bluuebunny/crossref_metadata_2025 huggingface dataset:
An Experimental Study of the Fluid Dynamics of Multiple Noncritical Stenoses
Authors: Talukder N. , Karayannacos P. E. , Nerem R. M. , Vasko J. S.
Published: November 2010

The effects of the number of stenoses and the distance between consecutive stenoses on the total pressure drop across a series of noncritical stenoses with 50 percent area reduction were determined experimentally. The mean flow rate was varied to correspond to a Reynolds number range of 30–280 and both in vitro and in vivo measurements of the pressure drop were carried out. Flow visualization studies also were performed. The pressure drop across a series of stenoses was found to increase linearly with the number of stenoses. Comparable results were obtained from the steady and pulsatile flow in vitro experiments as well as from the in vivo experiments. The results indicate that the total effect of a series of noncritical stenoses is approximately equal to the sum of their individual effects and that the combined effect of a series of noncritical stenoses thus can be critical.
Fluid Stresses in the Vicinity of Disk, Ball, and Tilting Disk Prosthetic Heart Valves From In-Vitro Measurements
Authors: Figliola R. S. , Mueller T. J.
Published: November 2010

Experiments were conducted in a steady flow test apparatus with an axisymmetric aortic shaped test chamber using hot-wire anemometry to obtain local momentum transfer and turbulence data in the vicinity of the model disk, Kay-Shiley disk, Starr-Edwards ball and Bjork-Shiley tilting disk prosthetic heart valve configurations. These data for Reynolds numbers of 2000, 4000, and 6000 were used to locate regions of high stress where erythrocytes may be lysed or severely strained. Nondimensionalized velocity profiles downstream of the valves indicated a similarity of behavior for all Reynolds numbers at an axial location. Velocity gradients of magnitudes potentially damaging to erythrocytes were found. These gradients were largest for disk-type occluders. Large regions of separated flow were found to occur behind the valve sewing ring, distal to the valve occluder, and along the test chamber wall distal to the valve for all valves tested. Relatively high turbulence was found to exist distal to all valves tested. Turbulent stresses of magnitudes potentially hemolytic were measured.
The Elasticity of Sclera and Choroid of the Human Eye, and Its Implications on Scleral Rigidity and Accommodation
Authors: Graebel W. P. , van Alphen G. W. H. M.
Published: November 2010

Uniaxial measurement of stress as a function of strain were performed on strips of sclera and choroid from human eyes. The scleral strips indicated an exponential stress-strain behavior, while the choroidal strips exhibited a power law behavior. Linear elastic models are used to deduce the physiologic range of interest and the relation of the stress-strain behavior to scleral rigidity. Stress changes in the choroid during accommodation are discussed.
The Prediction of Passenger Riding Comfort From Acceleration Data
Authors: Smith C. C. , McGehee D. Y. , Healey A. J.
Published: November 2010

Various methods for evaluating ride quality in automobiles are investigated by means of a field study involving two different automobiles, seventy-eight different passengers, and eighteen different raodway sections. Passenger rating panels were used to obtain subjective evaluation of the various rides, and measured vibration spectra were examined on the basis of various frequency weighting techniques to determine their ability to predict the subjective ratings. Included in the evaluation criteria considered are weighting functions derived from the ISO (International Standards Organization) Standard, the UTACV (Urban Tracked Air Cushion Vehicle) Specification, and the Absorbed Power method of Lee and Pradko. Excellent correlation was found to exist between the subjective ride ratings and simple root mean square acceleration measurements at either the vehicle floorboard or the passenger/seat interface. Equations are presented to predict the subjective ride rating from measured vibration spectra.
The Generation of Continuous Gradient Functions
Authors: Fuller M. A. , Grimble M. J.
Published: November 2010

Impulses in gradient functions are shown to arise when the systems contain impulses in their impulse response. Methods are described for obtaining search directions which are continuous functions and which can be used in gradient minimization algorithms.
Optimal Allocation of Actuators for Distributed-Parameter Systems
Authors: Martin Jean-Claude E.
Published: November 2010

We consider a distributed parameter system of parabolic type and N controllers which can be positioned at p(p > N) different points on the system’s spatial domain. Using relaxed control theory, the best location of the controllers is determined, at ecah time t, in order to get the minimum value of a given quadratic cost functional.
A Survey of Rail Vehicle Testing for Validation of Theoretical Dynamic Analyses
Authors: Cooperrider N. K. , Law E. H.
Published: November 2010

This paper discusses experience in rail vehicle testing for validation of theoretical rail vehicle dynamic analyses. Laboratory and field testing are covered including shaker, roller rig, freight car rock and roll, vehicle stability, vehicle forced response, and rail vehicle curving tests. The specific vehicle and roadbed characterization requirements for validation tests are described. Some of the shortcomings of previous testing efforts are outlined and recommendations for future validation testing made.
Optimal Control Concepts for the Characterization and Design of Highway Vehicle-Trailer Systems
Authors: Townsend M. A. , Shapiro A. B. , Ho K. T. A.
Published: November 2010

