bluuebunny/crossref_metadata_2025 huggingface dataset:
Conceptual Architecture of Digital Twin With Human-in-the-Loop-Based Smart Manufacturing
Authors: Kim Duck Bong , Bajestani Mahdi Sadeqi , Shao Guodong , Jones Albert , Noh Sang Do
Published: February 2024

This paper proposes a conceptual architecture of digital twin with human-in-the-loop-based smart manufacturing (DH-SM). Our proposed architecture integrates cyber-physical systems with human spaces, where artificial intelligence and human cognition are employed jointly to make informed decisions. This will enable real-time, collaborative decision-making between humans, software, and machines. For example, when evaluating a new product design, information about the product’s physical features, manufacturing requirements, and customer demands must be processed concurrently. Moreover, the DH-SM architecture enables the creation of an immersive environment that allows customers to be effectively involved in the manufacturing process. The DH-SM architecture is well fitted to those relatively new manufacturing processes, such as metal additive manufacturing, since they can benefit from using digital twins, data analytics, and artificial intelligence for monitoring and controlling those processes to support non-contact manufacturing. The proposed DH-SM will enable manufacturers to leverage the existing cyber-physical system and extended reality technologies to generate immersive experiences for end users, operators, managers, and stakeholders. A use case of wire + arc additive manufacturing is discussed to demonstrate the applicability of the proposed architecture. Relevant development and implementation challenges are also discussed.
Ergonomic Design of a Virtual Proctor System With Reliable Face Recognition and Tracking
Authors: Zhang Zhou , Chang Yizhe , Esche Sven K.
Published: February 2024

The function of proctors is to detect academic improprieties during examinations, tests, and laboratory experiments. With the breakout of the pandemic, many institutions went to online operation, which rendered a difficulty to the exams and tests. Then, various remote proctoring methods are employed. Virtual proctor (VP) systems that replace continuous human supervision with video surveillance are starting to become popular in distance education, despite their most common shortcomings, which include their vulnerability to pose translations of the learners and their de-pendency on the illumination conditions of the environment. As a result, virtual proctor systems impose extra constraints on the movements of the learners being monitored, and thus they may feel uncomfortable when being subjected to virtual proctoring. At present, in the design of VP systems, sufficient consideration of human factors and ergonomics is typically not given.

To overcome these shortcomings, a video-based VP system with a reliable two-stage face recognition and tracking method is proposed here. First, the face region is detected and cropped out from the video frames by a combination of eye, mouth, and face detection. After that, to render the usage of the VP system more comfortable for the learners being monitored, a modified face recognition method based on a proposed improved real-time stereo-matching algorithm is employed to track the learners’ movements. The VP system is capable of identifying a limited set of pre-defined suspicious behaviors that may represent cheating. In order to evaluate the efficiency of the proposed methods, two benchmark analyses with respect to the effect of pose translations and varying illumination conditions on the effectiveness of the VP system are presented. It is asserted that the proposed VP system is simpler to use than prior solutions and realizes an ergonomic design that makes the learners monitored more comfortable.
Feedback Guided Self Training Balance Equipment for Physical Therapy and Elite Athlete Use
Authors: Tatoglu Akin , Wilson Katharine , Chabot Alexandra , Marcelin Jarel , Campana Claudio , Arico Mary Cater
Published: February 2024

Balance boards are useful tools for a wide range of purposes. An example of a balance board is a wobble board, a circular plate mounted atop a hemisphere. Some wobble boards have variable difficulty, making them suitable for any type of physical conditioning — from elite athletic training to rehabilitation for elderly populations. Wobble boards are strictly mechanical devices, used only to obtain an assumed state of balance by the consumer. However, our goal is to design and validate a functioning interactive wobble board using an inertial measurement unit (IMU). The design features an IMU and Bluetooth communication to continuously stream the position, velocity, and acceleration of the user to a smart device (phone or tablet). An interactive game-like training exercise app will both simulate and record the user’s balance and coordination. The app will guide the user to follow a specific pattern, and their simulated movements on the board will be compared to the expected movements. Both the pattern difficulty and speed may be assigned by clinicians or trainers depending on training type. This wobble board prototype will help to strengthen muscles and joints to both heal and prevent injury, as well as enhance performance. Methodology to transform frameworks, setting up different regimens and practices, a set of experiments and benchmarking plots are shared at the end of the paper.
Dynamometer Testing of Hydrokinetic Turbines in a Towing Tank Facility
Authors: Rouhi Shahab , Xiros Nikolaos I. , Sadeqi Setare , Birk Lothar
Published: February 2024

