bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Laser-Ceramic and Laser-Metal Material Processing
Authors: Deng G. , Gordon M. H. , Roe L. A. , Malshe A. P. , Schmidt W. F. 
Published: November 2021

Abstract
In an effort to better understand and thereby utilize laser processing, an existing code describing laser-metal (aluminum) interaction is modified to describe laser-ceramic (diamond) interaction. Comparisons between our modified code (diamond target) and the original code (aluminum target) highlight similarities and differences between laser-ceramic and laser-metal processing. Gas breakdown effects, which are expected for the simulated short (time duration), high energy laser pulses, are observed in both codes. Due to the lower sublimation heat of aluminum (1.1×104J/g) compared to diamond (5.3×104J/g), aluminum vaporizes more quickly and exhibits a faster expansion speed (1.4×107 cm/sec compared to 8×106 cm/sec for diamond) in the early stage of the laser pulse. Because aluminum requires significantly more energy to fully ionize than does carbon, our simulations show that the diamond plasma is fully ionized (6 of 6 electrons per atom) and the aluminum plasma is partially ionized (11 of 13 electrons per atom).
The Use of a Multizone Model for Prediction of Soot and NOx Emission in a D.I. Diesel Engine as a Function of Intake Air O2 Content
Authors: Gao Zhiming , Schreiber Will 
Published: November 2021

Abstract
A phenomenological model based on the use of multiple zones is described and compared with other experimental and analytical work. This multizone model is used to examine the effect on emissions of increasing the oxygen concentration in the intake air of a compression-ignition, direct-injection engine. It is concluded that O2-enriched air could only be useful if combined with other modifications such as auxiliary gas injection, split injection, and exhaust gas recirculation.
Heat Transfer in Suddenly Expanded Flow in a Channel With Porous Inserts
Authors: Rocamora Francisco D. , de Lemos Marcelo J. S. 
Published: November 2021

Abstract
This paper presents numerical results for laminar heat transfer and turbulent flow past a backward-facing step channel with and without a porous insert. The effects of thickness and permeability of the inserts on flow pattern and heat transfer features are assessed. It is found that for some combinations of thickness and permeability, the recirculating bubble right after the step is completely suppressed, improving the heat transfer characteristics for the lower wall.
On the Wall Boundary Condition for Computing Turbulent Heat Transfer With K–ω Models
Authors: Bredberg J. , Peng S.-H. , Davidson L. 
Published: November 2021

Abstract
A new wall boundary condition for the standard Wilcox’s k–ω model (1988) is proposed. The model combines a wall function and a low-Reynolds number approach, and a function that smoothly blends the two formulations, enabling the model to be used independently of the location of the first interior computational node. The model is calibrated using DNS-data for a channel flow and applied to a heat transfer prediction for a flow in a rib-roughened channel (Reb = 100 000). The results obtained with the new model are improved for various mesh sizes and are asymptotically identical with those of the standard k–ω turbulence model.
Inverse Heat Flux Problem in Quenching
Authors: Alam M. Khairul , Kuriger Rex J. , Zhong Rong 
Published: November 2021

Abstract
The quenching process is an important heat treatment method used to improve material properties. However, the heat transfer during quenching is particularly difficult to analyze and predict. To collect temperature data, quench probes have been used in controlled quenching experiments. The process of determination of the heat flux at the surface from the measured temperature data is the Inverse Heat Conduction Problem (IHCP), which is extremely sensitive to measurement errors. This paper reports on an experimental and theoretical study of quenching which is carried out to determine the surface heat flux history during a quenching process by an IHCP algorithm. The inverse heat conduction algorithm is applied to experimental data from a quenching experiment. The surface heat flux is then calculated, and the theoretical curve is compared with experimental results.
Role of Vibration-Induced Streaming in Float-Zone Crystal Growth
Authors: Anilkumar Amrutur V. , Grugel Richard N. 
Published: November 2021

Abstract
The streaming induced in a short vertical liquid column by the vibration of one of the supporting end walls has been utilized in this novel study. Vibration essentially drives a surface flow in the zone away from the vibrating wall, with the return flow in the bulk towards the wall. Preliminary measurements of the surface streaming velocity show that it increases with the frequency and amplitude of vibration and the zone length, and decreases with the viscosity of the zone liquid. This controlled surface streaming has been employed to balance a opposing, steady thermocapillary flow in model half-zones of silicone oil and Sodium Nitrate. In addition, in a float-zone solidification experiment with Sodium Nitrate - Barium Nitrate eutectic as the study material, we have demonstrated that streaming-based balancing of thermocapillary flow promotes a planar solid/liquid interface and a uniform microstructure.
Design of a Biomimetic Directional Microphone Diaphragm
Authors: Gibbons C. , Miles R. N. 
Published: November 2021

