bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving Fuel Efficiency of a Boat by Retrofitting Propeller Modelling and Experimental Validation
Authors: Bonthu Satish , Unnthorsson Runar , Sigurbjarnarson Hordur , Gunnarsson Stefán
Published: February 2024

This paper presents the successful retrofitting of an old whale-watching boat incorporating a larger propeller and a new reduction gear. The retrofit resulted in an impressive, 30% improvement in fuel efficiency across the entire operating range of the propulsion system. This significant improvement directly translates to a reduction in carbon emissions, underscoring the project’s importance for further investigation. Given that the propeller contributes to 80–90% of the vessel’s fuel consumption, a detailed analysis of the hydrodynamic performance improvement is warranted. To address this, a cost-effective and efficient computational fluid dynamics (CFD) approach is proposed to qualitatively connect the observed field performance of the vessel with the mechanical performance of the new propeller. The study highlights the accuracy of this approach in realistically predicting the field performance of both the old and new propellers under different operating conditions derived from sea trials. In conclusion, this study demonstrates the potential for retrofitting existing vessels with improved propulsion systems, resulting in increased fuel efficiency and reduced carbon emissions.
A Solution to an Inverse Heat Transfer Problem With Phase Change by Means of Meta-Heuristics and Artificial Neural Networks: A Comparative Study
Authors: Klimeš Lubomír , Kůdela Jakub , Zálešák Martin , Charvát Pavel
Published: February 2024

Many engineering problems involve heat and mass transfer. A typical solution procedure for such a problem represents the determination of thermal behaviour and thermal response of a system under specific conditions, including thermal conditions (initial and boundary conditions) and material-related parameters (thermo-physical properties). Such a problem is referred to as a direct problem. In certain cases, however, some of these conditions or parameters are not known. Instead, information about the thermal behaviour is available. This is the case in which an inverse heat transfer problem has to be solved. Such a problem is actually a data-fitting and optimization task since conditions and parameters, which minimize the error between actual and prescribed data, are searched indirectly. A number of gradient-based methods to inverse problems have been developed in the past. However, they suffer from some disadvantages, including proneness to get trapped in local optima or a low performance in large-scale problems. This is the reason why so-called soft computing methods have experienced great development in recent years. In this paper, seven meta-heuristic algorithms and one algorithm based on an artificial neural network (ANN), referred to as an LSADE algorithm, were applied to the solution of an inverse heat transfer problem with phase change. The problem involved an inverse identification of parameters of an effective heat capacity function, which is a common technique used in phase change modelling. An air-PCM heat exchanger for latent heat thermal energy storage and solar air heating was used as a study case. Results obtained within the scope of the study indicate that the ANN-based LSADE algorithm significantly outperformed other meta-heuristic algorithms, which makes it a very promising tool for the solution of similar kinds of problems.
Basic Research on Music Prescriptions - Second Experiment With Classical Music
Authors: Hishida Hirotoshi , Hashimoto Shigehiro , Saeki Kaito , Kono Hikaru , Hishida Keiko
Published: February 2024

The authors assume that the stress state can be expressed by a value, SMB, and are trying to develop a method to change the value in an appropriate direction by music. This paper compares the results of the music therapy experiment conducted in 2022 with those in 2020. Subjects are recruited and classified into four groups according to whether they know the pieces played and whether they like the music. Some subjects wear the pulse oximeter throughout the concert. Other methods are employed to measure the stress states of all subjects at the beginning, the intermission, and the end of the concert.

Based on the experiment, the possibility of prescribing classical music to patients is recognized. The same music has different effects on the subjects, depending on the type of music and the subject’s characteristics such as gender and whether he/she likes the music. The effects also differ depending on the piano player. In other words, prescribing music would not be simply selecting songs according to the symptoms.

In the future, the music database will be grown up and the experimental methods using public concerts will be improved. Some of the stress measurement methods employed in this experiment may be combined to determine SMD.
On the Delamination of CFRP and Epoxy Adhesive Interface Using Laser Shock Adhesion Test (LaSAT)
Authors: Takagi Aoi , Hosoya Yuichi , Yasuda Shotaro , Ogata Kazuma , Takeda Tomo , Yonezu Akio
Published: February 2024

