bluuebunny/crossref_metadata_2025_split huggingface dataset:
First-Excursion Probability and Response Peak Distribution of a Nonlinear Structure Under Non-Gaussian Non-Stationary Loadings
Authors: Lua James , Mover E. Thomas 
Published: January 2022

Abstract
Probabilistic methods have been used recently for the reliability assessment and design of ship structures because of the presence of various uncertainties in structural configuration, material properties, and environmental and operating conditions. Among these uncertainties, random dynamic loads induced by either sea waves or slamming play a significant role in reliability-based ship structural design. The present state-of-the-art probabilistic method for ship design is based on a linear structural response model subjected to stationary Gaussian random processes. However, under extreme operating conditions, the ship structural response may not be linear due to the initiation and evolution of multiple local damage, such as local plastic deformation, stiffener tripping, panel buckling, or fracture. In addition, the complexity of fluid-structure interaction phenomena may render the assumptions on the loading process (stationary and Gaussian) invalid.
Under this study, we developed a simulation based probabilistic analysis framework for a nonlinear dynamic structural system under non-Gaussian non-stationary loadings. The general simulation based probabilistic analysis framework (SIMLAB) is formulated by integrating 1) random variable generating modules; 2) random process generation modules; and 3) user selected deterministic solver and limit state function. The developed random process simulation module is able to generate a Gaussian, non-Gaussian, stationary, or non-stationary process. To demonstrate the applicability of the developed tool for a structural dynamic system with random variables and random processes, a free-free beam subjected to a sea wave induced random process is solved by integrating a structural dynamics code, DYNA3D, with the developed probabilistic analysis framework. The limit state function is formulated based on the first crossing of a beam Von Mises stress at an integration point above a safe threshold.
In order to validate the accuracy of SIMLAB, a linear beam structure subjected to a stationary Gaussian process is considered first and the simulated statistical distributions of peak and extreme response variables are compared with analytical predictions. The effect of material nonlinearity on probability of failure and peak statistics is explored by using an elastoplastic beam model subjected to a random excitation. Results on probability of failure and peak statistics are compared with the corresponding statistical models for a linear structure. The great versatility of the simulation based probabilistic analysis framework provides us a solid foundation for the development of more advanced probabilistic analysis tools for reliability-based ship design.
Active Control of Vibration in a Flexible Structure With Uncertain Parameters via Sliding Mode and H∞/μ Techniques
Authors: Pai M. C. , Sinha A. 
Published: January 2022

Abstract
This paper presents a new approach for the robust control of vibration in flexible structures with uncertain parameters. The algorithm is based on sliding mode control and H∞ / μ techniques. First, the sliding mode control algorithm is developed using state feedback and the chattering behavior is eliminated using boundary layers around sliding hyperplanes. The LQ control method and H∞ control method for designing sliding hyperplanes are presented. The switching control is chosen to satisfy the so-called reaching condition. Then, the small gain theorem / μ analysis is applied to analyze the asymptotic behavior of the closed-loop system with parametric uncertainties inside boundary layers. Using a flexible tetrahedral truss structure, numerical examples are presented to verify the theoretical analysis. Results from H∞ full state feedback control method, sliding mode with H∞ full state feedback control method, LQ control method and sliding mode with LQ control method are presented and compared.
Modeling and Robust Control of Vibrations in a Flexible Four-Bar Mechanism
Authors: Karkoub Mansour , Yigit Ahmet S. 
Published: January 2022

Abstract
Dynamic modeling and controller design for a flexible four-bar mechanism is studied. The fully coupled nonlinear equations of motion are obtained through a constrained Lagrangian approach. Resulting differential-algebraic equations are solved numerically to obtain the system response. A linearized dynamic model is developed which facilitates design of various controllers. The fully coupled nature of the governing equations facilitates control of elastic motion through the input link alone. A simple PD and a robust μ-synthesis controller are shown to be efficient in suppressing the vibrations of the flexible link as well as controlling the rigid body motion.
Global Sensor Systems for Vibration and Noise Control Applications
Authors: Sun J. Q. , Hirsch S. M. , Jayachandran V. 
Published: January 2022

