bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Pressure Welding Process of Thin Sheet Metals in Cold and Warm Temperature Conditions
Authors: Mahabunphachai Sasawat , Koc¸ Muammer , Ni Jun
Published: March 2009

The effects of material and process conditions in the pressure welding process of thin sheet metals on the minimum welding pressure and the final bond strength are investigated in this work. The studied parameters include the material type (copper, aluminum, nickel, and stainless steel), initial blank thickness (0.051–0.254 mm), welding pressure, welding temperature (25–300°C), surface condition (wet, dry, and brushed), and indenter size. Two sets of pressure welding apparatus were developed for testing of different materials and process conditions. Based on the experimental results, copper, aluminum, and nickel blanks were successfully bonded at room temperature (“cold welding”), while stainless steel blanks could only be joined at elevated temperature levels (150 and 300°C). The material type (i.e. strength) and thickness were shown to have significant impact on the welding pressure; in that more pressure is required to bond the blanks with higher strength or thinner. To reduce the required welding pressure, the process can either be carried out at elevated temperature levels or by scratch brushing the surfaces to be joined. In this study, the bond strength of the welded blanks was measured using tensile testing. The tensile test results showed that the bond strength could be increased by either scratch brushing the surfaces or by increasing the welding pressure or temperature. However, the increase in bond strength by increasing welding pressure was shown to have an optimal point, after which the bond strength would decrease with further increase in pressure. This critical pressure value appeared to be dependent on the material and process conditions. The width of the straight line indenter showed no significant impact on the minimum welding pressure. Finally, the bond formation mechanisms for different materials were studied through microscopic analyses. The microscopy images of the weld spots showed that for the bonding to take place, the contaminant layers at the surfaces must be removed or broken to allow the virgin metal underneath to be extruded through. The metallic bonds only form at these locations where both surfaces are free of contaminant layers.
Development of Three-Dimensional Alginate Encapsulated Chondrocyte Hybrid Scaffolds Using Microstereolithography
Authors: Lee Seung-Jae , Kim Byung , Lim Geunbae , Rhie Jong-Won , Kang Hyun-Wook , Cho Dong-Woo
Published: March 2009

Hydrogels are useful materials because of their chemical similarity to extracellular matrix and their ability to rapidly diffuse hydrophilic nutrients and metabolites. Using rapid prototyping (RP) methods, we fabricated freeform three-dimensional (3-D) scaffolds with chondrocytes encapsulated in an alginate hydrogel. The 3-D hybrid scaffold was developed as combination of two components, a TMC/TMP framework and an alginate hydrogel within an encapsulation of chondrocytes. To develop 3-D hybrid scaffolds, we employed a microstereolithography system. The biodegradable, photo-polymerizable liquid prepolymer was prepared by the polymerization of trimethylene carbonate (TMC) with trimethylolpropane (TMP), and subsequently end-capped with an acrylate group. The meshed framework of scaffolds withstood mechanical loading effectively. The line depth and line width could be controlled by varying laser power, scan path, and scan speed. Results of cell culture indicate that the biomimetic nature of these encapsulated chondrocyte scaffolds effectively retain the phenotypic function of chondrocytes within the scaffold structure. The proposed 3-D hybrid scaffolds can be used for cartilage regeneration.
Some Investigations Into Multi-Objective Optimization of Wire Electro-Discharge Machining of Al/SiCp Composites
Authors: Patil N. G. , Brahmankar P. K. , Navale L. G.
Published: March 2009

Non-traditional process like wire electro-discharge machining (WEDM) is found to show a promise for machining metal matrix composites (MMCs). However, the machining information for the difficult-to-machine particle-reinforced material is inadequate. This paper is focused on experimental investigation to examine the effect of electrical as well as non-electrical machining parameters on performance in wire electro-discharge machining of metal matrix composites (Al/SiCp). Taguchi orthogonal arrays were employed to study the effects of combinations of voltage, current, pulse on-time, off-time, and wire speed and wire tension on kerf width and cutting speed. Voltage, current, and on-time were found to have significant effect on cutting speed and kerf width. The optimum machining parameter combinations were obtained for cutting speed and kerf width separately. Further, multi-objective optimization was done using Taguchi-Grey relational analysis. The process has been improved with the aid of Grey relational analysis and Taguchi orthogonal array. The results have been verified with confirmation experiments.
Design and Implementation of a High Bandwidth Servo Controller for Micro-Machining Center
Authors: Ko Roy Chih-Lung , Liu Wang-Lin
Published: March 2009

To achieve the required performance of a Micro Machining Center, the control system must issue position commands with nanometer resolution, while holding the axis position with oscillations down to sub-micron level. The requirements call for a highly flexible CNC platform with unconventionally high-bandwidth servo controller. In this paper, we present a system-wide design based on an open CNC architecture with integrated digital servo drives. The proposed design incorporates customization of the digital protocol between CNC and drives, ultra-fine interpolation of the encoder signal, and novel approaches to increase the servo-loop bandwidth. A three-axis Micro Machining Center was successfully built with the proposed design, which was then proven to meet the stringent requirements with extensive dry-run and cutting experiments.
The Use of Internal State Variable Plasticity Model via a User Subroutine to Evaluate the Effect of Materials Testing Modes on Hard Machining Simulation
Authors: Anurag S. , Guo Y. B. , Horstemeyer M. F.
Published: March 2009

