bluuebunny/crossref_metadata_2025 huggingface dataset:
A Numerical Solution for the Nonlinear Deflection of Membranes
Authors: Shaw F. S. , Perrone N.
Published: June 2021

A numerical method of solution for the nonlinear deflection of thin flat membranes subjected to normal forces as well as forces in the plane of the membrane has been given by Hencky. The equations he solved were first derived by Föppl, and they also follow directly from the von Kármán nonlinear plate equations on formally making the plate stiffness zero. Föppl’s equations are two in number, one being of fourth order and the other second. The unknown quantities are a stress function and the normal displacement. Hencky’s method of solution does not seem capable of easy generalization. The same class of membrane problems is reconsidered here. By casting the problem entirely in terms of displacement components three simultaneous nonlinear second-order partial differential equations are obtained, and a technique is here devised by means of which these equations can be solved without difficulty using finite-difference approximations in conjunction with a relaxation-iteration procedure. Various simple preliminary examples are discussed, after which an example involving a rectangular region is considered in complete detail. The technique devised can be used for a region of any shape, including the case where the boundary is curved, and also for any arbitrary given load system.
Tables for Frequencies and Modes of Free Vibration of Infinitely Long Thin Cylindrical Shells
Authors: Baron M. L. , Bleich H. H.
Published: June 2021

Tables are presented for the quick determination of the frequencies and shapes of modes of infinitely long thin cylindrical shells. To make the problem tractable, the shells are first treated as membranes without bending stiffness, and the bending effects are introduced subsequently as corrections. The underlying theory is based on the energy expressions for cylindrical shells. The tables cover the following range: lengths of longitudinal half wave L from 1 to 10 radii a; number n of circumferential waves from 0 to 6. The results apply for Poisson’s ratio ν = 0.30.
The Plasticity of an Isotropic Aggregate of Anisotropic Face-Centered Cubic Crystals
Authors: Hershey A. V.
Published: June 2021

The plasticity of a polycrystalline aggregate is expressed in terms of the plasticity of the individual grains. It is assumed that the local deviation of stress from the average stress is proportional to the local deviation of strain from the average strain, and it is assumed that plastic flow begins when there is an average of three active slip systems per grain. The plastic states of a grain are mapped as a function of the orientation of the crystallographic axes. A coexistence of different states of strain with different rotations of the axes at the same state of stress can be correlated with the occurrence of deformation bands. A range of orientations is illustrated in which the axes tend to congregate quickly and then move more slowly toward a stable end orientation. The residual strain which would be observed by x-ray diffraction after the release of stress is calculated for three sets of diffracting planes. The applications of the theory have so far been limited to face-centered cubic polycrystals with intrinsic elastic isotropy.
A Simple Nomogram for the Ratios of Octahedral to Maximum Shearing Stresses and Its Physical Interpretation
Authors: Zizicas G. A.
Published: June 2021

A nomogram constructed exclusively by means of straight lines is presented, giving the ratio of the octahedral to the maximum shearing stresses for all possible stress distributions in terms of the nondimensional ratios of the two principal stresses to the one of maximum absolute value. The physical interpretation of the nomogram is discussed. It is shown that states of stress with constant ratio of octahedral to maximum shearing stress are represented by straight lines. To such lines are found to correspond fixed values of the deviatoric parameter μ = 2 S 2 - S 1 - S 3 S 1 - S 3 in agreement with a recent observation by Novozhilov. The values of μ are given directly by the nomogram.
Impulsive Loading on an Elastic Half-Space
Authors: Huth J. H. , Cole J. D.
Published: June 2021

This brief note considers the wave system resulting from a step loading on an elastic half-space. A similar problem was treated by H. Lamb in 1904, but his interest was in surface tremors rather than the stresses treated herein.
Polyaxial Stress-Strain Relations of a Strain-Hardening Metal
Authors: Batdorf S. B. , Budiansky Bernard
Published: June 2021

The authors assess a plastic stress-strain law of anisotropic strain-hardening type which they previously developed on the basis of explicit consideration of the polycrystalline nature of metals and the mechanism of plastic deformation. The assumptions made are reviewed, together with the successes and limitations of the theory. The authors indicate the lines along which they feel that improvement of the theory is to be sought.
Rigid-Plastic Analysis of Symmetrically Loaded Cylindrical Shells
Authors: Hodge P. G.
Published: June 2021

A general method is presented for finding the stress and incipient velocity distribution in a symmetrically loaded cylindrical shell at collapse. The results are based upon a linearized yield surface, and a method is given for obtaining this linearized surface directly. The techniques are illustrated with reference to open and closed cylindrical shells under uniform external pressure. In each case the shell is specified completely by a single parameter c defined as the ratio of the half-length of the shell to the geometric mean of the radius and half-thickness; c = L / a ! . It is found that for moderately large values of c, the limiting load is greater for the closed shell, while for small c the reverse is true.
Steady-State Vibrations of Beam on Elastic Foundation for Moving Load
Authors: Kenney J. T.
Published: June 2021

