bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Performance Power Converters: An Engineering Systems Approach
Authors: Bartlett Edward L. 
Published: July 2023

Abstract
Ever since the transistor was introduced in the 1950’s, semiconductors have offered an ever increasing level of performance, providing exponentially greater applications. Life today would be vastly different without semiconductors. The successive introduction of the SCR (silicon controlled rectifier), the CTO (gated turn off thyristor) and then the ICBT (insulated gate bipolar transistor) has offered new, higher power applications for semiconductors.
Curing Analysis of a Flip-Chip-on-Board Electronic Package
Authors: Zheng Wen C. 
Published: July 2023

Abstract
A curing analysis of a Flip-Chip-On-Board (FCOB) assembly is reported in this paper. It is very important to understand the curing process of the FCOB assembly because a good curing scheme may obtain full mechanical and thermal properties of the epoxy. In order to do numerical simulations of the curing process, it is essential to establish the cure kinetic equations of the epoxy. Differential Scanning Calorimetry (DSC) tests were performed to collect experimental data. It was shown that the cure reaction satisfies the Arrhenius relation. It also was verified experimentally that the chemical curing reaction may be incomplete at lower isothermal cure temperatures. Various cure kinetic equations were used to fit the experimental cure data. The results show that the kinetic equations can be used to predict other DSC experiments quite well.
Two FEM models of the FCOB assembly, associated with the two different curing schemes, were analyzed by use of the FEM software ABAQUS. The cure kinetic equations were implemented in a user subroutine to update the heat generation due to the chemical reaction of the epoxy. Due to the part’s thinness, the results show that both the temperature and the degree of cure are distributed very uniformly over the FCOB assembly in the whole curing process, and that the history responses are almost independent of the sizes of the models. It is also proved numerically that the proposed curing scheme is better in that it may have the epoxy more fully cured.
Spectral Analysis of Constrained Translating Beams
Authors: Zhu W. D. , Guo B. Z. 
Published: July 2023

Abstract
A new spectral analysis for the distribution of eigenvalues of a constrained translating beam is presented. The constraint represented by a spring-mass-dashpot is located at any position along the beam. Closed-form, asymptotic solutions to the real parts of all eigenvalues are derived explicitly from the characteristic equation of the constrained system. The necessary and sufficient condition that ensures a uniform stability margin for all the modes of vibration is determined. Influences of the system parameters on the distribution of eigenvalues are identified. The analytical predictions for the asymptotic distribution of eigenvalues are validated by numerical solutions.
Analysis of Chatter Vibration in Multi-Flute End Milling
Authors: Shorr Michael J. , Liang Steven Y. 
Published: July 2023

Abstract
This research discusses the methodology of developing a symbolic closed form solution that describes the dynamic stability of multi-flute end milling. A solution of this nature facilitates machine tool design, machining parameter planning, process monitoring, diagnostics, and control. This study establishes a compliance feedback model that describes the dynamic behavior of regenerative chatter for multi-flute tool-work interaction. The model formulates the machining dynamics based upon the interconnecting relationship of the tool geometry convolution and the machining system compliance. The tool geometry convolution characterizes the cutting forces as a function of the process parameters and the material properties, while two independent vibratory modules, the mill tool and the workpiece, represent the machining system compliance. The compliance feedback model allows the development of a corresponding characteristic equation. By investigating the roots of the characteristic equation, this research symbolically expresses the stability of the system as a function of the cutting parameters, the tool geometry, the workpiece geometry, and the vibrational characteristics of the machine tool. Machining experimentation examining the fidelity of the regenerative chatter model is discussed. The dynamic cutting forces, cutting vibration, and surface finish of the machining process confirm the validity of the analytical prediction.
A Simulation of Active Control of Torsional Vibration in a Turbogenerator Rotor Shaft System (2)
Authors: Hao Z. , Elliott S. J. 
Published: July 2023

Abstract
The purpose of the paper is to derive an analysis that can be used to predict the achievable attenuation of total energy of torsional vibration in a turbogenerator shaft system and calculate the magnitude of the secondary source required to achieve this attenuation for a given active control actuator The results are showed by the computer simulation. The possibility of applying active control in the torsional vibration of a turbogenerator shaft system can thus be assessed.
Fracture Mechanics Analysis of Vehicle Body Panel Fatigue Cracking
Authors: Xia Houchun , Draper James D. , Xue David Y. 
Published: July 2023

