bluuebunny/crossref_metadata_2025 huggingface dataset:
New Voters for Redundant Systems
Authors: Broen R. B.
Published: November 2010

This paper describes a class of redundant voters which compute and provide a “correct” output signal given a set of redundant input signals. The output is determined as a continuous smooth function of the redundant inputs using a weighted “average.” This type of voter tends to minimize switching transients since the isolation of faulty signals is achieved through a continuous numerical weighting. Equalization schemes which are normally required in voter designs to inhibit adverse transients during a channel failure are negated by this method. This function approach to designing a voter and fault isolation system provides for direct calculation of the characteristics of the output signal, given known characteristics of the inputs. Using this proposed method, a voter can be designed to provide a weighted average of the remaining good signals of a redundant system in the presence of one or more failed signal channels. Computed examples of voter output for assumed values of voter input signals are given for one representative candidate voter when used in configurations for both triply redundant and quadruply redundant systems.
Vector Bond Graphs Applied to One-Dimensional Distributed Systems
Authors: Bonderson L. S.
Published: November 2010

Vector bond graph notation and conventions are presented which simplify the task of representing the multiple power bonds, transformations and junction structures of multiport systems. These ideas are shown to be particularly convenient in the reticulation of represntative microelements for a class of one-dimensional multipower distributed systems. The microelements are an aid in understanding the dynamics of distributed systems and may be used to construct approximate lumped models.
State Estimation and Parameter Identification of Freely Spinning Flexible Spacecraft
Authors: Johnson D. A.
Published: November 2010

This paper studies the attitude estimation of a flexible spacecraft using the noise-corrupted measurements provided by sensors. The flexibility of the system is expressed in terms of internal deformation modes, and only a limited number of the latter are kept in view of simplifying the model. The estimation method is based on the Extended Kalman Filter algorithm, using an augmented state vector which includes the unknown parameters of the system. The filter thus provides an estimation of these parameters along with that of the original state-variables of the system. The method is implemented using a simulated model, thereby permitting an appraisal of the results, and reference is made to results obtained for a practical case where a somewhat different approach was taken as regards the way in which the flexibility is expressed.
A Pneumatic On-Off Vehicle Suspension System
Authors: Klinger D. L. , Calzado A. J.
Published: November 2010

An active, nonlinear, pneumatic suspension applicable to passenger railcars is described. Standard on-off valves modulate pressure differences between dual opposing airbags to attenuate vibration and create guidance forces. Improved vibration isolation over that of conventional passive suspensions is achieved at low power levels. Guidance forces are provided with small suspension travel using short bursts of compressed air taken from vehicle supply reservoirs. Acceleration, relative displacement, and pressure transducers provide the control signals required for stabilization, feedforward guidance commands, and disturbance attenuation. Simulation results indicate that performance comparable to hydraulic servosystems can be attained with substantially reduced system complexity and power requirements.
Process Control Experience and a Self-Tuning Method for a Discrete-Time, Finite Time Settling Controller/Observer
Authors: Auslander D. M. , Tomizuka M. , Takahashi Y.
Published: November 2010

A self-tuning method is described for a simple discrete-time control algorithm presented in a previous paper. With self-tuning, the algorithm is a candidate for a new class of single-loop controllers that would be considerably more convenient to use than the present analog PID controllers. Experimental results are presented indicating the applicability of the tuning and control algorithms to typical, nonideal processes.
A Note on the Early Development of Control Theory
Authors: Bennett S.
Published: November 2010

The importance of the work of Huygens and Hooke on the use of the conical pendulum to the development of control theory and practice is discussed. It is argued that their work had little influence on the development of the concept of feedback and of control theory.
Transient Response of Fluid Lines by Frequency Response Conversion
Authors: Katz S.
Published: November 2010

A method of frequency response conversion to transient response is applied to terminated fluid lines. The method can be used to solve transmission line problems with various input waveforms and terminations. Some typical results for circular lines are presented in non-dimensional terms. The results show that the transient response is a function of a characteristic number which depends on the fluid properties and the geometry of the line.
Metal Flow Through Conical Converging Dies—A Lower Upper Bound Approach Using Generalized Boundaries of the Plastic Zone
Authors: Zimerman Zeev , Avitzur Betzalel
Published: November 2010

The boundaries of the plastic zone in radial flow through conical converging dies are analyzed. The assumed boundaries are generalized, so that their shape and location are functions of the geometry of the process. An upper bound approach to the energy consumed is calculated. The energy is minimized with respect to the shape of the boundaries and that shape that yields minimum energy is found as a function of the reduction in area, the die semicone angle, and the friction between the die and material. The energy calculated with generalized boundaries was found to be lower than the energy calculated for spherical boundaries, and thus the assumptions in the present work yield a better upper bound.
Design of a Shuttle Accelerometer
Authors: Barclay W. J. , Grady P. L.
Published: November 2010

