bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating the Micro-EDM Machinability of Bulk Metallic Glass in Micro-EDM Drilling
Authors: Liu Chong , Rashid Asif , Jahan Muhammad P. , Ma Jianfeng 
Published: January 2020

Abstract
Bulk Metallic Glass (BMG) is a solid metallic material with disordered atomic structure, that has the characteristics of high elasticity, hardness, fracture toughness, and superior corrosion resistance. High aspect ratio micro-through holes on BMG has prospective applications in space, nuclear reactor, thermodynamics engineering, biomedical, and electronics industries. In this study, the micro-EDM machinability of BMG (Vit 1b: Zr67Cu10.6Ni9.8Ti8.8Be3.8 (wt%)) is evaluated. The micro-EDM machinability of BMG has been assessed based on the volume of material removal rate (MRR), tool wear rate (TWR), micro-hole surface quality, and dimensional accuracy. The effect of various electrical and non-electrical parameters is studied. It is found that micro-EDM is capable producing high aspect ratio micro-holes on difficult-to-machine BMG. The deposition of resolidified debris around the edge of the micro-holes, both at the entrance and exit side, are found to be a common phenomenon in micro-EDM of BMG. The reduction of capacitance was found to be the effective way for reducing the resolidified debris around the edges. Capacitance was found to be have more pronounced effect, with gap voltage having little effect on the quality of micro-holes. The electrode rotational speed had insignificant effect on the quality of micro-holes. In terms of dimensional accuracy, which was measured by overcut and taper angle, both the gap voltage and electrode rotational speed had little effect. The lower electrode rpm was found to reduce the taperness of the micro-holes, although the material removal rate decreases and tool wear rate increases. Finally, analysis of the composition of tool electrode before and after machining indicates the migration of materials from the dielectric and workpiece to the tool electrode and vice versa.
Irregular Shape Optimization for the Film Cooling Nozzle of Gas Turbines Using Numerical Optimization Tool
Authors: Alshehaby Mohammad M. , El-Gabry Lamyaa 
Published: January 2020

Abstract
Film cooling, along with other approaches, is well known to be an important technique for preserving the integrity of turbine blades against high temperature gases. Accordingly, continuous enhancement of film cooling performance is still one of the gas turbines community’s interests. The coolant nozzle geometry, as an important parameter controlling the film cooling behavior, has been yielded to close test in the current study seeking for the optimum one that gives best cooling performance in terms of adiabatic film effectiveness and heat transfer coefficient at blowing ratio of one. An experimentally validated model, realizable k-ε model with scalable wall function, has been utilized through the current numerical study. The racetrack slot (rectangular slot with fully round ends) was proven to outperform the typical round hole in terms of the cooling effect. The racetrack aspect ratio of seven has been designated by previous study to give the best cooling performance. Therefore, it served as a starting point for further optimization of the coolant pipe shape utilizing ANSYS Fluent Adjoint solver. The advantage of the numerical optimization tool is that it allows for irregular shape optimization. The concern that used to face irregular geometry designs is the lack of manufacturability. Nevertheless, the recent advancement in manufacturing processes, especially with the wide range and spread of additive manufacturing technique, paved the way for more powerful shape design through less constrained optimization process. Starting from the optimum racetrack geometry, the optimum irregular pipe shape was designated in two optimization steps, through which the average adiabatic film effectiveness over the test surface has increased from 0.24 to 0.34, recording a remarkable improvement.
An Initial Study Towards In-Situ Ultrasonic Monitoring and Measurement of Part Properties During Photopolymer Based Additive Manufacturing
Authors: Su Tong , Jiang Menghan , Wang Qing-Ming , Zhao Xiayun 
Published: January 2020

