bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving Re-Use of Informal Information Through the Creation of an Engineering Electronic Logbook (EEL): A Demonstrator
Authors: McAlpine Hamish C. , Hicks Ben , Culley Stephen
Published: July 2010

Electronic logbooks (e-logbooks or e-notebooks) are used extensively in other domains — most notably the pharmaceutical industry — to good effect. However, despite a number of attempts over the last decade, engineers have resisted making the transition from their trusted paper logbooks. Reasons for this include a lack of understanding about how and why engineers use logbooks and a lack of appropriate software and hardware. In order to explore these issues, user-centric studies of engineers and their logbooks have been undertaken. From these studies a set of fundamental requirements have been developed that provide the basis for the creation of an Engineering Electronic Logbook (EEL). A demonstrator based on the Tablet PC platform to evaluate the information management aspects these requirements is then presented, together with details of how it is currently being evaluated. The contribution of this paper is a new information management strategy for e-logbooks — which has been derived from analysing existing paper-based logbooks and the note-taking practices of engineers — and its embodiment in a demonstrator for evaluation.
Energy Harvesting by Vibrations With MEMS Piezoelectric Benders
Authors: Mo Changki , Knight Ryan R. , Frederick Amanda A. , Clark William W.
Published: July 2010

Piezoelectric micro benders are fabricated and tested to demonstrate energy generating performance. Trapezoidal and diagonal unimorph PZT benders with an interdigitated electrode pattern are utilized. The d33 mode design is beneficial for the micro energy harvesting devices because it can generate higher voltage than that of the d31 mode design. It can also eliminate a bottom electrode by only using an interdigitated top electrode which facilitates fabrication, as opposed to the d31 mode design that requires both top and bottom electrodes. The MEMS benders consist of layers of SiO2/SiNx/ZrO2/PZT, and a top Au/Cr interdigitated electrode. The experimental results indicate that the fundamental frequencies of the micro benders are about 9.1 kHz for the trapezoidal bender and 18.48 kHz for the diagonal bender, respectively. The micro trapezoidal bender can generate power of approximately 1.4μW into a 680 kΩ resistive load at the resonant frequency. The diagonal bender can generate power of about 18.2 μW into a 100 kΩ resistive load at the resonant frequency.
Numerical Continuation in a Physical Experiment: Investigation of a Nonlinear Energy Harvester
Authors: Barton David A. W. , Burrow Stephen G.
Published: July 2010

In this paper we demonstrate the use of numerical continuation within a physical experiment: a nonlinear energy harvester, which is used to convert vibrational energy into usable electrical energy. To continue a branch of periodic orbits through a saddle-node bifurcation and along the associated branch of unstable periodic orbits, a modified time-delay controller is used. At each step in the continuation the pseudo-arclength equation is appended to a set of equations that ensure that the controller is non-invasive. The resulting nonlinear system is solved using a quasi-Newton iteration, where each evaluation of the nonlinear system requires changing the excitation parameters of the experiment and measuring the response. We present the continuation results for the energy harvester in a number of different configurations.
Optimization Problem in Biomolecular Simulations With DCA-Based Modeling of Transition From a Coarse to a Fine Fidelity
Authors: Anderson Kurt S. , Poursina Mohammad
Published: July 2010

In multiscale modeling of highly complex biomolecular systems, it is desirable to switch the system model either to coarser, or higher fidelity models to achieve the appropriate accuracy and speed. These transitions are achieved by effectively imposing (or releasing) certain systems constraints from a fine scale model to a reduced order model (or vice versa). The transition from a coarse model to a fine one may not result in a unique solution. Therefore, a knowledge-based or physics-based optimization procedure may be used to arrive at the finite number of solutions. In this paper, it is shown that traditional approaches to address and solve the optimization problem such as Lagrange multipliers or changing the constrained optimization problem to an unconstrained one based on coordinate partitioning or basic linear algebra methods are computationally expensive for biomolecular systems. It is demonstrated that using a DCA based approach in modeling the transition can reduce dramatically the computational expense associated with the manipulations performed as part of optimization as well as the ones performed to derive the dynamics of the transition.
Modal Testing of Nonlinear Vibrating Structures Based on a Nonlinear Extension of Force Appropriation
Authors: Peeters M. , Kerschen G. , Golinval J. C.
Published: July 2010

Modal testing and analysis is well-established for linear systems. The objective of this paper is to progress toward a practical experimental modal analysis methodology of nonlinear mechanical structures. In this context, nonlinear normal modes (NNMs) offer a solid theoretical and mathematical tool for interpreting a wide class of nonlinear dynamical phenomena, yet they have a clear and simple conceptual relation to the classical linear normal modes (LNMs). A nonlinear extension of force appropriation techniques is investigated in this study in order to isolate one single NNM during the experiments, similarly to what is carried out for ground vibration testing. With the help of time-frequency analysis, the modal curves and the corresponding backbones are then extracted from the time series. The proposed methodology is demonstrated using a numerical benchmark, which consists of a planar cantilever beam with a cubic spring at its free end.
Minkowski Sums of Periodic Surface Models
Authors: Wang Yan
Published: July 2010

