bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Reformulated Transfer Matrix Method for the Dynamic Response of Multistep Euler-Bernoulli and Timoshenko-Ehrenfest Beams
Authors: Segalman Daniel J. , Khasawneh Firas A. 
Published: February 2023

Abstract
Stepped beams constitute an important class of engineering structures whose vibration response has been widely studied. Many of the existing methods for studying stepped beams manifest serious numerical difficulties as the number of segments or the frequency of excitation increase. In this paper, we focus on the Transfer Matrix Method (TMM), which provides a simple and elegant formulation for multi-step beams. The main idea in the TMM is to model each step in the beam as a uniform element whose vibration configurations are spanned by the segment’s local eigenfunctions. Utilizing these local expressions, the boundary conditions at the ends of the multi-step beam as well as the continuity and compatibility conditions across each step are used to obtain the nonlinear eigenvalue problem. Also, and perhaps more importantly, we provide a reformulation for multi-step Euler-Bernoulli beams that avoids much of the numerical singularity problems that have plagued most of the earlier efforts. When this reformulation is extended to multi-segment Timoshenko beams, the numerical difficulties appear to be mitigated, but not solved.
Numerical Investigation of Irrigant Flow Characteristics for Manual Endodontic Debridement
Authors: Janes Gregory , Kocharian Tikran , Manoharan Sanjivan 
Published: February 2023

Abstract
Root canal therapy or endodontic treatment is a nonsurgical approach used to remove the infected pulp, disinfect, and reshape the canal. Despite more than a century of technological improvements in root canal procedures, clinical studies indicate that microbial flora remain in the canal following standardized cleaning and shaping procedures using antimicrobial irrigants. Unfortunately, accessing this ‘dead zone’ in the apical third has been challenging given the large number of parameters that govern the flow pattern. Computational fluid dynamics (CFD) presents a powerful tool to investigate flow behavior in areas where experimental measurements are difficult to perform. This paper is divided into two sections. First, the influence of irrigant flow rate and needle insertion depth on velocity characteristics are computationally investigated for a simplified root geometry. The needle type considered is a 30 gage KerrHawe with a side vent for fluid discharge. The simplified root canal was modeled as a frustum with a length of 18 mm, diameter of 1.59 mm at the orifice, and a diameter of 0.45 mm at the apical constriction (6.5% taper). Following this, a more realistic root geometry is used to investigate how the results from part 1 scale with root geometry.
Influence of the Inlet Velocity on Oxygen Gradients in a Liver-on-a-Chip Model
Authors: Carvalho Violeta , Rodrigues Nelson , Rodrigues Raquel O. , Teixeira José C. , Miranda João , Lima Rui A. , Teixeira Senhorinha 
Published: February 2023

Abstract
Cancer continues to be one of the diseases that most affect the population around the world and different lines of research have been conducted to develop new therapies. However, a critical problem in this process is the lack of suitable in vitro preclinical platforms to assess the drug targets, toxicity, and efficacy. In order to surpass these issues, organ-on-a-chip (OoC) platforms emerged as a potential alternative for two-dimensional in vitro models, and computational simulations have played an important role. This tool boosts and supports the development process of OoC devices. Moreover, through numerical simulations, an overview of the fluid flow can be obtained which is useful for getting insights about the expected experimental results. Nevertheless, attention must be taken when defining the boundary conditions, fluid properties, and solution methods among other parameters that will affect the end results. In this regard, the aim of the present work is to evaluate the influence of varying the boundary conditions on the oxygen gradients along the liver-on-a-chip, namely imposing different velocities at the inlet and considering or not the convective term. It was found that for the OoC tested, by increasing the inlet velocity, the dissolved oxygen that reaches the organoids decreases.
Understanding the Impact of the Rim Protector on the Aerodynamic Performance of a Standalone Tire
Authors: Rath Shubham , Untaroiu Alexandrina , Fu Gen 
Published: February 2023

