bluuebunny/crossref_metadata_2025 huggingface dataset:
The Essential Ingredients of Successful Sibling Relationships: An Emerging Framework for Advancing Theory and Practice
Authors: Kramer Laurie
Published: July 2010

Abstract— Although conflict is a frequent and dynamic interpersonal process in children’s sibling relationships, ambivalence (i.e., combinations of, or shifts between, positive and negative behaviors and affects) may better characterize normative sibling interactions. Nonetheless, there is a general assumption that reducing conflict is the most effective mechanism for improving sibling relationships. This review argues that the focus on conflict as the predominant attribute of sibling relationships is misplaced and has served to overshadow research on other relationship processes; it has also handicapped the development of effective prevention and intervention tools. Strategies are presented for moving theory, research, and practice toward the identification and development of factors and social processes that promote prosocial forms of sibling engagement and manage conflict. Innovative strategies are needed on two fronts: to help young siblings set their relationship on a positive trajectory and to help them avoid or remediate conflictual interactions.
Family Systems and Sibling Relationships
Authors: Cox Martha J.
Published: July 2010

Abstract— Family systems theory suggests the importance of the role of sibling relationships in the regulation of behavior and affect, not only as children develop but, in fact, throughout the life span. However, little research has been done on the potentially unique contributions that sibling relationships make to development. The 3 articles in this Special Section detail the existing literature on this topic and indicate important directions for further investigation.
Attachment and Life History Theory: A Rejoinder
Authors: Thompson Ross A.
Published: July 2010

Abstract— M. Del Giudice and J. Belsky (this issue) derive several provocative hypotheses from the application of life history theory to attachment, especially concerning the emergence of sex differences in insecurity in middle childhood. This commentary highlights the significant gaps in research knowledge that must be addressed before the merits of their proposals can be evaluated. It also examines the multiple meanings and functions of “attachment” as this term applies to child–parent and adult affectional relationships, and their association. Their ideas certainly deserve further exploration, especially in the broader context of elucidating the life‐span implications of early attachment within the framework of life history theory.
Evolving Attachment Theory: Beyond Bowlby and Back to Darwin
Authors: Del Giudice Marco , Belsky Jay
Published: July 2010

Abstract— In our reply to M. H. van IJzendoorn and M. J. Bakermans‐Kranenburg (this issue) and R. A. Thompson (this issue), we highlight 2 challenges that attachment researchers face today: (a) closing the gap between the developmental and social psychological traditions and (b) connecting attachment theory to the broader field of evolutionary psychology. We contend that an evolutionary life history approach can contribute to both goals and argue that attachment researchers should consider moving beyond some of Bowlby’s original formulations in order to permit further advancement of the field. Finally, we review van IJzendoorn and Bakermans‐Kranenburg’s criticism of the hypothesis that sex differences in attachment arise in middle childhood; we conclude that the claim that the hypothesis has been falsified is premature and that more research is necessary, thereby making our evolutionary‐inspired view potentially useful for the time being.
Modeling Variability in Individual Development: Differences of Degree or Kind?
Authors: Bauer Daniel J. , Reyes Heathe Luz McNaughton
Published: July 2010

Abstract— It is critical to the progress of developmental science that researchers make proper use of statistical models for analyzing individual change over time. Latent curve models, hierarchical linear growth models, group‐based trajectory models, and growth mixture models are increasingly important tools for longitudinal data analysis. To facilitate their understanding and use, this article clarifies similarities and differences between these models, paying particular attention to the assumptions they make about individual development. An example shows how the results and interpretation vary across model types. The discussion centers on reviewing the strengths and limitations of each approach for developmental research.
Tuning for Performance and Stability in Systems of Nearly Tautochronic Torsional Vibration Absorbers
Authors: Shaw Steven W. , Geist Bruce
Published: July 2010

This paper considers the dynamic response and performance characteristics of a special class of centrifugal pendulum torsional vibration absorbers. The absorbers of interest are designed by selection of the path that their center of mass follows, such that their dynamics are linear or nearly so, out to large amplitudes of motion, thereby avoiding the nonlinear-induced detuning that typically accompanies such responses. These order-tuned, tautochronic or isochronic, absorbers have been the subject of previous investigations, including analyses of the synchronous and certain nonsynchronous responses of systems comprised of a set of identical absorbers. The analysis and experiments have demonstrated that the synchronous response of such absorber systems can experience an instability that results in nonsynchronous responses in which a subset of absorbers have significantly larger amplitude than the corresponding synchronous response. In this study, we present results that generalize these stability results to include absorbers whose dynamics differ slightly from tautochronic by varying the absorber path such that both linear and nonlinear perturbations of perfect tuning are included. It is shown by analysis and verified by simulations that the perfect tuning case is quite special, specifically that the instability described above occurs for tunings very close to ideal and that the synchronous response can be made stable over the entire feasible operating range by employing small levels of linear and/or nonlinear detuning. Such detuning is known to have the additional benefit of resulting in smaller absorber responses and an attendant larger operating range albeit at the expense of absorber performance in terms of attenuating rotor torsional vibrations. The main conclusion of these results is that one can select a very small amount of detuning to avoid this undesirable instability and that such detuning does not have a significant effect on absorber effectiveness. The analytical results derived also provide a quantitative means of predicting synchronous absorber response amplitudes and the associated rotor torsional vibration levels, as well as the stability properties of these responses, results are very useful for the design of absorber systems.
Development of an Active Vibration Isolation System Using Linearized Zero-Power Control With Weight Support Springs
Authors: Hoque Md. Emdadul , Mizuno Takeshi , Kishita Daisuke , Takasaki Masaya , Ishino Yuji
Published: July 2010