Recently we proposed a periodic surface model to assist geometric construction in computer-aided nano-design. This implicit surface model helps create super-porous nano structures parametrically and support crystal packing. In this paper, we study construction methods of Minkowski sums for periodic surfaces. A numerical approximation approach based on the Chebyshev polynomials is developed and can be applied in both surface normal direction matching and volume translation formulations.
An Approach on Bladed-Disc Tuning
Authors: Duong Loc , Kazerounian Kazem , Murphy Kevin D.
Published: July 2010

High cycle fatigue of rotating components, produced as the system is driven near to resonant conditions, is undesirable and is one of the major design concerns in engineering today. Structurally, it is imperative to tune the excited vibration mode out of the operating speed range to avoid large amplitude vibrations. It has been demonstrated that for a single blade with distinct eigenvalues, it is possible to tune the eigenvalue of choice out of the operating speed range while maintaining little change to other natural frequencies through structural perturbations. These perturbations usually come in the form of a redistribution of the stiffness and/or mass [1]. The focus of this paper is to extend this approach to the tuning of two adjacent excited frequencies of a bladed-disc by first reducing the inter-blade coupling through stiffening the disc structure followed by “individual” blade tuning. Due to the complexity of the bladed disc structure, results from direct finite element analyses are used based upon analytical eigen-perturbed expressions to investigate the dynamic inter-blade behavior of an impeller. A good correlation between analysis and laser vibrometry test measurements is obtained.
Application of a Balancing Filter for Model-Based Fault Diagnosis on a Centrifugal Pump in Active Magnetic Bearings
Authors: Beckerle Philipp , Butzek Norman , Nordmann Rainer , Rinderknecht Stephan
Published: July 2010

This paper discusses the suitability of a special discrete filter, called balancing filter, to improve the performance of model-based fault detection and fault diagnosis on a centrifugal pump in active magnetic bearings. The focus in this subject lies on the extraction of better symptoms for the fault diagnosis. The application of the balancing filter sets up on a multi-model approach which uses a model of the system for the reference state and every fault that is to be detected. These models are stimulated with the same test signals as the ones applied to the process while it is running. To compare the simulation results of the models with the process response the output error is calculated. After this the remaining residuals are used as symptoms for the fault detection. The balancing filter is used to remove the large differences within the amplitude responses of the models caused by the lowpass characteristics of the mechanical part of the system. Hence the influence of the smaller differences caused by the examined faults is weighted equally at all interesting frequencies. This leads to new residuals which are separated more clearly. This approach is used to detect common faults appearing on centrifugal pumps as dry run, incorrect installation and worn out balance pistons. The test rig used to examine the suitability of the proposed filter is a one-level centrifugal pump in magnetic bearings. The rotor of the pump is driven by an asynchronous motor at rotation speeds up to 3000 rpm. The first flexible mode of the rotor is located at 280 Hz. In the seal gap fluid-structure-interaction is appearing. The forces on the rotor are calculated based on the current applied to the bearings, while its displacement is measured by eddy current sensors integrated into the bearings. The first two natural frequencies of the system are located at about 200Hz and 500 Hz. These frequencies are shifted when a fault is occuring. In the models for the fault states this behaviour is represented. Hence the model matching the current state of the pump leads to the lowest residual. The advantage of the balancing filter is that the detection of faults becomes more reliable. Below the examined faults, the model-based concept and the design of the balancing filter are described in detail. Results from experiments on the test rig are given to show the advantages of the balancing filter.
Structured Eigensolution Properties of Planetary Gears With Elastically Deformable Ring Gears
Authors: Parker Robert G. , Wu Xionghua
Published: July 2010

The distinctive modal properties of equally spaced planetary gears with elastic ring gears are studied through perturbation and a candidate mode method. All eigenfunctions fall into one of four mode types whose structured properties are derived analytically. Two perturbations are used to obtain closed-form expressions of all the eigenfunctions. In the Discrete Planetary Perturbation (DPP), the unperturbed system is a discrete planetary gear with a rigid ring. The stiffness of the ring is perturbed from infinite to a finite number. In the Elastic Ring Perturbation (ERP), the unperturbed system is an elastic ring supported by the ring-planet mesh springs; the sun, planet and carrier motions are treated as small perturbations. A subsequent candidate mode method analysis proves the perturbation results and removes any reliance on perturbation parameters being small. All vibration modes are classified into rotational, translational, planet and purely ring modes. The well defined properties of each type of mode are analytically determined. All modal properties are verified numerically.
Components for Composite Material Customization System
Authors: Nandi Soumitra , Siddique Zahed
Published: July 2010

