bluuebunny/crossref_metadata_2025 huggingface dataset:
Constitutive Modeling of the Cross-Linked Polymers During the Trio-Aging Mechanism: Effects of Water, Oxygen, UV
Authors: Bahrololoumi Amir , Shaafaey Mamoon , Dargazany Roozbeh
Published: February 2023

The synergized effects of diverse environmental conditions such as humidity, temperature, UV, and oxygen, are considered through a generic model by combining the concepts of network alteration, hygrothermal, and Photo-thermo oxidation Models [1–4]. Hygrothermal and Photo-oxidation are considered dual aging mechanisms which are due to the synergized effects of moisture-oxygen, and UV-oxygen, respectively at elevated temperatures. Here Trio-aging is considered as the synergized effects of Hygrothermal, and Photo-oxidation which the main environmental elements involved in polymer degradation are oxygen, water, and UV radiation where each of which has a different micro-structural impact on the polymer matrix. While oxygen imposes chain scission and cross-link formation, water, and UV radiation mainly cause chain scission. Similar to our recent models, the dual network hypothesis of Topolosky is utilized and as a result, the strain energy of the polymer matrix is written in terms of two states namely unaged and infinity. The infinity state network, itself, is decomposed into three networks, namely brittle, flexible, and dead networks. While the brittle network models the cross-link formation as sub-structural phenomena, the flexible and dead networks are utilized to represent the cross-link reduction and chain scission. The contribution of these networks in the infinity state is based on the amount of relevant environmental elements. The model is developed for a domain with plenty of oxygen and holds true for a gradual aging process that happens in super-thin samples.
Investigation of Emission Reduction and Power Generation on Electrochemical Catalytic Membranes With the Addition of Perovskite Nanocrystals
Authors: Willsey Aliza M. , Fields Kassidy , Welles Thomas S. , Lin Hanjie , Zheng Weiwei , Ahn Jeongmin
Published: February 2023

With the depletion of fossil fuel resources, as well as increasing global temperatures, the interest in sustainable energy is on the rise. Currently, cars are a significant source of harmful emissions due to the use of internal combustion engines. Incomplete combustion byproducts are extremely harmful to the environment and the population, with links to acid rain, smog, and respiratory issues. While green energy solutions, such as electric vehicles, are being developed, the treatment of exhaust can also be an effective way to reduce the release of emissions into the atmosphere. It has been shown that a solid oxide fuel cell (SOFC) is able to break down emissions, even exceeding the capability of typical exhaust treatment methods. An investigation into the usage of an SOFC as an exhaust treatment material has found that the amplification of a signal generated across the cell has an even greater effect on emission reduction.

Here, the addition of cesium lead bromide (CsPbBr3) nanocrystals to the fuel cell is being investigated. The SOFC is tested as an exhaust treatment solution and as a power generation device in comparison to a typical SOFC without added CsPbBr3 nanocrystals. CsPbBr3 is a perovskite semiconductor, so it is expected to have an effect on the reactivity of the fuel cell. Investigating the effects of adding nanocrystals into a SOFC will lead to advancements in exhaust treatment systems as well as power generation systems. The work here will show a direct relationship between the quantity of nanocrystals contained in the SOFC to the emission reduction and power generation abilities of the SOFC.
Investigating the Effects of Solvents and Nanocomposites on Tailoring the Elastic Modulus of Piezoelectric Thin Film PVDF-TrFE
Authors: Kunwar Deepak , Hassan Md Mehadi , Jackson Nathan
Published: February 2023

Polyvinylidene Fluoride (PVDF) and its co-polymer derivatives have been extensively investigated as a thin film piezoelectric material due to its flexibility, which is desired for flexible sensors, wearable devices, tactile sensors, and low-frequency energy harvesters. Researchers are interested to enhance the piezoelectric response as well as the mechanical properties of PVDF and its co-polymer to enhance device performance. This work primarily investigates the solvents used to synthesize the polymer and their effect on the mechanical properties (hardness and elastic modulus) of thin-film co-polymer polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE). Various solvents with varying physicochemical properties were screened for the dissolution of PVDF-TrFE polymer to investigate the effect of solvents to tailor the key properties of the solvents that influences hardness, Young’s Modulus, flexibility, and the piezoelectric response. The hardness of the thin films was also affected by the addition of various nanocomposites. Hence, the hardness and the Young’s Modulus of the thin films with different solvents and ZnO nanocomposite particles was determined via nanoindentation. The thin films were characterized via X-ray diffraction (XRD), and quasi-static piezometer measurements and the thickness of the thin film was determined by a profilometer. The crystallinity of the thin films was enhanced via annealing at 125°C leading to a higher piezoelectric constant. This paper reports that the hardness and the Young’s Modulus of the thin films are highly dependent on the solvent’s physicochemical properties, dipole moment, and the nanocomposite concentration. Our observation revealed that the solvent with the highest dipole moment (HMPA) inherits the highest piezoelectric coefficient. This study demonstrates how manufacturing methods can affect the film’s mechanical and piezoelectric properties which are useful for researchers using PVDF in MEMS devices in the future.
Effect of Ageing and Environmental Conditions on Mechanical Properties of 3D Printed Parts
Authors: Lapuz Oginne Rashid , Vasilyan Hayk , Atatreh Saleh Ghalib , Alyammahi Mozah , Al Mheiri Ahmad Abdulla , Susantyoko Rahmat Agung
Published: February 2023

