bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduced Mechanism for the Oxidation of Hydrogen Sulfide
Authors: Selim H. , Gupta A. K. , Sassi M.
Published: July 2010

Hydrogen sulfide is one of the most common gases accompanying fuels in oil and gas refinery processes. This gas has very harmful effect on the human health and environment so that it must be removed in an effective and efficient manner before using this fuel. These problems triggered the interest to study the chemistry of hydrogen sulfide oxidation, as it is mainly treated by chemical reactions. Simplification of the reaction mechanism will enable us to understand the properties of the chemical processes that occur during the process of hydrogen sulfide treatment. Reduction strategy is carried out here in order to reduce the detailed mechanism, where the direct relation graph and error propagation methodology (DRGEP) has been used in this paper. The results obtained from the resulting reduced mechanism showed very good agreement with the detailed chemistry results under different reaction conditions. However, some discrepancies have been found for some species, especially in the hydrogen and oxygen mole fractions. The reduced mechanism is also capable of tracking the difference in chemical kinetics that takes place due to the change in reaction conditions.
On the Inclusion of Sliding Kinematical Effects on the Biodynamical Modeling of Symmetrical Lifting Activities
Authors: Hassan Mohammed M. , Bakr E. M. , Hegazy A. A.
Published: July 2010

In this paper, A new biodynamical model was developed with the objective of analyzing the dynamic responses of the human back during the exertion of symmetric lifting activities. More emphasis was placed on the study of the lumbosacral disc located between the fifth lumbar and first sacral vertebrae (L5/S1). The present model accounts for the sliding components of velocity and acceleration as well as the Coriolis acceleration in the kinematical equations of the human back. The inclusion of those terms has enabled a more accurate computation of the generated sliding effect of the flexible disc as well as the change in its height and width which normally occurs during the gross body rotation of the back. This has turned to have a significant effect on the resulting compressive force applied at the L5/S1 region. A computer model was developed in this study to automate the biodynamical simulation processes for workers of different genders and for a vast range of body postures. Results indicated that the inclusion of the sliding components of velocity and acceleration do actually have a significant effect on the whole range of lifting activities in which an angular velocity exceeding 24 degree/sec is employed. Results obtained in this paper were compared with the experimental and computational (simulated) results of recent relevant publications. The comparison shows that there are good agreements between the results for angular velocities exceeding 24 degree/second, which is known as the normal range of operation in lifting activities. Results obtained in this paper were in good agreement with NIOSH action and maximum limits which make it reliable for use as a guideline to help workers in industry to avoid hostile lifting activities and bring to attention an early warning to avoid engaging industrial labors with postures leading to severe back pain problems.
Haptic Gloves With Compact Finger Mechanism Using Active and Passive Actuation
Authors: Dazkir Goktug A. , Gurocak Hakan
Published: July 2010

Most haptic gloves are complicated interfaces with many actuators. If the gloves were more compact and simpler, they would greatly increase our ability to interact with virtual worlds in a more natural way. This research explored design of force feedback gloves with a new finger mechanism. The mechanism enabled application of distributed forces at the bottom surface of the fingers while reducing the number of actuators. Most glove designs available in the literature apply a reaction force only to the fingertips. Two prototype gloves were built using (1) DC servo motors, and (2) brakes filled with magnetorheological fluid. The glove with MR-brakes is lighter and simpler than the one with motors. However, the glove with motors enabled much faster task completion times.
Adaptive Text Extraction for New Product Development
Authors: Lee Thomas Y.
Published: July 2010

The first step in product design and development involves concept generation. Concept generation involves identifying customer needs and then mapping those needs onto a set of product attributes (specifications). Traditional methods for concept generation involve focus groups, surveys, and anthropological studies to assess user needs. Techniques, like Quality Function Deployment (QFD), then guide designers in relating needs to explicit product specifications. In this paper, we propose to augment traditional methods for concept generation by automatically processing user generated online product reviews. We apply adaptive text extraction methods to automatically learn user needs and product attributes. Association rule mining is used to learn the mapping between needs and attributes. We summarize results from prior work for independently learning user needs and attribute specifications from product reviews and then discuss the application of these methods to concept generation for new product development.
Utilizing Combinatorial Testing on Discrete Event Simulation Models for Sustainable Manufacturing
Authors: Johansson Bjo¨rn , Kacker Raghu , Kessel Ru¨ediger , McLean Charles , Sriram Ram
Published: July 2010

