bluuebunny/crossref_metadata_2025 huggingface dataset:
Instability at an Interface Between Oil and Flowing Water
Authors: Jones W. T.
Published: November 2010

A linear, inviscid stability analysis is applied to the case of a relatively thin layer of stationary oil over a semi-infinite layer of water flowing at a constant velocity. Predictions of the velocity at which the interface becomes unstable and the effect of the oil depth on this velocity agree qualitatively with observations. Results can be applied to the problem of containing oil with mechanical booms. The model predicts initiation of oil loss by droplet separation from beneath the slick at low current velocities, for example, 0.39 to 0.53 fps for No. 2 diesel fuel depending on slick thickness. For practical purposes, earlier experiments have shown that this initial small oil loss by droplet entrainment can be tolerated up to a higher velocity of about 1.0 fps where substantial oil loss occurs.
In Vivo Determination of Elastic Modulus of Canine Cardiac Muscle
Authors: Lafferty J. F. , McCutcheon E. P. , Funk J. E. , Higgins A. M.
Published: November 2010

A practical technique was developed for in vivo determinations of the mechanical properties of canine left ventricle. A “quick stretch” was accomplished by rapid injection of isotonic saline into the ventricle during isovolumetric systole. The experimental pressure-volume data and a stress-strain analysis of the left ventricle as a thick-walled sphere permitted determination of the effective elastic modulus as a function of the mean circumferential stress. The elastic modulus E was found to be a linear function of the mean tangential stress σ throughout the isovolumetric systolic period; the slope (K, modulus of stiffness) of the Eversus σ curve was 18.8 with a standard deviation of 0.9.
Simulation of Cardiovascular Dynamics With the All-Pneumatic Artificial Ventricle System as a Replacement of the Myocardial Function
Authors: Tsang S. H. L. , duPlessis M. P.
Published: November 2010

The simulation of cardiovascular dynamics with the all-pneumatic artificial ventricle system as a replacement of the myocardial function is presented. The paper describes the mathematical models used in the study, and gives data that illustrate the effects of an artificial heart system on the hemodynamics of blood circulation. The results also show the regulation behavior of the pneumatic system as the vascular resistances are varied dynamically to double or half their normal values. The mathematical procedure described in the paper is a potentially powerful tool for the study of cardiovascular dynamics with an artificial heart to assist circulation.
Left Ventricular Function: Correlation With Deformation of the Myocardium
Authors: Phillips C. A. , Grood E. S. , Mates R. E. , Falsetti H. L.
Published: November 2010

The amount of local tissue deformation at the equatorial region of the left ventricle is quantitated by the ratio of the instantaneous cross-sectional area of a tissue element to the cross-sectional area at end-diastole. The area ratio, AR, was computed for the circumferential and longitudinal, apex to base, direction throughout the cardiac cycle from catheterization and cineangiographic data on 36 patients. The patients were divided into four groups: normal left ventricualr function—15, compensated volume overload—6, decompensated volume overload—9, and congestive cardiomyopathy—6. The peak longitudinal area ratio was elevated in the compensated group (P <0.001) and not statistically significant from normal in the decompensated group. A larger fraction of the cardiac cycle was required to reach the peak longitudinal (p <0.01) and circumferential (p <0.05) area ratio in the compensated group. The volume overload compensatory process apparently involves a change in the relative magnitude and timing of tissue deformation. The hypo-contractile ventricle was characterized by a reduction in the sum of the logitudinal and circumferential area ratios, which for all six patients in the congestive cardiomyopathy group, had a value less than any of the other thirty patients.
Stresses in Left Ventricular Wall and Biaxial Stress-Strain Relation of the Cardiac Muscle Fiber for the Potassium-Arrested Heart
Authors: Abe´ H. , Nakamura T. , Motomiya M. , Konno K. , Arai S.
Published: November 2010

Wall stresses and pseudo-strain energy function (W) were determined analytically from the pressure-volume relationships taken from (6 hypertrophied and 5 normal) canine hearts on the basis of large elastic deformation theory by assuming a spherical geometry of the left ventricles. The biaxial stress-strain relation of the myocardium was obtained from the function W. This relation was found to be more appropriate than the uniaxial relations for comparison of ventricles having different pressure-volume relationships and/or different sizes, since the uniaxial relation cannot be determined uniquely only from the pressure-volume relationship.
Analysis of Fully Developed Unsteady Viscous Flow in a Curved Elastic Tube Model to Provide Fluid Mechanical Data for Some Circulatory Path-Physiological Situations and Assist Devices
Authors: Chandran K. B. , Hosey R. R. , Ghista D. N. , Vayo V. W.
Published: November 2010