With the advancements of composite materials and research in nano-composites, designers have the flexibility to select materials from a wide range of properties to meet their specific design needs. Even with all these advancements, the material selection process during design follows a very conventional approach. The conventional approach to material design is to select a certain material from a given pre-set material list that allows the attainment of nearest properties required for the product. One of the disadvantages of this approach is that the trade-off inherent in the selection of material, when multiple properties are targeted, can be cumbersome to achieve or addressed at all. In this paper we present an approach to select and design composite materials, where the designer will have flexibility to select multiple properties of materials during the design of a new product. This approach employs an index for selection combined with heuristic optimization techniques to select the optimized combination of composite materials that could meet closest possible property goals. In the case study presented in this paper, we did not perform any optimization; rather, emphasize is given to the explanation of material selection technique, and an RMS value is introduced as an index for the selection.
FPGA Implementation of Self-Tuning Regulators
Authors: Caponetto R. , Dongola G. , Gallo A.
Published: July 2010

The paper presents an hardware realization of a self-tuning control system implemented on a development board, Field Programmable Gate Arrays (FPGAs) based, able to adapt the control rules for an uncertain and disturbance affected plant. In the paper the on-line estimation of the plant parameters is realized by applying the “Recursive Least Squares with exponential forgetting” method and the control law is designed by using the “Pole Placement” procedure. These algorithms require a greater computational load, justifying therefore the FPGA utilization, especially in the case of high speed variation of the plant parameters. In order to test the FPGA hardware implementation of Self-Tuning regulators the process is implemented on DSPACE and the parameter variations are produced via an Human Machine Interface (HMI) console. Besides, thanks to the reprogrammability of FPGAs, these devices allow the use of such adaptive control systems in hazardous area.
Stability Analysis and Bifurcation of Two Dimensional Incompressible Flow Around Circular Cylinder
Authors: Kang Wei , Liu Yan , Zhang Jia-zhong
Published: July 2010

Special attention is paid to the stability of the flow around circular cylinder, in particular to the evolution of vortices. From viewpoint of nonlinear dynamics, the stability of streamline patterns of the flow field is analyzed using qualitative theory of differential equations. Combined with the critical points of the flow, the local solutions of flow equations are derived to discuss the change of flow topology. It can be seen that the birth of vortices behind the cylinder are the results of the bifurcations of the corresponding critical points.
Particle Clustering to Improve Omnidirectional Localization in Outdoor Environments
Authors: Zingaretti Primo , Ascani Andrea , Mancini Adriano , Frontoni Emanuele
Published: July 2010

Monte Carlo Localization (MCL) is a common method for self-localization of a mobile robot under the assumption that a map of the environment is available. In addition to laser scanners and sonar sensors, localization approaches using vision sensors have also been recently developed with good results. In this paper we present two variations to improve the standard implementation of the MCL algorithm. The first change consists in a new strategy for the generation of particles, both at the initialization and at the resampling stage, which tries to generate new particles near the position of images in the learning dataset or in the neighborhood of particles with higher weights in the previous estimate, respectively. The second variation is related to a new approach to the estimate of the robot position, now based on two steps: clustering of particles and taking as estimate of robot position the center of the cluster, computed as a weighted sum of particle weights, with higher weight. The improved MCL algorithm described in this paper is compared with the standard MCL algorithm in terms of localization accuracy. In particular, tests were performed using local feature matching of omnidirectional images implemented on a real robot system operating in large outdoor environments with high dynamic content. Obtained results show that the localization accuracy of the improved MCL algorithm is more than twice that of the standard MCL algorithm.
Torsional Vibrations on a Hopper Dredger Due to Transient Conditions
Authors: Petit F. , Loccufier M.
Published: July 2010

Torsional vibrations are known to be a major threat to the drive line of every ship. While classification societies demand a thorough analysis of the regime behavior, the transient behavior is not studied. Transient loads involve among others starting/stopping the engine, engaging/disengaging clutches, altering the vessel’s speed and changing the pitch of the propeller. These high load changes are known to be a source of severe damage to gear boxes and flexible couplings. Further more, they tend to disturb the interaction between the mass-elastic system and the speed controller (governor instability). In this article, the different transient loads are described in detail for the specific case of a trailing suction hopper dredger. The focus lies on the engaging and disengaging behavior of the pump clutch. The different factors contributing to this transient load and their influence are explained without the use of a complex simulation model.
Using Support Vector Machines to Formalize the Valid Input Domain of Models in Data-Driven Predictive Modeling for Systems Design
Authors: Malak Richard J. , Paredis Christiaan J. J.
Published: July 2010