3D printing technology is often the go-to solution for rapid-prototyping thermoplastics. Parts can be created in record time with regards to the initial investment compared to the resources required in traditional fabrication methods such as injection molding. This has started a wave of manufacturers that are looking to scale their production with the use of 3D printing technology, as the parts have similar properties to their injection-molded counterparts.

As the advancement of 3D printing continues, to our knowledge, no studies have been conducted regarding the performance change of the part versus the use in inert-gas and vacuum antechamber environments. This study aims to demonstrate the effects of room, antechamber, dryer, and inert-gas environments with respect to the mechanical properties of 3D printed fused filament fabrication thermoplastics over time.

From the variation of the results that have been noticed on samples that were printed, the parts should not be utilized immediately, but rather they must be stored in a stable environment until the material properties are fully optimized. This would enable the designer to consider a risk factor to be applied that would account for expected changes in mechanical properties according to the environmental conditions for the intended application.
A Molecular Dynamics Study on the Piezoelectric Properties of Bulk ZnS and Nanobelts
Authors: Hijazi Iyad , Xie Rui , Houachissi Regis
Published: February 2023

A number of researchers have developed interatomic potentials for ZnS. The choice and reliability of a particular empirical ZnS potential is highly dependent on the application that the molecular mechanic simulation aims for, and therefore each of these potentials is designed to reproduce some specific ZnS properties. Therefore, in this work we proved the feasibility of using classical atomic simulations, namely molecular dynamics and molecular statics, to study the piezoelectric properties of bulk and nanobelts ZnS structures, by utilizing the core-shell atomic potential model. After conducting MD simulations of bulk and nanobelts ZnO piezoelectric constants, utilizing reliable ZnO core-shell potentials, we report the bulk ZnS piezoelectric constants calculated using three different classical interatomic core-shell ZnS potentials; the Wright and Jackson (1995) potential, the Wright and Gale (2004) potential, and the Namsani et al. (2015) potential. The simulation results showed that the Wright and Gale (2004) ZnS potential, which includes a four-body bonded term, is the most reliable potential to be used for large-scale atomic simulation of piezoelectric response of the bulk ZnS structures. Utilizing the Wright and Gale (2004) potential, we further studied the effect of size scale effect on the piezoelectric response of ZnS nanobelts by conduction molecular dynamics simulations for six ZnS nanobelts with length of 91.75 Å and transverse size of 22.94–42.06 Å. The results showed that, as with the ZnO nanobelts, the change of piezoelectric constant decreased with the increase of the size of the ZnS nanobelts structures.
Is the Blood Flow Laminar or Turbulent at Stenosed Coronary Artery?
Authors: Albadawi Muhamed , Abuouf Yasser , Elsagheer Samir , Sekiguchi Hidetoshi , Ookawara Shinichi , Ahmed Mahmoud
Published: February 2023

Coronary artery disease (CAD) is the abnormal contraction of heart supply blood vessel. This contraction in the blood vessels limits the flow of oxygenated blood to the heart. Thus, diagnosing its severity helps physicians to select the appropriate treatment plan. Most of the commonly diagnostic methods are qualitative. They depend on the physicians’ experience and judgement to specify the severity of the stenoses. Fractional flow reserve is one of the quantitative diagnostic tools used while coronary catheterization is being performed. Fractional flow reserve measures the pressure gradient from the proximal to the distal sides of a coronary artery stenosis; this helps in deciding whether the stenosis limits the oxygenated blood flow. Resent models of vascular hemodynamics consider physiologic blood flow to be laminar. Transition to turbulence is considered as a driving factor for numerous diseases such as stenosis and aneurysm. As the value of Reynolds number does not exceed 2000, the flow is laminar. Several researchers stated that the flow might be turbulent at critical Reynolds number value less than 2000.

Hence, the aim of this study is to investigate the most accurate turbulence flow model compared to the available experimental data. It is important to replicate the experimental model. Accordingly, the same non-Newtonian blood flow model and pulsatile flow boundary conditions were used. The stenosed simple geometry with a centered fractional flow reserve guidewire is constructed based on the same dimensions of the experimental setup. The numerical models were simulated with laminar flow and K-ε, and large eddy simulation (LES) turbulence modelling. The predicted results are compared with the actual available experimental measurements to investigate the most accurate numerical model of the blood flow in the stenosed coronary artery.

