bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Particle Overlapping Impacts in Erosion Process
Authors: Zang Xuerui , Cao Xuewen , Xie Zhenqiang , Zhang Jun , Li Yijie
Published: January 2022

To improve the accuracy of the erosion prediction, it is necessary to consider the influences of adjacent particles in the calculations. Therefore, in the present work Johnson-Cook hardening criterion and Johnson-Cook damage criterion are used in ABAQUS software to study erosion crater morphology and stress distribution on target materials subjected to overlapping impacts of spherical particles. The results show that the impact location of the adjacent particles, which is defined as the horizontal distance between the solid particle impacting spot, can significantly affect the erosion magnitude and pattern. As the horizontal distance between two impacts increases from 0 to 0.6 times the particle diameter, the interaction of the craters gradually decreases. When the horizontal distance is beyond 0.6 times the particle diameter, the interaction between two craters is disappeared. Furthermore, the depth difference between two craters is increased under the impact of adjacent particles. As the impact velocity increases from 14 m/s to 22 m/s, the difference between the depth of two craters is increased from 3.23 μm to 14.7 μm. When the impact angle increases from 25° to 85°, the depth difference between the two craters is increased from 0.11 μm to 14.40 μm. The numerical simulation of erosion process can provide a scientific basis for more elaborate erosion modeling.
A Numerical Study on Effect of Tool Roller Rotation on Channel Springback
Authors: Nikhare Chetan P.
Published: January 2022

The current work is an extension of the work published at IMECE2020. The study presents the innovative patented technique to reduce the springback in channel deformation. Springback is one of the common defects in sheet metal forming and is a constant research area due to continuous push on lightweight to decrease the fuel consumption and decrease the environmental impact. To follow the federal environmental guidelines the option is either use the lower density material or use the lower gages of advance high strength materials. In both cases springback will be an issue as the lower density material will be having lower modulus of elasticity and even the elastic values are higher in the higher strength material, with respect to strength the elastic recovery increases. With these many challenges with the materials and their properties which influences the springback, other possible innovative forming processes are applying electricity through the material after forming and before the release of the load, performing warm or hot forming, die compensation, etc. One such innovative and patented process which is studied in the paper is using rollers in the tool i.e., in die and punch during the forming process. During the channel deformation process the punch and die rollers rotate with a given rotations. The rollers are also set to rotate in either clockwise or counterclockwise direction. In IMECE2020 the work was published on considering the single roller rotation value in all cases i.e., from Case3 to 10. In this paper, four more roller rotations were studied to see the effect of tool roller rotation on the springback. The process was simulated in ABAQUS finite element software. The springback profile, springback angle and stresses in the channel were studied. It was found that with increasing the roller rotations the springback decreases.
Experimental Study of Gas-Liquid Displacement in a Porous Media Microchip by Digital Image Analysis Method
Authors: Yang Shuo , Kong Gaopan , Wu Zan
Published: January 2022

Gas-liquid displacement is still a complex and challenging topic in the field of nonequilibrium physics and many industrial applications. In this study, pore-scale displacement of gas-liquid flow in a porous medium was investigated. A digital image analysis method was used to process the images captured by a high-speed camera. The invasion pattern demonstrated that an increase in viscosity of the displaced liquid tends to decrease the finger width and the number of fingers. The effect of liquid viscosity on the invasion velocity was also investigated. The invasion velocity changes monotonously with the viscosity, showing an opposite trend at high and low gas flow rates, which is attributed to the viscous resistance of the liquid phase and the mass balance of the gas phase. Then the invasion area was measured and the N2 displacement ratio was used to estimate the injection efficiency. The displacement ratio decreases with the increase of liquid viscosity and gas flow rate. Finally, the invasion dynamics was studied. It revealed that the gas tip moves in a stepwise way, i.e., the tip goes forward, and then it stays there for a while and then goes forward again. The gas tip splits and expands in side directions and also moves backward when the gas pressure is not high enough to overcome the forward capillary pressure, which can be found for all the displaced liquids in this study.
Generation and Parameterization of Forced Isotropic Turbulent Flow Using Autoencoders and Generative Adversarial Networks
Authors: Kanishk  , Nandal Tanishk , Tyagi Prince , Singh Raj Kumar
Published: January 2022

