bluuebunny/crossref_metadata_2025 huggingface dataset:
Periodicity Conditions for Third-Order Nonlinear With Application to Wave Propagation in Relaxing Media
Authors: Nakhaie Jazar G. , Mahinfalah M. , Christopherson J. , Khazaei A. , Nazari G.
Published: May 2009

It is known that wave propagation in nonlinear continues media, such as acoustic waves in solids, water waves, and solitary waves in arteries, can be reduced to a third order ordinary differential equations. They can be cast in a general third order ODE as x‴‴‴+f(t,x,x′,x″)=0. However, having an ODE as a reduced model for a phenomenon expressible by a partial differential equation lacks a proof to grantee for having a periodic solution. A third-order existence theorem has been proven to establish the sufficient conditions of periodicity for the above general third-order ODE. However, the equation is too general. In this paper we examine the following more specific equation x‴‴‴+g1(x′)x″+g2(x)x′+g(x,x′,t)=e(t). and prove a new theorem to establish the sufficient condition for its periodicity. To obtain the periodicity conditions, the Schauder’s fixed-point theorem is implemented. A numerical method is also developed for rapid convergence.
A New Inverse Reliability Analysis Method Using MPP-Based Dimension Reduction Method (DRM)
Authors: Lee Ikjin , Choi Kyung K. , Du Liu , Gorsich David
Published: May 2009

There are two commonly used reliability analysis methods of analytical methods: linear approximation - First Order Reliability Method (FORM), and quadratic approximation - Second Order Reliability Method (SORM), of the performance functions. The reliability analysis using FORM could be acceptable for mildly nonlinear performance functions, whereas the reliability analysis using SORM is usually necessary for highly nonlinear performance functions of multi-variables. Even though the reliability analysis using SORM may be accurate, it is not desirable to use SORM for probability of failure calculation since SORM requires the second-order sensitivities. Moreover, the SORM-based inverse reliability analysis is very difficult to develop. This paper proposes a method that can be used for multi-dimensional highly nonlinear systems to yield very accurate probability of failure calculation without requiring the second order sensitivities. For this purpose, the univariate dimension reduction method (DRM) is used. A three-step computational process is proposed to carry out the inverse reliability analysis: constraint shift, reliability index (β) update, and the most probable point (MPP) approximation method. Using the three steps, a new DRM-based MPP is obtained, which computes the probability of failure of the performance function more accurately than FORM and more efficiently than SORM.
Internal Resonance and Localization in Micro-Resonator Arrays
Authors: Dick Andrew J. , Balachandran Balakumar , Mote C. Daniel
Published: May 2009

Intrinsic Localized Modes (ILMs) are localization caused by intrinsic nonlinearities within an array of perfectly periodic oscillators. This localization phenomenon is studied in the context of arrays of coupled micro-scale cantilevers and of coupled piezoelectric micro-scale resonators. Recent studies have identified the individual devices to be capable of producing nonlinear behavior and efforts are currently underway to develop resonator arrays to improve performance capabilities. It is important to determine whether an ILM would limit the performance of such an array and/or if one could take advantage of this type of localization in filter design. Previous studies have shown that it is possible to realize ILMs as forced nonlinear vibration modes. The effects of internal resonance conditions on the behavior of these localization events are explored here using analytical and numerical methods.
A Structure Excited by a DC Motor of Limited Power Supply and Controlled by a Pendulum Like Device
Authors: Brasil R. M. L. R. F. , Feitosa L. C. , Balthazar J. M.
Published: May 2009

In this paper, a mathematical model is derived via Lagrange’s Equation for a shear building structure that acts as a foundation of a non-ideal direct current electric motor, controlled by a mass loose inside a circular carving. Non-ideal sources of vibrations of structures are those whose characteristics are coupled to the motion of the structure, not being a function of time only as in the ideal case. Thus, in this case, an additional equation of motion is written, related to the motor rotation, coupled to the equation describing the horizontal motion of the shear building. This kind of problem can lead to the so-called Sommerfeld effect: steady state frequencies of the motor will usually increase as more power (voltage) is given to it in a step-by-step fashion. When a resonance condition with the structure is reached, the better part of this energy is consumed to generate large amplitude vibrations of the foundation without sensible change of the motor frequency as before. If additional increase steps in voltage are made, one may reach a situation where the rotor will jump to higher rotation regimes, no steady states being stable in between. As a device of passive control of both large amplitude vibrations and the Sommerfeld effect, a scheme is proposed using a point mass free to bounce back and forth inside a circular carving in the suspended mass of the structure. Numerical simulations of the model are also presented.
Reliability Based Design Optimization With Correlated Input Variables Using Copulas
Authors: Choi Kyung K. , Noh Yoojeong , Du Liu
Published: May 2009

