bluuebunny/crossref_metadata_2025 huggingface dataset:
Topology Optimization Using Neural Network for Stress Constrained Problems
Authors: Shishir Md. Imrul Reza , Tabarraei Alireza
Published: February 2024

This paper introduces an innovative approach that utilizes neural networks to incorporate stress constraints into topology optimization. In this method, a neural network is trained to generate the topology density field using a loss function, while Fourier space projection is employed to control the length scale. The implementation takes advantage of JAX, a high-performance Python library for automatic differentiation, which enables end-to-end differentiability and automatic sensitivity analysis through backpropagation. The use of a neural network enables expressing the entire optimization process as a single differentiable function. This feature streamlines the optimization process and facilitates faster convergence, providing a significant advantage over conventional methods.
Model-Based Assist-as-Needed Control on a Provisional Pediatric Lower-Limb Orthosis
Authors: Wiebrecht Jason J. , Strick Jacob A. , Goo Anthony , Sawicki Jerzy T.
Published: February 2024

This paper describes the development and preliminary testing of a model-based assist-as-needed (MBAAN) controller for a provisional pediatric lower-limb exoskeleton. Assistive control methodologies for medical exoskeletons can vary drastically due to user-specific pathologies and therapy goals. The MBAAN controller presented combines a model-based assistive torque controller with an assist-as-needed control methodology, resulting in a user-specific assistive torque profile. The goal of this approach is to improve gait position reference tracking while decreasing user effort, quantified by user applied torque to the system. The controller uses a linearized model of the system identified through frequency response analysis to generate a preliminary assistance profile. The MBAAN controller utilized this torque profile along with position error weighting to provide assistance when the gait of a simulated user was underperforming a desired performance threshold. The controller was first implemented in simulation, and then in physical experimentation on a provisional hip-knee orthosis to guide a model leg. Both the simulation and physical experiment suggested that MBAAN control can provide subject-specific assistance. The results from the physical experiment demonstrated that the MBAAN controller reduced the root-mean-squared (RMS) position error by 21% and 22% for the hips and knees relative to the baseline comparison, respectively. The MBAAN controller was also able to reduce emulated user applied RMS torque to the system by 15% and 23% for the hips and knees, respectively. The results of this study suggest that MBAAN control can improve user gait tracking while reducing user effort on the provisional orthosis, motivating further assistive studies.
Mounting Systems for Electric Powertrains: Optimization and Parameter Sensitivity
Authors: Kaul Sudhir , Borra Chaitanya
Published: February 2024

Noise, vibration, and harshness (NVH) characteristics of electric powertrains have been receiving increasing attention due to the unique vibroacoustic characteristics of different electric motors commonly used in electric and hybrid vehicles. NVH characteristics of electric powertrains are unique due to several reasons including harmonics of electromagnetic forces, coupling of modes of the motor stator assembly, noise and vibration resulting from pulse width modulation, etc. While a traditional mounting system for an internal combustion engine typically needs to be designed for a frequency range of 0 to 200 Hz, the response of an electric powertrain is generally expected to exceed 2 kHz. Therefore, factors such as internal resonance, wave effects, and high-frequency noise and vibration are specifically unique to electric powertrains and their mounting systems. Two engine mounting configurations that have shown promising results for electric powertrains are the cradle mounting system (three-point mounting) and the saddle mounting system (four-point mounting). These two mounting systems provide a balance between mitigation of force transmissibility at lower and higher frequencies while being well-suited for transient loads. This paper investigates the sensitivity of force transmissibility and frequency response to some of the design parameters of the engine mounting systems for electric powertrains. The determination of optimal mounting system parameters is also investigated in this study. A spatial model with a discretized representation of each engine mount has been used for analysis since it is capable of capturing wave effects as well as high-frequency responses up to 10 kHz. Results indicate that the model can be used to determine an optimal configuration of the mounting system especially when a specific frequency bandwidth is targeted. The optimal four-mount system is seen to substantially reduce the overall force transmissibility. The viscoelastic parameters and the mass and inertia of the powertrain are not seen to influence the peak amplitudes of force transmissibility while slightly shifting the natural frequencies of the lower modes without influencing higher modes. The results of this study can be used for the design and development of robust mounting systems for electric powertrains while accounting for design constraints.
Prediction of Critical Heat Flux in Tube Bundles With Crossflow
Authors: Shah Mirza Mohammed
Published: February 2024

Evaporators and boilers with flow across horizontal tube bundles are widely used in industries including refrigeration and chemical processing. As yet there is lack of a well-verified correlation for predicting local or average CHF (critical heat flux) in such bundles. The available data and correlations are reviewed. The available methods for predicting bundle mean CHF were found to be too conservative. More realistic values of bundle average CHF are proposed based on published test data. The author’s well-verified correlations for CHF on a single tube with subcooled and saturated flow at zero quality across it are compared with test data for tubes in tube bundles together with other correlations. The author’s correlations agree well with all data while the others fail for data other than their own. Results of the comparison are presented and discussed. The needs for further research are identified.
Statistical Shape Modelling of the Lumbar Spine With Reference to Gender and Principal Component Analysis
Authors: Almalki Faris A. , Cortes Daniel H.
Published: February 2024

