bluuebunny/crossref_metadata_2025_split huggingface dataset:
Machining Characteristics Estimation in WEDM Process While Machining Titanium Grade-2 Material Using ANN
Authors: Sudhir Prathik Jain , Holalu Venkatadas Ravindra , Gonchikar Ugrasen 
Published: February 2021

Abstract
Wire Electrical Discharge Machining (WEDM) provides an effective solution for machining hard materials with intricate shapes. WEDM is a specialized thermal machining process is capable to accurately machining parts of hard materials with complex shapes. However, selection of process parameters for obtaining higher machining efficiency or accuracy in wire EDM is still not fully solved, even with the most up-to-date CNC WED machine. The study presents the machining of Titanium grade 2 material using L’16 Orthogonal Array (OA). The process parameters considered for the present work are pulse on time, pulse off time, current, bed speed, voltage and flush rate. Among these process parameters voltage and flush rate were kept constant and the other four parameters were varied for the machining. Molybdenum wire of 0.18mm is used as the electrode material. Titanium is used in engine applications such as rotors, compressor blades, hydraulic system components and nacelles. Its application can also be found in critical jet engine rotating and airframes components in aircraft industries. Firstly optimization of the process parameters was done to know the effect of most influencing parameters on machining characteristics viz., Surface Roughness (SR) and Electrode Wear (EW). Then the simpler functional relationship plots were established between the parameters to know the possible information about the SR and EW. This simpler method of analysis does not provide the information on the status of the material and electrode. Hence more sophisticated method of analysis was used viz., Artificial Neural Network (ANN) for the estimation of the experimental values. SR and EW parameters prediction was carried out successfully for 50%, 60% and 70% of the training set for titanium material using ANN. Among the selected percentage data, at 70% training set showed remarkable similarities with the measured value then at 50% and 60%.
Development and Performance Evaluation of a Dynamic Compressed Air Energy Storage System
Authors: Kabinga R. K. N. , Tartibu L. K. , Okwu M. O. 
Published: February 2021

Abstract
Renewable and clean energy are safe sources for powering the world in the future. The use of fossil fuels in the transportation sector produces 15 to 20 % of greenhouse gas emissions. To solve this problem, renewable energy sources are being considered for use in the domain of transportation, and compressed air energy is one of them. But the efficiency of the compressed air powered systems depends largely on its energy storage density. In this paper, the performance of two distinct compressed air reservoirs for energy storage in small scale systems was investigated. Two air compressors fitted with static reservoirs were utilized for the experiment. The first air compressor was driven by an internal combustion engine (ICE) and the second was driven by an electric motor. The experimental results were used to provide a frame of reference for the computer (MATLAB) simulation on the dynamic reservoir. Additionally, the dynamic reservoir, which is a system fitted with a piston and spring, was analyzed considering three different spring stiffness. This study showed that the dynamic reservoir provides a consistent and better performance during the charging and discharging process, affecting positively the behavior of the pressure and the compressed air mass flowrate.
Molecular Dynamics Analysis of the Acceleration of Intergranular Cracking of Ni-Base Superalloy Caused by Accumulation of Vacancies and Dislocations Around Grain Boundaries
Authors: Kikuchi Ryo , Suzuki Shujiro , Suzuki Ken 
Published: February 2021

