bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of the Pin-Fin Heat Sink to Electronic Equipment [Study on Design Method for Flow-Guide Vanes]
Authors: Minakami Ko , Hisano Katsumi , Iwasaki Hideo , Mochizuki Sadanari
Published: July 2023

Experimental and numerical studies were carried out to evaluate the effect of flow-guide vanes on air-intake velocity into the air-cooling heat sink, in the case of using a high performance but large pressure loss heat sink, such as a pin-fin array, for microprocessors having high power density. The flow-guide vanes were placed at the inlet portion of the heat sink in the spanwise direction. The pin-fin array used in the experiments was made of square shaped thin (0.2 mm) copper pins. Thermal resistance of the pin-fin array with and without flow-guide vane was measured, varying the upstream air velocity and the angle of the flow-guide vanes as a parameter. In the numerical simulation, the pressure loss characteristic based on the empirical formulas was applied. Two-dimensional laminar flow analyses using the finite differential method were performed. The parameters were the upstream air velocity, and the width and angle of the flow-guide vanes. The tendencies of the experimental and numerical analysis results showed good agreement, and it was found that the effect of the angle of flow-guide vanes on the intake air velocity was small. Also, the relation between the upstream velocity and actual intake velocity to the heat sink was discussed, and the design method for the optimum configuration of flow-guide vanes was proposed.
Predicting Vehicle Crash Performance in Offset Barrier Impact
Authors: Fileta B. , Liu X.
Published: July 2023

This paper describes experimental and analytical techniques developed to alter a full barrier, one-dimension. lumped mass-spring model to a model which can be used to calculate the vehicle response in an offset rigid barrier impact. The changes to the full barrier model were based on significant findings from the comparative experimental investigation of the vehicle behavior in offset and full rigid barrier crashes. The techniques used to analyze the data in this experimental investigation are discussed. These techniques proved to be very effective in developing correlation factors between the two test types. Furthermore, methods of applying the experimental factors to generate new spring, mass, and contact data for modeling and crash simulation of the offset impact are presented. Finally, the paper discusses the correlation between the analytical results of the modified model and the crash test results.
Intelligent Hydraulic Bumper for Frontal Collision Mitigation
Authors: Jawad Saad A. W.
Published: July 2023

A proposal for collision mitigation is investigated in this paper. Two intelligently controlled hvdraulic cylinders is proposed to be extended prior to collision and absorb impact energy upon engagement with the other body. Feasibility and performance of collision mitigation were investigated with a simulation of the collision dynamics. Two phases of control were considered; pre-collision control and collision control. Various collision scenarios have been studied with view of predicting collision and proposing a pre-collision control strategy for activating the proposed hydraulic bumper. A learning digital computer pre-collision control is proposed.

For the purpose of this research a 0.5 m stroke hydraulic cylinders is used to act as an effective extension of the crash zone. A specially adapted fast response hydraulic flow control valve is proposed with certain collision control law. The collision control law aims at controlling the collision force at a given level corresponding to occupants acceleration not exceeding 20g. Simulation results revealed a maximum level of 15g deceleration could be achieved in a 30 mph collision.
Experimental and Theoretical Study on Heat Transfer of an Impinging Plasma Jet
Authors: Ogawa Kuniyasu , Hijikata Kunio
Published: July 2023

Heat transfer from an argon arc plasma jet at atmospheric pressure to a wall was investigated experimentally and theoretically. A new, water-cooled thermal probe was developed for measuring the plasma temperature and velocity. The temperature was determined from the measured heat flux by using an empirical relation for the heat transfer coefficient, taking into account the variable physical properties of the argon plasma. The measured temperature was in good agreement with those obtained from optical measurements. To clarify the effects of joule heating, re-combination of charged particles and electron working function on heat transfer to the wall, theoretical analysis near the stagnation point was performed and the results were compared with experimental data, where the local heat flux was measured by developing a new sensor. The results indicate that the most important heat transfer mechanism is heating by the electron work function.
Heat Transfer Characteristics in Polymers With Excimer Laser Irradiation
Authors: Fushinobu K. , Kimizuka J. , Satoh I. , Kurosaki Y.
Published: July 2023

