bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation and Accuracy Guarantee Technology of Fuselage Component Trial Assembly Based on Dynamic Process Model
Authors: Kang Yonggang , Chen Mingyuan , Chen Xiduo , Chen Zhihao , Xiao Huan 
Published: January 2022

Abstract
Modern aircraft fuselage size is large, structural rigidity is weak, the docking process is complex, accuracy guarantee is difficult and assembly efficiency is low. Especially in the plug-in butt joint assembly process of large fuselage parts, there is the inherent problem of invisible and unmeasurable docking end surfaces. It is more likely to lead to interference or uneven gaps in the docking process, and eventually lead to repeated trial assembly and decline in the consistency of the connection quality. That will affect the assembly efficiency and fatigue characteristics of the local structure. Aiming at the plug-in butt joint assembly of large fuselage parts, this paper integrates digital measurement technology, numerical control positioning technology and virtual simulation technology, through measurement modeling and trial assembly simulation to guide the digital positioning and docking process. It makes the invisible and unmeasurable process of insertion digitally visible. Through the integration of point cloud data acquisition and pre-processing, digital twin modeling and assembly simulation, a dynamic process model for trial assembly simulation is constructed. A complete test environment for the joint assembly of the fuselage barrel parts was built. Research was conducted on the reduced test pieces of MA700 front fuselage and middle fuselage. We developed a large space measurement module, a spatial attitude solution module, an integrated control module and a virtual simulation module. The effectiveness of the fuselage component trial assembly simulation based on dynamic process model and accuracy assurance technology was verified.
Mechanical Properties of Snap-Fits Fabricated by Selective Laser Sintering From Polyamide
Authors: Detzel Samuel , Sigling Annette C. , Lueth Tim C. 
Published: January 2022

Abstract
Snap-fits provide a quick, simple and reversible way to join larger additively manufactured parts. They take up little space and are flexible in their placement. The mechanical properties of snap-fits fabricated by selective laser sintering are not well explored. While the mechanical properties of the bulk material are available, these do not sufficiently describe the behavior of thin and flexible structures. The purpose of this research is the investigation of the mechanical properties of SLS-fabricated snap-fits. We explored the influence of geometric parameters, orientation during the manufacturing process and post-processing by chemical vapor smoothing as well as stress cycling. In a series of experiments, we measured the retaining force applied along the axis of the joint as well as the force necessary to open the snap-fit by pressing sideways. Based on literature, we formulated the relationship between geometry and mechanical properties. The resulting formulas were tested experimentally and corrected if necessary. The results show that the effective flexural modulus is 45% lower in cantilever snap-fits with width and thickness of less than 3 mm compared to bulk material. Smoothing reduced the flexural modulus as well as the friction even further.
Effect of Thermal Expansion Coefficient, Viscosity and Melting Range in Simulation of PCM Embedded Heat Exchangers With and Without Fins
Authors: Alam Tanjebul , Bacellar Daniel , Ling Jiazhen , Aute Vikrant 
Published: January 2022

Abstract
Phase change material heat exchangers (PCMHX) have animportant role in integrating renewable energy systems. PCMHX can offer high storage density at various temperatures of interest and can be used for grid load shifting purposes. Numerical models enable engineers to estimate PCMHX performance for different design parameters and operating conditions. Modeling phase change phenomena is challenging due to the complex time-dependent nature of the process. The accuracy of models is highly sensitive to PCM thermo-physical properties. Thermal expansion coefficient (β), viscosity (μ) and melting temperature range (MR) of a PCM are important properties, especially when natural convection is not negligible. In PCMHX modeling, using less than accurate values for these properties can have significant impact on the simulation outcomes. These propertiesand discussions thereof are not readily available in the literature. This paper presents a brief review of the literature and a numerical study investigating the model sensitivity to the above-mentioned properties for PCMHX with and without fins. CFD is used to evaluate the charging (melting) phenomena. The study quantifies the impact of uncertainty in these properties on the melting rate and temperature profile. Constant wall temperature was consideredas heat source with no heat loss to ambient. The results show that β and μ has significant effect on the melting rate andevolution of the melting front. For a non-finned domain when comparing results for different published values of β and μ, the deviation in melting time can be up to 12.9% and 57.6% respectively. For high wall temperatures, change in melting range did not impact melting time. But when the wall temperature is reduced, up to 9.8% deviation in melting time is observed.
Computational Model for an Electrochemical Hydrogen Compressor
Authors: Aziz Majid , Aryal Utsav Raj , Prasad Ajay K. 
Published: January 2022

