem-focus task given to the student participants and the variety of STEM skills required to arrive at a successful project outcome and a positive student learning experience.

The results of the study show significant correlation between the students’ prior exposure to design and engineering content before their undergraduate studies. Significant correlations were also observed between design self-efficacy factors and success in the Hackathon (measured through time of completion at various points). These findings have the potential to influence design pedagogy and team assignment criteria for future iterations of this cornerstone course and other curricular content focused on the engineering design process. The results of this study set the foundation for future work aimed at understanding our first-year engineering students’ prior design experiences and preparing them for academic success during undergraduate education. An extension of this work is planned that will facilitate longitudinal comparisons of achievement and progress across a four-year design experience.
Repurposed Desalination Salt: A Low-Cost Thermal Energy Storage Medium
Authors: Theroux Konnor M. , Salerno Christopher N. , Camey Brian C. , Salas Alex , Sephton Tom , Baghaei Lakeh Reza
Published: February 2024

In this techno-economic analysis, a thermal energy storage system that repurposes desalination salt as a storage medium is investigated. The proposed system meets the Department of Energy’s SunShot Initiative goal of $15/kWhth for thermal energy storage (TES). A sensitivity analysis was performed on significant cost factors to determine how to meet this goal while considering a positive financial gain from obtaining the salt from desalination facilities. Based on a previous TEA study, adjustments were made to the costs of labor and material to account for inflation. Nanoparticle additives are considered to enhance thermal conductivity and improve system efficiency. Furthermore, desalination concentrates with lower total dissolved solids (TDS) tends to provide lower TES cost. A ZLD (Zero Liquid Discharge) process was considered to extract the total dissolved solids from the desalination brine and provide an additional gain from the potable water sale. The overall $/kwh results show that the SunShot goal is met using a desalination salt that exhibits solid-to-liquid phase change.
Efficient Inverse Design of Acoustic Metamaterials Using Gradient-Based Optimization
Authors: Gerges Samer , Amirkulova Feruza A. , Samaniego Jovana
Published: February 2024

This work presents an efficient implementation of the inverse design of acoustic metamaterials using the gradient-based optimization (GBO) method. The inverse design is based on an optimization process using the semi-analytical optimization approach by adjusting the radius and position of each scatterer in the non-uniform planar configuration of scatterers of various radii. As an illustration of the method, the application of the GBO method for the design of an acoustic lens is demonstrated. The proposed inverse design method is implemented utilizing the GBO algorithms, such as the sequential quadratic programming (SQP) algorithms and the Julia programming language, which is suitable for large-scale simulations and optimization problems. Jointly they create a synergy that enhances the optimization process. The results are compared against computations performed on MATLAB using the f mincon solver with the SQP algorithms. This paper will present numerical examples of sound localization using random and symmetric non-uniform planar configurations of cylindrical rigid scatterers submerged in water.
A Comparative Classification Study on the Use of Acoustic Emission Signals for Surface Roughness Condition Monitoring in End Milling of Stainless Steel
Authors: Abu-Mahfouz Issam , Banerjee Amit , Rahman Esfakur AHM
Published: February 2024

Surface roughness quality has implications on the functionally, assembly, service life, and appearance of the machined product. Considering the complex nature of metal cutting processes, computer simulation models may not provide the needed accuracy to predict surface conditions under all cutting conditions. Therefore, machine learning (ML) techniques can provide more reliable predication models that are based on real time cutting process sensory data. The implementation of artificial intelligence (AI) techniques in the monitoring of manufacturing processes has been gaining momentum. The focus of this study is to predict the surface roughness using acoustic emissions (AE) signals during the dry end milling of stainless steel. AE sensors have been widely used to monitor the condition of structures and manufacturing processes. Furthermore, acoustic sensors are non-invasive and can be used at any location without disrupting or stopping the machining process. Features extracted from the AE signals are used as surface roughness quality indicators. These features include frequency bands averaged amplitudes, statistical quantities of the wavelet decompositions, raw signal RMS values, and crest factor. In this work, several machine learning algorithms are used to process the extracted AE features for surface roughness characterization. The total AE features are first processed for feature set reduction since many of the features are highly correlated. This is done using both supervised and unsupervised feature reduction and subset selection methods. The features extracted from supervised feature reduction methods are used to train three supervised classifiers — k-nearest neighbor (kNN) classifier, a radial-basis function support vector machine (RBF-SVM), and a random forest (RF) classifier. The reduced feature set from the unsupervised feature reduction methods are used as input to two unsupervised clustering methods — K-Means and DBSCAN. The classifier models are trained using multi-fold cross-validated mix of subsets of the reduced features. In this study we have used ten models using two-fold cross validation for training and validation for the supervised learning methods. The results of supervised classification are compared to unsupervised clustering and are reported for an average of the ten models (or ten runs with distinct initializations of the clustering algorithm), along with a detailed nonparametric testing to verify statistical significance in performance level between pairs of algorithms.
Tension Control in Filament Winding Using Constant Force Mechanisms
Authors: Ye Siwei , Mo Yaru , Ou Haihua , Bi Shun , Johnson Shane
Published: February 2024

