bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibration and Acoustic Crepitus Sensing Using Piezoelectric Accelerometers and Automated Signal Analysis
Authors: Roytman Gregory , Budavich Matthew , Pocius Judith D. , Faydenko Jocelyn , Muligano Dana , Cramer Gregory
Published: January 2022

The vibration and acoustic emissions produced within facet joints of the lumbar spine, known as crepitus, can be a potential biomarker to identify decreased joint functioning and the site of low back pain. Using piezoelectric accelerometers and a silicone “phantom” mechanical model we sought to identify the site of crepitus. Past analyses of these data with human observers have been too time consuming for eventual practical clinical application, and a more expedient algorithmic method of analysis is preferable. In this study the signal filtering and processing functions of MATLAB were harnessed to filter aberrant noise as well as determine the location (level and left or right side) from which crepitus originated during induced crepitus events in the phantom model (n = 30). Development of this automated method refined the definition of facet joint crepitus. The automated method was found to be as reliable and valid as assessment by human observers, and took significantly less time (p = 0.009). Future studies will assess the reliability of the automated method to detect this phenomenon in humans.
Thermophysical Properties of U-10Mo Monolithic Fuel
Authors: Ozaltun Hakan
Published: January 2022

Monolithic fuel is a candidate fuel form that is being considered for the conversion of high-performance research reactors. This plate-type fuel consists of a high-density, U-Mo fuel in a monolithic form that is sandwiched between zirconium diffusion barriers and encapsulated in an aluminum cladding. To date, many plates were irradiated with a satisfactory irradiation performance, demonstrating that the conceptual design works. The program is now moving to the qualification phase, a predecessor to the timely conversion of the target reactors. To qualify this fuel system, the program must show that the fuel plates have predictable behavior, meet the safety standards, and perform well in reactors. The requirement of a satisfactory irradiation performance under normal operating conditions is primarily demonstrated by a successful testing. To demonstrate that the fuel system has a predictable behavior, the several key material properties should be quantified accurately since these properties are needed to estimate the thermal and mechanical behavior of the fuel system. Although, there is a large set of thermophysical property data available for unirradiated material, the property data for irradiated fuel is scarce. Since irradiation causes drastic effects in material, a significant change in material properties occurs. Consequently, using representative degradation models becomes essential for accurate performance assessments. This work examines thermal conductivity of U-10Mo, by evaluating recent experimental data from the literature and available theoretical models. The study has discovered inconsistencies in the literature data, revealing that previously developed theoretical models fail to predict the thermal conductivity of irradiated fuel.
An Ultra-Low-Frequency Active Vertical Vibration Isolator With Horizontal Constraints for Absolute Gravimetry
Authors: Yao Jiamin , Zhuang Wei , Feng Jinyang , Zhao Yang , Wang Shaokai , Wu Shuqing , Fang Fang , Li Tianchu
Published: January 2022

Absolute gravimeters have been widely used as an important instrument in geological exploration and geophysics. To achieve a required measurement precision, it is necessary to integrate a vertical vibration isolator with ultra-low resonance frequency into the gravimeter. In this paper, an active vibration isolator designed on the basis of a BM-10 passive vibration isolation platform is presented. In the isolator, a seismometer placed next to the payload on the same plate outputs a voltage signal proportional to the payload’s velocity. According to this signal, a feedback circuit based on a PID controller controls two identical voice coil actuators to drive the platform synchronously. In this way, the vibration of the payload is suppressed. The BM-10 platform has 6-DOF passive vibration isolation originally, but its horizontal vibration isolation is proved unnecessary or even harmful in absolute gravimetry. Hence, two linear bushings are applied as a horizontal constraint to ensure that the payload only moves vertically in a straight line. Experiments show the resonance period of the isolator reaches approximately 88 s. In addition, the active vibration isolator has shown a much better performance for vibrations at low frequency than the passive isolator. In the future, the vibration isolator will be improved and then be integrated in the NIM-AGRb-1 atom-interferometry absolute gravimeter for the evaluation of its performance.
High Fidelity Human Modeling via Integration of Skeleton Tracking for Predictive HRC Collision Detection
Authors: Streitmatter Gabriel , Flowers Jared , Wiens Gloria
Published: January 2022

This paper develops a predictive collision detection algorithm for enhancing safety while respecting productivity in a Human Robot Collaborative (HRC) setting that operates on outputs from a Computer Vision (CV) environmental monitor. This prediction can trigger reactive and proactive robot action. The algorithm is designed to address two key challenges: 1) outputs from CV techniques are often highly noisy and incomplete due to occlusions and other factors, and 2) human tracking CV approaches typically provide a minimal set of points on the human. This noisy set of points must be augmented to define a high-fidelity model of the human’s predicted spatial and temporal occupancy. A filter is applied to decrease sensitivity of the algorithm to errors in the CV predictions. Kinematics of the human are leveraged to infer a full model of the human from a set of, at most, 18 points, and transform them into a point cloud occupying the swept volume of the human’s motion. This form can then quickly be compared with a compatible robot model for collision detection. Timed tests show that creation of human and robot models, and the subsequent collision check occurs in less than 30 ms on average, making this algorithm real-time capable.
Drying of a Fully Saturated Porous Medium With Excess Water Layers - A Numerical Study
Authors: Asar Munevver E. , Yagoobi Jamal S.
Published: January 2022

