bluuebunny/crossref_metadata_2025 huggingface dataset:
Updating of the Torsional Model of a Steam Turbo Generator
Authors: Ricci Roberto , Pennacchi Paolo , Pesatori Emanuel , Turozzi Giorgio
Published: July 2010

Rotor modeling by means of finite elements is necessary for rotordynamic calculations of industrial machines. Standard methods are available and allow forecasting rather accurately the experimental dynamic behavior of the considered machines. Anyhow, in some cases, due to the specific layout of the machine, the model made by means of these methods has to be updated to fit experimental results. In this paper, the updating of the torsional model of a steam turbogenerator is presented. Starting from some differences between the eigenfrequencies calculated using the standard model and the natural frequencies measured on-field, a modeling improvement is proposed, considering partially the dynamics of the parts usually modeled as rigid disks, with the aim to preserve the physical meaning of the model. The new model is updated and a very good fitting is obtained between eigenfrequencies and natural frequencies.
On an Non-Ideal Global and Local Energy Transfer, Using an Electro-Magneto and Magneto-Rheological Dampers
Authors: Balthazar Jose´ Manoel , Palacios Jorge L. F.
Published: July 2010

In this paper, we investigated the nonlinear vibrations of a Non-ideal (NIS) electromechanical absorber (NEVA), taking into account a modified mathematical model of (MR) Damper. We observed the presence of the Sommerfeld effect (it is the steady state frequencies of the DC motor, which it will usually increasing as more power (Voltage) is given to it, in a step-by-step fashion. When a resonance condition it is reached, the better part of this energy it is consumed to generate large amplitude vibrations of the foundation, without sensible change of the motor frequency). The obtained results, by using numerical and analytical simulations, were discussed, in details.
A Novel Real Time Diagnostic Method for Crack Detection on a Rotating Shaft
Authors: Bejarano Fernando A. , Rincon Amilcar A. , Camacho Yamil , Perereira Xaymara
Published: July 2010

This paper presents a novel real-time crack identification method to determine the position and depth of a transverse open crack on a rotating shaft. Wireless accelerometer capable of being mounted directly on the shaft is employed to monitor acceleration at different points of the shaft in a rotating coordinate system. The vibration parameters obtained from the wireless sensors and Finite Element Model provide operational data to perform Modal Analysis with different mock crack positions and depths, and an unique relation between the vibration parameters and crack characteristics is developed by Neural Networks Method working as function approximator to predict the crack size and location on the shaft. The method was experimentally validated and results have shown that the crack detection sensitivity parameters depend on the acceleration signals at different points of the shaft.
Methodological Integration of Parametric Associative CAD Systems in Product Lifecycle Management (PLM) Environment
Authors: Salehi Vahid , McMahon Chris
Published: July 2010

The automotive engineering process is characterized by a long and complex design process which starts with the first sketches in the preliminary design phase and extends to the final detailed CAD and physical models. Every design phase includes different process steps which are interconnected with each other. For a better handling of all created information in the different design stages there is a demand for capable Product Lifecycle Management systems (PLM). Furthermore, one of the important parts of PLM systems is the integration of the virtual product development process which can be based on parametric associative (PA) computer-aided design (CAD) systems. The main challenge is the full integration of all created PA CAD data with these kinds of system. To achieve the full potential of PA CAD systems, especially in view of the complexity of the CAD parts and assemblies, it is important to have a clear understanding of how best to use such systems. Accoring to Shah and Ma¨ntyla¨ [1] parametric systems solve constraints by applying sequentially assignment to model variables, where each assigned value is computed as a function of the previously assigned values. Related to design process associativity is the fix relationship and connection between geometrical entities and objects. These associative relationships include also the connection of 3D models and down stream process related elements. The focus of this paper is to present the results of a descriptive study which has been accomplished to identify the challenges, problems and weaknesses involved in the use of PA CAD systems in the automotive design process. After a short introduction the result of a literature survey is presented. The review is followed by presentation of the results of a questionnaire and interview study of engineers working in the automotive industry. This study demonstrates that engineers have significant difficulty in identifying and structuring the parameters and associative relationships used in PA CAD, especially in distributed design tasks. The review and the empirical study demonstrate the necessity of a generic integrated approach working with PA CAD systems. The results of this descriptive study will be used to support the methodological integration of the created CAD components in PLM environments.
Adaptive Disturbance Rejection and Stabilization for Rotor Systems With Internal Damping
Authors: Simon Andra´s , Flowers George T.
Published: July 2010

