bluuebunny/crossref_metadata_2025 huggingface dataset:
Deformation of Cells Passing Through Gaps Between Microcylinders in Channel
Authors: Hashimoto Shigehiro , Uehara Shogo , Yamamoto Kota
Published: February 2024

Gaps play an important role in cell sorting in vivo. Some cells pass through very narrow gaps and their deformation mode may be related to their biological functions. In this study, the gaps (25 μm, 20 μm, 15 μm, 10 μm width) between micro-cylinders (25 μm diameter, 60 μm height) were manufactured in a channel between parallel plates (1 mm width, 30 mm length, 60 μm height) by photolithographic techniques. In microscopic videos of myoblasts suspensions, the contours of cells passing through the gap were tracked, and the moving velocity, two-dimensional projected area, degree of deformation, and direction of deformation were measured. Analysis of experimental images showed that the direction of cell deformation during passage can be measured in this channel system with gaps between microcylinders.
High Fidelity Modeling of Wear, Hysteresis, and Tooth Cracks in Strain Wave Gears for PHM Purposes
Authors: Guida Roberto , Bertolino Antonio Carlo , De Martin Andrea , Raviola Andrea , Sorli Massimo
Published: February 2024

Strain Wave Gears (SWGs) are widely used in aerospace and robotics for their high reduction ratio, low backlash, and compact design. An important field in which they will be largely used in the future is the development of compact Electromechanical Actuators (cEMA) specifically designed for electric aircraft to be implemented in Urban Air Mobility scenarios. Due to the key role played by these components in guaranteeing the passengers’ safety, it is necessary to monitor their health status and estimate their remaining useful life. The application of Prognostics and Health Management (PHM) techniques requires a large amount of data, which can come from experimental tests, historical database, or simulations. The first two approaches are more effective, but they are expensive and require a lot of time. For these reasons, the third one is often chosen as suitable alternative. In this context, a two-dimensional planar equivalent model of a SWG is developed to replicate the reducer behavior in nominal and degraded operating conditions. The proposed model includes the effects of wear, hysteresis, and tooth crack on the SWG performance, and the outcomes of the simulations derived from it are compared with the literature in order to evaluate the ability of the model to replicate real behavior. The proposed model represents a first important step in the development of a fully-realized digital twin of the cEMA with a rotary output capable of replicating the system behavior in both nominal and faulty conditions.
Optimal Design of Magnetic (Eddy Current) Dampers for Tuned Damping Applications
Authors: Farran Abdulrhman , Kashani Ahmad Reza
Published: February 2024

In this study, magnetic damping (also known as an eddy current damping) which is generated by the eddy current induced in a conductive material subjected to a time-varying magnetic field (created by several rare earth permanent magnets) is explored. Two configurations of eddy current dampers (ECDs) are investigated in this paper. The first configuration is made up of a stack of eight Neodymium NdFeB (N42) permanent magnets separated by seven pole pieces made of nearly pure iron, assembled on a shaft moving back and forth in the confines of an aluminum tube. The second configuration of the eddy current damper contains a conductive copper plate and five NdFeB (N50) magnet plates placed on two iron plates that move in parallel and close vicinity of the copper plates. In both damping schemes, the interaction between the magnetic field of the permanent magnet assembly and the magnetic field of the electromagnet created by the eddy current within the conductor results in energy dissipation. The two configurations of eddy current damper are modeled numerically and verified experimentally. The motivation for conducting this study is to explore the use of eddy current damping as an alternative to liquid-based viscous and solid-based viscoelastic damping mechanisms.
Simulations of Pre-Mixed Droplet Injection for Achieving Isothermal Compressed Air Energy Storage
Authors: Simpson Juliet G. , Qin Chao , Loth Eric
Published: February 2024

The efficiency of compressed air energy storage (CAES) can be improved with water sprays to increase heat transfer during the compression and expansion processes for piston-based configurations. In general, direct injection is typically used for compression, but recent numerical simulations indicate that expansion can have generally lower energy efficiency for the same droplet mass and same droplet size. Herein, pre-mixed water droplet injection is considered as a potential alternative to improve efficiency for expansion. A parametric analysis is completed for 1-D simplified conditions, where air flow and droplet concentration are assumed to vary axially and the water droplets are assumed to move at terminal velocity. These 1-D results indicate similar trends as those for direct injection but that pre-mixed achieves higher isothermal roundtrip efficiencies (compared to direct injection) for expansion with droplet mass loadings of about unity. However, unsteady 2-D axisymmetric simulations with dynamic water droplet trajectories showed large spatial variations in air temperature, droplet temperature and droplet concentration due to complex flow structures. Despite these differences, the 1-D and 2-D model predictions of isothermal efficiency were very similar (within 7%), indicating that the 1-D model captures the key heat transfer physics of the expansion process. Suggested future work includes 3-D simulations and experiments to help to achieve high-efficiency isothermal CAES.
Artificial Intelligence Based Modelling for Energy Output Predictions of Renewables
Authors: Domenikos George-Rafael , Hajimirza Shima , Acar Gizem
Published: February 2024

