bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Computational Fluid Dynamics Analysis of Turbulence and Wakes of Horizontal Axis Wind Turbines During Non-Operational Time Periods
Authors: Al-Qarishey Hussein , Fletcher Robert W. 
Published: February 2021

Abstract
Wind turbines can create turbulence and downstream wakes which can introduce generation losses of downstream impacted turbines. These downstream turbine-induced losses are due to two different conditions. The first is from power-producing rotating blades of upstream wind turbines agitating the subsequent downstream wind in a cork-screw like manner. The second is from non-rotating, non-operational, non-power-generating wind turbines. These non-operating turbines may be under scheduled service shutdown, or rendered non-functional due to longer-term or permanent mechanical problems.
In this work CFD was used to study downstream turbulence and wakes of a utility-scale, non-operational three-blade horizontal axis wind turbines (HAWT). A flow field was constructed using an unstructured grid around a HAWT (rotor hub elevation of 80 meters and a blade length of 40 meters). Various wind velocities were studied up to 25 meters per second. Incompressible flow was used to assess downstream turbulence using a three-dimensional steady state and unsteady state SST k-ω (two equation) turbulence model. Different blade positions with respect to angle of attack (α) were studied, with a 4 degree angle of attack reported here. Pressures and velocities for distances of 100 meters in front and 500 meters downstream from the wind turbine are reported.
The Effect of Plate Curvature on the Influence of Macroscale Geometric Voids in Controlling Stress Wave Propagation
Authors: Florio C. S. 
Published: February 2021

Abstract
Much work has been done to create and understand means to control the propagation of acoustic and light waves through materials and structures. The ability to perform similar studies on the control of stress waves has implications not only for the development of capabilities to disrupt stress waves in order to limit their damage, but also to direct stress waves in order to tailor the behavior of a structure for a specific functional goal. Recent studies have demonstrated the use of voids and inclusions of varying size, geometry, arrangement, and composition in structures to attenuate impact forces or cloak stress waves in thin, flat, plane stress plates. However, many structures that may benefit from these wave modification methods are comprised of cylindrical shells. It is not currently known how well the techniques to control wave propagation and trends identified in plane stress plates can be applied to structures with cylindrical shells. Therefore, this study develops and uses computational modeling methods to examine the modification and control of stress waves induced by an axial impact load in metal plates of varying curvature through the inclusion of macroscale voids.
Methods are developed and used in this work to study the response of metal plates of varying curvature with and without voids of different shapes and arrangement to axial impact loads. The response is quantified through the magnitude of the fixed end reaction force and through normal oscillations of discrete points along the length of the plate. Fast Fourier transformation and wavelet coherence techniques are used to understand both the time-averaged and time-dependent oscillation behavior. Correlations are drawn between plate curvature and void design on the control of the propagation of stress waves. The knowledge gained can help guide the understanding design of these stress wave modification features.
Effect of Wire Electrode Materials on Performance Characteristics for Wire Electrical Discharge Machining of Metal Matrix Composite Material
Authors: Ramu Gurupavan Hurugalavadi , Ravindra Holalu Venkatadas , Muddegowda Devegowda Tadagavadi 
Published: February 2021

