bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance Study of an Electric Vehicle “Eolo” With a Mounted Aeolian Generator
Authors: Garcia Arturo , Reyes J. Sergio , Wang Xiuling , Roldan Javier , Olaya Mauricio
Published: January 2022

The issue of global warming and greenhouse gasses is being addressed in some ways with the production of hybrid vehicles, including the idea of the Colombian Wind Powered Electrical Vehicle (EV), Eolo. This paper will give a brief review over how the engineers behind this pioneering project created the hybrid Electric-Aeolian car. The primary focus was on verifying experimental results with simulations and gaining an in-depth understanding of its performance characteristics. Computational Fluid Dynamics (CFD) software of ANSYS, Fluent was used to model the vehicle traveling along the road at various wind machine configurations. The data gathered from the simulations along with empirical data collected by Eolo Company about their turbine would be used to calculate the aerodynamic coefficient, among other relevant engineering parameters. These values will be compared against the experimental values and evaluated as to any discrepancies and validation of the experimental results.
A Long-Term Assessment of the Impact of Natural Gas Production in North Texas Influencing Urban and Regional Air Quality
Authors: John Kuruvilla , Lim Guo Quan , Kanayankottupoyil Jithin
Published: January 2022

Unconventional energy production from the Barnett Shale Play in North Texas has grown and matured over the past two decades. The Dallas-Fort Worth (DFW) metroplex area is adjacent to this large energy production region. Ambient air quality data from three North Texas sites (Dallas Hinton (DAL), Fort Worth Northwest (FWNW), and Denton Airport South (DEN)) was acquired from Texas Commission on Environmental Quality (TCEQ). During 2000–2020, total nonmethane organic compound (TNMOC) concentrations decreased at DAL and FWNW by about −1.62%/year and −0.63%/year, respectively, while an increase of +9.97%/year was noted at DEN. An increase in the observed ethane concentrations and a decrease in acetylene concentrations were observed at all three sites. Ethane is a key ingredient in natural gas. While acetylene, typically associated with traffic emissions along with the concentrations of oxides of nitrogen (NOx) showed a year-to-year decline at all sites. The ozone formation potential (OFP) was calculated using measured TNMOC concentrations. Highly reactive volatile organic compounds (VOC) associated with urban sources (ethylene, propylene, and m/p-xylene) affected the calculated OFP in DAL and FWNW, while slow-reacting n-alkanes linked to natural gas operations (ethane, propane, and butane) influenced the OFP in DEN.
Effect of Pore Size of Copper Foam on Thermal Performance of Bio-Based PCM/Copper Foam Composite
Authors: Sheikh Yahya A. , Gadalla Mohamed , Azmeer Ahmed
Published: January 2022

Phase Change Materials (PCMs) are the materials that have the distinct ability to absorb or release significant quantities of thermal energy at a nearly constant temperature. As a result, PCMs present themselves as an appropriate material candidate when thermal management systems are considered. Unfortunately, bio-based PCMs suffer from one major drawback that is low thermal conductivity. As a result, bio-based PCMs exhibit an inefficient absorption ability of heat and a low heat utilization efficiency for the cooling application. This paper experimentally investigates the effect of pore size on the thermal performance of bio-based PCM/copper foam composite at a fixed porosity. The three copper foams that are used in the current study have the same dimensions of 106 × 96 × 3 mm, and the pore sizes of them are 20, 35, and 60 pores per inch (PPI). The results indicated that the use of Copper foam to augment the thermal performance of bio-based PCM heat sinks is justified due to lower final temperatures in the temperate profiles and longer time taken to reach critical temperatures for PCM-Copper composite samples when compared to pure PCM. Furthermore, amongst the three pore size configurations investigated, PCM-CF 35 PPI appeared to exhibit the most favorable thermal performance when compared to its 20 PPI, and 60 PPI counterparts.
A Projection-Based Derivation of the Equations of Motion for the Moving Frame Method for Multi-Body Dynamics
Authors: Luchtenburg Dirk M. , Shah Mili , Impelluso Thomas J. , Ravneberg Rykkje Thorstein
Published: January 2022

The moving frame method for multi-body dynamics, established by Murakami in [10] and [11], embodies a consistent notation and mathematical framework that simplifies the derivation of equations of motion of complex systems. The derivation of the equations of motion follows Hamilton’s principle and requires the calculation of virtual angular velocities and the corresponding virtual rotational displacements. The goal of this paper is to present a projection-based approach, which only requires knowledge of Euler’s first and second law, that results in the same equation of motion. The constraints need not satisfy d’Alembert’s principle and the projection is based on a generalization of Gauss’ principle of least constraint [14]. One advantage of the proposed method is that it avoids variational principles and therefore is more accessible to undergraduate students. In addition, the final form of the equation of motion is more easily understood. We motivate our approach using the example of the simple pendulum, derive the main result, and apply the methodology for derivation of the equations of motion for a modified Chaplygin sleigh and a rotary pendulum.
Theoretical Analysis of a Single-Stage Gas-Fired Ejector Heat Pump Water Heater
Authors: Spitzenberger Jeremy , Wang Pengtao , Ismael Laith , Ma Hongbin , Abuheiba Ahmad , Nawaz Kashif
Published: January 2022

