bluuebunny/crossref_metadata_2025 huggingface dataset:
Wave Propagation in Two-Dimensional Nonlinear Periodic Lattices
Authors: Narisetti Raj K. , Ruzzene Massimo , Leamy Michael J.
Published: July 2010

This paper investigates wave propagation in two-dimensional nonlinear periodic structures subject to point harmonic forcing. The infinite lattice is modeled as a springmass system consisting of linear and cubic-nonlinear stiffness. The effects of nonlinearity on harmonic wave propagation are analytically predicted using a novel perturbation approach. Response is characterized by group velocity contours (derived from phase-constant contours) functionally dependent on excitation amplitude and the nonlinear stiffness coefficients. Within the pass band there is a frequency band termed the “caustic band” where the response is characterized by the appearance of low amplitude regions or “dead zones.” For a two-dimensional lattice having asymmetric nonlinearity, it is shown that these caustic bands are dependent on the excitation amplitude, unlike in corresponding linear models. The analytical predictions obtained are verified via comparisons to responses generated using a time-domain simulation of a finite two-dimensional nonlinear lattice. Lastly, the study demonstrates amplitude-dependent wave beaming in two-dimensional nonlinear periodic structures.
A Framework for Uncertainty Quantification in Nonlinear Multi-Body System Dynamics
Authors: Datar M. , Negrut D. , Gorsich D. , Lamb D.
Published: July 2010

This paper outlines a methodology for determining the statistics associated with the time evolution of a nonlinear multi-body dynamic system operated under input uncertainty. The focus is on the dynamics of ground vehicle systems in environments characterized by multiple sources of uncertainty: road topography, friction coefficient at the road/tire interface and aerodynamic force loading. Drawing on parametric maximum likelihood estimation, the methodology outlined is general and can be applied to systematically study the impact of sources of uncertainty characterized herein by random processes. The proposed framework is demonstrated through a study that characterizes the uncertainty induced in the loading of the lower control arm of an SUV type vehicle by uncertainty associated with road topography.
Resonance Suppression in Multi-DOF Rotating Flexible Structures Using Order-Tuned Absorbers
Authors: Gozen Serif , Olson Brian J. , Shaw Steven W. , Pierre Christophe
Published: July 2010

This paper considers the dynamic response and order-tuning of vibration absorbers fitted to a rotating flexible structure under traveling wave (TW) engine order excitation. Of specific interest is the extension of previous results on the so-called no-resonance zone, that is, a region in linear tuning parameter space in which the coupled structure/absorber system does not experience resonance over all rotation speeds. The no-resonance feature was shown to exist for cyclic rotating structures with one structural and one absorber degree-of-freedom (DOF) per sector. This work uses a higher-fidelity structural model to investigate the effects of higher modes on the cyclically-coupled system. It is shown that the no-resonance zone is replaced by a resonance-suppression zone in which one structural mode is suppressed, but higher-order resonances still exist with the addition of the absorbers. The results are general, in the sense that one vibration mode can be eliminated using a set of identically-tuned absorbers on a rotating structure with arbitrarily many DOFs per sector.
Diagnosis and Treatment of Bowed, Misalign, and Eccentric Rotor Trains
Authors: Hidalgo Juan , Racic Zlatan
Published: July 2010

The intention of this paper is to demonstrate the advantages and the economic benefits of vibration root cause analysis and diagnosis, proper treatment of rotors during service outage, and follow up after commissioning of the units versus the general industry approach of field balance all vibration problems. During the course of the paper several diagnostic tools and repair procedures will be introduced and discussed. Special enfaces is made in the identification and treatment of rotor’s bows, misalignments, and eccentricities since they represent the most common and less recognized vibration root cause. A case study will be used as a guide to facilitate the comprehension and to illustrate real industry results that can be achieved by systematically following the proposed methodology.
Shoji: A Communication Terminal for Sending and Receiving Ambient Information
Authors: Shuzo Masaki , Shimura Makoto , Delaunay Jean-Jacques , Yamada Ichiro
Published: July 2010

In modern Japan, increased human mobility has resulted in many people being geographically separated from their families and friends. There thus exists a need for communication devices that provide a link between geographically separated family members and friends. Although there are two types of communication, instrumental and consummatory, few studies have been conducted on the latter. We have developed a communication terminal that uses the exchange of ambient information as a means to promote consummatory communication. A concept for effectively communicating ambient information was derived from data collected from questionnaires. This concept was used to develop a communication terminal called “Shoji” that can send and receive ambient information such as the temperature, illumination, light color temperature, and noise level as well as information about the presence or absence of individuals, their movements, and their emotions. We evaluated it experimentally. The participants were parents and children living apart. They judged that the information was sufficiently expressed, which indicates that the terminal is useful for exchanging ambient information.
Nonlinear Dynamic Modeling of Elastic Beam Fixed on a Moving Cart and Carrying Lumped Tip Mass Subjected to External Periodic Force
Authors: Ghaith Fadi A.
Published: July 2010