For the performance measure approach (PMA) of RBDO, a transformation between the input random variables and the standard normal random variables is necessary to carry out the inverse reliability analysis. For reliability analysis, Rosenblatt and Nataf transformations are commonly used. In many industrial RBDO problems, the input random variables are correlated. However, often only limited information such as the marginal distribution and covariance could be practically obtained, and the input joint probability distribution function (PDF) is very difficult to obtain. Thus, in literature, most RBDO methods assume all input random variables are independent. However, in this paper, it is found that the RBDO results can be significantly different when the input variables are correlated. Thus, various transformation methods are investigated for development of a RBDO method for problems with correlated input variables. It is found that Rosenblatt transformation is impractical for problems with correlated input variables due to difficulty of constructing a joint PDF from the marginal distributions and covariance. On the other hand, Nataf transformation can construct the joint CDF using the marginal distributions and covariance, and thus applicable to problems with correlated random input variables. The joint CDF is Nataf model, which is called a Gaussian copula in the copula family. Since the Gaussian copula can describe a wide range of the correlation coefficient, Nataf transformation can be widely used for various types of correlated input variables. In this paper, Nataf transformation is used to develop a RBDO method for design problems with correlated random input variables. Numerical examples are used to demonstrate the proposed method. Also, it is shown that the correlated random input variables significantly affect the RBDO results.
Solving the LQ and Non-Conventional Performance Index Optimal Problem With the Use of the Simulated Annealing Algorithm
Authors: Marti´nez-Alfaro Horacio , Valenzuela-Rendo´n Manuel
Published: May 2009

An approach to solve the discrete-time, time-invariant linear quadratic optimal control problem is presented. The design approach presented in here transforms the LQ problem into a combinatorial optimization problem and uses the Simulated Annealing algorithm to optimize the performance index. In addition, a non-conventional performance index is proposed. Some SISO and MIMO systems are tested. Results proved the approach to be an excellent option to find a solution to the problem.
A XML-Based Shop Floor Adaptive Scheduler Design
Authors: Wang Weida , Liu Xinhua , Liu Wenjian , Luo Yang
Published: May 2009

Due to the complex, uncertainty and dynamic in the modern manufacturing environment, a flexible and robust shop floor scheduler is essential to achieve the system production goals. The paper proposes a design framework of shop floor scheduler. The details of its function modules were discussed. An adaptive scheduling strategy and a XML-based process plan representation were utilized in the scheduler, which acquires the dispatching rule from the knowledge base and uses the build-in on-line simulator to evaluate the rule. These technologies enable the scheduler has a good fine-tune ability and transfers effectively process information to other heterogeneous information systems in a shop floor. The framework introduced in the paper has been demonstrated with a manufacturing case.
The Effect of Visco-Elastic Core Thickness on Modal Loss Factors of a Thick Three-Layer Cylinder
Authors: Hamidzadeh Hamid R.
Published: May 2009

Free vibration of damped three-layer sandwich cylinders with thick layers is considered. In particular, the effect of the different thicknesses for the middle layer on the overall natural frequencies and modal damping factors are studied. The constrained layer damping is accomplished by sandwiching a linear visco-elastic material between two isotropic elastic cylinders with the same properties. The governing equations are derived using the theory of elasto-dynamic, by employing complex elastic moduli for the sandwiched layer. Dimensionless natural frequencies and modal loss-factors for the first three thickness modes associated with wave numbers of n = 0, 1, 2, 3, and 4 are tabulated for a range of thicknesses for the middle visco-elastic layer while keeping the thicknesses of inner and outer layers unchanged.
Folksonomy and Designing: An Exploration
Authors: Titus Noel , Subrahmanian Eswaran , Ramani Karthik
Published: May 2009

This paper discusses the role of folksonomy in a product design scenario. The focus is on developing a framework for design retrieval using a folksonomic approach and on the emergence of a design taxonomy through user tagging. We analyze the potential uses of a design folksonomy and its relation to current design research. We specifically relate the folksonomy to design representation models, design teams and knowledge sharing and collaboration. Folksonomy is the result of tagging of information objects by a user freely using keywords relevant to the object being tagged. The tags are applied based on the user’s understanding of the information and utilizes the user’s vocabulary. This metadata generated by tagging is shared in a social environment i.e. across a body of users. “The collective metadata in the folksonomy representation is stored in the form of three data points, viz., the person doing the tagging, the object that is tagged, and the tag that has been applied to the object.” [37] In this paper, the utility of tagging is discussed in a product design context for retrieval of information, locating individuals with similar vocabulary and hence similar interests, and other people utilizing the same objects. We discuss a design information representation model where the folksonomy-based bottom up method and traditional top-down methods of ontology and taxonomy play complementary roles. An approach to implementing a framework for a product design folksonomy is also suggested in this paper.
Enhancing a Traditional Ergonomics Tool With Capabilities and Algorithms From Immersive Environments
Authors: Kim OkJoon , Jayaram Uma , Jayaram Sankar , Palmer Craig
Published: May 2009