This paper discusses a methodology for testing hydrokinetic turbines used to convert energy from water currents into electrical power. These turbines are designed similarly to wind turbines, but instead of using air, they use water to generate rotational kinetic energy that drives an electric generator. The hydrokinetic turbine considered in this research is of the open-flow, horizontal-axis three bladed type. To test this turbine, a methodology is proposed that utilizes a towing tank commonly used for naval architecture purposes. The methodology involves attaching an electro-machine to a 3D-printed turbine model and placing it in a 3D-printed watertight nacelle with sensors to record parameters such as rpm, torque, voltage, and current. The nacelle is then attached to the towing tank carriage and fully submerged at a carefully selected depth to perform the tests. The results of the tests allow the derivation of important parameters for the turbine’s hydrodynamic characteristics, such as torque and output power. The ultimate goal of this work is to propose a standardized and independently verifiable procedure for dynamometer testing of scale model wind turbines.
Factors Affecting the Behavior of a Fixed Quantity Fuel Spill
Authors: Islam Mehran , Duarte Juliana Pacheco , Lattimer Brian Y.
Published: February 2024

Fuel spills are a major hazard in industrial environments with the size of the spill dictating how severe a fuel spill fire can be. Though several experimental studies have been undertaken, there is still uncertainty on the relative importance of the key effects that dictate spill conditions and spill dynamics. A computational study was conducted to quantify the relative importance of different spill behavior conditions using the design of experiments. Two-dimensional simulations were conducted using ANSYS Fluent to determine the spill length and depth of a fixed quantity of fuel (0.5 L). The effects of fuel density, fuel viscosity, fuel surface tension, and surface roughness on spread dynamics and dimensions (length and depth) were observed. The statistical significance of the different parameters on spill length and depth was quantified using the JMP software. Results indicated that the fuel density and surface tension had the most significant impact on the spread length and depth of a spill. Subsequently, the high-density fuels spread further with a smaller spill depth whereas the fuels having a higher surface tension settled into a smaller spill with a thicker fuel layer. Although viscosity did not significantly affect the overall spread dimensions, it influenced the oscillating motion of the fuel spill resulting in advancing and receding motions.
Computational Analysis of Heat Recovery From Simple Cycle Gas Turbine Exhaust Stacks Through the Silencer Semi-Circular Sections
Authors: Faqihi Bouria , Ghaith Fadi A.
Published: February 2024

The challenge with exhaust heat recovery is that placing additional heat transfer surfaces in the exhaust flow path leads to pressure drop; which lowers the gas turbine (GT) performance. One way to overcome the increase in the pressure drop is to enlarge the exhaust flow path. However, that is associated with similar capital and space constraints as combined cycle (CC) conversion. This paper investigates the potential of integrating heat transfer channels within the existing semi-circular section of the exhaust silencer baffles of simple cycle (SC) gas turbines, in order to avoid such an exhaust flow path enlargement. A heat transfer fluid in the channels absorbs GT exhaust waste heat flow across the silencer. The heated fluid was utilized in the fuel gas pre-heater, leading to reduced fuel gas usage at the same GT output.

In this paper, a computational model of the integrated heat exchanger was developed, and compared to an existing mathematical model; showcasing the computational fluid dynamics (CFD) results of the model.

After describing the system, the paper describes the computer aided design (CAD) setup of the heat transfer model and flow channel details. The mesh setup and mesh independence study for optimal CFD analysis were conducted. The CFD setup, methodology and results using Ansys Fluent are described.

The computational model was successful in estimating the convective heat transfer coefficient, heat exchanger outlet temperatures and flow rates. The proposed system resulted in 2.3 MW heat recovery rate. It was found that while the existing mathematical model over-predicted the heat recovery, the system still provides significant net power gain and reduction in CO2 emissions.

The CFD flow visualization allowed for a greater understanding of the exhaust flow parameters enabling the localization of areas with maximized heat transfer coefficient potential. Utilizing this knowledge, areas of improvement for the heat transfer passages were identified; and future work proposed.
Holographic Terahertz Imaging for Breast Cancer Detection
Authors: Wang Lulu , Al-Rawi Mohammad
Published: February 2024

Terahertz (THz) imaging is a promising technology that can accurately detect breast tumors during breast-conserving surgery. Researchers have studied THz imaging and spectroscopy techniques to improve breast tumor detection for the past twenty years. This paper presents the recent development of the holographic THz imaging method for identifying breast tumors. To evaluate the effectiveness of this new approach, we have developed a numerical system that includes realistic breast models and an imaging processing model. Through various experiments, we have successfully used the proposed holographic THz imaging method to identify breast tumors. Our results have shown that this method can reconstruct high-quality breast images and accurately detect small tumor inclusions, providing the correct size and location information. Based on these promising results, further investigation is warranted to explore the potential of this approach for breast tumor detection in a faster and more cost-effective manner.
Effect of Physical Modification on the Tensile and Thermal Properties of Plantain Fibre Polymer Composite
Authors: Imoisili Patrick Ehi , Jen Tien-Chien
Published: February 2024

