bluuebunny/crossref_metadata_2025 huggingface dataset:
An Axisymmetric Computation of Thermal Field Around an Entry Vehicle Descending in the Martian Atmosphere
Authors: Rhisat Fahad Nizam , Molki Majid
Published: February 2024

In this research, an OpenFOAM flow solver is used to simulate the aerodynamic heating experienced by a spacecraft descending through the Martian atmosphere at 39 kilometers above the planet’s surface. Using a computational model and the Spalart-Allmaras Turbulence Model, the flow field at Mach numbers 5, 10, 15, 20, and 27 are simulated to investigate the formation of a bow shock wave and a subsonic layer near the wall boundary in a turbulent flow. The study focuses on the temperature distribution over the entry vehicle’s surface to provide critical information on the thermal challenges encountered in space applications. Pressure and velocity over the length of the entry vehicle are also shown. The results can be used to predict the heating intensity and design effective heat shields for safe descent through the Martian atmosphere. A 2D axisymmetric flow model is used due to computational ease and accessibility. The study shows the potential of computational models and simulations to investigate aerodynamic heating during hypersonic flight and improve the design of entry vehicles for a safe landing on Mars.
Research on Welding Quality Optimization of Ultra-High Strength Steel Welding Joint Under Different Laser Energy Inputs
Authors: Li Siliang , Zhang Heng , Pan Xuanjun , Wang Qian , Liu Haijiang
Published: February 2024

Al-Si coating 22MnB5 steel was the ultra-high strength steel, which was widely used in the field of automobile manufacturing. As an advanced manufacturing process with high energy density laser beam as heating source, laser welding can greatly improve manufacturing accuracy and efficiency. For the laser welding process, laser energy inputs was a key factor affecting the shape and stability of the molten pool. In order to clarify the optimization mechanism of different laser energy input on the welding quality of ultra-high strength steel laser welding joints, the laser welding experiments of Al-Si coating 22MnB5 steel were carried out. The results showed that if the laser power density was constant (7 × 105W/cm2), when laser energy inputs was less than 461 J/cm, undercut appeared on the front of the weld, and the incomplete penetration phenomenon appeared on the back. The welded joint was Y-shaped welded joint. In particular, when laser energy inputs was less than 428 J/cm, Aluminum-rich intermetallic compounds (IMCs) appeared at the edge of the welded joint fusion zone (FZ). When laser energy inputs was greater than 858 J/cm, a small amount of visible pores were generated on the weld. The welded joint was X-shaped welded joint, the distribution of S ferrite and lath martensite was not uniform. When laser energy inputs was 522 J/cm-749 J/cm, the weld surface was smooth and no visible pores. The δ ferrite and lath martensite were uniformly distributed and the grain size was smaller. With the decrease of laser energy inputs, the parameters such as weld penetration, upper and lower surface weld width, upper surface depression and fusion zone area of welded joints were decreased.
Effect of Water Cut and Temperature on the Stability of Emulsifier-Free Oil-Water Dispersion in Batch Separators at Various Stirrer Speeds
Authors: Alanazi Khalid , Mohan R. , Kolla S. S. , Shoham O.
Published: February 2024

The stability of an emulsifier-free oil-water dispersion in a 200 ml batch separator with a 60mm diameter was characterized using experimental data. The objective of the study was to investigate the impact of various water cuts (WC = 25%, 50%, 75%, and 90%) and temperatures (T = 25°C, 60°C and 80°C) on the starting times of water and oil separation, full emulsion’s separation time, and volumes of emulsion at various mixing speeds (600–2500 rpm). The two immiscible phases were EXXSOL™ D110 (mineral oil) and distilled water, with density and viscosity ratios of 0.805 and 0.330, respectively. For the fluid systems studied in this work, the emulsion formed with WCs ≥ 75% was significantly impacted by mixing speed and did not separate for several hours at speeds ≥ 1000 rpm. Emulsions of WCs ≤ 50%, on the other hand, were independent of the stirrer speed and separated fully immediately after formation. According to the experimental results, increasing the temperature accelerated the oil creaming rate but delayed the starting time of water sedimentation and was unsuccessful overall in the separation process. For WCs ≥ 75%, emulsions displayed a shear-thinning behavior with viscosities reaching more than 2300 cP at lower shear rates and water-like viscosities at higher shear rates.
Improving the Load Carrying Capacity of Highly Tapered Laminates
Authors: Ergin Fırat , Kayran Altan
Published: February 2024

