bluuebunny/crossref_metadata_2025 huggingface dataset:
ORIGINAL ARTICLE: Comparison of demographic and direct methods to calculate probabilistic maturation reaction norms for Flemish Cap cod (Gadus morhua)
Authors: Pérez‐Rodríguez Alfonso , Morgan Marie Joanne , Saborido‐Rey Fran
Published: July 2009

Age and length at maturation have declined in many fish populations and this has been hypothesized to be a genetic change caused by high fishing mortality. Probabilistic Maturation Reaction Norms (PMRNs) have been used as a tool to gain a better understanding of the possible genetic nature of these changes. The demographic and direct methods are two ways to calculate PMRNs. The data requirements are more often met for the demographic method than for the direct method which requires the identification of recruit spawners. However, the demographic method relies on more assumptions than the direct method, typically assuming equality of growth and mortality rates for immature and mature individuals within an age class. This study provides the first direct comparison of demographic and direct methods and shows that both methods produce comparable results. Differences between methods are hypothesized to be owed to possible differences in growth rate between mature and immature individuals in Flemish Cap cod.
Decreased Triadin and Increased Calstabin2 Expression in Great Danes with Dilated Cardiomyopathy
Authors: Oyama M.A. , Chittur S.V. , Reynolds C.A.
Published: August 2009

Background: Dilated cardiomyopathy (DCM) is a common cardiac disease of Great Dane dogs, yet very little is known about the underlying molecular abnormalities that contribute to disease.

Objective: Discover a set of genes that are differentially expressed in Great Dane dogs with DCM as a way to identify candidate genes for further study as well as to better understand the molecular abnormalities that underlie the disease.

Animals: Three Great Dane dogs with end‐stage DCM and 3 large breed control dogs.

Methods: Prospective study. Transcriptional activity of 42,869 canine DNA sequences was determined with a canine‐specific oligonucleotide microarray. Genome expression patterns of left ventricular tissue samples from affected Great Dane dogs were evaluated by measuring the relative amount of complementary RNA hybridization to the microarray probes and comparing it with expression from large breed dogs with noncardiac disease.

Results: Three hundred and twenty‐three transcripts were differentially expressed (≥2‐fold change). The transcript with the greatest degree of upregulation (+61.3‐fold) was calstabin2 (FKBP12.6), whereas the transcript with the greatest degree of downregulation (−9.07‐fold) was triadin. Calstabin2 and triadin are both regulatory components of the cardiac ryanodine receptor (RyR2) and are critical to normal intracellular Ca2+ release and excitation‐contraction coupling.

Conclusion and clinical importance: Great Dane dogs with DCM demonstrate abnormal calstabin2 and triadin expression. These changes likely affect Ca2+ flux within cardiac cells and may contribute to the pathophysiology of disease. Microarray‐based analysis identifies calstabin2, triadin, and RyR2 function as targets of future study.
Hopkinson Bar Loaded Fracture Experimental Technique: A Critical Review of Dynamic Fracture Toughness Tests
Authors: Jiang Fengchun , Vecchio Kenneth S.
Published: August 2009

Hopkinson bar experimental techniques have been extensively employed to investigate the mechanical response and fracture behavior of engineering materials under high rate loading. Among these applications, the study of the dynamic fracture behavior of materials at stress-wave loading conditions (corresponding stress-intensity factor rate ∼106 MPam/s) has been an active research area in recent years. Various Hopkinson bar loading configurations and corresponding experimental methods have been proposed to date for measuring dynamic fracture toughness and investigating fracture mechanisms of engineering materials. In this paper, advances in Hopkinson bar loaded dynamic fracture techniques over the past 30 years, focused on dynamic fracture toughness measurement, are presented. Various aspects of Hopkinson bar fracture testing are reviewed, including (a) the analysis of advantages and disadvantages of loading systems and sample configurations; (b) a discussion of operating principles for determining dynamic load and sample displacement in different loading configurations; (c) a comparison of various methods used for determining dynamic fracture parameters (load, displacement, fracture time, and fracture toughness), such as theoretical formula, optical gauges, and strain gauges; and (d) an update of modeling and simulation of loading configurations. Fundamental issues associated with stress-wave loading, such as stress-wave propagation along the elastic bars and in the sample, stress-state equilibrium validation, incident pulse-shaping effect, and the “loss-of-contact” phenomenon are also addressed in this review.
An Engineering Estimate for Plug-Flow Convection in Porous Media Discarding Fluid Conduction
Authors: Dukhan Nihad
Published: July 2009

Metal and graphite foam are relatively new types of porous materials characterized by having high-solid phase conductivities. In many cooling applications of these materials, including high-power electronics, low-conductivity fluids flow through them, e.g., air. A simple approximate engineering solution for the convection heat transfer inside a two-dimensional rectangular porous media subjected to constant heat flux on one side is presented. The conduction in the fluid is set to zero, and for simplicity, a plug flow is considered. As a result, the non-local-thermal equilibrium equations are significantly simplified and solved. The solid and fluid temperatures decay in what looks like an exponential fashion as the distance from the heated wall increases. The results are in good agreement with one more complex analytical solution in the literature, in the region far from the heated wall only.
In Situ Chip Stress Extractions for LFBGA Packages Through Piezoresistive Sensors
Authors: Lwo Ben-Je , Su Jeng-Shian , Chung Hsien
Published: July 2009