Heat transfer characteristics of the excimer laser irradiated polymers are investigated experimentally and theoretically. Polyethylene and polystyrene samples are prepared for the experiment and irradiated with ArF and KrF lasers. The temperature rise of the film rear surface is measured and compared with theoretical predictions. Comparison between the experimental data and theoretical analysis indicates that only less than 10% of the incident laser energy is transformed into thermal energy in the polymer samples. Three-dimensional numerical calculation suggests the importance of rigorous numerical modeling of the problem.
Vertical Bridgeman Crystal Growth of Cd1-x
MnxTe
Authors: Dyke George , Zebib Abdelfattah
Published: July 2023

A computational study of the temperature and flow fields of solidifying Cd1-xMnxTe in a vertical Bridgeman furnace is conducted. Influence of furnace temperature profile, pulling velocity, Grashof number Gr, Prandtl number Pr, ratio of thermal to liquid conductivity Kl/Ks, and Stefan number is examined. Convection consistently causes an undesirable convex interface (as seen from the solid). The solid liquid interface is found to be sensitive to only the temperature profile and Kl/Ks. The flow field is significantly affected by Kl/Ks, the furnace temperature profile, and Gr. Due to the pseudo state model employed, the pulling velocity shows little effect for the parameter values of this study.

The flow is bicellular, with a strong upper cell (caused by the particular furnace temperature profile) and a weak lower cell (caused by the inequality of Kl and Ks). These cells are competitive, with the upper cell often absorbing the lower one. When the lower cell is present the interface is more convex. At high Gr, the flow is bicellular with mass transport between the two cells occurring by diffusion.
Simulation and Measurement of a Vertical Bridgman Growth System for β-NiAl Crystal
Authors: Ouyang H. , Shyy W. , Levit V. I. , Kaufman M. J.
Published: July 2023

A coordinated theoretical and experimental study of the temperature distributions inside a customized vertical Bridgman system for growing β-NiAl crystal has been conducted. This model accounts for the combined effects of phase change dynamics, coupled heat transfer processes of conduction, convection and radiation, variable material properties, and complex geometry pertaining to the system. Comparisons between numerical predictions and experimental measurements show satisfactory agreement. Important processing parameters such as interface curvatures and temperature gradients across the interface, along with possibilities of improving the solidification process have been explored.
High-Resolution Computations of Thermocapillary Convection in the Laser Weld Pool
Authors: Chen Tien-Ching , Kannatey-Asibu Elijah , Chen Michael M.
Published: July 2023

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Morphological Analysis of Human Thoracic Spine Endplate
Authors: Yoganandan Narayan , Hollowell James P. , Pintar Frank A. , Nicol Brad
Published: July 2023

This study was designed to determine the three-dimensional morphological characteristics of the human thoracic spine endplate. The analysis was performed on vertebral bodies from T4 through T11 using cryomicrotome techniques. The specimens were embedded in carboxyl-methyl-cellulose gel and sequential anatomic cryosections were taken. A total of approximately 36 sagittal slices were obtained at intervals of 200 to 500 microns. Approximately 200 measurements were taken on each endplate from T4 through T11 from the anterior to the posterior direction to define the anatomy. Three-dimensional contours of the endplate were created and the data were analyzed using statistical procedures (ANOVA). Thicknesses up to 1.15 mm were found in these studies. The mean thickness of all the endplates was 0.313 mm. The endplate demonstrated regional variations as well as variations between the bony and the cartilaginous counterparts. The bony endplate was 31 percent thicker in the anterior compared to the posterior region; 38 percent thinner in the central compared to the peripheral region; and 52 percent thinner in the superior compared to the inferior regions. In contrast, the cartilaginous endplate was 22 percent thicker in the anterior compared to the posterior region; the peripheral region was 192 percent thicker compared to the central region; and 23 percent thinner in the superior compared to the inferior region. The mean overall thickness of the cartilaginous endplate was 0.22 mm with a range of 0 to 1.42 mm. These data are of importance to clinicians as well as biomechanical engineers. For example, in a clinical setting, there are arguments and counter arguments for preserving or compromising the integrity of the endplate [1]. Because the spinal grafts are not always placed at the same location, it is necessary to define the three-dimensional morphological characteristics as well as determine the internal load carrying capacities of these localized regions. This study provides the necessary fundamental data regarding the localized variations of the endplate thickness so that existing detailed finite element models can be improvised to accurately define the endplate characteristics in an attempt to determine the relative contribution of the endplate on the biomechanics of the human spinal column.
Mechanism of Coronal Decompensation in Idiopathic Scoliosis
Authors: Rimkus Aruna , Patwardhan Avinash G. , Meade Kevin P. , Gavin Thomas M. , Bueche Matthew J.
Published: July 2023

