bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Misaligned Grooved Journal Bearings
Authors: Pinkus Oscar , Bupara S. S.
Published: November 2010

The paper presents a comprehensive analysis of misaligned journal bearings. The equations are valid for finite bearings containing grooves at any angular position in which the misalignment can vary in magnitude as well as in direction with respect to the bearing’s boundaries. The relevant equations, the method of solution, and a set of results for the case of L/D = 1 are presented. Charts are offered for a number of additional cases which bring out some of the salient features of grooved bearing misalignment.
Experimental and Analytical Load-Life Relation for AISI 9310 Steel Spur Gears
Authors: Townsend D. P. , Coy J. J. , Zaretsky E. V.
Published: November 2010

Life tests were conducted at three different loads with three groups of 8.9 cm (3.5 in.) pitch diameter spur gears made of vacuum arc remelted (VAR) AISI 9310 steel. Life was found to vary inversely with load to the 4.3 and 5.1 power at the L10 and L50 life levels, respectively. The Weibull slope varied linearly with maximum Hertz contact stress, having an average value of 2.5. The test data when compared to AGMA standards showed a steeper slope for the load-life diagram.
Sensitivity Analysis and Optimization of Structures for Dynamic Response
Authors: Haug E. J. , Arora J. S. , Feng T. T.
Published: November 2010

A state space method of optimal design of structures under transient dynamic excitation is developed and three problems are solved. It is shown that exploitation of the mathematical form of the equations of structural dynamics leads to significant computational efficiencies. A factor of five reduction in computing time is shown to be achievable, relative to more conventional nonlinear programming methods.
Rotational Vibration With Backlash: Part 1
Authors: Wang C. C.
Published: November 2010

This paper considers the problem of dynamic tooth loads on lightly loaded precision class gears running at high speed. It provides theoretical and experimental explanations of the surprising fact that lightly loaded gears may suffer from both pitting and tooth breakage, while the same gear, heavily loaded, is immune from such damage. In the theoretical part, two idealized mathematical models—a two-mass system and a three-mass system—are analyzed. Both models provide for consideration of time-varying backlash (backlash is a function of gear angular position) as well as impact and displacement excitations. Large dynamic tooth load was shown to result from backlash impact, on both drive and nondrive tooth flanks. The motion was termed “rotation vibration” to distinguish it from “torsional vibration” as commonly understood. Rotational vibration includes torsional vibration as well as the “rigid body mode” oscillation of a mathematical form similar to a ball bouncing upon an oscillating table. In the experimental part, a testing rig was specially designed and built. The test results confirm the theory.
A Study on Hourglass Worm Gearing With Developable Tooth Surfaces
Authors: Sakai T. , Maki M. , Uesugi S. , Horiuchi A.
Published: November 2010

The authors developed a new type of hourglass worm gearing based on the authors’ own theories [1, 2]. The worm having the developable tooth surface can be ground precisely. The pair of the tooth surfaces of the gearing have comparatively small relative curvature and contact with each other with the contact line lying perpendicularly to the relative sliding velocity. The manufactured gears showed the efficiency of 80 percent with the authors’ experimental apparatus without trouble in continuous running test over 3000 hours. Conditions are: reduction ratio, 40; center distance, 100 mm; input power, 3.7 kW; rotating speed of the worm, 1800 rpm.
Analytical and Experimental Studies of a Dynamic System With a Gap
Authors: Masri S. F.
Published: November 2010

An analytical and experimental study is made of the forced vibration of a dynamic system with a motion-limiting stop, which is encountered in many practical cases involving mechanical equipment. An exact closed-form analytical solution is derived for the steady-state motion of the system when it is subjected to harmonic excitation. Experimental measurements with a mechanical model verify the analytical findings. The effects of various system parameters on the response are determined. Some interesting features of the motion are observed and compared to the jump resonance phenomenon exhibited by the solution of Duffing’s equation.
Forced Vibration of Continuous System With Nonlinear Boundary Conditions
Authors: Watanabe T.
Published: November 2010

This paper deals with the nonlinear vibration problem concerning mechanical equipment-piping systems in nuclear power plants and others. An analytical method by approximate solutions is introduced for these systems as a continuous system with nonlinear boundary conditions, and some numerical examples are shown. Finally some numerical results obtained as a continuous system are compared with those of a single-degree-of-freedom system.
Torsional Vibrations of a Vehicle Drive Line
Authors: Catchpole A. P. , Healy S. P. , Hodgetts D.
Published: November 2010

A theoretical and experimental study of drive-line torsional vibrations of a European saloon car is reported. Vibration histories, taken from a number of stations along the drive-line, and passenger compartment noise levels, were recorded in a series of road tests. Resonances were identified from spectral maps and order plots based on the results of digital analyses. A torsional resonance was identified as causing high noise levels in the car.
The Elastic-Dynamic Behavior of a Counterweighted Rocker Link with an Overhanging Endmass in a Four-Bar Linkage—Part I: Theory
Authors: Jandrasits W. G. , Lowen G. G.
Published: November 2010

