bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of Binary Pressure Sensitive Paint for Temperature and Heat Transfer Coefficient Measurement of Leading Edge Film Cooling
Authors: Burdett Timothy A. , Yeh Ming-Feng , Wright Lesley M. , Han Je-Chin
Published: February 2023

Film cooling is a common technique for protecting the leading edge of gas turbine vanes from the hot combustor exhaust. In the laboratory, film cooling effectiveness distributions are often obtained by measuring the mass transfer of a foreign gas coolant in mainstream air with pressure sensitive paint (PSP), eliminating the inherent conduction errors of steady-state heat transfer experiments and providing highly resolved measurements. However, both the effectiveness and heat transfer coefficient are necessary to calculate the heat flux for a given film cooling configuration and fully quantify the impact on the vane surface temperature.

The heat transfer coefficient generally requires a thermal test, which typically uses thermochromic liquid crystal (TLC), infrared (IR), or temperature sensitive paint (TSP) to measure the surface temperature. Alternatively, the additional luminophore in binary pressure sensitive paint (BPSP) can be used to measure the surface temperature. The second luminophore of most BPSPs is sensitive to temperature for use as a reference to correct pressure measurements for adiabatic heating in transonic and supersonic flows, but it can also be used to directly measure the surface temperature.

As a proof of concept, this paper uses BinaryFIB PSP from Innovative Scientific Solutions (ISSI) to measure the film cooling effectiveness and heat transfer coefficient on the leading edge of a cylinder, approximating flow on the leading edge of a gas turbine vane. The cylinder has a 7.62-cm diameter with two rows of cooling holes at ±15° from the leading edge. Each row contains 10 holes with a 0.475-cm diameter, spaced 4 diameters apart in the spanwise direction and angled 30° from the cylinder axis. The mainstream Reynolds number was 100,000 based on cylinder diameter with a turbulence intensity of 7.1%. The coolant-to-mainstream density ratio was 1.0, and the blowing ratio was 0.8. The film cooling effectiveness was measured in a typical steady-state mass transfer experiment using the pressure signal from the BPSP and nitrogen as coolant. The heat transfer coefficient was measured in a transient heat transfer experiment using the reference signal from the BPSP. The transient calculations assumed 1-D semi-infinite heat transfer.

Despite the high uncertainty of the measurement ranging from 24.0% to 71.1%, the results demonstrate the feasibility of the method, identify the best test methodology to minimize conduction errors, and provide a reasonable comparison with previous measurements in the literature. Further BPSP development of the reference luminophore is recommended to improve the sensitivity to temperature and increase the glass transition temperature.
Toolpath Planning With Thermal Stress Awareness for Material Extrusion Additive Manufacturing
Authors: Khatkar Jayant , Clemon Lee , Mettu Ramgopal
Published: February 2023

Additive manufacturing has emerged as a next-generation technology for advanced fabrication. Fused Filament Fabrication (FFF) is the most widespread form of material extrusion additive manufacturing and has growing applications in large scale construction. Despite its advantages, FFF is limited by structural weaknesses introduced by cooling of the material between layers. This paper presents an approach to reduce the probability of failure for a given object under known loading conditions through improved toolpath planning which considers temperature decay. Our approach reorders the fabrication sequence to vary the time to print between layers such that the thermal stress induced in fabrication is reduced in regions most likely to fail at the expense of increasing thermally induced stress in less critical areas. In our simulation experiments, we found that our approach offers the greatest improvement when the rate of cooling is large enough for significant temperature decay to occur, but not so large that cooling occurs too quickly for the print order to have any effect. Our approach offers the potential to improve the performance of 3D printed components under known loading conditions by considering the temperature of the print in the planning of the toolpath.
Piezoelectric Bi-Layer Waveguide on Quartz Saw Device for Liquid Sensing
Authors: Lee Kun-Lin , Kowach Glen , Voiculescu Ioana R.
Published: February 2023

Liquid viscosity is an important quantity for medical analyses (accurate and fast one-time tests) and microfluidic reaction systems (continuous flow sensing). A novel integrated piezoelectric layer with a polymer waveguide on a quartz SH-SAW device has been developed for liquid sensing. The device is capable of sensing viscosities from approximately 1 mPa·s to 10 mPa·s with higher precision than devices without the bilayer. The integrated piezoelectric layer and polymer waveguide enhance the sensitivity of the SH-SAW device. This work expands the potential applications for SH-SAW devices for real-time liquid drop or flow testing. ST-90°X quartz substrate was chosen for the SAW delay-line biosensor because of its stable temperature coefficient of frequency (TCF) at room temperature. Therefore, a zinc oxide (ZnO) piezoelectric thin film layer was used to enhance the local particle displacement and dielectric coupling. We demonstrate the local particle mobility enhancement due to the ZnO layer, and wave mode transition to surface horizontal waves with the bilayer waveguide.
Additive Manufacturing of Embedded Strain Sensors in Structural Composites
Authors: Zhao Dongfang , Meves Jacob , Mondal Anirban , Saha Mrinal C. , Liu Yingtao
Published: February 2023