Autoencoders and generative neural network models have recently gained popularity in fluid mechanics due to their spontaneity and low processing time instead of high fidelity CFD simulations. Auto encoders are used as model order reduction tools in applications of fluid mechanics by compressing input high-dimensional data using an encoder to map the input space into a lower-dimensional latent space. Whereas, generative models such as Variational Auto-encoders (VAEs) and Generative Adversarial Networks (GANs) are proving to be effective in generating solutions to chaotic models with high ‘randomness’ such as turbulent flows. In this study, forced isotropic turbulence flow is generated by parameterizing into some basic statistical characteristics. The models trained on pre-simulated data from dependencies on these characteristics and the flow generation is then affected by varying these parameters. The latent vectors pushed along the generator models like the decoders and generators contain independent entries which can be used to create different outputs with similar properties. The use of neural network-based architecture removes the need for dependency on the classical mesh-based Navier-Stoke equation estimation which is prominent in many CFD softwares.
Developing HVAC System Terminal Units Control Sequence Utilizing Game Theory Rules
Authors: Khazaii Javad , Khazaei Ali
Published: January 2022

Human thermal comfort depends on multiple factors such as temperature, humidity ratio, air velocity, metabolism etc. Two of the most important of these parameters that are being controlled simultaneously via air conditioning system in spaces are temperature and humidity ratio. Achieving thermal comfort in multi-occupancy spaces occupied with people with different levels of acceptable thermal comfort not only can help creating more desirable experience for majority of the occupants in these spaces, but also can save energy by optimizing the operation of the air conditioning system and avoiding unnecessary energy consumption when there is no need for controlling temperature and humidity at pre-selected values. Meanwhile, research shows current measures of thermal comfort are at best 30–40% accurate, since they have been developed decades ago and based on the desired references of a specific group of people in that time. Space control algorithms that are generally written to hold temperature and humidity ratio based on a typical human response to parameters affecting thermal comfort should be customized to provide the optimum comfort level for people with different thermal comfort preferences occupying the same offices or spaces. Such optimization can be achieved via utilizing rules of game theory — which is a strategic method of decision making among competing or cooperating decision makers — to help finding the best combination of the temperature and humidity ratio. This helps to create thermal comfort for different combinations of occupants in the space with different thermal comfort preference. This work represents a new way of writing sequence of controls for air handling units, to maximize thermal comfort of all the occupants and at the same time creates opportunity for saving energy by avoiding single set-point for delivering air temperature and humidity ratio.
Cascade Utilization of Geothermal Waste Heat for Enhanced Outdoor Crop Production
Authors: Mignano Christopher , Dushaj Enea , Unnthorsson Rúnar , Dell Robert
Published: January 2022

Iceland’s harsh climate limits the number of harvestable cultivars that can be grown outdoors. While Icelandic heated greenhouses enable a larger variety of crops to be grown, their upkeep is labor and resource intensive, and the associated costs can be prohibitive. Professor Robert Dell, Director of the Laboratory for Energy Reclamation and Innovation (LERI) at the Cooper Union has developed an intensive cascade utilization system using waste steam condensate and hot water as a working fluid that creates an outdoor shallow network of plastic pipes for heating garden soil. This research and development, which began in 2007 in New York City and 2009 in Iceland, compares plant growth between heated and control gardens. Previous studies’ test beds used municipal district heated wastewater, waste fluid from a geothermal heated swimming pool, and waste hot water from a traditional heated greenhouse. This paper analyzes the results of enhanced outdoor crop production using a new small-scale, high yield garden from the 2019 growing season at the Agricultural University of Iceland (Landbúnaðarháskóli Islands). The plants studied include turnips, zucchinis, tomatoes, oregano, and a variety of peppers. A plant growth index was developed for analytical purposes. It takes the weighted average of measurements of plant height and the two widest stem spread diameters to quantify growth before the harvest. The plants in heated gardens grew approximately 45% taller and wider on average than those in unheated beds.
Experimental Investigation of Multi-Component Emulsion Fuel Stability
Authors: Hentges Nicholas , Parveg A. S. M. Sazzad , Ratner Albert
Published: January 2022

The emulsification of water with liquid fuels to modify combustion characteristics has been of great interest to the combustion research community for some time. The emulsions are usually comprised of only water combined via ultrasonification (or other mechanical methods) with a base hydrocarbon fuel. These emulsions show improved combustion characteristics, such as lower combustion temperatures, and lower emissions. One of the main issues with these emulsions, however, is that these emulsions are not stable and are prone to phase separation over time, which inhibit the economic viability and practical application of these fuels. There are a multitude of ways being researched to improve fluid stability, including new mixing techniques, the addition of nanoparticles, as well as the addition of other fluids. The addition of ethanol to water-based emulsions has been shown to decrease the size of water droplets in the emulsion, allowing for a more homogenous mixture. With the aviation industry being a sizeable source of the global emissions caused by transportation, methods of lowering the emissions of aviation fuels as well as greener alternatives are needed. Present research quantitatively studies how the addition of ethanol to water and jet fuel emulsions affects the stability of the emulsion. A non-invasive, quantitative, and economical method for determining phase separation is used to study the stability of these multi-component mixtures. The system periodically measures the phase separation of the fluid column by automatically shining light through the fluid and detecting how much interference is created by the fluid. The system does this at five different depths of the fluid so the phase separation of the emulsion can be tracked in more detail. Ethanol and water are studied at mixtures of 5%, 10%, 15%, and 20% ethanol by weight and 5% and 10% water by weight emulsified with jet fuel. It is expected that the present research will lay additional foundation for the future study of fuel emulsion stability, as well as spark additional interest in utilizing emulsions to improve fuels.
Development of Single Piece Designed Compliant Locomotive Mechanism
Authors: Rouse Ciaphus , Estrada Benjamin , Sailors Caleb , Schneider Christian , Henderson Sean , Tekes Ayse
Published: January 2022