Based on the predicted results, pressure drop coefficient (CDP), Pressure recovery coefficient (CPR), and the pressure recovery factor η are investigated in the coronary stenosis with and without fractional flow reserve guidewire. For the severe 89% stenosis, it was found that the error in CDP before and during the guidewire insertion is small. The error in CDP before inserting the guidewire reached −7%, −7%, and −12% for laminar, turbulent K-ε, and LES models, respectively and −11%, −11%, and −4% for laminar, turbulent K-ε, and LES models, respectively during inserting the guidewire. Accordingly, it can be concluded that the laminar and LES modelling represent better performance in simulating the blood flow rather than the turbulence model.
Engagement State Definition and Detection in Education: A Review
Authors: Bocanumenth Aurora , Rendón-Vélez Elizabeth
Published: February 2023

Students’ level of positive learning-centered affective states, like engagement or flow state, has been proved to be strongly related to dropouts’ prevention, higher learning rate, and better student performance in their courses. Measuring users’ engagement state in a more effective and user-independent way may help create a better design of interactive applications and develop intelligent, more sophisticated, and adaptative study environments. The engagement reviews found in the literature go through psychological definitions but do not go deeper into the physiological and behavioral indicators of the state.

This review aims to analyze the current state of the art on engagement detection, to identify which are some of the most relevant physiological and behavioral indicators for engagement in students for its prediction during presential or online courses. A computer-aided systematic literature search was performed following the PRISMA methodology. A total of 24 articles were selected after removing duplicates and applying the selection criteria. These studies were analyzed to extract data relative to the physiological behavioral indicators, the classifier used, its’ accuracy, and the number of participants.

Indicators, such as leaning forward or backward and parasympathetic activation (such as HR, HRV, and GSR) have proven to be strongly related to students’ engagement states. The multimodal channel systems have been proven to have better performance, but the question of the best channel combination is still on the table. Different classification methods (SVM, RF, NB) have achieved high accuracy performance in experimental setups, but there are still challenges for real-life setups detection systems.
A Probabilistic Analysis in Vibration-Assisted Drilling to Measure Dynamic Behavior During Drilling and Understand Risk Factors
Authors: Marquez Eleazar , Garcia Samuel
Published: February 2023

In this paper, a mathematical representation is proposed to further understand the dynamic behavior and risk factors associated with vibration-assisted drilling (VAD) technology. The proposed Timoshenko beam model, which characterizes VAD technology, consists of two passive, counter-rotating coaxial rotors operating simultaneously, subjected to a stochastic excitation. In this regard, a finite element technique was incorporated to determine the physical parameters of the governing equation of motion, where the shear and rotary effects, as well as the gyroscopic couples generated perpendicular to the axis of rotation, were accounted for. Further, the relative velocity between the coaxial rotors was accounted in the equation of motion, which induced a modification on the stiffness and damping parameters. A fourth-order Runge-Kutta method was utilized to estimate the response and power spectra for soft and compact formations. Results indicated that resonance conditions due to gyroscopic effects manifest at soft and compact formations during drilling, however, at soft formations, the natural frequencies separated at lower RPMs, while at compact formations, higher RPMs were required to induce instabilities.
Optimizing the Curriculum in a Heating Ventilation and Air Conditioning Class With Realistic Labs, Projects and Interesting Realistic Problems to Enhance Learning
Authors: Larsen Kyle , Gharavi Hessam , Gerlick Robert , Michaelis Matthew
Published: February 2023

The primary purpose of a Heating Ventilation and Air Conditioning (HVAC) course is to provide the details and principles necessary to design a HVAC system. This encompasses the study of the many aspects of the various heating and air conditioning systems such as the moist air properties and conditioning processes, the comfort and health concerns, the cooling and heating loads and the system design including duct sizing, equipment and controls selection. This also includes the learning and using of software such as Trane Trace or Carrier HARP to calculate the heating and cooling loads for a commercial building and applying the applicable American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) standards. It is important to develop a method of dissecting a project to its essentials and solving it in a logical, organized manner. In our institution, we offer a one-quarter long HVAC class for the Mechanical Engineering and Mechanical Engineering Technology students. This is a comprehensive course which teaches our students the various aspects and topics of HVAC along with completing several realistic projects to help the students to learn real world applications of the design. This includes using the blueprints of a commercial building to design a HVAC system. Also included are labs, field trips, and guest speakers to help our students learn even more about HVAC. It is hoped that, after taking this course, students, if they choose, will be well prepared for a HVAC career. This paper will discuss and explore the many ways in which a HVAC class should be taught in order to make it a successful class. This includes teaching the basic principles and applying it to several real-world projects. One of the projects we have our students do at our university is to calculate the heating and cooling loads of a car dealer’s building which consists of an upstairs a front lobby, offices, kitchen, restrooms, and several car bays and to then recommend the equipment and controls necessary for the design. We also have the students complete a separate duct sizing project using both the equal friction and equal velocity methods. Further, we have several labs, including a refrigeration lab, calculating the coefficient of performances (COP) for various operating conditions. In addition, we explore alternate methods of energy savings such as ground source heat pumps, evaporative cooling combined with vapor compression refrigeration etc. Included in this course we have at least one guest speaker from ASHRAE as well as other professionals in the field. We also have our students visit our own universities’ steam and chilled water plant used for our heating and air conditioning as well as other relevant field trips.
A Novel Discrete, Mesoscale Modeling Framework for the Simulation of the Damaging and Fracturing Behavior of Composites
Authors: Salviato Marco , Phenisee Sean , Deleo Antonio , Pelessone Daniele , Flores Mark
Published: February 2023