Advanced rotor systems today consist of a lightweight rotor supported by radial active magnetic bearings. It has been shown in previous works that composite materials have high energy dissipation characteristics, mainly due to internal damping. In applications where the rotor speed is subcritical, this property is of low concern, whereas at supercritical speeds the effect of internal damping should not be ignored due to instability effects described in detail later. Therefore, it is essential that one must have a detailed understanding of the sources and effects of internal damping in these structures. This work addresses the application of Adaptive Disturbance Rejection control method to deal with the rotordynamic instability caused by internal damping and synchronous vibrations caused by mass imbalance in a rotor system operating at supercritical speed. The simulated system is a slim, flexible shaft represented by a 73-node finite element model. A detailed description of the problems and the strategies for addressing them are discussed.
An Analytical Model for Force Estimation on Arms of Concrete Mixers
Authors: Braccesi Claudio , Landi Luca
Published: July 2010

The main task of our research is to achieve a proper analytical model to describe the forces exchanged between the mixing arms of a mechanical mixing machine and concrete during the whole mixing process. The model has been validated through experimental tests on a real type of mixer. The behavior of the sand-cement mix is very different in the three principal phases of a possible mixing operation: Phase 1: first mixing phase, sand and concrete are inserted in the mixer without water, “dry–phase”, Phase 2: a proper quantity of water is added to the dry mix for final mixing, “wet phase”, Phase 3: final mixing for complete homogenization of the mix. The electrical power necessary in the three phases is very different and in close relation to very different theoretical model that we will discuss later in the article. The main correlations between the geometrical shape of a so called omega mixer and the force exchanged is presented in the article. At the end of the article the coupling between the theoretical and the experimental data is presented.
Electrostatics and Self Contact in an Elastic Rod Approximation for DNA
Authors: Lillian Todd D. , Perkins N. C.
Published: July 2010

DNA is a life-sustaining molecule that enables the storage and retrieval of genetic information. In its role during essential cellular processes, this long flexible molecule is significantly bent and twisted. Previously, we developed an elasto-dynamic rod approximation to study DNA deformed into a loop by a gene regulatory protein (lac repressor) and predicted the energetics and topology of the loops. Although adequate for DNA looping, our model neglected electrostatic interactions which are essential when considering processes that result in highly super-coiled DNA including plectonemes. Herein we extend the rod approximation to account for electrostatic interactions and present strategies that improve computational efficiency. Our calculations for the stability for a circularly bent rod and for an initially straight rod compare favorably to existing equilibrium models. With this new capability, we are now well-positioned to study the dynamics of transcription and other dynamic processes that result in DNA supercoiling.
Self-Excited Vibrations in a Delay Oscillator: Application to Milling With Simultaneously Engaged Helical Flutes
Authors: Khasawneh Firas A. , Mann Brian P. , Bobrenkov Oleg A. , Butcher Eric A.
Published: July 2010

This paper investigates the stability of a milling process with simultaneously engaged flutes by extending the state-space temporal finite elements method. In contrast to prior works, multiple flute engagement due to both a high depth of cut and a high step-over distance are considered. A particular outcome of this study is the development of a frame work to determine the stability of periodic, piecewise continuous delay differential equations. Another major outcome is the demonstration of different stability behavior at the loss of stability in comparison to prior results. To elaborate more, period doubling regions are shown to appear at relatively high radial immersions when multiple flutes with either a zero or non-zero helix angle are simultaneously cutting.
An I-Ching-TRIZ-Inspired Approach to Design Concept Generation
Authors: Pham Duc Truong , Liu Huimin
Published: July 2010

This paper presents a new approach to producing innovative design concepts. The proposed approach involves extending the inventive principles of TRIZ by integrating other TRIZ and TRIZ-inspired tools. The set of inventive principles is then structured according to a framework adapted from I-Ching and represented using TRIZ’s Behaviour-Entity (BE) formalism to which constraints have also been added. The adoption of the BE representation enables a reduction in the amount of repeated information in the inventive principles. A BE pair contains information on a design solution. A Behaviour-Entity-Constraint (BEC) triple additionally has information on constraints on the solution. The BEC representation thus facilitates the retrieval and generation of design solutions from design specifications. The paper uses the problem of laying out seats in an aircraft cabin to illustrate advantages of the proposed approach.
Assessing the Effect of Incentive on Computer-Aided Design Intent
Authors: Johnson Michael D. , Diwakaran Ram Prasad
Published: July 2010

In today’s global and digital world, computer-aided design (CAD) can facilitate communication among design team members and make engineers more efficient. To meet the needs of the modern design team it is important that CAD models be formulated in a manner that is easily understood and that they can easily be altered. This work examines the role of an incentive to produce models quickly on feature selection, order, and organization (design intent). The role of design intent on model perception and the time required to alter a model is also investigated. The incentive to produce designs quickly is shown to have a negative effect on model attributes associated with proper design intent. Feature selection and organization are shown to affect model perception. The overall rating of a model is shown to be correlated with the time required to alter it. The importance of design intent on the perception of, and alteration time for, CAD models is shown.
Automatic Source Code Generator Based on AUTOSAR RTE for Vehicular Applications
Authors: Jo Hyun Chul , Piao Shiquan , Jin Sung Ho , Jung Woo Young
Published: July 2010

