bluuebunny/crossref_metadata_2025 huggingface dataset:
Frictional and Thermal Behaviors of Sliding-Rolling Concentrated Contacts
Authors: Ku P. M. , Staph H. E. , Carper H. J.
Published: November 2010

Sliding-rolling disk scuffing tests were conducted over a wide range of sliding and sum velocities, using a straight mineral oil and three aviation gas turbine synthetic oils in combination with two carburized steels and a nitrided steel. Geometrically-similar disks of two different sizes were tested in two different disk testers of nearly similar designs. In addition to disk size and metallurgy, the surface treatment, surface texture, and surface roughness of the disks were also varied. The investigation further covered variations in the oil supply configuration and flow rate. It is shown that the disk friction coefficient is dependent not only on the oil-metal combination, but also on the disk surface treatment and topography as well as the operating conditions. The quasi-steady disk surface temperature and the mean conjunction-inlet oil temperature are shown to be strongly influenced by the frictional power loss at the contact, but not by the specific makeup of the frictional power loss. They are also influenced by the heat transfer from the disks, mainly by convection to the oil and conduction through the shafts, which are dependent on system design and oil flow rate.
Ion-Plated Thin Films for Anti-Wear Applications
Authors: Ohmae N. , Tsukizoe T. , Nakai T.
Published: November 2010

Anti-wear applications of ion-plated thin films have been investigated. Ion-plated films always showed better wear-resistance to fretting than the other vacuum-deposited films. Ion-plated chromium, gold, cadmium, zirconium, and boron carbide films have been effective in the prevention of fretting. Durability-surface was expressed three-dimensionally, and high hardness and large ion-radius were analyzed to be important factors for wear-resistance in air. Adhesion of coatings is critical to wear-resistance. Structures of film, interface, and substrate were studied with transmission and scanning electron microscopes and these all were found to be correlated with a good adhesion of ion-plated films. Microfibrous structure of film, microscopically intricate interface, and lattice defect concentration in substrate caused high adhesive strength of ion-plated films.
Thrust Bearing Characteristics in Impulsively Generated Motion
Authors: Rodkiewicz Cz. M. , Berka V. F.
Published: November 2010

Numerical solution is obtained for the case where the fluid within the lubricating film is initially at rest, however, at time zero the infinitely long slider suddenly assumes a constant velocity. Subsequently, the velocity and pressure fields are generated yielding time dependent load capacity. The time history of these quantities is presented in a graphical form.
Variables Influencing Degradation of SiC Abrasive Papers
Authors: Sugishita Junji , Imura Takashi , Fujiyoshi Syonoshin
Published: November 2010

Using a reciprocating friction machine in which different loads and different speeds for each stroke, the rate of detached grits separated from cementing resin base, metal removal rate and mean sizes of detached grits were investigated under various friction conditions. The degradation of 600-grade SiC abrasive papers were discussed in terms of fatigue deformation of cementing resin. Main results are: 1) Under the reciprocating friction, the rate of detached grits increased in proportion to frictional force amplitude under low load condition. 2) In comparison between one-way friction and the reciprocating, higher wear rate were obtained under the reciprocating. It is considered to be a difference of fatigue strength of the resin for completely reversed stress and pulsating stress.
Friction and Wear of Sintered Cast Iron Products
Authors: Sharma C. S. , Matsunaga M. , Nakagawa T. , Takeuchi E. , Kojima Y.
Published: November 2010

Recently developed sintered cast iron products from cast iron swarf powder have been examined for its application to plain bearing. In this paper, the mechanical properties related to bearing performance, and its friction and wear characteristics, have been described. Several conditions such as porous material impregnated with oil, high density material in dry running, and the cast iron sintered material with certain amount of added graphite are investigated. In most of the cases, the material sintered from cast iron powder either with or without added graphite is found to have good antifriction properties.
Experimental Investigation of Slider Gas Bearings With Ultra-Thin Films
Authors: Sereny Aron , Castelli Vittorio
Published: November 2010

The experimental investigation described here involves the highly accurate measurement of bearing clearances on the order of 0.25 μm in self-acting, pivoted, narrow-slider gas bearings. The experimental measurements are based on light interferometry using a variable-wavelength pulsed dye laser and a CW HeNe laser as monochromatic sources. The light interference in the gas bearing is obtained by flying the slider on a very precise, optically flat quartz disk through which the light beam is transmitted. The combined effect of high Knudsen numbers and surface irregularities on the flying height of narrow gas bearings is observed by varying the load on the bearing and the ambient molecular mean free path. The experimentally measured bearing clearances are compared quantitatively with theoretical predictions obtained by numerical solution of Reynolds differential equation for compressible fluids with slip boundary conditions.
Heat Transfer Characteristics of a Porous Thrust Bearing
Authors: Gorla Rama Subba Reddy
Published: November 2010

The effect of mass injection on the heat generated due to viscous dissipation in a porous thrust bearing is investigated analytically by solving the governing boundary layer equations. Numerical results are given for the velocity and temperature distributions as well as the wall derivatives of the velocity and temperature functions. The range of Prandtl numbers investigated was from 0.7 to 10 and the cross flow Reynolds number was varied from 0.001 to 50.
Some Experiments on Instability of Rotors Supported in Fluid-Film Bearings
Authors: Tonnesen J. , Lund J. W.
Published: November 2010