Increased interlaminar stresses in ply drop-off regions cause delamination and reduce the strength of the composite parts where a high number of plies are terminated in a short distance. A variable taper angle design is proposed and investigated in this study to postpone delamination in highly tapered laminated composites. The proposed design allows a smoother transition in tapered regions and reduces stress concentrations which are responsible for delamination. Different parametric studies are performed with 2D finite element models in ABAQUS to investigate the dependency of the onset loads of delamination and locations on taper angles. Cohesive elements are utilized for predicting damage in the interface and delamination growth. A parametric study with a single drop-off configuration showed that thin-section delamination is the main failure mode in highly tapered laminates. The study performed with variable taper angle designs showed that more than 55% improvement in the delamination initiation load in the thin-section compared to the constant taper angle design can be achieved with the proposed design.
Methodology to Design 3D Printed Joints: A Case Study Applied to Arm Splints for Healthcare
Authors: Perero Segarra Bryan S. , Helguero Carlos G. , Maldonado Fausto , Hurel Jorge , Amaya R. Jorge Luis , Ramírez Emilio , Vignat Frédéric , Lara Hernan
Published: February 2024

Additive Manufacturing (AM) in medicine has provided advancements in creating prostheses and/or orthoses (PAO). One such procedure is the creation of splints through 3D printing, which is considered an effective and practical alternative for bone and joint recovery. The fixation system employed in the splint is crucial in ensuring the immobilization of the body part, and it can have different locking mechanisms depending on the designer’s criteria. This article introduced a methodology to identify the appropriate joint type based on the design specification, including the type of loads, product geometry, requirements, and printing material. The restrictions are set based on the material used and the service conditions. The selected joint must meet the technical and geometric requirements according to the contact zones and behavior of the joints developed. This methodology selects the joint type that meets the minimum requirements to keep the components assembled based on the initial design requirements. A study case allows a probe of the methodology applied in a splint, and the design offers resistance in service while minimizing the amount of material and joints used to attach the sections to protect the body part. The sizing plans of the joints used in the splint are presented according to the geometry around the contact zone and elaborate on the selected joint’s guidelines.
Applied Experimental Work Designed to Evaluate the Fundamental Heat Transfer From Rotation Only and Rotation and Translation Motion due to Complex Shapes
Authors: G. Giorges Aklilu , Haynes Comas
Published: February 2024

An ongoing objective of food processors is to achieve efficiency without compromising food safety and quality standards. The food production environment is designed to produce specific products with a balance of resources, environment, human labor, automation, quality, and safety while also maximizing productivity and profitability. Energy efficiency plays a major role in food processing, and the heating and cooling processes are continually evolving. In poultry processing, where heterogeneous and complex-shaped products are processed, the thermal process cannot be easily predicted based on previous work done primarily with well-defined shapes and material properties. To understand the fundamentals of this complex system of heat transfer, applied experimental work is designed. It is designed to evaluate the flow type effect while keeping all the other features similar. The current work assesses the degree of differences and similarities between two motions: 1. Rotational system and 2. Rotational and translational system, which represent the in-line industrial water chilling system in practice. The test chicken carcasses were prepared by placing thermocouples at the core of the breast meat while suspended by the leg on the shackle. The cooling process was studied for motion of continually changing rotational direction with two revolutions in clockwise and counterclockwise directions for the duration of the test, with a rotational speed of 1 Hz and a near-zero-degree medium. The results showed a similar cooling profile. Furthermore, the statistical analysis of the data showed that, for the mass range test, the results were not statistically different. Since rotational only test requires less resources, the simpler rotational-only test can be used as a surrogate to evaluate some industrial processing conditions and treatments.
Modeling and Simulation of Orbit Rising Stem Ball Valve System for Real-Time Health Monitoring and Condition-Based Maintenance
Authors: Wang Yaou , Wassar Taoufik , Pan Shu , Shi Jibin , Zhang Haitao , Li Ke
Published: February 2024

The ORBIT rising stem ball valve is a proven technology for use in applications where zero leakage and frequent cycling operations are demanded. The valve uses a tilt-and-turn design, which eliminates rubbing between sealing surfaces, ensuring reliable, extended-life performance in critical and demanding shutoff applications such as switching valves in molecular sieve systems, high-pressure hydrogenation, and hot oil. Within these applications, a single valve failure can lead to significant downtime, production losses, and unforeseen costs for the end user. Traditionally, maintenance is scheduled at predetermined intervals, which can be costly and conservative. This project is focused on developing a physics-based modeling and simulation approach for condition-based maintenance of the ORBIT valve.

Two types of models were used to understand and mimic the ORBIT valve design’s real behavior: finite element method (FEM) and reduced-order models. FEM provided accurate results by considering detailed geometry, material properties, boundary conditions, and nonlinear behavior. The reduced-order model fused first principles and FEM results to reduce the number of costly FEM simulations while providing acceptable accuracy for condition-based monitoring of the ORBIT valve. The reduced-order model was used to establish a baseline condition for each valve and conduct what-if analyses to capture valve behavior under different degraded or failure conditions.