Abstract
Composite materials are the advanced materials which are widely used in manufacturing industries. The most commonly used composite materials are metal matrix composites. Due to the presence of abrasive reinforcing particles, traditional machining of these causes severe tool wear and hence reduces the life of cutting tool. Wire electrical discharge machining (WEDM) is quite successful for machining of metal matrix composites. Wire Electrical Discharge machining is a specialized thermal machining process capable of accurately machining parts of hard materials with complex shapes. One of the main research fields in WEDM is related to the improvement of the process productivity by avoiding wire breakage. Wire electrodes used in WEDM are the core of the system. In this study the effect of different wire electrode materials on electrode wear and surface finish for wire electrical discharge machining of metal matrix composite material were investigated. The experiments were conducted under the following process parameters viz., pulse-on time, pulse-off time, wire feed speed and current. For the experiment the aluminium 6061 alloy with 0%, 5%, and 10% of silicon carbide (SiC) reinforcement material was used. To conduct the experiment CNC wire EDM machine with two different wires viz., molybdenum and brass wire was used. Experimental results indicate that for better surface finish of Al6061 alloy, the brass wire is more suitable. The use of brass wire as electrode material leads to significant reduction in electrode wear in machining of Al-5%SiC and Al-10%SiC composite materials compare to molybdenum wire. Increasing percentage of silicon carbide in aluminium 6061 alloy increases the variation in surface finish and electrode wear. Wire wear rate of both brass and molybdenum wire is increased with increase in percentage of silicon carbide.
Influence of Random Variable Dimension on the Fast Numerical Integration Method of Aero Engine Rotor Disk Failure Risk Analysis
Authors: Junbo Liu , Shuiting Ding , Guo Li 
Published: February 2021

Abstract
In the risk assessment of turbine rotor disks, the probability of failure of a certain disk type (after N flight cycles) is a vital criterion for estimating whether the disk is safe to use. Monte Carlo simulation (MCS) is often used to calculate the failure probability but is costly because it requires a large sample size. The numerical integration (NI) algorithm has been proven more efficient than MCS in conditions entailing three random variables. However, the previous studies on the NI method have not dealt with the influence of random variable dimension on calculation efficiency. Hence, this study aims to summarize the influence of variable dimensions on the time cost of a fastintegration algorithm. The time cost increases exponentially with the number of variables in the NI method. This conclusion provides a reference for the selection of probability algorithms involving multiple variables. The findings are expected to be of interest to the practice of efficient security design that considers multivariable conditions.
Separation of Non-Viable Chinese Hamster Ovary (CHO) Cells Using Dielectrophoresis in a Deterministic Lateral Displacement Ratchet
Authors: Khan Mohammed , Chen Xiaolin , Xu Jie 
Published: February 2021

Abstract
Chinese hamster ovary (CHO) cell is the most widely used mammalian cell line for commercial production of therapeutic protein. Any presence of non-viable cells in culture medium may adversely affect subsequent functionality of these proteins. Therefore, separation of non-viable cells from suspending medium is critical in biopharmaceutical and biomedical sectors. One such method termed Deterministic Lateral Displacement has already shown promising capabilities in separating cells based on the cell size difference by taking advantage of the predictable flow laminae. However, in cases where size overlaps between viable and non-viable cells are present, separation based solely on size suffers and high-resolution separation techniques are required. Dielectrophoresis, one of the most widely used nonlinear electro-kinetic mechanism, has the potential to manipulate the same size cells depending on the dielectric properties of individual cells. In this work, we demonstrated that a DLD device can be combined with a frequency-based AC electric field to perform high resolution continuous separation of non-viable CHO cells from the viable or productive cells. The behavior of the coupled DLD-DEP device is further investigated by employing numerical simulation to check the effect of geometrical parameters of the DLD arrays, velocities of the flow field and required applied voltages. A moderate row shift fraction with velocity 700μm/s provided a good separation behavior without any trapping. The cell viability was also ensured by maintaining proper electric field which otherwise may cause cell loss due to ion leakage. Our developed numerical model and presented results lay the groundwork for design and fabrication of high resolution DLD-DEP microchips for enhanced separation of viable and nonviable cells.
Design of Yaw and Tilt Alignment Inspection System for a Low-Resolution 3D LiDAR Using Planar Target
Authors: Oh Seontaek , Yu Ji-Hwan , Eskandarian Azim , Kim Young-Keun 
Published: February 2021