This paper presents an analytic solution and resonance diagrams for a constant-velocity moving load on a beam on an elastic foundation including the effect of viscous damping. The limiting cases of no damping and critical damping are investigated. The possible velocities for the propagation of free bending waves are found and their relation to the critical velocity of the beam is studied.
Prediction and Evaluation of Sensitivity to Transient Accelerations
Authors: Kornhauser M.
Published: June 2021

The determination, presentation, and interpretation of inertia-sensitivity data are discussed with application to inertia devices and to shock-resistant structures. Theoretical analysis of the single-degree-of-freedom system for response to acceleration-time pulses, amplification factors, and inertia sensitivity are used as a basis for discussion of actual devices. Effects of deviations from the ideal mass-spring system are considered. Practical use of sensitivity data is discussed with regard to the reliability of laboratory methods, the accuracy of field measurements, and variability of service conditions. Criteria are suggested for design of inertia mechanisms and design of structures for resistance to shock.
Mechanism of Fretting Corrosion
Authors: Uhlig Herbert H.
Published: June 2021

A review of the facts suggests that the mechanism of fretting corrosion includes a chemical factor and a mechanical factor, with observed damage, in general, resulting from both. An asperity rubbing on a metal surface is considered to produce a track of clean metal which immediately oxidizes, or upon which gas rapidly adsorbs. The next asperity wipes off the oxide or initiates reaction of metal with adsorbed gas to form oxide. This is the so-called chemical factor of fretting. In addition, asperities dig below the surface to cause a certain amount of wear by welding or shearing action in which metal particles are dislodged. This is the mechanical factor of fretting. Metallic debris produced by fretting is thought not to oxidize spontaneously, as proposed by the molecular-attrition theory, but instead converts partially to iron oxide by secondary fretting action of particles rubbing against themselves or adjacent surfaces. This accounts for the fact that Fe2O3 is found by x ray to be the major corrosion product and metallic iron is present, if at all, in only very small amount. The quantitative expression for fretting corrosion derived on the basis of the foregoing model for relatively large values of load, frequency, and slip is W ( total ) = ( k 0 L 1 ⁄ 2 - k 1 L ) C f + k 2 l L C where W is the specimen weight loss, L is the load, C is the number of cycles, f is the frequency, l the slip, and k0, k1, and k2 are constants. The first two terms are the chemical factor of fretting corrosion and the third term is the mechanical factor. Accordingly, the equation predicts that fretting-corrosion weight loss is a hyperbolic function of frequency, is parabolic with load and linear with number of cycles or magnitude of slip. Furthermore, the terms concerned with a frequency effect disappear when the chemical factor is suppressed, as is observed when fretting tests are conducted in nitrogen. These conclusions are confirmed by the reported data. In addition, the calculated reaction-rate constant for oxidation of a freshly formed iron surface obtained from fretting data is reasonable and falls between two independently observed values. In our experiments, the chemical or corrosion factor falls within 6 to 78 per cent of the total observed fretting damage, depending on conditions of test. Remedial measures are outlined in light of the data and the proposed mechanism.
Small Rotationally Symmetric Deformations of Shallow Helicoidal Shells
Authors: Reissner Eric
Published: June 2021

Known solutions for transverse bending and plane stress of flat circular ring plates are generalized so as to apply to shallow helicoidal shells. The pitch of the middle surface of the shell is responsible for a coupling of what would be separate problems of plane stress and transverse bending for flat plates. Explicit results are obtained for an important sample problem. A general property of helicoidal cantilever shells is stated. Criteria are obtained indicating, in terms of the parameters of the shell (a) the range of applicability of the results obtained, and (b) the range in which the shell behaves like a flat plate.
On Turbulent Jet Mixing of Two Gases at Constant Temperature
Authors: Pai S. I.
Published: June 2021

The fundamental equations of both two-dimensional and axially symmetrical turbulent jet mixing of two gases at constant temperature are derived and discussed. A general method of solution of these equations is given. The most important factors in these equations are the turbulent exchange coefficient for velocity distribution and that for density distribution. In general, these coefficients are not equal. If we assume that these coefficients are the same, an analytic solution for the mixing of two uniform streams is found which is an extension of Görtler’s solution for the case of homogeneous fluids. The first-order effect of the difference in densities of the two gases in the mixture on the velocity distribution is small. For two-dimensional and axially symmetrical jet from small opening, if the turbulent exchange coefficients are assumed to be the same, the velocity distribution for the case of homogeneous fluid is the first-order approximation of the velocity distribution in the jet of the mixing of two gases and the density distribution is the same as the velocity distribution. Finally, the effect of the difference in the two turbulent exchange coefficients is discussed. It is found that the ratio of turbulent-exchange coefficient for density distribution to that for velocity distribution is larger than 1, and may be as high as 2, and the ratio increases as the difference in density of the two gases increases. The larger this ratio is, the wider the spread of the density distribution than that of velocity distribution will be.
The Stress Problem of Vibrating Compressor Blades
Authors: Schnittger Jan R.
Published: June 2021

In order to demonstrate the general nature of the actual vibrations of compressor and turbine blades, the author undertakes a simplified analysis in which a single stiff blade, with one translational and one pitching mode, is studied. It is shown that all problems of stress in vibrating compressor blades whether they arise from forced or self-sustained vibrations may be related to the magnitude of finite mechanical or aerodynamic disturbances.
Acceleration in Mechanisms
Authors: Hinkle R. T. , Ip C. , Frame J. S.
Published: June 2021

