bluuebunny/crossref_metadata_2025 huggingface dataset:
Knowledge Intensive Maintenance and Soft Machines: New Approaches Toward Advanced Maintenance
Authors: Tomiyama Tetsuo , Umeda Yasushi , Sakao Tomohiko , Shimomura Yoshiki
Published: July 2023

Maintenance is one of the least automated areas in a product life cycle. This paper proposes the concepts of knowledge intensive maintenance and soft machines to address this issue.

Knowledge intensive maintenance is an applied concept of knowledge intensive engineering, which aims at generating more added-value with intensively accumulated life cycle knowledge, to maintenance. It even includes upgrading, reconfiguring, and renewing activities into maintenance. Soft machines aim at yielding more added-value such as longer life, easy maintainability, and robustness against faults through reconfiguration, self-maintenance, and self-organization, based on design concepts including modularity, intelligence, and autonomy. These features are crucial for environment-conscious manufacturing to avoid too early retirement and replacement and to reduce production volume.

The paper reports a computational framework for knowledge intensive engineering called a knowledge intensive engineering framework. It also describes examples of soft machines including two types of self-maintenance machines and a cellular machine.
The Development of Machine Fault Detection Using Artificial Neural Network and Fuzzy Logic Technologies
Authors: Chow Mo-yuen , Lee Yuan-Shin
Published: July 2023

Machine fault detection has been attracting significant attention from industry. The early detection of faults in rotating machines can significantly enhance the safety, reliability, and economic issues of industrial operations. With the emerging technology of artificial neural networks and fuzzy logic, the machine fault detection problem can be solved using an innovative approach based on easy accessible measurements, without the need for expensive equipment or accurate mathematical models that are required from conventional fault detection techniques. This paper will describe the advantages and the challenge of using the technology of artificial neural networks to solve machine fault detection problems, and also highlights parts of the research results obtained by the authors. A case study of motor fault detection is presented in this paper.
New High-Order Neural Network and its Application in Multiple Faults Simultaneous Diagnosis for Rotating Machine
Authors: Binglin Zhong , Yongyong He , Minping Jia
Published: July 2023

To overcome limitations of the standard feedforward neural networks, a novel high-order neural networks (i.e. ellipsoidal unit networks), which is very available for pattern classification applications due to its bounded generalization and extrapolation, has been proposed recently. In this paper, the theory and structure of such networks are described. A method for initializing hyperellipsoids and the training algorithm based on the standard backpropagation algorithm are proposed. Then, a Hierarchical Diagnosis Artificial Neural Networks (HDANN) based on the ellipsoidal unit networks is put forward with respect to multiple faults simultaneous diagnosis for rotating machines, which consists of several subnetworks and aims at dividing a large pattern space into several smaller subspaces. The subnetworks can be trained in subspaces respectively and the whole network is capable of multiple faults simultaneous diagnosis. Finally, typical fault samples of rotating machines are tested in the network. The research results show that HDANN can obtain more accurate and efficient diagnosis results and is available for real-time condition monitoring and on-line diagnosis of rotating machines.
Diagnosis of Multiple Fixture Faults in Panel Assembly
Authors: Shi Jianjun , Apley Daniel W.
Published: July 2023

This paper presents a modeling procedure and diagnostic algorithm for fixture related faults in panel assembly. From geometric information about the panel and fixture, a fixture fault model can be constructed off-line. Combining the fault model with in-line panel dimensional measurements, the algorithm is capable of detecting and classifying multiple fixture faults. The algorithm, which relies heavily on the fault model, is based on least squares estimation. Consequently, the test is of relatively simple form and is easily implemented and analyzed. A theoretical analysis demonstrates the performance of the test, in terms of probability of detecting faults and probability of false alarms.
A Method for Rapid Characterization of the Volumetric Error of Multi-Axis Machines
Authors: Mou J.
Published: July 2023

In this paper, an innovative approach is proposed to integrate both neural networks and kinematics based models for machine error characterization. First, a method was presented for rapid characterizing the accuracy of multi-axis machines. Detailed derivation of a generalized error model was given. Second, a neural networks model is then implemented to map the nonlinear relationship among the positioning error, tool position, and temperature profile of the machine structure. The output of the neural networks model is the predicted coefficients for a kinematics based error model. The kinematics based model with the predicted coefficients is then used to compute the time-variant positioning error that relates to structural, kinematic, and thermally induced errors at any point within the workspace. In determining the error model coefficients, there is no measured data is available for direct comparison with the neural networks output. Instead, the difference between the predicted errors from kinematics based model and the measured errors is used to train the neural networks. Therefore, a new training algorithm is derived for this integrated error modeling system by adopting the gradient-decent method.
Gear Pitting and Chipping Assessment via Model-Based Algorithms: A Case Study
Authors: Li C. J. , Limmer J. , Yoo J.
Published: July 2023