This paper presents a hybrid vibration isolation system using linearized zero-power control with weight support springs. The isolation system, fundamentally, is developed by linking a mechanical spring in series with a negative stiffness spring realized by zero-power control in order to insulate ground vibration as well as to reject the effect of on-board-generated direct disturbances. In the original system, the table is suspended from the middle table solely by the attractive force produced by the magnets and therefore, the maximum supporting force on the table is limited by the capacity of the permanent magnets used for zero-power control. To meet the growing demand to support heavy payload on the table, the physical model is extended by introducing an additional mechanism-weight support springs, in parallel with the above system. However, the nonlinearity of the zero-power control instigates a nonlinear vibration isolation system, which leads to a deviation from zero compliance to direct disturbance. Therefore, a nonlinear compensator for the zero-power control is employed furthermore to the system to meet the ever-increasing precise disturbance rejection requirements in the hi-technology systems. The fundamental characteristics of the system are explained analytically and the improved control performances are demonstrated experimentally.
Harmonic Vibrations in Thermoelasticity of Microstretch Materials
Authors: Marin Marin
Published: July 2010

Consider a cylinder made of a microstretch thermoelastic material for which one plane end is subjected to plane boundary data varying harmonically in time. On the lateral surface and other base, we have zero body force and heat supply. By using a Toupin type measure associated with the corresponding steady-state vibration, and by assuming that the angular frequency of oscillations is lower than a certain critical frequency, we show that the amplitude of the vibrations decays exponentially with the distance to the base. This decay estimate is similar to that of the Saint-Venant type.
Development of an Active Compliance Chamber to Enhance the Performance of Hydraulic Bushings
Authors: Arzanpour S. , Golnaraghi M. F.
Published: July 2010

With the new improvements in the fuel economy engines and to enhance the passenger’s comfort, the topic of active vibration cancellation has received a lot of attention recently by both the automotive industry and researchers. Engine mounts and bushings are the devices used to suppress the transverse and tensional vibrations of engines, respectively. Engine mounts and bushings are primarily designed for the first order vibration of engine. Higher order vibrations, however, are neglected due to their lower amplitudes. Although lots of research has been focused on the improvement of the design and performance of engine mounts, engine bushings has not been addressed well in the literature. This paper focuses on the modeling and design of an active bushing, which addresses the higher order vibrations in engines. Such a bushing has a significant advantage in the ride quality of the newly commercialized variable displacement engine (VDE), where the amplitude of vibration induced by switching is higher than normal engines. For VDEs the higher amplitude of vibration makes the higher orders sensible. Isolation of these vibrations is beyond the capabilities of the passive hydraulic bushings. In this paper the design of a novel active chamber is proposed, which is ultimately utilized to control the fluid pressure inside the bushing. It is evident that the fluid pressure significantly contributes to the dynamic performance of the hydraulic bushing. The active chamber described in this paper utilizes a magnetic actuator, excited by electrical current signal, which is fed to a solenoid coil. The pulses produced by the magnetic actuator are used to adjust the pressure at any specific frequency. This feature enables the active chamber not only to alter the frequency response characteristic of the hydraulic bushing, but also to generate complex pressure frequency responses. A mathematical linear model for the magnetic actuator, and the active bushing assembly, is provided and then verified experimentally. The experimental results confirm that the active hydraulic bushing can well address the sophisticated vibration isolation requirements particular to the VDE systems.
Characteristics of the Flow-Induced Vibration and Forces With 1- and 2-DOF Vibrations and Limiting Solid-to-Fluid Density Ratios
Authors: Marzouk Osama A.
Published: July 2010

We studied various characteristics of the flow-induced vibration (FIV) of a spring-mounted cylinder, and the fluctuating lift and drag forces exerted on the cylinder due to the periodic changes in the fluid motion and vortex structure. We compared two conditions, which represent the limiting cases for the solid-to-fluid density ratio: the cylinder density is negligible relative to the fluid density, and the fluid density is negligible relative to the cylinder density. For both conditions, we examined the changes in these characteristics over a wide range of nondimensional mass-damping for one degree of freedom (1-DOF, cross-flow) and 2-DOF (cross-flow and in-line) vibration. The four cases exhibit differences (especially at low mass-damping) but also have some similarities in the characteristics of the FIV, induced forces, and energy extraction from the flow. We examined these differences and similarities, the implied errors when the in-line DOF is neglected, and the feasibility of using a single mass-damping parameter to describe the FIV.
Vibration of a Standing Heavy Column With Intermediate Support
Authors: Wang C. Y.
Published: July 2010

