bluuebunny/crossref_metadata_2025 huggingface dataset:
Plate and Rod Vibrations With Initial Stress
Authors: Wright T. W.
Published: October 2011

The influence of a homogeneous state of initial stress on the frequency of three-dimensional vibrations of plates and rods is considered. A linear constitutive relation is used and only terms to first power of initial stress are retained in all results. General frequency equations are found and various limiting cases are considered. Membrane and string tension terms appear in the bending modes indicating possible instabilities. In all other limiting cases, frequencies are modified only slightly by the presence of initial stress.
Multiparameter Perturbation Solution of Algebraic Equations
Authors: Ames W. F. , Sontowski J. F.
Published: October 2011

The classical perturbation method—the expansion of a solution of an algebraic equation as a power series in a parameter—is extended to an expansion in several parameters. An example concerning the Timoshenko beam equation is used to illustrate the ideas. Advantages of the procedure are discussed in the light of this example.
Clamped Circular Rigid-Plastic Plates Under Blast Loading
Authors: Florence A. L.
Published: October 2011

A theoretical study is made of clamped circular plates of rigid-plastic material subjected to blast loading uniformly distributed over the surface. The dependence of the permanent central deflection on pressure and impulse is obtained when the blast pulse is taken as a rectangular pulse.
Probability Distribution of Bilinear System Response to Impulse Excitation
Authors: Felszeghy Stephen F. , Thomson William T.
Published: October 2011

A single-degree-of-freedom system with a bilinear spring is excited by a rectangular impulse of constant value, but whose amplitude has a probability distribution which is Gaussian. The peak response of the system under this excitation is determined, and its probability distribution is plotted as a function of its peak value.
Compressive Strain-Rate Tests on Six Selected Materials at Strain Rates From 10−3 to 104 In/In/Sec
Authors: Maiden C. J. , Green S. J.
Published: October 2011

The results of compressive strain-rate tests on 6061-T6 aluminum, 7075-T6 aluminum, 6Al-4V titanium fully annealed, pyrolytic graphite, lucite, and micarta for rates of loading of 10−3 to 104 in/in/sec are presented. A medium strain-rate machine and a split Hopkinson bar apparatus used to conduct these tests are described, and the principle of operation, data-reduction methods, and a critique of techniques are given for each machine. Results of the tests show that the two aluminums exhibit no strain-rate sensitivity over the rates tested. Titanium, lucite, and micarta are rate sensitive with the titanium exhibiting a delayed yield and the lucite and micarta showing viscoelastic behavior. The pyrolytic graphite shows little rate sensitivity below 10 in/in/sec and slight sensitivity above this rate.
Optimum Thin-Wall Pressure Vessels of Anisotropic Materials
Authors: Gerard George , Lakshmikantham C.
Published: October 2011

A governing design synthesis relationship is derived for the primary structural weight of membrane-type pressure vessels. The structural efficiency is associated with the configuration and the failure law characterizing the material used, and it is this factor which is examined in some detail. Closed pressure vessels of various shapes utilizing isotropic and anisotropic materials of monolithic and filamentary construction are analyzed to establish optimum designs and then compared to establish relative structural efficiencies.
Turbulence as a Producer of Noise in Proportional Fluid Amplifiers
Authors: Prosser D. W. , Fisher M. J.
Published: October 2011

A theory was developed to predict the signal and noise, in terms of stagnation pressures, at the entrance to a blocked rectangular receiver placed in an otherwise free two-dimensional turbulent jet. Experimental verification of the theory was then undertaken. The results showed that a reversal of flow takes place within the entrance of a blocked receiver, so that stagnation conditions do not exist at the entrance and, hence, the theory is not valid under these conditions. The theory was easily altered to predict the momentum flux through a receiver which presents very little resistance to flow through its passageway. Employing a device called a momentum meter the altered theory was verified. The main results of this work are: (a) The noise-to-signal ratio of a receiver held fixed in the jet is minimized by keeping the receiver near the centerline of the jet. (b) The ratio of noise to change in signal, with relative movement between the jet and receiver, is minimized by keeping the receiver away from the centerline of the power jet.
Two-Phase Turbulent Flow in a Plane Jet
Authors: Goldschmidt V. , Eskinazi S.
Published: October 2011

Measurements of local mean aerosol concentration were made with a hot-wire anemometer and a special circuit including an electronic filter and counter. The concentration distribution of the liquid phase in a plane jet of air was measured and an analysis of the diffusion process is given and compared with the experiments. From the measurements the mass diffusivity of the liquid in the turbulent air is determined.
On the Unsteady Motion of a Viscous Hydromagnetic Fluid Contained in a Cylindrical Vessel
Authors: Groves R. N.
Published: October 2011

The problem of unsteady motion of an electrically conducting viscous liquid contained in a cylindrical vessel in the presence of an axially symmetric magnetic field of constant strength has been solved exactly by using concurrently two methods of operational calculus—the finite Hankel transform, and the Laplace transform. Results of these operations for general boundary conditions are presented in convolution integral form. The exact solutions of two special cases are presented in terms of tabulated functions, including those especially developed for the purposes of this paper. By examining the limiting cases of these special results, verification of results that have previously appeared in the literature and other interesting phenomena arise.
On Infinitesimal Cycloidal Kinematic Theory of Planar Motion
Authors: Sandor G. N.
Published: October 2011