The theoretical part of an investigation of the elastic-dynamic behavior of a counterweighted four-bar linkage rocker link, which in addition carries an overhanging mass, is given. The linearized equations of motion are derived by way of Hamilton’s integral, a novel elastic mechanism constraint equation, and the method of Kantorovich. The normal modes of the free vibration of the complex link provide the space portions of the solution, while the time portions are furnished by the resulting Hill’s equations. Floquet theory is adapted for stability considerations and a method for obtaining steady-state solutions is given. Part II applies the solution techniques to a specific mechanism and reports on confirming experimentation.
Design Analysis of an Epicyclic Rotary Pump Mechanism
Authors: Sadler J. P. , Nelle D. E.
Published: November 2010

A planetary gear train is analyzed and an application of the mechanism as a rotary pump is examined. General kinematic and static force analyses are performed, and expressions for housing and rotor profiles are derived. Numerical optimization yields good approximations of the nearly square housing and the triangular rotor using easy-to-produce geometric shapes. Different rotating chamber arrangements are considered and chamber volume variations are computed. A physical model which has been constructed to demonstrate the motion properties is discussed.
Displacement Analysis of a Spatial 7R Mechanism—A Generalized Lobster’s Arm
Authors: Duffy J. , Derby S.
Published: November 2010

An input-output equation of degree 24 is derived for a spatial 7R mechanism with consecutive pair axes intersecting. This mechanism is essentially the mathematical model for the kinematic analysis of a lobster’s arm which is an open 6R chain with mutually perpendicular consecutive pair axes, the geometry of which was first described by Willis [4] in 1841. The analysis of this special 7R mechanism constitutes a major step towards the solution of the general 7R mechanism with seven axes arbitrarily oriented in space.
A New Key and Keyway Design
Authors: Orthwein W. C.
Published: November 2010

A review of the history of the analysis of torsionally induced shaft stresses due to the inclusion of an empty keyway, or keyseat, is given with emphasis placed upon experimentally measured values. More realistic stresses recently found by photoelastic analysis of a shaft in which the keyways were not empty are then presented. A new, patented (U.S. Patent 3 920 343, Nov. 18, 1975 assigned to the U.S.), and operating key and keyway design which resulted from these tests, wherein the twisting forces were actually applied through the keys, is described toward the close of the paper.
Interactive Modeling and Analysis of Open or Closed Loop Dynamic Systems with Redundant Actuators
Authors: Williams R. J. , Seireg A.
Published: November 2010

This paper deals with the development of a computer-based procedure for the modeling and analysis of large displacement dynamic systems of the open or closed loop types. The procedure facilitates the construction of the model for such systems, automatically formulates the dynamic equations and provides the solution for any given input motion. The program is capable of analyzing complex systems with redundant force actuators utilizing a linear programming optimization scheme. It incorporates an interactive graphic capability which is invaluable in the construction, modification and visual checking of a model. The modeling procedure is general in nature and is applicable to systems of many connected rigid bodies. Its capabilities are illustrated in this paper by evaluating muscle forces and joint reactions of the musculoskeletal structure during dynamic activity. The system is readily applicable to the analysis of the actuation schemes in human and animal locomotion, many classes of machine systems, as well as robots and manipulators. Although only applications to open loop mechanisms are presented in this paper, the program can be readily extended to treat closed loop systems as well.
On The Torsional Vibration of Branched Systems Using Extended Transfer Matrix Method
Authors: Sankar S.
Published: November 2010

A novel method for the analysis of free vibration of branched torsional systems is presented. The method is radically different from the traditional methods in that an extended transfer matrix relation is formulated for each branch. For this, the calculations are propagated from the junction and proceed simultaneously in all branches toward their respective ends. Then by substituting the compatibility and equilibrium conditions, a frequency dependent characteristic matrix is formulated. This procedure automatically eliminates the need of any additional operation such as matrix inversion and the solution of a system of equations for the formulation of the characteristic matrix and also reduces the size of the matrix. Finally, the boundary conditions are applied to the matrix relation and the natural frequencies are determined from the roots of a frequency determinant derived from the characteristic matrix. For this purpose, the paper introduces a method based on the Newton-Raphson iterative technique which systematically finds the roots of the frequency determinant using both the value of the determinant and its derivative with respect to square of the natural frequency. The paper also presents a procedure for calculating these derivatives directly from the formulation of the extended transfer matrices. Numerical examples are given to illustrate the simplicity and straightforwardness of the proposed method in finding the natural frequencies of complex branched torsional systems. Results indicate that the method is accurate and allows a greater degree of error in the selection of trial frequencies.
Dynamic Analysis of Spatial Mechanisms Using Dual Successive Screw Method and D’Alembert’s Principle
Authors: Lee In-Ping J. , Soni A. H.
Published: November 2010