Abstract
Past studies have tried to understand the impact of the tire to understand its contribution to the overall drag on the vehicle. However, some features of the tire have not been studied to the extent to which is necessary to improve the drag performance of the tire. One such feature of the tire is the rim protector. The rim protector can have a considerable impact on the total drag contribution of the tire. In this study, the tire rim protector is parametrized, and design of experiments technique is used to understand the influence of the parameters on the drag performance of the tire as well as the effect on the flow structures around the tire.
In this study, a standalone tire model is used. The rim protector cross-section profile is simplified to a triangle. Both the base angles of the triangle as well as the altitude of this triangle are used as input parameters of the rim protector. Upon deciding the range of these parameters, the Kennard-Stone algorithm is used to create parameter sets to simulate for. Simulations were conducted in the open road domain. The open road domain was recreated using a cuboid enclosure with a vastly large volume with respect to the tire. Mesh parameters are chosen based on a grid convergence study. A turbulent flow regime and a transient time regime are used. The SST K-Omega turbulence model is selected for the simulation. Rotating wheel and moving ground boundary conditions are used. Drag area, which is influenced by the coefficient of drag and the frontal area of the tire, is chosen as the metric for the sensitivity study. A local sensitivity percentage is calculated, and 3D response surfaces are plotted to understand the impact of each of the parameters based on the drag area results from the design space.
It was found that of the three parameters, the altitude effected the drag performance of the tire the most, with a local sensitivity percentage of 70%. On the other hand, the base angles of the rim protector geometry each had a local sensitivity percentage of 20% and 10% each. This gives a very clear idea of how the rim protector shape can affect the drag performance of a tire. For further studies, a more detailed analysis on drag optimization can be conducted for the rim protector cross sectional geometry.
Heterogeneous Sensing and Bayesian Optimization for Smart Calibration in Additive Manufacturing Process
Authors: Rescsanski Sean , Imani Mahdi , Imani Farhad 
Published: February 2023

Abstract
Fused Filament Fabrication (FFF) is an extrusion-based additive manufacturing process that utilizes a filament material melted through a hot end extruder to generate a component. Despite the great potential of the process to drastically reduce time-to-produce, cost and material waste for the creation of geometrically complex components, the presence of diverse defects deteriorate the quality of the final build. Defects in FFF (e.g., voids, stringing, and varying track width) are primarily linked to improper calibration of parameters, including feed speed, extrusion speed, extruder temperature, and build plate temperature. Trial and error is the most common practice implemented to manually offset baseline parameters using an array of components generated with varying process parameters. However, fabrication with manual adjustment not only is time consuming, but also leads to a suboptimal solution that jeopardizes the strength and integrity of the generated components. We propose a novel Bayesian Optimization (BO) methodology in conjunction with heterogeneous sensing to determine optimal process parameters with a minimum number of experiments. BO consists of two steps: First, a Gaussian Process as a surrogate model that maps the relationship between controllable parameters (e.g., feed rate/flow rate ratio, extrusion temperature, and layer height) and build quality (i.e., the objective function that is derived from sensing data). Second, an acquisition function is defined from this surrogate to decide where to sample. We design build quality characterization model that formulated as an objective-scoring algorithm that returns the proportion of the effective specimen sensor measurements divided by the desired values. The experimental results on real-world case study shows that the proposed BO is capable of determining the values for parameters in just 7 steps with quality improvement of 0.036 from the best trial quality.
50kW PEMFC Hybrid Energy Management System Driving Strategies
Authors: Kim Younghyeon , Yu Sangseok 
Published: February 2023

Abstract
A 50kW class PEMFC and 30kAh battery was evaluated to find a correlation between the stack net power overshoot and the stack temperature for sudden load change. First, a 50kW class PEMFC (Proton Exchange Membrane Fuel Cell) model and a battery model were designed and verified using experimental values. Sensitivity study of Energy Management system strategy was also carried out to find the optimal power ratio of the stack and the battery. Next, net power overshoot of the stack and the temperature data of the stack during a sudden load change were compared. The results show that the main factors affecting the Energy Management System strategy of the stack is the stack temperature.
Non-Newtonian Fluid Apparent Viscosity Correlation Between Experimental Data and Computational Fluid Dynamics Results, A Case Study From Automatic Transmission Fluid Filtration Industry
Authors: Kehler Patrik , Arenas Nicolas , Meixner Ferdinand , Toews Jovan , Esquivel Liz , González Vivian , Benzo Renato , H. Kurita Jorge 
Published: February 2023