The problem of measuring the acceleration of a shuttle throughout its cycle of movement in a loom is discussed, and previous attempts to solve this problem are reviewed. A system is described that eliminates the inaccuracies and operating difficulties of other schemes. This method consists of placing an FM radio transmitter-transducer in the shuttle to transmit data to a remote receiver. The heart of this system is a flexible diaphragm, capacitance-type acceleration transducer used to modulate the frequency of an oscillator. Major emphasis is placed on the mechanical design of the acceleration transducer and the unique frequency response achieved by this design. A description of the verification of the design equations and principles by the construction and testing of a prototype model is included.
Effect of Loading Sequence on Notch Strength of Warm Prestressed Alloy Steel
Authors: Andrews W. R.
Published: November 2010

An experimental study of the effects of warm prestressing on the fracture strength of notched and fatigue-cracked bend bars of a Ni-Cr-Mo, low-alloy forging-grade steel was conducted. The steel was tested in four heat treatment conditions simulating four thickness fractions of a 23-1/2-in-thick forging. Three load-temperature paths were investigated: (1) preload-cool-fracture, (2) preload-cool-unload-fracture, (3) preload-unload-cool-fracture. The fracture strengths of the prestressed bars were compared with the fracture strengths of unprestressed bars. The benefits of prestressing for each load-temperature path decreased in the order listed, although prestressing was always beneficial. The benefits also decreased with decreasing fracture-test temperature relative to the 50-percent FATT.
Kinematic Synthesis of a Geared Five-Bar Function Generator
Authors: Erdman Arthur G. , Sandor George N.
Published: November 2010

A general closed form method of planar kinematic synthesis, using complex numbers to represent link vectors, is applied to the synthesis of a geared five-bar linkage for function generation. Equations are derived and a computer program is developed to yield several solutions. Angular displacements of the input, a cycloidal crank, and the output, a simple follower, are used as linear analogs of the independent and the dependent variables, respectively. A method is demonstrated for six precision conditions (three first, three second-order precision conditions). Numerical examples are included, and the structural error of these geared five-bars are compared to that of optimized four-bar linkages generating the same functions.
The Intersections of Solids Shown by Electronic Analog for Mechanism Simulation
Authors: Torfason L. E. , Crossley F. R. E.
Published: November 2010

The motion of certain spatial mechanisms with up to five links and containing at least one ball-and-socket joint can be visualized and analyzed by considering the intersections of three-dimensional surfaces generated by the mechanism. In this paper these solids and their intersections are represented by electronic analog computer, which can fully simulate in this way the motion capabilities of each link of the mechanism, and plot their relative displacements.
Six-Bar Cognates of Watt’s Form
Authors: Dijksman E. A.
Published: November 2010

The paper describes the equivalent of Roberts’ law for Watt-1 mechanisms. It is shown that two floating links of the mechanism may be in turn generated by more than one mechanism of this type. Another investigation reveals that the Watt-1 six-bar (coupler-) curve of degree 14 will be produced by an infinite number of cognates of the same form.
Inertia Force Analysis of Spatial Mechanisms
Authors: Yang An Tzu
Published: November 2010

A dual dynamic equation, based on dual vectors and screw calculus, is formulated here to provide a concise analytical tool for the study of the dynamics of rigid members in any complex mechanical system. In this paper the equation is applied to inertia force analysis of an RCCC mechanism of general proportions; bearing reactions and inertia torque are obtained in closed form dual-number expressions. Such analytical expressions are more susceptible for geometric interpretation and well adapted for digital computation.
Link Length Bounds on the Four-Bar Chain
Authors: Eschenbach P. W. , Tesar D.
Published: November 2010

The four-link kinematic chain is studied in an effort to establish a bounded region to limit the chain link lengths based upon transmission angle inequality constraints. The resulting constraint limitations are displayed graphically with the chain and their algebraic curve properties are delineated. Simple approximations of these complex loci are developed to facilitate practical application.
Multiply Separated Position Design of the Geared Five-Bar Function Generator
Authors: Oleksa S. A. , Tesar D.
Published: November 2010

The geared five-bar linkage is the foundation for a function generation problem meeting specifications for 5 multiply separated positions and containing 4 free design parameters. The four-bar linkage is shown to be a member of this class of mechanisms. Design examples of rarely treated functions are given with the quality of the generated approximation. Suggestions are made in terms of the 4 design parameters to assist the designer in obtaining good results.
Beyond Salary—Executive Compensation Past and Present
Authors: Dunaway Frank R.
Published: November 2010

