bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-Resolution Computations of Thermocapillary Convection in the Laser Weld Pool
Authors: Chen Tien-Ching , Kannatey-Asibu Elijah , Chen Michael M. 
Published: July 2023

Abstract
Fluid flow and heat transfer in the weld pool are driven by variations in the surface tension on the weld pool surface. For most metals and alloys, whose surface tension decreases as temperature increases, fluid flows from the center of the weld pool along the free surface toward the corners, leading to high thermal gradients and intense thermocapillary flow there. Most, if not all, previous numerical studies of the weld pool have suffered from inadequate resolution in the corner region, causing the conclusions of such calculations to be suspect. In order to understand the characteristics of the thermocapillary convection in the weld pool corner regions, the domain decomposition method is used to solve the weld pool convection problem accurately. A very fine mesh is used in the weld pool corner regions to insure adequate resolution. The results show that the shape of the solid-liquid interface in the corner regions is no longer nearly perpendicular to the flat free surface, as predicted by poorly resolved computations. In contrast, an inclined solid-liquid interface is found. The effect of Marangoni number on the slope of this solid-liquid interface and the heat transfer in the corner regions during laser welding are also discussed.
A Study of the Electronic Flame off Discharge Process Used for Ball Bonding in Microelectronic Packaging
Authors: Sripada Srinivas S. , Cohen I. M. , Ayyaswamy P. S. 
Published: July 2023

Abstract
Ball formation by electric discharge heating is the first step in the ball-wedge bonding process of microelectronic packaging. This is experimentally simulated using an up-scaled (x 60) model with a copper wire (1.55 mm diameter) having a bent tip. The Electronic Flame Off (EFO) discharge occurs in a 90 OCV arc chamber operating at a vacuum of 10–12 mmHg with air as cover gas. The control variables are current, voltage, arc duration, arc gap, and chamber pressure. Thermocouples embedded in the wire are used to obtain the transient, temperature variation. This temperature history is then used to deduce the heat transfer from the arc to the wire. Microscopic grain boundary studies of the balls are carried out to ascertain the nature of solidification, the extent of porosity and the heat affected zone (HAZ). Results for the transient current-power characteristics and the heat transfer are presented along with those for the metallographic studies. Based on studies such as this, optimal characteristics of “good” balls may be developed.
Infrared Feedback-Based Control of the Temperature Distribution in Thermal Rapid Prototyping
Authors: Doumanidis Charalabos C. , Fourligkas Nikolaos 
Published: July 2023

Abstract
Besides dimensional accuracy, the material structure and properties of parts fabricated by modern thermal desktop manufacturing techniques dictate the need for control of the temperature field through the heat input distribution on each prototype layer. A numerical simulation of the temperature and phase field in the solid and molten region of the scanned layers is first developed as an off-line computational testbed for control algorithms. Next, a computationally efficient linearized model based on Green’s field analysis is established as a real-time reference model for thermal identification and compensation of emissivity variations on the part surface. This is embedded in an adaptive control algorithm, using thermal feedback from an infrared camera to adjust the power of a heat source and guide its trajectory to the part region with the highest temperature deficiency, so as to optimize in-process the thermal field to a desired temperature distribution. This regulation strategy is tested by simulation and by experiment on a plasma-arc processing setup in open and closed-loop thermal blanking of simple layer patterns, while applications in other thermal rapid prototyping methods are also proposed.
Application of Discrete Exchange Factor Method to Combined Heat Transfer Problems in Cylindrical Media
Authors: Kassemi M. , Naraghi M. H. N. 
Published: July 2023