In the present work, a Bernoulli – Euler beam fixed on a moving cart and carrying lumped tip mass subjected to external periodic force is considered. Such a model could describe the motion of structures like forklift vehicles or ladder cars that carry heavy loads and military airplane wings with storage loads on their span. The nonlinear equations of motion which describe the global motion as well as the vibration motion were derived using Lagrangian approach under the inextensibility condition. In order to investigate the influence of the axial movement of the cart on the response of the system, unconstrained modal analysis has been carried out, and accurate mode shapes of the beam deflection were obtained. The assumed mode method was utilized for approximating the beam elastic deformation based on the single unconstrained mode shapes. Numerical simulation has been carried out to estimate the open-loop response of the nonlinear beam-mass-cart model as well as for the simplified linear model under the influence of the periodic excitation force. Also a comparison study between the responses of the linear and nonlinear models was established. It was shown that the maximum values of the beam tip deflection estimated from the nonlinear model are lower than the corresponding values obtained via the linear model, which reveals the importance of considering nonlinear hardening term in formulating the equations of motion for such system in order to come with more accurate and reliable model.
Non-Markovian Reinforcement-Based on Self-Optimizing Memory Controller
Authors: Osman Hassab Elgawi
Published: July 2010

This paper contributes on designing robotic self-optimizing memory controller for non-Markovian reinforcement tasks. Rather than holistic search for the whole memory contents the model adopts associated feature analysis to successively memorize a newly event state-action pair as an action of past experience. Actor-Critic learning is used to adaptively tuning the control parameters, while on-line variant of random forests (RF) learner is used as memory-capable to approximate the policy of Actor and the value function of Critic. Learning capability of the proposed model is experimentally examined through non-markovian cart-pole balancing task. The result shows that our self-optimizing memory controller acquired complex behaviors such as balancing two poles simultaneously, displays long-term planning and generalization capacity based on past experiences.
Data Handling With Two Independent Variables and the Bezier Filter
Authors: Venkataraman P.
Published: July 2010

Bezier functions of two independent variables are excellent vehicles for three dimensional data reduction that require preservation of derivative content. They can be applied to both smooth and noisy data. They represent the original data with good fidelity. The approximation is smooth and continuous to a high degree. The coefficients of the approximating Bezier function are obtained through a non iterative algebraic relation. These coefficients can replace the original data leading to significant data reduction. The Bezier function also allows the data over the entire domain to be represented by simple bivariate polynomials in two parameters. This continuous representation allows easy extraction of gradient and higher derivative information about the data. The first two examples demonstrate the technique using smooth data. Using random perturbation on these examples, two additional examples are generated to represent noisy data. It is shown that the underlying original smooth data can be recognized using the same algorithm. This process is recognized as the Bezier filter in this paper. These examples illustrate that the Bezier functions are excellent for data approximation, reduction, transformation, and smoothing. The Bezier function is global over all of the data so that any interpolated data have the same properties as the rest of the data. The examples establish two important properties in the use of Bezier functions for data analysis. The mean of the original data and the approximate data using Bezier function are the same. Large orders of polynomials can be used without significant distortion in the approximation.
Solving Inverse ODE Using Bezier Functions
Authors: Venkataraman P.
Published: July 2010

The simplest inverse boundary value problem is to identify the differential equation and the boundary conditions from a given set of discrete data points. For an ordinary differential equation, it would involve finding a function, which when expressed through some function of itself and its derivatives, and integrated using particular boundary conditions would generate the given data. Parametric Bezier functions are excellent candidates for these functions. They allow efficient approximation of data and its derivative content. The Bezier function is smooth and continuous to a high degree. In this paper the best Bezier function to fit the data represents this function which is being sought. This Bezier approximation also determines the boundary conditions. Next, a generic form of the differential equation is assumed. The Bezier function and its derivatives are then used in this generic form to establish the exponents and coefficients of the various terms in the actual differential equation. The paper looks at homogeneous ordinary differential equations and shows it can recover the exact form of both linear and nonlinear differential equations. Two examples are presented. The first example uses data from the Bessel equation, representing a linear equation. The second example uses the data from the Blassius equation which is nonlinear. In both cases the exact form of the equation is identified from the given discrete data.
Dynamic Analysis of a Motion Transformer Mimicking a Hula Hoop
Authors: Lu C. X. , Wang C. C. , Sung C. K. , Chao Paul C. P.
Published: July 2010