For a reduction of aircraft structural weight is strongly demanded, Carbon Fiber Reinforced Plastics (CFRP) has been widely used, since it has enormously lightweight and excellent specific strength, compared to metallic materials. In addition, for the joining technology of dissimilar materials, adhesive bonding has been actively developed instead of mechanical fastening such as bolts and rivets. In addition to understanding static mechanical characteristics, the development of advanced transport aircraft needs to clarify dynamic behavior and impact response. However, there are few studies on adhesive bonding strength of CFRP under ultra-high strain rate which ranges from 106 to 107 1/s. To achieve the purpose of bonding strength evaluation under such high strain rate, this study employed Laser Shock Adhesion Test (LaSAT) to evaluate the adhesive strength of CFRP and epoxy resin adhesive under high strain rate. LaSAT, which employs a laser ablation, induces strong shock wave, resulting in interfacial delamination under high strain rate. When the tensile stress wave reaches the critical strength, the interfacial delamination occurs. Moreover, CFRP laminate can change its mechanical property by changing the direction of carbon fiber in each stacking sequence. This study prepared two types of CFRP, i.e. UD-CFRP (Unidirectional fiber reinforcement composite) and QI-CFRP (Quasi-Isotropic composite). Using these two types of CFRP, this study investigated the effect of CFRP stacking sequence on the interfacial delamination morphology due to LaSAT. The delamination morphology and bonding strength of CFRP/epoxy resin adhesive were investigated.
Piezoelectric Energy Harvesting Array of Tethered Bodies Utilizing Flow-Induced Vibrations
Authors: Fam Marina , Roussinova Vesselina , Stoilov Vesselin
Published: February 2024

This paper investigates a mechanical system utilizing flow-induced vibration (FIV) of oscillating bodies in a steady flow. Multiple tethered bluff bodies are elastically mounted and arranged in three different staggered configurations. The hydrokinetic steady water flow is converted to mechanical oscillations via FIV, and the vibration energy is further converted to electrical energy by piezoelectric strips. To achieve the optimal design of the oscillating system, a series of experiments are performed to examine the effect of the optimal spacing between the oscillating bodies. Furthermore, the effect of the flow Reynolds number is investigated in the laboratory conditions for each configuration. The amplitudes and frequency of the oscillations of the mechanical system are analyzed from the measured voltage with the use of a data acquisition system. Furthermore, information for the dominant frequencies, spectra, and power levels is extracted from each individual body to examine the sheltering effect and estimate the power generated by each array configuration. The measured oscillations show that the sheltering effect is greater in the array’s center than at the edges. Moreover, the current experiments showed that the vibrational characteristics of each tethered body are close to the lock-in branch, where the body’s natural frequency matches the shedding frequency as closely as possible.
A Water Saving Device for Home Usage
Authors: Romero Navarrete José Antonio
Published: February 2024

An economy water-saving pedal valve is proposed in this paper, to be used at homes for controlling the water supply at sinks. The reduced cost derives from its conceptual design, which considers standard commercial components, while involves inexpensive manufacturing and assembly processes. Comparative testing of the proposed valve with respect to standard water control devices based upon standard hand-operated faucets, reveals water savings on the order of 50%, for a sample of 10 users. Such saving water characteristic adds to the hygienic quality of the device, due to its hands-free operation. The massive use of this device could represent daily savings of several hundreds of cubic meters of drinking water in a medium size city of 280000 inhabitants.
Machine Learning Based Search for Access Points in Anomaly Detection Model
Authors: Naik Vishnu Gangadhara , Fabarisov Tagir , Morozov Andrey
Published: February 2024

Heterogeneous systems are characterized by a high degree of complexity that poses challenges to conventional anomaly detection methods. One of the challenges is the production of large amounts of data where Deep Learning based Anomaly Detection Models (DLAD) have been demonstrated to outperform conventional techniques in detecting anomalies. However, DLAD models require the manual selection of Access Points, which are specific points in a system from which the training data is recorded. The selection of Access Points is a critical task that can significantly affect the performance of the anomaly detection models. It requires domain knowledge and expertise in the intricacies of the system, which is difficult to acquire and prone to human errors. As the size of the system grows, selecting Access Points becomes increasingly challenging.

In this paper, we propose a new machine learning-based algorithm called the Access Point Search Algorithm (APSA). The aim of APSA is to automate the task of finding the optimal set of Access Points that can aid DLAD models in detecting anomalies in a particular system. The algorithm utilizes a special error detector that dynamically takes in multiple signals and forecasts the signal values. The objective of finding the optimal set of Access Points is formulated as a feature selection problem, which is supervised using a binary variant of the Grasshopper Optimization Algorithm (GOA). We demonstrate the feasibility and effectiveness of the proposed algorithm by deploying it in a Simulink model.

We illustrate the reliability of the proposed algorithm by feeding the signals from all the Access Points in the set provided by APSA into the DLAD model one by one. The reliability is further discussed by carrying out a fault injection experiment on the Simulink model. The proposed algorithm was able to reduce 80% of the Access Points. The Access Points selected by APSA showed a high probability of detecting anomalies over the Access Points that were not selected. The results suggest that the proposed algorithm can efficiently and effectively select the optimal set of Access Points for DLAD models to detect anomalies in component signals. It offers a promising solution to automate the tedious and error-prone task of selecting Access Points, thereby reducing the domain knowledge and expertise required.
Workspace Specific Robot Arm Design
Authors: Parhofer Christoph August Wilhelm , Pancheri Felix , Rehekampff Christoph , Lueth Tim Christian
Published: February 2024

