bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Model of a Coupled Structural System Connected by Active/Passive Springs
Authors: Hwang Y. F. , Louie L. 
Published: July 2023

Abstract
A mathematical model of a coupled structure, consisting of two main structures connected by an arbitrary number of compliant elements (the passive springs) and a number of actuators (the active springs), was formulated. Due to size and weight considerations, this system utilizes active springs instead of conventional reaction mass actuators. Active springs, while they generate a force to reduce vibration on one structure, also exert a reaction force on the other connected structure. Solutions are based upon the formalism of Lagrange’s equations using the normal modes of the uncoupled structures as the generalized coordinates. The constraints by the compliant elements and supports are enforced by Lagrange multipliers. A numerical example is given for the case of two beams connected by a set of springs with one beam elastically supported. Results are compared with those obtained from a finite-element analysis and predictions are in a good agreement.
Analysis of Data From Single-Row Heat Exchanger Experiments Using an Artificial Neural Network
Authors: Díaz Gerardo , Yanes José , Sen Mihir , Yang K. T. , McClain Rodney L. 
Published: July 2023

Abstract
Experimental data obtained from tests relating to two different single-row heat exchangers are analyzed by means of an artificial neural network. The experiments are carried out by using hot water and room-temperature air as the rn-tube and over-tube fluids, respectively. The two heat exchangers are similar in the air side but with different water-side circuiting. The data obtained consisted of values for the flow rates, the inlet temperatures, and outlet temperatures for both fluids. Data analysis was through a neural network program written using the generalized-delta back-propagation algorithm. Through a random selection process, 75% of the experimental runs are chosen for training and 25% for testing. Flow rates and the inlet temperatures for both water and air are used as the input data for the neural network, and the heat transfer rates are the output. Once the neural network was trained, the values of the heat transfer rates for the test data are predicted. The predictions are compared with the actual measurements, and with the results of a linear interpolation procedure.
Application of Recursive Neural Networks to Six Degree-of-Freedom Simulation of an Experimental Model Undergoing Severe Maneuvers
Authors: Faller William E. , Smith William E. , Huang Thomas T. 
Published: July 2023

Abstract
Recursive neural networks (RNN) have been applied to six degree-of-freedom (6-DOF) simulation of an experimental radio controlled model undergoing severe 6-DOF maneuvers. The inputs to the RNN were the time-varying control signals (plane deflection angles, propeller RPM). The required outputs were the time-varying 6-DOF vehicle dynamics [u(t), v(t), w(t), p(t), q(t), r(t)]. The vehicle accelerations, Euler angles and trajectories were also calculated throughout the maneuver. The results showed that all variables (accelerations, velocities, angles and displacements) were accurately predicted throughout the entire maneuver. Further, all maneuvers could be accurately predicted over any time period during which the control inputs were a known function. The results also clearly showed that the RNN 6-DOF simulation generalized to severe maneuvers not used in the development process.
Active Control of Gaseous Systems: A Fuzzy Logic Approach
Authors: Kiriakidis Kiriakos , Tzes Anthony , Vradis George 
Published: July 2023

Abstract
The active control problem of gaseous systems is addressed in this article. The objective is to regulate gas velocity, at particular locations within the system, so that appropriate mass flow rate is achieved. The dynamics describing the system, using modal expansion, reduce to a finite set of ordinary differential equations. Due to variations of the gas properties with operating conditions, there exists parametric uncertainty in the obtained reduced-order model. To overcome the problem of estimating the model parameters or the extent of the parametric uncertainty, a variable structure controller is proposed. This controller utilizes a fuzzy logic rule base for on-line adjustment of the switching gain. The fuzzy rules create an adaptive law and tune this gain to the smallest value that verifies the sliding condition. Experimental results demonstrate the performance of the suggested mass flow rate control scheme, tested on a prototype air handling unit.
Laminar Flow Control With Neural Networks
Authors: Herbert Thorwald , Fan Xuetong , Haritonidis Joseph H. 
Published: July 2023