We propose a new approach to an automatic source code generator for the AUTOSAR-based vehicular software. The growing number of electrics/electronics software in vehicle systems makes more and more necessary the increasing demands. For example, it needs the essential requirements such as ensuring reliability, low production cost, coping with limited resources, and so on. Recently, there have been relative studies that point to this issue. An AUTOSAR development partnership is such a case. AUTOSAR is a standardized automotive software architecture which is an alliance of OEM and supplier. Now, the focus is mainly directed at a source code generator that deals with the AUTOSAR standard concept. In this paper, we present a novel source code generator which is based on the AUTOSAR software platform. The experimental process is presented to functionally verify the module, and structurally verify the generated source code.
Floating Frame of Reference and Absolute Nodal Coordinate Formulations in the Large Deformation Analysis of Robotic Manipulators: A Comparative Experimental and Numerical Study
Authors: Nada Ayman A. , Hussein Bassam A. , Megahed Said M. , Shabana Ahmed A.
Published: July 2010

This paper describes the use of flexible multibody system approaches in the dynamic modeling of interconnected rigid-elastic robotic manipulators. Two approaches are used to establish the flexible robot dynamic model; the floating frame of reference formulation (FFR) and the absolute nodal coordinate formulation (ANCF). The ANCF is used with two different methods for formulating the elastic forces; basic continuum mechanics approach (ANCF-BC) and elastic line method (ANCF-EL). The simulation results show that the use of the nonlinear FFR and the ANCF-EL improves the performance of the beam element in the modeling of flexible robotic manipulators. In the case of simple large deformation shape, the simulation results obtained show a good agreement between the FFR and the ANCF solutions. In the case of thin and stiff beams, the coupled deformation modes that result from the use of the ANCF-BC can be a source of numerical problems. These problems can be avoided using the implicit Hilber-Hughes-Taylor (HHT) integration method. On the other hand, HHT integrator does not capture high frequency axial modes when the FFR is used; RADAU5 method is used instead. The experimental results of the direct dynamics model are effectively used in this study to validate the numerical solutions.
Hysteresis Suppression in Nonlinear Mathieu M/NEMS Resonators
Authors: Kacem N. , Hentz S. , Baguet S. , Dufour R.
Published: July 2010

In order to compensate the loss of performances when scaling resonant sensors down to NEMS, it proves extremely useful to study the behavior of resonators up to very high displacements and hence high nonlinearities. This work describes a comprehensive nonlinear multiphysics model based on the Euler-Bernoulli equation which includes both mechanical and electrostatic nonlinearities valid up to displacements comparable to the gap in the case of a capacitive doubly clamped beam. Moreover, the model takes into account the fringing field effects, significant for thin resonators. The model has been compared to electrical measurements of devices fabricated on 200mm SOI wafers and show a very good agreement. This model allows designers to cancel out nonlinearities by tuning some design parameters and thus gives the possibility to drive the resonator beyond its critical amplitude. Consequently, the sensors performances can be enhanced to the maximum bellow the pull-in amplitude, while keeping a linear behavior.
Acquisition of High Quality Remote Sensing Data Using a UAV Controlled by an Open Source Autopilot
Authors: Schwarzbach Marc , Putze Uwe , Kirchgaessner Ursula , v. Schoenermark Maria
Published: July 2010

This paper describes the integration and application of the Paparazzi autopilot into an aircraft system for scientific research on remote sensing. The main purpose of the presented UAV, Stuttgarter Adler, is remote sensing of the environment for fundamental radiometric research as well as applications in agriculture, surveying and mapping. Employing a UAV for the retrieval of remote sensing data of quality comparable to data from manned missions represents a very flexible and inexpensive method of data acquisition. The sensors required for the intended resolution total several kilograms in weight and led to the construction of a matching airplane. All intended missions require a robust and precise control of the aircraft during image acquisition flights, which can only be achieved with an automated pilot assistance system. The Paparazzi system was chosen because its open source approach allowed to adapt the autopilot to the specific mission requirements. Interfaces to the digital remote control and to the camera and spectrometer payloads have been created. Test flights show good results in stabilizing the airplane and controlling the payload.
Swarm Coordination Under Conflict and Use of Enhanced Lyapunov Based Controller
Authors: Sierra Daniel A. , McCullough Paul , Olgac Nejat , Adams Eldridge
Published: July 2010