This paper presents our continuing work in approaches to link traditional, commercially available ergonomics evaluation tools with virtual environment tools for providing enhanced capabilities for engineering design. Ergonomic evaluation tools in engineering design are fairly mature and are used in important and specific ways to analyze human model postures in industry. The promising capabilities of immersive environment tools such as realistic environments and interactions, constraint-based modeling, and physically-based modeling are attractive to industry but have so far been available only in environments separate from the traditional ergonomics analysis tools. Our research seeks to create well-integrated synergistic approaches that will complement traditional ergonomics tools with a careful assimilation of capabilities and algorithms from a virtual environment. The information exchange, representations, communication, and computational issues involved in achieving this connectivity are discussed in this paper. We demonstrate this functionality between a commercial ergonomics tool and an immersive assembly system. It is anticipated that this synergy between an ergonomics tool and a virtual environment will lead to breakthroughs and ease of use benefits similar to those that have now been obtained by the close integration of CAD and virtual environments.
A 3D Graphical Method for Interactively Determining the Vertical Convexity of Designs to be Molded
Authors: Bailey Mike , Clark Dru , Rapp John
Published: May 2009

The Center for 3D Visualization Hardcopy (C3VH) was initiated in 1995 as a web-accessible facility to create 3D physical models. By making such prototyping hardware easy to access and the geometry files easy to check and correct, we have been able to drive the model-making process into the less traditional manufacturing area of scientific visualization. But, there have been requests for many copies of a single model. As “rapid” prototyping is actually quite slow and unsuitable for mass production, these requests have required us to enter the world of molding for mass production. As part of this, we have needed to quickly determine how feasible it is to mold a particular model. This paper shows an interactive OpenGL method that we developed for determining the optimal orientation for a model’s parting line. By using a novel OpenGL stencil buffer technique, the user can reorient the model on the screen, and see from the colors in the display how vertically convex it is in that orientation, and in what parts of the model it is not vertically convex.
Periodic Motions of the Machine Tools in Cutting Process
Authors: Gegg Brandon C. , Suh Steve S. , Luo Albert C. J.
Published: May 2009

In this paper, a two-degree of freedom dynamical system with discontinuity is developed to describe the vibration in the cutting process. The analytical solutions for the switchability of motion on the discontinuous boundary are presented. the switching sets based on the discontinuous boundary is introduced and the basic mappings are introduced to investigate periodic motion in such a mechanical model. The mapping structures for the stick and non-stick motions are discussed. Numerical predictions of motions of the machine tool in the cutting process are presented through the two-degree of freedom system with discontinuity. The phase trajectory and velocity and force responses are presented and the switchability of motion on the discontinuous boundary is illustrated through force distribution and force product on the boundary.
Quasi-Optimal Mesh Segmentation Via Region Growing/Merging
Authors: Mizoguchi Tomohiro , Date Hiroaki , Kanai Satoshi , Kishinami Takeshi
Published: May 2009

Recently meshes of engineering objects are easily acquired by 3D laser or high energy X-ray CT scanning systems, and these meshes are widely used in product developments. To effectively use scanned meshes in engineering applications, such as inspection, CAD model reconstruction, and convergent-type CAE, we need to segment meshes and extract desirable regions and their approximating surfaces as preprocessing. Engineering objects are commonly represented as a set of analytic surfaces, such as planes, cylinders, spheres, cones, and tori. Therefore, the mesh surface of engineering objects needs to be approximated as a set of analytic surfaces. Moreover, a mesh surface should be approximated with a minimum number of analytic surfaces and their approximating error should be minimized as a result of segmentation. We call the segmentation that satisfies these two conditions the optimal segmentation as proposed in [1]. However, optimal segmentation algorithms need a long calculation time. Today’s high energy X-ray CT scanning systems generate large meshes with millions of triangles from objects including hundreds of regions. Thus, computationally expensive algorithms, such as [1], cannot be directly applied to these large and complex meshes from the aspect of efficiency. In this paper we propose an efficient new quasi-optimal mesh segmentation algorithm via region growing and region merging. First, our algorithm robustly and accurately estimates mesh principal curvatures using the local surface fitting by two-pass algorithm. Second, it uses the curvatures to appropriately create seed regions, and then it quickly grows each seed region and extracts grown regions and their approximating analytic surfaces from a whole mesh. Finally, our region merging algorithm efficiently merges extracted regions in order to minimize the number of regions while keeping the user specified tolerances of the surface fitting, and it results in quasi-optimal segmentation. We demonstrate the performance of our algorithm with scanned meshes acquired from real engineering objects by 3D laser and X-ray CT scanning systems.
Design and Manufacturing Education Utilized Digital Engineering
Authors: Yamanaka Masashi
Published: May 2009