In this paper, a multi-walled nanotube-based nanocomposite is developed for the 3D printing of embedded strain sensors in structural composites. The formulation of nanocomposites is investigated, and the optimal nanotube concentration is identified, considering multiple aspects including cost, processing capability, and printing capability. The developed nanocomposites are directly printed onto glass fiber fabrics using the material extrusion-based additive manufacturing method. Then, the 3D printed nanocomposites in the format of strain gauges are employed for the fabrication of continuous fiber-reinforced composites with embedded sensors. To demonstrate the load and strain sensing capability, composite laminate beam samples are fabricated for testing. The microstructures, potentially embedded voids, and nanoparticle distributions are characterized using a scanning electron microscope. Moreover, the load sensing functionality of the manufactured glass fiber composites using embedded nanocomposite strain gauge is characterized under 3-point bending load conditions. The sensitivity, repeatability, and reliability of the 3D printed nanocomposites are experimentally characterized using a standard mechanical testing system. Particularly, the effects of maximum load and load rates on sensitivities of the developed composites are tested. The 3D printed strain gauges can be used for the monitoring of composite integrity, indicating their safety and reliability under complex and fatigue loading conditions.
Opportunities for Energy Efficiency Improvements in Craft and Micro-Breweries
Authors: Sueza Raffa Laryssa , Bennett Nick S. , Clemon Lee Michael
Published: February 2023

Rising energy prices and increasing competitiveness in the brewing industry challenge beer producers to reduce costs. To address this issue — and the environmental concerns over climate change — more energy-efficient brewing processes are required. The brewhouse consumes around one-quarter of the total energy demand in a brewery, especially wort boiling, where heat energy in the form of vapour is often wasted and presents a large potential for recovering energy. Although the technology for heat recovery during wort boiling is commercially available for large breweries, the development of equipment technology for craft and micro-breweries still lags behind. Based on a survey of Australian local craft and micro-breweries and a nano-brewery case study, we compare the evaporation rates during wort boiling for different operational parameters and use the results to verify a proposed mathematical model of evaporation from a kettle. We also propose and analyse options for re-utilising the recovered energy, such as pre-heating water for use in a subsequent process or storage for a later brew. Our study shows that the vapour released during the production of one litre of beer has the potential to heat 0.6 to 1.6 litres of water from ambient to 65°C. As for the potential energy savings and environmental impact, the case study nano-brewery can save approximately 5% of the brewhouse’s energy consumption or 2% of the energy required by the entire brewing process, while each surveyed brewery can spare 16 to 133 tonnes of CO2-e from being released into the atmosphere each year. These results reinforce the potential of recovering waste energy from wort boiling vapours in assisting breweries to become more energy-efficient, competitive and environmentally responsible.
Experiential Learning for Undergraduate Students Through Collaborative Capstone Projects on Advanced Manufacturing
Authors: Xu Jaijun , Shetty Devdas , Sanchez Guerrero Pablo
Published: February 2023

In order for students to enhance their understanding of engineering concepts, hands-on experience has proven to be essential. Incorporating the design component in undergraduate engineering education has been an immediate and pressing concern for educators, professional societies, industrial employers and agencies concerned with national productivity and competitiveness. While there are various ways of achieving that, one proven method is to have students working on projects and thinking about the learning objectives and tasks they are doing, a.k.a, experiential learning. There are several strong reasons to advocate the selection of experiential learning-based classroom teaching. An active learning-based approach can encompass both isolated and highly structured activities to motivate students to take charge of their deep learning. Active learning-based learning can also be very effective in creating personal connections between students and the course material, which strongly increases the student’s motivation to learn proactively. In addition to the course content, active learning-based learning develops life skills like improving subject mastery with others feedback, collaboration, and brainstorming to reach the most rational answers. Recently, advanced manufacturing technology has become increasingly appealing for a range of industries. however, it remains a challenge to infuse experiential learning experience in advanced manufacturing in undergraduate curriculum and to enhance undergraduate design and research experiences to meet both societal needs and the growing job-market demands. Here at the University of the District of Columbia (UDC), the District of Columbia’s only public institution of higher education, and a historically black college and university (HBCU), it has recently modernized its undergraduate curricula in engineering with an undergraduate concentration in Advanced Manufacturing to meet that need. This paper presents a case study of implementing experiential learning through a series of collaborative Capstone Design projects that are collaboratively advised by project advisor and external subject-matter experts. Specifically, the subjects include Additive Manufacturing and Nanotechnology with applications in Energy, Manufacturing, Aerospace and many other fields. Further, this paper will also discuss and present the assessment data from the author’s experience and provide suggestions and lessons learned from this practice to help the broader community of engineering education.
Design of an Improved Vertical Spiral Closed Loop Geothermal Heat Exchanger
Authors: Malhotra Tarun , Davis Dorian , Adams Deshawn , Gebre Fisseha L. , Xu Jiajun
Published: February 2023