We consider hostile conflicts between two multi-agent swarms. First, we investigate the complex nature of a single pursuer attempting to intercept a single evader (1P-1E), and establish some rudimentary rules of engagement. We elaborate on the stability repercussions of these rules. Second, we extend the modelling and stability analysis between multi-agent swarms of pursuers and evaders. The present document considers only swarms with equal membership strengths for simplicity. This effort is based on a set of suggested momenta deployed on individual agents. Due to the strong nonlinearities, Lyapunov-based stability analysis is used. The control of a group pursuit is divided into two phases: the approach phase during which the two swarms act like individuals in the 1P-1E interaction; and the assigned pursuit phase where each pursuer is assigned to an evader. A dissipative control momentum was suggested in an earlier publication, which caused undesirable control chatter. This study introduces a distributed control logic which ameliorates the chatter problems considerably.
On-Line University Physics Course Using Intelligent Virtual-Tutors, Virtual-Reality and Advanced Multimedia
Authors: Wasfy Tamer M. , Wasfy Hatem M. , Peters Jeanne M.
Published: July 2010

A web-based self-paced university physics course, called the Virtual Physics Lab (VPL) is described. The VPL delivers both the lecture and lab components of a physics course using interactive virtual-reality simulations, high-end multimedia lectures and 2D/3D mini-games/exercises. The VPL’s interactive simulations are delivered in a video-game-like 3D photo-realistic virtual environment using real-time models to simulate typical physics experiments performed in the lab part of the physics course such as: frictional motion of a block on an inclined plane, vibrations of a mass-spring system and impact of particles. Students can change in real-time the parameters of the experiments and observe the effect on the experiment’s response and measurements. The multimedia lectures are delivered using a multimodal combination of speech and highlighted text delivered by near-photorealistic intelligent animated lip and gesture synched virtual tutors. The multimedia lectures include synchronized interactive 2D/3D animated illustrations and movies. A search engine and a hierarchical expert system allow the virtual tutors to answer natural-language questions and execute natural-language commands given by the student. Exercises in the form of mini-games that use relevant physics principles are used to increase the students’ interest in the material being taught and to test the student’s comprehension. The VPL’s interactivity and visually stimulating instruction will result in faster assimilation, deeper understanding, and higher memory retention by the students than traditional classroom/text-book instruction.
Assessing Material Properties on Sensorial Scales
Authors: Karana Elvin , Hekkert Paul , Kandachar Prabhu
Published: July 2010

Product designers are expected to create products transferring certain meanings. Materials of products are used for supporting the intended meanings in product design; one material may convey luxury, another material can be associated with a particular culture. It is to be expected that materials are attributed different meanings in different products and contexts, affected by certain key variables such as form, function, manufacturing processes, use, and user characteristics. The sensorial properties of materials (e.g. smoothness, transparency, softness, etc.) are one of these key variables which collaborate with the other key variables in design in order to create unique sensorial experiences and meanings. There is a growing interest among scholars in the design domain for developing new methods and tools to guide designers particularly in creating sensorial experiences through material choices. Studies conducted for this aim mainly focus on understanding the links between certain formal characteristics of materials (i.e. physical and sensorial properties) and the affective responses of users. The main question of this paper stems from this point: Can people properly evaluate the materials of products in terms of their sensorial properties regarding different sensory modalities? This main question is investigated by measuring the level of agreement among a group of non-design students on the sensorial properties of ten different materials. The results of the study show that perceptions of some sensorial properties can be more affected by the type of user-product interaction and by other sensorial properties (or other sensory domains). The paper consists of a comprehensive discussion on the results of the study.
Development of the Sound Metric for the Impact Sound of a Car Using Wavelet Transform
Authors: Na Eun Woo , Kim Ho-Wuk , Lee Sang Kwon
Published: July 2010

Vehicles experience the impact due to harsh road conditions. Contact with a barrier on a road induces vehicles to vibrate, which brings about impact noise of high sound level. The attenuation of impact noise is an important issue since car passengers may complain about the impact noise. However, Perfect removal of impact noise is not possible as most of impact noise is caused by external conditions. It is thus necessary to make vehicles to possess more desirable sound quality characteristic of impact sound. More research is needed on objective attributes of impact noise; it is not a simple matter since impact noise is transient in nature and has a high level of sound at an instantaneous moment. A new objective attribute of impact noise is designed by using wavelet transform. Wavelet transform is appropriate for the analysis of transient signals such as impact noise. The usefulness of new objective attribute, which is a sound metric, is examined by comparison with the mean subjective rating for real impact noise of passenger cars. The new sound metric has better correlation with the mean subjective rating than already existing sound metrics.
High Presence Collaboration Using Plug-In Video Avatar
Authors: Ogi Tetsuro , Tateyama Yoshisuke , Oonuki Satoshi
Published: July 2010

