bluuebunny/crossref_metadata_2025 huggingface dataset:
Metal Transfer Behavior and Droplet Characteristics of High-Frequency Induction Heating System Towards the Development of Additive Manufacturing Process
Authors: Prasad Avadh Kishore , Bag Swarup , Kapil Sajan , Amin M. Ruhul
Published: February 2024

The induction heating-based wire-feed additive manufacturing (IH-WAM) process is a novel heat source metal depositing process where the metal wire feeds continuously through the induction coil to achieve the desired deposited bead; hence the temperature profile change in the wire due to wire movement must consider for precise results. The present work aims to find the optimized wire feed velocity that transfers sufficient thermal energy to the substrate in less time to develop an IH-WAM process. A 2D coupled electromagnetic, transient thermal, and fluid model is established to study the temperature generation on the moving wire and molten liquid metal with a velocity field. An optimized coil geometry (helical pancake) with 550 A coil current, 353 kHz frequency, and 4 mm coupling distance generates a high-frequency magnetic field. The simulated results suggest that the wire feed velocity of more than 0.015 m/s can not produce a liquid state towards the wire core. The wire feed velocity of 0.012 m/s generates sufficient temperature in the wire. It converts the complete wire diameter into liquid form and supplies the liquid metal having adequate temperature to the substrate. The maximum velocity of the liquid molten metal is found to be 0.22 m/s. It is observed that there is a significant temperature difference of 87 K when the wire is supplied at a velocity of 0.012 m/s compared to the stationary model. Hence the developed model predicts the temperature profile accurately for the IH-WAM process. The numerical results are compared with experimental results obtained from the independent literature. The developed model predicts the wire feed velocity that transfers sufficient deposition temperature to the substrate.
Industry Certification in Simulation Technology As a Part of the Lecture Course
Authors: Milanovic Ivana , Kumar Sunil , Eppes Tom A. , Goparaju Kalyan
Published: February 2024

This work aims to demonstrate one of the pathways in which industry certification in simulation technology can be a part of the lecture course. We explore the intersection between the rigorous theoretical approach to technical topics and the educational method that brings digital engineering into the curriculum. The objective is to improve student readiness for entry into the workforce by better integrating ‘theoretical’ and ‘application-oriented’ approaches to learning.

Industry certifications verify professional competence in tandem with a professional degree or work experience. The certification is typically a document stating that an individual was trained and prepared to meet a specific set of criteria. This document is awarded after passing the assessment administered by a recognized credentialing entity. The Ansys Associate Certification in simulation technology with Fluent as the software was successfully implemented in the three-credit lecture course. While students were assigned simulation projects from the beginning of the semester, the certification was conducted in two segments, simulations and theory, close to the end of the semester. First, the industry partner described the problem that required students to perform a simulation and respond to a given set of questions within a week. Upon the successful completion of this task, participants had to do one more simulation challenge. Finally, students had to pass an in-class exam on the material. The certification outcome (pass/no pass) did not influence the final grade for the course.

Our study builds upon the authors’ previous work on the use of simulations in lecture courses and course sequences. We introduce simulation assignments in addition to the classical pencil & paper assignments, without teaching or requiring prior knowledge of finite element analysis and computational fluid dynamics concepts. This educational method relies on the flexible learning space supported by an online learning management system and incorporates inquiry-based learning. Computational tools are used outside the classroom, while the experiences, competencies, and skills are brought back to the classroom. This approach can be replicated in any science or engineering curriculum with significant benefits such as: (1) improving students’ ability to translate mathematical answers into physical interpretations and translate physical situations into the correct mathematical descriptions, (2) increasing the time students invest in studying, and (3) providing students with an opportunity to earn an industry-recognized certification in simulation technology as a part of their coursework.

The concept of integrated ‘analog’ and ‘digital’ learning and its results are illustrated with qualitative and quantitative evidence. Qualitative data provide samples of student work and testimonials, while quantitative assessments include grades, surveys, and course evaluations.
Failure Analysis and Redesign of a 14th to 15th Century Replica Cannon Mount
Authors: Barrow Luke , Helminiak Nathaniel
Published: February 2024

Historians have noted that 15th century and similarly dated black powder mixtures do not operate optimally in modern cannon systems. They have posited that black power mixtures may have been optimized to work with cannons of the same era. To test this hypothesis, a replica 4 in bore cannon was produced and a wooden mount was constructed. During testing, the mount suffered catastrophic failure. A subsequent steel mounting system underwent significant plastic deformation. Examination of projectile-cannon response was conducted with images from the steel mount test utilizing digital image correlation (DIC) within MATLAB.