Abstract
This paper presents our recent preliminary study on using a novel in-house ultrasonic measurement technique to investigate ex situ the elastic modulus evolution during a photopolymer based additive manufacturing (PAM). Experiment is designed to study the effects of PAM process parameters on the elastic modulus of fabricated samples. A unique lab-built line-focused ultrasonic transducer based on time-resolved defocusing is employed to measure velocities of the surface waves (Rayleigh waves and longitudinal bulk waves) leaking from the samples. The samples’ elastic properties can be calculated from the obtained wave velocities. As a result, changes in elastic modulus with the varying PAM process conditions are successfully detected and quantified by this ex situ ultrasonic technique, revealing important information on both the “need-to” and “how-to” develop an in-situ monitoring and measurement system for part properties during PAM processes. The research outcome will not only enhance understanding about evolution of mechanical properties during PAM, but also offer insightful guidance on a future development based on the reported ex-situ ultrasonic technology towards an in-situ ultrasonic system for in-process measurement and advanced control of PAM.
On the Role of Segmentation in the Analysis of Micro-CT Data of Impact Damage in the CFRP Composites
Authors: Zhupanska Olesya I. 
Published: January 2020

Abstract
In this paper we discuss the role of different image segmentation methods that are used for the analysis of the micro computed tomography (micro-CT) data of damage in the carbon fiber reinforced polymer (CFRP) composites due to low velocity impact. Segmentation is one of the most critical steps in the image processing of the three dimensional (3D) CT data and accurate assessment of the damage from CT data depends to a great extent on the image segmentation. We have extensively studied low velocity impact damage in the CFRP composites using 3D CT. CFRP textile composite laminates were impacted using an Instron 8200 Dynatup drop-weight impact machine. ZEISS METROTOM 1500 CT scanner was used to evaluate internal impact damage. VGStudio MAX was used for reconstruction of CT images. Different segmentation procedures were used during image processing of the CT images. Differences in the estimates of the damage zone obtained using different segmentation techniques have been assessed.
Investigations of Three-Dimensional Flow Field Development in an Axial Compressor Cascade
Authors: El-Shahat Saeed A. , El-Batsh Hesham M. , Attia Ali M. A. , Li Guojun , Fu Lei 
Published: January 2020

Abstract
This paper presents a complete study about three-dimensional (3-D) flow field development in a linear compressor cascade where flow field in the blade passage has been studied experimentally as well as numerically.
In the experimental work, a linear compressor cascade test section was installed in an open loop wind tunnel. The experimental data was acquired for a Reynolds number of 2.98 × 105 based on the blade chord and the inlet flow conditions. The flow field characteristics in blade passage including 3-D flow velocity and velocity magnitude have been measured by using calibrated five and seven-hole pressure probes connected to ATX sensor module data acquisition system (DAQ). To investigate flow development in the blade passage, velocity coefficient through streamwise planes has been calculated from the measured data. The computational fluid dynamics (CFD) study of the flow field was performed to gain a better understanding of the flow features. Present computational study was first validated with previous experimental and numerical work to check mesh accuracy and give confidence for computational results. Then, two turbulence models, Spalart-Allmaras (S-A) and shear stress transport SST (k-ω) were used for the present work. From both parts of study, the flow field development through the cascade have been investigated and compared. Moreover, the received data demonstrated a good agreement between the experimental and computational results. The predicted flow streamlines by numerical calculations showed regions characterized by flow separation and recirculation zones such as corner separation that could be used to enhance the understanding of the loss mechanism in compressor cascades. All measurements taken by the two probes, 5 and 7-hole pressure probes, have been analyzed and compared. The 5-hole pressure probe measurements have showed more agreements with computational results than 7-hole probe. Furthermore S-A turbulence model calculations showed more consistencies with experimental results than SST (k-ω) model.
A Clinical Test to Capture Humidity From Exhalation: Self-Humidification
Authors: Grau-Bartual Sandra , Al-Jumaily Ahmed M. 
Published: January 2020