Recent years have seen enormous increases in the use of vehicle-trailer systems for commercial transport as well as personal/recreational use. Indeed, entire new industries and concepts have developed, along with questions pertaining to safety, legislation, etc. and the design of such systems. One problem in evaluating the design and operating-range performance of such systems is the identification of one or a few pertinent criteria for comparison and suitable characterizations of the relative stability and performance of these systems. In this paper, design concepts are developed from optimal control theory to provide such criteria and are then applied to one of the more innovative and potentially competitive concepts in commercial trucking: the multiple-trailer highway vehicle train. The definition of relevant models is given and criteria are then developed. Their applicability is demonstrated by the posing of optimal unloading schedules to improve dynamic performance, the sensitivity of such designs to changes in system parameters, and the design synthesis of couplers between the system components. The comparison of these systems with equivalent (in terms of load capacity) single-trailer systems is also indicated. The problem of discrete compartmented trailers is also addressed; this case can be viewed as a multi-stage dynamic programming problem. Obviously, the modeling is safer, less costly and time consuming than present prototype developmental procedures. The criteria developed are extremely general and appear to provide a basis for developing a systematic approach to the design of such systems for safety and dynamical behavior as well as for capacity. As it turns out, alternate and unexpected schedules and different designs can yield substantially improved behavior—and the results are not intuitively obvious.
Parameter Optimization for Two-Player Zero-Sum Differential Games
Authors: Dolezˇal J.
Published: November 2010

In addition to the classical formulation of a general two-player zero-sum differential game it is assumed that the minimizing player chooses the values of certain parameters to further decrease the pay-off functional at the expense of the maximizing player. To solve this problem in the best possible way for the minimizing player, a set of necessary optimality conditions is derived, which not only enable the determination of the saddle-point strategies for both participating players, but also the optimal parameters. Based on these conditions an iterative numerical algorithm of gradient type is suggested. As an illustration, several examples are solved applying the described algorithm.
The Wave Reflection Matrix in Beam Vibration Control
Authors: Van de Vegte J.
Published: November 2010

Vaughan [1] has considered the use of wave reflection concepts in the control of lateral vibrations of slender uniform beams. In this paper a different form of the wave reflection matrix is derived, which gives a clearer correlation between the values of its elements and the system response characteristics. In particular, the value of one element is shown to have a strongly dominating effect on the response.
Gas Flow Control Employing Temperature and Pressure Compensation
Authors: Goldstein Seth R. , Harvey Andrew C.
Published: November 2010

Two passive gas flow controllers are presented which provide compensation for variations in ambient temperature and supply pressure. One technique, which provides first-order error compensation, utilizes a choked orifice having its area linearily varied in proportion to a diaphragm deflection. Compensation is achieved by applying upstream pressure to one side of the diaphragm, and by applying a trapped gas pressure proportional to absolute temperature on the other side of the diaphragm. General design relationships are presented, and a prototype unit constructed to control a minute flow rate of high-pressure oxygen is described. A second flow control technique is presented which provides the required nonlinear temperature compensation for flow supplied through a constant-area choked orifice. This is achieved by utilizing a compliant volume of trapped gas to generate a pressure proportional to the square root of absolute temperature. This pressure is used to control the pressure upstream of the choked orifice, thus providing constant flow.
Personalized-Proctorial Instruction for Dynamic Systems and Control
Authors: Hoberock L. L.
Published: November 2010

A highly promising teaching technique using reinforcement learning theory and individually paced instruction is analyzed and shown to offer several advantages in conducting dynamic systems and control courses.
State of the Control Art and Practice in Japan: 1—General Survey
Authors: Oshima Y.
Published: November 2010

This set of articles is to introduce the state of control engineering in Japan. The series is divided into four parts: 1 General Survey; 2 Theory; 3 Components; and 4 Applications. Before entering detailed arguments, a brief general survey is presented.
Stability Bounds for Nonlinear Systems Designed Via Frequency Domain Stability Criteria
Authors: Garg D. P. , Rabins M. J.
Published: November 2010

Compensator design results are compared for the circle and Popov criteria, both of which are sufficiency conditions for absolute stability of nonlinear control systems. Analog simulation studies yielded higher compensator gains than either of the two criteria. Nevertheless, the analog results showed the same general trend as the circle and the Popov criteria results. The circle criterion was found to be more conservative than the Popov criterion in the numerical examples presented here.
An Analytical and Empirical Basis for the Design of Turbulence Amplifiers: Part I: Analysis and Experimental Confirmation
Authors: Bell A. C.
Published: November 2010

