bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Frost Formation in Freeze-Out Purification of Gases for Cryogenic Applications
Authors: Kroll Duncan , Hasan Nusair
Published: February 2023

Cryogenic refrigeration and liquefaction systems require ultra-high purity refrigerants (helium, argon, hydrogen, etc.) for proper operation. Common contaminants in the refrigerant gases freeze at the operating temperatures of these systems, causing performance degradation of process equipment. Therefore, ultra-high purity refrigerant gas (1.0 ppmv or less contaminants) is often used. However, removal of low levels of moisture (10 ppmv or less) from the refrigerant gas is particularly challenging. Contaminant freeze-out processes in a specifically designed heat exchanger have the potential to achieve effective and efficient purification. Developing an understanding of the contaminant frost formation process is crucial for the proper design of an effective freeze-out heat exchanger. A transient computational model simulating formation and densification of frost on an isothermal cryogenic surface from a contaminated refrigerant gas stream has been developed. The mass and energy conservation equations are discretized and simultaneously solved to obtain the frost layer thickness and frost surface temperature. The model is validated using available experimental data for frost formation from a humid air stream. Several parameters, namely — contaminated gas stream pressure, surface temperature, flow Reynolds number, and carrier (refrigerant) gas affect the interaction between frost formation and densification. The effect of these parameters on the frost formation characteristics has been systematically studied using the developed numerical model. The developed model can be utilized to predict the freeze-out heat exchanger performance degradation and its moisture collection capacity.
Contribution of Piezo1 in ECM Stiffness Incited Epithelial Cell Remodeling
Authors: Jetta Deekshitha , Shireen Tasnim , Prabhu Rajath D. , Hua Susan Z.
Published: February 2023

Cells are sensitive to mechanical cues from the ECM such as, stiffness, topography, and roughness. Tissue stiffening due to ageing or diseases has been shown to affect cell proliferation, differentiation, migration, and apoptosis, but the mechanosensors that respond to ECM stiffness changes have not yet been fully understood. Recent studies on mechanosensitive Piezo1 channels have shown that these channels are sensitive to ECM cues, such as mechanical confinements implemented by micropatterns. We hypothesize that Piezo1 could serve as a force sensor for local ECM stiffness. Using a ‘2-well PDMS chip’ consisting of substrates of different stiffness, namely, hard (∼1000 kPa) and soft (∼0.1 kPa), we studied the role of Piezo1 on stiffness-dependent morphology changes in epithelial cells. The results show that cells respond to substrate stiffness variations with profound cytoskeletal reorganization and moderate changes in their spreading area and shape. Cells on the hard substrates were only ∼20% larger than that on soft substrates within the same culture period of 2.5 hrs and at a similar confluency. However, cells on hard substrates show abundant F-actin bundles that are reorganized to peripheral actin rings on soft substrates. Inhibition of Piezo1 with GsMTx4 or Gd3+, largely reduced the formation of thick actin bundles on hard substrates. Activation of Piezo1 with specific agonist, Yoda1, enhanced the formation of actin bundles. These results indicate that the epithelial cells’ response to ECM stiffness is mediated by Piezo1 through its function of permeating Ca2+ ions. This study demonstrates that Piezo1 could be an ECM mechanosensor in epithelial cells.
Impact Damage Evaluations in a Composite Laminate Using Guided Wave-Based Simulation
Authors: Zhuang Linqi , Chaurasia Adarsh , Najafi Ali
Published: February 2023

In the present paper, guided wave propagation along a composite plate was simulated using a 3D Finite Element (FE) model in order to characterize the potential damage due to impact. The wave is induced by a piezoelectric transducer. A pristine composite case and various cases representing different commonly observed impact damage modes were created. The wavefield contour and out-of-plane displacement data at different sensors between the pristine and damage cases were then compared to differentiate type of damage existing within the composite plate. It is found that observed wave propagation pattern and signals had significant difference between delamination cases and pristine one and the maximum amplitude of out-of-plane displacement of the plate during wave propagation increases with increasing delamination size when wave reaches and passes damaged area. The wave propagation in a composite plate with earlier stage damage, i.e., matrix cracks simulated in the present study, however, shows little difference compared to the pristine case for the wavelet frequencies studied herein.
Effect of Metastructure Design on the Performance of Pressure Sensors
Authors: Zhao Huan , Huddy Julia E. , Scheideler William J. , Li Yan
Published: February 2023

