bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Leaf Vein Structure on Condensation Behavior of Vertical Copper Plate: An Experimental Approach
Authors: Bappy Md. Omarsany , Aziz Raihan , Shuvo Abdul Aziz , Morshed A. K. M. M. , Paul Titan C.
Published: January 2022

Condensation is one of the most effective ways of transferring heat and it is widely used in power generation units, refrigeration and air-conditioning system, water desalination systems, petroleum industry, chemical production plant, electronics thermal management, etc. Condensation heat transfer depends on many factors including surface material, surface morphology, degree of sub-cooling, characteristics of the fluid used, presence of impurities, etc. Among different properties, surface modification is an easy and effective way to enhance the condensation heat transfer behavior. Condensation behavior on coated, hydrophilic, hydrophobic, sine shaped groove, etc. has already been researched comprehensively but the effect of wedge shaped groove (mimic to leaf vein structure) on copper plate is yet to be explored. Surfaces of some plants and animals have natural ability to harvest water from the environment in an effective and efficient way. In this research, it is tried to mimic the leaf vein structure (wedge shaped groove) on copper plate and then carried out condensation heat transfer experiment. Due to fabrication of wedge shaped groove on copper plate, contact angle and droplet parameters like droplet size, droplet frequency, droplet growth rate, droplet coalescence rate, droplet drainage rate, etc. are affected. Condensation heat transfer behavior like condensation heat transfer co-efficient, contact angle, droplet diameter, droplet growth rate, droplet frequency, sliding velocity of condensate, etc. have been studied for both flat and wedge shaped micro grooved copper plate in this article. Due to the fabrication of leaf vein structure on copper plate it is observed that contact angle has increased significantly and active nucleation site of droplets has decreased which enhanced dropwise condensation. Falling droplet diameter and surface rejuvenation time has increased for modified copper plate. This larger diameter droplets slided faster in wedge shaped copper plate compared to flat copper plate due to gravity. But the condensate drainage rate is less for modified copper plate due to the increment of falling droplet diameter and surface rejuvenation time. A comparative study of droplet parameters and condensation heat transfer parameters have also been shown in this article. It is observed from the droplet nucleation process, coalescence rate and droplet drainage process that dropwise condensation is more stable in case of wedge shaped groove copper plate compared to flat copper plate thus the surface modification is effective in condensation process of copper plate like nature. Results obtained from this condensation heat transfer experiment shows that heat transfer co-efficient of wedge shaped groove copper plate is 20–50% greater compared to flat copper plate. Plausible reason of this enhancement has been broadly discussed in this paper.
Process Prediction for Repair of High-Speed Train Wheelseat Axle by Extreme High-Speed Laser Material Deposition (EHLA)
Authors: Li Tianci , Zhang Lele , Chen Geng , Schopphoven Thomas , Gasser Andres , Poprawe Reinhart
Published: January 2022

Due to the surface scratch, wear or cracks, the performance and dimension of high-speed train wheelseat axle reduce to a level that cannot meet the design requirement after a period of service. Reasonable and efficient maintenance of those worn and valuable parts yields both economical and ecological benefit. In this study, we focused on the feasibility of using extreme high-speed laser material deposition (EHLA) for the repair of full-scale high-speed train wheelseat axle. To this end, AISI 4140 powder particles were selected as additive materials, and suitable process parameters were determined for the production of reduced test pieces. To investigate the possibility of transferring the process parameters determined through reduced piece testing to the full-scale wheelseat axle, finite element (FE) analyses were conducted. In these analyses the temperature distributions for different diameters of substrate with same process parameters were compared, and the results indicate that the process parameters obtained from the reduced sample studies can be transferred to the repair of full-scale axles. On the other hand, however, to consider the effects of thermal history on the clad properties, supplementary heating treatment should be carried out during the EHLA process.
Analyzing the Effects of HVAC Equipment Uncertainty in Building Energy Modeling for Professional Environment
Authors: Birega Miseker , Khazaii Javad
Published: January 2022

The concept of evaluating the effects of uncertainty in energy modeling has been discussed in the past few years widely in academic environment. These evaluations have been mainly concentrated on architectural components of the buildings. Little effort has been done to investigate the effects of the uncertainty in the mechanical systems of the building on the energy modeling outcome. There has been a barrier against implementing the findings of the academic research into real world professional architectural and HVAC engineering design. The fact is that majority of the academic research in the field of uncertainty is done with software that are popular in academic environment but are not the choice of professional engineers when performing real life building energy modeling. To help improve this disconnect between the academic and professional realm, this effort introduces a supplemental software that is written on a free platform (Python) and can be interlocked with eQuest that is used for energy modeling by professional firms. Using this supplementary program helps engineers to start with mechanical parameters such as efficiency of boilers and efficiency of chillers as it has been used in design document, and change the values associated with these efficiencies within the allowed tolerances by testing standards. The study finds that the developed supplementary software can help specifying close to 6% range for energy consumption of a typical four-story office building, which highlights the supplementary software ability to improve current state of professional energy modeling practice.
Study of Vapor Condensation on a Vertical Porous Microgroove Copper Plate
Authors: Aziz Raihan , Bappy Md. Omarsany , Morshed A. K. M. M. , Paul Titan C.
Published: January 2022