Abstract
Conventional laminar-flow control (LFC) techniques aim at delaying transition by modifying the highly energetic mean flow toward increased stability. These LFC systems require considerable power, and the open-loop control is difficult to optimize or adapt to varying flight conditions. We perform conceptual studies on a “smart wall” which consists of an array of basic control units flush mounted on aerodynamic surfaces. Each control unit integrates sensors, actuator, neural networks, and training algorithms for adaptive control of instabilities. We have developed a computational procedure for the design of control units and have demonstrated the suppression of TS waves and wave packets in wind tunnel experiments. Mass-manufactured in silicon, the smart wall appears as a promising alternative to current LFC techniques.
A Stabilized Finite Element Formulation of the Navier-Stokes Equations for Fluid-Structure Interaction
Authors: Masud Arif 
Published: July 2023

Abstract
This paper presents a space-time finite element formulation of the Navier-Stokes equations, stabilized via the Galerkin/least-squares method. The variational equation is based on the time discontinuous Galerkin method and is written in terms of the physical entropy variables. This formulation is analogous to the arbitrary Lagrangian-Eulerian technique and thus is applicable to fluid-structure interaction problems. Free surface oscillation of a liquid filled tank is presented to show the performance of the proposed method.
Natural Circulation Flow Rates for a Non-Jet Pump Boiling Water Reactor
Authors: Choe Hwang , Sadeghi Nader 
Published: July 2023

Abstract
Natural Circulation provides cooling flow to the reactor core in Boiling Water Reactors (BWR) for those events when mechanical pumps are not available. However, natural circulation flow regime is at lower end of core flow, and not much study has been performed in the past. A transient behavior of reactor core flow in a non-jet pump BWR during a recirculation pump trip and pump runback event is studied by TRACG analysis. An analytical expression for the natural circulation flow is obtained for the recirculation pump trip event with three, four, and five recirculation loops open. The natural circulation flow rates predicted by the analytical expression agree with those predicted by TRACG code within 0.2 %.
Transient Analysis for Compressible Fluid Flow in Transmission Line by the Method of Characteristics
Authors: Sim W. G. , Choi C. Y. 
Published: July 2023

Abstract
Transient analysis for compressible fluid flow has been conducted to evaluate the dynamic characteristics of dead-ended or volume-terminated transmission lines following a sudden pressure change at its entrance. The acoustic waves due to compressibility of fluid might be generated by the sudden pressure change. The two partial-differential equations, based on the conversion of mass, energy and momentum, were derived for the one-dimensional adiabatic compressible flow with friction and entrance head loss. The governing equations describing the present transient-state flow are hyperbolic, partial differential equations. The boundary conditions involve a fixed volume termination at the exit and include sinusoidal disturbance in the sudden pressure change at tube entrance. The method of characteristics is used to transform the partial differential equation into the particular total differential equations, which can be integrated along the characteristic lines. The present results show good agreement with the existing results. The effects of tube length, tube diameter and end volume are evaluated.
On Matching Numerics and Physics in Applying CFD-Based Methods to Diverse Fields
Authors: Chakravarthy Sukumar R. 
Published: July 2023

Abstract
Computational Fluid Dynamics (CFD) has been a subject of focused research for the last three decades in the aerospace community. It has also received substantial attention in automotive application areas. The primary research driver has been the former because of available funding profiles. CFD technology available today is increasingly being applied to new areas partly due to the push for commercialization and partly due to changing funding distribution. Along with the scientific excitement and potential benefits of such use, one must exercise caution and be aware of cross-disciplinary issues. This paper attempts to qualitatively enumerate issues to be concerned about when considering the application of CFD-based methods to new areas.
Large Eddy Simulation of a Jet in Crossflow
Authors: Yuan Lester L. , Street Robert L. 
Published: July 2023