A kinematic theory is developed involving infinitesimally close coplanar positions of a moving plane, based on a finite cycloidal kinematic theory of plane motion, which was shown to include Burmester’s classical centerpoint-circlepoint theory as one of several special cases. The infinitesimal theory is developed for both the general cycloidal and for the special circular (Burmester) cases. Applications are derived for closed-form analytic synthesis of higher-order approximate path and motion generator linkages. Examples are given, and implementations of the theory in the form of computer programs are made available.
On the Vibration and Stability of Finitely Deformed Shallow Spherical Shells
Authors: Archer R. R. , Famili J.
Published: October 2011

Equations describing the asymmetric vibrations of a shallow spherical shell which has suffered a finite axisymmetric displacement due to axisymmetric loading are studied by means of a finite-difference analysis. Results are obtained which show a continuous variation of the frequency spectrum as a function of the load parameter ranging from the previously computed frequencies and modes of the unloaded shell to the modes corresponding to vanishing frequencies which reveal the asymmetric buckling modes and loads for the shell. Excellent agreement with earlier work is found for both limiting cases thus providing an independent check on the asymmetric buckling loads recently computed by Huang.
The Steady-State Response of a Two-Degree-of-Freedom Bilinear Hysteretic System
Authors: Iwan W. D.
Published: October 2011

The method of slowly varying parameters is used to obtain an approximate solution for the steady-state response of a two-degree-of-freedom bilinear hysteretic system. The stability of the system is investigated and it is shown that such a system exhibits unbounded amplitude resonance when the level of excitation is increased beyond a certain finite limit.
Fundamental Frequency of Simply Supported Rectangular Plates With Linearly Varying Thickness
Authors: Appl F. C. , Byers N. R.
Published: October 2011

Upper and lower bounds for the fundamental eigenvalue (frequency) of a simply supported rectangular plate with linearly varying thickness are given for several taper ratios and plan geometries. These bounds were determined using a previously published method which yields convergent bounds. In the present study, all results have been obtained to within 0.5 percent maximum possible error.
Closed Forms for the Stresses in a Class of Orthotropic Wedges
Authors: Baker B. R.
Published: October 2011

The Mellin transform is applied to problems of stress distribution in symmetric orthotropic wedges. Integral representations for the stresses are obtained and specialized for the fundamental problem of line loads. Asymptotic forms are obtained for the general class which gives the solution when loads are applied at the tip. A subclass of wedges is considered which satisfy a certain relationship between the opening angle and elastic constants. Closed forms for the stresses can be obtained for this subclass which is dense and therefore can be used to approximate any symmetric orthotropic wedge. As an example, numerical results are presented for a quarter-plane subjected to normal or shear loads.
Stress Distribution in Bonded Dissimilar Materials With Cracks
Authors: Erdogan F.
Published: October 2011

The problem of two bonded dissimilar semi-infinite planes containing cracks along the bond is reconsidered. The external loads considered include the tractions on the crack surfaces, in-plane moments, residual stresses due to temperature changes, concentrated load and couple acting at an arbitrary location in the plane, and one-sided wedge loading of the crack. The stresses along the bonds are calculated and shown in graphs. In the example of wedge loading, the stress state and displacements in the vicinity of the crack tip are more closely studied; and the bonding stress σ and the relative displacement v1 − v2 along the crack are plotted as functions of log(r/a). It was found that, even though the stresses and displacements oscillate as r approaches zero, for the example of glass-steel bond the first zero of σ occurs around (r/a) = 10−10.63, and at a distance (r/a) = 10−10 the stress-concentration factor has already exceeded 104. Similarly, the region within which relative displacements oscillate is 0 < (r/a) < 10−7, and the maximum value of interference becomes v2 − v1 = P10−9.7, P (lb/in.) being the wedge load. It was concluded that, considering the magnitudes of distances and stresses involved, in practical applications the phenomenon of stress oscillation, which seems to be a peculiar characteristic of mixed-boundary-value problems of linear infinitesimal elastostatics, may be ignored.
Plane Problems of Cracks in Dissimilar Media
Authors: Rice J. R. , Sih G. C.
Published: October 2011

The in-plane extension of two dissimilar materials with cracks or fault lines along their common interface is considered. A method is offered for solving such problems by the application of complex variables integrated with the eigenfunction-expansion technique presented in an earlier paper. The solution to any problem is resolved to finding a single complex potential resulting in a marked economy of effort as contrasted with the more laborious conventional methods which have not yielded satisfactory results. Boundary problems are formulated and solutions are given in closed form. The results of these evaluations also give stress-intensity factors (which determine the onset of rapid fracture in the theory of Griffith-Irwin) for plane problems.
Low Buckling Stresses of Axially Compressed Circular Cylindrical Shells of Finite Length
Authors: Hoff N. J.
Published: October 2011

