bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective HIFU Foaming to Fabricate Porous Polymer for Tissue Engineering Scaffolds
Authors: Wang Hai , Li Wei
Published: October 2008

A novel technique is presented in this paper for the fabrication of tissue engineering scaffolds using the High Intensity Focused Ultrasound (HIFU). This acoustic method is a solvent-free, highly efficient and low cost process that has the potential in scaffold-based tissue engineering. HIFU fabrication technique is capable of creating hierarchically-structured porous polymeric materials, which have various topographical features at different length scales. This will in turn affect the cellular response and behavior of certain type of cells, such as the integration and growth of smooth muscle cells (SMCs). In this study, the effect of HIFU porous polymer fabrication was investigated. Scanning-mode HIFU insonation was performed in the HIFU polymer foaming experiments. The acoustic power and the scanning speed were chosen as the parameters and varied in different groups of experiments. The created microstructures were characterized using the scanning electron microscopy (SEM). The fabricated samples were used for cell culture studies with human aortic SMCs (Passage 4). It was found that the selective HIFU foaming process could be used to create hierarchical structures by choosing appropriate ultrasound parameters. The SMCs were viable on the HIFU-created porous PMMA specimens, and the topographical nature of a HIFU-created porous structure affected the cellular response of SMCs.
Fabrication of a Nanoscale Ti-Ta-Nb Alloy Coating and Its Effect on Osteoblast Precursor Initial Response
Authors: Yang Y. , Moore M. , Appleford M. , Liu Y. , Kim S. , Chen W. , Oh S. , Park S. , Kim Y. , Choi N. , Lee D. J. , Lee K. , Bumgardner J. , Haggard W. , Ong J.
Published: October 2008

The aim of this study was to prepare a novel titanium-10tantalum-10niobium (Ti-Ta-Nb) alloy nanoscale coatings using sputter deposition and to evaluate their effect on osteoblast response. The three groups of Ti alloy used in this study were: (1) as-sputtered Ti-Ta-Nb coatings; (2) Ti-Ta-Nb disks; and (3) Ti6Al4V alloy disks as controls. The three surfaces were characterized using a x-ray diffractometer, a scanning electron microscope, a surface profilometer, and a contact angle measuring instrument. ATCC CRL 1486 human embryonic palatal mesenchymal cells were used to evaluate the cell responses. Cell attachment was measured using a coulter counter. After 4 days incubation, dsDNA, total protein, and alkaline phosphatase of the attached cells were assayed. The as-sputtered Ti-Ta-Nb coatings consisted of dense nanoscale grains. The Ti-Ta-Nb coatings exhibited significantly greater cell attachments compared to the two polished microgroove groups at 30minutes and 1hour. No significant differences were observed in dsDNA amount, total protein production and alkaline phosphatase specific activity among the three groups. These results demonstrated an equivalent performance for the Ti-Ta-Nb alloy and its nanoscale Ti-Ta-Nb coatings, suggesting an alternative biocompatible metal for use in dentistry and orthopedics.
Zirconia Thin-Films for Toughened Ceramics
Authors: Thompson J. Y. , Stoner B. R. , Piascik J. R.
Published: October 2008

Partially-stabilized zirconia (PSZ) has been studied extensively, due to its high temperature stability and stress-induced tetragonal to monoclinic phase transformation, which can elicit enhanced fracture resistance. Applications include thermal barriers, high-k dielectric gate oxides, biomedical components, and solid oxide fuel cells, where not only temperature is a factor, but aggressive environments can compromise function. Research has advanced from using PSZ in bulk form to creating thin films that utilize the same material properties. PSZ, where the high temperature tetragonal phase is stabilized at room temperature, offers the ability to create a thin film that takes advantage of the unique properties of zirconia by improving the fracture behavior of brittle substrates. Yttria (3 mol%) stabilized zirconia (YSZ) can be deposited by radio frequency (rf) magnetron sputtering under varying deposition parameters to produce thin films with unique microstructures and properties. Most YSZ films are characterized by a columnar grain structure, and it has been found that inter-crystalline porosity and overall film density can be controlled by applying differing substrate bias during film deposition. Film stress can subsequently be manipulated over a broad range. Initial film stresses ranging from approximately 100 MPa tensile to 200 MPa compressive have been reproducibly produced. It has also been found that exposure of YSZ thin films containing measurable inter-granular porosity (10–100Å) to ambient conditions (25°C, 75% relative humidity) leads to a substantial increase in compressive stress of films (as much as 100 MPa). Thermal reversibility of this environmental aging effect suggests a water vapor absorption mechanism that might be tailored to specific applications.
Bioactivity and Mechanical Behavior of Polymer-Hydroxyapatite Composite Biomaterials for Bone Tissue Engineering
Authors: Katti Kalpana S. , Verma Devendra , Bhowmik Rahul , Katti Dinesh R.
Published: October 2008