Numerical simulation of spine mechanics relies on anatomical features of the vertebrae. Statistical shape models aid in these simulations by including shape variability and differences between groups, facilitating finite element simulations for medical procedures. This study aims to develop a statistical shape model of the lumbar vertebrae and to determine shape differences between genders. This study used CT images and 3D segmentations from the Vertebrae Segmentation challenge (VerSe) with a total of 138 vertebrae from 46 patients consisting of L3, L4, and L5 vertebrae. From these segmentations, statistical shape models were created, using ShapeWorks software, for the overall and gender-specific means. Moreover, gender differences, principal component analysis and modes of variations were illustrated. Major differences in posterior elements between overall, male, and female means were identified. Regarding the principal component analysis, the first principal component accounted for 39.4% of the variation, which was distributed between the vertebrae in dissimilar patterns. The second principal component, accounting for 20.4% of the variation, was concentrated in L5. In conclusion, this study specifies locations in the lumbar vertebrae with significant differences between genders and identifies modes of variations in the sample using principal component analysis.
Attitude Control of a Satellite Applying the SDRE and H-Infinity Methods
Authors: Souza Luiz C. G. , Cubillos Ximena Celia Mendez
Published: February 2024

Space exploration is one of the main drivers of innovation and innovative technologies. Space missions are complex and high-cost procedure, involving several steps, where the Attitude Control System (ACS) needs to be robust, reliable and perform well. The ACS is responsible for the important phase that is injection of the satellite’s orbit where the angular velocities is extremely high until its attitude control associated with its normal mode of operation whose degree of pointing is extremely demanding compatible with the mission’s pointing requirements. The ACS of a satellite aims at determining and controlling the attitude of the satellite, and often cannot be repaired in space. On the others hand, when satellite dynamics involves plant uncertainties and large-angle maneuvers, linear control techniques are unable to design the ACS that meet the mission requirements. In this paper one investigates the performance and robustness of the union of the SDRE (State-dependent Riccati Equation) and the H-Infinite (H∞) control techniques. This investigation development a non-linear control algorithm with greater flexibility, which allows the space engineer to design an ACS with the balance between the performance of the SDRE technique with the robustness of the H∞ technique.
Design of Low Density Architectured Metamaterials With High Compressive and Torsional Stiffness
Authors: Liu Xiangbei , Jeon Joseph J. , Tiplea Anisia G. , Li Yan , Song Bo
Published: February 2024

Metamaterials are architected cellular networks with solid struts, plates, or shells that constitute the edges and faces of building cells. Certain metamaterial designs can balance light weight and high stiffness requirements, which are otherwise mutually exclusive in their bulk form. Existing studies on these materials typically focus on their mechanical response under uniaxial compression, but it is unclear whether a strut-based metastructure design with high compressive stiffness can exhibit high torsional stiffness simultaneously. Designing lightweight metastructures with both high compressive and torsional stiffnesses could save time and cost in future material development.

To explore the effect of unit cell design, unit cell number, and density distribution on both compressive and torsional stiffnesses, a computational design space was presented. Seven different unit cells, including three basic building blocks: body-centered cubic (BCC), face-centered cubic (FCC), and simple cubic (SC) were analyzed. All samples had a relative density of approximately 7%. It was found that a high compressive stiffness required a high concentration of struts along the loading direction, while a high torsional stiffness needed diagonal struts distributed on the outer face. Increasing unit cell numbers from 1 to 64 affected stiffness by changing the stress distribution globally. Non-uniform metastructure designs with strengthened vertical and diagonal struts towards the outer surface exhibited higher stiffness under either compressive or torsional loading. This study provides valuable guidelines for designing and manufacturing metamaterials for complex mechanical environments.
Investigation of the Influence of Nylon-6 vs. Nylon-66 on the Mechanical Performance of Composite Bone Tissue Scaffolds
Authors: Coburn Brandon , Joyce Robert , Salary Roozbeh (Ross)
Published: February 2024

Despite recent advances in bone tissue engineering, patient-specific treatment of bone pathology using porous osteoconductive scaffolds has faced clinical challenges, which to a great extent stem from a lack of mechanical strength as well as bioactivity (which are critical for osteogenesis, bone bridging, and ultimately bone healing). There is a need for synthesis of not only biocompatible, but also mechanically strong materials with low immunogenicity for bone regeneration. The goal of this industry-academia research work is to fabricate porous, biologically active, and mechanically robust bone tissue scaffolds for treatment of bone fractures, defects, and diseases. In pursuit of this goal, the overall objective of the work is to systematically investigate the effects of Nylon-6 as well as Nylon-66 on the mechanical properties of bone tissue scaffolds, fabricated using fused deposition modeling (FDM), which is a high-resolution additive manufacturing method.