In the electromagnetic spectrum, microwaves are electromagnetic waves with a frequency between radio and infrared. Certain materials are suited for microwave processing because they can transform microwaves into heat. Microwave energy is absorbed by the material and transformed into heat, in contrast to conventional heating where the heat is concentrated over the material’s surface rather than the core. The incorporation of fiber materials into polymer composites has shown enormous potential and has recently raised significant concerns due to the improved performance of these materials in manufacturing and critical applications. There are many different industrial uses for polymer composites packed with natural fiber (NF), and they are thermally stable at high temperatures. Ecologically suitable agricultural wastes NF as reinforcement have opened a new route into polymer composite research. According to research, physical modification methods have been found to reduce the inherent hydrophobicity of NF’s surface and can also improve the performance of a natural fiber-reinforced polymer composite (NFRPC). In this study, high-frequency microwave radiation (HFMW) applicability and suitability for modulating NF sourced from plantain (Musa paradisiaca) fiber (PF) and its impact on the thermal properties and tensile strength of the fibers reinforced polymer composite fibers was reported. PF was collected after harvesting the fruit bunch. NF was extracted from the pseudo-stem employing water retting over 28 days. Physical modification of extracted PF was employed using HFMW radiation at power different radiation watt power of 550 and 750 for a duration of 2 and 4 mins. The PF-reinforced polymer composite was fabricated by using extracted and microwave-modified PF. The composite was prepared by manually laying up and compression molding the microwave-modified and unmodified PF into an epoxy resin matrix. The effect of microwave radiation at different power and time on the PF modification with respect to the thermal properties of the fibers and tensile strength of the reinforced polymer composite were evaluated. The results obtained show that microwave irradiation at a frequency of 2.45 GHZ, 550W power, and treatment time of 4 minutes has successfully enhanced the properties of the PF-reinforced epoxy resin composite as increases in the thermal properties and tensile strength were achieved at optimized parameters. This study has demonstrated, that utilization of HFMW radiation is an effective physical treatment of plantain fibers at optimized microwave power and timing, thus, creating prospects and reliability of the fiber-reinforced bio-composite to be used in advanced materials, engineering, and structural applications.
Weighted Mori-Tanaka Approach for Homogenization of Particulate Composites at High Filler Fractions
Authors: Kabir Mobashar , Pervez Tasneem , Qamar Sayyad Zahid , Al-Jahwari Farooq K. S.
Published: February 2024

A thorough understanding of material properties allowed to tailor structures closer to their design specifications which then facilitated efficient lightweight products from transportation industry to the field of biomedical engineering. Our potential then to further optimize designs is contingent on our ability to more accurately predict effective properties of composites and is significantly important in products made of functionally graded composite materials that exhibit a gradual change in material properties along multiple directions. This research work proposes a new a simplified approach to determine effective properties of composites at high filler fractions using weight functions in conjunction with the Mori-Tanaka model. It is postulated that locally in any given particulate mixture of two materials, the composition based on local microstructure may either be defined as a filler of 1st material in a matrix of 2nd material or a filler of 2nd material in a matrix of 1st material i.e., reversing the role of constituents. The overall effective property is then obtained as a weighted sum of the two cases. Material properties predicted by the new approach lie strictly within the rigorous Hashin-Shtrikman-Walpole bounds. Predicted values for effective properties using the weighted Mori-Tanaka method yields good agreement with published experimental data, mainly at high filler volume fractions.
Modeling of Automotive Radar Sensor in Unreal Engine for Autonomous Vehicle Simulation
Authors: Rahi Adibuzzaman , Cardoza Chris Orlin , Vemulapalli Sri Sai Teja , Wasfy Tamer , Anwar Sohel
Published: February 2024

Accurately testing sensors used in vehicles prior to physical production is crucial for identifying potential shortcomings and configuring effective vehicle driver assistance systems and automations. The use of virtual environments for sensor simulation and testing offers extensive freedom and allows for experimentation with scenarios that are cost-prohibitive for physical testing. In this study, we developed a sensor model using the Unreal Engine to approximate the output of an actual Delphi ESR 2.5 medium-range radar. We utilized the LineBatcher function to create point clouds that simulate radar reflections and employed 3D grid based DBSCAN for object detection. Subsequently, we implemented centroid tracking to track objects and determine range rate, acceleration, and other outputs of the Delphi ESR Radar. In our test environment, the sensor performed close to identical to a Physical Delphi ESR 2.5 Radar with accuracy of 91% and at a data rate of 10–20 Hz.
Worldwide Lean Learning Factories
Authors: Witeck Gabriela R. , Alves Anabela C.
Published: February 2024

