bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling and Performance Comparison of a Refrigerant Cooled Liquid Desiccant Absorber With a Conventional Refrigerant Cooled Cooling Coil
Authors: Khan Arshad Y. , Robles Eliud , Sulsona Fernando J.
Published: July 2023

Heat and mass transfer performance of a non-conventional cooling and dehumidification system using a refrigerant cooled liquid desiccant absorber (RCLDA) employing ammonia as a refrigerant over a conventional refrigerant cooled cooling coil (RCCC) also using ammonia as a refrigerant is compared in this paper. Analytical models describing the heat and mass transfer in both the conventional and a non-conventional system are developed for this purpose. The study reveals that the performance of an RCLDA depends more on the evaporator temperature than on the refrigerant to air mass flow rate ratio for high values of the mass flow ratio, but for low values of the mass flow rate ratio a strong dependence on both parameters is predicted. Similar results are predicted regarding the performance of an RCCC. As opposed to the performance prediction of an RCCC, it is found that the deterioration in the cooling and dehumidification performance of an RCLDA takes place relatively more slowly. Furthermore, it is concluded from this study that the cooling and dehumidification performance of an RCLDA system is better than an RCCC system for evaporator temperatures and refrigerant mass flow rates of greater than 10°C and 0.50 respectively.
Impact of Natural Gas Substitution and Utility-Based Cogeneration for Industrial Process Heating
Authors: Rosen M. A. , Sy E. , Gharghouri P.
Published: July 2023

Significant benefits in the form of reduced energy use and related emissions are shown to be possible in the province of Ontario, Canada by (i) substituting natural gas heating for electric heating, and (ii) implementing utility-based cogeneration, using the facilities of the main provincial electrical utility, Ontario Hydro, to satisfy some of the needs for industrial process heating in the province. Examinations of a wide range of practical substitution levels shows the greatest benefits from substitution to be realized in the utility sector, where marked reductions occur in coal and uranium use. Two cogeneration scenarios are assessed, which assume implementation of utility-based cogeneration to satisfy minor or major portions of the heat demands of the industrial sector, and which show that cogeneration can provide significant technical, economic and environmental benefits to the province and its electrical utility. The results are most likely to be useful to the developers and designers of energy systems, and to decision makers on energy planning and policy.
Loss of Residual Heat Removal System Simulation Using CATHARE Thermal Hydraulic Code
Authors: Troshko A. A. , Hassan Y. A.
Published: July 2023

Thermal hydraulic CATHARE V1.3U code has been used to simulate an International Standard Problem (ISP38) experiment conducted at BETHSY Integral Test Facility located in Grenoble, France.

This experiment dealt with simulation of the loss of Residual Heat Removal System (RHRS) during midloop operation. It involved opening of the pressurizer manway and steam generator outlet plenum manway simultaneously with switching on the heating rods power simulating loss of RHRS. The total power was kept unchanged with the level 138 kW throughout the test. Mass discharge through both manways led to core boiling and uncovery. Test was stopped when the primary cooling system was filled back to a midloop level.

Overall, the code’s prediction and experimental data were found to be in a reasonable qualitative agreement. However, the code underestimated the time of the core uncovery and the actuation of the gravity feed injection due to the ovepredicted mass discharge through steam generator manway during the initial stage of the transient. This was caused by CATHARE’s miscalculation of the phase separation effect at the hot leg/surge line tee junction and significant water entrainment into the surge line at the beginning of the test. It was found that the code’s model of the upward tee junction needs to be refined for the low pressure ranges.
Stratification in Nuclear Reactor Components
Authors: Randorf J. A. , Hassan Y. A.
Published: July 2023

Several experiments have recorded loop stratification at a recent test performed at the Rig of Safety Assessment (ROSA) project at the Japanese Atomic Energy Research Institute’s Large Scale Test. This facilty (LSTF) is used for for the advanced nuclear reactor AP600 simulation. Prediction of stratification in reactor coolant loops is of interest during accident conditions. The present study attempts to develop the criteria for stratification in the coolant loops based on data from the LSTF experiments. The first criteria was developed for addressing injection-induced stratification. The second criteria applies to downcomer/cold leg junction stratification. Both criteria provided predictions consistent with LSTF data.
An Analytical Study of Investment Casting With Webbed Epoxy Patterns
Authors: Yao W. L. , Wong H. , Leu M. C. , Sebastian D. H.
Published: July 2023

