bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Using 3D Printed Parts on the Torque-Tension Relationship of Threaded Joints
Authors: Robusto Francesco , Nassar Sayed A. , Lee Joon Ha , Gerini-Romagnoli Marco , De Agostinis Massimiliano
Published: February 2023

This study investigates the effect of shot-peened additively manufactured aluminum parts on the torque-tension relationship of threaded joints, as compared to extruded components. Steel flange head bolts are utilized. A computer-controlled RS torque-tension system is used for tightening test joints to a target preload, and frictional data is collected at a high sampling rate. A final group of additive manufactured specimens is analyzed to evaluate the effect of machining on the tribological response of the bolted joint. The underhead friction coefficient is measured over 5 consecutive tightenings, with and without disassembly and cooldown. The bearing surface topology is analyzed using an optical profilometer after each tightening. Fasteners and parts are ultrasonically cleaned, and tests are performed with no lubrication. Cooldown between consecutive tightenings had a significant effect on the frictional characteristics of non-machined additively manufactured joints. The lower surface integrity of the 3D printed components resulted in severe damage to the bearing surface after 5 tightening operations. Discussion of the results and conclusions are provided.
Enhancing the Performance Measures of Abrasive Water Jet Machining on Drilling Acrylic Glass Material
Authors: Shanmugam Ragavanantham , T. Geethapriyan , Thangaraj Muthuramalingam , Ramoni Monsuru
Published: February 2023

Abrasive Water jet Machining finds its application on extensive range of materials. Both ductile and brittle materials can be machined by this process, but the material removal is different in both the cases, i.e., by Ductile fracture and Brittle fracture respectively. When it comes to brittle materials, conventional machining processes cannot be used due to a number of limitations of the material. Thus, non-conventional machining is a rather preferable choice for brittle materials. However, the quality of machining might vary, as it is dependent on some input parameters such as — Abrasive size, Water jet Pres-sure and Abrasive Flow rate. The quality of the machining for a drilling operation is evaluated based on the hole parameters i.e. — Circularity, Taper ratio, Overcut and Material Removal Rate (MRR). The process parameters are varied in accordance to the desirable outcome to be obtained. Outcomes like MRR and circularity are required to be maximized, whereas Taper ratio and Overcut have to be minimized. The effects and interactions between different parameters on the outcomes are studied using Analysis of Variance (ANOVA).
On the Development and Evaluation of a Framework for Brain-Computer Interface and Vibrotactile Feedback for Human-Robot-Interaction in Virtual Spaces and Robotic Hardware
Authors: Hazra Sudip , Whitaker Shane , Shiakolas Panos S.
Published: February 2023

Research in Brain-Computer Interface (BCI) aims to understand human intent with the goal to enhance Human-Robot Interaction (HRI) especially in the field of assistive robotics. The goal of this research is to develop a behavioral sequence based framework to help persons with upper limb disabilities to maintain self-dependence. The framework aims to operate in stages and links multiple functional components to identify human intent and control a robotic arm. The development, operation, and evaluation of the framework and the linked functional components to acquire, process, evaluate, and map BCI signals generated using facial expressions and head movements to predefined actions will be introduced.The framework will integrate multiple functional components such as a non-invasive BCI control device, a vibro-tactile haptic feedback device, a visual feedback environment, the evaluation and training platform, and a robotic arm. The robot pick, move and place actions are mapped to different facial expressions and presented using haptic and visual feedback to the user for classified action verification before performing the process using a robotic arm. The initial evaluation of the developed framework was 100% successful with two volunteers who also provided constructive feedback. The initial successful evaluation provides confidence to further test the framework with more volunteers to identify limitations and/or areas of improvement and its application for further research in HRI as it applies to assistive robotic systems.
A Topology Optimization Methodology With Vibration Constraint for an Aerospace Bracket Design
Authors: Karabiyik Hüseyin , Eroglu Osman , Metin Eskimez Muhammed , Oncul Berk Oncu , Yilmaz Muhammet Tayyip , Gökdağ İstemihan , Gorguluarslan Recep M.
Published: February 2023

The most important need in the aviation industry is the realization of high-strength and lightweight designs. For this reason, topology optimization methods have become widespread recently. Besides, meeting the natural frequency requirements is one of the important design elements. However, topology optimization with stiffness maximization requires a static finite element analysis evaluation while the natural frequency calculation requires a modal analysis evaluation. Using these two different analysis procedures at the same time in the topology optimization process, on the other hand, is a challenging task. To address this challenge, a topology optimization methodology that accounts for the natural frequency constraint in a compliance minimization process is presented in this study. Since the commercial software can either minimize compliance or minimize the vibration frequency at one time, using these two different analysis procedures at the same time together stands out as an innovative aspect of this study. The applicability of the developed methodology is shown for two bracket designs; namely, the so-called GE bracket and a real-world satellite bracket with natural frequency and mass constraints. The prototypes of the designs are fabricated using the additive manufacturing technique.
The Effect of Multi-Stage Age Treatment on Mechanical Properties of 7075 Al Alloy
Authors: Rahman A. H. M. E. , Abu-Mahfouz Issam , Banerjee Amit , Wisniewski Johnmark
Published: February 2023