An equation is derived for finding the instantaneous radii of curvature for the paths of relative motion described by the coincidental points of contact of direct-contact mechanisms, and a graphical method for solving the equation for these radii is developed. A proof of the validity of the equivalent linkage for direct-contact mechanisms is presented.
Problems of Plane Elasticity for Reinforced Boundaries
Authors: Radok J. R. M.
Published: June 2021

Based on N. I. Muskhelishvili’s approach to problems of plane elasticity, a general method has been deduced for the solution of problems of reinforced cutouts in infinitely thin sheets. As an illustration, the circular reinforced hole has been treated in detail and the results have been related to those obtained experimentally and theoretically by other authors. The solution for other shapes of cutouts will be greatly simplified, since full use may be made of the theory of conformal transformations.
Stress Distributions in Nonsymmetric Rotating Rays
Authors: Hodge P. G.
Published: June 2021

The centrifugal forces acting upon a rotating ray will produce longitudinal stresses along the ray. If the ray is not symmetric, these stresses will result not only in a longitudinal force, but also in a bending moment. A technique for finding the stress distribution in this case is developed and illustrated by means of simple examples. The limiting elastic speed and the maximum speed before large-scale plastic deformation commences are computed. An indication is given of how similar methods may be used to analyze a rotating disk with no plane of symmetry perpendicular to the axis.
Studies on Scabbing of Solids Under Explosive Attack
Authors: Broberg K. B.
Published: June 2021

The purpose of this paper is to analyze the mechanism of the scabbing phenomenon that occurs when an intense shock wave in a solid is reflected against a free surface. Only plane shock waves with normal incidence to the free surface are discussed. The shock wave is assumed to be initiated by the detonation of an explosive (especially TNT with a loading density of 1.5 g/cm3). The calculations are based upon values given by H. Jones and A. R. Miller (for the detonation pressure), D. J. McAdam (for the strength of the material at combined stresses), P. W. Bridgman (for the quantitative behavior of the material at very high pressures) and, finally, upon results from the author’s own experiments regarding the impulse and the pressure-time curve at detonation in contact with a metal surface. It is shown that fracture sometimes is likely to occur in several parallel layers of the material. Experiments have been performed which support the theoretical analysis. The research was carried out at the Royal Swedish Fortification and Works Administrative Service, Stockholm.
Lateral Buckling of Asymmetrical Beams
Authors: Langhaar H. L.
Published: June 2021

A simplified theory of lateral buckling of asymmetrical beams under the action of uniform bending moments and axial thrusts is developed.
An Approximate Nonuniform Bending Theory and Its Application to the Swept-Plate Problem
Authors: Plass H. J.
Published: June 2021

Differential equations and boundary conditions are derived, by means of the calculus of variations, for cylindrical bars in nonuniform bending. The resulting equations are used, together with similar nonuniform torsion equations, to obtain deflections and stresses in swept cantilever plates of uniform rectangular cross section. Comparisons are made with experimental results for plates with four different sweep angles. The theory predicts deflections quite close to those found experimentally. Stresses computed from the equations, however, are not in as close agreement. It is also noticed that the theory is less accurate for large sweep angles than for small ones.
Thermal Stresses in Rectangular Strips—II
Authors: Born J. S. , Horvay G.
Published: June 2021

Stresses and deformations in rectangular strips due to various longitudinal temperature distributions are presented in formulas, tables, and graphs. The results are important for slabs, plate assemblies, rectangular ducts, tube-sheet ligaments; they apply, in a more qualitative fashion, also to cylindrical bodies.
A Study of the Speed of Sound in Porous Granular Media
Authors: Brandt H.
Published: June 2021

A theory is developed to explain the influence of pressure, porosity, and liquid saturation on the speed of sound through a porous granular medium. An aggregate of randomly stacked spherical particles of four different sizes is used as a model for the porous medium. The volume-pressure relationship of the aggregate is determined by means of the Hertz theory for the deformation of elastic and isotropic spheres in contact. This relationship is extended to embrace the case of liquid saturation of the aggregate. The bulk modulus is derived from the volume-pressure relationship and the speed of sound is determined from the bulk modulus. It is shown how the theory can be extended to apply to the speed of sound through an aggregate comprised of nonspherical granules and finally, in an approximate form, through a consolidated granular medium. As an example of the application of the latter the speed of sound through sandstone under various conditions of pressure and saturation is predicted, and agreement is noted between the predicted results and those derived experimentally.
Force at Point in the Interior of a Semi-Infinite Solid With Fixed Boundary
Authors: Rongved Leif
Published: June 2021

The Papkovitch functions are determined for a force acting at a point in the interior of a semi-infinite isotropic solid with a fixed plane boundary. The normal traction on the boundary is then calculated.
Buckling of Laminated Columns
Authors: Clark L. G.
Published: June 2021

