bluuebunny/crossref_metadata_2025 huggingface dataset:
Addition of Heated Solid Particles to a Gas Flowing in a Pipe
Authors: Rudinger G.
Published: November 2010

A number of processes, such as pneumatic conveying of powdered materials through ducts, feed lines for powdered rocket fuels, or certain flow processes in air-augmented solid-propellant rockets, involve addition of a stream of solid particles to a gas flow. The present study deals with the analysis of gas flows from a constant-pressure and temperature reservoir through a pipe into which the particles are injected at some point, and the pipe is assumed long enough to allow equilibrium between the gas and the particles to be established. Ultimately, the mixture is discharged into another reservoir of constant pressure. The temperature of the injected particles may be different from the reservoir temperature of the gas, so that the effects of simultaneous particle and heat addition must be considered. Allowance is made in the flow equations for the volume fraction occupied by the particles, and the analysis may therefore be applied to arbitrarily high particle loadings. To demonstrate the influence of the various parameters involved, the flow equations are solved numerically with the aid of a digital computer. With increasing particle loading the gas flow is markedly reduced, and the temperature of the discharge closely approaches that of the injected particles as a result of the high heat capacity of the particle stream. If this temperature behavior is assumed to hold, simple relationships can be derived which yield results in good agreement with data obtained from the complete equations if the loading ratio equals about ten or more for typical gas-particle mixtures. Of special interest is the finding that the gas flow needed to transport particles at a prescribed rate can be significantly reduced by heating of the particles before injection. It is demonstrated that equivalent direct heating of the gas would not be practicable unless the particle loading is quite low.
The Influence of Warm Prestressing on the Brittle Fracture of Structures Containing Sharp Defects
Authors: Harrison T. C. , Fearnehough G. D.
Published: November 2010

The low temperature fracture behavior of prestressed notched bars has been studied. The fracture stress was generally below the prestress level due to the influence of reverse plastic flow at the notch tip on unloading. When reverse plastic flow was prevented, low temperature fracture occurred at stress levels in excess of the prestress level. The benefits of prestressing are interpreted in terms of the introduction of plastic zones rather than the influence of residual stresses. The influence of aging and higher strain rates on the fracture behavior of prestressed specimens is also studied.
Impact Crater Formation at Intermediate Velocities
Authors: Byrnside N. C. , Torvik P. J. , Swift H. F.
Published: November 2010

The influence of projectile strength on cratering was investigated for projectiles of aluminum alloys impacting semi-infinite aluminum targets over the velocity range of 1 km/sec to 5.0 km/sec. The experimental results showed that crater diameters were not significantly influenced by varying projectile strength. The crater depths were found to vary appreciably with strength at lower velocities but to become virtually the same at 3.5 km/sec for the series of projectile alloys investigated. A simple dynamic model for cratering was developed and compared with the experimental results of this study and other experimental results at higher velocities. These comparisons showed that the model provided predictions of crater diameter which were within 8 percent for the experimental results of this study and within 13 percent for the hypervelocity data. Crater depth predictions showed good agreement with the experimental results of this study for projectiles having greater yield strength than the target material. The predictions of depth as a function of velocity showed qualitative agreement with the hypervelocity data.
Experimentally Determined Mean Flow Characteristics of Gas-Solid Suspensions
Authors: Kramer T. J. , Depew C. A.
Published: November 2010

Particle velocity profiles, air velocity profiles, and local particle flux profiles were determined experimentally for suspensions consisting of air and spherical glass particles having average diameters of 62 and 200 microns. Three tube sizes were used: 0.5, 0.75, and 1.0 in. diameter, and the Reynolds number ranged from 5670 to 50,000. Continuum theory of suspension flows predicts a universal velocity profile for the suspension, and the experiments produced suspension velocities which form a family of logarithmic curves with the mass loading ratio as a parameter. Each profile was found to be independent of Reynolds number. Other results are presented and compared to the analytic solutions which are presented in another paper [1].
A Study of Creep Damage Rules
Authors: Abo El Ata M. M. , Finnie I.
Published: November 2010

