bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computational Design Optimization of PCM-Based Attenuator of Fluid Temperature Fluctuations
Authors: Klimeš L. , Kozubík L. , Charvát P. 
Published: January 2020

Abstract
A fluid-PCM heat exchanger (attenuator) of a circular design with water as the fluid was investigated both numerically and experimentally. A computational model of the PCM-based attenuator was developed with the use of the control volume method and the effective heat capacity. Square wave fluctuations of the water temperature at the inlet of the attenuator were considered in the study. The model and its functionality was validated by means of experimental data. The experimental investigation was carried out in a lab environment and two tanks containing water of different temperatures with the computer-controlled mixing valve were used to simulate square wave temperature fluctuations. The validated model was then coupled with metaheuristic optimization methods. The bee algorithm, the genetic algorithm, and the particle swarm optimization algorithm were applied in the study. Design optimization of the attenuator was performed with the aim to maximize the attenuation capability of the attenuator, but considering a cost factor as well. Results indicated that the metaheuristic approach represents a viable way for the solution of this kind of problems. All three metaheuristics provided comparable results in terms of the value of objective function as well as of the computational efficiency.
Determination of the Optimal Range of the Compressor Inlet Air Temperature in a Power Plant With Stig Cycle Through of Advanced Exergetic Analysis
Authors: Barreto D. , Fajardo J. , Campillo J. 
Published: January 2020

Abstract
Conventional exergy analysis identifies the more inefficient components; however, this doesn’t regard interaction between components, neither real improvement potential to each component of the system, this information is providing for the advanced exergy analysis. In this paper was developed an advanced exergy analysis to determine the optimal range of the compressor inlet air temperature, to compensate the power loss in a power plant with Stig cycle and an air cooling system. This plant without cooling system at ISO conditions produce 52 MW, while in local conditions (32 °C, 80%RH) its productions decreases to 44.3MW. The results showed that for every degree centigrade that the air temperature decreases at inlet compressor the power output increases in 0.17 MW and total destroyed exergy increases 0.23 MW. It was determined that for the optimal range of compressor inlet air temperature is between 10 and 12°C; at this range were obtained the highest power output values, and the values of the avoidable and endogenous exergy destroyed are diminished in 0.28 MW and 0.20 MW respectively compared to those given in local operating conditions.
Evaluation of Thermal Effects in Turning Processes: Numerical and Experimental Approach
Authors: Kolluri Aruna Prabha , Balla Srinivasa Prasad , Paruchuru Satya Prasad 
Published: January 2020

Abstract
The 3D Finite element method (FEM) is an efficient tool to predict the variables in the cutting process, which is otherwise challenging to obtain with the experimental methods alone. The present study combines both experimental findings and finite element simulation outcomes to investigate the effect of tool material on output process variables, such as vibrations, cutting temperature distribution and tool wear mechanism. Machining of popular aerospace materials like Ti-6Al-4V and Al7075 turned with coated and uncoated tools are part of the investigation. The authors choose the orthogonal test, measured vibrations and cutting temperatures and used FE simulations to carry out the subsequent validations. This study includes the influence of the predicted heat flux and temperature distribution on the tool wear mechanism. The main aim of this study is to investigate the performance quality of uncoated and coated carbide tools along with its thermal aspects. Comparison of experiment and simulation outcomes shows good agreement with a maximum error of 9.02%. It has been noted that the increase of cutting temperature is proportional to its cutting speed. As the cutting speed increases, it is observed that vibration parameter and flank wear value also increases. Overall, coated carbide turning insert tool is the best method for metal turning with higher rotational speeds of the spindle.
Influence of Fractional Flow Reserve Setting on the Procedure Precision
Authors: Abuouf Yasser , Ookawara Shinichi , Ahmed Mahmoud 
Published: January 2020