Drying of moist porous media can be very energy inefficient. For example, in the pulp and paper industry, paper drying consumes more than two-thirds of the total energy used in paper machine. Novel drying technologies can decrease the energy used for drying and lessen the manufacturing processes’ carbon footprint. Developing next generation drying technologies to dry moist porous media may require understanding of removing moisture from fully saturated porous material with excess water. During papermaking, dry paper is fully saturated with in a water mixture that contains additional “excess water” before reaching the pressing section of a paper machine.

This paper provides a fundamental understanding of heat and mass transfer in fully saturated porous medium with excess water. For this purpose, a theoretical drying model is developed where the porous medium corresponds to paper and is assumed to be sandwiched between two excess-water layers (bottom and top). The thickness of each water layer is calculated, based on local temperature and total moisture content. The numerical model is transient and one-dimensional in space in thickness direction. This paper demonstrates the governing equations, boundary conditions, and results when the saturated porous medium with water layers is heated from one (bottom) side. Moisture and temperature profiles are estimated in the thickness direction of the porous medium as it dries. Results show that initial drying is rapid, due to the drying of the top water layer. Then, the moisture from the bottom water layer penetrates the porous medium, as the porous medium becomes slightly unsaturated due to evaporation at its top surface exposed to ambient air. When the bottom water layer is dried up, the porous media starts losing its moisture more significantly than in the previous stages, as expected.
Multi-Objective Thermal Optimization of a Nanofluid-Cooled Rectangular Microchannel Heat Sink Using Genetic Algorithm: A Comparative Study
Authors: Fazeli Hamid
Published: January 2022

The use of nanofluids as coolant fluid in the microchannel heat sink (MCHS) is an effective technique for the improvement of thermal performance in electronic devices. A comparative study is performed with the help of a multi-objective genetic algorithm (MOGA) to find the optimal geometric variables of the MCHS and choose the appropriate nanofluid and its optimal characteristics. For that purpose, four practical nanofluids, including Al2O3-water, Cu-water, SiO2-water, and carbon nanotube (CNT)-water, are thoroughly investigated. Simultaneously minimization of the total thermal resistance and pumping power consumption are taken into account as the optimization goal, and the MOGA is employed to achieve the optimal solution. To check the accuracy of the thermal resistance modeling and assessing the optimization algorithm, several case studies with a different number of optimization variables are defined to investigate the capability of the algorithm in finding the optimal microchannel design variables and choosing the suitable nanofluid. The optimization variables consist of the channel aspect and wall ratios, base thickness, volume nanoparticle concentration, diameter, and volume flow rate. Compared to other nanofluids, CNT provides better thermal performance. Increasing the concentration of nanoparticles enhances thermal performance, which can also be achieved through the reduction of nanoparticle diameter. Results of the considered case studies also show that considering more design variables through the optimization procedure, better thermal performance is achievable.
Control Temperature of the Air Conditioning System of a Vessel From Exergoeconomic Analysis
Authors: Barreto Deibys , Fajardo Juan , Berrio Julián , Torres Rosa , Gordon Yimy , Vidal Carlos
Published: January 2022

In this work the air conditioning system of a 93 m long and 14 m wide vessel with 4081 refrigerated m3 distributed in 51 premises is studied. In which energy, exergetic and exergoeconomic analyzes were carried out for control temperatures between 20 and 27 ° C and 50% relative humidity, with outdoor air conditions of 35 ° C and 70% relative humidity. For the vessel, the thermal load is calculated with an adaptation of the ASHRAE CLDT / SCL / CLF (cooling load temperature difference/cooling load factor/solar cooling load factor) methodology and the ISO 7547 standard. Thermal load contributors taken into account for the study were heat transfer through walls, ceilings, and glass in addition to gains from people, lighting, and Appliances. Transmission through walls and ceilings represents 33% of the thermal load, followed by glass with 18% and power equipment with 15%, the last three sources of thermal load generation are Appliances (12%), people (12%) and lighting (10%). For each degree centigrade of the control temperature, the thermal load is reduced by 2.4 and 1.1%, respectively, as determined by the ASHRAE and ISO methodologies. Similarly, the destruction of exergy is reduced by 4.16% for each degree Celsius that the control temperature is increased. An indicator is proposed to calculate the cost of generation of cooling load per unit volume and exergy of the thermal load from which it is obtained that the higher the control temperature, the lower the value of the cost of generation of the cooling load. From the exergoeconomic analysis, it is highlighted that the destruction of exergy is the main factor in the increase in system costs. Increases in exergy destruction increase the value of the indicator of cooling load generation costs per volume and unit of heat load exergy. For each degree Celsius that the control temperature is reduced, the cost of generation of cooling load per volume and unit of exergy of thermal load increases on average 0.35%.
Spectral Correlation Method for Fatigue Crack Detection Based on Nonlinearly Mixed Ultrasonic Waves
Authors: Sampath Santhakumar , Sohn Hoon
Published: January 2022