The project began by employing analytical equations paired with DIC from previous shots to determine rough estimates for the forces experienced by the mount. Boundary conditions approximating sandbags on the original mount were found to have significant effect on structural response. Numerical models were then generated based on the original design. Finite Element Analysis (FEA) within SolidWorks revealed Von Misses stresses and deformation which matched previous experimental observations. As expected, the deformation of the original physical steel cannon mount matched the numerical model, occurring in areas above the yield strength of steel.

A series of design alternatives were examined, with a final design produced to prevent plastic failure mode and satisfy sponsor requirements. Through multiple rounds of optimization, the strength of the original design was increased. Improvements to the cannon mount anchoring to the soil better mimicked FEA boundary conditions. After assembly, the design was analyzed by DIC after live fire testing.
Introduction on Vibration Reproduction of Non-Strengthen Member by Real-Time Hybrid Testing
Authors: Kawaguchi Masataka , Shimada Kenshiro , Takeuchi Yugo , Tanaka Kazuto , Watanabe Kimitaka
Published: February 2024

Industrial vehicles such as construction machineries are exposed to severe vibration during actual work, which causes structural damages. Currently, vibration endurance testing for non-strengthen members such as doors and covers, requires the assembly of vehicle to reproduce vibration correctly, but it requires a great deal of labor and cost to build vehicle with them on shake table. On the other hand, real-time hybrid tests (RTHT), combining numerical simulation and test, are expected to reduce the cost of endurance test. However, some previous studies have shown that the application of RTHT is limited within large structures, because it could be difficult to apply it to light structure whose natural frequencies are higher.

Therefore, as a basic investigation of RTHT for non-strengthen members, on this study, some system simulations have been conducted using voice coil motor (VCM) as actuator, which is compact and capable of high-speed response. At first, the idea to reproduce their vibration by replacing supporting structure with control system, i.e. pseudo system, has been proposed. Next, vibration simulation with control system has been conducted to confirm the availability of RTHT to reproduce vibration. As the result, it has been verified that VCM could be used as suitable actuator, and that its RTHT system with phase-lead control could reproduce vibration stably of non-strengthen members.
Evaluating the Performance of Dry and Spray-Assisted Cooling Methods for Industrial Thermal Management Through Modeling and Experimental Data Validation
Authors: Jones Spencer , Languri Ethan
Published: February 2024

Industrial sites generate heat through space conditioning requirements and various manufacturing processes. Traditionally, this heat is removed by an evaporative cooling tower, but with many areas around the world suffering from water scarcity, the water used to satisfy these heat rejection requirements may not be available in the near future. Dry cooling is an alternative that could satisfy some evaporative cooling needs. Before now, analysis of the performance of a dry cooler has been difficult. For this reason, a program to analyze performance and improvements is developed for dry and spray-assisted cooling. Using basic heat transfer models in tandem with average, site-specific weather conditions, the model can predict the energy usage required to achieve a user-defined operation schedule. Dry cooling is known as a mechanism for heat rejection with a relatively low capacity, so for some industrial sites, dry cooling alone is not satisfactory and they must couple their dry cooler with evaporative spray cooling. The spray pre-cools the air as it passes over the heat exchanger, but does so in a more efficient way than an evaporative cooling tower.

With measured values from an industrial site, a retrofit project for the installation of a variable speed drive (VSD) on the fan can be analyzed to show the effectiveness and estimated energy savings. This program was developed with a focus on ease-of-use for the users and operators of such cooling systems to provide them with a better understanding of their system and potential energy and cost savings due to such projects.

Now dry and spray assisted cooling analysis is done in conjunction with average, site-specific weather data from Typical Meteorological Year 3 (TMY 3) weather data. This provides hourly averages for an entire year or 8,760 hours, based on the average weather conditions as recorded over three years. This allows for the program to provide a reliable, average performance results over an entire year of operation.

The program uses these 8,760 data points to predict the performance and energy usage of the dry or spray-assisted coolers over all hours of a year and provides the results in an easy to understand way. The results will show the user the annual energy usage, water usage, and cost, while highlighting data points where the defined operation schedule is not satisfied. By improving dry/spray-cooling owners and operators’ ability to understand their cooling system, the program aims to significantly diminish the energy and water usage of such systems and increasing confidence for industrial sites to exchange evaporative cooling for more water efficient dry or spray-assisted cooling.
A Comparative Study of the Long-Term Performance of Vertical U-Tube Borehole Heat Exchanger and Foundation Piles in a Cold Climate
Authors: Adebayo Philip , Beragama Jathunge Charaka , Shor Roman , Mohamad Abdulmajeed , Mwesigye Aggrey
Published: February 2024