Abstract
Ni-based superalloys with excellent high temperature strength have been used in advanced thermal power plants. It was found that grain boundary cracking is caused in the alloy under creep-fatigue loading due to the degradation of the crystallinity of grain boundaries and the grain boundary cracking degrades the lifetime of the alloy drastically. In order to clarify the mechanism of intergranular cracking, in this research, static and dynamic strains were applied to a bicrystal structure of the alloy perpendicularly to the grain boundary using molecular dynamics analysis. In addition, the effect of the accumulation of vacancies in the area with high-density of dislocations on the strength of the bicrystal structure was analysed. It was found that the fracture mode of the bicrystal structure changed from ductile transgranular fracture to brittle intergranular one as strong functions of the combination of Schmid factor of the two grains and the density of defects around the grain boundary. The local heavy plastic deformation occurred around the grain boundary with large difference in Schmid factor between nearby grains and the diffusion of the newly grown dislocations and vacancies was suppressed by the large strain field due to the large mismatch of the crystallographic orientation between the grains. The accumulation of vacancies accelerated the local plastic deformation around the grain boundary. Therefore, the mechanism of the acceleration of intergranular cracking under creep-fatigue loading was successfully clarified by MD analysis.
Subsonic Stall Flutter of a Linear Turbine Blade Cascade Using Experimental and CFD Analysis
Authors: Slama Vaclav , Rudas Bartolomej , Ira Jiri , Macalka Ales , Eret Petr , Tsymbalyuk Volodymyr 
Published: February 2021

Abstract
Stall flutter of long blades influences the operation safety of the large steam turbines in off-design conditions. As angles of attack are typically high, a partial or complete separation of the flow from the blade surface occurs. The prediction of stall flutter of turbine blades is a crucial task in the design and development of modern turbomachinery units and reliable design tools are necessary. In this work, aerodynamic stability of a linear turbine blade cascade is tested experimentally at high angle of attack +15°, Ma = 0.2 and the reduced frequency of 0.38. Controlled flutter testing has been performed in a travelling wave mode approach for the torsion with the motion amplitude of 0.5°. In addition, ANSYS CFX with SST k-ω turbulent model is used for URANS simulations of a full-scale computational domain. A separation bubble formed on suction surface near the leading edge has been found in CFD results for each blade. Excellent agreement between the experimental and numerical results in stability maps has been achieved for this case under investigation. This is encouraging and both experimental and numerical techniques will be tested further.
Identification of Variation Sources for High Precision Fabrication in a Digital Twin Context
Authors: Hultman Hugo , Cedergren Stefan , Söderberg Rikard , Wärmefjord Kristina 
Published: February 2021

Abstract
The aerospace industry is increasing its focus on fabrication in manufacturing, foregoing large castings to instead assemble and join smaller parts into final products. This increases the total amount of geometrical variation introduced during the production process, since the unique variation from each individual part can add to a propagating effect putting the final assembled product outside of tolerance limits. Geometry assurance and variation simulation has traditionally been applied as a part of the design process to develop robust manufacturing concepts that are as insensitive as possible to variation. A concept for geometry assurance has been proposed where variation simulation is conducted for each individual assembly using real measurements from incoming parts, making it possible to make adaptive adjustments to production parameters to optimize results. It is however not feasible to measure and simulate every aspect of the process. This paper provides a summary of relevant sources of geometrical variation for a high precision fabrication process, based on input from a fabrication process in the aerospace industry. Variation sources are analyzed and discussed from an industrial perspective, putting them in the context of an actual fabrication process as well as in the context of digital twins for geometry assurance.
Walking Speed Estimation From a Wearable Insole Pressure System Using a Bayesian Regularized Back Propagation Neural Network
Authors: Wei Wang , Kaiming Yang , Yu Zhu , Yuyang Qian , Chenhui Wan , Min Li 
Published: February 2021

Abstract
In this study, we introduced a machine learning method for estimating human walking speed using plantar pressure and acceleration data. A pressure-derivative based with pretest feature selection method was proposed to extracted speed-related features from plantar pressure sensors. The maximum, minimum and standard deviation of acceleration data were also selected as neural network inputs. To improve the generalization ability of the neural network, a Bayesian regularization method was adopted. To validate the performance of the proposed method, experiments were conducted under seven different walking speeds. The results show that a strong linear correlation (R = 0.995) exists between the estimated and the actual walking speeds. The average error of the proposed method is 0.003 ± 0.043 m/s (mean ± root mean square error), which is better than previous works. The desirable performance of the proposed method proves that including the speed-related information of both stance and swing phase is beneficial for improving the accuracy of walking speed estimation.
Peristaltic Roller Pump: Parametric Optimization for Hemolysis Control
Authors: Capata Roberto 
Published: February 2021