Experiments are conducted on two rotors, weighing 40 and 187.5 kg, respectively, and supported in cylindrical bearings with two axial grooves. The journal position in the bearing is measured by built-in capacitance displacement probes, and the dynamic behavior is monitored by pressure probes. The self-excited whirl at the threshold speed of instability, as well as the influence of unbalance on the whirl frequency, is investigated in detail. By adding damping at the supports, the heavier rotor is stabilized and operated up to 330 Hz. Correlation with theoretical predictions is presented.
Wear-Related Topography of Ion-Bombarded Surfaces
Authors: Sturges D. J. , Martin S. W. , Jones C. K.
Published: November 2010

Experimental data on surface topographical properties are presented for case-hardened materials which had been nitrided by both the glow discharge and ammonia gas processes. Included are the effects of growth, sputtering, nitriding exposure time, and initial surface conditions. Digital encoding equipment has been built to gather and store the large quantity of profilometer data needed to describe surface properties, for subsequent computer analysis. Results are given of these analyses, yielding parameters such as peak densities and radii, and composite indices derived from these parameters, governing lubrication regime, type of asperital deformation, and microcontact area and density. The data show that both nitriding time and initial roughness are significant in determining the relative merits of the final surfaces for friction and wear. Examples are also given of scanning electron microscope photographs of the same surfaces, revealing a texture beyond the resolving power of a profilometer. This is not expected to exercise a major influence on wear characteristics.
Finite Element and Finite Difference Methods in Engineering
Authors: Perrone N.
Published: November 2010

By means of a simple example, a stretched string under transverse load, finite element and finite difference methods which are so widely used in engineering are illustrated. The finite element method is shown to be an essentially modified Raleigh-Ritz procedure. The finite difference technique is applied directly to the string differential equation; an energy related approach is also discussed. The manner in which a combination finite element/finite difference solution can be effected for the same physical problem is treated. Application of both the finite element and finite difference methods to more complex problems as well as selected programs and depositories are mentioned.
On Some Aspects of Unsteady Aerodynamics and Vortex Induced Oscillations of Elliptic Cylinders at Subcritical Reynolds Number
Authors: Modi V. J. , Ieong L.
Published: November 2010

The paper presents results of an extensive test program aimed at better understanding of unsteady aerodynamics and vortex induced oscillations of a family of two dimensional elliptic cylinders in the Reynolds number range of 3 × 104 – 105. In the beginning, results on Strouhal number variation with cylinder eccentricity and angle of attack are presented which can be used to predict critical resonant velocity once the structural properties are identified. This is followed by the data on the fluctuating pressure at the surface of the cylinders which suggest their three dimensional character and significant dependence on the Reynolds number. However, the unsteady, sectional lift coefficient, obtained through integration of the pressure data, is virtually independent of the spanwise location. The correlation of phase between unsteady pressure signals along the span showed parabolic character of the vortexline at zero angle of attack of the model, but the vortexline tends to be straight and its alignment with the model improves as the angle of attack increases. On the other hand, the presence of end gaps (between the model and tunnel walls) results in a parabolic vortexline at all angles of attack. During the vortex excited oscillations, the familiar ‘capture’ phenomenon is exhibited where the vortex shedding frequency is controlled by the cylinder vibration over a finite range of wind velocity. Detailed measurements of cylinder and Strouhal frequencies, displacement amplitude and phase angle as functions of wind velocity, cylinder eccentricity and angle of attack provide information which should prove useful during design of such structural members.
Experimental and Analytical Investigation of Squeeze Film Bearing Damper Forces Induced by Offset Circular Whirl Orbits
Authors: Bansal P. N. , Hibner D. H.
Published: November 2010

A basic research program was conducted to investigate the hydrodynamic forces of a squeeze film bearing damper. These forces were induced by controlled offset circular whirl orbits of the damper journal. The orbits were mechanically produced by eccentric damper rings and cams in a specially designed, end sealed test rig. Aircraft engine damper geometry and operating conditions were simulated. The instantaneous circumferential pressure profiles, for specific orbits, were measured by eight high response pressure transducers. From these data, twelve composite pressure plots were developed; each was numerically integrated to determine the damper forces corresponding to every 30 deg position of the damper center, i.e., 0–360 deg. The variations in oil film thickness data were monitored via two proximity probes. A numerical method which uses the proximity test data and the damper geometry to calculate the instantaneous values of damper center eccentricity (e), phase angle (φ), radial velocity (e˙), and whirl velocity (φ˙) is presented. These test values are required to compare theory with test. Since the data reduction for offset orbits is extremely complicated, this simple method was found to be very useful in analyzing the test results. Test results for pressure profiles as well as damper forces were compared with theoretical predictions. Agreement was good. The analysis is based on “long bearing” solution of Reynolds equation and includes the effect of inlet and cavitation pressures. For the cavitated oil film, inlet pressure was shown to have important effect on damper forces.
A Computer-Aided Feel Cam Design
Authors: Han J. T.
Published: November 2010

