bluuebunny/crossref_metadata_2025 huggingface dataset:
An Experimental Study of the Influence of Size Effect on Springback of Micro Sheet Forming
Authors: Gau Jenn-Terng , Principe Chris , Yang Fengchen
Published: October 2008

An efficient and low cost experiment was conducted to investigate the influence of grain size effects on springback of thin sheet metal. A three-point bending setup was used to test Aluminum 1100 O-Temper and Brass 26000 1/2 Hard (H02). Thickness and average grain diameter were controlled to achieve a range of desired T/D (thickness/grain diameter) ratios because T/D ratio is a key factor that influences the springback behavior in micro sheet forming. The results from this experiment show that as T/D ratio becomes smaller (T/D > 1 → 1) the springback amount increases at a decreasing slope. And as T/D continues to become even smaller (T/D < 1) the springback amount begins to decrease. These behaviors demonstrate the influence of size effects on springback.
Fatigue and Wear Evaluation of Ti-15Al-33Nb(at.%) and Ti-21Al-29Nb(at.%) Alloys for Biomedical Applications
Authors: Boehlert Carl J. , Cowen Christopher J. , Quast Jeffrey P.
Published: October 2008

In this work the fatigue and wear behavior of Ti-15Al-33Nb(at.%) and Ti-21Al-29Nb(at.%) was evaluated and compared to that for other titanium-based biomedical implant alloys, in particular Ti-6Al-4V(wt.%). Fatigue stress versus life curves were obtained for tests performed at room temperature in air at a stress ratio of R = 0.1 for maximum stresses between 75%–90% of the ultimate tensile strength. The results indicated that the fatigue strength and lives of the as-processed alloys are comparable to that for Ti-6Al-4V(wt.%). Heat treatment significantly increased the orthorhombic-phase volume fractions in the alloys and resulted in reduced fatigue strength. The wear resistance for the alloys was significantly greater than that for Ti-6Al-4V(wt.%). Based on the current results, it is proposed that titanium-aluminum-niobium alloys will be of considerable future interest for biomedical applications.
Surface-Engineered Nanomaterials for Nanomedicine
Authors: Nagesha Dattatri , Amiji Mansoor M. , Sridhar Srinivas
Published: October 2008

An important feature of nanoparticles is the increased ratio of surface area to volume resulting in large percentage of the atoms on the surface, making them very reactive and offers opportunities to manipulate the properties through these surface atoms. For the most efficient use of nanoparticles in various applications, including biology and medicine, it is important to be able to manipulate the surface chemistry. This paper describes the synthesis and characterization of nanoparticles and the various surface engineering techniques that are utilized for optimizing their applications in nanomedicine.
Optimization of Phosphatidylserine-Modified Titanium Surfaces for Enhanced Osteoblast Response
Authors: Satsangi Neera , Satsangi Arpan , Ong Joo L. , Satsangi Rajiv V.
Published: October 2008

This report is part of a continued effort to evaluate the in vitro osteoblast responses on different phospholipid coatings on Titanium (Ti) implant materials. It has been established that, among analogous phopholipids, the Ti surfaces coated with calcium phosphate (CaP) complex of phosphatidylserine induce the best calcium deposition and osteoblast growth and metabolism. This communication describes an effort to optimize the chemical structure of phosphatidylserine at its position−1 and −2, as Ti surface coating relative to enhancement in osteoblast differentiation and growth in culture. Four synthetic phosphatidylserine analogs with varying fatty acyl chain length and unsaturation were converted to CaP complex, coated on Ti discs, and the osteoblast progenitor cells were cultured on them for up to 14 days to study their differentiation, growth and biochemistry as marked by the expression of alkaline phosphatase specific activity and protein production. In a separate experiment, the topography of the glass surface (glass Petri-dishes) coated the analogous phosphatidylserines, after immersion in simulated body fluid, was examined by scanning electron microscopy (SEM). The presence of calcium and phosphate ions in this deposit was also confirmed. The inclusion of unsaturation in fatty acyl chain in phosphatidylserine enhanced the Total protein production (TPP) as well as the alkaline phosphatase (ALP) specific activity.
Determination of the Convective Coefficient of Coolant by Comparing the Finite Element Model With the Experimental Results From Surface Grinding
Authors: Parthasarathy Anand , Grosse Ian R.
Published: October 2008

It is known that coolants play an important role in the grinding operation by reducing the heat that is generated on the work piece. As large amount of specific energy is spent in removing very small amount of the work piece in the finishing operations like grinding, the convective property of coolant plays a significant role in providing the required cooling effect. In today’s world, people have been customizing the coolant used for industry purposes as well as in the area of research. Thus the coolant property becomes an unknown quantity and the convection coefficient of the coolant, which dictates the quantity of heat removed from the workpiece during grinding, determines the coolant’s effectiveness. In this paper the convection coefficient of the coolant was determined for a particular velocity by computing and tuning of finite element model against experimental results. The convective property depends on various parameters such as thermal conductivity, heat capacity among others but in this paper, its dependence on velocity of the coolant is stressed. It was determined from the experimental results of surface grinding operation on workpiece and then comparing them with the finite element model simulated in ANSYS. By varying the convection coefficient parameter, the finite element model was fitted to the experimental results thus resulting in the determination of convective coefficient property of the coolant.
Integration of CAD, CAPP and Process Modeling Using XML Technologies
Authors: Khurana Pravin , Sormaz Dusan N. , Khetan Raghunath
Published: October 2008