Ejector driven systems have the ability to operate at high efficiencies, utilizing recycled thermal energy as a power source. For a typical ejector heat pump system, the increase of the condenser temperature reduces the coefficient of performance (COP). In addition, if the condenser temperature is higher than the critical temperature, the ejector may not function. In this situation, the condenser temperature must be reduced, and an additional heater will be utilized to heat the production water from the condenser temperature to the desired temperature. In this investigation, a single-stage gas-fired ejector heat pump (EHP) is investigated and thermodynamically modeled in order to optimize the system COP for the purpose of heating water by utilizing the thermal energy from the ambient air. The effects of the high-temperature evaporator (HTE) and low-temperature evaporator (LTE) temperatures on the ejector critical back pressure and the EHP system performance are examined for a HTE temperature range of 120–180 °C and LTE temperatures of 15.5, 17.5, and 19.5 °C. Results show that an optimized COP of the EHP system exists which depends on HTE and LTE temperatures, primary nozzle throat diameters. In addition, it is found that the EHP COP is independent of the ejector COP. From this investigation a maximum EHP COP of 1.31 is able to be achieved for a HTE temperature of 160 °C and a LTE temperature of 19.5 °C with a total heat capacity of 15.98 kW.
Climatology and Trends of Heat Index, Human Discomfort Index and Energy per Capita for CONUS and Meso-America
Authors: Faiz Qurat , González Jorge E.
Published: January 2022

Air temperature and humidity both affect the human comfort and health in warm and humid climates. An effective way to measure the overall effect of temperature and humidity on human comfort (or discomfort) is using the term referred as Heat Index (HI). The HI is a measure of how people “feel” when exposed to warm and humid environments, making it an effective variable to explain the effects of heat in people, to alert of heat advisories, and to reform public health policies. Evidently, heat index is a changing variable with geography and with climate seasons and change. This research aims to investigate the spatial and temporal trends of Heat Index and energy per capita (EPC) in the Continental US (CONUS) and the Meso-America (the Caribbean, and Northern Regions of South America).

In order to investigate the spatial and temporal distribution and trends of heat index and EPC in different regions of the CONUS and the Meso-America, hourly air temperature and relative humidity datasets were collected from two sources; The National Center for Atmospheric Research (NCEP) North American Regional Reanalysis (NARR) and weather stations for the period of thirty years: 1990 to 2019. The Algorithm used in our study to determine the HI is similar to the one used by the National Weather Service (NWS) measuring air temperature in degrees Fahrenheit (T) and relative humidity in percent (RH). Our analysis of the HI and EPC climatology for the summer season for Southeast US and the Meso-America exhibits the largest values in Southeast US, followed by the Greater Antilles, and then the Lesser Antilles. HI is used herein to quantify the impacts of these warming trends on EPC. Results of the analysis depict a Southern Greater Antilles with a positive EPC rate of 2 kWh per year for summer season. These spatial trends using NARR data were found to correlate very well with selected weather stations and were also determined to be statistically significant. The state level trends of electricity consumption per person per year (Figure 5.) suggests, in general, a correlation between trends on total energy consumption per capita and increasing maximum heat index. Therefore, increased energy production and improved energy infrastructure will be required to maintain ideal indoor building conditions as consequence of a warmer climate.
Computational Fluid Dynamics Modeling and Experimental Testing of Hydraulic Spool Valves
Authors: Janosky Kyle , Younessi Sinaki Maryam , Kashid Bipin
Published: January 2022

To have faster time to market one must reduce the required experiments needed to develop new products. In this paper, hydraulic spool valves were investigated and a comparison of actual experimental data to the results of Fluent simulation was made. This comparison included multiple standard turbulence models in addition to a custom version of GEKO k-omega. Along with turbulence models, different solver options were compared to evaluate their impact on the results. This data will help better correlate future simulations to experimental data, thus utilizing simulation to design and experiment to verify the final solution if required.
Imaging-Based Fatigue Mechanism Investigation of Additively Manufactured Ti-6Al-4V
Authors: Chen Jie , Meng Changyu , Liu Yongming
Published: January 2022

The fatigue characterization of additively manufactured Ti-6Al-4V plays a vital role in ensuring the structural safety. This study focuses on image based surface characterization and the fatigue mechanical property investigation of as-built additively manufactured Ti-6Al-4V. Three sets of processing parameters (the absorbed laser power, scan velocity, building orientation) are adopted corresponding to the EOS nominal settings, lack-of-fusion and keyhole regimes. Before the fatigue testing, the specimens are scanned using X-ray micro-computed tomography (microCT) and the complete surface morphology is obtained. During fatigue testing, the specimen is scanned using microCT after certain numbers of loading cycles to capture the fatigue crack initiation locations and trace the crack growth trajectories. After the fatigue testing is completed, the fractured specimen is scanned by both microCT and scanning electron microscope (SEM). Based on the experimental investigation, vertically built specimens have lower average surface roughness than angled specimens along the transverse direction. Along longitudinal direction, the average surface roughness does not very significantly among all specimens. The fatigue crack may initiate from near surface pores or external rough surface. Cracks initiating from different locations at the similar height coalesce while propagating. Fracture surfaces present tortuous or tearing features, which corresponds to shorter and longer fatigue lives under the same fatigue loading, respectively.
Research on Tone Quality for Vehicles Considering the Masking Effect
Authors: Lin Jiewei , Zhang Rui , Zhou Qidi , Zhang Junhong , Lin Gengyi
Published: January 2022

