bluuebunny/crossref_metadata_2025 huggingface dataset:
Mesh Processing for Computerized Anthropometry
Authors: Deo Dhanannjay , Sen Dibakar
Published: June 2008

Understanding of the shape and size of different features of human body from the scanned data is necessary for automated design and evaluation of product ergonomics. In this paper, a computational framework is presented for automatic detection and recognition of several facial feature-regions from scanned head and shoulder polyhedral models. A noise tolerant methodology is proposed using discrete curvature computations and morphological tools for isolation of the primary feature regions of face namely eye, nose and mouth. Spatial disposition of the critical points of these isolated feature-regions is analyzed for recognition of these critical points as the standard landarks associated with the primary facial features. A number of clinically identified landmarks lie on the facial midline. An efficient algorithm for detection and processing of the midline using a point samplng technique is also presented. The results are matching well with human perception and measurements done manually on the subjects.
Teaching Computer Aided Product Design With Aesthetic Considerations
Authors: Zhang Andy S. J.
Published: June 2008

This paper presents a study on how to utilize the computer based 3-dimensional parametric solid modeling software to integrate aesthetics into the lectures of product design related courses of a mechanical engineering curriculum to improve teaching and learning. The study indicates that when aesthetics were properly introduced into the classrooms of product design related courses; it created an environment that stimulated students’ imagination and creativity therefore enhancing their learning experience. When teaching product design courses, instruction tends to be focused on the underlying engineering requirements related to the product. Little is taught in the classroom about the aesthetic aspects of the product. As a result, the products created from the student’s design projects are mostly functional but not necessarily visually appealing. To address this issue, in teaching design-related courses, students were told to play the roles of both designers and consumers. After learning the basics of aesthetics, students were encouraged to inject their own aesthetic evaluations, considering themselves as customers, into the design process. This allowed the students to put more attention on the human elements (aesthetics) of their design. As a result, the students’ design projects have dramatically improved in content and in forms. The advances in computer based 3D parametric modeling software has made the integration of aesthetics into the engineering design curriculum possible. Both AutoDesk’s Inventor and PTC’s Pro Engineer Wildfire software packages were used in the classrooms. With the software’s enhanced spline and surface features, students were able to try different forms or shapes to generate the desired aesthetic effects that they weren’t able to create in the past.
Steady-State Dynamic Response of Preisach Hysteretic Systems
Authors: Spanos P. D. , Kontsos A. , Cacciola P.
Published: June 2008

The goal of this paper is to study the steady-state dynamic response of an oscillator with a hysteretic component to harmonic excitations. This is accomplished by using the Preisach formalism in the description of the contribution of the hysteretic part. Two cases are considered. In the first the hysteretic component is modeled using a series of Jenkin’s elements, while in the second the same component is modeled by a zero-memory plus a purely hysteretic term. The steady-state amplitude of the response is determined analytically by using the equivalent linearization technique which involves input-output relationships for the equivalent linear system the stiffness and damping coefficients of which are response-amplitude dependent. The derived results are compared with pertinent numerical data obtained by integrating the nonlinear equation of motion of the oscillator. The analytical and numerical results are found in excellent agreement, and supplement the analytical findings of certain previous studies.
An Approach to Product Family Positioning Based on Shared Surplus
Authors: Zhang Yiyang , Jiao Jianxin
Published: June 2008

To compete in the marketplace, manufacturers have been seeking for expansion of their product lines by providing product families. Product family positioning aims at planning the appropriate products to be provided to the target market segments. Due to the involved complexity such as diverse customer preferences, engineering costs, competition among similar products, etc, positioning the product family is very difficult. This paper proposes a shared surplus model for product family positioning. A comprehensive methodology for product family positioning is developed. An application of the proposed methodology for the notebook computer family positioning is reported.
A Knowledge-Based System Engineering Process for Obtaining Engineering Design Solutions
Authors: Prasad Brian , Rogers Jeff
Published: June 2008