The reliance of energy grids to a variety of energy sources leads to complex systems that need to consider multiple parameters in order to optimize the use of their resources as to have the least environmental impact. In this work the authors present a modelling based on statistical analysis and artificial intelligence that aims to predict the energy outcome of renewable energy sources, more specifically wind and solar farms. In the presented paper traditional mathematical/ statistical approaches (like time series through interpolation) are used in combination to Artificial Intelligence algorithms. Thus, by combining the use of Artificial Neural Networks (ANN) with mathematical prediction models it is showcased that energy output of these renewable sources can be predicted with great accuracy. In addition, using a combined quasi-AI algorithm consisting of an optimized use of both mathematical and AI models is shown to lead to quickly predicting results for short term energy production with much less computational intensity compared to full AI algorithms, requiring more intensive training. Overall, using the presented models an energy grid can be expected to utilize the potential of its renewable energy sources to the fullest, minimizing dependence on non-renewables and as such the environmental damage they cause.
Implementing Augmented Reality in a First-Year Mechanical Engineering Course
Authors: Rios Oziel , Fadda Dani
Published: February 2024

Spatial Visualization Skills (SVS) are related to a person’s ability to mentally generate and transform visual images and are associated with their problem-solving abilities. Engineering students need to solve problems requiring them to visualize and mentally manipulate complex geometric shapes. Augmented Reality (AR) is a powerful visualization tool because it provides a middle ground between virtual and physical manipulation allowing for a closer connection between a virtual object and the manipulations typical in engineering.

The objective of this paper is to present the experiences and lessons learned of implementing AR technology in a first-year mechanical engineering course. First, the needs of our students and the parameters and specifications of the AR technology implemented to support them are provided. Applications used in this study, which allow students to interact with virtual objects using simple hand gestures, are discussed. The two types of learning modules developed are presented — one where the students must determine what a 3D shape looks like from different perspectives (generating 2D orthographic views) and another where the students must construct a 3D shape given a set of orthographic views (3D model construction). Samples of student work generated with the AR technology are presented and student experiences are discussed. Recommendations for scaling to large classes are also provided. Finally, data collected over two semesters (16 students from Fall 2021 semester, and 15 students from Fall 2022) demonstrate that spatial skills are improved when students engage in AR activities.
Thermal Transport Study of KCl-UCl3 Using Molecular Dynamics Simulations
Authors: Bratescu Simon , Park Jungkyu
Published: February 2024

In the present study, we investigated the thermal transport in two important molten salt mixtures, i.e., LiF-ThF4 and KCl-UCl3. The Born-Mayer-Huggins short-ranged potential was used with LAMMPS and the reverse nonequilibrium molecular dynamics (RNEMD) algorithm to generate a heat flux across the simulation structure. Thermal conductivity was determined by Fourier’s law from the imposed heat flux and induced temperature gradient. The results show that the thermal transport in these molten salt mixtures is readily diffusive, and their thermal conductivities do not depend on temperatures. LiF-ThF4 mixture shows a clear dependency on the density; the thermal conductivity decreases with an increase in its density that results from the ThF4 mole fraction increase. An increase in density is likely to impact phonon transport negatively because of increased viscosity. Unlike LiF-ThF4, the thermal conductivity of KCl-UCl3 increases with an increase in its density that results from UCl3 mole fraction increase. The authors believe that the results obtained in this research will provide a microscopic understanding of the thermal transport properties of molten salt reactor fuels and contribute to the development of more advanced molten salt reactors.
Design and Development of a Shaking Machine and Techniques to Characterize the Damage Generated by Mechanical Vibrations in Feather Art and Antique Manuscripts
Authors: Armenta-Marquez Alí E. , Zamora-Garcia Diego A. , Arana-Lopez Luis F. , Corona-Lira Ma. Pilar , Ramirez-Reivich Alejandro C.
Published: February 2024