Recent developments in the nonlinear ultrasonic wave mixing method have enabled its use in detecting early-stage fatigue cracks. In this method, two input waves at distinct frequencies are applied to a structure with a fatigue crack (i.e., a nonlinear structure). The interaction between these waves gives rise to nonlinearly mixed harmonic components at the sum and difference of the input components. However, the amplitude of the mixed harmonic components generated by the fatigue crack becomes weak in a noisy environment. To overcome this issue, the conventional power spectrum method is used to extract the nonlinear components; however, it is unsuitable for analyzing nonlinear and nonstationary signals. This study presents an advanced signal processing method, called the spectral correlation method, to overcome this problem. The proposed method considers not only the mixed harmonic components in ultrasonic waves, but also the spectral correlation between these components. The uniqueness of the proposed method lies in the following: (1) a single transducer is used, instead of two individual transducers, to generate two input Lamb waves sequentially, (2) the spectral correlation of the mixed harmonic components is insensitive to noise components; (3) tone burst inputs are used as in spectral correlation, and a good contrast between intact and fatigue crack conditions is obtained when compared with the sinusoidal inputs, (4) the mixed components extracted from the spectral correlation method are more reliable than those obtained using conventional methods, and (5) the proposed approach can be applied to detect fatigue cracks. A theoretical model is presented to establish a relationship between the spectral correlation coefficient and the quadratic nonlinearity parameter. Experiments were conducted on aluminum plate specimens with fatigue cracks to validate the performance of the spectral correlation method. The experimental results showed that the nonlinearly mixed harmonic component extracted using our method is more effective for fatigue crack detection than that extracted using the conventional power spectrum method.
A Mathematical Model to Predict Alkaline Electrolyzer Performance Based on Basic Physical Principles and Previous Models Reported in Literature
Authors: Antoniou Antonios , Celis Cesar , Berastain Arturo
Published: January 2022

Hydrogen production through electrolysis is an important research topic since the use of hydrogen as a fuel has the potential to significantly reduce gaseous emissions in near future. The electrolytic splitting of water into hydrogen and oxygen can be carried out using for instance electricity generated from renewable energy sources such as solar radiation. Electrolysis processes occurring in electrolyzer cells are complex phenomena and a clear and accurate mathematical representation of the referred processes is vital to accurate predict electrolyzer cells performance. So a comprehensive mathematical model capable of properly describing alkaline electrolyzer cells performance, in terms of efficiency and hydrogen production rate, is proposed in this work. The mathematical model is based on several physical concepts such as energy losses due to electron and ion transfer, entropy increase, electrolyte flow rate, and electrolyzer physical structure and construction material. Compared to existing models, the new proposed one is more complete as it includes more operational parameters (six) affecting cells performance. Once developed, the proposed model has been fine-tuned using experimental data available in literature. The results obtained using the new developed model are in good agreement with Ulleberg’s experimental data. Based on the work carried out here, it is concluded that developing a mathematical model based on physical principles is crucial in the comprehension of electrolysis related processes and how to utilize them in the simplest and most reliable way.
Finite Element Model of a Cultured Vascular Smooth Muscle Cell Subjected to Uniaxial Stretch: Effect of Orientation Angle of Stress Fibers on Biomechanical Responses
Authors: Tamura Atsutaka , Makabe Kei , Yamashita Hatsune , Hongu Jun-ichi
Published: January 2022

Vascular smooth muscle cells (SMCs) in the extracellular matrix adapt to their surrounding environment in vivo with its contraction and relaxation. As blood pressure increases, the circumferential stress on the aortic wall also increases. The major components of the media are SMCs, so SMCs should regulate the vessel diameter and the mechanical balance of the aortic medial ring.

Thus, it is important to clarify how external forces on SMCs are transmitted through the intracellular components. Nuclei may sense changes in the applied mechanical stretch via stress fibers (SFs) or focal adhesions (FAs). However, there is little quantitative information available about the mechanical contribution of SFs and FAs to whole-cell mechanical events such as uniaxial stretching.