Predictive modeling can be a valuable tool for systems designers, allowing them to capture and reuse knowledge from a set of observed data related to their system. An important challenge associated with predictive modeling is that of describing the domain over which model predictions are valid. This is necessary to avoid extrapolating beyond the original data, particularly when designers use predictive models in concert with optimizers or other computational routines that search a model’s input space automatically. The general problem of domain description is complicated by the characteristics of observational data sets, which can contain small numbers of samples, can have nonlinear associations among the variables, can be non-convex, and can occur in largely disjoint clusters. Support Vector Machine (SVM) techniques, developed originally in the machine learning community, offer a solution to this problem. This paper is a description of a kernel-based SVM approach that yields a formal mathematical description of the valid input domain of a predictive model. The approach also provides for cluster analysis, which can lead to improved model accuracy through the decomposition of a data set into multiple subsets that designers can model independently. The paper includes a mathematical presentation of kernel-based SVM methods, an explanation of the procedure for applying the approach to predictive modeling problems, and illustrative examples for applying and using the approach in systems design.
Nonlinear Modal Analysis of Mechanical Systems With Frictionless Contact Interfaces
Authors: Laxalde Denis , Legrand Mathias , Pierre Christophe
Published: July 2010

This paper investigates the nonlinear analysis, in the form of nonlinear modes, of mechanical systems undergoing unilateral frictionless contact. The nonlinear eigenproblem is introduced by a Rayleigh quotient minimization with inequality constraints formulated in the frequency domain. An augmented Lagrangian procedure is used for the calculation of the nonlinear contact forces. The efficiency of the proposed method for large-scale mechanical systems involving non-smooth nonlinear terms is shown. An industrial application consisting of a compressor blade in contact with a rigid casing is proposed. Sensitivity of the nonlinear modal parameters to contact is illustrated.
The Assembly of Computational Models for the Collaborative Development of Virtual Prototypes
Authors: Wang Hongwei , Johnson Aylmer L. , Zhang Heming
Published: July 2010

In the context of collaborative product development, new requirements need to be accommodated for Virtual Prototyping Simulation (VPS), such as distributed processing and the integration of models created using different tools or languages. Existing solutions focus mainly on the implementation of distributed processing, but this paper explores the issues of combining different models (some of which may be proprietary) developed in different software environments. In this paper, we discuss several approaches for developing VPS, and suggest how it can best be integrated into the design process. An approach is developed to improve collaborative work in a VPS development by combining disparate computational models. Specifically, a system framework is proposed to separate the system-level modeling from the computational infrastructure. The implementation of a simple prototype demonstrates that such a paradigm is viable and thus provides a new means for distributed VPS development.
Fully Automated Tuning and Implementation of Fractional PID Controllers
Authors: Santamaria Guillermo E. , Tejado Ine´s , Vinagre Blas M. , Monje Concepcio´n A.
Published: July 2010

The advantages and applications of modeling and control of non-integer order linear systems are well known, but the inherent complexity of practical approximations has prevented the generalized appearance in the market of simple devices capable of implementing a fractional order control on a unknown given plant in a reliable way. The purpose of this work is to make a step forward in this sense, looking for a compromise between simplicity and reliability of the system. An automatic method for tuning, design, and implementation of fractional order PIαDμ controllers is presented in this paper. The auto-tuning method is based on plant magnitude and phase measuring at a frequency of interest, obtained by the relay feedback technique. A fractional order PIαDμ controller is designed from these measurements so that specifications of phase margin and robustness to variations of the plant gain are reached. Once the fractional order PIαDμ controller transfer function is obtained, it is discretized applying Pascal Matrix Method, and approximated using continuous fraction expansion of the Tustin Operator, generalized for a general transfer function. Simulation results obtained using the described method on an a priori unknown characteristic servo are presented in this paper.
Multimodal Perception-Action Interaction for the Exploitation of Enactive Knowledge
Authors: Bordegoni Monica , Cugini Umberto
Published: July 2010

This paper addresses issues related to enactive interfaces, which are human-computer interfaces based on enactive knowledge, i.e. the information that the user gains through perception-action interaction in the environment. These interfaces are typically multimodal, i.e. are based on the use of several channels for the communication between the user and the computer system, and in addition can be effectively used for exploiting users’ skills during the interaction with computers, differently from traditional interfaces. This paper reasons about enactive interfaces and describes an example of an application based on enactive interface, and its evaluation.
On Combined Use of POD Modes and Ritz Vectors for Model Reduction in Nonlinear Structural Dynamics
Authors: Kumar Nishant , Burton Thomas D.
Published: July 2010