Abstract
The evaluation of fatigue crack growth rate and prediction of fatigue life for automotive vehicle body panels using fracture mechanics method are presented in this paper. Two finite element approaches to calculate the strain energy release rate, C, are examined, i.e., the numerical differentiation method based on Griffith energy theory and the virtual crack closure technique. A numerical differentiation procedure based on quadratic interpolation polynomials to compute the G values is proposed, and the formulation for finite element implementation is derived. Excellent agreements are found between the two approaches. The fatigue crack analysis of a vehicle door outer panel under shipping conditions is presented as an example. Results show that the dominant failure mode for the panel cracking is opening mode or Mode-I, and the panel fatigue life can be significantly extended by properly designing the shipping containers.
Adaptive Neural Control for Active Flutter Suppression
Authors: Lichtenwalner Peter F. , Little Gerald R. , Pado Lawrence E. , Scott Robert C. 
Published: July 2023

Abstract
Under a joint research and development effort conducted by McDonnell Douglas Aerospace (MDA) and the National Aeronautics and Space Administration, Langley Research Center (NASA LaRC), a neural network-based adaptive control system has been developed and demonstrated for active wing flutter suppression. The adaptive control system, which uses a neural network embedded within a Model Predictive Control (MPC) framework, is referred to as Neural Predictive Control (NPC). During Phase II of the Adaptive Neural Control of Aeroelastic Response (ANCAR) program, the NPC system was applied for active flutter suppression using NASA’s Benchmark Active Controls Technology (BACT) wing model in the Transonic Dynamics Tunnel (TDT). The ability of the NPC system to self-configure a control law for stabilizing an unstable wing during flutter was demonstrated. This paper defines the basic architecture of the NPC approach and discusses the flutter suppression results obtained during the wind tunnel demonstration.
Calibration Neural Network for a Novel Omni-Directional Velocity Probe: PROBENET
Authors: Kinser Robert Eric , Furey Deborah A. , Rediniotis Othon K. 
Published: July 2023

Abstract
In this paper, the development of an adaptive neural network for the calibration of novel velocity measurement instrumentation is presented. The backpropagation-based algorithm, PROBENET, was initially developed for the calibration of multi-hole pressure probes, although at this point it has evolved to a generic-application code. The code offers distinct advantages over commercial packages (such as the Matlab Neural Network Toolkit, Demuth and Beale, 1994) in terms of maximum allowable network size, training convergence rates, flexibility in network architecture design and network optimization capabilities. PROBENET incorporates multiple activation functions per layer, as well as heuristics-based procedures for network-architecture optimization. Techniques for local minima avoidance and convergence rate improvement, incorporated into the algorithm, are: momentum, variable learning rate and Levenberg-Marquardt optimization methods.
The present study documents the performance of PROBENET when applied to the calibration of a novel 18-hole probe developed to overcome the flow angularity measurement limitations of traditional 5- and 7-hole probes. The study compared the performance of two types of network architectures: single activation function per layer and multiple activation functions per layer, and showed that the latter consistently produced a better solution in terms of convergence rate and accuracy. The use of multi-function layers and network optimization resulted in very good prediction accuracy of the flow parameters.
Neural Network Estimation of the Flowfield Structure of Spatially Excited Jets
Authors: Fuller Russell M. , Saunders William R. , Vandsburger Uri 
Published: July 2023

Abstract
In combustion systems, flows are both complex and nonlinear, leading to a need for tools such as neural networks which can be used for system identification of flowfield characteristic parameters. This article focuses on the use of two types of neural network architectures for the prediction of flowfield structures and jet expansion rates which were experimentally observed for a free jet undergoing spatial mode excitation. A nonlinear, backpropagation architecture is compared to a functional link neural network as both are used to predict the iso-velocity contours which result when a jet is acoustically excited with different spatial mode patterns. The results show that the neural networks estimate the azimuthal flow patterns at various downstream locations with a mean square error of less than 0.0041 inside the training set. Extrapolation outside the training set could not be verified because of the sparse data set available for the estimations; however, the qualitative assessment of those results indicated that the network results were reasonably accurate. It is also shown that the neural network estimates can accommodate nonlinearities in the flowfield structures which were not accurately predicted by previous research efforts in spatial mode excitation using linear stability analyses.
Application of Neural Networks to the Control of Burgers Equation With Random Forcing
Authors: Cho Yongseung , Agarwal Ramesh K. , Tupe Yogesh 
Published: July 2023