The most effective method in design and manufacturing education is to experience the series of processes, which are to be given a design subject, the design of the machine to qualify the specification, to manufacture or buy necessary parts, the assembly and the evaluation of performance, by oneself or few people. Firstly, the items to learn and improve in the course for the attending student were listed up and examined. These become the evaluation items of the program by the attending student. The program called ‘Clock Project’ was developed. The subject is to design the clock that displays ‘hour’ and ‘minute’. Various restrictions are installed in the size of machine, the parts can be used and etc. The evaluation function to decide the excellent/poor design is the number of parts. The design with small number of parts becomes an excellent one. A couple of students struggle with the program with collaboration. 3-D CAD is used to design and the efficiency is improved comparing with ordinary hand drafting. Moreover, the digital engineering such as a RP (Rapid Prototype) equipment and EC (Electric Commerce) service for the order of parts are utilized fully. As the result, the management cost was reduced drastically. The participated team designed unique clocks. There was no same clock though many types clock were designed in the class. The creativity is inspired through this program. In the paper, the progressed points are explained comparing with the ordinary educational program. And it is examined that whether the expected effect is obtained or not based on the result of evaluation by the students.
Seismic Response Control for Four High-Rise Building Structures Using Connected Control Method
Authors: Seto Kazuto , Iio Chinori , Inaba Shigeru , Mitani Shingo , Dohnal Fadi , Watanabe Toru
Published: May 2009

This paper presents a vibration control method for multiple high-rise buildings against large earthquake motion. This method is called as “Connected Control Method (CCM)” and has the merit of obtaining enough control force to protect high-rise buildings from large earthquakes using passive and semiactive devices. In this paper, first a modeling approach for four scaled building structures is shown and effectiveness of the CCM using LQ control approach for them is demonstrated by seismic response control results. Next, in order to reduce the supplied power, a semi-active control approach in place of active control is applied for the CCM. For this purpose, a new MR damper is developed and designed to have a close performance with results of the LQ control. This performance is verified by measured frequency responses.
Architecture for the Integration of High Performance Computing Applications in PLM
Authors: Anderl Reiner , Yaman Orkun
Published: May 2009

High Performance Computing (HPC) has become ubiquitous for simulations in the industrial context. To identify the requirements for integration of HPC-relevant data and processes a survey has been conducted concerning the German car manufacturers and service and component suppliers. This contribution presents the results of the evaluation and suggests an architecture concept to integrate data and workflows related with CAE and HPC-facilities in PLM. It describes the state of the art of HPC-applications within the simulation domain. Intensive efforts are currently invested on CAE-data management. However, an approach to systematic data management of HPC does not exist. This study states importance of an integrating approach for data management of HPC-applications and develops an architectural framework to implement HPC-data management into the existing PLM landscape. Requirements on key functionalities and interfaces are defined as well as a framework for a reference information model is conceptualized.
Passage Through Resonance in a Vibration Isolation System (Effects of Rate of Increasing the Voltage Applied to D.C. Motor)
Authors: Tange Tomohiko , Kawana Ryo , Tokoyoda Tetsuro , Yoshizawa Masatsugu , Sugiura Toshihiko
Published: May 2009

This paper deals with transient nonlinear vibration of a rigid body suspended on a foundation by elastic springs and constrained in a plane. In such a three degree-of-freedom vibration isolation system, we assume that ‘2-1-1’ internal resonance exists between the vertical and horizontal vibrations of the rigid body and the rotational vibration about its center of gravity. Our main purpose is to examine theoretically the transient behavior passing through resonance under the condition that the D.C. motor directly drives the unbalanced rotor. Numerical simulation was carried out to clarify effects of rate of increasing V(t) on the peak amplitude of the vibration of the rigid body and on the driving torque of the D.C. motor. Moreover, experiment was conducted with a physical model of a three degree-of-freedom vibration isolation system, and the transient behavior passing through resonance was observed and compared with theoretical results in a typical case with internal resonance.
Vibration Analysis of a Railway Carbody Model as a Non-Circular Cylindrical Shell
Authors: Kobayashi Yukinori , Ishiguri Kotaro , Tomioka Takahiro , Hoshino Yohei
Published: May 2009

Railway carbody is modeled as a non-circular cylindrical shell with simply-supported ends in this paper. The shell model doesn’t have end plates of the carbody and other equipments attached to actual carbody are neglected. We have applied the transfer matrix method (TMM) to the analysis of three-dimensional elastic vibration problems on the carbody. We also made a 1/12 size carbody model for experimental studies to verify the validity of the numerical simulation. The model has end plates and was placed on soft sponge at both ends of the model to emulate the freely-support. The modal analysis was applied to the experimental model, and natural frequencies and mode shapes of vibration were measured. Comparing the results by TMM and the experiment, natural frequencies and mode shapes of vibration for lower modes show good agreement each other in spite of differences of boundary conditions.
Pareto Optimal Structural Models and Predictions Consistent With Data and Modal Residuals
Authors: Ntotsios Evaggelos , Christodoulou Konstantinos , Papadimitriou Costas
Published: May 2009

