bluuebunny/crossref_metadata_2025 huggingface dataset:
The elementary force generation process probed by temperature and length perturbations in muscle fibres from the rabbit
Authors: Bershitsky Sergey Y. , Tsaturyan Andrey K.
Published: July 2002

Single chemically permeabilized fibres from rabbit psoas muscle were activated maximally at 5–6 °C and then exposed to a rapid temperature increase (‘T‐jump’) up to 37 °C by passing a high‐voltage pulse (40 kHz AC, 0.15 ms duration) through the fibre length. Fibre cooling after the T‐jump was compensated by applying a warming (40 kHz AC, 200 ms) pulse. Tension and changes in sarcomere length induced by the T‐jumps and by fast length step perturbations of the fibres were monitored. In some experiments sarcomere length feedback control was used. After T‐jumps tension increased from ∼55 kN m−2 at 5–6 °C to ∼270 kN m−2 at 36–37 °C, while stiffness rose by ∼15 %, suggesting that at a higher temperature the myosin head generates more force. The temperature‐tension relation became less steep at temperatures above 25°C, but was not saturated even at near‐physiological temperature. Comparison of tension transients induced by the T‐jump and length steps showed that they are different. The T‐jump transients were several times slower than fast partial tension recovery following length steps at low and high temperature (phase 2). The kinetics of the tension rise after the T‐jumps was independent of the preceding length changes. When the length steps were applied during the tension rise induced by the T‐jump, the observed complex tension transient was simply the sum of two separate responses to the mechanical and temperature perturbations. This demonstrates the absence of interaction between these processes. The data suggest that tension transients induced by the T‐jumps and length steps are caused by different processes in myosin cross‐bridges.
Formaldehyde Formation in Large Bore Engines Part 2: Factors Affecting Measured CH2O
Authors: Olsen Daniel B. , Mitchell Charles E.
Published: July 2002

Current research shows that the only hazardous air pollutant of significance emitted from large bore natural gas engines is formaldehyde CH2O. A literature review on formaldehyde formation is presented focusing on the interpretation of published test data and its applicability to large bore natural gas engines. The relationship of formaldehyde emissions to that of other pollutants is described. Formaldehyde is seen to have a strong correlation to total hydrocarbon (THC) level in the exhaust. It is observed that the ratio of formaldehyde to THC concentration is roughly 1.0–2.5 percent for a very wide range of large bore engines and operating conditions. The impact of engine operating parameters, load, rpm, spark timing, and equivalence ratio, on formaldehyde emissions is also evaluated. [S0742-4795(00)01004-8]
Dynamic Absorption by Passive and Active Control1
Authors: Singh Kumar Vikram , Ram Yitshak M.
Published: July 2002

The motion of a particular degree-of-freedom in a harmonically excited conservative system can be vanished by attaching an appropriate dynamic absorber to it. It is shown here that under certain conditions, which are characterized in the paper, the steady state motion of a damped system may be completely absorbed, without loss of stability, by active control implementing a single sensor and an actuator. The results are established theoretically and they are demonstrated by means of analytical examples. [S0739-3717(00)02104-8]
Combinations for the Free-Vibration Behaviors of Anisotropic Rectangular Plates Under General Edge Conditions
Authors: Narita Y.
Published: July 2002

The free-vibration behavior of rectangular plates constitutes an important field in applied mechanics, and the natural frequencies are known to be primarily affected by the boundary conditions as well as aspect and thickness ratios. Any one of the three classical edge conditions, i.e., free, simply supported, and clamped edges, may be used to model the constraint along an edge of the rectangle. Along the entire boundary with four edges, there exist a wide variety of combinations in the edge conditions, each yielding different natural frequencies and mode shapes. For counting the total number of possible combinations the present paper introduces the Polya counting theory in combinatorial mathematics. Formulas are derived for counting the exact numbers. A modified Ritz method is then developed to calculate natural frequencies of anisotropic rectangular plates under any combination of the three classical edge conditions and is used to numerically verify the numbers. In this numerical study the number of combinations in the free-vibration behavior is determined for some plate models by using the derived formulas. Results are corroborated by counting the numbers of different sets of the natural frequencies that are obtained from the modified Ritz method. [S0021-8936(00)02203-0]
Heat Transfer Coefficient in Rapid Solidification of a Liquid Layer on a Substrate
Authors: Wei P. S. , Yeh F. B.
Published: July 2002

The heat transfer coefficient at the bottom surface of a splat rapidly solidified on a cold substrate is self-consistently and quantitatively investigated. Provided that the boundary condition at the bottom surface of the splat is specified by introducing the obtained heat transfer coefficient, solutions of the splat can be conveniently obtained without solving the substrate. In this work, the solidification front in the splat is governed by nonequilibrium kinetics while the melting front in the substrate undergoes equilibrium phase change. By solving one-dimensional unsteady heat conduction equations and accounting for distinct properties between phases and splat and substrate, the results show that the time-dependent heat transfer coefficient or Biot number can be divided into five regimes: liquid splat-solid substrate, liquid splat-liquid substrate, nucleation of splat, solid splat-solid substrate, and solid splat-liquid substrate. The Biot number at the bottom surface of the splat during liquid splat cooling increases and nucleation time decreases with increasing contact Biot number, density ratio, and solid conductivity of the substrate, and decreasing specific heat ratio. Decreases in melting temperature and liquid conductivity of the substrate and increase in latent heat ratio further decrease the Biot number at the bottom surface of the splat after the substrate becomes molten. Time-dependent Biot number at the bottom surface of the splat is obtained from a scale analysis. [S0022-1481(00)01004-5]
How Is a Tissue Built?1
Authors: Cowin Stephen C.
Published: July 2002