The design of turbulence amplifiers is given a rational basis by identifying the critical parameter groups necessary to completely specify the performance of a given element, deriving by analysis or experiment the relationships between these nondimensional parameter groups, and developing a rational procedure for obtaining a quantitative dimensioned set of operating characteristics from these relationships. Part I of this paper outlines the problem, identifies the required relations, and presents analyses confirmed by data. These analyses develop relationships for tube pressure-flow characteristics, jet attenuation, and recovered pressure. Part II presents empirical relationships specifying jet stability and control characteristics, and develops a design procedure with an example.
Hydraulic Fluidics
Authors: Kelley L. R. , Boothe W. A.
Published: November 2010

Fluidic technology is equally applicable to liquid and gaseous operation, yet the bulk of the literature to date is concerned with the latter. This paper describes some of the unique effects encountered in fluidic devices for hydraulic operation, and compares air operation to hydraulic oil operation in several critical respects including potential response, power consumption, and Reynolds number. Test data on oil operated hydraulic elements show a high dependency on Reynolds number in the lower pressure and temperature regions. Gain as a function of Reynolds number and aspect ratio is presented. An effective means for correlating data to a modified Reynolds number is shown. Dynamic performance test results are also shown, and agree quite well with predictions based on lumped parameter analysis. The use of operational oil elements in specific open and closed-loop circuits is also described.
A Study of Feedback Fluid Jet Oscillator With a Supersonic Power Jet: Part II: Analytical Study of Its Characteristics
Authors: McGeachy J. D. , Chow W. L.
Published: November 2010

The study of the flow phenomena occurring within a feedback fluidic jet oscillator (see reference [2]) was continued on the basis of the quasi-steady flow concept. Description and explanation of these phenomena throughout the oscillating cycle were possible in view of the reasonably good agreement between the analytical results and experimental data. The characteristic pressures within the system prior to switching can be correlated and predicted. For a particular oscillation geometry, the required primary pressure to start jet switching and oscillation can also be estimated. A simplified oscillator model has also been suggested to illustrate the general behavior of such a feedback oscillator.
Digital Simulation of the Chemical Control of Ventilation
Authors: Milhorn H. T. , Reynolds W. J.
Published: November 2010

Experimental human data, obtained for the development and evaluation of a digital computer model of the human respiratory system, are presented. The data are from two series of experiments. In the first series the transient responses of tidal volume, respiratory frequency, minute ventilation, alveolar Pco2 and alveolar Po2 were obtained for several inspired CO2 concentrations (3, 5, 6, and 7 percent). In the second series, transient responses of the same variables were obtained for steps of inspired O2 concentration from room air to several lower oxygen levels (9, 8, and 7 percent). An example of the use of the data for the development and evaluation of a model is indicated.
Design of Optimal Passive Beam Vibration Controls by Optimal Control Techniques
Authors: Van De Vegte J. , Hladun A. R.
Published: November 2010

Modern optimal control techniques are applied to design passive systems consisting of linear dampers, rotary dampers, or dynamic absorbers, to minimize transient vibrations of slender uniform beams. A number of control configurations are considered. The controller parameters as well as locations along the beam are optimized, and data are presented on the sensitivity of the optimal designs to parameters variations. The particular purpose is to show the advantages of the technique in adjusting the dynamics to satisfy various requirements.
A Simple Algorithm for Pole Assignment in a Multiple Input Linear Time Invariant Dynamic System
Authors: Chidambara M. R. , Broen R. B. , Zaborszky J.
Published: November 2010

This paper is concerned with the development of a simple algorithm for solving the problem of pole assignment in a multiple input linear time-invariant dynamic system, by means of state variable feedback. Unlike other existing methods which solve the same problem, the proposed algorithm does not require the transformation of the system equations to a special canonical form or the reduction of the multiple input system to an equivalent single input system. Analogously, the dual problem of constructing an asymptotic state estimator for a multiple output system is solved, with the solution enjoying analogous advantages.
On a Piezoelectric Flapper Type Servovalve Operated by a Pulse-Width-Modulated-Signal
Authors: Ikebe Y. , Nakada T.
Published: November 2010

As a first step to developing a servovalve with minimum moving parts, a new servovalve is devised in which a piezoelectric flapper (a quartz strip) is used instead of a conventional flapper actuated through a torque motor. A servovalve of this type is desirable from the viewpoint of fast response, however it has not been in common use because of the strong hysteresis of piezoelectric material. In order to linearize the nonlinear characteristics of the flapper, a pulse width modulated wave is used as the input signal to the flapper. The frequency characteristics of the pulse width modulator is theoretically analyzed in detail to establish the theoretical basis of the pulse width modulation control system. As well-known, this basis has been ambiguous so far. The experimental frequency responses show that the bandwidth of the servovalve using this new technique is comparable to that of conventional valves having the same power output in spite of its simple construction in comparison with conventional ones.
Least-Squares Estimator for Nonlinear Systems With Transport Delay
Authors: Koivo A. J. , Stoller R. L.
Published: November 2010