Analysis of condensation of vapor on metal surfaces has been in the center of enormous attention due to its omnipotent application in numerous industrial processes. So far condensation on smooth, coated, hydrophobic, hydrophilic, grooved surfaces has been researched comprehensively but the effect of porous surface specially the combined effect of porosity and micro grooved has not been fully explored. In this study, condensation heat transfer performance is analyzed for vertical porous micro grooved copper surface and the change of performance due to varying numbers of pores on the modified micro grooved surface are compared with micro grooved surface with no pores. During condensation vapor releases latent heat and forms condensate droplets throughout the suitable nucleation sites on the surface. To enhance the condensation heat transfer it is preferred to come up with a modified condensation surface which can effectively hamper the film layer generation on the different regions of the surface as a result paves the way for new nucleation sites to develop. And increased nucleation site brings higher condensation rates. In our study, a unique experimental setup is constructed consisting of a cooling chamber and a vapor chamber separated by the porous micro grooved copper surface. Steam is generated by a mini boiler and fed into the vapor chamber. Porous opening on the test surface provided continuous liquid flow from cooling to condensation chamber in a controlled way. Liquids through the opening breaks the layer developed at very early stages and prolongs the drop wise condensation (DWC) time span and helps effectively to reduce the chance for droplet to stay on the surface and coalescence. Wedge pattern micro grooves are inscribed on the test surface providing the additional aid for the drainage of the droplets. As the number of porous opening changes various droplet parameters like droplet sweeping frequency, droplet diameter are subjected to change over time. It also affected the condensation heat transfer parameters to a great extent. A comparative analysis of condensation heat transfer parameters and droplet parameters due to the change of number of pores compared to no pores are carried out and shown with pictures of test surfaces captured real time during the experiment. Performance of the proposed surface is compared with that of the other surfaces based on the condensation rate and condensation heat transfer coefficient. Experimental results indicate heat transfer performance can be enhanced by 30–35% due to introducing the porous opening on the modified surface. The experiments are conducted under low steam pressure conditions.
Assessment of Low and High-Fidelity Turbulence Models for Liquid Metal Flow Predictions
Authors: Bhushan Shanti , Elmellouki Mohammed , Walters D. K. , Gorman M. , Hollrah B. , Hassan Y. A. , Mezrari E. , Obabko A.
Published: January 2022

The predictive capability of RANS, hybrid RANS/LES and LES turbulence models are assessed for low-Pr flows involving complex flow features expected in engineering applications, such as forced convection, buoyancy, shear, reattachment, and recirculation. The models are tested for three test case vertical channel, vertical backward facing step with heated wall and rod bundle lattice cases for Pr ranging from 0.002 to 2.0. k-ε based model is used for RANS, partially averaged Navier Stokes (PANS) for hybrid RANS/LES and dynamic Smagorinsky model for LES. The channel and backward facing step cases show that LES performs the best followed by PANS and RANS. The RANS model performs reasonably well for flows with strong buoyant forces, which augments the mean flow more than the turbulent features. But for moderate buoyant flow condition, which augments turbulence characteristics and associated diffusion, RANS models do not perform well. Considering both the computational cost and accuracy, the PANS provides a good compromise between RANS and LES.
A Two-Dimensional Parametric Computational Framework for Finite Element Heat Transfer Analysis of Self-Field Magnetoplasmadynamic Thrusters
Authors: Berry K. Joel
Published: January 2022

“SELF-FIELD” magnetoplasmadynamic (MPD) thrusters are low-thrust electric propulsion space-systems leveraging magnetohydrodynamic (MHD) principles for plasma acceleration and high-speed exhaust velocities. MPD thrusters produce high specific impulse and are suitable for long duration interplanetary space missions without externally applied magnetic fields. Alternatively, the applied electric field passing through the electrically conductive ionized plasma propellant generates a current (J→) across the plasma. The plasma current subsequently generates a “self-induced “ perpendicular magnetic field (B→) that interacts with the applied electric current field to induce an electromagnetic Lorenz thrust force (i.e., F→=J→×B→) and thereby producing electromagnetic and electrothermal acceleration. The work herein provides a 2D MPD computational framework for parametric property modeling, for automatic finite element parametric mesh generation, for the specification of unique gradient based and MPC (Multi-Point Constraints) boundary conditions, for the coupled, non-linear, transient, compressible finite element analysis that include a fluid/solid conjugate heat transfer thermal electromagnetic formulation, and for the flexible display of post-processing results.
Preliminary Investigation on the Acoustic Characteristics of Turning Processes
Authors: Kerner Scott , Deabenderfer Zachery , Korn Katherine , Ragai Ihab , Liao Yabin , Loker David
Published: January 2022

This research aims to characterize the turning process using acoustic signals (AS) for the purpose of remote condition monitoring. This will allow for non-invasive machine monitoring, reducing costs and interference in the machining operation. Various combinations of process parameters were investigated, including spindle speed, depth of cut, and feed rate. The machining parameters used herein were closely matched with those of a milling operation utilized in previous research. The intent is to investigate the use of AS to monitor and differentiate multiple machines around the shop floor, running simultaneously. The feed rates for the turning process were mapped to mimic those for the milling process.