The method based on the application of the successive dual screw displacements and d’Alembert’s principle, is developed to perform kinetostatic and dynamic analysis of space mechanisms with lower kinematic pairs. The method is applied to demonstrate its usefulness in performing kinetostatic and dynamic analysis of single-loop, four-link, five-link, six-link and seven-link mechanisms with lower kinematic pairs.
Selective Precision Synthesis of the Four-Bar Motion Generator With Prescribed Input Timing
Authors: Kramer S. N.
Published: November 2010

The recently developed Selective Precision Synthesis technique has been extended to the four-bar motion generating mechanism with prescribed input timing. A designer using this method can determine several mechanisms whose coupler triangle positions and orientations will be coordinated with the input crank rotations. The unique feature in the Selective Precision Synthesis formulation is that the path, orientations and rotations are specified along with allowable limits of accuracy creating an error envelope for each of these parameters. This modification removes the limiting conditions imposed by the precision point approach so that standard nonlinear programming techniques can be used to determine several mechanism solutions. It was found that the method yields fundamentally stable solutions rarely encountered in closed-form methods of mechanism synthesis. The problem of dyadic construction error in the original SPS technique is eliminated and the method developed here is well suited to batch or interactive computer-aided design. The computer program of this method is being made available to interested readers.
Rub-Induced Parametric Excitation in Rotors
Authors: Childs D. W.
Published: November 2010

Analysis is presented which explains earlier hypotheses and experimental results that circumferential stiffness variations induced by rubbing over a portion of a rotor’s orbit can lead to parametric excitation of half-speed whirl at a rotor’s natural frequency. The results do not explain cited occurrence of 1/3 and 1/4 running-speed whirl associated with the operation of rotating machinery. A polar-coordinate version of the Jeffcott model is employed to model the effect of rubbing over a portion of a rotor’s precessional orbit, with the rub-induced restoring force defined in terms of a Fourier series expansion. Rubbing contact between a rotor and its housing results in both an increased radial stiffness and a tangential force due to Coulomb friction. Hence, there are two mathematically distinct sources for rotor parametric excitation, and the results concern the influence of viscous damping on the ranges of unstable speeds induced by these two sources of parametric excitation. The analysis based on Hsu’s method yields the following results: (a) For zero Coulomb and external viscous damping, parametric excitation yields a band of unstable speeds about a running speed that is twice the natural frequency (ω = 2λ). (b) For finite Coulomb damping and no viscous damping, a rotor in a partial rubbing condition is predicted to be unstable at all running speeds. (c) External damping reduces the range of unstable running speeds centered about the ω = 2λ parametric excitation frequency, and sufficient damping completely eliminates the instability.
Nonlinear Effects on the Discontinuity Stresses in a Cylindrical Shell With a Flat Head Closure
Authors: McDonald C. K. , McDonald R. E.
Published: November 2010

The effect of large displacements on the flexural edge stresses in thin cylindrical shells with flat head closures subjected to axisymmetric loads is considered. Results are presented which show that neglecting this nonlinear effect leads to nonconservative results. However, it is shown that these effects can usually be safely neglected except for very thin shells or for shells with a low modulus of elasticity. Curves are given which illustrate this effect for selected shell parameters.
Line Load on Cylindrical Shell With End Plates
Authors: Williams J. H.
Published: November 2010

The elastic static stresses and displacements in a shell with end plates are determined when a circular cylinder is subjected to a uniform line load along a generator. The method of solution is the superposition of a particular solution in which the shell’s response is computed for simply supported end conditions and a complementary solution in which the true end plate reactions are imposed on the ends of the cylinder. Examination of the end conditions reveals that the assumptions Nx = w = 0 (no axial force and no radial displacement) are generally justified whereas the assumptions Mx = 0 and v = 0 (no axial moment and no circumferential displacement) will usually lead to considerable relative errors in the axial bending stresses and the circumferential membrane stresses, respectively.
The Shear Stud Closure
Authors: Jorgensen S. M.
Published: November 2010

A report on a new type high-pressure shear stud closure developed and patented by the Foster Wheeler Corporation and fabricated commercially by the Chicago Bridge & Iron Company. Details of design and development data are noted with a large diameter closure application.
Nonlinear Finite-Element Method for Plates and Its Application to Dynamic Response of Reactor Fuel Subassemblies
Authors: Belytschko T. , Marchertas A. H.
Published: November 2010

A finite-element procedure for transient analysis of plates and shells in three-dimensional space, and applicable to large displacements and nonlinear material properties, is described. This procedure employs a convected coordinate formulation enabling the use of simple strain-nodal displacement and nodal force-stress relations. The plate/shell element considers linear in-plane displacements and cubic transverse displacements. The orientation of lumped masses is described by unit vectors so that arbitrarily large rotations can be treated. Discretized equations of motion are integrated explicitly in time with a difference formula. Membrane artificial viscosity is utilized to stabilize occasional oscillations. The computational efficiency of the procedure is quite good: one element-time step takes 2 msec on an IBM 360/195 computer. Comparison of results with experimental data of impulsively loaded plates shows good agreement. The program was applied to a hexagonal fuel subassembly loaded internally. Various results are presented on its response and it is shown that, for that type of loading, two-dimensional cross-sectional models may be adequate.
Pressure Wave Transmission in a Fluid Contained in a Plastically Deforming Pipe
Authors: Fox G. L. , Stepnewski D. D.
Published: November 2010