The problem of estimation of states in nonlinear dynamical systems containing time delays is formally studied. The plant is specified by a set of nonlinear differential-difference equations. Observations are a nonlinear function of current and/or delayed states. Both contain deterministic additive disturbances. The criterion used for the optimal estimates is the integral of the weighted squared error. Using the theory of the calculus of variations, equations are developed for the estimation. They are first expressed in the form of a split boundary value problem, which is then converted to an (approximate) initial value problem for online estimation. The result yields an estimation scheme in which filtered and smoothed estimates are computed in a sequential manner. The applicability of the procedure is demonstrated by estimating variables of a nonlinear model describing the behavior of a stirred tank reactor.
Automatization of Distillation Processes From the Laboratory to the Industrial Plant
Authors: Bornard C. , Badgerahanian L.
Published: November 2010

This paper describes the modalities and the main results of a long cycle of studies—over about 10 years—on computer control applied to distillation processes. These studies were carried out by the Automatic Control Laboratory at Grenoble, with the collaboration of various industrial companies (Naphtachimie, Mors-Te´le´mecanique Electrique, Rhoˆne-Progil, and Shell) and supported by a grant from the French Government. The main objective was to decrease the gap existing between available theory and the methods effectively applied in industry, thus leading the Laboratory to direct our studies towards industrial implementation. To fulfill this goal, it proved useful to employ an intermediate step: the development of the methods and algorithms by preliminary application on pilot scale plants built for this purpose in the Laboratory. Important feedback is provided after each practical application, since experimental results often suggest further studies on the methods used or new theoretical developments.
Automatic Control of Water Distribution
Authors: DeMoyer R. , Horwitz L. R.
Published: November 2010

While many modern water companies are equipped with data logging computers, there is no generally accepted methodology for utilizing the large quantities of accumulated data for the purpose of least cost control. The overall control concept presented, designed to take advantage of such data, includes system modeling, adaptive modeling, analysis of time varying demand, and optimal pump control.
Instrumentation and Computer Control in the Food Processing Industry
Authors: Dahlin E. B. , Bakke R. M.
Published: November 2010

Instrumentation and computer control are tools for improving productivity and reducing costs in food processing plants. Approximately one-seventh of the total sales volume of industry in the United States is devoted to food processing. The growth rate of food processing is more than three times the population growth rate. This dissimilarity in growth can be attributed to expanding food product lines and the expanding role of food in international trade. A profit squeeze has existed traditionally in the food processing industry. As a result, there is a constant surveillance for methods that result in the cost reductions needed to finance this industrial expansion. Instrumentation and computer control are proven cost reduction tools in the food industry. Despite the large number of different food products, some problems are common to many food processors. Therefore, a few select instrumentation and computer control techniques offer solutions to important problems common to many in different segments of the food processing industry. This paper describes some applications now being installed in food processing plants. Included are: • energy conservation computer control • food preparation and cooking computer control • food moisture, drying, and dehydration computer control. A case study in the economics of a vegetable drying plant is developed in this paper.
Stability of Cyclic Dynamical Systems
Authors: Dickerson J. R. , Erickson P.
Published: November 2010

The stability of a closed loop of vehicles which are controlled by identical functions of the state of neighboring vehicles is investigated. The paper is divided into two parts, formulation and stability results for cyclic dynamical systems and, application of these results to three example problems with comparison to exact results when possible.
Analytical Models for Certain Guideway Irregularities
Authors: Hullender D. A.
Published: November 2010

The design and construction of a guideway for ground transportation vehicles involve compromises between the desired smoothness and the necessary sacrifices in regard to expense and time to achieve it. The objective of this paper is to derive and analyze equations for guideway roughness spectra in order to obtain design and construction criteria understandable by contractors. Although there are many sources of guideway irregularities that should be considered in the final version of the design specifications, this paper concentrates on a design criterion for minimizing the degree of necessary natural terrain alteration by means of filling or leveling. In addition, a model is derived that defines the significance of random alignment errors caused by either surveying inaccuracies or foundation settlement. The results are applicable to either at-grade or elevated guideways and to either vertical or lateral irregularities. Typical results based on an idealized vehicle suspension system and typical ride comfort criteria reveal that the absolute upper bound on permissible profile elevation variations varies between 1.39 cm and 21.09 cm.
Frequency Domain Approach to the Computation of the Impulse Response of Population Systems
Authors: Huang I. B. , Chang W. T. , Kung F. C.
Published: November 2010

Since a population inherently is a distributed system, it usually is complex and difficult to find an exact solution by conventional mathematical methods. To facilitate the solution of population systems, in this paper, the distributed-parameter model is reduced to a lumped-parameter model with distributed time lag, and two methods in frequency domain approach are developed to compute the impulse response of population systems. Since there is no information loss in the computation, the result is considered to be exact. The data and procedure required for the computation are rather simple. A typical example is given.
Comparison of Continuous and Discrete Adaptive Identification Algorithms
Authors: Colburn Bruce K. , Boland Joseph S.
Published: November 2010