Abstract
This work aims to analyze the various types of peristaltic pumps by studying, in particular, the use of the peristaltic roller pump to highlight its critical issues and propose new effective and innovative solutions. One possible application of this device is in hemodialysis, which is a physical therapy substitution of kidney function that allows, in almost all cases, recovery and maintenance of the main biological functions while remaining the uremic condition. As for the extracorporeal one, the equipment used to purify the blood from toxic substances that are no longer normally eliminated by kidney filtration is divided mainly into two types: rotary peristaltic pump and a linear peristaltic pump. Having to work with a very particular fluid such as blood and in direct contact with the patient, they need to be extremely accurate and must ensure a constant and continuous functioning. The rotary peristaltic pump is the most widely used for hemodialysis and having been extensively studied in literature it has since found extensive solutions in the application field. As is well known, peristaltic pump refers to a device that exploits the principle of peristalsis to function, i.e. the transit of a bottleneck on a tube, in this case, the catheter, to push the fluid contained outwards. In particular, a roundabout peristaltic pump consists of a rotating structure consisting of two or more rollers that in turn revolve around their axis. With their displacement, the rollers clog adjacent catheter sections at a time so that after the first roller has passed the tube returns to its initial size creating the vacuum and then sucking the fluid. In this way, the liquid is pushed from the tube towards the patient. The motion of all these components is powered by an electric motor connected directly to the main rotating structure. The pumping of fluids through hoses using the propagation of a peristaltic wave has been the subject of design and scientific studies for more than 4 decades. This is easily justifiable since the phenomenon of peristalsis is known to be an important responsible mechanism of fluid transport in many biological organs. The goal is (starting on studies on the blood, a variable density fluid) to analyze in detail the peristaltic roller pump and propose its parametric optimization, aimed at determining the critical speed, beyond which the machine damages any kind of fluid that needs special treatment (blood, food, special gel, medical ointments and so on).
Powdered Metal Heat Treatment Apparatus Designed for a Laboratory
Authors: Porter Jacob , Parmigiani John 
Published: February 2021

Abstract
Metal additive manufacturing is a rapidly growing and sophisticated industry however the manufacturing processes and equipment for the heat treatment of the needed powdered metals is underdeveloped. Heat treatment is a key step in the powdered metal production process and is often needed to produce desired material properties. The objective of this paper is to examine the design of a heat treatment machine that addresses the needs of a laboratory performing research on powdered metals. The device was designed to address the three criteria of a heat treatment device; treatment, environment, and containment. The treatment criterion is accomplished by continuous powder flow through a furnace. The environment criterion is accomplished through a gas handling system capable of creating both an argon and vacuum environment. Finally, the containment criterion is accomplished through a network of tubes that provides structure to contain the powder. The design of this machine will allow research and development labs to heat treat powdered to a higher quality at a significantly faster rate.
Francis Turbine Operation at Excess Flow Rate Using Large Eddy Simulation: The Effect of Water Injection
Authors: Altimemy Muhannad , Caspar Justin , Watheq Saif , Oztekin Alparslan 
Published: February 2021

Abstract
High-fidelity Large Eddy Simulations (LES) were conducted to characterize the spatial and temporal structure of turbulent flows in an industrial-sized Francis turbine running at 120% of the design flow rate. Injection at a 4% and 8% flow rate is applied and investigated as a mitigation method for pressure-induced fluctuations along the draft tube. Contours of velocity and vorticity in the draft tube are presented to examine the effects of water injection. Probes placed alongside the draft tube measure the pressure signal and compare both operational regimes to characterize the pressure fluctuations. The intensity of pressure fluctuations along the draft tube wall is an order of magnitude smaller compared to that at the center. As the injection is applied, the intensity of the pressure fluctuations along the draft tube wall is increased while the intensity of pressure fluctuations in the center of the draft tube is reduced. Pressure probes in the center of the draft tube measure an 86% to 57% reduction in amplitude for 4% to 8% flow rate injection, respectively. There is a 30% to 40% increase in fluctuations along the wall for 4% to 8% flow rate injection, respectively. These changes in flow structure are due to the dissipation of the vortex rope as the injection is applied.
Robotic Handling of Jet Engine Turbine Blade Using Collaborative Robot
Authors: Sahay Prateek , Dong Janet , Bisig Caleb , Ma Ou 
Published: February 2021