One of the widely used aerospace alloys is 7075 aluminum alloy (AA) because of its high tensile and compressive strength and good response to exfoliation corrosion. A solution heat treatment followed by artificial ageing is known as T6 temper designation was initially used to obtain peak strength for 7075 AA. The artificial aging, done at 115°C to 130°C (T6 temper), increases strength of 7075 AA to a peak level then decreases, however, resistance to stress-corrosion cracking is decreased. Recent trend shows that the strength can be increased more by applying multi-stage aging process. This research focuses on the effect of multiple aging temperature, time on the mechanical properties of 7075 aluminum alloys. ASTM standard coupons were machined from an as received aluminum plate and applied different combination of RRA age treatment. The initial results on mechanical properties are reported. The maximum tensile strength obtained was over 100 ksi for a double RRA at 200°C for 10 min. The hardness was measured using a micro hardness tester. The Vickers hardness numbers were within the range in literatures.
A Mapping Approach to Achieve Torque Control for Parallel-Actuated Robotic Systems
Authors: Welch Stephen B. , Runyon Christian D. , Beiter Benjamin C. , Herron Connor W. , Kalita Bhaben , Leonessa Alexander
Published: February 2023

In this work, we present an approach for realizing the torque control for a parallel-actuated robotic system by mapping the motion of a linear series elastic actuator (LSEA) to its driven robot joint. In most standard robotic modeling and control strategies, a robot is assumed to be actuated by torques applied directly at each joint and constructed as an open kinematic chain. However, the use of non-direct-drive actuators can violate these assumptions, causing additional challenges for the modelling and control of the robot. On our humanoid robot we use standard high level controllers to command desired joint positions and torques in order to generate desired behaviors. However, the humanoid robot is actually actuated by LSEAs, which are defined by actuator length and force. Overcoming this difference requires a method of mapping the motion and effort of an LSEA onto the corresponding joint of a robot. Our mapping approach allows for the conversion of generic desired joint position and torque trajectories consistent with standard controllers into actuator length and force trajectories that can be implemented on an LSEA-actuated robot. We present a two-stage methodology to achieve low-level torque control on our humanoid robot: a validation of the force-torque mapping in simulation, and a force controller implementation for tracking these resulting torque trajectories on a sample simulation of a single robot joint.
Development of a Bio-Inspired Hopping Leg for Lunar Exploration Rover
Authors: Nguyen Mary , Salai Elizabeth , Smith Andrew , Barth Andrew , Dong Janet , Ma Ou
Published: February 2023

The goal of this project is to develop and build a jumping robotic leg to be mounted in a rover for lunar terrain exploration. As we may know that most rovers are using wheels for locomotion, the purpose of replacing the wheels with a jumping robotic leg in this project is to enhance the ability of rovers to travel further distances in a shorter time. The improved speed and distance will make lunar missions more efficient on resources and time. The leg design also helps prevent a rover from getting stuck on the exploration due to geographic obstacles such as mountains, canyons, and other miscellaneous terrains. While this idea is not new, this project attempted to create a unique design using the biomechanics of a kangaroo leg to improve jump capabilities such as height and speed. It is expected that a kangaroo-inspired rover model offers a faster speed and better locomotive capacity in the low gravitational environment and allows the rover to navigate the rough lunar terrain more efficiently in comparison to a wheeled rover.

Three student teams have been working on this project in different academic years. This year’s team focuses on improving jumping height through energy conservation and reduction of weight. The new three-link leg spring mechanism model is designed, built, and tested. The hop is generated by an actuation system that includes three springs and a pull cable. In the design phase, a CAD model was created, and the jumping leg’s static analysis and dynamic simulation were conducted. The jumping heights were calculated and compared with theoretical calculation and simulation. The conservation of energy law was applied to solve the jump height for the theoretical calculation. In the dynamic simulation, the jump height was measured and recorded by adjusting several leg parameters. The jump heights from the calculation and dynamic simulation were compared. The optimum design of the leg, therefore, was determined to achieve the best jumping height.