Exact solutions are derived of the classical differential equations defining the deformations of axially compressed thin-walled circular cylindrical shells. The end conditions along the circular edges are assumed as the vanishing (a) of the radial displacement; (b) of the longitudinal bending moment; (c) of the variation in the axial normal stress resultant; and (d) of the circumferential membrane shear stress resultant. Under these conditions of simple support the critical value of the uniformly distributed axial normal stress is one half the classical critical value.
Transient Response in a Viscoelastic Material With Temperature-Dependent Properties and Thermomechanical Coupling
Authors: Wolosewick R. M. , Gratch Serge
Published: October 2011

The transient response of a semi-infinite, viscoelastic rod after application of a sinusoidal stress variation at one end has been investigated by a numerical method. Account has been taken of temperature dependence of properties and of thermomechanical coupling. It is found that, with values of physical properties typical for polymeric materials, temperature approaches steady state several orders of magnitude more slowly than would be the case for stress and strain in the absence of thermomechanical coupling.
Stress and Shape Analysis of a Paraglider Wing
Authors: Fralich Robert W.
Published: October 2011

A combined aerodynamic-structural analysis is made which is based on the assumption that the sail is flexible and has freedom to take the shape which the aerodynamic pressure and the internal stresses dictate. Numerical results were obtained for Newtonian impact aerodynamic theory and were compared with published results obtained for a rigid idealization of the paraglider wing. It was found that the assumed rigid idealization did not approximate the shape of a flexible wing well and led to significant errors in the lift and drag forces and the lift-to-drag ratio. The new calculations provide a basis for design of paragliders for hypersonic flight.
Response of a Submerged Cylindrical Shell to an Axially Propagating Step Wave
Authors: Forrestal M. J. , Herrmann G.
Published: October 2011

An infinitely long, circular, cylindrical shell is submerged in an acoustic medium and subjected to a plane, axially propagating step wave. The fluid-shell interaction is approximated by neglecting fluid motions in the axial direction, thereby assuming that cylindrical waves radiate away from the shell independently of the axial coordinate. Rotatory inertia and transverse shear deformations are included in the shell equations of motion, and a steady-state solution is obtained by combining the independent variables, time and the axial coordinate, through a transformation that measures the shell response from the advancing wave front. Results from the steady-state solution for the case of steel shells submerged in water are presented using both the Timoshenko-type shell theory and the bending shell theory. It is shown that previous solutions, which assumed plane waves radiated away from the vibrating shell, overestimated the dumping effect of the fluid, and that the inclusion of transverse shear deformations and rotatory inertia have an effect on the response ahead of the wave front.
On a Variational Theorem in Coupled Thermoelasticity
Authors: Ben-Amoz M.
Published: October 2011

Washizu’s principle for stresses, displacements, and strains in isothermal elasticity is extended to the field of coupled thermoelasticity. All field equations, including solid and thermal strain-displacement relations, are deduced from the extended functional. The relation to other known theorems is discussed.
Motions of a Stretched String Carrying a Moving Mass Particle
Authors: Smith Charles E.
Published: October 2011

A considerable amount of analytical work has been carried out in order to determine the effects of “traveling” loads on structures. Several methods—all approximate—have been used to predict the motion of a beam, along which a mass particle is constrained to move. An “exact” solution is presented here for a similar system in which a stretched string serves as support for the moving mass. Comparison with this system lends some insight into the more complicated beam problem. A singular behavior of the solution to the string problem suggests the possibility of an analogous singular behavior in the solution to the beam problem.
Concentrated Forces on Compressed Plates and Related Problems for Moving Loads
Authors: Jahanshahi A. , Dundurs J.
Published: October 2011

The paper gives the singularity for a concentrated lateral load on a unidirectionally compressed plate. The method of images is used to treat the infinite strip. For suitable initial conditions, the results derived for the unidirectionally compressed plate under static loads may also be interpreted as a solution for the plate subjected to moving loads.
Fixed Tube-Sheet Heat Exchangers
Authors: Boon G. B. , Walsh R. A.
Published: October 2011

The paper presents an analysis of fixed tube-sheet heat-exchanger stresses and tube-sheet deflections. The tube sheet is considered as a perforated, plate on an elastic foundation, which possesses both a deflection and rotational modulus, with an elastically built-in edge consisting of the shell and the channel head.
Application of Dual-Number Quaternion Algebra to the Analysis of Spatial Mechanisms
Authors: Yang A. T. , Freudenstein F.
Published: October 2011

Dual-number quaternion algebra has been used to obtain explicit, closed-form algebraic expressions for the displacements, velocities, velocity ratios, forces, torques, mechanical advantages, transmission angle, and locking positions in spatial four-link mechanisms having one turning pair and three turn-slides. The results have been programmed for automatic digital computation.
The Influence of Fluid Forces on the Sticking and the Lateral Vibration of Pistons
Authors: Boyd John
Published: October 2011

It is shown that both sticking (hydraulic lock) and lateral vibrations of pistons can be caused by hydrodynamic forces. Corrective methods are discussed.
The Bending of Plates of Dissimilar Materials With Cracks
Authors: Sih G. C. , Rice J. R.
Published: October 2011