Integration of CAD (Computer Aided Design), CAPP (Computer Aided Process Planning) and Process Modeling activities plays a vital role in enabling concurrent product and process design. Typically each of these functions is performed in its own dedicated software environment. The integration will require interfacing several disconnected processes and software components built in different languages, and platforms. This paper presents an integration methodology, validated using a case study, in which a steering housing was analyzed and its process planning and design tasks were integrated using several software tools. The first integration task was to generate a feature based CAD model (in Unigraphics) and map these design features to a set of manufacturing features. Feature based design was performed using the Horizontal Modeling™ approach developed at Delphi. Features developed using this approach were then mapped to manufacturing features using APPS, a software tool developed at Delphi Dynamics and Propulsion Innovation Center. This task involved interrogation of the geometric CAD model to generate geometric and tolerance information and represent them in a format suitable for feature-based process planning. The second task of integration is generation of feasible “production-intent” process plans. This task is performed using APPS and IMPlanner process planner, a knowledge based software tool developed at Ohio University. The third and final task of integration is automated generation of in-process CAD models. This task involved the integration of Delphi process design techniques to generate CAD models (in Unigraphics) to represent the component at each stage of the manufacturing process. Evaluation of these steps through the case study has identified the strengths and weaknesses of the proposed integration methodology, which is reported in this paper.
Optimal Part Family and Production Module Planning for Reconfigurable Manufacturing Systems
Authors: Liu Jian , Yip-Hoi Derek M. , Wang Wencai , Tang Li
Published: October 2008

Manufactures are adopting Reconfigurable Manufacturing Systems (RMS) to better cope with frequently changing market conditions, which place tremendous demands on a system’s flexibility as well as its cost-effectiveness. Considerable efforts have been devoted to the development of necessary tools for the system level design and performance improvement, resulting in approaches to designing a single RMS. In this paper, a methodology for cost-effective reconfiguration planning for multi-module-multi-product RMS’s that best reflect the market demand changes is proposed. Formulated as an optimization procedure, reconfiguration planning is defined as the best reallocation of part families to production modules in an RMS and the best rebalancing of the whole system and each individual module to achieve minimum related cost and simultaneously satisfy the market demand. A Genetic Algorithm (GA) approach is proposed to overcome the computational difficulties caused by the problem complexity. Effectiveness of the proposed methodology is demonstrated with a case study.
Explicit Yield Model (EYM) for Tolerance Synthesis of Large Scale Complex Assemblies
Authors: Huang Wenzhen , Phoomboplab T. , Ceglarek Dariusz
Published: October 2008

Tolerance synthesis for complex assemblies is formulated as a probabilistic optimization problem. A main challenge in statistical tolerance synthesis for complex assembly system design is the computation intensity in estimating the conformity probability of Key Product Characteristics (KPCs) or yield of assembled products. In assemblies with multiple KPCs, the yield can only be obtained numerically through simulation techniques such as Monte Carlo (MC) algorithm. The existing tolerance synthesis methods require a large number of yield assessments in optimization. A new approach is developed for yield model approximation based on computer experiment, multivariate distribution transformation (MDT) and regression analysis. An explicit yield function can thus be approximated. Therefore, the widely used gradient-based approaches (such as Sequential Quadratic Programming) can be applied and the intensive computation in direct optimization can be avoided. An industrial case study is presented to illustrate and validate the proposed methodology and compared with the existed tolerance synthesis methods.
Automatic Feature Extraction for Missing Part Detection in Forging Processes
Authors: Zhang Zhisheng , Tremblay Gabrielle , Jin Jionghua
Published: October 2008

In multiple operation forging processes, missing parts in some dies during production is a critical problem. The objective of this paper is to develop an effective missing part detection method through automatic classification of continuous production data. In the paper, a new feature extraction and sequential classification decision rule is developed, which aims to enhance the detection sensitivity and robustness. In the methodology development, the data segmentation is conducted at the first step based on an offline station-by-station test in a forging process. Then, PCA (Principal Component Analysis) is used as the data transform for the selected data segment of the training data sets under different missing part conditions. The effectiveness of the selected features is justified to minimize the misclassification probabilities among different classes. Finally, a decision rule is proposed for online classification of different missing parts conditions. A case study using a real-world forging process is provided to demonstrate the analysis procedures and effectiveness of the proposed methodology.
Directionally Independent Failure Prediction of End-Milling Tools During Pocketing Maneuvers
Authors: Suprock Christopher A. , Piazza Jospeh J. , Roth John T.
Published: October 2008