A theory is developed to determine the buckling of laminated columns composed of two or more laminations and riveted or fixed together at certain points along the column. The laminations can be of different size and material but must be long in comparison to the cross-sectional dimensions. The final result is presented in a form suitable for easy application. It is shown that for two laminations joined at an infinite number of points the problem reduces to that of a simple column. Two pinned-end columns were tested and the results are in satisfactory agreement with the theory.
The Nonlinear Bending of Thin Circular Rods
Authors: Conway H. D.
Published: June 2021

Two examples of the nonlinear bending of thin circular rods are discussed using the Bernoulli-Euler equation, which states that the change of curvature of a rod is proportional to the bending moment producing it. Numerical results are presented.
Theoretical Determination of Rigidity Properties of Orthogonally Stiffened Plates
Authors: Huffington N. J.
Published: June 2021

The analysis of bending and buckling of orthogonally stiffened plates may be simplified by conceptually replacing the plate-stiffener combination by an “equivalent” homogeneous orthotropic plate of constant thickness. This procedure requires the determination of the four elastic rigidity constants which occur in the theory of thin orthotropic plates. Methods are presented whereby these quantities may be determined analytically in terms of the elastic constants and geometrical configuration of the component parts of the structure.
Combined Stress Tests in Plasticity
Authors: Phillips Aris , Kaechele Lloyd
Published: June 2021

A substantial number of combined stress tests on thin-walled tubes of aluminum 2S-O are reported. In most of the tests the tubes have been subjected to combined tension and torsion with variable stress ratios. In the last six tests each tube has first been subjected to uniaxial tension until sufficiently deep in the plastic region and then this state of uniaxial stress has been rotated while the magnitude of the principal stresses remained constant.

The purpose of the tests was to get information as to the validity of the incremental theories of plasticity. The results of these tests favor the incremental theories.
Displacements in an Elastic-Plastic Cylindrical Shell
Authors: Hodge P. G.
Published: June 2021

A reinforced cylindrical shell which is loaded with a uniform excess external radial pressure can support a load considerably greater than the elastic limit. While several recent investigations have been concerned with finding the collapse load of the shell, no attention has been paid to the corresponding deformations. Although rigid-plastic theory is sufficient to determine the collapse load, the more complex elastic-plastic theory must be used in investigating the displacements. In the present paper the elastic-plastic problem is stated for an ideal sandwich shell, and the stresses and deformations are computed for a particular example. Since the computations are found to be quite laborious, an approximate technique, applicable to all shells, is developed. The paper closes with some comments on the relation between the theoretical results and the behavior to be expected in real shells.
Stress Concentration Caused by Multiple Punches and Cracks
Authors: Sadowsky Michael
Published: June 2021

The paper contains (a) a general theory of stress distribution under several punches in simultaneous action and of stress concentration caused by several cracks; (b) a complete evaluation for the case of two punches or two cracks. Considerable stress interference is found with punches (cracks) close to each other.
Bending and Torsion of Circular Cylinder Cantilever Beams of Cylindrically Aeolotropic Material
Authors: Ericksen W. S.
Published: June 2021

This paper deals with the problem of determining the components of stress and displacement associated with the flexure and torsion of a cantilever beam in the form of a hollow circular cylinder of cylindrically aeolotropic material. A solution satisfying the conditions of the theory of elasticity is obtained by the semi-inverse method of Saint Venant.
On the Torsion of Rectangular Sandwich Plates
Authors: Seide Paul
Published: June 2021

The torsional rigidity of rectangular sandwich plates of constant thickness is calculated, with cross sections assumed free to warp. The faces are isotropic and of equal thickness while the core may be orthotropic, the axes of orthotropy coinciding with co-ordinate axes of the structure.
High-Frequency Extensional Vibrations of Plates
Authors: Kane T. R. , Mindlin R. D.
Published: June 2021

The equations of generalized plane stress are applicable to the extensional vibrations of plates only for the low modes of motion of thin plates. In this paper equations are derived which are applicable to both low and high modes of thin plates and to low modes of thick plates. As an example, the equations are solved for the case of axially symmetric vibrations of a circular disk and comparisons are made with the theory of generalized plane stress and with experiments.
Theoretical Considerations of Combined Thermal and Mass Transfer From a Vertical Flat Plate
Authors: Somers E. V.
Published: June 2021

In free-convective processes involving both thermal and mass transfer, since the driving force for the fluid motion has its source solely in the density difference from ambient, it is necessary to consider the thermal and mass-transfer processes simultaneously in solving any given problem. The present problem involves evaporation and condensation phenomena associated with free-convective thermal and mass transfer from a wetted isothermal vertical flat plate to a gas at an ambient temperature and mass concentration different from that on the plate. This problem presents itself in the practical case of vaporization cooling of equipment without forced circulation of the ambient gas.
Computation of Roll Force and Torque in Cold-Rolling by Modern Theory
Authors: Whitton P. W.
Published: June 2021

The full theory for the comparison of calculated roll force and torque with experimental values is outlined. This takes into account the strip elastic compression, the derivation of the yield-stress curves in cold-rolling, and the accurate values for friction coefficient between rolls and strip. Hitherto, the contribution of each of these rolling variables has been found separately. This paper presents the combination of current theory on each. The application of this method yields results within ± 5 per cent, a much more accurate comparison than hitherto presented.
On the Stresses and Deflections of Rectangular Beams
Authors: Boley B. A. , Tolins I. S.
Published: June 2021