Abstract
Evidence of a Non-Newtonian behavior of automatic transmission fluid at sub-zero conditions was presented by several authors such as Khalil et. al. Accurate viscosity data of this fluid at cold conditions are critical, especially in the very competitive automotive industry. The proper design of a transmission fluid filter, this is, the calculation of the effective area of filtration media, depends heavily on this information. Technical difficulties of viscosity measurements by different shear rates at subzero conditions are driven by its cost and accuracy. In order to solve this issue, here is presented an alternative indirect viscosity measurement. By assuming Darcy’s law behavior on a fluid flow through a simple single flat sheet media configuration, for a given temperature and shear rate, apparent viscosity was calculated. This paper shows a correlation between Computational Fluid Dynamics (CFD) results and Test data. Effective shear rates in the porous media were obtained from fluid velocities at media face and porous media grade. It was observed a consistent shear thickening behavior. Results of applying this viscosity correlation, at the filter design stage, gave us a much better prediction of pressure drop performance in the actual filter test stage. An average of 40% difference between measured pressure drop and predicted pressure drop CFD was observed before applying this factor. The test data to CFD result difference was reduced to 10% average.
In addition to this correlation on porous media flow, a simple analysis of internal flow through a circular tube was analyzed. The Darcy-Weisbach equation gave us a theoretically calculated pressure drop for a given flow rate, tube inner diameter, and length. Associated Computational Fluid Dynamics simulation was conducted at the same boundary flow conditions. Test data from this analysis were compared to theoretical calculations and this CFD results.
This last analysis it was clearly observed the apparent viscosity dependence on shear rate. This is, for a given temperature and fluid, different flow rates showed pressure drop values that implied different fluid apparent viscosities.
This work set the path to develop correcting factors on viscosity values for pressure drop hand calculations in the automatic transmission filter porous media. Filter designers can dimension the porous media effective area in a more precise fashion, especially for operating conditions in very cold conditions, where this non-Newtonian behavior is frequently observed. Also, transmission fluid makers could use this data to better develop oil blends to avoid this cold freeze characteristic.
Taxonomy of Stair-Climbing Mechanisms for Wheelchairs
Authors: Desai Shubhankar , Piovesan Davide 
Published: February 2023

Abstract
Autonomous climbing mechanisms have been present for over a couple of decades now, and it has been a part of various equipment such as wheelchairs, agricultural robots, rescue robots, etc. A centralized database of all existing stair-climbing mechanisms for wheelchairs can aid in selecting the appropriate one for the subjective terrain and/or finalizing the direction of additional research and design.
This systematic literature review on autonomous climbing mechanisms for applications such as crossing obstacles, stair climbing, as well as climbing over/onto higher platforms, etc. assesses parameters such as climbing efficiency, power efficiency, stability, etc. This also initiates a centralized all-inclusive classification for existent robotic climbing mechanisms. By identifying commonly used components such as different ‘link and joint’ types as well as the nature of motion performed by the mechanism while climbing, different mechanisms are broken down into categories such as ‘Wheeled, Legged, Hybrid’. These are further broken down into ‘2-spoked, 3-spoked, etc… up to n-spoked and ∞-spoked’ with consideration to the parts interfering with the obstacle surfaces. Additionally, based on the nature of motion, such as continuous, periodic intermittent, sporadic, and hybrid, another aspect which is the nature of resultant motion is added to the classification. The control systems Used for different mechanisms are also a matter of concern for this review as it becomes a differentiation factor while categorizing into subdivisions under a hierarchical system. Some mechanisms can be controlled numerically, some receive their limitations on movement based on electronic signals received from the set of sensors used onboard, while some of them get limited by mechanical stoppers or limiters added from the early design stage. With the increasing acceptance and appreciation of robotic equipment in the rescue and safety section, the evaluation of climbing mechanisms for the availability of fail-safes and recovery majors is also considered a factor.
This review introduces a categorical structure to the classification of autonomous climbing mechanisms which can be used efficiently while selecting a climbing mechanism for a given set of requirements, or tasks.
An Automation Toolbox for Nonlinear FEA of Rotary Shouldered Threaded Connections
Authors: Song Fei , Li Ke 
Published: February 2023

Abstract
A rotary shouldered threaded connection consists of a pin element and a box element and acts as a key component to screw together the tools and subs used on the BHA (bottom hole assembly). Functionally, the rotary shouldered connection upon makeup must separate internal and annular pressures, transmit torque, and withstand fatigue loads when drilling through many revolutions in a curved well section. If these connections fail during drilling operation, a twist-off could occur, which could possibly lead to loss of the bottom BHA section in the hole with a tremendous amount of nonproductive time. Finite element analysis (FEA) can be used to capture the nonlinear interactions between the threads and between the seal faces of the pin and box subjected to a tightening torque and service loads such as axial and bending loads. To expedite and standardize such a simulation process, in this paper, a CAE automation toolbox has been developed for standardizing and accelerating nonlinear finite element analysis of rotary shouldered threaded connections. Such a toolbox can automatically create the CAD geometry of the threaded connection that contains tens of design parameters per the standard drawings, assignment of material properties with elasto-plastic models, generation of a desired mesh with refinement in the areas of interest, definition of appropriate contact interactions, application of loading and boundary conditions, and postprocessing of stress and strain results for visualization. The analysis results obtained from the developed automation toolbox were validated by comparing to those obtained manually with a commercially available finite element code (Abaqus). Excellent agreement was observed. The use of the automation toolbox can help shorten the analysis effort from days to only a few hours for nonlinear finite element analysis of rotary shouldered threaded connections. The automation toolbox has been widely utilized to accelerate design iterations of advanced rotary shouldered connections for enhancing drilling performance and reducing maintenance cost for drill stem components as well as root cause analysis of threaded connection failures.
Mechanical Orthosis for Knee Osteoarthritis Patients to Correct Internal Knee Joint Warping and Achieve Normal Knee Joint Rotation Motion
Authors: Kubota Kazuma , Katsube Go , Qi Song , Yano Ken'ichi , Matsui Naruki , Shinoda Nobuyuki 
Published: February 2023