An approach to develop Proper Orthogonal Decomposition (POD) based reduced order models for systems with local nonlinearities is presented in this paper. This technique is applied to multi-degree of freedom systems of coupled oscillators with isolated nonlinear elements. Typically, reduced order models are obtained using POD modes exclusively. In this work, we explore the suitability of using a combination of POD modes and other physically based “Ritz vectors” to produce the reduced model. The objectives are 1). to improve the accuracy of the reduced order differential equation model and 2). to expand the range of system parameters for which the reduced basis provides reasonably accurate approximations. The “Ritz vectors” used in this work are static displacement vectors that are calculated in one of the following three ways: 1). “Load – based Ritz vectors” [1, 2, 7, 8, 12, 16–18] – This is the static displacement vector due to a static loading that is proportional to the static version of the actual (assumed dynamic) loading to which the structure is subjected. 2). “Milman – Chu vectors” [3] – This is the static Ritz vector due to the imposition of equal and opposite static loads on the two masses to which the non-linear element is connected. The loading used to generate the first M – C vector is dictated by the location of the non-linearity. 3). “K – B (Kumar – Burton) vector” – This is a new Ritz vector defined in the spirit of the Milman – Chu vector. The K – B vector is the static displacement vector due to the imposition of a). equal and opposite static loads on the two masses to which the nonlinear element is connected (i.e. same as M – C loading) and b). equal and opposite static loads on the nearest neighbors. Thus, four masses are statically loaded. As for the M – C vector, the K – B loading is dictated by the location of the nonlinear element. The nonlinear model is numerically integrated to generate a full ODE model solution, which we call the “baseline solution”. We select a set of POD modes of the baseline nonlinear system response as basis functions. The POD modes are then augmented by various combinations of the three aforementioned Ritz vectors to generate reduced order models for system having parameters in vicinity of baseline system parameters. Our results indicate that the K – B augmentation vector combined with the Milman – Chu vector is an effective way to account for nonlinear effects for the system considered. The use of combined M – C/K – B augmentation also expands the range of system parameters for which the baseline POD modes provide accurate reduction. This is considered to be a significant result.
Accounting for Roller Dynamics in the Design of Bifilar Torsional Vibration Absorbers
Authors: Monroe Ryan J. , Shaw Steven W. , Haddow Alan H. , Geist Bruce K.
Published: July 2010

Centrifugal pendulum vibration absorbers are used for reducing torsional vibrations in rotating machines. The most common configuration of these devices utilizes a bifilar suspension in which the absorber mass rides on a pair of rollers, whose mass is small compared to that of the absorber. These rollers are typically solid steel cylinders that allow the CPVAs to move along a prescribed path relative to the rotor, determined by the shape of machined cutouts on the rotor and the absorber mass. Previous studies have considered how to account for the roller dynamics in selecting the linear tuning characteristics of the absorber system, but have not quantified the errors induced by the common approximations that either ignores their effects completely, or does not account for the nonlinear aspects of their dynamics. In this paper we systematically investigate these effects. Specifically, we first show that there exists an absorber path for which the absorber/roller system maintains the same frequency of free oscillation over all physically possible amplitudes. This tautochronic path has been well known for the case with zero roller inertia, and herein, for the first time, the corresponding path with rollers is shown to exist and is constructed. In addition, we carry out an analysis of the steady-state response of the rotor/absorber/roller system in order to quantify the effects of various approximations commonly used in regards to the roller dynamics. This analysis is based on the equations of motion, scaled in such a manner so that they are amenable to a perturbation analysis, which includes the effects of rollers in the perturbation terms. It is shown that if one accounts for the linear tuning aspects of the rollers, the system response is essentially insensitive to the selection of the nonlinear tuning parameter, so long as it is close to the tautochronic value. This implies that the approximation commonly used for selecting absorber paths with rollers is adequate.
Segment-Type Energy Harvester Powering Wireless Sensor for Building Automation
Authors: Lee Soobum , Youn Byeng D. , Jung Byungchang
Published: July 2010

This paper presents an innovative design platform of piezoelectric energy harvester (EH), named segment-type EH, and its application to a wireless sensor. Energy harvesting technology is motivated to minimize battery replacement cost for wireless sensors, which aims at developing self-powered sensors by utilizing ambient energy sources. Vibration energy is one of widely available ambient energy sources which can be converted into electrical energy using a piezoelectric material. The current state-of-the-art in piezoelectric EH technology mainly utilizes a single natural frequency which is less effective when utilizing a random ambient vibration with multimodal frequencies. This research thus proposes the segment-type harvester to generate electric power efficiently which utilizes multiple modes by separating the piezoelectric material. In order to reflect the random nature of ambient vibration energy, a stochastic design optimization is solved to determine the optimal configuration in terms of energy efficiency and durability. A prototype is manufactured and mounted on a heating, ventilation, air conditioning (HVAC) system to operate a temperature wireless sensor. It shows its excellent performance to generate sufficient power for a real time temperature monitoring for building automation.
Thermoelastic Whirling Analysis of Cylinders During Grinding
Authors: Keskinen Erno , Karvinen Timo , Dospel Vladimir , To¨ho¨nen Mika , Syrja¨nen Teppo , Koponen Janne
Published: July 2010