Achieving optimal mechanical strength of scaffolds is the key issue in bone tissue engineering. We describe a biomimetic route for design of composites of polymers (polyacrylic acid (PAAc) and polycaprolactone (PCL)) and hydroxyapatite (HAP). The mineral polymer interfaces have a significant role on mechanical behavior as well as bioactivity of the composite systems. We have used a combination of experimental (photoacoustic infrared spectroscopy) as well as modeling (molecular dynamics) techniques to evaluate the nature of interfaces in the composites. Porous composite scaffolds of in situ HAP with PCL are made. Our simulation studies indicate calcium bridging between COO− of PAAc and surface calcium of HAP as well as hydrogen bonding. These results are also supported by infrared spectroscopic studies. PAAc modified surfaces of in situ HAP influence the microstructure and mechanical response of porous composites. Significant differences are present in the mechanical response of in situ and ex situ composite scaffolds. In addition, the growth and mechanism of apatite growth in the in situ and ex situ composites is different. Bioactivity is measured by soaking composite scaffolds in simulated body fluid (SBF). Apatite growth in ex situ composites is primarily by heterogeneous nucleation and that in in situ is primarily by homogeneous nucleation. We also observe that apatite grown on in situ HAP/PCL composites from SBF exhibits higher elastic modulus and hardness. Thus, by influencing the interfacial behavior in bone biomaterials both mechanical response and bioactivity of the composite systems may be modified. The present study gives insight into the interfacial mechanisms responsible for mechanical response as well as bioactivity in biomaterials.
Numerical Simulation and Optimization of a Tee Shaped Tube Hydroforming Process
Authors: Crapps J. , Fang H. , Horstemeyer M. F.
Published: October 2008

We performed numerical simulations and multiobjective optimization of a hydroforming process for copper tees using the BCJ plasticity material model developed by Bammann et al., which accounts for material manufacturing and history effects. A finite element simulation of the hydroforming process was created using data from experiments and the industrial process. The process parameters and geometry factors were optimized using a multiobjective optimization methodology employing metamodeling and software developed at Mississippi State University’s Center for Advanced Vehicular Systems.
Failure Modes and Mechanisms of Functionally Gradient Ceramic Tools With High Thermal Shock Resistance
Authors: Zhao J. , Ai X.
Published: October 2008

As cutting tool materials, ceramics posses high hardness, wear resistance, heat resistance and chemical stability, with less deformation or dissolution wear in cutting processes. In spite of the advances in strengthening and toughening of ceramic tool materials as well as the improved processing techniques, their applications in intermittent cutting operations are still restricted by their intrinsic drawbacks such as lower strength, lower fracture toughness and lower thermal shock resistance. The introduction of the concept of functionally gradient materials (FGM) into the design and fabrication of ceramic cutting tool materials provides an approach to improving the thermomechanical properties of ceramic tool materials. However, the investigations on the thermal shock resistance evaluation of FGMs for cutting tool applications have been very few, with most work concentrating on the design, fabrication and evaluation of heat-shielding FGMs for space applications. A strength-based fracture criterion for thermal shock resistance evaluation of FGM ceramics is formulated in the present paper, based on which the design rules for FGM ceramics with high thermal shock resistance are presented. An Al2O3/TiC and an Al2O3/(W, Ti)C functionally gradient ceramic tool materials were consequently designed and fabricated by using hot pressing technique. Their cutting performance, failure modes and mechanisms were investigated via a series of intermittent cutting experiments in comparison with those of common ceramic tools. The results revealed improved tool lives of the FGM tools over that of the corresponding common ceramic tools with the same composition systems. The FGM tools exhibited similar wear and chipping characteristics to that of common ceramic tools at initial and normal cutting stages, but different failure modes from that of common ceramic tools. The failure of common ceramic tools was mainly caused by thermal shock and thermal fatigue, whereas the failure mechanisms of the FGM tools were mainly the mechanically induced wear and mechanical fatigue in virtue of their improved thermal shock resistance.
Sand Erosion Performance of Gradient Ceramic Nozzles by Abrasive Air-Jets
Authors: Deng Jianxin
Published: October 2008

A SiC/(W,Ti)C ceramic nozzle with gradient structures was produced by hot pressing. The purpose is to reduce the tensile stress at the entry region of the nozzle in abrasive air-jet. The sand erosion performance of this kind gradient ceramic nozzle caused by abrasive particle impact was investigated by abrasive air-jets in comparison with the common one. Results showed that the gradient ceramic nozzles exhibited an apparent increase in erosion wear resistance over the common ceramic nozzles. The mechanism responsible was explained as the formation of compressive residual stresses in nozzle entry region in fabricating process of the gradient ceramic nozzles, which may partially counteract the tensile stresses resulting from external loadings. It is indicated that gradient structures in ceramic nozzles is an effective way to improve the erosion wear resistance of common ceramic nozzles.
Identification of Friction Factors for Chamfered and Honed Tools Through Slip-Line Field Analysis
Authors: Karpat Yigˇit , O¨zel Tugˇrul
Published: October 2008