Abstract
Lung supportive devices are widely used for non-invasive positive airway pressure ventilation and respiratory therapy to help provide breathing support for patients with various lung diseases including Obstructive Sleep Apnea. These devices deliver air to the patient through a facial or nasal mask, and the use of these devices normally results in dryness in the upper airways. However, the exhaled air consists of very high humidity content hence the moisture content of this air can be reused in the inhalation process. This research focuses on testing clinically a previously developed element which can recover the moisture from the exhaled air and use it for re-inhalation. 21 healthy volunteers between the ages of 21 and 55, where 38.1% were females and 61.9% males, were invited to participate in this study. The results show a viable element which is able to trap water molecules from the expiration airflow and release them into the inspiration airflow.
Topology Optimization of Plastic Parts for Injection Molding
Authors: Oliver Kathryn , Anwar Sohel , Tovar Andres 
Published: January 2020

Abstract
Topology optimization is broadly recognized as a design approach to generate high-performance conceptual designs suitable for freeform fabrication, e.g., additive manufacturing. When other fabrication methods are considered, topology optimization must integrate manufacturing constraints. The integration of constraints for extrusion and casting has been addressed in the past by a few researcher groups. In this work, extrusion and casting constraints are revisited and extended to include plastic injection. The proposed method relies on the use of intersection planes and the definition of a parting line within the planes. The resulting topologies can be injected in a two-plate mold without the use of inserts. The implementation and results of the proposed approach are demonstrated in classic three-dimensional problems that include a cantilevered beam with different load conditions.
Large Deformation Behavior of Porous Polymer Materials With 3D Random Pore Structure: Experimental Investigation and FEM Modeling
Authors: Emori Kanako , Miura Tatsuma , Yonezu Akio 
Published: January 2020

Abstract
This study investigates the deformation behavior of porous polymer materials with 3D random pore structure. The test sample has sub-micron-sized pores with an open cellular structure, which plays a critical role for water purification. The base polymer is PVDF (polyvinylidene difluoride). First, the surface and cross section of the sample are observed using FESEM to investigate the microstructure (cell size and geometry of the cell ligament, etc). Next, uni-axial tensile loading is carried out for polymeric membrane and it is found that the membranes underwent elasto-plastic deformation. In order to establish a numerical model, finite element metod (FEM) is employed. Using a software of Surface Evolver, 3D random pore structure is created in the representative volume element (RVE). The established computational model can predict both elastic deformation and plastic deformation. Furthermore, viscoplastic deformation behavior (i.e. time-dependent deformation and creep deformation) is investigated, experimentally and numerically. In particular, creep compliance is measured, and we investigate the effect of applied loading on creep deformation behavior. Using the time–temperature–stress superposition principle (TTSSP), we obtain a new master curve, which covers higher stress level, and successfully establish an FEM model of creep deformation of the test sample. The present model enables the prediction of the macroscopic and microscopic deformation behavior of the porous materials, by taking into account of 3D random pore structure.
Electrostatically Actuated MEMS Circular Plate Resonators: Frequency Response of Superharmonic Resonance of Third Order
Authors: Beatriz Julio , Caruntu Dumitru I. 
Published: January 2020

Abstract
This paper deals with the frequency response of superharmonic resonance of order three of electrostatically actuated MicroElectroMechanical Systems (MEMS) circular plate resonators. The MEMS structure in this work consists of an elastic circular microplate parallel to an electrode ground plate. The microplate is elelctrostatically actuated through an AC voltage between the microplate and the ground plate. The voltage is in the category of hard excitations. The AC frequency is near one sixth of the natural frequency of the resonator. Since the electrostatic force acting on the resonator is proportional to the square of the voltage, it leads to superharmonic resonance of third order. Besides the electrostatic force, the system experiences damping. The damping force in this work is proportional to the velocity of the resonator, i.e. it is linear damping. Three methods are employed in this investigation. First, the Method of Multiple Scales (MMS), a perturbation method, is used predictions of the resonant regions for weak nonlinearities and small to moderate amplitudes. Second, the Reduced Order Model (ROM) method using two modes of vibration are also utilized to investigate the resonance. ROM is solved numerically integrated using Matlab in order to simulate time responses of the structure, and third, the ROM is used to predict the frequency response using AUTO, a software for continuation and bifurcation analysis. All methods are in agreement for moderate nonlinearities and small to moderate amplitudes. For relatively large amplitudes, when compared to the gap between the microplate and the ground plate, ROM more accurately predicts the behavior of the system. Effects of the parameters of the system on the frequency response are reported.
Physical Thorax Model and 2D Grid of Force Sensors to Monitor Respiration
Authors: Dean Matthew R. , Martins Noah J. , Brown Joseph D. , McCusker James , Ma Guohua , Dow Douglas E. 
Published: January 2020