Biomimetic robots have been the focus of many studies for the last decades since the motion in nature is accomplished through the bending of the flexible arms once subjected to an input force, displacement or torque as opposed to their rigid body counterparts thereby increasing the workspace. This study presents the design, analysis, and modeling of a novel monolithically designed compliant mechanism. The mechanism consists of two translational springs, three sliding carts, housing for the two servo motors, and two rigid-flexure-rigid (RFR) arms. While the main body of the biomimetic robot can be 3D printed using polyethylene terephthalate glycol (PETG), the RFR links are 3D printed in thermoplastic polyurethane (TPU) to prevent yielding when loaded. The mechanism model is derived using D’Alembert’s principles, pseudo rigid body modeling, and kinematic constraints. Finite element analysis is performed in MSC Adams and simulation model outputs are validated through experimental data for forward motion.
A Study of Stress Intensity Factors in Lozenge Pattern of Joints
Authors: Hithendra K. , Prakash Raghu V.
Published: January 2022

Riveted joints are very crucial in many industrial applications. Several studies have been carried out to understand the response of lap joints and butt joints with single and double row of rivets emphasizing on total fatigue life and residual stress evaluation. Studies that deal with initial crack and stress intensity factors (SIF) during its progress are very less. In addition, there is very less data on joints formed with Lozenge pattern. The present work aims to bridge this gap with studies on the Lozenge pattern of rivets with focus on the SIF in strap plates, given the fact that the initial cracks appear on them when the strap thickness is less than or equal to the plate thickness. The strap plate considered has six joints in Lozenge pattern in 3-2-1 fashion. Cracks were induced at different joint locations and variation of the stress intensity factor with progress in crack size was evaluated using Finite Element Analysis. Studies were conducted for various interference levels of practical interest. The most critical location of the crack and the most beneficial levels of interference were identified. Limits of interference, beyond which SIF increases drastically, were identified. Combined influence of interference and neighboring geometrical aspects such as holes and boundaries was recorded. Studies were also conducted to evaluate if there is a need for uniform interference at all joint locations. Also, to simulate the real world scenario, several combinations of random interference were induced at the joints and the SIF results were compared with that of uniform interference values. Finally, the effect of change in back pitch of the joints was also studied.
Theoretical Characterization of Liquid Sloshing in Containers
Authors: Karthick S. , Satish V.
Published: January 2022

This paper theoretically characterizes the sloshing phenomena at the free liquid surface in partially or filled stationary containers based on the analogy with surface gravity waves. The oscillations of the liquid surface and the associated dynamics of the liquid-air interface results in interfacial wave displacement of two types progressive (in-phase) and standing (out of phase) modes. This study involves a rectangular stationary fluid tank partially filled with the tested fluids and subjected to the dominant progressive wave at the liquid-air interface. The sloshing strength is decided based on the temporal progression of the generated wave spectrum obtained utilizing small-amplitude wave theory and linear stability analysis in combination. The expressions for determining the angular frequency, the phase speed, and the corresponding temporal growth rate of the progressive disturbances is derived. The tested fluids include standard liquid water and commercially preferable fluids ethylene glycol and glycerol. This model developed based on the irrotationality of fluid motion neglects the viscous influence and comprises the gravity and the surface tension mimicking a practical scenario. Utilizing deep-water assumptions, the effect of surface tension has been determined for wavenumbers in the range of 490–1250 rad/m. The independent evolution demonstrates the influence of surface tension on the temporal growth rate. Water with the maximum surface tension has a higher growth rate than a low surface tension fluid ethylene glycol among the tested fluids. The effect of surface tension is to escalate the temporal growth rate leading to instability and increased liquid sloshing rate.
Experimental and CFD Analysis of a Helical Coiled Heat Exchanger Using Various Fluids
Authors: Saiyara Shariqa , Hossain Nayeem , Ahsan Farzana , Sifat Najmus Saquib
Published: January 2022