Abstract
A sensor system is defined as being global if the reduction of a performance measure based on the sensor measurements guarantees a decrease in a global response measure of the system. In this paper, the mathematical condition for such a sensor system is derived and this concept is then applied to structural and acoustic control problems. It is shown that the nodal placement of sensors always leads to a global sensor system, and that in this case, the sensor based performance measure differs from the global performance measure by only a scaling constant. In tonal and narrow band problems, a global sensor system may be redundant. A criterion is developed to determine the number of sensors needed in such applications. Some simple examples are used to demonstrate the theory.
Passive Control of Systems Subjected to Repetitive Impulse
Authors: Minas Constantinos 
Published: January 2022

Abstract
A model describing a dynamic system subjected to repetitive impulse was developed. The methodology presented addressed the specific case where the impulse repetition occurred at equal time intervals. The methodology was illustrated through an example, where a cryocooler induced repetitive impulse to a cryocooler cooled device. The analysis considered both a rigidly and a flexibly mounted cryocooler. Passive control was implemented by varying the coupling stiffness between the cryocooler and the cryocooler cooled system, the stiffness to ground and the mass of the cryocooler.
Flow Modeling and Validation of the Encapsulation of Plastic Packages
Authors: Nguyen L. , Quentin C. , Lee W. , Bayyuk S. , Bidstrup-Allen S. A. , Wang S.-T. 
Published: January 2022

Abstract
A major manufacturing defect encountered in plastic encapsulation of IC components by transfer molding is wire sweep, the permanent deformation of wirebonds under the hydrodynamic loads imposed by the viscous flow front. Optimization of design geometries and processing conditions to minimize defects still cannot be achieved without time-consuming and expensive experiments that frequently involve hardware modifications. Thus, a need for simulation and defect-prediction techniques to replace the costly experiments is much needed for true design-for-manufacturability and faster cycle time.
This paper will present the results of a DARPA-funded program to develop a self-contained methodology and software suite (called PLICE-CAD) for modeling the entire packaging process. Simulation of the reactive flow in the molding of a thin quad flat package (TQFP) will be presented and validated with operating parameters (e.g., pressure, temperature, flow front advancement, ...) measured with in-process sensors.
A Testing Method and Device for Intrinsic Stress Measurement in Wafer Bumping Process
Authors: Guo Yifan , Mitchell Dianne , Sarihan Vijay , Zheng Dawei 
Published: January 2022

Abstract
A novel concept and the related testing methodology for a sensing device is presented. This device is used to determine the distributions of local residual stresses induced in wafer processes such as metalization and bumping. The sensing device is essentially a pressure sensor structure with a specified membrane thickness. Either a whole pressure sensor wafer or a single die sensor can be used for this purpose. This sensing device is put into the processes which are under investigation or being monitored. After each processing step, the membrane is deformed due to the process induced residual stress. The membrane deformation is either monitored continuously by the electrical signals from the pressure sensor during the process or measured by an optical method after each process step. Residual stresses are calculated from the measured membrane deformations.
Rheology of Suspensions in Reduced Gravity
Authors: Bakhtiyarov Sayavur I. , Overfelt Ruel A. 
Published: January 2022

Abstract
Viscosity of settling suspensions was studied experimentally in a series of reduced gravity parabolic flights aboard NASA’s KC - 135 aircraft. Slurries were made using silica sand (0.150 mm &lt; dp &lt; 0.212 mm) and Glycerol solution. The experimental set up incorporated instrumentation to measure the apparent viscosity of the sand suspensions at the wide range of the shear rates. The container had transparent walls to allow visualization of the structure changes involved in Couette flow in reduced gravity. Experiments were performed over a broad range of gravitational accelerations including microgravity and double gravity conditions.
The results of the flight and ground experiments reveal significant differences in the apparent viscosity of sand suspensions and overall void factor in microgravity as compared to one-g conditions.
Rheology of Drag-Reducing Surfactant Solutions
Authors: Pal Rajinder 
Published: January 2022