In order to realize effective collaboration between remote places, it is necessary to achieve high presence communication in the shared space. In this study, plug-in video avatar was developed. Video avatar is a technology that supports the communication between remote users by capturing the user’s video image and integrating it in the shared virtual world. In this method, stand-alone application can be expanded to the shared space application easily by using the plug-in function. The video avatar technology was applied to the remote collaboration by synthesizing it to various applications such as visualization, collaborative design, and remote presentation. The efficiency of the communication in the remote presentation and the system performance among three sites were investigated to evaluate the effectiveness of this system.
Stability Analysis of a Cracked Rotor With Several Degrees of Freedom
Authors: Ricci Roberto , Pennacchi Paolo
Published: July 2010

It is a common notion in literature that cracks in horizontal rotating shafts can cause instability of the system. Actually the stiffness variation due to the breathing mechanism may cause parametric excitation to the rotor system. This phenomenon has been investigated by means of both analytical models and simulation, but the studies are related to simple Jeffcott’s rotors. In this paper the method normally used to investigate the stability of cracked rotors, i.e. Floquet’s theory, is applied for the first time to a model of a real rotor with several degrees of freedom, considering also the bearings and the foundation. Huge calculation resources have been necessary and this may explain why this analysis was not performed before. The results are very different from those obtained by means of simple Jeffcott’s rotor.
Improvement of Hydractive Suspension Hard Mode Confort Thanks to a Low Frequency Active CRONE System: Part 1—Problematics, Strategy and Modelling
Authors: Moreau Xavier , Rizzo Audrey , Oustaloup Alain , Hernette Vincent
Published: July 2010

This paper presents, in 2 parts, a control law for a low frequency active suspension system. The first part, talks about the problematics, the strategy and the modelling. The control part and the results of the simulations are presented in the second part. More precisely, after the presentation of the problematics, the strategy which allows to get around the conflict of the passive suspensions is exposed in this first paper. Then, the hydropneumatic suspension which allows the implementation of this strategy is presented. It is composed of one hydractive part and one low frequency active part. Finally the validation and synthesis models are developed; their exploitation is made in the second paper.
Improvement of Hydractive Suspension Hard Mode Confort Thanks to a Low Frequency Active CRONE System: Part 2—Control Part and Simulation Results
Authors: Moreau Xavier , Rizzo Audrey , Oustaloup Alain , Hernette Vincent
Published: July 2010

This paper presents a control law for a low frequency active suspension system necessary for the implementation of the strategy defined in the first paper. The structure of the proposed control law is based on cooperation between feedforward and feedback. Feedforward design is based on the vehicle physics. The feedback law is synthesized from CRONE control-design method, french acronym of “Commande Robuste d’Ordre Non Entier” (non integer order robust control). Modeling, robust control-design in frequency-domain, optimal approach, stability analysis and performance are presented in this paper.
Explicit Nonlinear Rotational Controllers Using the Fundamental Equation
Authors: Schutte Aaron D. , Udwadia Firdaus E.
Published: July 2010

In this paper, we present two explicitly generated nonlinear controllers for rest-to-rest rigid body rotational maneuvers in terms of quaternions. The controllers are brought about by applying the fundamental equation of constrained motion to both the rotational dynamics and rotational control of rigid bodies. The first controller yields asymptotic stability at a desired orientation while allowing the stabilization to occur exactly along a pre-selected trajectory for three of the four components that make-up the quaternion. The second controller provides global stability at the desired orientation allowing stable motion to occur from any point in quaternion space. Numerical examples are provided showing the qualitative behavior that both rotational controllers yield when applied to a rigid body.
A Design Framework for Bi-Level Estimation of Machining Energy for Parts and Assemblies
Authors: Ameta Gaurav , Mani Mahesh , Huang He
Published: July 2010

This paper presents a framework and approach for the computation of machining energy for parts and assemblies, at two levels — early design stage and manufacturing stage. Energy estimation at an early design stage can be useful for redesign strategies and improving manufacturing efficiency. At the manufacturing stage, energy estimations allow for asset management based on energy efficient process planning and scheduling, thereby reducing the negative impacts of the product to the environment. To facilitate the computation of the machining energy, at an early design stage, we first automate the process of identifying the material removal volume for machining operations for a given part. We subsequently use the identified removal volume together with the material specific data to compute an energy range for manufacturing the part. For an assembly, the above computations for individual parts are aggregated to arrive at the final energy range. The proposed method allows the identification of energy intensive parts/features based on the percent contribution, thereby assisting re-design strategies. We additionally explore the application of statistical analysis and allocation principles to identify priority re-design parts. In this paper, we limit our product re-design discussions based on form (geometry and shape) and material. Future extensions will potentially also include manufacturing process optimization. Although the framework presented in this paper is currently applied only to milled parts and assemblies, it can also be extended to other machining methods.
Intrinsic Mode Decomposition of Physiological Signals for Feature Extraction
Authors: Samanta B. , Nataraj C.
Published: July 2010