Abstract
Results from large eddy simulations of a round jet issuing into a laminar crossflow are presented. The flow reproduces all of the coherent vortical structures observed in experiment. The counter-rotating vortex pair commonly observed in these flows is revealed to be a result of the time averaging of discrete parcels of vortical fluid. The generation of wake vortices is observed in the jet near field. Mean flow results agree reasonably well with experiment, and the effects of several common simplying boundary conditions are examined.
A Methodology for Computing the Uncertainty of Curve Fitting Parameters Interpolating Experimental Data
Authors: Antohe B. V. , Lage J. L. 
Published: July 2023

Abstract
A general procedure to determine the experimental uncertainty of parameters obtained directly from equations curve fitting experimental data is presented. The procedure, valid for any curve fitting equation, is used for estimating the uncertainties of permeability and inertia coefficient characterizing the hydraulic behavior of mechanically compressed aluminum porous matrices. These parameters, to be obtained experimentally since predictive models do not exist, are frequently determined by extrapolation of the experimental pressure drop versus fluid speed data to asymptotic regimes. In this case the results are rigorously valid only at the asymptotes and their uncertainties are independent of the curve fitting uncertainty. We propose here a new methodology for determining the permeability and inertia coefficient of porous media based on the curve fitting of the experimental results without using extrapolation. This methodology is found to yield more consistent and accurate results than existing methods because the parameters are valid now throughout the entire experimental range. The corresponding uncertainties, calculated following a prescribed scheme, are no longer local but global because they are affected by the uncertainties of each and every experimental data point via the curve fitting equation.
Effect of Flow Misalignment and Multi-Hole Interaction on Boundary-Layer Bleed Hole Flow Coefficient Behavior
Authors: Davis David O. , Grimes Marcus , Schoenenberger Mark 
Published: July 2023

Abstract
The effect of flow misalignment on the flow coefficient behavior of a 20° boundary-layer bleed hole and the effect of the interaction between two 90° bleed holes separated by two hole diameters on flow coefficient behavior has been studied experimentally. Both tests were run at freestream Mach numbers of 0.61, 1.62 and 2.49. The flow misalignment study was conducted over a range of 0 to 30°. The results show that neither flow misalignment nor hole interaction has much effect on the flow coefficient for the subsonic case. For the supersonic cases, flow misalignment causes significant degradation in the performance of the slant hole. For the supersonic normal hole interaction cases, depending on the hole orientation, either an increase or decrease in overall flow coefficient was observed. The largest change in flow coefficient, 6% increase at near choke conditions, occurred when the holes were oriented in line with the flow direction.
Simulation of the Inlet Flow of a Centrifugal Compressor Impeller With and Without a Spinner
Authors: Xi G. 
Published: July 2023

Abstract
This paper, based on a multi-purpose CFD code, presents a numerical method which can exactly model the actual spinner attached to the inlet of the experimental high-speed centrifugal compressor impellers. The inlet flow fields of the impeller with and without a spinner are numerically simulated and compared. The results indicate that the modelling of the actual spinner with a cylindrical surface does considerably change the inlet flow field of the impeller near the hub in the first half of the inlet. However, this influence is rapidly diminishing along the flow into the blade passage, and it does not bring a considerable deviation when comparing the calculated velocities with the data inside the blade passage.
Thermal Analysis of Compact Electronic Equipment With Cooling Fan
Authors: Hisano Katsumi , Iwasaki Hideo , Ishizuka Masaru , Makita Sadao 
Published: July 2023

Abstract
This paper describes thermal analysis of compact electronic equipment. A numerical analysis was carried out on the basis of thermal conduction treatment for the whole domain of a subnotebook personal computer with a cooling fan. In this work, numerical analysis based on finite volume method was employed to estimate the temperature distribution of the PC. To treat the air flow caused by the fan inside the cabinet, lump model was used in addition to the thermal conduction model. The numerical model includes Si chips, packages, printed wiring boards, casing, etc. Temperature rise of LSI packages obtained by the thermal analysis showed a good agreement with the measured values.
Thermal Control Subsystem Design for the Avionics of a Space Station Payload
Authors: Moran Matthew E. 
Published: July 2023