Analysis of tool-chip friction for tools with edge design in metal cutting helps to understand the complex material behavior around the cutting edge of the tool. The results of this analysis can be used to identify optimum tool edge design to achieve the most desirable machining performance. In this study, slip-line field analysis approach is used to investigate the average friction factor at the tool-chip interface and the dead metal zone phenomenon in orthogonal cutting for chamfered and honed tools. In an experimental set-up, an orthogonal cutting test of AISI 4340 steel is performed. Measured forces are utilized in identifying the friction factors at the tool-interface for both chamfered and honed tools for varying feed rates. Comparison of predicted and measured forces indicates good agreements. The results of this study can be utilized in designing friction at tool-chip interface for Finite Element simulations of machining with edge design tools. This study can also be extended to waterfall hone tools to identify the most optimum cutting edge geometry.
Worn Tool Force Modeling in 3D Oblique Cutting Under Hard Turning Conditions
Authors: Long Yu , Huang Yong
Published: October 2008

Quantitative understanding and prediction of cutting forces using worn tools is important to cutting process thermal modeling, tool life estimation, chatter prediction, and tool condition monitoring purposes. In this paper, a modeling approach in 3D oblique cutting is presented. The cutting configuration is featured with worn chamfered tools with a rounded tool nose under hard turning conditions, which are characterized by small feed rate and small depth of cut using a chamfered nose radius tool. The whole cutting edge is discretized into a number of elements, which follow the same chip flow angle. The force information is modeling by collectively considering the forces on each discretized elementary cutting edge based on a worn tool force model. The proposed model is further validated with the experimental hard turning studies. It is found that the chip flow angel does not change noticeably with tool wear. The predicted cutting and feed forces are relatively accurate compared with the predictions of the thrust forces. The force modeling accuracy is expected to be further improved by accurate consideration of the flank and crater wear geometry and generalization of the interaction forces between the discretized chip elements along the tool nose of the chamfer zone in the future studies.
Results of a Survey on Web-Based Approaches to Global Outsourcing in the Manufacturing Industry
Authors: Ameri Farhad , Dutta Debasish
Published: October 2008

Today, manufacturing industry is characterized by globalization, unpredictability and rapid change. To be competitive, companies are globally outsourcing activities that are outside their core competencies. In this context, online marketplaces for manufacturing services have become attractive venues for developing supply chain relationships. Despite their significant growth within last few years, online markets are still in their infancy phase. One of the underdeveloped areas in such markets is supply and demand representation. This paper reflects the result of a survey on the existing online markets in the manufacturing industry. Particular focus of this survey is on identifying the major criteria used by market administrators and users for describing supply and demand. Findings of this survey can provide preliminary data for future efforts in development of standard models for conceptualization and representation of supply and demand in online markets.
Quality Assured Setup Planning Based on the Stream-of-Variation Model for Multi-Stage Machining Processes
Authors: Liu Jian , Shi Jianjun , Hu S. Jack
Published: October 2008

Setup planning is a set of activities to arrange manufacturing features into an appropriate sequence for processing. As such, setup planning can significantly impact the product quality in terms of dimensional variation in the Key Product Characteristics (KPC’s). Current approaches in setup planning are experience-based and tend to be conservative by selecting unnecessarily precise machines and fixtures to ensure final product quality. This is especially true in multi-stage manufacturing processes because it has been difficult to predict the variation propagation and its impact on KPC quality. In this paper, a new methodology is proposed to realize cost-effective, quality ensured setup planning for multi-stage manufacturing processes. Setup planning is formulated as an optimization problem based on quantitative evaluation with the Stream-of-Variation (SoV) models. The optimal setup plan minimizes the cost related to process precision and satisfies the quality specifications. The effectiveness of the proposed approach is demonstrated through setup planning for a multi-stage machining process.
Solving the Multi-Objective Facility Layout Problem Using Evolutionary Multi-Objective Optimization Algorithms
Authors: Ismail Mohamed A. , Gomaa Attia H. , Nassef Ashraf O.
Published: October 2008

The multi-objective facility layout problem is defined in the literature as an extension of the famous quadratic assignment problem (QAP). Most previous mathematical models tried to combine both the quantitative and the qualitative objectives into a single objective by using weighting factors. This paper introduces a multi-objective mathematical model and solves it using the revised Strength Pareto Evolutionary Algorithm (SPEAII). The purpose of this paper is to find an efficient set of solutions “Pareto optimal set” which could be introduced to the decision maker to select the best alternative, while considering conflicting and noncommensurate objectives. A computer program is developed to define the mathematical model, code candidate solutions into genetic form, and use Evolutionary Multi-Objective Optimization algorithms (EMO) to find the efficient set of solutions. The problem model is built according to its customized data input. The suggested model and solution algorithms are applied to a wide set of different benchmark problems. Results showed the superiority of the suggested models and algorithms in terms of the quality of solution and objective space exploration.
A New Approach to G1 Biarc Approximations for Making Smooth, Accurate, and Non-Gouged Profile Features Using CNC Contouring
Authors: Chen Zezhong C. , Yang Xujing
Published: October 2008