Tissues change in many ways in the period that they are part of a living organism. They are created in fairly repeatable structural patterns, and we know that the patterns are due to both the genes and the (mechanical) environment, but we do not know exactly what part or percentage of a particular pattern to consider the genes, or the environment, responsible for. We do not know much about the beginning of tissue construction (morphogenesis) and we do not know the methods of tissue construction. When the tissue structure is altered to accommodate a new loading, we do not know how the decision is made for the structural reconstruction. We do know that tissues grow or reconstruct themselves without ceasing to continue with their structural function, but we do not understand the processes that permit them to accomplish this. Tissues change their structures to altered mechanical environments, but we are not sure how. Tissues heal themselves and we understand little of the structural mechanics of the process. With the objective of describing the interesting unsolved mechanics problems associated with these biological processes, some aspects of the formation, growth, and adaptation of living tissues are reviewed. The emphasis is on ideas and models. Beyond the objective is the hope that the work will stimulate new ideas and new observations in the mechanical and chemical aspects of developmental biology. [S0148-0731(00)00106-0]
A Mechanistic Cutting Force Model for 3D Ball-end Milling
Authors: Feng Hsi-Yung , Su Ning
Published: July 2002

This paper presents an improved mechanistic cutting force model for the ball-end milling process. The objective is to accurately model the cutting forces for nonhorizontal and cross-feed cutter movements in 3D finishing ball-end milling. Main features of the model include: (1) a robust cut geometry identification method to establish the complicated engaged area on the cutter; (2) a generalized algorithm to determine the undeformed chip thickness for each engaged cutting edge element; and (3) a comprehensive empirical chip-force relationship to characterize nonhorizontal cutting mechanics. Experimental results have shown that the present model gives excellent predictions of cutting forces in 3D ball-end milling.
The Effect of Mean Turbulent Strain Rate on the Flame Speed of Premixed, Growing Flames
Authors: Ting D. S.-K. , Checkel M. D.
Published: July 2002

This paper presents a flame growth model based on experimental measurements of flame speed and mean turbulent strain rate. Methane/air mixtures of 0.7 and 0.9 equivalence ratios were centrally spark-ignited in a 125 mm cubical chamber. Based on schlieren images and combustion pressure traces, a linear correlation was found between the turbulent flame speed and the turbulent strain rate. For these unity-Lewis-number and near-zero-Markstein-number flames, the effectiveness of turbulent strain in enhancing the flame speed was found to increase linearly with the mean flame radius over the range of conditions tested.
Stability of Flames Close to Auto-Ignition Temperatures Generated by Extreme Separated Gas-Air Inlets
Authors: Piepers O. , Breithaupt P. P. , van Beelen A. B. N.
Published: July 2002

Stabilization of the combustion of natural gas in high-temperature processes by using the auto-ignition of the fuel when mixed with highly preheated air is well known and has found application on many occasions. Reasonably strong internal flue gas recirculation not only reduces nitric oxides emissions and increases convective heat transfer rates, but reduces local flame temperatures such that the flames become almost invisible for a human eye. This combustion regime is called flameless oxidation. Gasunie’s interest in this technique of flameless oxidation has two aspects. First, it must be clear which geometrical restrictions and flow conditions/disturbances in the oven or furnace have to be taken into account. Secondly, the use of this principle requires the auto-ignition of the fuel. This raises the question as to the stability of the combustion at or near the limits for auto-ignition. The study which is presented here reports on the stability of the oxidation process at these limiting conditions. These conditions are minimum load to the combustion system and minimum temperature in a combustion chamber. The stability has been determined using some “burner”/furnace combinations in which the distance between nozzles for air and natural gas have been varied.
Specific Hydraulic Conductivity of Corneal Stroma as Seen by Quick-Freeze/Deep-Etch
Authors: Overby Darryl , Ruberti Jeffrey , Gong Haiyan , Freddo Thomas F. , Johnson Mark
Published: July 2002