Preserving art and heritage objects is essential to comprehend multiple aspects of the development of societies. When submitted to mechanical vibrations, there is little knowledge about these objects’ behavior and consequences. In this paper, a methodology for the design of a shaking machine and its development with a conservation perspective is explored. An artificial vision technique to measure overall shaking in a complex flexible object is also developed. It is concluded that the machine could establish a relation between the induced vibration level enforced on the test subject with the shaking level exhibited by these subjects. Further application of this technology can help conservationists make informed decisions concerning maneuvers and the exhibition of art objects.
On-Machine Positioning Method for Integral Impellers Based on Three-Dimensional Point Cloud
Authors: Chen Weihua , Ye Peiqing
Published: February 2024

The integral impellers are crucial components of aerospace engines. In recent years, pre-formed blanks made through 3D (three-dimensional) printing and powder metallurgy have been increasingly used to improve material removal rate and processing efficiency. However, advanced blank manufacturing processes require higher precision in clamping alignment. The 3D camera system is poised to replace on-machine probes in achieving precise pose of blanks as they provide measurements with high accuracy and density.

In this paper, we propose a methodology for precisely determining the positioning and pose of integral impeller blanks based on 3D point clouds. We first calibrated the 3D camera on the CNC machine. The homogeneous transformation matrix of the 3D camera coordinate system relative to the CNC machine coordinate system was calculated. Then, our proposed method enables a rapid alignment of the point clouds obtained from the blank with the corresponding CAD model. Finally, the machining allowance at the blades on the blank is calculated and optimized.

Our on-machine 3D camera system has been successfully implemented on a CNC machine, and our proposed method has been validated. The system reduces measurement time by 5/6 compared to contact probes, making it highly efficient. The average machining allowance distribution was adjusted from 2.55 ∼ 3.56 mm before optimization to 2.92 ∼ 3.22 mm after optimization. On-machine measurement experiments with the contact probe have also verified that compensation is effective. The system is expected to be extended to other complex-shaped parts such as inlets for clamping processes.
A Frozen-Time Method for Discontinuous Internal Forces of a Multi-Span Beam Carrying Moving Subsystems
Authors: Gao Hao , Wang Ruiyang , Qu Yegao , Meng Guang
Published: February 2024

A flexible structure that carries moving subsystems is subject to dynamical interaction forces with time-varying locations due to the elastic coupling between the subsystem and the structure. Those interaction forces render the internal shear force and moment distribution in the structure piecewisely continuous with jump discontinuities. Conventional modal expansion method that utilizes continuously differentiable eigenfunctions encounters very slow convergence and inevitable overshoot and undershoot at the jumps. To overcome this issue, we propose a novel method called modified series solution method (MSSM) to precisely determine the jump discontinuities in the internal shear force and bending moment of the host beam structure. The new solution contains three terms, including a conventional series dynamical solution and two static solutions evaluated at the current “frozen” time. The proposed augmented solution of the beam can not only precisely predict the time-varying jump discontinuities in the internal shear force and bending moment distribution without introducing any overshoots or undershoots, but also has a fast convergence rate the same as the displacement and the slope. It provides a new framework to analyze the discontinuous shear force and moment of a host structure induced by viscoelastically coupled subsystems.
Separation of CTCs From Blood Cells Using Curved Contraction-Expansion Microchannel Equipped With DEP Force
Authors: Sarowar Md Tanbir , Islam Md Sadiqul , Chen Xiaolin
Published: February 2024

The isolation and separation of circulating tumor cells (CTCs) from peripheral blood without compromising their viability is crucial for cancer diagnostics and prognosis. However, the successful isolation of CTCs is often quite challenging due to their low concentrations and size overlap with other blood cells. Microfluidics devices incorporating inertial forces in recent times have emerged as a promising tool for CTC separation with high throughput and minimal invasiveness. Despite these advantages, CTC isolation using inertial microfluidic devices still faces challenges in practical application due to their inability to separate CTCs having overlapping sizes with WBCs. To, tackle this issue, the present study offers a curved contraction-expansion structured inertial microfluidic device equipped with DEP, that possess the potential of continuous and high throughput separation of CTCs from WBCs regardless of their size overlap. The use of DEP force ensures the successful separation of similarly sized CTCs from WBCs from blood samples, and the use of a contraction-expansion structure offers precise microenvironment that enables the efficient use of DEP force for continuous label-free separation. The characteristics of cell transport and cell positioning are quantified through coupled physics analyses to evaluate the effects of different parameters such as: the aspect ratio of the rectangular channel on contraction zones and the ratio of sheath and mixture flow on separation efficiency of the proposed device.
Investigation of Transverse-Electric (TE) and Transverse-Magnetic (TM) Laser Modes in Hybrid Metal Optical Microlasers
Authors: Sakib Md Nazmus , Manzo Maurizio
Published: February 2024

Dye-doped optical microlasers’ laser emission is achieved by optically exciting a dye-doped optical microscale resonator. When the microlaser is excited by a light source, the fluorescence from the dye acts as the gain material for the optical resonances. The optical resonances (laser modes) are very sensitive to any perturbation of the microlaser’s morphology. When metal nanoparticles are added to the optical cavity, the laser emission can be enhanced, the energy threshold reduced, and the quenching effect limited. In this work, we investigate the effect on the laser modes emission for different gold (Au) nanoparticles distributions in dye-doped polymeric microlasers. When the polarization of the pumping laser is vertical, both TE (transverse electric) and TM modes can be observed in the lasing emission.