A double scoliotic curve wherein the thoracic curve is larger than the lumbar curve and the lumbar curve is more flexible than the thoracic curve (flexibility index > 0) is called a King type II curve. In the surgical treatment of these curves, only the thoracic part is fused. The purpose of leaving the lumbar curve unfused is to save as many mobile lumbar segments as possible thereby reducing the risk of back pain and other complications. The lumbar curve corrects spontaneously when the thoracic curve is surgically corrected with the appropriate selection of the lower level of fusion.
A Preliminary Report on the Mechanism of Vertical Longitudinal Tears of the Meniscus
Authors: Bergman Joseph W. , Shrive Nigel G. , Frank Cyril B.
Published: July 2023

The mechanism of traumatic vertical longitudinal tears of the meniscus is investigated. Meniscal injuries can have significant sequelae yet little understanding of the mechanism of injury exists. An anatomic position and force based model of meniscal injury is proposed and preliminary results of testing are presented. Using the described test apparatus, superficial tears were created in 4 of 6 samples. The validity of the proposed mechanism and the significance of the empirical results are discussed.
Force Transfer Characteristics for a Double-Fastener Dental Implant
Authors: Sadler J. P. , Wang L. , Breeding L. C.
Published: July 2023

The replacement of missing teeth with an implant-supported prostheses eliminates the necessity of preparing the adjacent teeth to support and retain a conventional fixed partial denture, and may be similar in expense to the patient in many situations. Unfortunately, the implant-supported denture presents a biomechanical design problem. Screw loosening is perhaps the most common cause of structural failure. It occurs under repeated loading at stress levels below the ultimate strength of the material. With an increased understanding of the mechanical principles related to screw tightening, various mechanical explanations and assumptions have been made (Fig. 1). However, little information has been published with regard to a general model that can be used to predict the screw joint tightening and force transformation.
Human Body Vibration Control and Ride Comfort: A Two State Semi-Active Suspension Design for Cabs and Seats
Authors: Amirouche Farid M. L. , Tong Rick T. , Palkovics L.
Published: July 2023

This paper presents a computer controlled cab and driver’s seat suspension model for heavy trucks and off-road vehicles. There are two models representing the vehicle with a cab suspension and a seat with an operator modeled as a lumped mass system. The vehicle is modeled as an 8 degrees-of-freedom lumped mass with suspension characteristics of 3 axles vehicle and three tires with masses and stiffnesses. The seat is supported by linear spring and damper whose characteristics are time dependent. The ride comfort is measured by an index of relative acceleration between parts of the driver and the vehicle under stochastic road excitation. First, a sky hook control semi-active controller is designed to seek optimum cab suspension. The velocity and displacement of the cab is then used as an input to the seat-operator model to minimize the accelerations at the lower torso, Head, and neck as well as the work performed by the body active forces. This paper shows how the energy transmitted to the seat can be minimized at the cab level. Furthermore the input to seat becomes small making the seat suspension more realistic and attainable.
Particle Deposition in Lung Upper Airways
Authors: Asgharian B. , Zhang L.
Published: July 2023

Airborne particles may deposit on airway surfaces upon inhalation and cause lung injury and disease. The severity of injury depends on the amount deposited at a site as well as on the sensitivity of the cells to the dose delivered. To assess the risk from exposure to airborne materials, the amount deposited at various sites in the lung must be determined as a first step.
A Finite Element Model of Vapor Transport in the Human Nose
Authors: Keyhani Keyvan , Scherer Peter W. , Mozell Maxwell M.
Published: July 2023