Abstract
The work discussed in this paper is a part of the project to build an automated robotic cell for removing two tabs from a Jet Engine Turbine Blade using a 3-axis CNC milling machine and for laser marking several lines of part information onto the blade body. The two tabs are extensions of the Turbine Blade, in which the necessary part information is ingrained. The part information is used as the identification of the Turbine Blade throughout its entire manufacturing process. The two tabs also serve as anchors during the milling of the body of the Turbine Blade in a 5-axis CNC machine. Once the milling of the blade body is done, the two tabs will be removed from the blade body. Removing tabs is currently being done in the same 5-axis CNC milling machine. It is expensive and wastes 5-axis machine time. Therefore, using a 3-axis CNC milling machine to remove tabs is proposed with a robot to tend machines to be cost-effective. Due to the complexity of the Turbine Blade having 3-D wavy geometry, it adds challenges in undertaking any operations on the blade with automation.
As automation is becoming relevant in many industries including the Aerospace, the method discussed in this paper can be used as a general guideline for carrying out material handling tasks with a thin part of wavy geometry by using a collaborative robot.
Airfoil Deterministic Lateral Displacement for High-Throughput Particle Separation in Viscous Fluids
Authors: Senf Brian , Ahasan Kawkab , Kim Jong-Hoon 
Published: February 2021

Abstract
Deterministic Lateral Displacement (DLD) is an inertial size-based particle separation technique with great possibilities for use with biological sample preparation. Recently it has been shown that particle shift of a DLD is highly dependent on the Reynolds number. Additionally, particle trajectory has been characterized in a high throughput airfoil array DLD with varying Angle of Attack (AoA) in Deionized water. The AoA can be shifted negatively assisting in particle trajectory increases at low Reynolds numbers. With variations in fluid viscosity, particle trajectories compared to Reynolds value should theoretically have a constant and similar slope. In this work, various viscosities are tested in a DLD with a neutral and negative AoA to eventually characterize non-Newtonian fluids within a DLD. Due to higher viscosities increasing the internal pressure of the device, the negative AoA DLD shows promising results at higher range viscosities due to its ability to shift particles at lower Reynolds numbers.
An Approach to Bayesian Optimization in Optimizing Weighted Tchebycheff Multi-Objective Black-Box Functions
Authors: Biswas Arpan , Fuentes Claudio , Hoyle Christopher 
Published: February 2021

Abstract
Bayesian optimization (BO) is a low-cost global optimization tool for expensive black-box objective functions, where we learn from prior evaluated designs, update a posterior surrogate Gaussian process model, and select new designs for future evaluation using an acquisition function. This research focuses upon developing a BO model with multiple black-box objective functions. In the standard multi-objective optimization problem, the weighted Tchebycheff method is efficiently used to find both convex and non-convex Pareto frontier. This approach requires knowledge of utopia values before we start optimization. However, in the BO framework, since the functions are expensive to evaluate, it is very expensive to obtain the utopia values as a priori knowledge. Therefore, in this paper, we develop a Multi-Objective Bayesian Optimization (MO-BO) framework where we calibrate with Multiple Linear Regression (MLR) models to estimate the utopia value for each objective as a function of design input variables; the models are updated iteratively with sampled training data from the proposed multi-objective BO. The iteratively estimated mean utopia values are used to formulate the weighted Tchebycheff multi-objective acquisition function. The proposed approach is implemented in optimizing a thin tube design under constant loading of temperature and pressure, with multiple objectives such as minimizing the risk of creep-fatigue failure and design cost along with risk-based and manufacturing constraints. Finally, the model accuracy with and without MLR-based calibration is compared to the true Pareto solutions. The results show potential broader impacts, future research directions for further improving the proposed MO-BO model, and potential extensions to the application of large-scale design problems.
Estimation of Endpoint Impedance of a 2D Parallel Manipulator Using Numerical Simulation Experiments
Authors: Regmi Sambad , Song Yun Seong 
Published: February 2021