Sound quality (SQ) plays important role in automobile competitiveness, in which the high frequency characteristics of tones are prominent when internal combustion engines are replaced by fuel cells or batteries. Hence, it is of great significance to explore the influence of tones on the SQ of such electric vehicles. At the moment, the prominence of tones is concerned but the influence of tones in different frequency ranges is not comprehensively considered. Meanwhile, there are some researches on the masking effect of background noise, but they are insufficient. To address these issues, the SQs of four types of vehicles (van, SUV, pure electric car, fuel cell heavy truck) are studied. The prominence ratio (PR) is found to be effective in the evaluation of tones SQ. The influence of tones on subjective evaluation is explored from two dimensions of “audible” and “irritable”. The results show that whether tones can be “audible” and “irritable” are related to the masking effect of background noise and the frequency distribution. Meanwhile, the PR limits of tones are obtained in different frequencies under various working conditions and operating modes.
Mass Transport and Thermal Stresses Evaluation of Micro Solid-Oxide Fuel Cells: A Numerical Study
Authors: Osman Sameer , Ahmed Mahmoud
Published: January 2022

Solid-oxide fuel cell (SOFC) are among the highest types of fuel cells in terms of efficiency, reaching as high as 65%. However, poor mechanical robustness and thermal cycling stability are the major disadvantages of these fuel cells due to high thermal stresses between layers. A new concept of a micro-monolithic ceramic cell was previously introduced that had extremely high power-densities (> 10 W/cm3) as well as high mechanical robustness and thermal cycling stability. In this study, a 3D comprehensive theoretical model is presented for ceramic fuel cells, which includes species, charge, momentum, and energy transport. Moreover, the bilinear elastoplastic material model is used to estimate thermal stresses in ceramics at high temperatures. This model is then used to simulate two new geometries for the cell and anode flow channels. Results indicate that circular anode channels are best in terms of thermal stresses, while being inferior in terms of electrochemical performance. A hexagonal cell with trapezoidal flow channels yielded the highest volumetric power density with an increase of 15% compared to the plain circular arrangement. On the other hand, circular sector flow channel increased the power density by only 9%. The increased current of the cell with the circular sectors and trapezoidal sections is due to the more efficient distribution of flow channel area such that the travel path for hydrogen gas is less restricted in terms of diffusion. As for the thermal stress, the newly introduced configurations increased the values of stress by 64% for the circular sector channels, compared to only 16% for the trapezoidal flow channels. This study is meant as an initial step in the optimization process for the microtubular SOFC with high volumetric power density, creating an opportunity for performance enhancement of this type of fuel cell.
An Imperfect Usage-Based Preventive Maintenance Planning Model for Railway Track Superstructures
Authors: Dinmohammadi Fateme , Shafiee Mahmood , Zio Enrico
Published: January 2022

Railway transport is considered one of the most reliable, comfortable and safest modes of travel for both freight and passengers. Rail infrastructure assets (such as tracks, bridges, earthworks, tunnels and drainage systems) must be inspected and maintained on a regular basis in order to ensure that transport services are delivered in compliance with contractual and legal obligations. The maintenance of railway track structures is preventive in nature and includes the repair or replacement of certain components at pre-determined time intervals (in terms of years of operation) and/or usage rates (in terms of gross tonnage). Maintenance actions such as grinding and stone-blowing either restore the track profile to its original condition, i.e., “as good as new (AGAN)”, leave the track in almost the same condition as it was in prior to the inspection, i.e., “as bad as old (ABAO)”, or restore the track condition to a state somewhere between AGAN and ABAO, i.e., the so-called imperfect maintenance. The effect of an imperfect maintenance is often characterized by two classes of models, namely, failure-intensity reduction and age-reduction. However, the impact of imperfect repair on assets’ usage has not yet been addressed in the literature. In this paper, a usage-based imperfect preventive maintenance (PM) planning model is proposed for railway track superstructures, where the effect of an imperfect maintenance is described by a reduced amount of total accumulated million gross tons (MGT) passed over the rail line. A constrained nonlinear programming model is formulated to optimize the maintenance interval (i.e., usage rate between consecutive PMs) and the degree (quality) of repair actions. The total mean maintenance cost for a Weibull failure distribution model is derived and, then, the conditions required to make PM actions beneficial are discussed. A numerical case example is provided to show the effectiveness of the proposed PM planning method over the track renewal and replacement policy.
Performance Assessment of a Closed Greenhouse in a Hot Arid Australian Climate
Authors: Hegazy Anwar , Subiantoro Alison , Norris Stuart
Published: January 2022