Direct comparisons of the reduced-order and FEM models showed that the difference between their outcomes in identifying extracted features was found to be less than 8%. Calibration using a 10 × 8 in API 6D Class 600 ORBIT valve indicated that the model accuracy was within predefined requirements. The FEM and reduced-order models improved the understanding of ORBIT valve systems, providing a foundation for future real-time health monitoring and condition-based maintenance of valves.
Developing a Floating Calorimeter for in Situ Study of Microbial Activities Near Coral Reefs
Authors: Zhang Yuwei , Kowalski Gregory
Published: February 2024

Calorimetry is a powerful tool used in various industries to measure thermodynamic properties. One potential application is studying the behavior of marine microbes living near coral reefs to assess their health and productivity. Estimating thermodynamic properties, such as Gibbs free energy, in marine microbes is challenging due to the complexity of the microbial community and the absence of complete knowledge regarding the biomass involved in each reaction. Accurately quantifying the Gibbs free energy of marine microbes is critical for understanding their metabolic activity and overall health. However, current commercial calorimeters have limitations preventing in situ experiments, but researchers at Northeastern University and the Microcalorimetry Laboratory at the Mechanical and Industry Department have proposed a novel floating calorimeter (FC) design that allows for accurate and immediate data collection at the beginning of a reaction. A photonic-based nanohole array (NHA) chip combined with the technology of extraordinary optical transmissions (EOT) is integrated into the FC to sense temperature variation. A unique chamber configuration allows microbes to freely flow under seawater environments in a cylindrical shape. By providing a new method for in situ experiments, the FC has the potential to revolutionize the study of marine microbes and contribute to efforts to protect coral reefs and other ecosystems.
Development of Representative Volume Element for Electromagnetic Characterization of a Heterogenous Geomaterial
Authors: Camacho Patrick S. , Betts J. Logan , Priddy Matthew W.
Published: February 2024

Electromagnetic (EM) analysis applied to structural geomaterials is a growing field of investigation for its significant potential in the field of non-destructive testing and characterization of the materials. Previous studies have simplified the multi-phase composition of geomaterials as layered structures, where each constituent material formed its own distinctive layer. While conclusions from such experimental studies were effective in detecting changes in EM responses, the methods of modeling heterogeneous, multi-phase structures were not be as representative of geomaterial composition like an aggregate-matrix model. A study was conducted to reveal discrepancies in EM responses of laminar and aggregate-matrix models. The laminar and heterogenous matrix models were compositionally equivalent with respect to the constituents present. Scattering parameter responses were recorded as a function of frequency for two-port systems; the frequency range of investigation was 0 to 25 GHz. Significant discrepancies in the responses were evident with no immediately apparent relationships between the responses. This conclusion prompted the need to further investigate the influences of a model’s geometric parameters on its EM response. The geometric parameters investigated here were the centroid positioning of the aggregates and the size of the material element simulated. The goal was to evaluate the extent of the parameters’ influences to identify criteria for an EM Representative Volume Element in their respect.
Engineering & Environmental Justice: Protections, Hazards, and Technological Systems
Authors: Fisher Riley , Kee Ernest , Johnson David , Bui Ha , Mohageghegh Zahra
Published: February 2024

Citizens have become increasingly concerned about sharing risks and resources in a fair and equitable way — awareness is increasing that Environmental Justice (EJ) should play a greater role. Evaluating fairness in the design of different schemes involving exposure to harms is the domain of philosophy, psychology, and politics, well outside the domain of engineering practice — a discipline central in evaluation of potential for harms and cost of protections as dictated by requirements citizens place on deployed hazardous technological systems in laws. Still, engineers are often asked to support schemes with quantitative risk estimates for harms, such as in Cost Benefit Analysis (CBA). Within the narrow domain of deployed hazardous technological systems, engineers can provide limited support for EJ schemes when they ask for de minimis harm and thereby remove the need to make judgements on fairness (for harms).1 Empirical evidence with decades of Nuclear Regulatory Commission (NRC) regulation of risk management in the United States commercial nuclear power industry shows engineering practice can produce designs with effectively no risk for harm. The same experience indicates investors may be unwilling to fund such designs based on their expected return in competitive markets.
Simulation and Experimental Validation of a Microfluidic Device
Authors: Carvalho Violeta , Gonçalves Inês M. , Rodrigues Nelson , Sousa Paulo , Pinto Vânia , Minas Graça , Rodrigues Raquel O. , Teixeira Senhorinha , Lima Rui A.
Published: February 2024

The combination of microfluidic devices with cell culture methods has risen over the years due to their ability to replicate several diseases and test different therapeutic techniques. Unlike in vivo models, in vitro systems avoid ethical issues and allow researchers to control several physiological variables and mimic the physiological microenvironment at reduced costs. Along with the experiments, computational tools have also played an important role in assessing fluid flow and related phenomena. Nonetheless, to assure that the numerical outcomes provide a good approximation of reality, its validation is needed. Despite this step being usually disregarded, it is of great importance to accomplish it. Herein, a microfluidic device was developed by combining additive manufacturing with a silicone polymer for flow visualization experiments, and its numerical model was established by using Ansys Fluent software. The results were compared both qualitatively and quantitatively. A good agreement was obtained, which indicates the potential use of the numerical model in further studies.
Design Optimization of Hexacopter Frame Using Generative Design and Additive Manufacturing
Authors: Azhagan M. Thirumal , Shanmugam Ragavanantham , Khan Saquib , Lata Surabhi
Published: February 2024