Abstract
Sleep disorders impair the quality of life for many individuals, but often go undiagnosed and untreated due to the cost and sleep-disturbing aggravation of polysomnography, the clinical sleep test. Simpler sleep monitoring systems that could be used at home may provide useful health information. A 2D grid of force sensors within a mat beneath the thorax of a sleeping subject has been reported to enable monitoring of respiration during sleep. A physical model of a thorax over such a 2D grid of force sensors may enable more tests and perturbations of parameters than could be done using only human subjects. The purpose of this project was to develop and test a physical model of a thorax undergoing volume changes, and measuring the changes in force by a grid of force sensors under the model. A prototype system was developed. Early testing shows promise for being able to monitor the changes in force as volume of the model changes. More development and testing are required toward development of improved algorithms and systems for sleep monitoring mats.
Analysis and Design of Twin Gyroscopes for Ocean-Wave Energy Converters and Ship Roll-Stabilizers
Authors: Murakami Hidenori , Ono Takeyuki 
Published: January 2020

Abstract
Twin-gyroscopic systems are designed for ocean-wave energy converters and ship roll-stabilizers to double desirable gyroscopic effects and eliminate undesirable reaction torques. In deriving analytical equations of motion, the configuration spaces of gyroscopic systems are defined by using body-attached moving frames. The moving frame of each constituent body is defined by its inertial coordinates of the center of mass and a rotation matrix which expresses the attitude of its coordinate axes from the inertial coordinate axes. Therefore, to utilize powerful Lagrange’s method, it is extended to accommodate rotation matrices in configuration spaces and allow angular velocities as generalized velocities.
First, in the paper, to identify undesirable reaction torques of gyroscopic systems and find a scheme to eliminate them, we present the basics of a reaction wheel. Second, to identify the desirable gyroscopic effect, we consider a control moment gyroscope and derive the equations of motion using the extended Lagrange’s method. In addition, the equations of motion are also derived by using the Newton-Euler method, where action and reaction torques are explicitly expressed. The comparison of the resulting equations derived by the two methods reveals the simplicity of Lagrange’s method in treating actuating motor torques and how the effects of reaction torques are implicitly included in the variationally derived equations. Finally, the equations of motion for a twin-gyroscopic system are obtained by incorporating the scheme to eliminate the undesirable reaction torques.
Survey of Computational Fluid Dynamics Software for Rotational Purposes
Authors: Bell Savannah B. , Blair Andrew C. , Wagner Lauren N. , Zou Vincent , Buendia Ali R. , Ashrafzadeh Farhad 
Published: January 2020