In the present study, therefore, we developed a finite element model of a cultured SMC, with contractile SFs, on a silicone substrate, and applied a uniaxial stretch, to investigate the mechanotransduction pathways involved in SMCs. We revealed that the initial orientation angle of the SFs was closely correlated with their resultant stretch, and the magnitude of the biomechanical force exerted by SFs.
Effect of Hole Diameter Deviation on Temporary Fastening Damage of Composite Materials
Authors: Yan Chen , Lin Yujin , Wang Hua
Published: January 2022

Temporary fastening technology has become an essential process in the aviation assembly process due to its functions such as eliminating the initial gap, suppressing the hole-making gap, and increasing the positioning accuracy. However, with the increasing proportion of carbon fiber reinforced polymer used in aviation, new problems have emerged in the installation of temporary fasteners: The contact area between the clamping feet and the composite hole is small. Excessive clamping force will cause damage to the periphery of the composite hole, which brings severe hidden dangers to the bearing capacity and durability of the aircraft composite structure. The deviation of the aperture at the assembly site will obviously aggravate the severity of this situation. Therefore, the size of the temporary fastener installation aperture needs to be carefully studied. In this paper, an FEA model is established in the Abaqus to investigate the effect of aperture deviation on temporary fastening damage. The model includes the reverse model of temporary fasteners and the composite laminates with holes. The 3D Hashin criterion is used to describe the failure of composite materials, the user material subroutine (UMAT) is written to predict the temporary fastening damage process of composite members, and the validity of the model is verified by comparison with experimental results, and the simulation of complex failure damage around the composite hole is realized. The established model is used to explore the influence of the installation aperture’s deviation on the temporary fastening damage of the composite component. The effect of the temporary fastener clamping feet’ installation direction and the degree of the temporary fastener’s off-axis is analyzed in detail. The results show that the deviation of the hole diameter will significantly impact the installation damage of the temporary fasteners of the composite member. As the installation aperture increases, the clamping force that can be applied by the temporary fastener gradually decreases. The installation direction of the clamping feet has little effect on the damage around the composite hole. The off-axis of the temporary fastener will cause serious damage to the composite hole. This paper has also obtained the mapping relationship between the maximum load-bearing clamping force around the composite hole and the hole diameter under the two conditions of no damage and limited damage. This paper’s research results will provide guidance for the tolerance design of the mounting holes on the assembly site and the installation of temporary fasteners to avoid unexpected installation damage to the high-value composite components caused by the temporary fastening process.
Spray-on Capacitive Proximity Sensors in 3D Printed Robotic Links
Authors: Detzel Samuel , Krieger Yannick S. , Hoefer Robert W. , Robe Anton , Sigling Annette C. , Lueth Tim C.
Published: January 2022

Proximity sensors are crucial components for any robotic system working in collaboration with humans. We integrated for the first time proximity sensors into 3D printed robotic links by realizing internal sensor electrodes with graphite spray coating. This method is perfectly suited for the manufacturing of specialized and individualized robotic systems or rapid prototyping. After design and fabrication of corresponding robotic links with appropriate inner chambers by selective laser sintering (SLS), graphite spray coating was applied to generate internal capacitor electrodes. Excellent sensor and detection properties were obtained. The proximity detection range proved to be indistinguishable from that of sensors made from conventional sheet metal. In addition to the advantage of enabling a simple integration of proximity sensors in different robotic link geometries, the sensor is protected from environmental influences due to its internal placement. Conductive spray paint allows us to cover even two-dimensionally curved surfaces. This way, the electrode areas can be maximized. The concept and its realization as well as the experimental results concerning the sensor properties and a 4R serial robot are shown in this paper.
Evaluating Piping Supports Modification to Mitigate Slug Flow Induced Vibration Utilizing Time-History/Response-Spectrum Approach in a Rich Amine Column NPS 30 Inlet Piping System
Authors: Herrera Sierralta Carlos , Al-Muslim Husain
Published: January 2022

Preventing potential failure in pipework due to fatigue induced vibration provoked by slug flow is a critical part of detailed engineering design phase as these types of failures have been evidenced across the industry, and particularly in the oil and gas sector leading to significant incidents.

Slug forces are generated at change of direction of piping systems (i.e: elbows, tees, branches, and laterals) due to change of momentum of the fluid in two-phase flow regimes; The order of magnitude of such slug forces depend on the process stream properties, and in the relation between the two phases liquid and gas converging into the same pipework.

In order to address this concern, the piping designer typical approach is to conduct the static equivalent method where dynamic loads are converted to static loads in the piping flexibility analysis. In this approach, the designer estimates the slug force by selecting the most conservative combination of both variables, density and velocity of the slug, which is multiplied by the internal sectional area of the pipe, where the slug load is expected to occur. The resulting slug force is then typically multiplied by 1.5 to 2.0 in order to take into account the dynamic load factor.

The resulting slug forces are applied at all the affected changes of directions as a constant force in the piping flexibility analysis. While this approach is routinely followed as it is typically conservative from the piping flexibility static load cases perspective, it does not simulate the real dynamic conditions of the piping system, as it does not consider the influence of the slug forces occurring as a function of time, wherein reality, not all the slug forces are occurring at once at any given time, but occurring sequentially as the fluid travels through the length of the pipe, impacting the elbows in a progressive order, which directly dependents on the velocity of the fluid and the estimated length of the slug.