Several different vibration-based gear diagnostic algorithms are compared for their ability to assess tooth surface pitting and chipped teeth. Existing algorithms include spectrum analysis, various Figures of Merit, energy operator analysis, narrow band demodulation, wide band demodulation and the Choi-Williams time-frequency distribution. These methods are compared with recently developed modeling/prediction error analysis methods.

Pitting assessment is tested using vibration measurements taken from a 350hp, 4-square gear testing setup at different times during a long term gear test in which frosting (i.e., micro-pitting) develops as documented by digital images of the pinion tooth surface. Examining the images of all the teeth, we found that frosting develops evenly throughout the pinion and the extent of frosting grows with time. Chipped tooth detection is evaluated using data from a setup where defects of different sizes were artificially seeded. It is found that model prediction error analysis and other existing methods work reasonably well on the chipped tooth gear. Prediction error analysis is the most accurate indicator of pitting, while wide band demodulation, FM4 and NA4 show some promise that requires further testing.
Detection and Isolation of Faults in the Stamping Process
Authors: Koh Christopher K. H. , Shi Jianjun , Williams William J. , Ni Jun
Published: July 2023

The sheet metal drawing operation is a complex manufacturing process involving more than forty process variables. A fault is said to occur when any of these process variables deviate beyond their specified limits. Current detection schemes based on this principle have exceptionally high false alarms rates. They are also unable to detect frequency or phase shifted fault signals whose amplitudes remain within specifications; nor do they provide information about the multiplicity1 or location2 of the faults. A method of overcoming these limitations is proposed in this paper. It is based on the orthogonal Haar transform which is used to generate a set of detection signals for the different fault conditions.
A Collaborative Process and Data Management Framework for Concurrent Product and Process Development
Authors: Chen Yuh-Min , Ho Cheng-Ter , Hsiao Yun-Tau
Published: July 2023

This paper presents a collaborative process and data management framework which is capable of supporting information sharing in concurrent product and process development by providing functions for process control and data management. Establishing this framework involves: (i) identification of functional requirements for computer-aided concurrent product and process development, with an emphasis on net shape processes, (ii) use of system engineering and object-oriented modeling techniques for development of the proposed framework.
A Research Agenda for Capacity Driven Systems Design
Authors: Meinert Timothy S. , Taylor G. Don
Published: July 2023

In many manufacturing settings, the design of products, processes, material handling and logistics systems, and plant layouts are not fully integrated and are evaluated using varied performance metrics. The research agenda presented herein seeks to develop a general set of tools and design guidelines to aid in the integration of these design functions and seeks to measure the effectiveness of these tools using a common set of performance criteria. The most unique aspect of the research is a holistic integration focus which includes explicit consideration of capacity issues as well as capability concerns. The effectiveness of system design guidelines will be evaluated using generalized settings as well as case studies with actual manufacturing systems and data. A research agenda to support capacity driven system design is put forth in this paper to demonstrate the depth and breadth of current research considerations.
Two-Dimensional Finite Element Thermal Stress Analysis of Butt Adhesive Joint in Steady Temperature State
Authors: Nakagawa Fumito , Sawa Toshiyuki , Nakano Yuichi , Katsuo Masahide
Published: July 2023

Thermal stresses of butt adhesive joints in steady temperature state are analyzed using a two-dimensional finite element method (FEM). The results obtained are as follows. The maximum principal thermal stress in the adhesive layer decreases when the ratio of thermal conductivity of an adhesive to that of an adherend approach I. When both adherends arc in the same temperature state, the maximum principal thermal stress in the joint decreases with a decrease of the adhesive thickness. When both adherends are in different temperature states, the maximum principal thermal stress varies with the ratio of the adherend thickness to the adhesive thickness. The maximum principal thermal stress in the joint which is subjected to the uniform temperature change AT is smaller than that in the joint in which the temperature difference of free surfaces of both the adherends is AT. In the experiments, the adhesive layer of the butt adhesive joint was modeled by an epoxide resin plate. The thermal stresses of the joints under steady temperature state were measured by two-dimensional photoelastic experiments. Fairly good agreement was seen between the numerical and the experimental results.
The Interaction of Crack and Creep in Cross-Ply Composites
Authors: Gao Zhanjun
Published: July 2023