Abstract
It is crucial to attach a LiDAR (Light Detection and Ranging), a 3D sensor for a mobile platform such as robot and vehicle within the acceptable misalignment to detect the relative positions of surrounding obstacles accurately. This paper proposes a novel inspection method to estimate the yaw and tilt alignment of a LiDAR after the sensor attachment. The proposed method uses a planar target board to estimate the yaw and tilt angles of a low-resolution LiDAR with milli-degree precision. Experiments were conducted to evaluate the accuracy and precision of the proposed method with the designed test-bench that can control the reference pointing angle of the LiDAR from −10 to 10 degrees. The experiment results on Velodyne VLP-16, a low-resolution LiDAR with 16 channels, showed that the proposed system estimated the yaw and tilt angles within accuracy and precision of 0.1 degrees.
Fluidic Injection Thrust Reverser System for High Bypass Ratio Turbofan Engines: Experimental Model
Authors: Kumar Raghav , Rajput Pankaj , Kumar Sunil 
Published: February 2021

Abstract
Conventional thrust reversers involve the usage of mechanical blockers which are bulky as they are designed to sustain heavy loads. As a result, they account for 30% of the nacelle weight (excluding the engine core). This added engine weight results in a 0.5%–1% increase in the specific fuel consumption of the aircraft. This paper advances our investigation of “Blockerless Engine Thrust Reversers” and uses it as an inspiration to optimize the system by designing an injection module (depicting an injection as a bleed from the core flow), conducting a computational analysis and demonstrating the viability of the process by building an experimental model of a 1:40 scale of a GE90 - 115B engine. A 3D printed experimental model was built after conducting an extensive parametric analysis. This model is used to demonstrate the viability of the “Fluidic Injection Thrust Reverser” (FITR) qualitatively and quantitatively.
A New Approach to Evaluate and Optimize Swirl Tube Demister Efficiency
Authors: Anderson Kyle , Reinhardt Ben , Sultani Walead , O' Hern Hannah , Zhang Xiang , Abbasi Bahman 
Published: February 2021

Abstract
The focus of this report is on a new technique to quantify the air-water separation efficiency of a swirl tube demister that has application in numerous water purification systems. This experimental study adds to the existing literature by quantifying the effect of design parameters on both the previously studied water collection efficiency, as well as the air bypass efficiency, defined as the ratio of the air mass flowrate exiting at the desired air outlet, over the inlet air mass flowrate. This parameter is important for the water purification field because air acts as a carrier of contaminants, necessitating that it does not leak into the purified water collection chamber. Results from this study showed there was a clear trend when comparing the air bypass efficiency to the inlet air to water ratio. As the inlet air to water ratio increased, the air bypass efficiency decreased. This trend was consistent among four different experimental apparatuses indicating that either the geometry of the swirl tube had very little effect of the air bypass efficiency, or that the ranges tested for dimensions thought to affect the swirl tube performance were not varied enough.
Periodic Motions in an Autonomous System With a Discontinuous Vector Field
Authors: Guo Siyu , Luo Albert C. J. 
Published: February 2021

Abstract
In this paper, periodic motions in an autonomous system with a discontinuous vector field are discussed. The periodic motions are obtained by constructing a set of algebraic equations based on motion mapping structures. The stability of periodic motions is investigated through eigenvalue analysis. The grazing bifurcations are presented by varying the spring stiffness. Once the grazing bifurcation occurs, periodic motions switches from the old motion to a new one. Numerical simulations are conducted for motion illustrations. The parameter study helps one understand autonomous discontinuous dynamical systems.
An Investigation of the Aerodynamic and Vibration Behavior of a Helicopter Rotor Blade
Authors: Pulok Mohammad Khairul Habib , Chakravarty Uttam K. 
Published: February 2021