This paper will discuss the process of this year’s senior team to develop this bio-inspired hopping rover for lunar exploration. The leg prototype was built and made of ABS plastic, and it stands 50 cm high with a weight of 1.56 kg. A testing rig was also developed to measure the leg’s jumping height. This bio-inspired rover could pave the way for improved mobility in unknown, rugged terrains and low gravity environments by overcoming the limitations of the wheeled rovers altogether. This model could lead to the pioneering of using the flexibility of locomotion and miniaturization for lunar exploration.
Extended Analysis of Micro Fin Array Configurations for Single- and Two-Phase Flow
Authors: Frear Colton , Carbajal Gerardo , Romero-Ramirez Edwar
Published: February 2023

An experimental study was conducted to compare heat transfer performance between three micro fin array configurations for transient and steady periodic operation. The study evaluates the time a microchannel takes to reach steady-state conditions for a given flow rate and heat input. It is crucial to investigate the response of the thermal device to overcome a sudden overheating. The experiment aims to analyze the effects of flow boiling in microchannels for extended periods. The study focuses on three novel microchannel cooling devices with different micro fin array configurations. The first design consists of an array of parallel straight fins. The second design resembles the first with the addition of diagonal cuts separating the channel into segments. The third and final design adds another set of diagonal cuts in the opposite direction, creating a diamond lattice of micro fins. It is believed that adding flow-disrupting geometries such as those found in designs 2 and 3 will be beneficial for both single and two-phase flow by improving flow mixing and reducing flow instability, respectively. The experimental results of each fin configuration were compared against a smooth plate (dummy channel) used as a reference. Each device was tested at flow rate of 0.1 to 0.5 ml/min at different heat inputs up to 500W. Temperature and pressure sensors located at the inlet and outlet of the channel measured and gathered fluid data every second for 1800 seconds. The surface temperature near the center of the channel was also collected every second. Once the system achieved steady-state conditions, the surface temperatures at the inlet and outlet of the plate were gathered to ensure correct readings. For this experiment, distilled water is the selected working fluid. Previous experimental studies have shown that adding turbulence caused by cut segments, like those in designs 2 and 3, may significantly improve the heat transfer effectiveness for flow boiling. The experimental results revealed a heat transfer enhancement during flow boiling for designs 2 and 3. Furthermore, for single-phase flow at low heat inputs, the straight parallel micro fins array exerted the highest pressure drop. The pressure drops for designs 2 and 3 were similar during flow boiling. The present study included the straight fin array design to a variable flow rate and increment heat input every 300 seconds. It was found that while the surface temperature data can easily be used as a reference to determine the onset of flow boiling, it cannot be used to detect flow instability effectively. Conversely, the pressure drop across the device provides valuable data for determining the onset of flow instability but is not very effective when used to assess flow boiling. As a result, a composite plot overlaying the surface temperature and pressure drop of the device over time is a great way to determine the onset of each phenomenon simultaneously.
A Microrobot With an Attached Micro-Force Sensor for Natural Orifice Access to the Bladder Interior Wall
Authors: Adejokun Samson A. , Kumat Shashank S. , Shiakolas Panos S.
Published: February 2023

In this work, we present the conceptual design of a 3.5mm outside diameter cable-driven hyper-redundant robotic manipulator with an attached micro-force sensor at the tip for application in transurethral palpation of any targeted area of the bladder interior wall tissue. The stain-gauge based micro-force sensor is designed using finite element analysis (safety factor > 3.5 and load capacity of 0.8N) and subsequently prototyped using additive manufacturing. Sensor components were prototyped using additive and traditional manufacturing, assembled and characterized using a data acquisition environment. The performance of the finite element and prototyped sensor was almost identical. The characterized sensor was used to evaluate tissue properties. The concept of a hyper-redundant 10-joint 6-DOF manipulator comprising of a 5-DOF rigid and a 5-DOF continuum segment is presented along with the forward and inverse kinematics analyses. The inverse kinematics is performed using a Jacobian based formulation to limit the possibilities of singularities. Studies employing the proposed inverse kinematics analysis demonstrated the ability of the manipulator to engage with any area in the bladder and especially the difficult to reach trigone area while attaining a normal pose at the point of contact. A normal pose is required for properly interrogating the tissue with the uniaxial force sensor. The proposed manipulator and force sensor system as presented suggest a probable solution for quantitatively evaluating localized biomechanical properties of the bladder interior wall tissue as a means towards improving treatment and providing better patient care. An initial limited functionality prototype demonstrates capabilities of the proposed concept and provides confidence for further research to fully realize the proposed concept.
Stereolithography Printing and Sintering of Silicon Carbide (SiC) Ceramics via Oxidation-Bonding
Authors: Kakanuru Padmalatha , Pochiraju Kishore
Published: February 2023

Additive manufacturing has given a way to manufacture complex-shaped ceramic parts, which is impossible with conventional manufacturing methods. This paper demonstrated stereolithography printing and sintering of Silicon Carbide (SiC) ceramics via oxidation-bonding. The commercially available SiC powder and the photopolymer resins were utilized for stereolithography printing. Experiments were designed to study the effect of printing process parameters with the increase in SiC powder loading for the photopolymer slurry. It was observed that the curing time increased drastically with SiC powder loading. The SiC green parts were sintered at 1200°C in the air. The SEM-EDS analysis of sintered parts showed evidence of bonding the SiC particles via oxidation. This study paves the way for additive manufacturing of high-density and high-strength SiC/Silica composites.
Performance Enhancement of Two Stages EHD Gas Pump in a Rectangular Channel With Uneven Voltages
Authors: Monayem H. Mazumder A. K. M.
Published: February 2023