For cross-ply laminates micro-matrix cracks in the 90° plies and creep deformation of the 0° and 90° plies are two forms of damages which affects the long-term durability of the materials. In this paper, a general framework for the analysis of cross-ply laminates with matrix cracks and creep deformation is proposed. For this purpose admissible stress fields are constructed which satisfy equilibrium and all boundary and interface conditions. The principle of minimum complementary energy is utilized to derive a differential equation for the stress function from which the stress field of the composite can be derived. The inhomogeneous term of the differential equation involves the creep strains which are loading history dependent. The Green’s function of the differential equation is then obtained. Using the Green’s function and a constitutive equation, two-dimensional stress and strain states in the composites at any time are represented through an integral of the Green’s function and the accumulated creep strains. This new analysis takes into consideration the microcrack-microcrack interaction, as well as the interaction between the microcracks and the creep deformation, and provides a point-wise stress field instead of average stress field as most of the analytical approaches yield.

The interactions of matrix cracks and creep deformation of an eight-harness satin weave (8H SW) Nextel 610/Aluminosilicate ceramic matrix composite is studied using the proposed model. The predicted creep strain of the composite shows good correlation with experimental data at different levels of temperature and stress conditions.
Experimental Study of Rotor Blade Tip Clearance Control Utilizing Smart Structure Technology
Authors: Lin Y.-J. , Wen C. , Choi B. , Saravanos D.
Published: July 2023

In this paper the experimental development of a simple and effective vibration control scheme for a flexible cantilever beam employing smart structure technology is presented. Our goal is to develop a physically realizable means to actively control turbine rotor blade tip vibration with piezoceramic sensors and actuators. To include the flexible characteristics of rotor blades in our analysis, a flexible cantilever beam is used to simulate the dynamic behavior of the turbine blades due to external disturbances, generated by a magnetic shaker. The shaker was installed near the free end of the flexible beam to maximize the external excitations. Piezoceramic sensor and actuator were used and evenly distributed as elements of the smart structure. The mathematical model of the smart structure including the piezoceramic sensors and actuators was determined by combining both analytical and experimental schemes. Based on the derived experimental dynamic model, a proportional gain feedback controller was implemented to compensate for the vibratory deflections of the underlying structure. The results of the work show that the proposed control methodology along with the smart structure can suppress more than 80% of the measured structural vibration, which is considered satisfactory.
The Selection of Diagnostic Technologies and Sensors for Condition Based Maintenance Systems
Authors: Nemarich Christopher P. , Hegner Henry R. , Natishan Marjorie Ann E.
Published: July 2023

The effective implementation of Condition Based Maintenance (CBM) systems generally requires the use of sensors selected specifically to detect, isolate and diagnose machinery component faults. In order for CBM systems to operate reliably, the diagnostic technologies and sensors used to monitor the machinery must provide repeatable and accurate measurements. The ability of a CBM system to effectively detect and correctly identify component faults at their inception depends largely on the appropriate selection of the fault parameters to be measured and the sensors used to measure them. Furthermore, the incorrect selection, inappropriate application, or inattention to the sensor performance requirements may lead to missed failure detects and false alarms, resulting in the general lack of acceptance of the entire CBM system. This paper presents an overview of a methodology for the selection of applicable diagnostic technologies and sensors for machinery health monitoring systems.
Reliability-Centered Maintenance Approach Applied to a Pipeline
Authors: Checkwitch Kerry S. , Glover Alan G. , Van Hardeveld Thomas
Published: July 2023

A recent business process re-engineering effort undertaken at NOVA Gas Transmission Ltd. provided an opportunity to completely review and improve upon strategies and methodologies used in the maintenance of a very complex natural gas transportation system. In order to achieve safety and reliability in an expanding and aging system, a completely new approach to maintenance planning was adopted based on a Reliability-Centered Maintenance strategy. This is the first application of this approach to a gas transportation system. Development of this maintenance methodology, its major components, and specifically how it has been applied to a pipeline are discussed. The integration of this strategy into a complete pipeline integrity management system allowing full assessment of all hazards specific to the pipe is also reviewed. Examples of results and benefits from the first systems analyzed using this new approach are presented.
The Briar Patch: From DoD to Commercial Systems Engineering
Authors: Hale Pat
Published: July 2023