Hard machining involves large strain, high strain rate, high temperatures, strain rate/temperature coupling, and potential loading history effects. The accuracy of characterizing the dynamic mechanical behavior in hard machining using any constitutive models is strongly affected by materials testing data in which a constitutive model is fitted. Tension or compression tests have been widely used to approximate material properties in various manufacturing processes. However, it has been a critical question whether tension or compression test should be utilized for capturing the true nature of material deformations in a hard machining process. In this study, the influences of two material testing modes on mechanical behavior of AISI52100 steel (62 HRc) were investigated using the internal state variable (ISV) plasticity model. Twenty material constants have been found by nonlinear fitting the ISV plasticity model to the base line test data obtained from each deformation mode. To understand the true nature of hard turning mechanics, a numerical model that incorporate the internal state variable plasticity model via a material user subroutine has been developed with the material constants from the compression and tension tests. A global material failure/damage evolution model was implemented to simulate chip formation which solely depends on the material deformation state. Orthogonal hard turning experiments have been performed to validate the numerical model. It has shown that the material testing modes have profound effects on some materials constants of the ISV model. The stress sensitivity study to ISV model parameters has identified the critical material constants for reflecting the nature of material deformation. The different testing modes have significant influence on the material constants associated with isotropic hardening rather than kinematic hardening. The numerical and experimental results have shown that the material constants from the compression test capture the true nature of a hard machining process. The compression mode of material deformation prevails in hard machining.
A New Method for Feature Selection and Gear Defect Detection
Authors: Chen Yan , Wang Haixia , Lee Jay
Published: March 2009

This paper presents a new method for gear defect detection. Firstly, the feature subset that describes a gear health state is generated, followed by two sub-steps: (I) features that are robust to data noise are extracted from the collected data utilizing the information-theoretical concept of entropy; (II) the optimal feature subset for gear defect detection is selected using a wrapper approach. Secondly, patterns of the feature subsets that describe the most current gear health states are grouped into a health-map, using the self-organizing map (SOM) method. This health-map shows a clear clustering of healthy and faulty gears, and can be used as a reference for future gear health evaluation. An industrial case study is presented that shows the effectiveness of the presented method.
Monitoring and Model Generation for Intelligent Optimization and Control of Surface Grinding Processes
Authors: Pavel Radu , Srivastava Anil
Published: March 2009

The grinding process involves more variables than most of the other machining processes. In the past, grinding process has been viewed as an art more than an exact science. This paper presents a monitoring and model generation strategy developed to allow science-based optimization and control of the grinding process. The monitoring solution involves simultaneous acquisition of power, forces, acoustic emission and vibration data generated during surface grinding. A custom build data acquisition program helps capture the information and visualize the process condition. Dressing consistency and spindle condition are monitored through the same system. Part of the data is processed off-line to determine coefficient values for generalized equations that model main monitored parameters. An optimization relative to cycle time or cost can be conducted based on the results gathered for each combination of grinding wheel, workpiece material and metalworking fluid. The procedure requires a minimal number of experimental runs to determine the model coefficients. The solution opens the path towards the development of a model-based condition monitoring system with adaptive control.
Assembly Faults Diagnosis Using Neural Networks and Process Knowledge
Authors: Zhao Qiangsheng , Camelio Jaime
Published: March 2009

Traditional manufacturing process fault monitoring and detection methodologies have been based on Statistical Process Control (SPC) charts and rules. In most cases, SPC is used to detect a fault or an out-of-control condition while fault diagnosis relies on operator expertise to identify the potential root causes. Current sensor developments allow for the acquisition of large amounts of data from parts and processes in a manufacturing environment. In addition, new modeling tools have increased the efficiency and accuracy of process modeling, providing useful knowledge about product-processes interaction. This paper presents a new methodology for fault diagnosis using a Feed Forward Back-Propagation Neural Network. The proposed neural network is trained using process knowledge and then applied to the detection of manufacturing process faults. The methodology results in a modified control chart that uses measurement data from the assembly components and plots an indicator representing the presence or absence of a predefined fault. Two case studies are presented: a diagnosis system for fixture faults in a generic assembly process, and a diagnosis tool for fault detection and identification in an automobile door assembly.
A Review on Thermally Assisted Machining
Authors: Lei Shuting , Pfefferkorn Frank
Published: March 2009