The unsteady and steady flow components of pulsatile flow response, to an experimentally monitored representative pressure pulse, are computed to provide fluid mechanical data for the etiology of arteriosclerosis at arterial curvature sites and for the design analysis of some extracorporeal dialysis and oxygenatory systems. The unsteady flow component of pulsatile flow in curved elastic tubes is simulated by the superposition of the first six Fourier components of a derived oscillatory flow solution of a viscous, incompressible fluid through an elastic tube of small curvature. The computer flow patterns, wall shear stress and hoop and axial stresses in the wall, due to unsteady and steady flow components of pulsatile flow response, are compared and their implications are discussed. The results show that the unsteady component yields shear stress of an order of magnitude greater than the steady flow, but the steady flow component has a greater variation in the shear stress distribution over a cross section. The steady and unsteady flow patterns are presented for several values of the tube diameters and curvature parameters typical of major arteries in the human circulatory system. The flow pattern and the stress variations could also prove useful in the design of extracorporeal systems such as dialysis machines and oxygenators.
The Effect of Pressure on Skin Temperature Measurements for a Disk Sensor
Authors: Mahanty S. D. , Roemer R. B.
Published: November 2010

In order to determine the effect of application pressure on the accuracy of skin temperature measurements for area contact sensors, low values of pressure (2-20 mm Hg) were applied to the mid-thigh and to the lateral aspect of the trochanter of human subjects using a thin, circular disk with a thermistor mounted in the base. From measurements of the local skin temperatures, it was determined that a pressure of 2 mm Hg is adequate to measure the skin temperature accurately. Applying larger pressure results in higher local skin temperatures with the thighs showing larger temperature increases than the trochanters. The results of a finite difference analysis indicate that the increases in skin temperature at higher pressures can be accounted for by the physical phenomena associated with the penetration of the sensor into the tissue. After the release of pressure, the local skin temperature immediately decreased for all subjects indicating little or no reactive hyperemia was occurring. A method of compensating for the changes in local skin temperature which are due to whole body transient thermal effects was also developed. Use of this method allows the effects of the local pressure application to be separated from the transient environmental effects.
Estimation of Systemic Arterial Impedance in Man From Cardiac Catheterization Data
Authors: Prakash R. , Grood E. S. , Mates R. E.
Published: November 2010

A five-parameter transfer function has been used to characterize the input impedance of the human systemic circulation. Aortic pressure and flow measurements obtained at cardiac catheterization are employed to evaluate the model parameters in individual patients. The appropriate parameters are chosen using a standard optimization technique to minimize the difference between pressures computed from the model and the measured values. Impedance parameters calculated for 19 patients showed considerable variation with no apparent correlation with the type of heart disease. The model is useful in describing the loading of the left ventricle produced by the systemic circulation. It may also have application to the study of vascular disease.
A Bond Graph Modeling Philosophy for Thermofluid Systems
Authors: Karnopp Dean
Published: November 2010

The unification that bond graph methods bring to the representation of mechanical, electrical, magnetic, and chemical kinetic systems is not completely achieved for fluid flow systems except in the special case of high pressure hydraulic systems. This is because power in fluid systems is not merely the product of two variables such as pressure and volume flow rate, but rather contains components due to the convection of internal and kinetic energy. Using a Lagrangian description rather than the more usual Eulerian description, however, normal bond graph elements succeed in representing fluid and thermal interactions. The approach leads to novel ways of simulating systems in which convection is important. Variable transport delay and dispersion are handled in a way preserving physical intuition since fixed quantities of matter are followed through the system.
On Gyrobondgraphs and Their Uses
Authors: Rosenberg R. C.
Published: November 2010

Graphical representations of lumped-parameter models for physical and engineering systems have been in use for some time. A relatively recent arrival is the bond graph, which displays energy flow and energy structure explicitly. Bond graphs are finding increasing use in a variety of applications, including classical electromechanical, hydraulic, and thermal energy systems as well as chemical and biological processes. In addition, there has been some effort to extend the approach to energy-like macroeconomic systems. The standard bond graph approach uses the same basic elements commonly found in network theory, although the graphing scheme is different. This paper defines a specific type of bond graph—the gyrobondgraph—and shows how it serves as a canonical form for a large class of lumped-parameter multiport models. The gyrobondgraph is based on only five elements and a standard graph format. A transformation procedure is described for obtaining a gyrobondgraph from a standard bond graph. The formulation of system equations associated with a gyrobondgraph is discussed briefly, and, as a point of interest, Tellegen’s Theorem in quasi-power form is derived. The gyrobondgraph appears to be an important new tool for the exploration of multiport system theory; furthermore, it is a source of new techniques for the computer simulation of bond graph models.
Basic Design Concepts of Laminar Fluidic Digital Logic Elements Using Laminar Proportional Amplifiers With Positive Feedback
Authors: Mon George
Published: November 2010

The basic design concepts of laminar digital logic elements using proportional amplifiers (LPA’s) with feekback are discussed. By using a decoupling amplifier, the input and output of these elements can be decoupled so that the switching threshold is independent of the output loading. Test results and theoretical predictions indicate that laminar digital logic elements with good performance characteristics can be designed by using LPA’s with feedback.
An Optimal Standard for Solar Heating Systems
Authors: Auslander D. M. , Tomizuka M. , Lee H.
Published: November 2010