Most of us are familiar from childhood with the Uncle Remus story where Br’er Rabbit escapes being the main dinner course by imploring his captor to “Throw me in that briar patch!”. Following defense secretary Perry’s initiative to move DoD toward commercial standards and best practices, many DoD systems engineers have wondered what distinguishes commercial systems engineering from traditional aerospace processes and practices. This paper describes the experiences and observations from a DoD systems engineer’s transition into a pure commercial product development environment. Topics include: What is ‘commercial’ systems engineering? What practices from DoD provide the highest added value in the commercial world? What are the unique challenges to application of systems engineering in the commercial world? What lessons can DoD learn from commercial industry? And, finally, is this commercial ‘briar patch’ a viable future address for you as an aerospace-trained systems engineer?
Why Mechanical Subsystems Are Difficult to Integrate
Authors: Segalman Daniel J. , Ortiz Keith , Wesner John W.
Published: July 2023

Though the theme of System Engineering is integration, and it is normal to attempt in integration to ignore the lines between disciplines, there are distinct characteristics of the mechanical design portion of any major system design project that make this difficult. How these characteristics compound the difficulty of integration is discussed and means to minimize the associated obstacles are suggested.
Perspectives on the Modern Manufacturing Engineering Systems
Authors: Lee Jay
Published: July 2023

This paper presents author’s perspectives on the manufacturing engineering systems in a changing world. A brief historical review of manufacturing evolution is described. Perspectives in making manufacturing engineering a science is presented. At last, issues and challenges of the manufacturing engineering systems in the future are discussed.
Developing High Technology Spacecraft in a Severely Cost Constrained Environment
Authors: Euler Edward A.
Published: July 2023

Traditionally, the development of high technology spacecraft for the U.S. Government has been a relatively long duration, high cost activity. A step by step serial process from concept development through manufacturing and test was carefully followed with voluminous documentation, rigorous reviews at each major milestone, and a thorough test and independent quality check of each component and assembly produced. This process has evolved over many years because successful first time operation is so critical. With spacecraft, there is no second chance after a failure. Before the relatively recent emergence of a commercial spacecraft market, the only customers were the U.S. Government (DoD and NASA) who indirectly controlled the development process to insure that technical performance has always been the top priority with cost and schedule significantly lower in importance.
Cure Kinetics for Conductive Adhesives
Authors: Mei Yuhai , Wu Sean , Yeh Chao-pin
Published: July 2023

Conductive adhesives as solder replacement play more and more important role in surface-mounting technology. The magnitude and duration of cure cycle temperature significantly influence the final physical and mechanical properties of the joints. Therefore, a knowledge of the reaction kinetics is essential for relating the physical properties to the extent of reaction of the system. A series of isothermal tests was processed, and the experimentally obtained results were checked against the proposed kinetic model. A modified kinetic model is proposed to describe the rate of degree of cure, and a good agreement was found between modeling and test results.
Finite Element Vibration Analysis for Zero Inserting Force Socket
Authors: Chiang Kuo-Ning , Fu Hsueh-Horng
Published: July 2023

In this research, a vibration analysis using finite element method with specific application to CHIP, LCP socket and PCB packaging are studied. The sensitivity of the design and material parameters of the whole CPU connector system is studied by two different approaches. A coarse finite element model is established to investigate the effects of vibration modes of the boundary condition parameters, and a detailed finite element model is adopted to evaluate the influence of the different types of boundary constrains to the whole system.
Step Soldering Factors Affecting the Reliability of Ag-Pd Thick Film Conductor Pads
Authors: Pan Tsung-Yu , Blair Howard D. , Mitlin David , Crosbie Gary M. , Nicholson John M. , Hangas Jon
Published: July 2023

One of the essential thick film materials on the hybrid circuit is the conductor which performs as an interconnection between discrete components. However, metallurgical reaction between the conductor and solder during the soldering or thermal aging/cycling may cause electrical failure and/or loss of adhesive strength due to the reaction of Ag/Pd with Sn and subsequent intermetallics formed. A step soldering process, which applies a high-Pb solder layer over the conductor layer before the eutectic or near-eutectic Sn-Pb solder is applied, has been shown to prevent contact between the conductor and Sn in the solder, as long as the high-Pb layer does not dissolve into the low-Pb layer. Experiments were carried out to quantify the isothermal interdiffusion reaction rate and the interface displacement between the 88Pb-10Sn-2Ag and the eutectic 63Sn-37Pb solder layers between 195 and 235°C. The results were analyzed by the methodology developed by Lommel and Chalmers (1959) which was based on Nernst-Brunner theory of dissolution (Moelwyn-Hughes, 1947). The displacement of the interface follows an Arrhenius relationship with an activation energy of 98 KJ/mole, which is close to the activation energy of solid Sn diffusion into Pb. A process window was constructed to show that temperature is a more sensitive parameter influencing the reaction rate than time. A mathematical model was applied to predict the interfacial displacement during the reflow process and was found to correlate well with experimental results.
Perspectives for Practical Application of Active Control of Noise and Vibrations in Passenger Cars
Authors: Moreggia Vittorio
Published: July 2023