A multi-objective identification method for model updating based on modal residuals is proposed. The method results in multiple Pareto optimal structural models that are consistent with the measured modal data, the class of models used to represent the structure and the modal residuals used to judge the closeness between the measured and model predicted modal data. The conventional single-objective weighted modal residuals method for model updating is also used to obtain Pareto optimal structural models by varying the values of the weights. Theoretical and computational issues related to the solution of the multi-objective and single optimization problems are addressed. The model updating methods are compared and their effectiveness is demonstrated using experimental results obtained from a three-story laboratory structure tested at a reference and a mass modified configuration. The variability of the Pareto optimal models and their associated response prediction variability are explored using two structural model classes, a simple 3-DOF model class and a higher fidelity 546-DOF finite element model class. It is shown that the Pareto optimal structural models and the corresponding response predictions may vary considerably. The variability of Pareto optimal structural model is affected by the size of modelling and measurement errors. This variability reduces as the fidelity of the selected model classes increases.
Assessment of a Plastic Optic Fiber Sensor for the Measurement of Static and Dynamic Strains
Authors: Sun Rongqiang , Oyadiji S. Olutunde
Published: May 2009

Optical sensor offers remarkable advantage compared with traditional sensor, such as electromagnetic immunity, small size, and light weight. A low-cost intensity-based plastic optical fibre (POF) sensor is presented in this paper to measure both static and dynamic strain on a cantilevered beam. The principle of measurement is that the intensity of transmitted light changes as strain changes. By detecting the transmitted light intensity, the change of strain can be measured. First, the principle and design of the sensor are presented. Three POF sensors made using three types of housings (silicon rubber tube, rubber tube and PTFE tube) are evaluated to compare their performance, such as sensitivity, resolution and linearity. A comparison of the strain response of these sensors in static test shows that the soft material (silicon rubber and rubber tube) offers better sensitivity than that of hard material (PTFE tube). However, in dynamic test, PFTE tube gives faster response time compared with rubber tube which is not suitable for high speed test (1k Hz). Both static and dynamic test results have shown that all sensors offer excellent agreement with electrical strain gauge readings and the sensitivity of POF sensor can be up to 20 μ strain. Strain transfer function is also conducted to examine the ability of optical sensors in detection of vibration modes of a cantilevered beam. A PCB piezoelectric accelerometer sensor is attached to the beam as well to measure the acceleration transfer function of the beam, which is used as a reference signal. The results also showed the possibility that POF sensors can be used for structural health monitoring.
Variant Indication Analysis: An Integrated Component of a Variable Process Model for Global Platforms
Authors: Gunzenhauser Martin , Gander Gregor E. J. , Bongulielmi Luca
Published: May 2009

Globalization pressures lead companies of the capital-intensive goods industry to follow the example of the automotive industry and develop global platform-based products. One of the most difficult task is to cover all kinds of local standards, laws, and regulations within the platform. Supplementary strong variations in the purchasing power of customers, education of work forces, and availability of technology or mere fashions in local markets have an impact on regional business processes. Thus, undesirable and unplanned redesigns become necessary during the localization of a global product family into its regional markets. Hence, this paper discusses a platform process, which incorporates life cycle and value chain thinking into the product structuring process. This process is supported by a Component Box platform model offering robustness for component re-use and flexibility for local differentiation. Moreover it facilitates the collaborative product development by an enhanced transparency throughout the entire process.
A New Look at the Fractional Brownian Motion Definition
Authors: Ortigueira Manuel Duarte , Batista Arnaldo Guimara˜es
Published: May 2009

A reinterpretation of the classic definition of fractional Brownian motion leads to a new definition involving a fractional noise obtained as a fractional derivative of white noise. To obtain this fractional noise, two sets of fractional derivatives are considered: a) the forward and backward and b) the central derivatives. For these derivatives the autocorrelation functions of the corresponding fractional noises have the same representations. The obtained results are used to define and propose a new simulation procedure.
Dynamic Investigation on a Pelton Runner: FEM Calculation and Experimental Results
Authors: Pesatori Emanuel , Turozzi Giorgio , Pennacchi Paolo , Tosi Alessandro
Published: May 2009