In this study, the fabricated bone scaffolds were composed of cellulose fibers, polyamide (nylon), as well as polyolefin (referred to as PAPC hereafter), having complex internal microstructures, designed based on triply periodic minimal surfaces (including Schwarz Gyroid, Schwarz Primitive, Schwarz Diamond, and Neovius microstructures). Three types of scaffolding composite materials, i.e., PAPC-I (Nylon-6-based), PAPC-II (Nylon-6-based), and PAPC-V (Nylon-66-based) were utilized in this study. The FDM fabrication of the bone scaffolds was based on a microcapillary nozzle (heated at 215 °C for PAPC-II as well as 235 °C for PAPC-I and PAPC-V) with a diameter of 400 μm, a print speed of 10 mm/s, and a material flow of 120%. Material deposition was on a heated surface, kept at 80 °C for PAPC-II as well as 95 °C for PAPC-I and PAPC-V. A layer height and line width of 200 μm and 300 μm, respectively, were set for the 3D-fabrication process. To avoid filament breakage during the FDM material deposition process, retraction distance as well as retraction speed were reduced to 5 mm and 10 mm/s, respectively. In addition, due to the brittle nature of PAPC-V (having a high Nylon-66 content), it was preheated prior to feeding. The mechanical properties (such as elasticity modulus) of the FDM-fabricated bone scaffolds were characterized using compression testing. Overall, the outcomes of this study will pave the way for patient-specific fabrication of mechanically robust and bioactive bone tissue scaffolds with optimal medical properties for the treatment of bone pathology.
Effects of Foil Camber and Non-Zero Angle of Attack on The Unsteady Forces Produced by a Turbomachine Ingesting Turbulence
Authors: Owsley Isaiah J. , Goldschmidt Margalit Z. , Hanford Amanda , Lysak Peter , Jonson Michael L.
Published: February 2024

Turbomachinery rotor blades experience unsteady lift forces due to turbulence and circumferential variation in the inflow velocity. These forces can be a source of unwanted vibration and radiated sound. The unsteady force spectrum is often modelled to first order using a flat plate approach. However, it is known that mean loading effects can have a significant influence on airfoil unsteady lift for sinusoidal gusts with certain wavevector orientations [1]. To this end, the Atassi [1] gust response model for airfoils with camber and non-zero angle of attack has been incorporated into a rotor turbulence ingestion model [2] to determine the effect on the unsteady force spectrum. The Atassi gust model describes the interaction between a two-dimensional sinusoidal gust with a cambered foil placed at a small angle of attack to the mean flow. To apply this single harmonic gust response to the turbulence ingestion model, the gust responses for sinusoidal components with a distribution of wavevector angles are integrated based on an isotropic turbulence energy spectrum.

The updated turbulence ingestion model is then applied to a parametric study investigating the effects of foil geometry (specifically camber and non-zero angle of attack) on the unsteady forces produced from turbulence ingestion. The baseline geometry used for this study is the Sevik [3] rotor. To assess the sensitivity of the unsteady force spectrum to camber, predictions for a 0, 6, and 12% cambered foil with zero thickness at 0° angle of attack are generated. For these cases, foil camber effects are found to be largely negligible, except at low frequencies where the additional forces generated by streamwise gust components become dominant. The influence of non-zero angle of attack on the turbulence ingestion rotor force is also relatively minor for small angles of attack, but an increase of a few dB is predicted at higher frequencies as the angle of attack is increased to 15°. These results are generally consistent with measurements reported in the literature, where camber and angle of attack effects are shown to be weak, and the overall effects are much smaller than the changes in the sinusoidal gust responses due to the streamwise symmetry and averaging effect that occurs with isotropic turbulence. While the turbulence ingestion model was successfully extended to account for foil geometry effects using the Atassi gust response model, there is continued interest to explore the effects on the unsteady force spectrum when the simplifying assumption of isotropic turbulence is removed.
A Comparative Study on Insulation Materials in Tanks for the Storage of Cryogenic Fluids in Fire Incidents
Authors: Eberwein Robert , Hajhariri Aliasghar , Camplese Davide , Scarponi Giordano Emrys , Cozzani Valerio , Otremba Frank
Published: February 2024

Liquefied Hydrogen (LH2) or Liquefied Natural Gas (LNG) establish themselves as important energy carriers in the transport sector. Its storage requires tanks with Thermal Super Insulations (TSI) to keep the transported fluid cold. TSI has proven itself in various applications over a long time, but not in the land transport sector, where accidents involving collisions, fires, and their combination are to be expected. The focus of this study is to investigate the behavior of different types of TSI when exposed to a heat source that represents a fire. Therefore, a High-Temperature Thermal Vacuum Chamber (HTTVC) was used that allows the thermal loading of thermal insulation material in a vacuum and measuring the heat flow through the TSI in parallel. Within this study, 5 samples were tested regarding 3 different types of MLI, rock wool, and perlites. The thermal exposure caused different effects on the samples. In practice, this can be connected to the rapid release of flammable gases as well as a Boiling Liquid Expanding Vapour Explosion (BLEVE). These results are relevant for the evaluation of accident scenarios, the improvement of TSI, and the development of emergency measures.
Curved Seawalls As an Erosion Management Tool for Saipan
Authors: Yagi Yoshihiro , An Yajun , Dillon Heather E.
Published: February 2024