Abstract
A miniature silicon condenser microphone diaphragm has been designed that exhibits good predicted directionality, sensitivity, and reliability. The design was based on the structure of a fly’s ear (Ormia ochracea) that has highly directional hearing through mechanical coupling of the eardrums. The diaphragm that is 1mm × 2mm × 20 microns is intended to be fabricated out of polysilicon through microelectromechanical micromachining. It was designed through the finite-element method in ANSYS in order to build the necessary mode shapes and frequencies into the mechanical behavior of the design. Through postprocessing of the ANSYS data, the diaphragm’s response to an arbitrary sound source, sensitivity, robustness, and Articulation Index - Directivity Index (AI-DI) were predicted. The design should yield a sensitivity as high as 100 mV/Pa, an AI-DI of 4.764 with Directivity Index as high as 6 between 1.5 and 5 kHz. The diaphragm structure was predicted be able to withstand a sound pressure level of 151.74 dB. The sound level that would result in collapse of the capacitive sensor is 129.9 dB.. The equivalent sound level due to the self-noise of the microphone is predicted to be 30.8 dBA.
Prediction of Turbulence Ingestion Forces for Rotors With Arbitrary Rake and Skew
Authors: Gavin Joseph R. , Lauchle Gerald C. , Jonson Michael L. 
Published: November 2021

Abstract
It is well known that turbomachinery rotors produce low frequency forces when subjected to a turbulent inflow. Predictions to date have been based largely upon idealizations of radial blades operating in homogeneous isotropic turbulence. In the present work these models are slightly extended to include the effects of complex blade geometry. The credibility of the method is then tested through comparison to existing experimental data. These comparisons show that the method performs well regarding the shape of the frequency spectrum and the relative effects of complex blade geometries. However, the method tends to sometimes overestimate the absolute levels of the thrust spectra.
Realization of a Minimum-Order Power Flow Model and SEA Model Updating Using Time Domain Measurements
Authors: Gregory Joseph W. , Keltie Richard F. , Caulfield F. Donald 
Published: November 2021

Abstract
A time domain method for identifying middle to high frequency system parameters from sound and vibration measurements is presented. This work is part of a beginning investigation with an objective of enhancing experimental Statistical Energy Analysis (SEA). Thus far, it is seen that a state space realization method can be used to identify a first order power flow model from measured transient power and energy data. Specifically, the Eigensystem Realization Algorithm (ERA) is observed to accurately identify a minimum order model for a simple system. Additionally, it is found that the identified model can be used to improve an existing SEA model of the system.
Identification of Complex Noise Sources Using the HELS Method
Authors: Wu Sean F. , Rayess N. E. , Shiau Mae-Ming 
Published: November 2021

Abstract
In this paper, the Helmholtz Equation Least Squares (HELS) method (Wang and Wu, 1997; Wu and Wang, 1998; Wu and Yu, 1998; Wu, 2000) is used to reconstruct the radiated acoustic pressure fields from a replicated vehicle front end. To simulate sound radiation from a real vehicle, an engine noise simulator (ENS) is installed inside the front end at the location of the engine. The white noise emitted from the ENS is measured by a microphone. For convenience, measurements are taken over finite planar surfaces above, in front, and alongside of the structure. These measured data are taken as input to the HELS formulation to reconstruct the acoustic pressures on the top, front, and side surfaces of the vehicle. The reconstructed acoustic pressures are then compared with measured ones at the same locations. Also shown are comparisons of the reconstructed and measured acoustic pressure spectra at various locations on the surface. Results show that satisfactory reconstruction can be obtained based on relatively few measurements taken in the field. Experiments indicate that the accuracy of reconstruction can be further improved by taking more measurements over a conformal surface around the structure at closer range. However, planar measurements are easier to implement in practice, while conformal measurements often requires a programmed robot arm which may make the reconstruction process more costly. In any event, the HELS method has proven to be effective in reconstructing the radiated acoustic pressure field from a non-spherical source in the low-to-mid frequency and may become potentially a viable noise diagnostic tool for the practicing engineers.
A Source Reconstruction Process Based on an Indirect Variational Boundary Element Formulation
Authors: Zhang Zhidong , Vlahopoulos Nickolas , Allen T. , Zhang K. Y. 
Published: November 2021