In this paper, we present a validated thermal model of a greenhouse. Then summer climatic data of a location in South of Australia (Port Augusta), known to have dry and hot summer, is used to compare the potential of different cooling technologies in providing cooling to greenhouse indoor air while considering the minimization of water consumption. Several cases are examined and compared to a reference case which is a closed greenhouse without cooling. The operation cases considered for cooling purpose are 1 - Fogging system; 2 - Single pipe Earth-to-Air Heat Exchanger (EAHE); 3 - Multiple pipe EAHE; 4 - combined operation of Fogging system and EAHE. Results indicated that relying on shallow geothermal energy through an Earth-to-Air Heat Exchanger (EAHE) minimized the water consumption of the fogging system reducing it from 11.6 to 4.7 kg/day. Furthermore, the results show that cooling via EAHE is the best strategy in terms of reducing water consumption without significantly affecting the temperature reduction when compared to the water reliant cooling technology fogging system. The combined operation of EAHE and fogging system managed to keep the indoor air condition at the favorable plant cultivation temperature level (20–30°C) and relative humidity (70–80%).
Direct Measurement of Thermal Boundary Resistance Reduction Due to Electron Carriers by Photothermal Radiometery
Authors: Villarreal Ezekiel , Horny Nicolas , Ban Heng
Published: January 2022

A thermal boundary resistance occurs between any two surfaces that are not in perfect contact with each other. It is well predicted that this thermal resistance decreases as heat carriers, typically phonons or electrons, cross the contact surface. While phonon transport and electron transport are well documented in a number of conditions, direct measurement of the electron contribution to thermal boundary resistance across micro layers has not been shown. Understanding the effect of electrons on the heat transfer of thin layer is very important in understanding the thermal behavior of micro- and nano-electronics, which has impact on both the life and the reliability of electronics. This paper presents an experimental test on the heat transfer as electrons cross the boundary of an n-doped Schottky Diode. Photothermal Radiometry (PTR) measurements were then taken to determine the thermal boundary resistance. Measurements were made on the same diode in both the open and closed state. The obtained open and closed fit parameters were then compared with each other to determine the reduction in thermal boundary resistance. It was found that the thermal boundary resistance of the diode in its opened state was 8.4 K m /GW; while the thermal boundary resistance was 6.4 K m /GW when the Schottky diode was closed with current of 100 mA. This represents a reduction in the thermal boundary resistance of approximately 24% for the case where the electrons were crossing the boundary. This result confirms experimentally that the electron heat transport effectively reduces the thermal resistance across boundaries.
Thermal Performance of a Packed Bed Latent Heat Thermal Energy Storage With Pure Silicon as PCM
Authors: Saha Sumit , Md. Ruslan Abu Raj , Morshed A. K. M. M. , Paul Titan C.
Published: January 2022

In this paper, effect of mass flow rate and inlet temperature on the thermal performance of a packed bed latent heat thermal energy storage has been numerically investigated. As the Heat Transfer Fluid (HTF), hot air is selected. Pure silicon is chosen as the PCM (Phase Change Material). The thermal performance has been evaluated on the basis of the following parameters: total heat transferred (Qcharging), TES charging rate (p), TES density (q), TES rate density (w). The values of these parameters have been calculated and compared for four different mass flow rates (0.08 Kg/s, 0.1 Kg/s, 0.12 Kg/s, 0.15 Kg/s) and four different inlet temperatures (1800 K, 1900 K, 2000 K, 2100 K) of the HTF for a charging period of 500 s. The simulations reveal a 0.54% increase per 1% increase in HTF mass flow rate and 15.6% increase per 1% increase in HTF inlet temperature in values of all the parameters after the charging period. A conclusion can be drawn that the HTF inlet temperature has more impact on the performance of packed bed latent heat thermal energy storage than HTF mass flow rate.
Thermal Circuit Analysis of Droplet Evaporation on Hot Microstructured Superhydrophobic Surfaces
Authors: Huang Wenge , He Xukun , Cheng Jiangtao
Published: January 2022

In this paper, the evaporation dynamics of solitary water droplet dwelling on the hot micro-structured superhydrophobic surfaces is experimentally and theoretically investigated. For the first time, two distinguished components of heat and mass transfer, i.e., from the droplet cap and the base surface, during the droplet evaporation are systematically studied. Considering all the thermal resistances from the heated substrate to the droplet cap surface, a comprehensive thermal circuit model is developed to analyze the effects of micropillars and substrate temperature on the sessile droplet evaporation. As substrate temperature increases, a more apparent temperature mismatch between droplet cap surface and heated substrate is experimentally observed, which could be explained by the increasing droplet cap surface evaporation rate and its evaporative cooling effect. Moreover, the increasing temperature of droplet cap during the evaporation could be successfully predicted by our model, indicating the component of evaporation ratio from the droplet base surface (φ) decreases. This work could advance our understanding of droplet evaporation on heated superhydrophobic surfaces and further provide us a new tool to accurately predict droplet temperature and evaporation rate during the evaporation process.
Cutting Fluid Application for Bandsawing: A Sustainable Solution for Cutting Solids
Authors: Rakurty C. S. , Rangasamy Nithin
Published: January 2022