Hula-hoop motion refers to the spinning of a ring around a human body; it is made possible by the interactive force between the moving ring and the body. Inspired by the generic concept of hula-hoop motion, this study proposes a novel motion transformer design that consists of a main mass sprung in one translational direction and a free-moving mass attached at one end of a rod, the other end of which is hinged onto the center of the main mass. It is expected that the transformer is capable of transforming linear reciprocating motion into rotational motion. In addition, the transformer could be integrated with coils, magnets, and electric circuits to form a portable energy scavenging device. A thorough dynamic analysis of the proposed transformer system is conducted in this study in order to characterize the relationships between the varied system parameters and the chance of hula-hoop motion occurrence. The governing equations are first derived by using Lagrange’s Method, which is followed by the search for steady-state solutions and the corresponding stability analysis via the homotopy perturbation method and Floquet theory. Direct numerical simulation is simultaneously performed to verify the correctness of the approximate analysis. In this manner, the feasibility of the proposed design and the occurrence criteria of hula-hoop motion are assessed.
Use of General Nonlinear Material Models in Beam Problems: Application to Belt and Rubber Chains
Authors: Maqueda Luis G. , Mohamed Abdel-Nasser A. , Shabana Ahmed A.
Published: July 2010

Accurate modeling of many engineering systems requires the integration of multibody system and large deformation finite element algorithms that are based on general constitutive models, account for the coupling between the large rotation and deformation, and allow capturing coupled deformation modes that cannot be captured using beam formulations implemented in existing computational algorithms and computer codes. In this investigation, a new nonlinear finite element dynamic model for the analysis of three-dimensional rubber chains and belt drives is developed using the finite element absolute nodal coordinate formulation (ANCF) that allows for a straight forward implementation of general linear and nonlinear material models for structural elements such as beams, plates and shells. Furthermore, this formulation, which is based on a more general kinematic description, can be used to predict the cross section deformation and its coupling with the extension and bending of the belt drives and rubber chains. The ANCF cross section deformation results are validated by comparison with the results obtained using solid finite elements in the case of a simple tension test problem. The effect of the use of different linear and nonlinear constitutive laws in modeling belt drives mechanism is also examined in this investigation. The finite element formulation presented in this paper is implemented in a general purpose three-dimensional flexible multibody algorithm that allows for developing detailed models of mechanical systems subject to general loading conditions, nonlinear algebraic constraint equations, and arbitrary large displacements that characterize belt drives and tracked vehicle dynamics. The successful integration of large deformation finite element and multibody system algorithms is shown to be necessary in order to be able to study the dynamics of complex tracked vehicles with rubber chains. A computer simulation of a three-dimensional multibody tracked vehicle model that consists of twenty rigid bodies and two flexible rubber chains is used in order to demonstrate the use of the formulations presented in this investigation.
Classification of Delamination and Matrix Cracking in Carbon Fibre Composite Plates Using Acoustic Emission (AE)
Authors: Aljets Dirk , Chong Alex , Wilcox Steve , Holford Karen , Pullin Rhys , Eaton Mark
Published: July 2010

Recent publications show that there is an increasing interest in the aircraft industry in monitoring the actual condition of a structure in real time and while the structure is in service. It is hoped that this Structural Health Monitoring (SHM) could make some regular inspections unnecessary and allow maintenance only when required. This is particularly important for CFRP structures for which aircraft manufacturers are increasingly interested. For these new composite structures where the experience of fatigue failure is relatively low, this technique could potentially be economical and improve the safety of the structures. Acoustic Emission is reported to be sensitive to the four failure types in composite materials, namely matrix cracking, delamination, debonding and fibre fracture. These failure modes can have different impacts on structural integrity and it is therefore of interest to identify these failure types before further maintenance steps are conducted. This report discusses different features in AE signals which can be used to identify the actual flaw type. These features were then applied to AE data collected from two different experiments on carbon fibre composite plates. These experiments were designed to induce the two different failure modes of matrix cracking and delamination. The data collected was used to train a neural network to recognise the two failure modes.
Effect of the Spatial Extent of the Control in a Bilinear Control Problem for the Schroedinger Equation
Authors: Kime Katherine A.
Published: July 2010

We consider control of the one-dimensional Schroedinger equation through a time-varying potential. Using a finite difference semi-discretization, we consider increasing the extent of the potential from a single central grid-point in space to two or more gridpoints. With the differential geometry package in Maple 8, we compute and compare the corresponding Control Lie Algebras, identifying a trend in the number of elements which span the Control Lie Algebras.
Design and Reconfiguration Algorithm of HexBot: A Modular Self-Reconfigurable Robotic System
Authors: Sadjadi Hossein , Mohareri Omid , Al-Jarrah Mohammad Amin , Assaleh Khaled
Published: July 2010