Previous studies of the hydraulic conductivity of connective tissues have failed to show a correspondence between ultrastructure and specific hydraulic conductivity. We used the technique of quick-freeze/deep-etch to examine the ultrastructure of the corneal stroma and then utilized morphometric studies to compute the specific hydraulic conductivity of the corneal stroma. Our studies demonstrated ultrastructural elements of the extracellular matrix of the corneal stroma that are not seen using conventional electron microscopic techniques. Furthermore, we found that these structures may be responsible for generating the high flow resistance characteristic of connective tissues. From analysis of micrographs corrected for depth-of-field effects, we used Carmen-Kozeny theory to bound a morphometrically determined specific hydraulic conductivity of the corneal stroma between 0.46×10−14 and 10.3×10−14 cm2. These bounds encompass experimentally measured values in the literature of 0.5×10−14 to 2×10−14 cm2. The largest source of uncertainty was due to the depth-of-field estimates that ranged from 15 to 51 nm; a better estimate would substantially reduce the uncertainty of these morphometrically determined values.
Apparently First Closed-Form Solution for Frequencies of Deterministically and/or Stochastically Inhomogeneous Simply Supported Beams
Authors: Candan S. , Elishakoff I.
Published: July 2002

An infinite number of closed-form solutions is reported for a deterministically or stochastically nonhomogeneous beam, for both natural frequencies and reliabilities, for specialized cases. These solutions may prove useful as benchmark solutions. Numerical examples are evaluated.
Influence of Axial Thrust Bearing on the Dynamic Behavior of an Elastic Shaft: Coupling Between the Axial Dynamic Behavior and the Bending Vibrations of a Flexible Shaft
Authors: Berger Se´bastien , Bonneau Olivier , Fre^ne Jean
Published: July 2002

This paper presents the nonlinear dynamic behavior of a flexible shaft. The shaft is mounted in two journal bearings and the axial load is supported by a hydrodynamic thrust bearing. The coupling between the axial thrust bearing behavior and the bending vibrations of the shaft is studied in particular. The shaft is modeled with typical beam finite elements. The dynamic behaviors of the fluid supports are considered as nonlinear. The dynamic behavior is analyzed using an unsteady time integration procedure. The paper shows the coupling between the axial dynamic behavior and the bending vibrations of the shaft.
Stiffness of Variable Thickness Belleville Springs
Authors: La Rosa G. , Messina M. , Risitano A.
Published: July 2002

The present study reports a theoretical analysis on Belleville springs with linearly variable thickness (radially tapered disk springs). The analysis aimed at the solution of two different problems: the realization of a spring with a zone of null slope in the stiffness curve (i.e. with the possibility of having different values of the deflection at a constant load, particularly useful in some regulation processes), and the definition of a disk spring with an almost constant stress state (with the stress linearly variable from the neutral axis to the upper and lower surfaces). Based on the hypothesis of Almen-Laszlo and Curti-Orlando-Podda, the theoretical analysis give the values of the stiffness curve and the stresses as a function of the geometrical parameters and allowed both problems to be resolved, clearly with different values of the geometric parameters. In order to compare the stresses obtained for large deflections, the authors constructed a numerical model which validated the theoretical analysis.
Coupled and Uncoupled CFD Prediction of the Characteristics of Jets From Combustor Air Admission Ports
Authors: McGuirk J. J. , Spencer A.
Published: July 2002

The paper focusses attention on alternative approaches for treating the coupling between the flow in the annulus supply ducts and the jets which enter combustor primary and dilution zones through air admission ports. Traditionally CFD predictions of combustor flows have modeled this in a very weakly coupled manner, with the port flow conditions being derived from 1D empirical correlations and used as boundary conditions for an internal-flow-only combustor CFD prediction. Recent work by the authors and others has introduced the viewpoint that fully coupled external-annulus–internal-combustor predictions is the way forward. Experimental data is gathered in the present work to quantify the strength of the interaction between annulus and core flows, which ultimately determines the jet characteristics at port exit. These data are then used to illustrate the improvement in the prediction of port exit jet characteristics which is obtained by adopting fully coupled calculations compared to the internal-flow-only approach. As a final demonstration of the importance of a fully coupled approach, isothermal calculations are presented for a single sector generic annular combustor. These show that quite different primary zone flow patterns are obtained from the two approaches, leading to considerable differences in the overall mixing pattern at combustor exit.
Conjugate Mixed Convection With Surface Radiation From a Vertical Plate With a Discrete Heat Source
Authors: Rao C. Gururaja , Balaji C. , Venkateshan S. P.
Published: July 2002

The results of a numerical study of the problem of two-dimensional, steady, incompressible, conjugate, laminar, mixed convection with surface radiation from a vertical plate with a flush-mounted discrete heat source are reported. The governing equations, written in vorticity-stream function form, are solved using a finite-volume based finite difference method. A hybrid grid system has been employed for discretization of the computational domain. The effects of (i) the magnitude and location of the heat source, (ii) the material and surface properties of the plate, and (iii) the free-stream velocity on both heat transfer and fluid flow have been studied. Based on a large set of (more than 550) numerical data, correlations have been developed for maximum and average non-dimensional plate temperatures and mean friction coefficient. A method for evaluating the forced convection mean friction coefficient component, which may be used in estimating the power input required for maintaining the flow, has been proposed.
Robustness in Geometric Computations*
Authors: Hoffmann Christoph M.
Published: July 2002