Pressure sensors have been used in devices that require accurate and stable pressure measurements for reliable operations. Metastructure-based pressure sensors (MBPS) have the potential to achieve higher sensitivity and broader sensing range with greater design flexibility and lower weight. Currently, additive manufacturing (AM) has enabled rapid prototyping of high-resolution metastructures at small scales. Deposition of a conductive coating layer on the metastructure can effectively introduce electrical conductivity in MBPS. However, the coupling between the electrical response and the mechanical properties of the metastructure remains unknown. It is not clear how the metastructure design can affect the performance of pressure sensors. In this work, a set of octet-truss cubic metastructures with different unit cell numbers are modeled and fabricated. The sensitivity and sensing range of each metastructure design are predicted from the coupled mechanical-electrical finite element model, the analytical model and the in-situ compression-resistance test, respectively. It is found that increasing unit cell number leads to decreased nominal resistance and enhanced sensing range. But the improvement of sensitivity is limited when the unit cell number exceeds a threshold value. The computational and experimental approaches developed here can be applied to other MBPS with different metastructure configurations and material selections.
Mechanical Characterization of Thermally Insulated Composites
Authors: Smith Michael P. , Cavallaro Paul V. , O’Donnell Jacob D. , Warner Eric A. , Valm Nicholas A. , Gencarelle Nick
Published: February 2023

This research study investigated the flame-smoke-toxicity (FST) behaviors of water-based, nontoxic, and lightweight coating materials as thermal insulation for fiber-reinforced polymer (FRP) composites. Material experiments were conducted to evaluate the thermal and mechanical performances of these materials in two forms, namely as coatings on and matrices in structural composites. The present research evaluated the thermal protection performance of a nontoxic, aqueous coating material (SBS-1607[1]) demonstrated on carbon- and glass fiber-reinforced epoxy composites. The SBS-1607 coating is a ceramic particulate-filled thermoset material. The SBS-1607 coating does not produce toxic gases during a burn event and can be used as novel matrix material.

The SBS-1607 material was applied as thin coatings on glass fiber (GF) and carbon fiber (CF) epoxy laminated plates. The dimensions of both laminates were 8 inches by 8 inches by 0.197 inches (203.2 mm by 203.2 mm by 5.00 mm). The thickness of the SBS-1607 coating was 0.025 inches (0.67 mm). The maximum temperatures measured from the thermocouple for the uncoated GF and CF samples were 158.7°F and 431.1°F, respectively; the inclusion of the SBS-1607 coating on the GF and CF samples reduced their maximum temperatures to 144.6°F and 227.2°F, respectively.

Residual tensile strengths and elastic moduli were used as indicators of thermal damage in the matrix. Visible damage zones were approximated using surface measurements. The coated GF and CF burned composite specimens respectively had 71.85% and 151.14% higher UTS than their uncoated counterpart; the GF and CF specimens with the SBS-1607 coating therefore sustained less damage after the thermal event test.
A Computational Parametric Design Approach for Orthopedic Implants Under Highly Nonlinear Conditions
Authors: Kulkarni Mandar C. , Dandekar Akshay , Burchnall Mark , DeWall Ryan , Oberli Joel
Published: February 2023

The ability to perform computational parametric studies can reduce design loops and thus the design development timeline. The models also need to be thoroughly verified and validated as per standards such as ASME VVUQ 40 to ensure their accuracy relative to the device design, its configuration and application.

As a case study, this paper presents the development of a computational approach to simulate off axis screw insertion followed by cantilever loading on a predicate/on-market trauma locking plate implant. Due to off-axis insertion a high probability of cross threading between the threads of the screw head and the plate exists. This can introduce significant damage to the threads on both the screw as well as the plate which then potentially impacts the load bearing capacity of the screw-plate interface.

This paper compares two simulation approaches i) Lagrangian approach with element deletion and ii) Coupled Eulerian Lagrangian (CEL). Simulations are performed using a general-purpose finite element code ABAQUS® along with an explicit time integration approach.

The modeling approach is validated by comparing the predicted response of the screw-plate interface with cantilever loading results from laboratory tests. The thread deformation profiles are compared to the observed thread damage from testing. Effect of simulation parameters such as mesh density and mass scaling for an explicit quasi-static simulation are studied.

The results show potential in continuing further investigations to enable employing the models as tools to perform parametric studies. For the insertion configurations simulated, the models are able to simulate the desired screw head prominence. The deformation profiles and the regions with thread damage as predicted by the analysis compare well with the observed thread damage during the tests. When the simulations diverge from the observed test data, the reasons for this variability are investigated and potential solutions or additional tests/simulations are recommended.

The paper highlights the challenges and potential evaluation approaches while attempting to develop a robust computational methodology which can be employed for design development when specifically applied to highly nonlinear complex loading scenarios.
Testing of a Robotic Prosthetic Leg
Authors: Davidson Michael , Daher Noha , Fryer Thomas , Dudley Robert , Schaepper Johannes , Tran Duc
Published: February 2023