Geothermal heat pumps present a very intricate installation process and requires a vast amount of space which can cause a financial hurdle for most users. The geothermal system makes use of the constant ground temperature at the minimum of 5 ft depth with a thermal conductive working fluid and specified length of pipping. The system undergoes the necessary heat transfer that will be used as part of the heating or cooling process. In this study, an additively manufactured heat exchanger was designed and developed to address this issue. The design has an innovative coiled inner pipping to reduce the space needed for its installation, as well as combining the heat exchanger component with a drill bit design to simplify and reduce the cost of installation. We used CREO 8.0 to make a detailed drawing and CAD model of the system, which will then be simulated on ANSYS fluent software. During the simulation we studied the performance of heat transfer. In addition, this study also analyzes the coefficient of heat transfer and fluid pressure drop as a function of Reynolds number. For production of the system an additive manufacturing technique was used to manufacture the prototype.
Energy Absorption of Axially Loaded Thin-Walled Pressurized Cylinders
Authors: Haji LaRance , Vejdani Hamid , Jawad Badih , Fernandez Vernon
Published: February 2023

Our goal in this paper is to experimentally measure the axial load and energy absorption capacity of thin-walled aluminum cylinders subjected to internal pressures. For this purpose and to achieve a high level of accuracy in manufacturing the thin-walled cylinders, we used regular soda cans as the cylindrical specimens. The specimens’ dimensions were selected based on attaining a large radius to thickness ratio (r/t) of 340 to minimize weight and also maintain a low axial length to radius ratio (L/r) of 2.6 to mitigate global buckling. Each specimen was compressed quasistatically while maintaining constant internal pressure with the use of input and output pressure regulators we designed and built for this purpose. One of our goals in this experiment was to better understand the energy absorption capability of such a lightweight structure and to study the failure modes of local buckling under different internal pressures. We observed that the local buckling mode switches from non-axisymmetric folds (diamond mode) to axisymmetric folds (ring mode) at a critical internal pressure. We also presented a comparison between pressurized aluminum thin-walled cylinders to steel cylinders and we found that aluminum made cylinders outperform their steel counterparts when compared by equivalent masses. Applications of this study vary across a wide range of industries, with the most appealing being automotive and aerospace.
Statistical Analysis of Strain Rate Dependency of the Mechanical Properties of Unidirectional CFRE Materials
Authors: Seif Charbel Y. , Hage Ilige S. , Hage Re-Mi , Baydoun Ahmad M. R. , Hamade Ramsey F.
Published: February 2023

With the aim of finding new materials having high stiffness to density ratio, carbon fiber composite materials have gained popularity as alternatives to traditional high-stiffness and high-density materials. This work investigates the dependency on strain rate of some mechanical properties of unidirectional carbon fiber reinforced epoxy, CFRE. The composite laminates were fabricated at fiber orientations of 0° (dubbed type 1) while others at 90° (dubbed type 2). Statistical analysis (using Minitab® software) has been applied to determine the statistical significance (modulus at confidence interval varying from 5% to 10%) of the effect of strain rate on composite material response and strength. Both type 1 and type 2 composite laminates were tested at several levels of flexural strain rates varying from 1.8*10−5 s−1 to 7.8*10−3 s−1. For type 1 and type 2 laminates, the flexural fracture stress values were found to increase around 4.5% and 8.6%, respectively, for the studied range of strain rates. It was also found that the flexural modulus of elasticity increased for both 0° and 90° increase in order of 5% and 10%, respectively, for type 1 and type 2 laminates over the strain rate range. This was evidenced by the increase in the variance of the experimentally collected flexural strength values with increasing operating strain rate.
Effect of Salt Spray Cyclic Corrosion on the Mechanical and Reversibility Performance of Mixed Material Joints With Modified Adhesive
Authors: Burczyk Matthew , Nassar Sayed A.
Published: February 2023

The effect of cyclic corrosion on the static strength performance and reversibility performance of multi-material single lap joints is investigated. Aluminum substrates are adhesively bonded to Carbon-Fiber-Reinforced thermoplastic composite substrates using a commercially available two-part epoxy. The adhesive is modified with Thermally Expandable Particles at various concentrations by weight, with the purpose of allowing for joint separation using a charged RF coil to evaluate reversibility performance. The quasi-static performance of baseline joints is assessed, and the results from the various particle concentrations are compared. The cyclic corrosion testing of the Single Lap Joints is performed in accordance with a GMW 14872 3 stage laboratory standard for different lengths of duration up to 57 cycles. Quasi-static lap shear tests are performed at various stages of corrosion cycling and compared. Results and conclusions are provided.
Taxonomy of Severity of Cyber-Attacks in Cyber-Manufacturing Systems
Authors: Espinoza-Zelaya Carlos , Moon Young
Published: February 2023