Abstract
The objective of the work presented in this paper is the development of a computational capability for recreating the vibration of a source from acoustic field data. The formulation is based on the indirect variational boundary element method (IVBEM). The vibration of the source is computed from transfer functions defined between the field points and the surface of the source. The capability to account for the presence of obstacles in the field adjacent to the vibrating sources and the treatment of irregular frequencies are included in the IVBEM formulation. A singular value decomposition (SVD) solver is integrated with the IVBEM computations in order to evaluate the vibration of the source. An algorithm that identifies the optimum field points where the acoustic pressure of the original field must be prescribed in order to accomplish the most efficient source reconstruction is also developed. Several validation and application cases are presented.
Monitoring and Defect Detection of an All-Composite Road Bridge
Authors: Crane Roger M. , Gillespie John W. , Heider Dirk , Eckel Douglas A. , Ratcliffe Colin P. 
Published: November 2021

Abstract
This paper presents the results of an ongoing investigation into the use of broadband vibration data to monitor the structural integrity and health of an all-composite road bridge. Bridge 1-351 on Business Route 896 in Glasgow, Delaware, was replaced with one of the first state-owned all-composite bridges in the nation in the fall of 1998. The bridge consists of two E-Glass/vinyl ester sandwich core sections (13-ft × 32 ft) joined by a longitudinal joint in the traffic direction. Each sandwich core section consists of a 28-inch deep core and 0.4-0.7-inch thick facesheets.
Vibration data were obtained from the upper and lower surfaces of the bridge using a mesh of 1050 test points. From the modal information and the visualization of the data, several aspects of the structural behavior of the bridge were obtained. These characteristics include the interactions between the bridge and abutments; the effectiveness of the longitudinal joint to couple the deck sections; the effectiveness of the core to couple the face sheets; and the structural integrity and dynamic consistency of the entire structure. Mode shapes and natural frequencies were determined and are correlated with theoretical calculations and vibration analyses conducted for this bridge.
A novel algorithm using the vibration data is being developed that enables local perturbations sensitive to the state of the material (e.g. manufacturing defects, material degradation or service damage) to be detected and spatially located in the bridge. This technique has been successfully validated for locating damage in 1-D beam structures and is being extended to the 3-D sandwich configuration of the bridge. By coupling this damage detection algorithm with the more conventional modal technique, the quality assurance/quality control and health monitoring of large composite bridge can be obtained.
Analysis of the Reflection Coefficient of Rayleigh Waves From Surface-Breaking Cracks
Authors: Hassan Waled , Veronesi William 
Published: November 2021

Abstract
The interaction of surface acoustic waves with finite-size, surface-breaking, semi-circular cracks is studied theoretically, numerically, and experimentally. We focus on the behavior of the reflection coefficient of the Rayleigh wave from such cracks in both the far and near fields of the crack. It is shown that, in the near field, the reflection coefficient from such cracks is higher than the reflection coefficient measured in the far field. This is mainly due to the diverging nature of the Rayleigh wave reflected from the crack. In the high crack depth to wave length ratio, the finite element and experimental results approach the limiting value of the reflection coefficient from a 90-degree corner.
Adaptation of a Combustion Chamber for Gasified Biomass Combustion: Numerical Simulations
Authors: Duwig Christophe , Fredriksson Jan , Fransson Torsten 
Published: November 2021

Abstract
A gas turbine combustor was modified for addition of Low Heating Value (LHV) gas operation while retaining the original diesel option. New fuel inlets were designed and tested through numerical simulations.
CFD calculations have been made in order to investigate the new design combustion abilities. A commercial 3D finite-volume Navier-Stokes solver was used. The Eddy Dissipation model was used to simulate the combustion phenomena and the flow fields were given by using k-ε model, Algebraic Stress Models and Reynolds Stress Model.
The comparison between predictions using different turbulence models and grids showed some differences. The required grid for having grid independent results was found too CPU expensive. However, comparisons were done to investigate the influence of the turbulence description on the result. This influence was found significant. It was deduced that the mixing controlled the combustion process. The numerical description of quenching of the flame was found to have more influence on the emission predictions than the description of the reacting zone (swirl).
Simulations validated the modified design. Successful combustion operating conditions have been predicted in terms of CO emission. Ammonia conversion to NO was also investigated. The conversion rate was found to be between 65 and 73 %. NO emissions have been predicted, as the maximum temperatures in the combustor were over-predicted, ammonia conversion to NO was also over valued. However, the results show that the combustion process of LHV gas within a small combustor volume is achievable. The swirl was found to be an efficient way to promote the combustion process by improving the mixing. High NO emissions have been predicted. It came from the high conversion rate of fuel ammonia into NO.
Effect of Reduced Inlet Space on a Medium Flow Coefficient Centrifugal Compressor Stage
Authors: Hohlweg William , Amineni Naresh 
Published: November 2021