Geometric computation software tends to be fragile and fails occasionally. This robustness problem is rooted in the difficulty of making unambiguous decisions about incidence and nonincidence, fundamentally impairing layering the geometry software reliably. Additionally, geometric operations tend to have a large number of special and singular cases, further adding to the difficulty of creating dependable geometric software. We review the problem origins and ways to address it.
Application of Large-Eddy Simulation to the Study of Pulsatile Flow in a Modeled Arterial Stenosis
Authors: Mittal R. , Simmons S. P. , Udaykumar H. S.
Published: July 2002

The technique of large-eddy simulation (LES) has been applied to the study of pulsatile flow through a modeled arterial stenosis. A simple stenosis model has been used that consists of a one-sided 50 percent semicircular constriction in a planar channel. The inlet volume flux is varied sinusoidally in time in a manner similar to the laminar flow simulations of Tutty (1992). LES is used to compute flow at a peak Reynolds number of 2000 and a Strouhal number of 0.024. At this Reynolds number, the flow downstream of the stenosis transitions to turbulence and exhibits all the classic features of post-stenotic flow as described by Khalifa and Giddens (1981) and Lieber and Giddens (1990). These include the periodic shedding of shear layer vortices and transition to turbulence downstream of the stenosis. Computed frequency spectra indicate that the vortex shedding occurs at a distinct high frequency, and the potential implication of this for noninvasive diagnosis of arterial stenoses is discussed. A variety of statistics have been also extracted and a number of other physical features of the flow are described in order to demonstrate the usefulness of LES for the study of post-stenotic flows.
Turbine Nozzle Endwall Film Cooling Study Using Pressure-Sensitive Paint
Authors: Zhang Luzeng J. , Jaiswal Ruchira Sharma
Published: July 2002

Endwall surface film cooling effectiveness was measured on a turbine vane endwall surface using the pressure-sensitive paint (PSP) technique. A double staggered row of holes and a single row of discrete slots were used to supply film cooling in front of the nozzle cascade leading edges. Nitrogen gas was used to simulate film cooling flow as well as a tracer gas to indicate oxygen concentration such that film effectiveness by the mass transfer analogy could be obtained. Cooling mass flow was controlled to be 0.5 to 3.0 percent of the mainstream mass flow. The free-stream Reynolds number was about 283,000 and Mach number was about 0.11. The free-stream turbulence intensity was kept at 6.0 percent for all the tests, measured by a thermal anemometer. The PSP was calibrated at various temperatures and pressures to obtain better accuracy before being applied to the endwall surface. Film effectiveness distributions were measured on a flat endwall surface for five different mass flow rates. The film effectiveness increased nonlinearly with mass flow rate, indicating a strong interference between the cooling jets and the endwall secondary flows. At lower mass flow ratios, the secondary flow dominated the near wall flow field, resulting in a low film effectiveness. At higher mass flow ratios, the cooling jet momentum dominated the near wall flow field, resulting in a higher film effectiveness. The comparison between hole injection and slot injection was also made.
Manufacturing System Robustness Through Integrated Modeling
Authors: Suri Rajiv , Otto Kevin
Published: July 2002

Robust design techniques are often applied to the design of manufacturing processes to determine the most robust operating points for a production system. However, such efforts have traditionally been focused on treating the output of each manufacturing operation in isolation. This approach ignores the fact that the sensitivity of each operation to input variation is a function of the operating point, which can only be changed in conjunction with the operating points of all other operations in that system. As such, applying robust design to each operation within a system individually does not guarantee lowest end-of-line variation. This is contrary to commonly held beliefs. What is needed instead is a method for conducting a system-wide parameter design where the operating points of each operation are optimized as a complete set to reduce final product variation. The logistics of such an integrated parameter design scheme become difficult or impossible on processes that may occur in different geographical locations. In this paper we outline the use of mathematical models to conduct system-wide parameter design. We demonstrate this technique on a model of a sheet stretch-forming manufacturing system. Through this example, we show that selecting operating points while considering the entire system results in a greater reduction in variation than Taguchi-style robust design conducted independently on each of the operations within the system.
Development of Zero-Spin Planetary Traction Drive Transmission: Part 2 — Performance Testing and Evaluation
Authors: Ai Xiaolan
Published: July 2002

A tapered roller planetary traction drive based on a so-called zero-spin design was built for performance evaluation. The traction drive demonstrated, in many aspects, superb performance characteristics. The zero-spin design increased the torque capacity and enabled the traction drive to operate under both fully lubricated and starved lubrication conditions. The traction drive improved mechanical efficiency compared with traction drives of conventional designs and was able to achieve high efficiency up to 99 percent. The traction drive had satisfactory temperature performance.
The Instability and Vibration of Rotating Beams With Arbitrary Pretwist and an Elastically Restrained Root
Authors: Lin S. M.
Published: July 2002