We describe in this paper a finite element analysis (FEA) study to analyze the stresses in the ceramic shells and epoxy patterns that are induced by the thermal expansion of the patterns in investment casting. Because it is computationally prohibitive to perform FEA of the stresses due to the thermal expansion of a complex pattern with an internal web structure, we devise a method which replaces the effect of the internal web structure by a set of forces exerting on the skin of the pattern. These forces are simply estimated from the web geometry and the heating temperature. The validity of this method is verified by comparing the FEA results using this technique and the FEA results obtained with exact web structure patterns. Also discussed are the effect of web geometry and location on thermal stresses and buckling of the web structure.
Adaptive Regulation of Thermal Desktop Manufacturing Methods
Authors: Doumanidis Charalabos C. , Fourligkas Nikolaos
Published: July 2023

In this paper, thermal feedback control techniques are applied to regulate the distributed-parameter, dynamic nonlinear heat transfer phenomena involved in thermal rapid prototyping processes. These mechanisms are captured in a numerical simulation of the thermal field generated during such operations. For the design of a multivariable controller, a linearized state-space model of lumped temperatures and heat inputs on a grid is established, and its parameters are identified in-process. The controller gains are adapted in real time and the torch power and motion is driven on a trajectory optimizing the thermal actuation. This control strategy is validated both by simulation and by experiment in a laminated object manufacturing operation, using a plasma-arc torch modulated through temperature feedback from an infrared camera.
Determination of Flat-End Cutter Orientation in 5-Axis Machining
Authors: Deng Zhongping , Leu Ming C. , Wang Liping , Blackmore Denis
Published: July 2023

Implementation of the method of finding flat-end cutter orientation based on slope and curvature matching for 5-axis NC machining is studied. The full advantages of 5-axis machining are exploited by considering the cutter’s inclination and yaw capability and the local differential geometric features of a designed surface. The machining error, or cusp height, is derived for two machining scenarios. An algorithm is developed which computes the cutter orientation by matching the slope and curvature of the surface at each discretized point while minimizing the machining error and satisfying constraints on both inclination and yaw angles.
Rapid Prototyping of Control Software for Automated Manufacturing Systems Using Supervisory Control Theory
Authors: Qiu Robin G. , Joshi Sanjay B.
Published: July 2023

Supervisory control (SC) theory, coupled with the TCT modeling package (Wonham, 1994), is theoretically powerful and practically useful. However, due to the lack of an efficient method to transform the SC model into operational control logic, this theory has found limited applications in manufacturing. This paper presents a method to rapidly prototype operational control software for an automated manufacturing system using SC theory. Given the control specification of a manufacturing workcell, an SC model can be developed using the TCT package. By transforming the SC model into an MPSG-based model (Smith, 1992), the modified MPSG builder can generate the corresponded control logic in the form of C++ source codes. After the equipment-level control and information handler functions are inserted into the control logic, an executable computer-based controller on the shop floor can be immediately compiled.
The Effect of Stencil Printing Optimization on Reliability of CBGA and PBGA Solder Joints
Authors: Li Y. , Mahajan R. L. , Subbarayan G.
Published: July 2023

As a follow-up and conclusion to previous work in stencil printing process modeling and optimization (Li et al., 1996), we investigate the effect of stencil printing optimization on the reliability of the ceramic and plastic ball grid arrays. For ceramic ball grid arrays, the eutectic solder fillet shape is calculated using a series of simple mathematical equations. The thermal strain distributions within the solder joints after two cycles of accelerated thermal cycling test are estimated using three-dimensional finite element models. The modified Coffin-Manson relationship is applied to calculate the mean fatigue lives of the solder joints. The results reveal that an optimized stencil printing process significantly reduces variation in the fatigue life of ceramic ball grid arrays. The results also show that the fatigue life of ceramic ball grid arrays is very sensitive to the card-side solder volume. The maximum strain region shifts from the card-side eutectic solder to the module side as the card-side eutectic solder volume increases. This shift in maximum strain suggests that there exists an optimum ratio between the card-side solder volume and the module-side solder volume for the reliability of a given ceramic ball grid array design. The implications of this for the package developers and users are discussed. The calculations indicate that the fatigue life of plastic ball grid arrays is almost insensitive to the card-side solder volume.
Design and Simulation of an Entry Edge Guide Control System for Tandem Cold Mills
Authors: Guo Remn-Min , Loen Mark V.
Published: July 2023

A new entry edge guide control system for cold mills was designed using a dual-mode control system. One control loop regulated the cylinder pressure to prevent machine damage due to pressure surge while the other loop provided strip edge guide position control. The target control level was ±1.59mm accuracy for a maximum operating strip speed with coil sidewall variances of ±12.5mm/sec.

