bluuebunny/crossref_metadata_2025_split huggingface dataset:
A General Purpose Automatic Mesh Generation Using Shape Recognition Technique
Authors: Takahashi H. , Shimizu H. 
Published: April 2021

Abstract
This paper proposes a new automatic mesh generation algorithm, in which an artificial intelligence technique is introduced to imitate the process of human thinking for generating meshes. In this paper, the word “mesh” is used in lieu of element used in Finite Element Method. This system satisfies the user requirement that a geometric model should be divided into only quadrilateral meshes such that distortions are relatively small. The shape of a geometric model is recognized to provide the system with the ability to generate meshes for an arbitrary shape, and the ambiguity contained in the shape recognition is expressed by the membership function used in Fuzzy Logic.
The algorithm for two dimensional automatic mesh generation is described and the application of this algorithm to a surface model is presented in this paper.
The Development of a Two-Dimensional Automatic Free-Form Mesh Generator
Authors: Sezer Levent , Zeid Ibrahim 
Published: April 2021

Abstract
A fully-automatic free-form mesh generation method is described in this paper. The related mesh generator is capable of meshing planar regions. In addition to being fully-automatic, the method produces quadrilateral or triangular elements with aspect ratios near one. The input to the method includes the region’s boundary curves, the element size, and the mesh grading information. The method begins by decomposing the planar region to be meshed into convex subregions. Each subregion is meshed by first generating nodes on its boundaries using the input element size. The boundary nodes are then offset to mesh the subregion. The resulting meshes are merged together to form the final mesh. The free-form mesh generator and its related method has been tested and applied to a wide number of regions. Sample examples are presented.
Simulation of Submicron Particle Deposition in Laminar and Turbulent Stagnation Point Flows
Authors: Abuzeid Salem , Busnaina Ahmed A. 
Published: April 2021

Abstract
The two dimensional laminar and turbulence stagnation-point flow over a wafer surface within a cleanroom environment are numerically simulated. This study shows the relationship between particle capture area on the wafer and the particle size and flow conditions. The mean flow field is simulated using a two equation k-ϵ turbulence model. Trajectories of aerosol particles are evaluated by solving the corresponding Lagrangian equation of motion that includes effects of drag, gravity, lift force, Brownian motion and turbulence fluctuations. The Brownian motion is modeled as a white noise process and turbulence fluctuation is assumed to behave as Gaussian random process. Simulations are carried out for aerosol particles (of various sizes) released at different locations over the surface. Depositions of particles on the wall are evaluated and a capture area which varies with particle sizes is produced. The results show that Brownian motion becomes very significant when turbulence fluctuations start to disappear near the wall for particles smaller than 1 μm in diameter. The results also show that, deposition of particles in turbulent flows are usually higher than that in laminar flows for all particle sizes considered. The effect of fluid on particle deposition rate is predicted for fluid of air and water. The results show that, particles deposition rate in air is higher than that in water.
A Boundary Integral Method for Examining Underwater Explosion Bubble Dynamics
Authors: Wilkerson Stephen 
Published: April 2021

Abstract
A boundary integral formulation for the numerical calculation of an underwater explosion bubble’s expansion and collapse is presented. The formulation makes use of first-order three-dimensional panels and adapts the methodology specifically for the simulation of an underwater explosion bubble. These simulations include a free field bubble as well as a bubble’s interaction with a nearby fixed surface. A number of explosion bubble codes have been written using the boundary integral formulation and are discussed throughout the three-dimensional formulation. Specifically, a spherically symmetric code, an axisymmetric code for simple geometries, and a first-order three-dimensional code was developed. The validity of the three-dimensional code presented is established through direct comparisons with the previously validated axisymmetric code (Wilkerson, 1989).
Investigations of Liquid Motion in Rigid Containers Under Microgravity Conditions
Authors: Vatistas G. H. , Kozel V. , Yan W. , Sankar T. S. 
Published: April 2021