A validated finite element model of air flow in the human nose was used to simulate nasal uptake of inhaled vapors. Computed steady laminar velocity fields were used in the solution of the uncoupled steady convective-diffusion equation. A wall boundary condition was developed that included effects of vapor solubility, transport, and removal in the nasal mucosa. The maximum inspiratory uptake was about 80% for highly mucus soluble vapors with Schmidt number equal to one at a half-nasal flow rate of 125 ml/s. The maximum flux in the turbinate region occurred at the anterior-inferior end of the middle turbinate. The flux pattern across the nasal surface became more uniform with a decrease in mucosal solubility.
Stretching-and-Folding Convective Mixing Induced by Chaotic Alveolated Duct Flow
Authors: Henry Frank S. , Tsuda Akira
Published: July 2023

A mechanism for aerosol mixing in the lung periphery is examined. It is shown that the rhythmical wall motion of acinar airways appears to generate an unexpected level of complexity in the acinar fluid flow and hence in the aerosol dynamics. A small particle cloud is shown to undergo stretching and folding, which is characteristic of chaotic mixing.
The Interaction of Geometry and Local Flow Phenomena in Compliant End-to-Side Anastomosis Models
Authors: Perktold Karl , Rappitsch Gerhard , Gruber Gerald , Trubel Wolfgang , Schima Heinz
Published: July 2023

Intimal thickening (IT) and consecutive occlusions preferentially occurring at the distal anastomosis are important complications in the clinical application of bypass grafts. Experimental and numerical studies have shown that there is a correlation between IT and hemodynamic factors, such as flow stagnation, separation and recirculation and low pulsatile wall shear stress (Bassiouny et al., 1992, Hofer et al., 1996). The present study aims to investigate the relationship between flow characteristics and IT in a conventional type end-to-side anastomosis using a PTFE graft. Due to the important influence of the geometry on the anastomotic flow field anatomically correct modelling is applied.
Computational Study of Local Fluid Speed-Up Past Vascular Indentation Without Significant Stenosis: A Potential Cause of Pressure Gradient Overestimation
Authors: Migliavacca Francesco , Kilner Philip J. , Dubini Gabriele , Pennati Giancarlo , Redaelli Alberto , Fumero Roberto
Published: July 2023

This paper presents a computational study of a fluid dynamic phenomenon which has bearing on clinical use of Doppler velocity measurements for estimation of pressure gradients across a suspected stenosis. In order to explore the phenomenon further, we set out to perform CFD simulations of pulsatile flow past localised wall deformations in rigid vessels of simulated size comparable to that of the aorta.
A Calculation of Two Dimensional Incompressible Flow Past Circular and Elliptical Cylinders at Different Positions in a Channel
Authors: Zhao Yu , Sharp M. Keith
Published: July 2023

A control volume based finite element method was used to calculate the two-dimensional viscous incompressible flow field around circular and elliptical cylinders at different positions in a channel. The Reynolds numbers based on the height of the channel and average inlet velocity in the calculation were 0.1, 0.5, 1, 5, 10, 15, and 20. The ratio of the diameter of the circular cylinder to the height of the channel was 0.1. The locations of the center of the cylinder compared with the height of the channel were 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45 and 0.5. The ratio of the long axis to the short axis of the ellipse was 1, 2, 3, 4, and 5 respectively and at the same time the area of the ellipse was kept equal to that of the cylinder. The pressure and viscous drag and lift forces exerted on the cylinder were calculated. These solutions were motivated by experimental evidence of lift on red blood cells in channel flow and in blood vessels and represent a first step in approaching the more complex problem of a deformable particle in channel flow. When the cylinder was assigned a weight representative of that of a typical red blood cell, results showed that when the channel Reynolds number is greater than about 0.5, the lift can raise the cylinder close to the center line of the channel.
Homographic, Hyperelastic Mathematical Modeling of Bio-Polymer and Soft Tissue Materials
Authors: Lucas Douglas R. , Conway Ted A.
Published: July 2023

The purpose of this paper and research is to develop data and results which may show that a constitutive model, based on thermodynamic relations, can be used to model isotropic, non-linear elastic, stable, incompressible, large deformation materials. The materials that I plan on reviewing are a bio-polymer, cis-polyisoprene, and biomaterials, ligaments and tendons.
Anterior Cruciate and Medial Collateral Ligament Fibroblasts Exhibit Different Ca2+ Responses to Fluid Flow
Authors: Hung Clark T. , Allen Fred D. , Pollack Solomon R. , Attia Eric T. , Hannafin Jo A. , Torzilli Peter A.
Published: July 2023