Designing and developing highly engineered products requires direct (and more dynamic) associations between customers’ specifications and product characteristics (or its behaviors). In order to meet the specified customer performance, cost, and integrity goals, a multitude of specialized analyses, heuristics, shortcuts, look-up tables, equations, algorithms, finite elements, and material substitution at multiple levels (system, subsystems, components and parts) are ought to be performed. The product geometries of such engineered product are often complex and many parts are designed interactively from scratch using a 3D commercial computer-aided design (CAD) — lately often referred as Product Life-cycle Management (PLM) system. Today, this very “PLM-based” engineered product-design process is often “static”, very “feature or geometry-dependent,” “knowledge-intensive,” and therefore, engineers often takes considerable time (months) to complete this manual process. Today, more and more companies want to quickly reengineer a product from a multitude of family solutions (corresponding to various design trade-off studies). They are interested in some dynamic form of a decision-based system that could automatically filter through a multitude of historical product solutions and quickly reconfigure one that meets the customer requirements with the least cost, weight, and time investment. Such decision-based product automation is not an easy task by any means. Product definitions without knowing specific geometry are hard to conceive, capture generically, and reuse widely (via any generative tool). A typical product development process —by its nature—is highly dynamic, nonlinear, discrete, feature-dependent, and part-dependent. The solution is not easy, since problem formulation is time-bound, has numerous discrete inputs, topologies, and several mathematical discontinuities. This paper discusses the system architecture of the Knowledge-driven Automation (KDA) program — established at Parker in 2002. It addresses many of the above product development issues and problems. In particular, authors describe a Knowledge-based System Engineering Process for Obtaining Engineering Design Solutions in a Commercial PLM Setting. The architecture and solutions use a number of innovative knowledge-based engineering (KBE) concepts and procedures. Through strategic use of generative modeling, spreadsheet tables, part and assembly templates, system engineering concepts, and our proprietary “smart part concepts,” authors were able to engineer-to-configure a family of hydraulic actuators automatically from their customer specifications using a set of PLM (CATIA V5 and its underlying knowledgeware) tools.
Recursive Coordinate Reduction: An Addendum
Authors: Sadowski Michael J. , Anderson Kurt S.
Published: June 2008

This paper presents an addendum to the Recursive Coordinate Reduction (RCR) algorithm for the efficient numerical analysis and simulation of modest to heavily constrained multi-rigid-body dynamic systems. The RCR algorithm can accommodate the spatial motion of broad categories of multi-rigid-body systems containing arbitrarily many closed loops in O(n + m) operations overall for systems containing n generalized coordinates, and m independent algebraic constraints. The presented approach does not suffer from the performance (speed) penalty encountered by most other of the so-called “(n)” state-space formulations, and does not require additional constraint violation stabilization procedures (e.g. Baumgartes method, coordinate partitioning, etc.). Due to these characteristics, the presented algorithm should offer superior computing performance relative to other methods in many situations involving both large n and m. This paper will specifically address an unpublished recursive step in the handling of “floating” loop base bodies, as well as present an extension to “spur” topologies.
Product Lifecycle Management Enhancement With an Ontological Approach
Authors: Silva Joa˜o P. M. A. , Jardim-Goncalves Ricardo , Steiger-Garc¸a˜o Adolfo , Monteiro Anto´nio A. C.
Published: June 2008

Recently, computational design aiding tools resources are undertaken in modern companies, enhancing high quality product definition development. However, accurate digital product descriptions are attained through multiple software applications, each one seeking to solve focused needs. Regardless significant advances, there still remains a substantial computational deficiency in how these systems interact with each other between the several PLC stages. Plural issues with different origin and nature contribute to such state, increasing the research community interest to contribute with solution that minimizes the problem. In particular, one main issue refers to product and process knowledge exchange along PLC stages. According to this scenario, and with market pressure to increase profits and reduce redundancies, an efficient coordination and management of all the activities taking place along the Production Process must be performed. Hence, promising technologies of Product Lifecycle Management are considered strategic to manage capture of product knowledge along its life, from initial conception to retirement. This paper proposes the use of an ontology to be used in a knowledge-based system, giving support to a comprehensive product model to improve integration and data exchange capabilities trough entire PLC. The capture, handle and re-use of knowledge from multiple disciplines during PLC (e.g. design, manufacture or maintenance), extending capabilities of existent product and process models is the promising main benefit of ontologies development.
Design of Intelligent Systems: Measure of Information Content
Authors: Naidu Prakash C. R. J. , Goldenberg Andrew A.
Published: June 2008

Increasing intelligence in new products has necessitated a closer look at the application of design theory and methodology in the specific context of intelligent systems. In this paper, after reviewing the several prevalent notions of intelligent systems, some of the parameters and the measure of intelligence are discussed. The earlier work on evaluation of information content of automation systems is extended in the context of intelligent systems. The paper discusses a generic definition of intelligence more suitable for measurement in the realm of axiomatic design theory. It investigates the different issues pertaining to computation of information and its interpretation as a measure of intelligence considering an example of the basic maneuvers of an autonomous robot. The paper discusses the observations and elucidates the usefulness of information as a metric for measurement of intelligence.
AP236-XML: A Framework for Integration and Harmonization of STEP Application Protocols
Authors: Jardim-Goncalves Ricardo , Agostinho Carlos , Malo Pedro , Steiger-Garcao Adolfo
Published: June 2008