The control of fiber tension has a significant impact on the geometrical and structural characteristics of the final product quality in filament winding. Controlling the tension and reducing disturbance in robotic filament winding is a great challenge due to the complex winding interface, sharp turning in trajectory, and fiber mechanics involved. Typical tension control strategies, e.g., rigid actuator or series elastic actuators, require costly electronic components or complex tension feedback control. Alternatively, constant force mechanisms (CFMs) may be incorporated into the filament winding system to control the tension force passively for a fixed displacement range. The objective of this study is to develop a large-stroke constant-force mechanism through design optimization and experimentally study the performance of force control with Proportional-Integral-Derivative (PID) and fuzzy controllers. A 2 × 2 Graph based path topology optimization was developed, and the resulting fixed-fixed beam was out-of-plumb with a slight out-of-straightness imperfection. In the experimental setup of the mock filament winding system, the fiber starts from a motorized feed mandrel, passes through pulleys with mounted tension/position sensors on a CFM array and finally reaches a motorized inlet mandrel. Both a PID controller and a Fuzzy controller were developed to evaluate and compare the performance of: (1) the CFM and rigid actuator systems, and (2) the controller types. The result shows that compared to the rigid actuator system, the CFM actuator system reduces peak tension overshoot by 34.17%∼45.42% and the tension coefficient of variation by 7.14%∼8.40%. In addition, the Fuzzy controller provides greater robustness, i.e., it allows more errors in position while continuing to maintain tension control performance. In conclusion, the CFM control strategy with PID or compatible Fuzzy control presents a great performance advantage over the existing tension control actuator strategies. The application of CFMs shows great potential in various force control in cable-based systems, e.g., vibration mitigation against strong wind in bridge cables, energy absorbing from earthquakes in buildings, elevators, etc.
Development of a LoRaWAN-Enabled Unmanned Aerial System for Autonomous Real-Time Surveillance and Monitoring
Authors: Sunny Manish Edassery , Umesh Pruthviraj , Gangadharan K. V. , Shetty Devdas
Published: February 2024

This research paper proposes a LoRaWAN-enabled Unmanned Aerial System (UAS) for autonomous real-time surveillance and monitoring for agriculture fields. Traditional security measures in agriculture face challenges due to their high costs and labor-intensive nature, especially on large farms. The paper outlines the development of the complete system, explaining each block that forms its components. Additionally, it presents an experiment where a UAS successfully flew to a specific location triggered by motion sensors connected to LoRa nodes as part of surveillance and monitoring of an area. The results demonstrate the system’s effectiveness in real-time monitoring and autonomous operation. By leveraging LoRaWAN technology, this system offers a promising solution to enhance agricultural security and efficiency. The integration of technologies showcased in this research contributes to the field of precision agriculture.
Generative Adversarial Networks Guided Lightweight Design Based on Shakedown Strength Constraint
Authors: Huang Songhua , Zhang Lele , Chen Min , Liu Zhiyuan , Lim Eng Gee
Published: February 2024

Compared to the classically performed elastic limit rule in structural lightweight optimization design, the shakedown analysis can help determine the non-failure external load region which is greater than the elastic limit but less than the plastic limit, without accounting for the loading history. By sacrificing some abundant load-bearing capacity, a lightweight design of the structure can be achieved. Combining the shakedown analysis with parameter optimization can help resolve parameter optimization intervals while considering structural fatigue in complex loading conditions. This approach ultimately translates into solving a max-min optimization problem. However, due to the nonlinear relationship between the shakedown limit and massive design parameters, a rugged ‘performance landscape’ which is considered to be extremely unfriendly will be led through a traditional surrogate model, sometimes it is not even possible to generate. Moreover, the total time-consuming of simulation data acquisition is unacceptable. The current research utilizes Generative Adversarial Networks (GANs) to enrich the surrogate model with shakedown strength boundary constraints. Benefiting from the unsupervised learning feature and the similarity between the generated data and the real data, GANs are able to build relationships in the above optimization problem quickly, which is an innovative and executable technique to the lightweight design under structural strength constraints. The research first presents the shakedown theory and its numerical implementation. Then, a shakedown strength constrained for mass minimization form and the GANs flowchart for solving this problem are built, and a benchmark example is presented to validate the suggested technique. By using this effective workflow combining shakedown theory and GANs to optimize lightweight frame structures, the structure was able to quickly achieve a lighter configuration design while avoiding failure forms like incremental collapse, ratcheting, and alternate plasticity. Furthermore, the method is used to determine an optimal lightweight design for a manned airtight module. The parametric study presented in the paper demonstrated the effectiveness of the proposed method in reducing the total mass of the structure. Moreover, the study highlights the improvement in design performance by allowing redundant shakedown load capacity and reducing material usage.
Investigation of Kinetics of Crystallization From a Concentration Controlled Supersaturated Solution in a Two-Phase Microfluidic System
Authors: Onel Selis , Ahmed Tijani Ahmed , Hatiboglu Anil
Published: February 2024