One obvious indication that managers are interested in this subject is the number of annual surveys and current articles in business and professional publications. This interest has been recognized mainly in the period since World War II, when executive mobility really began in earnest. Some of the writings on personnel management give clues to compensation practice at earlier dates, but the need to know the “going rate” for an executive in order to lure him away (or keep him) spurred detailed surveys of compensation and systematic review of practices. Tax policies, governmental regulations, and pressures from organized labor’s demands all have had an effect. Over the last two decades, tax-conscious compensation practices have become the rule for top executives. These will be just as imporant to the middle managers and professionals as their level of compensation is boosted by inflation and wage increases granted to production employees. New tools and techniques are evolving to make compensation more than just a salary to be divided between the manager and the tax collector. This paper reviews the evolution of executive compensation practices since the turn of the century, describes many of the practices in current use, and indicates which of these practices will be more important in the near future.
Placing the Management of Defense and Space Programs in Perspective
Authors: Acker David D.
Published: November 2010

The author assesses the management of defense and space programs. He describes the contractual environment leading to development of the present-day management systems and gives attention to (a) management system criteria, (b) the nature of program management, (c) organizational structures for managing programs, and (d) problems and benefits attributable to management approaches used.
The Static and Dynamic Behavior of Warren Type Machine Tool Structural Elements
Authors: Thornley R. H. , Howes P. S.
Published: November 2010

One of the basic features of many machine structures is the Warren type beam, and an understanding of its static and dynamic characteristics is important to the designer. It is the subject of this paper, therefore, to compare the static and dynamic torsional and bending characteristics of some Warren type beams with a range of configuration characteristics.
Spiral Power Springs. Part 2—Design
Authors: Queener C. A. , Wood G. E.
Published: November 2010

The theoretical model developed in a preceding companion paper for predicting the torque-turn behavior of a spiral power spring is extended in an effort to improve the practical applicability. A theoretical equation based on springback theory is developed for computing the shape factor in the logarithmic spiral and an empirical equation for calculating the magnitude of frictional hysteresis is obtained. The extended model is tested with two springs and the experimental and calculated results are in good accord. The computation procedure involved in practical application of the extended model for spring design is discussed.
Reduction of Alternating Stress Range Around Holes in Flat Plates by Use of Inserts
Authors: Koplik B. , Klassen D. D.
Published: November 2010

Airy stress functions are established herein for the solution of hollow annular interfering inserts in thin flat plates which extend to infinity. The equations presented are solved for the case of a non-circumferential-slip insert to plate interface in a uniaxial stress field. The solution assumes plane stress and yields the stress and displacement fields for both plate and insert. The interface friction coefficient necessary to enforce the nonslip condition is determined as a function of initial interference. The analysis is extended to the case of a biaxial stress field through the use of superposition. The results indicate that inserts can be used to significantly reduce the maximum alternating stress range induced by plate load fluctuations. Curves are presented which may be easily applied to the design of inserts for the most effective reduction of alternating stress ranges around holes that could otherwise be a potential cause of failure due to low-cycle fatigue.
An Improved Finite Difference Method Applied to Thin Shells
Authors: Nelson N. , Chang A.
Published: November 2010

New methods of deriving more accurate difference equations are given. These are used to compute the stresses in thin shells. The governing shell equations are derived making the Donnell assumptions, so that unknowns are expressed in changes of curvatures and normal forces. These equations are then solved using improved finite difference formulas in which terms of higher order, compared to ordinary finite difference formulas, are taken into account. Several examples are given showing results comparable to other methods but using far fewer unknowns.
Burst-Strength Analysis of Finite-Length, Specially Orthotropic Cylinders With Different End Closures
Authors: Mehta K. N. , Bert C. W.
Published: November 2010

An analysis is presented for predicting burst strengths of specially orthotropic, thin-walled cylinders of finite length with different end closures, including (a) rigid ends, (b) hemispherical domes, and (c) a practical case of torispherical domes. Hill’s theory of orthotropic plasticity is used, for materials possessing either power-law or linear strain-hardening characteristic. Numerical results are presented for burst strength of pressure vessels made of a wide range of isotropic materials and having various geometric parameters. Fair agreement was obtained with available test results. The burst strengths of the specially orthotropic cylinders, with anisotropic strength parameter ν > 1, are predicted to be higher than the isotropic cylinders, which is in good agreement with experimental results for texture-hardening titanium-alloy vessels. A finite-length cylinder with rigid ends is the strongest and that with the hemispherical domes is the weakest. The results show that the torispherical domes fall between the rigid ends and the hemispherical domes, as would be expected. Also, the effect of finite length is small for length/diameter (l) > 3, and the effect of different end closures is negligible for l > 2. However, for l < 2, this effect cannot be neglected and becomes more pronounced as l decreases. The results are compared with the allowable values given in the ASME code for unfired pressure vessels for cylinders with hemispherical and with torispherical domes.
System Features of a Space Station Prototype Environmental Thermal Control and Life Support System
Authors: Willis N. C. , Samonski F. H. , Flugel Charles , Tremblay Paul
Published: November 2010