A brief review is given of the literature on damage accumulation during creep and inadequacies in our present understanding are pointed out. By drawing on recent studies of the processes involved in creep-rupture, it is suggested that a new criterion for creep-damage accumulation may be proposed, which is more general than existing approaches. This involves the consideration of both the initiation and propagation phases of fracture, and it is seen that in some cases, strengthening rather than weakening may result from prior loadings. Experimental results are cited in support of these observations.
Hydrodynamic Winch for Salvage Operations
Authors: Rosenberg E. N.
Published: November 2010

Lifting or lowering of very heavy loads in the ocean (1000 tons or more) from any depth under controlled conditions has proven to be very difficult. Lifting very heavy loads from great depths using the present winching or lifting methods is for practical purposes nonexistent. Pontoons and winches have been used for limited loads and limited depths. The problem of breakout forces, buoyancy controls, dynamic wave induced cable stresses, etc., have made very heavy lifts from the ocean depths almost impossible to perform. The Hydrodynamic Winch is a proposed solution to the very heavy undersea lift and control problem.
Rheological Equations for Synovial Fluids
Authors: Lai W. M. , Kuei S. C. , Mow V. C.
Published: November 2010

This review examines a number of theoretical constitutive equations which are applicable to the description of rheological behaviors of synovial fluids. These equations include the integral type, the rate type, the differential type and the generalized new-tonian fluid. Explicit values of the material parameters and/or material functions appearing in these equations are obtained from the many rheological measurements on synovial fluids of the literature. Many of the values of these parameters are taken from the literature, but some are newly computed values obtained by the present authors to make the list of available constitutive equations more extensive, using the existing experimental data. It is hoped that the diversity of the constitutive equations presented here and their appropriate material constants and/or functions will afford researchers in the field of synovial joint biomechanics the choice of a particular constitutive model for synovial fluid to meet their specific purpose.
Inversion of a Class of Nonlinear Stress-Strain Relationships of Biological Soft Tissues
Authors: Fung Y. C.
Published: November 2010

The mechanical properly of soft tissues is highly nonlinear. Normally, the stress tensor is a nonlinear function of the strain tensor. Correspondingly, the strain energy function is not a quadratic function of the strain. The problem resolved in the present paper is to invert the stress-strain relationship so that the strain tensor can be expressed as a nonlinear function of the stress tensor. Correspondingly, the strain energy function is inverted into the complementary energy function which is a function of stresses. It is shown that these inversions can be done quite simply if the strain energy function is an analytic function of a polynomial of the strain components of the second degree. We have shown previously that experimental results on the skin, the blood vessels, the mesentery, and the lung tissue can be best described by strain energy functions of this type. Therefore, the inversion presented here is applicable to these tissues. On the other hand, a popular strain energy function, a polynomial of third degree or higher, cannot be so inverted.
Blood Perfusion Measurements by the Analysis of the Heated Thermocouple Probe’s Temperature Transients
Authors: Johnson W. R. , Abdelmessih A. H. , Grayson J.
Published: November 2010

The Gibbs’ heated thermocouple technique for measuring a tissue’s thermal conductivity to infer the blood perfusion rate has been synthesized with a model of transient heal transport in perfused tissue. This procedure eliminates the necessity of probe calibration in surrogate tissue. The analytical predictions of the transient temperature behavior of a newly designed spherical probe were compared with experimental temperature transients to deduce thermal conductivities of and perfusion rates in gelatin and dog kidney. The principle heating modality was step heating. Consistent conductivity values for both the gelatin and the kidney were found. The calculated perfusion rates in the kidney were consistent but were higly dependent upon probe size and geometry, and the independently measured tissue’s thermal conductivity.
Effect of Fixed Axes of Rotation on the Varus-Valgus and Torsional Load-Displacement Characteristics of the In-Vitro Human Knee
Authors: Rastegar J. , Piziali R. L. , Nagel D. A. , Schurman D. J.
Published: November 2010

The effects of fixed axes of rotation on the varus-valgus and torsional load-displacement characteristics of the human knee have been determined. The location of the axes of varus-valgus and torsional rotations resulting in minimum resisting loads are also determined, and it is shown that they correspond to minimal coupled load levels. The coupled loads are seen to be sensitive to the location of the axis of rotation. The nonlinear load-displacement data is fitted with a four interval least-squares cubic spline with matching first and second derivatives at nodes. The data from two fresh human knees are presented.
Thermal Conductivity and Thermal Diffusivity of Biomaterials: A Simultaneous Measurement Technique
Authors: Balasubramaniam T. A. , Bowman H. F.
Published: November 2010