A novel, discrete approach for the modeling of fiber reinforced composite materials which explicitly models the complex mesostructure is introduced. Fibers and fiber tows are represented as Timoshenko beam elements, and the mechanical behavior of the matrix is defined by vectorial constitutive laws expressed on facets obtained from the tessellation process in a tetrahedral mesh. For the mesoscale model generation, a computationally efficient, robust, and highly parallelized scheme is presented which is capable of generating laminates with fiber volume fractions higher than 60%.

Thanks to the explicit description, the constitutive laws of each constituent materials do not require complex mathematical equations and are physics-based with clearly defined material parameters.

To demonstrate the predictive capability of the model, uniaxial experiments are simulated for IM7/977-3 utilizing the novel framework. The investigated loading conditions include longitudinal tension/compression and transverse tension/compression. It is shown that the model is capable of capturing the strength of IM7/977-3 in both longitudinal and transverse directions. The damage mechanisms such as shear band formation and fiber micro-buckling are captured with the model using physics-based and clearly defined material parameters, thanks to the explicit description of fibers and matrix.
Joint Control With Passive Damping for a Planar Two-Link Tendon-Driven Flexible Manipulator
Authors: Ezeanya Emeka K. , Barhorst Alan A.
Published: February 2023

Flexibility and compliance are intrinsic qualities of continuum (soft) robots which make them desirable and extend their applicability beyond the level readily obtainable in the traditional rigid link robots. Thus, continuum robots can be used in manipulation, exploration, inspection, and surveillance tasks, in minimally invasive surgery (MIS) applications, and robotic rehabilitation devices. Unfortunately, the desirable qualities of these robotic systems lead to nonlinearities and complex deformations which must be clearly understood to develop a good model. At present, various modeling methods exist. However, this research employs a uniquely different approach based on the Hybrid Parameter Multiple Body Systems (HPMBS) methodology for the dynamic modeling and control of a two-link tendon-driven flexible manipulator. Owing to the benefits offered by this modeling approach, a high accurate, low order model for the complex deformations of the flexible manipulator system will be developed. Model simulations demonstrating joint position control with passive damping will be presented, whereby the manipulator can be accurately moved to various joint positions, with vibrations completely suppressed. As a result, the accurate, low order model could facilitate real time dynamic simulations and controls as may be required for various soft robotic applications.
Assembly for Enhanced Repeatability Under Planar Constraints
Authors: Bordoloi Jishnu , Khatait Jitendra P. , Mukherjee Sudipto
Published: February 2023

In dies used to cure preformed material, the top die is actuated to significant force levels. To ensure repeatability, three external V-grooves are used to guide so that the two halves are located accurately in the plane perpendicular to the designed approach direction. The kinematics of this assembly process is revealed by analysis. Infinitesimal screw theory describing the instantaneous motion, or the velocity and the corresponding reciprocal space, that of the possible force system are used to characterize the motion of the top die. Dynamic simulation with force input equations governing the local trajectory of the top die as it progressively engages with the grooves is established. We record the excursion of the top die in the plane normal to the nominal approach direction to characterize the motion. The two die halves mating before the V-grooves form line contacts is seen to be a necessary condition for self-alignment. We show that on reassembly from randomly perturbed initial conditions, only on specific design of the V groove system, the CG is moved towards a fixed position by the nesting force.
An Analytical Vehicle Kano Model Development Integrating With QFD and TRIZ Methods
Authors: Liu Chang , Chen Jiaquan , Chang Yin-ping
Published: February 2023

The rapid development of science and technology has resulted in ever-shortening product development cycle and varies customers’ wants and needs tremendously. To keep the pace of market developments and customers’ needs, a shorter product developing process and cycle is necessary. During the process of engineering design and development, there is always a gap between customers and engineers.