Abstract
One of the main challenges in developing the hydrogen infrastructure is the distribution and storage of hydrogen. A common method to store hydrogen is as a compressed gas. Electrochemical compression (ECC) is a promising technology that can sidestep some of the disadvantages present in conventional mechanical compressors. ECC is an externally powered device that employs an electrochemical cell containing a polymer electrolyte membrane (PEM) to compress the gas. This work presents a detailed 2D ECC model developed using COMSOL Multiphysics 5.6, that considers the important phenomenon of back diffusion resulting from the high pressure differential between cathode and anode during compression. Results from the current simulations are validated against experimental results obtained previously in our lab. Simulations were first conducted for the unpressurized cathode and the performance was analyzed in terms of the polarization curve. Next, simulations were conducted for the pressurized cathode, with and without considering back diffusion. In the absence of back diffusion, the pressure ratio reaches the value predicted by the Nernst equation. However, the presence of back diffusion greatly reduces the pressure ratio similar to experimental observations.
Experimental and Computational Study of Direct Contact Membrane Distillation
Authors: Kim Deliya , Caspar Justin , Romero Carlos , Neti Sudhakar , Oztekin Alparslan 
Published: January 2022

Abstract
Experimental and computational studies of direct contact membrane distillation (DCMD) are conducted. The permeate flux is measured in a module containing a flat sheet membrane. Polytetrafluoroethylene (PTFE) hydrophobic membrane (Membrane Solutions, FPB045A16) with a nominal pore size of 0.45 μm, the thickness of 179∼239 μm, the porosity of 80% is used in the experiments. The feed solution is a binary mixture of water and NaCl. The inlet feed temperature is fixed at 70°C, and the feed Reynolds number is varied between 500 and 2000. Two inlet feed concentrations, 0 and 35g/L, are considered. The permeate flow rate was kept constant at Re of 1300 and temperature of 20°C. Three-dimensional steady-state computational fluid dynamics (CFD) simulations are performed using the laminar model. The Navier’s Stokes, energy, and mass transport equations in each channel coupled with flux boundary conditions imposed at the membrane surface are solved. The predicted module-averaged flux is compared to measured data for all operating conditions. Measured and predicted flux agrees well; validating both experiments and model, Temperature polarization in the feed and permeate channel and concentration polarization in the feed channel are characterized by validated CFD simulations.
Wind Tunnel Data Acquisition System
Authors: Bishop Riley , Fisher Wesley , Doom Alex , Hollingsworth Elena , Mazzoni Brian , Chidurala Manohar 
Published: January 2022

Abstract
A team of mechanical engineering students at Western Kentucky University designed a subsonic wind tunnel data acquisition system through LabVIEW to analyze the forces acting on an object in external air flow. The experimental setup provides future fluid mechanics laboratory students a hands-on procedure to study aerodynamic forces such as lift and drag. The physical models tested include two 3D-printed cylinders and a NACA 0012 airfoil placed in the wind tunnel test section. The cylinder shape was chosen, because it provides a simple flow field that can easily be used to verify the accuracy of the system, and the NACA 0012 was selected for the simplicity of symmetric airfoil theory calculations. Pressure transducers were used to measure pitot tube velocity readings as well as the pressure at 16 points around the upper 180 degrees of the objects. The resulting pressure distribution on the surface of the bodies was then applied to calculate lift and drag forces acting on the objects. A force balance was also designed to securely mount objects in the wind tunnel while directly measuring the total lift and drag forces, calculating the moment about the leading edge, and monitoring the angle of attack. The force balance results can be used to verify the experimental results from the pressure distribution data. A LabVIEW program was written to communicate directly with data acquisition hardware (NI CompactDAQ), set experimental parameters such as air flow speed and sample rate, record data, and interpret the results through a single user interface. Inviscid theory was used to theoretically predict the ideal drag acting on the cylinder, and symmetric thin airfoil theory was used to predict the ideal lift acting on the airfoil. Along with theoretical models, CFD analysis was performed to simulate a controlled experiment and validate the experimental results. Though experimental data has not yet been collected, the LabVIEW code has been tested using simulated data, and the accuracy of the pressure transducers has been confirmed by comparing pressure readings to controlled manometer readings. The system is expected to provide accurate data limited to the maximum speed of the subsonic wind tunnel currently owned by the Thermofluids Laboratory at Western Kentucky University. Future improvements of this project could include purchasing a more capable wind tunnel to run experiments in the turbulent flow regime, as well as a larger test section to avoid error from wall effects. This experimental set up has laid the groundwork for a multitude of future studies. It can be used to observe aerodynamic forces acting on more complex NACA airfoil shapes, rotating plates, cylinders and spheres, wind turbine blades, ground vehicles, airplanes and more.
Deformation Manifold Learning Model for Deformation of Multi-Walled Carbon Nano-Tubes: Exploring the Latent Space
Authors: Yadav Upendra , Pathrudkar Shashank , Ghosh Susanta 
Published: January 2022