We report on our evaluation of a prototype robotic prosthetic leg on a subject with leg amputation. This biomedical device aimed to improve stance stability, increase balance confidence, and reduce the contralateral limb’s kinetic stresses in gait. The objective of this study was to test the safety and feasibility of the device on an active person with leg amputation. A single female subject with a knee disarticulation (KD) is fitted with the prototype prosthesis and tested against her prescribed daily use prosthesis. In addition to extended walking on level ground, kinematic and kinetic measures were taken in an 18-camera motion capture lab with two in-floor force platforms to assess body symmetry while the subject used this prototype device. We assessed balance confidence using the activities-based balance confidence questionnaire. While performing the 10MWT, the subject could ambulate at a maximum velocity of 0.77 m/s and an average of 0.61 m/s. In the six-minute walk test (6MWT), the subject walked a distance of 206 meters with a velocity of 0.57 m/s. Kinematic symmetry of both lower extremities improved in walking tasks. However, kinetic symmetry was inconclusive. In total, the subject walked on the device for 2 km. We found the device safe on a single amputee and is feasible for future clinical testing in a larger population.
Modeling and Simulation of Chip-Flow in Grinding of Different Materials – AlMg5 and C45
Authors: Lortz Wolfgang , Pavel Radu
Published: February 2023

Grinding offers specific advantages in comparison with other machining processes. The trend in industrial production toward higher productivity with increased part accuracy, using harder-to-machine materials, naturally leads to the increasing use of grinding to solve many material removal challenges. However, current technological advancements and innovation trends require science-based solutions capable to provide accurate models of the chip formation process, enabling optimization and control. The aim of this paper is to develop an adequate chip-formation model resulting in a realistic grinding chip with corresponding influence on the workpiece. The developed fundamental equations in metal plasticity are relevant for each material and their alloys; so that the total chip-flow with discontinuity and corresponding body forces can be solved. In addition, the resulting self-hardening effect, as well as the created temperatures — due to the deformation process — will be discussed and presented. Despite the large number of investigations and simulations, there is still no clarity on these subjects. The newly developed mathematical equations for strain and stress lead to square grid deformation in the chip formation zone, and this grid deformation will not disappear after completing the grinding process, so that the theoretical developments can be compared with practical results. As long as the created theoretical result will fit the practical result, we can be sure that we are on a relevant, realistic path. This will be presented for two different materials AlMg5 and the carbon steel C45. For the material AlMg5 we get a chip with integration of different plastic layers bonding together as a complete spherical grinding chip. The result is characterized by higher grinding forces, rough and thermally influenced workpiece surface. Quite contrary is the chip formation of the carbon steel C45. As a result of self-blockade at the interface between material and cutting edge, a segmented chip will follow with dynamic forces and a chattering process influencing the total machine behavior as well as the workpiece roundness and resulting surface. Finally, a high agreement between the developed theoretical and experimental results could be documented.
A Dynamics Model of Locomotive Mechanism Drilling Into Lunar Regolith
Authors: Yuan Zihao , Mu Ruinan , Yang Jiafeng , Wang Ke , Zhao Haifeng
Published: February 2023

In this work, a dynamic model is proposed to simulate the drilling and steering processing of an autonomous burrowing mole to access scientific samples from the deep subsurface of the Moon. The locomotive module is idealized as a rigid beam. The characteristic parameters are considered including the length, cross-section diameter and centroid of a cylindrical rod. Based on the Lagrangian mechanics, a 3-DOF dynamic model for the locomotion of autonomous device underground is developed. By introducing the contact algorithm and resistive force theory, the interaction scheme between the locomotive body and regolith is described. The effect of characteristic parameters on resistive force and torque is studied and discussed through numerical experiments. The simulation results show that this method may adapt to a variety of drilling and burrowing motions in the lunar subsurface environments. Overall, the proposed method actually provides a reduced-order model to simulate the operating and controlling scenarios an autonomous burrowing robot in lunar subsurface. It may be further generalized to consider more complex conditions, including depth-dependent regolith model, 3D trajectory planning and navigation algorithms, etc. This model may provide intuitive inputs to plan the space missions of a drilling robot to obtain surface samples in an extraterrestrial planet, such as the Moon or Mars, etc.
Uncertainty Quantification on Galvanic Corrosion Based on Adaptive Surrogate Modeling
Authors: Bansal Parth , Zheng Zhuoyuan , Li Yumeng
Published: February 2023

Dissimilar material joints are widely used in the vehicle manufacturing industry. These joints are mainly formed by using joining techniques like the Self-Piercing Riveting (SPR), Resistance Spot Welding (RSW) and Rivet-Welding (RW) due to their high performance, short cycle time, and adaptability. However, the difference in the equilibrium potential between the dissimilar materials in the presence of electrolytes leads to galvanic corrosion in these joints that can impact the safety and the reliability of the whole system. In this paper, we focus on Al-Fe galvanic corrosion and develop simulation-based machine learning based surrogate model for statistical corrosion analysis of such pairs, thereby enabling the resilience and reliability analysis of dissimilar material joints under corrosion environment. In this study, a physics-based finite element (FE) corrosion model has been developed to simulate the galvanic corrosion between a Fe cathode and an Al anode which considers the underlying crystal microstructure of the Al anode. Geometric and environmental factors such as crevice gap, roughness of anode, conductivity, and the temperature of the electrolyte are investigated. A comprehensive Uncertainty Quantification (UQ) study is then conducted to understand the overall corrosion behavior of the Fe-Al joints. Electrolyte conductivity is seen to have the largest effect on the material loss and therefore needs to be managed closely for better corrosion control. This study will help with enhancing the reliability and resilience of dissimilar material joints through designing and manufacturing considering corrosion performance.
Estimation of Road Slope Based on IMU Error Compensation and GPS Based Multi-Sensor Fusion
Authors: Xu Zeyu , Liu Haijiang , Xing Zheng
Published: February 2023

In the road test of vehicle performance evaluation, real-time and accurate estimation of road slope is essential for objective evaluation. Using slope meter directly can bring many problems such as large randomness and errors in road test. Using complex road slope estimation algorithm often brings redundant sensors and reduces detection efficiency.