Tracking the health of cutting tools under typical wear conditions is advantageous to the speed and efficiency of manufacturing processes. Existing techniques monitor tool performance through analyzing force or acceleration signals whereby prognoses are made from a single sensor type. However, this work proposes to enhance the spectral output of autoregressive models by combining tri-axial accelerometer and tri-axial dynamometer signals. Through parallel processing of force and acceleration signals using single six degree of freedom modeling, greater spectral resolution is achieved. Two entirely independent methods of tracking the tool wear are developed and contrasted. First, using the discrete cosine transform, primary component analysis will be applied to the spectral output of each AR auto and cross spectrum (Method 1). Each discrete cosine transform of the 6 dimensional spectral data is analyzed to determine the magnitude of the critical (primary) variance energy component of the respective spectrum. The eigenvalues of these selected spectral energies are then observed for trends towards failure. The second method involves monitoring the eigenvalues of the spectral matrices centered at the toothpass frequency (Method 2). The results of the two methodologies are compared. Through the use of the eigenvalue method, it is shown that, for straight and pocketing maneuvers, both methods successfully track the condition of the tool using statistical thresholding.
Leveraging Data Consolidation and Event Driven Systems to Provide Predictive Diagnostics on the Factory Floor
Authors: Gala Shyam , Arora Namrata , Moyne James , Tilbury Dawn , Luntz Jon
Published: October 2008

Maintenance activities on a plant floor result in lost production and capacity, and consequently lost money. Unscheduled maintenance events are especially costly and can generate costly ripple effects in other parts of the factory up and down the supply chain. The University of Michigan - Engineering Research Center (ERC) is currently working on a project with a major automotive manufacturer, whose objective is providing a factory-wide predictive diagnostics infrastructure by deploying an open-architecture event-driven software control system. The control architecture will link equipment data collection, equipment control and equipment & tool maintenance capabilities, and will provide for coordination of resources through event driven systems to both reduce unscheduled downtime and lessen mean-time-to-repair (MTTR). The proposed solution uses data that is currently collected from the plant floor; this data, when consolidated and collectively analyzed, will be utilized to enhance the predictability of maintenance events. This approach enables the leveraging of the existing plant data collection infrastructure into the control solution architecture. The first step of the project is a historical study of the data from the different plant floor systems to identify trends leading to failures. The next project step is the implementation of an event driven control solution that utilizes the Event Condition Action (ECA) paradigm with ECA control rules housed in a relational database; this approach provides for greater flexibility and reconfigurability of the control system. A key result that is demonstrated with this solution is that effective predictive maintenance can result from focusing on data consolidation, resource coordination and flexibility, while utilizing straight-forward prediction algorithms.
Tuned Vibration Based Gear Checker for Gear Profile Anomaly Detection
Authors: Hamidieh Youssef , Jalluri Chandra , Viswanathan Mohan , Magadi Prashanth , Carter James , Duffey Robert , Salmon James , Pospisil James
Published: October 2008

Significant cost and quality metrics can be realized through the no-faults-forwards approach. This philosophy has put emphasis on early detection of defects through innovative signature analysis techniques within Powertrain Operations production lines. This paper captures the unique approach adopted on gear machining line for functionality testing of individual gears and detection of subtle gear profile anomalies leading to Noise, Vibration and Harshness (NVH) issues in fully assembled transmissions and vehicles. Gears are tested in a Vibration Based Gear Checker (VGC) in single flank engagement and operating under a torque load. The short cycle time enables feasibility for high volume measurements. The structure of Gear Checker is tuned for optimum gear profile anomaly detection**. The tuning is accomplished by structural modifications such that the Gear Checker structural natural frequencies and modes are shifted to enable a high level of excitation at harmonics of Gear Mesh Frequency (GMF) during operation. Impact testing was deployed to guide the structural adjustments for tuning. Gear checker vibration signatures for smooth and defective gears are provided; capability for detection of defective gears is demonstrated. The Gear checker frequency band vibration levels exhibit excellent correlation with the dimensional gear profile measurements by Analytical Gear Checker Coordinate Measuring Machines (CMM’s).
Results of Cylinder Bore Inspection Probe Measurements
Authors: Segall S. B. , Byers M. B. , Pasqualin J. L.
Published: October 2008

A non contact optical technique for mapping the surface finish of cylinder bores has been developed, and a probe has been built for performing this mapping by scanning the surface of a cylinder with a laser beam and recording the intensity of scattered light detected as a function of position on the cylinder surface. The probe is not a surface roughness gauge. It is used primarily to distinguish the scattering signatures from different patterns of machining marks. For identical patterns of machining marks scattered light intensity is expected to be proportional to surface roughness. Measurement of a cylinder takes about 10 seconds using this probe. If an array of probes were used to inspect the cylinders of an engine block simultaneously, this technique could be used for 100% inspection of the entire surface of every cylinder of every block at the speed of an engine production line. In this paper we present data from a proof of concept experiment, describe the method of analyzing the data, and outline plans for future implementation of an inspection station on an engine block production line.
Real Time Curve Extrapolator for Fixtureless Inspection of Freeform Surfaces
Authors: Steiner D.
Published: October 2008