Abstract
The dynamic behavior of the free surface of a liquid placed in rectangular or cylindrical containers, during a step transition from terrestrial conditions to weightlessness and liquid drainage from rectangular containers in zero gravity are investigated numerically. The required time for the surface oscillations to decay to 1% of the original amplitude was found to depend on Reynolds number and the contact angle. The numerically obtained results are shown to approach the exact zero-gravity equilibrium state asymptotically. During liquid drainage through a central hole, the degree of surface depression was found to depend strongly on the exit velocity. The amount of residual liquid could be reduced by strategically placing the exit ports at the lower corners of the tank.
Computational Evolution of Optimal Iceform Shapes Over a Flat Plate
Authors: LaFleur Ronald S. 
Published: April 2021

Abstract
This paper presents the computational evolution of minimum energy dissipation iceform contours. The ice/water interface is shaped according to fluid dynamic and heat transfer characteristics of the flow field near the interface. A Couette iceform design model is used to approximate flow and thermal field behavior near the interface. The theory used to calculate the interface shape is based on a wedge model of the ice contour over a cold flat plate.
The steady state ice profile is calculated when Reynolds number and the thermal parameter are selected. The generation function, designation function and energy dissipation are related to the nonlinear geometric development. An optimal preprocess criterion is prescribed as zero evolution length. The result is optimal geometries that are adapted to the flow and thermal constraints.
Electrostatic Effects on Submicron Particles Deposition
Authors: Abuzeid Salem , Busnaina Ahmed A. 
Published: April 2021

Abstract
Laminar air flow in a two-dimensional stagnation point flow is numerically simulated. This geometry resemble the flow of air in clean room over a clean bench. The Lagrangian equation of motion of aerosol particle that includes effects of drag, gravity, lift force, Brownian motion and electrostatic force is solved numerically. The Brownian force is simulated as a Gaussian white noise random process. Trajectories of aerosol particles in the flow are evaluated and a deposition capture area which varies with particle sizes is produced. The effects of particle diameter and surface voltage on particle capture area (deposition area) are shown. Different surface voltages of 0.0, 1.0, and 4.0 kv/cm are considered. The results show that, deposition of particles increases as the surface voltage increases for all particle sizes considered. Also, the particles which have a minimum capture area are in the range of 0.50–1.0 μm. This implies that the particles which have a minimum deposition rate are in that range.
Optimizing the Operation of Gas Transmission Networks
Authors: Luongo C. A. , Yeung W. C. , Gilmour B. J. 
Published: April 2021

Abstract
This paper presents a generalized procedure for optimizing steady-state operation of natural gas networks based on different objectives: minimum fuel consumption, minimum fuel cost, maximum throughput, and maximum operating margin (profit). The generalized procedure is a hierarchical approach that combines linear and non-linear optimizers in order to achieve good performance without compromising accuracy in modeling physical network components (compressors, pipes, etc.). The non-linear optimizer is used to optimize the physical flows in the transmission networks. The non-linear optimizer calls the linear optimizer to find the optimum allocation of flows among the contracts for the best objective function. The solution technique used by the linear optimizer can handle thousands of contracts with and without two-tier priced structure. Separating the physical flow optimization and economic optimization makes the global optimization feasible for large problems usually encountered in the gas transmission industry. In that sense, the present optimization method bridges the gap between engineering modeling and economic dispatch optimization of natural gas networks.
Piston Geometry Design Effects on Combustion and Emission Characteristics
Authors: Gupta Ashwani K. , Jiang Lu , Keating Eugene L. 
Published: April 2021

Abstract
Numerical simulation of flow, combustion phenomena and pollutants emission characteristics have been obtained on an internal combustion engine having conventional flat piston and advanced piston geometries. The code employed the time marching procedure that solves the governing partial differential equations of multi-component chemically reactive fluid flow by finite difference method. The transient solution is marched out in a sequence of time steps. The results show that both the piston geometry and inlet flow conditions affects the local flame properties which subsequently alters the pollutants emission levels. The numerical results provide a cost effective means of developing advanced internal combustion engine chamber geometry design that provides high efficiency and low pollution levels. It is expected that increased computational tools will be used in the future for enhancing our understanding of the detailed combustion process in internal combustion engines and all other energy conversion systems. Such detailed information is critical for energy conservation and environmental pollution control.
Modeling of Free Vertical Turbulent Diffusion Flames
Authors: Gadalla M. A. , Sharif M. A. R. 
Published: April 2021