The governing differential equations and the boundary conditions for the coupled bending-bending-extensional vibration of a rotating nonuniform beam with arbitrary pretwist and an elastically restrained root are derived by Hamilton’s principle. The semianalytical solution procedure for an inextensional beam without taking account of the coriolis forces is derived. The coupled governing differential equations are transformed to be a vector characteristic governing equation. The frequency equation of the system is derived and expressed in terms of the transition matrix of the vector governing equation. A simple and efficient algorithm for determining the transition matrix of the general system with arbitrary pretwist is derived. The divergence in the Frobenius method does not exist in the proposed method. The frequency relations between different systems are revealed. The mechanism of instability is discovered. The influence of the rotatory inertia, the coupling effect of the rotating speed and the mass moment of inertia, the setting angle, the rotating speed and the spring constants on the natural frequencies, and the phenomenon of divergence instability are investigated.
Transient Pig Motion Through Gas and Liquid Pipelines
Authors: Nieckele A. O. , Braga A. M. B. , Azevedo L. F. A.
Published: July 2002

Simulation of the transient motion of pigs through liquid and gas pipelines is presented. The differential form of the mass and linear momentum equations for compressible liquid and gas flows were solved by a finite difference numerical technique. The fluid flow equations were combined with a linear momentum equation for the pig and a model for bypass flow through the pig. The pig/wall contact forces were simulated by a stick/slip model. The contact forces developed by disk pigs and the pipe wall were predicted by a postbuckling finite element analysis of the discs. Test cases representing typical pigging operations were studied using the numerical model developed. The fluid flow and pig behavior predicted by the model presented a reasonable behavior, and contributed for a better understanding of the pig dynamics through gas and liquid pipelines.
A Three-Gear Linkage for Generating Dwell Motions
Authors: Beiner L.
Published: July 2002

This study deals with a three-gear four-bar linkage that transforms a uniform input crank rotation into a forward-dwell motion of the output gear. Closed-form relations allowing to synthesize a geared linkage generating an approximate dwell of specified tolerance are derived. Such intermittent motions are useful in various transport and indexing devices found in textile, printing and packaging machines.
The Role of Lagrangian Strain in the Dynamic Response of a Flexible Connecting Rod
Authors: Chen Jen-San , Chen Kwin-Lin
Published: July 2002

Previous researches on the dynamic response of a flexible connecting rod can be categorized by the ways the axial load in the rod is being formulated. The axial load may be assumed to be (1) dependent only on time and can be obtained by treating the rod as rigid, (2) related to the transverse displacement by integrating the axial equilibrium equation, and (3) proportional to linear strain. This paper examines the validity of these formulations by first deriving the equations of motion assuming the axial load to be proportional to the Lagrangian strain. In order for the dimensionless displacements to be in the order of O(1), different nondimensionalization schemes have to be adopted for low and high crank speeds. The slenderness ratio of the connecting rod arises naturally as a small parameter with which the order of magnitude of each term in the equations of motion, and the implication of these simplified formulations can be examined. It is found that the formulations in previous researches give satisfactory results only when the crank speed is low. On the other hand when the crank speed is comparable to the first bending natural frequency of the connecting rod, these simplified formulations overestimate considerably the dynamic response because terms of significant order of magnitude are removed inadequately.
Evaporation-Combustion Affected by In-Cylinder, Reciprocating Porous Regenerator
Authors: Park Chan-Woo , Kaviany Massoud
Published: July 2002

An existing in-cylinder thermal regeneration concept for Diesel engines is examined for the roles of the porous insert motion and the fuel injection strategies on the fuel evaporation and combustion and on the engine efficiency. While the heated air emanating from the insert enhances fuel evaporation resulting in a superadiabatic combustion process (thus increasing thermal efficiency), the corresponding increase in the thermal NOx is undesirable. A two-gas-zone and a single-step reaction model are used with a Lagrangian droplet tracking model that allows for filtration by the insert. A thermal efficiency of 53 percent is predicted, compared to 43 percent of the conventional Diesel engines. The optimal regenerative cooling stroke occurs close to the peak flame temperature, thus increasing the superadiabatic flame temperature and the peak pressure, while decreasing the expansion stroke pressure and the pressure drop through the insert. During the regenerative heating stroke, the heated air enhances the droplet evaporation, resulting in a more uniform, premixed combustion and a higher peak pressure, thus a larger mechanical work.
Redesign of NEMO-Type Spherical Acrylic Submersible for Manned Operation to 3000 ft (914 m) Ocean Depth
Authors: Das Partha S.
Published: July 2002

A detailed nonlinear three-dimensional (3-D) finite element analysis (FEA) was performed in Phase I on a NEMO (naval experimental manned observatory) type HBOI (Harbor Branch Oceanographic Institution) spherical acrylic submersible in order to overcome the crack generation problem at its interfaces. An FEA has been carried out to develop a new design guideline, by reducing the higher stresses and relative displacements at the interfaces, which are believed to be two of the main reasons for crack generation at these areas. Variation of the stiffness between dissimilar materials at the interface, lower nylon gasket thickness, overdesigned aluminum hatch and bottom penetrator plug, attachment of the retainer ring with hatch ring, close placement of the rubber padding to the interface between the acrylic sphere, and the retainer ring are found to be the various causes for higher stresses within the acrylic sphere at the nylon gasket/acrylic interface. Based on the new design guidelines, in Phase II, a new spherical acrylic submersible was fabricated and tested. This design resulted in significant improvements by reducing the peak stresses and relative displacements at the gasket/acrylic interface areas. This improvement in design is expected to significantly extend the crack-free cyclic fatigue life of the acrylic submersible at 3000 ft (914 m) ocean depth.
Meshfree and particle methods and their applications
Authors: Li Shaofan , Liu Wing Kam
Published: July 2002