This paper describes how combinatorial testing using covering arrays can be implemented to optimize discrete event simulation models of manufacturing systems for measures of sustainability. Discrete event simulation models often have hundreds of parameters and many test values for each parameter. Generally the interactions between the parameter-values are not well understood; this can lead to sub-optimization of the system. Most optimization engines and software for discrete event simulation packages use full factorial designs, which require many runs and hence a lot of computation time. In this paper we introduce combinatorial testing using a test-suite generation tool called NIST-ACTS (National Institute of Standards and Technology - Advanced Combinatorial Test Suites) to dramatically decrease the number of runs required to detect the interactions and determine an optimal solution.
Stick-Slip Dynamics in Ultrasonic Consolidation
Authors: Gibert James M. , McCullough Daniel T. , Fadel Georges M. , Martin Grant K. M. , Austin Eric M.
Published: July 2010

Ultrasonic consolidation (UC) is a solid state rapid manufacturing process derived from ultrasonic welding of thin metal foils coupled with contour milling to achieve functional accurate components. Solidica Inc developed the process. The bonding of metal is accomplished by the local application of high frequency vibration energy under pressure producing a metallurgical bond without melting the base material. Its unique nature allows the design and fabrication of structural panels for satellites, production of injection molding tools, functionally graded structures, metal-matrix composites, embedded sensors, armor, and fiber embedded adaptive structures. It is commonly theorized that interfacial motion and friction at the bonding interface play a prominent role in the bonding process by removing surface contaminants, allowing direct metal to metal contact, and producing sufficient stress to induce plastic flow. The substrate’s geometry is also crucial in the bonding process. Researchers have experimentally observed that as the height of build specimen approaches its width, the bonding process degrades, and no further foils may be welded. Numerical simulations indicate that for features built at the nominal width (approximately 0.94 inches) the welding process excites several of the feature’s natural frequencies near the operating frequency of the ultrasonic welder, causing a resonance. This paper presents two modeling approaches to explain the behavior of the substrate as its dimensions approach the critical geometry: a finite element analysis and a lumped parameter model. We compare both models and present preliminary experimental results to verify their respective accuracies.
Navigation Over a Large Ontology for Industrial Web Applications
Authors: Crowder Richard M. , Wilson Max L. , Fowler David , Shadbolt Nigel , Wills Gary , Wong Sylvia
Published: July 2010

Ontologies for industrial semantic web applications are often very large. This is especially true in scientific and engineering applications where there exists a large pool of technical terminology necessary for operation within the domain. In this paper we look at the problem of presenting this domain ontology to users for navigation within web applications. The conventional tree view can be considered to be cumbersome and awkward to navigate for ontologies that have a very large breadth and/or depth. We present three approaches to this ontology presentation problem — content dependent filtering, autocompletion text box and partial segments using drop-down lists. All the approaches attempt to limit the ontology presented to users at one time. We implemented two of the proposed methods of ontology presentation in our demonstrators and have received positive and valuable feedback from engineers.
Experimental Results on Parametric Excitation Damping of an Axially Loaded Cantilever Beam
Authors: Ecker Horst , Pumho¨ssel Thomas
Published: July 2010

In various fields of engineering, e.g. aerospace applications, robotics or the bladings of turbomachinery, slender beam-like structures are in use and subject to free bending vibrations. Since such vibrations often are not wanted because they may degrade the performance or function of the structure, it is important to have a suitable means of vibration suppression available. In this experimental study we investigate a slender cantilever beam loaded with a controlled force at its tip. The force is always oriented towards the clamping point of the beam and generated by a piezo-actuator. Force control is based on an open-loop control without feedback from the structure. To enhance vibration suppression we take advantage of the additional damping observed when a periodic force modulation at a certain frequency is applied. From several theoretical studies it is known that parametrically excited systems show increased stability, and therefore enhanced damping properties, when the parametric excitation frequency is chosen near a certain combination frequency. Due to the almost axially applied force the cantilever beam system becomes a parametrically excited system and the effect mentioned can be observed. Numerous measurement runs have been carried out and vibration suppression as a function of the excitation frequency, the excitation amplitude and the beam initial deflection has been investigated. The results are in very good agreement with theoretical predictions and for the first time the numerical and analytical results obtained earlier are confirmed by experimental work.
On the Measurement of the Overall Elastic Stiffness and Bulk Modulus in Anisotropic Materials: Semiconductors
Authors: Gaith Mohamed S. , Alhayek Imad
Published: July 2010

In this study, the correlation between macroscopic and microscopic properties of the II-IV semiconductor compounds CdX (X = S, Se, Te) is investigated. Based on constructing orthonormal tensor basis elements using the form-invariant expressions, the elastic stiffness for cubic system materials is decomposed into two parts; isotropic (two terms) and anisotropic parts. A new scale for measuring the overall elastic stiffness of these compounds is introduced and its correlation with the calculated bulk modulus and lattice constants is analyzed. The overall elastic stiffness is calculated and found to be directly proportional to bulk modulus and inversely proportional to lattice constants. A scale quantitative comparison of the contribution of the anisotropy to the elastic stiffness and to measure the anisotropy degree in an anisotropic material is proposed using the Norm Ratio Criteria (NRC). It is found that CdS is the nearest to isotropy (or least anisotropic) while CdTe is the least near to isotropy (or nearest to anisotropic) among these compounds. The norm and norm ratios are found to be very useful for selecting suitable materials for electro-optic devices, transducers, modulators, acousto-optic devices.
Design of Limit-Switch Sensors Based on Discontinuity-Induced Nonlinearities
Authors: Wilcox Bryan , Dankowicz Harry
Published: July 2010