A spherical 32-microphone array was utilized for data collection with a sampling rate of 48 kHz. Frequency and time-domain characteristics were utilized to find distinguishing features of the AS. It was found that turning speeds produced noticeable differences in the observed peaks in the frequency content of the signal, providing a means of determining spindle speed from AS. Additionally, time-domain characteristics yielded discernible differences for both feed rate and depth of cut. An increase in the rms value was observed as the material removal rate (MRR) of the machining process increased. The results suggest that a combination of both frequency and time domain characteristics may be used to distinguish the process parameters. Feature extractions linked to MRR and the time/frequency domain can be used to expand AS monitoring to other process parameters and machines. Finally, a time-domain machine learning classifier was utilized for predicting the depth of cut. The Fine K-nearest neighbor (KNN) classifier was determined to provide the best results, with a prediction accuracy of approximately 62%.
A Framework for Spatial 3D Collision Models: Theory and Validation
Authors: Sværen Terje , Nygård Bård Inge , Impelluso Thomas J.
Published: January 2022

This project puts forth a framework for spatial collision models for bodies. The framework leverages a new method in dynamics to calculate the relevant post-collision trajectory in 3D space. The new method exploits Cartan’s notion of moving frames and places frames of reference on all moving (and colliding) bodies. Next, it exploits Lie group theory SO(3) and its associated algebra, so(3), to relate such frames to each other. Finally, it exploits a compact notation to streamline the mathematics. This project presents a numerical validation of the results using MSC Adams and compares the rotation and translation values of the bodies with those found using the new method. ThreeD web pages display the results using WebGL.
Energy Storage and Stabilization Simulation of Floating Wind Turbines
Authors: Aarmo Martinus K. , Sivesind Magnus N. , Bartl Jan Michael Simon , Lande-Sudall David , Impelluso Thomas J.
Published: January 2022

The goal of this project is to research how to use inertial disks to stabilize floating windmills and also store excess energy. The energy extracted can be delivered after the wind subsides. The gyroscopic effect will ensure stability. The project will deploy the Moving Frame Method (MFM) to analyze the kinematics and kinetics of the system. The MFM exploits aspects of Lie Group Theory in place of vector-based dynamics. It leverages the work of Elie Cartan to model all moving bodies. Finally, it deploys a compact notation for both 3D and 2D. This project introduces relevant forces acting on the system, implementation of an improved numerical integration scheme, and an accounting of mooring lines. The project defines the initial spin of the disks as a prescribed variable. We use the Runge-Kutta method for numerical integration of the equations of motion, and update the solution with an assumed correction for the rotation matrices that exploits Rodriguez’ formula. Afterwards we create a simulation by creating a port from Matlab to the Web Graphics Library and Three JS using Javascript.
Elastoplastic Behavior of SLA Resins in Compression
Authors: Baumgarner Julia , Piovesan Davide
Published: January 2022

Additive manufacturing is a growing field. One of the most common types of 3d printing methods is stereolithography. While the tensile properties of many stereolithographic resins are known, the compressive properties are not publicly available. In this paper, four types of resins that from Formlabs® are tested under compression to estimate their mechanical properties. Testing was performed on Clear, Tough, Durable and High Temperature resins with and without post processing. Post processing was performed in a customized curing oven following direction from the resin manufacturer. After testing, it was found that the Tough and Durable resins performed similarly when green, but the curing process stiffened the Tough Resin. Clear and High Temperature resins performed similarly after curing, whereas the High Temperature resin behaves more like an elastomer when green.

We estimated the tangent modulus of the stress-strain curve using a Polynomial fitting and were able to separate the elastic modulus from the viscous modulus. We found that the viscous modulus is non linear and depends upon the velocity of the test.

The test presented here are the first comparison of different types of Formalab resins under compression and can shed some light on the anisotropic behavior of many of these resins.
Effect of Inlet Geometry on Flat Plate, Film Cooling Effectiveness From Shaped Holes
Authors: Wang Hanlin , Wright Lesley M.
Published: January 2022

Modern gas turbine engines require a sophisticated cooling system design to achieve higher power output and efficiency. In this study, systematic tests were carried out to evaluate the potential effect of non-cylindrical inlet geometries on the performance of laid back, fan-shaped film cooling holes using the pressure sensitive paint (PSP) measurement technique.