Abstract
While endpoint impedance of manipulators can be modulated through feedback control, it may not be feasible to reduce it below a certain bound that is dictated by the inherent mechanical characteristics of the robot. In applications where the endpoint impedance of a robot arm needs to be modulated within a large range, it is beneficial to have a method that can estimate the passive characteristics (endpoint inertia and endpoint damping) of the robot arm as early as in the design phase, and use this information to modify the design, if necessary, before building the prototype. In our previous work, we developed a numerical simulation method to estimate 1-D endpoint impedance that is applicable only to limited scenarios. In this article, we present a new numerical simulation method to estimate the 2-D endpoint impedance for any general 2-D manipulators at various locations inside the workspace. We show that our method accurately estimates the endpoint inertia and presents feasible estimates of endpoint damping through numerical simulations. An analysis of the feasibility of using the robot for interaction tasks — based on the obtained impedance characteristics — is also discussed. With our method, robot output impedance can be tailored as early as in the design phase.
Numerical Analysis of Load Transfer Mechanism in Fiber-Reinforced Composites Enhanced by Zinc Oxide Nanowires
Authors: Marashizadeh Parisa , Abshirini Mohammad , Saha Mrinal , Liu Yingtao 
Published: February 2021

Abstract
In this study, a three-dimensional model of single carbon-fiber composites enhanced by radially grown zinc oxide (ZnO) nanowires is investigated numerically. Due to the different length scales of the composites and the theories used in the system, a multi-scale analysis is employed to simulate the behavior of the fiber-reinforced composites. The effective mechanical properties of the enhancement layer are extracted at the micro-scale by the homogenization analysis of an appropriate representative volume element. The fiber interface is modeled at the meso-scale utilizing the cohesive zone method. A thin layer of interface with the cohesive element is modeled around the fiber. The material properties of the interface are evaluated based on the properties of fiber and the enhancement layer. The macro-scale damage behavior of fiber is defined by user-defined mechanical material behavior. Single fiber fragmentation test is simulated in ABAQUS by applying the tensile loads on the structure. The load transfer mechanism is evaluated by capturing the number of fiber fragmentation and calculating the interfacial shear strength. The effect of different ZnO diameters and volume fractions are also investigated. The results show stronger interface and higher load transfer capacity in the enhanced composite compared to the bare composite.
On the Use of the Accident Dynamic Simulator Method in Ship Collision Accident Analysis
Authors: Shi Shuquan , Wang Tengfei , Diaconeasa Mihai 
Published: February 2021

Abstract
This paper proposes a maritime Accident Dynamic Simulator (MADS) method from one ship’s perspective of ship collision accident. The MADS model is built based on discrete dynamic event trees (D-DET) to generate the time-dependent ship collision accident scenarios. According to the characteristics of maritime activities, such as high freedom of participation, the big influence of the environment, and the high uncertainty, the MADS method is modified, and the analyzed ship collision scenario is reasonably simplified. Both crews’ decision-making process and ship manoeuvre are fully discretized to generate new branches of the D-DET. The interactions between encountered ships are modelled with an information transfer model to form the uncertainties between two ships. The MADS consists of physical simulation engine, crew response and interaction model, reliability model of the system hardware, functional model of human-system interfaces and event sequence controlling model. The MADS starts with a pre-set initiating event under a specific situation. Event branches are discretely generated based on probable alternative state changes of operator response or system evolution. The output probability of an end state can be calculated in the same way with the conventional event tree after the whole scenario completed. At the end of the paper, an accident case study is used to verify the efficiency of the ADS.