In previous experiments using Au-doped optical microlasers, it was found that the TE and TM laser modes were observed to compete each other for different values of pumping energy, for a certain metal nanoparticles’ concentration. Au particles were mixed randomly within the microlasers and different concentrations were tested.

In this work, spherical microlasers are fabricated using a mixture of UV curable polymer and the laser dye rhodamine 6G. The microlasers are then partially covered with gold nanoparticles by using a dispersed solution of Au particles placed on a glass slide. Since the resonator is spherical, in general, there is not a preferred path for the traveling light used to generate the laser modes. By partially covering the external surface of the microlaser with Au particles, it is possible to force the light to a preferred optical path, which can be used to investigate the metal nanoparticles’ distribution effect on the TE and TM laser modes.
Control Co-Design of Battery Packs With Immersion Cooling
Authors: Liu Zheng , Wu Jiaxin , Fu Wuchen , Kabirzadeh Pouya , Chung In-Bum , Dipto Mohammed Jubair , Miljkovic Nenad , Wang Pingfeng , Li Yumeng
Published: February 2024

To efficiently increase the energy density of the battery pack, cell-to-pack has become a widely used packing technology for electric vehicles. Among different cooling methods, immersion cooling with feedback control can provide robust thermal management to keep the temperature of all battery cells within a desirable range, therefore, ensuring a good cycle life performance for the battery pack. However, the layout of the battery pack and the target temperature of the feedback control are currently decided separately in the design of the battery pack and its immersion cooling system, which can only produce suboptimal results with a low thermal management efficiency. This paper presents the study of battery pack design study with immersion cooling that aims to lower the energy consumption of the immersion cooling system for a 21700 cylindrical battery pack using a control co-design method. First, a high-fidelity finite element model is established based on experimental data to predict the temperature and energy consumption considering the change in battery layout and target temperature. A Gaussian process based surrogate model is developed and used to predict the performance in different pack design scenarios therefore identifying an optimal design. The results showed that the optimal design obtained from the presented study lowered the immersion cooling system’s energy consumption by 13%.
3D Printing for Innovative Engineering Solutions “The Environmental Challenge”
Authors: Al-Hamidi Yasser , Kozusznik Marcin , Al-Rawashdeh Mamoun
Published: February 2024

For decades, the value of hands-on experience in engineering education has been recognized, emphasized, and understood. However, establishing and operating a successful hands-on experience, particularly with new emerging technologies such as 3D printing is a challenging endeavor. 3D printing, also known as additive manufacturing, allows the creation of tangible objects from a digital geometrical representation by sequentially adding materials layer by layer. Many industries have adopted this technology for its design flexibility, application specific materials availability, and ease of use compared to other manufacturing methods.

Although most of the major industrial engineering projects are multidisciplinary, the majority of existing undergraduate engineering curricula do not provide adequate opportunities for students to interact and collaborate with students from other majors to solve real-world technical interdisciplinary challenges, similar to what they will most probably have to deal with after graduation.

This paper details the efforts of a group of faculty and students at Texas A&M University at Qatar to develop and implement a multidisciplinary extracurricular activity (short course) on 3D printing for environmental applications. The activity takes place over the course of five days and focusses on introducing students to a systematic approach to solve real-world environmental issues and problems, such as global warming and pollution management. In the beginning of the course, enrolled students are introduced to three different need statements, CO2 capturing, NOx emission control, and Odor emission control. Then they are asked to form three interdisciplinary teams based on their interest in one of the need statements. To ensure that they are equipped with the required tools to device their innovative solutions, the students are exposed to the basics of CAD modeling and 3D printing. They also tour the 3D printing lab to receive hands-on training on how to operate polymer and ceramic 3D printers in particular. Inspired by the generic product design and development process, students are encouraged to articulate a list of customer needs and specifications of their product/s before they begin brainstorming concept solutions for their assigned need statement. In the last two days of the course, the students go over different iterations of prototyping and testing of their conceptual design/s against some given performance indicators like pressure drop and mixing efficiency to select the optimal concept solution.

