bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and Analysis of a Drone Mechanism With 3-Axis of Rotation
Authors: Mathur Varun , Yee Raymond K. 
Published: February 2021

Abstract
A quadcopter is an Unmanned Aerial Vehicle (UAV) with 4 propellers providing required force for motion. It has four equally spaced rotors, typically arranged at the corners of a central body. With four independent rotors, the need for a swashplate mechanism like that in a regular helicopter is alleviated. Due to the rotation of the propellers attached to a quadcopter an upward thrust is generated. The maneuverability of a quadcopter is primarily controlled by adjusting the speed of each propeller attached to a rotor which in turn creates different lifting forces for maneuvering. The objective of this work is to design a 2-axes rotation mechanism for a shaft while its propeller rotates about its own (the 3rd) axis in a 1 m by 1 m quadcopter. Besides the spinning of a propeller axis, two other perpendicular axes in the mechanism are capable of pivoting in a flight which dynamically modifies the thrust vector direction and enhances the quadcopter’s maneuverability. The project was accomplished by performing several key tasks involving mechanism design using bevel gears, shafts, and motors, computational fluid dynamics analysis to determine aerodynamic thrusts and airflow pattern, rigid body dynamics analysis to evaluate forces and torques at different sections of the mechanism, and finite element analysis of mechanical components to optimize the stresses and fatigue as well as their corresponding safety factors. The final mechanism design provides mobility similar to a spherical joint capable of pivoting from −45 degrees to 45 degrees about 2 orthogonal axes for a small size drone. The results of rigid body dynamics analyses for a small size drone indicate that the minimum required motor torque is about 0.5 N-m, based on using a 40-mm driving nylon gear with gear ratio of 1:2 and an aluminum shaft with its propeller rotating at 2000 rad/sec, the nylon gear is good for 5 million cycles, the ABS plastic fixture is good for 10 million cycles and the shaft was designed for 1 billion cycles of fatigue life. Further study would be required in developing the control system for this quadcopter design and optimizing the entire structure of the drone, prototype verification of the mechanism design on flight maneuverability is also recommended. A parallel study using the layered composite design is currently undertaken. A comparison between metal and fiber composite shafts on weight reduction and performance of the mechanism would be revealed in our next paper.
3D Digital Manufacturing Applied on Drilling of 7050-T651 Aluminum Performed by Robot
Authors: Zambrano Degan Bruno , Franco Barbosa Gustavo , Guerra-Zubiaga David , Nasajpour-Esfahani Navid , Al Mamun Abdullah 
Published: February 2021

Abstract
With advances in automation, industry seeks for optimization while new products are developed and manufacturing processes are becoming smarter. In this sense, virtual manufacturing validations have been demanded for reducing the cost with physical prototypes, ensuring ergonomically safe processes and increasing the quality of processes by emulating it realistically, levering automation utilization in industry environments with a faster and safer manner. By that, this research proposes the use of Tecnomatix Siemens® PLM software for process simulation of 7050 aluminum drilling, material which is widely used in aerospace industry, allowing the evaluation of complexes scenarios with multi-robot integration and its conditions and variables, in order to improve the machining process and its aeronautical structural assemblies. Thus, this research provided a relevant contribution regarding the analysis of main process parameters to obtain an efficient sequence of drilling, its productivity and ergonomic conditions.
Impacts on Head Loss in a Pumpless Solar Thermal Heater Calculated by Hardy-Cross Methodology
Authors: Scerbo Mikelann , D'Orazio Giancarlo , Tyagi Pawan 
Published: February 2021