In this paper, a new design method for serial robot arms is presented. The method aims to reduce the number of joints by customizing the connecting shape of a robot arm between its joints. For that, the classically straight shape of a robot arm is redesigned, depending on the workspace with its obstacles, the motion path and the location of the robot base. The focus of this work is the automated customization of such arms in MATLAB, by designing individual extrusion splines for each arm, in each environment. The design methodology is exemplarily implemented and validated on an in-house developed 4-DoF robot arm in different workspaces. For this purpose, the originally straight arm structures of the 4-DoF robot arm between the 2nd and 3rd joint as well as the 3rd and 4th joint are removed and replaced by the reshaped arm structures. To easily produce and change the arms in each environment at low cost FDM printing and snap fittings for the arm connections are used. Two examples of such reshaped arms are shown in this work for validation.
Evaluation of the Impact of COVID-19 on the Automotive Industry: Analysis of the Effects of Confinement on a Hybrid Vehicle
Authors: Carrera Rivera Gabriel , Espinoza-Andaluz Mayken , Ordóñez-Saca Brayan , Santana-Villamar Jordy
Published: February 2024

The COVID-19 pandemic has significantly impacted several aspects of daily life, including transportation. The transportation sector influences pollutant gas emissions and the economies of society. One solution to reduce emissions is to use hybrid or electric vehicles, which employ clean technologies and improve efficiency. This article analyzes production stoppages, decreased demand due to mobility restrictions, and interruptions in the supply chain for vehicle production during the pandemic. The effects of these variables on sales and production of hybrid vehicles in Ecuador and worldwide are also examined. The article presents a study on the damage caused by the disuse of a vehicle within a high-voltage hybrid charging system. It also proposes an analysis of a high-voltage battery set’s recovery and maintenance processes in a hybrid vehicle. Using test benches to analyze battery cells, categorizes the cells of the high-voltage battery body according to their state of charge. The results show that the vehicle’s high-voltage charging system was affected during the pandemic, with more than 50% of its cells in lousy condition. However, some cells can still undergo balancing and maintenance processes to form another set of cells for a high-voltage battery.
Origami-Inspired Cylindrical Structures for Energy Absorption in Aerospace Applications
Authors: Hussain Khaja Fayaz , Cantwell Wesley J. , Khan Kamran A.
Published: February 2024

The current work emphasizes on hybridization of the cylindrical curved crease origami structure with high energy absorbing state-of-the-art cellular lattices mainly, the plate, truss, and hourglass lattices, with a motive to enhance the energy absorption capability of the structure. A novel non-hybridized curved crease cylindrical origami namely star curved and three of its hybridized counterparts, star curved plate (S.C.P), star curved truss (S.C.T) and star curved hourglass (S.C.HG) are proposed in the paper and the effect of hybridization on the energy absorption properties was investigated. Additionally, the deteriorating effect of moisture on the mechanical properties and energy absorption characteristics was emphasized and it was observed that the dried samples outperformed the as-fabricated samples. The structures were designed with the help of CAD software and fabricated via fused filament fabrication (FFF) due to its capability of providing geometrical flexibility and precise control of micro architecture and dimensions using Nylon polymer. The structures were later tested on an Instron compression testing machine to obtain the force-displacement data for further processing. The results substantiate the validity of the hybridization approach as the specific energy absorption of the non-hybridized structure was enhanced from 4 kJ/kg to 6.6 kJ/kg. Moreover, the mechanical properties like peak strength and elastic modulus were remarkably improved from 1.3MPa to 6.5 MPa and 41 MPa to 290MPa respectively. The proposed approach leads to an increase in possibilities for improving the origami-inspired structures in terms of specific energy absorption for situation-specific applications and when incorporated into sandwich panels, the performance of these structures can further be explored.
An Investigation on the Aerodynamic Characteristics of An Electroactive Membrane
Authors: Ojo Oluwatosin , Su Ji , Chakravarty Uttam K.
Published: February 2024

Dielectric elastomer membranes are electroactive polymers that can generate large linear actuation strains likened to muscles when acting as an actuator. These membranes can both release and store elastic energy due to the elasticity of the materials when acting as an elastomer. Unique mechanical properties like low modulus, flexibility, and electrical induced deformation make the dielectric elastomer membrane an ideal material that can mimic the resonant actuation found in insects and winged mammals while simultaneously solving the complex transmission mechanism found in conventional unmanned aerial vehicle designs. The objective of this study is to computationally evaluate the aerodynamic characteristics and response of the dielectric elastomer material, VHB 4910. The result from this analysis validates the experimental aerodynamic responses from the material’s wind tunnel testing. The computational environment with flow conditions maintained at a low Reynold’s number suitable for the control of flow in micro air vehicles is used to analyze the fluid-structure interaction of the models. The standard and explicit model coupled with the computational fluid dynamic model of the surrounding air creates a cosimulation analysis. As the angle of attack increases, the coefficient of lift experiences a rise until it reaches a critical value, while the coefficient of drag also goes up.
Warehouse and Logistics Ergonomics Optimization Through Real-Time Evaluation of the NIOSH Index
Authors: Lanzoni Daniel , Negrello Francesca , Vitali Andrea , Regazzoni Daniele , Catalano Manuel G. , Rizzi Caterina
Published: February 2024