This research creates a new Customer to Engineering (C2E) system by integrating the Kano model, QFD and S-Curve in TRIZ method. The C2E system is the bridge to close the gap between the customers and engineers by constructing an engineering design chain from customers’ voices all the way to the engineering system. In this paper, an optimized analytical Kano model is developed, and a new classification method is conducted. Based on the classification and balance model of vehicle performance indices, two new parameters, Kano Classification Coefficient and Customer Perception Factor are introduced. Then the Relative Important Degree and the Ultimate Customer Perception Factor are derived with the concept of QFD to further optimize Kano model and digitalize HoQ (House of Quality) diagram with geometric progression for further analyses. The corresponding relationship between Kano model and S-Curve is introduced to identify the development stage of the engineering system for the first time. Once the stage is identified, further design modifications can be applied to the engineering system according to the S-Curve analyses.
Effect of Number of Contact Points on the Fretting Wear Estimation of a Frictionally Damped Blade Platform
Authors: Cardak Aykut , Cigeroglu Ender
Published: February 2023

Frictional interfaces, which induce energy dissipation in the system, are intentionally included in bladed disk system of gas turbine engines. By this way, resonant amplitude of the blade is decreased while high cycle fatigue failure of these structures is postponed. Mathematical modeling of the problem becomes complicated due to the nonlinear nature of the frictional contact which also adds difficulty to the solution of the problem. Time domain solution methods are expensive compared to frequency domain method for the determination of steady state response of nonlinear systems. Therefore, Harmonic Balance Method (HBM) is employed to constitute the set of algebraic equations to be solved numerically. Alternating Frequency Time (AFT) Method is utilized to find the Fourier coefficients of the friction force in an iterative way. In addition, analytical Jacobian formulation is implemented to the friction model to enhance the solution performance. Although various friction dampers have been designed, mathematically modeled, and discussed before, fretting wear which is the inevitable outcome of the dry friction is underemphasized up until today. In this work, a blade platform system which represents a simplified underplatform damper is studied to investigate the effect of number of macroslip friction elements on wear estimation and the effect of wear on the dynamic response of the system.
Optimal Design of Integrated Solar Combined Cycle and Desalination Systems
Authors: Pietrasanta Ariana M. , Mussati Sergio F. , Aguirre Pio A. , Morosuk Tatiana , Mussati Miguel C.
Published: February 2023

This paper addresses the optimization of dual-purpose desalination plants (DPDPs) for simultaneous generation of electricity and fresh water. The optimization problem is finding the optimal design and operating conditions to meet desired electricity generation and freshwater amount at a minimal total annual cost. The multi-effect distillation (MED) desalination and/or reverse osmosis (RO) processes are the candidates to produce the required freshwater production. Thus, the selection of the desalination process represents a model decision. First, a conventional DPDP is defined and used as the base case. Then, upgrading the optimized conventional DPDP (base case) is investigated by adding a solar collector and keeping unchanged the sizes of the process units of the optimized DPDP. The optimal process configuration is selected from different candidate configurations. For instance, (a) one solar collector/combined cycle/MED; and (b) one or two solar collectors/combined cycle/MED/RO.

Two new optimization problems are solved: (a) the optimization of the operating conditions of the entire process to maximize the electricity generation keeping the same fuel consumption, and (b) the optimization of the operating conditions of the entire process to minimize the fuel consumption keeping the same electricity generation.

By keeping the same process units obtained for the optimized conventional DPDP and by adding a solar collector, the electricity generation can be increased up to 5.62 MW, and the fuel consumption can be reduced by 2310 ton/yr and thereby 6352 CO2 ton/year.
Potentials and Limitations of Concentrator Silicon Solar Cells Energy Utilization
Authors: Elsabahy Mohamed M. , Emam Mohamed , Sekiguchi Hidetoshi , Ahmed Mahmoud
Published: February 2023

The maximum allowable concentration ratio of the silicon-based solar cells and their potential for thermal utilization applications are investigated. A three-dimensional thermal-fluid model is developed for silicon-based concentrator photovoltaics integrated with a generic heat sink. The generic heat sink is characterized by the heat transfer coefficient, resembling different scenarios of thermal management, and the heat sink temperature to reveal the potential of the CPV to provide high exergetic thermal energy. Under each combination, a wide range of concentration ratios are tested to obtain the performance characteristic maps of the solar cell, which assure the safe operation of the cell under 85°C (as recommended by manufacturers). The highest concentration ratio for the presented cell is ∼25 when the intensive cooling is applied at a heat transfer coefficient ranging from 104 – 105W/m2K under average heat sink temperature (i.e., 31°C) near the ambient one (i.e., 30°C). In addition, raising the heat sink temperature (e.g., 50°C) for thermal utilization reduces the maximum allowable concentration ratio (e.g., ∼17). Although the thermal utilization intuitively holds a higher potential at a high concentration ratio, the reverse is recommended for the solar cell when the safe operation is considered. This is attributed to the necessity of sufficiently reducing the temperature of the heat sink to draw the massive heat flux at a high concentration through the predefined solar cell thermal resistance. Consequently, low-quality thermal energy is extracted as indicated by thermal exergy efficiency. To conclude, if the objective of the CPV system is only power, working at a high concentration is recommended with a heat sink having a high heat transfer coefficient and working at a temperature nearly equal to the ambient temperature. On the other hand, if combined heat and power are intended, increasing the heat sink temperature to the target application is obtained at the cost of reducing the maximum allowable concentration ratio.
Introduction to Composite Materials in a Finite Element Method Course
Authors: Monterrubio Luis E.
Published: February 2023

The motivation of the work presented here is to include hands-on labs relevant to a finite element method (FEM) course. Hands-on laboratories are highly encouraged by ABET and results and surveys show that these types of labs help keeping students engage in this course.