Thermally assisted machining (TAM) involves the use of a heating source to elevate the workpiece temperature at the cutting zone to facilitate the material removal process. TAM has evolved over the years with the emergence of new heating sources and the need to machine newly developed hard and brittle materials. In recent years, the main activities in this research area have been focused on laser assisted machining (LAM) at both the macro and micro scale, largely because of focused and controlled delivery of energy that can be achieved with a laser. This paper attempts to provide an overview of research in the general area of TAM, with an emphasis on LAM at the macro scale. Both experimental and theoretical/numerical work will be presented in this review. The challenges and progresses made so far will be detailed. And finally, future research directions in this area will be discussed.
Comparison of Mixing Approaches in the Synthesis and Deposition of Ceria Nanoparticles
Authors: Tseng Chih Heng T. , Paul Brian K.
Published: March 2009

Nanoparticle deposition techniques hold the promise of simplifying thin film deposition while enabling enhanced performance through the control of film density, porosity and composition. In this paper, ceria nanoparticles are deposited from solution to a film via spin coating. A comparison is made between the nanoparticle shape and film morphology produced by depositing from different mixing approaches. In this paper, different mixing approaches were carried out by using traditional batch precipitation reactor and continuous microchannel reactor (T-mixer). Preliminary results show different particle shape and film morphology as a function of precursor concentration. Advantages of the microchannel approach include better control of nanoparticle shape and more uniform film with less agglomeration.
Characterization and Investigation of Deformation During Microextrusion Using X-Ray Texture Analyses
Authors: Parasız Sunal Ahmet , Kinsey Brad L. , Krishnan Neil , Cao Jian
Published: March 2009

In microforming scaling down the size of the process while the grain size is kept relatively constant usually results in inhomogeneous deformation. In most works, the inhomogeneous deformation of miniaturized samples is presented and evaluated by microstructure analyses of the deformed grains. However, in certain microforming processes, such as microextrusion, where the final texture of the conventional macro size samples is well known, texture analyses can provide useful information about the deformation. In our past research, extrusion experiments were performed to produce sub-millimeter sized pins having a base diameter of 0.76 mm and an extruded diameter of 0.57 mm. Curvature of differing degrees and directions was observed in workpieces with a coarse grain size of 211 μm. However, a similar effect did not occur in workpieces with a fine grain size of 32 μm. Microstructure analyses showed that when the sample size approaches the grain size, the deformation becomes inhomogeneous and the properties of individual grains can dominate the overall deformation of their cross-sections. Moreover, microhardness measurements revealed that deformation size effects are present and as a result the coarse grained pins strain hardened more than the fine grained pins during microextrusion. This result along with microstructure analyses suggested that the coarse grains in the central region possibly undergo more shear deformation. In this paper, X-ray texture analyses of the pins were performed to validate that there is penetration of shear deformation into the central regions of the coarse grained pins. Also, the texture analyses point to the possibility that the deformation in the curved region of the coarse grained pins is not axially symmetric which causes the curvature observed.
Fault Localization Analysis for Multiple Fault Diagnosis in Multi-Station Assembly Systems
Authors: Tsai Posheng , Mannar Kamal , Ceglarek Darek
Published: March 2009

Modern large scale multi-station manufacturing systems require effective variation reduction to improve the final assembly dimensional quality. One critical measure is to diagnose the fault in the process using knowledge-based root cause identification, which can be very challenging due to the complexity of the system. The paper investigates the need of data-driven fault localization to enhance the diagnosability within the context of multiple-fault scenario(s) in multi-station assembly processes where multivariate measurements are used. The paper proposes three types of fault-signal transmission in assembly system and illustrates the nature of structured noise. Moreover, the impact of structured noise on the diagnosability is illustrated on two major fault isolation methods, namely, Principal Component Analysis and Independent Component Analysis. We then propose to use data-driven fault localization to reduce the structured noise effect and enhance the diagnosability. A simulation case study based on automotive panel assembly model is provided to illustrate the impact of structured noise and the need for data-driven localization.
Thermal-Electric Finite Element Analysis of Electrosurgical Cautery Process
Authors: Dodde Robert E. , Miller Scott F. , Shih Albert J. , Geiger James D.
Published: March 2009

Cautery is a process to coagulate tissues and seal blood vessels using the heat. In this study, finite element modeling (FEM) was performed to analyze temperature distribution in biological tissue subject to cautery electrosurgical technique. FEM can provide detailed insight into the heat transfer in biological tissue to reduce the collateral thermal damage and improve the safety of cautery surgical procedure. A coupled thermal-electric FEM module was applied with temperature-dependent electrical and thermal properties for the tissue. Tissue temperature was measured at different locations during the electrosurgical experiments and compared to FEM results with good agreement. The temperature-dependent electrical conductivity has demonstrated to be critical. In comparison, the temperature-dependent thermal conductivity does not impact heat transfer as much as the electrical conductivity. FEM results show that the thermal effects can be varied with the electrode geometry that focuses the current density at the midline of the instrument profile.
Specification of Shear Zone Characteristics in Achieving Desired Residual Stress Profile
Authors: Hanna Carl R. , Liang Steven Y. , Chao Ru-Min
Published: March 2009