Shell and Helically coiled heat exchangers enhance the heat transfer rate by increasing surface area and inducing secondary fluid flow. In this paper, the heat transfer rate and effectiveness of a shell and helically coiled heat exchanger using two fluids have been analyzed experimentally and numerically. The majority of previous studies in this regard has been on helically coiled heat exchangers with water as the working fluid. The application of helically coiled heat exchanger in cooling the tube side fluid with a coolant inside the shell has been reported in many studies. There have not been many such studies using other working fluids like water-ethylene glycol inside the tube in a coiled heat exchanger. In this work, a helically coiled tube heat exchanger has been designed and a corresponding 3D computational fluid dynamics (CFD) model has been developed. Assessment has been done on the feasibility of using ethylene glycol-water mixture as a working fluid by conducting an experimental and numerical comparison with water. Two different fluids have been used inside the helical tube, water and water-ethylene glycol (50-50). An experimental set-up has been fabricated for evaluation of thermal properties of the shell and helically coiled heat exchanger. This work analyses the behavior of parameters like heat transfer rate, pressure drop and effectiveness by introducing hot fluid through shell and cold fluid through tube under variable flow rate. Enhancement of heat transfer rate has been observed for ethylene glycol-water mixture at higher mass flow rate. The simulation data is in close agreement with the experimental data.
Crystallinity-Induced Acceleration of Intergranular Cracking in Thin-Film Interconnections Under High Current Density
Authors: Akasaki Shota , Miura Hideo
Published: January 2022

The degradation process of the crystallinity of grain boundaries in thin-film interconnections was visualized by applying EBSD analysis under high current density. The grain boundary diffusion was accelerated by electromigration only along random grain boundaries with low crystallinity. The crystallinity (IQ value obtained from EBSD analysis) of grain boundaries varied drastically depending on manufacturing process such as temperature, gas pressure, substrate material, and so on. The effective activation energy of self-diffusion of component element was dominated by the crystallinity of random grain boundaries. The measured value obtained from the low-crystallinity interconnections was much lower than that obtained from the thermodynamically stable bulk material, and therefore, the lifetime of intergranular cracking decreased to one hundredth in the worst case.
Inline Topology Measurement of Material Jetted Metal Parts
Authors: Rehekampff Christoph , Kirchebner Benedikt , Krebs Florian , Irlinger Franz , Lueth Tim C.
Published: January 2022

In Material Jetting, build material is deposited as single droplets onto a platform. This offers potential advantages such as faster processing and cheaper raw material compared to powder based processes. For metals, this technology is subject of several research projects. Due to variations in droplet size, the process inevitably results in deviations between the desired and the actual height of a printed layer. Such deviations can add up over several layers and thus lead to an unacceptably high overall geometrical deviation of the component.

One possible solution to this problem is the compensation of local height deviations by adjusting the build strategy (droplet size, droplet spacing) in the next layer. For this, it is necessary to measure the geometric deviations of the local layer heights. However, the temperatures of up to 300 °C inside the build chamber pose a challenge for the integration of a measuring system.

In this work, a process monitoring system was integrated into a previously developed printer for Material Jetting of aluminum. The system consists of an optical confocal sensor that enables contactless distance measurement. To avoid overheating of the sensor, it is located outside the build chamber. An infrared filter glass allows measurement from the outside, while heat radiation from the build platform is absorbed by the glass. The sensor is water cooled to ensure a safe operating temperature.

A calibration object and printed aluminum components were measured to validate the system. The measurement results show the potential of the system for inline process monitoring for Material Jetting. Based on this, the development of a closed-loop layer height control is now possible.
Design of a Training and Evaluation System for Surgical Robot Operation Based on Chai3d and LSTM Algorithm
Authors: Gu Chenchen , Hou Qitao , Ge Zhaojie , Teng Zhiqiang , Zhao Ping
Published: January 2022

Compared with traditional surgery, femtosecond laser minimally invasive surgery has many uncomparable advantages and will have a significant impact on the medical industry in the future. In this paper, a simple scene for laser minimally invasive virtual surgery training is designed, in which the testers can practice repeatedly until the basic operational requirements are met. The haptic device adopts the Geomagic Touch from American 3D Systems Company. Eight testers using Geomagic Touch handle perform four basic actions (clamping, adjusting posture, pushing / pressing, moving tiny objects) in the left interface virtual environment. Each action was performed 10 times by per tester. During the process of human-computer interaction, the position, attitude, speed, button and other information of the handle are collected in real time, and the collected data is saved in the form of text. The collected data is multivariate time series data. Based on the characteristics of multivariate time series data, this paper proposes a design of an evaluation system based on LSTM model to classify the collected data and evaluate the standard of surgical action according to the output probability of action classification.
Thermodynamic Behavior and Equation of State for Cryogenic Helium 3-4 Mixtures
Authors: Domenikos G-R. , Rogdakis E. , Koronaki I.
Published: January 2022