The preliminary design phase of the Space Station Prototype Environmental Thermal Control and Life Support System Program has been completed, and the detailed design of the system is underway. This paper describes some of the specific system features which have been incorporated to solve the problems of maintainability, to ensure reliability without excessive weight penalties, and to achieve fault detection and isolation through use of the capabilities of an onboard checkout system.
Flexural Vibration of Pretwisted Tapered Cantilever Blades
Authors: Rao J. S.
Published: November 2010

The Ritz-Galerkin process is used to solve the two coupled differential equations of motion of a pretwisted tapered cantilever blade vibrating in flexure. A five-term solution for each y and x deflection satisfying the boundary conditions is found to give accurate values for the first three modes of a uniform beam. Using these five-term solutions the first five coupled frequencies of pretwisted tapered cantilever blades are determined and compared with experimental values of some typical blades. The theoretical values of frequencies obtained are shown to be in favorable agreement with the experimental values.
Bellows Vibration With Internal Cryogenic Fluid Flows
Authors: Bass R. L. , Holster J. L.
Published: November 2010

The flow-induced vibrations of metal bellows with internal cryogenic flow are examined experimentally, and analytical techniques are given to predict vibration suppression characteristics. Heat transfer is shown to create local vaporization inside the convolutes which kills the primary source of bellows vibration, vortex shedding. The reduction in vibration amplitude is shown to be a function of the state properties of the liquid inside the bellows and the heat transfer rate into the liquid. External damping from frost, ice, or condensed liquid, which can appear on the bellows exterior, is discussed, and a method for estimating the reduction in vibration severity with external condensation is presented.
Dual Formulation of Variational Problems in Optimal Design
Authors: Rozvany G. I. N. , Adidam S. R.
Published: November 2010

Using a dual variational formulation, criteria for bounds on the minimum cost of rigid, perfectly plastic structures are derived. The results are used to point out a duality which exists between plastic analysis and plastic optimal design. The relations between the theories of Prager, Shield, Drucker, Heyman, and Michell are discussed. The proposed theory is applied to Tresca sandwich plates and fiber-reinforced plates. Identical upper and lower bounds are used to show that the “membrane solution” gives a minimum volume for a certain class of Tresca sandwich-plates.
Flow Near Self-Excited and Forced Vibrating Circular Cylinders
Authors: Griffin O. M.
Published: November 2010

Many studies of flow-bluff body interactions have been undertaken because of the practical need to know the fluid forces acting on a body immersed in a flowing stream. Experiments were performed to investigate the interaction process between the vibrating cylinder and the wake flow for free-stream Reynolds numbers between 550 and 900 in the irregular range. Two circular cylinders of equal diameter were used for experimentation—one was tuned to self-excite under the influence of lift forces and another was a rigid cylinder mounted in a shaker and forced to vibrate sinusoidally perpendicular to the mean flow direction under conditions that duplicated the Reynolds number, Strouhal number, motion amplitude, and relative frequency of the tuned cylinder. Experimental results for the two means of vibration and the mechanics of the wake formation are discussed in terms of the fluid dynamical parameters that influence the vibrations. One finds the wake formation process to be similar for both cylinders under the same conditions of flow, and the amplitude and distribution of near wake velocity fluctuations also to be the same. A phase shift of ninety deg is observed between eighty and one hundred and ten percent of the peak self-excited resonance condition, with the phase angle between the velocity fluctuation and cylinder motion signals being equal for both means of excitation. The critical relative frequency that corresponds to peak resonant conditions is less than unity. The independent parameters that govern the vibrations are not the same for the two means of excitation, and the bounds for the forced and self-excited motions are discussed in terms of the present results and those reported in the literature.
Energy Transmission in Piping Systems and Its Relation to Noise Control
Authors: White Pritchard H. , Sawley Roger J.
Published: November 2010

The piping in a process plant acts as a distribution and radiation system throughout the plant for many significant sources of noise and vibration such as compressors, pumps, valves and other flow discontinuities, and the like. The acoustical and vibrational energy carried by the piping can result in the establishment of undesirable acoustic fields. This paper looks at those factors which are important to the proper description of the energy interaction and propagation in the fluid-filled piping system and discusses their significance in achieving noise control.
The Hunting Behavior of Conventional Railway Trucks
Authors: Cooperrider N. K.
Published: November 2010