Discretization of a popular continuous-time control algorithm is effected and an equivalent discrete-time identification law developed and compared to a published discrete identification algorithm developed from Lyapunov Theory. Results are compared as regards asymptotic stability as insured using Lyapunov theory. Some analysis and design guidelines are proposed as regards implementation and practical utility.
Unsymmetrical, Transient Heat Condition: Rotating Disk Applications
Authors: Mote C. D.
Published: November 2010

The finite-element method is used in the development of a general, finite-dimensional, state variable formulation of transient heat conduction with surface diffusion. An explicit numerical scheme is used which provides a rational basis for the time-step selection. The general methods are applied in detail to the transient and steady-state conduction of a thin, uniform circular disk with uninsulated surfaces rotating past a stationary point source. The disk models examined illustrate the general utility of the formulation and discuss questions of concern in rotating disk heat transfer.
Dynamic Bending Stress in a Disk-Type Gyroscope Rotor Under Steady Precession
Authors: Sann R. I.
Published: November 2010

This paper derives the equations which govern the cyclic bending stresses in the web of a precessing gyro rotor, and discusses methods of solution. These stresses are important because they contribute to fatigue failure. Starting from the well-known partial differential equation describing the free lateral vibration of a thin variable thickness plate in the presence of initial centrifugal stresses, an ordinary differential equation for the mode displacement as a function of radius is obtained. Boundary conditions consist of a light, flexible shaft at the inside diameter of the web and a rigid, heavy rim at the outside diameter of the web. Three methods of solving for the modal functions and resonant frequencies are described. These are 1 Reduction to a matrix-eigenvalue problem by collocation, 2 Reduction to a matrix-eigenvalue problem by finite differences, and 3 An iterative solution based on numerical integration of the differential equation. Newton-Raphson interpolation against the eigenvalue is used to satisfy the boundary conditions. The forced vibration response to steady precession rate is evaluated from the Lagrange equation governing excitation of the fundamental normal coordinate. This coordinate corresponds to the lowest “fan” vibration made of the system, i.e., a mode in which the web has one diametral nodal line and no interior nodal circles. Numerical results show the variation of fan mode frequency with rotor spin rate, using web thickness as a parameter. Maximum radial and tangential bending stresses in the web are plotted against radius, using spin rate as a parameter. The numerical results indicate existence of an optimum rotor spin-rate, at which the allowable precession torque, based on web fatigue, is maximum for a given rotor structure.
On Bending of Curved Circular Tubes
Authors: Cheng David H. , Thailer Henry J.
Published: November 2010

Based on the improved general solution for a thin, circular tube subjected to in-plane end moments, the effect of the radius ratio on the stress distribution, rigidity, and stress intensification factors is studied. The existing asymptotic solutions are reexamined and modified to reflect the effect of the radius ratio. The modified asymptotic formulas are compared with the existing experimental results.
Effect of Creep in Low-Cycle Fatigue of Pressure Vessel Steel
Authors: Dubuc J. , Biron A.
Published: November 2010

Low-cycle fatigue tests have been carried out at 2 cpm on a pressure vessel steel at 350 deg C (662 deg F). The total strain range was fixed for each test and the minimum (or mean) strain in some cases was constant (zero minimum value), in others increased uniformly in time at a predetermined rate. It was found that variations in the mean strain up to 0.5 percent/hour had no significant influence on the results.
Deformation in Orthogonal Cutting
Authors: Ramalingam S.
Published: November 2010

This paper examines the plastic deformation process involved in chip formation during orthogonal cutting. Results of the grid deformation studies carried out on polymeric workpieces are reported. Chip formation is shown to result from the action of a curved shear surface, and it is shown that the configuration of the deformation volume during orthogonal cutting is fully determined by the orientation and curvature of the shear surface active during the cutting process. Implications of this model in metal cutting are discussed.
Dynamic Response Characteristics of the Urban Gravity-Vacuum Transit System
Authors: Caywood W. C. , Dailey George
Published: November 2010

The accelerations and displacements felt by a passenger aboard a high-speed train will, in part, be determined by the response of the train and guideway to irregularities in the guideway. For the Gravity-Vacuum-Transit (GVT) System, computer programs have been written for the dynamic response of the system to sinusoidal track disturbances. Some results have also been obtained for the response of the train to any shape irregularity in track surface. The analytical models range from a simple unsprung mass moving along a rigid track to a complete train of N-cars with suspension springs and dampers moving along a flexible track-tube structure which is itself suspended by springs and dampers from a rigid tunnel wall. Numerical results have been obtained which identify and evaluate some of the major constraints of the system. It is felt that the analytical techniques as well as some of the results have general application to the ride comfort evaluation of high-speed transportation systems.
Local Flexibility Coefficients for Axisymmetric Junctures
Authors: Jones D. P. , O’Donnell W. J.
Published: November 2010