This paper considers the problem of bending of a plate composed of two plates of materials having dissimilar elastic properties, bonded together along a straight line which sustains a crack. Both materials are assumed to be isotropic and homogeneous. Upon obtaining stress solutions, it is found that the significant stresses are inversely proportional to the square root of the radial distance from the crack front and have an oscillatory character, which is shown to be confined to the immediate vicinity of the crack tip. A two-parameter set of equations expressing the general form of the stress distribution around the tip of such a crack is provided as it is of primary importance in predicting the strength of cracked plates. Some analogies are also observed between the characteristic equations occurring in the extension and bending of cracked plates composed of dissimilar materials.
The Contact Problem of a Plate Pressed Between Two Spheres
Authors: Tu Yih-O , Gazis D. C.
Published: October 2011

The elastic contact of a plate with two axisymmetric bodies, generally of dissimilar elastic properties and curvatures, is considered. The solution of the resulting two integral equations is given as a truncated series of Legendre polynomials of even order whose coefficients may be determined from a system of linear algebraic equations. The relationships between the total load, radii of curvature of the bodies, contact radii, approach, radial displacements, maximum contact stress, and the plate thickness can then be computed in terms of these coefficients. Numerical computations have been carried out for the contact of a plate with two identical spheres.
An Automatic Network Analog Computer for the Solution of the Biharmonic Equation
Authors: Hlinka J. W. , Landau H. G. , Paschkis V.
Published: October 2011

It is known that the biharmonic equation in two dimensions can be solved by use of a pair of coupled electric resistance networks. In the present paper, a modification of this method is described, involving the use of a controller device of novel design. The controller automatically performs the iterations necessary for the solution of the problem. The procedure is applied to two problems: (a) The deflection of a square plate under uniform load, and (b) a plane-stress problem. Errors are evaluated by comparison with the solutions of the corresponding finite-difference problems and with an analytic solution. The sources of error are discussed and recommendations made for improving the computer accuracy.
Longitudinal Strain Pulse Propagation in Wide Rectangular Bars: Part 2—Experimental Observations and Comparisons With Theory
Authors: Jones O. E. , Ellis A. T.
Published: October 2011

The plane-stress theory presented in Part 1 is shown to predict qualitatively the warping of plane sections observed in transient fringe patterns obtained using birefringent coatings and in dynamic photoelastic pictures obtained in other investigations. Measurements using conventional techniques are described in which wide rectangular bars were subjected to a longitudinal step-function pressure loading produced by a shock tube. Comparisons show that the gross features of the experimental records for the head of the pulse are qualitatively predicted by the theory. Both theory and experiment show that short-wavelength, second-mode disturbances arrive very early. Experimentally it is observed that these disturbances are accomplished by thickness-mode activity which cannot be accounted for by the plane-stress theory.
Asymptotic Solutions for Unsteady Laminar Free Convection on a Vertical Plate
Authors: Menold E. R. , Yang Kwang-Tzu
Published: October 2011

Exact asymptotic solutions for unsteady free convection on a vertical plate with arbitrary surface temperature or heat-flux variations and Prandtl number are presented. Analytical solutions in closed forms are given for stepwise and linear variations in both surface temperature and heat flux and arbitrary Prandtl number. Also described are phase relations of thermal responses when the prescribed thermal conditions at the plate become periodic.
Thermal Results for Forced Heat Convection Through Elliptical Ducts
Authors: Dunwoody N. T.
Published: October 2011

The purpose of the present investigation is to determine numerical results in respect of the heat transfer to the wall of a duct which has an elliptic cross section and through which a hot viscous fluid flows with a steady established laminar motion. The wall of the channel is at a constant temperature which is less than that of the entering fluid. Results for several cross-sectional eccentricities are presented and correlated.
Energy Dissipation in Contact Friction: Constant Normal and Cyclic Tangential Loading
Authors: Goodman L. E. , Brown C. B.
Published: October 2011

When a sphere is held between parallel flat surfaces by means of a constant clamping pressure and is then subjected to a cyclic tangential displacement parallel to the flats, energy is dissipated at the contacts. This occurs even when the maximum tangential force, T*, is less than Tmax, the force which will just produce slip over the entire contact surface. Measurements of the energy dissipated per cycle and of the hysteresis loop shapes have been found to agree well with the theory of Mindlin and Deresiewicz in the range investigated, 0.45 < δ*/δmax < 1. The sphere diameter and the normal load appear as parameters only in the way demanded by the theory. In the range investigated energy dissipation appears to be primarily a surface phenomenon and not one due to material damping. The material employed has been AISI 316 steel.
On the Burmester Points of a Plane
Authors: Freudenstein Ferdinand , Sandor George N.
Published: October 2011

The paper is divided into three parts concerned with the Burmester points associated with five distinct positions of a plane. In the first part, “Theory,” an equation is derived for the location of the Burmester points; algebraic and geometric properties of these points are deduced and special cases considered. An automatic digital-computer program is described in the second part, “Computation,” using a parametric form of the equation for the Burmester points. In the third part, “Application,” the analytical form of Burmester theory is applied to the solution of a variety of problems in plane kinematic synthesis in one uniform manner.
A Nondestructive Three-Dimensional Strain-Analysis Method
Authors: Durelli A. J. , Daniel I. M.
Published: October 2011