The dynamical phenomena involving a Pelton runner during normal operation are getting more and more of concern in the design of such kind of turbines. In fact, the increasing of the performance required by the market imposes runner designs that can become critical from a structural point of view. Each bucket is subjected to a certain number of impulses per revolution corresponding to the number of nozzles. This high frequency load could lead to a strong dynamic response of the runner if some kind of resonance takes place. For these reasons, an accurate modal analysis is to be performed before the runner realization, in order to avoid any crack arising during operation. This paper describes how a new, high performance profiled Pelton runner was modeled and dynamically calculated by FEM code ANSYS in order to obtain its natural frequencies and mode shapes. Subsequently, the modal behavior of the runner was experimentally investigated by means of an impulse test on field. The natural frequencies were got by examinating the FFT of the response and the mode shapes were reconstructed according to the stored signals of the accelerometers. The match between the experimental and numerical data was pretty good.
The Influence of Nonlinear Air Drag on Microbeam Response for Noncontact Atomic Force Microscopy
Authors: Gottlieb O. , Hoffman A. , Wu W. , Maimon R. , Edrei R. , Shavit A.
Published: May 2009

In this paper we formulate and analyze a continuum model for the vibration of a noncontacting atomic force microscope (AFM) microbeam in air that consistently incorporates nonlinear geometric and inertia effects, localized atomic interaction, viscoelastic damping and quadratic drag. We investigate a controlled set of experiments that include both free vibration decay of a large Silicon beam and forced vibration response of an AFM Silicon microbeam mapping a Silicon sample for various initial interaction distances. Nonlinear frequency and damping backbone curves are obtained from free vibration decay data and equivalent damping ratios are deduced from forced vibration frequency response. Estimation of the system linear viscoelastic parameters and nonlinear drag parameters is enabled by comparison of the experimental backbone curves with those of a nonlinear modal dynamical system deduced from the continuum model. The calibration results without sample interaction include both a slight softening effect for small amplitude response due to nonlinear inertia and viscoelastic damping and a hardening effect for large amplitude response governed by nonlinear geometric effects and drag. Validation of the nonlinear model is enabled by comparison with the measured forced vibration AFM frequency response below the dynamic jump-to-contact threshold.
Neural Network Modeling and Control of Stoker-Fired Boiler Plant
Authors: Thai S. M. , Wilcox S. J. , Chong A. Z. S. , Ward J.
Published: May 2009

The work described in this paper aims to address the development of a Neural Network Based Controller (NNBC) to control chain grate stoker fired boilers. Artificial Neural Networks (ANNs) were used to estimate future emissions from and control the combustion process. The resultant ANNs were able to characterise the dynamics of the process and delivered rational multi-step-ahead predictions wth test data collected at an industrial chain grate stoker at HM Prison Garth, Lancashire. This technique was built into a carefully designed control strategy, to control the industrial stoker. Test results showed that the developed NNBC was able to optimise the industrial stoker boiler plant whilst delivering the load demand required and in so doing, the NNBC also managed to maintain low pollutant emissions.
Penetration Behaviour of Steel Plates
Authors: Abdelshafy M. H. , Oyadiji S. O.
Published: May 2009

A finite element analysis using ABAQUS v6.6 has been performed to investigate the penetration behaviour of different target structures under the impact velocities of 1000 & 1200 m/s. The analysis has been performed to study the effect of the target configuration and the effect of introducing a damping material like rubber within the target structure on the penetration behaviour of these targets. Three dimensional (3D) models of targets consisting of various discrete one, two and three layers of hardened steel have been developed. The total thickness of each single or multiple layer steel target is 25 mm. These targets have been subjected to the impact of a projectile which was either blunt or had a hemispherical end and is made from a tungsten rod. Furthermore, 3D models consisting of layers of a damping material sandwiched between steel layers have also been developed and analysed. It is found that a purely steel target of multiple layers but of the same total thickness as a single layer steel target produced less residual velocity. This implies that the multiple layer steel targets produced more penetration resistance and, therefore, absorbed more of the impact energy than the single layer steel target. Similarly, multiple layer composite targets comprising layers of a damping material sandwiched between steel layers produced a greater penetration resistance and less residual velocity than a single layer steel target. However, the multiple layer composite targets only produced a slightly greater penetration resistance and less residual velocity than a multiple layer steel target.
Dynamic Stress Concentration on a Semi-Infinite Piezoelectric Medium With a Circular Cavity Near the Surface
Authors: Song Tianshu , Wang Shilong
Published: May 2009

Dynamic interaction is investigated theoretically between a circular cavity and the surface in a semi-infinite piezoelectric medium subjected to time-harmonic incident anti-plane shearing in the present paper. The formulations are based on the method of complex variable and wave function expandedness. Dynamic stress concentration factors at the edge of the circular cavity are obtained by solving boundary value problems with the method of orthogonal function expansion. The calculating results are plotted so as to show how the frequencies of incident wave, the piezoelectric characteristic parameters of the material and the structural geometries influence upon the dynamic stress concentration factors.
Analysis of the Hex Cell Discretization for Topology Synthesis of Compliant Mechanisms
Authors: Mankame Nilesh D. , Saxena Anupam
Published: May 2009