The purpose of this research is to address the problem of coastal erosion on Beach Road, Saipan’s main highway, by analyzing what type of curved seawall would be most effective at reflecting wave energy. This project is motivated by the challenge of coastal erosion which has become a major issue for many Pacific Islands. If left unaddressed, coastal erosion and inundation will leave many islands in economic and societal ruin, as these islands build their communities and infrastructure along their coastlines. As these island-communities have a vested interest in preserving their way of life, our goal is to provide these islands with information related to seawall type, overtopping potential, and potential failure points of various seawall geometries.

Our analysis was conducted with the computational fluid dynamics (CFD) solver OpenFOAM where experimental work began with the adaptation of a baseline dam break simulation to simulate a single crashing wave onto various seawalls. These seawalls were traced, and their geometries developed into a triangular mesh using Salome. Once developed, our geometries were then taken to OpenFOAM and incorporated into the dam break simulation. We then compared the fluid behavior in Open-FOAM with a physical experiment using 3-D printed scaled models and a digital hydraulic bench. Through OpenFOAM simulations we confirmed that the FSS seawall performed the best for reducing wave overtopping and reflecting waves when compared to the VW and inclined wall. This analysis on seawall geometry can be used to jumpstart talks on coastal defense mechanisms for Saipan.
Numerical Study of Liquid Piston Compression Using Large-Eddy Simulation and Volume-of-Fluid Approach
Authors: Nguyen Thien D. , Rendall Joe , Kowalski Steve
Published: February 2024

Efforts to increase the efficiency of residential and commercial air conditioners and heat pumps have demonstrated that the compressor accounts for most of the system’s electrical energy usage. Therefore, the efficiency of this component should be improved to reduce its energy usage. The US Department of Energy’s Oak Ridge National Laboratory developed a near-isothermal liquid piston compressor (LPC) that uses propylene glycol (PG) to compress CO2. This report presents numerical studies of the LPC in which the compression chamber fills with injected PG from the bottom inlet. Numerical simulations were performed using the large-eddy simulation (LES) with the wall-adapting local eddy-viscosity (WALE) subgrid-scale model coupled with the multiphase volume-of-fluid (VOF) model to simulate the transient interface between gas and liquid and to capture the heat and mass transfer within the compression chamber. In this effort, effects of boundary conditions applied to the LES-VOF calculations (e.g., no wall, an adiabatic wall, and a wall with a heat flux subscribed) to the overall pressure and temperature of CO2 gas as well as the transient evolution of flow and heat transfer evolution within the compression chamber are investigated and discussed. It was found that the LES calculation with no wall have shown no dynamical flow patterns and the volume-averaged temperature of CO2 increased from 305 to 392.7 K, while LES calculations with a constant wall temperature or a wall heat flux had similar increases of CO2 temperatures. Results of LES simulation using a wall heat flux showed different stages in the compression process and revealed dynamical formation and interaction of CO2 gas layers and circulation flow patterns within the chamber that contribute to the overall heat transfer between the solid wall, gas, and liquid surface in the compressor.
An Inexpensive Multidisplinary Teaching Lab Kit for Remote Dual Enrollment Introductory Engineering Courses
Authors: Lacerna Alexander D. , Parker Joel L. , Traum Matthew J.
Published: February 2024

In University of Florida’s EGS1006 “Introduction to Engineering” course, students explore the 14 different undergraduate majors offered through the Herbert Wertheim College of Engineering. In addition to in-person attendees, UF registers dual enrollment (high school + college) remote learners from across Florida in EGS1006. These students are often ethnic minorities, first-generation college students, female, and/or from socioeconomically disadvantaged communities: precisely the groups underrepresented in engineering majors that colleges strive to attract and retain.

Due to geographic dispersion, dual enrollment students are not able to engage in-person with the EGS1006 pragmatic activities, which potentially puts them at a disadvantage relative to their in-person peers. Therefore, a shippable educational laboratory kit was developed and deployed in Spring 2023 to mitigate this disadvantage. The kit and supporting curriculum provide hands-on activities and exposure to all UF’s 14 UF engineering disciplines at reasonable per kit cost (when manufactured, shipped, and returned/refurbished at scale). Moreover, since the kits are designed to be returned and refurbished for reuse each semester, the cost-per-student-served over many semesters approaches ∼$36 with $16/kit for roundtrip shipping and $20/kit for refurbishment.