The band saw cutting is one of the many cutting/machining operations that can benefit from cutting conditions and cutting fluid optimization. Optimizing cutting speed, feed rate, and cutting fluid application based on the cut material can increase the blade’s life. Most of the academic and industry work focuses on optimizing the cutting tool design and cutting conditions such as band saw blade speed and feed rate. Most of the band sawing industry uses flood cutting fluid to reduce the cutting temperatures, remove chips, and (in some cases) act as a lubricant. There is a lack of comprehensive understanding of the role of cutting fluid, and its method of application in the band saw cutting. In this paper, cutting fluid application on the cutting performance metrics such as surface roughness, (feed) force, and cutting edge wear (at ten cuts) were studied. The study also focuses on the chip formation and cutting temperatures generated while cutting with and without cutting fluid application. A flood cutting fluid application (recommended for the D2 tool steel), varying amounts, and compositions of the minimum quantity cutting fluid applications were studied along with dry (or no cutting fluid application) cutting. D2 tool steel material was used as workpiece material, and a carbide-tipped band saw blade was used as the cutting tool. In general, the band saw teeth split the kerf to improve the cutting process through reduced cutting temperatures and forces. The cutting conditions influence the chip formation and kerf splitting process. The results show that the minimum quantity cutting fluid applications negatively influenced the cutting performance. They produced the highest feed forces and caused severe tooth damage compared to the other experimental conditions. The results concluded that dry (no cutting fluid application) is recommended for cutting D2 tool steel material. This road map can be used to improve the band saw blade life and improve the cut-surface roughness.
Demand Response Analysis for Different Residential Personas in a Comfort-Driven Behavioral Context
Authors: Olawale Opeoluwa Wonuola , Gilbert Benjamin , Reyna Janet
Published: January 2022

Low demand response (DR) participation and high program drop-out rates continue to impede DR goals that could save up to $13 billion in annual grid expansion and electricity demand costs. Yet, the literature lacks a thorough understanding of how different residential customer segments enrolled in DR programs respond to utility signals in view of occupant comfort considerations. The objective of this study is to gain a clear understanding of the effects of four different customer personas on residential DR. Given current data limitations, this work developed an array of hypothetical personas with varied priorities, activity levels, and comfort thresholds based on demographic variables that have been found in previous studies to influence energy consumption. A BEopt™ DR model for a reference residential single-family building located in Colorado was built to isolate the effect of differences in buildings or climate. The results provide useful evidence on how persona-comfort differences lead to significant deviations in DR goals (especially peak demand reduction), ranging from 0.1% to 20%. This work presents a novel framework representing comfort preferences in DR models. The data generated, albeit synthetic, and the results could inform DR program design considerations of how different people respond to different comfort priorities.
Irradiation and Thermal Post-Processing for Vat-Polymerization Additive Manufacturing: Tensile Properties of Four Formlabs Resins
Authors: Baumgarner Julia , Piovesan Davide
Published: January 2022

With the introduction and recent advances of additive manufacturing there are a number of materials available for creating medical prototypes. Of particular interest are materials used for imitating bone properties for the execution of mock preparatory surgeries. However, when designing a print for a model it is important to understand the mechanical properties of each material. One of the most common methods of 3d printing is stereolithography. In this paper, four Formlabs resins were tested in tensile loading. Clear, Durable, Tough, and High Temperature resins were used for testing. Samples were tested with and without post-processing curing. Curing was performed in a customized curing oven that follows the Formlabs requirements. After testing, mechanical properties were calculated for all sample groups.
Ultrasound Assisted Production of Metal Foam From Polyurethane Precursor
Authors: Zahoor Asima , Mourad Abdel-Hamid I.
Published: January 2022

Metal foam is a novel class of metals that is inspired by naturally occurring, functionally graded, cellular structures like wood and bones. The properties of metal foam are so diverse that they can be tailored to suit the particular need, hence the study of metal foams has become attractive to researchers and efforts are being made to optimize the methodology to develop the metal foam. Most of the production methods cannot be widely utilized because of difficult process control and high production costs. One of the most economical ways to produce metal foam is adopting conventional electro deposition technique. The electro deposition technique starts from first metalizing the non-conducting polymeric foam and then electrically depositing metal onto this metallized precursor foam with open cells and later the precursor is removed by the sintering process. The main hindrance in this process is that foam being multi layered, a uniform deposition of the metal in the inner layers of the foam was not achieved. After sintering it was found that the foam sample turned out hollow at the center, due to lack or very less deposition of the metal. Experiments aiming to overcome this problem of non-uniform deposition of the metal in the inner layers of the precursor were conducted. It was found that mechanical agitation in the form of low frequency ultrasound promoted the uniform electro deposition throughout the metalized multilayered precursor. Finally, desired strength foam was produced.
Parametric Optimization of SMA Torsional Actuators for Aircraft Morphing Applications
Authors: Summers Christopher , Weaver-Rosen Jonathan M. , Karakalas Anargyros A. , Malak Richard J. , Lagoudas Dimitris C.
Published: January 2022