Control problems in solar heating systems are studied. Using a load temperature regulation specification based on minimum temperature, an optimal control problem is formulated to compute a lower bound on the amount of auxiliary energy needed, over a given cycle, for a fixed solar heating system. In order to estimate the sophistication of control necessary for achieving higher performance, a comparative study is made among several simple controllers with both proportional and on-off actuation.
Analysis of Massless Elastic Chains With Servo Controlled Joints
Authors: Book W. J.
Published: November 2010

The lumping approximation used frequently for dynamic analysis of distributed parameter systems is facilitated for a class of flexible systems by a technique using 4 × 4 coordinate transformation matrices to account for the deflection of elastic elements under load. This approach is used to develop the linear equations of spatial motion for a system of two rigid masses connected by a chain with an arbitrary number of massless beams and controlled joint rotations.
A Simple Digital Control Scheme for a Class of Multi-Input, Multi-Output Industrial Processes
Authors: Tomizuka M.
Published: November 2010

This paper deals with digital control of m-input, m-output industrial processes. The controller design is based on two kinds of mathematical process models which can be obtained from the process step (or pulse) responses. The structure of the closed loop system includes an integral control action in the main feedback loop and state vector feedback control via observer in the secondary feedback loop. Simple formulas for finite time settling controller and observer gains are given. Two examples are given to illustrate the design procedure and to examine the closed loop sysem behavior under the finite time settling control scheme.
Optimum Nonlinear Control of a Class of Randomly Excited Systems
Authors: Thau Fred E.
Published: November 2010

Optimum nonlinear control laws are obtained for linear systems having performance criteria involving quartic and higher-order forms in the state variables. It is shown that the optimum control law in the presence of random disturbances and measurement noise is not the same as the deterministic optimum control law for this class of systems. A second-order example is used to illustrate the results.
Effects of Upstream Disturbances on the Spreading of Large Fluid-Amplifier-Type Jets
Authors: Gray R. W. , Shearer J. L.
Published: November 2010

Flow disturbances were introduced upstream of a rectangular nozzle and spreading jet confined by top and bottom plates to determine the effect on the velocity profiles. The mean velocity and turbulence distributions in the symmetrical mixing regions near a given nozzle are presented for several upstream disturbance intensity levels and several jet nozzle exit velocities. For the essentially two-dimensional jet flow from a high aspect ratio nozzle the results at several upstream disturbance intensity levels revealed the mean velocity distribution to be self-preserving near the nozzle. Over a large range of upstream disturbance intensity inputs the location of the virtual origin for each mixing region changed significantly while the mixing regions exhibited a constant maximum dimensionless spread rate. Other results for the essentially three-dimensional jet flow from a low aspect ratio nozzle did not show self-preservation in the mixing regions and furthermore revealed extraordinary changes in the velocity profiles.
Optimal Selection of Measurement Locations in a Conductor for Approximate Determination of Temperature Distributions
Authors: Cannon J. R. , Klein R. E.
Published: November 2010

This paper considers an on-line technique for estimating the bounded state of a process described by a linear heat conduction equation. The estimation procedure generates a rationale for the optimal selection of the transducer measurement location within the spatial domain of the conductor. Approximate state estimation is accomplished by two independent procedures, linear programming and least squares, respectively. Appropriate a priori and a posteriori error estimates of the difference between the solution and its approximation are derived. The concept of quasi closed-loop control is introduced, and an extensive listing of related literature for distributed parameter observability and continuation problems is given following the References.
Introducing Some Operational Characteristics of Mind—The Human Outlook and the Dynamics of Society
Authors: Iberall A. S.
Published: November 2010

For the engineer to deal with social questions, it is necessary that he have some basic view of how human behavior is governed in a technical sense. A foundational view is presented for the outlook of mind. This view is based on a neurophysiological abstraction regarding thought and action, not a sociological abstraction. Sources for the neurophysiological abstraction are proposed, but not herein detailed. It turns out that the neurophysiological characterization agrees with a philosophic-sociological truism, the law of the wings. It is offered here as the polar axis of response from radical to reactionary, as a generalized transform characteristic of the mind joined to the body and to the body of society. This axis of response is not simply a political polarization. It represents the transform by which any input set of impinging information hurls the mind-body into thought and action. This paper is concerned with the nature of that transformation.
On the Physical Basis of a Theory of Human Thermoregulation
Authors: Iberall A. S. , Schindler A. M.
Published: November 2010