Abstract
Coronary artery disease is the progressive narrowing (stenosis) of the heart supply arteries. Heart attack could occur as a consequence of severe blockage in the artery. A definitive diagnosis of its severity is of great importance for physicians to decide the best treatment plan. Fractional flow reserve (FFR) is a procedure that adopts a sensor tipped guidewire to measure upstream and downstream pressures of the stenosis. It is considered the most accurate method to pinpoint the stenosis severity. In this procedure, the centerlines of the guidewire and blood vessel should be aligned together. Due to the long distance between its insertion point and the stenosis, a possible inclination of the guidewire can occur. The aim of the present study is to investigate the effect of guidewire inclination on pressure measurements. Three different degrees of severity are modeled with placing the guidewire at different inclination angles. Continuity and momentum equations of blood flow are stated and computationally simulated. Comparisons between calculated and available measured values show a good agreement. The ratios between pressure drop and distal dynamic pressure (CDP), and between pressure recovery coefficient and the area blockage (η) are calculated. The predicted results for each case are compared with the control case (without guidewire) and analyzed. The results aid in improving the FFR accuracy in diagnosis of stenosis severity.
A New Composite Phase Change Material for Thermal Energy Storage
Authors: Su Che-Fu , Xiang Xinrui , Esmaeilzadeh Hamed , Wang Jirui , Fratto Edward , Charmchi Majid , Gu Zhiyong , Sun Hongwei 
Published: January 2020

Abstract
Enhancing the thermal conductivity of phase change materials (PCMs) is attracting attention for renewable energy applications such as solar, geothermal and wind energy. The use of energy storage can significantly improve the efficiency of renewable energy systems due to their intermittent nature. Latent heat thermal energy storage is a particularly attractive technique due to its high capacity can store energy at near constant temperature corresponding to the phase transition temperature of the PCMs. The present work aims to overcome this undesirable property of low thermal conductivity by manipulating metal fillers including nickel (Ni) nanoparticles/nanowires within the paraffin wax to improve its thermal property. In present work, a finite element method (FEM) was developed to obtain a fundamental understanding of the behavior of the Ni particles/wires under a uniform magnetic field by predefined magnetic pads. In the model, the Navier-Stokes equations were introduced as governing equations for the fluid field and the magnetic field was simulated by Maxwell’s equations. Then the motion of single Ni wire was modeled and the translation and rotational movements of the wire was studied in this paper.
A Quaternion-Based Sliding Mode Observer for Gyro-Bias Estimation and Attitude Reconstruction
Authors: Tian Yuan , Compere Marc , Drakunov Sergey 
Published: January 2020

Abstract
Localization accuracy is one of the most important parts of Unmanned Vehicle Systems, Automated Vehicles, Robotics and Navigation. The 6-DOF Inertial Measurement Unit (IMU) is a commonly used device for inertial navigation and is composed of a 3-axis accelerometer and 3-axis gyroscope. The body-fixed IMU measurements are combined with initial values to produce a position and orientation estimate in the inertial frame with every new measurement. However, IMU performance is greatly degraded by bias, scale-factor, non-orthogonality, temperature, and noise. This paper develops a sliding mode observer specifically focused on gyroscope bias estimation to improve gyro measurement results. The work presented here improves the performance of tilt sensors equipped in a commercially available smartphones with accelerometers and gyroscopes. The algorithm uses quaternions to avoid the well-known Euler angle singularities also known as gimbal lock. The observed gyro-bias can be used to reconstruct an improved estimation of the real attitude. A sliding-mode observer was constructed, and A* Matrix stability criterion were used to guarantee observer error convergence in finite time. The algorithm was verified using both a simulated IMU model and experimental tests with a custom designed rotational platform. Simulation tests used a predefined gyros-bias to ensure the algorithm-estimated results converged to the correct value. Simulation results show the observer error quickly converges to zero and the gyro-bias estimation converged to the expected values. The results also show that the proposed method is very effective for reconstructing the real attitude using the observed gyro-bias. This study presents a fast, simple gyro-bias estimation method that can help reconstruct the real attitude with a simple formulation that eliminates complicated constraints.
Analysis of Combined Electroosmotic and Pressure Driven Flow of Multilayer Immiscible Fluids in a Narrow Capillary
Authors: Escandón Juan P. , Torres David A. 
Published: January 2020