Abstract
In this paper, the feasibility of using artificial neural network to obtain the control inputs for the flow governed by Burgers equation with random forcing is studied. The objective is to provide a real time active controller for the flow. The data obtained from the optimal (LQG) and robust (H∞) control are used to train the network. Due to the structure of a neural network, it is possible for the trained neural network to imitate the controller in real time. The network consists of a layer with 4 input neurons, 2 hidden layers, a layer with 1 output neuron, and a bias neuron. The network is trained using backpropagation method. Several data sets are used for training and testing the network. The trained network is tested for the generality and for fault tolerance. A simulation with the neural network controller is conducted for the flow modeled by the Burgers equation with random forcing input. The results show that the employment of neural network as a controller can be effective for flow control problems.
Simulation of High Temperature Molten Fuel Coolant Mixing
Authors: Leskovar Matjaž , Marn Jure 
Published: July 2023

Abstract
This paper is assessing the first, premixing, stage of a steam explosion, which may occur during a sever reactor accident following core meltdown when the molten fuel comes into contact with the coolant water.
A general 2D multiphase flow program ESE based on probabilistic multiphase flow equations was developed. Each phase was described using probabilistic mass, momentum and energy equations. The interfacial friction and the interfacial heat transfer were treated probabilistically. That means that they take a probabilistic value of a given probabilistic distribution at each time step of the calculation.
To examine the accuracy of the program ESE the premixing experiment “MIXA06” with corresponding geometry and initial conditions was simulated. The results of the simulation were compared with experimental data and presented in form of graphs depicting the phase presence probability fields, steaming rate and depth of melt penetration.
CFD Prediction of Panel Vents Velocity Profiles Validated With Hot-Wire Measurements
Authors: AbdulNour Bashar S. 
Published: July 2023

Abstract
The flow field of automotive A/C panel vents was investigated in this study. Computational Fluid Dynamics (CFD) results were obtained and compared to test data for a variety of vent designs. The analysis was performed using the CFD package STAR-CD. The velocity profiles were determined experimentally using hot-wire anemometers. The results provided a valuable insight into the factors affecting the shape and distribution of the plume due to the flow issuing from the vents. The ability of the CFD models to identify trends such as concentrated versus diffuse plumes was very good. The experimental results were used to verify the integrity of the CFD models and validate our use of CFD modeling. Based on the degree of correlation of velocity profiles between the CFD simulations and the experimental work, it can be concluded that CFD simulation is a valid technique to investigate the air flow characteristics through panel vents.
High-Reynolds-Number-Flow Simulation and its Visualization
Authors: Kuwahara Kunio 
Published: July 2023

Abstract
Incompressible high-Reynolds-number flows are simulated by solving the Navier-Stokes equations. A finite-difference method with third-order upwinding are employed without using any turbulence model. Validity of this method is discussed.
Also, a newly developed multi-directional formulation is applied for improved accuracy. Examples are presented to show the applicability of the present approach to variety of problems.
Unification of Unstructured Grid-Based Parallel Algorithms for Multidisciplinary Computations
Authors: Shankar Vijaya 
Published: July 2023

Abstract
Computational simulation of complex physical processes encountered in the design of advanced defense and commercial products increasingly requires modeling the complete three-dimensional geometrical details with tens of millions of grid cells to properly capture the physics. Advances in parallel computing, both in hardware and software, now make it feasible to solve such large scale simulations in a timely manner. The objective of this paper is to describe some of the recent work at Rockwell in performing parallel computing for providing quick-turnaround solutions to problems in Computational Fluid Dynamics (CFD), Computational Electromagnetics (CEM) and other computational disciplines.
Diffusion of High Concentrations by Shaking
Authors: Fadda Dani , Raad Peter E. , Bidoae Razvan 
Published: July 2023

Abstract
Shaking a partially filled fluid container causes the free surface of the fluid to deform significantly, indicating the existence of strong flow currents near the free surface. When the fluid is a solvent with a non homogeneous distribution of solute mass, these flow velocities cause convective mixing and significantly enhance the solute mass transfer. This work shows that the effect of shaking on the enhancement of mass transfer is significantly stronger in a region close to the free surface than elsewhere in the tank.
Numerical Model of a Round Buoyant Jet
Authors: Eldredge Tom , Roche James , Hadjerioua Boualem , Mobley Mark 
Published: July 2023

Abstract
A numerical model has been developed to predict the behavior of a buoyant round jet discharging into a quiescent, but thermally stratified ambient. The model has numerous applications for studying jet or plume dilution characteristics. The model has been applied for optimizing surface water pump operation for improving dissolved oxygen (DO) content in hydropower plant releases, without disturbing reservoir bottom sediment. The model predicts velocity, density, and concentration of a conserved species within the jet, and jet radius as a function of the distance from the initial point of discharge.
The model relies on an empirically based function for computing the rate of jet entrainment. Predictions of mean velocity from the one dimensional model were compared to field velocity measurements taken in the jet below a surface water pump with excellent agreement. In addition the predicted penetration depth of the jet was in good agreement with field data.
Simulation of Unsteady Turbulent Jet Flow Using a Localized Dynamic Subgrid Model
Authors: Chakravarthy V. K. , Menon Suresh 
Published: July 2023