This research paper presents an investigation into the use of generative design for the optimization of hexacopter chassis. Hexacopters, which are six-rotor aircraft, have a wide range of applications in areas such as aerial photography, search and rescue, and package delivery. The use of generative design in this study aims to improve the performance of the hexacopter chassis while reducing material usage and cost. The optimization process involved comparing various properties such as weight, factor of safety, von Mises stress, and material used. A static simulation was also conducted to evaluate the performance of the optimized chassis. The results of the study demonstrate that generative design can effectively optimize the hexacopter chassis for improved weight-to-strength ratio, an increased factor of safety, and reduced von Mises stress. Additionally, the study shows that the use of generative design can lead to a significant reduction in material usage, resulting in cost savings. The benefits of using generative design in this study include the ability to explore a large number of design options, optimize for multiple objectives simultaneously, and generate designs that are not feasible to create manually. Overall, this research provides valuable insights into the use of generative design for the optimization of hexacopter chassis and highlights the potential of this design approach for other aerospace and mechanical engineering applications.
Control of Corkscrew Swimming Locomotion of Soft-Millirobots in a Different Frequency
Authors: Scurry Jordan , Trinh Jessica , Bulang Christophe , Park Jungkyu , Kim Dal Hyung
Published: February 2024

Soft millirobots have been researched and studied extensively in recent years. In this paper, we investigate the locomotion of a small soft millirobot using a rotating magnetic field on the movement at various frequencies. To fabricate the soft millirobots, a combination of clear polymer and ferromagnetic particles is mixed together, and the head of the robot is magnetized using a permanent magnet. The fabricated soft millirobots are then placed in a chamber partially filled with water, where they are suspended by the water tension and float on the water’s surface. To validate the locomotion of the millirobots, the experimental setup involves placing the chamber with the millirobot into an enclosure surrounded by Helmholtz coils, which generate a rotating magnetic field. The soft millirobots are then subjected to a range of different frequencies, and their movements are observed and recorded. The findings indicate that the soft millirobots exhibit a variety of different types of locomotion in response to the rotating magnetic field. Also, we have demonstrated the feedback control experiment to validate its controllability.
Numerical Study of the Friction Coefficient of an Incompressible Laminar Flow With Solid Particles Over a Flat Plate
Authors: González Eliezer J. , Navarrete Luis E. , Ayala Orlando M. , Ayala Orlando F. , Ayala Manuel
Published: February 2024

This article presents a two-dimensional numerical study of the coefficient of friction of an incompressible laminar flow with particles over a flat plate. Various cases are presented varying parameters such as volumetric fraction (αp), relative particle size (Rsp) and Stokes number (Stk). The friction coefficients of particle-laden flows are compared to the friction coefficient of a particle-free flow. The results show that, during the initial development of the boundary layer, the presence of particles generates a higher friction coefficient. As the boundary layer further develops, the increment of the friction coefficient reduces. We found a linear relationship of the friction coefficient increment with respect to the volumetric fraction and the relative particle size. The peak of the friction coefficient increment occurs at the critical local Stokes number (Stkx) of one. For cases with low particle concentration, the effects of the particle presence can be disregarded and considered the flow as particle-free flow.
Toward Better Formability of Polymeric Materials in Single Point Incremental Forming: Effect of Process Parameters
Authors: Upcraft Clayton , Diefenderfer Rachel , Vanderwiel Chad , Ragai Ihab
Published: February 2024

Single-Point Incremental Forming (SPIF) is a process for low quantity production or prototyping of sheet products. It involves a sheet secured in a fixture, formed by the downward forces of a hemispherical endmill tool in a CNC mill. Multiple passes of the endmill tool deform the material until the desired geometry is attained. This study examines several combinations of SPIF process parameters, namely initial wall angle, feed rate, and step-down size, and their effect on the formability of the formability. Three materials were examined, polycarbonate (PC), polypropylene (PP) and polyvinylchloride (PVC). The following are the ranges in which the forming parameters were varied: feed rate from 1000 to 2000 rpm, wall angle from 10° to 30°, and step-down from 0.1 to 1.0 mm. The parameters that are held constant are the sheet material, tool material and diameter, and spindle speed. Sheets are formed by a 12.5 mm diameter copper 110 tool that is fixed in the spindle with no applied rotational speed, i.e., the spindle can rotate freely. It was found that the increase in wall angle results in local decrease of the thickness along the sides of the formed shape. Also, the results showed that feed rate has no significant effect on formability; however, an anomaly was observed that suggests there could be a threshold value after which thinning would be more pronounced. In all cases, the results showed heavy dependance on materials thermoplastic properties, particularly each material’s glass transition temperature.
Design and Development of a Low-Cost Prosthetic Leg for Below-Knee Amputations
Authors: Karibeeran Shanmuga Sundaram , Murugesan Pradeep Kumar , Jayakumar Jebin
Published: February 2024