Limit-switch sensors are input-output devices that switch operating state in reaction to the crossing of a threshold value of their input. These are used to monitor and control critical values of temperature, voltage, pressure, etc. in both consumer and industrial settings. This paper argues for exploiting nonsmooth fold bifurcations in the design of ultrafast and robust, resettable, electromechanical limit switches. Specifically, the discussion emphasizes the dramatic changes in system response associated with the onset of near-grazing, low-velocity contact in vibro-impacting systems. These include rapid transient dynamics away from a pre-grazing, periodic, steady-state trajectory following the onset of impacts and post-grazing steady-state trajectories with distinctly different amplitude and frequency content. The results reported here include an experimental and computational verification of the ultrafast transient growth rates that show a significant potential for dramatic improvement in sensor performance. Moreover, two novel candidate sensor designs are discussed that rely on the post-grazing response characteristics for device function. In the first instance, transduction of a change in the response periodicity following grazing in a mechanical device is detected in a coupled electromagnetic circuit. In the second instance, a snap-through post-grazing response forms the operating principle of a capacitively-driven circuit protection device.
Finite Element Modeling of the Dynamic Response of Tracked Vehicles
Authors: Wasfy Tamer M. , O’Kins James
Published: July 2010

A time-accurate finite element model for predicting the dynamic response of tracked vehicles is presented. The model supports flexible continuous belt-type tracks and segmented-tracks consisting of rigid and/or flexible links connected using revolute joints. The flexible multibody system representing the tracked vehicle is modeled using rigid bodies, flexible bodies, joints and actuators. Flexible bodies are modeled using total-Lagrangian brick, membrane, beam, truss and linear/rotational spring elements. The penalty method is used to impose the joint/contact constraints. An asperity-based friction model is used to model joint/contact friction. A recursive bounding box contact search algorithm is used to allow fast contact detection between finite elements and other elements as well as general triangular/quadrilateral surfaces. The governing equations of motion are solved along with joint/constraint equations using a time-accurate explicit solution procedure. The model can help improve the design of tracked vehicles including increasing the vehicle’s stability and durability.
Calculation of Polynomial Curves for Speed-Dependent Bearing Coefficients
Authors: Yang Tachung , Lin Kai-Shang
Published: July 2010

Estimating bearing coefficients based on the vibration responses under operating conditions is the most precise approach that reflects the true conditions of the bearings. For speed-dependent bearing coefficients, such as oil-film journal bearings, the numbers of unknown coefficients are twice the number of the equations relating to unbalance responses, as pointed out by Tiwari et al.. At least two unbalance test runs are necessary to solve the bearing coefficients from unbalance responses, which means the rotating machines have to stop at least once to adjust the unbalance configurations for the second test run. This research aims at identifying the bearing coefficient curves in only one test run by using the unbalance responses at different rotating speeds within a specific speed range. In a wider range of operating speeds, the variations of bearing coefficient curves may have two bends, as well as the critical speeds may occur within the speed range. Third-order polynomials, which can follow the two-bend trends, are used to approximate the coefficient curves of speed-dependent bearings in this paper. The coefficients of the polynomials are calculated from the unbalance responses directly. The merits of identification with one test run are that it does not require the rotating machines to stop for the setting of independent unbalance configurations and is suitable for on-line identification of the bearing coefficients. The feasibility of the proposed method is studied by simulation and the noise effects around critical speeds are also investigated.
Dynamic Emulation of Tire/Road Friction for Developing Electric Vehicle Control Systems
Authors: Ma Chengbin
Published: July 2010

Current researches on electric vehicles are focusing on the environment and energy aspects. However, electric motors also have much better control performance than the internal combustion engines. Electric vehicles could not only be “cleaner” and “more energy efficient”, but also become “safer” with “better driving performance”. In this paper, a discrete elasto-plastic friction model is proposed for a dynamic emulation of tire/road friction for developing control systems of electric vehicles. The friction model can capture the transient behavior of the friction force during braking and acceleration, therefore the model-based emulation could enable more reliable verifications for various electric vehicle control methods.
Manipulating Virtual Objects With a Haptic Glove Based on Soft Pneumatic Muscles
Authors: Kuusisto Jukka , Ellman Asko , Reunamo Joonas , Kuosa Joonatan
Published: July 2010