The transmission of high pressure pulses through piping loops such as reactor cooling systems is usually studied with water hammer analysis techniques. Conventional wave analysis includes only elastic pipe wall deformation. However, plastic deformation of the pipe wall is effective in reducing the magnitude of transmitted pressure waves if the pressure is of sufficient magnitude to cause plastic yielding. This effect can be treated using a one-dimensional dynamic analysis by noting the similarity between the equations describing pressure wave induced plastic deformation in a solid bar and wave transmission causing plastic strain in a fluid filled pipe. The results of the analysis show that at fluid pressures less than the pipe yield pressure, waves are transmitted at elastic wave velocity; however, at pressures which exceed the pipe yield point, wave velocities are substantially reduced and the waves are dispersed. These results demonstrate that plastic deformation from transient pressure loading is limited to a relatively short length of piping near the source of the pressure pulse. The significance of this behavior with respect to reactor cooling systems is that pressures above those causing yield are not transmitted to primary loop components such as pumps and heat exchangers. The theoretical results are compared with experimental tests and show reasonable agreement.
Dynamic Responses of Two Parallel Circular Cylinders in a Liquid
Authors: Chen Shoei-Sheng
Published: November 2010

The problem of two parallel circular cylinders vibrating in a liquid is studied analytically. First, the equations of motion including fluid coupling are derived using the added mass concept. Then, a closed form solution and an approximate solution are obtained for free vibration. Finally, the steady-state responses of two cylinders subjected to harmonic excitations are presented. The results of this study illustrate the significance of the interaction of two structures in a liquid.
Incremental Solution Procedure for Nonlinear Structural Dynamics Problems
Authors: Jones R. F. , Roderick J. E.
Published: November 2010

A general incremental formulation is presented for solving nonlinear structural dynamic problems. The formulation introduces a new term which is not obtained in the usual finite element tangent stiffness approach. The generality of the derivation is used to show how the computation of the geometric stiffness matrix can be eliminated and its contribution included through a simple addition of the estimated incremental displacements to the equilibrium correction term. This approximation thus has the potential for saving significant computing time in the assemblage of higher order finite elements. Two simple numerical experiments are conducted and it is shown that accuracy is still retained when this approximation is used.
A Comparison of the Capability of Four Hardening Rules to Predict a Material’s Plastic Behavior
Authors: Hunsaker B. , Vaughan D. K. , Stricklin J. A.
Published: November 2010

Isotropic hardening, Prager-Ziegler kinematic hardening, the Mroz model, and the mechanical sublayer model are investigated to determine which of these hardening rules are better suited for use in nonlinear small strain analysis of metal structures by the finite element or finite difference methods. The material response predicted by each hardening rule is compared with experiments from the literature for uniaxial and biaxial loading of metals. Computer storage requirements for each model are then presented along with the results of the elastic-plastic analysis of an impulsively loaded plate. Recommendations are then made of appropriate hardening rules based on material characteristics and loading conditions.
Further Observations on A533-B Steel Plate Tailored for Improved Radiation Embrittlement Resistance
Authors: Hawthorne J. R.
Published: November 2010

A series of advanced investigations on the radiation performance of four 6-in-thick plates from a large (30-ton) commercial melt of A533-B steel is described. The melt represented the first commercial scale demonstration test of improved radiation embrittlement resistance through the control (minimization) of selected residual impurity elements. Melt specifications emphasized the attainment of a low copper and phosphorus content; one half of the melt was modified, however, by a copper addition (0.03 percent Cu increased to 0.13 percent Cu). Initial plate tests described superior 550 F (288 C) radiation resistance, in terms of notch ductility retention, for the primary melt composition and verified the detrimental influence of impurity copper on irradiation behavior. Promising capability of the primary melt composition for very high fluence (∼2.5 × 1020 n/cm2 > 1 MeV) service is shown by the current investigations. In addition, a significant influence of copper content on radiation resistance is revealed for a broad range of exposure temperatures. A dependence of 650 F (343 C) postirradiation heat treatment response (notch ductility recovery) on copper content was also found. Charpy-V versus dynamic tear test performance and tensile strength trends with temperature are examined for low (<450 F, 121 C) and elevated (550 to 585 F, 288 to 307 C) temperature irradiation conditions.
Elastic-Plastic Analysis of Curved Structures Subjected to Static and Dynamic Loads
Authors: Fettahlioglu O. A. , Toridis T. G.
Published: November 2010