This paper is concerned with the basis for thermoregulation under conditions of thermodynamic equilibrium. The thermoregulatory system can in principle only be understood through an appropriate integration of its physical, chemical, physiological and neurological aspects. The common description of thermoregulation simply as a hypothalamic “feedback” control of a servomechanical “set point” has not led to an adequate self-contained model. Review of steady-state data (nude, resting human, low wind and humidity, 5–45 deg C ambient temperature Ta) indicates that, at the very least, there are physical-physiological aspects of thermoregulation not explained by a hypothalamic set point model. Rather, we can point to a wide spectrum of cyclic “thermodynamic engine” processes which regulate the various subsystems of the body [1]. The cooperative orchestration of all these processes produces a dynamic regulation of temperature, essentially as a self-regulation. This dynamic regulation produces an overall thermal equilibrium for the entire body. To illustrate some unresolved equilibrium problems: Reported mean skin temperatures Ts versus Ta are incompatible with the physically determined skin-to-air transfer coefficient of about 7 kcal/m2/hr/deg C. At low Ta, either mean metabolism M must be higher or Ts must be lower, or the physical conductance must be rejected. One experimental test suggests that Ts is lower than commonly quoted (e.g., Ts = 26 deg C instead of 30 deg C at Ta = 20 deg (C). Such discrepancies may arise if free convective transfer is suppressed or if experiments are not carried on to equilibrium. Change in metabolism, heat storage, and tissue temperature may be significant for several hours, requiring at least 3 hours of sample data for accurate equilibrium temperature measurements. At low Ta, there is no solid evidence for metabolic regulation; in the cold, equilibrium M rises only 20–30 percent, not 200–300 percent as proposed by some workers. At high Ta, the usual definition of mean tissue conductance [C = M/(Tc − Ts)] leads to nonphysically large C as Ts approaches deep body temperature Tc. This paper is restricted to the physiological-physical modeling of the regulation of a variety of coupled fluxes (e.g., oxidative metabolism, evaporative flux, free and forced convective flux, fluid heat exchange) and potentials (e.g., internal and surface temperatures, evaporative phase changes). To resolve the foregoing difficulties we offer two hypotheses: (a) the body autoregulates a vital core; peripheral regions cool, e.g., extremity Ts drops toward ambient, the regulated core “contracts” longitudinally; (b) a significant portion of the evaporative heat loss may occur below the skin’s surface. Adjustment of two parameters emerging from these hypotheses allows a consistent modeling of steady-state thermoregulation. We suggest that hypothalamic control is one component of regulation and operates at higher frequency (with 7-min period) than steady-state autoregulation (3-hr period).
Sinusoidal Excitation of a Free Turbulent Jet With Constant Amplitude Transverse Pressure Gradients Near the Nozzle Exit: Part I: Measurement of Mean Shear Velocities
Authors: Stiffler A. K. , Shearer J. L.
Published: November 2010

A free turbulent jet is perturbed transverse to the flow direction by a sinusoidal pressure gradient near the nozzle exit. Velocities in the jet are determined by hot wire anemometer measurements. Moving effective mean velocity profiles are defined and reconstructed from the point-by-point stationary measurements of the mean velocity and of the harmonic content of the time varying signal. The effective velocity profiles are described by the Gaussian distribution function where the spread parameter decays as the cube of the product of the excitation frequency and the downstream location from the nozzle. These profile measurements and analysis of their characteristics lead to a better understanding of the factors determining the gain of a fluidic amplifier under conditions of high frequency operation.
A Constraining Hyperplane Technique for State Variable Constrained Optimal Control Problems
Authors: Martensson K.
Published: November 2010

A new approach to the numerical solution of optimal control problems with state-variable inequality constraints is presented. It is shown that the concept of constraining hyperplanes may be used to approximate the original problem with a problem where the constraints are of a mixed state-control variable type. The efficiency and the accuracy of the combination of constraining hyperplanes and a second-order differential dynamic programming algorithm are investigated on problems of different complexity, and comparisons are made with the slack-variable and the penalty-function techniques.
The Method of Relaxed Causality in the Bond Graph Analysis of Nonlinear Systems
Authors: Joseph B. J. , Martens H. R.
Published: November 2010

A method is presented for the formulation of mathematical models of nonlinear systems. The method employs as the underlying principle the relaxation of the requirement of explicit causality at 0- and 1-junctions. Instead, causal assignments are made which are consistent with the computing causality of the nonlinear elements, thus leading to causal violations in the conventional sense. A classification of causal violations is identified which provides information useful in the systematic derivation of algebraic equations. A most attractive aspect of the method is the fact that causal relaxation is required only when needed, and only to the extent needed.
Constrained Optimal Nonlinear Regulators for Single-State Feedback
Authors: Gay T. A. , Hoberock L. L.
Published: November 2010

This work considers the regulator problem for single input-output linear plants in which only the plant output is available for control. A method is presented to specify an optimal nonlinear controller characteristic, constrained to lie within a given Popov sector, that yields improved performance over that obtained by proportional controllers. System performance is measured by a quadratic performance index, and performance is compared with that of both proportional and optimum linear state regulators.
Stability Criteria for Distributed Nonlinear Sampled-Data Systems Defined by Green’s Functions
Authors: Jumarie G.
Published: November 2010