The objective of this paper is to develop the technique of the embedded grid for three-dimensional strain and stress analysis. The application to the case of a sphere subjected to diametral loading is described and results are compared with theoretical and photoelastic ones. The limitations of the method are outlined and suggestions for improvement made. As it stands now, the method allows the nondestructive determination of three-dimensional strain fields with good precision. The determination of stresses, however, is less precise.
A Problem in Visco-Plasticity
Authors: Appleby E. J. , Prager W.
Published: October 2011

The paper treats the visco-plastic flow of a circular plate that is simply supported along its edge and subjected to a uniformly distributed transverse load. The material of the plate is supposed to be incompressible and rigid, visco-plastic. A linearized theory of visco-plasticity is used.
Fluid Flow Between Porous Rollers
Authors: Tao L. N. , Joseph D. D.
Published: October 2011

The problem of fluid flow between two porous rollers with a small gap is investigated. Solutions for both large and small values of the porosity of the minimum gap distance are derived. It is found that increasing porosity will decrease the maximum suction and shift its position away from the origin.
Shock Response of a Nonlinear System
Authors: Fung Y. C. , Barton M. V.
Published: October 2011

The dynamic response of a nonlinear, single-degree-of-freedom spring-mass system to shock loading is investigated. A specific value of the maximum deflection is chosen as a characteristic quantity called the “maximum allowable deflection”—which forms the starting point for a simplified presentation of the analytical results. The shock-response characteristics of each nonlinear system is compared with that of an associated linear system. In particular, the ratio of the magnitudes of the loads applied as a pulse to produce the same maximum allowable deflection in a nonlinear system and its associated linear system is defined as the “loading ratio.” This loading ratio, in combination with the usual “shock spectrum” for a linear system, can be used to determine the maximum dynamic load which a nonlinear system can withstand without exceeding the allowable deflection. A number of other engineering applications will be discussed also.
The Elastically Clamped Rectangular Plate With Arbitrary Lateral and Thermal Loading
Authors: Chao C. C. , Anuliker Max
Published: October 2011

Within the limits of classical thin-plate theory a variety of elementary problems have been solved for the rectangular plate3,4,5. In particular, the rectangular plate with edges simply supported or clamped has been dealt with at length and the solution to different loading cases given either in the form of a doubly infinite series or a single infinite series. In this paper a rapidly convergent series solution is outlined for the uniformly elastically clamped plate which is subjected to nonuniform lateral and thermal loading. The solution converges in the limit to those corresponding to the simply supported and rigidly clamped plate.
Experiments on the End Effect in Dual Material Columns
Authors: Becker E. C. H. , Conway H. D.
Published: October 2011

Compression experiments were made on columns formed from two circular cylinders of equal size with their flat ends in contact. From measurements of the diameters at various sections at and away from the junction, a measure of the end effect was obtained. The experiments were carried out on steel and brass cylinders in contact with one another, and with several diameters and contact-surface conditions. It was observed that the end effect with sand-blasted or physically joined ends disappeared after approximately two thirds of a diameter, irrespective of the diameter. This could easily be reduced to one third of a diameter by smoothing and lubricating the contact surfaces.
Stresses in Short Noncircular Cylindrical Shells Under Lateral Pressure
Authors: Romano Frank , Kempner Joseph
Published: October 2011

This paper presents an analysis of the deflections of and stresses in a short noncircular cylindrical shell of uniform wall thickness whose median-surface cross section is described analytically by a simple expression corresponding to a family of doubly symmetric ovals. The cylinder is under a uniform lateral load and is simply supported at its edges. The small deflection analysis considered is based upon a series solution of appropriate differential equations of shell theory which leads ultimately to infinite sets of algebraic equations, truncated forms of which are considered. Numerical values of the significant stresses and displacements for points of the oval cylinder, which are 5 percent of the axial length and 2.5 percent of the circumferential length a part, have been calculated for an oval cross section with a major-minor axis ratio of 1.10.
Note on the Large Deflection of a Certain Cylindrical Shell Panel
Authors: Basuli Sukumar
Published: October 2011

The large deflection of a supported cylindrical shell panel, all of the four edges of which are of equal length, is obtained following Berger’s approximate plate theory for large deflection.
A Bifurcation Phenomenon of Static Friction
Authors: Ling F. F. , Weiner R. S.
Published: October 2011

Measurements are reported of electric contact resistance, actual area of contact, static friction, adhesion and pure shear for lead on lead. The data exhibit a statistical bifurcation of friction. In other words, below extreme pressures, statistically there are two branches of the coefficient of friction versus normal load relationship. The nature of one of the branches is explicable exclusively in terms of the weld-junction or adhesion theory of friction. The nature of the other, however, is not so explicable. This points to the existence of what Holm [1] called the Y-term of friction, the nature of which has yet to be satisfactorily explained.
On the Aeroelastic Instability of Bluff Cylinders
Authors: Parkinson G. V. , Brooks N. P. H.
Published: October 2011