Prosthetics are made with solid, biocompatible materials. Though the materials have a very good strength-to-weight ratio, they are not aesthetic or customized. Most of the time, it is made standard and is not lightweight for the user. Presently Metal 3D printing develops lightweight structures with the highest strength-to-weight ratio. In countries like India, the people have limited access to a good prostheses, as the prostheses is not affordable. The prosthetic limbs, to a certain degree, help amputees get back to their basic functional movement systems and help amputees develop better mobility and operate freely without depending on others. The design and fabrication of an improved and affordable prosthetic leg for people with below-knee amputation which will mimic the function of the natural leg using additive manufacturing technology. The additive manufacturing allows design freedom and customisation advantage. Autodesk Fusion 360 and Solid Works software was used for solid modelling and simulation and topology optimization was done using Autodesk Fusion 360. After measurement of the leg parameters, the measured data are fed into editable 3D software. The best design is chosen from the available designs based on ESAR foot (Energy storage and return foot). The present work based on topologically optimized design and ESAR foot was able to withstand the given loads and can be easily moved and thus chosen for further manufacturing and testing. This pave the way to develop a customer-oriented design and use 3D printing to make prosthetic legs that would look more personal and aesthetic.
A Numerical Study on Performance Enhancement of Locally Produced Axial-Flow Fans for Grain Drying
Authors: Estaquio Ren Paulo , Danao Louis Angelo , Lustro Julius Rhoan
Published: February 2024

Utilization of a flatbed dryer (FBD) as a postharvest technology particularly in grain drying is continuously thriving in the Philippines. Throughout the years, its drying chamber component has been upgraded continually to improve overall dryer efficiency. However, its mechanical component, the fan, which drives the heated air into the chamber was found to perform poorly compared to international commercial fans. For instance, locally produced tube-axial fans perform at most 30% in efficiency compared to commercial ones that run at least 67%. The design of one of the tested locally produced fans is investigated through numerical methods, specifically using computational fluid dynamics (CFD), for potential development to achieve higher efficiency. In this way, parametric investigations can be performed at a much less cost compared to the cost of conducting physical testing. A general CFD model is developed to replicate the local standard procedure of testing agricultural fans and blowers. Furthermore, the present study uses the model to examine the effects of varying three (3) blade parameters on the aerodynamic performance of a reference fan. These parameters are the blade count, the tip clearance, and the pitch angle. FBD requires a specific static pressure and volume flow rate (PS-Q) depending on its drying chamber’s capacity and type. A methodology is introduced to capture the optimal rotational speed that applies for both individual PS-Q and a range of static pressures.

The investigation yields the following results: the current design (CD) with 12 blades appears to be optimal near the static pressure of 250 Pa. The static efficiency of the fan is proportional to the no. of blades until CD where the performance metric started to plateau. Decreasing the tip clearance drastically enhances the performance of the axial fan, with tip clearance ratio, TR, of 2.13% providing the highest improvement. The increase reached as high as 37% change to the CD with a TR of 4.80%. An axial fan with a blade pitch angle of 33° shows to be the superior option for an FBD with 250 Pa static pressure requirement. For FBD with higher PS-Q requirements such as 375 Pa and 500 Pa, the CD with 27° blade pitch angle is appropriate to use. The current study shows a numerical method like CFD can be applied to perform a cost- and time-effective design optimization to turbomachines such as fans attached to the FBD. More importantly, the developed CFD model can be extended to be used to investigate other parameters of the axial fan or to develop the design of centrifugal fans utilized in Philippine agricultural technologies.
Recent Development and Limitations of Laser Patterned Riblet-Structures
Authors: Hartung Konrad M. , Löschner Udo , Mauersberger Stefan , Oehlert Karsten
Published: February 2024

The extensive research over the last decades on riblet structures has proven their potential for vicious drag reduction in turbulent boundary layers. For an efficient application for technical use, however, riblet foils or riblets manufactured by grinding lack adaptability. In contrary laser processing technologies nowadays enable the production of riblet structures, whose dimensions can be adapted to the local flow conditions. As experiential laser structures differ process-related from ideal design specifications, however, a reliable prediction tool is necessary. Within this study, riblet structures were manufactured using a novel high-rate laser structuring technology. The viscous drag reduction is model based predicted solving the Navier-Stokes-Equations for a Coeutte flow over characteristic surface structures. Comparing own samples with samples manufactured by the national leading institutions in the fields, the achievable drag reduction shows an ongoing improvement with a currently achieved maximum wall shear stress reduction in the range of Δτ/τ0 ≈ –5,6%. This corresponds to about 70% of the viscous drag reduction achieved by geometric ideal structures. The authors will point out that further improvements are hardly feasible as manufacturable riblet dimensions, especially the riblet tip width, are limited by laser-physical and process-related restrictions.
A Statistical Machine Learning Approach to Predict Residential HVAC Usage With Lagged Environmental Predictors
Authors: Baath Jashanjeet , Little Madelyn , Bhattacharya Anirban , Bandyopadhyay Arkasama
Published: February 2024