Theory of composite materials is presented to students including an introduction to types of composite materials; a review of stress-strain relationships of isotropic, orthotropic, and transverse isotropic materials; elastic constants, stiffness and compliance matrices, manufacturing processes and models to determine mechanical properties of laminated structures, such as the rule of mixtures (ROM) and the Chamis model.

Finite element analyses (FEA) are carried out and compared to published results. The commercial finite element code Abaqus was used to set up a finite element frequency analysis of the composite plate setting the elastic mechanical properties in two different ways: using engineering constants or lamina. Results show that lamina results are marginally higher, but both approaches can model the composite material adequately.
A Computational Model for Analyisis of Field Force and Particle Dynamics in a Ferro-Magnetic Microfluidic System
Authors: Edwards Maegan , Hewlin Rodward L.
Published: February 2023

This paper presents the development of a computational model for analyzing the magnetic field, particle dynamics, and capture efficiency of magnetic and non-magnetic microparticles in a ferro-magnetic microfluidic system. This computational model demonstrates a proof-of-concept of a method for greatly enhancing magnetic bio-separation in microfluidic systems using an array of conductive elements arranged in quadrature. In contrast to previous works, our approach theoretically uses a microfluidic device with an electronic chip platform consisting of integrated copper electrodes that carry currents to generate programmable magnetic field gradients locally. In practice, alternating currents would be applied to the electrodes in quadrature to create a periodic magnetic field pattern that travels along the length of the microchannel. This work is a phase 1 study that analyzes particle dynamics in a static magnetic field. The model, which is described in more detail in the methods section, combines a Eulerian-Lagrangian and two-way particle-fluid coupling CFD analysis with closed-form magnetic field analysis that be used to predict magnetic separation considering dominant magnetic and hydrodynamic forces similar to our previous work in magnetic drug targeting. The result of this analysis show that the proposed magnetic capture configuration provides substantially enhanced particle capture efficiency relative to conventional systems.
Latent Heat Thermal Energy Storage in Shell and Tube With PCM and Metal Foam in LTNE With External Heat Losses
Authors: Buonomo Bernardo , Golia Maria Rita , Manca Oronzio , Nardini Sergio , Plomitallo Renato Elpidio
Published: February 2023

Energy storage systems have become increasingly important to reduce environmental impact and to solve the mismatch between temporal and methodical energy demanded and the energy produced.

The purpose of this paper is to describe the results obtained from the numerical simulation of the Latent Heat Thermal Energy Storage System (LHTESS) with a geometry of a vertical shell and tube, made of aluminum metal foam filled with a paraffin wax phase change material (PCM). In the numerical simulations the inner surface of the hollow cylinder is assumed to be at a constant temperature above the PCM melting temperature, the external surface to lose heat toward the outside external ambient, and the top and bottom surfaces are considered adiabatic. The phase change process is modeled with the enthalpy-porosity theory, while the Darcy-Forchheimer model and the Local Thermal Non-Equilibrium (LTNE) assumption are adopted to analyze the aluminum foam-filled by the paraffin. The results of numerical simulations, concerning LHTESS charging phase, are reported as a function of time and are compared in terms of melting time, average temperature, and energy storage rate. The presence of the metal foam is known to significantly improve heat transfer in the LHTESS, and the obtained results show that it is necessary to consider systems with an external heat loss to simulate real operating conditions and understand how this different heat transfer coefficient affects system storage.
Effect of Network Polydispersity on Finite Deformation Elasticity of Vitrimers
Authors: Sarvestani Alireza S. , Field Ryan
Published: February 2023

Recent advancements in polymer chemistry have introduced a new class of stimuli-responsive networks, called vitrimers. Due to the dynamic covalent reactions occurring above a certain temperature, vitrimers hold great promise as adaptive materials capable of shape reconfigurability, welding, and self-healing. Despite extensive experimental studies, the theoretical models for thermo-viscoelastic behavior of vitrimer networks are rare and often built upon simplifying assumptions on the network microstructure. One a priori assumption is that the constitutive strands of vitrimer networks are of uniform length. Transesterification reactions, however, are statistical processes that yield networks with polydisperse chain lengths. This contribution lays out a theoretical framework to study the effect of network polydispersity on viscoelastic properties of vitrimer networks subjected to finite deformations. To this end, the well-known 8-chain model for rubber elasticity is modified to account for vitrimer polydispersity. Assuming that the crosslinking process is uncorrelated along the primary chains, a Poisson distribution is obtained for the strand length in a random network. The free energy of the random network and consequently the components of Cauchy stress are calculated in closed form. The predictions of this constitutive model show a better agreement with the experimental results compared to the models assuming uniform chain length for the network.
Nonlinear Mapping Lyapunov Exponents-Based KNN Analysis for Fault Classification
Authors: Atique Md Saifuddin Ahmed , Yang Cai Xia
Published: February 2023