Several active sound and vibration control systems have been proposed for noise and vibration in automobiles, including In-Cabin Silencing systems for the “volumetric” reduction of engine or rolling noise inside the passangcr compartment, Active Engine Mounts for the reduction of structural vibrations in the car body, induced by the engine cycle, as well as “at source” ASC systems for noise radiated by the air induction and gas exhaust discharge orifices.

The paper overviews the implementation of experimental vehicles, the test resultes and the perspectives for application in mass-produced series. Emphasis is given to a comparative evaluation of the performances of In-Cabin Silencing, Active Engine Mounts and counterrotating engine balance shafts, for the abatement of engine “booming” noise in passenger cars.powered with 4-cilinder-in-line engines.
Active Control of Rolling Noise in a Passenger Car Through Structural and Acoustic Control
Authors: Banfo Gian Luca , Dehandschutter Wouter , Schmidetzki Rainer
Published: July 2023

Within the Brite-Euram Project “Anrava” several active control systems have been evaluated in order to reduce the road noise generated inside the cabin of a mid size station wagon during driving condition on different road surfaces. Different control strategies (feedforward with local and global control, pure feedback) and different approaches (active structural acoustic control and active noise control) have been tested on the car in laboratory conditions and the control performances have been evaluated. The final control strategies, that have been resulted from this study, are based on an adaptive feedforward control algorithm: six accelerometers provide the reference signals and 4 microphones placed inside the cabin give the error feedbacks. Two control configurations, each using a different kind of control sources, have been retained: the structural acoustic control system which works with 6 inertial shakers positioned through the main vibration transmission paths, the anti-noise system with 4 loudspeakers inside the cabin.

The paper describes the approaches utilized to design the different control systems and examines the results obtained during laboratory and road tests comparing them with the predicted performances based on numerical simulations.
Feedforward Active Vibration Control of the Axially Moving String With General Boundary Conditions
Authors: Ying S. , Tan C. A.
Published: July 2023

Active vibration control of an axially moving string by space feedforward control is presented. The problem is formulated to allow considerations of general boundary conditions, which are important from both practical and experimental viewpoints. Closed-form results for the transverse response of both the uncontrolled and controlled string are given in the s domain. The space feedforward controller is established by employing the idea of wave cancellation. The proposed control law indicates that vibration in the region downstream of the control force can be cancelled. Moreover, the control forces are expressed only in terms of measured response and are not explicit functions of the boundary conditions which in general cannot be easily determined. Stability conditions of the controlled system and characteristics of the control forces are also derived and discussed. Simulation results show that the response of the string to both sinusoidal and random excitations is suppressed by applying the space feedforward control.
Implementation of DR and DFFDR Techniques on Distributed Systems
Authors: Olgac Nejat , Elmali Hakan , Hosek Martin , Renzulli Mark
Published: July 2023

The Delayed Resonator (DR) and Dual Frequency Fixed Delayed Resonator (DFFDR) are newly introduced control techniques for active vibration absorption. Both methods propose a delayed position feedback within the absorber portion of the structure to impart ideal resonance features to the absorber. When installed on an oscillating body, they become ‘notch filters’ at their resonance frequencies against excitations on the primary structure. The DR absorber is shown to be real time tunable to the time varying disturbance frequencies. This article addresses the verification of these methods in high frequency ranges. Experiments are conducted on a steel beam to verify the analytical findings. Piezoelectric actuators are used to generate harmonic disturbances and also to implement the control. Encouraging correspondence between the theoretical and experimental findings is observed as well as effectiveness of the DR and DFFDR absorption techniques.
Comparison of Active and Semi-Active Vibration Controllers for a Dragline Boom
Authors: Clark William W. , Kim Sung Hwan
Published: July 2023