Wasteful energy uses, such as heating and cooling of unoccupied homes and rooms, inefficient appliances, and thermostat oversetting, contribute to at least 43% of total energy use in the residential sector. Accurate knowledge of domestic appliance-level electricity usage patterns can help energy modelers at electric utilities make informed decisions about residential load control and dynamic rate design. This study enhances an existing statistical machine learning approach to predict domestic appliance usage trends from overall energy consumption data obtained from Pecan Street Inc, by adding lagged environmental predictors. Five time-series on time-series regression models are explored, each with different combinations of lagged/current ambient temperature and relative humidity. The relative performances of the models are evaluated using the Akaike Information Criterion (AIC) value — a widely used model selection metric that determines the quality of a model by considering the data fit as well as model simplicity. Fifteen-minute interval data from two single-family detached homes in Austin, TX are used to demonstrate the methodology developed. Results indicate that while including lagged temperature and humidity as predictors enhances the quality of the energy consumption projections, there is not any significant difference among the models with various combinations of lagged/current environmental predictors.
Investigation of the Structural Behavior of Countersunk Bolts Under Multi-Directional Loading
Authors: Aksoy Tuğrul , Altıntaş Başar , Dilber Ahker Güneş
Published: February 2024

Tensile tests were performed by using the Tension/Shear Combined Loading (TSCL) test set-up at five different loading angles to understand the effects of combined loading on the countersunk bolts and compare the shear/tension interaction results with the failure envelopes from different references. Then the double shear tests were carried out so as to measure the bending effect on the failure of bolts and loading capacities were found as similar with the ones obtained from pure shear (90°) results of TSCL tests indicating that the bending moment effect on the loading capacities is unclear. Finally, a single countersunk bolt was tested on a special single lap shear joint by monitoring the bending load with two strain gauges attached on the bolt shank and a numerical simulation were performed on a finite element analysis model to verify the experiment. As a result, it is observed that the bending moment increases with the increasing load up to a certain point, and then gradually decreases as the load increases. Finite element analysis results were found as compatible with the results of this experiment. Both of the experiment and finite element analysis results demonstrated that the bolt bending affects the deformation process but does not have a significant effect on the load capacity of the bolt.
Computational Analysis for Effects on Hemodynamic Parameters Based on the Location of Cerebral Aneurysms
Authors: Reddy Garigapuram Prithvinath , Katore Srushti , Flamini Vittoria , Sahin Iskender
Published: February 2024

Cerebral aneurysms can affect about 1.5 to 5 percent of the general population. A ruptured aneurysm in the brain can result in severe consequences. The majority of brain aneurysms are seen in the anterior circulation near the bifurcation of an artery. Computational Fluid Dynamics is commonly used for conducting various analyses on the segmented images obtained from Magnetic Resonance Imaging, Magnetic Resonance Angiography, or Computed Tomography scans. This paper aims to analyze the different effects on hemodynamic parameters based on the locations of aneurysms. The most common locations for aneurysms in cerebral arteries are the Anterior Communicating artery, Middle Cerebral artery, and Internal carotid artery. In this study, four models were chosen for each corresponding location to determine and compare the hemodynamic parameters obtained from the analysis. To maintain homogeneity among the models, all of them had the same rupture status. The models were segmented and then processed in the ANSYS™ SpaceClaim software to produce idealized geometry for further analysis. They were further processed in ANSYS™ Fluent Mesh and Solver to create an idealized pulsatile blood flow. The hemodynamic parameters studied for this paper are Flow Velocity, Pressure Distribution, and Wall Shear Stress. The parameters are then compared to analyze how each location is affected.
Acceleration of Creep-Fatigue Damage of Ni-Base Alloy by Viscoelasticity at Elevated Temperature
Authors: Miura Hideo , Yasumura Ayane , Yamawaki Takuma , Kudo Takuto , Matsuda Hayato , Xu Le
Published: February 2024

The basic mechanism of the wide fluctuation of the creep-fatigue damage at elevated temperatures was clarified from the viewpoint of the loading strain rate. In this study, intermittent creep-fatigue tests were applied to a Ni-based superalloy, Alloy 617, and the degradation process of its crystallinity was monitored using an EBSD method. Creep-fatigue tests were performed intermittently at 800°C in inert Ar gas using small dumbbell-shaped specimens, and the degradation process of micro texture and local crystallinity of the alloy under the creep-fatigue loading was continuously observed in the same area in each specimen. IQ and KAM values and Schmid factor were applied to the crystallinity analysis. The main reason for the acceleration was found to be the accumulation of the residual strain during the unloading cycle and this accumulation occurred due to the activation of viscoelasticity of the alloy at elevated temperature. In particular, when the unloading time was shorter than the relaxation time of the material at that temperature, a next loading cycle started before the full relaxation of strain under stress control conditions. As a result, under this condition, therefore, the magnitude of the applied load and thus, creep-fatigue damage increased continuously cycle by cycle as a strong function of the period of the creep-fatigue load.
Improvement of Sensitivity and Selectivity of Graphene-Based Gas Sensor by Strain
Authors: Qiao Xiangyu , Yin Meng , Suzuki Ken , Miura Hideo
Published: February 2024