Extensive research on G1 biarcs fitting to free-form curves (i.e., Bezier, B-spline, and NURBS curves) has been conducted in the past decades for various purposes, including CNC contouring to make smooth, accurate profile features such as pockets, islands, and sides. However, all the proposed approaches only focused on the approximation errors and the biarc number, not on the radius of the individual fitting arc; so it could be smaller than the cutting tool, which would cause gouging during machining. This work, based on the tool radius pre-determined by the minimum size of the concavities of the design profile, proposes a new approach to approximating the profile with a G1 biarc curve in order to make smooth, accurate, and non-gouged profile features using CNC contouring. The significant new contribution of this work is a new mechanism that ensures all the concave arcs of the fitting curve are larger than the pre-determined tool and the fitting errors meet the specified tolerance. This approach can promote the use of G1 biarc tool paths in the manufacturing industry to make high precision profile features.
A New Approach to Determining Optimum Tool Size for Finish Milling of NURBS Profiles
Authors: Zhang Hongda , Chen Zezhong C.
Published: October 2008

A curve model of non-uniform rational B-spline (NURBS) has been widely adopted in mainstream CAD/CAM software systems to design complicated geometries of mechanical parts, for example, the curved profiles of pockets, sides, and islands. To accurately produce these geometries in finish milling, the size of the cutting tool should be optimized in order to attain high machining efficiency. Although this has been a research focus for a decade, optimal tool size determination still remains as a technical challenge. This work proposes a new approach to addressing this challenge so that the cutting tool of the largest allowable size is selected for finish machining without global and local gouge on the part. In this approach, a global optimization problem is formulated for the optimum tool size, and particle swarm optimization (PSO) method is employed to solve this problem. As a result, this approach can efficiently optimize the tool size for finish machining of the NURBS profiles; on the other hand, it can be more accurately and efficiently to detect global and local gouge on the profiles. Since it is easy to implement, this approach can be directly used in the manufacturing industry.
Agent-Based Process Sequencing Using Search Algorithms
Authors: Sormaz Dusan N.
Published: October 2008

Process sequencing represents one of very important tasks in the process planning. The order of tasks and the use of resources are determined by sequencing, and therefore the decision carries the burden of finally optimizing the whole process plan of the part. This paper proposes a flexible, agent-based framework for process sequencing which allows for realtime selection of the sequencing algorithm, dependent on the stage of the product development. The framework has been developed around a tool called space searcher which provides for application of space search algorithms in various domain. Space searcher receives a sequencing agent which provides the sequencing algorithm and executes a space search in order to generate context-specific optimal process sequence. Several process sequencing algorithms (and corresponding agents for space searcher) are described in detail. The application of those algorithms is illustrated on few examples.
Haptic-Based Product Prototyping and Virtual Sculpting Using Visibility Sphere Marching Algorithm in Constructing Polyhedral Models
Authors: Zhu Weihang , Lee Yuan-Shin
Published: October 2008

This paper presents a visibility sphere marching algorithm of constructing polyhedral models from Dexel volume models in haptic virtual sculpting for virtual prototyping and manufacturing. This paper presents a top-down approach in analyzing the conversion problem. The proposed visibility sphere marching algorithm is composed of 3 sub-algorithms: roof and floor covering, wall-building and hole-filling algorithms. Dexel volume model is used as the in-process model representation during interactive modification in a virtual sculpting system. The stock material represented in Dexel volume model is sculpted into a designed model using a developed haptic sculpting system. The sculpted Dexel volume model can be converted to polyhedral surface model in STL format by the proposed visibility sphere marching algorithm. Polyhedral surface model can then be input to and processed by available CAM (Computer-aided Manufacturing) or RP (Rapid Prototyping) systems. The presented technique can be used in virtual sculpting, CAD/CAM, NC (numerically-controlled) machining verification, and rapid prototyping.
Modeling of Manufacturing Complexity in Mixed-Model Assembly Lines
Authors: Zhu Xiaowei , Hu S. Jack , Koren Yoram , Marin Samuel P.
Published: October 2008