In mechanical engineering, hardware mock-ups are increasingly being replaced by virtual models. Virtual environments enable the testing of different designs with considerable savings on time and money. Haptic feedback helps the user in getting a realistic conception about the cabin dimensions and how different controls actually look and feel. The haptic interface must be convenient to use and give realistic feedback on the functioning of the controls. The haptic force-feedback glove “SPM Glove” with soft pneumatic muscles — SPMs for short — on the palm side has been developed at the Department of Mechanics and Design at Tampere University of Technology. The glove provides force feedback to the thumb, index, and middle fingertips. In this paper, the usability of the SPM Glove for grasping, moving, and comparing the size of virtual objects is investigated. For achieving finger position information, the SPM Glove was worn over a data glove. Hand position was tracked with a magnetic tracker. The results indicate that users find manipulating cylindrical objects easier, more comfortable, and more natural with force feedback provided by the SPM Glove than without it. Moreover, all test users managed to arrange three invisible virtual cylinders of different sizes in order of increasing thickness using the SPM Glove.
Towards CAD-Less Finite Element Analysis Using Group Boundaries for Enriched Meshes Manipulation
Authors: Lou R. , Giannini F. , Pernot J-P. , Mikchevitch A. , Falcidieno B. , Ve´ron P. , Marc R.
Published: July 2010

Nowadays, most of the numerical simulations are carried out by successively performing the following steps: CAD model definition or modification, conversion to a mesh model and enrichment with semantic data relative to the simulation (e.g. material behaviour laws, boundary conditions), Finite Element simulation and analysis of the results. Classically, the semantic data are attached to the mesh through the use of groups of geometric entities sharing the same characteristics. Thus, any modification of the CAD model always implies an update of the mesh as well as an update of the attached semantic data. This is time-consuming and not adapted to the context of industrial maintenance. Moreover, the CAD models do not always exist and should therefore be reconstructed starting from scratch or from the physical object. In this paper, we set up a framework towards the definition of CAD-less Finite Element analyses wherein enriched meshes are manipulated directly. The geometric manipulations are constrained with information extracted from the group definition. Actually, the boundaries of those groups are exploited to constrain the modifications. The concept of Virtual Group Boundaries is introduced to focus on the extension of the attached semantic information instead of the actual tessellation while generalising the approach to groups of any dimension going from 0D (vertex) to 3D (e.g. tetrahedron). The notion of Elementary Group is also introduced as a mean to ease the forthcoming transfer of the semantics from the initial to the modified models. Such a framework also finds interest in the preliminary design phases where alternative solutions have to be evaluated.
Stability and Convergence of Two New Implicit Numerical Methods for the Fractional Cable Equation
Authors: Liu F. , Yang Q. , Turner I.
Published: July 2010

The cable equation is one the most fundamental equations for modeling neuronal dynamics. Cable equations with fractional order temporal operators have been introduced to model electrotonic properties of spiny neuronal dendrites. In this paper we consider the following fractional cable equation involving two fractional temporal derivatives: ∂u(x,t)∂t=0Dt1−γ1κ∂2u(x,t)∂x2−μ02Dt1−γ2u(x,t)+f(x,t), where 0 < γ1,γ2 < 1, κ > 0, and μ02 are constants, and 0Dt1−γu(x,t) is the Rieman-Liouville fractional partial derivative of order 1 − γ. Two new implicit numerical methods with convergence order O(τ + h2) and O(τ2 + h2) for the fractional cable equation are proposed respectively, where τ and h are the time and space step sizes. The stability and convergence of these methods are investigated using the energy method. Finally, numerical results are given to demonstrate the effectiveness of both implicit numerical methods. These techniques can also be applied to solve other types of anomalous subdiffusion problems.
A Natural Language to Component Term Methodology: Towards a Form Based Concept Generation Tool
Authors: Bohm Matt R. , Stone Robert B.
Published: July 2010

Over the last few decades design researchers have put forward theories and proposed methodologies that increase the chance that a design team will reliably arrive at the optimal solution to a given design problem. Studies, however, bear out that theories and methodologies alone will not guarantee an optimal or even good design solution. Instead, a breadth of knowledge across multiple engineering domains and the time and tools to thoroughly evaluate the design space are as important as any prescriptive design method. This work presents one of the underlying engineering technologies needed to leverage artificial intelligence approaches to thoroughly search the design space and synthesize concept solutions. Artificial intelligence methods are employed to generate a natural language to formal component terms thesaurus as part of a novel form-initiated concept generation approach. With this fundamental natural language interpretation algorithm, designers may now suggest an initial solution to a problem, expressed in everyday terms, and then rely on a machine to abstract the underlying functionality and conduct a thorough search of the solution space.
Mathematical Model of Transition Velocity-Dependent (TVD) Friction for a Free-Stroke Damper in a Washing Machine
Authors: Yoo Wan-Suk , Jung Sung-Woon , Park Jin-Hong , Chung Bo-Sun , Lee Jeong-Han , Nho Gyung-Hun
Published: July 2010