Sampled-data, nonlinear, distributed systems, which exhibit a structure similar to that of the standard closed loop with lumped parameter, are investigated from the viewpoint of their input-output stability. These systems are governed by operational equations involving discrete Laplace-Green kernels. Their feedback gains are bounded by upper and lower values which depend explicitly on the time and the distributed parameter. The main result is: an input-output stability theorem is given which applies both in L∞ (O, ∞) and L2 (O, ∞). This criterion, which may be considered as being an extension of the ≪circle criterion≫, involves the mean square value on the bounds of the feedback gain. Stability conditions for continuous systems are derived from this result. In the special case of systems with distributed periodical time-varying feedback gains, a stability criterion is given which applies in Marcinkiewicz space M2 (O, ∞). This result which involves the mean square value of the feedback gain is generally less restrictive than the L2 (O, ∞) stability criterion mentioned above.
Application of Process Computers in Automatic Control
Authors: Pavlik E. , Schendel C.
Published: November 2010

The process computer has become firmly established in industrial automatic control. It is used on an increasing scale for direct open-loop and closed-loop control. This opens up new possibilities for applying knowledge gained by the theoretical approach to problems of process automation. Remarkable results have already been achieved, but it has also been realized that automation has its practical limits, which are mainly due to the very nature of the processes themselves. Aspects of economy, reliable operation and easy handling are becoming more and more important for the efficient use of automatic control systems.
Longitudinal Track-Train Dynamics: A New Approach
Authors: Genin J. , Ginsberg J. H. , Ting E. C.
Published: November 2010

Using a measured functional relationship for draft gear characteristics a nonlinear model is developed to predict the coupler forces between cars of a railroad train. The model is then simplified, using modal expansion, to effect an economy of digital computation time.
LSI Microcomputer and Digital Control
Authors: Lee I.
Published: November 2010

This paper gives a tutorial presentation and overview of LSI microprocessor technology for control engineers and control logic designers. The historical background, present status and future trends of this dynamic technology are presented, and its enormous potential impact on digital control system design and implementation is explored through examples and extrapolation of the present trend.
Bond Graph Sign Conventions
Authors: Perelson A. S.
Published: November 2010

The lack of arbitrariness in the choice of bond graph sign conventions is established. It is shown that an unoriented bond graph may have no unique meaning and that with certain choices of orientation a bond graph may not correspond to any lumped parameter system constructed from the same set of elements. Network interpretations of these two facts are given. Defining a bond graph as an oriented object leads to the consideration of equivalence classes of oriented bond graphs which represent the same system. It is also shown that only changes in the orientation of bonds connecting 0-junctions and 1-junctions can lead to changes in the observable properties of a bond graph model.
Maximizing Distance of the Golf Drive: An Optimal Control Study
Authors: Lampsa M. A.
Published: November 2010

Optimal control theory is used to search for the optimal control torques necessary to maximize distance of the golf drive. In the method, a mathematical model of a generalized golf swing is first developed. Film of the author’s swing serves to verify the model and to supply parameter values, constraints, and actual torques. The variational formulation of optimal control theory is utilized to establish necessary conditions for optimal control, in which constraint violations are discouraged by inclusion of penalty functions. Finally, the method of steepest ascent is used to compute optimal control torques. Also, comparison of optimal and actual torques is made, and the sensitivity of the results to small changes in model parameter values is investigated.
Dynamic Interactions Between Vehicles and Elevated, Flexible Randomly Irregular Guideways
Authors: Snyder J. E. , Wormley D. N.
Published: November 2010

A dynamic interaction model is formulated for the heave-pitch motion of vehicles crossing elevated flexible, randomly irregular spans. Span dynamic motion due to a vehicle passage is modeled using a Bernoulli-Euler beam model and modal analysis techniques. Four types of random irregularities characteristic of elevated guideways are modeled numerically including vertical span offset, pier misalignment, camber, and surface roughness. Analytical expressions for each irregularity power spectral density are derived and the relative contributions of irregularities to vehicle excitation are examined. The limitations to vehicle passenger comfort levels posed by guideway deflection and irregularity are illustrated for personal and rapid transit types of vehicles.
Dynamics of an Electrohydraulic Stepping Motor
Authors: Vilenius M. J.
Published: November 2010

In this paper a nonlinear mathematical model is presented for a modified commercially constructed electrohydraulic stepping motor. With the aid of the model, the dynamic performance of the motor is examined and the quality of the model tested.
The Design of a Signal Synthesis Model Reference Adaptive Control System for Linear Unknown Plants
Authors: Nikiforuk P. N. , Gupta M. M. , Tamura K.
Published: November 2010