Mixed-model assembly lines have been recognized as a major enabler to handle product variety. However, the assembly process becomes very complex when the number of product variants is high, which, in turn, may impact the system performance (quality and productivity). The paper considers the variety induced manufacturing complexity in manual, mixed-model assembly lines where operators have to make choices for various assembly activities. A complexity measure called “Operator Choice Complexity” (OCC) is proposed to quantify human performance of making the choices. The OCC takes an analytical form as an information-theoretic entropy measure of the average randomness in a choice process. Meanwhile, empirical evidences are provided to support the proposed complexity measure. Based on the OCC, models are developed to evaluate the complexity at each station, and for the entire assembly line. Consequently, complexity can be minimized by making systems design and operation decisions, such as error-proof strategies and assembly sequence planning.
Nonlinearity Analysis of Multi-Station Assembly Processes
Authors: Ren Yuan , Ding Yu , Zhou Shiyu
Published: October 2008

Linearization is commonly employed in modeling of multi-station manufacturing processes for quality improvement purposes. However, an analysis of the accuracy of the linear models is inevitable before they could be used, because practical manufacturing processes are inherently nonlinear. Such analysis is not straightforward for the high dimensionality of multi-station manufacturing processes and the complicated relationship between process parameters and the process output. This paper presents a nonlinearity analysis method for multi-station assembly processes through an integration of experiment design and data mining. It is found that certain design parameters (e.g., the ratio between locator deviations and the distance between locators) and the number of stations play an important role in the linearization error. Although demonstrated in the specific context of two dimensional multi-station assembly processes, the proposed method can be applied to investigate many characteristics of a broad variety of manufacturing process models.
Simultaneous Scalable-Reconfigurable Manufacturing System Design and Inventory Control Policy Decision Making
Authors: Spicer J. Patrick , Carlo Hector J.
Published: October 2008

Scalable reconfigurable manufacturing systems (scalable-RMS) consist of standardized modular equipment that can be quickly added or removed to adjust the production capacity. Each modular machine, referred to as a scalable reconfigurable machine tool (scalable-RMT), is composed of identical modules that can be added to, or removed from the machine depending on its required throughput. In previous work, conceptual scalable-RMTs have been described. Additional scalable-RMTs are presented in this paper to highlight the applicability of this concept in manufacturing. As an extension to existing scalable-RMS literature, this paper incorporates multiple products in the system configuration design. Specifically, this paper proposes an integer programming based iterative algorithm for finding the minimum cost configuration of a multi-product system. It is shown that the proposed algorithm converges to the optimal solution under the majority of practical conditions. Then, a mathematical formulation to minimize the system investment and operational costs in a multi-product scalable-RMS is presented. A numerical example compares the solution obtained using the traditional approach of determining the system design and then the inventory control policy versus the proposed simultaneous approach. It is concluded that the simultaneous approach yields significant improvement over the traditional (decoupled) approach.
Automobile Warranty Forecasting Using Wavelet Transform Analysis and Neural Networks
Authors: Rai Bharatendra , Singh Nanua
Published: October 2008

Automobile warranty forecasting is made challenging by ‘maturing data’ (also called warranty growth) phenomena that causes warranty performance at specific months-in-service (MIS) values to change with time. In this paper a wavelet transform based technique is proposed for forecasting the warranty performance in presence of the ‘maturing data’ phenomena. The wavelet transform helps to cut the warranty performance data into different frequency components, and then allow study of each component with a resolution matched to its scale. In other words it allows the use of long time intervals (or longer window widths) for low-frequency information and shorter regions (or shorter window width) for higher-frequency information. The shorter the window width, the better is the resolution. The window widths of the wavelet transform can be adjusted automatically, and provide better time resolution for high frequency components and better frequency resolution for low frequency components of the warranty performance pattern. The proposed approach first decomposes the warranty performance patterns into several scales at different levels of resolution using wavelet transform analysis. The decomposition involves an approximate part from which higher frequency information has been filtered and detail parts from which lower frequency information have been filtered. The chosen approximate and detail parts are extended using neural networks. Subsequently original and the forecasted signals are reconstructed to obtain forecast values for the warranty performance. A real-world application example is used to illustrate the use of the proposed methodology.
Variation Analysis for Rigid Workpiece Locating Considering Quadratic Effects Using the Method of Moments
Authors: Cao Jun , Lai Xinmin , Cai Wayne , Jin Sun
Published: October 2008

Locators are used to constrain and position workpieces. The proper arrangement of locators, i.e., the locating scheme, is essential for both functionality and quality. In this paper, we propose a quadratic method to calculate the positional and rotational variations of a rigid workpiece using the Method of Moments. First, the workpiece geometry is quadratically approximated (hence allowing the inclusion of the linear and quadratic geometry data) to form the nonlinear constraint equations of the locators through a homogenous coordinate transformation. For a deterministic analysis, these highly nonlinear constraint equations can be solved using the Newton-Raphson method. To calculate the workpiece variations due to the locating source variations, the workpiece positional and rotational errors are first quadratically approximated around the locator positions using the Taylor expansion and then calculated using the Method of Moments. The advantage of the Method of Moment for a variation analysis is its efficiency as compared to the time-consuming Monte Carlo simulations. Examples are presented to benchmark the proposed method with prior research. By using the proposed method, the quadratic geometry effect and the interactions between locating source errors can be captured and hence the analysis results are more accurate, especially when error sources are large.
Variation Propagation Analysis on Compliant Assemblies Considering Contact Interaction
Authors: Xie Kang , Wells Lee , Camelio Jaime A. , Youn Byeng D.
Published: October 2008