This work was piloted successfully with 12 students from different engineering majors. The teams presented their final concept solutions in front of jury of academic and industrial experts in the field. Students work and presentations were scored based on a predefined rubric which was given to students prior to conducting their presentations. Some of the work is expected to lead potentially to a patent.
Modeling of Human Femoral Bone Idealized As Functionally Graded and Laminated Composite Structure
Authors: Kabir Mobashar , Pervez Tasneem , Al-Jahwari Farooq K. S. , Qamar Sayyad Zahid
Published: February 2024

Femur, the largest bone in the human skeletal system, provides critical mechanical support in bearing internal and external loads. It is a sophisticated natural composite with a complex hierarchical construction of multiple layers having varying material properties. This research work explores modeling approaches focusing on localized behavior of bone material under lateral loads. Small elements taken from cross-sections of femur bone are considered for analysis. To simplify the analysis, it is assumed that the chosen elements can be idealized as plate structures. Two representative bone models are presented and their structural response under similar loading and boundary conditions is investigated. In the laminated composite approach, an idealized bone plate is modelled as a layered composite of discrete orthotropic and isotropic layers with a stepped variation in material properties along the thickness. In the functionally graded approach, an identical representative plate is modelled as a functionally graded structure with a gradual change in properties instead. Material properties of femoral bone used in this work were acquired from experimental data available in literature. A higher order shear deformation theory with seven degrees of freedom is then used to obtain deformation and stresses using analytical and finite element methods. Accuracy of the models are validated by benchmarking with 3-D elasticity solutions and published reference data in literature. Preliminary results show generally lower deformations in the functionally graded model with smooth and continuous stress profiles.
Investigation of the Urban Microclimate Variations Based on the Measured Weather Data: a Case Study of Education City and Lusail City of Qatar
Authors: Kabir Nahin , Abdelhafez Habiba , Sezer Nurettin , Hassan Ibrahim Galal , Wang Liangzhu (Leon) , Rahman Mohammad Azizur
Published: February 2024

Due to significant cooling requirements, urban buildings in hot climatic regions require careful analysis of Urban Heat Island (UHI) and Urban Wind Sheltering (UWS) effects for accurate design of cooling systems. Most studies considered microclimatic data from a nearby weather station, estimated by remote sensing or CFD simulation, all of which carry numerous variables and could yield erroneous results. The most reliable source would be to use data directly measured by weather stations in the study area. To this end, this study investigates the UHI and UWS effects in Qatar based on the comparative analysis of hourly microclimatic data obtained from two urban weather stations in Lusail City and Education City and five established airport weather stations across Qatar for the entirety of 2022. From analyzing the difference in temperature (UHI intensity) and wind speed (UWS intensity) of urban and rural areas, a clear increase in temperature and a sharp decrease in wind speed is observed in both studied urban areas. According to the results, the highest UHI intensity recorded was 16.8°C on the 16th of May (summer) at 1 pm, and the UWS intensity was −65.9 m/s on the 17th of March (winter) at 4 pm.
Error Budget of Wafer Bonding Alignment System Based on Machine Vision
Authors: Wang Rui , Lu Sen , Yang Kaiming , Zhu Yu
Published: February 2024

Accurate wafer alignment is the key to achieving wafer bonding accuracy. High precision wafer alignment systems typically use machine vision to locate the aligned Mark on two wafers, and use complex mechanisms to perform multiple composite movements to achieve functionality, making the coupling effect of multiple types of errors more complex and challenging the error budget of wafer alignment systems. This paper proposes an error budgeting method for such machine vision based multi body precision systems. This method takes the Homogeneous Transformation Matrix (HTM) method as the core to model the system error and establish two types of error transfer chains. For the error chain involving visual measurement, an analysis method based on geometrical optics is proposed to consider the influence of the position and orientation errors of the optical path components. Then organize the possible error sources in the system and model the parameters of each error based on actual test results. Combined with the process flow, customize the error model for each link. Finally, perform Monte Carlo simulation. Using the aforementioned method to budget errors for a certain configuration of wafer alignment system, main error sources were identified, and accuracy indicators were proposed based on the alignment accuracy requirements of ± 200nm. The rationality of the error budget conclusion in this study has been verified through experiments on the construction machine.
Four Purchasing Levels in Prototyping
Authors: Fadda Dani , Rios Oziel , Summers Joshua
Published: February 2024

A method for categorizing a physical prototype by reviewing the purchasing demands is offered. Four levels of purchasing are identified to procure materials for developing a physical prototype: (1) complete buyout, (2) buy major components, (3) buy for repurposing, and (4) buy raw materials only. These purchasing levels are presented with examples along with a decision tree to identify the purchasing level for components on any project. A design course, which allows all four purchasing levels, is also described as the background of this paper.