On this study the authors have derived and present an overall Equation of State for Helium 3 and Helium 4 mixtures. The point of the present study is to give equations that are usable for engineering low temperature applications such as dilution or Stirling refrigerators, without the need to make any approximations or having to use different models for different phase regions. The offered model uses all the existing data, experimental and theoretical, describing the different phases of the Helium 3-4 mixture. Additionally, to the pure data, in areas where no direct data exist the presented equations are such that they follow the expected and observed behaviors and in parallel continuously connecting the data refence points while being self-coherent and able to correlate the different thermodynamic values and their derivatives with each other. Furthermore, the effects of mixing properties in the total values have been studied and through the understanding and modeling of their behavior, combined with the equations of state for the pure isotopes the authors have been able to extend the range of the equations outside of any current models by offering a range from near absolute zero to over the lambda line of Helium 4. Because of its importance in applications also the osmotic pressure of the mixture has been included. Lastly in order to make the model more usable for thermodynamic cycles the thermodynamic maps have been created where one can directly foresee the expected behaviors without the need to run the calculations.
Design of a Modular Hand Exoskeleton for Rehabilitation and Training
Authors: Dragusanu Mihai , Iqbal Zubair , Prattichizzo Domenico , Malvezzi Monica
Published: January 2022

Nowadays, the rehabilitation process can significantly increase the efficacy exploiting the potentialities of robot-mediated therapies. Robot rehabilitation is an emerging and promising topic that incorporates robotics with neuroscience and rehabilitation to define new methods for supporting patients with neurological diseases. In this paper we present the design of an innovative exoskeleton for hand finger flexion/extension motion rehabilitation and training. It is designed to be modular, wearable, and easy to control and manage. It can be used by the patient in collaboration with the therapist or autonomously. The paper introduces the main steps of device design and development and presents and compare three different solutions.
Real-Time Sound Source Localization Using a Parabolic Reflector
Authors: Liu Chang , Mao Xu , Wang Chang , Heredia Juesas Juan , Martinez-Lorenzo Jose Angel
Published: January 2022

Contrary to the active detection methods, the passive sound source localization technologies only rely on the differences among the signals recorded by different receivers to localize the object generating the sound wave, without the knowledge of the sound source profile and excitation time. Time domain investigation methods have been widely applied in the analysis of sound source tracking, which greatly suffers from the high ambient noise problems. Instead, this paper applies an imaging method based on frequency domain cross-coherence (FDCC) operation to reconstruct the source to alleviate the effect of noise. The experimental results show the reliability of this method to recover the source in 3D. Moreover, a parabolic reflector is proposed to further increase the measurement amplitude and signal to noise ratio. The FDCC method successfully localizes the source even if the propagation path of the sound wave is disturbed by the reflector.
Synthesis-Structure-Property Relationship for Ultra-Soft Tissue-Equivalent Alginate Hydrogel
Authors: Li Xiangpeng , Gou Jihua , Ilegbusi Olusegun J.
Published: January 2022

Alginate hydrogels have properties that are similar to extra cellular matrix (ECM). Thus, their mechanical behavior approximates soft tissue, which makes them desirable for production of tissue-equivalent soft deformable structures. This study aims to determine the synthesis-structure-property relationship for alginate hydrogel with Young’s modulus in the range of 100∼101 kPa, equivalent to that of human lung tissue. Hydrogels are hydrophilic polymers with 3D network. Homogeneous alginate hydrogels are synthesized by direct mixture of sodium alginate and CaCO3, followed by the addition of D-glucono-δ-lactone to initiate in-situ Ca2+ release and gelation. The influence of alginate concentration and molar ratio of the constituent calcium ion to carboxyl group are evaluated while the Young’s modulus of the hydrogel is carefully controlled within the desired range. Elongation testing is performed to determine the initial-stage Young’s modulus of the material. FTIR is used to characterize the influence of synthesis parameters on the chemical bonds. Empirical relations are established between synthesis parameters and the mechanical property. The result of the study will be subsequently used to guide the additive manufacturing of soft deformable structures based on alginate hydrogels.
Experimental Investigation on Falling-Film Droplet Flow Behavior on Varied Horizontal Tube Spacing
Authors: Prudviraj K. , Deshmukh Sandip , K. Supradeepan
Published: January 2022