Developing a cam to provide a feel or feedback, based on balancing of various forces and torques and spring energy conservation of the system.
Random Excitation of a Nonlinear Vibration Neutralizer
Authors: Masri S. F. , Stott S. J.
Published: November 2010

An approximate analytical solution is obtained for the stationary response of a highly nonlinear auxiliary mass damper (a dynamic vibration neutralizer with motion-limiting stops) attached to an oscillator that is subjected to random excitation. Experimental measurements with an electronic analog computer and numerically simulated solutions generated by means of a digital computer verify the findings. Results are given for the power spectral density and root-mean-squared level of the response. The effects of various damper parameters on the response of the primary system are determined. The nonlinear damper under consideration is shown to be significantly more effective than the conventional dynamic vibration neutralizer in controlling the response of systems subjected to random excitation.
Technology Transfer in the Determination of Torque Characteristics of Instrument Ball Bearings at High Speeds with Radial and Axial Loads
Authors: Mabie H. H.
Published: November 2010

Torque-speed curves are presented for R2, R2-6, R156, R166, R188, R3, and R4 ball bearings with various combinations of radial and axial loads with oil and with grease lubrication. These curves have been selected from papers previously published by the author and from theses by R. S. Rodgers and K. C. Korby. The curves are reproduced with permission from the Americn Society of Lubrication Engineers and from Virginia Polytechnic Institute and State University.
The Horizontal Plate Filter as a Torsional Vibration System With Vibration Absorption
Authors: Habeck R.
Published: November 2010

Filter cake is removed from the plates of a horizontal plate filter by means of torsional vibrations of the plates. For good vibration isolation from the surrounding objects the application of a new vibration absorber technique is suggested for the vibrational design of the apparatus. The design includes the consideration of damping forces between cake and plates. The theoretical results are confirmed by experiments with a simplified model.
Performance Criteria for High-Speed Crank-and-Rocker Linkages—Part II: Spherical Crank-and-Rocker Linkages
Authors: Funabashi H. , Freudenstein F.
Published: November 2010

In Part I proportions were derived for high-speed plane crank-and-rocker mechanisms. In this part, the corresponding developments are given for spherical crank-and-rocker mechanisms. The ratios of the sine functions of the transmission angles and of the rocker accelerations—both at the dead-center positions—remain the static and dynamic performance criteria of the linkage. The results are illustrated by numerical examples, which show the influence of these ratios on the transmission-angle variation, rocker acceleration and the ratio of minimum to maximum link length.
On Velocity Fluctuation in Skew Four-Bar Mechanisms
Authors: Pamidi P. R.
Published: November 2010

Velocity fluctuations in skew four-bar mechanisms with a simple skew (that is, skew four-bar mechanisms in which the planes of the crank circles intersect the common perpendicular between the crank axes) have been investigated by algebraic means and the conditions for the existence of extreme values of velocity ratio have been obtained. The results are general in nature and make it possible to obtain the extreme values of velocity ratio of any given simply skewed four-bar mechanism. The method of the paper has been illustrated by several numerical examples. The results can also be used to synthesize simply skewed four-bar mechanisms with prescribed extreme values of velocity ratio.
The Elastic-Dynamic Behavior of a Counterweighted Rocker Link with an Overhanging Endmass in a Four-Bar Linkage—Part II: Application and Experiment
Authors: Jandrasits W. G. , Lowen G. G.
Published: November 2010

This paper presents Part II of a two-part investigation dealing with the damped elastic behavior of the counterweighted rocker link of a four-bar linkage which also carries an overhanging mass. The analytical techniques developed in Part I are applied to an example mechanism and the results are compared to those of an associated experiment. Three mode solutions of decoupled Hill’s equations furnish a stability analysis as well as steady state solutions for strain responses at off- and on-resonance locations over a range of speeds from 100 to 200 rpm. In general, good qualitative as well as quantitative agreement between analytical and experimental results was found.
Topological Reaction Force Analysis
Authors: Milner J. R. , Smith D. A.
Published: November 2010

A method of using directed linear graphs for the determination of reaction forces in dynamic mechanical systems is developed. The method is compatible with other more classical techniques for calculating reaction forces and results in a more efficient computational approach than alternative methods. Example problems are discussed and analyzed using these topological techniques.
A Contour Plotting Scheme for Design Optimization
Authors: Afimiwala K. A. , Mayne R. W.
Published: November 2010

A procedure is developed for drawing contours of an objective function and constraints in two dimensions. Polynomial expressions are first obtained for the design objective and the constraints. Then a non-parametric curve generation technique is used to draw approximate contours. By superimposing the constraints on the contour plots the feasible design region is readily identified, and the 2-D minimum can be located by inspection. Contours are obtained for some typical applications to illustrate the effectiveness of the method. Problems with more than two design variables can be approached by considering various 2-D views of the design space.
Structural Analysis of Kinematic Chains and Mechanisms Based on Matrix Representation
Authors: Mruthyunjaya T. S. , Raghavan M. R.
Published: November 2010