This paper primarily addresses the design and implementation of a planar hexagonal Modular Self-Reconfigurable Robotic System (MSRRS) along with the construction of its reconfiguration path planner and control algorithm. A universal module is carefully designed to be in line with the common goals of MSRRS including homogeneity, cost-effectiveness, fast actuation and quick and strong connections. Although the implemented working prototype is both large and restricted to a planar geometry, it is designed such that its hardware and software can be scaled up in the number of units and down in unit size; similarly, the platform has the potential to be extended for 3D applications. The software infrastructure of this platform is designed in a way that different hierarchies for distributed control and communication can be implemented. The algorithmic design is based on a hierarchical multilayer approach, where upper layers decompose the problem into sub-problems solvable by lower layers. An optimal reconfiguration path planner is developed to minimize the number of module movements during the reconfiguration while enforcing collision avoidance and connectivity constraints in addition to taking into account the kinematic model of the platform. The core of the algorithm relies on a heuristic function and a Markov Decision Process (MDP) optimization to generate a near-optimal reconfiguration path planner and a control algorithm for HexBot shown in Figure 1, a lattice, homogenous, rigid, planar hexagonal MSRRS. Among several novel approaches incorporated in this system, multilayer nature of both hardware and software design provides openness, flexibility and ease of modification or adaptation for other platforms. In this approach each layer is dedicated to perform a specific task and can be modified or enhanced separately while keeping the remaining layers untouched.
Dynamics of a Piecewise-Linear Oscillator With Limited Power Supply
Authors: de Souza Silvio L. T. , Caldas Ibereˆ L. , Balthazar Jose´ M. , Brasil Reyolando M. L. R. F.
Published: July 2010

We discuss dynamics of a vibro-impact system consisting of a cart with an piecewise-linear restoring force, which vibrates under driving by a source with limited power supply. From the point of view of dynamical systems, vibro-impact systems exhibit a rich variety of phenomena, particularly chaotic motion. In our analyzes, we use bifurcation diagrams, basins of attractions, identifying several non-linear phenomena, such as chaotic regimes, crises, intermittent mechanisms, and coexistence of attractors with complex basins of attraction.
Contact Force Models and Dynamics of a Drifting Oscillator
Authors: Ajibose Olusegun K. , Wiercigroch Marian , Pavlovskaia Ekaterina , Akisanya Alfred R.
Published: July 2010

The modelling of vibro-impact systems used in industry requires accurate description of the contact force between its impacting members. In this paper, the influence of contact force models on the global and local dynamics of a drifting oscillator is investigated. Three contact force models are examined in this study, namely: the Kelvin-Voigt (KV), the Hertz stiffness (HS) and the nonlinear contact stiffness and damping (NSD) models. Analysis of the considered system reveals that the local and global dynamic behaviour depend on the choice of contact force model. The short-term (local) dynamic response for the system are almost identical for all the three models. However, results for the long-term (global) dynamics of the system depend on the choice of contact force model; while the results for HS model are topologically similar to those of the KV model, the corresponding results for NSD are different from the other two models.
Stochastic Modeling of Damage Physics for Mechanical Component Prognostics Using Condition Indicators
Authors: He David , Li Ruoyu , Bechhoefer Eric
Published: July 2010

The health of a mechanical component deteriorates over time and its service life is randomly distributed and can be modeled by a stochastic deterioration process. For most of the mechanical components, the deterioration process follows a certain physical laws and their mean life to failure can be determined approximately by these laws. However, it is not easy to apply these laws for mechanical component prognostics in current health monitoring applications. In this paper, a stochastic modeling methodology for mechanical component prognostics with condition indicators used in current health monitoring applications is presented. The effectiveness of the methodology is demonstrated with a real shaft fatigue life prediction case study.
Comparing Kinematic and Dynamic Hand Models for Interactive Grasping Simulation
Authors: Rusa´k Zolta´n , Antonya Csaba , Horva´th Imre , Talaba Doru
Published: July 2010

This paper compares two approaches to controlling virtual hands in grasping simulation, and it investigates the ability of humans to control with their hands a virtual hand model in manipulative tasks. In our setup, the users are following their interaction in a desktop virtual reality environment, in order to determine the feasibility of user studies for user – virtual product interaction. Because no real force feed-back is provided, the user can decide upon the correctness of the grasping posture only from visual feedback. The hand and the virtual object interaction are computed from a simulation, therefore accurate spatial position of the real hand and fingers are needed to be measured in real time. Our simulation program is using the Nvidia PhysX SDK. We have implemented two control mechanisms, which enables the users of the system to manipulate the virtual hand. The first mechanism controls the motion of the virtual hand and grasping forces based on the principles of kinematics and energy transfer by contact simulation. The second mechanism relies on the principles of multibody dynamics, controlling the motion of the hand by PD controllers, and applying joint torques to the hand in order to exert forces on the grasped object. In this paper, we compare how well these principles perform in (a) accurately moving the virtual hand in the simulation space, (b) accurately positioning the fingers on the grasped objects, and (c) controlling the grasping forces on the objects.
Dynamics and Control of Crane Payloads That Bounce and Pitch During Hoisting
Authors: Yoon Jisup , Singhose William , Vaughan Joshua , Ramirez Gabriel , Kim Michael , Tawde Sujay
Published: July 2010