Lean production, also known as the Toyota Production System, is a management model that is being actively taught in academia through active learning methodologies. One such methodology is the use of learning factories to teach Lean concepts. Many Higher Education Institutions are promoting and installing learning factories to teach lean concepts effectively. This paper’s objectives are to discuss lean learning factories (LFF): characterization; importance for managers and organizations; lessons learned; lean learning aspects and general outcomes for life-long learning. To achieve this, the authors developed A literature review was conducted on lean learning factories, utilizing scientific articles obtained from the Scopus database. The review encompassed the period from 1990 to 2023. This literature review resulted in 95 papers, being the first articles relating to lean and learning factories published in 2006. The main findings revealed that the LLF can be found worldwide, and these initiatives were taken by universities and some involved organizations. Findings evidenced that setting up and installing one such LLF is not trivial and needs resources, but they contribute to the effectiveness of lean learning. The significance of these factories lies in their aim to replicate intricate real-world settings as accurately as possible, facilitating the best training in lean methodologies that align with the fundamental principles of Industry 4.0 and Industry 5.0.
Energy Absorbing Analysis and Deformation Modes of Crush Tube With Tapered Geometry
Authors: Jenson Sean , Ali Muhammad
Published: February 2024

Thin-walled axial crushing members, or crush tubes, are often utilized as energy absorbers due to their high strength to weight ratios. Applications of such devices include automotive, aerospace, and structural components. Core materials such as graded honeycomb or other support members have shown to greatly increase energy absorbing capacity, while improving structural stability during deformation or collapse. The ideal performance of such members through axial crushing exhibits numerous stepwise collapse mechanisms, or folding, up to complete exhaustion of the structure. The total capacity of these structures is highly dependent on the number of folds present during collapse. The present study aimed to improve upon previous axial crushing members with graded cellular cores through introduction of a tapered tube geometry. Optimization strategies included: decrease in component mass while meeting or exceeding previous energy absorbing performance. This study was conducted through a numerical approach using ABAQUS/Explicit dynamic modeling environment. Numerical analysis was performed until densification of the structure and numerical outputs were analyzed for crushing force, deformation modes, and total energy absorption. The tapered geometry of the tube and reduced mass of the tube/core presented a 21.3% weight reduction while maintaining similar energy absorbing performance to previous square tube configurations. The tapered tube geometry exhibited predictable stepwise collapse/fold initiation progressing from impact to distal end of tube. The overall weight reduction and predictable collapse pattern showed potential to increase customizability of crush tube members and provide additional optimization parameters.
Parametric Modeling of Lattice Structures for Manufacturing via Masked Stereolithography Apparatus
Authors: Sherwood Benjamin D. , Billings Christopher , Liu Yingtao
Published: February 2024

An investigation into parametric modeling of lattice structures is conducted in pursuit of an effective and efficient process for manufacturing lattice structures via masked stereolithography apparatus (MSLA). Principals of Design for Additive Manufacturing (DfAM) are applied, keeping in mind the manufacturing process to be used. Key design features are parameterized to decrease the effort required to design and implement changes to the structures. Unit cells are modeled as interconnected struts according to parameters such as unit cell side length and strut diameter or thickness. As well as parameterizing the unit cell geometry, the number of cells in each of the three cartesian directions are parameterized such that a three dimensional array of unit cells is constructed based on the single unit cell. Three unit cells are to be considered: the simple cubic (SC) unit cell, the body-centered cubic + simple cubic (BCC|SC) unit cell, and the face-centered cubic + simple cubic (FCC|SC) unit cell. A simple procedure for interfacing the lattice to bulk material is proposed. The proposed design process is validated through qualitative analysis of lattice samples designed with varying unit cell and overall lattice properties with results supporting future studies. Additionally, an example of replacing a solid model’s interior with the lattice structure is detailed to demonstrate the simplicity and power of the approach. It is found that even very thin features with maximum dimensions less than 10 pixels or layers depending on feature orientation (0.34mm and 0.5mm, respectively) are able to be manufactured using affordable consumer grade equipment, which allows for a multitude of potential applications from general purpose lightening to primitive object strength augmentation.
Variable Geometry Crush Tube With Induced Folding Mechanisms
Authors: Jenson Sean , Ali Muhammad
Published: February 2024

