bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Liner Albedo on UVC Irradiation Control
Authors: Mamidi Rachana , Sharifbaev Arvin , Patel Shivani P. , Gacura Matthew , Vanderlaan Gary , Ji Xiaoxu , Piovesan Davide
Published: February 2023

Ultraviolet germicidal irradiation (UVGI) has been used successfully for the sterilization of tools and whole environments. The advantages of this method are numerous. There does not need to be any physical contact with the artifact to be sterilized; the procedure is quite fast and allows for covering large areas. As a drawback, the cost of these systems is often still prohibitive, and the necessity of the light to hit the surface to be effective might leave residual contamination in the shadowed areas within lumens. To avoid potential shadows, the internal surface of an environment can be covered with specific reflective materials appropriate for the wavelength of the irradiation source. We designed a cost-efficient sterilization chamber that uses UVC for decontamination (SHIVA, Small High-Intensity ultra-Violet Antimicrobial chamber.). The design focuses on a decontamination chamber easy to manufacture for rapid deployment. The device can also be used by the general public for sanitizing non washable materials. We tested the control of irradiation dose, based on different types of materials lining the internal part of the sterilization chamber. The reflectance of the material in the UVC Spectrum was critical for the increase of irradiation dose at the target. We tested 3 lining materials (Teflon, Aluminum, and Vinyl) using an 8W UVGI fluorescent lamp in the Ultra Violet-C (UVC) wavelength range, with peak irradiation at 254.3 nm. Variations between linings could provide a variation in dosage up to 30%. We observed that Vinyl reflectivity in the UVC range is close to 90% and provides the best compromise between the price of the lining, and the final irradiation dose provided to the samples. An increase in total irradiation allows for a more energy-efficient system that could utilize batteries rather than electrical energy from an outlet; hence improving portability.
Continuous Stereolithography 3D Printing of Multi-Network Hydrogels in Triply Periodic Minimal Structures (TPMS) With Tunable Mechanical Strength for Energy Absorption
Authors: Guo Zipeng , Yang Ruizhe , Liu Jun , Armstrong Jason , Zhao Ruogang , Zhou Chi
Published: February 2023

A fast additive manufacturing (AM) protocol to fabricate multi-network hydrogels is reported in this work. The gas-permeable PDMS film creates a polymerization-inhibition zone, facilitating the continuous stereolithography (SLA) 3D printing of hydrogels. The fabricated multi-bonding network integrates the rigid covalent bonding and the tough ionic bonding. The elastic modulus and strength could be effectively tuned by varying the ratio between the covalent and ionic bonding networks to fulfill various loading conditions. The printed triply periodic minimal structures (TPMS) hydrogels demonstrated high compressibility for up to 80% recoverable strain. Moreover, the dried TPMS hydrogels show novel energy absorption properties. We fabricated uniform and gradient hydrogels and compared their energy absorption capability. The anisotropy and quasi-isotropy behavior of TPMS structures were analyzed using simulation studies, providing insights into designing and controlling the TPMS structures for energy absorption. The results showed that the gradient TPMS hydrogels are preferable energy absorbers and have potential applications in impact resistance and absorption.
The Design Evolution of a Lower Extremity Exoskeleton Device for Leg Muscle Rehabilitation
Authors: Fusilero Patrick , Reyes Andres , Trejo Rodrigo , Madireddy Indeever , Vemuri Aayush , Zaidi Sohail , Viswanathan Vimal
Published: February 2023

The proposed design of the robotic-assisted pneumatic knee-brace is activated by using surface electromyographic (EMG) sensors to activate motion for rehabilitation exercises. These muscles are actuators powered by a pneumatic system that expands or contracts depending on the compressed air entering the system. An Arduino-based controller performs the pneumatic control. The first design consisted of two fluidic muscles mounted on a human leg where several EMG sensors were placed on the upper part of the leg randomly to activate the controllers. This device is currently further modified for patients who have undergone total kneed replacement surgery and need leg rehabilitation exercises to recover. In this design, multiple fluidic muscles are incorporated to minimize the reaction time of the device. The brace is designed to mount on a knee of a sitting person and consists of four bars (two bars are mounted on the thighs and the remaining two on the calves). EMG sensors are placed on six muscles, including Vastus Medialis, Vastus Lateralis, Rectus Femoris, Semitendinosus, Biceps Femoris, and Semimembranosus. The new knee brace is fully characterized by mounting it on various sitting persons’ legs. In the current experiment, a healthy person’s legs are targeted. The leg motion is being investigated as a function of air pressure inside the fluid muscles and the location of EMG sensors on the legs for various age groups. The current presentation will include the systematic design improvement in our knee-brace device and its applications. The software that processed the EMG sensors was modified to reject the input noise to give an accurate and fast response. The details of the software and its processing will be discussed in greater detail. The device characterization results will be summarized for practical applications.
Mathematical Modeling of a Piezo-Actuated Cantilever Beam With Interferometer Feedback
Authors: Kochavi Jordan David , Xing Siyuan
Published: February 2023