A laid-back, fan-shaped hole outlet design in open literature was selected as the basis for the film cooling holes in this study, with varying inlet geometries. “Racetrack” shaped inlet geometries with aspect ratios of 2:1 and 4:1 were tested along with traditional cylindrical inlets. The coolant flow conditions range from blowing ratios of M = 0.3–1.5 and density ratios DR = 1 and 2. The mainstream turbulence intensity is fixed at 6%.

Test results show that the shaped inlets can provide a higher area-averaged film cooling effectiveness, η, over the traditional cylindrical inlet design using the same amount of coolant. For the 2:1 inlet, an advantage of 20% higher η could be maintained for DR = 1, while for DR = 2 this advantage is reduced to 10%. For the 4:1 inlet, when the coolant momentum flux ratio I < 0.5, a similar or slightly higher improvement can be obtained, but when I > 1, the advantage diminishes with the growing momentum flux ratio to approximately 5%, at I = 2.25. In terms of discharge coefficients, the 2:1 inlet geometry is similar to the cylindrical inlet under most flow conditions. For the 4:1 inlet, its discharge coefficient is 2–5% lower than the fan-shaped holes with a cylindrical inlet, under the same flow conditions.
Sit to Stand Gait Trainer: Modulation of Lift Force via Elastic Network
Authors: Smith Jordan , Felmlee Robert , Crowe Mary , Piovesan Davide
Published: January 2022

Falls in nursing homes and hospitals are common occurrences and a significant problem in the healthcare industry. A large number of accidents occur during sit to stand transitions. Not only patients with lower limb weakness are prone to injury after falls, but the healthcare workers are prone to musculoskeletal injuries when helping individuals transitioning from sitting to a standing position. Sit to stand devices are currently being used in hospitals, but the current models are expensive and do not allow patients to use any of their lower body strength in the process. We proposed the design of a device adjustable to each user in order to maximize the use of their own strength and allow them to stand up comfortably and safely. The design is innovative, customizable, and enables the device to be used as a walker as well. We propose an actuation system that combines a set of elastic bands to modulate the force used for lifting and gravity compensation. The system comprises of two sets of rubber bands that can modulate the force profile as a function of the height of the seat. Furthermore, this device offers a potential solution to the disproportionate number of workers injured in the healthcare field during lifting and assisting patients during the sit to stand transition.
Experimental Investigation on the Effect of Condenser Length on the Heat Transfer Performance of an Ω-Shaped Cryogenic Axially Grooved Heat Pipe
Authors: Li Yongyan , Li Nanxi , Dong Deping
Published: January 2022

In order to optimize the coupling between the heat pipe and the cold source, and to study the influence of different condenser lengths on the performance of heat pipes, a nitrogen charged Ω-shaped axially grooved heat pipe with a gas reservoir working at ambient temperature was designed based on the heat transport demand for space cryogenic applications. The supercritical startup performance of the heat pipe in the liquid nitrogen temperature zone and the heat transfer performance under different condenser heat fluxes are tested. The experimental results reveal that the heat pipe with gas reservoir starts up rapidly, and the length of the condenser has no effect on the start-up rate. When the filling rate of the heat pipe is 100%, for a given operating temperature under the same heat load, with the decrease in the condenser length, the heat pipe requires a greater degree of subcooling at the condenser to dissipate heat, so the thermal resistance of the heat pipe increases. Meanwhile, the heat transfer capacity will decrease. It is because the decrease of capillary pressure due to the increase of the contact angle of the working fluid on the wick surface. At a given operating temperature and the same length of the condenser, when the heat load increases, the heat transfer coefficient of evaporator and condenser will increase, so the thermal resistance of the heat pipe will decrease accordingly.
Damage Tolerance Analysis of Wing Fuselage Interface in BWB Aircraft Design
Authors: Bakshi Ashok K. , Dattaguru B.
Published: January 2022

As conventional aircraft manufactured based on tube and wing concept came to design saturation stage, aircraft industry is looking for totally new efficient configurations. In this regard the BWB (Blended Wing Body) configuration offers a paradigm shift in the aircraft design. This design provides aerodynamically efficient, low carbon emission environmentally friendly benefits and can adopt advanced technologies like laminar flow, jet flaps and distributed propulsion and ease of flight controls. However, despite these benefits, the BWB is yet to be produced for commercial use due to several challenges. To benefit the airline operators and optimize profit, both passenger and cargo options are suggested to make a multi-role version. This paper tried to bring out alternate proposition in BWB design highlighting design challenges that have hindered the actual production of a viable BWB passenger aircraft with multi-role cargo option. Even though the fully composite BWB concept is three decades old, it has not gone into production due to issues related to product quality and reliability of composite material apart from high costs in damage tolerance design which will be addressed in this paper.
Introducing Students to Cogeneration Systems Using a Design and Analysis Software in Energy Systems
Authors: Naman Yasin , Kowalski Gregory J. , Zenouzi Mansour
Published: January 2022