Abstract
This paper presents the analytical solution of a combined electroosmotic and pressure driven flow of multilayer immiscible fluids in a narrow capillary. The mathematical model is based in the Poisson-Boltzmann equation and the modified Navier-Stokes equations. In the steady-state analysis, we consider different conditions at the interfaces between the fluids as potential differences, surface charge densities and electro-viscous stresses balances, which are discussed in detail. Results show the transport phenomena coupled in the description of velocity distribution, by the analyzing of the dimensionless parameters obtained, such as: potential differences, surface charge densities, electrokinetic parameters, term involving the external pressure gradient, ratios of viscosity and of dielectric permittivity. Here, the presence of a net electric charges balance at the interfaces breaks the continuity of the electric potential distributions and viscous shear stresses, modifying the flow field; thus, the electrical conditions established at the interfaces play an important role on the flow behavior. The present work, in which the velocity field is described, aims to be an important contribution in the development of theoretical models that provide a better understanding about labs-on-a-chip design.
Investigation of Heat Transfer Characteristics of Supercritical Carbon Dioxide at Microchannels
Authors: Asadzadeh Mostafa , Parahovnik Anatoly , Adeoye Stephen , Peles Yoav 
Published: January 2020

Abstract
Carbon Dioxide (SCO2) can revolutionize the thermal management landscape due to a dramatic increase in enthalpy and a specific heat near supercritical state, particularly along the pseudocritical line, which correspond to much lower temperatures and pressures than water and other refrigerants. This study is conducted to assess the capability of supercritical CO2 in heat transfer applications. The heat transfer coefficient of carbon dioxide near the pseudocritical conditions was experimentally studied at the micro scale. Devices with 20 micro channels were fabricated to measure local and average heat transfer coefficient as well as system pressure drop. The experimental results showed a significant increase up to 72000 W/m2.k in local heat transfer coefficient and large pressure drop up to 3 MPa at microscale with supercritical CO2.
The Influence Rule of Geometric Parameters on the Closure of Inside Cavity of the Skew Rolled Steel Ball by Floating Pressure Method
Authors: Shu Chang , Xia Yingxiang , Shu Xuedao , Tian Duanyang 
Published: January 2020

Abstract
Due to the impact of alternating tension-and-compression on the skew rolled steel ball, it is prone to generate the defects of cavity inside the steel ball. In order to eliminate this cavity, this paper applies the Floating-Pressure-Method (FPM) to handle this imperfection. The procedures of FPM are: putting the rolled steel ball into the floating pressure device, then increasing the air pressure on the steel ball and maintaining this pressure for some time, finally eliminating the undesired cavity inside the steel ball. The DEFORM-3D finite element software, is used for simulation of the void cavity inside the steel ball by applying the FPM conditions, then analyzing the diameter, shape and position of cavity as well as the numbers of cavities and so on, obtaining the influence rule of geometric parameters on the closure of inside cavity of the skew rolled steel ball by floating pressure method. The experiment of FPM shows that the cavity inside the steel ball can be closed effectively and the maintain high dimensional accuracy. The research results provide theoretical basis for reasonably determining the process parameters of FPM and improving the quality of rolling products.
Fundamental Study on Friction-Driven Gyroscopic Power Generator Works Under Arbitrary Vibration
Authors: Watanabe Aya , Yuyama Ryousuke , Hosaka Hiroshi , Yamashita Akira 
Published: January 2020

