bluuebunny/crossref_metadata_2025 huggingface dataset:
An Introduction to Product Family Evaluation Graphs
Authors: Ye Xiaoli , Gershenson John K. , Khadke Kiran , Lai Xiaoxia , Guo Fang
Published: June 2008

With increasingly aggressive competition for market share, manufacturing companies are facing the challenge of providing nearly customized products at bulk prices. To achieve this, product families — a group of related products derived from a single product platform — have been used to provide strategic variety to satisfy customer requirements and simultaneously achieve economies of scale. Many methods for product family design have been developed. However, we still lack the ability to evaluate a product family based on quantitative tradeoffs between product family commonality and product family variety. In this paper, we introduce the Product Family Evaluation Graph (PFEG), which can assist product family designers choosing the “best” product family design among a set of product family design options. This method is complete in its formulation, but lacking in tools for implementation. It is our purpose to show the usefulness of such a method and discuss its foundation. We show how the tool can be used to compare candidate product family designs and used in the robust design of a single product family. In addition, we highlight the strategic factors and measures that are the basis for evaluating any product family. We offer ten example strategic factors — customization, market life, technological innovation, family size, complexity, development time, service and maintenance, environmental impacts, manufacturing cost, and production volume — that determine the ideal tradeoff strategy between commonality and variety. We also highlight the need for more research into the validity of these factors, the specific relationships between these factors, and a tradeoff strategy. The measures of commonality are shown to be well established. However, we show that there is still a glaring need for the quantitative evaluation of product family variety. In summary, this paper is intended as a starting place, an opening set of questions, and as a framework for the general solution to the problem of a quantitative evaluation of product family design.
Multi-Objective Optimisation of Quarter-Car Models With Linear or Piecewise Linear Suspension Dampers
Authors: Verros G. , Georgiou G. , Natsiavas S.
Published: June 2008

A systematic methodology is applied leading to optimum selection of the suspension damping and stiffness parameters for two degree of freedom quarter-car models, subjected to road excitation. First, models involving passive damping with constant or dual rate characteristics are considered. Then, models where the damping coefficient of the suspension is selected so that the resulting system approximates the performance of an active suspension system with sky-hook damping are also examined. For all these models, appropriate methodologies are first employed for locating the motions of the vehicle resulting from passing over roads of a given geometric profile with constant horizontal speed. Three suitable performance indices are then defined, whose optimisation yields the most important suspension stiffness and damping parameters. Since these indices are conflicting, a suitable multi-objective optimisation methodology is set up and applied. As a result, a series of diagrams with typical numerical results are obtained and presented in both the corresponding objective spaces (in the form of classical Pareto fronts) and parameter spaces, for vehicle models running over roads involving an isolated or a distributed geometric irregularity.
Performance Comparisons of Timing Techniques in a Non-Real-Time Environment
Authors: Proctor Frederick M. , Hibbits Justin R.
Published: June 2008

General-purpose computers are increasingly being used for serious control applications, due to their prevalence, low cost and high performance. Real-time operating systems are available for PCs that overcome the nondeterminism inherent in desktop operating systems. Depending on the timing requirements, however, many users can get by with a non-real-time operating system. This paper discusses timing techniques applicable to non-real-time operating systems, using Linux as an example, and compares them with the performance that can be obtained with true real-time OSes.
A Comparison of Three Feedback Controllers for Container Cranes
Authors: Nayfeh Nader , Masoud Ziyad , Baumann William
Published: June 2008

We investigate three feedback schemes for controlling container cranes. The control schemes are a classical feedback controller, a time-delayed position feedback controller, and a linear quadtratic regulator controller. The controllers are developed for a linearized version of the nonlinear model. The performance, however, is evaluated using the full nonlinear model. The metrics used to evaluate the controllers are the payload sway, the settling time of the sway, and the trolley acceleration. The time-delayed position feedback controller has the best overall performance.
Design Optimization by Integration of Evolutionary Search and Cumulative Approximation
Authors: Fujita Kikuo , Ushiro Tomoki , Hirokawa Noriyasu
Published: June 2008

This paper proposes a new design optimization framework by integrating evolutionary search and cumulative function approximation. While evolutionary algorithms are robust even under multi-peaks, rugged natures, etc., their computational cost is inferior to ordinary schemes such as gradient-based methods. While response surface techniques such as quadratic approximation can save computational cost for complicated design problems, the fidelity of solution is affected by density of samples. The new framework simultaneously performs evolutionary search and constructs response surfaces. That is, in its early phase the search is performed over roughly but globally approximated surfaces with the relatively small number of samples, and in its later phase the search is performed intensively around promising regions, which are revealed in the preceded phases, over response surfaces enhanced with additional samples. This framework is expected to be able to robustly find the optimal solution with less sampling. An optimization algorithm is implemented by combining a real-coded genetic algorithm and a Voronoi diagram based cumulative approximation, and it is applied to some numerical examples for discussing its potential and promises.
Reduced Sensitivity to Perturbations in the Numerical Solution of Multibody DAEs
Authors: Bottasso Carlo L. , Bauchau Olivier A.
Published: June 2008