Cylinder grinding has been the subject for an intensive research, because delay-type resonances, commonly known as chatter-vibrations, have been reason for serious surface quality problems in industry [1]. As a result of this activity there is available a simulation platform, on which the complete grinding process including delay-resonances can be driven [2]. This platform consists of models for the grinder, for the cylindrical work piece and for the stone-cylinder grinding contact. The elastic cylinder model is based on analytical eigenfunctions in bending vibrations, which basis has been used to present the rotordynamic equations of cylinder in modal coordinates. Stone-cylinder interaction mechanism has been derived by combining the rules of mass and momentum transfer in the material removal process. The contribution of this paper is to update the platform to include the thermal effects of the work body. Following the method to use the eigenfunctions of a non-supported beam to describe the rotordynamic motion of the work body, a promising method could be to use in a similar way the eigenfunctions of a thermally isolated cylinder to solve the temperature distribution of the cylinder. The temperature distribution and terms related to the non-homogeneous boundary conditions will then be the input to the thermoelastic problem. It can be shown that the eigenfunction basis consists of trigonometric functions in axial and circumferential directions while the radial eigenfunctions are Bessel functions. The stone-cylinder interface has to be updated also to include thermal effects. A portion of the mechanical power is transferred to the work piece. The rest goes to the stone, to the material, which is removed and to the cutting coolant. On the other hand, thermal deformations modify the grinding forces, which are loading the work piece. The solution of the coupled thermal and thermoelastic problem will be done in terms of modal coordinates corresponding to the eigenfunction basis. This leads to numerical time integration of two groups of differential equations, the solution of which can be used to perform the temperature distributions and the corresponding thermal deformations.
Modeling and Control of Underwater Pan/Tilt Camera Tracking System
Authors: Ji Yingfeng , Amano Ryoichi S. , Perez Ronald A.
Published: July 2010

Biologists study on the biological behavior of various marine creatures in situ using underwater observation systems. However, darkness in an underwater environment is always one of the most difficult problems to overcome in order to clearly monitor the life of underwater creatures. In this research, a light-following scheme is proposed with the lighting device installed on a separate Pan/Tilt platform as a slave while the main Pan/Tilt camera platform works as a master. A dynamic model of Pan/Tilt platform was developed using the Lagrange’s equation. In order to achieve high speed manipulation of the Pan/Tilt platforms in underwater environment, hydrodynamic forces have to be considered. Scientists had done a great deal of researches on the hydrodynamic forces of underwater motion bodies. Most of the researches employed the semi-empirical equation based on the experimental study. The coefficients (Cd Cm) of drag and added-mass which were solved by experimental study were the research point of hydrodynamic modeling in previous researches. However, these modeling methods can be employed for the underwater bodies with the simple geometry dimension. Two hydrodynamic torque models which represent the degree of freedoms (DOFs) of panning and tilting respectively had been developed employing CFD software. The selection of turbulence models, i.e., K-E, K-W, SST, RSM and LES, was firstly accomplished using the case of turbulence flow over flat plane. The hydrodynamic torque models are obtained with the simulations results for a certain range of position and velocity values for each of DOFs. The maximum velocity for simulation was set at 60 rpm for each axis. The geometry model which represents the space relationship between the master (camera) and slave (light) and the control algorithms would be elaborated in a separate paper.
Robust Modelling Using Bi-Lateral Delay Lines for Real Time and Faster Than Real Time System Simulation
Authors: Krus Petter
Published: July 2010

A very suitable method for modelling and simulation of large complex dynamic systems is represented by distributed modelling using transmission line elements (or bi-lateral delay lines). This method evolves naturally for calculation of pressures when hydraulic pipelines are modelled with distributed parameters. It is also applicable to other physical systems, such as mechanical, electrical, gas etc. One interesting application for distributed solvers using bi-lateral delay lines is in real time simulation. Modelling for real-time applications puts special requirements on robustness in the numerical methods used. In real-time applications there is no room for decreasing time step in numerically critical stages. Furthermore, if a system is relaying on a real-time simulation for its functionality, failure in the numerical properties is unacceptable. It is also in many applications possible to simulate the system faster than real time, which means that high fidelity system simulation can be used to plan ahead in control applications, and for simulation based optimisation.
Simplified Tele-Operation of Mobile-Manipulator Systems Using Knowledge of Their Singular Configurations
Authors: Frejek Michael C. , Nokleby Scott B.
Published: July 2010