Abstract
This paper presents a numerical methodology for solving combined radiation-conduction-convection heat transfer problems in cylindrical geometries. The radiation heat transfer equations are discretized for a generalized cylindrical absorbing-emitting-scattering medium using the Discrete Exchange Factor (DEF) method. The accuracy of the method is demonstrated by comparing heat flux predictions to benchmark solutions and experimental results. Numerical simulations for two practical test cases extracted from ongoing research in thermal manufacturing are also included. The first example considers combined conduction-radiation heat transfer in sapphire fibers pulled from melt where the solid is cooled by volumetric radiation loss to the surroundings. Comparison of numerical results with analytical solutions based on singular perturbation analysis shows excellent agreement. The second example considers radiation and natural convection interactions in a cylindrical enclosure where because of the coupling between energy and flow equations through the buoyancy term, radiative heat transfer drastically modifies both the temperature and flow fields in the enclosure.
Study of a Wall Jet Burner for the Outside Vapor Deposition Process
Authors: Graham G. M. , Alam M. K. 
Published: July 2023

Abstract
An elongated wall jet burner for the production of optical fiber preforms using the outside vapor deposition process has been developed at Ohio University. The burner has been tested experimentally and has been found to produce a laminar flame jet at relatively large flow rates. The elongated design permits the deposition of SiO2 soot particles over a larger substrate area than for cylindrical burners. The burner has been tested in combination with a flat plate substrate to support concurrent numerical modeling efforts. The numerical model uses the commercial code FLUENT for computing the velocity and temperature fields and a second code developed at Ohio University for computing the particle deposition. Experimental data are used for velocity and temperature boundary conditions. Numerically computed deposition efficiencies correlate with experimental data.
Thermal Characteristics and Critical Heat Flux Behavior of Cutting Coolant and Water Mixtures Under Spray Cooling
Authors: Um Jae-Yong , Sehmbey Maninder S. , Chow Louis C. 
Published: July 2023

Abstract
An experiment was set up to investigate the heat transfer characteristics of spray cooling using mixtures of pure water with synthetic cutting fluid and emulsified oil. The heat transfer characteristics and the CHF (critical heat flux) behavior were studied in the traditional manner by measuring the heat flux versus the heater surface temperature. Different coolant mixtures showed different CHF values and heat transfer characteristics. A mixture of water with synthetic fluid has a higher heat removal capacity compared to pure water and has a peculiar CHF behavior (there are two CHF points). The emulsified oil and water mixture does not show the two CHF points phenomenon and has a lower CHF as compared to water.
On Selective Optical Absorber Film for Rotor of Opto Microengine
Authors: Ota Masahiro , Ishiguro Masataka , Sakamoto Moriyoshi 
Published: July 2023

Abstract
In this paper a selective optical absorber-plate is proposed for the rotor of the opto microengine as the actuator of a micromachine. The thin films of the selective optical absorber-plate are fabricated by a vacuum deposition machine. The deposited plates are at first stage pyrex glasses and then at the second stage aluminum ones. The deposition on the pyrex glasses is for estimating the deposition rate and revealing the characteristics of the deposited films. Germanium and silicon oxide are selected as the materials for making selective optical absorber-thin films. Germanium is used as an absorbent for absorbing a visible beam from a laser generator. On the other hand, silicon oxide is selected as the materials for making a thin film with a small reflectance of the visible beam.
The selective optical absorber-plates for the rotor of the opto microengines are made of aluminum plates deposited a germanium thin film and a silicon oxide thin film. The germanium film is at first deposited on aluminum flat plates and then the silicon film is deposited on the germanium film. Therefore, the rotor surface has the characteristics of small reflectance in visible rays and large reflectance in infrared rays. The surface deposited the films is named as a forward surface and on the other hand the opposite surface is a backward surface, respectively. The backward surface is an aluminum one.
Analysis of Drying Shrinkage and Flow due to Surface Tension of Spin-Coated Films on Grooved Substrates
Authors: Hirasawa Shigeki , Saito Yoko , Nezu Hiroki , Ohashi Naofumi , Maruyama Hiroyuki 
Published: July 2023