A simple preconditioning for the multibody dynamics equations of motion in index 3 form is presented. The perturbation analysis of the transformed system shows a decreased sensitivity to the propagation of errors in the numerical solution by BDF-type schemes. The scaling transformation is simple to implement and does not require the re-writing of the system equations as other approaches. The theoretical analysis is confirmed by a simple numerical example.
Sherpa Moving Mass Entry Descent Landing System
Authors: Balaram J.
Published: June 2008

We describe Sherpa — a Strap-on High-altitude Entry Reconnaissance & Precision Aeromaneuver system that utilizes a moving mass system within an entry capsule to land a spacecraft precisely onto the surface of Mars. Sherpa uses two sets of “strap-on” assemblies, one for high-altitude sensing using a terrain imager, and another for agile hypersonic flight using a moving-mass steering device. In this paper we focus on the moving mass system — a steering device that provides an agile trajectory control capability that is mechanically simple, completely internal to the vehicle, has high control authority, and is robust to mechanism failure. The Sherpa system takes a small fraction (5–10%) of the total system mass, and is capable of delivering payloads to within the proximity (~5 km) of a wide variety of landing sites including those at high-altitude (2.5+ km above the reference geoid).
FUNdesign: A Function-Based Method for Addressing Uncertainty During the Design of Engineering Systems — Representations and Knowledge Storage
Authors: Hutcheson Ryan S. , Donndelinger Joseph A. , McAdams Daniel A. , Stone Robert B.
Published: June 2008

This paper outlines a function-based method for addressing design parameter uncertainty during the conceptual design phase of an engineering system. The method is given the name FUNdesign and represents a set of tools for obtaining and storing sensitivity information of functions from previous designs as well as tools for applying this information to designing new systems. To store the sensitivity information, functional models created using the Functional Basis are first created for previous designs. Performance models for each function in the model are then identified and a sensitivity analysis performed on each model with respect to each design parameter. This sensitivity information and its associated performance models are then stored according to functionality in an engineering design repository. The information stored in the repository is then used to aide the allocation of design and modeling resources during the design of a system with similar functionality. The specific focus areas of this paper are the sensitivity parameters and methods required to store the sensitivity information.
A Model-Based Approach to Improve Planning Practice in Collaborative Aerospace Design
Authors: Wynn David , Clarkson P. John , Eckert Claudia
Published: June 2008

The research reported in this paper complements previous work in the modeling and analysis of product development processes to reduce process risk and lead time. Such methods have found a receptive audience in industry, as evidenced by many academic case studies and the initiation of similar process improvement initiatives by the companies themselves. Given the ongoing ‘pull’ from a number of companies, we are interested to understand why such model-based methods have not yet impacted upon wider operational planning in industry. In this paper, based on an extended research study at a large UK aerospace company, we describe the application of the Signposting process modeling approach to the problem of developing a pragmatic method to support planning practice. The research described in the paper focuses on the elicitation, representation and manipulation of process information in a form which can inform planning and scheduling; during the study, addressing these issues was key to gaining support of the approach within the company.
Adaptive Fuzzy Logic Control of a Flexible Four-Bar Mechanism With a Smart Coupler Link
Authors: Smaili Ahmad , Mrad Foaud , Maamoun Hadi
Published: June 2008

This paper presents the results of an investigation in which a PD-like and adaptive Fuzzy Logic Controllers (FLC) are designed to reduce the effects of the most dominant vibration mode on the elastodynamic response of a flexible mechanism system. The FLC schemes are implemented on a flexible four-bar mechanism whose coupler link is retrofitted with a pair of thin plate-type piezoceramic actuator and sensor bonded to the coupler link surface at the high strain location corresponding to the dominant vibration mode. Simulation results indicated that active damping with FLC is a viable strategy in reducing the amplitudes of vibrations. Moreover adaptive FLC with fixed, optimally obtained adaptation rates provides higher attenuation rate than with fuzzy adaptation mechanism. However, a simple robustness test indicated that fuzzy adaptation is more robust tan fixed adaptation.
Robustness of Boundary Control of Fractional Wave Equations With Delayed Boundary Measurement Using Fractional Order Controller and the Smith Predictor
Authors: Liang Jinsong , Zhang Weiwei , Chen YangQuan , Podlubny Igor
Published: June 2008