Novel design of more efficient, environmentally friendly, quiet, and cost-effective air transportation could be substantially benefited by introducing highly adaptive, multi-functional systems that are able to mimic the operation of biological systems, like birds. Altering the Outer Mold Line (OML) of an aircraft allows for achieving the optimal response under a wide range of operational conditions. In the framework of the “Adaptive Aerostructures for Revolutionary Civil Supersonic Transportation” project funded by NASA, an articulated panel mechanism controlled by Shape Memory Alloy (SMA) actuators is investigated as a means for reducing the perceived loudness of the sonic boom produced by a commercial aircraft when flying at supersonic speeds. A pair of SMA torque tubes is envisioned to induce the required rotation of the panels in order to achieve the desirable OML shapes. However, design objectives such as minimizing power consumption, mass, and cooling time are often competing and the selection of the optimal dimensions is neither elementary nor straightforward. In the research conducted herein, a case study is defined and realized for the optimal design of the SMA torque tubes as part of a larger morphing structure. In the early stages of design, engineers are often faced with the challenge of making decisions with incomplete information. For example, the designer must know the aerodynamic loads to choose the optimal dimensions, but the aerodynamic loads depend on aircraft dimensions. To enable detailed optimization in the early design stages, parametric optimization can be used to solve for the parameterized Pareto frontier. This parameterized Pareto frontier allows a designer to explore how the traditional Pareto frontier might change as exogenous parameters (the values of which are not yet fully known) change. In this work, the design variables under the control of the engineer are the dimensions of the torque tube, i.e. length, inner diameter, and thickness. The objectives are to minimize cooling time and maximize rigidity. The exogenous parameters outside of the designer’s control include the required actuation stroke and aerodynamic forces. Results show the effects of parameters on the objective tradeoffs and demonstrate how an engineer can choose an optimal solution once the parameter values are known.
Design of a Personalized Bio-Mechanical Knee Orthosis
Authors: Tacescu Alex , Goldfarb Nathaniel , Secino Benjamin , Fischer Gregory S.
Published: January 2022

Exoskeleton joints should be aligned and follow the anatomy of the person to prevent putting additional strain on the ligaments or creating skin complications through rubbing between the patient and the exoskeleton. The human knee is a challenging joint to replicate accurately since its motion is not a simple hinge joint; the knee rotates through its range of motion while the tibia extends relative to the joint center. This paper presents a powered biomechanical-inspired knee joint for an exoskeleton developed to follow the flexion-extension motion. By utilizing previous literature that used Magnetic Resonance Imaging scans to identify the relationship of flexion-extension, the design requirements for the knee mechanism were defined. The flexion-extension motion was used to determine the polynomial-shaped cam mechanism, translating the shank segment as the joint rotates. This knee joint takes advantage of Fused Deposition Modeling 3D printing, allowing the knee to be easily manufactured and customized. Motion capture and finite element analysis are used to validate the motion and mechanical strength. The final biomechanical knee joint is highly customizable and easy to manufacture.
Gait Stability Using Lyapunov Exponents
Authors: Galarza Jose , Caruntu Dumitru I. , Vasquez Simon , Freeman Robert
Published: January 2022

This work deals with the stability of the dynamics of human gait. This is a common exercise. The focus of this investigation is to analyze the knee angle time series and calculate the divergence for over-ground and treadmill walking. Experiments using motion capture technology are used to capture the movement. MATLAB software package is used to calculate the Lyapunov Exponents from the time series. Results are compared with similar studies in the literature. This work provides an insight on the level of stability for treadmill walking. A comparison with stability of normal gait might give an insight on how the treadmill can facilitate rehabilitation using gait.
Influence of Coating on High Performance Heat Resistant Textile Curtains
Authors: Vilarinho Maria Cândida , Araújo Paulo , Teixeira José Carlos , Silva Elisabete , Silveira Dionisio , Soares Delfim , Paiva Maria C. , Ribeiro Daniel , Branco Marisa
Published: January 2022

The protection of human life and goods assumes a growing concern in all forms of activities. The fire and smoke curtains act as a physical barrier to prevent the fire from spreading between spaces as well as to staunch the smoke and heat transfer to adjacent areas, while causing minimal interference. Usually, curtains are based on fiber structures that can be coated to enhance their protective capabilities. Also, the fiber structure can be developed into a complex pattern of 2D and 3D threads, with single or multiple materials that can be tailored to optimize its behavior. The thermal and fire protection depends on the fibers, fabric pattern and coatings.

The present paper reports the development of novel coated structures of fibers used for fire protection curtains. Basalt and glass fibers are used as yarn materials.

Following the certification standards the samples were assessed for their thermal resistance by measuring the temperature differential they provide while their integrity is evaluated. The sample is placed under stress in an attempt to mimic its own weight effect when in service. The temperature is monitored using thermocouples which are placed at both sides of the fabric and the integrity parameter is assessed through the occurrence of fabric rupture and smoke and/or odor release motivated by its deterioration.