A method of including the local flexibility due to cross-sectional warping at axisymmetric junctures is presented. Local flexibility coefficients are derived which have very general applicability in discontinuity analyses involving plate and shell elements. The effects of local flexibilities are quite significant at nozzle to vessel intersections, head to shell junctures, tube to tubesheet joints, and the like. The use of earlier plane strain local flexibility coefficients is found to be inaccurate except for junctures having very large radius-to-thickness ratios.
A Relaxation and Gradient Combination Applied to the Computer Simulation of a Plane Four-Bar Chain
Authors: Nechi A. J.
Published: November 2010

This optimization process uses only output data received from an analog simulation of the four-bar mechanism. The complexity of the analytical expression for the coupler curve is illustrated and explains the necessity of such a complex method to the curve synthesis. The minimization of the matching error between the desired and the obtained coupler curve is achieved by a combined relaxation and gradient method, and could also be used for other problems which require optimum solutions. An attempt is made to compare the random method with the presented procedure.
A Rating Formula for Fine Pitch Boundary Lubricated Gears
Authors: Walker T.
Published: November 2010

For the Instrument Engineer involved in the design of mechanisms that transmit power under boundary lubricated conditions, little information is available on which to base fine pitch gear load capacity and life. This paper discusses a gear test program and the development of a rating formula for the surface loading of these gears, and in particular those made from stainless steel and aluminum and stocked by precision gear manufacturers.
Coupler Cognates of Eight-Link Mechanisms With Ternary and Quaternary Links—Part 1
Authors: Soni A. H.
Published: November 2010

Using the principle of stretch rotation and the principle of similarly varying triangle, existence of coupler cognates of eight-link mechanisms with ternary and quaternary links is established. It is shown that there are two additional stationary foci; each of these stationary foci yields an infinite number of cognate mechanisms for a given source eight-link mechanism.
Development and Application of a Generalized d’Alembert Force for Multifreedom Mechanical Systems
Authors: Chace M. A. , Bayazitoglu Y. O.
Published: November 2010

A set of expressions termed the generalized d’Alembert force is determined for application to two and three-dimensional dynamic analysis of discrete, nonlinear, multifreedom, constrained, mechanical dynamic systems. These expressions greatly simplify the task of developing a correct set of second order differential equations of motion for mechanical systems which are nonlinear because of large deflections or other geometric effects. They apply to both constrained and unconstrained mechanical systems via the method of Lagrange equations with constraint. The two-dimensional version of the expressions has been successfully applied in a type-varient computer program for the dynamic analysis of mechanical networks, and example problems simulated with this program are discussed.
On the Smallest Circle Determined by Three Positions of a Rigid Body
Authors: Bottema O. , Koetsier T. , Roth B.
Published: November 2010

Three finitely separated positions of a rigid body determine circles which pass through the three homologous positions of each point. In this paper we determine the points in the body for which the radii of the associated circles have stationary values. In particular, we determine the global minimum, i.e., the point (or points), for which the associated circle has the smallest radius.
Dynamic Behavior and Design of Fatigue Test Specimens
Authors: Wolf Barry
Published: November 2010

In tension-tension, as well as in compression-tension, fatigue testing it has been observed that there exist combinations of loading and specimen characteristics for which the specimen becomes unstable. The theory explaining this behavior is well known and stability curves which predict the stability or instability of the specimen have been tabulated. Unfortunately these tabulations do not extend into the regions of interest for actual fatigue tests. The present work outlines the theory and offers a simple criterion for the design of stable fatigue tests which results from the extension of these stability curves.
Optimization of Multistage Machining System: Analysis of Optimal Machining Conditions for the Flow-Type Machining System
Authors: Hitomi K.
Published: November 2010

A fundamental mathematical model for the flow-type multistage machining system was built in an attempt to determine optimum machining conditions to be set on production stages. Based upon three kinds of evaluation criteria, i.e., the maximum production rate, the minimum production cost, and the maximum profit rate, the optimal cutting speeds to be set on production stages and the optimal cycle time for the multistage machining system were theoretically analyzed, and the computational procedure for obtaining them was developed. The computer program was also prepared and used to solve typical examples of optimzation of the multistage machining system.
Design of Rotating Disks With Integral Shafts
Authors: Surana K. S. , Seireg A.
Published: November 2010

This paper presents two-dimensional and three-dimensional procedures for evaluation of stress distribution in rotating disks of nonuniform thickness with integral shafts. The two-dimensional analysis is utilized in a design procedure to obtain the configuration of such disks which improves the tangential distribution. The three-dimensional analysis can then be used for accurate evaluation of the stress distribution. A comparison between the results from the two and three-dimensional analyses is illustrated by several examples.
The NEMO Submersible
Authors: Snoey M. R. , Briggs E. M.
Published: November 2010

The NEMO (Naval Experimental Manned Observatory) is the first transparent-hull submersible capable of operation to depths as great as 600 ft. Subsystems such as pressure hull, life support, power, hydraulic, and communications are described in this paper. The NEMO brings new and unique capabilities to the current family of undersea submersibles.
Requirements of Packaged Gas Compressor Units
Authors: Joplin J. L.
Published: November 2010