Abstract
Test versus CFD predictions are presented for a medium flow coefficient, centrifugal compressor stage with 10% shorter axial stage space. Short axial length is achieved by reducing the shroud radius of curvature of the upstream return channel inlet. Situations often occur in multistage compressor applications where either rotor dynamics on new equipment or existing casing length on revamped units necessitate shorter stage space. The effect of the reduced space on various stage performance parameters is discussed referenced to the original, full length, stage design. CFD analysis for both configurations is also presented to compare with the test results and help explain the aerodynamic source of the increased losses. The complete stage is modeled on the program CFX-TASCflow beginning with a radial inlet and continuing through the impeller, diffuser and return channel.
Thermomechanical Transformation Fatigue of SMA Actuators
Authors: Lagoudas Dimitris C. , Li Changcheng , Miller David A. , Rong Lijian 
Published: November 2021

Abstract
Thermally induced transformation fatigue experiments of Shape Memory Alloy (SMA) actuator wires are performed under different heat treatment conditions and different stress levels. The effect of various heat treatment conditions on the thermal transformation fatigue life of Ti-Ni-Cu (K-alloy) SMA wires is analyzed first and the optimal heat treatment condition is found. Results are then presented for the plastic strain accumulation as a function of the number of cycles to failure for different stress levels, and a relationship similar to the Manson-Coffin law is considered. Finally, fatigue results for partial phase transformation cycles are discussed.
Texture Evolution Induced by Electric Field in Piezoelectric Ceramics
Authors: Wan Shan , Bowman Keith J. 
Published: November 2021

Abstract
Piezoelectricity is strongly dependent on the preferred domain orientation. A fiber-like texture of a Navy VI Lead Zirconate Titanate (PZT) piezoelectric ceramic can be induced by electric poling. This texture can be further changed and strengthened by cross-poling, that is, applying a strong electrical field perpendicular to the original poling direction. In this paper we show preferred domain orientation changes and anisotropy transitions associated with poling and cross-poling in PZT piezoelectric ceramic. The poling and cross-poling induced textures can be explained by three-dimensional orientation dependent domain switching. Based on this discussion, we demonstrate that it is possible to tailor the preferred domain orientation distribution and improve anisotropic properties of piezoelectric ceramics by directional control of the 90° domain switching using cross-poling.
Damage Detection in Simulated Aging-Aircraft Panels Using the Electro-Mechanical Impedance Technique
Authors: Giurgiutiu Victor , Zagrai Andrei 
Published: November 2021

Abstract
The aging of aerospace structures is a major current concern of civilian and military aircraft operators. PZT active sensors offer special opportunities for developing sensor arrays for in-situ health monitoring of aging aircraft structures. In this paper, we examine the structural health monitoring of aging aircraft structures with the electro-mechanical (E/M) impedance method. Local impedance methodology as well as damage detection strategy were developed. The detection of damage due to corrosion, structural cracks, and active sensor self-diagnostics with electro-mechanical (E/M) impedance method are discussed. The paper emphasis is sensor fabrication and installation procedures. Consistency and repeatability of sensor fabrication and installation were perfected and confirmed by statistical tests on a number of nominally identical specimens. Experiments on simple metallic beams were then performed and the results were compared with readily available theoretical predictions. Experiments on square plates manufactured from aircraft grade thin-gage stock followed. Statistical analysis of plate data confirmed that consistent and repeatability results could be achieved with our methodology. Finally, experiments on realistic aircraft panels with simulated crack and corrosion damage were performed. An array of four sensors were installed along a line emanating at a right angle from the crack, and E/M impedance readings were collected from all sensors. Consistency of sensor readings was verified. Also, the tendency of frequency to shift in the vicinity of the crack was noticed. However, further data processing, and detailed FEM modeling are still needed before full understanding of the correlation between crack presence and sensors readings is achieved.
Disturbance Rejection Control of an Electromagnetic Bearing Spindle
Authors: Petteys Rebecca , Parker Gordon , Redmond James 
Published: November 2021

Abstract
The force exerted on the rotor by an active magnetic bearing is determined by the current flow in the magnet coils. This force can be controlled very precisely, making magnetic bearings a potential benefit for grinding, where cutting forces act as external disturbances on the shaft, resulting in degraded part finish. It is possible to achieve precise shaft positioning, reduce vibration of the shaft caused by external disturbances, and even damp out resonant modes. Adaptive control is an appealing approach for these systems because the controller can tune itself to account for an unknown periodic disturbance, such as cutting or grinding forces, injected in to the system. In this paper we show how one adaptive control algorithm can be applied to an AMB system with a periodic disturbance applied to the rotor. An adaptive algorithm was developed and implemented in both simulation and hardware, yielding significant reductions in rotor displacement in the presence of an external excitation. Ultimately, this type of algorithm could be applied to a magnetic bearing grinder to reduce unwanted motion of the spindle which leads to poor part finish and chatter.