This paper introduces the EGS1006 kit, describes activities and experiments that showcase how each UF engineering major is represented, and explains how the kit is fabricated. Additionally, a series of indirect assessment questions have been developed and embedded within the dual enrollment EGS1006 assignments. These questions were designed to gauge students’ pre/post impressions on 1) using the kit, 2) self-efficiency, 3) attitude toward engineering overall, and 4) interest/disinterest in specific engineering majors. These questions are included to describe and frame an ongoing pedagogical study of the kits’ value and utility for the EGS1006 dual enrollment cohort.
Vortex Spoilers Do Not Work to Suppress Pulsations Generated by Turning Flows Into a Side Branch Against a Deadleg
Authors: Botros Kamal K. , Clavelle Eric , Chan Nic , Satish Hemanth
Published: February 2024

Turning flow into side branches against a deadleg along the main run can generate high levels of pulsations if the piping system acoustic resonance frequency matches closely the flow generated instabilities within the T-junction characterized by specific Strouhal number (St) that is function of the branch to main run diameters ratio (d/D). In order to suppress these pulsations, vortex spoilers (aka vortex breakers), akin to those employed and inserted inside the side branch to suppress pulsations generated due to flow past side branches, have been considered. The difference lies in the fact that these spoilers would have to be placed in the main-run close to the downstream trailing edge of the T-junction. Three spoilers of different geometries and characteristics were designed and tested experimentally on a high-pressure natural gas test setup at a pressure range of 4–5 MPa, mean gas velocities of 6–36 m/s in a DN100 piping arrangement and for d/D = 1.0. These spoilers are flat plate, perforated plate, and cross-plates all of length = 2.1D. Tests were carried out at different positions of the respective spoilers in relation of the T-junction intended to interfere and suppress the coherent vorticity generation and its interaction with the mean flow velocity and acoustic fields according to Howe acoustic source power theory. The paper presents details of the test setup, data collected, analysis of the normalized pulsation amplitude (P*) vs. St number and effectiveness of each of the three spoilers at three different positions inside the main run. It was found that the maximum amplitude of P* without spoilers was reached at St number approximately equals to 0.12 which is close to published data. However, none of the tested three spoilers was effective in suppressing the level of pulsations irrespective of their placement position inside the main run. It appears that due to the fact that the flow has to turn into the side branch, a high degree of shearing resulting in regions of high vorticity generation, combined with the predominant direction of the mean flow into to the side branch, all of which contribute to the acoustic power source, regardless of any interference or potential interference brought about by any spoiler. Complementary unsteady CFD simulations were also conducted on a similar experimental setup on air under well-defined flow and acoustic boundary conditions published in IMECE 2021. The combined experimental and CFD simulations concluded with that vortex spoilers appear to be of no use in suppressing pulsations generated by turning flows into a side branch against a deadleg at least in the range of spoiler placement positions studied.
Bison Verification and Validation Activities for TRISO
Authors: Toptan Aysenur , Hales Jason D. , Jiang Wen
Published: February 2024

Numerical modeling and simulation (M&S) tools play a key role in the research, development, and overall safety assessments of next-generation nuclear energy systems. One such tool, Bison, is a nuclear fuel performance code applicable to many different fuel forms (e.g., light-water reactor fuel, oxide and metallic fuel for fast reactors, tri-structural isotropic (TRISO) fuel, and plate fuel), and it uses the finite element method to model the thermo-mechanical response of nuclear fuels. One fuel form widely utilized in Generation-IV high-temperature gas-cooled and fluoride-salt-cooled nuclear reactor concepts is TRISO fuel. Recently, Bison’s capabilities were significantly expanded to enable it to model the performance of TRISO particles and compacts. It is important that Bison’s computational results be reliable and predictive, since this code is used to inform high-consequence decisions. The various processes developed to address this issue generally entail two fundamental steps: verification and validation (V&V). Verification ensures that the code functions correctly and is reliable. Code/solution verification, code benchmark, and software quality assurance (SQA) exercises are examples of verification activities, whereas validation is the process of assessing a code’s capability to accurately model physical problems. Comparisons between code results and experiments are used to quantify the validation level. Application of V&V procedures is crucial to the development of computational tools that are free of coding mistakes and can accurately represent reality. The current study presents an overview of Bison V&V activities relevant to the TRISO fuel concept, including code/solution verification exercises, International Atomic Energy Agency (IAEA)-coordinated Coordinated Research Program (CRP-6) benchmark exercises, and validation exercises utilizing the Advanced Gas Reactor (AGR) experiment series (e.g., AGR-1, AGR-2, and AGR-3/4).
Buckling Analysis of Filament-Wound Cylindrical Shells Considering Pattern Effect
Authors: Özaslan Emre , Yetgin Ali , Acar Bülent
Published: February 2024