Logistic activities can cause long-term musculoskeletal problems due to repetitive and incorrect movements, heavy loads, and uncomfortable positions. Ergonomic evaluations are conducted to prevent these risks, optimize workstations, and work processes. Some studies use automatic evaluation of ergonomic indices or frameworks for optimizing workstations and logistics reorganization. However, optimization is often disconnected from real-world case studies. This research work validates a new approach that integrates an automatic ergonomic evaluation and optimization in real-world scenarios, comparing this analysis with traditional manual evaluation method. Our approach is applied to a real logistics case study using a wearable motion capture system and an interactive interface that displays the Digital Twin of the analyzed task. Results show that our approach provides a more accurate evaluation of the ergonomics and an evident time-saving.
Automated Design of Custom Printed Circuit Board Enclosures With Integrated Cooling Capabilities
Authors: Pancheri Felix , Sun Yilun , Parhofer Christoph August Wilhelm , Rehekampff Christoph , Zhang Dingzhi , Lueth Tim C.
Published: February 2024

Power electronics or processing units generate significant amounts of heat during operation, which must be dissipated. At the same time, there is a trend towards the production of small quantities of individual printed circuit boards. Thus, more and more individual cooling solutions for printed circuit boards are required. Conventionally, individual components on printed circuit boards are cooled using commercially available heat sinks. Housing the printed circuit board inside an enclosure can affect the cooling performance of heat sinks. If a printed circuit board is unusually shaped or a particularly compact design is required, suitable prefabricated enclosures are not necessarily available. In these situations, enclosures designed specifically for an individual printed board can be used. Custom designed enclosures made of materials with sufficiently high thermal conductivity can serve directly as heat sinks. In this work, an automated design process of custom dual-purpose enclosures for printed circuit boards with integrated cooling capabilities is proposed. The automated design process is based on the Solid-Geometry (SG) Library, a MATLAB-toolbox for automated design of surface models and optimized for additive manufacturing methods. Based on a geometry model of the printed circuit board, a suitable enclosure is automatically designed. In addition, several design examples are also presented to demonstrate the feasibility of the proposed approach.
Numerical Simulation Research on Thermal Energy Storage Characteristics of a Cascaded Packed Bed With Phase Change Material
Authors: Zhao Bingzhou , Wu Junjun , Fu Qian , Liao Qiang , Cheng Min
Published: February 2024

Latent heat storage technology is an efficient way of heat storage due to its high energy storage density and stable energy storage temperature. Cascaded latent heat storage (CLHS) is a promising technology to improve the heat transfer rate and energy efficiency in the packed-bed thermal energy system (PBTES). In this paper, a 1-D two-phase model is established to study the thermal performance of cascaded latent heat storage (CLHS) system. The study used energy and exergy analysis theories to investigate the effects of heat transfer fluid (HTF) flow rates, HTF inlet temperatures, and layout of PCMs on thermal performance of PBTES. The indexes of heat storage density, average heat storage rate, effective heat storage time and exergy efficiency are used to compare the performance of single-PCM and CLHS systems. The results show that the CLHS system has a higher heat storage and thermal density compared with single-PCM heat storage systems. The exergic efficiency of CLHS is 0.93, which is much higher than PBTES. And increasing the inlet temperature or fluid flow rate can be the effective way to improve the thermal performance of packed bed thermal energy system.
Energy Efficiency Improvement Through Pumping System Modeling and Analysis
Authors: Jones Spencer , Languri Ethan
Published: February 2024

In this paper, the operation of the raw water pumping system for a water treatment plant is redesigned to sequence pump operation and improve energy efficiency. Using field data for the pump system’s flow, power, and head pressure, the parameters for the new pump operation sequence are set. By defining the system operation to use the more efficient pumps to satisfy base load conditions, the system inefficiency is diminished. Secondly, field data analysis revealed a persistent overlapping of pump operation, where multiple pumps would operate at one moment only to cause an unnecessary increase in head pressure as required flow had already been achieved.

The system analysis uses the total system flowrate as its control parameter. In the new system operation, the most efficient pump is loaded to its best efficiency point (BEP) then the remainder flowrate is given to the following pumps based on their efficiency. With an absence of pump curves, a variable speed drive (VSD) speed versus motor power relation can be made to predict, with a polynomial data fit, the motor power at calculated VSD speeds. With system operation sequenced by efficient motors and keeping head pressure near constant, a decrease in energy usage of 29.6% is demonstrated over the duration of the field data.

The proposed system operation is shown to operate remainder flow rate pumps at partial loads below their minimum design flowrate, due to the need to keep total flowrate parameter constant. By highlighting these operation points below the minimum design flow rate, the flow rate must be increased to that minimum for the pump, thus proposed operation is simulated with a slightly increased average flow rate.