The objective of this paper is to provide a tool for faculty or project mentors to identify the level of their design team’s purchasing demand and anticipate subsequent activities that can follow the purchase. The purchasing level can be aligned with the project requirements even though the level can also be influenced by the pedagogical outcomes of a course.
Numerical Study of Distributed Acoustic Sensing (DAS) for Railway Condition Monitoring
Authors: Jones Michael , Rahman Md Arifur , Taheri Mohammad , Taheri Hossein
Published: February 2024

One of the most paramount factors for the railroad industry is the safe transportation of cargo and passengers. For the safe movement of locomotives, real-time tracking of trains and their cargo is critical and necessary. Current tracking systems face many challenges from weather interference to expensive implementations. Fiber optic acoustic detection has been developed for application to the railroad industry to improve the reliability of tracking locomotives along their route. Due to the wide variety of circumstances that the system could encounter, the in-situ testing of these systems has proven to be highly expensive. To reduce the cost of testing, finite element analysis is used in this study to determine the effectiveness of fiber optic acoustic detection in a variety of circumstances. The numerical results indicated that the properties of the material surrounding the cable have a significant effect on the accuracy, sensitivity, and effectiveness of the system. In particular, the density and Poisson ratio of a material are highly important to the efficacy of the detection system. The more compact material surrounding the fiber, the better acoustic matching occurs, and the stress/strain distribution is more uniform causing a better detection by the fiber optic system. In addition, the location of the fiber with respect to the applied external load is a critical parameter affecting the accuracy and probability of the detection by the fiber optic system.
Mechanical Analysis of an Additive Manufactured Deflecting-Tapered-Land Hydrodynamic Thrust Bearing
Authors: Yasko Isaiah , Downs William , Fais Collier , Ali Muhammad , Wisner Brian , Walker Rick
Published: February 2024

The research conducted here aims to expand the operating load range and offset manufacturing costs of tapered-land hydrodynamic bearings by creating deflecting bearing sectors through use of selective laser sintering. The motivation of this study comes from the fact that the required taper depth of tapered-land hydrodynamic thrust bearings is determined before manufacturing and is dependent on the expected operating axial loads. If the applied load exceeds the range for which the taper depth was selected for, the bearing will not operate efficiently, and an increased rate of wear will occur. Here, the bearing sectors are designed to deflect during applied loading; this acts as a self-governing device that allows the bearings to operate efficiently over a wider range of applied axial loads compared to their traditionally manufactured counterparts. Experimental analysis was conducted on selective laser sintered aluminum alloy tensile samples to obtain necessary material properties. Three bi-directional bearing sectors having an initial taper height of 88.9 μm were modeled with internal features that allow and limit deflection during pressure generation and bearing operation. The internal features can only be manufactured using additive manufacturing techniques such as selective laser sintering. A mechanical analysis was conducted in ABAQUS/Standard using the material data captured from the tensile tests to show that the bearing sectors deflect 38.8 μm, 64.1 μm, and 76.8 μm due to in-service film pressure distributions. The results of this analysis provide evidence that additive manufacturing can be used to expand operating loads and offset costs of traditional subtractive manufactured hydrodynamic bearings through tailoring of internal structures during manufacturing.
Experimental Investigation of Radiative Cooling Potential in Mediterranean Basin Countries
Authors: Farahat Mohamed A. , ElNaggar Shahd , Kader Ahmad M. , Ahmed Shehab , Rashad Muhammad I.
Published: February 2024

Radiative cooling (RC) is a cost-effective and electricity-free method of heat dissipation through infrared radiation, offering potential energy savings and reduced reliance on conventional cooling systems. Its application is particularly advantageous in regions with high energy costs and limited electricity access, benefiting low-income households and developing nations. RC aligns with sustainable development goals, including climate action, affordable clean energy, and sustainable cities, by mitigating greenhouse gas emissions from power generation. However, further investigations are needed in humid regions, such as Mediterranean countries, due to humidity’s impact on RC performance. This study experimentally explores RC potential in the Middle East and North Africa (MENA) region using economically accessible materials. The emission spectrum of materials -in addition to other parameters-can affect their efficacy as radiative coolers, with the atmospheric window (8–13 μm) being crucial for effective heat dissipation. The setup includes emitters and transmitters, isolating the emitter from warm surroundings and utilizing high-transmissivity transmitters within the atmospheric window. Calcium sulfate dihydrate (gypsum) and calcium carbonate serve as emitters, while polyethylene (PE) and polyvinyl chloride (PVC) act as transmitters. Experimental tests conducted under various sky conditions reveal a temperature difference ranging from 0.97 to 5.57 degrees Celsius below ambient temperature. The combination of gypsum as an emitter and PVC as a transmitter demonstrates the most efficient cooling rate. These findings contribute to the understanding and implementation of RC technology in the MENA region, offering a sustainable approach to address cooling needs and energy challenges.
Chaos Detection in Planar Mechanism With Clearance Using Local, Global and Correlation Dimensions
Authors: Yousuf Louay S.
Published: February 2024