In this study, performance enhancement of a two stage electrohydrodynamic (EHD) gas pump in a rectangular channel has been evaluated by experimental measurement and numerical simulations. This study is implemented by a two stage EHD gas pump with uneven voltages for 8 emitting electrodes configuration to seek the relation between the number of stages and applied voltages. The EHD pump is evaluated for a combination of three different operating voltages (20 kV, 24 kV, and 28 kV) for further enhancement in its performance. To achieve the maximum enhancement, the emitting electrodes of the EHD gas pump are flush mounted on the channel walls so that the corona wind produced directly disturbs the boundary layer thickness and improves gas pumping. Velocities are measured at three cross-sections along the tube length and then integrated to obtain the volume flow rate. The numerical results enable vivid flow visualizations inside the channel, providing a great understanding of the development of the flow. The two stages EHD gas pump, which can be produced and sustained air flows with a maximum volume flow rate is considered more efficient when it is operated with uneven applied voltages. The results show that EHD technique has a great potential for many engineering applications.
Additive Manufacturing With Ceramic Slurries
Authors: Nowicki Margaret , Sheward Sara , Zuchowski Lane , Addeo Seth , States Owen , Omolade Oreofeoluwa , Andreen Steven , Ku Nicholas , Vargas-Gonzalez Lionel , Bennett Jennifer
Published: February 2023

Additive manufacturing (AM) is a growing field in which products are created through the addition of materials in a layer-by-layer fashion. Ceramics are typically manufactured using powder compaction and sintering. Ceramic AM is typically executed using Selective Lase Sintering (SLS) techniques to fuse powders using a laser. As with many AM techniques this process allows for the inclusion of unique and complex geometries but does not easily allow for gradient or composite material features. Conclusions from previous investigations indicate chaotic mixing, achieved through integrating a disrupted nubbed section on a traditional screw auger, was more effective for achieving composite homogeneity. However, channel depth results conflicted upon integration of nubbed sections: the existing simulation does not accurately match this inconsistency in the test data. Current work strives to close the gap between test data and simulation, and specifically match this inconsistency between the effect of channel depth and nubbed sections independently, and when combined. The goal is to seamlessly transition between mixtures while minimizing or eliminating waste. To achieve this, it will be necessary to not only understand how print head volume and geometries impact transport, but also determine the impact of gcode on improving transition speed while minimizing material waste.
A Novel Fuzzy-BELBIC Structure for the Adaptive Control of Satellite Attitude
Authors: Safari Kosar , Imani Farhad
Published: February 2023

The performance of the satellite not only relies on environmental factors but also is impacted by internal disturbances. The influential factors complicate the design of accurate controllers for attitude adjustments. The proposed research addresses this control problem by introducing a Brain Emotional Learning Based Intelligent Controller (BELBIC) tuned by a fuzzy inference system. Here, the learning weights and the gain inputs of the BELBIC are adjusted using a fuzzy inference system. In contrast, the initial parameters of the fuzzy inference system are adapted through the whale optimization algorithm. We validate and evaluate the performance of the proposed intelligent controller utilizing simulation studies. The results demonstrate the applicability and satisfactory performance of the proposed controller compared to the PID-BELBIC.
A Data Driven Analysis on the Energy Performance and Efficiency of Water Treatment Plants
Authors: Callinan Alex , Najafi Hamidreza , Fabregas Aldo , Nguyen Troy
Published: February 2023

Water treatment plants are responsible for over 30 terawatt-hours per year of electricity consumption in the United States with an annual cost of nearly $2 billion [1]. Understanding the energy consumption in water treatment plants as well as the potential energy efficiency measures (EEMs) for these facilities can help the municipalities to prioritize the relevant energy efficiency projects based on their payback period and potential impact on their energy bill. In the present paper, the energy performance data for 192 water treatment plants is obtained from the U.S. Department of Energy Industrial Assessment Center (IAC) database. Energy audits were performed in these 192 sites between 2009 and 2022. The database includes the approximate location, square footage, annual energy use, annual plant production, identified EEMs, and their associated energy/cost savings as well as estimated payback period. The annual energy consumed per unit of production (EUP) and per unit of plant area (EUI) are calculated. The mean EUI and EUP for all the plants are found as 267.32 kBTU/ft2/Year and 265.97 kBTU/Thousand Gallons/Year, respectively. Also, the median EUI and EUP are evaluated as 42.4776 kBTU/ft2/Year and 8.203 kBTU/Thousand Gallons/Year, respectively. The analysis is also extended to understand the most promising EEMs for water treatment plants. An artificial neural network (ANN) is then developed to facilitate energy forecasting of water treatment plants using basic inputs including plant area and annual production. The outputs include estimated annual energy consumption and estimated potential savings that can be identified through conducting an energy audit. The training, testing and validation was satisfactory, but expected to much improve in the future with the addition of more assessment data to the IAC database. The ANN model will be the core of a basic energy analysis tool that can help the municipalities to easily evaluate the performance of their water treatment plants and estimate the potential savings that may be achieved as the result of performing an energy audit.
Microscopic Optical Acoustic Sensors for Intracranial Measurements
Authors: Maupin David B. , Dumm Christopher M. , Klinzing George E. , Balaban Carey D. , Vipperman Jeffrey S.
Published: February 2023