Piezoresistive sensors have been demonstrated to be an accurate and efficient tool for stress measurements on chip surfaces inside microelectronic packaging. In this work, test chips with piezoresistive stress sensors, diode temperature sensors as well as heaters were first designed, fabricated, and calibrated. We next packaged the test chips into low profile, fine pitch ball grid array (LFBGA) packaging with 196 balls and measured the stresses on chip surfaces inside the packaging. After measuring the packaging induced stress as well as the stress under stable environmental temperature rises, it was found that compressive stresses were obtained at room temperature, and the stresses were relaxed as temperature went up at a rate between 0.45 MPa/°C and 0.60 MPa/°C. For thermo-stress experiments, the temperatures on chip surfaces at different power levels were measured, and compressive chip stresses were first extracted. As the chip power increased, the compressive stresses became tensions. Since the LFBGA structure is thinner with higher packaging efficiency, different results from our earlier plastic quad flat package stress measurements were observed and discussed. In addition, the final comparisons between the experimental data and the finite element simulations show good consistency.
Tensile Behaviors of Lead-Containing and Lead-Free Solders at High Strain Rates
Authors: Qin Fei , An Tong , Chen Na , Bai Jie
Published: July 2009

Behavior of solder joints in microelectronic packages is crucial to the drop impact reliability design of mobile electronic products. In this paper, tensile behaviors of Sn37Pb, Sn3.5Ag, and Sn3.0Ag0.5Cu at strain rates of 600 s−1, 1200 s−1, and 1800 s−1 were investigated using the split Hopkinson tensile bar experimental technique. Stress-strain curves of the three solders were obtained, and microstructure and fractography of the specimens before and after the tests were examined and presented. The experimental results show that the lead-free solders are strongly strain rate dependent: Their tensile strength, percent elongation, and percent reduction in area are much greater than those properties of the lead-containing solder at high strain rates.
Effect of Leadframe Oxidation on the Reliability of a Quad Flat No-Lead Package
Authors: Abdullah S. , Abdullah M. F. , Ariffin A. K. , Jalar A.
Published: July 2009

This study analyzed the reliability of two condition types of copper leadframe, namely, good and oxidized. Both types of leadframe were used in the fabricating process of a quad flat no-lead (QFN) package. Determining the adhesiveness of die strength and determining the strength of the leadframe are important in order for the package to obtain higher reliability. Commonly, an epoxy material is used in the die attachment process for die adherence onto the leadframe. A statistical analysis of the die shear test and the cyclic strain test of a QFN package was performed in this paper. From the application of the t-test method, the p-value shows a significant difference in die shear stress depending on leadframe condition. Based on a process capability ratio (Cpk) above 1, the leadframe in good condition showed better processing capability than the oxidized leadframe. The Coffin–Manson approach was used in the cyclic loading of a QFN package to predict the package reliability in terms of cyclic strain. The leadframe in good condition showed a higher die strength value and lower microstrain compared with the oxidized leadframe. The oxidized leadframe provided a poor surface to attach adhesive and a higher microstrain on cyclic load, resulting in a negative effect on package reliability, such as a crack phenomenon at the epoxy interface between the die and the leadframe. This occurrence may ultimately cause delamination, which occurs between the die and the leadframe die pad.
An Overmolded Pressure Sensor Package Using an Ultrathick Photoresist Sacrificial Layer
Authors: Chen Lung-Tai , Cheng Wood-Hi
Published: July 2009

This study presents a novel technique for an overmolded package of piezoresistive pressure sensors using an ultrathick photoresist sacrificial layer. A 150 μm photoresist block is placed just on the silicon membrane of the pressure sensor and removed after the molding transfer process. The removal of the photoresist block exposes and reserves a sensing channel in the overmolded pressure sensor package. Experimental observations reveal that the silicon membrane of the pressure sensor is completely free of any epoxy molding compound contamination after the transfer molding process. The effectiveness of the photoresist block in shielding the silicon membrane of the pressure sensor was confirmed. Experiment and finite element model results reveal that the packaged pressure sensor has similar sensing characteristics to those of an unpackaged pressure sensor at room temperature. However, the packaged pressure sensor exerts a thermomechanical stress on the silicon membrane of the pressure sensor, resulting in an undesired output voltage drift. Employing a proper package design can reduce the output voltage drift. The proposed packaging scheme has a small package volume and surface mount device compatible features, making it suitable for portable commercial devices.
Upscaling of the Geological Models of Large-Scale Porous Media Using Multiresolution Wavelet Transformations
Authors: Rasaei M. Reza , Sahimi Muhammad
Published: August 2009