A method is presented for the finite-element analysis of curved planar structures consisting of a combination of thin straight and curved beam elements. In the analysis both static and dynamic loads, elastic-plastic deformations, strain-hardening and hysteresis effects are taken into consideration. The properties of the curved beam element are derived based on the exact solutions of previously developed Euler differential equations for a circular ring accounting for the effect of extensional deformations. The elements of the stiffness and consistent mass matrices of the planar curved beam element are derived in closed-form, thus eliminating the loss of computer time and round-off errors associated with extensive matrix operations in the computational algorithm. The effect of rotary inertia is also considered in the derivation of the consistent mass matrix. The applicability of the analytical method presented herein is demonstrated by the solution of some typical structures subjected to static and dynamic loads, in particular, pipe whip restraints.
Stress Intensity Factors for Reactor Vessel Nozzle Cracks
Authors: Smith C. W. , Peters W. H. , Jolles M. I.
Published: November 2010

A method consisting of a marriage between frozen stress photoelasticity and a computerized least-squares data analysis for extracting stress intensity factor (SIF) distributions in three-dimensional cracked body problems is reviewed. Results from the application of the method to three programs dealing with nozzle corner cracks are discussed. The importance of using actual flaw shapes in analysis is stressed. It is concluded that the flaw growth in such problems is generally not self-similar due to the complexity and variety of boundary shapes. The experimental technique described appears to offer a viable independent estimate of SIF distributions for such problems.
Use of Explosives to Enhance Power of a New Design of Pile Hammer
Authors: Graff W. J. , Gomah E. M. , O’Neill M. W.
Published: November 2010

The purpose of this paper is to describe the adaptation of conventional concepts of internal ballistics to the driving of piles. Special considerations are given to the differentiation between the usual solution for guns, in which a lightweight projectile is propelled at a very high velocity, and a pile driving hammer propelling a ram with a relatively low velocity. The basic premise of a high explosive hammer is introduced, and a scheme is suggested for obtaining a pressure-space relationship for the propellant chamber and the velocity of a movable ram, comprising the base of the chamber, at the time it impacts a pile. The feasibility of using such a hammer to drive an offshore deep penetration pile in a deposit of clay is investigated by means of wave equation modeling.
Fluid Flow and Heat Transfer Through Hydraulically Induced Fractures in Hot, Dry Rock Masses
Authors: Nemat-Nasser S. , Ohtsubo H.
Published: November 2010

Geothermal energy extraction from hot, dry rock requires the circulation of water under pressure through a crack with a small opening (several millimeters) and a large radius (several hundred meters) at several kilometers beneath ground surface. Here we present the basic two-dimensional field equations for the fluid flow and heat transfer, by systematically integrating over the crack thickness the fundamental mass, momentum, and energy equations. The importance of various terms on physical grounds is briefly discussed, and on this basis the corresponding equations are simplified. Finally, with the aid of a finite-element approximation, typical illustrative examples are worked out. These examples reveal that a more accurate estimate for the effective conductivity between fluid and the solid must be obtained in order to more realistically estimate the basic heat extraction process. In particular, the effect of secondary cracks must be carefully examined. This and related aspects of the problem are discussed, and certain areas in need of further research are pointed out.
Pile Foundations in Frozen Soils
Authors: Phukan A.
Published: November 2010

A design philosophy for pile foundations in frozen soils is presented whereby seven different pile types may be used in different frozen subsoil conditions. The mechanics of frozen ground as well as of geotechnical engineering are emphasized to select a particular pile type. Various factors governing the pile-load capacity are analyzed to determine the worst design conditions which include the evaluations of summer and winter loadings.
Thermal Stresses Induced into Two Plane Strain Sectors Having Different Material Properties
Authors: Wang I-Chih , Eimermacher J. P.
Published: November 2010

Thermal stresses induced into two joined plane strain sectors having different physical properties and subjected to a uniform temperature distribution are investigated. Considering the elastic equations of equilibrium, compatibility, the stress-strain equations and appropriate boundary conditions, airy stress functions are formulated which describe the structural characteristics of the sectors. Stress and displacement relations are then obtained. Numerical examples are given illustrating the usage and general application of the derived expressions.
Inelastic Behavior of Finite Circular Cylindrical Shells
Authors: Chern J. M. , Pai D. H.
Published: November 2010

In the design of elevated temperature components such as those encountered in Liquid Metal Fast Breeder Reactor (LMFBR) service, the designer/analyst is often faced with the task of having to assess structural adequacy of pressure vessel and piping components which experience high cyclic thermal stresses. Expensive and time consuming detailed inelastic analyses using finite element techniques are often necessary for such an assessment. Experience with the design of the LMFBR components has focused on an urgent need for simplified inelastic analysis methods which can aid the designer/analyst in scoping the design and minimize the number of parts requiring detailed inelastic analysis. Through its participation in the FFTF (Fast Flux Test Facility) and CRBRP (Clinch River Breeder Reactor Plant), Foster Wheeler Energy Corporation has developed a series of simplified analysis computer programs. The underlying philosophy in this work has been to make simplifying assumptions on the structural model but to solve the resulting boundary value problem as exactly as practicable so that approximations in the stress state or constitutive equations are not introduced. This paper is the third in a series [1, 11] by the authors dealing with the elastic-plastic-creep behavior of cylindrical structures. A rate formulation is presented for the elastic-plastic-creep analysis of finite circular cylindrical shells with various end conditions subjected to varying axisymmetric pressure loads, through-the-wall and along-the-length temperature gradients, and either axial loads or axial deformations. The solution procedure is based on direct integration and successive approximation and shown to be efficient in dealing with complicated loading histories. Applications of the present method of analysis are illustrated by numerical examples of elevated temperature design problem.
Three-Dimensional Force and Deflection Analysis of a Variable Cross Section Drill String
Authors: Walker B. H. , Friedman M. B.
Published: November 2010