Laser interferometry, commonly used in high-precision motion control systems, is rarely adopted in experimental vibration analysis because their installation and mounting are invasive to dynamical systems. However, new technology in high-precision manufacturing, such as vibration-assisted machining, has shown the meaningfulness of using laser interferometers implemented in motion control systems for vibration analysis, system identification, and feedback control. To this end, this study investigates the use of laser interferometry for vibration analysis through a piezoelectrically actuated cantilever beam. The complete dynamics of the cantilevered beam with a piezoelectric actuator and a laser interferometer is modeled through the Euler-Bernoulli beam theory. Through the method of separation of variables, the original continuous system is transformed into a discrete system represented in a state-space form. The response of the beam is analytically predicted, then compared with the numerical result from a multibody model constructed in Simscape. The frequency response at the retroreflector is obtained through the Laplace transformation of the state-space form. It is found that the first modal frequencies from analytical prediction precisely agree with their experimental counterpart.
Coexisting Unstable Periodic Motions in the Rössler System
Authors: Xing Siyuan , Luo Albert C. J.
Published: February 2023

This paper studies the coexisting unstable periodic motions in the Rössler system. The periodic orbits are predicted by the corresponding mapping structures of the implicit discrete maps in conjunction with initial and periodicity conditions. The stability of the periodic motions is discussed through eigenvalue analysis of the corresponding variational equations. The harmonic amplitudes and phases of the periodic motions are presented.
Heat Flux Analysis of a Solar Thermal Collector Incorporated With Optimized Involuted Reflectors
Authors: Lim Celine S. L. , Sobhansarbandi Sarvenaz
Published: February 2023

Solar energy plays a vital role in the future of clean energy production due to its availability all year round. Some prominent solar energy technologies, e.g. concentrating solar power (CSP), have the ability to focus/concentrate sunlight for large-scale commercial use. Meanwhile for smaller-scale residential use, solar water heating (SWH) systems are often used to provide hot water for household applications, where the solar collectors are the main components of such systems. The type of solar collector of interest in this study is the heat pipe evacuated tube collector (HPETC). To enhance the system’s thermal and optical efficiencies, this study investigates the incorporation of a custom-made involuted reflector mirror to a single HPETC through employing SolTrace’s optical ray tracing method, where the heat flux around the circumference of the absorber tube can be obtained. The maximum and averaged heat flux is compared between a traditional HPETC system and the HPETC system with the involuted reflectors. The result from this study showed that the HPETC system with an optimized involuted reflector experiences up to ∼ 55.3 % increase in maximum heat flux, and an increase up to ∼ 81.2 % in average heat flux across the absorber tube. Consequently, the HPETC incorporating the custom-made involuted reflectors yields to more collected heat and is capable of providing more hot water to be used for residential SWH applications.
Heat Transfer and Flow Characteristic of Sinusoidal Wavy Microchannel Heat Sink With Different Phase Shift
Authors: Shuvo Abdul Aziz , Bappy Md. Omarsany , Tikadar Amitav , Paul Titan C. , Morshed A. K. M. Monjur
Published: February 2023

Microchannel heat sinks (MCHS) are promisingly utilized to remove large heat flux from microelectronic devices. However, the velocity and thermal boundary layers grow continually in a straight microchannel. As a result, the performance of the microchannel degrades. Disrupting the formation of the boundary layer can enhance the performance of MCHS. One approach to achieve that goal is to develop a wavy channel rather than a straight microchannel (s-MCHS) which hinders the continual growth of boundary layers due to its waviness. Numerous researches suggested that wave amplitude increment and wavelength decrement enhanced the chaotic advection and better coolant mixing. Thus, heat transfer and pressure drop were increased in the MCHS. Although wavelength and wave amplitude in a wavy MCHS (w-MCHS) significantly impact heat transfer performance, the phase shift (θp) between two wavy walls in an MCHS also affects the flow and heat transfer characteristics. When the upper and lower sinusoidal walls are in different phases, the cross-sectional area of the MCHS varies. So, the cross-sectional flow area variation creates an adverse pressure gradient in the MCHS. which causes more flow reversal and better coolant mixing, resulting in improved thermal performance.