This paper presents a study for extracting features from physiological signals using intrinsic mode decomposition. The complex, nonlinear and non-stationary biomedical signals are first decomposed into intrinsic mode functions (IMF). Next each IMF is subjected to morphological signal processing (MSP) for extracting features, namely, pattern spectrum entropy (PSEn), that characterize the shape-size complexity of the component signals. These along with other features like energy (E) and sample entropy (SampEn) are extracted from the individual IMF as well as the cumulative sums of IMF for characterizing the signals. The procedure is illustrated using heart sound signals digitally recorded during cardiac auscultation representing different cardiac conditions. The study examines the effectiveness of IMF based features in the assessment of cardiac state.
Nonlinear Flexible Multibody Dynamics Simulation of Operating Shock Response and Head Lift-Off in Hard Disk Drives
Authors: Eguchi Takehiko , Otake Noritaka , Watanabe Keiko
Published: July 2010

This paper describes a method of simulating the operational shock (op-shock) response of hard disk drives (HDDs) and its application to improving the op-shock robustness of HDDs. This flexible multibody dynamics simulation model is based on component-mode synthesis of three components; a rotating part including rotating disks and the hub/shaft of the spindle motor, a stationary part including base plate, top cover, and other major stationary parts, and an actuator part representing the moving parts of the head actuator mounted on head sliders. These components are connected to each other by fluid dynamic bearings, pivot bearings, and air bearings, and their nonlinear characteristics are considered in the op-shock response simulation. Linear and nonlinear drive-level simulation models were built, and their accuracies were experimentally verified in terms of their predicted linear frequency response, nonlinear time historical response, and head lift-off boundary. Moreover, a parametric study was performed to improve the op-shock robustness of a 2.5-inch HDD for the head lift-off boundaries of 3920 m/s2 (400 G) and 4900 m/s2 (500 G). The study indicated that the HDD model sensitivities to changes in the stiffness of the base plate and in the thickness of the disk were substantial but they saturated as the parameters became larger. The results indicated that the head lift-off boundary of 3920 m/s2 can be reached by making small modifications to the parts design, but the 4900 m/s2 boundary can’t be reached without the whole drive system being redesigned.
Modeling Perception of 3D Forms Using Fuzzy Knowledge Bases
Authors: Achiche Sofiane , Ahmed Saeema
Published: July 2010

The aesthetics of a product influences the decisions made by consumers when purchasing products. Research has shown that designers are not always successful in creating a product with the desired perception amongst its users. Hence methods and tools which can support the designer in predicting how the aesthetics of their products are likely to be perceived are of value. In this paper the authors propose an approach to formalize the relationship between geometric information of a 3D object and the intended emotion using fuzzy logic. 3D objects (shapes) created by design engineering students to evoke a certain perception were analysed. Three different fuzzy logic models, with different input variables, for evaluating massiveness and lightness in a form are proposed. The authors identified geometric information as inputs of the fuzzy model and developed a set of fuzzy if/then rules to map the relationships between the fuzzy sets on each input premise and the output premise. In our case the output premise of the fuzzy logic model is the level of belonging to the design context (emotion). An evaluation of how users perceived the shapes was conducted to validate the fuzzy logic models and showed a high correlation between the fuzzy logic model and user perception. The models show the possibility of creating tools to support designers with forms to evoke the desired perceptions amongst consumers.
A Dynamic Simulation of a Human Gait Using the Hybrid Muscle Model and a QCT-Based Flexible Tibia
Authors: Klodowski Adam , Rantalainen Timo , Mikkola Aki , Dastidar Prasun , Heinonen Ari , Sievanen Harri
Published: July 2010

The flexible multibody simulation [9] approach can be used in a wide variety of engineering applications. In a previous study of authors [1], flexible multibody simulation approach was used to estimate strains during walking at tibial midshaft. In the previous study, simple muscle models were used in conjunction with a flexible tibia model based on magnetic resonance images (MRI). This study is an extension of the previous developments [1], [2] demonstrating the potential of model improvement by introducing hybrid muscle models, along with the flexible tibia based model on computed tomography (CT). The computed tomography technique allows for the accounting of inhomogeneous density and elasticity in the flexible bone model comparing to magnetic resonance which do not provide any information on material properties. Hybrid muscle configuration used in this study consists of electromyography (EMG) actuated simple muscles configured with open-loop control for soleus, tibialis anterior, gastrocnemius and rectus femoris muscles and closed-loop Hill-based muscles [13] for the remaining lower body muscles. Strain results introduced in the study show good correlation with previous studies.
Milling Bifurcations: A Numerical Study
Authors: Radhakrishnan Anupam , Fales Roger , Mann Brian
Published: July 2010