The vibration of a free standing column under its own weight is studied. An intermediate support increases the fundamental frequency. The optimum location for the support is determined for clamped-free, pinned-free, and sliding-free columns. The problem is integrated by a simple accurate initial value method. Approximate and exact relations are also found.
Analytical Solutions for Anisotropic Heat Conduction Problems in a Trimaterial With Heat Sources
Authors: Shen Ming-Ho , Chen Fu-Mo , Hung Shih-Yu
Published: July 2010

In this work, the analytical solution of a fundamental problem of heat conduction in anisotropic medium is derived. The steady-state temperature field in an anisotropic trimaterial subject to an arbitrary heat source is analyzed. “Trimaterial” denotes an infinite body composed of three dissimilar materials bonded along two parallel interfaces. The method of analytical continuation is applied across the two parallel interfaces in order to derive the trimaterial solution in a series form from the corresponding homogeneous solution. A variety of problems, e.g., bimaterial, a finite thin film on a semi-infinite substrate, and a finite strip, can be analyzed as special cases of the present study. The numerical results of the temperature distributions for some practical examples are provided in graphic form and discussed in details.
Effect of Selective Accommodation on Soot Aggregate Shielding in Time-Resolved Laser-Induced Incandescence Experiments
Authors: Daun K. J.
Published: July 2010

Time-resolved laser-induced incandescence is an emerging diagnostic for characterizing primary particle size distributions within soot-laden aerosols. This measurement requires an accurate model of heat conduction between the laser-energized soot and the surrounding gas, which is complicated by the fractal-like structure of soot aggregates since primary particles on the aggregate exterior shield the interior from approaching gas molecules. Previous efforts to characterize aggregate shielding through direct simulation Monte Carlo analysis assume a Maxwell scattering kernel, which poorly represents actual gas/surface interactions. This paper shows how selective thermal accommodation into the translational and rotational modes of the gas molecule influences the aggregate shielding effect using the Cercignani–Lampis–Lord kernel and thermal accommodation coefficients derived from molecular dynamics simulations.
An Experimental Study to Show the Effect of Thermal Stress on Thermal Contact Conductance at Sub-megapascal Contact Pressures
Authors: Misra Prashant , Nagaraju J.
Published: July 2010

Experimental studies are presented to show the effect of thermal stresses on thermal contact conductance (TCC) at low contact pressures. It is observed that in a closed contact assembly, contact pressure acting on the interface changes with the changing temperature of contact members. This change in contact pressure consequently causes variations in the TCC of the junction. A relationship between temperature change and the corresponding magnitude of developed thermal stress in a contact assembly is determined experimentally. Inclusion of a term called temperature dependent load correction factor is suggested in the theoretical model for TCC to make it capable of predicting TCC values more accurately in contact assemblies that experience large temperature fluctuations.
Reacting Turbulent Flow and Thermal Field in a Channel With Inclined Bluff Body Flame Holders
Authors: Lin Cheng-Xian , Holder Richard Jack
Published: July 2010

In this paper, a numerical study has been carried out to investigate the effects of inlet turbulent intensity and angle of attack on the chemically reacting turbulent flow and thermal fields in a channel with an inclined bluff body V-gutter flame holder. With a basic geometry used in a previous experimental study, the inlet turbulent intensity was varied from 2% to 100%, while the angle of attack of the V-gutter was varied from 0 deg to 30 deg. The turbulent flow was modeled with a realizable k-ε two-equation turbulence model. The chemical reaction was premixed propane-air combustion with an equivalence ratio of 0.6. The chemistry-turbulence interaction was simulated with an eddy-dissipation model. Numerical results indicated that increasing the inlet turbulent intensity and V-gutter angle of attack resulted in an increase not only in the size, but also in the magnitude of the downstream high turbulence areas with shedding vortexes. The recirculation flow behind the flame holder tended to maintain the rear wall at constant temperature, except at the edges of the wall. The friction factor of the flow channel was more sensitive to the change in inlet turbulence intensity at smaller angle of attack of the V-gutter.
Heat Flux and Temperature Field Estimation Using Differential Interferometer
Authors: Prasanna S. , Venkateshan S. P.
Published: July 2010

A new methodology based on least-squares approach has been developed to estimate the temperature field from an interferogram recorded using a Differential interferometer (DI). The interferograms are digitally evaluated using two dimensional Fourier transforms to retrieve the temperature gradient field. Temperature field is constructed by fitting a cubic spline to the first derivatives data. The methodology has been applied to both experimental and synthetic interferograms. Both convective heat flux and temperature field were predicted accurately. The role of image noise and errors in the temperature measurements on the temperature field estimation have been studied with the aid of synthetic interferograms.
Heater Size and Gravity Based Pool Boiling Regime Map: Transition Criteria Between Buoyancy and Surface Tension Dominated Boiling
Authors: Raj Rishi , Kim Jungho
Published: July 2010