Recently, a new type of friction damper has been used to reduce vibrations of washing machines. The damper has a free-stroke region to isolate it from the vibration source during the dehydration operation. In the free-stroke region of the damper, a lubricated sponge is held on the inner tube of the damper so as not to invoke friction force. Once the sponge is moved by the contact force occurring between the outer tube and sponge, a friction is force generated. In this case, the friction force is induced by stick-slip motion and viscous elastic deformation of the sponge. Physical tests were performed using a testing machine by changing excitation amplitudes and frequencies to determine the characteristics of the damper. A mathematical model of a free-stroke damper was developed. Optimum values of parameters were evaluated through an optimization technique. To describe the friction force, which is increased by the external excitation velocity in the slip region of the sponge, a transition velocity-dependent (TVD) friction model is proposed. Our TVD friction model simulation results showed good agreement with physical test.
Optimizing Locator Position to Maximize Robustness in Critical Product Dimensions
Authors: Lo¨o¨f Johan , Lindkvist Lars , So¨derberg Rikard
Published: July 2010

The way parts are located in relation to each other or in fixtures is critical for how geometrical variation will propagate and cause variation in critical product dimensions. Therefore, more emphasis should be put on this activity in early design phases in order to avoid assembly and production problems later on. In earlier literature, locator positions have been defined using optimization to reach a robust locating scheme. This implies that the total robustness of a part is optimized by placing the locators in an optimal way. Sometimes there are areas on parts that are more sensitive to variation than others. Therefore, this paper suggests an approach for optimizing the positions of locators in a locating scheme to maximize robustness in defined critical dimensions. A formulation of an optimization problem is presented, and an algorithm solving this in a heuristic approach is developed. Finally, this algorithm is applied on an industrial example.
On the Choice of the Contact Frame in Railroad Vehicle Dynamics
Authors: Afshari Ali , Shabana Ahmed A.
Published: July 2010

In some of the wheel/rail creep theories used in railroad vehicle simulations, the direction of the tangential creep forces is assumed to be the wheel rolling direction (RD). When Hertz theory is used, an assumption is made that the rolling direction is the direction of one of the axes of the contact ellipse. In principle, the rolling direction depends on the wheel motion, while the direction of the axes of the contact ellipse (CE) are determined using the principal directions which depend only on the geometry of the wheel and rail surfaces and do not depend on the motion of the wheel. The RD and CE directions can also be different from the direction of the rail longitudinal tangent (LT) at the contact point. In this investigation, the differences between the contact frames that are based on the RD, LT, and CE directions, that enter into the calculation of the wheel/rail creep forces and moments, are discussed. The choice of the frame, in which the contact forces are defined, can be determined using one longitudinal vector and the normal to the rail at the contact point. While the normal vector is uniquely defined, different choices can be made for the longitudinal vector including the RD, LT, and CE directions. In the case of pure rolling or when the slipping is small, the RD direction can be defined using the cross product of the angular velocity vector and the vector that defines the location of the contact point. Therefore, this direction does not depend explicitly on the geometry of the wheel and rail surfaces at the contact point. The LT direction is defined as the direction of the longitudinal tangent obtained by differentiation of the rail surface equation with respect to the rail longitudinal parameter (arc length). Such a tangent does not depend explicitly on the direction of the wheel angular velocity nor does it depend on the wheel geometry. The CE direction is defined using the direction of the axes of the contact ellipse used in Hertz theory. In the Hertzian contact theory, the contact ellipse axes are determined using the principal directions associated with the principal curvatures. Therefore, the CE direction differs from the RD and LT directions in the sense that it is function of the geometry of the wheel and rail surfaces. In order to better understand the role of geometry in the formulation of the creep forces, the relationship between the principal curvatures of the rail surface and the curvatures of the rail profile and the rail space curve is discussed in this investigation. Numerical examples are presented in order to examine the differences in the results obtained using the RD, LT and CE contact frames.
On an Explicit Difference Method for Fractional Diffusion and Diffusion-Wave Equations
Authors: Quintana Murillo Joaqui´n , Yuste Santos Bravo
Published: July 2010

An explicit difference scheme for solving fractional diffusion and fractional diffusion-wave equations, in which the fractional derivative is in the Caputo form, is considered. The two equations are studied separately: for the fractional diffusion equation, the L1 discretization formula is employed, whereas the L2 discretization formula is used for the fractional diffusion-wave equation. Its accuracy is similar to other well-known explicit difference schemes, but its region of stability is larger. The stability analysis is carried out by means of a procedure similar to the standard von Neumann method. The stability bound, which is given in terms of the the Riemann Zeta function, is checked numerically.
Development of Experimental Chaos Identification Analysis System
Authors: Yang Qingchao , Liu Shuyong , Zhu Shijian , Diao Aimin
Published: July 2010