Ground source heat pumps (GSHP) are gaining traction as a reliable and environmentally friendly solution for space heating and cooling. In cold climates, like Canada, heating loads are greater than cooling loads, which makes the amount of heat extracted from the ground each year greater than heat injected back. This causes a soil temperature decline, gradual performance reduction and possibly eventual failure. The associated ground thermal imbalance and high initial cost of a GSHP are a major challenge to wider adoption of this clean energy technology. This study aims to evaluate and compare the long-term thermal performance of the foundation pile and the conventional borehole heat exchanger of a ground source heat pump system for space heating and cooling in a residential building in Calgary, Canada. A meticulously validated and verified computational fluid dynamics model was developed using Ansys Fluent. The validated model was extended and coupled with transient building energy loads obtained from OpenStudio/EnergyPlus through a developed user defined function. The foundation pile, 20 m deep, 0.139 m diameter with enhanced bentonite grout as backfill material and vertical borehole heat exchanger, 150 m deep, 150 mm diameter were examined for a period of 5 years. The results show that the borehole heat exchanger handling 1.5 tons of the total building load gives better performance with the highest average cooling COP of 3.37 at the end of the 5th year with minimal impact on the ground temperature.
On the Reduction of the HVAC Noise Using Active and Passive Noise Control Technologies
Authors: Shige Koki , Terashima Osamu
Published: February 2024

In this study, an attempt to reduce the flow-induced noise generated by heating, ventilation, and air-conditioning (HVAC) systems for commercial electric vehicles using feedback active noise control with real-time filter update in frequency domain was conducted to improve the quietness of a running vehicle. In active noise control (ANC), the frequency-domain gradient descent algorithms (FDGD) to adapt the noises were studied. In the experiment, air conditioner noise was measured using a microphone placed at the driver’s left ear and referenced by a microphone at a map lamp for ANC. Results shows that in the 1/3-octave band, the sound pressure level in driver’s left ear was 7.2 dB smaller at maximum when the control was operated. The effective frequency bands were between 50 and 150 Hz. Its reduction was 4.7 dB on average. In passive noise control (PNC), the focus was on porous materials inspired by the properties of bird feathers with a closed structure, which have high sound permeability but low fluid permeability. The overall value of noise reduction at the ear position of the driver was approximately 5 dB; this was achieved by attaching this porous material to a part of the HVAC system of a commercial electric vehicle and ventilating it. Furthermore, the noise reduction measured from the velocity fields at the airflow exit of the HVAC system was caused by the change in the magnitude of the velocity fluctuation in the flow field.
Line Waves in Elastic Metamaterials
Authors: Dwivedi Ankur , Horsley Simon A. R.
Published: February 2024

Line modes have been recently identified in electromagnetic materials: one dimensional waves bound to surfaces with opposite sign of permittivity and permeability. Here, we communicate analogous elastic line waves in mechanical metamaterials, using both analytical theory and the finite element method. We show analytically that a pure shear line mode exists at the boundary of an elastic material, at a junction between a region where the boundary is pinned in the plane, and out of the plane. We also numerically investigate the properties of line waves for the inverse situation where the boundary condition of the elastic media is fixed, but the sign of bulk material properties abruptly change. The eigenfrequency of line modes at an interface between bulk metamaterials can be tuned by varying the mass density of the materials.
Discrimination of Vibrotactile Stimuli: Effects of Frequency Variation
Authors: Yeganeh Nashmin , Makarov Ivan , Kristjánsson Árni , Unnthorsson Runar
Published: February 2024

This paper reports on an empirical study that investigated the effect of frequency on the acuity of spatial localization on the skin of the forearm, as well as differences in localizability at different locations on the forearm. Three actuators were positioned in a 3 × 1 array along the forearm, and two adjacent actuators were sequentially activated with a 100 ms interstimulus interval, followed by activation of one of the three actuators in random order. Participants were asked about the direction of the second stimulation relative to the first one, and whether it was perceived in the same location as the first, below, or above it. Three frequencies — 100Hz, 200Hz, and 250Hz — were used for the stimuli. Results show that the frequency of the stimulus has a negligible influence on accuracy when the amplitude is kept constant. However, significant differences in the localization accuracy were found at different parts of the forearm. This study provides valuable insights into the design of tactile displays for conveying information on the skin. It suggests that spatial resolution may be optimized by positioning the actuators appropriately, rather than by manipulating the frequency of the stimulus.
Design, Prototype, and Evaluation of a Low-Cost Multimodal Device for Cardiovascular Monitoring
Authors: Ruckman Sophia , Bhatt Jigar , Cook Jadyn , Thibbotuwawa Gamage Peshala , Kakavand Bahram , Taebi Amirtahà
Published: February 2024