A method based on Bocher’s formulae has been presented for determining the characteristic coefficients (which have recently been suggested [19] as an index of isomorphism) of the matrix associated with the kinematic chain. The method provides an insight into the physical meaning of these coefficients and leads to a possible way of arriving at the coefficients by an inspection of the chain. A modification to the matrix notation is proposed with a view to permit derivation of all possible mechanisms from a kinematic chain and distinguishing the structurally distinct ones. Algebraic tests are presented for determining whether a chain possesses total, partial or fractionated freedom. Finally a generalized matrix notation is proposed to facilitate representation and analysis of multiple-jointed chains.
Chebychev Approximations of Spatial Point Sets Using Spheres and Planes
Authors: Sarkisyan Y. L. , Gupta K. C. , Roth B.
Published: November 2010

The main problem considered is that of determining spheres which best approximate given sets of spatial points. The spheres sought are best in the sense of having the minimum-maximum radial distance from the points to be approximated. Configuration of the points with respect to the best spheres is discussed in detail. Related results are also obtained for the approximation of points by planes.
Global Non-Iterative Design Optimization Using Monotonicity Analysis
Authors: Papalambros P. , Wilde D. J.
Published: November 2010

The numerical techniques used in conventional optimization may not work for engineering design problems, which often present peculiar difficulties. Monotonicity analysis can identify a global optimum without any special computations and also prevent acceptance of false solutions generated by the numerical techniques. In the present paper, these advantages are demonstrated in a problem taken from the literature, for which diverse numerical solutions have been obtained. Monotonicity analysis identifies and proves the global optimum. Its application may require some algebraic rearrangement of the problem statement.
A Point of View in Large Flanges Analysis
Authors: Paraschivescu M.
Published: November 2010

The paper introduces an analytical method for computing large flanges and an analog computer pattern for their simulation. Chapter I summarizes previous works in the field (Waters, et al., Murray and Stuart) to which a new analysis of the flange ring is proposed. Chapters II and III present EA C-technique of simulating stress-displacement dependence of a flange under external loads.
Effect of Relative Mean Strain in High-Temperature Low-Cycle Fatigue of a Stainless Steel
Authors: Bui-Quoc Thang , Biron Andre
Published: November 2010

The effect of the relative mean strain in the low-cycle fatigue of a stainless steel (AISI 304) in air at 650°C and at a constant strain rate (4 × 10−3s−1) is studied. Two modes of strain measurement (axial and diametral) were used separately in nonzero mean strain experiments with controlled axial strain in real time. The effect of the relative mean strain on the fatigue life has been found to be negligible in the range of lives 200 ⩽ N ⩽ 10,000 cycles when the mean strain does not exceed 1.5 times the total range. This effect, however, becomes important when the mean strain is several times the total strain range. In addition, for N < 200 cycles at failure, the effect of even a small value of the mean strain appears to be significant. The extension of a method previously developed is presented for establishing the high-temperature fatigue behavior under isothermal conditions with positive mean strain. On the basis of the results of a short-term tensile test, the technique gives predictions in good agreement with experimental data.
Hydrodynamic Inertia Coefficients for a Tube Surrounded by Rigid Tubes
Authors: Moretti P. M. , Lowery R. L.
Published: November 2010

The virtual mass of a long, transversely vibrating tube submerged in a liquid was experimentally determined. The tube was surrounded by rigid tubes in a hexangular array and in square array, at pitch-to-diameter ratios from 1.25 to 1.5. The inertia coefficients observed were considerably larger than for a cylinder in an infinite volume of fluid, but smaller than one would compute assuming an annulus inscribed within the clear space around the vibrating tube. The results show the reduction of natural frequencies in a submerged tube bundle for one particular relative motion of tubes. Experimental results concerning the increase in damping due to the surrounding tubes are briefly indicated.
Techniques of Pilot-Scale Drilling Research
Authors: Estes Jack C.
Published: November 2010

Various phases of drilling research are possible, from tool development (bits, drill strings, percussion drills, downhole motors, etc.), optimization of operating conditions (optimum WT-RPM, bit selection, hydraulics, etc.), to drilling fluids development (fluid loss mud additives, shale stabilization, viscosifiers, etc.). This paper discusses the techniques necessary to conduct pilot-scale, micro-bit drilling research. By employing proper experimental methods, the results of micro-bit research can be applied to the problems associated with the drilling fluids phase of drilling research activities.
Deformation of Polymers During Hydrostatic Extrusion
Authors: Inoue N. , Nakayama T. , Shimono M.
Published: November 2010

Crystalline as well as amorphous polymers and a thermosetting resin were hydrostatically extruded with pressures up to 4 kilobars. A linear relation was obtained between the extrusion pressure and extrusion ratio. Temperature of the billets during the extrusion process was determined, along with the flow pattern of the deformation. Tension tests at the temperature, to which the billet was exposed during the extrusion, was carried out at atmospheric pressure on the high-density polyethylene specimen to supply a theoretical basis to the experimental formula. Effects of temperature and strain rate on the extrusion process are discussed in the light of the temperature-time superposition principle.
Rational and Economical Multicomponent Seismic Design of Piping Systems
Authors: Gupta A. K.
Published: November 2010