The pump system is comprised of 4 centrifugal raw water pumps, one 200 HP and three 150 HP, with an average annual flowrate of 9,200 GPM. The raw water pumping system moves raw water from the federally managed water source to the treatment plant. The proposed system operation would be performed by a motor controller capable of managing at least four pumps at different sites as one pump is separated from the other three pumps. The specifications defined by the analysis in this study would be parameters for the controller programming along with the predicted performance after controller implementation. Analytical characteristics of such controllers are discussed along with their effect on the total pumping system. Finally, the economic impact and carbon emissions reduction of the proposed operational design are discussed.
Development of a Novel Hybrid Soft Cable-Driven Parallel Robot
Authors: Ovando Ammy , Papendorp Sky , Ashuri Turaj , Amiri Moghadam Amir Ali
Published: February 2024

This paper reports on the development of novel hybrid soft cable-driven parallel robots (HSCP). As the growth and refinement of the soft robotic field progresses, new methods of soft robotic actuation and control will continue to be developed. While most of the existing soft robotic systems have a serial structure, soft parallel robots have received a lot of attention recently. This is due to the wide range of applications of these systems in different industries such as the medical and the food industry. To the best of our knowledge, most of the existing soft parallel robots have active flexible legs. However, in this work for the first time, we have proposed a novel soft parallel robot with only passive flexible legs. In our hybrid design the stiffness of the robot is maintained through the passive soft legs and the actuation is based on a cable-driven mechanism. This will simplify the design and modeling of the robot. As an example of our design approach, a 6 degrees of freedom (DOF) hybrid soft parallel robot is designed which resembles the rigid Stewart mechanism. The mechanics of the robot are unique, being controlled only through cable actuation through six servo motors positioned around the base of the robot. The supports which were 3D printed with deformable Ninja Flex filament supply a nonlinear force to the robot, combined with the cable control enabling the robot to be able to execute basic movement within the workspace as well as being safer for human-machine interaction due to the soft support system. This paper also compares the kinematics and controls of this new robotic system to a typical rigid steward robot.
Material Model Parameters Optimization in Liquid Mercury Target Dynamics Simulation With Machine Learning Surrogates
Authors: Lin Lianshan , Tran Hoang , Radaideh Majdi I. , Gorti Sarma , Simunovic Srdjan , Jiang Hao , Winder Drew , Cousineau Sarah
Published: February 2024

A pulsed spallation target is subjected to very short (∼0.7μs) but intense loads (23.3 kJ) from repeated proton pulses, which knock away neutrons from the mercury atoms’ nuclei for a wide range application in physics, engineering, medicine, petroleum exploration, biology, chemistry, etc. The effect of this pulsed loading on the stainless-steel target module which contains the flowing mercury target material is difficult to predict not only due to its short but intense explosive-like physical reaction, but also the nonlinear material behavior of the liquid mercury in the structure. Injecting small helium bubbles in the mercury has been an efficient method of mitigating the pressure wave at high power level stage. However, prediction of the resultant loading on the target is more difficult when helium gas is intentionally injected into the mercury. A 2-phase material model that incorporates the Rayleigh-Plesset (R-P) model is expected to address this complex multi-physics dynamics problem by including the bubble dynamics in the liquid mercury. A parameter sensitivity study was firstly employed to understand their impact on the simulation strains. The investigated parameters included E, μ, γ, σ, n, VFgas, and gas cumulative volume curve control parameters a and b. Verification and validation results from sparse polynomial expansions (SPE) method and directional Gaussian smoothing (DGS) optimization show that the surrogate model had training error of ∼7% and validation error of ∼15%, indicating that machine learning methods and surrogate models can help optimize the uncertain parameters in the complex 2-phase material model. This approach is expected to fill the knowledge gap between unknown liquid-gas mixture material model and measured vessel strain responses.
Effect of Nonlinearities on the Vibration Reduction Performance of a System With Multiple Nonlinear Tuned Mass Dampers
Authors: Ekici Yigitcan , Cigeroglu Ender
Published: February 2024

In this study, a single-degree-of-freedom structure with multiple nonlinear tuned mass dampers is investigated. A sinusoidal excitation is assumed to be applied to the structure. In order to obtain the results, a nonlinear mathematical model of the general system is obtained in the form of a set of nonlinear ordinary differential equations. Dry friction and cubic stiffness nonlinearities are considered for the nonlinear terms. To obtain steady-state frequency responses of the system, these nonlinear ordinary differential equations are transformed into a set of nonlinear algebraic equations by using Harmonic Balance Method. Fourier transformation is used in the calculation of the Fourier coefficients of the nonlinear forcing terms. Then, numerical solutions to the resulting nonlinear algebraic equations are obtained using Newton’s Method with Arc Length Continuation. The effect of the number of tuned mass dampers and their arrangement, i.e. in series or in parallel, on vibration reduction is observed by performing optimization on several cases and comparing them. In order to observe the separate and combined effects of the nonlinearities, and the number of tuned mass dampers used, several case studies are carried out using optimized case parameters with different combinations of the nonlinearities. The results of these case studies and the linear model are compared with each other to see the effect of the nonlinearities. Additionally, results of the system with optimum nonlinear tuned mass dampers are compared with that of the optimum linear tuned mass dampers and the effect of nonlinearities are discussed.
Optimization of the Flow Parameters for a Liver Organ-on-a-Chip Computational Model
Authors: Pinto Edgar , Carvalho Violeta , Rodrigues Nelson , Rodrigues Raquel O. , Lima Rui A. , Teixeira Senhorinha
Published: February 2024