The hydrodynamic behavior of the liquid film has a great significance in horizontal tube falling-film flow. Basic flow modes between inline horizontal tubes include droplet flow, column flow, sheet flow, and intermediate flow modes such as droplet-column and column-sheet mode. The flow patterns between the tubes can be adjusted by flow rate, fluid properties, distributor type, tube spacing, and spraying width. Droplet flow is one of the fundamental flow modes, which is commonly found in industrial heat exchangers. In the present study, the complete progression of droplet flow phenomena between the inline horizontal tubes for tube spacing of 10/20/30/40 mm is visualized with the aid of high-speed photography. The Sobel edge detection algorithm with gradient function is adopted in this analysis to detect the edges. The results indicated that the droplet flow phenomena between the tubes can be broadly classified into the following phases; wavy droplet formation, droplet evolution, droplet elongation, droplet impact, and distribution of a droplet over the tubes. The development of detached spherical droplet pattern, neck formation and retraction stages were observed with increased tube spacing. For the same Reynolds number and different tube spacing, the difference in droplet impacting modes were observed. It is found that the droplet velocity increases with the increases in inter tube distance. The findings are useful for modeling a heat transfer analysis in droplets.
Thermal Expansion Simulation of Bi-Directional Taper Formation in Composite Hydrodynamic Thrust Bearings
Authors: Yasko Isaiah , Lutfullaeva Anbara , Fais Collier , Ali Muhammad , Alam Khairul
Published: January 2022

Tapered-land hydrodynamic thrust bearings require taper depths of approximately 20–100 μm to operate efficiently within the hydrodynamic regime. Machining the tapers in traditionally manufactured bearings increase production time and costs. The thermo-mechanical analysis presented in this work shows that the utilization of composite laminas in place of taper machining may be used to provide taper formation in hydrodynamic bearings by exploiting the thermal expansion produced from frictional heating. Thermal expansion of three different carbon/epoxy composite layups (AS-4/3501-6, IM7/3501-6, T-300/3501-6) was analyzed using ABAQUS/CAE composite module. The analysis shows that the composites provide bidirectional taper depths of 24.25 μm, 23.7 μm, and 22.27 μm while being subjected to in-service film pressures and temperatures.
Additive Manufacturing Process Parameter Optimization for Titanium-Alloy Orthopedic Implants
Authors: Gaur Bhanupratap , Ghyar Rupesh , Ravi Bhallamudi
Published: January 2022

Orthopedic implants are widely used for treating bone tumors and trauma defects in patients. The complex and organic geometry of patient-customized implants (PCIs) required in single order quantity makes them suitable for fabrication using additive manufacturing technologies such as Laser beam powder bed fusion. While there is considerable technical literature on these technologies, the choice of optimal process parameters to obtain the required quality considering the relevant applicable international quality standards for orthopedic implants is still a major challenge for the manufacturers.

This experimental work relies on the minimum requirements of various mechanical properties recommended by ASTM F3001-14 and ASTM F136-13 standards for determining the optimal process parameters for PCI manufacture. Ti6Al4V ELI (Titanium–6Aluminum–4Vanadium Extra-Low-Interstitial) alloy test samples were fabricated using a Direct Metal Laser Sintering (DMLS) system. The three most critical printing parameters, namely, laser power, laser velocity and hatch distance, were varied in three levels using the Taguchi approach. Properties such as ultimate tensile strength, percentage elongation and part density were considered for optimizing the process parameter combinations using VIKOR, a multi-criteria decision-making technique. The results show that a combination of moderate laser power, high laser velocity and low hatch distance values produce implants with superior mechanical properties. The proposed methodology and results are expected to help researchers and manufacturers in choosing the initial process parameters for PCI fabrication.
On the Mapping Problem in SLAM Approaches for Autonomous Robot Navigation
Authors: Raju Vomsheendhur , Selekwa Majura F.
Published: January 2022

Simultaneous Localization and Mapping (SLAM) is a well-known strategy for enabling robots to maneuver in unknown environments. The solution to a SLAM problem provides information about the location of the robot and the structure of the environment in a way that enables better decisions to be made by that robot. There are many ways of localizing the robot by using on-board sensors such as ranging sensors, motion sensors, and vision sensors; however, all SLAM methods tend to share features of the mapping strategy. Generally, there are two main mapping methods. One approach augments the coordinates of all landmarks in the environment with the robot pose as one state vector, and the second creates a 2-D or 3-D grid of the environment and then assigns occupancy levels of the landmarks in each grid location. Although both methods have been effective, they have some limitations. The first method is computationally burdensome since increases the size of the state vector whenever landmarks are observed; the second method treats all grid occupancy levels in binary form where all occupied grids are assumed to be at equal levels although certain grids may have occupancies that do not affect the robot mobility. This paper presents a simple but effective grid-based mapping strategy that integrates the path planning step for autonomous ground robotic vehicles. The map is presented as a 2-D surface on which each point is weighted based on observed landmarks and their sizes. This map is updated continuously as new landmarks are detected without changing memory requirements of the robot. The path planning task is implemented by joining points that are on a steep path towards the destination. Preliminary numerical results on its performance on path planning indicate the robot was able to follow the shortest path and the process is not computationally intensive.
Parametric Investigation on Thermal and Hydraulic Performance of Minichannel Heatsink
Authors: Atalay Ozan , Gultekin Murat , Cadirci Sertac
Published: January 2022