This paper compares three semi-active control techniques to two fully-active control methods in suppressing transient vibrations of a dragline, a crane used for excavation. The fully-active methods include full-state feedback optimal control and direct-velocity feedback control, and are used as the benchmarks in the comparison. The semi-active techniques include simple damping, stiffness, and hybrid damping/stiffness controllers. The semi-active methods are selected such that they could be practically implemented on the dragline. The paper first looks at the control methods as applied to a single degree-of-freedom system in order to demonstrate their techniques, then the methods are applied to a 50th-order model of a dragline. The performance of each controller is quantified by several measures, and the feasibility of implementing semi-active control in a large flexible structure such as the dragline is discussed.
Parametric Control of Structural Vibrations via Adaptable Stiffness Dynamic Absorbers
Authors: Lai J. S. , Wang K. W.
Published: July 2023

An energy-based algorithm is developed for dynamic absorbers with adaptable stiffness to suppress structural vibrations via real-time parametric control actions. A controller with multi-objective fuzzy logic is created to reduce the main structure energy while constraining the total system energy. An adaptive-passive supervisor is designed to provide guidelines for implementing the control law. It is proved that the system using this supervisor is globally stable in the sense that all signals involved are bounded. The performance of the controller is demonstrated on a beam example. It is shown that the structure energy level and vibration amplitude can be suppressed effectively.
Sensing/Control of Shell Symmetrical Modes Using Diagonal Line Sensors/Actuators
Authors: Zhong J. P. , Tzou H. S. , Tani J.
Published: July 2023

With the recent introduction of spatially distributed piezoelectric transducers, distributed sensing and control of distributed parameter systems, i.e., elastic continua, can be realized in real physical systems. Since the transducers are spatially distributed in nature, sensor/actuator shapes are crucial to their spatial sensing and control characteristics. This paper is to present a new class of distributed line sensor/actuator specifically designed for sensing/control of shell symmetrical modes. Electromechanics of the line sensor/actuator is discussed and the membrane and bending contributions are analyzed. Sensing and control effectiveness of cylindrical shells are evaluated.
Hybrid Controller for Vibration Suppression: Integrating Physical and Modal Information Using Fuzzy Reasoning
Authors: Greif Robert , Asdigha Mehran
Published: July 2023

Independent Modal space Control (IMSC) is a well established method in active control of vibration. In this method, the control law is developed exclusively in the modal space, allowing for independent design of modal control forces. These forces are then transformed to the physical space by modal transformation. The resulting controller is fixed-gain, with the active damping introduced to the system determined independently for each mode. This damping is directly proportional to the modal velocity in the under-damped case. In this work, we propose to modify IMSC using kinetic energy distribution in the modal space, and fuzzy reasoning. The result is a new non-linear control law, embedding fuzzy reasoning and an implicit fuzzy rule-base that transforms the standard algorithm from a fixed-gain, to a variable-gain controller. A variant of the new algorithm uses information about the velocity profile across the sensed locations to distribute the active damping rationally among the modal controllers. This new algorithm complements the local view of the traditional algorithm in the modal space, with a global view of the velocities in the physical space. The results show significant improvement in the settling time as the performance criterion.
Hybrid Feedforward/Kalman-Filter Controller for Reaction Force Suppression
Authors: Clark William W. , Kim Joo H. , Shelley Franz J.
Published: July 2023

This paper presents a method for actively controlling dynamic reaction forces in flexible structures subject to persistent excitations. The motivation is provided by applications in which dynamic loads result in structural or machinery failures (for example, in the bearings of rotating machinery), or in situations where transmitted vibrations degrade the performance of a system or process. This work is a deviation from much of the vibration control work which focuses on suppressing structural displacements instead of forces.

The controller is based on an adaptive feedforward disturbance cancellation scheme which has come to be a commonly used method among researchers for persistent disturbance cancellation. In order to use that method for control of forces, however, some modifications are necessary. First, since reaction forces are not typically measured in structures, a Kalman filter state estimator is developed to provide the reaction force signal to the feedforward algorithm, and second, the residual flexibility matrix is used in conjunction with the Kalman filter in order to provide accurate force estimates in spite of a reduced-order model. This paper presents the development of the reaction forces, the Kalman filter estimator, and the hybrid feedforward control law, and applies the overall method to a flexible beam test rig to suppress the dynamic reaction forces at its supports.
Numerical Model of a Coupled Structural System Connected by Active/Passive Springs
Authors: Hwang Y. F. , Louie L.
Published: July 2023

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.