The natural sway of crane payloads is detrimental to safe and efficient operation. Most crane control research has focused on oscillation induced by motion of the overhead trolley that is perpendicular to the vertical suspension cables. Little consideration has been given to bouncing oscillation in the hoist direction and pitching oscillation with respect to mass center of the payload. These dynamic effects arise in cases when the suspension cables are very long. These oscillations may interfere with the ability of the crane operators to accurately unload the payload at its desired position and orientation. This paper presents a method for generating shaped commands that suppress payload oscillations of bouncing and pitching. Theoretical models are initially used to develop and evaluate the input-shaping control algorithm. Then, experiments performed on a portable tower crane are used to demonstrate the improved response provided by the proposed approach.
A Brief Investigation of Swarm Theory and Applications
Authors: Johnson Jay T.
Published: July 2010

For the last half century scientists have been discovering the biological complexities of colonies of ants, termites, bees and other insects. Although these colonies are composed of individuals with limited physical and intellectual aptitude, the behavior of the system as a whole displays highly adaptive and intelligent behavior. As a result, in the last two decades, engineers have been pursuing methods to create artificial swarm intelligence and applying these concepts of complex swarming systems to traditional and novel engineering areas such as robotics, optimization algorithms, wireless networks, and military applications. In this paper, an overview of swarm theory research is provided, followed by a more in depth demonstration of swarm behaviors including swarm clustering, formation control and swarm motion.
Towards Wearable Augmented Reality in Automotive Assembly Training
Authors: Kreft Sven , Gausemeier Ju¨rgen , Matysczok Carsten
Published: July 2010

Today, ubiquitous available information is an increasing success factor of industrial enterprises. Mobile Computing allows to manually accessing information, independent from the user’s current location. An additional technology in this context is Wearable Computing. It supports mobile activities by automatically (context-sensitively) gathering and presenting relevant information to the user. Within the wearIT@work project several Wearable Computing applications have been developed in order to demonstrate the overall benefit and maturity of this technology. However, these Wearable Computing applications display information in form of simple text or video. In contrast, Augmented Reality (AR) uses interactive 3D-objects to facilitate the user’s understanding of complex tasks. Combining both technologies in order to exploit their particular capabilities seems promising; not at last, since on a general level differences in their basic technologies can be unveiled hardly. In this paper, we propose a systematic approach to enhance Wearable Computing applications with Augmented Reality functionalities. Thereby, the necessary decision making and development processes are standardized and simplified. The approach has been applied to an existing Wearable Computing application in the field of automotive assembly training. We followed the proposed phases resulting in an economically reasonable concept for a Wearable Augmented Reality system that facilitates the trainee’s understanding of complex assembly tasks.
Optimization of Port Design for Layered Core Heat Exchanger
Authors: Berman Andrew B. , Burgmeier Chad B. , Beutin Kyle J. , Amano Ryo S.
Published: July 2010

This paper presents a design study of the geometry of the ports on a layered core heat exchanger, which is used in automotive engines. Using fluid dynamics, and fluid computational programs, the performance characteristics of a double boss port design was obtained as well as a single boss port design. The two designs were compared, and an optimized design shall be proposed. This optimization study compares the fluid flow and overall heat transfer of the layered core heat exchanger.
Impact Severity in Drive Line Systems With Backlash
Authors: Boere Stijn , Shukla Amit , Fey Rob , Nijmeijer Henk
Published: July 2010

Numerical simulations are used to study the transient behavior of a four degree-of-freedom, rotational piecewise linear system. This study focusses on the impact between bodies in a system with backlash as a result of a sudden step input and the associated transient response. The subsequent Single Sided Impacts and Double Sided Impacts are studied as a function of the amplitude of the step input and the size of the backlash. Transitions have been observed between Double Sided Impact regions and Single Sided Impact regions which agree with earlier findings. However, in this paper a more complete overview of the boundaries is given. The severity of the impacts is quantified with the peak-to-peak acceleration of the impacting bodies. Increasing the size of the step input increases the severity of the impacts. However, increasing backlash size leads to an extremum in impact severity. This is a possible explanation for seeming contradictions in literature.
Quasi-Active Damping
Authors: Potter Jack N. , Neild Simon A. , Wagg David J.
Published: July 2010