In this paper, we analyze the robustness of the fractional wave equation with a fractional order boundary controller subject to delayed boundary measurement. Conditions are given to guarantee stability when the delay is small. For large delays, the Smith predictor is applied to solve the instability problem and the scheme is proved to be robust against a small difference between the assumed delay and the actual delay. The analysis shows that fractional order controllers are better than integer order controllers in the robustness against delays in the boundary measurement.
Nonlinear Flexural-Torsional Vibrations of a Gundrilling Tool
Authors: Gouskov Alexander M. , Voronov Sergey A. , Butcher Eric , Sinha Subhash C.
Published: June 2008

The nonlinear dynamics of a tool commonly employed in deep hole drilling is analyzed. The tool is modeled as a continuous beam that vibrates in transverse and axial directions caused by cutting process. The mechanical model of cutting forces is a nonlinear function of cutting tool displacement including state variables with time delay. The equations of new surface formation are separated as a specific set. These equations naturally include the regeneration effect of oscillations under cutting and it is possible to analyze continuous and intermittent cutting involving either stationary or non-stationary processes. The vibratory drilling tool feed consists of a constant as well as a periodic component. Due to the constant component of feed, the distance between the supports of beam is regarded as a slowly varying function of time. The system includes three types of non-linearity, viz., discontinuity of cutting, nonlinear machining law, and the influence of transverse displacement of beam on axial deflection of cutting edges. Variation of machined chip thickness cause variation of axial trust force and it is an additional source of parametric excitation of system oscillations.
An Analysis on Vibration of Moving Silent Chain by Multi-Body Dynamics
Authors: Zhang Weiming
Published: June 2008

There have been a lot of researches on noise and vibration of chain drives. The chain usually has been modeled as an axially moving continuous string in most researches, and there have been large numbers of researches on moving strings as the models of belts or cables. Also the chain has been treated as a multi-degree-of-freedom system. However, it is hard to find the research that treats the transverse vibration of moving chain with the model of a multi-degree-of-freedom system. In this paper, an analysis for the transverse vibration of an axially moving silent chain by using multi-body dynamics is presented.
An Approach to Drawing-Like View Generation From 3D Models
Authors: Pu Jiantao , Ramani Karthik
Published: June 2008

In this paper we propose a method to generate 2D drawing-like views from 3D models automatically. The view generation process is conducted in object space and supported by two algorithms: (1) pose determination for 3D models: unifying the space between 2D drawings and 3D models; and (2) 2D drawing-like view generation from 3D models: building the correspondence between 2D drawings and 3D models. The pose determination method for 3D objects is proposed on the basis of a concept called Virtual Contact Area. Meanwhile an efficient occlusion algorithm based regular grid is described to generate orthogonal drawing-like views from 3D models along the pose orientations. To evaluate the validity of the proposed methods, respective experiments are presented.
A Strategy for Simulation-Based Multiscale, Multi-Functional Products and Associated Design Processes
Authors: Panchal Jitesh H. , Choi Hae-Jin , Shephard Jim , Allen Janet K. , McDowell David L. , Mistree Farrokh
Published: June 2008

Simulation Based Engineering Science (SBES) is an evolving interdisciplinary research area rooted in the methods for modeling multiscale, multi-physics events. The objective in SBES is to develop methodologies that are foundational to designing multiscale systems by accounting for phenomena at multiple scales of lengths and time. Some of the key challenges faced in SBES include lack of methods for bridging various time and length scales, management of models and uncertainty associated with them, management of huge amount and variety of information, and methods for efficient decision making based on the available models. Although efforts have been made to address some of these challenges for individual application domains, a domain independent framework for addressing these challenges associated with multiscale problems is not currently available in the literature. In this paper, we make a clear distinction between multiscale modeling and multiscale design. Multiscale modeling deals with efficient integration of information from multiscale models to gain a holistic understanding of the system, whereas multiscale design deals with efficient utilization of information to satisfy design objectives. Our focus in this paper is on multiscale design. In order to address the challenges associated with multiscale design, we propose a domain independent strategy that is based on understanding the generic interaction patterns between models at multiple scales. The design strategy outlined in this paper has as its foundation a systems-based approach for designing design processes (meta-design) and robust design. The concepts are illustrated with a multiscale design problem from materials domain.
Differential Cable Length Manipulation for Oscillation Control of Quay-Side Container Cranes
Authors: Masoud Ziyad N.
Published: June 2008