Regarding the uncoated samples, the one composed of glass-fiber in both directions presents the best thermal performance. The addition of an alumina coating significantly improves the performance of all samples. However, while a thinner (0.05 μm) alumina layer provides better results for the sample with glass-fiber in both warp and weft directions, the behavior of samples composed of glass-fiber and basalt is superior when a thicker (0.3 μm) alumina layer is used. In both cases, an alumina coating application results in an increase of the gradient temperature (between curtain inside/outside temperatures) of about 38.0% (310.0 °C vs. 427.0 °C for the first and 386.0 °C vs. 526.0 °C for the latter.
Design and Testing of DiMES Carbon Ablation Rods in the DIII-D Tokamak
Authors: Orlov Dmitri M. , Hanson Michael O. , Escalera Jason , Taheri Hadith , Villareal Caitlin N. , Zubovic Daniel M. , Bykov Igor , Kostadinova Evdokiya G. , Rudakov Dmitry L. , Ghazinejad Maziar
Published: January 2022

We present the design of ATJ graphite [1] rods developed for ablation experiments under high heat flux (up to 50 MW/m2) in the lower divertor of the DIII-D tokamak [2], a magnetic plasma confinement device. This work is motivated by the need to test ablation models relevant to carbon-based thermal shields used in high-speed spacecraft atmospheric entries, where the heat fluxes encountered can be comparable to those achieved in the DIII-D divertor plasma. Several different designs for the flow-facing side of the rod are analyzed, including “sharp nose,” “blunt,” and “concave”. The last shape is studied for its potential to lower heat fluxes at the rod surface by increased radiation from trapped neutrals and reduced parallel plasma pressure. We also analyze the possibility of applying a thin (approximately 30 microns) layer of silicon carbide (SiC) to the exposed part of several carbon ablation rods to benchmark its erosion calculations and lifetime predictions. Such calculations are of interest as SiC represents a promising material for both thermal protection systems (TPS) and a fusion plasma-facing material (PFM). [3,4] Preliminary results from the DIII-D rod ablation experiments are also discussed.
Stochastic Dynamics of Rotating Wind Turbine Blades Influenced by Turbulence and Aeroelastic Uncertainties: Recent Developments
Authors: Caracoglia Luca
Published: January 2022

This paper describes the results of recent developments examining the flutter instability of wind turbine blades subject to various sources of input error and noise. The problem is relevant to the safety of the very long blades, usually installed on offshore wind turbine towers. The formulation is based on an implementation of stochastic calculus methods, allowing the evaluation of the effects of both inflow turbulence and aeroelastic load modeling errors and simplifications. The study establishes the general conditions for moment stability Feasibility of this type of analysis for the reliability of the blades is demonstrated by a numerical example.
Oligodendrocyte Tethering Effect on Hyperelastic 3D Response of Injured Axons in Brain White Matter
Authors: Agarwal Mohit , Pasupathy Parameshwaran , De Simone Robert , Pelegri Assimina A.
Published: January 2022

Numerical simulations using non-linear hyper-elastic material models to describe interactions between brain white matter (axons and extra cellular matrix (ECM)) have enabled high-fidelity characterization of stress-strain response. In this paper, a novel finite element model (FEM) has been developed to study mechanical response of axons embedded in ECM when subjected to tensile loads under purely non-affine kinematic boundary conditions. FEM leveraging Ogden hyper-elastic material model is deployed to understand impact of parametrically varying oligodendrocyte-axon tethering and analyze influence of aging material characteristics on stress propagation. In proposed FEM, oligodendrocyte connections to axons are represented via spring-dashpot model, such tethering technique facilitates contact definition at various locations, parameterize connection points and vary stiffness of connection hubs. Two FE submodels are discussed: 1) multiple oligodendrocytes arbitrarily tethered to the nearest axons, and 2) single oligodendrocyte tethered to all axons at various locations. Root mean square deviation (RMSD) were computed between stress-strain plots to depict trends in mechanical response. Axonal stiffness was found to rise with increasing tethering, indicating role of oligodendrocytes in stress redistribution. Finally, stress state results for aging axon material, with varying stiffnesses and number of connections in FEM ensemble have also been discussed to demonstrate gradual softening of tissues.
Steady Flow Studies of the Geometry Effects on the Recirculation Properties at the Iliac Bifurcation
Authors: Carvalho Violeta , Carneiro Filipa , Ferreira Ana C. , Gama Vasco , Teixeira Senhorinha , Teixeira Jose C.
Published: January 2022

The characterization of blood flow patterns is an important task to establish links between hemodynamics and atherosclerosis development, one of the leading causes of death worldwide. Taking into account that the development of cardiovascular diseases and the disturbances in blood flow profiles are characteristic of each individual, the study of the effects of geometry and flow distribution is quite important. For this reason, in the present paper, a CFD numerical model for both simplified and real anatomic iliac bifurcation was developed, taking into account a steady velocity inlet profile.