The seismic analysis of complex piping systems is often carried out by the response spectrum method. The maximum probable responses are calculated as the square root of the sum of the squares (SRSS) of the responses obtained in various modes of vibration for the three components of earthquake. A coupling matrix is introduced in case of modes with closely spaced frequencies. The ASME strength criterion for the pipes is based on maximum shear stress which can be calculated from the two orthogonal bending moments and the torsional moment acting on the cross section. Strictly speaking, one should know the combination of these three moments acting simultaneously which would give the maximum shear stress at the section being designed. However, the response spectrum method gives the maximum probable values which in general do not occur simultaneously. Often the pipe is conservatively designed as if these probable maximum values were occurring simultaneously. It can be shown that this procedure may overestimate the maximum shear stress by as much as 73 percent. To overcome this problem a new method is applied by which simultaneous variation in the three moments can be predicted to cause the extreme probable effect. The new method is “exact” within the framework of existing procedures and assumptions.
Stresses Around a Rib-Reinforced Elliptic Hole in a Circular Cylindrical Shell Under Tension
Authors: Chou S. I. , Chaudhary Om P.
Published: November 2010

The stress state around a rib reinforced elliptic hole in a circular cylindrical shell under axial tension at its ends is determined by perturbation in terms of a curvature parameter and the eccentricity of the elliptic hole. The reinforcing rib is assumed to be rectangular in cross section, and has extensional, flexural and torsional rigidities. Nondimensional membrane stresses and bending stresses around the hole are given for different values of E1/E1 where E1 and E are moduli of elasticity of the rib and the shell respectively. It is shown that the reinforcing rib substantially reduces the stress concentration around the hole.
Design, Fabrication, and Installation of a Prototype Multiline Marine Production Riser System
Authors: Gammage W. E. , Ortloff J. E. , Teers M. L. , Caldwell J. B.
Published: November 2010

A multiline marine production riser and floating production, storage, and terminal facility may be required for economic development of oil and gas reserves in remote, deep water locations. A deep water production riser design has evolved through study, analyses, and model testing. In order to gain experience, development confidence, and improve the riser design prior to commercial application, a prototype has been built for testing as part of Exxon’s Submerged Production System offshore test in the Gulf of Mexico. This paper treats the design, manufacture, and installation of the prototype multiline marine production riser system.
Minimizing Casing Wear in Dog Legs
Authors: Bradley W. B.
Published: November 2010

Procedures are presented for estimating the amount of casing wear produced in wells by the rotation of tool joints, drill pipe, and drill pipe protectors against casing. The procedures are based upon experimental information and limited field measurements developed over a period of several years [1–5]. The procedures have been used with moderate success in predicting the casing wear rates seen in the field for a limited number of cases. The paper again emphasizes that with the proper use of drill pipe protectors casing wear can be minimized. In addition, the paper presents suggested procedures for selecting drill pipe protectors to assure consistent casing wear performance.
Inner and Outer Cracks in Internally Pressurized Cylinders
Authors: Kobayashi A. S. , Polvanich N. , Emery A. F. , Love W. J.
Published: November 2010

Stress intensity factors of pressurized surface cracks at the internal surface and un-pressurized surface cracks at the external surface of an internally pressurized cylinder are estimated from stress intensity factors of a semi-elliptical crack in a finite-thickness flat plate. Curvature effects of the cylinder are determined by comparing two-dimensional finite element solutions of fixed-grip, single edge-notched plates and single edge-notched cylinders. Stress intensity factors for semi-elliptical cracks with crack aspect ratios of b/a = 0.2 and 0.98 at crack depths up to 80 percent of the cylindrical wall thickness are shown for internally pressurized cylinders with outer to inner diameter ratios, Ro/Ri, ranging from 10:9 to 5:4 for outer surface cracks and to 3:2 for inner surface cracks.
High-Pressure Jet-Drilling Experiments in Some Hard Rocks
Authors: Pols A. C.
Published: November 2010

The potential penetration rates of high-pressure jet bits drilling in hard rocks have been investigated experimentally. It has been found that the rates of penetration are much lower in hard, impermeable rock than in permeable rock [1]. Test results indicate that a laminated rock (Martelange schist) cannot be cut by jets at a high rate, which calls for hybrid bits. Isotropic rock can be jet-drilled at higher than conventional drilling rates, which may become profitable at daily rig costs in excess of approximately $20,000.
Implicit and Explicit Computational Schemes in Dynamic Plasticity
Authors: Zudans Z.
Published: November 2010

The analytical methods described in this paper are designed to handle two classes of problems. The first class is associated with a load history duration of 50 millisec or more (such as light water reactor blowdown transient); the second class is associated with very rapid load application and a response history of about 100 μsec. The first class of problem is solved by using an implicit method of solution, and the second class is solved by an explicit method. The method of solution for both classes of problems is developed with an appropriate consideration of the materials and geometric non-linearities. Material nonlinearities, both for isotropic and kinematic strain hardening, are handled in a novel manner, such that the solution points remain on the materials curve with any degree of accuracy desired. An iterative scheme and a piecewise Lagrangian formulation are used in the analysis.
A Finite Plate Method to Solve Cylinder-to-Cylinder Structures Subjected to Internal Pressure
Authors: Brown S. J.
Published: November 2010