Abstract
This project explores the impacts that temperature and various geometries have on head loss in a heat exchanger intended to be used as a component of a pumpless solar thermal heater. The heat exchanger component of the pumpless solar thermal heater is a vertical pipe configuration with one inlet pipe through which water flows downward to a well. There are a number of outlet pipes through which water flows upward from the well. The outlet pipes contain a number of conical features at some angle that act as fins to increase heat transfer. The entire heat exchanger is assumed to be submersed in a shell at constant temperature. A Python program was developed using the NTU method to calculate the temperature variation from the inlet to the outlet of the heat exchanger across a varied set of geometry parameters, including: number of outlet pipes, outlet pipe diameter, number of conical features, and angle of conical features. The impact of the temperature variation was accounted for in the head loss calculation within the Python program. For a set of head loss values, an optimized set of geometry parameters was found to maximize the outlet temperature.
Edge Coil Force Fitting and Current Optimal Commutation Algorithm for Magnetic Levitation Planar Motor With Moving Magnet
Authors: Sun Haobo , Zhu Yu , Yang Kaiming , Lu Sen 
Published: February 2021

Abstract
In this paper, edge coils are added to the commutation algorithm of the coil array. In order to reduce the theoretical modeling error of the edge coil force, a method of edge coil force fitting based on radial basis function (RBF) network is proposed. The obtained attenuation function of edge force can replace the weighting function in the switching algorithm, so it can effectively reduce the current density of the central coils and the heat loss power of the coil array. On this basis, a non-iterative current optimal commutation algorithm is proposed. The algorithm takes the weighted sum of the 2-norm of the coil current and the 2-norm of the difference between the coil current and the saturation current as the optimization objective, and obtains the analytical expression of the instantaneous current by solving the Karush Kuhn Tucker (KKT) equation. The results of simulation show that, compared with the direct decoupling algorithm with weighting function, the proposed commutation algorithm can reduce the heat loss power of the coil array and allow the translator to provide greater acceleration under the same maximum current limitation.
3D Modeling of Additive Manufacturing Process: The Case of Polymer Laser Sintering
Authors: Zhang Lan , Boutaous M'hamed , Xin Shihe , Siginer Dennis A. 
Published: February 2021

Abstract
This work focusses on studying multiphysical transient phenomena in polymer powders occurring during selective laser sintering in polymers powders. Multiple phenomena stemming from the interaction of the laser with the polymer powder bed and the transfer of the laser power to the powder bed including laser scattering and absorption, polymer heating, melting, coalescence, densification, and the variation of the material parameters with the temperature are simulated via the modified Monte Carlo-ray tracing method coupled with the Mie theory. A finite volume method is adopted for the heat transfer. The model couples heat diffusion, melting, coalescence and densification of the polymer grains, and the crystallization kinetics during the cooling steps. Laser intensity is concentrated on the surface of the material contrary to the predictions of the Beer-Lambert law. Laser acting on thermoplastic material cause the polymer powder melt, coalescence between melted grains, air diffusion versus densification, crystallization and volume shrinkage. All these processes are simulated by a series of multiphysical models. The reliability of the modeling is tested by comparison with experiments in the literature, and a parametric analysis is performed, based on the process characteristics such as laser sweep speed, its intensity and shape, polymeric grain size among others. Several recommendations to optimize the process are proposed.
Inlet Box Structure Optimization of a Large Axial-Flow Fan Using Response Surface Methodology
Authors: Xiong Jin , Zhang Yinkun , Guo Penghua , Li Jingyin 
Published: February 2021

Abstract
Large axial-flow fans are widely used in many fields. The inlet box is an integral part of large axial-flow fans, and a well-designed inlet box could effectively improve fan efficiency. However, the inlet box structure is complicated, and the existing inlet box design method severely depends on the design experience. In this study, we propose a structure optimization design system based on a surrogate model technique for researching the critical structure parameters of the inlet box and accomplishing aerodynamic performance optimization. As for this expensive optimization problem, the design system contains twice optimization procedures by using the Response Surface Methodology (RSM) with the orthogonal design method. The optimization object is an existing large axial-flow fan. The optimization objective is the total pressure efficiency of the fan, and the total pressure rise is the restriction condition. We generate eighteen different inlet boxes connect with the same impeller and outlet pipe by the orthogonal design method and calculated fan aerodynamic performance by CFX software. After the first optimization, we find the key structural parameters by the sensitivity analysis and the reselect variables total of 25 cases are adopted in a further RSM optimal process. The ultimate surrogate model estimates the fan with the optimal inlet box has a better aerodynamic characteristic and a 6.7% total pressure efficiency rise. Finally, we compare the aerodynamic characteristics of the ultimate design fan and the initial fan by CFD simulation. The numerical results show that: the total pressure efficiency is 6.5% higher than that of the initial impeller, and the pressure rise is 3% higher than that of the initial impeller. The result demonstrates that some most critical parameters of the inlet box structure decide the aerodynamic performance, and the inlet box optimization effectively increases the fan efficiency in the meanwhile.
Acoustic Amplification of Flow Ripple and Cavitation Damage in an Aerospace Fuel System Component
Authors: Lee Andrew , Desai Mihir 
Published: February 2021