Surface integrity of a machined component in meeting the demands of a specific application requirement is defined by several characteristics. The residual stress profile at the surface and sub-surface of the workpiece is often one of these characteristics as it carries a direct effect on the fatigue life of a machined component. Machined residual stress is difficult to predict since it is governed by less than predictable high stresses, temperature gradients, and phase transformation occurring during the cutting process. A significant amount of effort have been dedicated by researchers to predict residual stress in a workpiece using analytical, experimental, and numerical modeling methods. Nonetheless, no method is available that could express the cutting process parameters and tool geometry parameters as functions of machined residual stress profile to allow process planning in achieving desired residual stress profile. This paper presents a physics-based approach to predict the shear zone characteristics during an orthogonal cutting operation. Using machined residual stress requirement at the surface as an input, information such as the shear angle, the shear stress in the shear zone, the depth of cut and consequently the cutting forces are obtained by inverse calculations procedure based on the rolling/sliding contact theory, the McDowell hybrid residual stress algorithm, and the specific cutting energy. This work constitutes a basis for further design and optimization of process and tool geometry parameters in achieving a specified residual stress profile. Experimental data are presented to validate the developed model.
Micromelting for Laser Micro Polishing of Meso/Micro Metallic Components
Authors: Perry Tyler L. , Werschmoeller Dirk , Li Xiaochun , Pfefferkorn Frank E. , Duffie Neil A.
Published: March 2009

The relative surface accuracy (surface roughness/feature size) of meso/micro parts fabricated by emerging meso/micro manufacturing processes is generally worse than that of macro parts fabricated by conventional processes. Meso/micro parts have unique tribology issues and surface roughness strongly impacts their performance, hence there is a demand for effective polishing of their complex shapes. A laser micro polishing method based on rapid surface micromelting is described. To develop a fundamental understanding of the underlying processes, a nickel sample was fabricated using silicon-based microfabrication and electroplating techniques. Results demonstrating the effectiveness of laser polishing using a pulsed 1064 nm Nd:YAG laser are presented. These results show that brief (200–300 ns) laser pulses can significantly improve the sample surface roughness (Ra). Additionally, by examining surface profile data in the spatial frequency domain it is clear that using pulses (up to 300 ns), laser polishing can effectively remove surface roughness features greater than 200 mm−1 in spatial frequency.
Collaborative Workflow Technology for Design and Manufacturing Coordination: An Overview
Authors: Hao Qi , Shen Weiming
Published: March 2009

Manufacturing companies often face a harsh problem caused by misunderstanding between engineering and manufacturing departments. Based on different perspectives, they both strive to achieve some goals without fully evaluating the impacts of their decisions. Ambiguity in the description of responsibilities, interactions and processes makes collaborative product design and manufacturing very difficult to address. This paper presents a comprehensive overview of collaborative workflow technology which is made up of three major parts, workflow, software agents and Web services. We propose to use collaborative workflow technologies to facilitate heterogeneous processes of product design and manufacturing processes.
Intelligent Fault Diagnosis of Rolling Element Bearing Based on SVMs and Statistical Characteristics
Authors: Yang Junyan , Zhang Youyun , Zhu Yongsheng , Wang Qinghua
Published: March 2009

In this paper, the statistical characteristics of time, frequency and time-frequency domain are applied to discriminate various fault types and evaluate various fault conditions of rolling element bearing, and the classification performance of them is evaluated by using SVMs. Experimental results showed that the statistical characteristics Mean, Variance, Root, RMS and Peak of the 25 sub frequency bands in frequency domain obtain higher classification accuracy rate on all the fault datasets than the statistical characteristics in the whole time and frequency domain. Wavelet packet decomposition is an efficient time-frequency analysis tool, and it can decompose the original signal into independent frequency bands. Experiment on the statistical characteristics of the 5th level wavelet packet decomposition showed that the statistical characteristics Variance, Root, RMS and Peak can discriminate various fault types and evaluate various fault conditions well on all the datasets. Compared with the statistical characteristics of sub frequency bands in frequency domain, the classification performance of the statistical characteristics of the wavelet packet transform is a little lower than that of the statistical characteristics of sub frequency bands in frequency domain.
A Concentration-Dependent Diffusion Model for Selective Ultrasonic Foaming
Authors: Wang Hai , Li Wei
Published: March 2009

A novel technique was developed for the fabrication of porous polymer for biomedical applications using selective ultrasonic foaming. It was found that the gas concentration of saturated polymer samples plays an important role in the creation of open celled, interconnected porous structures. In this paper, we present a concentration-dependent diffusion model for PMMA-CO2 gas polymer system to understand the open-cell mechanism in the selective ultrasonic foaming process. An explicit finite difference scheme was employed to solve the nonlinear gas diffusion equation. By comparing with the polymer gas saturation data, a necessary condition for open celled structure is established in terms of the gas concentration levels.
Fractal Geometry Based Model for a Musical Cymbal Design and Rapid Manufacturing
Authors: Zhou Jack , Vas Ananth , Blackmore Denis , Mulero Rafael
Published: March 2009