Abstract
A mathematical/empirical model compatible with the jet mixing theory for predicting the flow field properties, flame envelope, temperature distribution, and flame heights around a free vertical axi-symmetric turbulent diffusion flame has been developed. The model considers the effects of buoyancy force and the relative angle between the reactant jets. The flames are issued from a burner which consists of a central air jet and an annular fuel (commercial butane) jet. The annular jet is issued either vertically or at an angle to the flame axis. Experiments were performed earlier to measure the temperature distribution and concentration of carbon dioxide and oxygen in such flames. Three angular positions of the annular fuel jet and nine burner geometries were investigated. The model predictions in similar configurations are found to be in fair agreement with the experimental data.
Computer Simulation of Dynamic Impact Processes: A Visual and Audio Presentation
Authors: Cheng Wing L. , Craig Alan , Dilber Ilhan 
Published: April 2021

Abstract
Complicated dynamic phenomena as occurred in high velocity impact processes were studied using a numerical approach. A transient nonlinear finite element program was used to model and simulate the impact events. The use of supercomputers was required in these simulations due to the size of the problem and the duration of the events. Techniques designed to visualize 3D geometry as well as scientific data were developed to help researchers make sense out of the tremendous amount of data generated by the supercomputers. Resulting animation sequences provided a means to the researchers to study these dynamic processes. A newly developed technique called data sonification was also exploited to provide an additional medium to display scientific data. This is accomplished by mapping various parameters of the dataset to various parameters of sound. Two complex 3D numerical examples were used to demonstrate both visual and sonic techniques.
Finite Element Stress Analysis of Engine Piston
Authors: Mistry Anil , Sodhi Raj 
Published: April 2021

Abstract
In this analysis, Ford Motor Company’s, modular engine series piston was selected for the analysis purposes. The engine has a capacity of 4.6 liter, V-8 cylinder and with 2 valves. The piston is made of aluminum alloy material Z-16-T6. A three-dimensional finite element model was created to analyze the piston. The model, which contains only the quarter section of the piston due to loading symmetry and geometry, was used to calculate operating temperatures and the corresponding thermal expansion. Operating stresses due to thermal and mechanical loads were also calculated. The accuracy of the model was verified by material data published in the literature, as well as from the data provided by Ford Motor Company. The obtained results are very useful in the designing and developing the existing piston to increase wear resistance capacity. These results are also useful for design and development that will absorb more heat load, and reduce noise by proper barrel planning of the skirt from the deformation data of the piston. Additionally, it helps in reducing the piston weight and inertia forces through optimization.
Guidelines for Using Finite Element to Model Cortical Defects
Authors: Gessel G. R. , Bartlett J. P. , An K.-A. , Morrey B. F. 
Published: April 2021

Abstract
Guidelines for using finite element to model cortical defects were established by determining the consequences for solution accuracy of various modeling strategies. Solution accuracy was established by comparing finite element results to an existing experimental benchmark for the torsion of circular tubes that contained transverse through circular holes. A new automated modeling approach was developed that could be used to support clinical modeling of cortical defects.
Evaluating Optical Surfaces Using the Finite Element Method
Authors: Hatheway Alson E. , Bella David , Ghazarian Vigen 
Published: April 2021