Traditionally, a crane is modeled as a simple pendulum with a lumped mass at the end of a hoisting cable. However, in the case of quay-side container cranes the actual hoisting mechanism consists typically of a set of four hoisting cables. Modern quay-side container cranes use independent front and rear hoisting cables. This degree of freedom can be utilized to control payload sway oscillations. In this work, a delayed feedback algorithm is used to produce a controlled differential change in the length of the front and rear hoisting cables of a typical quay-side container crane.
Nonlinear Thermal Vibration Analysis of a Thin Laminated Microstructure
Authors: He Xiaoling
Published: June 2008

Nonlinear deformation can occur in thin laminated structures due to thermal fields present in the laminates. Thermally induced laminate response in buckling and vibration has been previously studied in nonlinear dynamics by approximations that compromise the total energy of the system. In this paper, this problem is studied based on the nonlinear thermal mechanical analysis of a thin laminated structure using a Galerkin type approach, with total energy conservation. Equation of motion for laminates in orthotropic and isotropic structures in thermal buckling response in a simply supported boundary condition is obtained in a decoupled modal form of the Duffing equation, with consideration of both non-uniform in-plane and transverse temperature variations, in steady state and transient state. Analysis is made for the thermal buckling behavior of an isotropic laminate with respect to the steady-state and transient thermal fields. In particular, chaos and instability due to the transient thermal field are investigated.
Shear Lag Based Iwan Model for Interface Friction Contacts
Authors: Deshmukh D. V. , Berger E. J.
Published: June 2008

Reduced order models for characterizing friction interfaces have been investigated for the last 75 years. Recent work has been focused on microslip formulation of the interface behavior, where continuous contact is approximated with a multi-point contact model. A novel multi-point contact model is presented in this work, which is entirely derived from a shear lag approach to resolve the kinematic state of the friction interface under the presence of tangential loading. Both static and dynamic loading conditions are analyzed and comparisons are drawn between the continuous and discrete models. The series Iwan model presented in this work differentiates between the elastic and friction components of the interface displacement, both parameters being calibrated using material properties and model geometry. Convergence behavior of such models with increasing model order is demonstrated. The response characteristics of the series Iwan model under dynamic loading conditions is also investigated. The series Iwan model is in good agreement with the shear lag approach for results such as propagation of the slip zone with increasing pullout force. The transient response of the the structural mass and the kinematic states of the damping elements are convergent with increasing model order.
Reasoning in Engineering Design
Authors: Summers Joshua D.
Published: June 2008

Peirce, the American philosopher of the late 19th and early 20th centuries, is credited with first observing the triple of reasoning (deductive, inductive, and abductive). These three types of reasoning are discussed as they relate to the engineering design process. The reasoning classes are based upon distinctions between what is given and what is derived with respect to the grounds, the warrants, and the conclusions. Simple definitions are synthesized that agree well with the literature, while distinctions are made where overlapping and often conflicting definitions are found. This distinction leads to the need for separating abductive reasoning and retroductive reasoning. A generalized description of design agrees well with the definition for retroductive reasoning, as is demonstrated in this paper. A brief survey of “traditional” design reasoning methods (rule based reasoning, analogy based reasoning, simulation based reasoning, and constraint based reasoning) is developed to show that these design methods are equivalent or decomposable into the fundamental reasoning classes. This paper provides a discussion in a common framework for comparing design reasoning strategies found in automation systems based upon the fundamental classes.
An Inductive Design Exploration Method for the Integrated Design of Multi-Scale Materials and Products
Authors: Choi Hae-Jin , Allen Janet K. , Rosen David , McDowell David L. , Mistree Farrokh
Published: June 2008

In this paper, we propose an Inductive Design Exploration Method (IDEM) which can be used to design materials and products concurrently and systematically. IDEM facilitates hierarchical materials and product design synthesis, which includes multi-scale material structure and product analysis chains, and uncertainty in models and its propagation through the chains. In this method, we sequentially identify a ranged set of feasible specifications, instead of an optimal point solution in each segment of a hierarchical design process. The feasible spaces are searched from top-level design requirements to product and materials specifications taking into account propagated uncertainty. Strategies for parallelizing computations and achieving a robust solution for uncertainty in models are also addressed. The method is demonstrated with a simple example of designing a clay-filled polyethylene cantilever beam.
Customer Need Driven Function-Behavior Platform Formation
Authors: Kumar Rupesh , Allada Venkat
Published: June 2008