This paper aims at an equation based simulation, CAD modeling and manufacturing of a fractal surface embedded on a musical cymbal. This study is essentially a proof-of-concept of a new method of complex-surface characterization, design and manufacturing using an equation-based approach. A cymbal shape was chosen to carry the fractal profile because generally most musical cymbals have an inherent broken surface pattern that is created to enhance the resulting musical quality, and hence it would be a topic of further study to characterize the musical notes emanating from a fractal surface on this cymbal. A fractal surface cymbal model was developed; a point cloud representation of the cymbal was generated from Matlab; a surface model was built and processed in image data processing software Imageware; a solid model was completed in CAD software PRO/E; a rapid prototype of the fractal surface cymbal was fabricated; and MasterCam software was used to generate CNC codes and simulate the CNC machining process. The effect of the variation of the parameters of the equation based surface is also shown by varying the topothesy and fractal parameter of the surface. Finally, the equation based method is used to generate other complex surfaces such as Cassini surface and the Bohemian Dome which are then solidified and prepared of manufacture.
Development of Spherical Magnetic Abrasive Made by Plasma Spray
Authors: Yamaguchi Hitomi , Hanada Kotaro
Published: March 2009

Magnetic abrasive used for the internal finishing of capillary tubes, which prevents accumulation of contamination and erratic flow of the conveyed fluid, is a composite particle, consisting of iron and Al2O3 abrasive grains. The irregularity of the magnetic abrasive shape, due to the mechanical crushing process, causes non-uniform depth of cut of the abrasive and restricts the improvement of the finished surface quality. This has resulted in a narrow range of finishing performance. Moreover, the irregularity of the magnetic abrasive shape brings about difficulty in merely introducing it into capillary tubes. To break through these difficulties, this research proposes to develop a spherical iron-based magnetic abrasive, which carries Al2O3 grains on the surface, made by plasma spray. This paper firstly examines the feasibility of the plasma spray to make the existing magnetic abrasive more spherical, and suggests the conditions needed to produce the spherical magnetic abrasive. Secondly, it studies the development of the new spherical magnetic abrasive made of separate particles: iron particles and Al2O3 abrasive grains, which carries the nonferrous abrasive on the outer surface alone. Their finishing performance, evaluated through the experiments using SUS304 stainless steel tubes, shows their applicability to magnetic abrasive finishing.
Manufacturing of Glass Diffractive Optical Elements by Use of Precision Compression Molding Process
Authors: Chen Yang , Yi Allen Y. , Klocke Fritz , Pongs Guido
Published: March 2009

Recent advances in compression molding process offer a potential high volume precision net shape fabrication method for micro and diffractive glass optical elements. In this research, glass diffractive optical elements with lateral features in the order of 2 μm and a vertical height of about 500 nm were fabricated using glassy carbon molds and BK-7 optical glass material. Glassy carbon molds used in this research were fabricated with traditional cleanroom lithography and reactive ion etching process. Compression mold process was performed to duplicate the diffractive structures onto optical glass surface. Molded glass diffractive elements were studied using an atomic force microscope and a Veeco optical profilometer to evaluate the accuracy of replication and the capacity of the molding process. Different molding process parameters were tested to improve the molding process. The experimental results showed that the compression molding process is an effective alternative fabricating method for high volume, net shape and low cost glass diffractive optical elements.
Theoretical and Experimental Substantiation of Angle Orientation of Rolling Bushings of Roller and Bushing Chains
Authors: Kryvyy Petro , Kryvinskyy Petro , Bodnar Volodymyr , Sotnyk Iryna , Senyk Andriy
Published: March 2009

Shape accuracy (deviations from the rounding) of inner cylindrical surface (ICS) of built-up bushings of transmission roller and bushing chains (TRBC) and its influence on wear-resistance of their joints and increase of internal tin and external tex contact steps is considered. Deviations from the rounding of inner cylinder surfaces of built-up bushing of transmission roller and bushing chains along ICS perimeter as well as built-up joints and diametrically opposite areas are obtained as the result of out-of-roundness profiles statistic processing. It is determined that minimum deviations from the rounding of ICS of built-up bushings take place in the area which are defined by central angle equal π/2 and is situated diametrical opposite to bushing butt joint.
Force Modeling for Laser Assisted Micro-Grooving
Authors: Singh Ramesh K. , Melkote Shreyes N.
Published: March 2009

Laser Assisted Mechanical Micro-machining (LAMM) is a process that utilizes highly localized thermal softening of the material by continuous wave laser irradiation applied simultaneously and directly in front of a miniature cutting tool in order to produce micron scale three dimensional features in difficult-to-machine materials. This process can produce lower cutting forces and deflections, prevent catastrophic tool failure and potentially increase the material removal rate. The miniature machine-tool system used to implement this process has a finite stiffness and therefore deflects under the cutting forces. The deflections may be of the same order of magnitude as the depth of cut in some cases, thereby having an effect on the dimensional accuracy of the micro-machined feature. As a result, selection of the laser and cutting parameters that will yield the desired reduction in cutting forces and deflection, and consequently an improvement in the dimensional accuracy of the micro-machined feature requires a reliable cutting force model. This paper describes a cutting force model for a laser-assisted mechanical micro-grooving process. The model combines an existing slip-line field based force model with a finite element based thermal model of laser heating and a constitutive model of the material flow stress to predict the cutting and thrust forces. Experiments are carried out on H-13 steel (42 HRC) to validate the force model with and without laser heating. The effects of LAMM parameters such as laser power, cutting speed and laser beam mode — Gaussian versus Uniform — on the forces are also analyzed. The predictions from the force model are within 10–20% of the experimental values with most below 15%.
Analyses of Full-Scale Tank Car Shell Impact Tests
Authors: Tang Y. H. , Yu H. , Gordon J. E. , Priante M. , Jeong D. Y. , Tyrell D. C. , Perlman A. B.
Published: March 2009