Graphene has been considered to be the most promising next-generation gas sensing material because of its large surface-to-volume ratio, excellent gas adsorption properties, and high carrier mobility. Application of strain to graphene was found to modulate its Fermi level, and thus, it is expected that the gas adsorption behavior of graphene is changed by strain, leading to enhanced sensitivities and selectivity of graphene-based gas sensors.

In this study, the effect of strain on the gas adsorption behavior of graphene was experimentally investigated. Monolayer graphene with high quality was synthesized by low-pressure chemical vapor deposition, and a graphene-based flexible gas sensor was fabricated on a polyimide substrate. The performance of the sensor was evaluated in situ in a homemade gas testing system. The good stability of the sensor under compressive strain was confirmed. A good sensitivity to NO2 and NH3 was observed in the fabricated sensor. Under compressive strain, the sensitivity of the sensor to 1-ppm NO2 was found to be increased by about 0.07%/%ε, and to 10-ppm NH3 was increased by about 0.11%/%ε, indicating the possibility of improving the performance of graphene-based gas sensors by strain.
Machine Learning-Based Fatigue Life Evaluation of the Pump Spindle Assembly With Parametrized Geometry
Authors: Wang Lizhe , Zhang Zhichao , Chen Min , Xie Junyi , Liu Fuyuan , Yuan Hang , Xiang Zhouyi , Yu Lingyun
Published: February 2024

Artificial intelligence-based fatigue analysis methods have gained considerable attention in recent years, but little research has been conducted on the fatigue behaviors of assembled structures, which involve numerous factors that impact structural fatigue life and complicated assembling associations in parameter selection. This paper presents a hybrid machine learning (ML) model-based evaluation platform for data-driven fatigue life analyses of a parameterized industrial pump spindle that considers the impacts of variable loads and characteristic design parameters. Firstly, the numerical fatigue evaluation is validated by comparing experimental and simulation results of spindle samples with a specific dimension. Secondly, datasets for training and testing are constructed to assess high cycle and low cycle fatigue lives of parameterized pump spindle assemblies under two real working conditions of cyclic start-stop and continuous running. The proposed hybrid ML method exhibits excellent overall performance for both running conditions, validating its accuracy and reliability. Additionally, the superiority of the hybrid method for fatigue evaluation of the assembly is confirmed through performance comparisons between single forward models. Finally, sensitivity-based parametric analysis is performed to interpret the model, revealing that pre-tightening load and diameter of the shaft seal have the most significant impacts on the fatigue properties under both cyclic working conditions. This work provides an efficient tool for quantifying the fatigue lives of parametrized spindles and contributes to the safety assessment in structural design and optimization.
ICE Performance Optimization With Double Supercharging With E-Booster
Authors: Capata Roberto , Calabria Alfonso , Donato Federico , Martellucci Leone
Published: February 2024

When it comes to the European Green Deal and Carbon Neutrality, we cannot ignore a fundamental element: the transport sector in the EU alone is responsible for 27% of greenhouse gas emissions and, between 1990 and today, aviation and maritime navigation have increased emissions by 50%. But the real lion’s share has been played by road transport, which alone contributes to 71.7% of emissions in transport, while railways have an extremely small impact, equal to about 1%. The present work aims to improve the performance of a commercial ICE through a double supercharging with eBooster to improve performance and reduce consumption, trying to reduce consumption, emissions, improve the overall efficiency of the vehicle and to make road transport sustainable. Thanks to this system it is possible to have a larger turbocharger that guarantees a greater power at high engine rotational speed without losing the torque at low rpm that will be guaranteed by the electric compressor. The operational conditions and parameters have been studied through a one-dimensional analysis via software. Through this simulation, different configurations were tested in order to obtain, in a preliminary way, the solution that maximizes the performance of the engine, thus saving in terms of costs and time on experimental tests. All simulations are carried out at full load with the same stoichiometric ratio of the mixture and ignition time, within a speed range between 2500 and 8500 rpm. Initially, a model with turbocharger available on the market has been studied, simulated and proposed, operating with good efficiency at a higher engine rotational speed. The choice to use a commercial compressor has been dictated by the possibility of replicating the operational maps of the device and using them in the simulations. Once this phase was optimized, it has proceeded to study which electrical device to introduce. After the addition of the electric compressor, an optimization of the system has been conducted. This simulation allows to compare different dimensions of the connection (piping, manifolds, valves, etc.) trying to exploit the pressure waves that are inside generated to improve the filling of the engine. Finally, through the analysis of the pressures inside the intake and exhaust ducts and the cylinder internal pressure, an ideal timing for this system has been set. Through the carried-out simulations, it was possible to underline that the larger turbocharger increases the engine efficiency, both from the point of view of power and fuel consumption, and thanks to the electric compressor it is possible to have a favorable torque curve at low rotational speed.
Power Take-Off Design Study for a Small-Scale Oscillating Surge Wave Energy Converter for Powering the Blue Economy Applications
Authors: Wills Jackson , Tom Nathan , Sirnivas Senu
Published: February 2024