Today, organizations have to deal with the integration of applications across company borders, and must support collaboration of business processes between organizations in networked environments that are seamless, flexible and interoperable. This characteristic of horizontality, where one application embraces more than one domain of activity, is frequently found and raises the need for integration and cooperation between multiple standard application protocols and business objects. However, a standard for data representation cannot cove the whole range of activities one application needs to handle. This paper contributes by proposing a framework that supports interoperability in distributed heterogeneous networked environments, assisting in the integration of reference models described following dissimilar methodologies. This framework assists in the automatic mapping between ISO10303 STEP, UML and XML models. The proposed work results from research developed and validated in the scope of the IMS SMART-fm project (www.smart-fm.funstep.org, www.ims.org), involving partners from USA, Europe, Canada and Australia, using emerging approaches for modeling and technology.
Structural Dynamic and Aeroelastic Finite Element Simulation of an F-18 Tail Rudder: Impact of Adding a Control Surface
Authors: Anderson Kevin R. , White Kevin , McEntire Wayne
Published: June 2008

This paper presents the findings of a Finite Element Analysis (FEA) based aeroelastic analysis performed on the F-18 tail rudder using MacNeal-Schwendler (MSC) suite of commercial FEA codes. The purpose of the study was to examine the stabilizing effects of adding a control surface to the tail wing, in this case the control surface is the tail rudder. MSC NASTRAN modal analysis and aeroelastic simulations were employed to carry out the investigation. Results are presented herein for the fundamental modes subject to a structural dynamics analysis and a series of supersonic 4G rolling maneuvers. Without a control surface, modal analysis yielded the following; 1st bending mode = 17.098 Hz, 1st torsional mode = 53.879 Hz, 2nd bending mode = 80.531 Hz, and 2nd torsional mode = 117.15 Hz. By adding the of rudder, the following is found; 1st bending mode = 17.797 Hz, 1st torsional mode = 48.266 Hz, 2nd torsional mode = 61.267 Hz, and 2nd bending mode = 81.142 Hz. Hence, adding the control surface, changes the precedence of the 2nd torsional and 2nd bending modes. Aeroelasticity predictions show that for a 100% increase in Mach number, the maximum pressure on the control surface increases by 93%.
Relation Oriented Modeling for Heterogeneous Object Design
Authors: Kou X. Y. , Tan S. T. , Sze W. S.
Published: June 2008

Relation oriented modeling approaches are proposed to design heterogeneous objects. The heterogeneous object modeling process is viewed as representing and manipulating complex geometrical, topological and material variation relations with proper data structures. Linear list structure, hierarchical tree structures and more general graph structures are used to represent complex heterogeneous objects. The powerful non-manifold cellular representation and the hierarchical heterogeneous feature tree representation are combined to model complex objects with simultaneous geometry intricacies and compound material variations. We demonstrate that relations play critical roles in heterogeneous object design and under the relation oriented framework, heterogeneous objects can be modeled with generic, uniform representations. The proposed relation oriented modeling approaches are tested with a prototype heterogeneous CAD modeler and presented with different types of heterogeneous object examples.
On the Viability of Developing CAD Data Exchange Standard for Form Features
Authors: Joshi Nilesh S. , Shah Jami J.
Published: June 2008

Form feature data exchange is divided into three types: CAD-to-CAD, CAD-to-Downstream applications and inter-downstream applications. Essential characteristics for CAD-to-CAD and CAD-to-Downstream types of feature data transfer are established flowed by a set of criteria for evaluation of a form feature exchange schema. Contemporary neutral feature data exchange schemas like AP 224, AP 203 and NRep are evaluated. It is concluded that none of them is fully equipped to do the job. AP 203 belongs to the CAD-to-CAD feature data exchange class. It exchanges only the final part geometry and the feature model is lost. AP 224 and NRep belong to the CAD-to-Downstream class. AP 224 attempts to enlist all features that can be manufactured using milling and turning processes. It limits the user to finite set of features. On the other hand, NRep permits the user to define his own features and does not provide a standard set. For a complete feature data transfer between two CAD applications, one needs to model the design intent of each design feature and transfer it with construction history of creation of the part model while for an efficient feature data transfer between CAD and downstream applications, the schema needs to standardize a set of most common features but also provide means for the user to define customized features with desired parameterization and attributes.
Information and Knowledge Modeling for Computer Supported Micro Electro-Mechanical Systems Design and Development
Authors: Zha Xuan F. , Sriram Ram D. , Gupta Satyandra K.
Published: June 2008