A complexity of a filament-wound structure lies in the winding pattern that naturally occurs during the manufacturing process. The winding angle changes from +θ to −θ in the transition regions between the patterns. This type of geometrical change can potentially decrease the strength of the structure and lead to catastrophic failure, particularly under axial compression loading. It is well-known that compression loads can cause buckling failures, which are sudden and without prior warning. Therefore, considering the local deformation in the transition regions of the patterns as a source of imperfection in buckling analysis is crucial to prevent such failures. This study examines the effects of the pattern on the buckling behavior of a filament wound cylindrical composite shell numerically. After validating the finite element model with experimental results from the literature, a detailed investigation was performed to understand the influence of various parameters on the buckling load. These parameters include pattern number, winding angle and thickness. The importance of conducting geometrical nonlinear analysis to determine a realistic buckling load and mode was emphasized. It is observed that the effect of patterns on the buckling load is more pronounced in thin shells and at low winding angles. However, no direct relationship was detected between pattern number and the buckling load.
Best Fits, Dark Horses, and Cognitive Style: Investigating Differences in Design Solution Perceptions
Authors: Henderson Daniel , Patel Krina , Jablokow Kathryn , Kilicay-Ergin Nil , Sonalkar Neeraj
Published: February 2024

In industry, engineering design teams can be asked to produce design solutions that clearly follow given specifications and constraints of a problem (i.e., Best Fit solutions), or they may be encouraged to provide higher risk design solutions that challenge those constraints, but offer other potential rewards (i.e., Dark Horse solutions). This study utilized a self-assessment tool to investigate designers’ perceptions of their teams’ Best Fit and Dark Horse solutions. Kirton’s Adaption-Innovation theory of cognitive style provided the framework to explore the impacts of cognitive style on design solution perceptions. The study involved 17 design teams of 3–5 individuals (64 participants) from five different professional organizations, with each team generating one Best Fit solution and one Dark Horse solution in response to the same design prompt. Participants were then asked to place their team’s Best Fit and Dark Horse solutions onto a “FUN diagram,” which is a ternary-style triangular diagram where the vertices correspond to Feasibility, Usefulness, or Novelty, respectively.

The analysis of the responses showed that most adaptive and innovative individuals held distinct perceptions of their Best Fit and Dark Horse solutions, as reflected by their FUN diagram placements. While Best Fit solutions were more often perceived as being Feasible or Neutral, Dark Horse solutions were perceived as being Novel. More adaptive individuals perceived their Best Fit solutions as Feasible, whereas more innovative individuals perceived Best Fit solutions as Neutral. However, there was no apparent relationship between cognitive style and Dark Horse solution perceptions. Understanding more about how individuals perceived their Best Fit and Dark Horse solutions can enable engineering educators and industry practitioners to identify ways to support designers and teams more effectively.
A Comprehensive Review of Acoustic Induced Vibration Methodologies
Authors: Liu Yuqing , Diwakar Philip , Eljaouhari Ismat , Shen Lulin
Published: February 2024

High acoustic energy has the potential to cause severe Acoustic Induced Vibration (AIV) that lead to fatigue failure in a piping system. Over the past few decades, many technical papers have been published on AIV research, and several industry codes and guidelines have been developed. However, gaps and inconsistencies exist, due to limited data and unverified assumptions. With new technologies — in continuous development — in the oil and gas industry, process conditions (such as temperature and pressure) have seen significant changes in recent industrial projects. As a result, the acoustic energy in piping system has been growing exponentially, exceeding the limits of current industrial codes and guidelines.

In this paper, a comprehensive review of AIV methodologies is conducted. Failure data reported in 1980s and 90s, as well as AIV methodologies developed in the 2000s (Carucci-Mueller curve, Eisinger curve, Bruce curve, Energy Institute Guideline, MTD Guideline, etc.) are reviewed along with their limitations and unverified assumptions (based on available data at that time) and compared to the latest research. The latest failure data from recent projects is used to demonstrate the application range for each method. Methods developed based on data in 1980s/90s were limited to sound power level (PWL) of 180 dB, while many plants designed recently have PWL greater than 185 dB, with some as high as 200 dB. Applying traditional methods to new plants with excessive PWL leads to unrealistic and overly conservative design leading to thicker piping and higher costs.

This paper hopes to close these major gaps including noise induced by sonic flow, noise attenuation, effectiveness of asymmetric reinforcement, explore fatigue limits of contour fittings and risks of welded supports. Further goal is to evaluate inconsistencies between industry codes and standards. Most AIV methodologies developed in the past focused on branch fittings with nearly no testing data on welded supports. Many fittings such as sweepolet, sweeplus®, forged tee, 45-deg fitting, and short-contour were not evaluated due to lack of testing data.

Failure modes and lessons learned during the development phase are addressed to emphasize the importance of AIV evaluation during design and operation along with the latest trend in industry codes and guidelines on AIV. In the past, AIV evaluation was often conducted as a post-event assessment, resulting in costly physical changes after the plant had already been constructed. With the latest revision of ASME B31J Code, most engineers now perform AIV evaluation early in the design phase to mitigate risks. The comprehensive review of AIV methodologies presented in this paper helps to provide a more comprehensive guideline for safe design practices and structural integrity.
A Data-Driven Approach for Predicting the Onset of Entrainment in Two-Fluid Stratified Systems During Selective Withdrawal Process Using Machine Learning Techniques
Authors: Hassan Sabbir , James Darryl
Published: February 2024

Selective withdrawal is crucial in the US Strategic Petroleum Reserve and other applications, such as micro-particle coating, thin glass fiber fabrication, and local drug delivery. Physics-based mechanistic models are commonly used to predict the onset of entrainment but have challenges and uncertainties in its computational solutions. Machine learning (ML) models, like Gaussian Process Regression (GPR) and Artificial Neural Networks (ANN), can provide more efficient solutions to these problems.