The validity of quasi-steady theory, using experimental aerodynamic coefficients, to explain the observed aeroelastic instability of bluff cylinders in a uniform stream is examined for several cylinder sections. Only plunging oscillation is considered, and the analytical model is an oscillator with nonlinear damping dependent on the aerodynamic coefficients. Static and dynamic wind-tunnel tests were made of cylinder models of square, rectangular, and D-section. The D-section and the short rectangular sections behaved dynamically like the circular cylinder, showing plunge instability only near resonance with the von Karman vortex street. In complete contrast, the square and long rectangular sections showed plunge instability with amplitude increasing with wind speed for all speeds above a critical value. These dynamic results were in quite good agreement with the theoretical predictions, using the static test data.
Bending and Stretching of Certain Types of Heterogeneous Aeolotropic Elastic Plates
Authors: Reissner E. , Stavsky Y.
Published: October 2011

The class of plates with which this paper is concerned includes as an important special case plates consisting of two orthotropic sheets of equal thickness which are laminated in such a way that the axes of elastic symmetry enclose an angle +θ with the x, y-axes in one sheet and an angle −θ in the other sheet. For plates of this type there occurs a coupling phenomenon between in-plane stretching and transverse bending which does not occur in the theory of homogeneous plates and which has not been considered in earlier work for such plates. The general results of the present paper are illustrated by means of explicit solutions for two specific plate problems.
Elastic-Plastic Design of Rectangular Pressure Tubing
Authors: Gauthier R. D. , Weibel E. E.
Published: October 2011

Elastic-plastic design permits the most effective use of the strength of the rectangular tube section. The condition of failure for a tube of perfectly elastic-plastic material is analyzed, and a formula is derived from which the limit load can be computed directly, A procedure is developed for determining by the area-moment method the wall deflection at any load from a bending-moment diagram modified to account for reduced rigidity. The total deflections thus found are plotted against the various loads. This theoretical load-deflection curve then becomes the basis for design.
Analysis for Calculating Lateral Vibration Characteristics of Rotating Systems With Any Number of Flexible Supports: Part 1—The Method of Analysis
Authors: Koenig E. C.
Published: October 2011

A method is presented for calculating the lateral vibration characteristics of rotating systems and establishes improved criteria for design. The method is also applicable to the vibration analysis of interconnected beam systems which are nonrotating and lying in a single plane. This first part restricts itself to the development of the method of analysis. A companion paper describes the experiences related to the computer program and to some of the applications of the method since 1957.
Description of a 2,683-Base-Pair Plasmid Containing
qnrD
in Two Providencia rettgeri Isolates
Authors: Guillard Thomas , Cambau Emmanuelle , Neuwirth Catherine , Nenninger Thomas , Mbadi Aurore , Brasme Lucien , Vernet-Garnier Véronique , Bajolet Odile , de Champs Christophe
Published: October 2011

qnr
genes are plasmid-mediated quinolone resistance genes mainly harbored on large conjugative multiresistant plasmids. The
qnrD
gene was recently observed in
Salmonella enterica
on a small nonconjugative plasmid (p2007057). We describe two strains of
Providencia rettgeri
harboring
qnrD
on nonconjugative plasmids. The plasmids were 99% identical, with 2,683 bp and four open reading frames, including
qnrD
, but exhibited only 53% identity with the plasmid found in
S. enterica
.
DISCOVERY AND EVALUATION OF POTENTIAL SONIC HEDGEHOG SIGNALING PATHWAY INHIBITORS USING PHARMACOPHORE MODELING AND MOLECULAR DYNAMICS SIMULATIONS
Authors: HWANG SWAN , THANGAPANDIAN SUNDARAPANDIAN , LEE YUNO , SAKKIAH SUGUNADEVI , JOHN SHALINI , LEE KEUN WOO
Published: October 2011

Sonic hedgehog (Shh) plays an important role in the activation of Shh signaling pathway that regulates preservation and rebirth of adult tissues. An abnormal activation of this pathway has been identified in hyperplasia and various tumorigenesis. Hence the inhibition of this pathway using a Shh inhibitor might be an efficient way to treat a wide range of malignancies. This study was done in order to develop a lead chemical candidate that has an inhibitory function in the Shh signaling pathway. We have generated common feature pharmacophore models using three-dimensional (3D) structural information of robotnikinin, an inhibitor of the Shh signaling pathway, and its analogs. These models have been validated with fit values of robotnikinin and its analogs, and the best model was used as a 3D structural query to screen chemical databases. The hit compounds resulted from the screening docked into a proposed binding site of the Shh named pseudo-active site. Molecular dynamics (MD) simulations were performed to investigate detailed binding modes and molecular interactions between the hit compounds and functional residues of the pseudo-active site. The results of the MD simulation analyses revealed that the hit compounds can bind the pseudo-active site with high affinity than robotnikinin. As a result of this study, a candidate inhibitor (GK 03795) was selected as a potential lead to be employed in future Shh inhibitor design.
Reassembling operator equalisation
Authors: Silva Sara
Published: October 2011