An interactive software package is presented for evaluation and design of hybrid co-generation systems. This software with user-friendly interface is introduced to replace a previous graphical summary of a simulation of a Brayton Cycle-fuel cell cogeneration system in an introductory graduate course in the Energy Systems program at Northeastern University and an advanced undergraduate course at Universidad de América. The description of the software package code and how it is implemented is outlined. The code is a MATLAB simulation of a hybrid co-generation system including the analysis of the solid oxide fuel cell and reformer. While there was a small sample of students in 2020–2 class and special circumstances related to the COVD-19 restrictions, there is evidence that the software package was an improvement over the previous methodology. A written tutorial and YouTube interactive guide for students to download the software considered as an improvement by the student feedback survey.
Design of a Carbon Fiber Ankle Foot Orthotic With Optimal Joint Stiffness
Authors: Koch Aaron , Richardson Brandon , Schell Daniel , Piovesan Davide
Published: January 2022

An Ankle Foot Orthosis, or AFO, is a device used in human rehabilitation to support lower extremities. The device is similar to a brace that is capable of maintaining the stability of a joint while storing some elastic energy to help lifting the legs at the ankle.

The main challenge for this design is to determine the optimal stiffness of the device and how such stiffness comes from the distribution of the stiffness at the joints. Furthermore, the device must be stiff enough for athletic play, but be comfortable for clinical scenarios.

We performed a set of experiments on a commercial AFO made of carbon fiber. The angles at the ankle and toes were measured during self-paced walking together with the interaction force between the shin and the AFO. Based on such measurements, we estimated the total rotational stiffness of the device and the distribution of stiffness at each joint. A 3-point bending test following ASTM D7264/D7264M-15 standard was used to evaluate the stiffness of the material produced by a Mark II 3D printer capable of printing long fiber composite. After the optimal printing parameters were selected to obtain the desired stiffness of the material, a finite element analysis was performed to design the AFO geometry to match each single joint stiffness.

This customized procedure can provide the design specification of a device so to produce the best athletic performances still maintaining comfort.
Conjugate Mixed Convective Flow of Gallium in a Partially Vented Square Cavity in the Presence of a Rotating Cylinder
Authors: Faiaz Abrar Nur-E , Priam Shadman Sakib , Shahriar Asif , Mamun Mohammad Arif Hasan
Published: January 2022

The aim of this research is to investigate mixed convection heat transfer properties in a ventilated square cavity with a heated cylinder. The cylinder is positioned in the cavity’s middle. The cylinder has been observed in both stationary and rotating (counter-clockwise and clockwise rotating directions) conditions. Furthermore, the cavity’s wall is believed to be thermally insulated along with a solid wall on the left side. Flows (Liquid Gallium) enter the cavity through the inlet at the top of the right wall and exit the cavity through the bottom of the right wall. The current research simulates a real-world device, such as liquid-cooled electronic equipment with a heating part or a heated oven. The effects of the cylinder diameter and rotational direction of the cylinder in the cavity are highlighted. The coupled equations of mass, momentum, and energy govern the mathematical model, which is solved using a Galerkin weighted finite element formulation. The current study takes into account a broad range of relevant parameters, including Richardson number, cylinder diameter, and cylinder rotation direction. Divers kinds of results are simulated using these parameters such as streamlines, isotherms as well as heat transfer rate by calculating the average Nusselt number on the hot cylinder wall and bulk fluid temperature of the cavity. For pure mixed convection (Ri = 1), the clockwise spin direction gives 10% more heat transfer rate than the counter-clockwise spin direction. The heat transfer rate is an increasing function of Hartman number and a decreasing function of cylinder diameter. In the case of pure mixed convection (Ri = 1), increasing cylinder diameter from o.1L to 0.3L causes the heat transfer rate to reduce at a rate of 57.7%, and increasing the Hartman number from 0 to 100 causes the heat transfer rate to increase at a rate of 11.1%.
Multiscale Modelling of Multifunctional Composites: A Review
Authors: Suresh Babu Sandeep , Mourad Abdel-Hamid I.
Published: January 2022

Multi-scale modelling is a cornerstone for the relatively new class of hierarchical materials which can perform multifunctional tasks, owing to their electrical, magnetic or thermal properties. Careful design strategies are to be devised, in-order to maintain their multi-functionality over the expected range of operation. In this study, we focus on these materials, which can be manufactured using a specialized technique of additive manufacturing, known as fused deposition modelling (FDM), owing to its flexibility and compatibility, working with polymer based materials. A review has been made on the various parameters affecting the manufacturing process, and how these variations can affect the properties of the end product. Future research directions are also pointed out, including stimuli responsive printing technique, popularly known as 4D printing and integration of neural networks into the manufacturing process which can improve the overall design lifecycle efficiency. This can involve autonomous production of test specimen, and revert back the data for model improvement, thereby enhancing predictive capabilities. The major focus of this work is on how we can use our current knowledge and techniques in the design of efficient and effective multifunctional composite materials from the bottoms-up approach.
A Study on the Onset of Secondary Hydriding in Defective Zr-2 Fuel for Boiling Water Reactors
Authors: Enivweru Doctor , Wang Qingyu , Ayodeji Abiodun , Moussa Hassane Ayouba
Published: January 2022