Optical acoustic sensors provide a potential means for making accurate intracranial pressure measurements. Complex cranial geometries consisting of bone, tissue, and fluid filled spaces pose problematic conditions for the use of conventional acoustic sensors. This research investigates the potential limitations of previously devised optical acoustic sensors in addition to introducing a novel procedure utilizing micro-scale additive manufacturing to fabricate such sensors with a bandwidth on the order of 20kHz to 200kHz. The significance of individual parameters describing the sensor geometry are discussed as a basis for developing sensors with desired characteristics. Results are obtained through finite element modeling comparing mechanical sensitivities and frequency response arising from diaphragm geometric design and optical fiber positioning within a sensor body. Fabrication techniques and sensor performance are reported.
A Proof-of-Concept Study of a Magnetorheological Micropump
Authors: Cesmeci Sevki , Hassan Rubayet , Thompson Mark
Published: February 2023

In this paper, we studied a flap valve micro-fluidic pump that relies on an electromagnetic actuation mechanism. The upper wall pump chamber is made of a smart material called magnetorheological elastomer (MRE). Under a magnetic field, the upper wall contracts, and the amount of contraction depends on the intensity of the applied magnetic field, which can be controlled via electromagnets. Moreover, flap valves mounted inside this micropump can convey fluids unidirectionally. A Finite Element Analysis (FEA)/Computational Fluid Dynamics (CFD)-based approach was embraced for the design of the device due to the coupled electromagnetic-fluid-structural interactions in the device. Simulations were carried out in COMSOL Multiphysics software. The performance characteristics of the pump were presented and discussed. In addition, a parametric study was conducted to see the effects of important design parameters on the net pumped volume, results of which were also presented and discussed. After the simulation studies, a working prototype pump with a 10.22 × 7.67 × 51.11 mm (W × H × L) was 3D printed. The experimental plan for the working prototype was discussed for further studies. The presented study lays the foundation for future studies where the pump size will be reduced to under 1 mm. The proposed micropump could potentially be used in a broad range of applications, such as an insulin dosing system for Type 1 Diabetic patients, artificial organs to transport blood, organ-on-chip applications, and so on.
Fume Flow Analysis Generated From Landfill Fire, A Case Study
Authors: González Vivian , Esquivel Liz , Espínola Elías , García Abdías , Burgos Víctor , Coronel Fabio , Gómez Francisco , Cañete Pedro , Gusto Luis , Vázquez Juan , González Diego , Villalba Rossana , Kurita Jorge
Published: February 2023

Toxic gasses generated as a result of landfill fire are a big concern to human health, especially in heavily populated urban areas. Such a situation occurred on September 25, 2020, at the country’s main landfill situated in Asuncion city, the most populated urban area in Paraguay.

This is a recurrent situation, two days later; another fire started at the same landfill. It took 12 hours to control the fire. This event generated a plume of toxic smoke that spread through the urban area. This caused severe respiratory problems to the citizens living in the surrounding buildings.

This work is a case study on the analysis of the smoke plume spreading from this landfill in an eventual fire in different wind directions. The main goal was to conduct computational fluid dynamics CFD simulation to be able to map the risk zone on this surrounding urban area. In order to validate this simulation, it was important to replicate this toxic cloud flow by conducting a computational fluid dynamics CFD simulation and comparing this result with actual data. For this purpose, a satellite image taken on the September 25 of the year 2020 fire event was utilized. A good agreement was observed in this comparison. This validated the boundary conditions of this computational tool. A mesh sensitivity analysis was also carried out to ensure a reliable result was obtained.

The city hall as well as the fire departments from the city of Asuncion are now using this map as a guide to better prepare to deal with this toxic smoke by quickly evacuating or notifying residents in the risk zones. The national secretary of emergency is also provided with this map.

Future work includes the analysis of not only other landfills but also warehouse or electric power substations where toxic fuel, such as askarel is present in a latent mode. A recent fire at community markets is also on the list of the potential smoke sources to be analyzed. This undergraduate student research paper is a work in progress. More data is being analyzed. The usefulness and practical use of this kind of computational tool are getting the interest of local authorities.