The stresses and deflections in rectangular beams and bars are calculated from the two-dimensional elasticity theory by an iterative procedure previously derived. The loading consists of either normal or shear forces varying smoothly along the span. The results are obtained in the form of infinite series, whose first terms represent the elementary solutions of strength of materials; the accuracy of the Mc/I and P/A formulas can thus be estimated. A comparison with the Timoshenko beam theory is included.
The Effect of Spring Mass on Contact-Accelerometer Responses
Authors: Lin T. H.
Published: June 2021

Theoretical responses of a contact-break accelerometer are analyzed for steady-state and some transient motions. The distributed mass of the spring is considered in the present analysis. For steady-state motions, viscous damping is assumed to exist between the spring and the case of the instrument. Responses to simple harmonic motions of different frequencies are shown. Responses to a single cosine wave and a step function of acceleration are analyzed. The main source of error in the contact-break accelerometer is shown to be due to the spring mass. An electromagnetic-contact accelerometer with no spring mass is proposed. Preliminary study of this accelerometer is shown.
On the Carrying Capacity of Redundant Structures
Authors: Masur E. F. , Milbradt K. P.
Published: June 2021

It has been shown previously (1) how the inclusion of certain nonlinear terms in the analysis of redundant trusses affects the predicted behavior of such structures in the postbuckling range. In particular, it was demonstrated that the nonlinear theory predicts states of axial stress corresponding to a general stiffening of the structure compared with the results of the classical linear analysis. After establishing a generalized minimum-strain-energy principle, this paper describes a series of tests which corroborates experimentally the predictions of the nonlinear theory. For example, the predicted (and measured) ultimate load of the test model amounts to about three times the load at which the linear theory predicts collapse through instability. A similar theory (2) dealing with the response of redundant trusses to primary bending moments is extended to certain types of singular cases which were excluded from the previous paper. It is shown analytically and verified by experiment that a constant ultimate state of axial stress may be reached already for finite applied couples. Elastic behavior is assumed throughout the paper.
Analysis of Slip Damping With Reference to Turbine-Blade Vibration
Authors: Goodman L. E. , Klumpp J. H.
Published: June 2021

Energy of vibration may be dissipated by microscopic slip-on interfaces where machine elements are joined in a press fit. In this paper slip damping is studied as an agent in reducing turbine-blade resonant stresses and prolonging turbine life. A general theory of slip damping is developed and an expression for the energy loss per cycle of oscillation is found. The predictions of the theory are compared with the results of controlled experiments. It appears that the theory is in satisfactory agreement with experiment and with measurements made on turbine blades elsewhere in this country and abroad. The implications of the general theory in the design of turbine blades are discussed. It appears that slip damping is capable of being an effective agent in reducing resonant stresses, especially in the “stall-flutter” condition where aerodynamic damping is inadequate. The design of a slip-damping joint which would achieve theoretically possible energy decrements much larger than are present in existing commercial construction is shown to depend on the maintenance of an optimum contact pressure.
A New Method of Analyzing Stresses and Strains in Work-Hardening Plastic Solids
Authors: Prager William
Published: June 2021

For work-hardening plastic solids, segmentwise linear yield conditions and the associated flow rules constitute a reasonable compromise between the mathematically convenient but physically unsound total stress-strain laws and the physically sound but mathematically inconvenient incremental laws. They allow total stress-strain laws to be used in the small, but retain the characteristic features of incremental laws in the large. The use of a segmentwise linear yield condition and the associated flow rule is illustrated by the analysis of the bending moments and deflections of a simply supported circular plate that is made of a work-hardening material and subjected to a uniformly distributed transverse load.
The Effect of Shear on the Plastic Bending of Beams
Authors: Drucker D. C.
Published: June 2021

The end-loaded cantilever beam of perfectly plastic material has been studied in considerable detail but many questions remain unanswered. As a first step in extension to plates, the concept is explored of an interaction curve relating limiting values of shearing force and bending moment for perfectly plastic beams. Simple illustrations demonstrate that, far more than in the elastic range, such interaction is not just a local matter but depends upon the geometry and loading of the entire beam. Useful interaction curves are obtained, nevertheless, with the aid of the upper and lower bound techniques of limit analysis, choosing the maximum-shearing-stress criterion of yielding for convenience. It is shown, in particular, that although a small amount of shear produces but a second-order reduction in the limit moment of beams, a small moment reduces the limiting shear value by a first-order term.
The Tapered-Land Thrust Bearing
Authors: Kettleborough C. F.
Published: June 2021

Neglecting side leakage the maximum load capacity which can be carried per unit width is obtained when there is a stepped convergence to the oil film. However, when side leakage is considered the stepped bearing is only slightly better than the tilting-pad bearing, this being due to the fact that the maximum oil pressure occurs at the step where the oil-film thickness is a maximum and hence there is easy means of escape for oil. The tapered-land bearing does not suffer from this disadvantage and computations have been carried out which show that the maximum load this bearing is capable of supporting is about 14 per cent greater than the maximum load capable of being supported by the tilting-pad bearing, both cases not neglecting side leakage. Some numerical calculations are made.
Deposition Process and Equivalent Markov Motion of High-Inertia Particles in a Long Straight Pipeline
Authors: Zhang Ri , Xu Kai , Liu Yong , Wang Yumiao
Published: June 2021