Thin-walled axial crushing members are employed as front energy absorbers in automobile chassis design. They improve crashworthiness while maintaining low structural weight addition due to their high strength to weight ratios. The addition of core material has also been shown to increase energy absorption capacity and structural stability during deformation. Specifically, the addition of functionally graded cellular cores maintained high strength to weight ratios and assisted the increase in strength and stability. The present study aimed to investigate the effects of induced folding of the outer tapered tube structure to maximize energy absorbing performance of the axial crush tube member. This study was conducted through a numerical approach utilizing ABAQUS/Explicit dynamic module. Numerical analysis was performed until densification/locking strain for each case. Analysis criteria included: crushing force, plateau stress, deformation modes and energy-deformation stroke plots. The induced structural collapse due to the peripheral cuts forced progressive folding in a more predictable pattern as compared to the standalone structure. It has been shown that energy absorption increases with the number of deformation sites and the induced folding mechanism assisted in maximizing this effect while following a predictable deformation behavior. The increased number of deformation sites due to the peripheral cuts resulted in a 10.1 % increase in mean crushing force and 14.6% increase in energy absorption as compared to the configuration without peripheral cut hence confirming potential for further improvement in energy absorption of thin-walled axial members.
Dielectric and Mechanical Characteristics of Polyamide-Silicon Dioxide Nanocomposites
Authors: Mahon Nicholas R. , Ericksen Jared , Lawton Sean F. , Coraggio Max P. , Terifay John P. , Smith Michael , Martinez-Castro Diana , Maienza Paul M. , Xue Wei
Published: February 2024

Nanocomposites have emerged as a promising area of research in recent decades due to their ability to improve the properties of host materials. Nanocomposites for cryogenic applications have gained significant attention for their potential in high-temperature superconducting (HTS) power transmission systems. However, exposure to low temperatures has detrimental effects on the material properties of the dielectrics, limiting their applications. This necessitates the investigation of thermally stable high-quality dielectrics, which can be quantified through electrical and tensile testing in various controlled environments. This paper discusses the preparation of a polyamide (PA) / SiO2 nanocomposite through a sol-gel process. The primary focus in this project is on the baseline material characteristics at room temperature. We have performed a multitude of microscopy imaging, AC and DC dielectric tests, and tensile tests, all under a room temperature environment. The results of this research can help improve the understanding of these composites and guide our future material testing in cryogenic environments.
Experimental Determination of Load-Carrying Capacity of Modified Tapered-Land Hydrodynamic Thrust Pad Bearings
Authors: Trammell Jenna , Fais Collier , Ali Muhammad , Walker Rick
Published: February 2024

In this study, a method for increasing specific load on hydrodynamic thrust bearings is introduced and experimentally evaluated. Experimental determination of thrust bearing load capacity is limited by the applied load capability of test equipment which may be unequipped to create specific load magnitudes for application-sized bearings. Theoretical analysis of Reynolds equation suggests there is a linear relationship between the number of pads on a thrust pad bearing and the maximum thrust load a bearing can support. Two bearing samples, one with 8 active thrust pads and the other with 4 similarly sized active thrust pads are fabricated and subjected to an experimental test matrix. Each bearing is tested at 20 different combinations of steady-state speed and thrust load all at consistent oil inlet conditions. Sensors integrated in the test rig measure the magnitude of hydrodynamic pressure acting on the middle of the thrust pads along with bearing temperature and minimum oil film thickness. Results from this study show that reduction of the active thrust bearing surface area by half was shown to increase the hydrodynamic pressure acting on the bearing by nearly 100%. Removing active thrust pads is proven to effectively multiply the specific load on the bearing pad and create a more extreme operating condition under lower thrust force without increasing the bearing size envelope and/or undergoing time consuming and costly test rig upgrades.
Computational Study on the Effect of Multiple Inlets in a Vacuum Membrane Distillation Module
Authors: Caspar Justin , Xue Guanyang , Oztekin Alparslan
Published: February 2024

2D Large Eddy Simulations (LES) were run to characterize the flow inside vacuum membrane distillation channels with multiple inlets. Jets are commonly used in industrial applications to induce mixing and disperse chemicals. For membrane distillation, multiple inlets provide a way to mitigate axial temperature polarization while promoting mixing in the channel. Four modules operating in the laminar regime, Reynolds number 750, were designed, two with inlets placed via fittings in the channel and two with inlets placed on the bottom wall of the channel. The injection was done through three inlets spaced evenly in a L/H 200 channel. The total injection flow rate was equal to the inlet flow rate. The jets were seen to reduce the impact of temperature and concentration polarization in the membrane module for the selected conditions by increasing the local Reynolds number and leading to a smaller boundary layer thickness. Injection through fittings saw flow separation in the channel at x/H of 150–200. The mixing structures, combined with the impact of the jet, lead to a 12% increase in flux performance. Without mixing, the jets contributed to a 6.5% flux increase.
Mobile Robot With Robotic Arm: Development and Validation of a Digital Twin
Authors: Salamina Laura , Gaidano Matteo , Melchiorre Matteo , Mauro Stefano
Published: February 2024