In this paper, we present a preliminary research effort towards an effective computer support environment for the design and development of micro-electro-mechanical systems (MEMS). We first identify the characteristics of MEMS product design and development processes and examine the state-of-the-art of MEMS CAD and simulation systems. We then propose a function-(environment-effect)-behavior-(principle-state)-form (FEEBPSF) framework based on the NIST core product model and its extensions for modeling MEMS products, and apply the OESM (open embedded system model) developed to model information and knowledge for embedded MEMS design and development. Moreover, in order to tackle the knowledge-intensive tasks of design and development for MEMS products, we develop a general and flexible knowledge repository, called KR-MEMS, based on the FEEBPSF framework and the UML/XML model, and integrate KR-MEMS into a web-based MEMS design support system. Throughout the paper, a micro fluidic dispensing device (a biomedical device for drug-delivery) is used as an example to illustrate the concepts, models, and knowledge bases necessary to support the MEMS product design and development.
Stability of Transported Flexible Beam With Elastic Support
Authors: Aida Ken-Ichiro , Kobayashi Nobuyuki , Zhang Yajun , Sugiyama Hiroyuki
Published: June 2008

The stability of translating flexible beam that passes through the elastic support is investigated. We modeled the flexible beam using the finite segment method to account for the geometric nonlinearities due to the large rotation, as it is the time variant system. Numerical simulation results show the instability of the beam, that is stable in the low axial moving velocity, is observed as the axial moving velocity increases. It is clarified from the consideration with the simplified rigid beam model that the mass and damping coefficient ratio of the elastic support yields negative damping effect of the system and the damping coefficient and stiffness ratio of the elastic support yields negative stiffness effect of the system as the axial moving velocity increases. These results show that the property of the elastic support gives the significant effect on the instability of the translating beam.
On Theory of Systems of Fractional Linear Differential Equations
Authors: Bonilla Blanca , Rivero Margarita , Trujillo Juan J.
Published: June 2008

This paper is a continuation of a previous one dedicated to establishing a general theory of linear fractional differential equations. This paper deals with the study of linear systems of fractional differential equations such as the following: Y¯(α=A(x)Y¯+B¯(x)(1) where DαY ≡ Y(α is the Riemann-Liouville or Caputo fractional derivative of order α(0 < α ≤ 1), and: A(x)=a11(x)...a1n(x)…….....…….....…….....an1(x)...ann(x);B¯(x)=b1(x)…….…….…….bn(x)(2) are matrices of known real functions. We introduce a generalisation of the usual matrix exponential function and the Green function of fractional order, in connection with the Mittag-Leffler type functions. This function allows us to obtain an explicit representation of the general solution to system (1) when A is a constant matrix, in a way analogous to the usual case. Some applications of this theory are presented through the natural connection between system (1) and linear differential equations of fractional order. Some new models are presented.
A Hierarchical Approach for Design and Assembly of Mechanisms
Authors: Mukundakrishnan Bharath , Kumar Vijay , Song Peng , Trinkle J. C. , Pang Jong-Shi
Published: June 2008

We introduce a hierarchical approach for the analysis and design of systems with multiple frictional contacts, with a focus on applications to the design of part feeding and assembly processes. The simplest model in the hierarchy is the geometric model described by a set of non-penetration constraints that depends only on the geometry of the design. The model with the highest fidelity is one that incorporates rigid body dynamics, joint constraints, and frictional contacts. Our approach is based on a scheme that first uses Rapidly-exploring Random Trees (RRTs) to explore and prune the feasible set of design parameters. The next step is to redesign the system iteratively with the pruned parameter set using a model with higher fidelity. This process is repeated with improved models, until an optimal design is obtained with the model of desired fidelity. We illustrate the models, the design process, and the feasibility of this hierarchical approach by applying it to the design of a simple part feeder.
Wheel-Terrain Contact Modeling in the ROAMS Planetary Rover Simulation
Authors: Sohl Garett , Jain Abhinandan
Published: June 2008

This paper describes wheel-terrain contact modeling in the ROAMS physics-based simulator for planetary surface exploration rover vehicles. ROAMS models a wide range of rover systems and provides a user interface to a simulated rover. The wheel-terrain interaction is of primary interest during rover motion over rough terrain. The wheel-terrain contact model must provide physically realistic behavior without being too computationally intensive for real-time simulation. Physically realistic behavior may be defined using empirical data and ROAMS provides mechanisms for tuning the contact model parameters to match this data. In cases where empirical data is non-existent or there are large amounts of uncertainty, ROAMS can be used to extrapolate a range of behaviors based on physical parameters. The ROAMS simulator can be used in stand-alone mode, for closed-loop simulation with on-board software or for operator-in-the-loop simulations.
Dynamic Testing and Simulation of the Mars Exploration Rover
Authors: Lindemann Randel
Published: June 2008