An algorithm for the simplified tele-operation of a mobile-manipulator system is presented. It allows for unified, intuitive, and coordinated control. Unlike other approaches, the mobile-manipulator system is modelled and controlled as two separate entities rather than as a whole. The algorithm consists of three states. In the first state, a joystick is used to freely control the manipulator’s position and orientation. The second state occurs when the manipulator approaches a singular configuration. This causes the mobile base to proceed in such a way as to keep the end-effector moving in its last direction. This is done through the use of a simple optimization routine. The third state is triggered by the user: once the end-effector is in the desired position, the mobile base and manipulator both move with respect to one another keeping the end-effector stationary and placing the manipulator into an ideal configuration. The proposed algorithm avoids the problems of algorithmic singularities and simplifies the control approach. A preliminary version of the algorithm has been implemented on the Jasper mobile-manipulator system with success.
PROMPT: A Small Walking Robot for Planetary Exploration
Authors: Rocheleau Simon G. , Duchaine Vincent , Bochud Pascal , Gosselin Cle´ment
Published: July 2010

Planetary exploration has already taken place for several years now using wheeled rovers. However, even though successful, these missions are limited to relatively flat and sedentary grounds. The areas explored are very interesting, but are of less importance from the point of view of searching for potential traces of life when compared to certain riskier zones. It is well understood that space agencies cannot afford the risk of using costly robots in these zones of uncommon geology. It is therefore anticipated that space exploration will evolve towards the use of small low-cost robots mobile enough to be used on rough terrains rich in geological information. This paper presents a small walking robot platform that was developed based on requirements provided by the Canadian Space Agency (CSA).
Dynamic Formation Control Using Networked Mobile Sensors and Centroidal Voronoi Tessellations
Authors: Rounds Shelley , Chen YangQuan
Published: July 2010

The main objective for this research is to design an economical and robust swarm system to achieve formation control. The system combines swarm intelligence with centroidal Voronoi tessellations (CVT) to create desired static and dynamic formations. This paper also analyzes the affect of initial starting positions and robot number on formation performance. Experiments are conducted both in simulation and on an actual mobile robot platform which show the flexible and robust nature of CVTs over other formation control algorithms.
Analyzing and Implementing a Feature Mapping Approach to CAD System Interoperability
Authors: Altidor John , Wileden Jack , Wang Yiwen , Hanayneh Leen , Wang Yan
Published: July 2010

Interoperable information exchange between computer-aided design (CAD) systems is one of the major problems to enable information integration in a collaborative engineering environment. Although a significant amount of work has been done on the extension and standardization of CAD data formats as well as the cooperation of CAD systems in both academy and industry, these approaches are generally low-level and narrowly targeted. Lack of fundamental study of interoperability and generic solution to this problem is the major issue. Our intention of this research is to design a solution of CAD feature interoperability as generic as possible based on a theoretical foundation of language types. In this paper, we present a fundamental model of semantic features and feature mapping process based on the type theory. We implement and demonstrate our approach for automated feature exchange between commercial CAD systems.
Approximation of Finite Rigid Body Motions
Authors: Mu¨ller Andreas
Published: July 2010

It is well-known that there is no integrable relation between the twist of a rigid body and its finite motion, since the angular velocity components are non-holonomic velocity coordinates. Moreover, the reconstruction of the body’s motion requires to solve a set of differential equations on the rigid body motion group. This is usually avoided by introducing local parameters (e.g. Euler angles) so that the problem becomes an ordinary differential equation on a vector space (e.g. kinematic Euler equations). In this paper the original problem on the motion group is treated. A family of approximation formulas is presented that allow reconstructing large rigid body motions from a given velocity field up to a desired order. It is shown that a k-th order accurate reconstruction requires the first k – 1 time derivative of the velocity. As an application the reconstruction formulas are used for the rotation update in a momentum preserving time stepping scheme for time integration of the dynamic Euler equations.
Towards Ubiquitous Design Support
Authors: Horva´th Imre , Rusa´k Zolta´n , Opiyo Eliab Z. , Kooijman Adrie
Published: July 2010