Dimensional variation is inherent to any manufacturing process. In order to minimize its impact on assembly products is important to understand how it propagates through the assembly process. Unfortunately, manufacturing processes are complex and in many cases highly non-linear. Traditional assembly models have represented assembly as a linear process. However, assemblies that include the contact between their components and tools show a highly non-linear response. This paper presents a new assembly methodology considering the contact effect. In addition, an efficient to predict output response is presented. The enhance dimension reduction method (eDR) is used to accurately and efficiently predict the statistical response of the assembly to variation on the input parameters.
On-Line Seam Detection in Rolling Processes Using Snake Projection and Discrete Wavelet Transform
Authors: Li Jing , Shi Jianjun , Chang Tzyy-Shuh
Published: October 2008

This paper proposes an on-line quality inspection method to detect seam, a major type of surface defect generated in rolling processes. A feature-preserving snake-projection procedure is first adopted to convert the images of suspect seams to one-dimensional sequences. Discrete Wavelet Transform is then performed on the derived sequences with features extracted from wavelet coefficients. Finally, T2 control chart is established to discriminate between real seams and false positives. Minimization of the discrimination error based on training data is also presented with illustrations. On-line implementation of the proposed method shows that it satisfies the requirements of both detection accuracy and detection speed.
Pattern Identification in Complex Systems: A Statistical Thermodynamic Approach
Authors: Gupta Shalabh , Srivastav Abhishek , Ray Asok
Published: October 2008

This paper presents a novel method of pattern identification in complex systems using the tools derived from statistical thermodynamics. Complexity issues arise in natural or human-engineered systems due to behavioral uncertainties and nonlinearities involved in the process dynamics. The paper introduces a novel concept of behavioral pattern identification and anomaly detection in mechanical systems from macroscopically observed time series of the available sensor data. The theme is built upon the principles of Statistical Thermodynamics and Information Theory. The efficacy of this method is experimentally validated on a laboratory apparatus where the behavioral changes accrue from the evolving fatigue damage in polycrystalline alloy structures.
Fuel Cell Condition Assessment Using Transient and Standard Polarization Curves
Authors: Li C. James , Chien Alex
Published: October 2008

To identify important fuel cell performance parameters for predicting its performance and assessing its health, this paper describes a two-step procedure that uses standard and transient polarization curves in sequence to identify activation, resistance and concentration losses of a fuel cell system. An existing fuel cell model was modified to facilitate simulation studies which were used to ascertain the feasibility and limitation of the proposed method.
Model Based PEM Fuel Cell Health Monitoring
Authors: Li C. James
Published: October 2008

To identify important fuel cell performance parameters for predicting its performance and assessing its health from its operating data (without performing special tests), this paper describes a model based parameter identification approach. It employs a non-linear programming method to identify optimal values of parameters of a fuel cell model that minimize the difference between the voltage trajectory predicted by the model and that of an actual fuel cell when both are subjected to the same current draws. Using an existing fuel cell model, simulation studies were carried out to demonstrate the feasibility. Specifically, the membrane resistance and a coefficient of the concentration loss term were identified. The study shows that both can be identified accurately even poor initial guesses were used.
An Advanced Vibration Based Real-Time Machine Health and Process Monitoring System
Authors: Jalluri Chandra , Magadi Prashanth , Viswanathan Mohan , Furness Richard , Kluft Werner , Hostettler Friedhelm
Published: October 2008

The ever-increasing emphasis on product quality with increased productivity has been driving the automotive manufacturing industry to find new ways to produce high quality products without increasing production time and manufacturing costs. In addition, automotive manufacturing plants are implementing flexible manufacturing strategies with computer numerical control (CNC) machining centers to address excess capacity, shifting consumer trends and future volume uncertainty of products. Over time, plants have used several preventative and predictive maintenance methods to address machine reliability. Such systems include, but are not limited to, scheduling machine down times at regular intervals to check/replace bearings and other spindle/slide components before they can have an adverse affect on part quality. However, most of these methods and traditional systems are not cost effective and cause significant machine down-times, safety concerns and labor overheads and do not reliably monitor other process issues, such as, clamping, incoming stock variations and thermal phenomena. This paper describes an advanced real-time vibration based machine health and process monitoring system that has been developed to address the above issues. The system, called Condition Indicator Analysis Box for CNC (CIAB™-CNC), is easily configurable, and provides real-time data and historical trends of machines, processes and tooling, enabling manufacturing plants to make accurate predictions regarding future production runs. The system also aids in the optimization of preventative maintenance tasks in a cost effective manner. The developed system monitors machine spindle and slide for unbalance, misalignment, damaged/spalled bearings, mechanical looseness, and ball screw issues. Additionally, it performs in-process monitoring during machining as well as non-machining by individual tool and/or feature to detect tool breakages, quality issues and other gross process or machine anomalies. Innovative statistical trending algorithms enable the system to automatically adapt to valid process/parameter changes and significantly reduce the chances of false alarms and warnings. The developed system provides manufacturing plants with a tool to analyze machine tools and their associated components in an effort to gather information they can use effectively to make decisions regarding flexible machines, processes and tooling.
Part Accuracy in High-Speed Machining: Preliminary Results
Authors: Schmitz Tony L. , Ziegert John C. , Zapata Raul , Canning J. Suzanne
Published: October 2008