This work helps to promote students’ motivation in the field of fluid dynamics. The impact on STEM education was noted in this case study. It is planned to compare other software and schemes to better understand computational tools. Finally, a result comparison between cases is expected to be presented.
Assessment of Unilateral Transtibial Amputee Gait Deviations Through Instrumented Gait Analysis: A Review
Authors: Moreno Daniel , Rendon-Velez Elizabeth , Valencia-Legarda Fanny
Published: February 2023

The detection of gait abnormalities is a topic that has been of great interest in recent years. However, most of the reported literature has focused on healthy subjects or subjects with various pathologies. Specifically, the detection of abnormal gait patterns in lower limb amputees is a field that has not yet been widely explored. To develop a system that is capable of detecting these gait abnormalities, each of these abnormal patterns needs to be characterized. It is necessary to determine which are the most relevant features in each of these patterns.To the author’s knowledge, few abnormal gait patterns of lower limb amputees have been characterized and those reported in the literature focus on gait abnormalities in people with transfemoral amputation and not with transtibial amputation. For this reason, the objective of this article is to review the existing literature on gait deviations that were measured using instrumented gait analysis methods in order to establish which variables/features best characterize or represent the different gait patterns of transtibial amputees. A search in biomedical databases was carried out, after reviewing the literature and removing articles that did not meet the inclusion criteria, 37 articles remained. Variables that authors found of significance relative to specific gait patterns were extracted. These variables can be kinematic, kinetic, spatio-temporal, or physiological variables. In the literature found, the experiments were performed on flat surfaces, stairs, and destabilizing surfaces. Flat surfaces were the most prevalent surface used in literature. Multiple authors reported that the energy expenditure of transtibial amputees was the same as un-amputated controls. Transtibial amputee gait should be considered asymmetrical, many authors have found that persons with kinematic variables in acceptable ranges show compensatory patterns in kinematic or physiological variables. This behavior shows that to have a normal ambulation amputees generate asymmetrical loads which can lead to osteoarthritis or lower back pain. The reviewed literature provides characteristics about gait deviations of healthy transtibial amputees in different walking conditions. Additional research exploring other walking conditions or gait patterns of individuals without rehabilitation is required.
Energy and Consumption Fuel Study for a Mobile Air Conditioning System Using Ejector and R445A As a Replacement Alternative for R134a
Authors: Méndez Méndez Dario , Pérez García Vicente , Solorio Alvarado Angel Isaac , Belman Flores Juan Manuel , Ramírez Minguela José de Jesús
Published: February 2023

Vapor compression refrigeration systems (VCR) continue to be the most widely used type of air conditioning system for automobiles, however, they represent high energy consumption and, due to the use of R134a as a refrigerant fluid, they induce a significant environmental impact. Although investigations have increased over the last three decades, alternative automotive air conditioning systems (MACs) are not yet fully developed. Among these opportunities is the replacement of the traditional expansion device used in VCR systems with an ejector which represents low investment costs, lower losses can be achieved during the expansion process, and contribute to the recovery of work in the compressor, this reduction in the work consumption of the MACs produces a lower fuel consumption of the automobile engine.

Due to international regulations regarding the use of refrigerants in automotive air conditioning systems, R134a is a fluid that is already being phased out. Before this action, various options were proposed to match or even exceed the energy performance that R134a offered in MACs. One option that emerges from all of them is R445A, especially since it fully complies with the low GWP limit set in the Normative EU-517/2014. In this work, the basic refrigeration cycle (BRC) is modeled and compared to the refrigeration cycle configuration that uses an ejector (EC). Both models were made using R134a and R445A to compare the influence of the ejector and the low GWP refrigerant. The results show that the EC with R445A reaches increases in COP from 4.1 to 15.6%, compared to that obtained in BRC mode, in addition to reducing power consumption in the compressor from 2.7 to 11.3%. On the other hand, when comparing the COP of the EC with R445A and the BRC using R134a, increases of up to 6.3% are observed in favor of R445A and a power requirement of 14.3% less for R445A compared to R134a. In addition, when evaluating the fuel consumption in volume per unit of time, the EC configuration proposed with R445A reduces the fuel required for this system by up to 40.4% for an evaporating temperature of 5°C, in the same way, for the evaporation conditions of 10 and 15°C, lower fuel requirements were obtained between 18.1 and 35.5%, this compared to the base system, R134a in BRC mode. Finally, by varying the condensing temperature in a range from 35 to 55°C, the fuel requirement increased, however, the EC configuration maintained the trend towards savings in the required fuel flow concerning the BRC.
Numerical Simulation of Three Bubbles Interaction During Flow Boiling of Water in Microchannel
Authors: Rahman Dewan , Mukherjee Abhijit
Published: February 2023