To model fluid flow and energy transport in a large-scale porous medium, such as an oil or a geothermal reservoir, one must first develop the porous medium’s geological model (GM) that contains all the relevant data at all the important length scales. Such a model, represented by a computational grid, usually contains several million grid blocks. As a result, simulation of fluid flow and energy transport with the GM, particularly over large time scales (for example, a few years), is impractical. Thus, an important problem is upscaling of the GM. That is, starting from the GM, one attempts to generate an upscaled or coarsened computational grid with only a few thousands grid blocks, which describes fluid flow and transport in the medium as accurately as the GM. We describe a powerful upscaling method, which is based on the wavelet transformation of the spatial distribution of any static property of the porous medium, such as its permeability, or a dynamic property, such as the spatial distribution of the local fluid velocities in the medium. The method is a multiscale approach that takes into account the effect of the heterogeneities at all the length scales that can be incorporated in the GM. It generates a nonuniform computational grid with a low level of upscaling in the high permeability sectors but utilizes high levels of upscaling in the rest of the GM. After generating the upscaled computational grid, a critical step is to calculate the equivalent permeability of the upscaled blocks. In this paper, six permeability upscaling techniques are examined. The techniques are either analytical or numerical methods. The results of computer simulations of displacement of oil by water, obtained with each of the six methods, are then compared with those obtained by the GM.
Forced Convection With Laminar Pulsating Counterflow in a Saturated Porous Channel
Authors: Nield D. A. , Kuznetsov A. V.
Published: August 2009

An analytical solution is obtained for forced convection in a parallel-plate channel occupied by a layered saturated porous medium with counterflow produced by pulsating pressure gradients. The case of asymmetrical constant heat-flux boundary conditions is considered, and the Brinkman model is employed for the porous medium. A perturbation approach is used to obtain analytical expressions for the velocity, temperature distribution, and transient Nusselt number for convection produced by an applied pressure gradient that fluctuates with small amplitude harmonically in time about a nonzero mean. It is shown that the fluctuating part of the Nusselt number alters in magnitude and phase as the dimensionless frequency increases. The magnitude increases from zero, goes through a peak, and then decreases to zero. The height of the peak depends on the values of various parameters. The phase (relative to that of the steady component) decreases as the frequency increases. The phase angle at very low frequency can be π/2 or −π/2 depending on the degree of asymmetry of the heating and the values of other parameters.
Torpedo Propulsion Systems
Authors: Gottfredson R. K.
Published: July 2009

The paper begins with a short discussion of torpedo propulsion criteria followed by definitions of the three generic torpedo types and a brief description of each. A major portion of the paper is devoted to descriptions of lightweight anti-submarine torpedoes since the greatest advances in technology will be required for this generic type. Two basic torpedo propulsion systems are discussed; electric and open cycle thermal. Advantages and disadvantages of both types are pointed out followed by examples representative of state-of-the-art systems. In depth presentations of various energy sources, prime movers, and speed reducers are given and several new potential propulsion subsystems are described.
Characteristics of Surface Topography and Static Friction on Scraped Surface Slideway—Part 2
Authors: Kato S. , Marui E. , Kobayashi A. , Matsubayashi T.
Published: July 2009

The relation between static friction characteristics and surface topography of contacting scraped surfaces are theoretically examined under boundary lubrication. As a result, it is clarified that the topographic effects on static friction of a scraped surface can be evaluated quantitatively by a nondimensional parameter (coefficient of surface topography). The sliding characteristics of scraped surface slideway can be improved by using surfaces having a large coefficient of surface topography.
A Method of Obtaining Detailed Freight Car Truck Loading Data
Authors: Spencer C. P. , Pitchford T. L.
Published: July 2009

A method of obtaining freight car truck loading data utilizing a strain gaged truck bolster as a load cell is described. Analysis necessary to derive both the magnitude and location of the line of action of the freight car body vertical load resultant is presented. Techniques for cycle counting applicable to fatigue studies are suggested. Sample data from actual service testing are presented.
An Analysis of Unsteady Thermal Stresses in Rolls of CCP under a Rotating Heat Source
Authors: Takeuti Y. , Noda N.
Published: July 2009

The subject treated in this paper forms a part of a more precise thermomechanical consideration in designing of rolls in the continuous casting plant at the iron manufacture. From an analytical point of view, a fundamental problem in rolls is reduced to the problem of solving the transient thermal stress in a hollow circular cylinder due to a rotating arc heat source with a constant angular velocity. Numerical results are given for the thermal stress distribution in actual rolls.
Super Microscopic Displacement and Angle Adjusting Instrument
Authors: Tsuda N. , Nakano K. , Sawabe M.
Published: July 2009

A newly developed apparatus that can afford fine displacement and angle is reported here. The characteristics of this is to make use of elastic deformation and to be manufactured as firmly as possible in a solid structure. The experimental results show that adjusting rectilinear displacement can be set within 0.01 μm, and this apparatus can perform paralleled movement of 4 μm displacement within 0.01 seconds of arc, moreover can set the given angles, for example 1.0, 0.5 and 0.2 seconds of arc correctly and easily.
Development of a New Concept for Cylindrical Pressure Hulls
Authors: Knapp R. H. , Kudo R. T. , Auksmann B.
Published: July 2009