In this paper, a design of a signal synthesis adaptive controller for a class of linear time-varying uncertain plants using model reference adaptive control techniques is presented. Following a discussion of the general concept, the design of an adaptive controller for unconstrained and constrained control conditions is given. The small ultimate boundness of the state error is considered as the adaptation criterion, which is shown to be satisfied by a Liapunov type stability theorem. To handle the uncertainties that are associated with the plant dynamics and its environment, a min-max concept is employed in the design of the controller. The signal synthesis adaptive approach presented in this paper does not require as many structural assumptions as do most other adaptive approachers, and this is its principal advantage. The state vectors of the plant and model are assumed to be both accessible. Some simulation results are presented which illustrate the effectiveness of the design given here.
Microcomputer Implementation of Direct Digital Control Algorithms for Thermal Process Control Applications
Authors: Jacobs D. , Donaghey L. F.
Published: November 2010

The implementation and performance of direct digital control algorithms in a microcomputer-based controller was studied in relation to the control of nonlinear thermal processes. Particular emphasis was given to discrete algorithms such as proportional-integral and finite time settling control algorithms. Experimental studies were carried out with a nonlinear diffusion furnace controlled by an Intel 8080-based microcomputer system, on which the control algorithms were implemented. The performance of different, modified, linear control algorithms were evaluated in thermal process control applications.
A Planar Fluidic Flowmeter Applicable to Respiratory Flows
Authors: Parker G. A. , Hay A. E.
Published: November 2010

Tests are described on a bidirectional fluidic flowmeter for respiratory measurements using the principle first described by Tanney. Good dynamic response and acceptable linearity is achieved over most of the very wide flow range conditions encountered in respiratory flow measurements. A flow range of 380 litres/minute with a signal-to-noise ratio of 150 and a transient rate flow change of 14,500 litres/minute/second were measured for the best flowmeter configuration.
Fatigue and Burst Analysis of Hy-140(T) Steel Pressure Vessels
Authors: Barsom J. M. , Rolfe S. T.
Published: November 2010

Increasing use of high-strength steels in pressure-vessel design has resulted from emphasis on decreasing the weight of pressure vessels for certain applications. To demonstrate the suitability of a 140-ksi yield strength steel for use in unwelded pressure vessels, HY-140(T)—a quenched and tempered 5Ni-Cr-Mo-V steel—was fabricated and subjected to various burst and fatigue tests, as well as to various laboratory tests. In general, results of the investigation indicated very good tensile, Charpy, Nil Ductility Transition Temperature (NDT), low-cycle fatigue, and stress-corrosion properties of HY-140(T) steels, as well as very good burst tests results, in comparison with existing high-yield strength pressure-vessel steels. The results also indicate that the HY-140(T) steel should be an excellent material for its originally designed purpose, Naval hull applications.
A New Method of Making Square and Pentagonal Tubing
Authors: Lee D. , Coffin L. F.
Published: November 2010

A new process of forming square and pentagonal-shaped tubes from round tubes by rotating the tube between three rollers is described. It is found that, depending on the ratio of the roller diameter to tube diameter, the final shape of the tube could be altered. The process may have some commercial use as, for example, the forming of a square or pentagonal shape of some length at the end of the tube as well as remote from the ends. Consideration is given to the mechanism involved in forming these shapes, but because of the complex nature of the forming process, a detailed physical description cannot be outlined at the present time.
Glass Housing For Hydrospace Lights and Instruments
Authors: Gray K. O. , Stachiw J. D.
Published: November 2010

Commercially mass produced glass chemical reaction flasks and glass pipe sections have been experimentally evaluated for their adaptability to hydrospace applications. The evaluation concerned itself primarily with their implosion depths and fatigue life, although the effect of different surface finishes, bearing gaskets, and seals on their performance under hydrostatic pressure was also investigated. In addition to the evaluation of commercially available glassware for undersea applications, hydrospace lights and instrument housings have been designed utilizing some of the glass items evaluated in this study. These lights have been experimentally proven to cover the depth range from shallow waters to the greatest ocean depths.
A Bayesian Model of Machining Economics for Optimization by Adaptive Control
Authors: Ermer Donald S.
Published: November 2010

A learning model of tool wear based on Bayesian statistical methods provides a means for regulating the optimum cutting conditions as periodic sampling data on flank wear become available during production under adaptive control. The sampling process is used to estimate the current parameters of the wear process, and by incorporating this updated information into the machining economics model, an optimal a posteriori program of cutting conditions can be determined to best match the current conditions of the tool, workpiece, and machine. The application of the Bayesian learning model is illustrated for a basic turning operation with minimum cost as the optimizing criterion.
In-Plane Bending of a U-Shaped Circular Tube With End Constraints
Authors: Thailer Henry J. , Cheng David H.
Published: November 2010

A general solution is presented for a thin, curved, circular tube containing rigid end constraints, subjected to in-plane bending moments. Inextensibility of the meridional center line is assumed. The displacements are expanded in series form and the equations of equilibrium are guaranteed by minimizing the total potential energy. The minimization is achieved in the manner of Rayleigh-Ritz. Analytical results are compared with published experimental results and existing axisymmetric theory.
Static Force and Torque Analysis Using 3 × 3 Screw Matrix, and Transmission Criteria for Space Mechanisms
Authors: Bagci C.
Published: November 2010