Railway vehicles under certain conditions experience sustained lateral oscillations during which the wheel flanges bang from one rail to the other. It has been found that this behavior, called hunting, only occurs above certain critical forward velocities. Approximations to these critical velocities have been found from a stability analysis of the linear equations of motion for many different railway vehicle models. Hunting is characterized by violent motions that impose large loads on the vehicle and track, and bring several important nonlinear effects into play. This paper reports results of an analysis of nonlinear equations of motion written for two models of a railway truck. The influence of the nonlinear effects on stability is determined and the character of the hunting motion is investigated. One model represents a truck whose axle bearings are rigidly held in the truck frame while the truck frame is connected through a suspension system to a reference that moves along the track with constant velocity. The more complex model includes additional suspension elements between the axle bearings and truck frame. The effects of flange contact, wheel slip and Coulomb friction are described by nonlinear expressions. These results show the significant influence of flange contact on stability, and illustrate the effects of vehicle and track parameters such as rail adhesion, forward velocity, and wheel load on the forces and power dissipation at the wheel-rail interface.
Areas of Contact and Pressure Distribution in Bolted Joints
Authors: Gould H. H. , Mikic B. B.
Published: November 2010

The pressure distribution in the contact zones and the radii at which flat and smooth axisymmetric, linear elastic plates will separate were computed for several thicknesses as a function of the configuration of the bolt load by the finite element method. The radii of separation were also measured by two experimental methods. One method employed autoradiographic techniques. The other method measured the polished area around the bolt hole of the plates caused by sliding under load in the contact zone. The computational and experimental results are in agreement and these yield smaller zones of contact than indicated by the literature. It is shown that the discrepancy is due to an assumption made in the previous analyses.
A Simplified Analytical Model of a Flash Evaporator Stage Having Channel Flow
Authors: Coogan C. H. , Brewster P. S.
Published: November 2010

Free surface flow with evaporation such as occurs in multi-stage sea water evaporators is modeled. Using one experimentally determined constant, i.e., the turbulent thermal conductivity of the liquid, permits use of the model in design. Flash down and non-equilibrium temperature differentials are related to the evaporation ratio.
Surge Waves in Stranded Springs
Authors: Nayfeh A. H. , Saric W. S. , Rodriguez D. A.
Published: November 2010

The basic theory of surge wave propagation in stranded wire, helical coil springs, including the effects of damping, has been presented. Solutions for spring forces, coil velocities and displacements, separation times of mass and spring, and the time to stop the impacting mass have been developed for the following cases: (a) mass impacting a preloaded spring, (b) spring launching a mass, (c) expansion of a preloaded spring, and (d) mass impacting an unloaded spring.
Clement-Desormes Measurements in Low-Pressure Superheated Steam
Authors: Potter J. H.
Published: November 2010

The specific heat ratio γ, was measured in low-pressure superheated steam, using a modified form of the free expansion experiment performed originally by Clement and Desormes. Values for γ are compared to those obtained from velocity of sound experiments, and to those calculated from the equations used in the ASME Steam Tables of 1967.
Analysis and Design of a Drill Grinder and Evaluation of Grinding Parameters
Authors: Fujii S. , DeVries M. F. , Wu S. M.
Published: November 2010

A prototype drill grinder was designed and built based on a computer aided drill point geometry analysis. The new grinder controls all essential drill point grinding parameters. The new grinder was evaluated by grinding drills, measuring their point geometry parameters, and comparing these measurements with their expected values. The effects of five parameters, consisting of three grinding and two cutting condition parameters, on the drill thrust and torque are determined by an experiment using a two-level factorial design.
A Rational Approach for Designing Gray Iron Components
Authors: Jhansale H. R. , Green R. , Topper T. H.
Published: November 2010

Three suggested phases of improvement in the design methods for gray iron components are: (a) design based on accurate strength and deformation analyses, instead of the currently used elastic formulas; (b) an ultimate strength instead of working stress approach to ensure consistent strength designs; and (c) factors of safety based on probabilistic methods to help eliminate bias based on the behavior of the material. An initial contribution covering these three aspects is presented.
A Theoretical Analysis of Temperature Distributions in the High Speed Forging of Hot Steel
Authors: The J. H. L. , Scrutton R. F.
Published: November 2010

The power and forces required to fill a corner cavity in closed-die forging depend on the amount of transient thermal conduction from the heated billet into the cold die. The amount of this conduction is calculated numerically for a steel billet and a steel die, by neglecting the flow of heat in the direction parallel to the movement of metal. The theory takes account of variations in the flow stress consequent on temperature change within the bulk of the plastic material and in the plastic boundary layer near the interface.
Elasto-Plastic Analysis of Constrained Disk Burst Tests
Authors: Riccardella P. C.
Published: November 2010

The PVRC Subcommittee on Effective Utilization of Yield Strength has conducted an extensive series of pressurized burst tests on constrained disk specimens of seven steels. Elasto-plastic analyses have been performed for nine of these tests and the results are presented in this report. Good agreement between the analytical and experimental results all the way to failure pressure is illustrated by a comparison of centerline deflections. Interpretation of the analytical data indicates that both edge type and centerline type of failures are correlated reasonably well by the conventional reduction in area from a uniaxial tensile test once triaxiality is accounted for.
Bin Loads—Part 4: Funnel-Flow Bins
Authors: Jenike A. W. , Johanson J. R. , Carson J. W.
Published: November 2010