The prebuckled cylindrical (PC) shell represents a new structural concept suitable for use in the undersea environment. The externally pressurized PC shell has been shown to be more resistant to buckling failure than a comparable “true” cylinder. The technical feasibility of this new concept has now been realized by the design and construction of a large-scale prototype made entirely of transparent acrylic plastic. The success of this initial effort offers encouragement to further pursue applications of this novel structural form to other uses in the ocean.
First Order Dynamic Response of Freight Car to Track Irregularities
Authors: Guins S. G.
Published: July 2009

This paper offers a review of simple dynamic response of the freight car suspension to track irregularities, the resultant effect on lading and energy feed back to the track structure.
Unit Machining Operations: An Automated Process Planning and Selection Program
Authors: Wysk R. A. , Barash M. M. , Moodie C. M.
Published: July 2009

In most metal cutting or removing facilities, the task of planning piece part operations and sequences is the responsibility of the process planner. Although this individual holds the key to the profitability of a specific product, little has been done to aid the process planner in the performance of his job. With the cost of machinery skyrocketing as the degree of automation is increasing, much emphasis has been placed on process planning or engineering. This paper outlines the responsibilities and functions carried out by the process planner. The paper is primarily concerned with automated manufacturing systems and, in particular, the planning of parts on machining centers. It demonstrates the decisions required of process planner and the lack of quantifiable data available to make logical decisions at the present time. A review of the two approaches to automated process planning, called variant and generative planning, is presented. The paper also describes some of the shortcomings of classification codes that have been used for automated process planning. The framework for a computer generative process planning scheme is demonstrated. The selection of machining parameters (feed, speed and depth of cut) are also discussed.
Sampling for Confidence Interval Estimation of the Fiber Shape Factor
Authors: Russell C. B. , Barker R. L. , Lyons D. W.
Published: July 2009

A method is described for estimating the shape factor, the ratio of the maximum and minimum projected diameters, of a fiber from measurements made on a longitudinal view. The method assumes that the measured diameters have a uniform distribution, an assumption which seems justified for cotton fibers. An estimator of the shape factor is given; a confidence interval for the shape factor is derived; and a sampling plan together with formulae for determining an adequate sample size is presented.
The Potential for Industrial Energy Conservation in California
Authors: Dornfeld D. , Benenson P. , Barnes R.
Published: July 2009

The industrial energy conservation scenarios developed in this study show the combined effect on energy consumption of implementing a number of conservation measures. The scenarios include assumptions about economic, demographic and behavioral, and technological variables such as population, industrial growth, and conservation implementation levels. The basic approach for the conservation scenario construction is to quantify base year (1974) per capita energy consumption by industrial subsector, reduce per capita consumption by the estimated conservation potential in the appropriate year, and extrapolate by industrial and population growth. The scenario projects significant reductions in energy consumption. The estimated savings of 2.7 × 1015 BTU (2.9 × 1018 Joules) in 2020 is approximately 30% less than the estimated energy consumption without conservation. Although the scenario was calculated for California industry, the estimates of individual conservation potentials are applicable to other regions of the United States.
Polycarbonate Plastic Inserts for Spherical Acrylic Plastic Shells Under Hydrostatic Loading
Authors: Stachiw J. D. , Dolan R. B. , Clayton D. L.
Published: July 2009

An acrylic plastic spherical pressure hull incorporating polycarbonate inserts for mounting of penetrators has been built and pressure tested. The transparent hull will serve as one atmosphere cockpit in Johnson-Sea-Link #3 submersible for 2500 ft. service. Tests have been conducted with model scale polycarbonate inserts in acrylic plastic spherical pressure hulls and windows to evaluate the structural integrity and cyclic fatigue life of polycarbonate plastic inserts and acrylic shells in which they are mounted under repeated hydrostatic pressurizations. Test results indicate that the short term, long term and cyclic fatigue life of a polycarbonate insert, serving as a bulkhead for electric or hydraulic penetrators in spherical acrylic plastic pressure hulls or windows, exceeds that of the acrylic plastic shell in which it is mounted. Structural parameters of polycarbonate inserts are discussed and design criteria formulated for their utilization in manned submersibles and pressure vessels for human occupancy. Particular emphasis is placed on selection of material, seal configuration, and retainment design.
Relationships Between Cutting Force Variations and Cutting Factors in Plain Milling Operations. Part 1: Plain Milling With a Single-Toothed Helical Cutter
Authors: Kato S. , Yamada T. , Hashimoto M. , Yamaguchi K.
Published: July 2009