Abstract
Knee osteoarthritis (OA) is the most frequent form of lower limb arthritis. The severity of knee OA patients is graded, with moderate patients having deteriorating symptoms due to abnormal lower extremity alignment and poor lower leg rotation. To prevent the worsening of symptoms, orthoses are prescribed for patients with knee OA. Although conventional orthoses can either correct alignment or guide the rotation of the lower leg, it is difficult for them to achieve both corrective force and normal range of rotation. Therefore, an orthosis equipped with a mechanism that can simultaneously correct alignment and guide rotation of the lower leg is necessary. In this study, we focused on the relationship between the change in the tilt angle of the lower leg and the rotation of the tibia to enable both corrective force and the induction of rotation of the lower leg. We then developed a lower limb orthosis equipped with a mechanism to both correct alignment and normalize rotation. Finally, walking experiments with actual patients with knee OA demonstrate the effectiveness of the proposed mechanism in correcting abnormal alignment and guiding the patient to a regular rotation.
Detecting Defects in Low-Cost 3D Printing
Authors: Forte Mark , Eisenhour Madison , Malkowski Ryan M. , Radhakrishnan Pradeep , Brown David C. 
Published: February 2023

Abstract
3D printing is widely used in prototyping projects, but low-cost, open-type 3D printers can produce defects, wasting time and material. This project’s goal was to develop a system to detect defects automatically during the printing process to prevent that waste. We developed DaR3D, a monitoring system that can detect slippage in 3D printed parts and alert the user as soon as it is detected. The system’s environment consists of a webcam fixed to a custom 3D printed mount, an enclosure, and lighting. A variety of defect detection algorithms were researched. DaR3D’s detection algorithm acquires an image from OctoLapse, removes the background, then uses statistical analysis to compare it to a previous image. If the images are different enough, the algorithm determines that slippage has occurred. The resulting system correctly identifies slippage in prints with 89.6% accuracy, using samples from two different 3D printers and many different printed models. The paper will discuss the process, challenges and planned future work.
Non-Destructive Infrared Thermographic Curing Analysis of Polymer Composites
Authors: Rahman Md Ashiqur , Becerril Javier , Ghosh Dipannita , Islam Nazmul , Ashraf Ali 
Published: February 2023

Abstract
Infrared (IR) thermography is a non-contact method of measuring temperature that analyzes the infrared radiation emitted by an object. Properties of polymer composites are heavily influenced by the filler material, filler size, and filler dispersion, and thus thermographic analysis can be a useful tool to determine the curing and filler dispersion. In this study, we investigated the curing mechanisms of polymer composites at the microscale by capturing real-time temperature using an IR Thermal Camera. Silicone polymers with fillers of Graphene, Graphite powder, Graphite flake, and Molybdenum disulfide (MoS2) were subsequently poured into a customized 3D printed mold for thermography. The nanocomposites were microscopically heated with a Nichrome resistance wire, and real-time surface temperatures were measured using different Softwares. This infrared thermal camera divides the target area into 640 × 480 pixels, allowing measurement and analysis of the sample with a resolution of 65 micrometers. Depending on the filler material, the temperature rises to a certain maximum point before curing, and once curing is complete, polymer composites exhibit a rapid temperature change indicating a transition from viscous fluid to solid. MoS2, Polydimethylsiloxane (PDMS) without filler, and PDMS with larger filler are ranked in order of maximum constant temperature. PDMS (without filler) cures in 500s, while PDMS-Graphene and PDMS Graphite Powder cure in about 800s. The curing time for PDMS Graphite flake is slightly longer (950s), while MoS2 is around 520s. Therefore, this technique can indicate the influence of fillers on the curing of composites at the microscale, which is difficult to achieve by conventional methods such as differential scanning calorimetry. This nondestructive, low-cost, fast infrared thermography can be used to analyze the properties of polymer composites with different fillers and dispersion qualities in a variety of applications including precision additive manufacturing and quality control of curable composite inks.