An axisymmetric geometric assumption combined with the use of asymmetric loading conditions is presented as an inexpensive alternative to 3-D geometric stress analysis of a variety of nozzle-to-cylinder structures. The finite plate concept explored by Rodabaugh, is used as the axisymmetric attachment to the nozzle, and both nozzle and plate are idealized by the finite element method. The variable plate parameters are the plate outer radius and the harmonic loading at the outer radius. These parameters are determined by utilizing the shell solution of stresses about a circular hole in a cylinder as data for point matching in a flat plate with a hole. The appropriate plate parameters are determined as a function of the curvature parameter β. Examples comparing 3-D and axisymmetric geometric finite element data are presented which illustrate the method. Finally, a discussion of the applicability and limitations of the method in the analysis of nozzles is presented.
Prediction of Drilling Mud Rheology Using a Simplified Herschel-Bulkley Model
Authors: Zamora M. , Bleier R.
Published: November 2010

Drilling muds are rheologically complex. Models presently used to characterize their behavior are those of Bingham and Ostwald-deWaele (power law). The Herschel-Bulkley model is shown in this paper to be superior, but more difficult to implement with theoretic exactness. However, a simplified approach suitable for field use is developed and compared to rigorous solutions.
Simulation of Sea Ice Dynamics During AIDJEX
Authors: Pritchard R. S. , Coon M. D. , McPhee M. G.
Published: November 2010

A mathematical model is used to simulate sea ice conditions observed during May 15–25, 1975 as part of the Arctic Ice Dynamics Joint Experiment. Calculated motions and forces within the region are compared with observed values. Ice velocity and tractions exerted on the upper and lower ice surface compare well with observed values. Results of another calculation using different boundary layer parameters help assess the effect of boundary layer models on the computed ice drift. The calculated strain field does not compare with observed strains well enough to allow prediction of stress in the pack ice. Several sources of error have been identified for future study.
Stress Response Investigations Related to In-Situ Gasification of Coal
Authors: Advani S. H. , Shuck L. Z. , Lee K. Y.
Published: November 2010

The influence of in-situ stresses and thermal effects on underground gasification of bituminous coals is studied. Evaluations of temperature profiles, stress magnitudes and stress intensity factors are given. The effects of stresses and temperature on coal fracture permeabilities are discussed. In addition, the influence of stress on combustion front stability in thin seams is discussed.
Fatigue Crack Growth of Stainless Steel Piping in a Pressurized Water Reactor Environment
Authors: Bamford W. H.
Published: November 2010

Fatigue crack-growth behavior was investigated for types 304 and 316 stainless steel exposed to a pressurized water reactor environment. The effects of test frequency, stress ratio, specimen orientation, heat to heat variables and weld versus base metal performance were evaluated. Crack-growth rates were correlated with the range of crack-tip stress intensity factor, as well as the “effective stress intensity factor” proposed by Walker to account for R ratio effects. Results of the study showed that fatigue crack-growth rates in the water environment were not significantly different from results at the same stress ratio in an air environment at the same temperature. The most important parameter found to affect the crack-growth rate was the stress ratio R, and increasing values of R produced increased crack-growth rates at any given value of stress intensity factor range ΔK. The stress ratio effects were successfully accounted for by employment of the Walker model.
Energy Release From Rupturing High-Pressure Vessels: A Possible Code Consideration
Authors: Pohto H. A.
Published: November 2010

Seven, one-cu-ft (0.028-m3) pressure vessels were burst with argon gas pressures of 15,000, 30,000, and 50,000 psi (103, 206, and 345 MPa). Curves were plotted depicting TNT equivalents and resulting overpressures. Characteristics of released energies are illustrated from a vessel at 15,000 psi (103 MPa) purposely ruptured within a simulated concrete cell housing. Energies of other media under high pressure are discussed.
A Procedure for Estimating the Stress Intensity Factor of a Flattened Surface Crack at a Nozzle Corner
Authors: Kobayashi A. S. , Emery A. F. , Love W. J. , Antipas A.
Published: November 2010

A flattened surface crack at a nozzle corner is modeled by a segment of a semi-elliptical crack in a finite thickness plate with matching crack contour and crack pressure corresponding to the normal stresses in the uncracked nozzle corner. Lacking other solutions for comparison, a qualitative comparison was made between nondimensionalized stress intensity factors at the deepest crack penetration with those obtained experimentally for similar corner cracks in epoxy models.
Pressure Vessels of Noncircular Cross Section (Commentary on New Rules for ASME Code)
Authors: Faupel J. H.
Published: November 2010

Background information is given relative to Code design procedures for pressure vessels of noncircular cross section. Such vessels have wide application as component parts of air-cooled heat exchangers, duct work, special piping, extrusion chambers and specialty vessels used in laundry and hospital service and heat transfer applications. Present design coverage is for internal pressure only for unreinforced, reinforced and stayed vessels of rectangular and obround cross section.
Modeling cadmium uptake from water and food by the freshwater bivalve Pyganodon grandis
Authors: Cooper Sophie , Hare Landis , Campbell Peter G.C.
Published: November 2010