Efficient computer support of product innovation processes has become an important issue of industrial competitiveness in the last forty years. As a consequence, there has been a growing demand for new computer-based tools and system. Various hardware, software and knowledge technologies have been used over the years as the basis of design support systems. With the appearance of network technologies, the conventional standalone workstation paradigm has been replaced by the paradigm of web-interconnected collaborative environments. Currently, the emerging and rapidly proliferating mobile and ubiquitous computing technologies create a technological push again. These technologies force us to reconsider not only the digital information processing devices and their interconnection, but also the way of obtaining, processing and communicating product design information. Many researches and laboratories are engaged with the development of novel concepts, architectures, tools and methods for next-generation design support environments. They will integrate many resources of the current collaborative design environments with pervasive computing functionality and large-scale mobility in a volatile manner. Part of the design support tools will have fixed location, but will be remotely accessible through wireless networks. Other part of the tools will be moving with the designers as portable, embedded, wearable and transferable devices, and will feature ad hoc connectivity. These not only offer new ways for aggregation, processing and presentation of design information, but also enable alternative ways of completing design activities. Our current research concentrates on three interrelated main issues: (i) studying workflow scenarios for future design support environment, (ii) investigation and integration of multiple technologies into an ad hoc interconnected heterogeneous infrastructure, and (iii) exploring efficient methods for utilizing new affordances in supporting product innovation. In this paper we report on the results of our recent technology study that analyzed the current results and trends of ubiquitous technology development, and tried to form a vision about the possible manifestation of future ubiquitous design support environments. Essentially, they have been conceptualized as ad hoc and volatile networks of fixed and mobile information collection, processing and communication units. This network functions as a complex service provider system, with special attention to the on-demand information management in the fuzzy front end of design projects.
Fractional Order Flight Control of a Small Fixed-Wing UAV: Controller Design and Simulation Study
Authors: Chao Haiyang , Luo Ying , Di Long , Chen YangQuan
Published: July 2010

This paper focuses on designing and implementation of fractional order proportional integral (PIα) flight controller on a small fixed-wing unmanned aerial vehicle (UAV). It describes mainly the controller design and simulation studies. The basics of UAV flight control are introduced first with a special emphasis on small UAV platforms. Time domain system identification methods are tried on the UAV roll channel. A new fractional order PI controller design method is then provided based on the identified first order model. The fractional order PIα controller can outperform the traditional integer order PID controller because it has a larger memory and more candidate solutions to choose. The simulation results show the effectiveness of the proposed controller design strategy and the robustness of fractional order controller under conditions of wind gusts and various pay-loads.
Nonlinear Resonant Vibration of Counter-Shaft Gears With Fluctuating Mesh Stiffness
Authors: Parker Robert G.
Published: July 2010

This work studies the nonlinear, parametrically excited dynamics of counter-shaft gear systems. The dynamic model includes parametric excitations and tooth contact loss. The steady state response is found using perturbation analysis and compared against numerical solutions. The mesh interactions depend strongly on the relation of the two mesh periods. The closed-form solutions provide design guidelines in terms of the system parameters.
Logarithmic Complexity Sensitivity Analysis of Flexible Multibody Systems
Authors: Bhalerao Kishor D. , Poursina Mohammad , Anderson Kurt S.
Published: July 2010

This paper presents a recursive direct differentiation method for sensitivity analysis of flexible multibody systems. Large rotations and translations in the system are modeled as rigid body degrees of freedom while the deformation field within each body is approximated by superposition of modal shape functions. The equations of motion for the flexible members are differentiated at body level and the sensitivity information is generated via a recursive divide and conquer scheme. The number of differentiations required in this method is minimal. The method works concurrently with the forward dynamics simulation of the system and requires minimum data storage. The use of divide and conquer framework makes the method linear and logarithmic in complexity for serial and parallel implementation, respectively, and ideally suited for general topologies. The method is applied to a flexible two arm robotic manipulator to calculate sensitivity information and the results are compared with the finite difference approach.
Correspondence Between Intrinsic Mode Functions and Slow Flows
Authors: Lee Young S. , Tsakirtzis Stylianos , Vakakis Alexander F. , Bergman Lawrence A. , McFarland D. Michael
Published: July 2010

We study the correspondence between analytical and empirical slow-flow analyses, which will form a basis for a time-domain nonparametric nonlinear system identification method. Given a sufficiently dense set of sensors, measured time series recorded throughout a mechanical or structural system contains all information regarding the dynamics of that system. Empirical mode decomposition (EMD) is a useful tool for decomposing the measured time series in terms of intrinsic mode functions (IMFs), which are oscillatory modes embedded in the data that fully reproduce the time series. The equivalence of responses of the analytical slow-flow models and the dominant IMFs derived from EMD provides a physics-based theoretical foundation for EMD, which currently is performed formally, in an ad hoc fashion. First deriving appropriate mathematical expressions governing the empirical slow flows and based on analyticity conditions, we demonstrate only close correspondence between analytical and empirical slow flows in a physical system that can be modeled as a two-degree-of-freedom strongly nonlinear coupled oscillators.
Guiding Engineering Design Activities Through a Question Based Approach
Authors: Grebici Khadidja , Aurisicchio Marco , Bracewell Rob
Published: July 2010

The design of complex systems requires accurate planning and sequencing of the processes into task and activities. Companies such as the aerospace engine manufacturers demand effective methods and tools to support engineering designers in their tasks and activities. This paper presents exploratory research to investigate the possibility of supporting design activities through a question based approach. Sets of generic questions are extracted from the analysis of the question types proposed in previous research. The paper proposes that designers could be guided into their design inquiries by consulting the generic questions identified in this research and design knowledge indexes.