Two methods are used to study the process of particle deposition in a turbulent pipe flow. The Monte Carlo method tracks 10,000 particles in the turbulent pipe flow to reproduce the deposition process of the particles. The deposition velocity of the particles is determined by calculating the proportion of particles passing through the test section. The simplified deposition model uses an equivalent Markov motion instead of the radial movement of the particle in the turbulent core. The probability that a particle leaves the turbulent core depends on the radial particle position and the probability density distribution of the random vortex. The probability that a particle penetrates the boundary layer can be solved by integrating the probability density distribution of radial particle velocity. The deposition velocity of particles can be obtained by calculating the probability of an individual particle leaving the turbulent core and penetrating the boundary layer. Five experimental data series from the literature are applied to examine the predictive abilities of the two methods. The results demonstrate that the Monte Carlo method can be properly used to track the particle deposition process in the diffusion–impaction and inertia-moderated regimes. The simplified model is suitable for high-inertia particles.
Effect of the Speed Factor on the Amplitude of the Blade Passing Frequency in the Vaneless Space of a Pump Turbine in Turbine Mode
Authors: Hu Jinhong , Yang Jiebin , Zeng Wei , Yang Jiandong
Published: June 2021

An exponential expression describing the relationship between the amplitude of the blade passing frequency in the vaneless space of a pump turbine operating in the turbine mode and the speed factor is proposed based on statistical analysis. This mathematical relationship was discovered through signal processing of the data recorded during the emergency load rejection process of a prototype pump turbine. Subsequently, based on the pumped-storage test rig at Wuhan University, an experimental investigation was conducted to verify this mathematical relationship. The results indicated that, under the optimal guide vane opening of the model pump turbine, the goodness of fit of this mathematical relationship was quite high. As for the Francis pump turbine, the speed factor corresponds to the Strouhal number. Therefore, for this correlation, the underlying physical mechanism is the influence of the Strouhal number. This relation could inform the design and operation of pump turbines to control the intensity of pressure pulsations in the vaneless space. In addition, based on this mathematical relationship, the intensity of the rotor–stator interaction for different pump turbines can be compared quantitively.
Analysis of Flow Regimes and Associated Sources of Dissipation in Splash Lubricated Planetary Gear Sets
Authors: Boni J. B. , Changenet C. , Ville F.
Published: June 2021

Planetary gears are used in several applications given that they provide high reduction ratio in a compact size. Two kinds of lubrication are used in these applications: injection or splash lubrication. In case of splash lubrication, the authors already highlighted the importance of the centrifugal effects leading to the formation of an oil ring inside the reducer, therefore giving a method to compute churning power losses. In this paper, another flow regime is underlined when centrifugal forces are not sufficient to turn the oil sump into a ring. In addition to this observation, an in-depth analysis is given regarding the dependence of the churning power losses with operating conditions and oil characteristics.
A Novel Method for Fracture Pressure Prediction in Shallow Formation During Deep-Water Drilling
Authors: Yang Jin , Liu Shujie , Wang Huanhuan , Zhou Xu , Song Yu , Xie Renjun , Zhang Zhenxiang , Yin Qishuai , Xu Fei
Published: June 2021

Large numbers of deep-water drilling practices have shown that more than 60% of deep-water wells have complex leak-off during the drilling process, which poses great difficulties and challenges for the safety and operation time of deep-water drilling. The purpose of this article is to establish a method for predicting the fracture pressure in shallow formations. In this study, the deep-water shallow formation was divided into the upper unconsolidated soil layer, and the lower diagenetic rock layer according to the geotechnical distribution characteristics of the deep-water shallow formation. The location of the transition soil/rock layer zone was determined using the upper soil layer density trend line, and the lower rock layer density log data regression trend line. The deep-water shallow fracture pressure prediction model was established based on the soil/rock transition zone. The shear failure criterion was used above the transition zone, and the tensile failure criterion is used below the transition zone. The shallow fracture pressure of six drilled exploratory wells in the X block from the South China Sea was calculated using this new method and the calculation errors were all less than 3.18%. Moreover, the shallow fracture pressure body in this block was established using the Kriging interpolation method based on six drilled exploratory wells data. This shallow fracture pressure body established here was used to predict nine development wells shallow fracture pressure with a predictive error of less than 1.7% and there were no drilling accidents. The case study demonstrates that the new model can significantly improve the prediction accuracy has good prospects for popularization and application.
Experimental and Molecular Dynamics Simulation-Based Investigations on Hydrogen Embrittlement Behavior of Chromium Electroplated 4340 Steel
Authors: Dogan Ozge , Kapci Mehmet Fazil , Esat Volkan , Bal Burak
Published: June 2021