This study uses experimental data from various sources to investigate GPR and ANN for predicting the onset of entrainment in two-fluid stratified systems. Non-dimensional parameters were used as model inputs to ensure generalizability, and dimensionality reduction techniques, like the Genetic Algorithm, were employed to optimize the models. The machine learning models’ predictions were compared with physics-based models across different flow regimes.

Preliminary findings show that GPR and ANN models have excellent predictive capabilities, surpassing physics-based models. GPR demonstrated slightly better performance than ANN. However, predictions are only accurate if the underlying physical regime remains unchanged. Machine learning models can unify physics-based models based on available training data at different flow regimes. This study emphasizes the potential of machine learning techniques in solving complex problems and offers a novel approach to predicting the onset of entrainment in select two-fluid stratified systems.
Fracture Mechanics of Tetragraphene Under Mixed Mode Loading
Authors: Haddadi Elnaz , Tabarraei Alireza
Published: February 2024

The need to overcome the limitations of graphene in electronic applications has prompted numerous investigations into the exploration of novel two-dimensional carbon-based materials that could potentially introduce an electronic bandgap. Graphene has many 2D carbon allotropes; a quasi-2D semiconductor carbon allotrope, called tetragraphene (TG), was recently proposed. TG is composed of hexagonal and tetragonal rings and shows metallic or semiconducting behaviors with no limitations in electronic applications. This study uses molecular dynamics (MD) simulations to understand fracture properties of triple-layered TG sheets under mixed mode I and II loading using the Tersoff-Erhart potential. We investigate the effect of loading phase angle and temperature on the crack propagation path and critical stress intensity factors. The findings reveal that the critical stress intensity factor and crack propagation path are influenced by both the loading phase angle and temperature. Nonetheless, temperature has an insignificant effect on the critical stress intensity factor, except for cases where the loading phase angle is either 0° or 90°.
Classification of Brain Malignant Tumors Using MRI Scans and CNN Architectures With Optimized Hyperparameters
Authors: Weiss Cohen Miri
Published: February 2024

Based on Magnetic Resonance Imaging (MRI) scans and Convolutional Neural Network (CNN) architectures with optimized hyperparameters, this study proposes a machine learning system for classification of brain malignant tumors. Using a two-level approach, the first level identifies the most suitable MRI modalities for classification by evaluating the performance of the modalities under different hyperparameters. The second level consists of the development and comparison of two CNN architectures, Inceptionv3 and DenseNet121, based on their respective training methods. As part of the optimization process, various hyperparameters are tested, such as epochs, batch sizes, learning rates, and dropout rates. Additionally, it was found that learning rate has an important impact on the training phase with a lower learning rate resulting in a smoother, more consistent process. As a result of optimizing the system, it has been demonstrated that it can accurately classify brain malignant tumors, particularly Glioblastomas.
Testing and Analysis of Mechanical, and Corrosion Properties of 2024 Aluminum Alloy Using Friction Stir Processing
Authors: Dhamodaran Shanthakumar , Velukkudi Santhanam Senthil Kumar , Kuppusamy Raman
Published: February 2024

The friction stir method, an emerging metalworking technique, has the ability to locally and deliberately change the microstructures in the near-surface layers of a treated metallic component. A significant amount of material is permanently deformed, mixed, and exposed to heat in the treatment zone as part of this surface modification procedure, which significantly alters the material’s microstructure. The treated zone is distinguished by a recrystallized fine-grained structure. This strategy was developed from friction stir welding, a type of solid-state joining technique that employs friction to permanently bond metals. The friction stir technique is used to preserve the bulk qualities of the base material while further enhancing resistance to wear, creep, and fatigue. Because of its high specific strength, lightweight, and machinability, There are numerous applications for aluminum and the associated alloys. The AA2024 is one of the strongest aluminum alloys, and it will contain copper as a primary alloying element. Owing to its substantial strength-to-weight ratio, The AA2024 is a material utilised in the aviation industry, notably fuselage structures and orthopaedic equipment. The microstructure and mechanical characteristics of the treated zone can be manipulated by adjusting the tool design and FSP parameters. The current effort tries to determine the best range of processing parameters by altering the tool rotational speed, traverse speed, and applied force. This experiment included tool rotational speeds of 1000, 1300, and 1600 rpm, tool traverse speeds of 15 mm/min, 30 mm/min, and 45 mm/min, and applied loads of 8 kg, 10.25 kg, and 12.5 kg. The experiment is designed using the Box-Behnken optimization technique, which considers three factors at three different levels. To improve material flow for the reinforcing particles, a cylindrical pin of H13 tool steel bearing a hardness of 60 HRC is designed and produced. The ultimate tensile strength (UTS) of FSPed AA2024 samples was tested using a universal testing machine in accordance with ASTM E8 standards. The Vicker’s hardness testing machine was used to perform microhardness tests as per ASTM E384 standards to determine the hardness of FSPed AA2024 samples. By comparing the sample weights before and after testing, the corrosion rates had been determined using the immersion corrosion testing method. The 2D-surface roughness tests were carried out using Taylor Hobson’s Surtronic S-128 roughness testing machine to determine the roughness value of FSPed AA2024 samples. The most effective friction stir process variables are chosen using Grey Relational Analysis (GRA), which is applied to the outcomes of many response tests. At a 95% confidence level, the most important contributing friction stir process factors are identified using an analysis of variance (ANOVA).
Naturally-Circulated Waste Heat Recovery Equipment Driven by Flue Gas Dumped at a Stack and Performance Improvement
Authors: Lee Jaedal , Yi Junseok , Cho Seongkuk , Jeon Soohwan
Published: February 2024