This is one of a series of papers by the authors on the loads exerted by bulk solids on the walls of containing vessels. In this paper, design formulas and charts are presented for mass-flow bins.
Flow Patterns and Wall Stresses in a Mass-Flow Bunker
Authors: Blair-Fish P. M. , Bransby P. L.
Published: November 2010

Observations are reported of the shear and normal stresses on the walls of a small mass flow bunker and of the variations of density in the flowing material. Changes in wall stresses which occur as the material discharges are correlated with the formation and reformation of zones of intense deformation within the bunker.
A Means of Increasing Drill Collar Connection Life
Authors: Weiner P. D. , True M. E.
Published: November 2010

Drill collar connection failures have increased as oil and gas wells are drilled to greater depths requiring the use of smaller collars. The high cost resulting from these failures prompted a project to develop means of reducing the drill collar connection failures. This paper discusses laboratory investigations and the results of a development program conducted by Texas A&M University Research Foundation to determine the magnitude of drill collar connection stresses and the selection of a collar modification to reduce connection stresses. Full-scale laboratory fatigue tests of drill collar connections and subsequent field service demonstrated that the use of exterior stress relief grooves on each side of the connection materially increased connection life before failure occurred. Field Service tests following fuel scale laboratory fatigue tests show increased drill collar connection life resulting from use of exterior stress-relief grooves.
Mesh Generation—A Survey
Authors: Buell W. R. , Bush B. A.
Published: November 2010

This report discusses pertinent schemes in finite element mesh generation. It is divided into two parts; node point generation and element generation. Node generation consists of automatically determining the coordinates of the finite element nodes. The basic node generation methods reviewed are straight line interpolation, sides and parts, electro-mechanical devices, simplified finite difference, the equipotential method and the natural coordinate system method. Element generation consists of automatically connecting the nodes to form elements. These methods are simple increments, sides and parts pseudo I-J transformation, fully surrounded point, and I-J transformation.
A Power Cycle to Eliminate Thermal Pollution
Authors: Potter J. H.
Published: November 2010

A cycle is proposed in which no condenser cooling water is required. Turbine back-pressure is kept to conventional levels by condensing the steam during the evaporation of a refrigerant. Heat is rejected from the refrigerating loop in air coolers. Application of this concept to an 826 MW fossil-fueled power station shows the anticipated increases in heat rate and capital cost.
Kinematic Synthesis of Adjustable Mechanisms—Part 1: Function Generation
Authors: McGovern Joseph F. , Sandor George N.
Published: November 2010

One of the major advantages of linkages over cams is the ease with which they can be adjusted to modify their output. Incorporating an adjustment into the design of a linkage makes it possible to make a selection from two, three, or more different outputs by simply making the adjustment. Adjustable mechanisms make it possible to use the same hardware for different input-output relationships. The adjustment considered in this paper is the changing of a fixed pivot location. This paper presents a method of synthesizing adjustable planar linkages for function generation with finitely separated precision points and higher order synthesis involving prescribed velocities, accelerations, and higher accelerations. The method of synthesis is analytical with closed form solutions and utilizes complex numbers. The method is programmed for automatic digital computation. The linkages considered are a four-bar, a geared five-bar, and a geared six-bar mechanism. Examples include adjustable mechanisms which have been successfully synthesized with the method developed here. Future extensions of the complex number method to include adjustment by changing the length of a link and by changing of the relative orientation of the gears in geared linkages are outlined.
Tensile Strength of Composite Materials—Part 2: Interpretation of Analysis
Authors: Avitzur B.
Published: November 2010

The upper bound equation derived in Part 1 is manipulated to obtain more detailed information about composite strength and deformation behavior. Several behavior transitions which occur are discussed and the transition from homogeneous to nonhomogeneous deformation is approximated. Finally, it is demonstrated that developed expressions can be utilized to estimate composite strength.
Fatigue and Fracture Toughness Properties of 9 Percent Nickel Steel at LNG Temperatures
Authors: Sarno D. A. , McCabe D. E. , Heberling T. G.
Published: November 2010

9 percent nickel steel has been evaluated for use in a semimembrane LNG containment design. Fatigue and fracture toughness properties of 1/4 in. thick base plate and weldments have been determined at cryogenic temperatures. Results of rotating beam fatigue, stress intensity (Kc) and fatigue crack growth rate (da/dN versus ΔK) studies are presented. Data predict that 9 percent nickel steel, fabricated with the gas metal arc and shielded metal arc welding processes, may be successfully applied as the primary tank material for this LNG design.
Relationship Between the Parameters of an Autoregressive Model and Grinding Wheel Constituents
Authors: Deutsch S. J. , Wu S. M.
Published: November 2010