A numerical study has been performed to analyze the wall heat transfer mechanisms during growth of three vapor bubbles inside a microchannel. Flow through microchannel is a subject of extensive study due to its widespread applications in thermal engineering and biological sciences. The microchannel that was used here is 200 μm square cross section and vapor bubbles begins to nucleate at certain distance apart, with liquid coming in through the channel inlet. The complete Navier-Stokes equations along with continuity and energy equations are solved using the SIMPLER method. The liquid vapor interface is captured using the level set technique. The numerical result show that bubbles with the lowest contact angle and high wall superheat temperature resulted in the highest wall heat transfer. Reynolds number don’t have any effect in the microchannel flow boiling. Finally, a comparative study was done between single bubble, two bubbles and three bubbles inside a microchannel. Experiment was done with placing bubbles at different distances, some are close to each other which eventually merged together and some are far enough which never merged. Heat transfer increases when the bubbles do not merge together compared to when they do merge.
Thermoelectric Generation From Exhaust Heat in Electrified Natural Gas Trucks - Part1: Modeling and Analysis on Engine System Efficiency Improvement
Authors: Sok Ratnak , Kusaka Jin , Nakashima Hisaharu , Minagata Hidetaka
Published: February 2023

Thermoelectric generator (TEG) effectiveness in boosting hybridized, compressed natural gas (CNG) 3.0 L engines is demonstrated using a model-based development approach. Measured data from the corrugated fin-type TEG under different gas temperatures and mass flow rates are used for validating the model. The accurate TEG model can reproduce measured pressure loss, heat transfer, and thermal performance characteristics. Next, the model is integrated into the spark ignited CNG engine. Predicted engine performances are well-calibrated with measured data from the twin-turbocharged, mass-production engine used in light-duty delivery trucks. The engine model is validated with measured data for 35 conditions under the JE05 cycle (800–2800 RPM, 2.6–102 kW). The results show that the engine brake thermal efficiency (BTE) is improved by 0.56% using a 7 × 9 TEG module arrangement. A 9 × 10 arrangement can enhance the BTE to 0.8%. Effective electrical power is generated up to 1.168 kW from the TEG, depending on JE05 operating regions, without significant power loss.
Unsupervised Machine Learning Algorithms for Analysis of Low Velocity Impact Damage in Composite Structures From CT Image Data
Authors: Zhupanska Olesya I. , Krokhmal Pavlo A.
Published: February 2023

In this work, novel unsupervised machine learning (ML) algorithms for automatic image segmentation for the analysis of the micro-CT data for impact damage assessment in the composite materials have been developed. The algorithms are based on the statistical distances including the Kullback-Leibler divergence, the Helling distance, and the Renyi divergence.

The developed algorithms have been applied to the analysis of low velocity impact damage in carbon fiber reinforced polymer (CFRP) composites. The grayscale images from the CT scans of the impacted CFRP specimens have been analyzed to identify and isolate impact damage and optimal statistics-based damage thresholds have been found. The results show that the developed algorithms enable not only an automatic image segmentation, but also deliver statistics-based rigorous damage thresholds.
Design, Fabrication and Testing of a Novel Thermally-Actuated Tesla Valve (TATV): A Hybrid Microvalve
Authors: Lee Jonghyun , Thyagarajan Ashok , Bamido Alaba , Shettigar Nandan , Banerjee Debjyoti
Published: February 2023

Conventional technologies that are deployed in contemporary irrigation systems need improvement, especially for precise metering of water to individual plants. In this study, a novel thermally-actuated hybrid microvalve was designed, fabricated, assembled, and tested using soft lithography-based approaches to develop microfluidic platforms which enable precise delivery of water volumes to individual plant for precision agriculture application (other applications include hydroponics and deep-space missions). The modified design integrates the “normally open and closed” hybrid configurations of Tesla Valves with a thermo-pneumatic actuator microfabricated in-situ - that modulates the diodicity of the microvalve apparatus in the microfluidic chip. Here, diodicity (Di) is defined as the ratio of flow rate in the forward direction to that of the reverse direction (for a constant value of pressure drop that is imposed on a microvalve device). The results from the study successfully demonstrated the operation of an array of Tesla Valves that are normally open in forward direction and marginally closed in reverse direction at room temperature (i.e., with Di > 1, the flow resistance values were different when the inlet and outlet ports were swapped). When the microfluidic chip was heated (at steady state conditions with a nominal temperature of ∼30°C), the diodicity virtually vanished (i.e., Di ≈ 1) resulting in both reverse and forward directions being normally open (or having the same flow resistance - irrespective of the flow direction).
The Impact of the Printed Part Geometry on the Shrinkage and Relative Density in Binder Jetting Additive Manufacturing of Ceramics Powder
Authors: Obeidat Suleiman , Ma Junkun , Himelstein Sophie , Acharya Aniruddha
Published: February 2023