The organ-on-a-Chip (OOC) concept appeared intending to increase the efficiency and effectiveness of R&D activities, and open doors to precision and personalized medicine. However, for such devices to provide adequate results, they must mimic a specific human microenvironment with great accuracy. In the present work, a computational model of an organ-on-a-chip model was developed and optimized by evaluating the effectiveness and characteristics of some optimization methods. To perform the optimization and simulation, a geometry appropriate to the needs was first designed, having in base the current literature. After that, a mesh set capable of maintaining a balance between the accuracy of the results and computational performance was generated and a mesh study was conducted. Then, the simulation and optimization were performed. The latter was conducted by applying two different methods, the Multi-Objective Genetic Algorithm (MOGA) and Nonlinear Programming by Quadratic Lagrangian (NLPQL), for later comparison of results. Bearing in mind the hemodynamics in the liver, the goal of this optimization was to minimize the organ model blood flow mean velocity, in order to allow the adequate transfer of substances between the blood and liver cells.
Effect of Wear on the Forced Response of a Shrouded Blade
Authors: Cardak Aykut , Cigeroglu Ender
Published: February 2024

Dry friction damping is a commonly used approach in reducing resonant amplitudes in turbomachinery vibrations to prevent High Cycle Fatigue (HCF) failure of the blades in turbines or compressors. Intentional friction contact provides additional damping to the overall system by means of dry friction; however, predicting the forced response of frictionally constrained structures can be challenging due to the nonlinear nature of the problem. Although previous studies have worked on designing and mathematical modelling of various friction dampers, the effect of cumulative wear degradation on the structure over the operational lifetime is often underestimated. In this paper, the finite element model of a shrouded blade is used for this purpose as a case study. Harmonic Balance Method (HBM) in conjunction with Receptance Method (RM) is utilized to formulate the nonlinear algebraic equations of motion which are solved in frequency domain. In this study, one dimensional dry friction element with normal load variation is used in modeling friction contact. Alternating Frequency Time (AFT) method is used to obtain the harmonic coefficients, also known as Fourier coefficients, of the nonlinear forces introduced by frictional contact. Additionally, the well-known wear-energy method, which predicts the wear degradation at the contact interface is coupled to the nonlinear forced response analysis. This study aims to investigate how wear affects the dynamic response, performance, and reliability of the shrouded blade case study considered.
Heat Transfer and Combustion Processes in the OSU Calorimeter for Rate of Heat Release Predictions
Authors: Cappello Garrett , Farouk Bakhtier
Published: February 2024

Various calorimetric devices and measurement methods have been used historically in obtaining heat release rates of materials. A comprehensive ANSYS-Fluent computational fluid dynamic model for the full-scale OSU (Ohio State University) reactor is under development for the prediction of the flow, heat transfer and heat release characteristics of the reactor. The validated model will serve as a benchmark for providing uniformity in predictions of the OSU reactors located in different laboratories. A validated model will also provide better understanding of the flow and heat transfer characteristics in the OSU reactor.
In-Situ Shear Exfoliation of Graphene From Graphite Polymer Nanocomposites for Lung and Heart Motion
Authors: Rahman Md Ashiqur , Salam Md. Abdur Rahman Bin Abdus , Ashraf Ali
Published: February 2024

Graphene-based nanocomposites have become attractive for different applications such as energy storage, sensors, biomolecule detection, biomedical, healthcare, and wearable devices due to their unique mechanical, electrical, and thermal properties. However, using commercial graphene for making nanocomposite devices can be expensive, and fabricating nanocomposites can be challenging due to impurities while transferring graphene to elastomer composites. In this study, we used a simple, inexpensive in-situ shear exfoliation method to produce graphene from graphite directly within the elastomer. As the graphene in the elastomer reached beyond its percolation or threshold, electrons hop or tunnel around from one graphene flake to another. So, the as-prepared nanodevices are piezoresistive in nature, and the resistance changes whenever there is a change in distance between graphene flakes. The abovementioned devices were able to detect podiatric pressure, heart, and lung motion (left and right rectus abdominis). The nanocomposite strain possesses high sensitivity, a conductivity of ∼20 S/m (measured by ASTM D4496 - Standard Test Method For D-C Resistance or Conductance of Moderately Conductive Materials), excellent stretchability, and ultra-sensitivity (heart rate was measured 100 BPM). Thus, these graphene-enhanced elastomeric composite (referred to as G-EMC) devices can be an excellent platform for healthcare applications like heart and lung motion detection.
An Investigation of the Influences of Diameter Ratio and Attaching Angle on the Performance of a Helical-Bladed Combined Darrieus-Savonius Wind Turbine
Authors: Saad Ahmed S. , Ahmed Mahmoud
Published: February 2024