It is an important task to identify chaotic vibration in nonlinear vibration isolation system chaotification experiment. However, the chaotic time series toolbox is provided in few traditional data analysis software. The experimental chaos identification analysis system is developed in this paper based on LabVIEW. It can be applied to measure and analyze vibration signal in time, and the time history, power spectrum and phase space diagram can be observed with this developed system. Furthermore, it can be used as different signal sources such as harmonic signal, pulse and chaotic signal. In order to check the effectiveness of this system, the experiment is carried out, and the period-1, period-2, and chaotic attractor are measured. The different attractors are compared, and the self-similarity structure of the chaotic one is shown.
The Chebyshev Spectral Continuous Time Approximation for Periodic Delay Differential Equations
Authors: Butcher Eric A. , Bobrenkov Oleg A.
Published: July 2010

In this paper, the approximation technique proposed in [1] for converting a system of constant-coefficient delay differential equations (DDEs) into a system of ordinary differential equations (ODEs) using pseudospectral differencing is applied to both constant and periodic systems of DDEs. Specifically, the use of Chebyshev spectral collocation is proposed in order to obtain the “spectral accuracy” convergence behavior shown in [1]. The proposed technique is used to study the stability of first and second order constant coefficient DDEs with one or two fixed delays with or without cubic nonlinearity and parametric sinusoidal excitation, as well as of the delayed Mathieu’s equation. In all the examples, the results of the approximation by the proposed method show good agreement with either analytical results, or the results obtained before by other reliable approximation methods. In particular, the greater accuracy and convergence properties of this method compared to the finite difference-based continuous time approximation proposed recently in [2] is shown.
Fault Feature Analysis of Rotor System With Looseness Fault
Authors: Ma Hui , Sun Wei , Dai Jishuang , Wen Bangchun , Wang Zongyan
Published: July 2010

Focusing on pedestal looseness fault often occurring in practical engineering, a new looseness model is presented by considering respective advantages and disadvantages of all kinds of pedestal looseness model. By using finite element method, the looseness fault is simulated and the fault features are obtained. The simulation results show that when the amplitude of equivalent looseness mass is less than the looseness clearance, the system motion is from period-one through period-two to period-four, amplitudes of low frequency components gradually increase and the axis orbit changes from ellipse to twist with the decrease of looseness stiffness. When the amplitude of equivalent looseness mass is greater than the looseness clearance, high multiple frequency components and continuous spectra appear and axis orbit is similar to a trapezoid due to axis motion restrained by bilateral constraint. These fault features that obtained in different conditions are helpful to diagnose pedestal looseness fault in rotor system.
Weak Coupling of Multibody Dynamics and Block Diagram Simulation Tools
Authors: Gonza´lez Francisco , Gonza´lez Manuel , Cuadrado Javier
Published: July 2010

Dynamic simulation of complex mechatronic systems can be carried out in an efficient and modular way making use of weakly coupled co-simulation setups. When using this approach, multirate methods are often needed to improve the efficiency, since the physical components of the system usually have different frequencies and time scales. However, most multirate methods have been designed for strongly coupled setups, and their application in weakly coupled co-simulations is not straightforward due to the limitations enforced by the commercial simulation tools used for mechatronics design. This work describes a weakly coupled multirate method applied to combine a block diagram simulator (Simulink) with a multibody dynamics simulator in a co-simulation setup. A double-mass triple-spring system with known analytical solution is used as test problem in order to investigate the behavior of the method as a function of the frequency ratio (FR) of the coupled subsystems. Several synchronization schemes (fastest-first and slowest-first) and interpolation/extrapolation methods (polynomials of different order and smoothing) have been tested. Results show that the slowest-first methods deliver the best results, combined with a cubic interpolation (for FR < 25) or without interpolation (for 25 < FR < 50). For FR > 50, none of the tested methods can deliver precise results, although smoothing techniques can reduce interpolation errors for certain situations.
Adaptronic Precision Positioning Technology
Authors: Pahlke Achim , Rosen Simon , Ka¨stner Markus , Mo¨hring Hans-Christian , Reithmeier Eduard , Denkena Berend
Published: July 2010

The adaptronic precision positioning technology is applied to the fitting of rotation-symmetric components such as gearwheels in a hard turning process in order to compensate eccentricity. Distorted gearwheels, showing e.g. a significant quench distortion, cause a malposition in the chuck during clamping. This malposition leads to low quality workpieces or scrap in the hard turning process. To compensate the malposition of the workpieces, a new technology for precision positioning within the rotating chuck is being researched. In the introduction, the motivation of the preceding research project “Allowance-oriented precision positioning” and the framework of the adaptronic precision positioning technology are summarized. Next part is the description of the system’s components, beginning with the principles and the redesign of the mechatronic chuck. Completing the adaptronic precision positioning technology, the optical metrology, the data processing and automation aspects are shown in the following part. Afterwards, a short summary concludes this paper.
On Solving Certain Fractional Differential Equations With Right-Sided Derivatives
Authors: Klimek Malgorzata
Published: July 2010