This article introduces a new method of system design using semi-active dampers named quasi-active damping. This technique is the design of dynamical systems and controllers using multiple semi-active dampers such that, at any instant, the desired control force can always be achieved using a combination of the dampers. The motivation is to produce levels of performance approaching those of active systems but with the energy consumption and stability of semi-active systems. The concept is demonstrated in simulation through the design of a stiffness-cancelling suspension system. It is also shown how the robustness of the system can be improved through the addition of a secondary, closed-loop, controller.
Computations of SIFs for Non-Symmetric V-Notched Plates by the FFEM
Authors: Treifi Muhammad , Oyadiji S. Olutunde
Published: July 2010

The present paper further develops The Fractal-like Finite Element Method (FFEM) to compute the stress intensity factors (SIFs) for non-symmetrical configurations of sharp V-notched plates. The use of global interpolation functions (GIFs) in the FFEM significantly reduces the number of unknown variables (nodal displacements) in a singular region surrounding a singular point to a small set of generalised coordinates. The same exact analytical solutions of the notch tip asymptotic field derived for a symmetrical notch case can be used as GIFs when the notch is non-symmetrical. However, appropriate local coordinate transformation in the singular region is required to obtain the correct global stiffness matrix. Neither post-processing technique to extract SIFs nor special singular elements to model the singular region are required. Any conventional finite elements can be used to model the singular region. The SIFs are directly computed because of the use of exact analytical solutions as GIFs whose coefficients (generalised coordinates) are the unknowns in the singular region. To demonstrate the accuracy and efficiency of the FFEM to compute the SIFs and model the singularity at a notch tip of non-symmetrical configurations of notched plates, various numerical examples are presented and results are validated via available published data.
Fractional Mechanics on the Extended Phase Space
Authors: Baleanu Dumitru , Muslih Sami I. , Golmankhaneh Alireza K. , Golmankhaneh Ali K. , Rabei Eqab M.
Published: July 2010

Fractional calculus has gained a lot of importance and potential applications in several areas of science and engineering. The fractional dynamics and the fractional variational principles started to be used intensively as an alternative tool in order to describe the physical complex phenomena. In this paper we have discussed the fractional extension of the classical dynamics. The fractional Hamiltonian is constructed and the fractional generalized Poisson’s brackets on the extended phase space is established.
Interaction Between In-Plane and Out-of-Plane Cable Modes for a Cable-Deck System
Authors: Marsico Maria R. , Gonzalez-Buelga Alicia , Neild Simon A. , Wagg David J.
Published: July 2010

When cables form part of larger structures, the interaction between the cable and structure can lead to complex vibration response. In this paper we consider a simplified one degree of freedom cable-stay bridge model, representing a bridge deck movement, which interacts with a particular cable in the structure. An analytical model is developed based on a modal decomposition and averaging to find the boundary at which nonlinear effects create out-of-plane vibration response. Experimental verification is carried out using a testing technique called real-time dynamic substructuring. This approach allowed the numerical model parameters to be varied, so the effects of parameter variation on the cable response could be studied. Small changes in the bridge deck frequency were found to lead to significant changes in the cable vibration response. This was investigated by computing stability boundaries for the out-of-plane modes, and good agreement was found between the experimental and analytical results.
A Linear Stability Analysis for Curve Squealing of Trains
Authors: Glocker Christoph
Published: July 2010

Curve squealing of railway wheels occurs in narrow curves with a frequency of about 4 kHz and is caused by a self-excited stick-slip oscillation in the wheel-rail contact. A squeal model, consisting of the first modal forms of an elastic wheel and a three-dimensional hard Coulomb contact, is developed to analyze the stability of the stationary run through a curve via linearization about the steady sliding equilibrium. The results show that in particular the front inner of the four wheels of a certain bogie tends to squeal.
A Model of Force Generation by Locust Skeletal Muscle in Response to Individual Stimuli
Authors: Wilson Emma , Rustighi Emiliano , Newland Philip L. , Mace Brian R.
Published: July 2010

A mathematical model of the locust hind leg extensor muscle is presented. The model accounts for the force response of the muscle due to individual stimuli under isometric conditions. Experimental data was collected by stimulating the muscle directly and force measured at the tibia. Joint dimensions were calculated, enabling tibial force to be converted into muscle force. In developing a model it was assumed that the response to a single isolated stimulus was linear, but no assumptions were made about the model order. Models of various order were fitted using time and frequency domain methods to data obtained from well-separated input pulses. The response could be approximated as an impulse response, with the response to each stimulus best described by a linear third-order system. Responses where input pulses were not well-separated, so that summation of subsequent pulses occurred, were also investigated. As has been observed in mammalian muscle, both facilitation and force depression were evident in locust muscle. The linear third-order model was found to provide an adequate fit to data in which depression and facilitation were evident if the parameters describing the system were allowed to vary between each response.
Annotation in Product Lifecycle Management: A Review of Approaches
Authors: Li Chunlei , McMahon Chris , Newnes Linda
Published: July 2010