Abstract
Rotary-wing aircrafts are the best-suited option in many cases for its vertical take-off and landing capacity, especially in any congested area, where a fixed-wing aircraft cannot perform. Rotor aerodynamic loading is the major reason behind helicopter vibration, therefore, determining the aerodynamic loadings are important. Coupling among aerodynamics and structural dynamics is involved in rotor blade design where the unsteady aerodynamic analysis is also imperative. In this study, a Bo 105 helicopter rotor blade is considered for computational aerodynamic analysis. A fluid-structure interaction model of the rotor blade with surrounding air is considered where the finite element model of the blade is coupled with the computational fluid dynamics model of the surrounding air. Aerodynamic coefficients, velocity profiles, and pressure profiles are analyzed from the fluid-structure interaction model. The resonance frequencies and mode shapes are also obtained by the computational method. A small-scale model of the rotor blade is manufactured, and experimental analysis of similar contemplation is conducted for the validation of the numerical results. Wind tunnel and vibration testing arrangements are used for the experimental validation of the aerodynamic and vibration characteristics by the small-scale rotor blade. The computational results show that the aerodynamic properties of the rotor blade vary with the change of angle of attack and natural frequency changes with mode number.
Vibration Suppression of an Elastically Supported Beam With Closely Spaced Natural Frequencies
Authors: Liu Haizhou , Gao Hao 
Published: February 2021

Abstract
Vibration suppression of distributed parameter systems is of great interest and has a wide range of applications. The dynamic performance of a primary system can be improved by adding dynamic vibration absorbers (DVA). Although the relevant topics have been studied for decades, the trade-off between capability of suppressing multiple resonant peaks and complexity of absorbers has not been well addressed. In this paper, the vibration suppression problem of a uniform Euler-Bernoulli beam with closely spaced natural frequencies is investigated. To achieve desired vibration reduction, a two-DOF DVA is connected to the beam through a pair of a spring and a dashpot. By introducing a virtual ground spring, the parameters of the absorber are determined via extended fixed point theory. The proposed method only requires univariate optimization and is computationally efficient. Numerical examples conducted verify the viability of the proposed method and the effectiveness of a two-DOF DVA in suppressing double resonances.
An Investigation on Flexural Fatigue Behavior of CFRP Quasi-Isotropic Laminates
Authors: Panbarasu K. , Ranganath V. R. , Prakash Raghu V. 
Published: February 2021

Abstract
In this study, AS4/914 grade carbon fibre reinforced plastic (CFRP) laminates with two different quasi-isotropic (QI) layup sequences are compared for their performance under four point bend flexure fatigue loads. The QI laminates were designated and fabricated as Laminate-1 (L1) [0/45/-45/90]2S and Laminate-2 (L2) [0/90/45/-45]2S, respectively. These laminates were designed, such that the 0° layers are placed at a similar position in both the laminate systems by changing the other layers. During the test, load and displacement data was monitored online along with instantaneous number of constant load amplitude (CLA) fatigue cycles to calculate the stiffness degradation. Three load levels of 90%, 80%, and 70% of the ultimate flexure strength (UFS) were chosen for assessing the flexure fatigue behavior of the laminates. A few tests were also attempted under variable amplitude loads: (i) high amplitude cycles followed by low amplitude and (ii) low amplitude cycles followed by high amplitude to examine load sequence effect on fatigue life, if any, as compared to the fatigue life under CLA. It has been observed that the laminate L1 performs better under higher amplitudes, while the laminate L2 shows increased life under lower load and variable amplitudes. The results obtained in the form of data plots and failure modes, supported by microscopic images, are discussed in the paper.
Mechanical Testing and Reliability Analysis for 3D Printed Cubic Lattices
Authors: Kulkarni Nitin Nagesh , Ekwaro-Osire Stephen , Egan Paul F. 
Published: February 2021