Although Darrieus wind turbines are capable of producing high power coefficients, they also exhibit a low self-starting capability. Savonius wind turbines on the other hand are capable of providing relatively high self-starting capabilities but have a lower power coefficient. The objective of the present study is thus to develop a modified design of a combined Darrieus-Savonius wind turbine in order to improve its self-starting capability and power coefficient. The modified combined design consists of helical-bladed Darrieus and Savonius rotors with helical angles of 90 and 45 degrees, respectively. The influences of various diameter ratios in addition to various attaching angles between Darrieus and Savonius rotors in the proposed design are numerically investigated.

The Reynolds-Average Navier-Stokes equations in three dimensions along with the turbulence model of k-ω (SST) are developed and numerically simulated. The predicted results are validated using the available measurements. Thus, numerical predictions of the variations of the coefficient of power versus tip speed ratio as well as the coefficient of torque over a whole cycle can be made. As part of the evaluation of the starting characteristics of the proposed configurations, the static torque coefficient during a complete revolution is also calculated.

Based on the current study, some significant findings can be derived. The coefficient of power remarkably increases with rising the diameter ratio up to an optimal value of 0.45, then a significant reduction in coefficient of power is observed with further increment of diameter ratio beyond 0.45 due to increasing the drag losses by Savonius rotor. In comparison to a solo Darrieus rotor at the same dimensions, the combined turbine with the best design parameters achieved a peak coefficient of power of 0.386 with a performance gain of about 19 %. Furthermore, the combined design significantly reduces the fluctuations of coefficient of static torque in addition to achieving a higher average coefficient of static torque with positive values at all azimuth angles compared to solo Darrieus rotor.
Study of Adhesive Joints Quality Based on Multi-Camera DIC System
Authors: Guo Bicheng , Gao Zhongfang , Gerini-Romagnoli Marco , Yang Lianxiang
Published: February 2024

Carbon and glass fiber-reinforced plastic (CFRP and GFRP) composites have gained popularity in various industries and settings owing to their exceptional strength-to-weight ratio, corrosion resistance, fatigue resistance, and design flexibility. Adhesives are commonly utilized to bond carbon fiber reinforced plastics to other materials or to themselves. Bonded joints have been found to enhance the mechanical characteristics of materials, while also reducing additional costs for practical applications. The bonding region’s strength can be influenced by different material combinations and substrate thicknesses. The present investigation employed a double-sided multi-digital image correlation (DS-Multi-DIC) system to quantify the deformation and fracture mechanisms of adherends during tensile testing. The primary objective was to assess the static impact on the strength of the bonded zone under tensile loading. The system comprises of two stereo vision DIC measurement systems, wherein each system comprises of two GigE cameras. These cameras are positioned at the front and back of the sample, respectively the process of system calibration involves the utilization of the double-sided calibration technique to integrate the coordinate systems of the two DIC measurement subsystems with the global coordinate system. This enables the direct measurement of deformation and strain in three dimensions. This paper examines the impact of adhesive thickness and type on the strength of the bonded area and fracture mechanism by analyzing the alteration in strain distribution and maximum strain during static stretching. The study yielded a conclusion that the magnitude of the bonded region’s strength is positively correlated with the thickness of the bonding material. The cohesive force of the bonded region is positively correlated with the malleability of the adhesive bond. Furthermore, an examination was conducted on the impact of adhesive thickness and type on peeling strain. As the bond’s bending stiffness diminishes, there is a corresponding increase in the peel strain it undergoes. Furthermore, a succinct description is provided regarding the unequal allocation of auditory alterations that occur during stationary stretching.
Physics Based Electrolyte Evaporation Model for Use in Li-Ion Thermal Runaway Simulations
Authors: Poe Dylan , Parhizi Mohammad , Jain Ankur , Kilaz Gozdem , Ostanek Jason
Published: February 2024