The method of determining the static force and torque distributions in space mechanisms by use of the 3 × 3 screw matrix is presented. Transmissivities in favor of rotation and translation, and angles of transmission in space mechanisms are defined. Transmissivities are used to show why some space mechanisms have no dead center positions. In the process, the dual equilibrium equations, one for each link, are written in dual vector form, then they are solved simultaneously for the dual force components. Explicit expressions for forces and torques in the RCCC and RSSR space mechanisms are obtained. Torque distribution in the spherical four-bar mechanism is reduced from the results for the RCCC space mechanism. The numerical example considers a symmetrical crank-rocker RSSR space mechanism, where the output torque is due to the load inertia. Variations in the input torque, output torque, mechanical advantage, and transmission angle for one cycle are given for both geometric inversions.
On the Fundamental Mechanism of Large Strain Plastic Deformation: Electron Microscopy of Metal Cutting Chips
Authors: Black J. T.
Published: November 2010

The process of large strain plastic deformation, such as commonly found in the machining process, has been investigated by transmission and scanning electron microscopy techniques. The lamella-shear front nature of deformation in copper and aluminum chips has been elucidated fully and the occurrence of lamellae has been correlated with crystallographic and metal cutting parameters.
Complete Force Balancing of Spatial Linkages
Authors: Kaufman Roger E. , Sandor George N.
Published: November 2010

A new method permits the complete force balancing of spatial linkages such as the RSSR and RSSP mechanisms. Operator equations are written describing the location of the center of mass for the given mechanism. The coefficients of the time-dependent terms are set to zero by properly locating the mass centers of selected links. As a result, the location of the total center of mass is invariant and there is no resultant shaking force.
Design and Performance of High-Pressure Blowoff Silencers
Authors: Sparks Cecil R. , Lindgren D. E.
Published: November 2010

Through the application of fluid dynamic and acoustic theory, the noise generation of a high pressure blowoff can be approximated. The effects of silencer configurations can likewise be predicted through the application of pertinent field data taken to define performance of the silencer components. This paper describes recent test results and their application to improved silencer design for natural gas pipeline applications.
Force and Stability Measurements on Models of Submerged Pipelines
Authors: Wilson J. F. , Caldwell H. M.
Published: November 2010

The effect of currents on pipes anchored just above the ocean floor is the subject of this study. Lift, drag, and stability of two parallel pipes, parallel to a flat plane (the sea floor) were measured for simulated ocean currents up to two knots at several subcritical, free stream Reynolds numbers. First, a wind tunnel was utilized to find the lift and drag coefficients on two parallel, rigid, cylindrical models. The effects of horizontal spacing, vertical spacing from the ground plane, and orientation angle of the horizontal free stream velocity were observed. These results were compared to date available for the single and double cylinder cases where the ground plane was absent. Second, a water tow tank was utilized to observe conditions for vortex-shedding induced vibrations for fixed end, flexible, parallel cylinders. The natural frequencies and buoyancies of these models simulated pipelines of reasonable span clamped to evenly spaced anchor blocks. A numerical example illustrates the use of these data in the design of a dynamically stable piping system close to the ocean floor.
Velocities of Fragments From Bursting Gas Reservoirs
Authors: Taylor D. E. , Price C. F.
Published: November 2010

A solution is obtained from a simplified approach for the problem of the motion of two fragments driven into a vacuum after rupture of a container filled with gas. Following rupture, the two container fragments are driven in opposite directions. From the separation developed between the moving fragments, the originally contained gas escapes to the vacuum, perpendicular to the direction of motion of the fragments, and with locally sonic velocity. The present solution removes two restrictions of an earlier similar approach: (1) the speed of the gas within the original volume (and consequently, by inference, that of the fragments) is small relative to the sonic escape velocity, and (2) the volume between the separating fragments while they are accelerating undergoes negligible change from the original volume.
The Effect of Support Flexibility and Damping on the Synchronous Response of a Single-Mass Flexible Rotor
Authors: Kirk R. G. , Gunter E. J.
Published: November 2010

This paper deals with the dynamic unbalance response and transient motion of the single-mass Jeffcott rotor in elastic bearings mounted on damped, flexible supports. A steady-state analysis of the shaft and the bearing housing motion was made by assuming synchronous precession of the system. The conditions under which the support system would act as a dynamic vibration absorber at the rotor critical speed were studied and plots of the rotor and support amplitudes, phase angles, and forces transmitted were evaluated by the computer and the performance curves were plotted by an automatic plotter unit. Curves are presented on the optimization of the support housing characteristics to attenuate the rotor synchronous unbalance response. The complete transient motion including rotor unbalance was examined by integrating the equations of motion numerically using a modified 4th-order Runge–Kutta procedure and the resulting whirl orbits were plotted by an automatic plotter unit. The results of the transient analysis are discussed with regard to the design optimization procedure derived from the steady-state analysis.
Structural Damping Using a Four Layer Sandwich
Authors: Nakra B. C. , Grootenhuis P.
Published: November 2010