Aiming at the above problems, this paper proposes a road slope estimation model based on IMU error calibration and multi-sensor signal fusion. First, the vehicle-road dynamics and kinematics models are established. Then, the error sources of IMU are analyzed, and the calibration and compensation methods are proposed. The acceleration signal of IMU is compensated by inertia through the vehicle velocity signal obtained by multi-sensors, and the projection of gravity acceleration vector in the vehicle coordinate is decoupled. Finally, the model fuses the decoupled result with IMU angular velocity value through Kalman filter algorithm, and outputs the estimated slope of the road.

The road test results show that the model can effectively compensate the IMU installation error and accurately estimate the road slope. And the slope estimation error is less than 0.5%, which can meet the needs of the road test of vehicle performance evaluation.
Dynamic Modelling of a 4WD/4WS Ground Vehicle by Using Gibbs-Appell Approach
Authors: Pius Pius E. , Selekwa Majura F.
Published: February 2023

Although most wheeled robotic ground vehicles are either skid steered or differentially steered, there has been an increased interest in four independently driven all-wheel steering systems because of their torque density and maneuverability in tight turns. Controlling these vehicles requires coordination of the steering angles and wheel speeds such that the basic rigid body kinematic constraint on the instantaneous center of rotation (ICR) is satisfied. This makes them difficult to control except for simple cases where either the center of curvature for all turns is constrained to be along the perpendicular bisector to the longitudinal centerline of the vehicle or considerable wheel slippage is allowed to happen. Several efforts have been reported to address this problem, most of which tend to simplify the problem by extending the well-known bicycle model to these vehicles. This paper uses the Gibbs-Appel formulation to develop the equations of motion of a 4WD/4WS vehicle in the quasi-coordinate space while enforcing both the ICR and no slip constraints. Unlike the Lagrange-Euler and the Newton-Euler formulations that use Lagrange multipliers to handle constraints, which increases the dimension of the system, the Gibbs-Appell formulation results in a model of a relatively lower dimension. This model is not only easy to use in control design but also captures the dynamics of the vehicle by constraining the wheels to remain on the path. Simulation results using a simple feedback linearization controller showed the vehicle tracking the path more accurately without wheel slip where the wheels remained on the path all times.
Flexible Energy Harvesters for Harsh Environments: A Review
Authors: Haskell Andrew , Soltani Seyed
Published: February 2023

As the power consumption requirements for the electronics decreases, the notion of powering the electric circuits by harvesting the ambient energy deems more practical. Particularly, energy harvesters could be used for powering the next-generation “flexible” microelectronics capable of being stretched, bent, twisted, and deformed without affecting their normal functionality. So far, several energy harvesters have been developed by the researchers, however, less attention has been paid to the performance of the energy harvesters in harsh i.e., hot humid, environment. Thin film technologies, used to protect the MEMS energy harvesters, continue to play a key role in the development of stretchable electronics, flexible displays, and a host of other applications. Nevertheless, movable components can be exposed to cyclic loading in these applications, which can result in fatigue failure of the MEMS device, the thin film coating, or both. While the applied coating is expected to prevent the moisture and oxygen ingress into the energy harvester hence effectively improve its fatigue life in the harsh environments, it will also add such parameters to the design as the critical permeation thickness and will possibly move the crack initiation location to the bond line between the coating and the substrate. As such, it is important to characterize the fatigue behavior of the microstructures under different loading and environmental conditions. Hence, the investigation of fatigue degradation mechanisms of thin films is linked to the reliability concerns. Particularly, extreme stress gradients and stress ratio can occur for notched and unnotched components in bending mode. The geometry and the presence of extreme stress gradient under different stress amplitude necessitate characterizing the effect of extreme stress gradients and stress ratios on microstructurallysmall crack growth behavior to address the major reliability concerns for the thin film applications. The complex behavior of short cracks is due to less crack closure effects in short cracks as well as the interaction with the surrounding microstructural features in the materials such as grain boundaries, precipitates, inclusions, and phase boundaries. In addition to the experimental studies, finite element analysis has been employed to evaluate thermal stresses and temperature distribution in the coated energy harvesters during the fatigue test. This paper reviews the state-of-the-art in fabrication and characterization in flexible energy harvesters. The aim of this literature survey is to promote creation, development and application of novel experimental approaches to answer major and currently open questions on short fatigue mechanism of microstructural materials and also to provide a deeper understanding of mechanics of coated materials.
Weighted Rail Network Topological Analysis by Waybill Commodity Volumes
Authors: Mao Yujie , Elsibaie Sherief , Ayyub Bilal M. , Elsibaie Magdy , Omar Tarek , McClure Karen
Published: February 2023