In January of 2004, NASA landed two mobile robotic spacecraft on the surface of Mars as part of the Mars Exploration Rover (MER) project. Named Spirit and Opportunity, each of these rovers is performing their separate scientific missions of exploration more than a year after landing. The Mars Exploration Rovers represent a great advance in planetary rover technology. Part of that advance is represented by the mobility capabilities of these vehicles. At the 1.5 year mark, the two vehicles have traversed more than 10 km over broad plains, craters, rocks, and hills. In order to assess the mobility characteristics of the rovers in the Mars environment, an engineering model vehicle was tested before the mission launches in a representative environment of slopes, rock obstacles, and soft soil. In addition, to gain better insight into the rovers’ capabilities, a dynamic model of the rovers was created in the software package ADAMS. The rover model was then used to simulate many of the test cases, which provided a means for model correction and correlation. The results and lessons learned of the test and dynamic simulation of the MER vehicles is provided in this paper. The results from the test and simulation program allowed Spirit and Opportunity to be used in terrain well outside of the original mission requirements. The resulting increase in terrain access, led to substantial additions to the missions science return.
Flatness Control: Application to a Fractional Thermal System
Authors: Melchior Pierre , Cugnet Mikae¨l , Sabatier Jocelyn , Oustaloup Alain
Published: June 2008

This paper concerns the application of flatness principle to fractional systems. As soon as the path has been obtained by flatness, a new robust path tracking based on CRONE control is presented. The flatness concept in path planning is used when the trajectory is fixed (in space and in time), to determine the controls to apply without having to integrate any differential equations. A lot of developments have been made but, in the case of non integer differential systems (or fractional systems), few developments are still to be made. So, the aim of this paper is to apply flatness principle to a fractional system and to define a robust path tracking by CRONE control strategy. Firstly, we remind flatness principle definitions used in control’s theory. We study the fractional systems dynamic inversion. A robust path tracking based on CRONE control is presented. Finally, simulations with two different controllers (PID and CRONE) illustrate the path tracking robustness.
The Hamel Representation: A Diagonalized Poincare´ Form
Authors: Sovinsky Michael C. , Hurtado John E. , Griffith D. Todd , Turner James D.
Published: June 2008

The Poincare´ equations, also known as Lagrange’s equations in quasi coordinates, are revisited with special attention focused on a diagonal form. The diagonal form stems from a special choice of quasi velocities that were first introduced by Georg Hamel nearly a century ago. The form has been largely ignored because the quasi velocities create so-called Hamel coefficients that appear in the governing equations and are based on the partial derivative of the mass matrix factorization. Consequently, closed-form expressions for the Hamel coefficients can be difficult to obtain and relying on finite-dimensional, numerical methods are unattractive. In this paper we use a newly developed operator overloading technique to automatically generate the Hamel coefficients through exact partial differentiation together with numerical evaluation. The equations can then be numerically integrated for system simulation. These special Poincare´ equations are called the Hamel Form and their usefulness in dynamic modeling and control is investigated.
Analysis of Power Generating Performance for Unimorph Cantilever Piezoelectric Beams With Interdigitated Electrodes
Authors: Mo Changki , Kim Sunghwan , Clark William W.
Published: June 2008

A great amount of research has been done to determine whether piezoelectric materials can be used as power generators for a variety of portable and low power consuming devices. Among the possibilities for energy harvesters, the 31-type cantilever piezoelectric benders have been generally used. In this work a unimorph piezoelectric cantilever beam with the interdigitated electrode pattern was examined. The focus of this paper was to develop a model and propose design parameters to improve the power generating performance of the interdigitated piezoelectric power harvester.
The Design of Enhanced Condition Monitoring Systems Using a Novel Sensor Positioning and Signal Conditioning Approach
Authors: Al-Habaibeh A. , Parkin R. M. , Redgate J.
Published: June 2008

This paper describes a novel approach, named Initial Optimisation Procedure (IOP), which is implemented to design enhanced condition monitoring systems. The IOP method is designed to evaluate the most sensitive location for a sensor for the detection of machine or process faults. The vibration data of a milling process is used in an experimental work to demonstrate the suggested methodology. Fourier Transformation and Wavelet are used for data analysis. The results show that the suggested approach is most suitable for vibration and acoustic emission sensors to improve the reliability and the capability of condition monitoring systems.
Modeling Imprecise and Uncertain Engineering Information in EXPRESS-G and Relational Data Models
Authors: Ma Z. M.
Published: June 2008

Computer-based information systems have become the nerve center of current manufacturing systems. Engineering information modeling in databases is thus essential. However, information imprecision and uncertainty extensively arise in engineering design and manufacturing. So contemporary engineering applications have put a requirement on imprecise and uncertain information modeling. Viewed from database systems, engineering information modeling can be identified at two levels: conceptual data modeling and logical database modeling and correspondingly we have conceptual data models and logical database models, respectively. In this paper, we first investigate information imprecision and uncertainty in engineering applications. Then EXPRESS-G, which is a graphical modeling tool of EXPRESS for conceptual data modeling of engineering information, and nested relational databases are extended based on possibility distribution theory, respectively, in order to model imprecise and uncertain engineering information. The formal methods to mapping fuzzy EXPRESS-G schema to fuzzy relational schema are developed.
Determination of Engine Roughness Using Multi-Physics Numerical Predictions
Authors: Perera M. , Theodossiades S. , Rahnejat H.
Published: June 2008