Therefore, this approach may not be reliable to evaluate existing systems with high vibration due to the high level of confidence required before proceeding to perform field modifications.

This paper describe over a real case example, an alternative methodology which allowed to determine the dynamic interaction of the slugging forces by utilizing the Time-History assisted by Response-Spectrum, both available within common piping flexibility analysis software.

The methodology allowed to resolve the piping vibration problem on subject by re-designing the associated spring and supports, without reducing the gas treatment plant production rates nor shutting down the facility.

The original design and modification of NPS 30 piping inlet to a Rich Amine Column is discussed along with results of both flexibility analysis and field vibration measurements before and after the modification.
Fast Methods for Nonlinear Vibration Analysis of Variable Stiffness Panels
Authors: Andérez González Jorge , Vescovini Riccardo
Published: January 2022

This paper presents an approach for the nonlinear vibration analysis of Variable Stiffness (VS) plates based on Third-order Shear Deformation Theory (TSDT) along with a mixed variational formulation. The unknowns are expanded using the Ritz method, whilst time dependency is handled by referring to the Differential Quadrature (DQ) and the Harmonic Balance (HB) methods. The proposed framework guarantees reduced computational time, which is of particular interest when exploring the large design space offered by variable stiffness configurations. Validation against reference results is presented, as well as exemplary parametric studies illustrating the potential of the approach.
Deep Learning for Drag Coefficient Predictions of Spherical and Non-Spherical Particles
Authors: Mahyawansi Pratik , Lin Cheng-Xian , Chen Shu-Ching
Published: January 2022

The drag model for non-spherical particles required in a particle-laden flow is not fully established, which could cover a wide range of sphericities. This study focuses on developing an artificial neural network model by using a large number of available experimental data for a wide range of sphericities (0.034–1), density ratios (0.0005–0.491), and Reynold numbers (0.002–79432). Available experimental and DNS data for particles of various sizes and materials tested against liquid and gas are identified to correlate the drag coefficient. Three different neural network algorithms, Random Forest, Gradient Boosting, and a Deep Neural Network (DNN), are trained and evaluated. The neural network results were compared to the experimental results and to select numerical correlations. It was found that the DNN model outperforms all the other methods and algorithms for most of the studied sphericities (0.36–1).
A Novel Trilogy of e-STEM Programs
Authors: Gharib Mohamed , Katbeh Tala , Cieslinski G. Benjamin , Creel Brady
Published: January 2022

In recent years, pre-college educational programs have been introduced to increase the interest and supply of skillful people to work in STEM fields. While the emphasis has previously been primarily focused on the content of project-based learning programs, another factor that needs to be accounted for is the accessibility of the said programs. Unprecedented issues such as the sudden closure of educational facilities, as was experienced during the COVID-19 pandemic, should not hinder the learning opportunities that the students are after. Therefore, the shift from hosting conventional STEM programs to online platforms has become a crucial element in the expansion of STEM education. Delivering engineering-based projects through online STEM programs to school students includes wide expansion of the participating audience — which is not confined by the capacity limit of in-person programs — as well as ease of access. This has value not only on the individual level but also at the social level.

Three successful e-STEM (electronic STEM) programs are presented in this paper that are designed to support and enhance students’ learning of engineering concepts while also increasing students’ understanding of real-life applications. This has a close connection to the desire to increase online education in developing countries over recent years. The first program is called Innovate, Design and Engineer an App (IDEA). In this program, the students explore the fundamentals of programming and mobile app development. This provides the students with the foundation of coding, algorithms, and refining their ideas to produce a working mobile phone app that is created to meet a specified challenge. The second program is called Creative Fusion and Innovation (CFI). In this program, the students learned the basics of creating, editing, and analyzing their 3D designs; recognize the importance of creating 3D models in engineering; and understand how 3D printing works as they create their own 3D models. The third program is called Virtual Robotics Games (VRG). In this program, the students learn the fundamentals of designing, building, programming, and testing robots in a virtual environment. Through this program, the students learn the basics of robot design in addition to coding and simulation, which are all necessary tools for aspiring engineers.

These programs aim to provide STEM education access to build communities specifically in engineering, which is in high demand. Throughout these programs, the students are able to learn important computer skills and the concepts of the engineering design process. The programs also equip them with the required knowledge and problem-solving skills to tackle challenges. At the end of each program, the students will have created successful designs as solutions to the real-life problems that they were tasked with. In this paper, the details behind the planning, formation and production, and implementation of the three online programs are presented.
Laser-Assisted Friction Element Welding
Authors: Grimm Tyler J. , Parvathy Gowtham Vadivel , Mears Laine
Published: January 2022

Governmental regulations and increasing awareness of global greenhouse gas effects have caused a need to rapidly improve energy efficiency across all industries. The transportation industry is one such sector which utilizes a significant amount of energy, thus necessitating efforts to drastically improve the fuel economy of vehicles. A well-known method for achieving this is by vehicle lightweighting, which can be done through the use of multi-material structures. Inherent to the utilization of multiple materials is the joining process, which creates new challenges since vehicles and the supporting infrastructure have traditionally been based on mainly steel designs.