Solvothermal synthesis of advanced materials with complex metal-organic frameworks, superlattice crystalline structures, or intermediate phases requires precisely controlled thermodynamic and kinetic conditions. Droplet-based microfluidics provide a controlled platform for the investigation of chemical and physical kinetic processes confined in picoliter reactors for faster transfer of heat and mass and uniform distribution of temperature and concentration. We used a transparent thermo-fluidic device on an inverted microscope with a fast camera to observe the solidification kinetics in monodisperse microdroplets of a supersaturated solution in a continuous phase of silicon oil. The precursor solution involved a zirconium chloride salt, organic ligands, and a solvent. We optimized the two-phase flow conditions to control the reactor size. Nucleation experiments were conducted at 50, 80, and 100 °C. The residence time required to start nucleation was identified by a change in color and form in the droplets indicating a phase change. Higher temperatures resulted in shorter residence times due to faster nucleation kinetics. We used an Arrhenius relation to model droplet shrinkage due to dissolution of the solvent in oil and to calculate the concentration of the precursor solution at nucleation. Miniaturization of the reaction environment in microfluidic systems proved to be powerful for better control and observation of phase transitions in supersaturated solutions and in optimizing the precursor recipes towards desired products.
Effect of Miniaturization Using Droplet Based Micro Fluidic Systems on the Synthesis of UiO-66 MOF Nanoparticles
Authors: Onel Selis , Parlak Buse , Korkmaz Gaye , Dilci Elif Gokcen
Published: February 2024

Nanoparticles with metal-organic framework (MOF) structures are emerging advanced materials with exceptional internal structural and external surface properties. Particles with MOF crystalline structure can be synthesized with the conventional solvothermal methods using a metal salt and an organic ligand dissolved in a solvent in proper ratios to prepare a precursor solution. Precise control of the concentration of the precursor solution and the thermodynamic conditions, such as the temperature, pressure, and volume of the reactor, is critical in obtaining the desired MOF structure, but difficult for systems in bulk amounts. Droplet-generating microfluidic devices offer a controlled environment and inherent compartmentalization. Heat and mass transfer is dramatically enhanced at the micro-scale. In this study, we comparatively investigated the synthesis of zirconium(IV)-based UiO-66 nanoparticles using both a macro-scale batch reactor and a droplet-based microfluidic system. The resulting products from both the macro and micro scale systems were analyzed using XRD and SEM. We determined the recipes and the residence times that yielded UiO-66 nanoparticles with a size less than 100 nm at 100 °C. We found that more concentrated precursor solution recipes reduce the time required for nucleation and crystal growth, which is favorable in the microfluidic system.
Design and Development of an Adjustable Constant Force Mechanism
Authors: Johnson Shane , Rehman Tanzeel Ur
Published: February 2024

“Constant force mechanisms (CFMs) are widely used in various applications, including force regulators, surgical graspers, grippers, micro injectors, vibration isolation and constant force actuators. CFMs, designed for a single constant force, necessitate active mechanical control for force adjustability. The objective of this paper is to develop a semi-active, structural controlled adjustable CFM (ACFM) with a large change in constant force. A path based structural optimization is conducted using graphs. A 2 × 2 grid is selected, and nodal locations are perturbed to obtain a large stroke CFM with high quality constant force as defined by the energy similarity index, i.e., ratio of the energy capacity of the CFM to an ideal CFM. The slenderness of the CFM was tuned in order to change the constant force of the mechanism using a parametric study. The parametric study showed a change in constant force, maximum stroke and the quality of constant force as the slenderness was changed. In the experiment using a 2-layer unidirectional fiberglass specimen, slenderness was tuned by modifying a fixed boundary condition location in a fixed-fixed setup. The constant force (CF) was doubled from its value while maintaining a high energy similarity index of 0.9. Compared to mechanisms in the literature, the selected proposed mechanism was found to be 4.1% more compact. In conclusion, semi active control using boundary condition location adjustment in CFM was implemented for the first time to develop an ACFM. The ACFM is ideal for diverse applications including impact attenuation, vibration isolation, and surgical graspers.”