Autoregressive models are developed for eight wheels differing in grit size, hardness, and structure. Using the parameters as responses of a factorially designed experiment, the relative contribution of the wheel constituents to the total wheel topography is related and quantified. Utilizing the effects observed, the individual and interactive roles of the wheel constituents are discussed. From the experimental observations a formation mechanism is suggested.
Optimum Design of an Orientation Control Device for Submersibles
Authors: Seireg A. , Baz A.
Published: November 2010

This study deals with the optimum design of an orientation mechanism capable of producing controlled orientation in the vertical plane for underwater submersibles. The location of an eccentric weight relative to the submersible’s center of buoyancy controls its equilibrium orientation angle. The mechanism can be utilized for controlling the position of scuba divers, underwater cameras and other devices requiring specific orientation in the marine environment.
A Class of Minimum Weight Shafts
Authors: Maday C. J.
Published: November 2010

Light weight shafts reduce bearing forces and allow the use of smaller bearings, seals, and supports. The Minimum Principle is used to set up the problem of determining the minimum weight shaft for a specified critical speed of given order. Specific examples include simply supported shafts and cantilevered shafts with and without a disk. The designs are obtained from the solution to a nonlinear multi-point boundary-value-problem. Minimum weight configurations represent a standard against which other designs, such as stepped shafts, can be compared.
On the Doubly Regenerative Stability of a Grinder
Authors: Thompson R. A.
Published: November 2010

Traditionally, grinder stability analyses have been based on Laplace Transform techniques. In this paper an alternative approach is developed which takes into account the wear and speed of both the wheel and workpiece. Starting with the steady-state response of a grinder, the damping c, for quasi-stability, is expressed in terms of the fundamental dynamic parameters of the grinder and cutting process. The requirements for speed independent or unconditional stability are found by maximizing the pression for c. They are valid for both surface and cylindrical grinding, and reduce to those derived by Hahn in the special case of a nonwearing wheel. The requirements for conditional stability are found. The importance of wheel dress and extraneous forces is emphasized, and it is shown that conditional stability is dependent on lobe precession rates. The effect of wheel speed on conditional stability is questioned.
The Effect of Geometrical Parameters of Hypoid and Spiroid Gears on Its Quality Characteristics
Authors: Litvin F. L. , Petrov K. M. , Ganshin V. A.
Published: November 2010

The orthogonal hypoid and spiroid gears are considered. The point of tangency of the pitch cones is presumed to be simultaneously the calculation contact point of the teeth surfaces. Analytical relationships for the geometrical parameters and important quality characteristics depending on the contact point, coordinates are given. These analytical relationships make it possible to vary independent geometrical parameters within permissible limits. In such a way a pair of pitch cones may be found with the best quality characteristics.
Comparison of Theories and Experimental Results for Surface Temperature of Spur Gear Teeth
Authors: Terauchi Yoshio , Mori Hidetaro
Published: November 2010

The surface temperature of gear teeth is one of the important factors for evaluating the scoring resistance of a gear. In a present paper, the comparison of numerically calculated value with experimentally measured value is reported. The calculation of surface temperature was performed with the following procedure. First, the dynamic loads applied to gear teeth were calculated in consideration of the variation of different factors, for instance transmission errors of test gears and total stiffness of gear teeth. Second, under the condition that there must be no temperature discontinuity over the contact zone of sliding surfaces, the temperature distribution over the contact area was calculated. On the other hand, the measurement of surface temperature was performed using the meshing gears themselves as a dynamic thermocouple. The results of numerical solution by means of a digital computer are in fairly good coincidence with the experimental results.
Prediction of Objective Passenger Comfort From Road Profile
Authors: Park W. H. , Wambold J. C. , Vashlishan R. G.
Published: November 2010

Objective comfort evaluation using the method of absorbed power requires the interface acceleration between the vehicle seat and the passenger. This acceleration can be obtained experimentally, or can be calculated from the road profile by determining the vehicle transfer function. A profilometer vehicle which simultaneously measured road profile and passenger/seat accelerations was used for data gathering. Absorbed power was calculated and distributed into amplitude and frequency bands, using random signal description technique called amplitude frequency distribution. Utilizing this format results in a matrix showing which amplitude and frequency bands contribute the greatest discomfort to the ride. The roughness effects of six roads were ranked in proper order by the passenger comfort prediction.
Penetration Rates and Stability of Motions of a Harmonically Forced Fore-Aft Vibrating Plow
Authors: Senator M.
Published: November 2010

A fore-aft vibrating plow with applied harmonic and bias forces, and with soil-blade interaction modeled by a constant tip resistance in uncut soil and zero skin friction is studied analytically. Necessary conditions are found which must be satisfied by transition crank angles if steady state motions with velocity period equal to an integer number of harmonic force periods are to exist. The infinitesimal stability of these motions is examined and the range of parameters over which stable and unstable motions exist is delineated. Average plowing speeds corresponding to these regular motions are computed and the variation of plowing speed with system parameters is found. These results are useful, both for estimating penetration rates of conceptual plows and for adjusting machine parameters to obtain optimum performance.
A New Random Data Description and Its Use in Transferring Road Roughness to Vehicle Response
Authors: Wambold J. C. , Park W. H. , Vashlishan R. G.
Published: November 2010