Abstract
A novel machine learning model is presented in this work to obtain the complex high-dimensional deformation of Multi-Walled Carbon Nanotubes (MWCNTs) containing millions of atoms. To obtain the deformation of these high dimensional systems, existing models like Atomistic, Continuum or Atomistic-Continuum models are very accurate and reliable but are computationally prohibitive for these large systems. This high computational requirement slows down the exploration of physics of these materials. To alleviate this problem, we developed a machine learning model that contains a) a novel dimensionality reduction technique which is combined with b) deep neural network based learning in the reduced dimension. The proposed non-linear dimensionality reduction technique serves as an extension of functional principal component analysis. This extension ensures that the geometric constraints of deformation are satisfied exactly and hence we termed this extension as constrained functional principal component analysis. The novelty of this technique is its ability to design a function space where all the functions satisfy the constraints exactly, not approximately. The efficient dimensionality reduction along with the exact satisfaction of the constraint bolster the deep neural network to achieve remarkable accuracy. The proposed model predicts the deformation of MWCNTs very accurately when compared with the deformation obtained through atomistic-physics-based model. To simulate the complex high-dimensional deformation the atomistic-physics-based models takes weeks high performance computing facility, whereas the proposed machine learning model can predict the deformation in seconds. This technique also extracts the universally dominant pattern of deformation in an unsupervised manner. These patterns are comprehensible to us and provides us a better explanation on the working of the model. The comprehensibility of the dominant modes of deformation yields the interpretability of the model.
Tritium Absorption on Carbon Nanostructures
Authors: Atchley Bryce , Wu Erica , Park Jungkyu , Farfan Eduardo 
Published: January 2022

Abstract
In the present research study, we utilize a molecular dynamics simulation to investigate the possibility of using multiple graphene sheets for tritium control. The graphene sheets are equilibrated to temperatures of 10k, 100k, 300k, 600k, 900k, or 1200k in a simulation. After equilibration, the tritium atoms are made to travel toward the graphene sheet with uniform velocity. The velocities of tritium atoms are selected so that incident energies may be 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, or 500 eV. Reflection is shown to be the dominant interaction at low tritium incident energy, with a sharp decline in reflection rates as energy increases. For the case of a single layer of graphene, reflection rates reach a minimum around 5eV and steadily climbs as energy is increased to 10eV. Absorption rates are shown to increase with increasing tritium energy until energies are very high, around 5 eV. After 5 eV, absorption rates decrease as incident energy increases. Penetration rates of incident tritium atoms remain low until 5 eV, after which the rates increase steadily. Higher graphene equilibration temperatures yield higher absorption rates at low incident energies but lead to lower absorption rates at high incident energies. At low incident energies, reflection is favored more at lower temperatures, while graphene temperatures do not seem to affect reflection rates much at high incident energies. Lastly, penetration rates are consistently higher at higher graphene temperatures. The larger amount of energy present in the structure at higher temperatures allows for the C-C bonds in graphene to be more readily broken. The results obtained in this research study will be used to develop novel nanomaterials that can be employed for tritium control.
Aeromedical Evacuation Skeletal Traction
Authors: Rabb Ethan , Zifchock Rebecca , Nowicki Margaret , Paquin Jeremy , Posner Matthew 
Published: January 2022

Abstract
The purpose of this project is to design a device that provides skeletal traction to a patient with a fractured femur in an aeromedical evacuation environment. Skeletal traction is typically provided by using weights and cable to provide tension onto a fractured limb. However, in an aeromedical evacuation environment, the forces vary and the environment is not stable, so the traditional method to provide skeletal traction is not suitable. Therefore, we designed and tested a device that could provide skeletal traction to a femoral fracture in an aeromedical evacuation environment.
Targeted CAD/CAM Workshops for Freshmen to Improve Overall Performance
Authors: Kocharian Tikran , Manoharan Sanjivan 
Published: January 2022

Abstract
Introduction to Computer Aided Design (CAD)/Computer Aided Manufacturing (CAM) is typically covered at the freshman level. This course is especially crucial for institutes where students engage in cooperative education with employers in the manufacturing industry. In addition, given the demanding nature of the course, retention at the freshman level has been a persisting issue. The culminating experience for this particular course requires all students to take the Certified SolidWorks Associate (CSWA) exam. Unfortunately, 54.7% of the students failed the CSWA exam in the previous offering. A major issue has been the insufficient course contact hours for this content-heavy course. In addition to CAD/CAM introduction, there are several other courses in the freshman sequence resulting in a total class time of only 50 minutes per week. Taking this into consideration, targeted practical workshops were held every three weeks in the latter half of the semester to better prepare the students. The workshops were carefully designed to effectively cover the following areas: fluency in SolidWorks, critical thinking and decision making, design intent, CAD management, and software customization. A total of three workshops were held remotely for the students enrolled in a section taught by the primary author. The control group comprised of the remaining students enrolled in other sections. The student response for the workshops was overwhelmingly positive, and there was an evident improvement in the performance on the CSWA exam. All students who attended the workshop passed the certification exam thus improving the overall course failure rate by over 10%.
A Comparative Study on Feature Descriptors for Relative Pose Estimation in Connected Vehicles
Authors: Nayak Anshul , Eskandarian Azim , Ghorai Prasenjit , Doerzaph Zachary 
Published: January 2022