Abstract
In the late 1960’s Malvick and Pearson (1968) used dynamic relaxation techniques to solve for the deflections of a four meter mirror in a variety of mounting configurations. The material has been widely used to design the mounting of large primary mirrors for a generation of optical instruments. In view of the advances in computational techniques and hardware in the intervening twenty years there has been interest in validating the analysis in a contemporary finite element code.
The writers have undertaken the task to update the analysis originally performed by Malvick and Pearson. The same problems are being solved using MSC/NASTRAN, Version 66. This paper is a discussion of the initial results with comments directed to analysts attempting to evaluate mounts for large mirrors.
An Attempt at the Detection of a Flaw Using the Inverse Problem Solution of Impedance Imaging
Authors: Hussain M. A. , McKee M. , Frankel J. 
Published: April 2021

Abstract
In this paper we present some preliminary numerical simulations which allow us to predict a single flaw in a simply connected body. The purpose of this investigation was to detect flaws and cracks of engineering components using the method of electrical current computed tomography (ECCT), which is used in non-destructive testing technology. As in the previous paper, we have utilized the network analogy to detect a single flaw anywhere in the object. For detection of multiple flaws, the analysis has to be refined to give consistent results.
Dynamic Response Formulation for Pneumatically Driven Liquid in a Pressure Vessel
Authors: Loucks Richard B. 
Published: April 2021

Abstract
The Thermal Radiation Simulator (TRS) at the U.S. Army Ballistic Research Laboratory uses aluminum powder reacting with liquid oxygen to create a large jet like flame. The flame acts as a large thermally radiant wall, exposing targets to a nuclear weapon equivalent. The aluminum powder is driven pneumatically to the combustion chamber from a pressurized containment vessel. Unfortunately the thermal output of the flame oscillates with large amplitude relative to the mean yield. The fluctuating mass flow rate of aluminum powder from the aluminum powder containment vessel seemed the cause of the unstable output.
A computer model of the aluminum vessel was constructed to determine the pressure dynamics in the pressure vessel. The aluminum powder was assumed to behave as a Newtonian liquid. The pneumatic fluid was assumed to be an ideal gas. The model concentrated inside the vessel and at the exit. The result was to determine the mass flow rate of aluminum from the exit given the inlet gas pressures.
The model did reveal the source of mass flow fluctuations not to be caused directly by the existing pneumatic set-up. The variation was shown to be perturbated by forces outside the pressure vessel. Once the outside influence was eliminated, the model showed a clean mean flow rate of aluminum powder. The results were applied to the TRS and the thermal output was stabilized.
Dynamic Overturning Response of an Army Vehicle Subjected to a Side-On Blast Overpressure
Authors: Gupta Aaron Das , Wisniewski Henry L. 
Published: April 2021

Abstract
The dynamic overturning response of combat vehicles and vehicles with electronic equipment shelters is of interest to the defense community since critical internal equipments can be damaged contributing to system malfunction and reduction of vehicle effectiveness which can jeopardize the mission. To overcome sensitivity of vehicles and associated equipments to overturning, the Army is actively engaged in a hardening program which will result in overturning mitigation. The current investigation is devoted to determination of overturning response and sliding motion of a specific Army vehicle i.e., HMMWV jeep and the S-250 shelter assembly subjected to side-on diffraction and drag loads from a 10 psi blast overpressure. Assemblage of aerodynamic box models has been configured to represent the two vehicles and the generated models have been run upto 1.6 s using MINITRUCK which is an implicit two-dimensional version of a flexible multibody dynamics code available at the Ballistic Research Laboratory. The study indicates large sliding and overturning response of these vehicles in the absence of restraints and demonstrates the need for stabilization and overturning mitigation using outrigger pairs, cables, guywires and other active devices attached to the vehicle body.
Structural Finite Elements With High-Order Basis Functions
Authors: Balch Chad D. 
Published: April 2021

Abstract
In the p-version of the finite element method, convergence is achieved by increasing the polynomial order of the elements. This paper discusses high-order three-dimensional carved beam and shell elements which have been implemented in a general purpose p-version linear finite element code. The displacement and rotation fields are represented by polynomials up to ninth order. Beam axes are three-dimensional space curves, and shell midsurfaces are general doubly-curved surfaces. Results for linear static and modal analyses are presented. In particular, it is demonstrated that a relatively small number of elements provide highly accurate results for typical benchmark problems. The elements perform robustly, with no locking or spurious deformation modes.
Analysis of Stiffened Plates Using the Boundary Element and Finite Element Hybrid Method
Authors: Shih Hui-Ru , Duffield Roger C. 
Published: April 2021