A pool boiling regime map demarcating the boundary between the surface tension and buoyancy dominated boiling regimes is developed based on heater size and gravity. For large heaters and/or high gravity conditions, boiling is dominated by buoyancy, and the ebullition cycle dominates the contribution to heat transfer. As the gravity level and/or heater size is decreased, surface tension forces become increasingly dominant, and a decrease in heat transfer is observed. The ratio of the heater size Lh (length of a side for a square heater) to the capillary length Lc is found to be a suitable parameter to define the transition criterion between these regimes. Based on the data obtained using FC-72 and pentane, the threshold value of Lh/Lc above which pool boiling is buoyancy dominated was found to be about 2.1. This transition criterion was found to be the same for gravity levels between ∼0g–1.7g and liquid subcoolings between 6.6°C and 26.6°C.
Limiting Length, Steady Spread, and Nongrowing Flames in Concurrent Flow Over Solids
Authors: Tseng Ya-Ting , T’ien James S.
Published: July 2010

A detailed two-dimensional transient model has been formulated and numerically solved for concurrent flames over thick and thin solids in low-speed forced flows. The processes of flame growth leading to steady states are numerically simulated. For a thick solid, the steady state is a nongrowing stationary flame with a limiting length. For a thin solid, the steady state is a spreading flame with a constant spread rate and a constant flame length. The reason for a nongrowing limiting flame for the thick solid is the balance between the flame heat feedback and the surface radiative heat loss at the pyrolysis front, as first suggested by Honda and Ronney. The reason for achieving a steady spread for thin solids is the balance between the solid burnout rate and the flame tip advancing rate. Detailed transient flame and thermal profiles are presented to illustrate the different flame growth features between the thick- and thin-solid fuel samples.
On the Mechanism of Dropwise Condensation of Steam on Ion Implanted Metallic Surfaces
Authors: Rausch Michael H. , Leipertz Alfred , Fröba Andreas P.
Published: July 2010

Our recent experimental studies indicate that nanostructured, chemically inhomogeneous surfaces are the origin of dropwise condensation of steam on ion implanted metals. Yet, the underlying microscopic mechanism governing this special condensation form is still not clear. We suggest a condensation model based on droplet nucleation and growth on elevated precipitates, resulting in short-term steam entrapment after droplet coalescence. According to the wetting theory, this transition state yields increased macroscopic contact angles. Condensation phenomena such as enlarging dropwise condensation areas in spite of increasing condensation rate become comprehensible by our model. Furthermore, it points out that for this special surface type, contact angles and surface free energies measured under ambient air conditions are not usable for predicting the condensation form of steam. Although the suggested microscopic model cannot be directly proved by experiment, its validity is supported by its capability of explaining experimental observations colliding with previous theoretical approaches.
Adaptive Posture Advisory System for Spinal Cord Injury Patient During Long Haul Air Travel
Authors: Tan CheeFai , Chen Wei , Verbunt Marcel , Bartneck Christoph , Rauterberg Matthias
Published: July 2010

Today, air travel is popular as a way of transportation for different purpose such as business and tourism. The numbers of air travel passengers are increasing every year. At the same time the flight distance is increased because of better fuel efficiency and technology advancement of airplanes. Sitting is the most common activity during the flight. The US Department of Health advised the disable people to change their sitting posture frequently to relieve sitting pressures at least every 1 hour, and every 15 minutes for normal people. Decubitus is widely recognized as serious complication for a person with spinal cord injury. Motor paralyses affected a person’s ability to respond unconsciously to potential noxious stimuli. Decubitus affect the quality of life of spinal cord injury patient. For the spinal cord injury patient who travels with long haul flight, which is more than 5 hours, the decubitus risk will increase. The paper describes the development of an adaptive posture advisory system for spinal cord injury passengers. The aim of the system is to reduce the decubitus risk of the spinal cord injury patient during long haul flight.
Finite Element Analysis of the Effect of Oil Jet Peening Process in a Material
Authors: Sahaya Grinspon A. , Gnanamoorthy R.
Published: July 2010

Oil peening is a new surface modification technique developed to introduce compressive residual stresses in metallic components. The magnitude and distribution of residual stresses and plastic strain in the oil peened AA6061-T4 alloy was evaluated using finite element method (FEM). The simulation of single drop impact against a plastically deformable material was performed. The contours of stress components are presented to show the formation of residual stress distribution. Finite element analysis reveals that the stress and strain patterns around the impact region of an oil drop during loading and unloading with different impact pressures. Impact pressure significantly influences the axial displacement, residual pileup and residual stress.
Analytical Investigation of Periodic Solutions for a Coupled Oscillator With Dry Friction
Authors: Pascal Madeleine
Published: July 2010