A mathematical model was developed to simulate the dynamic behavior of the control system using the state space design method. The control system features two PID controllers, two hydraulic proportional valves, and a digital edge sensor. The PID tuning constants and the hydraulic proportional valves were specified by simulation results considering system response and signal noise. Data from 35 coils was used to investigate control performance. The results show that the average standard error is entirely acceptable. The majority of the coils are expected to have tracking errors less than the required accuracy.
The Development of Process Models for Use With Global Optimization of a Manufacturing System
Authors: Gunasekera Jay S. , Fischer Christian E. , Malas James C. , Mullins William M. , Yang Michael S.
Published: July 2023

This paper addresses the development of a system which will enable the optimization of an entire manufacturing process sequence. Typically such a sequence may involve several stages and alternative routes of manufacturing a given part. It is important that such a system be optimized globally, (rather than locally, as is the current practice) in order to achieve improvements in affordability, producibility, and performance. This paper demonstrates the development of a simplified forging model, an ordinal optimization technique for searching and reducing a very large design space, and an objective function to evaluate the cost of a design sequence.
Form Tolerance Estimation Using Jackknife Methods
Authors: Shao Jun , Tsui Kwok-Leung
Published: July 2023

A coordinate measuring machine (CMM) is a computer controlled device that uses a programmable probe to obtain measurements on a part surface. Recently CMMs have become very popular for dimensional measurement in industry due to their flexibility, accuracy, and ease of automation. Despite the advantages offered by CMM’s, problems have emerged with their use because tolerance standards require knowledge of the entire surface while a CMM provides only a sample of points on the surface. These problems could be quite challenging, and both practitioners and researchers have shown great interest.

Among these problems, estimating form tolerances for different part features is very important to practitioners. The least squares and minimum zone methods are the most commonly used methods for form tolerance estimation. Dowling et al. (1996a) show that these two methods give seriously biased estimates of the part deviation range when the sample size is small. This paper proposes several jackknife estimates that correct the bias of the least squares and minimum zone estimates. Based on a simulation study, it is found that the jackknife estimates effectively reduce the bias of the two common estimates in many situations, and thus reduce the chance of accepting bad parts in tolerance verification.
Time-Frequency Distribution and Nonlinear Model-Based Virtual Torsional Vibration Sensor for Milling Insert Wear Assessment
Authors: Li C. James , Tzeng Tzong-Chyi
Published: July 2023

This study establishes the utility of torsional vibration, time-frequency analysis, and neural networks for on-line estimation of the extent of flank wear in a milling insert. First, a time-frequency distribution, i.e., a Choi-Williams distribution, is calculated from the torsional vibration of a milling machine spindle. Second, scattering matrices and orthogonalization are employed to identify the time-frequency components that are best correlated to the extent of wear. Third, a neural network is trained to estimate the extent of wear from these critical time-frequency components. To reduce the cost of the system, a nonlinear model-based virtual sensor is developed to eliminate the need for a permanent torsional vibration sensor, which is more expensive and bulky than the translational vibration sensor. Experimental results have shown the usefulness of the proposed solution.
Multi-Spindle Drilling Process Condition Monitoring and Fault Diagnosis
Authors: Gu S. , Ni J.
Published: July 2023

A multi-spindle drilling process is often used in auto industries, e.g., in engine block and transmission case manufacturing. Condition monitoring and fault diagnosis for the multiple spindle drilling process is very important. Although extensive research has been done on drilling process monitoring and diagnosis, relatively little research deals with the multiple spindle drilling process. Because of the nature of the multiple spindle drilling operation, the approach used for single spindle drilling process monitoring and diagnosis cannot be directly applied for multiple spindle drilling cases. In this paper, a force sensor will be used for multi-spindle drill wear condition monitoring, while a vibration sensor will be used for the drill wear fault diagnosis (detecting a worn drill location). Experimental results show that they are effective for the monitoring and the diagnosis, respectively. In this paper, a multiple fault classification method, called Recursive Optimal Pairwise Linear Discriminant Function (RO-PLDF), is implemented for the fault classification. The success rate of locating a worn drill position by this approach can be as high as 100% with a trained diagnostic model.
Simultaneous Analysis of Products and Orders in Storage Assignment
Authors: Amirhosseini Michael M. , Sharp Gunter P.
Published: July 2023