The inspection of free-form surfaces is an important task in manufacturing process control. This task motivated researchers to develop methodologies and technologies for fixtureless inspection. The motivation for performing fixtureless inspection rises from the fact that a datum or an exact fixture is not always available for free-form objects. When datum and fixtures are not present, the location and rotation of the object in space relative to the sensor coordinate system are unknown. Thus, scanning along a proper trajectory is not trivial especially when dealing with high precision sensors with small depth of field (DOF). In this paper we introduce a theoretical scheme for real time curve extrapolation. This scheme performs real time automatic adjustment to the sensor depth of field by smoothly changing the position of the sensor. The proposed scheme can handle local C1 discontinuity (C0 continuity). In the proposed scheme, the velocity of the motion stages can be controlled by the curvature of the extrapolated curve, thus controlling the density of the sampled data. Also, no knowledge of the surface orientation and location is needed nor any reference plane or other datum. The scheme was tested using computer simulation that was developed for this purpose. The robustness of the scheme is shown at the end of this paper through simulation results using high order polynomial surfaces as test cases.
Investigating Machining Impact on Fatigue Variance: A Machining Quality Perspective
Authors: Yang Xiaoping , Liu C. Richard
Published: October 2008

Fatigue life of nominally identical structures under nominally identical loading conditions can scatter widely. This study has investigated the impact of machining processes on such scatters. After Ti 6Al-4V samples were surface ground and face turned, they were subject to constant amplitude four-point bending fatigue tests under room temperature. The best case scenario of process capability ratios of fatigue for these samples were evaluated with assumed tolerances of fatigue life. Based on these ratios, the numbers of nonconforming parts were estimated. Under the machining conditions from a handbook, up to 39% of samples due to one process are expected to be nonconforming while only up to 0.6% of samples due to the other process are expected to be nonconforming. The ramifications in terms of cost for machining quality control due to the different capability ratios have been discussed. The current findings indicate an urgent need to further the study of this issue in a scientific manner.
Fabrication and Application of Micro Sensor Arrays on Nickel Substrate for Meso-Scale Manufacturing Processes
Authors: Cheng Xudong , Li Xiaochun
Published: October 2008

Real time monitoring, diagnosis and control of numerous manufacturing processes is of critical importance in reducing operation costs, improving product quality, and shortening response time. Current sensors used in manufacturing, especially at meso/micro scale, are normally unable to provide measurements with desired spatial and temporal resolution at critical locations in metal structures (e.g. tooling). Micro sensors are expected to offer tremendous benefits for real time sensing in manufacturing processes. In this study, a batch production of micro thin film sensor arrays was realized by transferring thin film sensors from silicon wafers directly onto nickel substrates through standard microfabrication and electroplating techniques. To demonstrate the potential applications, micro sensor arrays that consist of multiple thermocouples and thermopiles were designed, fabricated and transferred into electroplated nickel to study temperature field and heat generation during meso-scale ultrasonic welding. Sensor arrays are arranged immediately adjacent to the mesoscale welding area for in-situ temperature and surface heat flux measurement. These micro sensor arrays provide high spatial and temporal resolution that cannot be achieved with conventional macro sensors.
Transient Surface Temperature Measurement With Micro Sensors for Nanosecond Pulsed Laser Micromachining of Nickel
Authors: Choi Hongseok , Li Xiaochun
Published: October 2008

In order to investigate and understand the complicated transient thermal phenomena in laser micro processing, it is essential to accurately measure time-resolved temperatures of the workpiece. Micro thin film thermocouples with a micrometer spatial and nanosecond temporal resolution were fabricated on electroplated nickel workpieces to measure transient surface temperatures in nanosecond pulsed laser micromachining by ablation. Transient temperatures were successfully measured, and the effect of laser energy fluences on the peak temperatures was experimentally investigated. This study demonstrates that the micro TFTCs can be useful in measuring the transient temperatures on the workpiece during laser micromachining, and the measured data can be utilized to validate and improve existing analytical and numerical models.
Sensor Fusion for Industrial Applications Using Transducer Markup Language
Authors: Yoder Valerie J. , Havens Steven W. , Na Arthur J. , Weingrad Rachel E.
Published: October 2008