Numerical analysis of thermal runaway and propagating failures often relies on solving the transient heat conduction equation. Exothermic decomposition reactions create a heat source within the active material. The generated heat diffuses through the cell via heat conduction and is carried away from the cell via conduction, convection, and radiation. However, many studies neglect the evaporation of liquid electrolyte from the battery cell after the vent mechanism activates despite evidence that evaporation significantly affects the time-to-thermal-runaway. In studies which have considered evaporation of electrolyte, the rate of evaporation was modeled using a semi-empirical relationship instead of rigorous theoretical analysis. This work presents a new, physics-based evaporation model in which the mass transfer of electrolyte in the jellyroll is treated as a 1-D liquid diffusion process. Experiments were conducted to determine the diffusion coefficient of electrolyte through the porous separator material. The 1-D liquid diffusion model was then integrated within an existing battery thermal abuse model. The thermal abuse model with physics-based electrolyte evaporation model was exercised for oven tests at 150 °C and 155 °C and compared with published experimental data. Simulated results agreed well with experimental data, capturing the characteristic temperature drop after vent activation. The model may be used to further investigate the role of electrolyte evaporation on thermal runaway and propagating failures.
Numerical Study on CO2 Hydrate Formation in a Bubble Column Reactor From Flue Gas Mixtures
Authors: Bhati Awan , Kar Aritra , Bahadur Vaibhav
Published: February 2024

Gigascale carbon capture and sequestration (CCS) is increasingly seen as essential to meeting the targets of the Paris Agreement. Sequestration of CO2 as CO2 hydrates (ice-like materials of CO2 and water) has received research attention recently. CO2 hydrates form at medium pressures and temperatures close to freezing from a water-CO2 gas mixture. Bubble column reactors (BCR) are a preferred way of rapidly forming CO2 hydrates. This study uses a recently-developed and validated model to predict performance of a BCR for CO2 hydrate formation from flue gas (CO2/N2). In particular, two performance parameters are analyzed, the gas consumption rate for hydrate formation, and the fraction of CO2 that can be converted to CO2 hydrates (conversion factor). Extensive parametric analysis is conducted to study the influence of pressure, temperature, CO2 mole fraction at inlet, inlet gas flow rate, reactor height and reactor diameter on CO2 hydrate formation rate. Across the range of simulations conducted in this study, the maximum reported hydrate formation rate is 71 ton/yr and the highest conversion efficiency is 67.8%. It is seen that both the performance parameters improve with increasing pressure, decreasing temperature and increasing inlet mole fraction of CO2. Increasing gas flow rate increases the gas consumption rate (i.e., hydrate formation rate) but reduces the conversion factor. This suggests that the operation of BCR for gas separation should involve low flow rates but that high flow rates should be used to synthesize hydrates for CO2 sequestration. An increase in reactor volume by increasing the height or diameter, improves hydrate formation on both performance parameters (rate, conversion factor).
Improving CFD Simulations by Local Machine-Learned Corrections
Authors: Mitra Peetak , Haghshenas Majid , Dal Santo Niccolo , Daly Conor , Schmidt David P.
Published: February 2024

High-fidelity computational fluid dynamics (CFD) simulations for design space explorations can be exceedingly expensive due to the cost associated with resolving the finest scales. This computational cost/accuracy trade-off is a major challenge for modern CFD simulations. In the present study, we propose a method that uses a trained machine learning model that has learned to predict the discretization error as a function of large-scale flow features to inversely estimate the degree of lost information due to mesh coarsening. This information is then added back to the low-resolution solution during run time, thereby enhancing the quality of the under-resolved coarse mesh simulation, aposteriori. The use of a coarser mesh produces a non-linear benefit in speed while the cost of inferring and correcting for the lost information has a linear cost. We demonstrate the numerical stability of a problem of engineering interest, a 3D turbulent channel flow. In addition to this demonstration, we further show the potential for speedup without sacrificing solution accuracy using this method, thereby making the cost/accuracy trade-off of CFD more favorable.
Effects of Knee Hyperextension on Transtibial Amputate Gait
Authors: Moreno-Agudelo Daniel , Ortega-Bedoya Yessika , Valencia-Legarda Fanny , Rendon-Velez Elizabeth
Published: February 2024

This article presents an exploratory study investigating the kinematic variations made by transtibial amputees during gait with knee hyperextension. Other authors have studied other abnormal amputee gait patterns like circumduction or vaulting. The within-subject study involved 20 participants and used the MVN Awinda Motion Capture System to record kinematic variables during gait cycles. Knee hyperextension was induced by using a 3D-printed outsole placed on the prosthetic foot in order to restrict the ankle dorsi-flexion angle. The condition was verified by inspecting the kinematic curve of this joint in the sagittal plane. After this inspection, two groups were identified based on flexion-extension angles during mid-stance: one group had a constant flexion-extension angle during this sub-phase and the other one had a fluctuating angle. Differences between control and hyperextension trials were found in ankle, knee, and hip joints. Group 1 showed higher values for ankle flexion on the healthy limb during all gait events in the control trial and higher hip abduction and shoulder flexion during all gait events during hyperextension trials. Group 2 presented higher values for the healthy knee abduction during heel strike and load response and hip abduction on the amputated side during load response and terminal extension during knee hyperextension trials. Future studies should consider using physiological information such as electromyography to deepen understanding of this abnormal gait pattern. These findings have important implications for early diagnosis and prevention of future difficulties resulting from knee hyperextension in transtibial amputees. The presented findings can be implemented in the creation of automated gait pattern detection algorithms as well.