This research focuses on non-traditional analysis of products in an order processing environment. The approach is different from an ABC analysis whereby more popular and fast moving products are assigned to the most accessible storage locations. In Simultaneous Analysis of Products and Orders in Storage Assignment, a generalized correlation measure is introduced that will look at the degree to which two or more products together fill warehouse or customer orders. The motivation behind this idea is the intuitive understanding that by grouping products according to the degree to which orders are satisfied, the overall distance during order-picking will be decreased, hence increasing order-picking productivity. This order-satisfying correlation measure is contrasted against other popular correlation measures in creating hierarchical clusters or groups of products. A specially-developed cluster analysis software is then used in obtaining various product correlation measures, in creating nested product clusters, and in performing the necessary analyses.
Two-Dimensional Stress Analysis of Single-Lap Joints of Dissimilar Adherends Subjected to External Bending Moments
Authors: Sawa Toshiyuki , Nakano Katsuyuki , Ratani Hiroshi To
Published: July 2023

The stress distributions of single-lap adhesive joints of dissimilar adherends subjected to external bending moments are analyzed as a three-body contact problem by using a two-dimensional theory of elasticity (plain strain). In the analysis, dissimilar adherends and an adhesive are replaced by finite strips, respectively. In the numerical calculations, the effects of Young’s modulus ratio, adherend thickness ratio and adherend length ratio on the stress distribution at the interface are examined. As the results, it is seen that the stress singularity occurs at the edges of the interfaces and it increases at the edge of the interface of adherend with greater Young’s modulus It is noticed that the singular stress decreases at the edge of the interface of adherend with larger adherend thickness. Strain measurements on adherends were conducted. A fairly good agreement is seen between the analytical and the measured results.
Relative Index Method for Nonlinear Strain Analysis of Piezoceramic Sensored Structure
Authors: Lin Y.-J. , Lee T. , Saravanos D.
Published: July 2023

In this paper, a relative index method is proposed to analyze the nonlinear Von Karman strain effects on the piezoceramic sensored rotor blades. Although other qualitative and quantitative methods are available for nonlinear strain analysis, these methods have inherent drawbacks. For qualitative method the fuzzy terms such as severe, negligible influence, etc., are usually used to describe the effect. The main disadvantage of using these terms is that to different people the same fuzzy word can be interpreted differently. This causes inconsistency which may lead to inaccurate analysis. For quantitative methods, the major disadvantage is that they are unable to delineate the whole picture of the nonlinear effects. However, the proposed relative index method circumvents the drawbacks of both qualitative and quantitative methods. Firstly, it measures the nonlinear effect and converts it into a numerical value. The value is in the range of zero to one in which zero is corresponding to negligible effects and one indicates the highest severity of the nonlinear effects. In addition, to generate the index value this method takes the whole picture of nonlinear effect response into consideration.

The results of using the relative index method show that at any given mode of vibration the nonlinear effect on sensor is relatively negligible at high rate of rotation than that on lower ones. The results also indicate that the nonlinear effect is increasing at lower modes of vibration but its effect on sensor almost levels off at higher modes. Moreover, if comparing index value of a given modes of vibration with the index value of its preceding modes, the effect of nonlinearity is decreasing. In addition, the results also suggest that at any given instantaneous speed of rotation the level of the nonlinear effect is diminishing with the higher acceleration/deceleration rate of operation of the blade.
Design and Fabrication of the Fundamental Components Integrated to Realize a Functional Silicon Micromachined Gas Chromatography System
Authors: Kolesar Edward S. , Reston Rocky R.
Published: July 2023