Abstract
In semiconductor manufacturing processes, it is important that the SiO2 isolation films around aluminum connection lines have flat surfaces in order to produce the multi-layered connection lines used in high-density devices. In this paper, we analyzed transient changes, in the thickness distributions of a liquid-SOG (Spin-on-Glass) film on a two-dimensional grooved substrate during the evaporative shrinking process. The flow due to surface tension of the shrinking liquid film was calculated. Since the film is thin, a boundary layer approximation could be applied, and fourth-order equations of film thickness were solved using an iteration method. The viscosity and the shrinkage rate were assumed to be functions of the concentration of the solvent in the film. When the parameter of [(surface tension) / {(shrinking speed) × (viscosity)}] is large and the width of the grooves is small, final surface undulations of the film are shallow. The effect of the centrifugal force was also analyzed.
Numerical Simulation of Spray Temperature Modulation in Spray Forming Process by Ceramic Powder Injection
Authors: Muoio Nathan G. , Crowe Clayton T. , Fritsching Udo , Bergmann Dirk 
Published: July 2023

Abstract
In the spray forming process, molten metals are atomized by high speed gas jets to form a metal droplet spray. The high heat transfer rates to the gas from the molten metal droplets effects a hot spray core which hinders droplets solidification. The introduction of ceramic materials to form a metal matrix composite can effectively cool the spray and enhance droplet solidification.
Numerical Dynamic Analysis of Moving GTA Weld Pool
Authors: Zhang Y. M. , Cao Z. N. , Kovačević R. 
Published: July 2023

Abstract
A three dimensional model with a moving heat source is developed to describe heat transfer and fluid flow in transient weld pools. Full penetration and free top and bottom surfaces are incorporated in the model in order to simulate the welding process more practically. The influence of plate thickness and welding current on the dynamics of weld pools is analyzed using calculated data. It is shown that when the workpiece is nearly penetrated, the depth of weld pool increases quickly. Also, the elevation of the top surface decrease quickly once the full penetration status is established.
Dye Diffusion Digital Imaging
Authors: LaFleche John E. , Benson Richard C. , Stack Kenneth D. , Burns Stephen J. 
Published: July 2023

Abstract
During the dye diffusion thermal printing process a dye-carrying ribbon is brought into contact with a receiver and these two surfaces are compressed between a printhead bead and elastomeric drum, creating the thermal printer nip. Within this highly pressurized contact region both heat and mass transfer takes place. In order to better understand the printing process we have created a finite difference model that simultaneously solves the heat and dye diffusion equation. Using experimental head temperature data we will describe a method for determining a surface boundary condition that can be used in the simulation. This boundary condition will allow us to incorporate different pulse modulation heating schemes in order to predict temperature variations and dye penetration patterns. In the discretization of the diffusion equation we will account for concentration dependence of the diffusivities that is common in many polymer systems. This consideration leads to a nonlinear governing equation for the dye diffusion process.
Closed-Form Forced Response of a Damped, Rotating, Multiple Disks/Spindle System
Authors: Shen I. Y. 
Published: July 2023

Abstract
This paper is to study forced vibration response of a rotating disk/spindle system consisting of multiple flexible circular disks clamped to a rigid spindle supported by two flexible bearings. In particular, the disk/spindle system is subjected to prescribed translational base excitations as well as externally applied loads. Because of the bearing flexibility, the rigid spindle undergoes infinitesimal rigid-body rotation and translation simultaneously. To model real vibration response that has finite resonance amplitudes, the disks and the bearings are assumed to be viscously damped. Equations of motion are then derived through use of Rayleigh dissipation function and Lagrange’s equation. The equations of motion include three sets of matrix differential equations: one for the rigid-body rocking of the spindle and one-nodal-diameter disk modes, one for the axial translation of the spindle and axisymmetric disk modes, and one for disk modes with two or more nodal diameters. Each matrix differential equation contains either a gyroscopic matrix or a damping matrix or both. The causal Green’s function of each matrix differential equation is determined explicitly in closed form through use of matrix inversion and inverse Laplace transforms. Closed-form forced response of the damped rotating disk/spindle system is then obtained from the causal Green’s function and the generalized forces through convolution integrals. Finally, responses of a disk/spindle system subjected to a concentrated sinusoidal load or an impulsive load are demonstrated numerically as an example.
Stability of Continuous Gyroscopic Systems Using Perturbation Analysis
Authors: Parker Robert G. 
Published: July 2023