A serious limitation in the use of sandwich type damping with a single viscoelastic material is that the effectiveness is very frequency dependent. Practical applications demand a high overall loss factor over a wide frequency range. It is shown that this requirement can be met with a dual core made from two viscoelastic layers with very different values for the shear modulus, one to be at least 100 times greater than the other. This makes the construction asymmetric and the equations of motion have been derived using Hamilton’s energy principle. The solution cannot be given in closed form but computer results have been verified by experiment. Comparison with unconstrained layer damping and with 3-layer construction with an equal thickness damping layer has demonstrated the much wider frequency effectiveness of the 4-layer sandwich.
Automated Design Parameter Identification: A New Approach
Authors: Sevin E.
Published: November 2010

A new method for parameter identification of large dynamic systems is described, and the broad outlines of an automated procedure presented. The dynamic system may consist of an arbitrary assemblage of structural and mechanical elements for which numerical values of certain “design parameters” are to be determined. This “design” problem is formulated in discrete mathematical programming terms as a problem in constrained minimization. The method of solution is indirect, requiring first the time-wise synthesis of element response functions to optimally satisfy the stated design problem. The design parameters subsequently are identified by a function matching procedure in the time domain. For a large class of problems the optimal synthesis phase reduces to a problem in linear programming, while the parameter identification phase is a matter of least squares curve fitting for each design element independently. The great computational advantage over direct methods results from elimination of the need to repetatively solve the system dynamics during the identification process. Thus the computational size of the linear programming problem does not depend on the kinematic degrees of freedom of the dynamic system. An illustrative example involving 32 design parameters is presented.
Use of Direct Search in Automated Optimal Design
Authors: Pappas M.
Published: November 2010

A direct search penalty function procedure is described for treating a rather general mathematical programming form of the optimal design problem. A rotating coordinate modification of the pattern search of Hooke and Jeeves is proposed and compared with the original method, and an earlier variable step modification, as the basic optimal search method. The algorithm is successfully applied to several design examples which indicate that both modifications are comparable and are significantly superior to the original pattern search procedure.
A Survey of Optimization of Mechanical Design
Authors: Seireg A.
Published: November 2010

This paper presents a review of some illustrative examples of the use of optimization techniques in the design of mechanical elements and systems. The cases cited include gears, bearings, dynamic systems, rotating discs, pressure vessels, shafts under bending and torsion, beams subjected to longitudinal impact, and problems of elastic contact and load distribution.
Dynamic Shock Phenomena in Rolling Mills
Authors: Kashay A. M. , Voelker F. C. , Smalley A. J.
Published: November 2010

Torsional shock phenomena in a large steel rolling mill are studied. Results of field measurements on a finishing stand are presented. An analytical model of rolling mill systems is outlined, and the predictions of this model are compared with torque measurements. Satisfactory agreement is obtained. Certain significant factors affecting stress level in a rolling mill are established, and some recommendations are made for improving the maintenance performance of a mill.
Cord Force Measurements in Radial Tires
Authors: Walter J. D.
Published: November 2010

Miniature force transducers in the form of strain gage instrumented tension links are used to measure the loads developed in the rayon cords in both the stabilizer and body plies of automobile tires of radial construction. These transducers are placed in series with the cord and are embedded in the rubber matrix of the tire during building. Cord forces are obtained at various wheel loads and inflation pressures for straight ahead rolling and cornering of the tires in operation. It is shown that a relatively simple formula can be used to theoretically predict the cord tension developed in the sidewall region due to inflation pressure.
Influence of Flow Stress and Friction Upon Metal Flow in Upset Forging of Rings and Cylinders
Authors: Lee C. H. , Altan T.
Published: November 2010

An upper-bound velocity field that considers bulging has been applied to cylinder and ring upsetting. Computer programs have been developed to (a) determine strain, strain rate, velocity, and flow-stress distributions, and (b) predict load and bulge profile at various reductions by simulating the upsetting process. The calibration curve for a 6:3:2 ring, the load-displacement curves for ring and cylinder upsetting, and flow stress from the ring test have been predicted. The experimental results, with annealed 1100 Aluminum samples, agree well with theory at the lower and practical range of friction, but they show some disagreement at high friction.
General Theorems Concerning Full Force Balancing of Planar Linkages by Internal Mass Redistribution
Authors: Tepper F. R. , Lowen G. G.
Published: November 2010

Two basic questions concerning the full force balancing of n-linked planar mechanisms with pinned and sliding joints are resolved. A contour theorem is shown to differentiate between mechanisms which can be fully force-balanced and those which cannot. (Mechanisms with axisymmetric link groupings are excluded.) In addition, a generalization of the Method of Linearly Independent Vectors for single degree of freedom mechanisms is given, and it is proven that the “apparent” minimum number of counterweights producing full force balancing by internal mass redistribution alone equals n/2.