Abstract
The rheology of drag reducing cationic surfactant solutions was investigated using a controlled-stress rheometer. Both steady and oscillatory shear measurements were carried out at 25°C with the help of the cylindrical double-gap measuring geometry. The cationic surfactant investigated was Ethoquad T/13-27W, a commercial product manufactured by Akzo Nobel Chemicals Inc., U.S.A. Sodium salicylate (NaSal) was used as counterion. The effects of the surfactant and counterion concentrations on the rheological behaviour were also determined.
The surfactant solutions in the presence of counterion exhibit non-Newtonian rheological behaviour. At shear rates below some critical value, the surfactant solutions behave as either shear-thinning or Newtonian depending upon the counterion concentration; at low NaSal concentrations, shear-thinning is observed whereas at high NaSal concentrations, Newtonian behaviour is observed. When the shear rate is increased above the critical value, a rise in viscosity is observed indicating shear-thickening or dilatant behaviour. Oscillatory shear measurements indicate that the surfactant solutions are significantly viscoelastic. At a given surfactant concentration, the rheological parameters such as zero shear viscosity, critical shear rate, storage and loss moduli, etc. first increase, reach a maximum value, and then decrease with the increase in NaSal concentration. With the increase in surfactant concentration at a fixed NaSal/surfactant weight ratio, the rheological parameters show a significant increase.
A Rheological Characterization of High Percent Solids Kraft Black Liquor
Authors: Sanders Christian L. , Bakhtiyarov Sayavur I. , Siginer Dennis A. 
Published: January 2022

Abstract
Tube flow elastic recovery is employed to measure the normal stresses of an experimental liquid, polyacrylamide, and an industrial liquid, kraft black liquor. It is shown that the elastic recovery provides a reasonable method to measure normal stresses where the conditions of interest are difficult to reproduce in standard measurement techniques. Tube flow elastic recovery assumptions are tested for the liquids under study. New normal stress measurement data is presented for the kraft black liquor and it is shown to be a function of shear rate and temperature.
Shear Stress of ER Suspensions
Authors: Tsukiji Tetsuhiro , Saito Shigeaki , Asako Yoshinobu , Kawakami Toshihiro 
Published: January 2022

Abstract
The shear stresses of ER (Electro-rheological) suspensions are measured by changing a shear rate, amplitude and frequency of electric fields using rotational viscometer whose gap between electrodes can be changed. We use two ER suspensions which are called ERFC and ERFP. ERFC consist of cellulose suspended in silicone oil. The size of cellulose particles is typically about 10∼20 μm and a viscosity of silicone oil is 10mm2/s. Cellulose concentration is 20wt.% and the percentage of moisture content is 0.6%. ERFP contains highly sulfonated poly (styrene-co-divinylbenzene) particles. An average particle diameter of ERFP is 9 microns and the water content is 2.0 wt.%. Unipolar sine-wave electric fields which is AC with DC bias and bipolar sine-wave electric fields without DC bias are used. The shear rates of 400 s−1 are employed. Amplitudes of the electric fields are 0.4 and 0.8 kV/mm and DC component is 1.0 kV/mm for unipolar sine-wave electric fields. Amplitudes are between 1.0 and 2.5 kV/mm for bipolar sine-wave electric fields. The frequency of the electric fields is changed from 0.1 to 100 Hz. Dependence of the shear stress on electrical excitation frequency is investigared.
Recent Developments in Network Theory
Authors: De Kee D. , Chan Man Fong C. F. 
Published: January 2022