Rotating machinery are widely used in industry. Machine failures may result in costly downtime. Without effective fault diagnosis, it is impossible to predict the lead-time to failure. Therefore, conducting effective fault detection and identification are desirable and imperative. However, diagnosing faults in rotating machinery is often a labor-intensive and time-consuming practice. This makes conducting effective and efficient fault diagnosis a challenge for technicians and plant maintainers.

This paper presents a Lyapunov Exponents-Based K-Nearest Neighbor (LE-Based KNN) analysis method for detecting and classifying rotating machinery fault. To distinguish different machine conditions, Lyapunov exponents (LEs) calculated using nonlinear mapping were selected as features in KNN analysis for classifying the signature of different faults from the machine vibration. The LEs from forty-four vibration recordings served as training dataset for KNN analysis, and the machine health conditions were grouped into four categories. Data from unknown machinery health condition were used as testing data. The results show that proposed LE-Based KNN analysis method can achieve reliable fault classification on operating condition. The LE-Based KNN analysis method has potential improvement in classification with modified KNN and optimized feature selection. This approach can be used to acquire a complete machine vibration profile that may predict occurrence of damage in different parts of machine and help to detect and identify the defective machineries at early stages.
Investigation of Velocity and Drag With Spherical and Non-Spherical Particles
Authors: Larsen Kyle , Gharavi Hessam , Gerlick Robert , Bae Heechang
Published: February 2023

Numerous practical applications exist where dispersed solid particles are transported within a turbulent accelerating or deceleration gaseous flow. The large density variation between phases creates the potential for significant differences in velocity known as slip. Flow over a backward facing step provides a well characterized, turbulent, decelerating flow useful for measuring the relative velocities of the solid and gaseous phases in order to determine velocity slip and particle drag. Numerous investigations have been conducted to determine the gas phase velocity in a backward facing step for both laminar and turbulent flows and therefore the gas phase flow is well known and documented. Furthermore, some studies have also been conducted to determine the velocity of various sizes of spherical particles in a backward facing step and compared with their corresponding gas phase velocities. Few, if any, velocity measurements have been made for non-spherical particles in a backward facing step. In this work, a Phase Doppler Particle Analyzer (PDPA) was used to measure gas and particle phase velocities in a backward facing step. The step produced a 2:1 increase in cross sectional area with a Reynolds number of 22,000 (based on step height) upstream of the step. Spherical particles of 1–10 μm with an average diameter of 4 μm were used to measure the gas phase velocity. At least three sizes in the range of 38–212 μm for four different particle shapes were studied. The shapes included spheres, flakes, gravel, and cylinders. Since the PDPA is not able to measure the size of the non-spherical particles, the particles were first separated into size bins and a technique was developed using the Photo Multiplier Tubes (PMT) gain to isolate the particles size of interest for each size measured. The same technique was also used to measure terminal velocities of particles in quiescent air. This paper will discuss the results of the measurement of the particles and show that for the gas phase velocity and spherical solid phase particles that the measurements were in good agreement with previous measurements in the literature. However, for the non-spherical particles it will be shown that the drag coefficients were an order of magnitude higher in turbulent flows when compared to the literature values which are based on particles moving through a still fluid. This information is valuable for modeling turbulent two-phase flows since most assumptions of the drag are based on correlations from empirical data with particles moving through still fluid.
Cold Spray Helium Recovery System Noise Study
Authors: Young Steven D. , Brungart Timothy A. , Jonson Michael L.
Published: February 2023

Helium recovery systems require multiple compressors, fans, valves and other mechanical components which are likely to radiate considerable sound to the outdoor environment. To assure compliance with a local residential noise ordinance prior to installation, sound propagation effects were investigated at the future site of a helium recovery system in State College, PA. Sound pressure spectra from a baffled acoustic source were measured at distances of 1 meter to 50 meters away from the planned installation location, and the pressure spectra were found to collapse reasonably well with distance using simple spherical spreading principles. This scaling was then applied to sound pressure spectra acquired from a representative helium recovery system located at the manufacturer’s plant in Box Elder, South Dakota. The overall sound pressure level (OASPL) from the dominant noise source on the representative system (i.e. the compressor exhaust) was measured at 1 meter and scaled to the residential property line located approximately 50 meters away from the future State College, PA site. The predicted OASPL for the new system at the residential property line was 61 dBA, which is 6 dBA above the local township noise ordinance requirement of 55 dBA. Noise control efforts are currently being considered and include the installation of an acoustic attenuator at the compressor exhaust location to reduce the overall noise level.
Cellulose Nanofibers (CNF)/Carbon Fiber Composites With Enhanced Flexural Strength for Structural Applications
Authors: Bhaganagar Siddharth , Biswas Pias Kumar , Agarwal Mangilal , Dalir Hamid
Published: February 2023