Manufacturing processes would greatly benefit from fusing data from many disparate sensors, but systems today do not fully exploit available sensor data. Disparate sensors could include Coordinate Measurement Machines (CMM), laser surface scanners, micro sensors, cameras, acoustic devices, thermocouples, or other various devices which provide measurement or visual data. Often, sensor data requires separate customized software for each type of sensor system, as opposed to having common tools for use across a wide array of sensor systems. This process of stove-piping requires proprietary software for analysis and display of each sensor type, and inhibits interoperability. There are several challenges to sensor fusion which need to be addressed. First, many sensors providing data are heterogeneous in phenomena detection and operation, providing measurements of different target attributes. This makes the measurements very difficult to fuse directly. Second, these disparate sensors are asynchronous in time. The collection, integration, buffering and transmitting time can each affect the way time is calculated and stored by the sensor. Transducer Markup Language (TML), developed by IRIS Corporation, addresses these challenges. This paper describes TML and addresses examples of industrial applications of TML-enabled transducer networks.
State-of-the-Art Review of Micro Ultrasonic Machining
Authors: Hu X. , Yu Z. , Rajurkar K. P.
Published: October 2008

In ultrasonic machining (USM), hard and brittle material is removed by the hammering of abrasive particles excited by ultrasonic vibration delivered to the tool. USM does not significantly alter metallurgical, chemical, or physical properties of work material because of its non-thermal, non-chemical and non-electrical nature. USM has been downscaled to generate micro-scale features in brittle and hard materials such as silicon, quartz, glass and ceramics. Micro holes, slots and 3-D features have been machined. However, the knowledge base for micro USM is far from sufficient to provide instructive rules in applying micro USM to practical manufacturing. This paper presents a systematic literature review and reports the state-of-the-art investigation in micro USM based on previous experimental and theoretical results. Research issues are identified for further improvement of this special micromachining process.
An Acoustic Emission-Based Method for Determining Relative Orientation Between a Tool and Workpiece at the Micro-Scale
Authors: Bourne Keith A. , Jun Martin B. G. , Kapoor Shiv G. , DeVor Richard E.
Published: October 2008

An acoustic emission-based touch-off detection system has been developed to determine the relative orientation between a rotating micro-tool and a workpiece surface with micron-level accuracy. The system has been implemented on an existing 3-axis micro-scale machine tool (mMT). The system has been tested with micro-endmills as small as 50 μm in diameter and micro-drills as small as 254 μm in diameter. The accuracy of the system has been found to depend on tool geometry and workpiece surface characteristics and is generally on the order of one micron. An analytical model has been constructed to predict touch-off detection error. The calibrated model has been shown to predict surface overshoot and undershoot trends quite well. Simulations have shown that touch-off error is dominated by part surface roughness.
Numerical and Experimental Investigation of Micromelting for Laser Micro Polishing of Meso/Micro Metallic Components
Authors: Qu Yi , Choi Hongseok , Perry Tyler , Jeon Yongho , Pfefferkorn Frank , Li Xiaochun , Duffie Neil
Published: October 2008

The relative accuracy (accuracy/overall dimension) of meso/micro parts (e.g. dies/molds) generally is far worse than that of macro parts fabricated by conventional manufacturing processes. Meso/micro parts have unique tribology issues, and surface roughness strongly impacts their relative accuracy and performance. There is a high demand for effective polishing of complex shapes in meso/micro engineering. A laser micro polishing method based on rapid surface micro melting is described in this paper. Fundamental understanding of pulse laser micro melting is achieved through a combination of studies of analytical modeling, numerical simulation and experimentation. It is found that a power limit window exists for laser polishing. In the experimental study, a Nd:YAG laser with a wavelength of 355 nm and a pulse of 10 ns is used to polish patterned electroplated nickel surfaces. The experiments show an improvement of surface roughness with repetitive rapid micro melting. These preliminary results show improved surface roughness can be achieved and that laser micro polishing is a viable methodology for automated polishing of 3-D meso/micro complex surfaces of metallic parts.
Chatter Stability Analysis Using the Matrix Lambert Function and Bifurcation Analysis
Authors: Yi Sun , Nelson Patrick W. , Ulsoy A. Galip
Published: October 2008

We investigate the stability of the regenerative machine tool chatter problem, in a turning process modeled using delay differential equations (DDEs). An approach using the matrix Lambert function for the analytical solution to systems to delay differential equations is applied to this problem and compared with the result obtained using a bifurcation analysis. The Lambert function, known to be useful for solving scalar first order DDEs, has recently been extended to a matrix Lambert function approach to solve systems of DDEs. The essential advantage of the matrix Lambert approach is not only the similarity to the concept of the state transition matrix in linear ordinary differential equations, enabling its use for general classes of linear delay differential equations, but also the observation that we need only the principal branch among an infinite number of roots to determine the stability of a system of DDEs. The bifurcation method combined with Sturm sequences provides an algorithm for determining the stability of DDEs without restrictive geometric analysis. With this approach, one can obtain the critical values of delay which determine the stability of a system and hence the preferred operating spindle speed without chatter. We apply both the matrix Lambert function and the bifurcation analysis approach to the problem of chatter stability in turning, and compare the results obtained to existing methods. The two new approaches show excellent accuracy, and certain other advantages, when compared to traditional graphical, computational and approximate methods.
Tool Runout Estimation Using Feed Force Spectral Components
Authors: Jacobson Douglas , Fussell Barry , Jerard Robert
Published: October 2008

