bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Wave Energy on the Willamette River
Authors: Poor C. J. , Anderson Rachel , Dillon H. E. 
Published: January 2022

Abstract
The trend of using larger boats for wake surfing in river systems has caused concern for dock stability, bank erosion, safety of other boaters, and natural resource conservation. This study evaluates the wave energy due to boat traffic in the Newberg Pool of the Willamette River using budget conscious equipment and involving community stakeholders. Low-cost motion activated game cameras were used to record videos of waves when boats passed.
The video processing was completed using image analysis in the computational tool Matlab. For each image a high-contrast point of reference was used for the tracking, often tape on a dock piling. As the wave or dock moved, the reference point in the image was tracked in Matlab using the maximum or minimum grayscale pixel in a specific part of the image. This calculation allowed the research team to approximate the change in vertical direction in pixels.
A computational analysis tool was used at 4 sites, 2 in wake surfing zones, 1 in a wake zone, and 1 in a no wake zone, to quantify wave height and period. A total of 8567 videos were collected from the four sites, and 1227 were analyzed. For the wake surfing zone, the average and maximum wave heights were 0.026 m and 0.149 m, respectively, and average and maximum wave energies were 0.905 W/m and 19.2 W/m, respectively. In the wake zone, the average and maximum wave heights were 0.031 m and 0.137 m, respectively, and average and maximum wave energies were 1.405 W/m and 5.74 W/m, respectively. The average wave energy was higher in the wake zone, however, the maximum wave height and the number of boat-caused waves recorded were higher (2984 in the wake surfing zone compared to 1117 in the wake zone) in the wake surfing zone. Cameras were attached to dock pilings which may have resulted in lower values due to the dampening of the dock. Wake surfing was also observed in wake zones, where it is not allowed. This study indicates that the large boats used for wake surfing create larger waves that can potentially cause damage to property along the river and natural resources.
The processes and procedures used within this research would not have been possible without citizen involvement. The citizens partaking in the research allowed for their property to be used as a heavily monitored site or a self-monitored site. The self-monitored sites were a useful tool in collecting more data.
Numerical Study of the Percussive Riveting Process: Analysis Validation
Authors: Krovvidi Sai C. , Ramulu M. , Reinhall Per G. 
Published: January 2022

Abstract
This effort represents the continuation of percussive riveting work that has been performed by this University of Washington research group and presented at this event in the past. Percussive riveting is an assembly method that is used ubiquitously in the aerospace industry, especially in the fuselage final assembly phase. It is a dynamic assembly process that requires two entities operating simultaneously in order to form a rivet. One entity operates with a riveting gun on the exterior of the fuselage. The rivet gun provides the energy input to carry out the assembly process. The other entity operates with a bucking bar on the interior of the fuselage. This entity is responsible for forming the rivet from the shank end. In previous work undertaken by this research group, an axisymmetric thermomechanical finite element model (FEM) framework implementing actual boundary conditions was developed to understand the effect of geometric factors on the residual stress and strain distributions within the riveting stackup. A countersunk rivet and two skins are part of the riveting stackup. The countersunk rivet is widely used in the aerospace industry because of flushness requirements. Because no further joint finishing processes are required after the countersunk rivet has been formed, it is an economically viable final assembly method. Residual stress and strain distributions within the rivet stackup affect the fatigue performance of the assembled joint. The percussive riveting process is different from the conventional squeeze riveting process because of the dynamic and adiabatic nature of the percussive riveting process. Strain rate effects and thermal effects are negligible in the squeeze riveting process because of the low velocities and strain rates involved. But these two effects along with large strain magnitude play an influential role in the percussive riveting process. Because of the dynamic nature of the percussive assembly process, framework validation is important. A three-dimensional FEM (3DFEM) was constructed with asymmetric motion of the bucking bar, also known as the forming tool. The results of the 3DFEM simulation are compared with previously presented axisymmetric FEM and are presented in this study. Analysis validation of the axisymmetric FEM was performed and analysis results were compared with FEM results.
Applications of High-Dimensional Data Analytics in Structural Health Monitoring and Non-Destructive Evaluation: Thermal Videos Processing Using Tensor-Based Analysis
Authors: Momeni Hamed , Ebrahimkhanlou Arvin 
Published: January 2022