Here, waste heat recovery equipment driven by flue gas dumped at a stack is introduced in order to perform a task to augment energy saving and combustion efficiency in industrial furnaces. The main structure is composed of an evaporator and a condenser as a pair unit for natural circulation of steam as a working fluid. The evaporator and condenser are helical solid finned tubes erected vertically in which the fin side fluids make a cross flow. Steam boiled by the flue gas that sweeps over the evaporator finside condenses into water liquid along the condenser tubeside. Air used for combustion is heated by absorbing latent heat release issuing from steam condensation in the condenser. Thermal robustness and stability tests were carried out to have a long-term operation capability and experience, and secure driving characteristics with which future commissioning scenario will be composed. Two operation modes were performed for thermal efficiency evaluation: one for a baseline with plain tubes in the condenser, and the other with hiTran inserts (product of CalGavin Co., Ltd. [1]) in the condenser. The hiTran was half installed from upstream of the condenser. The hiTran mode has a better thermal efficiency slightly over 2% than that of the baseline mode near at a flue gas inlet temperature of 300°C. By leading to disturbing step-wisely downward-growing boundary layer along the condenser tube surface, the insert as an obstacle against the developing boundary layer seems to be contributable to thermal efficiency augmentation. On the other hand, there appears more subcooled steam condensate at the condenser outlet such that more heat load is assigned to the evaporator. The subcooled heat loads that are allocated to the evaporator for the baseline mode and the hiTran mode are assigned to 5.7% and 12.9%, respectively.
A Literature Review of Automated Fault Detection and Diagnostics for HVAC Systems
Authors: Allen-Magande Hugh , Khazaii Javad , Esmaeili Amin
Published: February 2024

Modern HVAC systems are significant energy consumers and major contributors to environmental pollution. These systems consume around 52% of the total U.S. energy used in commercial buildings on average; withal, the air conditioning industry is responsible for approximately 4% of global greenhouse gas emissions annually. Previous research has targeted ways to improve the energy efficiency of HVAC systems and reduce their environmental impact via enhanced control algorithms. However, because maintenance teams execute HVAC system diagnostics offline, this hinders detecting and correcting any system malfunctions or underperformance immediately. Currently, innumerable research is underway that focuses on improving automated fault detection and diagnostics (AFDD) algorithms for HVAC systems to reduce operating costs and improve efficiency and indoor air quality (IAQ). This study aims to synopsize the typical fault detection and diagnosis systems being developed for commercial and industrial buildings. Still, the authors believe there is a need for less expensive AFDD algorithms for HVAC systems, as well as common standards or protocols for FDD development. Machine learning may be the best approach to achieve a more dynamic system that adapts to changing situations independently, which could be the key to developing an adaptive HVAC AFDD system using Artificial Intelligence.
Finite Element Analysis and Fatigue Life Prediction of a Laterally Conducting GaN-Based Power Package Under Thermal Cycling
Authors: Zaghari Pouria , Sinha Sourish S. , Ryu Jong Eun , Franzon Paul D. , Hopkins Douglas C.
Published: February 2024

Thermal fatigue life analysis of GaN packages is an important consideration that affects the reliability and durability of electronic devices. In this paper, the fatigue life assessment of a GaN laterally conducting power packaging, including SAC305 and Sn63/Pb37 solders was conducted using the finite element analysis (FEA) method. The thermal cycling loading was chosen based on JEDEC Standard JESD22-A104D condition M. With temperature cycling from −40°C to 150°C. To simulate the viscoplastic behavior of solder materials under thermal cycling, the Anand constitutive model was adopted. Coffin-Manson, Engelmaier, and Solomon empirical models were utilized to predict the cyclic life of the package based on stress and strain distribution in the solder layers. Results showed that the critical solder joint location of the failure was in the SAC305 solder. The maximum inelastic strain range of SAC305 solder was calculated to be 0.023697. The fatigue life prediction of the module showed that the Engelmaier model was the most conservative model resulting in a fatigue life of 136 cycles.