Cardiovascular diseases (CVDs) are the leading cause of death in the United States. In most cases, these diseases go undiagnosed and untreated in the general population until the patient’s health is severely affected. Scanning for these diseases is generally done in a clinical setting, something that not everyone takes advantage of. These tests can also be expensive for many, especially in underserved areas. In that regard, the availability of a low-cost monitoring device can help in the early detection and management of cardiovascular diseases, leading to reduced morbidity, mortality, and associated healthcare costs. The goal of this pilot study is to construct and establish the feasibility of an inexpensive sensing device that is noninvasive and can be used to monitor cardiovascular functions outside of healthcare facilities. This device includes an MPU-6050 inertial measurement unit, an AD8232 signal conditioning block, a MAX30102 sensor, and a microcontroller to measure triaxial seismocardiogram (SCG), triaxial gyrocardiogram (GCG), electrocardiogram (ECG), and the oxygen level of the blood. The sensors were enclosed by a custom-designed case that is composed of various 3D printed parts. The combination of these different modalities assessed both electrical and mechanical aspects of cardiovascular activity. To evaluate the performance of the device, three adult subjects (both sexes: 2 males and 1 female; mean age: 26±5.29 years old) were recruited after institutional review board approval. The subjects were asked to lie in a supine position and breath normally during the experiment. The prototype was placed on the sternum around the 4th intercostal space of the subjects to acquire their SCG, GCG, and ECG signals, as well as the blood oxygen level. The ECG electrodes were placed under the right clavicle, left clavicle, and the lower right side of the abdomen. The signals of interest were also measured simultaneously using more sensitive, expensive, and commercially available sensors (as the gold standard). The signals collected from the prototype were then compared to the gold-standard signals using a similarity index based on dynamic time warping. Results demonstrated a high similarity between the two groups of signals, proving the feasibility of the proposed multimodal device. Future directions for this technology include wireless integration, increased compactness, reduced cost, and clinical testing on a larger and more diverse population including patients with cardiovascular issues. This device will ultimately provide an inexpensive and noninvasive method of scanning for CVDs in the general population.
Proposal of Support Method for Directing Exploration and Exploitation in Engineering Design
Authors: Okamoto Masahiro , Murakami Tamotsu
Published: February 2024

Enterprises must continuously pursue exploration and exploitation activities to enable them to adapt to rapidly changing business environments and generate sustainable profits. However, strategies that balance exploration and exploitation in engineering design have yet to be established. Previously, we developed methods to quantitatively evaluate the degree of exploration and exploitation in design by focusing on qualitative and quantitative changes in product functions and attributes, respectively; however, these methods do not support new product design. This paper presents a method that offers directions for new product design based on information from past products and large-scale external information resources. The proposed method involves extracting function phrases and attribute values from documents, product cluster analysis based on function and attribute distances, and analysis of semantic similarity of functions and chronological trends of attributes. Furthermore, the proposed method was applied to the design of a vacuum cleaner to confirm its effectiveness. Some of the suggestions included functions that lead to design exploration, while others were not effective because of the properties of the external information resources used and natural language processing. Some suggested directions for exploitation were consistent with recent trends in vacuum cleaners, indicating the effectiveness of the method; however, further validation in actual design problems is essential.
Predicting Multi-Mode Dynamic Responses of Structures Using Long Short-Term Memory Neural Networks
Authors: Liao Yabin , Golan Aviad , Sensmeier Mark
Published: February 2024

This paper reports the progress of a research project of using Long Short-Time Memory (LSTM) deep learning neural networks for modeling structural dynamics of complex structures and predicting the structures’ vibration responses due to random excitation. In a prior study, the feasibility of the approach was investigated. The LSTM networks were applied to the responses of various simulated systems subjected to random excitation loads. While the networks demonstrated promising capabilities of modeling and predicting responses of a single dynamic mode, they exhibited difficulties in modeling responses of multiple modes accurately. To resolve the multi-mode issue, this paper presents an improved approach that converts a multi-mode problem into a set of single-mode problems. The multi-mode responses are separated into individual modal response components. A set of mode-specific sub-LSTM networks are obtained, with each trained by using the original input data and a particular modal response component. These sub-LSTM networks are then combined to yield an equivalent LSTM network to model and predict the multi-mode responses. The proposed multi-mode approach is applied to a tapered, cambered wing structure numerically modeled with finite elements and subjected to a random force excitation. The multi-mode approach shows significant improvement over the original direct approach and yields an excellent match between the actual and predicted responses.
Effects of Areal Surface Topography on Thermal Oxidation of Ti6Al4V
Authors: Murwamadala Rabelani Dennis , Veeredhi Vasudeva Rao
Published: February 2024

A simple way to improve and optimize the mechanical properties of a metals surfaces’ is by using a suitable heat treatment. In the case of heat treatment of Ti-6Al-4V alloy, heat treatment alters its areal surface topography. In this study, samples of Ti-6Al-4V alloys are prepared with varying roughness are treated at 750 °C at varying time durations. The treated surfaces were then measured using a laser confocal microscope, and data was processed in the Confomap software. The software has advanced analyses modules useful for real-time quick analysis of topological data. The study explores the topological changes caused by heat treatment using these advanced modules. The changes in surface, functional parameters, directionality, isotropy, and areal spectral properties are summarized and reported. The results show a direct correlation between these surface changes, initial surface properties, and the treatment duration. The results show a significant change in the two-hour treatment for all measured parameters except the areal spectral results, which significantly changed in the eight-hour treatment experiment.
Capillary Network for Fluid Access
Authors: Zhang Xuewei , Lorente Sylvie
Published: February 2024