The results were analyzed, in terms of the recirculation zone length and location, but also in velocity and wall shear stress distribution. It was observed that the bifurcation angle does not affect significantly the recirculation properties. However, significant differences were achieved with different iliac diameters and bifurcation geometry. Moreover, outflow maldistribution in the iliac arteries leads to more complex flow patterns near the iliac bifurcation, intensifying reverse and asymmetric flow patterns. The results of the simulation using the realistic model geometry confirmed that the regions of the geometry prone to develop recirculation areas occur, preferentially, downstream the bifurcation at the outer walls of iliac branches.

In brief, this study allowed a better understanding of the relationship between hemodynamics and vascular diseases, through assessing the distributions of blood velocity and biomechanical forces imposed on the arterial wall by the blood.
Effect of Subcooling on Pool Boiling Heat Transfer Over Minichannel Surfaces
Authors: Dhanalakota Praveen , Mahapatra Pallab Sinha , Pattamatta Arvind
Published: January 2022

In the present work, pool boiling experiments are performed on copper minichannel and flat surfaces at atmospheric pressure with water as the working fluid. The pool boiling experiments are conducted for liquid subcooling of 0K (saturated), 10K, and 20K at atmospheric pressure. Minichannel-1 and Minichannel-2 have a square cross-section with side lengths 1 mm and 2 mm, respectively. The thermal performance of the boiling surface is characterized by the critical heat flux and heat transfer coefficient. The critical heat flux (CHF) is increased by 36–45 % for minichannel-2 and 15–17 % for minichannel-1 compared to a flat surface at all subcoolings. CHF can be increased as high as 287.54 W/cm2 by employing minichannel-2 and 20 K subcooling. Minichannel-1 and minichannel-2 enhanced the heat transfer coefficient as high as 25.21% and 68.59 %, respectively, compared to the flat surface. It is observed that the increase in surface area is the dominant factor in the enhancement of pool boiling heat transfer on minichannel surfaces.
i9Masks: From a Multidisciplinary Summer Project to a Non-Accredited Short Course
Authors: Carvalho Violeta , Rodrigues Cristina , Minas Graça , Lima Rui , Teixeira Jose C. , Teixeira Senhorinha
Published: January 2022

This study presents a research experience with engineering students at undergraduate and graduate levels, during the summer of 2020 at the School of Engineering, University of Minho, Portugal.

Following the first pandemic event in Portugal, from March to May 2020, the Foundation for promoting Science and Technology (FCT) has opened a call for research projects among students and researchers at different Universities. The main aim of these projects was to motivate students to return physically to the campus during a summer course, and to promote a research environment among them.

i9Masks was one of the projects approved by the University of Minho and its main objective was the development of innovative masks in a silicone elastomer for the protection of COVID-19 with the use of state-of-the-art technologies. The development of masks was at the time a very hot topic as well as a fashionable subject for research.

Considering the results obtained, from the final works presented by students, a very positive balance of the experience was achieved.

The i9Masks project was a useful learning experience for engineering education, particularly in Portugal, where the opportunity to participate in this type of “learning by doing” experience is very small.
Beam Element-Based Inverse Finite Element Method for Shape Reconstruction of a Wing Structure
Authors: Dong Tianyu , Yuan Shenfang , Huang Tianxiang
Published: January 2022

Shape sensing technology is the basis for the control system of the adaptive deformation wing. There are various deformation reconstruction methods based on strain information. The inverse Finite Element Method (iFEM) is popular for the advantages of no need to know the structural material and load information. However, iFEM, which mainly uses shell elements, has problems when applied on purely bending beam structures such as large amount of calculation and the waste of more than half of the element’s degrees of freedom. To solve this problem, this paper proposes a beam element-based inverse finite element method. This paper firstly derives the theoretical process of the beam element-based inverse finite element method based on the classical beam bending theory and the least squares variational principle. Then, the proposed method is applied on the main load-bearing structure of the fishbone shape of an adaptive deformable wing. COMSOL is used to calculate the displacement and strain and the FEM strain can be used as the input of the beam element-based inverse finite element method to calculate the reconstruction displacement. At last, the effectiveness and accuracy of the proposed method are verified by comparing the error of reconstruction and simulation displacement.
Fatigue Crack Growth Prognosis With the Particle Filter and On-Line Guided Wave Structural Monitoring Data
Authors: Chen Jian , Yuan Shenfang , Qiu Lei , Ren Yuanqiang
Published: January 2022

Prognostics and health management (PHM) techniques have been widely studied in recent years to increase reliability, availability, safety, and reducing maintenance costs of safe-critical systems, like aircraft and power plants. In these systems, fatigue cracking is still one of the most widespread problems affecting structural safety. However, it is difficult to determine the structure’s fatigue life of an individual system due to uncertainties arising from various sources such as intrinsic material properties, loading, and environmental factors. Even fatigue lives of the same specimens under laboratory tests have large dispersion. To deal with this problem, this paper introduces a fatigue crack growth prognosis method with the particle filter (PF) and on-line guided wave structural health monitoring (SHM) data. The guided wave-based SHM technique is adopted for on-line monitoring the presence and size of the fatigue crack. Besides, the monitored data is sequentially combined for correcting a physical fatigue crack growth model within the PF algorithm. Finally, the data of the fatigue tests of the hole-edge crack is used for demonstrating the proposed method.