Mobile robots coupled with robotic arms are a powerful instrument for factory automation, and they have become more and more popular in last years. Their digital twins allow to simulate the behavior in an industrial environment, increasing the capability to monitor their performance to detect failures or deviation from expected behavior. This work considers a system composed by a MiR250 mobile robot and by a UR5 anthropomorphic robot and describes the digital twin of the composed system. The digital twin is the coupling of the model of the UR5 robotic arm and that of the mobile robot. The model of the mobile robot considers a dynamic model of each wheel, to investigate the behavior of driving and caster wheels, and the model of the motors, to evaluate the expected motor torque. The digital twin of the UR5 robotic arm was tuned according to an identification methodology previously developed. An experimental campaign was carried using an Optitrack motion capture system. The results show that the model can provide reliable data to check and forecast the behavior of the system. The paper describes the complete model of the system, discusses its identification process, and shows some results obtained in the experimental campaign.
Computational and Experimental Study on Effect of Increased Makeup Torque on Fatigue Life of Rotary Shouldered Connections
Authors: Song Fei , Du Michael , Li Ke
Published: February 2024

The tools and subs used on the bottom hole assembly (BHA) are threaded together by rotary shouldered connections. A rotary shouldered connection consists of a pin element and a box element has two main components: a seal/torque shoulder and threads. The rotary shouldered connection upon makeup needs to seal between internal and annular pressures at the shoulder and transmit torque, while withstanding the cyclic bending loads when drilling through a curved section of the well. If twist-offs occur on the connections, the drilling and measurement tools could be flooded with drilling mud invasion, causing severe damage of the expensive measurement devices and sensors, along with a significant amount of nonproductive time for fishing. With drilling becoming increasingly aggressive and challenging in recent years, the BHA can continue to torque up in the downhole. Rotary shouldered connections can be required to be made-up above the recommended torque values, such that uncontrolled downhole makeup in severe drilling environments could be prevented. With higher makeup torque, the fatigue resistance of the rotary shouldered connections would be compromised. Therefore, there is a strong need to understand the effect of increased makeup torque on the fatigue strength of the rotary shouldered connections.

In this paper, a computational model based on finite element analysis (FEA) of the threads is developed for predicting the bending fatigue life of the rotary shouldered connection under specific makeup torques. Specifically, the FEA model can capture the nonlinear interactions between the pin and box threads and on the seal face under combined loads of pretension and bending. Strain-life approach is used to assess the fatigue life of the connection under constant-amplitude cyclic bending based on the alternating strain and mean stress obtained from the FEA model. The developed FEA model is validated through comparison of the numerical predictions to the test results obtained from full-scale rotating bending fatigue tests of the rotary shouldered connections. Favorable agreement is found between the predicted fatigue strength of the connection and the experimental observations at various makeup torque values. Upon validation, the numerical modeling approach has been successfully utilized to virtually qualify the rotary shouldered connections of various types without conducting physical tests and to support operation in different drilling conditions, which has led to a tremendous amount of cost and time savings for rotary shouldered connection development and reduction in the cost of service delivery (COSD).
Thermal Performance of a Geothermal Source High-Temperature Heat Pump for District Heating – Comparison of Single-Stage and Cascade Vapor Compression Cycles
Authors: Dickinson Devon , Mai An , Govedaric Aleksandra , Shor Roman , Mwesigye Aggrey
Published: February 2024

Reducing greenhouse gas emissions is of utmost importance in the race to keep the global average temperature increase to within 1.5°C of pre-industrial levels to avoid catastrophic consequences of climate change. In cold climates, a large portion of carbon dioxide emissions come from the heating requirements of buildings, primarily space heating and hot water heating. Large institutional and commercial buildings use considerable amounts of energy to provide space heating and hot water, most of which comes from large-scale district heating systems powered by fossil fuels. There is therefore potential for emission reduction in institutional and commercial buildings using clean and renewable energy. This study investigates the use of high-temperature heat pumps in a high-temperature district heating system for a University Campus. The considered heat pump system meets 51 MWth of heating demand. The heat pump is coupled to a geothermal borehole 2 km in depth whose performance is modeled using CMG software for thermal reservoir modeling to improve its performance. The performance of the heat pump system using R134a is compared with that of environmentally friendly refrigerants, including R1233zd(E), R1366mzz(Z), R1234ze(Z), Butene, ammonia, R1224yd(Z), and RE245CB2. Results show that the cascade system yields higher average COPs regardless of the refrigerant due to lower compressor energy inputs. Results further show that using refrigerant R1233zd(E) in both system stages produces the best performance, with an average COP of approximately 3.0. Furthermore, for the building energy loads considered, high flow rates between 500 m3/h to 6000 m3/h are needed to meet the entire heating demand depending on the temperature difference between the inlet and outlet temperatures of the geothermal heat transfer fluid.
Solar Trackers Using Spherical Mechanisms
Authors: Sivarapu Aditya Krishna , Zhou Hong
Published: February 2024