Increasingly named as the number one non-traditional risk cyber-attacks against Cyber-manufacturing Systems (CMS) can cause a wide variety of losses. As the 4th industrial revolution is taking place CMS have become more resilient with the implementation of prevention, detection, redundancy, withstanding, and recovery mechanisms against cyber-attacks. However, the ever-evolving nature of these threats require systems to still be prepared for their eventual occurrence as it’s been demonstrated in the increasingly more common advent of successful cyber-attacks. While multiple generic threat models have been proposed by academics and government organizations for assessing the impact of cyber-attacks against Cyber-Physical Systems there is a research gap when it comes to manufacturing specific applications and how to assess their severity. In order to evaluate the impact of a cyber-attack against CMS this taxonomy proposes a classification of threats severity comprising three general themes: i) Operational Impact: Effective production time loss that incur in inability to yield the expected output, ii) Economic Impacts: Direct financial cost of the attack, mitigation, and recovery, and iii) Intangible Losses: Integrity breaches against original patents, models, or intangible actives.
Numerical Investigation on Aerodynamic Performance of a Racing Car by Drag Reduction
Authors: Hassan Mahedi , Hassan Mahmudul , Ali Mohammad , Amin M. Ruhul
Published: February 2023

Recent energy crisis has forced researchers to design fuel-efficient automobiles, where one of the main critical changes is to reduce aerodynamics drag created by fluid friction. At high speed, aerodynamics drag, especially the pressure drag, creates a substantial backward force, and hence, unwanted excess fuel is consumed to counterbalance this dragging effect, which hinders designing fuel-efficient automobiles. Hence, to mitigate this pressure drag, here in this work, numerical analyses have been done (i) to examine drag coefficient changes through incorporating aerodynamic vents at the front, at the rear, and both front and rear on the automobiles, (ii) to reduce drag force by utilizing exhaust gas to fill the low-pressure vortex, (iii) to investigate the effect of wheels on the overall drag resistance of the model. The ANSYS™ 2020 R1 Fluent module is used to perform this numerical simulation. Appreciable improvement on drag reduction can be found by incorporating above mentioned modifications on racing car body configuration.
An Efficient Time-Domain Model to Simulate Parametric Resonances in a Floating Body Free to Move in Six Degrees of Freedom
Authors: Kurniawan Adi , Tran Thanh Toan , Yu Yi-Hsiang
Published: February 2023

We present a computationally efficient time-domain model capable of simulating parametric resonances in a floating body in waves. The model assumes all wave forces to be linear, but the inertia and restoring forces acting on the body are expanded to second order in body motions. The simulation speed on a standard computer is approximately 40 times faster than real time. The model is applied to a soft-moored floating axisymmetric body which absorbs energy through heave, but is otherwise free to move in six degrees of freedom. Under certain conditions, we show that the body undergoes parametric resonance with large amplitudes not only in surge and pitch, but also in sway, roll, and yaw, provided it is given some small initial displacement in one of these out-of-plane modes. The predictions are confirmed by simulations using state-of-the-art nonlinear Froude-Krylov and computational fluid dynamics models.
Safe Design of Gas-Management Systems for Turning Bolt-Action Rifles in View of Known Ammunition Mismatch Hazards
Authors: Munsell W. P.
Published: February 2023

Ammunition mismatch refers to a phenomenon by where the chamber of a firearm can accommodate more than one caliber of ammunition. This is possible due to the historical development of firearms and ammunition which has been largely unregulated, and therefore lacking in any commonly agreed-upon rules for architecture. If a user inadvertently chambers an oversize caliber round, the result is usually a failure of the shell casing during discharge due to the lack of proper support from the chamber walls. These failures manifest themselves as burst case-heads and/or primers which allow the rearward flow of expanding gases. Such flows may harm the user directly through direct contact with flame or excessive heat, or indirectly by initiating an over-pressure which fractures the magazine well and rifle stock. Shrapnel from this secondary failure can maim or kill the user or by-standers in the vicinity. The lack of a standardized performance criteria for this issue has resulted of a mix of designs in the marketplace which expose users to vastly different levels of risk. This disparity is not communicated to the user in any way, and up until now has not been formally studied and quantified in a published, peer-reviewed paper for use by the technical community.