A mathematical model of an oil field drill string which includes the effect of torque has been developed. The drill string can include arbitrary members with known mechanical properties. The solution gives the three-dimensional deflection curve, forces on the borehole wall, the magnitude and direction of the resultant force and slope of the deflection curve at the bit.
Influence of Material Orthotropy on the State of Stress Around a Circular Hole in a Cylindrical Shell
Authors: Lakshminarayana H. V. , Viswanath S.
Published: November 2010

Numerical solutions are obtained for stresses around a circular hole in laminated composite cylindrical shells subjected to uniform internal pressure loading. Matrix method of structural analysis using a high-precision triangular laminated anisotropic cylindrical shell finite element is employed. Results are presented to show significant influence of composite material systems, winding patterns and curvatures on the state of stress around the opening.
Limit Design of Perforated Cylindrical Shells per ASME Code
Authors: Porowski J. S. , O’Donnell W. J. , Farr J. R.
Published: November 2010

Limit pressures are evaluated for cylindrical perforated shells containing circular holes arranged in the various penetration patterns typically found in practice. Statically admissible discontinuous fields of stress are used to obtain rigorous lower-bound limit pressures. These solutions are shown to be quite close to the actual limit pressures based on the efficiency of the discontinuous fields of stress and a comparison with upper-bound solutions. The optimal spacing parameters are obtained over the interesting range of ligament efficiencies for both the diamond (romboidal) and rectangular penetration patterns. The results of this work show that for most penetration configurations, the present ASME standards require substantially thicker shells than would be needed to maintain the same safety factors that are used for unperforated shells. On the other hand, the British and German standards allow the use of thinner shells than would be needed to maintain the safety factors for unperforated shells. Revised design curves which provide the same margin of safety for all configurations are derived and are proposed for use in design standards.
Dynamic Response of a Circular Cylinder Subjected to Liquid Cross Flow
Authors: Chen S. S. , Jendrzejczyk J. A.
Published: November 2010

This paper describes a series of experimental investigations of single tubes subjected to crossflow. The experiments have two distinct features: 1–the damping in the lift and drag direction is measured as a function of reduced flow velocity; 2–the detailed response characteristics of the tube are obtained at various reduced flow velocities. The analytical model is also presented to correlate with the experimental data. The results of this study provide some additional insight into the response characteristics of a single tube subjected to liquid cross flow including, among others, flow-velocity dependent damping and “lock-in” region of tube motion in the drag direction.
Maximum Isentropic Flow of Dry Saturated Steam Through Pressure Relief Valves
Authors: Thompson L. , Buxton O. E.
Published: November 2010

The maximum isentropic flow of dry saturated steam using iterative computer techniques with standard (ASME) steam property data is determined. Comparison of this maximum flow with the Napier flow (the calibrating ideal flow for ASME pressure relief valve capacity ratings) reveals significant divergence between the two. A correction factor is developed to be applied to existing ASME safety and safety relief valve capacity ratings to rectify the difference. Experimental flow measurement work verifying the divergence between the maximum isentropic flow and the Napier flow is described.
Elasto-Plastic Analysis of Perforated Plates Containing Triangular Penetration Patterns of 10 Percent Ligament Efficiency
Authors: Jones D. P. , Gordon J. L.
Published: November 2010

The finite element method is utilized to obtain the elasto-plastic stress and strain fields in a perforated plate made of a work-hardening material. The perforated plate contains penetrations arranged in a triangular pattern with a ligament efficiency of 10 percent and is considered to be in a state of plane stress. Stress distributions as well as strain concentration factors are presented for the two orthogonal uniaxial and the pure shear load cases. Effective elasto-plastic equivalent solid plate properties are presented in terms of Hill’s anisotropic deformation plasticity theory. The localized stress and plastic strain distributions are discussed in terms of the work-hardening characteristics of the material. Conclusions are drawn relevant to the plastic design and analysis of perforated plates.
Elastic-Plastic Buckling of Internally Pressurized Thin Torispherical Shells
Authors: Galletly G. D. , Radhamohan S. K.
Published: November 2010

The elastic-plastic buckling of internally pressurized torispherical shells is considered in some detail in the paper. The effects of geometric parameters (r/D, RS/D and D/t) and material properties (σyp, E and the strain-hardening coefficient) on the elastic-plastic internal buckling pressures were investigated using the BOSOR 5 program. Based on the results of the parametric study, approximate formulas for predicting the elastic-plastic internal buckling pressures are suggested. These should be useful to designers.
Zooplankton, lipids and stable isotopes: importance of seasonal, latitudinal, and taxonomic differences
Authors: Syväranta Jari , Rautio Milla
Published: November 2010