Abstract
Computational fluid dynamics (CFD) software has become an essential modeling tool to study and validate flow problems in engineered systems. Many computer-aided engineering (CAE) programs for CFD are available with different capabilities, making it difficult to select the best program for a specific application. This problem compounds in fields with static and rotational regions due to varying approaches for developing the computational mesh and performing flow rotation operations.
Three different CFD programs were reviewed and evaluated by analyzing a real-world problem: flow field analysis and power requirements of a spinning lawnmower blade. Simulations with SolidWorks, SimScale, and ANSYS Fluent were performed to study viscous and pressure forces on a lawnmower blade and compare quantitative and qualitative aspects of each software. The programs’ features, drawbacks, usability, and outputs were recorded and compared. Accuracy of the programs’ output torque was compared using torque data based on the differential power consumption of the electric lawn mower motor unloaded and loaded with the blade. The verification of methodology and results was approached with an analytical model based on drag relations around simplified geometry. Based on these analyses, Fluent provided more consistent solution accuracy with low computational costs and more versatile visualization capabilities.
Experimental Investigation of a Membrane Distillation System Using Solar Evacuated Tubes
Authors: Bamasag Ahmad , Alqahtani Talal , Sinha Shahnawaz , Phelan Patrick 
Published: January 2020

Abstract
Membrane distillation (MD) has been studied as a promising solution in the desalination industry but it has not been widely accepted or commercialized due to energy and cost concerns. MD is considered as a hybrid method that involves phase-change thermal processes and the use of membrane separation. Unlike conventional pressure-driven membrane methods such as reverse osmosis (RO), MD does not require intensive pre-treatment and can operate at lower pressure with higher salinities; but more importantly, it can utilize low-grade heat sources such as solar energy or waste heat for its operation. In this paper, an innovative MD module to directly employ solar thermal energy to assist in desalination is studied. MD systems that use solar energy as an external heater is investigated experimentally and theoretically. The proposed system, however, integrates hollow-fiber distillation membranes inside evacuated tubes solar collectors. As a result, the temperature is more uniformly distributed, minimizing the effect of temperature polarization, one of the key challenges of MD operation, thus can enhance the MD performance. The technical performance of the system is measured experimentally. The results of the proposed system are compared with a conventional MD process to investigate improvements in water production.
Neural Network Based Fault Tolerant Control for a Semi-Active Suspension
Authors: Rueda Villanoba Sergio Alberto , Borrás Pinilla Carlos 
Published: January 2020

Abstract
In this study a Neural Network based fault tolerant control is proposed to accommodate oil leakages in a magnetorheological suspension system based in a half car dynamic model. This model consists of vehicle body (spring mass) connected by the MR suspension system to two lateral wheels (unsprung mass). The semi-active suspension system is a four states nonlinear model; it can be written as a state space representation.
The main objectives of a suspension are: Isolate the chassis from road disturbances (passenger comfort) and maintain contact between tire and road to provide better maneuverability, safety and performance. On the other hand, component faults/failures are inevitable in all practical systems, the shock absorbers of semi-active suspensions are prone to fail due to fluid leakage but quickly detect and diagnose this fault in the system, avoid major damage to the system and ensure the safety of the driver.
To successfully achieve desirable control performance, it is necessary to have a damping force model which can accurately represent the highly nonlinear and hysteretic dynamic of the MR damper. To simulate parameters of the damper, a quasi-static model was applied, quasi-static approaches are based on non-newtonian yield stress fluids flow by using the Bingham MR Damper Model, relating the relative displacement of the piston, the frictional force, a damping constant, the stiffness of the elastic element of the damper and an offset force.
The Fault detection and isolation module is based on residual generation algorithms. The residua r is computed as the difference between the displacement signal of functional and faulty model, when the residual is close to zero, the process is free of faults, while any change in r represents a faulty scheme then a wavelet transform, (Morlet wave function) is used to determine the natural frequencies and amplitudes of displacement and acceleration signal during the failure, this module provides parameters to the neural network controller in order to accommodate the failure using compensation forces from the remaining healthy damper. The neural network uses the error between the plant output and the neural network plant for computing the required electric current to correct the malfunction using the inverse dynamics function of the MR damper model.
Consequently, a bump condition, and a random profile road (ISO 8608) described by the power spectral density (PSD) of its vertical displacement, is used as disturbance of control system. The performance of the proposed FTC structure is demonstrated trough simulation. Results shows that the control system could reduce the effect of the partial fault of the MR Damper on system performance.