This paper presents the results of a battery of both nondestructive and destructive experiments performed on two major manufacturer’s designs. New methods of analysis are explored, quantified, and compared to live-fire test data. Most importantly, the question of whether an economically feasible design which safely manages gas flow under the condition of ammunition mismatch is answered. It was found that effective measures are available to prevent user injury under at least some ammunition mismatch conditions, and that the incorporation of these measures is not correlated to the price point of the product.
Producing High-Strength Pellets From Seaweed, Sawdust, and Hay for Gasification
Authors: Nazemi Mohiodin , Safavi Aysan , Camille P. Bonthonneau Eyja , Richter Christiaan , Unnþórsson Rúnar
Published: February 2023

Hay, invasive lupine plants, wood chips, and seaweed are the four abundant biogenic fuel options in Iceland. These four biomass types are potential renewable fuel feedstock as they can be converted into syngas or high-value fuels using thermochemical processes such as pyrolysis and gasification. In this study, we focus on biomass pelletizing, which is a major process for preparing various kinds of feed for either gasification or controlled combustion as in powerplants and heat applications. Pelletizing is producing a low-humid, dense, and uniform shape of feedstock, which is appropriate for the continuous and efficient performance of the gasifier. The pellets need to be dense enough not to collapse in the hopper while being fed to the reactor. The challenge in this study is to produce high-quality pellets with high energy content, high strength, and optimized moisture level from abundant biomass types in Iceland that can be gasified efficiently and continuously in the gasifier. To address this challenge, we pelletized blends of hay, wood chips, and seaweed with different percentages. In this study, we focus on the strength of the pellets. The experiments suggest that up to a hay fraction of 20 wt.% a higher hay content results in a stronger pellet. Based on our experiments, pellets made only from wood are typically not strong enough for gasification. It was observed that after running several pelletizing experiments continuously, the temperature of the discharged pellets increased, and this parameter influenced the strength of the pellets.
Preparation of Hybrid Alkaline Cement Based on Natural Zeolite As Sustainable Building Material
Authors: Cornejo Mauricio , Baykara Haci , Garcia Natividad , Garces Juan , Correa Walter , Frere Cecibel , Torres Julio
Published: February 2023

Alkaline hybrid type cement is an interesting multi-component system that incorporates a high content of mineral additions, low content of Portland clinker (CK) (< 40%), and alkaline activator. The development of these types of cement allows a significant reduction in the clinker factor, thus leading to an economic and mainly environmental benefit.This study explores the possible development of such cement. Hybrid cement samples were prepared by alkaline activation of the natural zeolite, mainly composed of mordenite, and utilizing a NaOH solution. After mixing with OPC and with an alkaline solution, zeolite-rich tuff formed cement pastes with an activator/binder ratio of 0.5 that were cured for 24 hours at room temperature and then for 7 days underwater. The optimal alternative was evaluated based on compressive strength, quantitative X-ray diffraction, and Fourier Transform Infrared spectroscopy. As a result, the best dosage was that of 60% zeolite ruch tuffs and 40% CEM Type I showing values of compressive strength of 10 and 14 MPa at 7 and 28 days, respectively.
Machine-Learning Approach to Modeling Oxidation of Toluene in a Bubble Column Reactor
Authors: Tayeb Raihan , Zhang Yuwen
Published: February 2023

A feed forward machine-learning (ML) model is applied to study bubble induced turbulence and bubble mass transfer in a bubble column reactor. Using direct numerical simulation data for forced turbulence, bubble deformations and flow velocities are predicted. To predict mass transfer, ML sub-grid scale (SGS) modeling technique is introduced for the concentration of reactants and products undergoing parallel competitive reactions in the oxidation of toluene. The ML model replaces the iterative approach associated with the use of analytical profiles for previous SGS models for correcting concentration profiles in boundary layers. The present model, thus, offers a significant performance bonus as well as the flexibility to extend to more complex scenarios due to its data-driven nature.
Virtual Vibrations Laboratory
Authors: Mohammadzadeh AliReza , Haidar Salim M.
Published: February 2023

Lacking a physical vibrations lab, a series of virtual experiments were developed and deployed to enhance students’ understanding of topics covered in the Study of Vibrations course. MATLAB and SIMULINK were utilized to simulate response of single-degree and two-degree freedom systems to free vibrations, damped vibrations, harmonic forced vibrations, and transient unit step excitations. Using the scope and power spectral density windows in SIMULINK, clear understanding of stable and unstable response of the system for different system parameters and excitations were examined. Beating phenomenon, together with system resonance to harmonic excitations were realized. Phase diagram together with instability, and stability of the response along with limit cycles were simulated and analyzed. Response of nonlinear systems to different initial conditions in free vibrations together with forced harmonic and transient excitations were simulated and analyzed. These experiments promote functional understanding by design of important concepts and theories in Vibrations. Also, they provide for an effective economical means to expose additional students to the instrumentation of modeling and simulation-based laboratories. These experiments and their ensuing uses will be presented in this paper along with corresponding students’ learning outcomes.
Attaining Nonlinear Hardening Stiffness in Piezoelectric Vibration Applications Using Passive Nonlinear P-N Junction Capacitance
Authors: Taşkıran Muhammed Ali , Özer Mehmet Bülent
Published: February 2023