Cellulose Nanofibers (CNF) are produced from plant cellulose microfibers through a facile synthesis process. These fibers are discontinuous, very graphitic, and extremely compatible with the majority of polymer processing techniques; they can be dispersed isotropically or anisotropically. Since they are available in a free-flowing powder form, the dry carbon fiber can be physically modified with the addition of CNF. The effect of the CNF compositions, their morphology on carbon fiber, and subsequent mechanical properties are explored in this paper. The CNF composite nanofiber networks are introduced as interleave layers to improve the interlaminar shear strength (ILSS) of an epoxy/carbon fiber laminate composite. Dry carbon fiber is coated by different volume fractions of CNF (0.6 wt.%, 0.8 wt.%, 1 wt.%) through the strong bath sonication process. Laminates are fabricated by modifying dry carbon fiber surface with CNF resulting in a considerable improvement in the mechanical characteristics as compared to a neat sample. The application of CNF composite nanofiber networks as an interleaved layer in an epoxy/carbon laminate increases the delamination resistance of the ILSS in both 0.8wt% and 1 wt.% CNF enhanced laminates by 27.2%, and 12.4% respectively, but no significant difference is found for ILSS in 0.6 wt.% CNF enhanced laminate. Moreover, a significant improvement is observed in flexural modulus for 0.8 wt.% CNF coated carbon fiber laminate. This suggests that CNF can enhance the delamination resistance and flexural strength of an epoxy/carbon fiber laminate undergoing delamination and deformation. This result is attributed to crack path modification, and load energy absorption by higher modulus CNFs reinforced nanofibers interleave in the laminate resulting in a higher shear modulus to the networks.
Thermal Analysis and Design of Self-Heating Molds Using Large-Scale Additive Manufacturing for Out-of-Autoclave Applications
Authors: Pokkalla Deepak Kumar , Hassen Ahmed Arabi , Heineman Jesse , Snape Thomas , Arimond John , Kunc Vlastimil , Kim Seokpum
Published: February 2023

Autoclave processing is a commonly used state-of-the-art fiber-reinforced composite manufacturing technology, albeit with high capital cost, long cycle times and high energy consumption. Alternatively, out-of-autoclave processing reduces the initial and operating costs while producing composite structures with similar quality as that of autoclave parts. Additive Manufacturing (AM) the scaled-up molds for out-of-autoclave process using carbon fiber (CF) reinforced composite offers design flexibility, enhanced mechanical, and thermal properties in addition to reduction in weight and cost. However, heating of these molds using an oven is still expensive and necessitates an energy-efficient heating process. In this study, resistive heating through heating elements embedded within fiber reinforced composite molds is used as an efficient heating mechanism. The goal is to design wire embeddings and determine the optimal heat flux density to achieve a target uniform temperature of 80°C across the mold surface. To this end, numerical analyses were performed to evaluate the temperature distribution across the composite mold surface for a given wire placement and mold configuration. Constant thermal properties of the 20 wt.% short CF reinforced acrylonitrile butadiene styrene (ABS) were used in the thermal analysis. Time taken to reach the steady state temperature was also estimated. Design guidelines for wire embeddings were included to enable efficient manufacturing of fiber-reinforced composites through out-of-autoclave molds.
Toward the Design of a Kangaroo-Inspired Robot
Authors: Beaster Garrick , Jawad Badih , Fernandez Vernon , Vejdani Hamid
Published: February 2023

In this paper we report on the design and fabrication of a Kangaroo-inspired running robot. The goal was to develop a robotic platform to understand the effects of the leg dynamics on the stability of running gaits. Specifically, we studied the effect of the leg posture and compliance on the self-stability characteristic of spring mass running gait. In our design, we tuned the leg compliance and leg resting posture and studied their effect on the stability performance of the system. The design of this platform was carried out based on the well-known Spring Loaded Inverted Pendulum (SLIP) as a first stage reduced order model. After that, we modeled the segmented leg with a rotational spring at the knee and studied the effect of the spring stiffness and resting posture of the leg on the self-stability of the system. Then, to be able to manage the whole energy level of the system and in order to transition to different energy levels, we expanded the model to a hip-actuated system in which the body can apply hip torque during the stance phase. For the flight phase swing leg control policy, we followed the simple constant angle of attack strategy in which the system lands with a constant leg orientation. The results showed that if the leg posture and compliance were chosen properly, the self stability of the system improves and a simple hip torque controller can manage the energy transitioning in a robust way with high convergence rate.