In the paper, solutions of basic fractional differential equations with right-sided derivatives of order α and with variable tβ - potential are derived using the Mellin transform method. The results are Meijer G-function series fulfilling the respective boundary conditions. The obtained series are transformed into solutions of analogous equations with left-sided derivatives and (b – t)β - potential. As an example case α + β = α/J is studied and for J = 1 the eigenfunctions of the right-sided Riemann-Liouville derivative are recovered.
A Floating-Frame-of-Reference Formulation for Deformable Rotors Using the Properties of Free Elastic Vibration Modes
Authors: Irschik H. , Nader M. , Stangl M. , v. Garssen H.-G.
Published: July 2010

Formulations in rotordynamics are usually based on the assumption that the displacements of the bearings of the rotor are small, such that, besides the axial rotation, no large rigid-body motions have to be taken into account. This results in linear equations of motion with gyroscopic terms. When the axial angular speed of a rotor is increased, however, as well as for rapidly changing transient conditions, a non-linear coupling between the large axial rotation and the small rigid body motion induced by the compliance of the bearings and the small elastic deformation of the rotor body itself is to be expected. It is the scope of the present contribution to present a rational strategy for dealing with this situation. First, we present a problem-oriented version of the floating-frame-of-reference formulation (FFRF). We use a co-rotating rigid rotor as reference configuration, which allows using linear modes of the non-rotating elastic rotor as Ritz approximations. The position vector of the origin of a body-fixed coordinate system and three suitable Bryant angles are used as rigid body coordinates, and free elastic modes of the rotor are considered as elastic Ritz approximations. The properties of the latter and their consequences upon simplifying the necessary spatial integrals in the FFRF are addressed in some detail. The free modes are obtained from a Finite Elements pre-processing of the elastic rotor body. The non-linear equations of motion of the rotor are obtained afterwards by means of symbolic computation This formulation leads to a set of relations, in which the rigid-body degrees of freedom need not to be small, and which is integrated using an implicit scheme. Results for a rotor with unbalance forces, accelerated by external forces and having linear visco-elastic bearings are successfully compared to a commercial multi-body dynamics code.
Voxel-Based Interactive Haptic Simulation of Dental Drilling
Authors: Wu Jun , Yu Ge , Wang Dangxiao , Zhang Yuru , Wang Charlie C. L.
Published: July 2010

Haptics is one of the most important sensations for dentists to prepare cavity in dental surgery, which is however not easy to simulate in a computer system because of the large drilling force and the small speed of movement and material removal. In this paper, we present a fully voxel-based approach to interactively simulate dental drilling. Different from those voxel/mesh hybrid models, the drilling forces are computed directly from the voxel-representation while considering the factors of teeth’s material properties, the posture and forward speed of dentist’s drill and the contact surface area. To overcome force discontinuity caused by removal of tooth material, we define two layers of voxels on drill, where the boundary voxels are only employed to compute force feedback and the interior voxels are adopted to remove materials from teeth. The experimental result shows that our force model can produce smooth and large force feedback at a slow movement on haptic devices. Other than haptic rendering, a real-time filtering method directly using voxel representation has also been developed to improve visual rendering in dental simulation.
The Bio-Insect and Artificial Robots Interaction Based on Multi-Agent Reinforcement Learning
Authors: Choi Young-Cheol , Ahn Hyo-Sung
Published: July 2010

Multi-agent reinforcement learning is a challenging research topic used in various fields including robotics, artificial intelligence, distributed control, and so on. Recently, there have been lots of efforts to develop multi-agent reinforcement learning theories; but there exist many difficulties in multi-agent reinforcement learning system. In this paper, we introduce our on-going project BRIDS (Bio-insect and artificial Robot Interaction based on Distributed System), which is for interactions between a bio-insect and artificial robots using multi-agent reinforcement learning. The main objective of this project is to drive the bio-insect to the desired position using a group of artificial intelligent robots. Simulation results show that artificial intelligent robots drive the bio-insect to the target position using reinforcement learning.
Adomian’s Method Applied to Navier-Stokes Equation With a Fractional Order
Authors: Wang Yihong , Zhao Zhengang , Li Changpin , Chen YangQuan
Published: July 2010

In this paper, Adomian’s method is effectively implemented to determine the (approximate) analytic solution of the fractional-order Navier-Stokes equation. Such a solution is expressed in the form of a series with easily computable components. An illustrative example is presented.
Numerical Approximation and Error Estimation of a Time Fractional Order Diffusion Equation
Authors: Li Changpin , Zhao Zhengang , Chen YangQuan
Published: July 2010