Abstract
An understanding of the flow properties of non-Newtonian fluids is important in many areas of application. To solve flow problems, it is required to introduce a constitutive equation that relates the stress tensor to various kinematic tensors. The determination of a constitutive equation which describes adequately the rheological properties of a fluid under all flow conditions is one of the central problems in rheology. Constitutive equations have been developed based on either continuum mechanics or on the molecular structure of the fluids.
Preform-Particle-Flow Interactions in Impregnation of Fibrous Preforms With Particle-Filled Resin
Authors: Erdal Merve , Güçeri Selçuk 
Published: January 2022

Abstract
Particle-filled preceramic polymer injection into woven fiber preforms is currently under investigation as a means of processing dense, complex-shaped ceramic composites. The distribution of filler particles as a result of filtration during their impregnation into dense fiber preforms, has a crucial effect on the properties of the end product. In general, highly filtered particle distributions are not desirable since they lead to nonhomogeneous part microstructure and hence, mechanical properties of the composite. In order to understand how various process parameters (injection velocity, inlet particle concentration, fiber preform permeability, etc.) interact during impregnation and to ultimately control the amount of filtration, a process model is presented. A multi-dimensional, transient particle filtration formulation is coupled with isothermal, anisotropic Darcy’s flow to predict filler concentration profiles during molding of complex shapes. The permeability of the preform, porosity of the flow domain, viscosity of the impregnating resin and filtration coefficient are all affected by the particle deposition and they constitute the nonlinearity in the coupled flow and filtration equations. Results for 2-D impregnation into complex preforms are presented and methods for manipulating particle distribution are discussed.
Steering System of John Deere 8000 Series Track Tractors
Authors: Mistry Sanjay I. , Hou Yifei R. 
Published: January 2022

Abstract
The John Deere 8000 series track (8000T) tractors, introduced in June 1997 represent a significant change in steering system compared to previous John Deere tire tractor models. John Deere 8000 series track tractors are the first tractors in North America using “steer-by-wire” philosophy. The new steering system uses an electric signal to control the electro-hydraulic hydro-static system. The steering system provides performance improvements in several areas for unmatched operator convenience and control. This paper describes the steering system configuration, components, operation, characteristics and some of the engineering considerations dealt with in the development process. The overall steering system truly represents a mechatronic design.
An Investigation of a Roll Control Suspension Hydraulic Actuation System
Authors: Darling Jos , Hickson Luke R. 
Published: January 2022

Abstract
It is recognised that roll control suspensions offer a partial solution to the well known compromise between ride and handling. In this paper a simulation and experimental study of a vehicle with a roll control hydraulic actuation system is presented in which a variety of ways to reduce power consumption and cost are investigated. The introduction of dead-band into the control system can reduce power consumption while a proportional valve with a spool configuration which interconnects the load and tank ports when in the null position is shown to improve ride comfort and raise the system damping during conditions when the vehicle is subjected to aerodynamic lateral side loads. In the prototype vehicle it is argued that the system pressure could be reduced to levels similar to those of existing power steering systems, if the actuation system control gains are chosen appropriately.
A Self-Tuning Fuzzy Control of an Electro-Hydraulic Fin Position Servo System
Authors: Lee Sang Yeal , Park Young Jun , Cho Hyung Suck 
Published: January 2022

Abstract
Electro-hydraulic servo systems have been frequently used in the fin position servo system of a missile because of their high power and good positioning capability. The objective of this paper is to realize a self-tuning fuzzy controller for the position control of an electro-hydraulic fin servo system. In this paper, we propose a new self-tuning fuzzy controller, which can improve the overall performance of the electro-hydraulic fin position servo system. The uniqueness of this self-tuning fuzzy controller is that the performance evaluation of the fin position servo system is carried out in a phase plane mapped to a decision rule table. The effectiveness of this control scheme is verified by comparison with a fixed fuzzy control with initial rules through a series of simulation studies.
Continuous CMAC and its Application in Identification of Electrohydraulic Servo System
Authors: Wei Sun , Hong He , Shulian Wang 
Published: January 2022