Abstract
Large eddy simulations of spatially evolving turbulent jets are conducted using a dynamic one equation model. The study focuses on the aspects of the simulations specific to spatially evolving flows. Spatially evolving shear layers, in the near field, are not fully turbulent. The performance of LES models, derived from the phenomenology of fully developed turbulence, is then in question. The effect of the model under such circumstances is studied. The one equation model while capable of representing the non-equilibrium of the subgrid scales, suffers from the inadequacy that an extra inflow condition for the scalar needs to be specified. This specification could be one of the most significant factors in the simulation. Hence, LES, using realistic turbulent inflow-conditions are compared to simulations without a model to study the effect of the model. It is seen that the model significantly alters the evolution of the flow field. However, it is also seen that the backscatter of energy from subgrid scales to the resolved scales, which is ignored in the present simulations, plays a significant role in evolving flows. The role of backscatter in such flows and the implications of neglecting it in a LES is discussed as a pointer towards future LES research.
A Methodology for Determining Experimental Uncertainties in Regressions
Authors: Brown Kendall K. , Coleman Hugh W. , Steele W. Glenn 
Published: July 2023

Abstract
In this paper a methodology is presented to determine the experimental uncertainties associated with regressions. When a regression model is used to represent experimental information, the uncertainty associated with the model is affected by precision, systematic, and correlated systematic uncertainties associated with the experimental data. The key to the proper estimation of the uncertainty associated with a regression is a careful, comprehensive accounting of systematic and correlated systematic uncertainties. The approach presented in this paper is a continuation of work to develop such a methodology by applying uncertainty propagation techniques to the linear regression analysis equations. The effectiveness of this methodology was investigated and proven using Monte Carlo simulations.
Vortex Breaker Design for a Flue Stack With Swirling Flow
Authors: Boller Shaun M. , Nickerson Robert M. , Eibeck Pam 
Published: July 2023

Abstract
The objective of this project was to design a vortex breaker configuration that would reduce the average yaw angle across the diameter of a flue stack to below the EPA maximum of 20°. A Plexiglas cylindrical wind tunnel was constructed in order to evaluate the effectiveness of a variety of vortex breaker designs. A tangential-type swirl generator was fabricated to induce swirling flow which was strongest at the cylinder wail in the wind tunnel and therefore simulated swirl conditions in the flue stack. Nine different vortex breaker configurations were tested and compared using the deflection angles of floss fastened to the cylinder wall, allowing quantification of the yaw angle of flow. Swirl intensities were measured for each breaker configuration at locations x/d = 6, 8.7, 9.4, 14.6, and compared with swirl intensity at these locations without the presence of a vortex breaker. Results indicated that vortex breaker effectiveness was a function of both breaker length and the number of breaker fins. A five-hole pressure probe was used to verify results for four optimum breaker designs and it was determined that the flow visualization results were accurate. Due to its cost-effectiveness, a four-fin L/d = 1 breaker was installed in the flue stack. Preliminary testing with cold flue gas resulted in an average yaw angle of 0° across the diameter of the flue stack.
Damage Evolution and Progressive Failure in Composite Material Highway Guardrails
Authors: Gentry T. Russell , Bank Lawrence C. , Yin Jiansheng , Lamtenzan J. Daniel 
Published: July 2023

Abstract
The evolution of damage and the progressive failure of prototype highway guardrails, constructed of thermoset plastic /E-glass composite materials, is described. The composite material guardrails are being studied as potential replacements for conventional steel w-beam guardrails. The objective of this phase of the study was to investigate progressive failure of composite cross-sections as a means of dissipating energy in the guardrail when subjected to a vehicular impact. The prototype rails were connected to standard steel blockouts and tested quasi-statically under displacement control. The blockouts were designed to allow local rotation of the blockouts and large deflection of the guardrail sections so as to develop a tension field in the rail following the initial “local damage phase.” The results of the static tests on the composite rails were compared with those of a standard steel w-beam tested in the same fixture. From the quasi-static tests the evolution of the local damage and the progressive failure in the composite prototype rails could be observed. Observed changes in failure modes at different load levels could be correlated with discontinuities in the load-deformation data obtained during the testing. A study of the energy absorbed during the initial flexural damage phase (prior to the tension field developing in the rail) revealed the relative contribution of this phase to the overall energy absorbed during the progressive failure of the rail. From this preliminary study it appears that composite material guardrails may be able to dissipate more energy in the initial flexural phase than conventional steel w-beams.