The power harvesting from a solar panel is maximized when its face is perpendicular to the solar ray. In order for a solar panel to face the sun during the daytime, its orientation has to be adjusted by a solar tracker. There are two relative motions between earth and sun. Compared with its daily east to west rotation, sun’s south-north movement is much smaller. If only sun’s east-west relative motion is considered for developing solar trackers, mechanisms with single degree of freedom can be adopted. If the orientation of a solar tracker with single degree of freedom is adjusted seasonally or monthly to cover sun’s small south-north relative movement, the solar tracker can effectively fulfill its solar tracking function. Single-axis solar trackers commonly consume less power to operate than their two-axis counterparts and cost less to fabricate and maintain, which brings their solar tracking merits. This research is on single-axis solar tracking mechanisms that are based on four-bar mechanisms. Because of their simple structure, high reliability, and easy maintenance, four-bar mechanisms have been extensively employed for various applications that include solar tracking. Four-bar solar tracking mechanisms currently have room for further improvement. The difficulties facing them include limited solar tracking motion, high solar tracking power consumption, and lacking self-locking function. Surmounting these difficulties makes designing four-bar solar tracking mechanisms challenging. Four-bar solar tracking mechanisms can be planar 4R, planar 3R1P, spherical four-bar mechanisms. Each of the three types has its unique solar tracking features. In this research, the performances of these four-bar solar tracking mechanisms are analyzed, simulated and compared with the motivation of improving them. The research results are tried to provide some guidelines for developing and promoting four-bar solar trackers.
Multi-Physics Simulation for Morphology Design of Si Anode
Authors: Bansal Parth , Li Yumeng
Published: February 2024

Due to a constant increase in the usage of portable battery power storage and delivery systems, there is a constant need for innovation in the area of battery design. One such possible innovation is the use of Silicon (Si) as the anode material in Lithium-Ion Batteries (LIBs). While Si is a much better anode material than the traditionally used graphite anode, its usage comes with its own issues. The intercalating mechanism in Si anodes for Li ion storage, causes an increase in the specific capacity of battery along with significant variation in the volume of Si during the charge/discharge cycling. Volumetric variations of up to 300% are observed during the lithiation/delithiation in the Si anode which results in the development of massive internal stresses in the anode. These internal stresses are observed to cause delamination of the anode from the metal substrate and also the cracking within the anode material itself, which ultimately decreases the capacity of the battery. A possible solution to this problem is to design the morphology of nickel backbones in Si anode to reduce the intensity of the internal stresses and therefore the resulted failure and capacity degradation. In this paper, multiphysics simulation based on finite element analysis is developed to understand and quantify the effect of the morphology of nickel backbone on the lithiation induced stress in the Si anode. A convex and concave anode structure, along with a flat design for comparison, will be simulated for different lithiation/delithiation rates, using the FE model and the FE analysis will be conducted to investigate the changes in the corresponding stresses in Si layer, the cracking pattern and the delaminated area. It is expected the developed multiphysics FE simulations can inform the morphological design of anode to minimize the mechanical degradation and reduce capability loss.
A Decentralized Multi-Agent Path Planning Approach Based on Imitation Learning and Global Static Feature Extraction
Authors: Feng Bohan , Bi Youyi , Li Mian , Lin Liyong
Published: February 2024

Multi-agent path planning is a crucial problem in numerous industrial robotic implementations, ranging from smart material transportation, mobile patrolling to automated warehousing. In this paper, we introduce a decentralized multi-agent path planning approach based on imitation learning and global static feature extraction. Our approach employs a convolutional neural network in the information extraction layer to obtain features from local field-of-view observations and expert-planned paths under a global static map. The information aggregation layer then uses a graph attention network to combine feature information from selected neighboring agents. The request-reply based selective communication is also applied in the information aggregation layer to identify appropriate neighboring agents to be included in the graph attention network. Finally, the action output layer translates the aggregated feature information into actions for each agent. Additionally, we develop a strategy switching mechanism that adaptively utilizes expert-planned paths under a global static map to support agents to escape from local traps. The effectiveness of our proposed approach is evaluated in simulated grid environments with varying map sizes, obstacle densities, and numbers of agents. Experimental results demonstrate that our approach outperforms other decentralized path planning methods in success rate and generalizability. Furthermore, our approach is computationally efficient and scalable, making it suitable for real-world applications.
Understanding Governing Physical Mechanism of Bio-Inspired Nanostructured Antifouling Coating
Authors: Singh Akash , Li Yumeng
Published: February 2024