For this study, the unionid bivalve Pyganodon grandis was either exposed to dissolved cadmium (Cd) or fed Cd-contaminated algae ( Pseudokirchneriella subcapitata ) during short-term laboratory experiments. Cadmium accumulated largely in the digestive gland after a dietary exposure, or in the gills after an aqueous exposure; in these latter experiments, Cd accumulation from the dissolved phase increased as bivalve filtration rates increased. The results of these uptake experiments were used to parameterize a biodynamic model, which was then used to estimate the relative importance of water and food as sources of Cd for this bivalve, and to predict steady state Cd concentrations in the gills and digestive gland of native bivalves. In comparisons between the simulations and data obtained from earlier field studies on P. grandis, the model adequately predicted Cd concentrations in P. grandis gills, except in Ca-rich lakes, whereas it tended to overestimate Cd concentrations in the digestive gland. The field simulations indicate that water is the main source of Cd for both the gills (relative importance water:food::99:1) and the digestive gland (water:food::80:20). These results will facilitate the interpretation of spatial and temporal variations in Cd concentrations in free-living P. grandis, which is a promising metal biomonitor.
Effects of nitrogen additions on nitrogen resorption and use efficiencies and foliar litterfall of six tree species in a mixed birch and poplar forest, northeastern China
Authors: Li Xuefeng , Zheng Xingbo , Han Shijie , Zheng Junqiang , Li Tonghua
Published: November 2010

We studied nitrogen (N) resorption efficiencies (NRE), N use efficiencies (NUE), carbon-to-nitrogen ratios of green (C:Ngreen) and senesced (C:Nsenesced) foliage, and foliar litterfall for six tree species under three N treatments (control, no N addition; low N addition, 2.5 g N·m–2·year–1; and high N addition, 5.0 g N·m–2·year–1) in a mixed birch and poplar forest in northeastern China in 2007 and 2008. N additions were initiated in 2006. NRE, NUE, C:Ngreen, and C:Nsenesced were significantly decreased by N additions and tended to decrease with increasing N addition treatments. N additions significantly increased foliar litterfall of Acer mono Maxim., Betula platyphylla Sukatschev, Pinus koraiensis Siebold & Zucc., and Populus davidiana Dode and slightly altered litterfall of Fraxinus mandschurica Rupr. and Populus koreana Rehder. High N addition changed foliar litterfall of A. mono, F. mandschurica, P. davidiana, and P. koreana more than low N addition, whereas an opposite pattern was found for B. platyphylla and P. koraiensis. Our study showed that foliar litterfall responses to N additions varied among tree species, but this could not be predicted by the interspecific differences in NRE, NUE, C:Ngreen, and C:Nsenesced under each of the three N treatments.
ON THE BALANCE ENERGY AND NUCLEAR DYNAMICS IN PERIPHERAL HEAVY-ION COLLISIONS
Authors: CHUGH RAJIV , PURI RAJEEV K.
Published: November 2010

We present here the system size dependence of balance energy for semi-central and peripheral collisions using quantum molecular dynamics model. For this study, the reactions of Ne 20+ Ne 20, Ca 40+ Ca 40, Ni 58+ Ni 58, Nb 93+ Nb 93, Xe 131+ Xe 131, and Au 197+ Au 197 are simulated at different incident energies and impact parameters. A hard equation of state along with nucleon–nucleon cross-sections between 40 and 55 mb explains the data nicely. Interestingly, balance energy follows a power law ∝Aτ for the mass dependence at all colliding geometries. The power factor τ is close to [Formula: see text] in central collisions, whereas it is [Formula: see text] for peripheral collisions suggesting stronger system size dependence at peripheral geometries. This also suggests that in the absence of momentum dependent interactions, Coulomb's interaction plays an exceedingly significant role. These results are further analyzed for nuclear dynamics at the balance point.
NEAR-INFRARED, BROAD-BAND SPECTRAL IMAGING OF THE HUMAN BREAST FOR QUANTITATIVE OXIMETRY: APPLICATIONS TO HEALTHY AND CANCEROUS BREASTS
Authors: YU YANG , SASSAROLI ANGELO , CHEN DEBBIE K. , HOMER MARC J. , GRAHAM ROGER A. , FANTINI SERGIO
Published: November 2010

We have examined ten human subjects with a previously developed instrument for near-infrared diffuse spectral imaging of the female breast. The instrument is based on a tandem, planar scan of two collinear optical fibers (one for illumination and one for collection) to image a gently compressed breast in a transmission geometry. The optical data collection features a spatial sampling of 25 points/cm2 over the whole breast, and a spectral sampling of 2 points/nm in the 650–900 nm wavelength range. Of the ten human subjects examined, eight are healthy subjects and two are cancer patients with unilateral invasive ductal carcinoma and ductal carcinoma in situ, respectively. For each subject, we generate second-derivative images that identify a network of highly absorbing structures in the breast that we assign to blood vessels. A previously developed paired-wavelength spectral method assigns oxygenation values to the absorbing structures displayed in the second-derivative images. The resulting oxygenation images feature average values over the whole breast that are significantly lower in cancerous breasts (69 ± 14%, n = 2) than in healthy breasts (85 ± 7%, n = 18) (p < 0.01). Furthermore, in the two patients with breast cancer, the average oxygenation values in the cancerous regions are also significantly lower than in the remainder of the breast (invasive ductal carcinoma: 49 ± 11% vs 61 ± 16%, p < 0.01; ductal carcinoma in situ: 58 ± 8% vs 77 ± 11%, p < 0.001).
LABEL-FREE 3D OPTICAL MICROANGIOGRAPHY IMAGING OF FUNCTIONAL VASA NERVORUM AND PERIPHERAL MICROVASCULAR TREE IN THE HIND LIMB OF DIABETIC MICE
Authors: JIA YALI , BAUMANN THOMAS K. , WANG RUIKANG K.
Published: November 2010