The power take-off (PTO) is an integral part of wave energy conversion, and the design process is nontrivial. Better PTOs, and better processes for selecting and designing PTO architectures for various applications, would benefit devices that assist in powering the blue economy by decreasing time and money spent on PTO design and increasing the overall energy capture performance of these devices. This paper chronicles the selection process of a PTO for a small-scale surge-type wave energy converter (WEC) for the purpose of informing future PTO selection processes. Three PTO architectures are evaluated in WEC-Sim: a hydraulic check valve PTO, a hydraulic active valving PTO, and a directly electrified PTO. Simple models of each PTO are constructed. Because a model for the small-scale device was initially unavailable, the PTOs are simulated on a large-scale device. The results are scaled down using Froude scaling and compared to results from directly simulating a small-scale model. Strong assumptions are made because this work is early in the design stages, and a coarse look at PTO options was desired. Specifically, the effectiveness of controls is investigated, along with the efficiency of energy conversion. However, energy capture is only part of the consideration; there are also logistic concerns to be considered when selecting a PTO. For example, components for large-scale WECs are so large and expensive that it may make sense to custom-build PTO components, but small-scale WECs would benefit from off-the-shelf availability because the cost of customization would be a significant portion of the total capital cost of deployment at a small scale. Submersible, off-the-shelf components are much easier to source for hydraulic PTOs. Because of highly effective controls, efficient energy conversion, and availability of marine-grade components, an active valving hydraulic PTO is selected for this small-scale surge-type WEC.
Damage-Induced Softening of the Sclera: A Pseudo-Elastic Modeling Approach
Authors: Colmenarez Jose A. , Zhai Yingnan , Mendoza Valentina O. , Dong Pengfei , Nunes Kenia , Suh Donny , Gu Linxia
Published: February 2024

The biomechanical properties of the sclera such as the stiffness, anisotropic behavior, and non-linear stress-strain relationship have been extensively investigated for the pathogenesis study of ocular diseases. Even so, scarce mechanical investigations have been conducted on the damage in the sclera when subjected to large and repetitive deformations. Hence, the aim of this study is to quantify the extent of microstructural damage of the posterior and anterior sclera under loadings beyond the physiological range, through mechanical testing and model fitting. We performed uniaxial mechanical tests on scleral strips dissected from African green monkeys. Samples were subjected to strain-driven cycles of 5%, 10%, 15%, and 20% to evaluate the damage behavior commonly known as the Mullins effect. Experimental results showed qualitative changes in the stress-stretch curves when higher loading cycles were applied. A pseudo-elastic model accurately captured the curve trends across all tested samples, as indicated by a determination coefficient above 0.96 and a subsequent finite element analysis (FEA) validation. Damage evolution and resultant permanent set demonstrated that considerable microstructural failure was attainable at small strain levels, and that the inherent plasticity had a similar contribution to stress-softening as the Mullins effect. Computed material and damage properties are expected to provide a broader understanding of the underlying mechanisms of ocular diseases and the development of more effective approaches for their treatment.
Piezoelectric Blood Pressure Sensor for Implantable Devices
Authors: Katey Bright , Voiculescu Ioana , Li Fang , Untaroiu Alexandrina
Published: February 2024

The paper presents the model and simulation of a piezoelectric pressure sensor intended to be used for a ventricular assist device for children and adults affected by the Single Functional Ventricle Congenital Heart Defect (CHD). This syndrome is the condition of the heart, where one of the ventricles, typically the right one, is either underdeveloped or not developed at the time of birth. To address this problem, we propose a mechanical cavo-pulmonary assist device with a dual-propeller pump, which is self-expanding. This is implanted into the total cavopulmonary junction (TCPC). The propellers’ scope is to regulate the blood flow directed to the lungs. The pressure sensor is an integral component of this sophisticated biotechnology device. It will be used to control the blood pressure by sending a signal to the motor and propeller pump to adjust its operating condition when the blood pressure is below the physiological levels. The pressure sensor is designed from a piezoelectric material which gives it a self-powering functionality.

To enhance the sensitivity of the pressure sensor, arrays of micro-pillars will be fabricated on piezoelectric materials. Finite element analysis (FEA) with Ansys was used to model the pressure sensor, without and with micro-pillars and we demonstrated that the micro-pillars have the capability to increase the pressure sensor sensitivity.