Abstract
In a recent investigation of external fuel leaks from an aerospace pressure control valve, cavitation damages were discovered in a small deadheaded cavity, which was created by the axial clearance between the mating subcomponents. Experiments using high bandwidth pressure sensors showed that there were severe pressure fluctuations in the cavity and that the pressure repeatedly fell below the local vapor pressure of the fuel, which would cause cavitation. Spectral analyses showed resonance-like amplification of flow ripple in the valve surrounding inside the valve cavity. The apparent resonance frequency matched the computed fundamental Helmholtz resonance frequency of the cavity. These findings led to a venting solution of the deadheaded cavity by placing an appropriately sized through hole. Back-to-back testing with unvented valves showed stark improvements of the vented solution. This paper presents test and analytical data on the formation of a Helmholtz resonator in the small deadhead cavity of a gas turbine fuel delivery system component. This paper also demonstrates the validity of simple engineering formulas widely available in acoustics literature for predicting the Helmholtz resonance frequencies as a function of neck geometry, neck arrangement, and fuel properties.
Design of a Cognitive Rehabilitation System Based on Gesture Recognition
Authors: Teng Zhiqiang , Chen Haodong , Hou Qitao , Song Wanbing , Gu Chenchen , Zhao Ping 
Published: February 2021

Abstract
Computer-assisted cognitive training is an effective intervention for patients with mild cognitive impairment (MCI), which can avoid the disadvantages of traditional cognitive training that consumes a lot of medical resources and is difficult to be standardized. However, many computer-assisted cognitive training systems have unfriendly human-computer interaction, for not considering that most MCI patients have certain difficulties in using computers. In this paper, we design a cognitive training system which allows patients to implement human-computer interaction through gestures. First, a gesture recognition algorithm is proposed, in which we implement gesture segmentation based on YCbCr color space and Otsu algorithm, extract Fourier Descriptors of gesture contour as feature vectors and use SVM algorithm to train a classifier to recognize gestures. Then, the graphical user interface (GUI) of the system is designed to realize the task requirement of cognitive training for the MCI patients. Finally, the results of tests show the accuracy of the algorithm and the feasibility of the GUI. With the above computer-assisted cognitive training system, patients can achieve human-computer interaction only through gestures without the need to use keyboard, mouse, etc., greatly reducing the burden of patients during training.
Development of a Strain-Controlled Graphene-Based Highly Sensitive Gas Sensor
Authors: Qiao Xiangyu , Zhang Qinqiang , Suzuki Ken 
Published: February 2021