Diabetic neuropathy (DN) is, at least in part, associated with the functional attenuation of vasa nervorum, the microvascular structure of peripheral nerves. Microvascular imaging options for vasa nervorum still remain limited. In this work, optical microangiography (OMAG), a volumetric, label-free imaging technique, is utilized for characterizing, with high resolution, blood perfusion of peripheral nerve in diabetic mice. We demonstrate that OMAG is able to visualize the structure of microvasculature and to quantify the changes of dynamic blood flow and vessel diameters during administration of vessel stimulant in both diabetic and normal mice. The results indicate the potential of OMAG to assess the blood supply of nerve involved in the pathology and treatment of DN.
A mixed reality approach for interactively blending dynamic models with corresponding physical phenomena
Authors: Quarles John , Fishwick Paul , Lampotang Samsun , Fischler Ira , Lok Benjamin
Published: November 2010

The design, visualization, manipulation, and implementation of models for computer simulation are key parts of the discipline. Models are constructed as a means to understand physical phenomena as state changes occur over time. One issue that arises is the need to correlate models and their components with the phenomena being modeled. For example, a part of an automotive engine needs to be placed into cognitive context with the diagrammatic icon that represents that part's function. A typical solution to this problem is to display a dynamic model of the engine in one window and the engine's CAD model in another. Users are expected to, on their own, mentally blend the dynamic model and the physical phenomenon into the same context. However, this contextualization is not trivial in many applications.

Our approach expands upon this form of user interaction by specifying two ways in which dynamic models and the corresponding physical phenomena may be viewed, and experimented with, within the same human interaction space. We present a methodology and implementation of contextualization for diagram-based dynamic models using an anesthesia machine, and then follow up with a human study of its effects on spatial cognition.
Bacterial Antisense RNAs: How Many Are There, and What Are They Doing?
Authors: Thomason Maureen Kiley , Storz Gisela
Published: November 2010

Antisense RNAs encoded on the DNA strand opposite another gene have the potential to form extensive base-pairing interactions with the corresponding sense RNA. Unlike other smaller regulatory RNAs in bacteria, antisense RNAs range in size from tens to thousands of nucleotides. The numbers of antisense RNAs reported for different bacteria vary extensively, but hundreds have been suggested in some species. If all of these reported antisense RNAs are expressed at levels sufficient to regulate the genes encoded opposite them, antisense RNAs could significantly impact gene expression in bacteria. Here, we review the evidence for these RNA regulators and describe what is known about the functions and mechanisms of action for some of these RNAs. Important considerations for future research as well as potential applications are also discussed.
From Zebrafish to Mammal: Functional Evolution of Prestin, the Motor Protein of Cochlear Outer Hair Cells
Authors: Tan Xiaodong , Pecka Jason L. , Tang Jie , Okoruwa Oseremen E. , Zhang Qian , Beisel Kirk W. , He David Z. Z.
Published: November 2010

Prestin is the motor protein of cochlear outer hair cells. It belongs to a distinct anion transporter family called solute carrier protein 26A, or SLC26A. Members of this family serve two fundamentally distinct functions. Although most members transport different anion substrates across a variety of epithelia, prestin (SLC26A5) is unique, functioning as a voltage-dependent motor protein. Recent evidence suggests that prestin orthologs from zebrafish and chicken are electrogenic divalent/chloride anion exchangers/transporters with no motor function. These studies appear to suggest that prestin was evolved from an anion transporter. We examined the motor and transport functions of prestin and its orthologs from four different species in the vertebrate lineage, to gain insights of how these two physiological functions became distinct. Somatic motility, voltage-dependent nonlinear capacitance (NLC), and transporter function were measured in transfected human embryonic kidney (HEK) cells using voltage-clamp and anion uptake techniques. Zebrafish and chicken prestins both exhibited weak NLC, with peaks significantly shifted in the depolarization (right) direction. This was contrasted by robust NLC with peaks left shifted in the platypus and gerbil. The platypus and gerbil prestins retained little transporter function compared with robust anion transport capacities in the zebrafish and chicken orthologs. Somatic motility was detected only in the platypus and gerbil prestins. There appears to be an inverse relationship between NLC and anion transport functions, whereas motor function appears to have emerged only in mammalian prestin. Our results suggest that motor function is an innovation of therian prestin and is concurrent with diminished transporter capabilities.