Product platform formation has long been considered as an effective method to meet challenges set forth by mass customization. To cater to the changes in customer need driven functional requirements and technological advancements, product platforms have to be robust for a given planning horizon from the manufacturer’s point of view. To date, most of the product platform research is directed towards developing approaches that maximize the usage of common physical structures (such as sub-assemblies and components), amongst product variants. We argue that there is a need to start thinking about platforms at a higher level of abstraction than just at the physical structure level because after all, the physical structures are the end result of the mapping process that starts with the customer needs, cascades to the functional requirements and the behaviors (aka working principle/behavior) that will be used to realize the functions. The Function-Behavior-Structure approach discussed by Gero and Kannengiesser (2003) deals with such an approach. In this paper, we present a methodology called the Function-Behavior Ant Colony Optimization (FB-ACO), to determine a higher abstract level platform at the FB level. The proposed approach can be used to provide critical decisions related to the planning of the advent and egress of a product or the use of a behavior, configuration of the function-behavior platform and the number of such platforms to be considered at a particular time. The FB platform can then be used to develop the detailed design for the family of products under consideration. We demonstrate our proposed approach using the example of a computer mouse product family.
Product Family Architecture Reasoning
Authors: Siddique Zahed , Adupala Rajeshwar
Published: June 2008

Designing family of products, instead of single products, using a common platform approach has gained momentum in various industries. One of the main challenges faced by companies includes specifying a product family architecture to support the varieties. Designers need to consider different viewpoints related to product, assembly, manufacturing, etc. during the development of the product family architecture. The purpose of this paper is to present a configuration reasoning method to develop a product family architecture that not only satisfy, but also has improved characteristics for different viewpoints. This paper attempts to accomplish these objectives by developing representations for components, modules, product family architecture, and assembly process. The paper also presents mathematical formulations to generate feasible product family architectures, indices for architecture evaluation, rules to ensure feasibility and improve from multiple viewpoints. The application of this configuration reasoning framework is illustrated using identifying product family architecture for a set of coffeemakers.
Fuzzy Logic Based Vehicle Stability Enhancement Through Combined Differential Braking and Active Front Steering
Authors: Ahmadi J. , Ghaffari A. , Kazemi R.
Published: June 2008

This paper examines the usefulness of a combined differential braking and active front steering system on the stability enhancement of a vehicle. The two manipulated inputs for steering intervention are the added front steer angle and the brake torque, where the later is applied at only one wheel at a time. In this study active front steering controller is designed independent of differential braking controller. Since the yaw and lateral motions are highly nonlinear, two fuzzy logic controllers are constructed to compensate the effects of road condition and parameter variation. Computer simulations using nonlinear seven degree of freedom vehicle model show the strong capability of the combined approach and its relative merit compared to the case that one subsystem is actuated.
Design of Car Active Suspension Systems to Obtain Desired Performance on Reducing Effect of Road Excitation on Human Health
Authors: Abdollahpour Rooholah , Sharifi Sedeh Reza , Ahmadian Mohamad Taghi , Sadati Nasser
Published: June 2008

Advent of passenger cars has caused people to use them for more efficiency in their performance and wasting less time. Problems, however, still exist in them. For instance, since people travel with cars, their human bodies undergo in fatigue, restlessness, and sometimes health problems. Human body reaction under external vibration depends on the amplitude, frequency, and acceleration of the applied external excitation. These limitations which are usually announced by the bureau of standards imply the necessity of control of amplitude, vibration, frequency, and acceleration received by human body due to cars passing humps and bumps. In this paper, a quarter car model with active suspension system is considered and three control approaches namely optimal control, fuzzy control, and adaptive fuzzy optimal control (AFOC) are applied. Moreover, the performance of different controllers is compared. Application of three different methods indicate that adaptive fuzzy optimal control results in a higher performance in time, acceleration, amplitude, and consequently lower hazards to human body.
“Collaborating To Success”: An Experimental Study of Group Idea Generation Techniques
Authors: Linsey J. S. , Green M. G. , Murphy J. T. , Wood K. L. , Markman A. B.
Published: June 2008

Numerous concept generation methods have been developed that can assist an engineer in the initial phases of design. Unfortunately, limited empirical data is available to guide users in selecting preferred techniques. This study systematically investigates underlying factors of four well-used and documented techniques: Brainsketching, Gallery, 6-3-5, and C-Sketch. These techniques are resolved into their key parameters and a factorial experiment is performed to understand how the key parameters affect the outcomes of the techniques. The factors chosen for this study include: how ideas are displayed to participants (all are viewed at once or exchanged between participants, “rotational viewing”) and the mode used to communicate ideas (written words only, sketches only, or a combination of written words and sketches). This study also provides a method for measuring the quantity of ideas generated when the ideas are represented in the form of both sketches and words. A number of interesting findings are produced from the study. First, the study shows that individuals gain a significant number of ideas from their teammates. Ideas when shared, can foster new idea tracks, more complete layouts, and diverse synthesis. Second, the systematic exchange of a set of ideas between participants produces a greater quantity of ideas than having all ideas displayed in a gallery form. This result shows that techniques like 6-3-5 or C-Sketch, where each person views only a subset of all the team’s ideas at any given time, are more likely to produce a larger quantity of ideas than techniques where individuals can continuously view all the ideas the team has generated. Finally, as teams developed ideas, the quality improved. This result is a consequence of the teamsharing environment and, in conjunction with quantity of concepts, validates the effectiveness of group idea generation.
Capturing Design Knowledge of Robust Designs Using Configurable Components
Authors: Claesson Anders , Rosvall Bjo¨rn , Johannesson Hans
Published: June 2008