Insulated Gate Bipolar Transistor (IGBT) is one of the basic electronic components of rail and electric vehicle traction systems. They are used for switching and can perform this task very quickly. Regarding its operation, thermal modelling of IGBT modules is vital for obtaining temperature distribution for these components and thermal resistances of the entire IGBT as well. Nowadays, Computational Fluid Dynamics (CFD) is a robust and advantageous tool for modelling fluid flow and heat transfer problems that can be adopted to the thermal design of such critical components to better understand the effects of the design variables on the thermal-hydraulic performance of IGBT. This study is about conjugate heat transfer in a heat sink with diode and IGBT chips as heat sources and investigates the effect of minichannel porosity on Nusselt number (Nu) and the pumping power at several inlet Reynolds number (Re). The CFD analysis have been conducted parametrically and revealed that with increasing Re, both Nu and pumping powers increased significantly, indicating that heat transfer enhancement as well as power consumption are dominated by the flowrate. It is also shown that low minichannel porosities provide higher Nu and pumping power as well. The parametric studies provided a knowledge about the thermal-hydraulic performance of the IGBT and assisted to understand the effects of the governing parameters on the target functions.
Frequency Regulation With Connected Lighting Systems
Authors: Wang Peng , Brambley Michael , Poplawski Michael
Published: January 2022

The management of end-use energy loads, including commercial buildings, has been increasingly investigated as a promising source of services for the electric power grid. Lighting consumes about 17% of the total electricity use of U.S. commercial buildings; however, it may contribute significantly to services that improve the reliability and resilience of the grid due to its rapid speed of response. Connected lighting systems (CLS), which build upon solid-state light-emitting diode (LED) technology, can change their power demand more quickly than most other building electricity end-uses. But the potential of CLS to provide grid services has not been fully investigated. In this paper, we describe initial research to evaluate the potential of CLS for providing frequency regulation grid service. Frequency regulation is a reliability service that corrects in a matter of seconds for short-term changes in the balance between supply and demand that might affect the stability of the power system in a specific balancing area. Frequency regulation signals for a medium office building are generated from the normalized test signals for the PJM Regional Transmission Organization Reg-A and Reg-D regulations services. CLS are controlled in simulations to follow the Reg-A or Reg-D signal and thereby provide frequency regulation service. The performance of CLS providing frequency regulation is evaluated using the PJM 40-Minute Performance Score Template. The performance scores obtained for five different CLS categories responding to both Reg-A and Reg-D signals far exceed the minimum qualification score, a very promising result for CLS aiming to provide frequency regulation service.
A Proposed New Molecular Model for Liquids and Solids
Authors: Howlett Larry D.
Published: January 2022

Proposed: free, unconstrained molecules exist in pure liquids and solids. This new molecular model is a direct development from using vapor pressure as a primary variable for understanding seed storage and osmosis. Current seed models consider relative humidity as an important variable. Current understanding of osmosis considers chemical potential, concentration, and osmotic pressure as important variables.

My new concepts began 25 years ago with an engineering consulting project to design and build a warehouse for storing seeds. Solutions for design changes and supplier errors led to a new viewpoint: vapor pressure is an important variable for understanding stored seed. After extending this idea to modeling moisture transfer between a seed and its environment and two rejected papers about seeds, my model was different from the current textbook explanation for moisture transfer across a membrane: osmosis. After studying osmosis and its history, I concluded that vapor pressure is the driving force for moisture transfer across a membrane. The vapor pressure concept introduces a physical model for the osmosis process.

All I did was reexamine seeds and osmosis from a new viewpoint. Vapor pressure was introduced as an important variable. Since vapor pressure is the force per unit area resulting from molecular collisions, and osmosis occurs with liquid on both sides of the membrane, I proposed that free molecules must exist in pure liquids and solids.
Development and Performance Assessment of a Hydraulic Hybrid System
Authors: Wressell D. L. , Tartibu L. K. , Tekweme F. K.
Published: January 2022

The automotive industry has for some years considered hydraulic regeneration systems for use in hybrid vehicles; combining the concurrent use of an internal combustion engine and a hydraulic system to reduce fuel consumption and increase performance. This study describes the development of a hydraulic hybrid system using a small passenger vehicle (SPV) model and a hydraulic hybrid pump/motor (P/M) model. A model of an SPV vehicle was developed and validated using MATLAB Simulink. Simulations were performed to analyse and test the performance of the hybrid system. This study addresses the gap related to the prediction of the performance of the hydraulic hybrid system for use on an SPV. A novel control system was developed to simulate the drive cycle and predict the fuel-saving of the hydraulic hybrid system. Variables included accumulator size, hydraulic P/M displacement and accumulator pre-charge, which were adjusted to optimise the hydraulic hybrid system. The Fuel consumption of the model before the implementation of the hybrid system was calibrated with the recorded fuel consumption of the test vehicle. The hydraulic hybrid system was then developed and implemented to the SPV model along with a revised control system. The fuel-saving of a novel hydraulic hybrid control was estimated using MATLAB Simulink. A controller was developed to manage the distribution of energy between the hydraulic system and the diesel engine. The effects of the hybrid system on the brakes and the engine demand were analyzed. The results indicated a 45% reduction in diesel engine demand and a 65% decrease in brake usage throughout the drive cycle. The model of the hydraulic hybrid passenger vehicle predicted a fuel saving of approximately 17%. This study shows that the hydraulic hybrid system can potentially improve fuel consumption and optimize engine performance in passenger vehicles.
Tracking Control Design and Implementation of Multiaxial Controller for Social Robotic Devices
Authors: Cheng Marvin , Bakhoum Ezzat
Published: January 2022