In plain milling operations with a single-toothed helical cutter, three components of cutting force are measured simultaneously and continuously corresponding to the varying cross-sectional area of cut by means of a unique optical method. Based on the measured cutting force variation in a constant width of cut, some required cutting force variations in various widths of cut can be obtained by summing up the overlapped basic cutting force variation patterns. Relationships between cutting force variations and cutting factors in plain milling operations are explained on the basis of the experimental results and the expanded results of experiments.
Stochastic and Fuzzy Decision Problems in Three-Workpiece Lapping Process
Authors: Sakai Y. , Tanaka Y. , Ido M.
Published: July 2009

The basic, remarkable properties lying in the three-workpiece lapping process were previously described by the authors. It was assured there that highly flat surfaces can be obtained predicting and controlling the change in shape of the three workpieces. A methodology of an optimal handling of the process was also developed in another paper, regarding the process as a deterministic one. A modified but more practical discussion is taken up here taking into consideration the stochastic behavior of the process. In so doing, a stochastic treatment in the dynamic programming approach is introduced with the reformulation of the process dynamics as a stochastic differential equation. The concept of fuzzy sets is also employed in order to overcome the difficulty in setting the criterion for optimal policies, which seems to be useful in manufacturing fields.
Ride Quality Analysis of Multi-Level Auto Rack Equipped Flat Cars
Authors: Carman R. W. , Kieres K. C.
Published: July 2009

Ride characteristics of three different truck spring arrangements applied to multi-level auto rack equipped 89 ft. (27.1 m) flat cars were measured. Spring arrangements consisted of a group designed to carry the full AAR axle capacity, a reduced capacity group designed for the actual weight carried, and a hydraulically damped spring group. Data was reduced using a spectrum analyzer to produce spectral density plots.
Passive Acoustic Detection of Gas Leaks in Buried Pipes
Authors: Soom A. , Martin H. R. , Lea J. A.
Published: July 2009

The feasibility of using microphones to detect sounds generated by small (1.1 to 3.5 mm dia) buried jet-like gas leaks is examined. The main aspects of the problem, namely, the determination of leak-radiated sound power, the attenuation of air waves in sands and soils, and the measurement of ambient sound pressure levels below ground are explored experimentally under laboratory and simulated field conditions. It is found that there are fairly severe range limitations to detection due to low source strengths and high attenuation rates in soils and sands, even though ambient noise below ground tends to be of a low level. Nevertheless, detection to ranges of 3 m or more is feasible at line pressure above approximately 60 kPa. This capability could be useful in the precise location of leaks once an approximate leak position has been established by other means. Errors in previously published values of attenuation constants in sands are identified.
Sound Transmission Through a Cylindrical Pipe Wall
Authors: Fagerlund A. C. , Chou D. C.
Published: July 2009

A theory is developed for predicting the limiting transmission loss of sound through pipe wall. The approach is general to allow an evaluation of the effects of the internal and external fluids as well as the basic physical characteristics of the cylinder. The effects of internal static pressure and the presence of a uniforn flow are also discussed. Results of an experimental program are presented which verify the theory for standard commercial pipes.
Train Brake and Track Capacity Requirements for the ’80s
Authors: Blaine D. G. , Hengel M. F. , Peterson J. H.
Published: July 2009

Ten years ago, the authors presented ASME Paper 71-WA/RT-9 which examined air brake system operating and test procedures and their effect on train operation. To meet the requirements of the ’80s, the authors believe it is essential to look back over the last ten years at the factors which influenced the thinking, maintenance trends, and performance of the freight car fleet. To meet future demands, a projection of the car fleet and the tonnage to be carried must be reviewed. Important changes and improvements have been put into place regarding air brake equipment and train speed control. This paper reviews the present situation and looks into the ’90s to identify areas where further changes and improvements seem necessary.
Oxygen Facilities for Synthetic Fuel Projects
Authors: Scharle W. J. , Wilson K.
Published: July 2009

Synthetic fuel projects will require very large oxygen facilities. This paper examines the issues that must be resolved in the design of these facilities. It surveys the major items of equipment, and proposes criteria for train-size selection. Data on energy efficiency and capital investment are presented, as functions of train size. Field construction problems, shipping constraints, and equipment availability are considered. Compression alternatives for high pressure oxygen, system reliability, and process computer control are discussed in detail. The paper concludes that only a modest extrapolation of present experience will be required to build these massive facilities.
Table Sliding Taper Hobbing of Conical Gear Using Cylindrical Hob. Part 2: Hobbing of Conical Involute Gear
Authors: Mitome K.
Published: July 2009

First this paper discusses an imaginary generating rack when an involute hob is used, on the basis of the theoretical analysis in Part 1 of this paper. Next a conical involute gear generated by the rack is analyzed. Finally, practical hobbing is discussed. Some test gears are cut and inspected. And is confirmed propriety of considering the ideal conical gear defined in Part 1 as the representative of the gear cut by the table sliding taper hobbing.
A Finite Element Method for the Elastic Contact Problems
Authors: Sachdeva T. D. , Ramakrishnan C. V. , Natarajan R.
Published: July 2009