Cutter Runout is the eccentricity caused by a combination of imperfections in the cutting tool, tool holder, and spindle. While magnitudes of cutter runout are generally small (e.g 10 μm), the effect is noticeable in high tolerance finishing operations, and can cause significant variations in the force experienced on a multi tooth cutter. The goal of this research is to design and evaluate an indirect runout estimation method, using feed force components at the spindle and tooth passing frequency. The accuracy of the method is evaluated for a range of cutting conditions for 4 and 6 tooth helical flat end mills. The standard error of the runout estimation method for 27 test cases was determined to be 7.1 μm. The error was skewed by several data points from a 6 tooth cutter. Additional testing is needed with 2, 3 and 5 tooth cutters.
Control of the Error Induced by Cutting Force in NC Milling Machine
Authors: Gelvis Turyagyenda , Yang Jian Guo , Wu Hao
Published: October 2008

This paper presents a real-time compensation system for cutting force induced error on CNC miller. Induced errors in form of deformations for individual joints of the transmission system are identified and monitored. A force dynamometer is calibrated in reference to displacement sensors to acts as an online sensor. The Relationships between superimposed forces and corresponding deformations are established. Hence able to indirectly predict the deformations in accordance with the system embedded model. Sequentially is established by duly applying regression analysis to force-displacement data obtained from the experiments. The functional dependence of error on the on the force as prerequisite of appropriation for its relationship with cutting force is modeled. The implementation of the error compensation is done through a predetermined kinematic model that predicts the error according to the online sensor value. Finally relevant error components are disregarded by intercepting the control signal with a reverse signal equivalent to the error.
Clustering Methods for Defect Tracking in Order to Assess the Performance of a Porosity Inspection System
Authors: Rubin Rachel N. , Spicer J. Patrick , Katz Reuven R.
Published: October 2008

Surface porosity inspection is important for quality assurance of critical mating surfaces on machined components. An important metric for assessing the performance of an automated surface porosity inspection system is repeatability. Traditional gage repeatability analysis is well defined for dimensional measurements of machined part features. However, the analysis becomes more difficult for surface porosity inspection. This is because surface porosity appears in random sizes and in random locations. Repeatability analysis requires painstaking effort in tracking individual pores through repeated measurements. Therefore, this paper presents an automated approach for tracking porosity for the purpose of repeatability analysis. Two different algorithms are proposed and evaluated. The first is a tolerance based method that uses pre-specified tolerances to determine if pores should be grouped together. The second algorithm is similar to hierarchical agglomerative clustering, using a similarity matrix to store differences between cluster centroids. However, this algorithm uses a training period to determine when to stop clustering instead of continuing until all pores are in one cluster. Experimental results describe differences in the accuracy of both approaches and effort required to obtain a solution. The computation time required for the first method is much shorter than that of the second method. However, the first algorithm requires a-priori information to specify the tolerances, whereas the second algorithm requires no prior knowledge.
A Look Into the Pinellas County Florida Waste-to-Energy Facility: Host Tour Site
Authors: Hauser Robert , Smith Warren N.
Published: October 2008

Pinellas County Utilities – Solid Waste Operations was formed in the mid-seventies as a partnership between Pinellas County and the 24 cities within the county. Under this partnership, the County took responsibility for the management and disposal of all solid waste generated within Pinellas County.
Applying Lessons Learned From Waste-to-Energy Feasibility Study Projections to Contract Renewals, Expansions and New Projects
Authors: Bilmes Jonathan S. , Hemenway Susan F.
Published: October 2008

A majority of today’s operating waste to energy plants were developed in the 1980s. In order to finance these facilities, comprehensive feasibility reports were required that assessed the engineering and financial feasibility of the projects. The Bristol Resource Facility Operating Committee (BRRFOC) commissioned two such reports; in 1985 when the project was initially financed and again in 1993 when the initial bonds were refunded. Key assumptions were made in the 1985 and 1993 reports regarding energy prices, landfill costs, inflation, member tonnage, recycling rates, changes in law and plant operations. Despite the enormous changes that have occurred in the waste to energy industry over the past 20 years, BRRFOC’s member community tipping fee has consistently outperformed projections. In fact, due to BRRFOC’s financial track record, a 2005 refinancing was successfully marketed to financial institutions without an independent economic study. This paper will compare and contrast the 1985 and 1993 projections and assumptions to actual performance. The information provided will assist decision makers contemplating contract renewals, expansions or new waste to energy projects determine what sensitivity analyses, if any, need to be included in the feasibility report.
Maximizing Energy Revenues: Providing the Best Incentive to the Contract Operator
Authors: LoRe Anthony , Stoller Paul , Hauser Robert
Published: October 2008