In this paper, we present an analytical method to investigate the behavior of a two degrees of freedom oscillator excited by dry friction. The system consists of two masses connected by linear springs. These two masses are in contact with a driving belt moving at a constant velocity. The contact forces between the masses and the belt are obtained from Coulomb’s friction laws. A set of periodic solutions involving a global sticking phase followed by several other phases where one or both masses are slipping, are found in close form. Stability conditions related to these solutions are obtained.
Product Performance Validation Life Cycle Management
Authors: Joshi Alhad , Panicker Binu , Lakshminarayana Shashidhar
Published: July 2010

This paper will discuss critical issues and needs in the product performance validation domain. There is a primary need to manage a vast variety of CAE and Test data files that are used and generated throughout the product performance life cycle. The paper will discuss the different elements of managing such data including basic data structures, process and work flow requirements, product validation plans, and security and access privilege considerations. The goal of executing CAE Analysis or performing physical tests is to gather all product performance information. Evaluating all performance measurements specified for the product makes it possible to ensure that the product will behave as specified throughout its service life. The key here is that decision makers need access to all possible performance metrics for a product, an assembly or a component. There is a primary need to manage a vast variety of CAE and Test data files that are used and generated through the product performance life cycle. The paper addresses the different elements of managing such data including basic data structures, process and work flow requirements, product validation plans, security access privilege considerations and data standardization. This paper will also outline how the product validation management system architecture can support all the needs of this domain. The principal elements of the system include the supporting data structures that are mapped to a database management system and access methods using a service-oriented architecture (SOA).
Shape Optimization of Multi-Chamber Mufflers With Plug-Inlet Tube on a Venting Process by Genetic Algorithms
Authors: Chiu Min-Chie
Published: July 2010

Research on new techniques of single-chamber plug-inlet mufflers has been addressed. However, research work on shape optimization of multi-chamber plug-inlet mufflers along with work on the maximal back pressure has been neglected. Therefore, a numerical case for eliminating a broadband steam blow-off noise using multi-chamber plug-inlet mufflers in conjunction with genetic algorithm (GA) as well as numerical decoupling technique under space-constrained pressure drop is introduced in this paper. To verify the liability of GA optimization, optimal noise abatements for various pure tones on a one-chamber plug-inlet muffler are exemplified. Also, the accuracy of the mathematical model has to be checked by experimental data. Results indicate that the maximal sound transmission losses are precisely located at the desired target tones. Consequently, both the pressure drop and the acoustical performance will be increased when the diameters (at inlet tubes and perforated holes), the perforated ratio, and the length of perforated tube decrease.
Using a Vibration Absorber to Suppress Chatter Vibration in Turning Process With a Worn Tool
Authors: Moradi Hamed , Bakhtiari-Nejad Firooz , Movahhedi Mohammad R.
Published: July 2010

Dynamic vibration absorbers are used as semi-active controllers to reduce the undesirable vibrations in many applications such as electrical transmission lines, helicopters, gas turbines, engines, bridges and etc. One type of these absorbers is tunable vibration absorber (TVA). In this paper, regenerative chatter in an orthogonal turning process is suppressed using a (TVA). It is shown that TVA can modify the frequency response function of the cutting tool so as to improve cutting stability in turning process. In addition, tool wear is an important factor which works as a positive damping and helps the chatter suppression beside exertion of the TVA. Finally, using the SIMULINK Toolbox of MATLAB, the analog simulated block diagram of the problem is developed. The advantage of this simulation is that, one can analyze the effect of other types of excitations such as step, ramp, etc on the absorbed system.
Fuzzy Wavelet Neural Network Control for Coordinated Motion of Free-Floating Space Manipulator System in Joint Space
Authors: Dengfeng Huang , Li Chen
Published: July 2010

The dynamic control for coordinated motion of free-floating space manipulator system in joint space is discussed. According to the geometrical relationship and the linear momentum conservation law, the dynamic equations of space manipulator system are established through Lagrange equation of the second kind. Based on the above, a fuzzy wavelet neural network scheme is designed to control the base’s attitude and the joint angle of manipulator to track desired trajectories synchronously in joint space. The control scheme needs neither linearly parameterize the dynamic equations of the system, nor know any dynamic parameters. Moreover, its network weight is learning by back propagation algorithm online so the training time is saved. Numerical simulations are presented to verify the feasibility and effectiveness of the proposed control scheme.
Design of an Automotive Gateway for In-Vehicle Networks
Authors: Seo Suk-Hyun , Kim Jin-Ho , Kwon Key Ho , Jeon Jae Wook , Hwang SungHo
Published: July 2010