In this work, a new model for predicting the dynamic behavior of the milling process is developed. Modeling of the discontinuous cutting forces now takes into account the motion of the cutting tool. The chip thickness is determined by using a search algorithm at each simulation step that determines when the tool cutting edge is in contact with the work piece and how far below the surface the cutting edge is. This new model has lead to a new, more precise, understanding of the stability of the dynamic milling system. For example, the new model is able to predict hysteresis effects in the point at which stability bifurcations occur. The bifurcation point depends on the direction of the change of the control parameter, depth of cut. The hysteresis effect was first seen in experimental results. The model details are presented with the aid programming flow charts. Simulation results show that the tool motion is unstable at large depth of cut and becomes stable as the depth of cut is slowly decreased. If the simulation begins with a small depth of cut stable behavior is exhibited. As the depth of cut slowly increases, the behavior becomes unstable. The depth of cut parameter value at which the bifurcation occurs depends on whether the depth of cut is increasing or decreasing. Simulation results show that an impulse can be given to the simulation to cause the system to jump from one attractor to another.
Torsional Vibration Analysis and Stress Calculation for the Fault 600MW Steam Turbine Generator Shaft System
Authors: Jiang Dongxiang , Hong Liangyou , Wang Zheng , Xie Xiaorong
Published: July 2010

Subsynchronous oscillation (SSO) or torsional vibration may cause shaft of steam turbine generator hurt heavily. This phenomenon has destroyed two generator shafts in one of China’s power plant in 2008. Detailed analysis and several measurements have been taken to identify the reason of the accident. First, the operational data is analyzed, including field torsional vibration dada. Then, the modal of the shaft system is calculated. Each torsional vibration frequency is gotten with corresponding modal shape. Dangerous location of the shaft system is obtained. Third, torque value of different operation condition is calculated based on two different models: one is traditional multiple mass element rotor dynamic model and the other is an four mass element electromechanical model of rotor oscillation. Following, the maximum stress on the dangerous location is calculated using finite element method. Finally, the root cause of shaft destruction is analyzed and identified.
Reliability Mathematical Model of Continuous System Based on Segment-Partition
Authors: Hao Guangbo , Xie Liyang
Published: July 2010

For the purpose of reliability assessment of continuous system like long pipeline and wire cable, the object should be taken as a series system composed of a great number of segments. First of all, two factors concerning the strength distribution of the object, i.e. material inhomogeneity factor and material quality instability factor were discussed in detail. Then, a reliability mathematical model of the object considering dependent failure was presented based on order statistics of segment strength, which was verified by Monte Carlo method. The result shows that the proposed reliability model can reflect the effects of dependent failure, material inhomogeneity and material quality instability for the application of continuous system.
Analogue Fractional-Order Generalized Memristive Devices
Authors: Coopmans Calvin , Petra´sˇ Ivo , Chen YangQuan
Published: July 2010

Memristor is a new electrical element which has been predicted and described in 1971 by Leon O. Chua and for the first time realized by HP laboratory in 2008. Chua proved that memristor behavior could not be duplicated by any circuit built using only the other three elements (resistor, capacitor, inductor), which is why the memristor is truly fundamental. Memristor is a contraction of memory resistor, because that is exactly its function: to remember its history. The memristor is a two-terminal device whose resistance depends on the magnitude and polarity of the voltage applied to it and the length of time that voltage has been applied. The missing element—the memristor, with memristance M—provides a functional relation between charge and flux, dφ = Mdq. In this paper, for the first time, the concept of (integer-order) memristive systems is generalized to non-integer order case using fractional calculus. We also show that the memory effect of such devices can be also used for an analogue implementation of the fractional-order operator, namely fractional-order integral and fractional-order derivatives. This kind of operators are useful for realization of the fractional-order controllers. We present theoretical description of such implementation and we proposed the practical realization and did some experiments as well.
The Modeling of Great Salt Lake Elevation Time Series Based on ARFIMA With Stable Innovations
Authors: Sheng Hu , Chen YangQuan
Published: July 2010