We use non-linear finite element simulations to study the convergence behavior of the honeycomb or hex cell design discretization for optimization-based synthesis of compliant mechanisms in this paper. Adjacent elements share exactly one common edge in the hex cell discretization, unlike the square cell discretization in which adjacent elements can be connected by a single node. As the single node connections in bilinear quadrilateral plane stress elements allow strain-free relative rotations, compliant mechanism designs obtained from square cell discretizations with these elements often contain elements with single node connections or point flexures. Point flexures are sites of lumped compliance, and as such, are undesirable as they lead to compliant mechanisms designs which deviate from the ideal of distributed compliance. The hex cell design discretization circumvents the problem of point flexures without any additional computational expense (e.g. filtering, extra constraints, etc.) by exploiting the geometry of the discretization. In this work we compare the elastic response of a group of four cells in which two adjacent cells have the least connectivity in both: the square and the hex discretizations. Simulations show that the hex cell discretization leads to a more accurate modeling of the displacement, stress and strain energy fields in the vicinity of the least connectivity regions than the square cell discretization. Therefore, the hex cell discretization does not suffer from stress singularities that plague the square cell discretization. These properties ensure that continuous optimization-based compliant mechanism synthesis procedures that use the hex cell discretization, exhibit a faster and more stable convergence to designs that can be readily manufactured than those that use the square cell discretization.
On the Inharmonicity of a String
Authors: Nakai Mikio , Kawaguchi Kazuya
Published: May 2009

This paper describes the phenomenon called the inharmonicity for struck and plucked strings. Its spectral components consist of two inharmonic peak series: ‘first partials’ due to the elastic stiffness of a string and ‘second partials’. Experimental tests for examining second partials were performed with a monochord string. The experiments suggest that second partials are those that have frequencies equal to the sum of two normal first partials. Numerical simulations were done mainly for struck string by nonlinear equations involving both longitudinal and transverse vibrations of large deflected string. In these simulations, a triangular wave was assumed as an impulse function, and furthermore, a V notch shape was taken as initial displacement.
Development of Kansei Design System Using Image Processing
Authors: Arakawa Masao , Kitajima Hiroyuki , Ishida Masahiro , Manabe Tadaharu
Published: May 2009

It is often said that it might be very important to take Kansei, some kind of human sensuous inspiration, into account of design. And it becomes more and more important especially in the design of products whose functions are saturated and it becomes difficult to gain competitive power only by adding a new function. In those cases, it is difficult to gain competitive power by neither discounting its prices nor making efforts in human engineering sense of ease in handling. In such cases, visual design will be more important, so that visual designers become key of success in the product. However, Kansei design used to be based on questionnaires to the customers, and it is basically based on putting emphasis on the greatest common of them. But, in most of cases visual designers would like to show their feelings into design and lead majority to his or her sense. So that Kansei design database is often useless to them and it is sometimes obstacle for their creativity. In this paper, we will propose the Kansei design system which is based on image processing system and qualifying image by using Fourier transform and make up a new visual design by using those Fourier transform data. As an example, we have used the proposed system in design of doors. We have verified the results by inspiration test and brain test and showed a possibility of the proposed method.
Comparison of Active Control Algorithms for Rotor Unbalance Compensation
Authors: Tammi Kari , Laiho Antti
Published: May 2009

This paper shows a short introduction to three unbalance compensation algorithms and an experimental comparison of those algorithms. The algorithms have been tested experimentally on a laboratory-scale test rig equipped with an electromagnetic actuator. So called Convergent Control algorithm has been found the most suitable for the current purpose in terms of performance and simplicity. The algorithms are subjected further tests on rotor unbalance compensation in an electrical machine. This paper shows some initial considerations for those further tests.
Identifying a Transfer Function From a Frequency Response
Authors: Ortigueira Manuel Duarte , Vale´rio Duarte , Sa´ da Costa Jose´
Published: May 2009

In this paper, the classic Levy identification method is reviewed and reformulated using a complex representation. This new formulation is able to solve the well known bias of the classic method at low frequencies. The formulation is generic, addressing both integer order and fractional order transfer functions. A new algorithm based on a stacked matrix and its pseudo-inverse is proposed to accommodate the data over a wide range of frequencies. Several simulation results are presented, together with a real system identification. This system is the Archimedes Wave Swing, a prototype of a device to convert the energy of sea waves into electricity.
Configuration Bifurcation Characteristics of the Semi-Regular Hexagon Gough-Stewart Parallel Manipulator
Authors: Wang Yu-Xin , Li Yu-Tong , Wang Yi-Ming , Yan Xiu-Tian
Published: May 2009