In this study, chromium electroplating process, corresponding hydrogen embrittlement, and the effects of baking on hydrogen diffusion are investigated. Three types of materials in the form of Raw 4340 steel, Chromium electroplated 4340 steel, and Chromium electroplated and baked 4340 steel are used in order to shed light on the aforementioned processes. Mechanical and microstructural analyses are carried out to observe the effects of hydrogen diffusion. Mechanical analyses show that the tensile strength and hardness of the specimens deteriorate after the chrome-electroplating process due to the presence of atomic hydrogen. X-ray diffraction (XRD) analyses are carried out for material characterization. Microstructural analyses reveal that hydrogen enters into the material with chromium electroplating process, and baking after chromium electroplating process is an effective way to prevent hydrogen embrittlement. Additionally, the effects of hydrogen on the tensile response of α-Fe-based microstructure with a similar chemical composition of alloying elements are simulated through molecular dynamics (MD) method.
Internal Training Load Affects Day-After-Pretraining Perceived Fatigue in Female Volleyball Players
Authors: Ungureanu Alexandru Nicolae , Lupo Corrado , Boccia Gennaro , Brustio Paolo Riccardo
Published: June 2021

Purpose:The primary aim of this study was to evaluate whether the internal (session rating of perceived exertion [sRPE] and Edwards heart-rate-based method) and external training load (jumps) affect the presession well-being perception on the day after (ie, +22 h), according to age and tactical position, in elite (ie, Serie A2) female volleyball training.Methods:Ten female elite volleyball players (age = 23 [4] y, height = 1.82 [0.04] m, body mass = 73.2 [4.9] kg) had their heart rate monitored during 13 team (115 individual) training sessions (duration: 101 [8] min). Mixed-effect models were applied to evaluate whether sRPE, Edwards method, and jumps were correlated (P ≤ .05) to Hooper index factors (ie, perceived sleep quality/disorders, stress level, fatigue, and delayed-onset muscle soreness) in relation to age and tactical position (ie, hitters, central blockers, opposites, and setters).Results:The results showed a direct relationship between sRPE (P < .001) and presession well-being perception 22 hours apart, whereas the relationship was the inverse for Edwards method internal training load. Age, as well as the performed jumps, did not affect the well-being perception of the day after. Finally, central blockers experienced a higher delayed-onset muscle soreness than hitters (P = .003).Conclusions:Findings indicated that female volleyball players’ internal training load influences the pretraining well-being status on the day after (+ 22 h). Therefore, coaches can benefit from this information to accurately implement periodization in a short-term perspective and to properly adopt recovery strategies in relation to the players’ well-being status.
Genetic Polymorphisms Related to VO2max Adaptation Are Associated With Elite Rugby Union Status and Competitive Marathon Performance
Authors: Hall Elliott C.R. , Almeida Sandro S. , Heffernan Shane M. , Lockey Sarah J. , Herbert Adam J. , Callus Peter , Day Stephen H. , Pedlar Charles R. , Kipps Courtney , Collins Malcolm , Pitsiladis Yannis P. , Bennett Mark A. , Kilduff Liam P. , Stebbings Georgina K. , Erskine Robert M. , Williams Alun G.
Published: June 2021

Purpose: Genetic polymorphisms have been associated with the adaptation to training in maximal oxygen uptake (). However, the genotype distribution of selected polymorphisms in athletic cohorts is unknown, with their influence on performance characteristics also undetermined. This study investigated whether the genotype distributions of 3 polymorphisms previously associated with training adaptation are associated with elite athlete status and performance characteristics in runners and rugby athletes, competitors for whom aerobic metabolism is important. Methods: Genomic DNA was collected from 732 men including 165 long-distance runners, 212 elite rugby union athletes, and 355 nonathletes. Genotype and allele frequencies of PRDM1 rs10499043 C/T, GRIN3A rs1535628 G/A, and KCNH8 rs4973706 T/C were compared between athletes and nonathletes. Personal-best marathon times in runners, as well as in-game performance variables and playing position, of rugby athletes were analyzed according to genotype. Results: Runners with PRDM1 T alleles recorded marathon times ∼3 minutes faster than CC homozygotes (02:27:55 [00:07:32] h vs 02:31:03 [00:08:24] h, P = .023). Rugby athletes had 1.57 times greater odds of possessing the KCNH8 TT genotype than nonathletes (65.5% vs 54.7%, χ2 = 6.494, P = .013). No other associations were identified. Conclusions: This study is the first to demonstrate that polymorphisms previously associated with training adaptations in nonathletes are also associated with marathon performance (PRDM1) and elite rugby union status (KCNH8). The genotypes and alleles previously associated with superior endurance-training adaptation appear to be advantageous in long-distance running and achieving elite status in rugby union.
Experimental quantum conference key agreement
Authors: Proietti Massimiliano , Ho Joseph , Grasselli Federico , Barrow Peter , Malik Mehul , Fedrizzi Alessandro
Published: June 2021