Abstract
This study reviews existing and potential applications of high-dimensional data analytics in the fields of structural health monitoring and non-destructive evaluation. Contrary to the high potential of these methods, the implemented applications in structural health monitoring and non-destructive evaluation topics are limited. In addition, with the ever-increasing development of measurement equipment, the necessity of using these methods is enhancing. In this paper, videos captured by different non-destructive evaluation techniques are studied as an example of high-dimensional data. Thermal videos are used for automatic damage detection and localization. Particularly, thermal cameras are employed to find delamination zones in composite plates, commonly used in aircraft wings. Due to the high-dimensional intrinsic of videos, using conventional statistical methods raise theoretical and practical challenges. One of the solutions to overcome these challenges is implementing tensor-based data analysis to analyze videos. Two tensor factorization methods are presented and employed to localize the damage automatically. The results show that the recorded video can be represented by a few vectors, which easily extract the time variation and extent of the damage.
On the Dynamic and Control for a Three Degree-of-Freedom Robotic Arm Used for Rehabilitation Purposes in Medicine
Authors: Grandas Franco Jean Carlo , Borrás Pinilla Carlos 
Published: January 2022

Abstract
The usage of “robotic arms” for passive rehabilitation of post-stroke patients has been gaining relevance, considering how it can assist medical personal to carry out their tasks properly. However, when it comes to controlling these kinds of devices, it normally must deal with non-linearities issues resulting from the mathematical model of robotic arms, which is the case for three degrees of freedom (3DoF) articulated arm. Besides, uncertainties and constraints must be considered, as well as proper reduction of error signals, to assist real patients.
For the given case of study, two control strategies were developed and implemented: PID and Sliding Mode Control with LQG. For both cases, the nonlinear mathematical model was developed and implemented as the system to be controlled. The PID controller was developed as a performance reference and comparison, and the Sliding Mode Controller with Extended Kalman Filter (LQG) design was proposed to increase robustness and stability on tracking trajectories to the rehabilitation of patients.
The mathematical model of the 3DOF robotic arm was derived from the Euler-Lagrange formulation which is based on energy equations. For both control strategies, the system was implemented in Matlab© and Simulink© environments. While both show good performance in terms of settling time, SMC delivers the best results in terms of energy costs, noise rejection, and uncertainties, which can be easily set up with a combination of LQG control strategies. Since weight compensation was considered for the plant “robotic arm” design, the control could be applied for a real robot prototype, and it is scalable in terms of physical parameters and the required compensation forces.
Holmquist-Johnson-Cook Constitutive Model Validation and Experimental Study on the Impact Response of Cellular Concrete
Authors: Collard Jack , Lanham Jake , Davis Brad G. 
Published: January 2022

Abstract
In a previous study by Davis and Dequenne, a Holmquist-Johnson-Cook (HJC) constitutive model for a cellular concrete with a nominal density of 1442 kg/m3 was developed from existing direct tension, uniaxial strain, and triaxial shear testing conducted at the United States Army Corps of Engineers Engineer Research and Development Center (ERDC) and Sandia National Laboratory (SNL). The resulting constitutive model was compared to depth of penetration results from testing conducted by Goodman at the Aberdeen Test Center with promising results. This study seeks to build on this previous work by producing depth of penetration and perforation experiments using non-deforming projectiles into a similar cellular concrete for validation of the fit HJC model. Depth of penetration experiments were conducted by firing into a 305 mm thick panel over a velocity range of 200–800 m/s with the strike velocity and depth of penetration recorded for each experiment. Perforation experiments were conducted over a range of 200–800 m/s against panels with thicknesses of 38 mm, 76 mm, and 114 mm with the strike velocity, residual velocity, and crater characteristics recorded for each experiment. 2D numerical simulations were conducted for each experiment and the results were compared for initial model validation, but additional experimental testing and simulation is required. There is error between the experimental and numerical results and a sensitivity analysis should be conducted to determine where additional testing is appropriate to improve the model’s correlation with experimental results.
Implementing a Discrete Element Method for Fused Deposition Modeling Additive Manufacturing Thermal Modeling
Authors: Menezes Chelsea , Turner Cameron J. 
Published: January 2022