This paper examines the topology of railroad networks using weight factors based on network topological attributes, such as commodity volumes transported; therefore, offering additional insights for enhancing freight rail networks and informing planning and operational decisions. The method proposed in this paper uses connectedness efficiency for network performance by considering node and link weights based on origination, termination, and interchange commodity volumes. These volume-based weights are designed to enable mixed units through normalizations. This paper uses freight traffic1 and associated volumes of goods moved as attributes to analyze the topology of an aggregate U.S. national railroad network as a case study. Following the topology of the aggregate network, freight data associated with U. S. counties are assigned to the nearest nodes in the network, and used to calculate node weights. After the assignment of node weights, connectedness efficiency was computed as a primary measure to assess the network for both unweighted and weighted cases with weights node for comparison purposes. It can be used for modeling network resilience at a topological level. In addition, the criticality of nodes and links were assessed reflecting the impact on network efficiency with a single node or single link loss or disability. Quarterly and annual waybill data were examined to assess seasonal changes and influences.
Damage Compensation and Strain Correction in Piezocomposite Laminates
Authors: Conaghan Grant , Payne Nicholas
Published: February 2023

Piezocomposites are composite materials composed of constituents that possess piezoelectric properties, by which an applied electric field induces a mechanical strain in the material. A common form of composite material is a laminated structure composed of numerous layers, or laminae, with embedded reinforcements whose orientation varies from layer to layer to create desired apparent mechanical properties at a larger scale. Composite laminates that are exposed to excessive loading above a critical threshold can experience damage in one or more laminae that will decrease the overall stiffness and load carrying capacity of the structure. In the case of a piezocomposite laminate in a damaged state, the application of electric fields to the laminate as a whole, or on an individual lamina basis, can compensate for the damage sustained and correct both the strain and degraded stiffness to pre-damaged values given the proper choice of electric field function. A methodology for determining the proper field function to compensate for the damage is derived and demonstrated in this paper.

First, piezoelectric homogenized properties at the lamina level are first derived using the Law of Mixtures with micromechanical subregions and shown to share the same form as hygrothermal coefficients. The mechanics of the laminate are treated using Classical Laminate Theory framework where the structure is conceptualized as a thin plate form factor whose deformation is described by a set of midplane strains and midplane curvatures which are uniform over the entire plate and all deformed material coordinates vary linearly through the plate thickness consistent with Kirchhoff-Love plate theory. Then, the method for compensating for the loss in stiffness and increase in strain from the occurrence of damage is established by equating the plate strain tensor in the damaged state with that of an equivalent undamaged state and solving for the necessary applied electric field.

The implications of fabricating a structure with a single field through the entire plate, or discretized into multiple fields with unique values is explored and solutions for each presented.

In the multi-field case, the system of equations has the mathematical property of being under-determined for any system with more than 6 discrete fields, so the least norm solution is employed. Several loading cases are examined, and the damage compensation solution is demonstrated to match the response of an equivalent laminate without damage behavior. The compensation method is agnostic to the type of damage model used on the micromechanical or lamina level and as such is generally applicable to any composite laminate that can be defined within Classical Laminate Theory. This methodology is applicable to devices which must maintain specific mechanical responses and can be applied to the design of active piezocomposite systems that auto-detect and correct for lamina damage.
Heat Transfer Performance Evaluation of PEMFC With Diamond-Shaped Staggered Cooling Channel
Authors: Mughal Pirbux , He Yadong , Luhur Ramzan
Published: February 2023

The fossil fuel depletion and environmental pollution are global challenges. Hydrogen is one of the most abundant elements on earth. Recently, scientists and researchers are investigating water splitting to produce oxy-hydrogen for internal combustion engines. Several studies have been published where hydrogen was used to generate electricity. The proton exchange membrane fuel cell (PEMFC) is an alternative energy resource for future electric vehicles. The reaction of PEMFC includes hydrogen molecules splitting as hydrogen ions and electrons on the anode whereas proton meet with oxygen and electrons and form water and release heat on the cathode. There are several processes involved in heat generation in PEMFC such as resistance in current flow, entropic heat reaction, and irreversibility of the electrochemical reactions. The generated heat in PEMFC is removed through cooling channels. The heat transfer rate depends on thermal properties. The design of the such as polymer electrolyte membrane, catalyst layer, gas diffusion layer, and electrodes have different thermal properties which influence heat transfer. Proper thermal management is critical part of PEMFC operation. Because the efficiency of PEMFC depends on heat loss in-between critical range. In this study, a numerical approach is used to investigate heat transfer performance of a (PEMFC) cooling channel. The heat transfer rate, convective heat transfer coefficient, temperature distribution and pressure drop were evaluated in this work. All these results were carried out on, 0.2, 0.4, 0.6 0.8 and 1 kg/s of mass flow rate of coolant in the PEMFC cooling channel. Ansys Fluent is used for the numerical investigation. The diamond shape extended staggered pattern cooling channel were used in fuel cell for distributed flow. In this study, 2mm transverse pitch whereas 1mm, 1.5 mm and 2 mm longitudinal pitch with diamond shape extended in PEMFC cooling channel are used. However, design of experiments method was used to sort optimum results. The results reveal the extended staggered cooling channel improve heat transfer performance, 2mm and 1.5 mm transverse and longitudinal pitch respectively gave better heat transfer results and slightly higher pressure drops than 2mm pitch. Turbulence kinetic increases with decreasing transverse pitch and flow distribution improved with longitudinal pitch.
A Sustainable Approach to Designing a Bird Wing Prosthesis
Authors: Mukhamedjanova Aleese , Lundemo Trinity , Shady Sally
Published: February 2023