In many engineering fields, a great deal of development is based on information processing, in particular the storing, retrieving, interpretation, and re-use of existing data. To be more competitive, the fast developing Product Lifecycle Management (PLM) systems are widely deployed by large scale enterprises. In order to improve the efficiency of data management and communication, annotation technology is considered as a promising approach to aid collaboration between design teams in concurrent design and to aid various needs during the entire product lifecycle. In this paper, a classification of approaches to annotation based on an investigation of the state-of-the-art is presented. Cases are used to illustrate how these approaches aid different phases of the product life cycle. Finally, future challenges in the use of annotation in engineering are discussed. Through this research, the contribution of the use of annotation is demonstrated, and further research work is proposed based on the findings.
Trajectory Simulations for Laser-Launched Microsatellites Using a 7-DOF Flight Dynamics Model
Authors: Kenoyer David A. , Anderson Kurt S. , Myrabo Leik N.
Published: July 2010

Laser launch trajectories are being developed for boosting nano- and micro-satellite sized payloads (i.e., 1 to 100 kg) using a 7-Degree Of Freedom (DOF) flight dynamics model that has been extensively calibrated against 16 actual trajectories of small scale model lightcraft flown at White Sands Missile Range, NM on a 10 kW pulsed CO2 laser called PLVTS. The full system 7-DOF model is comprised of individual aerodynamics, engine, laser beam propagation, variable vehicle inertia, reaction controls system, and dynamics models, integrated to represent all major phenomena in a consistent framework. The suborbital trajectory results presented herein are for a 240 cm diameter lightcraft (100 kg payload; 100 MW beam power) flown under three different laser-boost scenarios: 1) liftoff and vertical climb-out on a vertically oriented laser beam; 2) liftoff and climb-out along a constant laser beam pointing angle (fixed azimuth and zenith) defined relative to the launch pad; 3) liftoff and climb-out on a beam with a time-varying pointing schedule (azimuth and zenith) to “slingshot” the lightcraft laterally, making maximum use of the engine’s autonomous beam-riding feature. For simplicity, simulations assume a solid ablative rocket propellant (e.g., Teflon®-like performance) with a vacuum specific impulse of 644 seconds, momentum coupling coefficient of 190 N/MW, and overall efficiency of 60%. This flight dynamics model and associated 7-DOF code provide a physics-based predictive tool for basic research investigations into laser launched lightcraft for suborbital and orbital missions. An investigative protocol was developed to identify and quantify phenomena that dominate each phase of the launch trajectory. These protocols are specified herein, along with physics-based explanations for such phenomena, both predicted and observed.
Quantifying the Performance of MT-Connect in a Distributed Manufacturing Environment
Authors: Michaloski John , Lee Byeongeon , Proctor Frederick , Venkatesh Sid , Ly Sidney
Published: July 2010

Recently, MTConnect has been developed as an open and free communications standard to facilitate the exchange of data on the manufacturing floor for machine tools and related devices. This paper will briefly describe MTC, and look at quality of service issues investigated by implementing a modest MTConnect testbed in a “Dual-Ethernet” machine tool network configuration. MTConnect is expected to address the continuing pressure to reduce costs and improve time to market places in the CNC manufacturing world. It can facilitate smarter ways of manufacturing and intensifies the need to integrate feedback from the shop floor into the enterprise business systems.
Energy Harvesting From an Impulsive Load With Essential Nonlinearities
Authors: Triplett Angela , Quinn D. Dane , Vakakis Alexander F. , Bergman Lawrence A.
Published: July 2010

Vibration based energy harvesting, whereby mechanical energy is converted to electrical energy that can be stored and later used, offers the possibility of a long-term energy source under many realistic environmental conditions. This work considers an energy harvesting system based on the response of an attachment with strong nonlinear behavior. The electro-mechanical coupling is achieved with a piezo-electric element across a resistive load. When the system is subject to harmonic excitation, the harvested power from the nonlinear system exhibits a wider interval of frequencies over which the harvested power is significant, although an equivalent linear device offers greater efficiency at its design frequency. However, under impulsive excitation the performance of the nonlinear harvesting system exceeds the corresponding linear system in terms of both magnitude of power harvested and the frequency interval over which significant power can be drawn from the mechanical vibrations.
Fuzzy Reward-Based Cooperative Reinforcement Learning for Bio-Insect and Artificial Robot Interaction
Authors: Son Ji-Hwan , Ahn Hyo-Sung
Published: July 2010