Basic application factors and limitations of gas compressors and prime movers are outlined. Selection of auxiliary equipment, instruments, safety devices, and drives is discussed along with fabrication and piping requirements.
Large Sideward Deflections of Two-Hinged Circular Arches
Authors: Dadeppo Donald A. , Schmidt Robert
Published: November 2010

Deflections and stress resultants are calculated for hinged-hinged circular arches subjected to a horizontal point load at the crown. The underlying theory is based on the Bernoulli-Euler hypothesis. The magnitudes of deflections are unrestricted. The solutions are expressed in terms of Legendre’s elliptic integrals of the first and second kind. Calculated results are presented in graphical form. These include deflected configurations and load-deflection curves, as well as normal force, shearing force, and bending moment diagrams for arches with three different subtending angles and three different values of the applied load on each arch.
Application of Gradient Search Procedures for the Identification of Unknown System Parameters From System Response Observations
Authors: Laurenson R. M. , Baumgarten J. R.
Published: November 2010

Techniques for identifying and evaluating the physical parameters of nonlinear dynamic systems have been investigated A method has been developed for converting the measured dynamic response of a system into estimates of its unknown dissipation function. A computational algorithm employing an optimization or gradient search technique was written for determining the unknown system parameters. This procedure uses a least squares criterion function to determine the measure of agreement between the mathematical representation of the system and the physical system. A rather general statement of the nonlinear equation of motion allows a better final determination of the system than that provided by some fixed-form describing function. The technique is especially adaptable to the identification problem of determining the dissipation function of a nonlinear shock absorber.
A Simulation Model for Flexible Rotating Equipment
Authors: Childs D. W.
Published: November 2010

The objective of the analysis which follows is the derivation of simulation models for flexible rotating equipment such as turbine rotors. The analysis employed is based on relatively simple concepts of vector mechanics and results in a “lumped-parameter” simulation model. The basic simulation model is simplified by invoking the small-deflection assumptions of the theory of elasticity. It is then restated in terms of a non-body-fixed (nonspinning) coordinate system. Methods for modeling bearing constraints and the applicability of eigenanalaysis are discussed. Representative numerical results are provided for a simulation of the Mark 15-F turbopump of the J-2 engine system.
Nonlinear Response of Gas-Lubricated Shrouded Rayleigh-Step Thrust Pad
Authors: Cheng C. , Cheng H. S.
Published: November 2010

The quasi-static pressure characteristics of a gas-lubricated thrust bearing with shrouded Rayleigh-step pads are determined for a time-varying film thickness. The axial response of the thrust bearing to an axial forcing function or an axial rotor disturbance is investigated by treating the gas film as a spring having nonlinear restoring and damping forces. These forces are related to the film thickness by a power relation. The nonlinear equation of motion in the axial mode is solved by the Ritz–Galerkin method as well as by direct numerical integration. Results of the nonlinear response by both methods are compared with the response based on the linearized equation.
A Strain Energy Comparison of Discrete Modeling for Vibrating Continuous Systems
Authors: Tolani S. K. , Rocke R. D.
Published: November 2010

Lumped parameter models commonly used to describe continuous one-dimensional and Bernoulli-Euler beam vibration problems have been compared on the basis of maximum system strain energy. The consistent mass matrix approach has been included in the comparison. Standard matrix techniques have been employed to mathematically obtain desired solutions. Closed form solutions and solutions via the models to the system strain energy were obtained for all systems in three dynamic states: Free vibrations, constant base acceleration, and half sine base acceleration. Behavior of the strain energy errors, in general, were found to be similar to those of the frequency root errors.
An Investigation of Broad Band Random Vibration Simulation
Authors: Roberts J. W.
Published: November 2010

The paper is concerned with the simulation of the action of a force environment on a multi-mode structure by means of a substituted force environment and is relevant to vibration testing of shell-like structures. The use of broad-band average spectral densities as response parameters in the simulation is justified. It is assumed that only simulation in some average sense of the modal responses in frequency bands can be contemplated because of the numbers of modes involved and their indeterminacy. By introducing a simple probabilistic model of the structure-environment interactions, some general results concerning the accuracy of simulation are deduced. Predictions of the simulation accuracy are shown to be possible if the relevant parameters can be estimated. This is confirmed by an experimental investigation.
Optimal Trajectories and Controls for Systems of Coupled Rigid Bodies
Authors: Townsend M. , Seireg A.
Published: November 2010

This paper presents a mathematical programming method for the performance synthesis of dynamic systems modelled by coupled rigid bodies. A technique is given for the decomposition and efficient evaluation of the trajectories and internal forces (controls) which cause a system to optimally perform tasks which may include cyclic relative motions between the bodies. The technique is useful for the synthesis of variable structure devices such as robots and all-terrain vehicles, and for the analysis of human and animal locomotion.
Fluctuating Lift Forces of the Karman Vortex Streets on Single Circular Cylinders and in Tube Bundles: Part 2—Lift Forces of Single Cylinders
Authors: Chen Y. N.
Published: November 2010