One of the most common threats to the integrity of reactor fuel cladding is the geometric imperfections such as the missing pellet surface (MPS) that produces a remarkable surge in the local fuel-clad gap. The cooling water could occupy this gap leading to secondary hydriding (SH) and hydrogen embrittlement. Most studies on this subject have identified extensive radiolysis in boiling water reactors (BWRs) to be responsible for hydrogen evolution during accident conditions. However, the quantitative determination of hydrogen and how it affects zircaloy-2 during normal reactor operation has not been given adequate attention. To bridge this gap and to better predict the onset of cladding failure, this study investigates secondary hydriding and its characteristic phenomenon in a fuel cladded with zircaloy-2. Multiphysics model is used to model diffusion of heat and hydrogen, then the effect of an intermediary porous/non-protective oxide layer and the impact of dose rate from different types of radiation are studied. The contributions of the source term due to radiolysis of neutrons (n), gamma (γ), alpha (α) and beta (β) radiations are also considered. Results showed that neutrons, having a maximum dose rate of 39.9 kGy/s accounts for over 99% of ZrH precipitation in a UO2 fuel with MPS. The effect of oxide (ZrO2) thickness in SH, and the derivative of oxide thickness are also discussed.
Structural Reliability Estimation of Steel Hall Exhibiting Random Mechanical Parameters
Authors: Bredow Rafał , Kamiński Marcin
Published: January 2022

The main idea behind this work is computational verification of the FORM reliability indices for industrial steel halls with the use of Stochastic Finite Element Method. This approach is implemented in the computer algebra software thanks to an application of the iterative generalized stochastic perturbation method. Structural static and dynamic responses of typical steel hall are numerically determined in the context of Serviceability and Ultimate Limit States. They are computed using BFGS algorithm for large deformations, HHT method in case of structural vibrations and Euler-Bernoulli beam theory available all in the FEM system ROBOT. Expected values, coefficients of variations as well as reliability indices are found while randomizing Young modulus of the steel according to Gaussian distribution. This randomness is selected due to the fact that arbitrary value is recommended for all steel types by most of designing codes while material engineering results show that this parameter exhibit remarkable differences due to the alloy components and their processing. Static equivalent of the wind pressure in civil engineering design of such structures is found to be quite efficient not only in deterministic approach but also in the context of reliability analysis.
An Exploration of X-Vectors for Damage Detection and Identification
Authors: Hom Kyle , Beigi Homayoon , Betti Raimondo
Published: January 2022

Damage identification for structural health monitoring (SHM) is explored through applying the x-vector speaker recognition technique in the structural domain. Using the progressive damage tests from the Z24 Bridge Benchmark dataset, a time-delay neural network (TDNN) is trained as an acoustic model to classify the provided global damage scenarios. The outputs of a pre-final layer, called x-vectors, are used as damage-sensitive features for identification of damage presence and mechanisms. Since the developed TDNN has learned the underpinning dynamics of the damage mechanisms in the Z24 tests, we apply it as a basis for damage identification problems tangential to the Z24 progressive damage classification task. Transfer learning and domain transfer are investigated via application of the developed TDNN towards local damage identification of the Z24 Bridge, and global and local damage identification for the unseen LANL SHM Alamosa Canyon Bridge, UC-Irvine Bridge Column, and Bookshelf studies. Supervised and unsupervised classification techniques are explored to assess this method, and strong results in damage detection are obtained for these SHM problems.
Design the Future Activities (DFA): Framework to Develop Case Studies to Incorporate Deep Understanding of the Coupling Between Technology, Society and the Future
Authors: Ali Hadi
Published: January 2022

Although engineering education research is concerned with preparing future engineers, the integration of future trends in technology with the engineering curriculum has been limited. This paper utilizes the Design the Future Activities (DFA) framework to provide guidelines for developing case studies in engineering design education to address the need for design for the future. The DFA as a framework systematically identifies and integrates emerging areas of research and technologies, such as artificial intelligence, into the teaching of engineering design. It links the contents of its three levels (Understanding technology analysis and system integration; Making a value chain, and Developing responsible innovations) with effective pedagogy for each level. Here, case studies are discussed in depth as an effective pedagogy for the second and third levels of the DFA framework. While engineers continue to be creators and influencers of such technologies, the lack of understanding of the impact of their own technologies continues to cause an imbalanced innovation landscape, in education and in the workplace. The new, revived design education approach should be attempted, assuming that educators will systematically anticipate the future and recalibrate the curriculum.
Effect of Heat Stabilization and Solid Lubricants on High Strain Rate Response of Polyamide 6
Authors: Rodriguez Luis Rafael Miranda , Shah Neel , Haynes Aisha S. , Lim Calvin , Stout Christopher G. , Recchia Stephen S. , Pelegri Assimina A.
Published: January 2022