Type-II singularities exist in parallel manipulators commonly. At this kind of singularities, the end-effector is locally movable and uncertain even when all the actuate joints are located. In order to explore a possible approach to obtain the concrete output of the mobile platform at the very small vicinity (germ space) of the singular point, in this paper, the configuration bifurcation characteristics at the germ space have been investigated. At first, the type-II singularity has been identified with Golubitsky-Schaeffer normal form. The result shows that the type-II singular points belong to the turning points. Then, the configuration bifurcation equation is reduced into one dimensional form. Based on this one dimensional equation, the unperturbed and perturbed configuration bifurcation behaviors at the germ space of the turning point have been analyzed. It is found that all configuration branches converged in the same singular point in the unperturbed system can be separated in the perturbed system. This discovery has presented a possible approach to control the parallel manipulator passing through the singular point with a desired configuration.
Computerized Modeling and Simulation of Idle and Loaded Multi-Tooth Contact Analysis in Worm-Face Gear Drives
Authors: Napau Mircea , Napau Ileana D. , Napau Ioan , Maties Vistrian , Napau-Stoica Ana A. , Napau-Stoica Radu C.
Published: May 2009

The virtual simulation methods used in the gear industry allow for the prediction of requirements in the gears manufacturing process, as well as, prediction of their mesh before they are manufactured. The aim of this paper is to present an approach regarding the virtual simulation of multi-tooth contact analysis of worm-face gear drives used in the automotive industry. The methods presented in this paper are intended to reduce the process development phase of gearboxes, having as components, worm-face gear drives and thus saving large amounts of time and money. A procedure has been developed in order to simulate the idle multi-tooth contact, in a worm-face gear drive with localized contact, as a combinative algorithm of using a virtual manufacturing method and the power of MathCAD software. Virtual simulation of loaded multi-tooth contact analysis has been carried out together with the contact stress analysis by FEA method using ANSYS software. The FEM models have been developed by Computer Manufacturing Simulation (CMS) method. 3D CAD examples illustrating the idle contact pattern on face gear teeth flanks are presented for both directions of rotation of the driving worm. Numerical results related to the loaded multi-tooth contact analysis and contact stress analysis, respectively, are also provided in order to illustrate the developed approach.
Tactile Whole-Field Imaging Sensor on Photoelasticity
Authors: Dubey Venketesh N. , Grewal Gurtej S.
Published: May 2009

The paper describes a whole-field imaging sensor developed on the principles of photoelasticity. The sensor produces colored fringe patterns when load is applied on the contacting surface. These fringes can be analyzed using conventional photoelastic techniques, however, as the loading in the present case is not conventional some new strategies need to be devised to analyze the load imprint. The loading is unconventional in the sense that low modulus photoelastic material is deformed under vertical load in the direction of light travel to induce the photoelastic effect. The paper discusses the efficacy of both RGB calibration and phase shifting techniques in sensing applications. The characteristics of fringe patterns obtained under vertical and shear loads have been studied and the results obtained under these conditions are discussed with their limitations specifically when this is applied for sensing applications. Finally a case study has been conducted to analyze a foot image and conclusions drawn from this have been presented.
Analysis of Controllability of the Stewart Platform at the Type-II Singularities
Authors: Wang Yu-Xin
Published: May 2009

This paper deals with analysis of the gain of the degree-of-freedoms at a singular point for the Gough-Stewart platform. Through investigating the configuration bifurcation behaviors of the manipulator, it is found that two assembly configuration branches corresponding with the same input parameters intersect at the singular point, and it is easy for the component to jump from its original configuration branch to the other configuration branch if two configuration branches are close enough in the vicinity of the singular point. With the aid of the maximum loss-control domain, which reflects the configuration bifurcation characteristic at the singular points and the control precision of systems, the gain of degree-of-freedoms for the Stewart platform are analyzed. The research shows that the gain of degrees of freedom mainly depends on the configuration bifurcation characteristic in the vicinity of the singular points. The parallel manipulator with a higher control precision will obtain fewer degree-of-freedoms and its configuration is easy to be controlled in the vicinity of the singular point. This investigation has potential applications in selecting joints’ clearance and determining the control precision of the Stewart platform.
Assembly Concept of a Magnetic Levitation System for a Linear Micro Actuator
Authors: Cvetkovic S. , Ruffert C. , Gatzen Hans H.
Published: May 2009

Linear micro motors lend themselves to being fabricated in a hybrid fashion, i.e. fabricating stator and traveler on separate wafers. While such an approach provides substantial flexibility in fabricating the micro components, it requires to coming up with an appropriate guide system, as well as an assembly process for system integration. This process has to assure that the most critical dimension (typically the air gap between stator and traveler) is achieved. In general, such a challenge is best met by a self-alignment assembly process. The first generation of linear actuators used an assembly process where a ball guide consisting of ground V-grooves and 200 μm ruby balls was created. Both micro step motors and micro synchronous motors were equipped with such guides, which proved to be quite reliable. However, to further minimize friction, future linear micro motors will feature magnetic levitation bearings. This paper presents an assembly process for such micro motors.