A technique is presented for the simultaneous determination of thermal conductivity and thermal diffusivity of biomaterials. Measurements are derived from the transient power supplied to a thermistor probe operated in a self-heated mode. The thermal properties are extracted through the use of an appropriate thermal model. Thermal conductivity is determined through a simple algebraic equation. Thermal diffusivity is determined from a convenient set of nondimensionalized curves. The technique can be used in vivo and in vitro. Measurements can be made in sample volumes of less than 1 cc in less than 30 s.
Analysis of an Artificial Ventricle and Mock Circulatory System
Authors: High K. M. , Brighton J. A. , Brickman A. D. , Pierce W. S.
Published: November 2010

A mathematical model is developed for calculating the pressures and flows in an artificial heart, its pneumatic drive unit, and a mock circulatory system. The system is divided into convenient subsystems to facilitate the analysis, and each subsystem is then analyzed separately. The set of independent equations developed is solved on a computer and corresponding experimental tests are made on the actual system. A comparison of the experimental and computer results shows good agreement for the mean flow rate through the pump and also for several instantaneous pressures and flow rates in the system.
Instrument Design for Vitreous Surgery via the Pars Plana
Authors: Harvey G. R.
Published: November 2010

The vitreous body is a transparent gel occupying the posterior segment of the ocular globe. In diseased states, vision is obscured by haemorrhage or opacity or may be lost because of retinal detachment. The design of instruments for pars plana vitrectomy is based on the therapy of the disease. Conclusions drawn from human and mechanical factor analysis have been grouped into four categories: (a) instrument design parameters; (b) surgical procedure; (c) intraocular illumination; and (d) indications and results. Possible extensions with fibre optic illumination of the infusion system are indicated.
Coupled Vertical-Lateral Dynamics of a Pneumatic Tired Vehicle: Part I—A Mathematical Model
Authors: Nathoo N. S. , Healey A. J.
Published: November 2010

A method is presented which permits the simulation of the coupled vertical and lateral rigid body vibration response of an automobile to roadway roughness inputs. A set of equations in matrix form is obtained for an assumed ten degree-of-freedom mathematical model of the vehicle-tire system using generalized linear and Euler angle coordinates. Kinematic relations for a rolling tire which treat it as an elastically supported string under tension are incorporated into the overall system model. Forces and moments that act in the tire-roadway contact interface are represented mathematically as a function of the parameters and response variables of the vehicle system. The nonlinear system equations are subsequently simplified in order to apply them to a vehicle moving along a straight roadway. The formulated model is shown to be adequate for predicting acceleration response in a frequency range of 0.1–10 Hz for the set of roadway test roadway sections considered in the present study.
Nonlinear Wheelset Forces in Flange Contact—Part 1: Steady State Analysis and Numerical Results
Authors: Sweet L. M. , Sivak J. A.
Published: November 2010

A theoretical model for steady-state wheelset force/displacement relations in tread and flange contact is presented. The analysis includes nonlinear geometric constraints that characterize wheel/rail contact, creep forces in the contact plane due to wheel/rail differential velocities, limits on adhesion at each contact point, and equilibrium conditions applied to the wheelset body forces. Results are summarized as the resultant lateral force and yaw moment acting on the wheelset as functions of lateral position and yaw angle. The results of this analysis, verified experimentally in Part 2 of this paper, are important to the analysis of wheelset response to track inputs, curving performance, and wheelclimb derailment.
Indirect Control of the Forces of Constraint in Dynamic Systems
Authors: Hemami H. , Wyman B. F.
Published: November 2010

In this paper two problems are investigated; how to control a dynamic system such that holonomic constraints are maintained and further the forces of constraint are a priori specified. Two cases of the latter are considered: constant forces of constraint and forces that are functions of the state. The dynamic system is linearized about an operating point and linear feedback is exploited for the solution of both problems. A methodology for computing the feedback gains is developed and applied to a nonhuman biped model that possesses ankle torques in the frontal plane. Simulation results are carried out for the nonlinear biped model to maintain the vertical force of constraint constant under the foot. Applications to locking of joints in natural biological systems is noted.
A Design Procedure for a Class of Distributed Parameter Control Systems
Authors: Orner P. A. , Foster A. M.
Published: November 2010