Additive manufacturing has been used extensively for the last decade in making different parts of different complexities. One of the additive manufacturing methods discussed in this work is binder jetting additive manufacturing (BJAM) process where a liquid-based binder is deposited on the powder bed to make the part layer by layer. In this work, ceramics particles are used to investigate the effect of the part geometry on the density and shrinkage of the part made. Three different shapes (spheres, cylinders, and rectangular blocks) of the same size are printed at 100%, 75% core saturation limit at zero second and 10-seconds delay using a binder jetting 3D printer at 0.2 mm layer thickness. The green parts are de-powdered and dried for 6–8 hours using a drying heater at 35° C then de-bound and sintered to improve the strength and the density of the part made. We use ceramics powder of particle size range 50–200 μm to print the parts. It is found that the apparent density of the rectangular block is the highest in all cases except at 100% saturation with 10-seconds delay. The apparent densities of the sphere and the cylinder are very close to each other. Also, the shrinkage percentage for the sphere is the highest then cylinder comes next, and the rectangular block comes last in all cases except when the core saturation is 100% and delay is 0 second where the cylinder shrinkage is higher than that of the sphere. The reason behind this is maybe the difference in the surface area of each part printed. It is noticed also that the relative density obtained is in the range of about 79% to about 85% and the shrinkage percentage is in the range of 36% to 55%.
Characterization of Aluminum and Steel Thin Plates Using Electromagnetic Acoustic Transducers
Authors: Peterson Lukas , Zagrai Andrei
Published: February 2023

Several techniques are currently used for the noncontact thickness mapping of thin-walled structures, which include laser contour mapping and electrical capacitance measurement, but very few methods are available when one side of the structure is not accessible. A popular technique when only one side of the structure is accessible is the use of ultrasonics in either a resonance approach or a through transmission approach. This study will focus on the use of the through transition approach using ultrasonic guided waves transmitted and received by Electro Magnetic Acoustic Transducers (EMATs) in thin aluminum and steel plates. To validate results a Fourier analysis was preformed verifying thickness resonant frequencies predicted by dispersion curves. Because the medium is a thin plate, symmetric and antisymmetric Lamb waves as well as shear horizontal waves are the candidates for analysis in the thickness measurements. The EMATs are used for both transmission and reception of guided waves of different types. The major challenge with this type of transducers is power requirement which is achieved with the high-power ultrasonic pulse generator and a transformer circuit. The temporal difference in transmitted and received signals of various wave types were used to calculate the average ultrasonic speed of propagation in several regions of the plates. The speed of propagation is a function of plate thickness as well as several physical parameters, allowing an average thickness to be calculated over the path of the guided waves. These values can then used to produce a map of the thickness over the entire structure as a precursor to the identification and localization of damage in thin-walled structures such as large scratches, corrosion pitting, and holes. If further quantization of plate thickness is desirable, the guided waves can be explored in several orientations allowing for a finer map of sound speeds over the plate to be created. Guided wave thickness calculations where preformed on both steel and aluminum plates proving the validity of the approach to both ferrous and non-ferrous metals while providing accuracy and precision values for the methodology and hardware used. This is in preparation for future work detecting both uniform and pitting type corrosion using similar techniques.
Numerical Study on Diffusion Law and Risk Assessment of Indoor Hydrogen Leakage
Authors: Shao Yanbo , Cao Xuewen , Li Hao , Xia Wenzhu , Zhang Weibing , Zhang Zhigui , Nan Zilong , Bian Jiang
Published: February 2023

Energy shortages and environment pollution are among the most important problems all over the world. As a clean and renewable energy carrier, hydrogen is expected to be one of the most promising alternative solutions to the energy and environmental problems in the near future. However, the safety issues in hydrogen production, transport and storage have to be thoroughly addressed before commercialization of hydrogen energy to give authorities confidence and to eliminate the public fear of using hydrogen. Accurate knowledge of the dispersion characteristics of unintended hydrogen releases in the atmosphere is essential to developing good standards and codes for hydrogen safety. This paper presents a numerical study on the indoor hydrogen leakage risk assessment and numerical simulation. The physical and mathematical model of hydrogen leakage and diffusion process are established. Based on computational fluid dynamics, the numerical simulation of hydrogen leakage process is studied. The effects of leakage source height and direction on hydrogen leakage and diffusion in indoor space are analyzed. The results show that the hydrogen leakage in the laboratory space is initially diffused by jet. With the development of time, the leaked hydrogen with different height and direction of leakage source forms different forms of vortex in the space, which affects the speed and amount of hydrogen accumulation in the space. When the hydrogen leakage source is low, the leakage direction is downward and back to the vent, the safety risk is greater.
Modeling and Control of a Novel Thermoelectric Cooling System
Authors: Bardarson Jeremy , Clement Jack , Dahiya Sachin , Gartia Manas Ranjan , Barbalata Corina
Published: February 2023

This paper presents the modeling and control of a novel thermometric cooling system that can be used for head trauma injuries. The proposed device enables fluid circulation and accurate control of the fluid temperature. The overall system consists of a micro heat exchanger, a Peltier unit, a pump, appropriate tubing, a thermocouple, and an electronic control system. This paper is focused on the design of the pumping system, the thermodynamic modeling, and the development of the electronic control system. Experimental results with the proposed device show the capabilities of the system to reach various temperatures and maintain them as much as needed.