A relatively simple technique used by Francavilla, et al. for frictionless elastic contact problems with displacement boundary conditions has been extended to handle the problems with force boundary conditions. The number of iterations necessary for solving this nonlinear problem is very small. The method has been applied to several test and practical problems and excellent results have been obtained.
On the Use of the Finite Element Method on Some Acoustical Problems
Authors: Cederfeldt L.
Published: July 2009

In a project carried out in 1974-1975, financially supported by the National Swedish Council for Building Research, the finite element method was applied on some acoustical problems to illustrate the possibilities of the method. Calculations have been made for the following examples; sound attenuation of a lined right angle bend, a lined straight duct, and expansion chamber and the sound reduction of a resilient skin. The FEM has its power for small geometries particularly at low frequencies, that is, when analytical methods usually are weak. The more complicated geometry and boundary conditions of the studied problem may be the more powerful the FEM is compared to analytical methods.
Mathematical Modeling of Metal Extrusion Process
Authors: Bhattacharyya S. , Majumdar A. K. , Basu S. K.
Published: July 2009

The present paper describes a novel calculation procedure for the detailed prediction of flow field during the process of metal extrusion. The flow of metal has been regarded as a flow of highly viscous Newtonian fluid. A finite-difference algorithm commonly used for solving hydrodynamics has been adapted to develop an improved prediction procedure. The predicted flow field compares well with the available experiments. A new dimensionless parameter which has been shown to represent the metal forming process has been identified; its relationship with extrusion ratio has also been demonstrated.
Transfer Lines: A Deterministic Model for Buffer Capacity Selection
Authors: Canuto E. , Villa A. , Rossetto S.
Published: July 2009

A key problem in transfer line design is that of determining what size should be assigned to intermediate storage buffers in order to maintain a desired production rate despite the imbalances in supply and demand which may arise within the system. In this paper, a deterministic model of production and storage operations of a transfer line, subject to breakdowns and subsequent repair of stations, is presented. Then a simple method, based on the cumulative production curve of each station, for analyzing transfer lines operations is suggested. An extensive use of the method, both numerically and graphically, allows an accurate selection of intermediate storage capacities in the light of guaranteeing the system a stationary mean production rate.
Effect of Weather, Age, and Cyclic Pressurizations on Structural Performance of Acrylic Plastic Spherical Shells Under External Pressure Loading
Authors: Stachiw J. D. , Dolan R. B.
Published: July 2009

Weathering, aging, and cyclic application of stresses to acrylic plastic degrades its physical properties. The rate of degradation must be known if the useful life of load-carrying acrylic structures is to be predicted with accuracy. Physical and chemical tests conducted by the authors on thick spherical shells indicate that the weathering affects only a thin surface layer of material, which after 10 years is still less than 0.020 in. thick. Similarly, pollutants in the ambient atmosphere of the pressure chamber affect the surface layer of the spherical shell facing the interior of the chamber. The physical and chemical properties of the thin surface layer affected by weathering differed significantly from those in the middle of 2.5-in.-thick Plexiglas G plate; the decrease in properties was: 40 percent in tensile elongation, 34 percent in flexure strength, 21 percent in tensile strength, and 79 percent in molecular weight. Since the interior body of the thick plastic shell is not affected by weathering or chemical attack and the affected surface layers are very thin, the ability of the shell to carry compressive loads is not significantly diminished after 10 years of service. Only an 11 percent decrease of critical pressure was observed in spherical shells with thickness of 1 in. subjected to 10 years of weathering and 2000 pressure cycles of 8 hour duration each to 30 percent of its original critical pressure. Based on the preceding data it appears safe to extend the operational life from 10 to 20 years of all acrylic plastic spherical shells with bearing surfaces normal to spherical surface designed on the basis of ANSI/ASME PVHO-1 Safety Standard for external pressure service.
Ring Forming: An Upper Bound Approach. Part 1: Flow Pattern and Calculation of Power
Authors: Avitzur B. , Van Tyne C. J.
Published: July 2009

In this series of papers, the generalized ring forming process is analyzed for a Mises’ material, using an upper bound approach. This analysis allows the motivation for the process to be supplied on any surface, and permits the application of external surface tractions on any of the other surfaces of the ring. Because of the generality of the analysis, the range of valves that the radial flow parameter (i.e. the neutral radius) can possess is broadened. Under certain circumstances, the traditionally defined neutral radius becomes an imaginary (i.e. complex) number. An introduction to the approach and the calculation of the individual power terms is presented in Part 1. The analytical equations for the ring forming process are developed in Part 2. Application of the general analysis is made to the specific cases of constrained ring forgings and deformation of a flange during deep drawing in the third part of the series.
An Investigation of the Shell Nosing Process by the Finite-Element Method. Part 2: Nosing at Elevated Temperatures (Hot Nosing)
Authors: Tang Ming-Ching , Kobayashi Shiro
Published: July 2009