A rational deterministic design procedure is presented for a class of distributed parameter multivariable plants described by linear scalar differential equations. The Galerkin projection method is employed to form an approximate finite dimensional plant model. The subsequent solution of a quadratic regulator problem for the finite dimensional model results in a lumped multivariable controller which operates on the inputs and outputs of the actual plant. A deterministic observer is constructed to estimate the model state. Techniques for optimal location of the input zones and output transducers are developed. Two examples are presented.
Active Control of Vehicle Air Cushion Suspensions
Authors: Hullender D. A. , Wormley D. N. , Richardson H. H.
Published: November 2010

A primitive vehicle suspension system coupling a simple vehicle model to a guideway having random irregularities is defined. The optimum linear suspension which minimizes a linear combination of vehicle heave acceleration (a passenger comfort index) and suspension-guideway displacement (a measure of required suspension stroke length) is synthesized using a Wiener- Ho¨pf technique. This optimum suspension, which is independent of specific mechanical, magnetic, or fluid methods of implementation, is used to determine the form of active control required to make the performance of a flexible-skirted air cushion suspension approach the optimum performance. The optimally compensated suspension acceleration, flexible base, and gap height excursions are computed and compared with those of optimum passive suspensions. A reduction in acceleration by a factor of 2.7 is possible with optimum active control. Finally, the limitations and constraints in implementing both optimum and suboptimum control of an air cushion suspension were studied using a small scale experimental suspension.
Determination of Optimal Multiyear Air Pollution Control Policies
Authors: Kyan C. P. , Seinfeld J. H.
Published: November 2010

A general theoretical framework for the determination of multiyear air pollution control strategies for an airshed is presented. It is assumed that emission control procedures are changed on a year-to-year basis. The problem considered is to determine the set of control measures that minimizes the total cost of control while maintaining specified levels of air quality each year. It is assumed that an airshed model exists which is capable of predicting pollutant concentrations as a function of source emissions in the airshed. It is shown that the general multiyear problem can be solved by discrete dynamic programming. The method is illustrated on the problem of determining control strategies for carbon monoxide for a three-year period in the Los Angeles basin.
An Obscure Influence in the Golf Shot
Authors: Williams A. J.
Published: November 2010

Over 20 years ago the author began to apply a little science in his search for the cause of a tendency to “slice” his golf shots. His 1957 ASME paper [1] defined the object of the search as “An obscure influence which brings the club head from a position trailing the shaft (for the greater portion of the down swing) to a position abreast of the shaft at impact.” Many informative measurements were described, but the “obscure influence” remained obscure. Since his retirement in 1968 the author made an exciting discovery about the left wrist, which led to an understandable theory, thus making the obscure less obscure. A crude mechanical analog was built, the performance of which, checks the theory, at least to the satisfaction of the author.
Parameter Identification Using the Galerkin Procedure in Nonlinear Boundary-Value Problems
Authors: Neuman C. P. , Casasayas F. G.
Published: November 2010

This paper introduces a computationally rapid and effective approach for parameter identification in both linear and nonlinear boundary-value problems. The technique proposed evolves around application of the Galerkin procedure with a small number (N ≤6) of low-degree polynomial modes and employs the Newton-Raphson method and quasilinearization. The numerical results presented illustrate the power of the approach.
Direct and Inverse Transformations Between Phase Variable and Canonical Forms
Authors: Beck R. R. , Lance G. M.
Published: November 2010

A complete, general treatment of the transformations, direct and inverse, between the phase variable form and the canonical or Jordan canonical form of the system matrix is presented. Analytical expressions are obtained for the matrices and all combinations of real, complex, distinct, and repeated eigenvalues are covered.
Guideway Camber and Three-Stage Passive Suspension for Improved Tracked Air Cushion Vehicle Ride Quality: Part II of a Parametric Study
Authors: Biggers S. B.
Published: November 2010