Recent developments of meshfree and particle methods and their applications in applied mechanics are surveyed. Three major methodologies have been reviewed. First, smoothed particle hydrodynamics (SPH) is discussed as a representative of a non-local kernel, strong form collocation approach. Second, mesh-free Galerkin methods, which have been an active research area in recent years, are reviewed. Third, some applications of molecular dynamics (MD) in applied mechanics are discussed. The emphases of this survey are placed on simulations of finite deformations, fracture, strain localization of solids; incompressible as well as compressible flows; and applications of multiscale methods and nano-scale mechanics. This review article includes 397 references.
Compound Circular Reflector of a Novel Design for Evacuated Tubular Collectors
Authors: Zhao C. J. , Kanayama K. , Baba H.
Published: July 2002

A new type of the reflectors for evacuated tubular collectors (ETC) which we referred to as a Compound Circular Reflector (CCR) was designed. The reflectors allow reducing the number of tubes per collector area due to increasing the center-to-center distance of tubes, i.e. the pitch of tubes, so that the weight and cost of the collectors coupled with the reflectors decrease. The reflectors also improve collector efficiency. In comparison with a collector coupled with the planar reflectors, the collector coupled with CCRs accomplished following purposes: The weight per collector area decreases by 20% and the collector efficiency increases by about 7 percentage points as well as the cost of production per collector area decreases by 33%. Therefore the cost-effectiveness of the collectors is markedly improved.
A Theoretical Analysis of Floating Bush Journal Bearing With Axial Oil Film Rupture Being Considered
Authors: Hatakenaka Kiyoshi , Tanaka Masato , Suzuki Kenji
Published: July 2002

A new modified Reynolds equation is derived with centrifugal force acting on the hydrodynamic oil film being considered. This equation, together with a cavitation model, is used to obtain the steady-state equilibrium and calculate the rotordynamic coefficients of lightly loaded floating bush journal bearings operating at very high shaft speeds. The bush-to-shaft speed ratio and the linear cross-coupling spring coefficients of the inner oil film is found to decrease with the increase in shaft speed as the axial oil film rupture develops in the inner oil film. The present model can give reasonable explanation to the steady-state behavior and the stability behavior of the bearing observed in actual machines.
Numeralytics: A Computation Approach for Engineering Practitioners
Authors: Sandler Ben Zion
Published: July 2002

Much of the time spent on engineering calculations and that devoted to teaching mathematics-associated disciplines can be considerably reduced, since the application of mathematics to engineering needs is well defined: computations in engineering must be completed within certain time restrictions and the required computation accuracy is limited in the domain of reality. The use of combined analytical and numerical techniques—numeralytics—when applied without vulgarization, may be very effective in saving time in both teaching and computation for engineering purposes. This work describes application of the technique by demonstrating some examples of engineering computations in dynamics.
Modeling the Lubrication, Dynamics, and Effects of Piston Dynamic Tilt of Twin-Land Oil Control Rings in Internal Combustion Engines
Authors: Tian T. , Wong V. W.
Published: July 2002

A theoretical model was developed to study the lubrication, friction, dynamics, and oil transport of twin-land oil control rings (TLOCR) in internal combustion engines. A mixed lubrication model with consideration of shear-thinning effects of multigrade oils was used to describe the lubrication between the running surfaces of the two lands and the liner. Oil squeezing and asperity contact were both considered for the interaction between the flanks of the TLOCR and the ring groove. Then, the moments and axial forces from TLOCR/liner lubrication and TLOCR/groove interaction were coupled into the dynamic equations of the TLOCR. Furthermore, effects of piston dynamic tilt were considered in a quasi three-dimensional manner so that the behaviors of the TLOCR at different circumferential locations could be studied. As a first step, variation of the third land pressure was neglected. The model predictions were illustrated via an SI engine. One important finding is that around thrust and anti-thrust sides, the difference between the minimum oil film thickness of two lands can be as high as several micrometers due to piston dynamic tilt. As a result, at thrust and anti-thrust sides, significant oil can pass under one land of the TLOCR along the bore, although the other land perfectly seals the bore. Then, the capabilities of the model were further explained by studying the effects of ring tension and torsional resistance on the lubrication and oil transport between the lands and the liner. The effects of oil film thickness on the flanks of the ring groove on the dynamics of the TLOCR were also studied. Friction results show that boundary lubrication contributes significantly to the total friction of the TLOCR. [S0742-4795(00)01801-9]
Closure to “Discussion of ‘Internal Bearing Chamber Wall Heat Transfer as a Function of Operating Conditions and Chamber Geometry’ ” [ASME J. Eng. Gas Turbines Power, 122, No. 2, p. 364]
Authors: Busam S.
Published: July 2002