In this research, high strain rate impact testing of polyamide 6 composites (PA6) with different inclusions and processes is performed to assess the material response to increasing impact loads. Testing groups are divided into four categories depending on their inclusions and process: no inclusions, heat stabilized with no inclusions, oil & Molybdenum disulfide (MoS2), and glass fiber solid lubricant. Computational analysis is performed to obtain material properties such as dynamic modulus and stress-strain behavior from Split Hopkinson Pressure Bar (SHPB) tests. Out of the four groups, it was concluded that oil & MoS2 and glass fiber solid lubricant were more capable of maintaining dynamic modulus. In contrast, PA6 without any inclusions experienced a rapid decrease in dynamic modulus with increasing strain rate. Microscopic imagery is taken to evaluate crack formation in samples and sample deformation. Multiple side and edge cracks were developed from the specimens starting from a strain rate of 1900s−1; however, shattering of specimens was not experienced until above 2300s−1 strain rates were achieved. It is concluded that tested specimens experienced hardening trends at higher testing pressures and strain rates. A computational analysis is underway to establish the effect of heat stabilization and lubricant inclusions in PA6 strain rate-dependent mechanical response.
Infrared Radiometry Based Steady-State Method for Thermal Conductivity Measurement
Authors: Wang Dihui , Ban Heng
Published: January 2022

This study develops an infrared radiometry-based steady-state technique (SSIR) that combines the benefits of transient pump technique, steady-state method, and infrared radiometry. The method uses a continuous wave (CW) laser as the pump source and a high-speed infrared camera system to capture temperature-time maps as the probe system. Instead of the thermoreflectance measurement, the advanced infrared camera system eases the theoretical model and experiment. The infrared camera system enables straightforward temperature versus time reading with a good spatial resolution. For demonstration, material with thermal conductivity over two orders of magnitude (1∼150Wm−1K−1) are measured. This technique enables measuring thermal conductivity independently from volumetric heat capacity, and by using reference sample, the sensitivity to most input parameters is effectively reduced. Therefore, SSIR shows lower uncertainty to standard FDTR and TDTR.
Experimental Investigation of Nanosecond Laser Ablation of Carbon Nanotubes
Authors: Pachon Oscar , Ma J. , Schaper Nicholas , Jahan M. P. , Lei Shuting , Kuljanishvili Irma
Published: January 2022

Carbon nanotubes (CNTs) have been a subject of development and investigation in the last two decades due to their superior physical and chemical properties, such as high electrical conductivity, high thermal conductivity, high mechanical and elastic properties, and relative inexpensiveness. This paper aims to grow CNTs in the lab and then investigate its manufacturability and relevant properties changes using the laser ablation process. The CNTs were grown using Chemical Vapor Deposition (CVD) process. The catalyst used for the growth was Iron on a Silicon substrate. The average size of the substrate samples is 5 mm by 5 mm. Continuum Surelite Class III laser with 1064 nm wavelength of single pulse mode is used to ablate the CNTs to assess property changes in CNTs resulting from laser-matter interaction. The laser beam energy and beam diameter are varied to investigate their influences on properties changes in CNTs. The laser beam energy ranges from 0.063 J to 0.35 J and the beam diameter is adjusted using an optical lens, for which the focal length is 150 mm. Twelve samples have been tested and Scanning Electron Microscopy (SEM) and Raman Spectroscopy have been used to characterize the samples before and after laser ablation. A Raman spectrum was taken 4 to 6 times for each of the samples before the ablation. The density of the population for both SWCNTs and MWCNTs is demonstrated on the spectrum. It is found that when 0.153 J is used with the distance between sample and lens being equal to the focal length of the lens, SEM imaging and Raman Spectrum show a bright burned circumference caused by the laser beam. The CNTs at a distance of 200 micrometers around are found to be broken down as well due to the heat propagation from the laser beam. The application of laser can be used to reduce the electrical conductivity from a CNT network without damaging silicon substrate, which could expand the application of CNTs in the Electronics industry.
Enhanced Crystallinity Development of Poly-Lactic Acid by Dynamic Melt Manipulation
Authors: Gao Peng , Kundu Animesh , Alqosaibi Khalid , Coulter John
Published: January 2022