The current study aims to study the flow and heat transfer characteristics in w-MCHS for three different phase shifts, θp = 0, π/2, π, under laminar flow conditions. Re ranges from 300 to 800 in the study. w-MCHS with phase shift, θp = π/2, π always shows higher Nusselt number (Nu) than s-MCHS and w-MCHS with phase shift, θp = 0. An increase in surface area due to phase shifts, θp = π/2 and θp = π in wavy MCHS, is negligible and the enhancement in heat transfer of phase-shifted w-MCHS is caused by interruption, reinitialization, and reattachment of boundary layers. In the current numerical study, Nu was found to increase with the phase shift and found 7 times higher than s-MCHS at phase shift, θp = π for wavelength (λ) = 3.5 mm. Besides higher heat transfer and better coolant mixing, the phase shift in wavy MCHS causes increased shear stress and pressure drop due to chaotic flow in wavy MCHS.
The Design of an Open-Source 3D Printable Humanoid Robotic Hand: CHUCHU
Authors: Harling Joseph , Yeh Eric , Ma Gloria , McCusker James , Cuckov Filip
Published: February 2023

One of the heavily desired aspects of human functionality to implement into robotics is the dexterity of our hands for manipulating objects. As it stands, there is a healthy market for robotic hands; however, the market is heavily weighted on either end of the price-functionality spectrum. A hand can provide exceptional human-like features and flexibility but is priced far out of range for small groups or individuals. Or the hand is below $2k but has limited characteristics that mimic the human hand.

This project details the Cognitive Hand Unit for Collaboration with Human Users (CHUCHU), a humanoid robotic hand designed to be affordable, accessible, and comparable in features to other solutions on the market. Its 3D-printed fingers feature fully actuated joints that are controlled by linear actuators with positional feedback, while a spring tendon system is used to manipulate the underactuated joints to keep them compliant. The fingers feature force sensors to provide feedback to the PCB electronics containing the microcontroller and circuitry. The microcontroller utilizes Micro-ROS to receive and send feedback to Linux workstations for overall control.

The resulting iterations of the fingers were subjected to mechanical stress testing for qualification and comparison. Along with this, an analysis of the inverse kinematics of the design is presented in this paper.
Design of a New Vehicle Front End Structure to Optimise Crashworthiness
Authors: Elmarakbi Mohab , Combrinck Madeleine , Elmasry Ahmed , Elmarakbi Ahmed
Published: February 2023

Within this paper methods in reducing weight and optimizing the front-end structure, by specifically targeting both new materials and redesigning the cashbox, to improve crashworthiness were investigated. This was accomplished through redesigning the cross-sectional shape of the crash box, trigger location and type of trigger used, and the use of different materials. The optimal crash box design was found to be a hexagonal prism that incorporated a central trigger which reduced the thickness from 2mm to 1mm. Moreover, the ideal material was identified to be SGF/PA6/GnPls. When this optimized crash box was incorporated to the front-end structure and the ideal material applied to the bumper beam, the fully optimized front-end structure reduced the weight by 75%, reduced peak force by 28% and increased specific energy absorption by 94% and 55% for a frontal and side collision respectively.
An Experimental Setup to Study the Fundamental Phenomena Associated With Biomass Combustion
Authors: Silva João Pedro , Teixeira Senhorinha , Teixeira José Carlos
Published: February 2023