Development of complex, platform-based, and variant-rich products within the automotive industry is in many respects a challenging task. The competitive pressure within the industry requires more and more collaborative development and utilization of systems and components not only within, but also across, product platforms. In such an environment the ability to effectively and efficiently deal with how variability is achieved is an important issue. Many approaches to deal with configuration issues have been subject to extensive research and exploration. In the research presented here the basic idea is to merge influences from established design tools and methods with concepts from research on configuration tasks as well as from product description approaches used within the industry. The presented work has an exploratory nature that aims at increased understanding of the mechanisms, methodology and value of the application of the configurable component concept as a development support tool during platform-based vehicle development. The work presented here has been performed in parallel with a feasibility study for a vehicle cock-pit family. The study aims at investigating prerequisites for enabling a cock-pit solution to be shared as a common solution in several vehicle platforms as well as within each of the platforms. The paper contributes to the understanding of how configurable components can improve the definition and maintenance of design variants and facilitate reuse of these design solutions through the captured trail of design rationale that is achieved through the systematic use of the component definitions.
Half-Critical Response of Cylindrical Rotor to Distributed Elasticity Excitation
Authors: Keskinen Erno , Cotsaftis Michel , Martikainen Matti
Published: June 2008

Due to the limitations of manufacturing accuracy, long cylindrical rotors used in heavy power transmission lines and paper machinery are dynamically excited by internal elastic forces. The origin of these forces is the out-of-roundness profile of the inner and outer radii of the rotor, which contributes to the bending stiffness distribution along the rotor span. Distributed anisotropy of the rotor under gravitational load is reason of the existence of half-critical speeds, on which the rotor experiences non-classical resonance state. This problem has been formulated in terms of nominal and deviated motion according to the splitting of the bending stiffness tensor in a similar way. This leads to a static rotor equation, whose amplification effect on to the dynamic part of the motion has been analyzed in details. This includes formal solution of the resulting dynamic Hill equation in terms of the modal coordinates of the corresponding free whirling Rayleigh beam.
Modelling of Magnetic Pull in Large Size Generator
Authors: Pennacchi Paolo , Frosini Lucia
Published: June 2008

This paper presents a method to analyze the dynamical behaviour of large size generators due to the magnetic pull. In rotating electrical machines, the electromagnetic radial forces acting upon rotor and stator surfaces are very large, but they are balanced when the rotor is concentric with the stator. Similarly, the tangential forces produce only an axially rotating moment. If the rotor becomes eccentric, then an imbalance of these forces occurs, so that a net radial electromagnetic force, known as Unbalanced Magnetic Pull (UMP), is developed. The models traditionally proposed in the literature to study the UMP can be considered as reliable in case of small size electrical machines supported by rolling bearings. On the contrary, in case of large size machines, such as turbo-generators supported by oil-film bearings, the approximation of circular orbits of the rotor is not acceptable. Nevertheless, the authors who have dealt with UMP in big size generators have disregarded that these rotor filtered orbits are elliptical and generally the orbit centres are not concentric with the stator. In order to provide a more realistic model and an original contribution, in this work the actual distribution of the air-gap length during the rotation will be determined in analytical terms, by taking into account the effects produced by the actual rotor orbit. The actual UMP is calculated by using the air-gap permeance approach and the simulation of the dynamical behaviour of a 320 MW generator is presented, showing the harmonic content of the UMP and the presence of non-linearities.
Design Evolution Using the Artisan-Patron Model: The Case of Automobile Evolution
Authors: Wissmann Luke A. , Yassine Ali A.
Published: June 2008

This paper uses the descriptive Artisan-Patron (AP) model to create a transparent framework to analyze how environmental variables such as fuel price, price of steel, and CAFE´ legislation affected the evolution of the automobile (namely horsepower and weight). The analysis and results demonstrate the utility of the AP model as a frame for complex multi-epoch adaptive design problems.
Interpretive Real-Time Linux Interface and Its Applications
Authors: Wang Zhaoqing , Nestinger Stephen S. , Cheng Harry H. , Proctor Frederick M.
Published: June 2008