This paper provides preliminary results from a study of the relative contributions of various error sources to overall dimensional errors in parts produced by milling operations. The error sources studied include machine geometry errors, thermal errors, controller tracking errors, and errors due to cutting forces. These error sources are modeled and measured on a modern high-speed machining CNC machining center. It is found that dynamic cutting force errors can be a significant contributor to part dimensional errors in high-speed milling operations.
Mechanical Design of a Precision Instrument for Measuring the Roundness Profiles of Micro Shafts
Authors: Loychik Neil , Barraja Mathieu , Khan Afzal , Vallance R. Ryan , Marsh Eric R. , Arneson Dave A.
Published: October 2008

This paper presents a new instrument for measuring roundness profiles of axially symmetric micro shafts with diameters below 250 micrometers. The instrument will measure form error in cutting tools used for micro machining, small-hole metrology probes, and other high aspect ratio micro structures. This instrument operates on the same physical principle as scanning tunneling microscopes, which measure surface topography using fluctuations in tunneling of electrons between probe and sample. The instrument will measure roundness profiles using a fixed-sensitive-direction arrangement of the detector, similar to macro scale metrology instruments. Challenges resulting from dimensional scaling necessitate an entirely new instrument compared to conventional instruments. We describe the need for this instrument, its working principle, architecture, the design of the traction drive mechanism, and the design of the nano positioning stages.
Surface Characterization and the Functionality of Mating Parts
Authors: Wyatt J. E. , Smith G. T. , Berry J. T.
Published: October 2008

The surface of a machined component is the only part of that item which interacts with its surrounding or mating parts. Therefore, the surface must be made suitable to perform the function for which that component was designed. Most designs merely specify the average surface roughness Ra. This parameter does not reflect the suitability of the surface to perform its designed function. If the surface is to be either a bearing/lubricating surface, as opposed to a locking surface used for painting or coating, then the Ra value is somewhat misleading. The parameters that have to be employed are those of Skewness (Rsk) and Kurtosis (Rku). These can be directly measured with currently available surface analysis systems. When these surface measurements are compared to each other then the functionality of the surface can be determined on a basis of being either a bearing or locking surface. All manufacturing operations will produce surfaces which, dependent on the operation and selected parameters will show a particular functionality characteristic for the area measured. This study examines the suitability of high speed milling techniques in producing either bearing or locking type surfaces. The study uses specially designed face and end mills to machine three grades of stainless steel, two austenitic and one martensitic. It is interesting to note that when employing 12mm diameter endmills with differing axial rake angles with cutting speeds between 100 and 750 m/min, the surface tends to be generally bearing in nature. However, this is not true for a cutting speed of 500 m/min where the surface topography skews to become locking and then once the speed is increased it reverts to bearing. This interesting phenomenon, which is repeatable, is currently being investigated by the authors. Later work will discuss observations using the custom designed facemill.
Laser Interferometry Hologram Registration for Three-Dimensional Precision Measurements
Authors: Huang Z. , Shih A. J. , Ni J.
Published: October 2008

Laser holographic interferometry is an advanced precision measurement technology with sub-μm accuracy and large, over 17 mm, depth-of-field. The limitation of current laser holographic interferometry is the limited measurement area, which cannot be larger than the field of view (FOV). A hologram registration method without using targets is developed to overcome this problem. The theory of laser holographic interferometry, including the phase-shifting and multi-wavelength tuning, is described. The cross-correlation analysis is used to find the translation and overlapped regions, which determine the tilt and shift correction for data registration. The proposed method is validated using two examples with different approaches. The first example, a wheel hub, is smaller than the FOV and demonstrates only 0.1 μm discrepancy of the surface flatness between the registered and standard measurements. The second example, an engine combustion deck surface, is larger than the FOV. The registered surface measurements are compared to that of coordinate measurement machine (CMM) with only 2.5% discrepancy of the peak-to-valley flatness. This data registration method enables the sub-μm precision and large depth of field (several centimeters) measurement of large size objects.
Friction Drilling: A Chipless Hole-Making Process
Authors: Miller Scott F. , Shih Albert J.
Published: October 2008