The theoretical and numerical development of capillary networks for water transportation is documented here. The capillary network is made of dendritic structures connecting the sources to a sink (the outlet); water is extracted by capillary suction from those multiple random sources and the flow is conducted to one single outlet. The approach is based on the constructal law of evolutionary design. The development of the network starts with one channel, then sources are connected to the network one by one with the objective of transporting higher and higher flow rates through the network while decreasing the overall friction losses. For a fixed network volume, the capillary network generated in a plate has a higher flow rate compared to the one generated in a sphere. The average bifurcation angle from both cases which leads to a higher flow rate is 71°. The impact of the Hess-Murray’s law is discussed in the work. The higher volumetric flow rates are obtained when the radius exponent ratio between the mother and daughter channels ranges from 2 to 25 whilst the value is 3 according to Hess-Murray’s law. A transient numerical study of the capillary flow in the developed network is performed. The end of the transient regime leads to results equivalent to the ones obtained with the in-house approach, therefore validating it.
Success Factors and Barriers in Industry-Academia Collaborations - A Descriptive Model
Authors: Kempf Christoph , Hellwig Imke , Bastian Annika , Ritzer Katharina , Albers Albert
Published: February 2024

Companies cannot overcome the increasing complexity of nowadays cyber-physical systems alone. Thus, the industry uses academic research as an important source for gaining new knowledge and technologies. However, a successful exchange is fraught with barriers, so it is important to understand the success factors and barriers. This paper presents a model explaining the most relevant success factors and barriers to industry-academia collaborations and their relations. Based on a systematic literature review, an interview study, an online survey, and focus groups, we identified 22 relevant success factors and 22 barriers. We clustered these success factors and barriers into five categories: communication & feedback, information & (technical) support, motivation & commitment, people & team, and structure & organization. We believe that our model will help improve industry-academia collaboration’s success by raising awareness of the barriers and offering success factors as setting levers. Furthermore, our model can serve as the basis for further research of methods for and to support industry-academia collaboration. Therefore, we intend to develop a methodology for challenge-driven industry-academia collaboration.
Determine the Maximum Negative Operating and Collapse Pressure of Stocked Spiral Duct With and Without Corrugations
Authors: Harvey Justin , Walker Charles D. , Paruchuri Venkata Avinash , Idem Stephen
Published: February 2024

This paper describes an experimental program to experimentally determine the extent to which incorporating corrugations in spiral ducts increased their strength, thus permitting operating and collapse pressures that were higher (more negative) than non-corrugated ducts of the same gauge. The presence of corrugations increased the apparent stiffness of the ducts, and therefore suppressed their tendency to deform under negative pressure. Relatively small diameter spiral seam ducts were more resistant to excessive deformations than larger diameter ducts, for a given wall thickness. At the smallest nominal duct diameters considered in this test program the negative internal gauge pressures where corrugated spiral seam ducts were likely to first exceed a prescribed deflection limit were as much as 6 to 9 times greater than the corresponding values for non-corrugated ducts of the same wall thickness. The ability to withstand the effects of negative internal gauge pressures diminished as the duct diameter increased. Little or no benefit to incorporating corrugations was observed at the largest duct diameters that were investigated. This research yielded a table of negative pressure capacity for several standard gauge spiral ducts, with and without corrugations, that will enable the estimation of maximum deflection of the ducts. This also provides guidance regarding potential collapse pressures.
Highlights of Accelerated Degradation Mechanisms for Polymer Electrolyte Fuel Cell
Authors: Ordóñez-Saca Brayan , Espinoza-Andaluz Mayken , Santana-Villamar Jordy , Andersson Martin
Published: February 2024

Polymer electrolyte fuel cells (PEFCs), considered green devices, use hydrogen and oxygen as reactants in electrochemical processes to produce electricity, water, and heat as by-products. The use of this technology in the automotive industry and power generation has led to a detailed study of its operating principle to make it cost-effective. Polymer electrolyte fuel cells as innovative technology has promoted research to improve its performance. For this reason, a review of the accelerated degradation methods for the membrane, the catalyst layer, the gas diffusion layer, and finally, the bipolar plates are presented. In this work, it also been found that accelerated stress test has already been standardized for cell structure in general however and on the other side there is a little research on degradation methods for bipolar plates. Finally, a brief review of the mitigation strategies has been carried out, given that with the compilation of accelerated aging in the fuel cell structures, it has been observed that the research is focused on improving materials for the use in the layers of fuel cell.
Controlling Thermal Conductivity of Composite Material – Few Large and Many Small Approach
Authors: Athadkar Meghana , Lorente Sylvie
Published: February 2024