Abstract
Small-size wearable multi-gas sensor with high selectivity and sensitivity is demanded for detecting various harmful gases with high sensitivity in chemical plants, various mines, volcanos, oil and gas fields. Graphene is considered to be the most promising gas-sensitive material due to its large specific surface area and high electron mobility. Many studies have shown that it has a high sensitivity to many gases such as NH3, CO, NO2, H2O, and so on. However, the lack of gas selectivity limits the further application of graphene to gas sensing field. In this study, a first-principle calculation was used to investigate the effect of strain on the gas adsorption behavior of graphene. As a result, it was found that the adsorption behavior of H2O and CO molecules was changed by strain. The adsorption energy of both gases increased monotonically with strain. For carbon monoxide molecules, desorption occurred when the applied tensile strain reached about 5%. These analytical results clearly indicated that there is a possibility of the high selectivity of plural gases by applying appropriate critical strain at which its adsorption changes to desorption. To verify this result, the strain-controlled sensor using graphene was developed. The sensor is composed of graphene and electrodes mounted on a deformable substrate. The high-quality graphene is synthesized on copper by LPCVD (low pressure chemical vapor deposition), and then transferred to the PDMS (Polydimethylsiloxane) substrate using PMMA (Poly methyl methacrylate) as a support layer. It was found that the graphene was monolayer and successfully transferred to the target substrate. The effect of strain on the adsorption of some gases was validated by measuring the change of the resistivity of graphene under the application of uniaxial strain.
Complex Fastener Model for Simulation of Airframe Assembly Process
Authors: Lupuleac Sergey , Smirnov Aleksandr , Shinder Julia , Petukhova Margarita , Churilova Maria , Victorov Evgeniy , Bouriquet Jacques 
Published: February 2021

Abstract
The complex model of fastener for the global modeling of aircraft assembly with regard to compliance and contact interaction of parts is introduced in the paper. The presented complex fastener model incorporates such effects as the stiffness of fastening elements; the loosening of fasteners and also the failure of fasteners (if the load exceeds the maximal value that fastener can hold).
This model can be implemented for all types of fastening elements in variation simulation and assembly optimization analysis. It provides more realistic simulation results at expense of higher model dimension. The fastener is modeled as having an additional stretching stiffness. The option of fastener loosening is included by implementation of additional contact node in each fastening element. This option allows taking into account the pre-tension in fasteners and also enables the modeling of installation and removal of fasteners without change of stiffness matrix.
Numerical Study on Antibacterial Effects of Bio-Inspired Nanostructured Surface
Authors: Zheng Zhouyuan , Bansal Parth , Li Yumeng 
Published: February 2021

Abstract
Natural bactericidal surfaces are found on the wings of cicada and dragonfly that compose of nanopatterns such as nanopillar arrays. Experimental studies have unveiled that the nanopillars can penetrate the bacterial walls or stretch them, resulting in the cell death. This offers an attractive “chemical-free” and wide-spectrum strategy to fight against bacteria-related infections and fouling, especially for implant-associated infections (IAIs). However, what is the fundamental mechanism and key factors governing the bactericidal performance of the nanostructured surface is the critical research questions need to be answered to realize its full potential. In this work, we developed mechanical single cell model of bacteria based on finite element analysis (FEA) to simulate the interactions between different strains of bacteria and the nanostructured surface. The nanostructured surface contains nanopillar arrays, which are made of polymer materials. Different strains of bacteria are simulated by adopting the corresponding geometry and material properties from experimental values. The mechanical responses of the bacteria cell on the nanopillar arrays with various configurations are studied based on estimated stress and strain distributions within the cell.
Corrosion Modeling and Prognosis of the Al-Fe Self-Pierce Riveting Joints
Authors: Zheng Zhouyuan , Bansal Parth , Wang Pingfeng , Shao Chenhui , Li Yumeng 
Published: February 2021

Abstract
Self-pierce riveting (SPR) is one of the commonly used joining technologies, which is useful to assemble dissimilar materials. However, the galvanic / crevice corrosion between joining metals and metal-rivet interfaces plays an important role on the mechanical properties of the joint. It is critical to have a compressive understanding on the corrosion phenomena of the joint. In this study, a hybrid model that combines the stochastic corrosion nucleation method and physics-based finite element (FE) modeling is proposed. The corrosion nucleation variables, including the positions of the nucleation sites and their corrosion trigger time, are firstly obtained based upon statistical analysis on experiments and then imported in the physics-based FE model as initial conditions. Afterwards, the corrosion propagation process is evaluated via the FE model. Various corrosion scenarios with different nucleation variables are generated and statistically analyzed. Experimental results are used to validate the model. It is found that, the proposed hybrid model can reasonably predict the localized corrosion results of the SPR joints, compared to experimental observations. Moreover, the corrosion area and material loss in the SPR joint are predicted.
Particle Immobilization Stiffness in Dielectrophoresis Trap Depending on the Geometry
Authors: Rahman Mohammad Rizwen Ur , Kwak Tae Joon , Woehl Jörg C. , Chang Woo-Jin 
Published: February 2021