During the combustion of solid biomass in a grate-fired boiler, each particle experiences a sequence of processes which include heating, drying, devolatilization, and char combustion. Furthermore, in the gas phase, products may react with oxygen. As it is impossible to maintain repeatable and fully controlled environments, and to monitor all the dynamics involved in field-scale experiments, it becomes necessary to perform investigations at a small scale. This should be sufficient to provide a controlled environment, and large enough to define realistic conditions. In this way, to evaluate the thermal behavior of biomass particles under an oxidative atmosphere and determine the composition of the flue gas released into the atmosphere, a small-scale reactor was developed and presented in this paper. The results of the different mass loss profiles at different combustion conditions and with samples with different size are presented. Additionally, the composition of the gases released over the devolatilization period was determined using a gas chromatograph and they are here correlated with the reactor temperature. This work proved to be very useful since it is important for the computational modeling of industrial boilers and is required for the design and operation of biomass combustion equipment. In the future, this study will be very valuable to develop a computational tool to analyze the combustion process inside an industrial grate-fired boiler.
Effect of Tool Material and Process Parameters on Surface Conditions in Single Point Incremental Forming (SPIF) of Polymeric Materials
Authors: Ragai Ihab , Goldstein Joe , Meyer Cayla , Upcraft Clayton
Published: February 2023

Single point incremental forming (SPIF) is a relatively new process for forming sheet products. Typically, the sheet is clamped into a fixture and is incrementally formed by moving a hemispherical end-mill tool using a multi-axis CNC milling machine. The tool deforms the material in each pass until the desired geometry is achieved.

Friction between the tool and the formed sheet can have detrimental effects on the final geometry. The increase in friction coefficient can result in a significant decrease in sheet formability due to excessive thinning and subsequent fracture. Additionally, tool rotational speed may also contribute to the surface roughness of the formed part. The interaction between the tool and workpiece materials over relatively small areas of surface asperity is typically where friction and subsequent damage take place.

The purpose of this research is to study the effect tool rotational speed as well as tool-workpiece material interaction on the surface condition and formability of formed components. Three polymeric materials have been considered herein, namely polypropylene (PP), polycarbonate (PC), and polyvinyl chloride (PVC). Spindle speeds varied from 600 to 1800 rpm. Four tool materials were also investigated, namely stainless steel, copper 110, beryllium-copper, and thermoplastic syntactic foam. Full factorial design of experiments took place. The parts were allowed to form until fracture takes place. Subsequently, the height of the cone was measured and used as representation of formability. Additionally, surface roughness and asperity height distribution were analyzed using both profilometry and microscopy. The aim is to explore possible correlations between process parameters and surface condition and their effect on single point incrementally formed shapes.
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

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

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

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

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

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

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

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

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

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

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

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

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.
Bruise Development Measurement in Apples Using Thermal Imaging Technique
Authors: Gurupatham Sathish K. , Bailey Caleb
Published: February 2023

Apple is an important fruit worldwide with nutrition and a huge market value. However, due to the mechanical damage during its handling after the harvest, millions of dollars are lost in the apple industry. Bruise (subcutaneous) is a mechanical damage caused to a fruit without any tearing of the fruit-skin. It could be caused by a mechanical impact, vibration, or compression which the fruit might come across during its handling after the harvest. It results in local degradation of the flesh tissue with browning effect with time. Normally, apple bruises take place beneath the peel and are difficult to detect by either visual or automatic color sorting. Thermal imaging offers a promising, contact-free, alternative technique for bruise detection in apples. Thermal imaging technique measures infrared energy emitted from the object surface which is converted into a thermal map called a thermogram. In the literature, there has been some work done on the influence of temperature and relative humidity of the surrounding on bruise susceptibility of fruits. In this paper, the influence of relative humidity in bruise development on apple was investigated applying thermal imaging technique. To accomplish this, two batches of healthy, almost same-sized, yellow and green apples with ten apples per batch were considered. The apples were subjected to a mechanical impact by dropping them from a constant height ensuring the fruit skin is not torn by the impact and the impact is same is for all the apples. Then, they were thermal imaged with the focus on their bruises. They were kept and observed at two different temperatures and relative humidity. The first set involved the relative humidity of 40–43% with room conditions whereas the second one involved the relative humidity of 80%–82% in the freezer compartment of a domestic refrigerator. For all the trials, the same condition was maintained for the fruits throughout the three-day observation. At the end of stipulated observation period, the fruits were thermal imaged to capture the bruise development for the different relative humidity levels for two different temperatures. The observation was repeated for three times to obtain the repeatability.