The recent Crossover Bias theory has shown that bloat in Genetic Programming can be caused by the proliferation of small unfit individuals in the population. Inspired by this theory, Operator Equalisation is the most recent and successful bloat control method available. In this work we revisit two bloat control methods, the old Brood Recombination and the newer Dynamic Limits, hypothesizing that together they contain the two main ingredients that make Operator Equalisation so successful. We reassemble Operator Equalisation by joining these two ingredients in a hybrid method, and test it in a hard real world regression problem. The results are surprising. Operator Equalisation and the hybrid variants exhibit completely different behaviors, and an unexpected feature of Operator Equalisation is revealed, one that may be the true responsible for its success: a nearly flat length distribution target. We support this finding with additional results, and discuss its implications.
Forty data communications research questions
Authors: Partridge Craig
Published: October 2011

About ten years ago, Bob Lucky asked me for a list of open research questions in networking. I didn't have a ready list and reacted it would be good to have one. This essay is my (long- belated) reply.
Synthesis of Copper and Copper-Ruthenium Nanoparticles in Ionic Liquids for the Metallization of Advanced Interconnect Structures
Authors: Arquilliere Philippe P. , Santini Catherine , Haumesser Paul-Henri , Aouine Mimoun
Published: October 2011

Bimetallic nanoparticles can be used in a variety of applications such as catalysis, in advanced magnetic or optical devices or as starting materials to form continuous metallic layers. In this study, we report the synthesis of bimetallic ruthenium-copper (Ru-Cu) nanoparticles in ionic liquids. For this purpose, solutions of ionic liquids containing a mixture of precursors of Ru and Cu were decomposed under dihydrogen. Small, crystalline and well dispersed Ru-CuNPs (2.5 ± 0.6 nm) were obtained, which are significantly smaller than the pure Ru or pure CuNPs formed under the same conditions. Our analyses suggest that these NPs have a Ru core - Cu shell structure. This structure is expected from thermodynamical and kinetics data. Moreover, this could explain the dramatic size reduction observed when mixing the two metals.
Models for Corrosion of Metals under Thin Electrolyte Layers
Authors: Venkatraman Murali Sankar , Bosco Infant Gabriel , Cole Ivan S. , Emmanuel Bosco
Published: October 2011

One-dimensional mathematical models are presented for the free corrosion of a metal surface under a thin electrolyte layer with or without an oxide layer. The models address anodic metal dissolution which is controlled by oxygen diffusion through the electrolyte layer and by the oxygen reduction at the metal surface. Under free corrosion the effect of a porous oxide layer under the thin electrolyte film which is either inert or supports the oxygen reduction on its surface is discussed.
Passivation Rates for Small Particulate Aluminum in Contact with Oxide and Nitride Powders
Authors: Padilla Victor E. , Skrovan John , Gasem Zuhair
Published: October 2011

The self passivation of aluminum in water generally prevents the generation of hydrogen from an aluminum-water reaction in conditions preferred for portable systems. However the corrosion rate of aluminum powders is seen to greatly increase when in contact with alumina powder. This allows commercially useful amounts of hydrogen to be generated at moderate temperatures and neutral pH regions. Scratch tests were run on aluminum disks covered with oxide and nitride powders to look at repassivation rates after the surface film was disturbed and a decrease in the repassivation time observed. Small pellets of aluminum powder mixed with oxide or nitride powders were also studied with scratch events showing far lower current perturbation than seen for pure aluminum.
Comparing Chain Length Effect of Single Chain and Gemini Surfactants on Corrosion Inhibition of Steel in Acid
Authors: Asefi Dourna , Arami Mokhtar , Mahmoodi Niyaz Mohammad
Published: October 2011

Corrosion inhibition efficiency of Gemini surfactant 1,4-butan-bis-dimethyl dodecyl ammonium bromide (designed as 12-4-12), 1,4-butan-bis-dimethyl tetradecyl ammonium bromide (designed as 14-4-14), conventional surfactants dodecyl thrimethyl ammonium bromide (DTAB) and tetradecyl thrimethyl ammonium bromide (TTAB) on low carbon steel is investigated using three common methods namely, weight loss, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS). The influence of chain length and temperature of the media is verified. Data indicate that, the corrosion inhibition efficiency is improved by increasing the concentration and chain length of the surfactants. Corrosion rate of steel increases by increasing the temperature of the medium containing surfactant. Adsorption isotherm of used surfactants and kinetic parameters are studied.
Kinetics of Metal Deposition via Surface-Limited Redox Replacement Reaction
Authors: Gokcen Dincer , Bae Sang -E. , Brankovic Stanko R.
Published: October 2011

In this work, we examined the kinetics of metal deposition via surface-limited redox replacement reaction (SLRR). The model system was Pt submonolayer deposition on Au(111) via redox replacement of Pb and Cu underpotentially deposited (UPD) monolayers (MLs) on Au(111). The deposition kinetics were studied through the formalism of the comprehensive analytical model developed to fit open circuit potential (OCP) transients from our deposition experiments. Reaction half time, reaction order, and reaction rate constant were extracted and discussed within the frame of their application to the design and control of deposition experiments. Through the scope of the analytical model, different aspects of SLRR (i.e., the nature of the UPD metal monolayer participating in the redox reaction, the transport limitation, and the role of the anions/electrolyte) were investigated in terms of their effects on the reaction kinetics.
Redox Catalysis for Dehydrogenation of Liquid Hydrogen Carrier Fuels for Energy Storage and Conversion
Authors: Driscoll Peter , Deunf Elise , Rubin Leah , Luca Oana , Crabtree Robert , Chidsey Christopher , Arnold John , Kerr John
Published: October 2011