Abstract
Continuous gyroscopic system eigenvalues and stability are analytically calculable in only a limited set of cases. This paper presents an eigenvalue perturbation analysis to determine approximate eigenvalue loci and stability conclusions in the vicinity of critical speeds and zero speed. The perturbation analysis relies on a formulation of the general continuous gyroscopic system eigenvalue problem in terms of matrix differential operators and vector eigenfunctions. The eigenvalue λ appears only as λ2 in the formulation, and the smoothness of λ2 at the critical speeds and zero speed is the essential feature required for the perturbatton. First order eigenvalue perturbations are determined at the critical speeds and zero speed. The derived eigenvalue perturbations are simple expressions in terms of the original mass, gyroscopic, and stiffness operators and the critical speed/stationary system eigenfunctions. Prediction of whether an eigenvalue passes to or from a region of divergence instability is determined by the sign of the eigenvalue perturbation. Additionally, perturbation of the critical speed/stationary system yields approximations for the eigenvalue loci at speeds away from these. The results provide analytical means for estimating continuous gyroscopic system eigenvalues and stability near critical speeds without numerical computation. The results are limited to systems having one independent eigenfunction associated with each critical speed and each stationary system eigenvalue. The techniques also apply to discrete gyroscopic systems. Examples are presented for an axially-moving, tensioned beam and a rotating rigid body and comparisons with known solutions are given.
Study on Vibrational Damping of Microcantilevers
Authors: Hosaka Hiroshi , Itao Kiyoshi 
Published: July 2023

Abstract
The damping characteristics of microcantilevers were clarified analytically and experimentally as a step towards developing next-generation information systems that use micromechanical devices. First, an approximate formula of airflow damping is derived using the Navier-Stokes equation and the total damping is obtained by combining this with internal friction and support loss. Precise measurement apparatus was then developed to verify the theory. The damping ratio of cantilevers ranging from 0.1 mm to 100 mm in length was measured and the effects of beam size, vibrational mode number, and vibrational amplitude on damping ratio were studied. Finally the relationship between vibrational damping and mechanical design parameters were summarized so that the results can be utilized in the actual design.
Design of an Accurate Speed Control System for Brushless DC Motor
Authors: Chen Zhang , Ma Joseph T. 
Published: July 2023

Abstract
The brushless DC motor is widely used in industry. In this paper, we present a low cost, high accuracy control scheme based on the structure characteristics of a brushless DC motor for speed control. The main features of the control system are as follows:
• Optimized motor efficiency
• Control of the spindle motor speed by a micro-controller
• Accuracy achieved on the operating speed at 3600 rpm is ±0.03%
The Stability of Flexible Spinning Disks Supported by Incompressible Hydrodynamic Lubrication
Authors: Renshaw Anthony A. 
Published: July 2023

Abstract
This paper uses Lyapunov’s method to examine the stability of a flexible spinning disk that is hydrodynamically coupled to the thin films of air surrounding it. A hydrodynamically coupled Lyapunov functional that defines the stable operational speed range of the disk is presented here for the first time. The stability boundary or, equivalently, the maximum stable speed, defined by this functional is independent of the strength of the coupling and allows significantly higher rotation speeds than allowed in the absence of hydrodynamic coupling. The hydrodynamically coupled critical speed is an order of magnitude higher than the uncoupled critical speed for clamping ratios less than 0.3. Several vibration modes of the disk which travel forwards at one half the rotation speed are stable but not asymptotically stable despite the large hydrodynamic damping present in the system. Unlike many elastohydrodynamic stability problems, calculation of the stability boundary using Lyapunov’s method is linear and tractable. The form of the Lyapunov functional suggests several design features that may be helpful in the design of improved, high speed configurations.
Thermal Modeling of Hard Disk Drives
Authors: Schirle Neal B. , Lew David 
Published: July 2023