A planar mechanism with three moving parts is connected to a cam. The mechanism is consisted from crank arm, connecting rod, flat-faced follower, polydyne cam, and two guides with clearance. The level of chaos is investigated based on the value of the correlation dimension. Local and global embedding dimensions described the exponential function of each point of the contact force with respect to the state space domain. An average mutual information algorithm is used to calculate the value of time delay. Time delay, decorrelation time, and ‘bad’ predict time are used to calculate local, global, and correlation embedding dimensions. SolidWorks program is used in the calculation of contact force at different cam speeds and different guides’ widths. The algorithm code of the dynamic tool is used to calculate local, global and correlation dimensions. Local Lyapunov exponent is calculated using MatLab code of the dynamic tool algorithm based on the values of time delay, local and global embedding dimensions. The investigation of the dynamic simulation of the contact force between the cam and the follower is considered in the presence of crank arm and connecting rod mechanism.
Teaching Engineering Dynamics Using Interactive Pedagogies and Entrepreneurial Minded Learning
Authors: Chauhan Vedang
Published: February 2024

Engineering dynamics is a vital field for many engineering disciplines, but it can be challenging for students due to its mathematical and physical concepts. Traditional teaching tools like textbooks and whiteboards rely on static diagrams and representations that don’t fully capture the dynamic and complex nature of motion. Engineering dynamics demands a more hands-on approach, with advanced tools and technologies like computer simulations, virtual reality tools, and physical experiments enabling students to observe and manipulate motion in real-time. This research explores innovative teaching methods, including interactive and entrepreneurial-minded (EM) learning, to improve students’ engagement, learning outcomes, and conceptual understanding. The module developed involved exciting activities allowing students to apply theoretical learning to experimental setups, collect and analyze data, and write professional reports and presentations. The module aimed to foster an entrepreneurial mindset by encouraging students to identify opportunities, brainstorm ideas, and connect multidomain knowledge for problem-solving. Results showed that the module increased classroom engagement, improved students’ conceptual understanding, and nurtured an entrepreneurial mindset. This research can help educators develop more effective pedagogical approaches to this critical subject, benefiting both students and the engineering community.
Numerical and Experimental Evaluation of an Enhanced Boundary Node Path-Planning Method for Agri-Robots in Dynamic Environments
Authors: Saeed R. A. , Carabin Giovanni , Vidoni Renato , Von Ellenrieder Karl
Published: February 2024

The agro-forestry sector is one of those that could benefit from new technologies and robotic applications to adapt to climate change effects, population growth and globalization. These applications can improve the efficiency and performance of the operations, as well as the products’ quality and traceability. Anyhow, the possibility to automate many of the applications carried out in the open field is related to the development of mobile platforms able to move and adapt to highly unstructured environments. Within this context, this work focuses on the development of a path-planning algorithm for UAVs navigating through an orchard/vineyard environment without colliding with static obstacles (e.g., plants) and/or unexpected ones (e.g., people or other robots operating in the same area). The path-planning strategy is grounded on an enhanced Boundary Node Method (BNM) and a re-planning approach is considered to recomputing and reconfiguring the path in case of unexpected obstacles that prevent the robot from following the original one. The developed method has been firstly evaluated in a simulated environment (i.e., Gazebo simulator), considering different combinations of obstacles and robot tasks. The same numerical experiments were then tested in a real emulated orchard scenario. The results showed good path-tracking capabilities in case of both known and unknown obstacles.
Frequency Controls of O- and X-Carbon Nanotube Reinforced Rings With Light-Activated Shape Memory Polymers
Authors: Li Hongjie , Deng Yan , Fan Mu , Wang Dan , Tzou Hornsen
Published: February 2024