The paper presents a detailed engine modelling method, referred to as a multi-physics approach, in which combined rigid body inertial dynamics, structural modal characteristics of elastic components and tribological behaviour of load bearing surfaces can be studied within a single analysis. This approach is regarded as holistic and a good aid for detailed design. Of particular interest is the evaluation of behaviour of critical elements in the system, such as the load bearing conjunctions (e.g. crankshaft engine bearings). Another important feature is the inclusion of study of motion across the physics of scale, from micro-scale fluid film formation in bearings to sub-millimetre structural deformation of components and large displacement inertial dynamics. In order to arrive at predictions within sensible industrial time scales, it is essential to include, as far as possible, modelling features of analytical rather than numerical nature, which necessitates inclusion of some simplifying assumptions. When such an undertaking is made, the validity of model predictions must be gauged against experimental findings to enhance confidence in the use of the method. The paper shows good conformance between model predictions and experimental investigations. It further shows that some important issues in engine design and development can be addressed in a satisfactory manner, paving the way for reduction in the empirical or iterative nature of engine design evaluation.
Integrated Feature Modeller for Certain Manufacturing Processes
Authors: Jebaraj C. , Kingsly Jeba Singh D.
Published: June 2008

This work explains the development of an integrated modeler, which is applied in the design-to-manufacturing stages of manufacturing processes namely machining, sheet metal processing and forging. Its system architecture is broadly divided into four modules namely, Feature Based Design (FBD), Virtual Factory Environment (VFE), Process Based Feature Mapping (PBFM) and Process Planning (PP). Feature based design is used for the design, modeling, synthesis, representation and validation of the components for manufacturing applications. New set of features namely integrated features are pre-defined as feature templates and instanced to get / derive the information required for the design-to-manufacturing stages of the components. VFE defines the factory, which provides the database for operations, machines, cutting tools, work pieces etc. The knowledge base of the developed system maps validated features of the component into operation sets in the first phase of the PBFM. Each operation in the operation sets can be executed using different machines and tools in a factory. All these possible choices are obtained in the second phase of PBFM. Genetic algorithm is used to find the optimal sequence of operations, machines and tools for different criteria in the process planning stage. This paper explains the developed system with case studies.
A Musical Use for the Haar Function Wavelet
Authors: Caswell Daryl
Published: June 2008

The utility of the Haar function wavelet has long been dismissed due to its inability to transpose between the time domain and the frequency domain. However, the Haar function possesses attributes that make it an ideal wavelet for certain applications. In this paper, we explore the use of the Haar function as a means to expose aspects of musical tone that are not available through other sound analysis techniques. Specifically, the method presented here was used to identify the differences in the tone of the French Horn created by different acoustically reflective surfaces placed in the near field of the horn bell. The fundamentals of the Haar function wavelet are described and its use as a signal analyzer is explained. Results are shown that demonstrate the effect of two different kinds of sound reflectors constructed for a major North American concert hall.
Development of Hybrid Genetic Algorithms for the Resource Constrained Multi-Project Scheduling Problem
Authors: Liu Wenjian , Li Jinghua
Published: June 2008

In multi-project environment, multiple projects share and compete for the limited resources to achieve their own goals. Besides resource constraints, there exist precedence constraints among activities within each project. This paper presents a hybrid genetic algorithm to solve the resource-constrained multi-project scheduling problem (RCMPSP), which is well known NP-hard problem. Objectives described in this paper are to minimize total project time of multiple projects. The chromosome representation of the problem is based on activity lists. The proposed algorithm was operated in two phases. In the first phase, the feasible schedules are constructed as the initialization of the algorithm by permutation based simulation and priority rules. In the second phase, this feasible schedule was optimized by genetic algorithm, thus a better approximate solution was obtained. Finally, after comparing several different algorithms, the validity of proposed algorithm is shown by a practical example.
Integrated Multi-Body Dynamic and Cam-Tappet Contact Analysis for a Single Cylinder IC Engine
Authors: Teodorescu M. , Kushwaha M. , Rahnejat H. , Rothberg S.
Published: June 2008

The paper investigates the valve train system of a 4-stroke single cylinder engine. An integrated approach for the dynamics and tribological behavior of the mechanism, as well as cam-tappet contact characteristics is described. The proposed model predicts the cam-tappet contact sub-surface stress field as well as contact deflection. Experimental validation is provided for the dynamic model with a motored test rig, using Laser Doppler vibrometry (LDV). The model can be used in the design stage or for design evaluation.
Dynamic Pressure Data Acquisition Via Strain Gage Measurements
Authors: Szasz Gyorgy , Fujikawa Karen K. , Ananth Raju
Published: June 2008