In this paper, we address our on-going research that is for interaction between artificial robots and a bio-insect. The research motivation and research goal were introduced in [1]. In order to report a progress of this project, this paper contains advanced framework and simulation results. When we did experiments using real bio-insects, their movement showed a little randomness. For this reason, fuzzy logic is employed to drive the model-free bio-insect towards a desired point. The framework formulated in this paper is based on fuzzy reward system and fuzzy expertise measurement system. Fuzzy reward system uses three inputs and an output resulting in numerical value within −1 to 1. Fuzzy expertise measurement system is inspired by area of expertise. In area of expertise method, it uses expertise measurement equation for finding expert agent. Based on area of expertise method, our method uses three expertise measurements to calculate score of individual agent. Based on this score, agents can share their intelligences with weighted scores. Simulation results demonstrate the validity of the framework established in this research.
Van der Pol Type Self-Excited Microcantilever and Its Application to AFM
Authors: Yabuno Hiroshi , Kuroda Masaharu , Someya Takashi , Ohta Masahiro , Kokawa Ryohei
Published: July 2010

We propose a van der Pol type self-excited micro-cantilever probe for AFM (atomic force microscope). Because the response frequency of self-excited oscillators is its natural frequency, the equivalent natural frequency depending on the atomic force is easily measured from detecting the response frequency of the self-excited micro-cantilever probe. While the amplitude of the linear self-excited oscillator grows with time, it can be kept very small by the nonlinear effect as van ver Pol oscillator. Therefore, if the micro-cantilever probe has the same dynamics as that of van Pol oscillator, the contact of the micro-cantilever to the material surface is prohibited and non-contact mode AFM is realized. In the present study, we design a van der Pol type micro-cantilever for the application to the practical AFM system.
Non-Linear Strain Description for Two-Dimensional Shear Deformable Beam Element Based on the Absolute Nodal Coordinate Formulation
Authors: Sopanen Jussi , Matikainen Marko , Mikkola Aki
Published: July 2010

In the absolute nodal coordinate formulation, the transverse shear deformation can be accounted for by using a fully parametrized element or, alternatively, by replacing longitudinal slope coordinates by a vector that describes the orientation of the cross-section. The use of a fully parametrized element allows the description of cross-section deformations in the case of beams and, correspondingly, fiber deformations in the case of plates and shells. It is noteworthy, however, that cross-section or fiber deformations are usually associated with high natural frequencies complicating the time integration of a fully parametrized element. A procedure to replace longitudinal slope coordinates by the vector that describes cross-section orientation was recently applied to a two-dimensional beam element based on the absolute nodal coordinate formulation. In this study, the procedure to account for shear deformation using the vector that describes cross-section orientation is extended to account for the nonlinear strain-displacement relationship in the definition of the elastic forces of the beam element. To accomplish this, the exact displacement field is used in the description of element kinematical and strain measures. This makes it straightforward to implement the non-linear strain-displacement relationship in the description of the elastic forces. Numerical results demonstrate that the enhanced beam element yields accurate results in eigenfrequency analysis. Results obtained in large deformation cases are in line with previously proposed elements based on the absolute nodal coordinate formulation.
PD-PD Type Learning Control for Uncertain Nonlinear Systems
Authors: Ouyang P. R.
Published: July 2010

In this paper, a new learning control, called PD-PD type learning control, is proposed for trajectory tracking of nonlinear systems with uncertainty and disturbance. In the developed control scheme, a PD feedback control with the current tracking errors and a PD type iterative learning control using the previous tracking errors are combined in the updating law. Explicit expressions have been developed for choosing the feedback control gains and the iterative learning gains, and an initial updating scheme is proposed to reduce and eliminate initial errors from iteration to iteration. It is proven that the final tracking error is guaranteed to converge toward the desired trajectory in the presence of varying uncertainty, disturbance, and initial errors. Comparing with the traditional iterative learning control, the new algorithm has potential benefits that include: fast convergence rate, more flexible choices of the learning gains, and monotonic convergence of the tracking error. The effectiveness of the proposed learning control method is demonstrated by simulation experiments. Due to the straightforward implementation and very good trajectory performance of the proposed control algorithm, it should be highly applicable to industrial systems.
Modeling Rotorcraft Dynamics With Finite Element Multibody Procedures
Authors: Bauchau Olivier A.
Published: July 2010

This paper describes a multibody dynamics approach to the modeling of rotorcraft systems and reviews the key aspects of the simulation procedure. The multibody dynamics analysis is cast within the framework of nonlinear finite element methods, and the element library includes rigid and deformable bodies as well as joint elements. No modal reduction is performed for the modeling of flexible bodies. The structural and joint element library is briefly described. The algorithms used to integrate the resulting equations of motion with maximum efficiency and robustness are discussed. Various solution procedures, static, dynamic, stability, and trim analysis, are presented. Post-processing and visualization issues are also addressed. Finally, the paper concludes with selected rotorcraft applications.