Communities that own waste-to-energy (WTE) facilities rely heavily on the revenues generated by their facility to help pay for the costs to finance, operate and maintain these facilities. The two primary revenue streams are tipping fees and energy sales, generally in the form of electricity. While communities often retain all of the tipping fee revenue, revenue from the sale of energy is nearly always shared with the contract operator. In some cases the shared energy revenues include both capacity and electricity payments. The basis of this strategy is to offer the contract operator an added incentive to maximize this revenue stream through more efficient operation and, in the case of capacity payments, to meet certain capacity commitment criteria required by the energy purchaser. This strategy recognizes that the contract operator has some degree of control over the factors that affect energy production. Under most existing service agreements, which date back to the 1980s, energy revenues are shared on a 90/10 basis, with 90 percent going to the community. Now that many of these service agreements are coming up for renewal or are expiring, communities will need to revisit how best to share energy revenues with the contract operator in order to maximize the total revenues retained by the community. This paper analyzes several different approaches to sharing energy revenues in light of the operational experience gained over the past 20 plus years and concludes that, while energy revenue sharing is still in the best interest of the community, the widely employed strategy of a 90/10 split may not offer the best incentive, and therefore may not lead to the maximization of energy revenues to the community.
Application of Dry Chemical Stabilization Technology in Taiwan Kobin Bottom Ash Processing and Recycle Plant
Authors: Shih Chien-Jen , Forrester Keith E. , Fan Wen-Bin
Published: October 2008

The Taiwan Kobin Bottom Ash Processing & Recycle Plant (Kobin-BAPRP) processes approximately one quarter million metric tons of bottom ashes from several municipal solid wastes the incinerators annually, generating fine aggregate finished products and ferrous recovery. The results from USEPA Method 1311 Toxicity Characteristic Leaching Procedure (TCLP) for un-treated bottom ash indicate that about 5% of the time that lead and less than 0.5% of the time, copper or cadmium may fail to meet leaching standards (i.e. 5 mg/L for Pb, 15 mg/L for Cu, and 1 mg/L for Cd ). Previously, Kobin applied phosphoric acid solution for stabilization, which caused strong odor problem, increased moisture content, and still about 1% of the time that TCLP-Pb failed to pass the standard, hence, required reprocessing. Recently, Kobin-BAPRP has switched its stabilization agent from the phosphoric acid solution to dry chemical dosage. In addition to having a better stabilized byproduct, the use of dry chemical further ensures worker safety. Dry chemical is water insoluble and fine calcium phosphate particles, with different combinations of buffers and complexing agents, such as Fe+2, Fe+3, Al+3, or chloride. It took about 8 months for laboratory tests and plant trials to identify the optimum dosage as well as the best mixing point. Long term operation has demonstrated that dry chemical spread and mixing is safe to communities and workers, non-reactive with storage and handling materials, generates no toxic gases or odor, and most importantly, provides for effective and consistent Pb stabilization. The final stable family of mineral crystals includes complexed hydroxyapatite and chlorapatite minerals.
Problem Solving Tools in Waste-to-Energy Systems
Authors: White Mark , Epelbaum Greg
Published: October 2008

Covanta is using a multifaceted approach to problem solving in Waste-to-Energy systems which combines several types of computer modeling with physical cold flow models, field testing, and engineering experience. This problem-solving approach is applied to boiler corrosion, gas and particulate flow patterns, reagent injection, and APC system issues. Our goals are to bring the most appropriate tools to each issue and incorporate results back into the engineering approach in order to continually improve our technical capabilities. Several types of computer modeling are used. A commercially available energy balance program is used for steam cycle evaluations and boiler energy balance and heat transfer calculations. Computational Fluid Dynamics (CFD) models are developed to investigate temperature and flow patterns where local conditions must be understood in detail. We have made extensive use of cold flow models to improve performance of APC systems, and to evaluate overfire air mixing in furnaces, and flow distribution through tube banks in boilers. Field testing is used to investigate temperature fluctuations and distributions, flow stratification, corrosion rates, and to validate modeling or analytical results. Each of these approaches has its own set of advantages, disadvantages, and limitations, and must always be combined with a healthy dose of operating and engineering experience. Analytical work is done by, or in close cooperation with, our operations and engineering staff with many years of experience operating, designing, and modifying boilers, APC systems, and related equipment. This integrated approach has yielded significant improvements in many cases and is being used in increasingly complex applications.
Pulse Combustion Technology
Authors: Plavnik Gene
Published: October 2008

Pulse combustion has been used in a variety of ways since first being discovered in 1877. This a combustion process that occurs under oscillatory conditions with changing state variables, such as pressure, temperature and velocity. This paper looks at the historic uses of pulse combustion, and it provides an overview of this unique process. Pulse combustion has been used to amplify thrust power with the German V-1 rockets. Pulse combustion has been used to optimize flame efficiencies, and it is now reemerging in many new industrial applications including some for Waste to Energy.
Combating Corrosion in WTE Facilities: Theory and Experience
Authors: Lee Shang-Hsiu , Themelis Nickolas J. , Castaldi Marco J.
Published: October 2008