Dynamic pressure measurements are often helpful in characterizing operating conditions within industrial piping. The most straight forward method to obtain this type of data is to mount pressure transducers on the piping [6]. The orifice necessary for these instruments, frequently presents an undesirable opening in the pressure boundary of the affected system. One type of pressure transducer employs a strain gage mounted internally on a membrane that is exposed to the pressure to be measured [4, 5]. The deformation of the membrane is proportional to the pressure to be measured and is reported as a pressure value. A union of these two concepts yields the idea of mounting the gages directly on the piping and thereby eliminating the need for compromising piping integrity. One of the challenges is performing this measurement in the presence of significant axial train that is not related to the internal pressure. In the recent past Structural Integrity Associates Inc. has successfully applied this innovative technique to several main steam piping systems in various nuclear power plants in the US. This paper will describe some of the considerations regarding compensation for interfering axial strains as well as provide sample results from existing installations.
Multi-Stage Modeling of Turbine Engine Rotor Vibration
Authors: Song Sang Heon , Castanier Matthew P. , Pierre Christophe
Published: June 2008

In this study, an efficient approach for modeling the vibration of multi-stage rotors is proposed in order to allow more realistic predictions of the free and forced response of bladed disks. The reduced-order modeling approach is based on component mode synthesis, with each stage (bladed disk) treated as a separate component. Thus, each component retains cyclic symmetry, and single-sector models may be used for calculating the component modes. Because adjacent stages typically have different numbers of blades, the single-stage models are synthesized by projecting the stage-to-stage interface motion onto a common basis of circumferentially harmonic shapes. In this manner, any mismatch between sector sizes and finite element meshes at the interface can be handled systematically and automatically, without requiring additional multi-point constraints. For further size reduction, secondary modal analysis is performed on the entire synthesized model. Therefore, only a small set of multi-stage modes are retained in the final reduced-order model, yielding an extremely compact model that retains high accuracy relative to the parent finite element model.
Free Vibration of Elliptical Plates in Uniform Temperature Field
Authors: Yao Xiaohu , Han Qiang , Dai Liming
Published: June 2008

The free vibration of clamped elliptical plate, when temperature and stress fields are coupled, is analyzed based on the fundamental equations of nonlinear thermo-elastic vibrations. A system of nonlinear differential equations of time is obtained with utilization of Galerkin’s method. The vibration states are compared with respect to different coefficients. The effects of thermo-elastic coupling on the amplitude and frequency are also presented.
Sensitivity Analysis for the Transverse Displacements of a Cracked Plate Using the Spatial Wavelet Approach
Authors: Sun H. Y. , Lee Y. Y. , Lam H. F. , Su R. K. L.
Published: June 2008

In this paper, the effectiveness of the proposed technique is used for the sensitivity analysis of cracked plates, and verified theoretically and experimentally. The transverse displacements and natural frequencies of cracked plates are obtained using the fractal two-level finite element method The transverse displacements of the cracked plates are then transformed using the spatial wavelet method. The numerical and experimental results have concluded that 1) the natural frequencies are not very sensitive to small cracks. The presences of the small cracks and crack locations cannot be identified effectively by examining the natural frequencies; 2) the transformed transverse displacements are more sensitive to the crack extent and change significantly at the crack locations, provided that the wavelet dilation index is high enough (i.e., the wavelet transform resolution is fine enough); 3) however, the experimental results show that if the wavelet dilation index is set too high, the crack locations cannot be detected from the transformed displacements. It is because the plate surface roughness in the experiment cases induces some local variations on the transformed displacement curve to mask the crack location.
Quantitative image quality evaluation of MR images using perceptual difference models
Authors: Miao Jun , Huo Donglai , Wilson David L.
Published: June 2008

The authors are using a perceptual difference model (Case‐PDM) to quantitatively evaluate image quality of the thousands of test images which can be created when optimizing fast magnetic resonance (MR) imaging strategies and reconstruction techniques. In this validation study, they compared human evaluation of MR images from multiple organs and from multiple image reconstruction algorithms to Case‐PDM and similar models. The authors found that Case‐PDM compared very favorably to human observers in double‐stimulus continuous‐quality scale and functional measurement theory studies over a large range of image quality. The Case‐PDM threshold for nonperceptible differences in a 2‐alternative forced choice study varied with the type of image under study, but wasfor diffuse image effects, providing a rule of thumb. Ordering the image quality evaluation models, we found in overall Case‐PDMIDM (Sarnoff Corporation)SSIM [Wang et al. IEEE Trans. Image Process. 13, 600–612 (2004)]mean squared errorNR [Wang et al. (2004) (unpublished)]DCTune (NASA)IQM (MITRE Corporation). The authors conclude that Case‐PDM is very useful in MR image evaluation but that one should probably restrict studies to similar images and similar processing, normally not a limitation in image reconstruction studies.
Design and evaluation of a novel breast cancer detection system combining both thermoacoustic (TA) and photoacoustic (PA) tomography
Authors: Pramanik Manojit , Ku Geng , Li Changhui , Wang Lihong V.
Published: June 2008