Abstract
This paper describes a friction-driven gyro generator that works under arbitrary vibrations and generates more than 1 W of power. Vibrational generators are energy harvesters that convert environmental vibrations into electrical power via the inertial force of pendulums. In conventional generators that use simple vibration, the power is less than 10 mW for a wearable size because vibrations in the natural environment are as low as 1 Hz. Gyroscopic generators increase the inertial force by rotating a pendulum at high speed and creating a gyro effect. In this generator, a palm-size product that generates 0.1 W and weighs 280 g has already been commercialized, but this device operates only under a particular vibration that synchronizes rotor precession and stalls under random vibration. To solve this problem, in this research, two gimbals and a precession spring are introduced to support the rotor. We developed a prototype generator with straight tracks measuring 16 cm × 11 cm × 12 cm with a mass of 980 g. Under a vibration of 4 Hz and ±20 degrees, power generation of 1.6 W was confirmed. Next, a prototype circular track was made. Power generation of 0.2 W with a vibration of 1 Hz and ±90 degrees was confirmed. Finally, a simple formula to estimate the upper limit of the generation power is derived. It is suggested that the circular-type generator is suitable for low-frequency vibration and can generate twice the power of a straight-type generator.
X-Ray Induced Acoustic Computed Tomography for Non-Destructive Testing of Aircraft Structure
Authors: Tran Tiffany , Samant Pratik , Xiang Liangzhong , Liu Yingtao 
Published: January 2020

Abstract
For decades, aircraft disasters have always been a concern for airline companies and especially for consumers. Scientists all over the world have been constantly trying to study, discover and invent new methods for testing and prevention to reduce future aircraft accidents. One of those methods is non-destructive testing, which is a widely adaptive process for analyzing structural integrity over wide arrays of object. X-rays, ultrasound and computed tomography (CT) are non-destructive testing applications commonly used for the commercial aircraft maintenance. These non-destructive testing methods for aircraft structures give us high-quality images of structural damage but, there are some disadvantages related to resolution and the contrast mechanism of the image. The goal of this study is to demonstrate the concept of X-Ray Induced Acoustic Computed Tomography (XACT) imaging method for defect detection and localization through simulations using k-wave MATLAB toolbox. XACT is a technique based on the X-ray induced acoustic effect. In XACT, a short pulsed of X-rays are required to achieve thermal response and generate acoustic waves. X-ray travels to an object, the photons are absorbed causing the temperature in the object to raise, which generates acoustic waves due to thermoelastic expansion. These acoustic waves are then detected by ultrasonic transducers. Within the fuselage of the aircraft, the aircraft’s stiffener is designed using SolidWorks. along with two different types of defects through voids due to manufacturing imperfection process. As well as, cracks in the surface of the model due to mechanical failures are created in MATLAB. Two properties of Aluminum 6065 and Inconel 625 materials were selected for our simulation study since it is often used for the fuselage and/or aircraft engines. XACT images are generated under the combination of high X-ray absorption and ultrasonic transducers that will be able to overcome the disadvantages of the X-ray imaging technique and ultrasound imaging technique in image resolution and contrast mechanisms. The results from this simulation study demonstrate that the XACT method not only gives us high-resolution images but moreover, higher contrast of images that also allows us to detect position accuracy of the cons created.
Time-Domain Spectral Element Simulation of Lamb Wave Time Reversal Method for Detecting a Breathing Crack in a Plate
Authors: Yu Zexing , Du Fei , Xu Chao 
Published: January 2020

Abstract
Lamb wave is considered as an appropriate approach to detect the cracks in structures. This paper combines an efficient time-domain spectral finite element with time reversal method to develop an efficient breathing crack detection method. In this regard, Gauss-Lobatto-Legendre quadrature rules and penalty function method are carried out to construct an effective and accurate approach. Comparing the computation scales and results of this method and traditional finite element method, the validity and superiority of the proposed model is stressed. The reconstructed signals of two scenarios, intact and impaired structures, are captured. It is concluded that, this approach is capable of detecting breathing cracks. In addition, the influences of the relative depth of the notch and incident region are studied. This research may provide the guidance for experiment configuration and the further study.
Multi-Material FDM 3D Printing Process Parameter Development Based on Bending Test Characterization
Authors: Lai Heather L. , Nelson Aaron 
Published: January 2020