Abstract
A case study of the thermal control subsystem development for a space based payload is presented from the concept stage through preliminary design. This payload, the Space Acceleration Measurement System II (SAMS-II), will measure the acceleration environment at select locations within the International Space Station. Its thermal control subsystem must maintain component temperatures within an acceptable range over a 10 year life span, while restricting accessible surfaces to touch temperature limits and insuring fail safe conditions in the event of loss of cooling. In addition to these primary design objectives, system level requirements and constraints are imposed on the payload, many of which are driven by multidisciplinary issues. Blending these issues into the overall system design required concurrent design sessions with the project team, iterative conceptual design layouts, thermal analysis and modeling, and hardware testing. Multiple tradeoff studies were also performed to investigate the many options which surfaced during the development cycle.
Application of the Pin-Fin Heat Sink to Electronic Equipment [Study on Design Method for Flow-Guide Vanes]
Authors: Minakami Ko , Hisano Katsumi , Iwasaki Hideo , Mochizuki Sadanari 
Published: July 2023

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

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

Abstract
A proposal for collision mitigation is investigated in this paper. Two intelligently controlled hvdraulic cylinders is proposed to be extended prior to collision and absorb impact energy upon engagement with the other body. Feasibility and performance of collision mitigation were investigated with a simulation of the collision dynamics. Two phases of control were considered; pre-collision control and collision control. Various collision scenarios have been studied with view of predicting collision and proposing a pre-collision control strategy for activating the proposed hydraulic bumper. A learning digital computer pre-collision control is proposed.
For the purpose of this research a 0.5 m stroke hydraulic cylinders is used to act as an effective extension of the crash zone. A specially adapted fast response hydraulic flow control valve is proposed with certain collision control law. The collision control law aims at controlling the collision force at a given level corresponding to occupants acceleration not exceeding 20g. Simulation results revealed a maximum level of 15g deceleration could be achieved in a 30 mph collision.
Experimental and Theoretical Study on Heat Transfer of an Impinging Plasma Jet
Authors: Ogawa Kuniyasu , Hijikata Kunio 
Published: July 2023

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

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

Abstract
A computational study of the temperature and flow fields of solidifying Cd1-xMnxTe in a vertical Bridgeman furnace is conducted. Influence of furnace temperature profile, pulling velocity, Grashof number Gr, Prandtl number Pr, ratio of thermal to liquid conductivity Kl/Ks, and Stefan number is examined. Convection consistently causes an undesirable convex interface (as seen from the solid). The solid liquid interface is found to be sensitive to only the temperature profile and Kl/Ks. The flow field is significantly affected by Kl/Ks, the furnace temperature profile, and Gr. Due to the pseudo state model employed, the pulling velocity shows little effect for the parameter values of this study.
The flow is bicellular, with a strong upper cell (caused by the particular furnace temperature profile) and a weak lower cell (caused by the inequality of Kl and Ks). These cells are competitive, with the upper cell often absorbing the lower one. When the lower cell is present the interface is more convex. At high Gr, the flow is bicellular with mass transport between the two cells occurring by diffusion.
Simulation and Measurement of a Vertical Bridgman Growth System for β-NiAl Crystal
Authors: Ouyang H. , Shyy W. , Levit V. I. , Kaufman M. J. 
Published: July 2023

Abstract
A coordinated theoretical and experimental study of the temperature distributions inside a customized vertical Bridgman system for growing β-NiAl crystal has been conducted. This model accounts for the combined effects of phase change dynamics, coupled heat transfer processes of conduction, convection and radiation, variable material properties, and complex geometry pertaining to the system. Comparisons between numerical predictions and experimental measurements show satisfactory agreement. Important processing parameters such as interface curvatures and temperature gradients across the interface, along with possibilities of improving the solidification process have been explored.