Composite metal foams are made of metal matrix and air-filled spherical inclusions. They have superior mechanical and thermal characteristics when compared to the parent metals. Intrinsic material properties like thermal conductivity of composite metal foams can be controlled by distributing the porosity in the matrix based on few-large-and-many-small approach inspired by the Constructal law. To demonstrate this, large spheres in a metal foam are replaced with smaller diameter spheres, while maintaining constant porosity. It is shown that this form of redistribution of porosity results in decreased thermal conductivity of the metal foam.
Using Low-Cost Hands-On Equipment and Virtual Lab for Teaching and Learning of Mechanical Vibrations
Authors: Tran Kevin , Walker Britt , Utschig Tris , Tekes Ayse
Published: February 2024

Hands-on learning elevates the student’s learning of abstract topics to a new level so they will bridge the gap between the theory and its application area. Although mechanical engineering students are only exposed to hands-on learning in laboratories, students take the fundamental course separate from labs which are offered in the following semester or year, unlike mechatronics, electrical, and computer engineering students. Additionally, the laboratory equipment utilized in mechanical vibrations and control labs are very expensive and bulky and integrated with their own software preventing students to discern signal flow and data recording using sensors and data acquisition systems. To address this problem, we designed two low-cost, portable, and 3D-printed lab equipment for the mechanical vibrations control theory courses and their associated laboratories so that faculty can bring it into the classroom for a quick demonstration and build multiple of the same setups for the lab courses to demonstrate modeling of mechanical systems and fundamentals of vibrations. In addition to the developed equipment, we created a virtual lab in MATLAB Simscape so students can work on the analysis at their own pace.
Laminar Drag Reduction in Microchannels With Slippery Polymer Brush Surfaces
Authors: Sutradhar Jayanta , Fan Bei
Published: February 2024

Flow drag reduction plays a significant role in numerous engineering applications. Microfluidics has been studied for various important applications, such as energy conversion, microfluidic sensors, biosensing, and biomedical devices. In laminar flows in microchannels, drag reduction is capable of reducing the required pumping power, enhancing microfluidic cooling, augmenting electrokinetic energy harvesting, enabling better flow control in chemical and biological devices and etc. To reduce fluid drag, researchers have investigated different techniques which include textured slippery surfaces filled with fluid lubricant (i.e., air or oil) in their textures like superhydrophobic or slippery liquid-infused surfaces. For traditional textured slippery surfaces, to retain fluid lubricant, typically additional specific surface textures are required. However, there are two significant challenges associated with textured slippery surfaces: 1) the surface coverage of the fluid lubricant layer is often limited, restricting overall drag reduction; and 2) fluid lubricant suffers from poor durability as the lubricant layer could be depleted by the overlaying shear flow, after which the surfaces will lose their slipping property and even increases the wall friction. In recent studies, a novel type of non-textured slippery liquid-like polymer brush surface has been developed. The slippery liquid-like polymer brush surface has been demonstrated to exhibit macroscope liquid-like properties with an apparent viscosity that can be potentially smaller than that of water and can work as a fluid lubricant layer. Thus, this novel non-textured slippery liquid-like polymer brush surface represents a promising candidate for drag reduction. To investigate the drag reduction induced by the slippery liquid-like polymer brush surfaces, in this work, we fabricated microchannels with slippery polymer brush-grafted surfaces and microchannels made of silicon surfaces and measured the pressure drops along the microchannels under various flow rates and Reynolds numbers. The drag reduction coefficient and corresponding fluid slip length are calculated. The drag reduction coefficient is between 4.53% to 18.77% for Reynolds number between 5.5 to 12 and fluid slip length in micron scale is achieved.
Experimental Study of Spray Cooling Technique in Liquid Piston Gas Compression at Different Initial Pressure Levels
Authors: Ahn Barah , Ro Paul I.
Published: February 2024

Compressed air energy storage (CAES) is one of the promising energy storage options for renewable energy owing to its relatively small environmental impacts and economic viability. The combination of a liquid piston gas compressor and droplet injection through spray can greatly improve the efficiency of the compression stage of CAES. In the present work, the spray cooling technique in a liquid piston gas compressor at different pressure levels is experimentally tested. Gas compressions starting from 1, 2, and 3 bars with a pressure ratio of 2 were performed with and without the spray method, and the impacts of the initial pressure level on compression efficiency were evaluated. The spray technique showed about 98–98.5% isothermal efficiencies for all three pressure levels, which are substantial improvements from the efficiencies of 83–88% without the spray. Although the three cases show similar isothermal performances with spray, the actual efficiencies may differ depending on the pressure. This is because the spray needs higher inlet pressure and consumes more work when the pressure level is higher. On top of the compression efficiency, droplet properties that are critical to determining heat transfer were estimated to observe how the pressure levels affect the properties.
Feasibility of Trapezius Muscle Electromyography and Electrocardiography to Monitor Stress Levels in High Demand Positions
Authors: Ahmed Mohammad H. , Kaya Mehmet , Taebi Amirtaha , Thibbotuwawa Gamage Peshala
Published: February 2024