This paper summarizes the research on friction drilling, a chipless hole making process using the rotating conical tool. Extensive research in experiment, modeling, tool wear, and metallurgical analysis of friction drilling tool and workpiece has been carried out to demonstrate the feasibility of this technology for hole-making in thin metals. The experimentally measured thrust force and torque were analyzed and compared with analytical and finite element modeling results for validation. The microstructures and indentation hardness were characterized on the cross-section of friction drilled holes for different work-materials. For brittle cast metals, effects of workpiece temperature, spindle speed, and feed rate were analyzed. The wear of a tool, which is made of hard carbide material, for friction drilling of carbon steel workpiece, was also studied to demonstrate the capability of a durable tool in the production environment.
Biomedical Manufacturing: A New Frontier of Manufacturing Research
Authors: Shih Albert J.
Published: October 2008

A new frontier of manufacturing research, biomedical manufacturing, is presented. Advanced manufacturing technologies, such as manufacturing processes, systems, and quality control, can be readily applied to improve the safety, quality, cost, and speed of medical and healthcare service and research. The analogy of hospital as factory is explored to define biomedical manufacturing. Characteristics and engineering needs of biomedical manufacturing are discussed. Examples in interventional cardiology on the grinding and cutting of plaque and the tissue machining on minimizing the nerve tissue thermal damage in surgery are used to demonstrate the broad spectrum of biomedical manufacturing research. On education, the scope and lessons learned from teaching a new senior undergraduate/first-year graduate level course in Biomedical Design and Manufacturing are presented.
EMBench: An IEC61499 Based Integrated Environment for Manufacturing Systems
Authors: Yuan Chengyin , Ferreira Placid
Published: October 2008

In these days, manufacturing organizations are facing global competition and short technological cycles. The flexibility of an enterprise and its ability to respond to miscellaneous customer requests decide the competitiveness in the global market. It also requires that the manufacturing plant must reorganize efficiently to produce various products at low cost and short time. This flexibility in the manufacturing process must be able to accommodate various tasks to share resources under safe and efficient control. In the current development processes of manufacturing systems, information handling usually is an undeveloped area. Domains such as design, validation, and deployment will be separated and isolated. One reason for the redundant non-value-added implementation of the component model is that existing system development largely consists of isolated sub-processes that generate proprietary information such as control logic, simulation models, etc. This paper focuses on introducing an innovative software environment, EMBench, which integrates mechanical design, control configuration, simulation and deployment services seamlessly for manufacturing automation systems. Its auto-generated user-friendly GUI (Graphical User Interface) supports direct commanding to the controller at different layers, and internal data (control/mechanical) and model (simulation/physical) mapping eliminates redundant and error-prone manual data entry and model replication at different stages. This tool provides a means of layered and encapsulated services so that complex systems can be designed, configured, simulated and deployed hierarchically with various levels of details. IEC61499 is an emerging industrial standard for distributed industrial process measurement & control systems. Using IEC61499 function blocks and service layer architecture, control services ranging from basic joint servo, to kinematics of a mechanism, to trajectory interpolation, to language parsing and HMI processing, to complex multiple resources/processes coordination can be configured for an application. With the adaptation of IEC61499, EMBench serves as a modular, component-based design, simulation and prototyping tool for shop floor control. Several case studies are presented in details and various potential usages in different fields are discussed. EMBench uses IEC61499 as a means for modularization and reuse of control services.
Current Developments in the Area of Micromilling Tools: Diamond Deposition and Wear Characteristics
Authors: Jackson M. J. , Robinson G. M. , Ahmed W.
Published: October 2008

Chemical vapor deposited diamond films have many industrial applications but are assuming increasing importance in the area of micro engineering, most notably in the development of diamond coated micromilling tools. For these applications the control of structure and morphology is of critical importance. The crystallite size, orientation, surface roughness, and the degree of sp3 character have a profound effect on the tribological properties of the films deposited. In this paper we present experimental results on the effects of nitrogen doping on the surface morphology, crystallite size, and wear of micromilling tools. The sp3 character optimises at 200 ppm of nitrogen and above this value the surface becomes much smoother and crystal sizes decrease considerably. Fracture induced wear of the diamond grain is the most important mechanism of material removal from a micromilling tool during the grinding process. Fracture occurs as a consequence of tensile stresses induced into diamond grains by grinding forces to which they are subjected. The relationship between the wear of diamond coated milling tools, component machining forces, and induced stresses in the model diamond grains is described in detail. A significant correlation is found between the maximum value of tensile stress induced in the diamond grain and the appropriate wear parameter, in this case the grinding ratio. It is concluded that the magnitude of tensile stresses induced in the diamond grain by machining forces at the rake face is the best indicator of tool wear during the micromachining process.