This paper presents the requirements of an automotive gateway for in-vehicle networks. Modern vehicles include several heterogeneous networks such as LIN, CAN, FlexRay, and MOST. The gateway enables seamless communication between heterogeneous networks. The role of a gateway is not complex, but the gateway has the potential to damage the operation of other connected electronic control units and networks. In this paper, we analyze the requirements for the automotive gateway from the viewpoint of hard real-time embedded systems in automotive distributed control systems. We implement the gateway based on these requirements. Finally, we evaluate the performance of the gateway.
On the Stability Properties of a Periodically Forced, Time-Varying Mass System
Authors: van Horssen W. T. , Pischanskyy O. V. , Dubbeldam J. L. A.
Published: July 2010

In this paper the forced vibrations of a linear, single degree of freedom oscillator (sdofo) with a time-varying mass will be studied. The forced vibrations are due to small masses which are periodically hitting and leaving the oscillator with different velocities. Since these small masses stay for some time on the oscillator surface the effective mass of the oscillator will periodically vary in time. Not only solutions of the oscillator equation will be constructed, but also the stability properties, and the existence of periodic solutions will be discussed.
Nonlinear Vibration and Control of Piezoelectric Laminates
Authors: Chen Li-hua , Liu Chang-Liang , Zhang Wei , Fan Jin-hong
Published: July 2010

In this paper, the dynamic behavior of piezoelectric laminates is investigated. Thin piezoelectric layers are assumed to be embedded on the top and the bottom surfaces of the rectangular plate. The top and the bottom layers are taken as the actuator and sensor, respectively. Based on Von Karman theory, the geometrically nonlinear relation between strain and displacement is proposed and basic large deformation equations are established. Nonlinear dynamic equations of piezoelectric laminates are formulated using Hamilton’s principle. The Galerkin’s approach is applied to partial differential equations to obtain the ordinary differential equations. The numerical results show the existence of periodic, bifurcation and chaotic motions for the laminated piezoelectric rectangular plate with the changes of frequency and amplitude of forcing loads. Furthermore we can control the vibration of the piezoelectric laminates using a constant gain velocity minus control algorithm. Using the control gain, the free vibration of the plate is damped out more quickly, and the nonlinear dynamic behavior varies from the system without control. Finally, a numerical simulation example shows that the method suggested in this paper is effective and simply.
A Preliminary Investigation Into Geometric and Spatial Characteristics of Interacting Fields for Shipboard CP Systems
Authors: DeGiorgi V. G. , Wimmer S. A.
Published: July 2010

Electrical fields generated from cathodic protection systems occur not only on the structure’s surface but in the surrounding electrolyte. The value of off-board and on-board fields are determined by the combined effects of strength and spatial orientation of sources and sinks on the structure and in the surrounding region. Typically shipboard ICCP system analysis, either computational or experimental, deals with a single ship far from any sources and sinks that are not directly attached to the ship structure. In this work the authors use boundary element methods to generate preliminary analyses of the effects of a source in the surrounding media on both the calculated fields on the structure and the off-board fields measured near the structure. This work is scoping analyses designed to help design experimental work investigating the effects of off-board sources.
Design of “Figure-8” Spherical Motion Flapping Wing for Miniature UAV
Authors: Rehmat Zohaib , Roll Jesse , Lee Joon S. , Yim Woosoon , Trabia Mohamed B.
Published: July 2010

Hummingbirds and some insects exhibit a “Figure-8” flapping motion, which allows them to undergo variety of maneuvers including hovering. It is therefore desirable to have miniature air vehicle (FWMAV) with this wing motion. This paper presents a design of a flapping-wing for FWMAV that can mimic “Figure-8” motion using a spherical four bar mechanism. In the proposed design, the wing is attached to a coupler point on the mechanism, which is driven by a DC servo motor. A prototype is fabricated to verify that the design objectives are met. Experimental testing was conducted to determine the validity of the design. The results indicate good correlation between model and experimental prototype.
Study on Nonlinear Vibration and Dynamic Characteristics of Rigid Rotor Roller Bearing System
Authors: Cui Li , Liu Changli , Zheng Jianrong
Published: July 2010

Rotor system supported by roller bearing displays complicated nonlinear behavior due to nonlinear Hertzian contact force of roller bearing. In this paper, nonlinear bearing forces of roller bearing under four-dimensional loads are given, and four-DOF dynamic equations of rotor roller bearing system are established. The Newmark-β method and Newton-Raphson method are used to solve the nonlinear equations. In order to obtain accurate analysis data, the dynamic characteristics of rotor roller bearing system are computed considering coupling of bearing and rotor system. Finally, the critical speed of the rotor roller bearing system and axis orbit of the rotor are measured on a rotor bearing test bench, which are compared with the analysis results. The results demonstrate that the model and methods put forward in this paper to forecast the characteristics of rotor roller bearing system are precise.
Control Concepts of Semi-Active Friction Dampers
Authors: Gaul Lothar , Becker Jens
Published: July 2010