Prolonged exposure to stress can have detrimental effects on physical and mental health. This study aimed to monitor anxiety levels with minimal sensors by using trapezius muscle EMG and ECG data during a stress task. Ten healthy adults were recruited, and HRV features were compared with EEG to determine alertness during the stress task. EMG data was compared with EEG β and α wave activity to determine stress levels. During the stress task, an increased β to α ratio in EEG indicated heightened alertness and focus, with a significant increase in trapezius muscle activity and asymmetry to indicate increased muscle tension and stress. Trapezius muscle EMG did prove to be an effective method for determining stress when compared to EEG. ECG derived HRV features showed potential to determine stress levels but require further testing. Based on the results, trapezius muscle EMG and ECG can potentially quantify stress and relate anxiety levels from EEG.
Introducing Machine Learning in Undergraduate Mechanical Engineering Mechatronics Classes
Authors: Kim Jinki , Choi Junghun , Kim Jongyeop
Published: February 2024

Machine learning (ML) that has emerged as a new technology for analyzing big data sets to uncover hidden relationships in an increasingly connected world has a great potential to serve as a critical tool for mechanical engineers to develop better devices and to better understand physical phenomena around us. However, compared to the critical importance and impact of ML and increasingly wide adoption of ML in various mechanical engineering fields, very few mechanical engineering undergraduate students receive direct instruction on ML during their undergraduate work. In order to address these concerns, the goal of this research is to improve undergraduate mechanical engineering students’ understanding and use of machine learning. To accomplish this goal, the research team establishes an integrated education framework to effectively introduce ML to junior-level undergraduate ME students through active and authentic learning by providing hands-on activities with mechanical testbeds. The research team incorporated ML into mechatronics lab activities for measuring mechanical vibrations to introduce and practice ML as an alternative method to analyze vibration signals in addition to classical time and frequency domain vibration analysis, which is one of the important subjects in the curriculum of mechanical engineering. The research group first introduced basic concepts of ML and Long Short-Term Memory (LSTM) model which is one of the ML models suitable for predicting one dimensional or time-series data. Students are then tasked to use the vibration signals they measured as input to train an LSTM model that was provided as a pre-filled MATLAB code with blanks for students to adjust. The results of pre- and post-self-assessment survey asked to the students indicate that students have shown great interest in ML, and considered it important for their careers regardless of the pilot ML learning module. On the other hand, after the pilot laboratory, the students’ self-confidence in ML and mechanical vibrations has greatly increased. Furthermore, the interest in mechanical vibrations increased as well, which provided promising opportunities for enhancing students’ learning. This study results enhance our understanding of how exposure to ML affects undergraduate mechanical engineering students’ understanding and attitude toward ML as a non-computing major and their academic achievement in mechanical engineering.
Application of Convex Optimization for Economic Dispatch and DC Optimal Load Flow Problem
Authors: Adapa Rithvik Reddy , Wang Xin
Published: February 2024

The utilization of Economic Dispatch (ED) and DC Optimal Power Flow (DC-OPF) is aimed at minimizing generation costs, while increasing the reliability of power generation. In contrast to traditional loads in power grids that are static, modern smart grid EV charging stations exhibit time-varying dynamic loads. The Electric Vehicle Supply Equipment (EVSE) loads are dependent on the utility price of electricity at the station and the real-time charging in the EVs, which may impact power quality, grid inertia, and power system stability due to their dynamic nature. Therefore, it is crucial to optimize the operation of generators and power systems to ensure the reliable operation of EV-connected smart power grid systems. To address this issue, this paper proposes novel and effective methods for economic dispatch and DC optimal load flow based on convex optimization. The proposed techniques are applied to an IEEE 30-bus system with static loads replaced with EV charging stations at buses 4, 10 and 19 to simulate a typical power system. The total generation cost and total earning from EV charging stations are calculated from the system. The results obtained indicated better values when compared with previous work.
Global Sensitivity Analysis Method for Model-Based System Safety Assessment on Aviation Piston Engine
Authors: Li Guo , Teng Yida , Xu Tongge , Wang Zilu , Ding Shuiting
Published: February 2024