Raptors are some of the most threatened birds around the globe, with 18% of raptor species being in danger of extinction and 52% with declining populations. Many birds that are brought into rescue centers with a complicated wing injury must be euthanized. In very rare cases, such birds may alternatively have their wing amputated, often leaving them grounded and unbalanced. Many raptors are endangered, and as predators at the top of their food chains, the loss of these birds from the ecosystem leads to severe environmental upheavals that can affect the daily lives of people. Thus, euthanasia and rehabilitation are not sustainable solutions with regards to raptors with broken wings. Alternatively, this study proposes a transhumeral prosthetic wing that can allow amputee raptors to potentially fly again. A series of biomechanical analyses were performed along with a material analysis to create a three-dimensional model of a prosthetic wing. An analysis of forces and flapping gait during flight was conducted, which, to our knowledge, has not previously been done. Environmentally friendly polymers that consist of PLA and beta-keratin were assessed to determine feasibility in a wing prosthesis. A finite element analysis (FEA) was performed and revealed that the sustainable PLA and beta-keratin material has sufficient mechanical properties to withstand the kinetics of extended flight, improving the model’s structural integrity.
Performance Characteristics of PMDC Motor of Small-Scale Experimental Ocean Current Turbine
Authors: Rouhi Shahab , Xiros Nikolaos , Aktosun Erdem , VanZwieten James , Sultan Cornel , Ioup Juliette , Sadeqi Setare
Published: February 2023

A comprehensive numerical model was developed to address the performance of a permanent magnet direct current (PMDC) motor which is employed as a small-scale three-bladed horizontal axis ocean current turbine. This numerical model development is presented along with a comparison to experimental data to quantify the motor performance. The proposed experimental design is discussed in detail. Due to the nature of the ocean current turbine, it is required to run it first by applying input power, subsequently to be governed by hydrokinetic energy. Thus, a detailed performance of the PMDC motor is essential when it runs as a motor and generator. Based on our preliminary work, the angular speed of the small-scale turbine is less than 500 rpm. Thus, a combination of the PMDC motor and a planetary gearhead is used to fulfill this low-speed requirement. The gearhead is driven in reverse when operating as a generator which leads to poor efficiency. This efficiency is experimentally derived to be 47.8% at maximum speed of 479.4 rpm at 12V.
Benchmark Study of XFTA and SCRAM Fault Tree Solvers Using Synthetically Generated Fault Trees Models
Authors: Aras Egemen M. , Farag Asmaa S. , Earthperson Arjun , Diaconeasa Mihai A.
Published: February 2023

The development of the nuclear industry’s Probabilistic Risk Assessment (PRA) has significantly contributed to the design, reliability, and safety of nuclear power plants (NPP). Today, PRAs form integration in all nuclear power plant development stages, including design, licensing, operation, maintenance, and decommissioning. Many legacy PRA tools have been used in the nuclear field; however, more powerful tools are needed to cope with the rapid development of the nuclear industry and NPP designs. These tools are now required to analyze new aspects of the plants that were never envisioned before, and more computational resources are needed.

This study uses synthetically generated fault trees of various sizes and specifications to benchmark fault tree solvers; XFTA version 1.3.1 and SCRAM version 0.16.2. The analysis is performed in two steps. The first step is to compare the probabilities, minimal cut sets, and importance factors. The second step is measuring CPU time, wall time, and the memory usage of each engine for benchmarking. The result for the first step for the same configuration is the same for each calculation engine. Overall, XFTA can complete most of the given runs in a shorter time with less memory usage than SCRAM. All computations and measurements are done on a specified computer.
Finite Element Simulation and Analysis of Drop Tests to Improve the Mechanical Design of a Handheld QSTM Medical Device
Authors: Bhattacharjee Abhinaba , Loghmani Terry , Anwar Sohel
Published: February 2023