The fluctuating lift force of the Karman vortex on a single circular cylinder will be investigated theoretically for an ideal inviscid vortex street with rectilinear vortices. In this investigation the model introduced by von Karman will be used. As a result, the relationship between the fluctuating lift coefficient CL and the characteristic dimensions of the vortex street can be derived. This leads to establishing the equation between the fluctuating lift coefficient CL and the steady pressure drag coefficient CD. Since the curve of the theoretical lift coefficient practically envelops the spreading field of the experimentally determined points, the theory can be considered to be adequate to give the right order of magnitude for the lift of the Karman vortex. It will further be shown, that the spread of the measured values is in connection with the correlation length of the vortex along the cylinder axis.
On the Continuously Operating Tapered Arbor Spring Slip Clutch
Authors: Robe T. R. , Rogers J. C.
Published: November 2010

The criteria needed for the design of a continuously operating constant torque spring slip clutch are presented. These criteria include a tapered arbor feature which permits the design of a wearless chatterless clutch. The output torque of the resulting clutch is shown to be accurately predicted using the equations derived in the paper.
An Experimental Investigation of Lubrication in Hydrostatic Extrusion Using Wax as a Model Material
Authors: Wuerscher A. , Rice W. B.
Published: November 2010

This paper describes hydrostatic extrusion experiments in which paraffin wax was extruded, undertaken to test the validity of a theory proposed by Iyengar and Rice concerning the conditions necessary for hydrodynamic lubrication. Three fluids were used: castor oil, and two silicone fluids. Stress-strain curves obtained at several strain rates revealed that the particular wax behaves like many metals in that Y = Aεm. Strain-rates in the die are assessed, and corresponding values of Y are incorporated in the Hoffman and Sachs analysis of extrusion, which is then used to estimate the coefficient of friction from observed values of extrusion pressure. Analogy with journal bearing friction phenomena leads to the conclusion that at higher speeds hydrodynamic lubrication was attained with all three fluids, but that it was “thin-film” rather than “thick-film” predicted for similar billet speeds. Violent pressure fluctuations observed at higher speeds with castor oil, but not with the silicone fluids are attributed to smaller compressibility and viscosity of the castor oil.
The Use of Superplastic Alloy of the Eutectic of Lead–Tin for the Analysis of Hot Extrusion Process
Authors: Shabaik A. H. , Virani A. M.
Published: November 2010

The dynamic similarity of two geometrically similar extrusion processes was examined. The flow lines, values of the flow function ψ, and velocity components were compared for the hot extrusion of SAE 1018 steel at 1800 deg F and 10 ips, and the superplastic eutectic alloy of lead–tin at room temperature and 0.088 ipm. The comparison showed a good agreement between the two cases and that dynamic similarity of the flow fields was achieved under the previous conditions. Material properties were examined and results indicated that similarity of the mechanical properties is necessary for the dynamic similarity of the flow fields.
Computer-Aided Visioplasticity Solution to Axisymmetric Extrusion Through Curved Boundaries
Authors: Shabaik A. H.
Published: November 2010

A procedure for smoothing the experimental values of the flow function ψ in axisymmetric extrusion through curved boundaries was developed. The analysis was applied to a 45 deg conical die with a 6:1 extrusion ratio and a circular arc of 0.33-in. radius and 0.033-in. land at the exit section. An analytical expression of ψ in terms of r and z was obtained and used in the calculation of velocity and strain rate components in axisymmetric extrusion of a superplastic of the eutectic of lead–tin. The stress components were obtained from the known values of the strain rates by considering equilibrium and plasticity equations and material properties.
Analysis of Chatter Vibration Through Step-Function Response
Authors: Takeyama H. , Sakata O.
Published: November 2010

This paper deals with a challenge to apply the method of indicial response analysis for obtaining the frequency characteristics of total cutting system, tool system, and cutting zone. The feasibility of this method has been verified by simulation tests. Furthermore, linearity in cutting zone has been demonstrated to a first approximation by utilizing the proposed method. As examples of its application, on-line prediction or prevention of chatter vibration and simple evaluation of machine tool structure have been proposed.
Optimization of Finite Element Grids Based on Minimum Potential Energy
Authors: McNeice G. M. , Marcal P. V.
Published: November 2010

An initial study has been made of a method for optimizing finite element grids. This method is based on the minimum potential energy where the nodal point positions are also treated as independent variables. Necessary conditions have been obtained for the optimized grids. Case studies demonstrate the procedure for a one-dimensional tapered bar under axial load and for a two-dimensional square membrane subjected to a parabolic tensile stress. The optimized grids were observed to give improved stress estimates.