[S0742-4795(00)03202-6]
Experimental Investigation of Boundary Layer Behavior in a Simulated Low Pressure Turbine
Authors: Shyne Rickey J. , Sohn Ki-Hyeon , De Witt Kenneth J.
Published: July 2002

A detailed investigation of the flow physics occurring on the suction side of a simulated low pressure turbine (LPT) blade was performed. A contoured upper wall was designed to simulate the pressure distribution of an actual LPT blade onto a flat plate. The experiments were carried out at Reynolds numbers of 100,000 and 250,000 with three levels of freestream turbulence. The main emphasis in this paper is placed on flow field surveys performed at a Reynolds number of 100,000 with levels of freestream turbulence ranging from 0.8 percent to 3 percent. Smoke-wire flow visualization data were used to confirm that the boundary layer was separated and formed a bubble. The transition process over the separated flow region is observed to be similar to a laminar free shear layer flow with the formation of a large coherent eddy structure. For each condition, the locations defining the separation bubble were determined by careful examination of pressure and mean velocity profile data. Transition onset location and length determined from intermittency profiles decrease as freestream turbulence levels increase. Additionally, the length and height of the laminar separation bubbles were observed to be inversely proportional to the levels of freestream turbulence. [S0098-2202(00)00701-X]
Nonlinear Transient Heat Conduction Using Similarity Groups
Authors: Becker M.
Published: July 2002

Nonlinear response is studied using similarity groups. The nonlinear solution is similar to the linear solution except with properties evaluated at the local temperature and is consistent with reported empirical observations that, near the heat source, high-temperature properties are needed to predict cooling times to high temperatures and that low temperature properties are needed to predict cooling time to low temperatures. For position-dependent characteristics of the solution away from the source, like magnitudes and locations of peak temperatures, nonlinear and linear solutions are similar if local properties are evaluated at current temperatures prevailing near the source. [S0022-1481(00)02701-8]
A Monte Carlo Solution of Heat Conduction and Poisson Equations
Authors: Grigoriu M.
Published: July 2002

A Monte Carlo method is developed for solving the heat conduction, Poisson, and Laplace equations. The method is based on properties of Brownian motion and Ito^ processes, the Ito^ formula for differentiable functions of these processes, and the similarities between the generator of Ito^ processes and the differential operators of these equations. The proposed method is similar to current Monte Carlo solutions, such as the fixed random walk, exodus, and floating walk methods, in the sense that it is local, that is, it determines the solution at a single point or a small set of points of the domain of definition of the heat conduction equation directly. However, the proposed and the current Monte Carlo solutions are based on different theoretical considerations. The proposed Monte Carlo method has some attractive features. The method does not require to discretize the domain of definition of the differential equation, can be applied to domains of any dimension and geometry, works for both Dirichlet and Neumann boundary conditions, and provides simple solutions for the steady-state and transient heat equations. Several examples are presented to illustrate the application of the proposed method and demonstrate its accuracy. [S0022-1481(00)02201-5]
The Application of a Robust Design Method to Tolerancing
Authors: Parkinson D. B.
Published: July 2002

A deterministic method of robust design (previously described and summarized here) has been applied to the problem of determining optimum nominal dimensions of manufactured components which are subject to dimensional tolerances. The optimum sought is that for which an assembly of the components shows least variability, as measured by one or more relevant parameters (e.g. a clearance) for a fixed set of tolerances. The aim of the method is demonstrated by an example of a multiparameter assembly problem. The method provides a potential means of improving assembly quality without tightening tolerances, when nominal dimensions can be adjusted subject to other requirements of the design. [S1050-0472(00)00802-3]
Thermohydrodynamic Lubrication Analysis Incorporating Bingham Rheological Model
Authors: Kim J. H. , Seireg A. A.
Published: July 2002

A mathematical model is developed for parametric investigation of the influence of the rheological properties of the lubricant on the thermohydrodynamic film conditions which occur in slider and journal bearings. The model is utilized for predicting the thickness of the shear zone in lubricating films with fixed geometry between the stationary and moving surfaces using a Bingham model with a shear yield stress which best fits the experimental pressure. It is found that the shear zone thickness is significantly smaller than the fluid film thickness in the lubrication zone and is of the same order of magnitude as that obtained by the empirical formula proposed by Wang and Seireg (1995) ASME J. Tribol., 117, p. 444. The results also suggest that the shear yield stress for the lubricating film is proportional to the pressure developed in the film within the range of the investigated cases. [S0742-4787(00)05101-8]
A Simplified 4-DOF Suspension Model for Dynamic Load/Unload Simulation and Its Application
Authors: Zeng Q. H. , Bogy D. B.
Published: July 2002