When Alice and Bob invite their friends, quantum key distribution with multiparty entanglement enables secure conference call.
Autophagy suppresses the formation of hepatocyte-derived cancer-initiating ductular progenitor cells in the liver
Authors: Barthet Valentin J. A. , Brucoli Martina , Ladds Marcus J. G. W. , Nössing Christoph , Kiourtis Christos , Baudot Alice D. , O’Prey James , Zunino Barbara , Müller Miryam , May Stephanie , Nixon Colin , Long Jaclyn S. , Bird Thomas G. , Ryan Kevin M.
Published: June 2021

Autophagy represses YAP/TAZ-dependent hepatocyte dedifferentiation into liver progenitor cells to prevent tumorigenesis.
Budding yeast relies on G
1
cyclin specificity to couple cell cycle progression with morphogenetic development
Authors: Pirincci Ercan Deniz , Chrétien Florine , Chakravarty Probir , Flynn Helen R. , Snijders Ambrosius P. , Uhlmann Frank
Published: June 2021

A synthetic biology approach reveals why budding yeast needs more than one cyclin to grow and divide.
ERK signaling mediates resistance to immunomodulatory drugs in the bone marrow microenvironment
Authors: Liu Jiye , Hideshima Teru , Xing Lijie , Wang Su , Zhou Wenrong , Samur Mehmet K. , Sewastianik Tomasz , Ogiya Daisuke , An Gang , Gao Shaobing , Yang Li , Ji Tong , Bianchi Giada , Wen Kenneth , Tai Yu-Tzu , Munshi Nikhil , Richardson Paul , Carrasco Ruben , Cang Yong , Anderson Kenneth C.
Published: June 2021

Blocking of MEK-ERK pathway overcomes myeloma cells resistance to immunomodulatory drugs in the bone marrow microenvironment.
Conversion of mouse embryonic fibroblasts into neural crest cells and functional corneal endothelia by defined small molecules
Authors: Pan Shao-Hui , Zhao Ning , Feng Xiang , Jie Ying , Jin Zi-Bing
Published: June 2021

Small-molecule cocktails converted fibroblasts into neural crest cells and functional corneal endothelial cells.
Phospholipase A Activity in the Hemolysis of Sheep and Human Erythrocytes by
Rickettsia prowazeki
Authors: Winkler Herbert H. , Miller Elizabeth T.
Published: June 2021

Incubation of
Rickettsia prowazeki
with sheep or human erythrocytes resulted in lysis of the erythrocytes and formation of free fatty acids and lysophosphatides. Inhibitors of lysis were also invariably inhibitors of this phospholipase A activity. The target for this activity was the glycerophospholipids of the erythrocyte and not those of the rickettsia. Rickettsial phosphatidylethanolamine labeled with
32
PO
4
or [
3
H]acetate remained intact during lysis, and the composition of the free fatty acids released resembled that of the erythrocyte species used and not the rickettsiae. The products of hydrolysis remained associated with the sedimentable material in the reaction mixture under the usual conditions but partitioned into the supernatant fluid when bovine serum albumin was present. Initially, the time course of phospholipase A activity and lysis was identical, but the release of free fatty acids continued for a short time after the release of hemoglobin was complete. Both the inner and outer leaflets of the erythrocyte membrane were accessible to this rickettsial phospholipase A activity since both phosphatidylcholine and phosphatidylethanolamine were substrates in human erythrocytes. The questions of whether rickettsiae possess their own phospholipase A or activate a latent erythrocyte enzyme and what the role of the energy requirement is in these processes remain unanswered.
Mice Refractory to Lipopolysaccharide Manifest High Immunoglobulin A Responses to Orally Administered Antigen
Authors: Babb James L. , McGhee Jerry R.
Published: June 2021

Lipid A-nonresponding C3H/HeJ mice manifested high immune responses to orally administered (either by feeding or by intragastric immunization) heterologous erythrocytes when compared with syngeneic lipid A-responding C3H/HeN mice. Prolonged consumption of horse erythrocytes resulted in a significant secretory immune response in both C3H mouse strains as evidenced by high salivary agglutinin titers. Although salivary agglutinin titers were only slightly greater in C3H/HeJ mice than those of C3H/HeN mice, serum agglutinin titers and immunoglobulin A (IgA) levels were consistently higher (two- to fourfold) in C3H/HeJ mice. The appearance of anti-horse erythrocyte plaque-forming cell responses in spleens of immunized animals was followed by an increase in salivary anti-horse erythrocyte agglutinin activity. Peak levels of both responses were attained after approximately 3 weeks of immunization. Differences in immune responsiveness between C3H mouse strains were also evident at the cellular level since splenic IgA anti-horse erythrocyte plaque-forming cell responses in fed C3H/HeJ mice were twofold higher than those in similarly treated C3H/HeN mice. This higher response pattern was also observed when C3H/HeJ mice manifested threefold higher splenic IgM and IgA plaque-forming cell responses to intragastrically administered sheep erythrocytes. Thus, higher responsiveness was observed in the C3H/HeJ mice given heterologous erythrocytes by the oral route. Furthermore, levels of serum IgA in 10- to 12-month-old nonimmunized C3H/HeJ mice were higher than those of C3H/HeN mice. These findings suggest that lack of host responsiveness to lipopolysaccharide affects the manifestation of subsequent immune responses to orally administered antigens. The possible mechanisms and implications of this high responsiveness are discussed.