Abstract
3D printing has enabled new avenues to design and fabricate diverse structures for engineering applications, such as mechanically efficient lattices. Lattices are useful as implants for biological applications for supporting in vivo loads. However, inconsistencies in 3D printing motivates a need to quantify uncertainties contributing to mechanical failure using probabilistic analysis. Here, 50 cubic unit cell lattice samples were printed and tested with designs of 50% porosity, 500-micron beam diameters, and 3.5mm length, width, and height dimensions. The average length, width, and height measurements ranged from 3.47mm to 3.48mm. The precision in printing with a 95% confidence level was greater than 99.8%. Lattice elastic moduli ranged from about 270 MPa to 345 MPa, with a mean of 305 MPa. Probabilistic analyses were conducted with NESSUS software. The distributions of input parameters were determined using a chi-square test. The first-order reliability method was used to calculate the probability of failure and sensitivity of each input parameter. The elastic modulus was the most sensitive among all input parameters, with 57% of the total sensitivity. The study quantified printing inconsistencies and sensitives using empirical evidence and is a significant step forward for designing 3D printed parts for mechanical applications.
Measurement of Modes of Vibration of a Cultured Cell for its Mechanosensing Mechanisms
Authors: Sato Katsuya , Shiraishi Toshihiko 
Published: February 2021

Abstract
Applying mechanical vibration to cultured cells gives intracellular biochemical responses activated, for instance, their gene expression level is increased, so that it can be applied in the medical field. However, the cellular mechanisms of sensing mechanical vibration and transducing into the biochemical responses have not been clarified. One of the previous studies culturing osteoblastic cells under mechanical vibration showed that some of the intracellular biochemical responses reached peak depending on the frequencies like a resonance in the mechanical engineering field; the mRNA level of alkaline phosphatase at the frequency of 50 Hz reaches approximately 4.5 times as high as that at the control group [1]. Considering the analogy between the mechanical and the biochemical responses of a cell, the modes of vibration of a cell are thought to be related to the mechanosensing. In this study, the mode shapes of a single cell were experimentally measured under mechanical vibration up to 100 Hz using an improved experimental system with high natural frequencies designed to be low mass and high rigidity. This present paper will report the obtained experimental results of the mode shapes of a single cell nucleus and may contribute to the elucidation of the mechanosensing mechanisms of a cell for mechanical vibration.
Wet Gas Compressor Testing – Performance Uncertainty
Authors: Mæland Dagfinn , Bakken Lars E. 
Published: February 2021

Abstract
Based on experience from wet gas compressor testing at NTNU (low-pressure air-water fluid) and K-Lab full-scale testing (normal operating conditions, high pressure and hydrocarbon fluids), this paper documents important aspects relating to the uncertainty evaluation of wet gas compressor performance test results.
The Monte Carlo method for evaluation of uncertainty on a wet gas compressor system is outlined, and the resulting uncertainties of key compressor performance parameters are presented.
Furthermore, a sensitivity analysis has been performed to evaluate how uncertainties in the output of the model can be appointed to different sources of uncertainty in the inputs, thus identifying main contributors to the uncertainties.
The importance of accurately determining the fluid composition, the properties of the fluid components and how these affect the fluid characterization are discussed. Together with the choice of equation of state, the characterization directly affects the simulated fluid properties, and great care is required to obtain reliable compressor performance results.
Uncertainties of physical properties originating from the thermodynamic simulation show that compressor power and gas density ideally should be determined from direct measurements and not from thermodynamic simulations.
Estimation and Feasibility of Generating Power Using Tidal Energy
Authors: Paruchuru Satya Prasad , Koneti Siva Kalyani , Jammula Deepthi , Nuthalapati Jashwitha 
Published: February 2021

Abstract
Capturing the tidal energy is one of the ways of tapping natural and renewable energy which do not involve the cost of working fluid/ fuel. The present work focuses on some of the feasibility aspects of setting up of major tidal power plants along the seacoast. Besides, the present study synergizes on methods of estimating the power-producing capacities in regions along the seacoast. Estimation of power-producing capacities, calendar month-wise, and lunar month-wise gave handy information. Also, the estimation of power-producing capacities of different regions along a location gave clarity on the probable regions of interest for producing power simultaneously. A comparison of the estimates with the details of the literature authenticated the study. A discussion of producing more tidal power in specific locations gave insights into the aspects that may have been ignored in the literature. Geographic restrictions along the local seacoast like identifying the security-sensitive regions rationalized the estimating procedures. The paper includes a discussion of various factors that address the feasibility concerns. The study supposedly helps space exploration too.