The structural integrity of an electro-mechanical assembly significantly determines the robustness of the design and durability of a product. Handheld portable medical devices require more attention on their compactness and packaging to ensure design fidelity for manufacturing and avoid permanent damages during inevitable drops or rough handling in a clinical setup. Hence, a finite element analysis is performed for quality conservation, risk assessment, and design failure mode error analysis. This paper investigates the mechanical impacts of drop tests on a handheld portable mechatronic medical device used to quantify real-time dispersive force-motion patterns in the form of Quantifiable Soft Tissue Manipulation (QSTM) for therapeutic massage, clinical manual therapy, and pain level assessments against neuro-musculoskeletal conditions. Structural analysis of the handheld medical device’s mechanical design and assembly has been performed by finite element methods to identify parts of assembly susceptible to maximum stress and deformation during static impact loading and impacts of collisions at drop test simulations. The CAD model of the medical device is illustrated and evaluated with material modeling and structural analysis to distinguish weaker supports and further reinforce them with modified design iterations. This analysis enabled a revised design of the QSTM device which showed significant reduction in stresses and deformations as compared to the baseline design.
Electrical Characteristics of the Oxyfuel Preheat Flame: 3D Computational Model Subject to Electric Bias Voltages
Authors: Rahman S. M. Mahbobur , Warrier Rohith , Untaroiu Alexandrina , Martin Christopher R.
Published: February 2023

A three-dimensional (3D) computational model is presented in this paper that illustrates the detailed electrical characteristics, and the current-voltage (i-v) relationship throughout the preheating process of premixed methane-oxygen oxyfuel cutting flame subject to electric bias voltages. As such, the equations describing combustion, electrochemical transport for charged species, and potential are solved through a commercially available finite-volume Computational Fluid Dynamics (CFD) code. The reactions of the methane-oxygen (CH4 – O2) flame were combined with a reduced mechanism, and additional ionization reactions that generate three chemi-ions, H3O+, HCO+, and e−, to describe the chemistry of ions in flames. The electrical characteristics such as ion migrations and ion distributions are investigated for a range of electric potential, V ∈ [−5V, +5V]. Since the physical flame is comprised of twelve Bunsen-like conical flame, inclusion of the third dimension imparts the resolution of fluid mechanics and the interaction among the individual cones. It was concluded that charged ‘sheaths’ are formed at both torch and workpiece surfaces, subsequently forming three distinct regimes in the i-v relationship. The i-v characteristics obtained out of the current study have been compared to the previous experimental and two-dimensional (2D) computational model for premixed flame. In this way, the overall model generates a better understanding of the physical behavior of the oxyfuel cutting flames, along with a more validated i-v characteristics. Such understanding might provide critical information towards achieving an autonomous oxyfuel cutting process.
Impact of the Tip Clearance and the Inflow Nozzle Shape on the Performance of Low-Pressure Axial Fans
Authors: Fritsche Manuel , Epple Philipp , Delgado Antonio
Published: February 2023

Low-pressure axial fans have a very wide range of applications in the field of heating, ventilation and air conditioning as well as refrigeration (HVAC&R). Due to stricter legal requirements, increasingly higher fan efficiencies are required. Due to legal regulations, more efficient machines are becoming increasingly important. A small gap, the so-called tip clearance, is necessary between the rotating impeller and the stationary shroud due to manufacturing tolerances and structural-mechanical expansion as well as thermal expansion. However, this tip clearance has a strong impact on the performance of the fan. Due to the gap between the blade tip and the shroud wall, a circulation volume flow rate occurs depending on the operating point. This can have a strong influence on the inflow condition, for instance a standing vortex can develop at lower volume flow rates in front of the impeller at the tip region. Overall, this affects the operating behavior and the performance characteristics, i.e. the integral pressure characteristics as well as the efficiency characteristics. In the present investigation, an axial impeller was designed and optimized for this purpose. The impeller blades were designed as flat sheet metal blades with a constant thickness. This axial impeller was modeled with ANSYS Blade Modeler and simulated with the commercial CFD solver ANSYS CFX.

In the first simulation study, the tip clearance was varied and analyzed. As a reference case the impeller was simulated also with no gap. Since the tip clearance effectively makes the blade shorter, the influence of the shortened blades was compensated considering the similarity theory of fans. Second, the shape of the inflow nozzle, i.e. the radius and the length, was varied, simulated and evaluated.