A miniature gas chromatography (GC) system has been designed, fabricated and developed using modem silicon micromachining and VLSI circuit processing techniques. The GC system is composed of a miniature sample injector that incorporates a 10 μ1 sample loop; a 0.9 m long, rectangular-shaped (300 μm width and 10 μm height) capillary column coated with a 0.2 μm thick copper phthalocyanine (CuPc) stationary phase; and a dual-detector scheme based upon a CuPc-coated chemiresistor and a commercially available, 125-μm diameter thermal conductivity detector (TCD) bead. Silicon micromachining was employed to fabricate the interface between the sample injector and the GC system’s column, the GC system’s column itself, and the dual-detector cavity. A novel integrated circuit thin film processing technique was developed to sublime the CuPc stationary phase coating on the GC system’s column walls micromachined in the host silicon wafer substrate and the Pyrex® cover plate which are subsequently electrostatically bonded together. The CuPc-coated chemiresistor was designed and fabricated using conventional VLSI circuit processing techniques. The miniature GC system has demonstrated the capability to directly and completely separate parts-per-million (ppm) ammonia and nitrogen dioxide concentrations when isothermally operated (55–80°C). With a helium carrier gas and nitrogen diluent, a 10 μl sample volume containing ammonia and nitrogen dioxide injected at 40 psi can be separated in less than 30 minutes.
High Performance Power Converters: An Engineering Systems Approach
Authors: Bartlett Edward L.
Published: July 2023

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

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

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

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

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

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

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

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

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.
Applications of Fuzzy Logic and Neural Networks to Identification and Control Problems in Fluid Mechanics
Authors: Tzes Anthony , Borowiec Joseph
Published: July 2023

This article presents a survey of the current literature on recent conference and journal articles related to applications of fuzzy logic and neural networks to identification and control problems in fluid mechanics.
Application of Neural Networks to the Control of Burgers Equation With Random Forcing
Authors: Cho Yongseung , Agarwal Ramesh K. , Tupe Yogesh
Published: July 2023

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

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

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

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

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

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

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

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

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

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

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.
Validation of a Non-Linear Finite Element Vehicle Model Using Multiple Impact Data
Authors: Zaouk Abdullatif K. , Bedewi Nabih E. , Kan Cing-Dao , Marzougui Dhafer
Published: July 2023

A detailed multi-purpose finite element model of a 1994 Chevrolet C-1500 pick-up truck was developed at the FHWA/NHTSA National Crash Analysis Center. The model is the first of its kind developed specifically to address vehicle safety issues, including front and side performance, as well as road side hardware design. The former application typically involves large regional deformation with impact durations of no more than 150 msec. The latter encompasses damage along a larger portion of the vehicle, and due to longer interaction time between the vehicle and impacted device coupled with the need to observe post impact dynamics, requires simulations that could last as long as 1 second.

This paper describes the results of a non-linear finite element computer simulation using this model for frontal full barrier and median highway barrier impacts. These simulations are conducted in support of research studies undergoing at the National Highway Traffic Safety Administration (NHTSA) and the Federal Highway Administration (FHWA) to investigate vehicle compatibility, new offset barrier tests, and highway/vehicle safety issues. Full scale vehicle crash tests conducted by NHTSA and FHWA are used for evaluation of the performance of the model. Two tests are compared, a frontal impact with a full rigid wall and a corner impact to a 42-inch Vertical Concrete Median. The comparisons between tests and simulations in terms of overall impact deformation, component failure modes, velocity and acceleration at various locations in the vehicle are presented. Modeling issues including element size, connectivity, and slide line interface of different parts are discussed. In addition, some simulation related hardware and software issues are addressed. The results clearly indicate the model to be consistent with the full scale tests. Additional simulations need to be performed to fully evaluate and validate the model.
Non-Steady-State Gas Dynamical Process of a Laser Supported Wave Formation in Free Gas Flow
Authors: Surzhikov Sergey T.
Published: July 2023

A non-steady-state problem concerning subsonic stage of low-temperature plasma jet formation in laser supported waves in air of atmospheric pressure is considered. The low-temperature plasma is sustained by CW CO2 laser radiation focusing near a surface through which an air of atmospheric pressure is blowing.

Two-dimensional radiative-gasdynamical model is presented. The model consists of Navier-Stokes equations, conservation energy equation, selective radiative heat transfer equation and CO2-laser radiation transfer equation. The real temperature dependence of air thermophysical and optical properties are taken into account.

Numerical results of computational simulation of the phenomena are presented. A numerical solution with vortex gas dynamical structure inside laser supported plasma is obtained.