Reduction of structural vibrations is of major interest in mechanical engineering for lowering sound emission of vibrating structures, improving accuracy of machines and increasing structure durability. Besides design optimization and passive damping treatments, active structural vibration control can be applied to reduce unwanted vibrations. In this contribution, two semi-active control laws for control of friction dampers are derived and investigated in simulations and experiments. Thereby, semi-active control concepts have the advantage over active control to yield intrinsically stable closed-loop systems and low energy consumption. In the experimental implementation, the control makes use of piezoelectric stack actuators to apply adjustable normal forces between structure and attached friction dampers. The control uses an observer based on reduced finite-element models to estimate the unknown relative displacement beneath the normal force actuator from acceleration measurements. Experimental results of the control algorithms for a structure with attached friction damper show the effectiveness of the proposed control algorithms.
Using MatCont in a Two-Parameter Bifurcation Study of Models for Cell Cycle Controls
Authors: Govaerts Willy , De Witte Virginie , Kheibarshekan Leila
Published: July 2010

A recent application field of bifurcation theory is in modelling the cell cycle. We refer in particular to the work of J.J. Tyson and B. Novak where the fundamental idea is that the cell cycle is an alternation between two stable steady states of a system of kinetic equations. We study and extend the basic model of Tyson and Novak using the Matlab numerical bifurcation software MatCont, in a two-parameter setting and highlight several new features. We show that the limit point curves in the two-variable model behave in an ungeneric way under variation of the natural parameters and that the hysteresis loop in the model is not the usual loop caused by the existence of a codimension-2 cusp point. We continue orbits homoclinic-to-saddle-node (HSN) in the three-variable model and find that these orbits die in a non-central orbit homoclinic-to-saddle-node under a natural parameter variation. As an extension we introduce a model in which cell division appears as a continuous-in-time limit cycle. We perform a continuation of this limit cycle under a natural parameter variation and show that it loses stability in a limit point of cycles bifurcation. Alternatively, we study the cell cycle as a boundary value problem as proposed by Tyson and Novak. This leads to an interpretation of the cell as a slow-fast system and we derive several conclusions on the relation between the growth rate of the cells and the cell size at division, and on the controllability of the process.
A Theory for Nonlinear Webs
Authors: Luo Albert C. J.
Published: July 2010

This paper presents a nonlinear theory for webs. Because the webs cannot resist any compressive forces, the initial configuration is selected on the inextensible web. From a different point of view, the nonlinear theory for webs is presented, including network non-continuum webs, fabric non-continuum webs and continuum webs.
Application of Fractional Calculus in Reservoir Characterization From Pressure Transient Data in Fractal Reservoir With Phase Redistribution
Authors: Mishra Asha S.
Published: July 2010

The present paper describes the use of pressure derivative and second derivative of integral of pressure in a fractal reservoir with matrix participation with phase redistribution in a geological environment that are not possible by conventional techniques. The analysis of this type of data in reservoir characterization is known as “inverse problem” and one can obtain information about interwell and vertical permeability distribution in a reservoir. The fractal geometry in a dynamic pressure transient tests data plays a very vital role for heterogeneity characterization. The pressure transient response is analyzed for flow in a connected fracture network and fracture with matrix participation. The computer aided matching technique for both pressure and its derivative by nonlinear regression techniques are used in estimating the reservoir properties from measured drawdown/buildup and falloff pressure data of heterogeneous reservoir. In the present paper the fractional calculus approach has been utilized to solve the diffusivity equation with phase redistribution in fractal reservoir. The pressure solution of the diffusivity is in terms of Laplace space and its analytical inversion is not possible. We have obtained numerically inversion of the problem and the pressure, pressure derivative, integral of pressure and its first and second derivative has been calculated. The permeability estimated from pressure transient test data of a well are in good agreement with the identified the geological model.
Stability and Bifurcation Analysis of a Rotating Beam Substructured Model
Authors: Garci´a Vallejo Daniel , Valverde Garci´a Juan S.
Published: July 2010

One of the most well-known situations in which nonlinear effects must be taken into account to obtain realistic results is the rotating beam problem. This problem has been extensively studied in the literature and has even become a benchmark problem for the validation of nonlinear formulations. The substructuring technique was proven to be a valid strategy to account for this problem. The earliest developments of the absolute nodal coordinate formulation were focused on the use of a substructured schem, in which each element uses a local element frame for the elastic force implementation. Later on, the similarities between the absolute nodal coordinate formulation and the substructuring technique were demonstrated in the literature. In a recent study of the rotating beam, it was found the existence of a critical angular velocity, beyond which the system becomes unstable, that was dependent on the number of substructures. Since the dependence of the critical velocity was not so far clear, this paper tries to shed some light on it. Moreover, previous studies were focused on a constant angular velocity analysis where the effects of Coriolis forces were neglected. In this paper, the influence of the Coriolis force term is not neglected. The influence of the reference conditions of the element frame are also investigated in this paper.
Development of a Uniaxial Cyclic Stretch Apparatus for Tissue Engineering
Authors: Pang Qiming , Zu Jean W. , Siu Geoffrey M. , Li Ren-Ke
Published: July 2010