The results show that the bruise development is faster for the higher relative humidity than for the lower one. This could be due to the lower transpiration rate of water from the fruits at higher relative humidity. Also, the water potential under the bruised skin decreases faster for lower relative humidity condition which results in decreased bruise development.
Using Deep Convolutional Neural Networks (DCNN) to Learn by Sensor Signal Classification Critical Local Regions of a Physical Shaft-Rotor System: A Complex Mechanical System Example for Machine Learning Considerations
Authors: Papageorgiou Pantelis Panagiotis , Georgiou Ioannis T.
Published: February 2023

Complex machinery contains critical regions, such as revolute joints-ball bearings-journal bearings, that are prone to damage initiation and growth. If not detected early, damage in critical local regions leads to premature failure. The overall complexity of an integrated system limits developed classical methods from detecting early damage in complicated local areas. A pure experimental data environment could provide solutions given the broad impact of machine learning. Here an interesting idea is introduced to support a machine learning framework for damage detection in local critical regions. The vibration field developed in a local area surrounding a ball bearing support of a lab flexible shaft-rotor system was measured by a set of accelerometers to form a dataset environment. It was used as an experience for machine learning by a deep convolutional neural network adapted from the AlexNet architecture. Our main result is the casting of a solid mechanics prediction problem into a classification problem and eventually computing a solution by a deep machine learning technique. Technology innovations improve computer speed, data storage media, and graphics processing units. These factors are turning existing machine learning techniques into state-of-the-art prediction tools that can be adapted and developed to exploit large volumes of vibration data for diagnostics. Data-driven predictive-diagnostics results in improved condition monitoring of the complex machinery system with economic gains form estimated low-cost maintenance and energy savings. Classical condition monitoring techniques cannot learn from experiences predictive models of the dynamics-diagnostics of onboard ship and aircraft machinery operating under varying environmental conditions.
A Computationally Efficient Approach for the Simulation of Silicon Anodes in Lithium-Ion Cells
Authors: Webb Rebecca , Chen Xiaoling , Mazumder Sandip , Canova Marcello
Published: February 2023

Silicon has emerged as a frontrunner for next generation anode materials due to its high theoretical gravimetric capacity (∼4200 mAh g-1). The presence of volume changes and stress in silicon anodes introduces strong, nonlinear couplings with the lithiation and delithiation process, requiring a significant increase in the complexity of the mathematical framework describing its behavior.

A mathematical description of the multiphysics coupling process is presented, requiring the simultaneous solution of the spherical diffusion equations for a binary system with volume change and stress applied to a representative particle. The resulting model description is in the form of a nonlinear set of index-2 Partial Differential and Algebraic Equations (PDAEs).

This paper proposes a computationally efficient approach to solve the PDAE system, with the objective of predicting the lithium concentration, volume change, and stress generation during galvanostatic charge and discharge conditions. A semi-explicit scheme is proposed to reformulate the original system into decoupled sets of nonlinear ordinary differential equations and nonlinear algebraic equations. After a grid sensitivity analysis in the space and time domains, the proposed approach results into a computationally efficient implementation that ensures the numerical accuracy in solving this problem, for use in lithium-ion battery control and estimation applications.

This study shows that a semi-explicit scheme can produce results at a rate 2.5–3.5 times faster with comparable accuracy when compared to traditional fully implicit solution methods. Limiting the number of Newton iterations in the semi-explicit scheme further reduces the semi-explicit computation time by 25 minutes.
Simplified Geometries for Intracranial Acoustic Modeling
Authors: Cites Marianne E. , Dumm Christopher M. , Hiers Anna C. , Klinzing George E. , Balaban Carey D. , Vipperman Jeffrey S.
Published: February 2023

The geometric complexity of the contents of the head confounds mechanical analysis of intracranial structures. Conventional models for computational analysis are typically created through a laborious segmentation and reconstruction process highly dependent on expert labor and anatomical insight. This study explores a deterministic process for construction of a simplified, anatomically-relevant head model appropriate for acoustical modeling. Various key anatomical features with acoustical significance are reviewed. Models of increasing complexity are generated, spanning a range from coupled concentric spheres to more advanced geometries incorporating ventricles, brain structures, and other anatomical landmarks. Geometric relevance of the models is assessed by comparison to a high-fidelity computational geometry derived from medical imagery. These techniques and models are useful for a variety of studies investigating phenomena such as traumatic brain injury mechanics and industrial safety.