This paper describes analyses of a railroad tank car impacted at its side by a ram car with a rigid punch. This generalized collision, referred to as a shell impact, is examined using nonlinear (i.e., elastic-plastic) finite element analysis (FEA) and three-dimensional (3-D) collision dynamics modeling. Moreover, the analysis results are compared to full-scale test data to validate the models. Commercial software packages are used to carry out the nonlinear FEA (ABAQUS and LS-DYNA) and the 3-D collision dynamics analysis (ADAMS). Model results from the two finite element codes are compared to verify the analysis methodology. Results from static, nonlinear FEA are compared to closed-form solutions based on rigid-plastic collapse for additional verification of the analysis. Results from dynamic, nonlinear FEA are compared to data obtained from full-scale tests to validate the analysis. The collision dynamics model is calibrated using test data. While the nonlinear FEA requires high computational times, the collision dynamics model calculates gross behavior of the colliding cars in times that are several orders of magnitude less than the FEA models.
Improved Tank Car Safety Research
Authors: Tyrell David , Jeong David , Jacobsen Karina , Martinez Eloy
Published: March 2009

Three recent accidents involving the release of hazardous material have focused attention on the structural integrity of railroad tank cars: (1) Minot, ND, on January 18, 2002; (2) Macdona, TX, on June 28, 2004; and (3) Graniteville, SC, on January 6, 2005. Each of these accidents resulted in fatalities. Research is being conducted to develop strategies for improving railroad tank cars so they can maintain tank integrity in severe accidents. A collaborative effort called the Next Generation Rail Tank Car (NGRTC) Project intends to use these research results to help develop improved tank car designs. Dow Chemical Company, Union Pacific Railroad, and Union Tank Car Company are the industry sponsors of the NGRTC Project. The Federal Railroad Administration (FRA) and Transport Canada participate in the NGRTC project through Memoranda of Cooperation. FRA and the Pipeline and Hazardous Materials Safety Administration intend to use these research results to support rulemaking. The approach taken in performing this research is to define the collision conditions of concern, to evaluate the behavior of current design equipment in these scenarios, and to develop alternative strategies for increasing the maximum impact speed for which tank integrity is maintained. The accident scenarios have been developed from a review of accidents and are intended to bound the range of main-line accidents that can lead to a release of hazardous material from a tank car. The accident scenarios and collision modes have been used to define car-to-car impact scenarios. These car-to-car impact scenarios define the conditions under which the commodity must be contained. The impact scenarios are being used to evaluate the integrity of current design and improved design tank cars. Full-scale impact tests are also being conducted, to help validate modeling of the baseline equipment. The models have been refined based on the test results. The models are now being applied to develop the improved equipment designs. This paper describes the overall research framework and provides an overview of the research done to date, as well as the planned efforts.
Onboard Locomotive Exhaust Emissions Measurement
Authors: Brabb David C. , Vithani Anand R. , Punwani S. K.
Published: March 2009

Limiting harmful locomotive exhaust emissions is important to the Nation’s health and safety. The Environmental Protection Agency (EPA) has comprehensive gaseous exhaust emissions (or referred to as emissions hereto) testing requirements in place. All current tests are conducted on stationary locomotives. This paper discusses the development of an efficient stationary emissions measurement system that is compact, portable, easy to use, and applicable to onboard locomotives for in-use, over-the-road testing. More efficient locomotive emissions testing and better understanding of in-use emissions would be beneficial to all stakeholders. Sharma & Associates, Inc., (SA) adapted an off-the-shelf, portable, on-road, heavy-duty diesel truck emissions analyzer for locomotive use. This process included development of the necessary peripheral equipment and a computer program to take the raw emissions and report them as brake-specific emissions rates and duty cycle emissions. This paper describes the use of this system on a stationary locomotive. The system is currently being fitted and tested for over-the-road use. The measurement of particulate matter and smoke opacity were out of scope of the phase of the project that this paper is based on and not addressed hereto.
Flexible Wheel/Rail Contact Model for Railway Vehicle Dynamics Without Pre-Calculation
Authors: Durali Mohammad , Salehi S. Hassan , Jalili Mohammad Mehdi
Published: March 2009