Nanostructured anti-fouling surface has been discovered on the wings of insects like Cicada, which have the ability to kill bacteria on contact. The discovery of such nanostructured surface on cicada wings started a race amongst researchers to find and develop anti-biotic coating for implantable devices, which can prevent the infection from harmful bacteria and simultaneously reduce the use of antibiotic chemicals. To develop and design such biomimetic bactericidal surfaces, thorough understanding of the bactericidal mechanism is critical. However, due to extremely small relevant length and time scales, it is challenging to investigate the bactericidal process in an experimental setting. Molecular Dynamics (MD) simulation provides an exceptional tool to predict structural and material behaviors at small length and time scales with good accuracy and a fraction of costs relative to experimental testing. We have developed a coarse-grained model to simulate the deformation of bacteria on nanopillared array/surfaces to investigate the governing killing mechanism of bacteria. This study has investigated the effect of nanopillars height and bending rigidity of the bacteria’s membrane on the governing killing mechanism and bactericidal efficiency. It is suggested that for bacteria with high membrane bending rigidity, nanopillar height is not an important factor and piercing of the bacteria’s membrane is the dominating bactericidal mechanism. For bacteria’s with low bending rigidity sagging of the bacteria’s cell membrane between nanopillars and resulting stretching/tearing is the major killing mechanism. Therefore, nanopillar height is an important factor for governing the bactericidal efficiency because small nanopillars allow the bacteria to sag down and reach the bottom surface for extra support without damaging. In addition, the present study implies that there exists a critical height of nanopillars for the development of efficient antifouling surfaces against bacteria with low membrane bending rigidity.
A Framework on Performing Virtual Building Energy Audit
Authors: Guo Qi , Chiasson Andrew , Almoatham Sulaiman
Published: February 2024

This article outlines a method for conducting virtual energy audits in situations where on-site visits are not possible. The approach provides a systematic methodology, including utility cost analysis, facility energy balance analysis, and lean energy analysis, to identify and prioritize energy-saving measures. The critical areas examined during a virtual visit include the building envelope, lighting, and HVAC systems. The paper also includes a case study that highlights the efficacy of the proposed framework. The study recommends several energy-saving measures, such as consolidating electricity meters, using photosensors for sidewalk lights, replacing traditional bulbs with LED bulbs, and upgrading parking lot lights to LED bulbs. The article contributes significantly to the field of energy auditing, especially in cases where physical access to buildings is restricted. The proposed framework provides a cost-effective and efficient alternative to traditional energy audits and allows organizations to promote environmental sustainability by reducing energy consumption.
System Parameter Design for Community Microgrid Energy System Based on a Bi-Level Optimization Model
Authors: Liu Jiangshan , Bi Youyi
Published: February 2024

With the increasing use of renewable energy in the context of global climate change, microgrids are expected to be a promising form of accessing and distributing renewable energy sources. However, existing design methods for microgrid energy systems usually consider the system planning and system operation as separate problems, which cannot guarantee the safety, reliability and cost economy of microgrids from a holistic view. To fill this gap, we propose a system parameter design approach for community microgrid based on a bi-level optimization model. This approach can generate optimal system configuration parameters and operation parameters for a community microgrid energy system in an integrated way. To demonstrate the validity of the proposed approach, we use the construction and operation of a medium-sized community microgrid system in a southern-China city as the illustrative example. The results show that the generated system planning and operation strategies can effectively improve the reliability and lower the operation cost of the microgrid system without raising customers’ power consumption expenditures. In addition, the influence of the environmental sensitivity of renewable energy and the dynamics of customers’ power consumption patterns on the reliability and economy of microgrid are also examined and discussed. Our study contributes to the development of advanced design and operation methods for smart-community energy systems.
A Reduced Order Model for Static and Buckling Analysis of Thin-Walled Stiffened Plate on a Non-Conformal Mesh
Authors: Hashemian Fatemeh , Zhao Wei , Wang Yi
Published: February 2024

Thin-walled stiffened plates can be susceptible to buckling-induced instability failures. An accurate and efficient model is essential for optimizing stiffener size and shape and analyzing buckling while considering geometric complexity, location, loading, and boundary conditions. A full-scale finite element analysis (FEA) was previously employed to determine the buckling load of the stiffened plate during the stiffener shape and size optimization. A non-conformal mesh method based on an inverse isoparametric mapping algorithm (IIMA) was developed recently to model stiffened plates with complex-shaped stiffeners keeping the base plate unchanged. Built on this work, this paper presents a reduced order modeling (ROM) approach to accelerate the static and buckling analysis of the stiffened plate. The principle is to use the base plate’s free-vibration modal shapes to estimate its displacement and link the ROM of the base plate with stiffeners through displacement compatibility at the interface. ROM is used again to approximate the eigenvalues in the buckling analysis of the stiffened plate. The proposed ROM approaches turned out to be accurate and significantly reduce computational time compared to full-scale FEA.