Abstract
One of the challenges of additively manufactured parts is that additive manufacturing processes can lead to anisotropic material properties. For this research, we focus on fused deposition modeling (FDM) which is a common consumer grade process that also is often used for early prototyping due to its low investment and processing cost. In FDM, a semimolten filament is extruded. Within the filament (the intrafilament bonds), the material properties are essentially that of a bulk material that has been injection molded. However, because of the differences in temperature when adjacent filaments are deposited, the material properties between filaments within a layer (the intralayer bonds) are generally less than that of the intrafilament bonds leading to an anisotropic behavior within a layer. Similarly, the temperature difference between layers leads to yet another different material bonding strength (interlayer) that is also less than that of the intralayer or intrafilament bonds.
Our hypothesis is that these anisotropic property differences can be predicted using Discrete Element Models (DEM) to model the process of printing the part filament by filament and layer by layer and the subsequent cooling process. A DEM approach discretizes the filament into discrete elements that are treated as a lumped parameter elements connected to adjacent elements through a set of heat transfer boundary conditions. Elements with external part surfaces are therefore connected to the external environment, or in the case of elements in the base layer of the part, are connected to the print bed which is often heated to encourage bonding between filaments.
The DEM model is validated by comparing the predictions of the model against observed behaviors in FDM printing. For instance, the exposed surfaces of an FDM print will cool faster than elements in the core of the print, or elements that are in contact with the heated printing bed.
This paper describes the process of developing a thermal DEM model in MatLAB, including the assumptions underlying the element level heat transfer model. In addition, discussion of the model results is included to demonstrate the validity of the model as well as the comparisons made to available simulation and experimental data which allows us to validate the underlying behavior of the model. As a result of this research, there are several avenues available for future work including the estimation of bond strength between fibers and layers, the incorporation of viscosity effects, mechanical loading, and the possibilities for process optimization based on intelligent filament path planning, reheating technologies and adaptively controlling the build plate and environmental temperatures.
Utilizing the NASA Human Exploration Rover Challenge Project at the University of the District of Columbia (UDC) to Enhance the Engineering Experience for the Diverse Population of Underrepresented Students
Authors: Harrigan Voss , Xu Jiajun , Haghani Sasan 
Published: January 2022

Abstract
For several years, the University of the District of Columbia (UDC), the only public university in the nation’s capital and a land-grant university, has participated in the NASA Human Exploration Rover Challenge. The Rover Challenge participants are tasked with designing and fabricating a two-person human-powered rover capable of traversing a course designed by NASA to simulate various terrain. Based on the success over the years, a team was once again formed in 2020 to improve the previous design and develop students’ areas of proficiency in additive manufacturing and sensor integration. This was done by leveraging UDC’s new NASA-funded Center for Advanced Manufacturing in Space Technology & Applied Research (CAM-STAR) and its additive manufacturing facilities. In this paper, the authors will introduce the rover competition for 2020, new changes for the competition, and UDC team’s news design, AM produced parts for the rover, and lesson learned and plan forward. This paper will also discuss how a diverse population of students were engaged and their feedback on this experiential learning experience. Lastly, this paper will also discuss the impact of infusing cutting-edge technology (i.e., Additive Manufacturing) in STEM project and how it has helped attract students and increase their career readiness.
Dynamics of Droplets in Core Gas Flow Superimposed With Acoustic Pressure Waves
Authors: Mortazavi Mehdi , Pedley Taylor 
Published: January 2022

Abstract
During the operation of a proton exchange membrane fuel cell, water is produced in the cathode electrode. Accumulation of produced water in the flow channel can block the transport of reactants, which ultimately lowers the performance of the cell. The water content in the flow channel can be efficiently removed from the channel with an external excitation. Previously, the author reported utilization of acoustic pressure waves in order to remove the water content from the flow channel [1]. However, the dynamics of liquid water droplets during this removal process were not investigated. The current study investigates dynamics of water droplets on the surface of the gas diffusion layer (GDL) when acoustic pressure waves are superimposed on the core gas flow. Two different modes of superimposition were implemented; (i) continuous, and (ii) on demand. Study of droplet dynamics was achieved by visualizing the droplet from the side-view with a high-speed camera. When the superimposition was done in the continuous mode at 20 Hz, the droplet went through the rocking motion on the surface of the GDL. For 60 and 80 Hz of superimposition, in addition to the rocking motion, droplets underwent the prolate mode of oscillation, which was characterized by vertical oscillations. For higher frequencies of acoustic pressure waves, in addition to rocking and prolate modes of oscillation, droplets underwent the oblate mode of oscillation, which featured horizontal oscillations. The on on demand experiments demonstrated that the liquid water droplet detached from the surface of the GDL only when the droplet size was large enough.
On Structural Damping Characteristics in the Electro-Mechanical Impedance Method
Authors: Misla Aaron , Zagrai Andrei 
Published: January 2022