An advanced method using progressive concept of geometrical correspondence is applied to create a new wheel/rail contact model based on virtual penetration theory. The geometry and contact mechanism are solved simultaneously because of the independency in a defined correspondence. The model takes the penetrated profiles of wheel and rail and also associated creeps as inputs, and produces driving contact forces as output. The advantage of this model is that it doesn’t require pretabulation of rigid contact situation. The method allows calculating flexible, non-elliptical, multiple contact patches during integration of the model. Consequently the rails with substructures can vibrate separately from the vehicle in a flexible wheel/rail contact model. The simulation results indicate that this method can be used in various rail vehicle dynamic problems.
A Methodology for the Modeling of Rail Vehicles From Time Series Measurements Using Time-Delay Neural Networks
Authors: Zolock John , Greif Robert
Published: March 2009

The main goal of this research is to develop and demonstrate a general, efficient, mathematically and theoretically based methodology to model nonlinear forced vibrating mechanical systems from time series measurements. A system identification modeling methodology for forced dynamical systems is presented based on dynamic system theory and nonlinear time series analysis that employs phase space reconstruction (delay vector embedding) for modeling of dynamical systems from time series data using time-delay neural networks (TDNN). The first part of this work details the modeling methodology including background on dynamic systems, phase space reconstruction, and neural networks. In the second part of this work the methodology is evaluated based on its ability to model selected analytical lumped parameter forced vibrating dynamic systems including an example of a linear system predicting lumped mass displacement using a displacement forcing. function The work discusses the application to nonlinear systems, multi degree-of-freedom systems, and multi-input systems. The methodology is further evaluated on its ability to model an analytical passenger rail vehicle predicting vertical wheel/rail force using vertical rail profile as input. Studying the neural modeling methodology using an analytical systems shows the clearest observations from results which provide prospective users of this tool an understanding of the expectations and limitations of the modeling methodology.
Comprehensive Characterization of Genes Required for Protein Folding in the Endoplasmic Reticulum
Authors: Jonikas Martin C. , Collins Sean R. , Denic Vladimir , Oh Eugene , Quan Erin M. , Schmid Volker , Weibezahn Jimena , Schwappach Blanche , Walter Peter , Weissman Jonathan S. , Schuldiner Maya
Published: March 2009

Protein folding in the endoplasmic reticulum is a complex process whose malfunction is implicated in disease and aging. By using the cell's endogenous sensor (the unfolded protein response), we identified several hundred yeast genes with roles in endoplasmic reticulum folding and systematically characterized their functional interdependencies by measuring unfolded protein response levels in double mutants. This strategy revealed multiple conserved factors critical for endoplasmic reticulum folding, including an intimate dependence on the later secretory pathway, a previously uncharacterized six-protein transmembrane complex, and a co-chaperone complex that delivers tail-anchored proteins to their membrane insertion machinery. The use of a quantitative reporter in a comprehensive screen followed by systematic analysis of genetic dependencies should be broadly applicable to functional dissection of complex cellular processes from yeast to human.
Emerging Market Organisms
Authors: Slack Jonathan M. W.
Published: March 2009

Emerging Model Organisms
. A Laboratory Manual. Volume 1. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 2009. 604 pp. $158, £100. ISBN 9780879698263. Paper, $89, £55. ISBN 9780879698720.
http://cshprotocols.cshlp.org/emo/

For each species (or group), the authors describe possible applications in lab research; summarize husbandry, genetics, and genomics; list other resources; and provide basic protocols for work with the organism.
The Darwinian Eye
Authors: Ritvo Harriet
Published: March 2009

Endless Forms
. Charles Darwin, Natural Science and the Visual Arts.
Diana Donald and Jane Munro, Curators
. Yale Center for British Art, New Haven, CT. 12 February-3 May, 2009. Fitzwilliam Museum, Cambridge. 16 June-4 October, 2009.
www.darwinendlessforms.org

Endless Forms
. Charles Darwin, Natural Science and the Visual Arts.
Diana Donald and Jane Munro, Eds.
. Yale University Press, New Haven, CT, 2009. 358 pp. $75, £40. ISBN 9780300148268.

This exhibit explores the wide range of interplay between Darwin's ideas and the visual culture of the 19th century.
Two-Step Epstein-Barr Virus Immunoglobulin A Enzyme-Linked Immunosorbent Assay System for Serological Screening and Confirmation of Nasopharyngeal Carcinoma
Authors: Paramita Dewi K. , Fachiroh Jajah , Haryana Sofia M. , Middeldorp Jaap M.
Published: March 2009