The process of redox catalysis has been known and well studied theoretically and experimentally for several decades. Studies of redox catalysis can be instrumental in determining mechanistic aspects of electrochemical reactions and in measuring basic thermodynamic and kinetic parameters. The application of redox catalysis to the electrochemical dehydrogenation of organic molecules is of interest for a hybrid flow battery/fuel cell system for energy storage. Redox catalysis has the ability to reduce the overpotential of the dehydrogenation reaction used in such a system. The mechanism of catalysis can involve an ECE-type reaction or a CEE-type reaction. In either case the acid-base chemistry of the medium is critical. Preliminary results of catalytic current measurements as a function of redox catalyst, base concentration, and base strength are described along with possible reaction mechanisms.
Preferential Oxidation of CO Based on Electro-Thermally Assisted Catalytic Ni/Cu Nanostructures on Si Micro-Grass
Authors: Ebrahimi Aida , Mohajerzadeh Shamsoddin , Alihosseinzadeh Amir , Khodadadi AbbasAli , Mortazavi Yadollah
Published: October 2011

We propose a novel electro-thermal method to fabricate catalytic structures for preferential oxidation of carbon-monoxide (CO) based on nickel and copper nanostructures formed on tip of textured silicon micro-grasses. The silicon surface is textured to realize micro- and nano-structures using a reactive ion etching (RIE) process followed by electron-beam deposition of a thin layer of Ni or Cu. The formation of catalytic nano-sized structures is achieved by applying a DC voltage in a chamber with hydrogen flow. The conversion efficiency has been examined and various parameters involved in this phenomenon have been studied.
Catalytic Performance of Pt/C Catalyst by Pulse-Microwave Assisted Chemical Reduction: Effect of Microwave Irradiation Time
Authors: Zheng Jun-Sheng , Wang Xi-Zhao , Fu Rong , Deng Peng , Ma Jian-Xin
Published: October 2011

Pt/C catalysts were synthesized by a pulse-microwave assisted solvent chemical reduction (PMWSCR) process, and the microwave irradiation time effects on physico-chemical properties and electrocatalytic performances of catalysts were investigated. High resolution transmission electron microscope (HRTEM) images showed that the sizes of platinum nanoparticles synthesized by PMWSCR were about 1.9-2.6 nm, and the microwave irradiation time had an important influence on metal nanoparticle size and distribution. Cyclic voltammetric analysis revealed that the electrochemical surface areas of electrocatalysts were influenced by the microwave irradiation time, and the highest surface area of catalyst appeared when the microwave irradiation time was 12s. Single cell testing results proven that the catalyst had the maximum power density when the microwave irradiation time was 12s.
(The Gordon E. Moore Medal for Outstanding Achievement in Solid State Science and Technology Award) Wide Bandgap Semiconductors for Electronics, Photonics, and Sensing Applications
Authors: Pearton Stephen J. , Ren Fan
Published: October 2011

Recent progress in development of GaN-based transistors for gas and bio-sensing applications and amorphous IGZO layers for use thin film transistors (TFTs) on flexible substrates, including paper, is presented. For the detection of gases such as hydrogen, the gateless GaN transistors are typically coated with a catalyst metal such as Pd to increase the detection sensitivity at room temperature. Functionalizing the surface with oxides, polymers and nitrides enhances the detection sensitivity for gases and ionic solutions. The use of enzymes or antibody layers on the surface leads to highly specific detection of a range of antigens of interest in the medical and security fields. We give examples showing sensitive detection of glucose, prostate cancer and breast cancer markers and the integration of the sensors with wireless data transmission systems. The amorphous transparent conducting oxide InZnGaO4 (IGZO) is attracting attention because of its high electron mobility, high transparency in the visible region and its ability to be deposited with a wide range of conductivities. This raises the possibility of making low-cost electronics on a range of arbitrary surfaces, including paper and plastics. Remaining obstacles to use of IGZO TFTs are presented.
A Comparative Study of the Performance of Ultra-Porous Membranes as Separators in Supercapacitor Devices
Authors: Laforgue Alexis , Robitaille Lucie
Published: October 2011

Commercial porous membranes as well as in-house fabricated ultraporous nonwoven membranes were tested as separators in aqueous carbon-based supercapacitors. The separators were obtained by electrospinning and melt-blowing of nonwoven nano and microfibers. A pressure-controlled laboratory cell was designed and fabricated in order to precisely compare the supercapacitor performance and discriminate the separator influence. The electrochemical results showed that the separator does not influence the capacitance of the cell but has a significant impact on its internal resistance. It was demonstrated that increasing the porosity of the separator led to a decreased cell resistance and then to a higher energy available at high power demand.