Abstract
The purpose of this investigation is to study the effects of perimeter inflation on the dynamic behavior of a flexible / rigid multi-material interface. The results of this study can be applied to applications where there is a need for low cost, multi-material 3D printed parts which have both flexibility and strength at the material interfaces designed to undergo simultaneous axial strain and flexural strain.
A non-homogeneous 3D printed structure with the desired static and dynamic mechanical behavior was designed using a flexible thermoplastic polyurethane substrate (NinjaFlex) and stiff ABS segment. The multi-material part was printed using a consumer grade dual extruder desktop FDM 3D printer.
This project focused on the evaluation of the mechanical behavior of the 3D multi-material due to delamination at the interfaces between the materials undergoing simultaneous flexural and axial loading. In order to reduce the occurrences of delamination, overlap at the interfaces was imposed by using perimeter inflation of both the two different materials. The purpose of the project was to develop a test methodology for the evaluation of the use of perimeter inflation in order to improve the behavior of the multi-material fused deposition printed parts. A modified 3 point bending test was developed to measure the equivalent stiffness and internal damping of the material interface.
As a result of this testing, increasing the perimeter inflation was found to cause a modest increase in the stiffness of the interface, with little effect on the internal damping of the interface.
Cancelling Gyroscopic Effects in AMB Systems With Flexible Rotors via Modal Feedback
Authors: Sahinkaya Alican , Sawicki Jerzy T. 
Published: January 2020

Abstract
For active magnetic bearing (AMB) systems with rotors having significant polar to transverse moments of inertia ratio, the influence of gyroscopic effects needs to be considered in controller design procedures to prevent excessive vibrations and potential instability during operation. This consideration leads to conservative controllers due to large uncertainties caused by the rotational speed range of the rotor, or gain-scheduled controllers that require larger computational power, both of which are not desirable. A cross-feedback control has been applied in the literature to compensate for the gyroscopic effects of AMB systems with rigid rotors. However, the method is not applicable to AMB systems with flexible rotors due to lack of full-state sensory information and under actuation. This paper proposes a novel modal state feedback control as an addon controller for AMB systems with flexible rotors to compensate for the gyroscopic effects of selected modes. The aim of the add-on controller is to alter the open loop AMB system such that the open loop dynamics presents reduced gyroscopic effects of the selected modes from a controller point of view, reducing the uncertainties in the model for robust controller design. The proposed approach is demonstrated on an AMB rotor test rig with a rotor configuration featuring noticeable gyroscopic effects. The comparison of the frequency response data of the open loop AMB system with and without the proposed add-on controller shows the feasibility of the approach.
Calibration Strategies and Modeling Approaches for Predicting Load-Displacement Behavior and Failure for Multiaxial Loadings in Threaded Fasteners
Authors: Mersch John P. , Smith Jeffrey A. , Orient George E. , Grimmer Peter W. , Gearhart Jhana 
Published: January 2020

Abstract
Multiple fastener reduced-order models and fitting strategies are used on a multiaxial dataset and these models are further evaluated using a high-fidelity analysis model to demonstrate how well these strategies predict load-displacement behavior and failure. Two common reduced-order modeling approaches, the plug and spot weld, are calibrated, assessed, and compared to a more intensive approach — a “two-block” plug calibrated to multiple datasets. An optimization analysis workflow leveraging a genetic algorithm was exercised on a set of quasistatic test data where fasteners were pulled at angles from 0° to 90° in 15° increments to obtain material parameters for a fastener model that best capture the load-displacement behavior of the chosen datasets. The one-block plug is calibrated just to the tension data, the spot weld is calibrated to the tension (0°) and shear (90°), and the two-block plug is calibrated to all data available (0°–90°). These calibrations are further assessed by incorporating these models and modeling approaches into a high-fidelity analysis model of the test setup and comparing the load-displacement predictions to the raw test data.