We found considerable seasonal, latitudinal, and taxonomic differences in zooplankton lipid content and concurrent δ13C values of zooplankton. We collected cladoceran as well as cyclopoid and calanoid copepod zooplankton from boreal and subarctic lakes throughout a year, allowing us to study zooplankton likely subjected to different isotopic fractionation processes and with highly variable lipid contents. Considerable seasonal variation was observed in the difference between bulk and lipid-extracted zooplankton δ13C values, indicating that seasonally changing lipid content introduced notable variation in zooplankton δ13C values. The difference between bulk and lipid-extracted material was most amplified in lipid-rich subarctic zooplankton in winter, δ13C difference being >5 units. Significant differences were also observed among zooplankton taxa, with copepods showing a greater lipid impact on δ13C than cladocerans. Published lipid correction models failed to produce satisfying fits to our data, and considerable variation was left even after recalibrating the model parameters. This was likely due to taxonomic differences in lipid effects on δ13C values. We therefore produced separate mass balance-based lipid correction models for cladocerans and also cyclopoid and calanoid copepods. We conclude that arithmetic lipid correction models perform well with zooplankton samples, but taxonomic differences need to be considered.
Patterns in apparent survival of Atlantic salmon (Salmo salar) parr in relation to variable ice conditions throughout winter
Authors: Linnansaari Tommi , Cunjak Richard A.
Published: November 2010

Apparent within-site survival of Atlantic salmon ( Salmo salar ) parr, individually tagged with passive integrated transponders, was not constant throughout the winter period in a 3-year study (2003–2006) in Catamaran Brook, New Brunswick, Canada. Highest decline in apparent survival (19.4%–33.3% of the study population) occurred prior to any ice formation and coincided with early winter acclimatization period (dynamic temperature and discharge regime). Stream discharge and parr maturity were identified to be relevant factors explaining emigration prior to ice formation. Apparent survival was improved during the period affected by subsurface ice and considerably better when surface ice was prevailing, with a decline in population size between 0% and 15.4%. Overall, observed within-site winter mortality was low (4.4%), and the majority of the loss of tagged salmon parr occurred because of emigration. On average, the within-site population of tagged salmon parr declined by 31.7% over the whole winter (November–April). Our data suggest that anthropogenic impacts, like climate change or river regulation, are likely to affect the apparent survival rate and distribution of juvenile Atlantic salmon because of their effects on natural ice regime in streams.
Analysis of variables associated with the Ichthyophonus hoferi epizootics in Norwegian spring spawning herring, 1992–2008
Authors: Kramer-Schadt Stephanie , Holst Jens Christian , Skagen Dankert
Published: November 2010

We present a long-term study of epizootics in a migratory fish species that shows major advancements in our understanding of marine disease ecology. On the individual macroscopic level, Ichthyophonus hoferi infections in herring significantly reduced body condition (p < 0.01) and reproductive capacity (gonad weight, p < 0.001). Infection prevalence increased with age (p < 0.001, R adj2  = 0.71). Prevalence in the catches strongly depended on target school size and was thus higher in trawl catches. We found strong seasonality in infection prevalence within years, with peaks in summer and winter. Summer peaks spatially formed an “infectious belt” off the west coast of Norway, consisting of infected fish unable to follow the migration routes to the feeding grounds. Prevalence varied also between years (p ≤ 0.001). Since 1992, it had declined from stock prevalence levels of 10%, down to almost extinction, with another major peak in 1999. The annual peaks could best be associated with strong year classes (Pearson’s r = 0.56), a good overall body condition (r = 0.86), and plastic wintering behaviour.
The response of zooplankton in a whole-lake experiment on the effects of a cage aquaculture operation for rainbow trout (Oncorhynchus mykiss)
Authors: Paterson Michael J. , Podemski Cheryl L. , Findlay Wilhelmina J. , Findlay David L. , Salki Alex G.
Published: November 2010

There is hope that increased development of aquaculture will help meet future global needs for protein. The growth of the freshwater aquaculture industry in Canada, however, has been hampered by insufficient information on environmental impacts. We examined the effects of an experimental cage aquaculture operation for rainbow trout ( Oncorhynchus mykiss ) on planktonic Crustacea and rotifers using 6 years of precage and 7 years of postcage data. Following the initiation of aquaculture, total crustacean and rotifer biomass, egg production, and depth distributions did not change significantly when compared with data from three nearby unimpacted lakes. We found statistically detectable increases in densities of Bosmina  cf.  longirostris and Diacyclops thomasi and an overall change in crustacean zooplankton community structure using correspondence analysis. The response of zooplankton was less than we expected because comparatively large changes were observed in phytoplankton biomass, hypolimnetic O2, and densities of invertebrate ( Mysis diluviana ) and fish predators. Our study emphasizes the need to monitor multiple variables when assessing the ecosystem impacts of potential stressors such as aquaculture.
Effects of wildland fire smoke on a tree-roosting bat: integrating a plume model, field measurements, and mammalian dose–response relationships
Authors: Dickinson M. B. , Norris J. C. , Bova A. S. , Kremens R. L. , Young V. , Lacki M. J.
Published: November 2010