Piezoelectric vibration isolation and energy harvesting applications has been studied extensively. Nonlinear approaches may provide better performance over a broader frequency range. Nonlinearity can be introduced in the mechanical domain or electrical domain actively or passively. Since electrical components can be in smaller scales compared to mechanical counterparts, nonlinearity in the electrical domain can be more practical and convenient. Moreover, passive structures require no energy supply and controller therefore they are simpler and more reliable than active ones.

In this paper, a novel way to attain passive hardening stiffness was presented for piezoelectric vibration isolation or energy harvesting. Nonlinearity was suggested to be attained with use of nonlinear capacitance of P-N junction in electrical domain and its capacitance model is introduced. A piezoelectric patch operating in d33 mode is considered and modelled as a single degree of freedom (SDOF) linear stiffness element without internal damping. force vs. displacement curves obtained by the models and finite element method (FEM) showed that hardening stiffness can be achieved. Frequency domain analysis is conducted for hardening stiffness and effect of piezoelectric coupling coefficient on resonance frequencies investigated. It is explored that resonances of nonlinear frequency response curves are bounded by open and short circuit resonance frequencies. Lastly, whether theoretically analyzed hardening capacitor is realizable or not is discussed.
Towards the Deep Learning-Based Autonomous Collision Avoidance
Authors: He Binxin , Xiao Youan , Wang Tengfei , Li Zhuo
Published: February 2023

Reinforcement learning (RL) is considered as an effective method to avoid ship collision. In this study, a ship collision avoidance method based on MADDPG in RL is proposed. In algorithm, some indicators, including DCPA, TCPA, relative distance and relative velocity between ships, are calculated and then collision risk index and the best way point are calculated. In the implementation part, by gathering observational information, setting the reward of the agent and restricting the action of the agent, the agent can learn an effective strategy after training. When there is a risk of collision, the ships in the environment can make reasonable actions to avoid collision. The final experiment verifies the effectiveness of this method.
Application of Artificial Neural Network to Predict the Performance of Thermoelectric Power Plants at Design Conditions
Authors: Carapellucci Roberto , Giordano Lorena
Published: February 2023

Recently Artificial Neural Networks (ANNs) have been gaining an important role in the analysis of complex power cycles, since they have the potential to reduce the computational effort in designing and control of power plants operating conditions compared to rigorous thermodynamic models.

This paper presents a novel methodology for the prediction and optimization of the performance of thermoelectric power plants at design conditions using ANNs. The methodology involves a preliminary study to randomly generate the dataset of input variables (i.e., power plant operating conditions) and evaluate the dataset of output variables (i.e., energy and economic performance indicators) via thermodynamic simulation. Using these datasets, ANNs are trained and validated. Finally, the ability of ANN algorithms to replicate thermodynamic models is assessed in terms of absolute relative errors and coefficient of determination. The proposed methodology is flexible with regard to the type of power plants to be replicated and the extent of the investigation, that can be easily adapted by properly selecting the set of input and output variables.

To prove its feasibility, the methodology is applied to a coal-fired power plant and a triple-pressure reheat combined cycle. In both case studies, the methodology provided a very good accuracy in predicting the power plant behavior and optimizing their energy or economic performance.
A Comparative Study of Disk Wear Volume Evaluation of Al2024 Based on ASTM G99
Authors: Salguero Jorge , Iglesias Patricia , Vazquez-Martinez Juan Manuel , Batista Moises , Del Sol Irene
Published: February 2023

In this paper, a comparative study between the three different methods proposed in the ASTM G99 standard for volume loss calculation in tribological Pin-on-Disk tests is presented. The mass/density and the geometrical methods (exact and reduced approximation) have been applied to the evaluation of aluminum/WC-Co tribological pair, providing similar results, with differences lower than 7%. However, adhesion wear mechanism typically found in aluminum alloys, is not considered in this method, increasing the differences between mass and geometrical methods, which stands the need of a corrector factor for wear evaluation in soft materials.
On the Stability Analysis of a Double-Link Inverted Pendulum Subject to an Oscillatory Tilted Excitation
Authors: Taherian Babak , Shankar Praveen
Published: February 2023