In boilers that use municipal solid wastes as fuel, metal wastage due to corrosion and erosion and tube fouling due to the buildup of deposits present serious problems to the system designer and operator. This study examines the corrosion mechanisms in Waste-To-Energy (WTE) boilers and summarizes the findings of a corrosion survey of several WTE facilities and of interviews with senior engineers in the WTE industry. In addition, this study examines the existing methods of reducing corrosion that are adopted in WTE plants. Finally, the study proposes experimental research on corrosion resistant materials to be carried in the near future.
A Comparison of Ice Loads From Level Ice and Ice Ridges on Sloping Offshore Structures Calculated in Accordance With Different International and National Standards
Authors: Bruun Per Kristian , Gudmestad Ove Tobias
Published: October 2008

Existing national and international standards for determination of level ice and ice ridge loads on sloping offshore structures recommend different methods for the analysis. The objective of this paper is to review the codes and standards recommendations regarding ice-sloping structures interaction process and highlight the differences between them. Development of offshore hydrocarbon fields in the Eastern Barents Sea is foreseen to take place in the near future while developments already take place in the Pechora Sea and offshore Sakhalin as well as in the Northern Caspian Sea. One of the most difficult issues facing the designer of offshore structures for these areas is how to design for loads from level ice and ice ridges. The ice load considerations will have a major effect on the form and cost of these structures. It is known that different designers use very different ice load estimates (Shkhinek et al., 1994). The standards recommend different methods for determination of the global ice loads on both cone-shaped and sloping rectangular structures. For determination of the global ice loads on these types of structures, it is obvious that the ice-structure interaction process must be identified. Rubble effects must be included in the analysis. The ice-structure interaction process for these geometries depends on many factors, such as; the ice thickness, ice strength, ice-structure friction coefficient, ice velocity, width of the structure and slope angle of the structure. The methods for determination of ice loads recommended by the different standards are very much influenced by local ice conditions and the parameters listed above are given different importance in the different standards. The differences in loads calculated by using the different standards and their validity for the ice-structure interaction process have been investigated and example calculations are presented to show these differences. It is thought that the paper may be of interest for those preparing the new ISO standard (ISO 19906) on Arctic Offshore Structures.
Numerical Simulation of Non-Gaussian Wave Elevation and Kinematics Based on Two-Dimensional Fourier Transform
Authors: Zheng Xiang Yuan , Moan Torgeir , Quek Ser Tong
Published: October 2008

The one-dimensional Fast Fourier Transform (FFT) has been extensively applied to efficiently simulate Gaussian wave elevation and water particle kinematics. The actual sea elevation/kinematics exhibit non-Gaussianities that mathematically can be represented by the second-order random wave theory. The elevation/kinematics formulation contains double-summation frequency sum and difference terms which in computation make the dynamic analysis of offshore structural response prohibitive. This study aims at a direct and efficient two-dimensional FFT algorithm for simulating the frequency sum terms. For the frequency difference terms, inverse FFT and FFT are respectively implemented across the two dimensions of the wave interaction matrix. Given specified wave conditions, not only the wave elevation but kinematics and associated Morison force are simulated. Favorable agreements are achieved when the statistics of elevation/kinematics are compared with not only the empirical fits but the analytical solutions developed based on modified eigenvalue/eigenvector approach, while the computation effort is very limited. In addition, the stochastic analyses in both time-and frequency domains show that the near-surface Morison force and induced linear oscillator response exhibits stronger non-Gaussianities by involving the second-order wave effects.
Creep Analysis for an Unbonded Flexible Pipe Barrier
Authors: Qiu Lun , Zhang John
Published: October 2008

The fluid barrier in an unbonded flexible pipe seals the pressure from the internal fluid. Since the barrier is usually made of polymer materials, it is unable to hold the pressure by itself. A metal reinforced hoop layer is usually needed outside the barrier layer in order to resist the pressure. The hoop layer is usually a steel bar with a cross-section of an irregular shape. It is helically wrapped at the outside of the barrier layer. When the pipe is pressurized, the barrier will be supported by the hoop reinforcement layer from outside. However, at the gap between the steel wraps where the barrier layer bridges, material of the barrier will be forced to extrude into the gap. The amount of the extrusion is a function of many parameters such as temperature, material property, and internal pressure and so on. In addition, it is time dependent. The creep effect needs be considered. It is critical to have a proper barrier design for a flexible pipe structure. This article presents a practical finite element method for evaluation of the barrier/gap design. The creep behavior of the polymers is multi-parameter related. Therefore, a series of material tests has been conducted under various stresses and temperatures for nylon, polyethylene and Polyvinylidene Fluoride. In this work a method is given to determine the creep behavior parameters through parameter matching based on the tests. The creep deformation of barrier was analyzed with a finite element model using these parameters.