Abstract
The boundary element and finite element hybrid method, based on a combination of unstiffened plate boundary element method and stiffener finite elements, is employed for static analysis of concentrically stiffened plates subjected to transverse loading. The integral equation formulation and its boundary element solution procedures for bending of a unstiffened plate are briefly reviewed. The algorithm which permits coupling of the unstiffened plate boundary elements with the beam (stiffener) finite elements is presented. The numerical implementations of the equilibrium and compatibility conditions along the interface between the plate and its stiffener are given in detail. Numerical examples illustrate the accuracy as well as the capability of the proposed method to determine the solution of stiffened plate bending problems.
Distribution of Flow Across the Radius of an Axisymmetric Shock Tube With Variable Cross-Sectional Area
Authors: Schraml Stephen J. , Pearson Richard J. 
Published: April 2021

Abstract
Experiments were conducted to study the characteristics of unsteady flow in a small, axisymmetric shock tube. These experiments have been supplemented by calculational results obtained from the SHARC hydrodynamic computer code. Early calculational results indicated that a substantial gradient in flow velocity and dynamic pressure may exist along the cross-section of the shock tube. To further investigate this phenomenon, a series of experiments was performed in which dynamic pressure measurements were made at various radii in the expansion section of the shock tube. Additional calculations with the SHARC code were also performed in which turbulence modelling, artificial viscosity and second order advection were employed.
The second set of calculations agree very well with the experimental results. These results indicate that the dynamic pressure is nearly constant across the radius of the shock tube. This contradicts the early computational results which were performed with first order advection and without turbulence modelling. As a result of these findings, it was concluded that turbulence modelling was necessary to obtain accurate shock tube flow simulations.
Analysis of EDM Process: A Finite Element Approach
Authors: Madhu P. , Jain V. K. , Sundararajan T. , Rajurkar K. P. 
Published: April 2021

Abstract
A model has been proposed for predicting the material removal rate and depth of damaged layer during Electro Discharge Machining (EDM). The transient heat conduction equation for the workpiece which accounts for the heat absorption due to melting, has been solved by the finite element method (FEM). Gaussian heat distribution of power within a spark has been considered and unlike in earlier theoretical works, the periodical updating of the shape of the workpiece surface has been performed. Computations have been performed for a single spark in the form of a pulse and a multi-sparks situation with a continuous power input and zero off time. The estimated results match fairly well with the experimental results.
Elastic-Plastic FEM Analysis of Deformations of a Cylinder Subjected to Severe Uniaxial and Bilateral Compression by Flat Plates
Authors: Gotoh M. , Shibata Y. 
Published: April 2021

Abstract
Uni-lateral and bi-lateral elastic-plastic compressions of a circular cylinder with three different wall thicknesses by flat plates are numerically analysed by the Finite Element Method (FEM). J2-flow theory (J2F), and J2-Gotoh’s corner theory (J2G) which was previously proposed by one of the authors are used as the constitutive equations. In the case of uni-lateral compression, the cylinder is compressed up to a completely flattened shape, which is considered a kind of plastic forming processes. The deformed shapes and the compressive force are predicted better by J2G than by J2F. The spring-back behaviours are also analysed by imposing unloading process during deformation. The deformation process in the compression of a ring (plane stress state) and a spherical shell (axi-symmetric state) is also analysed. In the case of bi-lateral compression, the process is considered a kind of square-tube forming. In its final stage, the cylinder deforms into a completely unexpected shape which could be thought of as a square tube reinforced with ribs. The J2G allows the process to proceed at a lower compressive force than that for J2F. The effect of n-value (the strain-hardedning exponent) on the deformation pattern is also discussed.