For time deterministic control, manufacturers and system designers of computer controlled machinery use real-time based systems to satisfy stringent requirements. Standard real-time systems contain built in kernel modules and often some type of user interface written in C. With a large multidimensional system spanning many smaller objective systems, it is hard for specialists to access real-time controlled objects on the spot. Making modifications to the user interface may require a slew of compilation and linking. This article presents an Interpretive Real-Time Linux Interface, which seamlessly integrates C/C++ applications using a C/C++ interpreter. Running the application interpretively makes the interface insensitive to user customization and product upgrading. An example of an insensitive interface is given in which a CGI web based user interface written in C has been implemented allowing users to control the frequency output of a speaker through a real-time Linux system from the web.
Modeling the Transient and Steady-State Flow Over a Stationary Cylinder
Authors: Nayfeh Ali H. , Marzouk Osama A. , Arafat Haider N. , Akhtar Imran
Published: June 2008

A reduced-order model for the two-dimensional flow over a stationary circular cylinder is examined. The lift is modeled with the van der Pol equation with three parameters; it models self-excited self-limiting systems. The drag is modeled as the sum of a mean term and a time-varying term proportional to the product of the lift and its time derivative. The transient and steady-state flows are calculated using a CFD code based on the unsteady Reynolds-averaged Navier-Stokes equations. The steady-state lift and drag CFD results are used to identify the three parameters in the lift model using a combination of higher-order spectral techniques and perturbation methods. The model is validated using steady-state numerical simulations for three cases describing low, moderate, and high Reynolds number flows. Then, the model is shown to reproduce the transient lift and drag calculated with the CFD code.
Using an Updating Urn-Scheme for Prioritizing Quality Requirements in the Early Stage of Collaboration Design
Authors: Hsieh Ping-Hung , Ge Ping , Meier Stefan
Published: June 2008

The effective prioritization of quality requirements (QR) in collaborative product development is studied. The requirements for a quality product are often obtained by questioning and interviewing targeted customers. However, the targeted customers often are not able to clearly articulate and be specific on what constitute a quality product. Even for those clearly specified requirements, they may not be able to determine the relative importance. Moreover, concerns of the developer’s organization and the society, such as the company goals and priorities as well as environmental regulations, may not get necessary attention by customers. Hence, efforts to prioritize QR’s across all stakeholders in developing a quality product are necessary. Prior research has focused on developing a process of prioritizing QR’s. Although our proposed urn-scheme method in prioritizing QR’s may be considered yet another voting mechanism, it differs in two major directions. Firstly, the proposed method explicitly incorporates social dynamic factors such as interpersonal trust and trustworthiness into the voting process. These latent factors are quantified and measured allowing us to visualize their effects on individual stakeholder’s prioritization list. Secondly, with the most trusted stakeholders’ prioritization lists amplified and the least trusted stakeholders’ opinions down weighed, the final combined prioritization list, weighing over all individual lists, is the result of the direct voting and social dynamics, all quantified, and thus, relative importance of quality requirements can be derived. The most important requirements are typically viewed by most stakeholders as important and particularly so by the most trusted stakeholders. A discussion on possible voting results is given. Extension of the proposed method to cover issues such as power influence and conflicts as well as degree of consensus is also provided.
Multibody Dynamics Integrated With Muscle Models and Space-Time Constraints for Optimization of Lifting Movements
Authors: Huang Cunjun , Sheth Pradip N. , Granata Kevin P.
Published: June 2008

A multibody dynamics model integrated with space-time constraints based optimization is presented in this paper for generating optimal trajectories of human lifting movements. “Space-time constraints” is a two-point boundary value dynamic optimization technique developed for animation of computer graphics characters and has a significant potential for biomechanics and other mechanical movement based dynamic optimization problems. Optimization results demonstrate the ability to consider different preferences for minimizing the loading of specific joints such as an ankle, or a knee, or a shoulder during the lifting motion and the resulting lifting trajectories are shown to be different. Lumped muscle models to generate the joint torques are incorporated at five joints to model the actuation effects of the muscular system during the dynamic movement. The dynamic optimization is then based on the muscle activation parameters instead of the traditionally used joint torques. The muscle activation model optimization is shown to correlate better with the actual motion tests conducted by the VICON video capture and test data analysis system.
Transforming Design Education by Design
Authors: Kolberg Eli , Reich Yoram , Levin Ilya
Published: June 2008