The metal-forming processes of shell nosing at elevated temperatures were analyzed by the finite-element method. The strain-rate effects on materials properties and the flow stress dependence on temperatures were included in the finite-element analysis. A thermodynamic theory of visco-plasticity based on rational mechanics was adapted to a rigid-plastic material idealization. An implicit scheme is used for the time integration of heat transfer equations, which is coupled to the plasticity equations. The nine-node quadrilateral elements with quadratic velocity distribution were used for the workpiece, and four-node quadrilateral elements were used for the die in the heat transfer analysis and temperature calculations. The coupled analysis of heat transfer and deformation was applied to the forming of AISI 1045 steel shells. Correlation between simulation and experimental results are good.
Orthonormal Processing of Metals. Part 2: Mixalloying Process
Authors: Suh N. P. , Tsuda N. , Moon M. G. , Saka N.
Published: July 2009

An orthonormal metal processing technique called Mixalloy Process is investigated experimentally. Lead and tin, aluminum and copper, and aluminum and tin were mixed in an impingement mixing chamber and cast in water-cooled copper molds. The microstructure of these Mixalloy products are characterized and compared with those made conventionally.
A Three-Dimensional Model of Surface Asperities Developed Using Moment Theory
Authors: DeVries W. R.
Published: July 2009

Methods are presented to construct a three-dimensional model of a composite surface asperity based on profile measurements taken in different directions. The theory used to accomplish this is based on least squares estimation to find a locus equation for the moment properties measured experimentally in five directions. The asperity model is developed based on this locus of moment properties of height and slope, which are used to interpolate in different directions to generate the base and sides of an asperity. Two examples are used to show how these techniques can be used. One is a face milled cast iron surface and the other a surface ground specimen of low carbon steel.
Catastrophe Theory Models of Chip Formation
Authors: Klamecki B. E.
Published: July 2009

The problem of describing variations in the deformation process in chip formation is considered by constructing two catastrophe theory models of the process. Shear plane chip formation models are studied, in which the shear energy as a function of shear plane orientation and work-piece deformation along a fixed shear angle is minimized. Both of these formulations result in cusp catastrophes represented as a folded minimum energy surface, i.e., the minimum energy surface is multivalued for some values of the chip formation model parameters. It is argued, that as deformation proceeds, changes in the work material properties move the chip formation state on the energy surface and can produce large-scale deformation behavior changes if the folded region of the surface is encountered.
Measures of Functional Coupling in Design
Authors: Rinderle J. R. , Suh N. P.
Published: July 2009

Algebraic and geometric representations of the general design problem are presented. Quantitative measures of functional coupling in design are developed from this representation which provide valuable insight into the significance of the independence axiom of design. These theoretical measures are applied to Reaction Injection Molding machinery to illustrate the concept of functional independence and the application of quantitative measures of functional coupling.
Nondestructive, Continuous Rapid Measurement and Control of Flock Density
Authors: Semenov V. A. , Hersh S. P. , Mock G. N. , Malstrom C. W.
Published: July 2009

A nondestructive technique for rapidly and continuously measuring the density of flocked fabric was developed and used to continuously monitor an experimental flocking range. A sensing device measured the capacitance of a capacitor when the fabric with adhesive passed through it. This value was saved and compared with the value read when the flocked substrate passed through a second transducer downstream. A process monitoring computer received these signals and output a signal to a strip chart recorder proportional to the mass of flock on the substrate. The recorded signal could then be used to control the uniformity of flock deposition on the substrate.
Interpretation of Loss in Strength and Breaking Elongation of Resin-Treated Cotton Fibers Using Microscopical Technique
Authors: Barghash A. , Seyam A.
Published: July 2009

Interpretation of reduction in strength and breaking elongation of resin-treated cotton fibers using a simple light microscope and swelling agent has been shown. The effect of the three factors, namely, resin pickup, setting temperature, and setting time, has been studied. Shape and location of damage for different treatment conditions have been used to deduce the reasons of reduction in both properties. Treatment stages have been broken down to deduce the contribution of each treatment stage to the reduction in strength and breaking elongation. The results obtained showed that the loss in strength and breaking extension of resin-treated cotton fibers is due to the presence of crosslinks and chemical degradation. This is in full agreement with earlier postulation.
An Upper Bound Approach on Deformation of Two-Phase Materials in Uniaxial Tension
Authors: Tada Y. , Oyane M. , Shima S. , Sato T. , Omura M.
Published: July 2009

Strength and deformation of two-phase materials are investigated by the upper bound approach in relation to the volume fraction of the second-phase particles, yield strength ratio and bond strength between the constituents, shape of the particles, and environmental hydrostatic pressure. The stress-strain curve of a two-phase material is estimated as an application of this method. The calculated results are in good agreement with experimental ones.
Effect of Kinematic Oscillation on Tractive Characteristics of Steel Wheel on Rail
Authors: Kumar S. , Kim Jong S. , Rao D. L. Prasanna , Qian Lixin
Published: July 2009