The initial portion of the paper discusses the more conventional method of obtaining a vehicle transfer function where phase and magnitude are determined by dividing the cross spectral density of the input/output by the power spectral density (PSD) of the input. The authors needed a more descriptive analysis (over PSD) and developed a new signal description called Amplitude Frequency Distribution (AFD); a discrete joint probability of amplitude and frequency with the advantage of retaining amplitude distribution as well as frequency distribution. A better understanding was obtained, and transfer matrix functions were developed using AFD.
Calculation of Forced Whirling and Stability of Centrifugal Pump Rotor Systems
Authors: Black H. F.
Published: November 2010

Although common problems with well established solutions are met in all rotor systems embodying hydrodynamic bearings, a number of factors peculiar to centrifugal pumps radically affect their vibrations response. Close internal clearances retaining pressure act as powerful hybrid bearings. In high performance pumps with vaned diffusers, large hydraulic forces are exerted on the rotor at part-load: these forces depend qualitatively and quantitatively on the ratio of flow to optimum flow. A calculation method taking all relevant factors into account is described. Some typical forced whirling response and stability results for a multistage rotor system are given. The application of calculations to remedial action in a service problem is described.
Effect of Hydrostatic Pressure on Corrosion-Fatigue at High Frequency
Authors: Jolliff J. V. , Thiruvengadam A.
Published: November 2010

An experimental investigation into the effect of hydrostatic pressure on corrosion-fatigue at a frequency of 20,000 cycles per sec is reported for a number of materials currently considered for use in the ocean environment. The high-frequency fatigue technique used for this study is based on the principle of producing longitudinal vibrations in a properly designed fatigue specimen at its resonant frequency. This, in turn, produces maximum uniaxial alternating strains at the specimen nodal point. The fatigue specimens are tested in a uniquely designed pressure chamber containing synthetic seawater under constant temperature. The investigation shows that the corrosion-fatigue life of some of the materials tested is significantly reduced when they are subjected to a hydrostatic pressure of 2000 psi as compared to that experienced at atmospheric pressure. It appears that the mechanism of the influence of hydrostatic pressure is primarily chemical in nature. This is evidenced by scanning electron microphotographs of specimens fatigued under hydrostatic pressure which reveal that the fracture surface is rougher and contains multiple crack zones, greater substructure secondary cracking, deeper rivering arrays, and innumerable crack branching. These features are not prevalent in specimens tested at atmospheric pressure.
Stresses in Cylindrical Tubes Subjected to a Pressure Band
Authors: Motosh N.
Published: November 2010

In this work, the stresses in stiffened thick tubes are calculated. The results obtained from the proposed theory are compared with experimental values of stresses measured at the outer surface of steel tubes.
Stress Relaxation of Tension-Compression Members Having Constant Elongations
Authors: Krauter Allan I.
Published: November 2010

This paper presents a generalization of a commonly used stress relaxation relationship. The generalization applies to tension or compression members which have constant elongations and which obey the Bσn creep law.
Elimination of Vibrations in an Ore Unloading Bin
Authors: Wei M. L. , Johanson J. R.
Published: November 2010

Problems of undesirable vibrations in an ore unloading structure are described. Earlier unsuccessful attempts to eliminate vibrations by changing allegedly exciting frequencies mechanically and by increasing natural frequencies structurally are cited. Scientific evaluations of granular material flow patterns in the bin are presented, which identify possible causes of and methods to alleviate the vibrations. Finally, the corrective measures in flow control taken to eliminate vibrations are illustrated.
An Analysis of Coupled Extensional-Torsional Oscillations in Wire Rope
Authors: Samras R. K. , Skop R. A. , Milburn D. A.
Published: November 2010

Coupled extensional-torsional behavior of wire rope is considered. Equations of motion for a straight rope section loaded simultaneously in tension and torque are derived, and constitutive equations relating these loadings to extensional and rotational deformations of the rope are postulated. A pair of wave equations describing coupled extensional-torsional oscillations of a wire rope is then obtained. The solution to these equations shows that, in general, two types of waves can propagate through a straight rope section. Four commonly occurring boundary value problems for a rope stretched between the ocean floor and ocean surface are considered. Each problem has a different combination of end restraints—either clamped or swiveled. A sinusoidal forcing function representing wave action is applied to the upper end of the rope. The critical driving frequencies as a function of rope length are calculated for each boundary value problem. These critical frequencies are compared with those predicted by considering extensional oscillations only. The comparison shows that significant differences exist bewteen the predicted resonant frequencies and demonstrates the importance of examining the torsional behavior of wire rope.