Friction element welding (FEW) is a process which can effectively join aluminum sheets to steel. This process involves the formation of a friction weld between a fastening element and lower steel substrate, securing an upper aluminum sheet between the fastener head and the steel. Prior to forming the friction weld, the fastener penetrates the aluminum through frictional heat-based softening and axial load. In relatively soft alloys, the aluminum flow remains close to the fastener’s shaft. However, when penetrating harder alloys, the aluminum flows further away from the shaft, resulting in protrusion outside of the fastener’s head in the final joint. This external material can lead to accelerated corrosion. Laser power is herein explored as a method for rapidly and efficiently heating the workpiece material to preemptively soften it before joining using FEW, thereby improving the flow behavior. It was experimentally determined that laser heating is a viable augmentation of the FEW process for improving aluminum flow during penetration. Furthermore, this process does not significantly increase the processing time of FEW, as heating can be performed in parallel with other essential steps. It can also reduce the total energy consumption under certain parameters.
Numerical Simulation of Impinging Slot Air Jet in the Presence of a Cross Flow
Authors: Gudi Abhay , Hindasageri Vijaykumar
Published: January 2022

A numerical investigation is carried out to study the effect of cross flow on local heat transfer distribution of a flat surface impinged normally by a slot air jet using ANSYS Fluent commercial software. Initially an experimental validation study is conducted to validate the centerline Nusselt number and to fix numerical settings such as Turbulence model, optimal mesh size and solution strategy. During this study, it is observed that the k-ϵ realizable model predicts fairly accurate results (less than 10%) when compared with the experiment data and therefore used for all further simulations in the present work. Grid independence study was conducted to arrive at optimal grid size. Grid size was varied from 0.08 million cell size to 0.2 million cells with 3% variation in percentage of peak Nusselt number. It is ensured that minimum of five boundary layers are maintained in numerical grid with y+ not more than 5 for all the cases studied. Further, the influence of nozzle exit to impingement plate distance (z/d = 2 to 6) is studied for different cross flow velocity to the main jet velocity ratios (M = 0 to 1). The Reynolds number (Re) is varied from 5000 to 50000. Furthermore, the aspect ratio of the slot jet is also varied. The center-line distribution of Nusselt number along the crossflow direction is provided. From the present numerical investigations, it is found that the presence of cross flow jet may result in either increase or decrease of the peak Nusselt number. This is attributed to the vorticial structures generated from the interaction of the wall jet of the main flow jet with the cross-flow jet. For the smallest nozzle tip to plate spacing, Z/D = 2, the peak Nusselt number is observed for the highest cross flow, M = 1 at higher Reynolds number (Re = 20,000 and 50,0000). For the larger nozzle tip to plate spacing (Z/D = 4 and 6), the peak Nusselt number is observed for the intermediate cross flow (M = 1/2) at higher Reynolds number (Re = 20,000 and 50, 0000). For the highest aspect ratio of 2, it is observed that peak Nusselt number decreases with the increase in crossflow. On the contrary, the square nozzle with lowest aspect ratio of 1, it is observed that the peak Nusselt number increases with the increase in crossflow.
Experimental Verification of Model-Free Vibration Control Technique Based on a Virtual Controlled Object Considering Actuator Parameter Uncertainty
Authors: Yonezawa Ansei , Yonezawa Heisei , Kajiwara Itsuro
Published: January 2022

This study proposes a novel model-free vibration controller based on a virtual controlled object (VCO) considering actuator parameter uncertainty. A proof-mass actuator, which is modeled as a single-degree-of-freedom (SDOF) system, is employed. A VCO, which is defined as an SDOF system, is inserted between the actual controlled object and the actuator model. Considering frequency transfer characteristic from actual controlled object to VCO, setting appropriate parameters of the VCO realizes model-free control. A state equation to design the model-free controller is derived based on the two-degree-of-freedom (2DOF) system composed of the actuator model and the VCO. The actuator parameter uncertainty is quantitatively modeled in the 2DOF plant. Traditional mixed H2/H∞ control theory is applied for the uncertain plant to design a model-free controller with high damping performance and robustness to the actuator uncertainty. The effectiveness of the proposed controller is confirmed by vibration control experiments.
Fracture Behavior of Alumina/Epoxy Resin Interface and Effect of Water Molecules by Using Molecular Dynamics Using Reaction Force Field (ReaxFF)
Authors: Nishino Hiroki , Kanamori Kohei , Kimoto Yoshikatsu , Okada Kazuma , Yonezu Akio
Published: January 2022