Abstract
Based on finite element interpolation method a continuos CMAC (CCMAC) is proposed in this paper, the output of the network can change with its input continuously, the generalization of network is improved, the training speed and identification precision are also improved. The continuous CMAC is used in the system identification of electrohydraulic velocity servo control system, many simulation and experiment results are satisfactory.
Towards Autonomous Control of Hydraulic Actuator Systems
Authors: Hansen Poul E. , Conrad Finn 
Published: January 2022

Abstract
The proper adjustment of parameters in electro-hydraulic positioning controls demands a knowledge of the plant and the controller. Since this information is seldom available to the electrician, the result is often a crude tuned control system and even instability can occur. Different control algorithms are developed in this paper in order to increase the autonomy or intelligence of hydraulic controls. A refinement of the relay-tuning method is used to determine the controller parameters of a lag-lead and a pole placement controller. Furthermore, an integral action is included in the pole placement controller for eliminating steady state errors. A fail-safe function is developed to hinder surges and mechanical fractures. Experiments conducted on a hydraulic test robot demonstrate that the controllers considered perform well.
A Pneumatic Library for AMESim
Authors: Bideaux E. , Scavarda S. 
Published: January 2022

Abstract
The present development of the simulation and virtual prototyping actually has lead to the development of specialized software packages to industries using fluid power based components as the truck, railway or car industry. These specialized packages such as AMESim (Advanced Modeling Environment for performing Simulations), consist of a robust solver and multidisciplinary libraries of models, since the solving method is strongly linked to the simulation aim and the modeling step itself. AMESim has already proposed hydraulic and one-dimensional mechanical components and some useful tools for the study of fluid power systems. As strong links exist between hydraulic and pneumatic technology, we have implemented a library of pneumatic components that could be used in connection with the other existing libraries. The models arise directly from our pseudo bond graph knowledge and our experience of measuring existing pneumatic components. The first library (the Basic Elements Library) contains the basic elements : sources, modulated dissipative elements, modulated transformers, capacitive elements, sensors, which allow the simulation of any pneumatic based system. In the second library called the Elementary Component Library, we propose a selection of standard components such as relief valves, distributors, servo-valves and spools. The third and last library is the Advanced Component Library and it consists of models for specialists such as pipes, variable volume chambers, and more complex components.
In this paper, we propose an overview of this library of pneumatic components and we show its possibilities by simulating of an existing pneumatic systems.
On the Application of an Industrial Motion Controller to a Pneumatic Positioning System
Authors: Brook N. , Surgenor B. W. 
Published: January 2022

Abstract
This paper documents experience with the application of an industrial motion controller, originally intended for an electric servomotor positioning system, to a pneumatic positioning system. The pneumatic system consisted of a rodless cylinder connected to a proportional servovalve with a command signal generated by the motion controller. A linear analog potentiometer provided position feedback to the controller. The payload was 5 kg with a stroke of 0.6 m. Results demonstrate that respectable performance can be achieved, although the PID tuning technique normally implemented with the motion controller could not be used. An achievable motion trajectory is identified, and an appropriate PID tuning techniques is presented.
Influence of Viscosity on Aircraft Noise Diffracted by Edges
Authors: Pierce Allan D. , Zampolli Mario 
Published: January 2022

Abstract
The analysis of the influence of viscosity on diffraction of aircraft noise by edges is exemplified by the mathematical problem of diffraction of an acoustic plane wave by a thin rigid screen. The linearized equations of compressible fluid mechanics with viscosity included are considered with the overall disturbance field regarded as a sum of acoustic and vorticity fields. Each such field, for disturbances of fixed frequency, is governed by a separate Helmholtz equation, but they are coupled by the no-slip and nonpenetrability conditions at the screen’s surface. With viscosity taken into account, the perturbation-induced fluid velocity near the edge is not infinite, but is nevertheless very large when the viscosity is small, even though the velocity vanishes identically at the surface.