Abstract
In dielectrophoresis, a neutral particle experiences a partial charge separation, i.e. induced net dipole moment, when exposed to a non-uniform electric field, and this leads translational movement of the particle. This induced attractive or repulsive motion of the particle suspended in a fluid is known as dielectrophoresis (DEP). In this paper, we have characterized the strength of DEP traps depending on geometry. Three different micro-trap geometries, i.e. triangle, square and circle, were tested to characterize the effect of trap shape on trap stiffness experimentally and numerically using single particle immobilized in the trap. The maximum DEP force generated in triangular μ-trap was found largest among tested geometries. The maximum DEP force of square and circular trap was found around 68.4% and 79.1% of triangular μ-trap, respectively. The trajectory analysis using trapped single particle revealed that the stiffness of circular μ-trap is 1.23 and 1.34 times stronger than the triangular and square μ-trap, respectively. These results will provide useful information in DEP trap geometry designing to enhance trapping efficiency.
Analysis of Injury Mechanisms Within Lead-Vehicle Stopped Impacts: Implications for Autonomous Vehicle Behavior Design
Authors: Eichaker Lauren , Ramachandra Rakshit , Bolte John 
Published: February 2021

Abstract
Lead vehicle stopped crashes are a top contributor to traffic and health care expenditures out of NHTSA’s 37 pre-crash scenarios. It is important to better understand how these crashes occur, so that evolving autonomous vehicle technologies may be tailored towards injury mitigation in crash-imminent scenarios. Additionally, as autonomous vehicle technologies increase in prevalence and usage, out of position seating and distracted driving behavior may also increase. In order to analyze injury patterns in real-world lead vehicle stopped crashes, the public portal of Crash Injury Research Engineering Network (CIREN) was surveyed for lead vehicle stopped impacts. The review found that, of all the body regions, the thorax and lower extremity body regions frequently sustained AIS 3+ injuries (P &lt; 0.01). Additionally, the upper extremity frequently sustained AID 3+ injuries in some scenarios. Steering wheel contact (often times through a deployed air bag) was the source of 62% of the thorax injuries and the knee bolster was the source of 76% of the lower extremity injuries. Truck impacts, and complicated crashes accounted for over 50% of the cases in the cohort. Automated vehicle behaviors have the potential to augment passive and active safety systems to potentially decrease the occurrence of AIS 3+ injuries by improving a vehicle’s response to lead vehicle stopped, crash imminent scenarios.
A Flexible Hair-Like Laser Induced Graphitic Sensor for Low Flow Rate Sensing Applications
Authors: Abbasnejad Behrokh , McGloin David , Clemon Lee 
Published: February 2021

Abstract
Direct low flow sensing is of interest to many applications in medical and biochemical industries. Low flow rate measurement is still challenging, and conventional flow sensors such as hot films, hot wires and Pitot probes are not capable of measuring very low flow rates accurately. In some applications that require flow measurement in a small diameter tubing (e.g. intravenous (IV) infusion), using such sensors also becomes mechanically impractical. Herein, a flexible laser-induced graphitic (LIG) piezoresistive flow sensor has been fabricated in a cost-effective single processing step. The capability of the LIG sensor in very low flow rate measurement has been investigated by embedding the sensor within an intravenous (IV) line. The embedded LIG hair-like sensor was tested at ambient temperature within the IV line at flow rates ranging from 0 m/s to 0.3 m/s (IV infusion free-flow rate). The LIG hair-like sensor presented in this study detects live flow rates of IV infusions with a threshold detection limit as low as 0.02 m/s. Moreover, the deformation of the LIG hair-like sensor that lead to resistance change in response to various flow rates is simulated using COMSOL Multiphysics.