Adhesion bonding of metals and polymers is attracting attention as an innovative bonding technology to realize high functionality and weight reduction of various mechanical parts and structural materials. This technology has been significantly demanded with the rapid development of multi-materials in recent years. However, it has been reported that natural oxide film and hydroxide film are formed on the metal surface, resulting in the change in adhesion, especially degradation of adhesion is sometimes accelerated by water molecules at the interface. The mechanism of adhesion degradation is still unclear. In this study, the interface between metal and resin was modeled using the molecular dynamics (MD) simulation to investigate how the moisture (water molecules) on the interfacial surface affects the adhesion. This study varied the amount of water molecules at the interface and investigated how water molecules affect the adhesive strength subjected to uni-axial tensile loading. In addition, the potential energy around the interface was calculated, and the adhesion mechanism with respected to water molecules was carefully discussed.
Analysis of Correlation Between Manufacturing Parameters and Mechanical Strength Followed by Uncertainty Propagation of Geometric Defects in Lattice Structures
Authors: Mang Chetra , Tahmasebimoradi Ahmadali , Lorang Xavier
Published: January 2022

Lattice structures are widely used in various applications, especially in aeronautic, aerospace, and medical applications because of their suitable properties. Thanks to advancement of the additive manufacturing technology, the lattice structures can be manufactured by different methods such as laser beam melting technology. However, the presence of geometric defects in the lattice structures is inevitable due to the manufacturing process. The geometric defects may have high impact on the mechanical strength of the structures. The geometric defects are directly linked to the process parameters. This paper presents the analysis of the correlation between the process parameters and the mechanical strengths. In addition, the uncertainty propagation of the mechanical strengths according to the process parameters is also studied.
Analysis of Drilling Thrust for Straight and Inclined Micro-Hole in Thermal Barrier Coated Inconel 718 Superalloy
Authors: Khadtare Avinash N. , Pawade Raju S. , Joshi Suhas S.
Published: January 2022

The aero engine turbine blades made of Inconel 718, have thermal barrier coatings (TBC) to sustain high temperature air stream and cooling holes to reduce severe heat load. The complex physical and chemical properties of metal and ceramic layers pose challenges in a drilling these holes. Therefore, researchers have used laser and electrical discharge machining processes, which are time-consuming, costly, and inflict surface damages in and around the holes. To overcome these drawbacks, conventional micro-holes drilling has been adopted in this work. Drilling thrust distribution over cutting edges of micro-drills while drilling straight and inclined holes, under different cutting conditions has been analysed. The input parameters include: spindle speed, drill feed, and workpiece inclination, each at two levels. Each experiment was performed on TBC IN 718 sheet using a 600 μm TiAlN coated carbide drill under a dry peck-drilling cycle and was repeated twice. The results show that maximum elemental thrust in each experiment was found to be at the chisel edge. It was found to be 50–60% of the total thrust and varied non-linearly along the drill cutting edges, for straight as well as an inclined hole drilling. The unequal radial thrust distribution was observed due to workpiece inclination in case of inclined hole drilling, whereas a straight hole drilling shows an equal radial thrust distribution on each cutting edge.
Scalable Fiber Dip Drawing Method Using Automated Tracks
Authors: Heinz Abigail , Jao Dave , Beachley Vincent
Published: January 2022

A novel fiber production system established using principles of the dip drawing process is outlined in this paper, known as track spinning (TS). This system can produce micro- and nanofibers from polymer solutions for use in a variety of applications including filtration and biomedical devices. The system features automated tracks operated by a programmable motion controller in combination with stepper motors to consistently produce nanofibers. Utilizing a lignin-based solution, nanofibers of approximately 700–800 nanometers diameter have been successfully achieved and replicated with this device. TS offers wider compatibility with various solutions, in addition to scalability to fit the needs of the application or product. The TS device could open the doors to wide scale, automated nanofiber production.
Experimental Investigation of the Manufacturing of Porous Solid Oxide Fuel Cells
Authors: Wilhelm Cole , Schaffer Evan , Welles Thomas , Ahn Jeongmin
Published: January 2022