The mathematical models are critical for accurate simulation of the dynamic load/unload (L/UL) process in disk drives. The air bearing slider and the suspension are the most important parts in the L/UL mechanism. The air bearing modeling has been well researched, but an adequate and efficient suspension model is not available. A simplified 4-DOF suspension model is proposed in this paper. In this model the slider’s pitch angle change due to the motion of the L/UL tab on the ramp is included in the simulation, and the forces applied by the ramp can be directly obtained. The effects of the suspension inertia are included in the effective inertia moments of the slider to improve the loading simulation. The model is implemented and applied to simulate the L/UL process of a pico slider that has been used in recent IBM mobile drives. The effects of the pitch static attitude (PSA), the roll static attitude (RSA), and some initial disturbances to the loading process are investigated. It is found that a positive PSA can significantly smoothen the loading process. The effects of the PSA, the disk rpm, and the unload velocity on the unloading process are also simulated, and it is found that a positive PSA can also greatly improve the unloading performance of the slider. The results show that the unloading process can be accurately simulated by using the proposed model, and the loading process can be more accurately simulated by using this 4-DOF model than the 3-DOF model. [S0742-4787(00)03601-8]
Closure to “Discussion of ‘Operation of Foil Bearings Beyond the Bending Critical Mode’ ” [ASME J. Tribol., 122, No. 2, p. 478 (2000)]1
Authors: Heshmat, Hooshang
Published: July 2002

[S0742-4787(00)02802-2]
Hydrodynamic Fluid Pressure in Grinding Zone During Grinding With Metal-Bonded Diamond Wheels
Authors: Zhang Bo , Nakajima Akira
Published: July 2002

Experimental and theoretical studies on hydrodynamic fluid pressure were conducted for the cases of plane grinding with nonporous metal bonded diamond wheels of SD140 and SD4000. Hydrodynamic force was successfully separated from the actual grinding force using the device developed in this study. Both experimental results and theoretical analysis showed that the effect of side leakage of grinding fluid on hydrodynamic pressure is negligible under grinding condition and therefore the infinite width cylindrical bearing theory is applicable. The effective clearance includes the effects of both the protrusion of cutting points and the waviness of the wheel surface for SD140. However, for a fine wheel such as SD4000, the waviness is predominant. Hydrodynamic force predominates normal grinding force even for a coarse wheel as SD140. [S0742-4787(00)01302-3]
Stall Inception in the Compressor System of a Turbofan Engine
Authors: Ho¨ss Bernd , Leinhos Dirk , Fottner Leonhard
Published: July 2002

Compressor flow instabilities have been the subject of a great number of investigations during the past decade. While most of this research work was done on isolated test-rig compressors, this paper presents stall inception measurements in the compressor system of a two-spool turbofan engine at various power settings. Several analyzing techniques such as temporal low-pass and band-pass filtering, temporal and spatial Fourier transforms including power-spectral-density calculations of the spatial coefficients, and a wavelet analyzing technique are applied. For the low-pressure compressor three different types of stall inception processes were observed depending on the rotor speed. At low speed, stall originates from spike-type precursors, while long wavy pressure fluctuations corresponding to modal waves were observed prior to stall at midspeed for undistorted inlet flow. At high speed, the rotor shaft unbalancing dominates the stall inception process as an external forcing function. In the case of distorted inlet flow spike-type stall inception behavior dominates throughout the speed range. While filtering and the Fourier spectra give a good insight into the physical background of the stall inception process (but with a very short warning time), the wavelet transform indicates the approach of the stalling process a few hundred rotor revolutions in advance independently of the type of precursor. Setting up a reliable stall avoidance control based on this analysis scheme seems to be promising. [S0889-504X(00)00401-3]
Editorial
Authors: Davidson Jane
Published: July 2002

[S0199-6231(00)03001-X]
CuF2 by XPS
Authors: Vasquez Richard P.
Published: July 2002

X-ray photoemission measurements of high purity CuF2 are presented. XPS studies of Cu compounds in this laboratory have been motivated by the need to identify species on chemically-etched high temperature superconductor surfaces [see R. P. Vasquez, M. C. Foote, and B. D. Hunt, J. Appl. Phys. 66, 4866 (1989)].
Natural Iron and Manganese Oxide Samples by XPS
Authors: Rosso Jodi J. , Hochella Michael F.
Published: July 2002

XPS analyses of naturally formed iron and manganese oxide surfaces reveals important information used for interpreting mineral surface reactivity in our environment. Specifically, these oxides and oxyhydroxides give us details about the oxidation state of manganese phases commonly found during heterogeneous reactions. This type of analysis is also useful for interpreting the formation history of natural mineral surfaces. In this submission we present XPS data on the mineral surfaces hematite (α-Fe2O3), goethite (α-FeOOH), pyrolusite (β-MnO2), and manganite (α-MnOOH).
Study of Four Single Crystal Faces of ZnO, by UPS
Authors: Solomon Edward I. , Henrich V. E.
Published: July 2002

The four most studied faces of ZnO are the polar (0001)-Zn and (0001¯)-O, and the non-polar (101¯0) and (112¯0). The different faces exhibit significantly different He II UPS spectra of the valence band and Zn 3d region. These spectra are taken on atomically clean, ion-bombarded and annealed samples [see R. R. Gay, M. H. Nodine, E. I. Solomon, V. E. Henrich, and H. J. Zeiger, J. Am. Chem. Soc. 102, 6752 (1980)].
Cu2O by XPS
Authors: Vasquez R. P.
Published: July 2002

X-ray photoemission measurements of Cu2O are presented.