The effect of kinematic oscillation of a wheel on a rail has been experimentally investigated by using the newly redesigned and improved quarter scale IIT-GMEMD Wheel Rail Simulation Facility. It has been found that unlike the decrease of longitudinal adhesion observed in curve negotiation with a steady angle of attack, the kinematic oscillation at a small oscillation angle seems to actually increase the maximum adhesion levels that can be achieved. This implies that the wheel conicity is slightly beneficial from the point of view of the levels of adhesion that may be achieved. It has also been observed that the condition of the surface in terms of the roughness (>20 μin.) is a more significant parameter influencing degree of adhesion as compared to the influence of kinematic oscillation. Slightly higher roughness seems to increase the adhesion level achieved.
Experimental Investigation of Contact Stresses Between a U.S. Locomotive Wheel and Rail
Authors: Kumar S. , Adenwala Y. S. , Rajkumar B. R.
Published: July 2009

An experimental study of the real contact stresses for U.S. locomotives and rails including the effects of plasticity and wear has been performed under laboratory Hertzian simulation using the IIT-GMEMD wheel-rail simulation facility. Experiments were performed under both traction and braking conditions to account for differences observed earlier in the two modes. Wheel/rail tests were conducted using adhesion coefficients of 0.02, 0.15, and 0.25. Average contact stresses for various stages of wear were determined by measuring the contact areas. A synthesis of all the data generated showed that for operation of purely tractive wheels of a typical U.S. locomotive on a rail, the stabilized average contact stress ranges from approximately 100 to 25 ksi as the continuous operating adhesion coefficient ranges from 0 to 0.25. In order to determine the contact stresses for locomotives under field conditions, measurements of contact stresses were made on three different locomotives with wheels of different degrees of wear. Contact stresses for locomotives were found to be higher than stabilized contact stresses established by laboratory simulation tests. The locomotive wheel contact stresses were found to be closer to freight car wheel stabilized contact stresses established in an earlier study than for the laboratory locomotive simulation. It is suggested that this is due to the fact that 20 to 50 times as many cars operate on the same rails as do locomotives. On the basis of these experiments it is recommended that for U.S. locomotive wheels an average stabilized contact stress of approximately 65 ksi rather than the current 138 ksi would be quite stable. Profile and dynamic stability should be achieved simultaneously in such an approach. Currently available 2-D theories have been used to compare the experimental data showing poor agreement and reasons for discrepancy.
Dynamic Performance of Single-Axle Freight Trucks
Authors: Wormley D. N. , Tombers P. A.
Published: July 2009

An analysis has been developed to evaluate the stability of freight cars employing single-axle freight trucks. The analysis has been used to evaluate the influence of wheel/track contact geometry, suspension stiffness, and loading on truck stability. Field data resulting from measurement of a prototype car lateral axle accelerations have been used to identify car critical speeds as a function of suspension stiffness and loading. These data have agreed closely with the analytical calculations and provided a basis for selection of car design parameters to achieve desired values of critical speed.
Two-Dimensional Stock Cutting Problems and Solution Methodologies
Authors: Sarin S. C.
Published: July 2009

In this paper methodologies available in the literature to solve two-dimensional stock cutting problems are reviewed. Several variations of the problem are discussed. An interactive optimization procedure for a general two-dimensional stock cutting problem is introduced.
Analysis of the Rolling Process Assuming Materials Described by Hyperbolic Sine Law
Authors: Lee Y. S. , Smith L. C.
Published: July 2009

An analysis of the rolling process is performed presuming rate dependent materials described by the hyperbolic sine law which represents the low and medium stress levels. The materials described by the power law illustrate the deviation from actual creep behavior in the region of small creep rates. The assumptions employed in the analysis are consistent with assumptions commonly used in the analysis of the rolling process. The vertical and horizontal stress distribution in the roll gap for various Coulomb friction coefficients are obtained by solving the VonKarman equilibrium equation. The intention of the analysis discussed herein is to emphasize the method used to solve the equation defining the rolling process presuming hyperbolic sine law materials rather than to show the practical application of the results obtained from this analysis.
Surface Texture and Machining Conditions. Part 1: Model Building Logic in View of Process Control
Authors: Villa A. , Rossetto S. , Levi R.
Published: July 2009

Surface texture generation in machining processes is examined in view of establishing a model building procedure capable of linking surface finish parameters to machining conditions. In the first part of the paper, with reference to cutting processes with defined tool geometry, a model capable of describing a surface profile as an ordered sequence of tool marks is developed. The use of such a model for process control is also discussed. In the second part, the identification procedure of a model describing profile generation in face milling versus cutting parameters is presented.
The Force in a Die Forging Hammer
Authors: Haller Hans W.
Published: July 2009

The blow of a die forging hammer in its nature and quantity is influenced by the behavior of the forging and its deformation status. In forging, the hammer supplies the energy necessary for plastic deformation as well as the force necessary to coin the forging. The main purpose of this paper is to determine, in hammer forging, how the forces are generated and how the hammer energy is transformed into energies (a) useful for deformation and (b) lost in vibration and noise. Theoretical prediction of the forces is possible by considering the energy balance between the kinetic energy of the ram and the energies used for deformation and lost in rebounding of the ram and the acceleration of the anvil. The results given in this paper show that it is possible to predict at least the upper limits of the generated forces for a given size of an anvil hammer.