Abstract
A methodology for thermal modeling of hard disk drives (HDD) using a computational fluid dynamics (CFD) program that solves the conjugate (conduction and convection) heat transfer problem is presented. The methodology addresses assumptions, model construction, and boundary conditions, as well as measurement methods for determining key model inputs such as HDD component power. Computed results are compared to measurements at a range of heat input conditions, volumetric flow rates, and HDD sizes. It is shown that the model does well in predicting temperature trends. It is also shown that for first order approximations, to predict average base casting temperatures, the total HDD power with an average convective heat transfer coefficient can be used. Also noted is the importance of considering the heat path through the air gap between the brushless d.c. motor stator and rotor.
Mechanism of Industrial Back Belts
Authors: Hsiang Simon , McGorry Ray , Bezverkhny Ilya 
Published: July 2023

Abstract
Back belts are commonly used in industry for the purpose of minimizing low back injury. Linear correlations among belt tension intra-abdominal pressure (IAP) and lumbar curvature were investigated as measures of back belt function. In this study, the mechanism was perturbed under the following conditions; no belt, elastic belt and sturdy belt, with and without Valsalva’s maneuver. Results showed strong interaction between belt tension and IAP, and less evident interaction between belt tension and lumbar curvature.
Trunk Extension and Flexion in Standing and Kneeling Postures: Peak Torque and Associated Electromyography of Ten Trunk Muscles
Authors: Gallagher Sean , Hamrick Christopher A. 
Published: July 2023

Abstract
Five subjects performed isometric trunk extension and flexion exercises in standing and kneeling postures at three angles of trunk flexion. Peak torque and electromyography (EMG) of ten trunk muscles were collected during these tests. Results indicated a 16% lower strength capacity in the kneeling posture; however, trunk muscle activity was similar in both postures. The altered biomechanics of the lower limbs in the kneeling posture may be responsible for the reduced strength capacity observed.
Finite Element Modeling of Pacemaker Leads for Use During the Design Process
Authors: Baxter Walt W. , Waldman Lewis K. , McIntyre Peter , McCulloch Andrew D. 
Published: July 2023

Abstract
The In Vivo intra-cardiac loading conditions placed upon transvenous endocardial pacing leads is not well understood. We have developed a technique for determining In Vivo pacing lead geometries and computing the resulting bending stress distribution at various times throughout a cardiac cycle. Using the model, one may locate areas of high stress concentration and determine the effect of changing design characteristics such as material stiffnesses or geometric parameters. The model is general and can be used to determine stresses and reactions acting upon any beam-like invasive device.
A NURBS Based Grid Generation Technique for a Temporally Deforming Geometry
Authors: Clutter Edward G. 
Published: July 2023

Abstract
When conducting a Computational Field Simulation of fluid flow for a biological application, such as blood flow through a vein, the results obtained will more accurately represent the physics involved if the interaction of wall mechanics and blood flow can be taken into account. However, the CPU time required to generate a new numerical grid at each time step quickly becomes too costly to be feasible for most real applications involving complex geometries. If this obstacle is to be overcome, a grid generation technique which can produce a grid in a timely fashion, while maintaining an accurate representation of the boundary in its currently deformed shape, must be devised. It is with this goal in mind that the following grid generation technique has been developed.
Correlation of Volume-Pressure Relationship in Lumbar Spinal Discs Using Both 3-D Model and Experimental Studies
Authors: Shirazi-Adl A. , Ranu Harcharan Singh 
Published: July 2023

Abstract
A 3-D finite element model has been developed and it is being used to analyse the effect of alteration in the nucleus fluid content on the over all mechanics of a lumbar motion segment. The results show that a change in the nucleus volume directly affected the intradiscal pressure. Similar results are also obtained in an experimental study where intradiscal pressures are measured by infusing a small volume of saline solution in an intervertebral disc in a slow and continuous fashion by a pump.