Undifferentiated nasopharyngeal carcinoma (NPC; WHO type III) is 100% associated with Epstein-Barr virus (EBV) infection and the fourth most prevalent cancer in Indonesian males. Therapy failure is high, since most patients come to the hospital at an advanced stage of disease. Screening for early-stage NPC is needed. Here, a simple and economical two-step enzyme-linked immunosorbent assay (ELISA) system is proposed for diagnosing NPC in high-risk populations, employing the peptide-based immunoglobulin A (IgA) EBNA1 plus viral capsid antigen p18 ELISA as an initial screening test and the IgA early antigen (EA) ELISA using a different set of EBV antigens as a confirmation test. A total of 151 NPC patients and 199 regional healthy EBV carriers were used to evaluate the two-step ELISA approach. Routinely, EBV IgG immunoblotting is used as a standard confirmation test. The sensitivity and specificity for diagnosing NPC by the two-step ELISA approach increased from 85.4% to 96.7% and 90.1% to 98%, respectively, with positive predictive values and negative predictive values increasing from 78.7 and 93.9% to 97.3 and 97.5%, respectively, relative to the immunoblotting confirmation system. On discrepant samples, additional testing was done by EBV DNA load quantification in blood. Results showed that 5/11 discrepant NPC samples with an elevated IgA EA ELISA also had elevated an EBV DNA load in the circulation (range, 3,200 to 25,820 copies/ml). Therefore, the IgA EA ELISA is proposed as a confirmation test in first-line NPC serological screening studies. This two-step EBV ELISA system provides a standardized approach for NPC screening and may be used in combination with dried blood sampling in future field studies for identification of early-stage NPC in high-risk regions.
Rapid Detection of H5N1 Subtype Influenza Viruses by Antigen Capture Enzyme-Linked Immunosorbent Assay Using H5- and N1-Specific Monoclonal Antibodies
Authors: Ho Hui-Ting , Qian Hong-Liang , He Fang , Meng Tao , Szyporta Milene , Prabhu Nayana , Prabakaran Mookkan , Chan Kwai-Peng , Kwang Jimmy
Published: March 2009

Highly pathogenic avian influenza (HPAI) virus of the H5N1 subtype has caused devastating damage to poultry flocks and sporadic human H5N1 infections. There is concern that this virus subtype may gain transmissibility and become pandemic. Rapid diagnosis and surveillance for H5N1 subtype viruses are critical for the control of H5N1 infection. In this study, we report a robust antigen-capture enzyme-linked immunosorbent assay (AC-ELISA) based on H5- and N1-specific monoclonal antibodies (MAbs) for the rapid detection of H5N1 subtype viruses. The H5 hemagglutinin (HA)-specific MAb (2D9) targets a conformational epitope which recognized multiple clades of H5N1 viruses, including clades 0, 1, 2.1, 2.2, 2.3, 4, 7, and 8. The N1 neuraminidase (NA)-specific MAb (8H12) recognized a linear epitope comprising the sequence AELPF. This epitope was 99% conserved in the NA of 708 analyzed H5N1 viruses, while the epitope was absent in NAs of subtypes N2 through N9. The specificity of the AC-ELISA was examined by using 41 H5N1 HPAI strains from multiple clades, 36 non-H5N1 viruses, and 4 influenza B viruses. No cross-reactivity was observed for any of the non-H5N1 viruses tested. The estimated detection limit was 1 to 2 HA titers. It is concluded that this H5N1 AC-ELISA can simultaneously detect H5 and N1 subtype antigens, eliminating the need for secondary testing for the NA subtype. Implementation of this assay in ELISA-like formats suitable for field use, such as dot ELISA, immunofiltration, or electrochemical biosensor technologies, would provide dual on-site detection of H5 and N1 in clinical or environmental specimens.
Laboratory Diagnosis of Amoebic Keratitis: Comparison of Four Diagnostic Methods for Different Types of Clinical Specimens
Authors: Boggild Andrea K. , Martin Donald S. , Lee Theresa YuLing , Yu Billy , Low Donald E.
Published: March 2009

Amoebic keratitis causes significant ocular morbidity in contact lens wearers. Current diagnostic methods for amoebic keratitis are insensitive and labor-intensive and have poor turnaround time. We evaluated four laboratory methods for detection of acanthamoebae in clinical specimens. Deidentified, delinked consecutive specimens from patients with suspected amoebic keratitis were assayed for acanthamoebae by direct smear analysis, culture, and PCR using two different primer sets specific for
Acanthamoeba
ribosomal DNA. The consensus reference standard was considered fulfilled when the results for any two of the four tests were positive, and the outcome measures were sensitivity and specificity. Of 107 specimens assayed over an 18-month period, 20 were positive for acanthamoebae. The sensitivity and specificity of each assay were as follows, respectively: for smear analysis, 55% (95% confidence interval [CI], 33.2 to 76.8%) and 100%; for culture, 73.7% (95% CI, 54.4 to 93.0%) and 100%; for PCR using Nelson primers, 90% (95% CI, 76.9 to 100%) and 90.8% (95% CI, 84.7 to 96.9%); and for PCR using JDP primers, 65% (95% CI, 44.1 to 85.9%) and 100%. Nelson primer PCR demonstrated a single-organism level of analytic sensitivity. The performance characteristics of the assays varied by specimen type, with contact lenses and casings showing the highest rates of detectable acanthamoebae and the highest diagnostic sensitivities for direct smear analysis, culture, and JDP primer PCR, though these results are based on small numbers and should be interpreted cautiously. These findings have important implications for clinicians collecting diagnostic specimens and for diagnostic laboratories, especially in outbreak situations.