Faunal injury and mortality in wildland fires is a concern for wildlife and fire management although little work has been done on the mechanisms by which exposures cause their effects. In this paper, we use an integral plume model, field measurements, and models of carbon monoxide and heat effects to explore risk to tree-roosting bats during prescribed fires in mixed-oak forests of southeastern Ohio and eastern Kentucky. Tree-roosting bats are of interest primarily because of the need to mitigate risks for the endangered Indiana bat ( Myotis sodalis ), our focal species. Blood carboxyhemoglobin concentrations predicted from carbon monoxide data supplemented by model output only approached critical levels just above flames in the most intense fires. By contrast, an ear-heating model driven by plume model output suggested that injury to the bat’s thermally thin ears would occur up to heights similar to those of foliage necrosis, an effect for which predictive relationships exist. Risks of heat injury increase with fireline intensity and decrease with both roost height and ambient wind. Although more information is needed on bat arousal from torpor and behavior during fires, strategies for reducing the risk of heat injury emerge from consideration of the underlying causal processes.
GLOBAL DYNAMICS OF THE LORENZ SYSTEM WITH INVARIANT ALGEBRAIC SURFACES
Authors: LLIBRE JAUME , MESSIAS MARCELO , DA SILVA PAULO RICARDO
Published: November 2010

In this paper by using the Poincaré compactification of ℝ3 we describe the global dynamics of the Lorenz system [Formula: see text] having some invariant algebraic surfaces. Of course (x, y, z) ∈ ℝ3 are the state variables and (s, r, b) ∈ ℝ3 are the parameters. For six sets of the parameter values, the Lorenz system has invariant algebraic surfaces. For these six sets, we provide the global phase portrait of the system in the Poincaré ball (i.e. in the compactification of ℝ3 with the sphere 𝕊2 of the infinity).
ON NONLINEAR ELLIPTIC BELLMAN SYSTEMS FOR A CLASS OF STOCHASTIC DIFFERENTIAL GAMES IN ARBITRARY DIMENSION
Authors: BULÍČEK MIROSLAV , FREHSE JENS
Published: November 2010

We consider nonlinear elliptic Bellman systems which arise in the theory of stochastic differential games. The right-hand sides of the equations (which are called Hamiltonians) may have quadratic growth with respect to the gradient of the unknowns. Under certain assumptions on the Hamiltonians, that are satisfied for many types of stochastic games, we establish the existence of a regular solution. This partially generalizes recent works of Bensoussan, Frehse and Vogelgesang from two-dimensional setting onto arbitrary dimension. The main novelty of the paper consists of introducing a new (semi-continuity) method for obtaining the continuity of the solution and the corresponding estimates.
CHARGE AND MASS CHANGING CROSS-SECTIONS OF 158A GeV Pb PROJECTILES ON Al, Cu, Bi, AND Pb TARGETS: FRAGMENTATION PROCESSES
Authors: RANA MUKHTAR AHMED , MANZOOR SHAHID , SHER GUL
Published: November 2010

We report here on total and partial charge changing cross-sections of 158A GeV lead projectiles on Al , Cu , Pb and Bi stationary targets using CR-39 detectors. Present results are compared with relevant published results. Deep discussion of nuclear fragmentation processes is provided. Stacks of CR-39 Track Detectors with above-mentioned targets were exposed to 158 A GeV 207 Pb projectiles at the CERN-SPS beam facility at normal incidence with a fluence of about 1500 ions/cm 2. Lengths of etched cones on one face of the CR-39 detectors before and after the target were measured for each stack. These measurements were used for determination of total and partial charge changing cross-sections of 158 A GeV Pb 82+ projectiles on these targets in the charge region 63 < Z < 82. The charge resolution (σZ) achieved in the present experiment is ~0.18e. Mass changing cross-sections are derived from the measured charge changing cross-sections using hyper-geometric relationship. A new method is proposed for separate measurements of electromagnetic and nuclear parts of fragmentation cross-sections using ion channeling and blocking conditions of projectiles in crystalline targets.
THE DEPENDENCE OF THE NUCLEON MASS ON THE PION MASS IN THE EXTENDED QUARK SIGMA MODEL
Authors: ABU-SHADY M.
Published: November 2010

The dependence of the nucleon mass on the pion mass is studied in the framework of the extended quark sigma model. We apply the modified quark sigma model to analyze the pion–nucleon sigma term. Analytic expressions are derived using the Feynman–Hellman theorem. The field equations are solved in the mean-field approximation. The results are compared with the CP-PACS group and the cloudy bag model. The results indicate that the extended linear sigma model provides good agreement compared to other models in the mean-field approximation.