In the recent years, robotic devices have been widely used to interact with human beings in various scenarios, including healthcare, education, tourism, and manufacturing applications. These applications of robotic devices have also been expanded to many social activities. These social robots can take the form of a traditional mobile robot or a humanoid system that provide one-on-one interaction. Among different types of robotic devices, the bio-inspired humanoid robotics has received extensive attention in therapeutic settings by providing psychological and physiological benefits. With the social benefits, humanoid type of social robots can be an important tool to assist people in many different situations.

To allow social robotic devices to better interact with human being, it is desired that these robotic systems can identify on-going human motions and respond to the motions by mimicking human movements. Thus, these systems need to acquire human motions and predict the types of these movements in real-time. Such a technique has been investigated by various research groups. Once the human motions have been identified, corresponding reactions of the robots can be determined accordingly, which usually requires the involved joints to move along specific trajectories. To synthesize such an interactive robotic system, a platform of a multi-axial robotic device, a motion identification model of human motions, a reference generator based on the identified motions, the sensors used for real-time motion measurements, and an adequate control strategy need to be integrated as a single system. The major bottleneck of such a system is that the processing and control units might not be efficient enough and can cause dramatic legacy. To validate the overall process, a simplified system was developed to investigate the feasibility of such an interactive robotic system.

In this study, an experimental multi-axial robotic arm was adopted. A developed motion identification model was used to determine the on-going motions of the interacting person. Once the motion being identified, the responding motion of robotic device can be determined based on a pre-selected motion library. The trajectories of individual joints of the robotic arm can then also be generated accordingly. The robotic arm was then following the pre-selected trajectories for corresponding interactions. To compensate for the nonlinear factors caused by existing mechanical/electrical components and the cross-coupled dynamics among the mechanical components, a control strategy that integrates an adaptive robust control method and a linear controller for motion tracking was applied. With the proposed control scheme, an adequate controlled outcome can be achieved.
Drone Pollination of Flowering Vegetation for Agricultural Applications
Authors: Diaz Guzman Sonia , Henspeter Devon , Taylor Megan , Duan Shawn
Published: January 2022

With an ever-changing climate, the decline in the bee population is forcing humans to find supplemental ways to pollinate. A mechanical substitute for a bee needs to be as efficient or better than bee pollination since it will require one person to do the work of many bees. Pollinating one flower at a time would be too time consuming to be effective, so a drone mounted pollen distribution device is the best direction to go to solve this problem. This is a game changing design to prevent a lack of food-producing plant growth as the bee population decreases over time. The design is a low-cost alternative that can be adjusted to meet the consumer needs based on the type of pollination. This design is easy to manufacture en masse due to its simplicity. The design and operation have been optimized using stress, torque, and safety factor analyses to ensure that the product can withstand the loads applied during operation.

This drone pollinator will have the ability to work for various drone types and plant pollens. With the use of commercial drones, the ability to distribute pollen to a large orchard or forested area will allow humans to supplement bee pollination on a large scale in the farming and forest conservation industries.
Strength and Quality of Recycled Acrylonitrile Butadiene Styrene (ABS)
Authors: Bibb Micah , Nowicki Margaret , McDonald Kenneth , Zander Nicole
Published: January 2022

Many times, when 3D printed parts exceed their useful life or when there is a mistake in the manufacturing process, that 3D printed material is thrown away. To avoid such waste, that material can be shredded up and re-extruded into useable filament. There are some concerns over the degradation of the material as it is recycled and reprinted. In this study, the strength and quality of ABS plastic as it is recycled and reprinted has been investigated. The ABS at each stage of recycling was printed into “dog bone” test samples for mechanical testing. The tensile strength was measured using an MTS Universal Testing Machine. Following the completion of these tests, the chemical properties of the samples were tested using thermogravimetric analysis and differential scanning calorimetry. With each recycle, the tensile load capabilities of the ABS dropped by an average of 5.93%; however, chemical tests showed no significant degradation in thermal strength.