Great Salt Lake (GSL) is the largest salt lake in the western hemisphere, the fourth-largest terminal lake in the world. The elevation of Great Salt Lake has critical effect on the people who live nearby and their properties. It is crucial to build an exact model of GSL elevation time series in order to predict the GSL elevation precisely. Although some models, such as FARIMA or ARFIMA (Auto-Regressive Fractional Integral and Moving Average), GARCH (Generalized Auto-Regressive Conditional Heteroskedasticity) and FIGARCH (Fractional Integral Generalized Auto-Regressive Conditional Heteroskedasticity), have been built to characterize the variation of Great Salt Lake elevation, these models can not characterize it perfectly. Therefore, it became a key point to build a more appropriate model of GSL elevation time series. In this paper a new model based on fractional autoregressive integrated moving average (ARFIMA) with Stable innovations is applied to analyze the data and predict the future levels. From the analysis we can see that the new model can characterize GSL elevation time series more accurately. The new model will be beneficial to predict GSL elevation more precisely.
Analysis of Electrochemical Noise (ECN) of TiO2 Nanoparticles Coated Ti-6Al-4V in Simulated Biofluids Using Fractional Order Signal Processing (FOSP) Techniques
Authors: Sheng Hu , Zaveri Nikita , Chen YangQuan , Zhou Anhong
Published: July 2010

The electrochemical noise (ECN) measurements were conducted and used to assess the corrosion behaviors of the bare and TiO2 nanoparticles coated Ti-6Al-4V bioimplants exposed to three simulated biofluid solutions: 1) NaCl solution; 2) Hank’s solution; and 3) Cigada solution. The ECN data for bioimplants in these solutions were assessed by signal analysis techniques in both the time and frequency domains. In time domain analysis, the parameters including skewness, kurtosis, and noise resistance (Rn) were calculated. In frequency domain analysis, we introduced Fractional Order Signal Processing (FOSP) techniques to process the ECN data. Our results suggested that FOSP may provide a better signal analysis tool to evaluate the ECN signals than the conventional fast Fourier transforms (FFT) processing method.
Interfaces Per Module: Is There an Ideal Number?
Authors: Dobberfuhl Andrea , Lange Mark W.
Published: July 2010

Identifying an appropriate level of abstraction for a technical system is a task often left to more experienced product designers. Based on a systematic approach to modular product design, experience has shown that module interfaces are a key factor in identifying this appropriate level. The foundation for this research is that there are an ideal number of interfaces that corresponds to three semiotic, or signed, notational levels of product design communication. This report will present an empirical metric that represents this ideal number, which can be used to assess the quality of the decomposition based on the number of interface types. The conclusion of the report is that the empirical value very closely matches the semiotic theory of three interfaces per module.
Fractional One-Dimensional Transport Equation Within Spectral Method Combined With Modified Adomian Decomposition Method
Authors: Baleanu Dumitru , Kadem Abdelouahab
Published: July 2010

In this paper the Chebyshev polynomials technique combined with the modified Adomian decomposition method were applied to solve analytically the fractional transport equation in one-dimensional plane geometry.
Delay Effects in Supercavitating Vehicle Dynamics
Authors: Hassouneh Munther A. , Balachandran Balakumar , Abed Eyad H.
Published: July 2010

The dive-plane dynamics of a supercavitating vehicle is considered, a model with a time delay is constructed, and the physical basis for this delay effect is described. The time delay is on the order of the vehicle length divided by its speed. Stability analysis and feedback control design are carried out with this model. It is found that the open-loop system with and without the time delay is unstable. Feedback control laws, which stabilize the delay-free system, are found to be ineffective in the presence of the time delay. It is also shown that the delay leads to destabilization of the dynamics of the supercavitating vehicle in the sense that operation at a stable trim condition is replaced by a stable limit-cycle motion that is commonly referred to as tail-slap.
Model Reduction for Nonlinear Elastic Structures With Inertial Quadratic Nonlinearities
Authors: Wang Fengxia , Bajaj Anil K.
Published: July 2010

In order to achieve accurate and high fidelity nonlinear response predictions, discrete models usually obtained through Galerkin approximation utilizing linear normal modes of the structure, need to retain a large number of degrees of freedom. This is specially the case if the structural response has the possibility of modal interactions. Then, a possible approach suggested in the literature to decrease the required degrees of freedom while retaining same accuracy is to use nonlinear normal modes of the structure to perform further model reduction. In this work, we discuss model reduction for nonlinear structural systems under harmonic excitations. The analysis needs to carefully consider the possibility of external resonances, parametric resonances, combination parametric resonances (the parametric excitation frequency being near the sum or difference of frequencies of two modes), and internal resonances. A master-slave separation of degrees of freedom is used, and a nonlinear relation between the slave coordinates and the master coordinates is constructed based on the multiple time scales approximation. More specifically, three cases are considered: external resonance of a mode without any internal resonance, and subharmonic as well as superharmonic excitation for systems with 1:2 internal resonance. The steady state periodic responses determined by the method of multiple time scales are compared to exact solutions of the discrete model computed by the bifurcation analysis and parameter continuation software AUTO. It is seen that for systems with essential inertial quadratic nonlinearities, the technique based on nonlinear model reduction through multiple time scales approximation over-predict the softening nonlinear response.