Ring structure has been widely used in aerospace, architecture and other fields. Precise control is required for some precision equipment composed of ring structures. However, the ring structure is lightweight and has high flexibility, so it is easy to be disturbed by external excitation. It is very important to control the vibration of the ring by using sensors and actuators. Traditional passive and semi-active dynamic shock absorbers are mature and effective, but they need to occupy a certain space and cannot be organically combined with the ring structure. Based on the concept of smart structures, smart materials as sensors and actuators are directly pasted on the surface of the ring, forming the sensing and control system of the smart ring structure. Among them, the light-activated shape memory polymer (LaSMP) exhibits low density, large deformation, non-contact actuation and little temperature change during transformation. It is a novel smart material with great application potential. Under ultraviolet (UV) light illumination, the Young’s modulus of LaSMP changes greatly and the shape can be restored before deformation. LaSMP has a small temperature range when driven and produces no electric or magnetic fields, so there are few restrictions on application. The dynamic stiffness and shape memory properties of LaSMP can be applied to the vibration control of structures. Frequency control is an important method in the vibration control of ring structures. By adjusting the natural frequency of the ring, the resonance of the structure under the external excitation of some frequencies can be avoided. The Young’s modulus of the LaSMP changes under UV light illumination. The change in the Young’s modulus will affect the stiffness of the ring and change the natural frequency of the ring. In this study, two distribution types of carbon nanotubes (CNTs) are investigated, namely, the O-distribution type and the X-distribution type. A LaSMP is uniformly distributed on both the inner and outer surfaces of the ring. This study aims to control the frequency of O- and X-CNT reinforced rings by using the dynamic stiffness characteristics of the LaSMP and compare the frequency control effects of these two distributions. The dynamic stiffness model of the LaSMP is introduced and the natural frequency of the laminated rings is given. The natural frequency of O- and X-CNT reinforced rings laminated with LaSMP before and after light irradiation are analyzed. The variation of natural frequency during UV irradiation is studied, which verifies that the LaSMP can be used for frequency control of the ring. Finally, the effects of two distribution types of CNTs on frequency control efficiency are compared.
Multi-Channel Vibration Control of Conical Shells Based on Flexoelectric Effect
Authors: Li Haoran , Fan Mu
Published: February 2024

The flexoelectric effect in solid dielectric is another form of electrol-mechanical coupling, which is different from piezoelectric effect. Flexoelectricity usually refers to the ability of a dielectric body to polarize under non-uniform deformation, which is a electrol-mechanical coupling phenomenon between the electric field and the strain gradient. The flexoelectric smart structure can realize the sensing, vibration control and stability control of the structure, so the flexoelectric smart structure has a broad application prospect in engineering applications.

In this paper, the vibration control of a conical shell with multiple flexoelectric actuators is studied, and the optimal position distribution of the flexoelectric actuators is predicted by using the neural network model. In the physical model, the AFM probe is placed on the upper surface of the flexoelectric patch to induce a high intensity non-uniform electric field on the flexoelectric actuator, thus generating the internal stress of the flexoelectric actuator patch according to the reverse flexoelectric effect. The case studys show that the high intensity non-uniform electric field generated by the AFM probe has almost zero contribution to the electric field in the area far from the contact point, so the stress generated by the converse flexoelectric effect is mainly concentrated near the AFM probe, and the size and shape of the torsion plate have very limited influence on the actuation. Based on the assumption of small deformation and linear displacement, considering the vibration control of multiple flexoelectric actuators on the truncated conical shell, the lateral displacement results controlled by multiple torsional electric actuators can be calculated by the superposition principle. When multiple flexoelectric actuators work together, when the same flexoelectric actuator is in different positions, it may produce opposite lateral displacement at a point on the surface of the truncated conical shell, this situation will make the vibration displacement of the flexoelectric actuator cancel each other. The approximate optimal distribution positions of the multi-channel flexoelectirc actuators were obtained through experimental simulation.
Cast Silicone Robotic Gripper in Underwater Applications
Authors: Liu Wen , Shin Minchul
Published: February 2024

The robotic gripper is widely used in manufacturing and other areas in modern society. Robotic grippers have the advantage of providing precise control and a wide range of torque output and size for different applications. Power sources of robotic gripers are variable like pneumatic, hydraulic, electric, or mechanical systems. Pneumatics gripper is one of the most common and popular types; Pneumatics robotic grippers have advantages of providing wide range of power output, low cost, easy to maintain, and more. At the same time, the pneumatic gripper is more flexible for different sizes. The small pneumatic gripper will still be able to provide strong gripping force and precise control.

Robotic grippers come more in a solid form that is construed by metal or other solid material. The soft robotic gripper is another form of robotic gripper that has the advantages of adapting to irregular shapes, able to withstand blunt force trauma, and able to grip fragile objects. Silicone rubber pneumatic soft robotic gripper combined advantages of pneumatic system and soft robotic to provide a precise control, strong gripping force, adapting to irregular shape, and more.