Aviation piston engines provide an important source of power for general aviation, thereby the identification of safety-critical influences during the design phase is an important requirement for ensuring aircraft safety. Model-based system safety assessment have been developed to overcome the limitations of traditional analytical methods in objectively decomposing and identifying failure in complex coupling problems. Nevertheless, the method is limited research for aviation piston engine, especially for determining safety-critical influences from the global perspective of the entire-engine structure with high complexity. In this paper, a new method for rapidly analyzing entire-engine safety sensitivity analysis from the global perspective is proposed, by introducing model-based system safety assessment for the analysis of aviation piston engine. Compared with local sensitivity analysis results, the proposed RSM-Sobol global sensitivity analysis could not only supply additional information on the interactions between parameters but also accommodate rapid iterative complex system safety analysis in the design stage. A methodical case of sensitivity analysis of the structural parameters of a simplified aviation piston engine is given using the proposed method in this paper. Results show that the importance of each parameter can be ranked by the sensitivity index through global sensitivity analysis. Therefore, the safety criteria could be satisfied by reducing the uncertainty of critical parameters and adjusting the input range based on the analysis, allowing an efficient and intuitive safety analysis during design.
An Experimental Study of the Impinging and Freezing Dynamics of Colloidal Droplet on Solid Surfaces
Authors: Abdelmalek Andro , Zhang Xiaoxiao , Liu Yang
Published: February 2024

In this paper, an experimental study was conducted to characterize the dynamics and thermal evolutions of colloidal droplets impinging and freezing on solid surfaces with different wettabilities (i.e., superhydrophobic vs. hydrophilic) towards the development of a novel freezing-based inkjet additive manufacturing (AM) technology. The experiments were carried out in the Freeze Layering Inkjet Printing (FLIP) facility in the Mechanical Engineering Department of the City College of New York (CCNY). While the transient impinging/freezing dynamics of colloidal droplets were resolved by using a high-speed imaging system, the thermal evolutions of the freezing colloidal droplets were also characterized by using a high-speed high-resolution Infrared (IR) thermal imaging system. In addition, the deposition patterns formed under the conventional evaporation-based approach and the novel freezing-sublimation approach were also evaluated by using an automated high-accuracy freeze dryer facility. It was found that the time scale of the dynamic process (i.e., impact, spreading, receding, rebounding, and settling) was much faster than the thermal process (i.e., nucleation and solidification) for both surfaces. The dynamics of the colloidal droplets during the impinging process were coupled with the thermal processes that govern the freezing of the droplets. The surface wettability had a direct effect on both the freezing footprint and the freezing rate.
Life Cycle Assessment of Waste Coal and Biomass Co-Fired Power Plant With Carbon Capture and Storage Technologies
Authors: Sarkar Surja , Bhoi Prakash
Published: February 2024

One of the global concerns that have received a lot of attention recently is climate change. Coal, natural gas, petroleum, and other gases constitute the majority of the fuel used to generate utility-scale electricity in the US. Global warming is a result of widespread emissions of greenhouse gases, particularly CO2, from the combustion of fossil fuels. However, due to their lower carbon footprint, biomass-based heat and power generation are expanding quickly, aiding in the achievement of the target of zero carbon emissions. In this study, the life cycle assessment (LCA) of a 100 MW subcritical waste coal and biomass co-fired power plant with and without carbon capture and storage (CCS) technologies has been assessed considering raw material extraction, transportation, power generation, and associated inputs and outputs. The findings demonstrate that increasing the biomass ratio reduced global warming potential (GWP), and incorporating CCS further decreased the GWP. However, higher biomass ratios and CCS integration led to increased eutrophication, ozone layer depletion, acidification, and other impact potentials.
Improving the Long-Term Durability of Polymers Used in Biomedical Applications
Authors: Hossain Mohammad , Madasani Ravi Chandra
Published: February 2024

Hydrophobic surfaces can improve the long-term mechanical response of polymers by delaying their degradation caused by moisture absorption over time. This improvement in long-term mechanical performance can significantly increase the lifespan of polymers used in various biomedical applications, such as total joint replacement prostheses applications. Although a number of surface modification techniques have been developed over the years, such as introduction of various textures on the surface; their specific influences on hydrophobicity enhancement as well as long-term mechanical performance are yet to be fully understood. In this study, surface textures, with variation in type and geometry, are introduced on model Ultrahigh Molecular Weight Polyethylene (UHMWPE) and High Density Polyethylene (HDPE) surfaces to study the effect of surface modification on hydrophobicity and long-term mechanical performance under environmental conditions. The results show that introduction of surface textures significantly improves the hydrophobicity of model polymers. Texture length or diameter significantly affects the improvement in hydrophobicity. However, texture spacing does not have significant influence on the improvement in hydrophobicity. How this improvement in hydrophobicity facilitates improving the long-term mechanical performance under environmental conditions is investigated. The study provides useful guidelines to improve the long-term mechanical response of polymers for various applications, including biomedical applications.