Abstract
The electro-mechanical impedance method is a useful tool for structural health assessment in a broad range of applications. In the past, the electro-mechanical impedance method was utilized for assessment of metallic aerospace structures. However, advancements in materials engineering have led to the emergence of composite materials as the preferred choice for many aerospace applications. Limited work exists on application of the electro-mechanical impedance method to composite materials. To evaluate the behavioral differences between metallic and composite materials, a study into the impedance response of one dimensional beam structures with surface-bonded thin piezoelectric wafer sensors was conducted. Euler-Bernoulli beam theory is incorporated in the development of an analytical solution, along with viscous and strain-rate damping models, to evaluate the interaction between the piezoelectric wafer and the resulting bending moment and axial force in the beam. Modeling results were compared to experimental observations. Experimentally obtained damping characteristics were utilized to update analytical and numerical electro-mechanical impedance models. The sensitivity of the electromechanical impedance method to detect damage at various distances from a piezoelectric sensor was evaluated in composite and metallic materials using beams of different lengths. Using the results from these studies and evaluation of the effects of attenuation and structural geometry suggestions for structural evaluation using the electro-mechanical impedance method are presented.
Chemical Structure Analysis of Carbon-Doped Silicon Oxide Thin Films by Plasma-Enhanced Chemical Vapor Deposition of Tetrakis(Trimethylsilyloxy)Silane Precursor
Authors: Comeaux Jacob , Wirth William B. , Courville Justin , Luo Lingyiqian , Yan Hui , Jang Seonhee 
Published: January 2022

Abstract
Carbon-doped silicon oxide (CDO) thin films as low dielectric constant materials were deposited on both n-type silicon (Si) (100) and indium tin oxide coated polyethylene naphthalate (ITO/PEN) substrates, using the plasma-enhanced chemical vapor deposition of tetrakis(trimethylsilyoxy)silane (TTMSS) precursor. Chemical structures of the CDO films were analyzed by using FTIR (Fourier transformation infrared) spectroscopy and XPS (X-ray photoelectron spectroscopy). The chemical bonds related with hydrocarbon and Si–O were the main characteristics of the CDO films. The prominent peaks from the FTIR spectra included Si–O–Si stretching, Si–CH3 bending, Si–(CH3)x stretching, and CHx stretching modes. XPS spectra composed of the O1s, C1s, and Si2p electron orbitals were used to quantitatively analyze the elemental composition of the CDO films. The growth mechanisms of CDO films were dependent on the substrate type. For the ITO/PEN substrate, the lack of Si atoms on the ITO surface made difficulty in forming initial Si–O bonds, resulting in insufficient Si–O–Si structure. In comparison, the CDO films could grow easily on Si substrates due to pre-existing Si–O bonds on the surface. The chemical structures of the CDO films are expected to affect electrical and mechanical performances.
Micro Fin Array Configuration in Heat Transfer Enhancement in Mini-Channels
Authors: Carbajal Gerardo , Frear Colton , Clarke Charisma , Romero-Ramirez Edwar 
Published: January 2022

Abstract
An experimental study was conducted on a novel cooling device that consists of a rectangular micro-fins array placed inside the cooling device. A unique cover was designed and fabricated to allow the mass flow rate in and out and for measuring the temperature and pressure of the fluid. Scanning electronic microscope measurements showed that the average hydraulic diameter of the mini channel is 155 microns. The novel mini channels were tested with different volume flow rates and heat inputs. Two thermocouples and two pressure transducer sensors installed at the inlet and outlet recorded the pressure drop and temperature difference for the different flow conditions. A similar experiment was conducted on a dummy finless device to compare its performance with the minichannels. The experimental results showed an improvement in the heat transfer rate of the novel device compared with the dummy device. According to the experimental results, this study revealed an improvement in the cooling process by having rectangular micro-fins inside the device. For constant flow rates, the novel microchannel design was able to remove 5.6 times as much heat as the finless plate. It is expected that this novel device may increase the heat transfer rate significantly in aerospace and electronic cooling applications.
Effects of Geometrical Configuration on the Aerodynamic Performance of the Joined Wings
Authors: Alam M. D. , Soeimanikutanaei Soheil 
Published: January 2022

Abstract
Joined wing holds promises for future generation airplane application. It might provide a superior lift to drag ratio by reducing the effect of the wing vortex as well as the reduced drag. Moreover, it has higher structural rigidity, therefore, provides a lighter aircraft design facility. In this paper, the aerodynamic performance of a joined wing with a different sweep angle of the front and aft wings has been studied numerically. The Reynolds-averaged Navier–Stokes (RANS) equations were solved by the SST model to study the fully developed turbulence flow over the wing. The solution of the flow obtained by commercial software Ansys Fluent. The lift, drag and lift to drag ratio for the various angle of attacks have been calculated and plotted for the different specified geometries. The simulation result shows that the lift, drag coefficient increase with the increase of angle of attack whereas, the lift to drag coefficient increase first then gradually decreases for different joined wing configurations. In some cases, irregular behavior was observed, the vortex shedding behind the front wing could highly affect the aft wing so it might be the reason for this irregularity. The study findings emphasize that the aerodynamic wing performance for joined wing depends on the specification of each wing as well as also the mutual interaction between them.