Solid oxide fuel cells (SOFCs) are typically operated in a dual-chamber setup, where the fuel and oxidant flows are separated by the fuel cell. However, dual-chamber SOFCs (DCSOFCs) require sealant to keep the flows separate, meaning that rapid heating and cooling cycling could break the seal. The initial answer to this problem was a single-chamber SOFC (SC-SOFC). The SC-SOFC is simply a planar fuel cell mounted parallel to a mixed fuel and oxidant flow. This system operates through the catalytic reactions of the anode and cathode with the fuel and oxidant, respectively. The drawback of this design comes from the requirement of fuel rich flow. A fuel lean flow leads to the oxidation of the anode and failure of the cell. On the other end, a fuel rich flow will greatly decrease system efficiency as much fuel will pass the cell and be wasted, making SC-SOFCs a difficult technology to implement. This issue led to the development of a porous SOFC (PSOFC), as a variant on the SC-SOFC. The PSOFC incorporates a similar mixed flow but is mounted perpendicular to the flow with cathode upstream of anode, and a catalyst downstream of the anode with the goal of reforming exhaust into syngas for a zero-emission fuel cell. Pores through the entire cell allow the flow to reach the anode, from the cathode side of the cell. The zero-emission condition is realized with the use of hydrocarbon fuels in the mixed flow. Reactions of fuel and air in the cell result in products of CO2 and H2O, which are then reformed by the catalyst into syngas (H2 and CO). Exhaust reformation by the catalyst is possible due to the high operating temperature of SOFCs. Syngas from the cell may be used immediately for further electricity generation or stored for later use. Manufacturing of a PSOFC is carried out with additive manufacturing (3D printing). Techniques of manufacturing PSOFCs will be discussed. The catalyst layer has been omitted from cell production until electricity generation performance of the cell improves. PSOFCs tested thus far have produced under 100 mW/cm2 with an open circuit voltage (OCV) of 0.60 V. This performance is not enough to begin implementing PSOFCs in industry. However, it does set a solid base for future PSOFCs and shows that they are a viable source of power generation. With further improvement of manufacturing methods and implementation of a catalyst, PSOFCs will become an important tool in zero-emission power production.
Advanced Exergetic Analysis of Preheat Train of a Crude Oil Distillation Unit
Authors: Fajardo Juan , Negrette Camilo , Yabrudy Daniel , Cardona Camilo
Published: January 2022

In this investigation, the conventional and advanced exergy analysis is used to obtain information about the conditions of the heat exchangers belonging to a crude oil distillation unit, previously to future studies to establish the most cost-efficient moments for the execution of maintenance activities in the exchangers. Conventional, unavoidable, avoidable, endogenous, and exogenous exergy destruction is calculated and the combinations between these last four terms. Mexogenous analysis is applied to individualize the relationships between the exchangers of the network. The results put the total exergy destruction at over 61.6 MW, being 63% avoidable. Five heat exchangers are considered critical because they concentrate the highest rates of exergy destruction, corresponding to 39% of the total exergy destruction in the network, this categorization allows focusing the improvement works on heat exchangers that will produce a substantial increase in the efficiency of the preheat train. Additionally, to evaluate the performance in a better way, the effect of unavoidable exergy destruction on performance measurement of exchangers through the exergy efficiency is studied, indicating that in some cases removing the unavoidable part can increase the second law efficiency by more than fifteen percentage points.
Tunable Topological Wave Control in a Three-Dimensional Metastable Elastic Metamaterial
Authors: Dorin Patrick , Liu Xiang , Wang K. W.
Published: January 2022

The concepts of topological insulators in condensed matter physics have been harnessed in elastic metamaterials to obtain quasi-lossless and omnidirectional guiding of elastic waves. Initial studies concerning topological wave propagation in elastic metamaterials focused on localizing waves in 1D or 2D mechanical structures. More recent investigations involving topological metamaterials have uncovered methodologies to achieve unprecedented control of elastic waves in 3D structures. However, a 3D topological metamaterial that can be tuned online to expand functionalities and respond to external conditions has yet to be developed. To advance the state of the art, this research proposes a tunable 3D elastic metamaterial that enables the reconfiguration of a topological waveguide through the switching of metastable states. Through careful design of internal bistable elements in the metastable unit cell, a switching methodology is developed to obtain topologically distinct lattices and a full topological bandgap. Analysis of the dispersion relation for a supercell reveals the presence of a topological surface state at the interface of topologically distinct lattices. Full-scale finite element simulations illustrate topological wave propagation in a 3D structure with a path that can be tailored on-demand. The research outcomes presented in this paper could be beneficial to potential applications requiring programmable and robust energy transport in 3D mechanical structures and serve as an inspiration for further work in adaptive 3D topological metamaterials.
Navigation and Path Planning of an Autonomous Mobile Robot
Authors: Nandikolla Vidya K. , Morris Eden , Aquino John , Paris Thomas , Wheeler Kevin
Published: January 2022

Autonomously navigating robots are used in many applications including assistive robotics, military, space exploration, manufacturing, etc. Unmanned ground vehicles (UGV) are an example of autonomous systems falling under the category of navigation, where navigation is dominantly composed of automatic transport and movement in real world environments. Simultaneous Localization and Mapping (SLAM) provides the best approach to the problems faced in unknown environments. Visual based cameras, light detection and ranging (LiDAR) sensors, global positioning systems, and inertial measuring units (IMU) feed constant streams of data to the SLAM algorithm. These sensors allow the UGV to explore an unknown outdoor environment whilst traversing around obstacles. The objects focused are construction barrels, cones, ramps, flags, and white lanes. Utilizing open source ROS packages, the UGV navigation algorithm uses 2D LiDAR, IMU, GPS, and depth camera data to combine the sensor inputs for a reliable robotic system. This paper demonstrates a robotic system combining RGB depth camera, object detection, and conventional outdoor SLAM navigation in unknown environments. Once a ramp or flag is detected an alternative path is implemented that is different from the global GPS path. The UGV combines all these methods to reliably explore unknown environments without the need for teleoperation.