This paper presents the study of the stability characteristics of a two-link (double) inverted pendulum system subject to a tilted and oscillatory excitation at the bottom pivot. Each of the two links are assumed to have a concentrated point mass at their ends. The excitation force acts at the bottom of the first link and its amplitude, frequency and tilt angle can be varied. The system is also assumed to have very light damping between the two links. Euler-Lagrange formulation is used to develop the equations of motion of the double-link inverted pendulum which results in a non-autonomous dynamic system. The method of multiple timescales is implemented to convert it to an autonomous system which allows for determination of the equilibrium points. Bifurcation analysis of the damped and undamped system with respect to frequency and amplitude of the input excitation is performed using a continuation analysis software. Further, the evolution of the equilibrium points and their stability properties of the system using extensive Monte-Carlo simulation of the nonlinear system as several parameters such as damping coefficient, excitation frequency and tilt angle are varied is presented.
Structural Evaluation of a Lapidus-Type Cuneometatarsal Arthrodesis
Authors: Mancera-Campos Natali , Hinojosa-Buenrostro Josseline Paola , Vidal-Lesso A. , Martínez-Bocanegra Marco Antonio , Bayod-López Javier
Published: February 2023

The numerical models developed to analyze the hypermobility of the first ray are varied since this is considered the most common condition to which the cause of a varied type of pathologies of the adult foot is attributed. Lapidus-type arthrodesis is one of the treatments most used to correct it. However, no works analyzed, numerically, the biomechanical behavior of the foot bones related to the surgical technique; or the plate used for the procedure. Therefore, the effects of fixation on bones and the structural strength of the plate are unknown.

For the above, in this work, a 3D nonlinear finite element analysis of arthrodesis in the cuneometatarsal joint of the first ray is performed, for which a simplified foot model is used and inserted with a Lapidus plate that fixes the plantar area.

The results found with this model indicate that the insertion of the plate contributes to reducing the hypermobility up to 124 % for the hallux angle parameter and contributes to the bones reaching a considerable percentage (42.87%) of their ultimate stress. Although these values do not exceed the ultimate stress of the material, neither in bone nor in plate, it is suggested to carry out an analysis that includes the trabecular part of the bone since the stress found with this model exceeds the ultimate stress value of this material.
Acceleration of Intergranular Cracking in Ni-Base Alloy GH4169 (IN718) Due to the Growth of δ-Phase Around Grain Boundaries Under Creep Loading at Elevated Temperatures
Authors: Nakayama Ayumi , Wang Runzi , Miura Hideo
Published: February 2023

In this study, intermittent creep tests were conducted on GH4169 (IN718) at 800°C to elucidate the degradation mechanism of the grain boundary strength accompanied by microstructural changes under mechanical loading at elevated temperature. The microstructural degradation process was visualized by EBSD (Electron Back-Scatter Diffraction) method and the degradation of the strength of grain boundaries was verified by a micro tensile test in a scanning electron microscope using FIB (Focused-Ion Beam) apparatus. Under the creep loading, the precipitation of δ-phase (Ni3Nb) was found to grow around grain boundaries. The δ-phase precipitates grew around grain boundaries by the coarsening of the solute strengthened γ″ phase in this alloy. Thus, the growth of the δ-phase caused the disappearance of the solute strengthened phase in the surrounded grains. As a result, the effective strength of grains decreased, and the effective strength of grain boundaries increased by the precipitation strengthening around the grain boundaries. The effective strength of grain boundaries, however, started to decrease with time due to the acceleration of the growth of vacancies and dislocations around the interfaces between the precipitates and the matrix. This accumulation of defects was attributed to the large lattice mismatch between the precipitate and the matrix. As a result, intergranular cracking was accelerated. The change of the effective strength of a grain and a grain boundary was validated by the micro tensile test of bicrystal structures cut from the damaged polycrystalline alloy during the intermittent test.
Modeling the Damage Initiation of White Matter Brain Tissue During Indentation
Authors: He Ge , Fan Lei
Published: February 2023

Understanding and modeling the mechanical behaviors of white matter brain tissue is important to gain insights into brain injury. With embedded axonal fiber bundles, white matter is typically treated as an anisotropic material whose mechanical behaviors and properties are extensively studied and characterized through experimental approaches in the past decades. However, although the injured brain tissue may experience large deformation in some head impact scenarios, most works characterize the white matter in a small-strain regime to avoid the large deformation-induced damage. Both experimental and modeling studies of white matter at large strain are still few, especially when the damage effect is included. We recently performed the indentation tests on porcine white matter with the indenter having a large displacement and found a clear damage initiation and progressive failure behavior of white matter when deformed beyond certain strain levels. To model this behavior, we assume that this failure phenomenon is caused by the fracture of axonal fiber bundles and propose a coupled hyperelasticity-damage constitutive model. The proposed constitutive model is implemented into finite element codes that is used to reproduce the indentation process. Results show that by using this proposed constitutive model with identified parameters, the finite element simulation can reproduce the damage initiation observed in experiments.
Thermo-Mechanical Process Modeling of Additive Friction Stir Deposition of Ti-6Al-4V Alloy
Authors: Raihan Gazi Abu , Chakravarty Uttam K.
Published: February 2023