Injuries to the medial collateral ligament and anterior collateral ligament heal differently in vivo and this may be related to their response to physical forces. This hypothesis was tested by measuring the intracellular calcium concentration, [Ca2+]i, in canine MCL and ACL fibroblasts subjected to fluid flow (wall shear stress of 25 dynes/cm2). In experiments where a modified Hanks’ balanced salt solution perfusate was used, both cell types had a significant increase in [Ca2+]i compared to respective no-flow controls, MCL fibroblasts being nearly 2-fold greater than that of ACL fibroblasts. When 2% newborn bovine serum was added to the perfusate, ACL fibroblasts responded nearly 3-fold greater than MCL fibroblasts. The observed difference between the MCL and ACL fibroblast response to flow demonstrates that these cells are not the same.
Correlating Rabbit Movement With Load on its Medial Collateral Ligament
Authors: Spelier Eduard L. , Shrive Nigel G. , Frank Cyril B.
Published: July 2023

The relationship between the movement of a rabbits and the in vivo load on its Medial Collateral Ligament (MCL) was examined as well as the movement pattern differences before and after MCL gap surgery. No relationship could be established between movement and load. It was found however that the MCL is experiences only low loads in straight forward movement, and that the rabbit unloads the leg with the load-cell implanted.
Finite Element Formulation of a Biphasic Poroviscoelastic Model for Articular Cartilage
Authors: Bai S. , Suh J.-K.
Published: July 2023

Articular cartilage, a composite mixture of extracellular matrix and interstitial fluid, manifests viscoelastic characteristics, partly due to the frictional interaction between the porous matrix substrate and the interstitial fluid and partly due to the intrinsic viscoelastic behavior of proteoglycan gel of cartilage. The biphasic poroviscoelastic model (BPVE) has been used to predict the 1-D deformational behavior of articular cartilage [1,2]. In this study, we developed a finite element formulation of the poroviscoelastic model to investigate the mechanical response of articular cartilage under confined compression.
A Novel Method for Determination of Affinity of Surface Bound Receptor-Ligand Binding
Authors: Piper James W. , Swerlick Robert A. , Zhu Cheng
Published: July 2023

Cell-cell and cell-substrate adhesion is an integral component of many biological processes. These adhesive interactions are mediated by binding of cell adhesion molecules to their specific receptors. An important determinant of the receptor-ligand interaction is their binding affinity. Existing bulk chemistry approaches for measuring binding affinity require at least one of the reactants to be in solution. Therefore, at least one molecular species is able to move in three dimensions, and there is no force acting on the bond. This kind of binding affinity is referred to as 3-D affinity in the present paper. In contrast, in the case of cell adhesion, the motions of both molecular species are restricted to two-dimensional because both receptor and ligand are anchored to a surface (and the binding affinity is thereby referred to as 2-D affinity). In addition, dislodging forces usually exist which affect the binding reaction. This coupling between chemistry and mechanics requires that the binding affinity be a function of the bond force instead of a constant. Because of these differences, the (3D) binding affinity measured via traditional approaches cannot be directly applied to the analysis of receptor-ligand binding in cell adhesion. There is a lack of methods for the direct measurement of binding affinity when both receptor and ligand are bound to a surface and subject to a force. It is this gap that the present paper intends to fill.
Tensorial Character of Stress or Strain and the Experimental Constitutive Equation
Authors: Mazilu N. , Conway T. A. , Vossoughi J.
Published: July 2023

The well known classical approach of tensorial constitutive laws, in the isotropic case, shows a quadratic constitutive law as a possible relation between stress and strain tensors [1]. This law is obtained as a direct consequence of the Hamilton-Cayley theorem for 3 × 3 matrices and the hypothesis of existence of an energy function [2]. Now, from the experimental point of view, the most reliable facts are, undoubtedly, those related to uniaxial loading tests. These experiments only indicate a certain functionality between stress and strain, having usually a representation by integral functions. Such a representation is quadratic only in special cases, and these cases are extremely useful in discerning some special materials.