Abstract
In cooperative perception, reliable detection and localization of surrounding objects and communicating the information between vehicles is necessary for safety. However, V2V transmission of huge datasets or images can be computationally expensive and pose bandwidth issue often making real-time implementation non-feasible. An efficient and robust approach for ensuring such cooperation can be achieved by relative pose estimation between two vehicles sharing a common field of view. Especially when an object is not in the field of view of an ego vehicle, dynamically detecting the object and transferring its location in real-time to the ego vehicle is necessary. In such scenarios, reliable and robust pose recovery at each instant ensures accurate trajectory estimation by the ego vehicle. In our current study, pose recovery is achieved through common visual features present in a pair of images. Traditionally, algorithms like SIFT and KAZE have been used to detect and match features between an image pair from sensors looking from a different perspective. However, recently with the advent of binary detection and description algorithms like ORB and AKAZE, we have decided to analyze and show a comparative study on the efficacy and robustness of such methods for feature matching. The performance metrics for each method are decided based on total detected features, the number of good matches, and the computation time. The current study also tests the performance of each method under varying degrees of angular orientation and camera exposure setting, which can be helpful for motion estimation under dim light. Overall, AKAZE was computationally faster among all, while ORB and SIFT fared equally on other parameters. The corresponding research can be a precursor to future trajectory prediction of dynamic objects by the ego vehicle when there is a sudden loss of communication with the lead vehicle after the initial data transfer.
Peculiar Transmission Manipulation of Antisymmetric Lamb Waves via a Surface-Bonded Single-Layer Elastic Meta-Structure
Authors: Tian Yiran , Shen Yanfeng 
Published: January 2022

Abstract
Metasurfaces, treated as equivalent two-dimensional (2D) metamaterials, have the advantages of compactness and simplicity. In spite of the recent related booming researches, the non-perforated or surface-bonded ultrathin elastic metasurfaces have seldom been reported, since there exists a big challenge in designing such a single unit to satisfy the requirements of 2π phase span and simultaneous high transmission. In this paper, an elastic meta-structural functional unit is carefully designed, enabling an effective wave manipulation application for Structural Health Monitoring (SHM) and Non-destructive Evaluation (NDE) communities. Through conducting a series of parametric studies, the full 2π phase span and high transmittance can be achieved by a singl-elayer meta-structural unit. When proceeding to calculate the phase profile for realizing the full 2π phase span, the height of the unit cell stub is tuned by exploring a finite element model (FEM) using harmonic analysis. The nephograms of the phase shift varying with the stub height and excitation frequency exhibit the successful achievement of a full 2π span covering a wide frequency range. Further, to enable a high transmittance at the same time, two sets of parametric studies are complementally carried out through adjusting two additional structural parameters. Subsequently, various single-layer elastic meta-structures are designed with the proposed unit cell for the peculiar transmission manipulation of antisymmetric Lamb waves demonstrated by numerical simulations. The paper finishes with summary, concluding remarks, and suggestions for future work.
Numerical Study of the Effect of Burner Position and Reformer Tubes on the Design of an Annular Steam Methane-Reforming Reactor for Hydrogen Production
Authors: Rohini Ajith Krishnan , Lee Hee Joon 
Published: January 2022

Abstract
This work presents a computational fluid dynamic-based numerical study of the effect of burner position and number of reformer tubes on an annular steam methane-reforming (SMR) reactor for hydrogen (H2) production. Three different burner configurations such as single co-axial inside burner (SCIB), single top burner (STB), and multiple top burner (MTB) arrangements were considered. The number of reformer tubes inside the reactor was varied to four-, six-, and eight-tube arrangements. This study revealed that the STB configuration was preferable to the SCIB and MTB configurations owing to the effective utilization of heat from the combustion gas and uniform temperature distribution. The flue-gas inlet temperature, reformer inlet velocity, and number of reformer tubes were found to exert a significant effect on the SMR reactor. Additionally, the SMR design was modified by installing a sleeve around the outer reformer with a sleeve spacing of 15 mm and a burner at the bottom. The effect of the sleeve design on the H2 yield, temperature distribution, and wall heat-transfer coefficient was also presented.