A uniaxial cyclic stretch apparatus is designed and developed for tissue engineering research. The biostretch apparatus employs non-contact electromagnetic force to uniaxial stretch a rectangular Gelfoam® or RTV silicon scaffold. A reliable controller is implemented to independently control four stretch parameters: strength, frequency, pattern, and duration of the stretch time. The non-contact driving force and the specially designed mounting tray allow researchers to use standard Petri dishes and commercially available CO2 incubators to culture an engineered tissue patch with mechanical stimulus. The apparatus greatly simplifies the culture process over existing biostretch apparatuses. Further, unlike traditional uniaxial stretch apparatuses, which normally fix one side and stretch other side, the new biostretch apparatus can also apply uniaxial stretch from both ends simultaneously. Using the biostretch apparatus, the distribution of strain on the Gelfoam® and GE RTV 6166 silicon scaffold is quantitatively analyzed.
Response Dynamics in the Continuum Limit of the Lattice Dynamical Theory of Viscoelasticity (Fractional Calculus Approach)
Authors: Narahari Achar B. N. , Hanneken John W.
Published: July 2010

A fractional diffusion-wave equation is derived in the continuum limit of the lattice dynamical equations of motion of a chain of coupled fractional oscillators obtained from the integral equations of motion of a linear chain of simple harmonic oscillators by generalization of the ordinary integrals into ones involving fractional integrals. The set of integral equations of motion pertaining to the chain of coupled fractional oscillators in the continuum limit is solved by using Laplace transforms. The response of the system to impulse and sinusoidal forcing is studied. Numerical applications are discussed with particular reference to energy flow and dissipation.
Uncertainties in Drill Dynamics: The Role of a Random Weight-on-Hook
Authors: Ritto T. G. , Soize C. , Sampaio R.
Published: July 2010

A drill-string is a slender structure that turns and drills into the rock in search of oil. This paper aims to investigate uncertainties on the weight-on-hook, which is the supporting force exerted by the hook at the top. In a drilling operation there are three parameters that can be continuously controlled: (1) the weight-on-hook, (2) the drilling fluid inlet velocity and (3) the rotational speed of the rotary table. The idea is to understand how the performance of the system (which is measured by the rate-of-penetration) if affected when the weight-on-hook is considered uncertain. A numerical model is developed using the Timoshenko beam theory and discretized by means of the Finite Element Method. The nonlinear dynamics presented includes bit-rock interaction, fluid-structure interaction and impacts. The probability theory is used to model the uncertainties. To construct the probability density function of the random variable, the Maximum Entropy Principle is employed, so that the probability distribution is derived from the mechanical properties of the weight-on-hook.
Nonlinear Oscillation and Stability Analysis of the Turning Process With a Worn Tool
Authors: Moradi Hamed , Ahmadian Mohammad T. , Bakhtiari-Nejad Firooz
Published: July 2010

Self-excited and forced vibrations are important topics in machining processes because their occurrence results in poor surface finish, increase in tool wear and hampers productivity. In this paper, turning process is modeled as a SDOF dynamic system including quadratic and cubic structural nonlinearities. The effect of tool flank wear, as a contact force between the work-piece and tool, is addressed vigorously. Multiple scale method is used to find the solution of the nonlinear dynamic equation including regenerative chatter, forced excitation and tool wear. It is shown that, width of cut can be considered as the bifurcation parameter of the system. Primary, super-harmonic and sub-harmonic resonance situations are discussed. Specifically, under super-harmonic resonance, turning process shows interesting behavior. Finally, stability of the steady state motion is investigated in terms of tool wear length, width of cut and spindle rotational speed. Results are compared for two distinct cases: system with fresh and worn tools.
Rayleigh-Ritz Analysis of Vibrating Plates Based on a Class of Eigenfunctions
Authors: Catania Giuseppe , Sorrentino Silvio
Published: July 2010

In the Rayleigh-Ritz condensation method the solution of the equation of motion is approximated by a linear combination of shape-functions selected among appropriate sets. Extensive literature dealing with the choice of appropriate basis of shape functions exists, the selection depending on the particular boundary conditions of the structure considered. This paper is aimed at investigating the possibility of adopting a set of eigenfunctions evaluated from a simple stucture as a general basis for the analysis of arbitrary-shaped plates. The results are compared to those available in the literature and using standard finite element analysis.
On Stability of Periodic Motions in a Switching System With Multiple Subsystems
Authors: Luo Albert C. J. , Wang Yang
Published: July 2010

In this paper, the stability and bifurcation of periodic flows in a switching system of multiple subsystems with transport laws at switching points is investigated. The linear switching systems used as an example for illustration. Analytical prediction and numerical illustrations of periodic flows in linear switching systems are carried out for a better understanding of dynamical behaviors of switching systems. The effects of the transport laws in the switching systems are also discussed.