We have developed a novel scanner for breast cancer detection, integrating both thermoacoustic and photoacoustic techniques to achieve dual contrast (microwave and light absorption) imaging. This scanner is nonionizing, low cost, and can potentially provide high‐resolution, dual modality three‐dimensional images of the breast. The scanner uses front instead of side breast compression and dry instead of gel ultrasonic coupling. Here we present the design of the breast scanner along with initial tissue phantom study results as a precursor to an actual patient study.
Optimization of deterministic transport parameters for the calculation of the dose distribution around a high dose‐rate brachytherapy source
Authors: Gifford Kent A. , Price Michael J. , Horton John L. , Wareing Todd A. , Mourtada Firas
Published: June 2008

The goal of this work was to calculate the dose distribution around a high dose‐rate brachytherapy source using a multi‐group discrete ordinates code and then to compare the results with a Monte Carlo calculated dose distribution. The unstructured tetrahedral mesh discrete ordinates code Attila™ version 6.1.1 was used to calculate the photon kerma rate distribution in water around the Nucletron microSelectron mHDRv2 source. MCNPX 2.5.c was used to compute the Monte Carlo water photon kerma rate distribution. Two hundred million histories were simulated, resulting in standard errors of the mean of less than overall. The number of energy groups, (angular order), (scattering order), and mesh elements were varied in addition to the method of analytic ray tracing to assess their effects on the deterministic solution. Water photon kerma rate matrices were exported from both codes into an in‐house data analysis software. This software quantified the percent dose difference distribution, the number of points within and , and the mean percent difference between the two codes. The data demonstrated that a 5 energy‐group cross‐section set calculated results to within of a 15 group cross‐section set. was sufficient to resolve the solution in angle. expansion of the scattering cross‐section was necessary to compute accurate distributions. A computational mesh with 55 064 tetrahedral elements in a 30 cm diameter phantom resolved the solution spatially. An efficiency factor of 110 with the above parameters was realized in comparison to MC methods. The Attila™ code provided an accurate and efficient solution of the Boltzmann transport equation for the mHDRv2 source.
An analysis of tolerance levels in IMRT quality assurance procedures
Authors: Basran Parminder S. , Woo Milton K.
Published: June 2008

Increased use of intensity modulated radiation therapy (IMRT) has resulted in increased efforts in patient quality assurance (QA). Software and detector systems intended to streamline the IMRT quality assurance process often report metrics, such as percent discrepancies between measured and computed doses, which can be compared to benchmark or threshold values. The purpose of this work is to examine the relationships between two different types of IMRT QA processes in order to define, or refine, appropriate tolerances values. For 115 IMRT plans delivered in a 3 month period, we examine the discrepancies between (a) the treatment planning system (TPS) and results from a commercial independent monitor unit (MU) calculation program; (b) TPS and results from a commercial diode‐array measurement system; and (c) the independent MU calculation and the diode‐array measurements. Statistical tests were performed to assess significance in the IMRT QA results for different disease site and machine models. There is no evidence that the average total dose discrepancy in the monitor unit calculation depends on the disease site. Second, the discrepancies in the two IMRT QA methods are independent: there is no evidence that a better —or worse—monitor unit validation result is related to a better—or worse—diode‐array measurement result. Third, there is marginal benefit in repeating the independent MU calculation with a more suitable dose point, if the initial IMRT QA failed a certain tolerance. Based on these findings, the authors conclude at some acceptable tolerances based on disease site and IMRT QA method. Specifically, monitor unit validations are expected to have a total dose discrepancy of overall, and per beam, independent of disease site. Diode array measurements are expected to have a total absolute dose discrepancy of overall, and per beam, independent of disease site. The percent of pixels exceeding a and 3 mm threshold in a gamma analysis should be greater than or equal to for non‐head and neck IMRT cases, and for head and neck IMRT cases. The IMRT QA methodology described here is neither unique nor ubiquitous, and the ability to deliver a safe IMRT does not simply require IMRT QA tests to pass a given tolerance; however, the selection of a tolerance should be meaningful when assessing a complex plan. The methodology in defining appropriate tolerances, described in this article, is based on an interpretation of IMRT QA results from IMRT plans deemed safe to deliver.