The primary objective of this research was to gain fundamental insight on the effect of imposed shear rates by dynamic melt modulation during injection molding on the crystallinity development of PLA. The dynamic melt modulation was achieved by a Dynamic & Intelligent Shear-Controlled Injection Molding (DISC-IM) instrument that utilized an in-house developed control system capable of oscillating the injection screw. The melt modulation process proved to be an efficient processing technique for enhanced properties in a particular commercial grade of PLA that contained various additives. The cycle time was reduced by 40% and total crystallinity was increased by ∼50% during DISC-IM as compared to the conventional injection molding under similar conditions. The oscillatory movements also promoted the formation of a phase crystalline structures on the surface layer of the samples. The crystallization behavior of neat PLA was dramatically enhanced by 1wt.% of orotic acid. Introduction of DISC-IM enhanced the crystallinity of PLA-OA blends from 25% to 56% at a mold temperature of 70°C. Although, the overall crystallinity was relatively similar for different DISC-IM conditions, the crystalline phases that were formed was different. DISC-IM process promoted the formation of á phases for PLA-OA blends.
Laser Microgrooving and Nanofiber Membrane Application for Total Knee Replacement Implants Using a Caprine Model
Authors: Khandaker Morshed , Nikfarjam Sadegh , Kari Karim , Kalay Onur Can , Karpat Fatih , Progri Helga , Bhuiyan Ariful , Clary Erik , Haleem Amgad
Published: January 2022

Aseptic loosening is a well-recognized phenomenon in cementless total knee replacement (TKR) and often carries severe consequences for the patient. We recently developed and tested in vitro a novel strategy for enhancing osseointegration and acute mechanical stability of orthopedic implants that employ laser-induced microgroove (LIM) and nanofiber membrane (NFM) applications at the bone-implant interface. We report herein investigation of the approach with results from a pilot study employing three skeletally mature female Spanish cross goats (∼4y, 35–45kg) receiving cementless TKR with a commercially available implant system (Biomedrix® Canine Total Knee). Pre-operative radiographs were taken to ensure limb normality and to select the appropriately sized implants for each goat. With the animal under general anesthesia and the limb properly prepped for aseptic surgery, the stifle was approached, and osteotomies of the proximal tibia and distal femur performed in preparation for implantation of the tibial (TT) and femoral (FT) trays. For one goat, the arthroplasty implant surfaces were unaltered from the manufacturer’s mirror-polished (MP) condition. For the other two goats, the TT bone-contact surface was laser-micro grooved (150 μm depth, 200 μm width, 200 μm spacing) prior to sterilization and then implanted with (LIM/NFM) or without (LIM) an intermediate (surface-applied) polycaprolactone (PCL) nanofiber mesh (50 × 50mm, electrospun, aligned, unidirectional, 10 μm thickness). Following surgery, animals received appropriate analgesic therapy and rehabilitative care to maximize animal comfort, function, and quality of life while limiting the risk of major complications. Post-operative monitoring included assessment of mentation, vital signs, pain level, digestive function (weight, appetite, rumen contractions, feed intake, fecal output), and limb status (usage, range of motion, muscular volume). By the study’s end (12 wks), all animals had recovered a pre-surgery range of motion in the operated knee and exhibited typical bony changes on radiographic follow-up. At necropsy following humane euthanasia, no gross instability of TKR components was observed. Histomorphometric analysis of explanted bone-TT constructs showed the increased new bone surface area in the LIM-NFM sample (0.49 mm2) compared with the MP sample (0.03 mm2), suggesting that microgrooves and/or PCL nanofiber coating may improve the clinical performance of the implant. A finite element analysis (FEA) model was developed to explore the impact of surface micro grooving to the mechanical stimuli at the bone-implant interface to supplement the in vivo studies. The three-dimensional geometry of the tibia was scanned using computed tomography and imported into a proprietary (MIMICS®) software to construct the solid models for finite element micro-strain analyses.
Effect of LiNbO3 Coating on Capacity and Cycling of Nickel-Rich NMC Cathode Active Material
Authors: Frisone Dominic , Amiriyan Mahdi , Hassan Eman , Dunham Joshua , Farahati Rashid , Farhad Siamak
Published: January 2022

Among many types of all-solid-state lithium batteries (ASSLBs), the one based on argyrodite crystalline electrolyte is considered as one of the most promising batteries because of their safety and high energy density. Significant efforts have been devoted toward developing argyrodite-type ASSLBs, but the commercialization of these batteries still needs to resolve some scientific and technical problems. Two problems that need to be addressed are reducing the interfacial resistance between the electrolyte and electrode active materials and minimizing the reaction between the electrolyte and electrode active materials. One method to solve these two problems is to coat the electrode active material with a material which is compatible with argyrodite electrolyte. The aims of this paper are (1) to compare two methods of synthesizing and coating of cathode active material and (2) to evaluate the capacity and cycling performance of the coated active material. In this study the emphasis is on lithium niobate (LiNbO3) as the coating material and LiNi0.85Mn0.1Co0.05O2 (NMC) as the nickel-rich cathode active material.