In order to determine the influence of the tip clearance and the shape of the inflow nozzle, the integral characteristics such as the pressure characteristic and the efficiency characteristic were compared. In addition, the flow field around the blade tip as well as in the inflow nozzle were analyzed and areas of flow detachment were evaluated. For the inflow nozzle the meridian and circumferential velocity was evaluated and compared in different sections in the inflow nozzle. Finally, the study showed that for the present application of the low-pressure axial fan, the tip clearance has a significant impact on the performance of the fan. An optimal compromise between manufacturing costs and acceptable losses due to tip clearance was sought. The method and the results are presented and discussed in detail.
Reliability and Safety Assessment of Passive Safety Systems Through Coupling of Fault Tree Analysis and Artificial Neural Network
Authors: Khosravi Babadi Parham , Lu Lixuan
Published: February 2023

Small Modular Reactors (SMRs) have attracted much attention in recent years, and they could play a significant role in the future of energy supply and the nuclear industry. Many factors have contributed to the advancement of SMRs, including their affordability and zero greenhouse gas emissions. However, the most significant advantage associated with SMRs is their increased safety level, which has been achieved by introducing a wide range of new design features. Despite the diversity of design techniques, a similar set of design principles, such as Passive Safety Systems (PSSs), has been adopted to improve plant safety and robustness, eliminate design vulnerabilities, minimize accident likelihood, and mitigate accident effects. Reliability and safety evaluation of PSSs are crucial from the design phase to achieve these objectives. Probabilistic Safety Assessment (PSA) is a well-known methodology for analyzing risk levels associated with safety-critical systems in many industries, such as the aerospace, oil and gas, and nuclear industries. Probabilistic safety assessment utilizes the combination of Event Tree (ET) and Fault Tree (FT) techniques to estimate risks associated with certain undesired top events, such as core meltdown in the nuclear industry. Although PSA offers a range of advantages for safety assessment compared with traditional deterministic risk analysis technology, it also has some limitations. There are still many challenges associated with dynamic PSA analysis due to the demand for computational power for oversized FTs and ETs. Moreover, the final assessment result is prone to a significant uncertainty level due to human-related errors.

Some of the challenges associated with PSA might be alleviated by Artificial Neural Networks (ANNs), as ANNs address the limitations of PSA, such as adaptive capacity, learning ability, and real-time calculation, which are challenging for dynamic process systems. Apart from ANNs, Bayesian Networks (BNs) are used to establish the collection of stochastic processes and their conditional dependencies through graphical connections. Bayesian Network is a graph layout that models accident scenarios and various real-world problems. This paper investigates the application of artificial intelligence (Deep Learning (DL)) to enhance FT analysis through the conversion of FT and ANN models.

The potentiality of extending this technique to analyze the reliability and safety of PSSs in SMRs is examined. In SMRs, natural circulation has a low driving force, and PSSs are easily manipulated by system variables such as heat loss, flow friction, and oxidation, leading to system instability and jeopardizing the system’s safety. As a result, FT analysis is inadequate to capture these effects in real-time to analyze the reliability and safety of PSSs. This paper demonstrates that the introduction of ANN could help address some of these limitations.
Cellular Lattices With Struts and Plates
Authors: D’Souza Nandika Anne , Ghosh Mahan
Published: February 2023

Lightweighting through the creation of porous architectures has been employed extensively in materials such as foams and aerogels. The use of two-dimensional columnar systems such as honeycombs and their related polygons have been employed due to the ease of manufacturing using large scale calendaring. More recently the availability of 3d printing led to a resurgence of cellular architectures that are based on struts. Systems have been explored using atomic lattice mimicry and named as face centered cubic, body centered cubic or simple cubic. The utilization of faces has also been explored paired to the struts. In this paper we explore the effect of gradual face insertion into a body centered cubic lattice. We examine a single cell oriented such as that the faces are arranged around the centroid of the cube. A 4 × 4 × 4 lattice is then explored to examine stress transfer to the nearest neighbor. The results present a novel approach to mitigating the challenge with stress concentration that has limited the strut-based lattices in Fused Deposition Modeling (FDM) printing as all systems with faces show significant benefits in modulus, stress and energy absorption enhancement over the pure strut-based lattice.
Compostable, Full Biobased Foams Using Environmentally Benign Manufacturing
Authors: Oluwabunmi Kayode , D’Souza Nandika Anne , Zhao Weihuan
Published: February 2023

With initiatives on carbon capture utilization, use of CO2 in the manufacture of foamed polymers is valuable. The low solubility and strong temperature/pressure correlation to utilization remains a limit. Here we explore two aspects of green manufacturing. Use of a biopolymer and CO2 to foam it. Microcellular foams were produced from amorphous polylactic acid (PLA) with 12% d-lactide content using the batch foaming method. The batch method produces foams that are affected by cell nucleation, growth and solidification. In the thermal soak method, CO2 was introduced into PLA above its Tg, depressurized resulting in solidification, followed by soaking in a hot water bath for trapped CO2 to be released. In a second method, CO2 injected above the Tg was held at a temperature above ambient to encourage cell growth followed by a quench. The results showed that foams made through the decompression technique at foaming temperature of 55 °C were rigid in nature and had a better mix of cellular architecture due to their well-defined bimodal cellular structure compared to the foams made at foaming temperature of 75° C. Excellent mechanical and good sound absorption properties were attributed to the bimodal distr. Thermal conductivity values of (0.031–0.063) W/mK obtained for the PLA foams made using the thermal soak and decompression techniques was equivalent to that of petroleum based extruded polystyrene (EPS) and expanded polystyrene (XPS) foams ∼ (0.03–0.06) W/mK valuable for building insulation.