Finite element method is used to approximately solve a class of linear time-invariant, time-fractional-order diffusion equation formulated by the non-classical Fick law and a “long-tail” power kernel. In our derivation, “long-tail” power kernel relates the matter flux vector to the concentration gradient while the power-law relates the mean-squared displacement to the Gauss white noise. This work contributes a numerical analysis of a fully discrete numerical approximation using the space Galerkin finite element method and the approximation property of the Caputo time fractional derivative of an efficient fractional finite difference scheme. Both approximate schemes and error estimates are presented in details. Numerical examples are included to validate the theoretical predictions for various values of order of fractional derivatives.
On the Resonant Nonlinear Normal Modes
Authors: Zhang Xinhua
Published: July 2010

The resonant nonlinear normal modes (NNMs) of a 2-dof conservative vibratory system is investigated in this paper. Three different approaches, the modified Adomian decomposition method, the variational method and the numerical NNM determination method are exploited respectively for constructing the NNM manifolds. Being different from the results reported in the literatures, new resonant NNM is obtained via these methods and for the 2-dof vibratory system considered herein, there is no NNM bifurcation, the number of the NNMs of this system is always equal to two.
Early Experiences in Using Multibody Dynamics Software to Simulate Flexible Webs in Production
Authors: Ross Brant A. , Woo Nelson
Published: July 2010

The production of products and packaging that are based on flexible web material is a substantial industry. While there is a wide assortment of products, manufacturers share the goals of maximizing the production rate (maximum web velocity), maintaining precise control of the web and maximizing the tolerance of the production line to variability in the web. The use of simulation to achieve these goals has been limited due to the complexity of characterizing a flexible body going through geometrically-nonlinear deformation as well as making contact with rollers and guides. Instead, physical test and the knowledge of experts are used to optimize the production lines. However, the detailed understanding of web behavior is limited since it is difficult to add instrumentation to a flexible web undergoing contact on both sides. Nonlinear FEA software can be used to study the web but the run times for a web moving though a reasonable motion can be extremely long. The use of commercial, off-the-shelf, multibody dynamics software offers hope for detailed results with shorter run times. This paper describes the use of multibody dynamics software to simulate web behavior, including the development of correct input conditions and the specification of outputs of interest to the web-handling community. Two examples are shown: a web response to roller misalignment and a study of trough formation.
Virtual Equipment Engineering: A Novel Approach for the Integrated Development of Semiconductor Manufacturing Equipment
Authors: Koitzsch Matthias , Mattes Andreas , Schellenberger Martin , Pfitzner Lothar , Frey Lothar
Published: July 2010

An innovative approach for the integrated and virtual development of new semiconductor manufacturing equipment is presented in this paper: Virtual Equipment Engineering (VEE). This new concept allows for the intelligent coupling of CAD with existing and novel simulation methods of the equipment development process towards a flexibly configurable integrated system. The main objective of VEE is to forecast the influence of development measures on the process and on the final device characteristics in the very early development stages of new equipment. Therefore, VEE follows a holistic view on equipment and processes to offer an integrated and adaptable development environment and a consistent simulation of equipment, process, process chain, and final devices. The major challenge in realizing this approach is the provision of a continuous, consistent, and persistent simulation chain. One possible solution dealing with this challenge is being developed and presented in this paper.
On Self-Consistent Operators With Application to Operators of Fractional Order
Authors: Lorenzo Carl F. , Hartley Tom T.
Published: July 2010

This paper extends the idea of the initialization function to the more general concept of a continuation function. The paper sets forth definitions for operator self-consistency which are then applied to test three operators, the ordinary Riemann integral, the time-varying initialized Riemann-Liouville fractional integral, and finally the Caputo derivative. Self-consistency was found for the first two cases. The Caputo fractional derivative operator was found to be self-inconsistent based on possible continuation functions derived from the Laplace transform of the derivative. A theoretical continuation function was derived which does make the derivative self-consistent, but requires a time-varying initialization function negating a primary attraction of this derivative.
The Fractional Meta-Trigonometry Based on the R-Function: Part I—Background, Definitions, and Complexity Function Graphics
Authors: Lorenzo Carl F.
Published: July 2010

The current fractional trigonometries and hyperboletry are based on three forms of the fractional exponential R-function, Rq,v(a,t), Rq,v(ai,t), and Rq,v(a,it). The fractional meta-trigonometry extends this to an infinite number of bases using the form Rq,v(aiα,iβt). Meta-definitions, meta-Laplace transforms, and meta-identities are developed for these generalized fractional trigonometric functions. Graphic results are presented. Extensions of the fractional trigonometries to the negative time domain and complementary fractional trigonometries are considered. Part I provides; background on the ongoing development of the fractional trigonometries, the definitions of the meta-trigonometry and its motivation, and a limited set of graphic results for the complexity based fractional trigonometric functions.