Design is a contextualized activity influenced by many factors. In order to understand or teach it, a holistic approach that involves students in actual design activities is required. Often, such educational setup is called problem or project-based learning (PBL). There are many views about implementing PBL. Our approach to design education is different than others in the way we treat design courses as products with constraints and objectives. Following our experience in previous design courses, we set to create the best design course possible in our particular context by carefully designing it using design tools developed in design research. We elaborated the course objectives; observed and analyzed failures of design projects in previous courses; and proposed new design methods that could remedy those failures. The collection of potential design methods was evaluated and six methods were selected as the backbone of the design curriculum. The curriculum we designed was implemented in a mechatronic course for high school students. Careful study with several groups including control demonstrated that our design improves the existing course. We describe the course design; provide some details about the design methods that comprise the design curriculum and some examples of using these methods in the course to ground the discussion. A reader unfamiliar with mechatronic could skip these descriptions. The contribution of this paper is twofold. First, we show that there is no single general design methodology. For different products and contexts, different design methodologies should be designed. If we use design methods developed in design research, the methodologies could prove successful. Second, and more specifically, we present a new, possible, and successful design methodology for mechatronics. We are not aware of such comprehensive approach in the literature.
Simulation-Based Tolerance and Assemblability Analyses of Assemblies With Multiple Pin/Hole Floating Mating Conditions
Authors: Shen Zhengshu , Shah Jami J. , Davidson Joseph K.
Published: June 2008

Development of tolerance analysis methods that are consistent with the ASME and ISO GD&T (geometric dimensioning and tolerancing) standards is a challenging task. Such methods are the basis for creating computer-aided tools for 3D tolerance analysis and assemblability analysis. These tools, along with the others, make it possible to realize virtual manufacturing in order to shorten lead-time and reduce cost in the product development process. Current simulation tools for 3D tolerance analysis and assemblability analysis are far from satisfactory because the underlying variation algorithms are not fully consistent with the GD&T standards. Better algorithms are still to be developed. Towards that goal, this paper proposes an improved simulation-based approach to tolerance and assemblability analyses for assemblies with pin/hole floating mating conditions in mechanical products. A floating pin/hole mating condition is the one where the mating pin should be able to “float” within the mating hole, and thus press-fit is not necessary for the parts to assemble properly. When multiple pin/hole mating pairs are involved in a product, the feasibility of assembly needs to be analyzed. This paper will introduce a more complete method of analyzing assemblability for such assemblies. In most cases, a 3D (3-dimensional) problem can be simplified to 1D (1-dimensional) or 2D (2-dimensional) problem, with the loss of some accuracy. To make a comparison and find out how accurately 1D and 2D analyses can approximate 3D analysis, this paper will provide the variation algorithms for 1D, 2D and 3D simulations. The algorithms developed account not only for bonus/shift tolerances but also for feasibility of assembling. These algorithms are extendable to consider other different GD&T specifications. The assemblability criteria proposed is generally applicable to any assemblies with pin/hole floating mating conditions. Case studies are provided to demonstrate the algorithms developed. The comparison study shows quantitatively the difference in the results from 1D, 2D and 3D simulation based analyses.
Implicit Solid Modeling for Mesh Free Analysis
Authors: Kumar Ashok V. , Lee Jongho , Burla Ravi
Published: June 2008

In traditional solid modeling the boundaries of the solid are represented using parametric equations. Even though the application of implicit equations has also been explored, they have not been widely used. Interest has been rekindled recently due to application of implicit equations to mesh free engineering analysis. In this paper, an implicit representation scheme for solids is presented where the boundaries of primitive solids are defined using implicit equation of surfaces. To ensure that the equations are axis independent, the characteristic functions for the implicit equations are defined by interpolating within hexahedral elements. Primitive solids are defined by sweeping closed 2D profiles. The boundaries of these profiles are defined using implicit equations of curves. Implicit equations can be used for constructing “step function” of the primitives and their Boolean combinations. The step functions of a solid has a unit value inside the solid and zero outside and can be used for computing volume integrals needed for mesh free analysis.
An Information Theoretical Perspective on Performance, Refinement and Cost
Authors: Krus Petter
Published: June 2008

Design in general is about increasing the information of the product/system. Therefore it is natural to investigate the design process from an information theoretical point of view. There are basically two (although related) strains of information theory. The first is the information theory of communication. Another strain is the algorithmic theory of information. In this paper the design process is described as a information transformation process, where an initial set of requirements are transformed to a system specification. Performance and cost are both a functions of complexity and refinement, that can be expressed in information theoretical terms. The information theoretical model is demonstrated on examples. The model has implications for the balance between number of design parameters, and the degree of convergence in design optimization. Furthermore, the relationship between concept refinement and design space expansion can be viewed in information theoretical terms.