In this study, a computational fluid dynamics (CFD) model is developed to investigate the thermal-mechanical process in additive friction stir deposition (AFSD), a novel additive manufacturing (AM) process allowing site-specific deposition. Material conversation law with a steady-state heat is applied where the heat generation is measured considering stacking/slipping boundary conditions and the spatial heat flux is incorporated using ANSYS user-defined functions (UDFs). For measuring the temperature evolution throughout the process, the conservation of energy equation is solved where the heat is generated from the dynamic contact between the tool and feed rod interfaces. For material flow, the laminar viscous model is adopted where the feed rod is considered as a non-Newtonian visco-plastic material, and the viscosity and strain rate are temperature-dependent. The simulation results show the temperature evaluation of the deposited material as a highly viscous flow where the temperature is optimized around 20% below the melting point temperature of the feed rod. Since the heat generation depends on the rotational and translational motion of the feed rod, the maximum temperature changes with varying process parameters. Finally, the results of the simulation such as temperature evolution, heat flux, material velocity, etc are exhibited with varying process parameters.
An Investigation on a Novel Soft Metamaterial for Space Applications
Authors: Pulok Mohammad Khairul Habib , Sarker Pratik , Chakravarty Uttam K.
Published: February 2023

Naturally available materials are inadequate in many advanced applications, including space. Therefore, functional materials answer the requirement of operation-specific customized characteristics. Soft matter-based metamaterials exhibit various desired physical properties for space applications in terms of mechanical, optical, acoustic, and electromagnetic behavior. A composite metamaterial is studied in this project comprising an intricate hexagonal-shaped fractal geometry of SU-8 with a soft platinum-catalyzed silicone Ecoflex 00-30 infused in the cavities of the rigid skeleton. The finite element models of the proposed metamaterial are developed for computational study. Mechanical behavior in tensile, fatigue, shear, and modal responses are studied using the finite element model. The von-Mises stress, equivalent strain, total deformation, fatigue life, natural frequencies, mode shapes, etc., are among the properties that are investigated in the computational study. This benchmark cases of similar experimental situations are considered to compare and validate the computational model. Results show that the maximum stress is shared by the hard skeleton, and maximum strain is developed in the soft elastomer regions of the metamaterial. The material properties of hard and soft elastomers imply a change in the modal characteristics in terms of natural frequencies. This type of new functional metamaterials opens new opportunities, especially with the fatigue-resistant performances for applications requiring stretchable materials.
Natural Frequency and Mode Shape of a Shaft With Elastically Mounted Rotary Inertia From Governing Equations With Dirac Delta Function
Authors: Hassanpour Pezhman
Published: February 2023

This paper addresses the exact solution of a shaft’s free vibrations with a concentrated rotary load within its intervals. A new approach in deriving the governing equation of motion of such systems is demonstrated with the fundamental difference from the classic approach being that the dynamics of the concentrated rotary load is taken into account in the partial differential equation rather than the boundary conditions. The properties of Dirac delta functions are used to represent the concentrated loads. The Dirac delta function appears as a coefficient in the governing differential equations. The specific technique to solve such differential equations is presented. The solution derived using this technique is fundamentally identical to the solution of the classic method; however, the proposed approach offers a simplified and more straight-forward route to the derivation of the characteristic equation. As an example of the application of the proposed method, the characteristic equation, natural frequencies, and mode shapes of a shaft with an elastically attached flywheel are derived.
Matrix Pattern Micromarkers for Tracking Local Contractile Movements of Myotubes Cultured on Thin-Film Scaffold
Authors: Hashimoto Shigehiro , Sakai Shusei
Published: February 2023

To measure the distribution of local contractile movements in the layer of the myotubes, the movement of the matrix pattern of micro-markers placed on the back surface of the thin film to which the myotubes were attached has been tracked in vitro. A matrix pattern of micro-markers (diameter 4 μm, height 2 μm, spacing 30 μm) was created on the back surface of a polydimethylsiloxane thin film (thickness 6 μm) using photolithography technology. Mouse myoblasts were seeded on the front surface of the thin film and incubated for 10 days to differentiate into myotubes. Periodic electrical pulses (amplitude 2 V, pulse period 0.5 s, pulse width 1 ms) were applied between the electrodes of the titanium wire immersed in the medium. The movements of both the myotubes and the markers were observed simultaneously with an optical microscope. Experimental results show that the distribution of movement for each marker is related to the local periodic movement of the myotubes layer. A thin film with matrix pattern micro-markers created on the back side may allow in vitro analysis of the distribution of local repetitive contractile movements in the myotubes layer.