Two means of providing a high quality air cushion ride at high speed using simple passive suspension systems are investigated. The inclusion of the proper amount of camber in guideway beams is shown to greatly reduce both low and high speed heave accelerations. A three-stage passively suspended vehicle including two degrees of pitching motion is shown to eliminate the high speed peak in accelerations present with two-stage vehicles. The effects of secondary and tertiary damping, of the vehicle to span length ratio, and of guideway camber on the ride quality of this vehicle are investigated. Coupled with cambered guideway beams, the three-stage passive suspension system appears to be an attractive alternative to active suspension systems.
Fluidic Control of a Hydrostatic Transmission in a Vehicle Propulsion System
Authors: Reid K. N. , Woods R. L.
Published: November 2010

A vehicle propulsion system is considered which consists of an engine, hydrostatic transmission, and automatic controller. Control requirements are established for optimum or near optimum operation based on a steady-state performance index. Various controller classes are identified and a systematic method for synthesis of the “best” controller is outlined. A unique fluidic controller is discussed which adjusts the transmission ratio to maintain a specified engine speed-engine load relationship which maximizes overall system efficiency for a wide range of external load conditions.
Identification of Parameters in Nonlinear Boundary Conditions of Distributed Systems With Linear Fields
Authors: Ward E. D. , Goodson R. E.
Published: November 2010

A method is presented for the formulation of an experimental procedure for the identification of unknown parameters in nonlinear boundary conditions in distributed parameter dynamic systems. In contrast to other available techniques, this method requires only as many measurement sensors within the field as there are unknown boundary conditions. Results are presented for simulated data from an example of heat conduction with a radiation boundary and for experimental data from a cantilever beam with a nonlinear moment at the boundary. The method may be applied to partial differential equations which are linear, one-dimensional, and have known time invariant coefficients. The nonlinear boundary conditions are specified up to a set of unknown constant parameters which appear linearly in the boundary conditions.
Design Criteria for Multi-Axis Closed Loop Computer Numerical Control Systems
Authors: Middleditch A. E.
Published: November 2010

Automatic machine tools have traditionally been controlled by hard-wired numerical controllers (NC). Recently, systems have been introduced which use a general purpose mini-computer (CNC). Some of these computer systems generate position references and close the position control loops of the machine tool’s feed axes using software, while others retain these functions in hardware. If the software approach is used, the dynamic performance of the system may be degraded. This paper investigates the constraints necessary to avoid severe performance degradation.
Stabilization of Nonlinear Systems Using Linear Observers
Authors: Strane R. E. , Vogt W. G.
Published: November 2010

In this paper, it is shown that a linear observer can always be designed to stabilize a nonlinear system which contains a Lur’e type nonlinearity in the sector [0, k], where k is finite, if both the output of the nonlinearity and a completely observable output of the linear portion are available as inputs to the observer. In case a completely observable output is not available from the linear portion, stabilization is shown to be possible if the original linear approximation of the system is asymptotically stable or those state variables corresponding to the unstable eigenvalues are available. It is also established that a linear observer can be used to guarantee that a finite region of asymptotic stability exists for a plant described by a more general set of nonlinear equations, and in some cases the domain of asymptotic stability can be made as large as desired.
Optimal Direct Control Programs for a Prey-Predator System
Authors: Vincent T. L. , Cliff E. M. , Goh Bean-San
Published: November 2010

Numerous biological systems involve species acting out the roles of prey and predators. In this paper, it is assumed that the prey feed upon resources of value to humans and that the predators only food supply is the prey. An often used control program for such a situation is a direct one in which the prey are controlled by destroying them outright. Such programs often times also involve the predators resulting in side effects which can be both unexpected and unpleasant. In this paper, the influence of direct human control is added to a known model for a prey-predator system. Optimal control programs are determined for a cost function dependent upon both resource damage due to the prey and economic (including environmental) costs of control. The basic characteristics of a direct optimal pest management program are illustrated with several figures and discussion.
Performance of Magnetic Suspensions for High Speed Vehicles Operating Over Flexible Guideways
Authors: Katz R. M. , Nene V. D. , Ravera R. J. , Skalski C. A.
Published: November 2010

A real time simulation is used to analyze two idealized MAGLEV suspensions, one an attraction (ferromagnetic) system and the other a repulsion (cryogenic) system. Performance characteristics are presented. The effects of guideway roughness, guide-way flexibility, and of force nonlinearities are examined. On the basis of the cases investigated, it is concluded that MAGLEV suspension systems for 300 mph vehicles which provide reliable tracking while meeting ride quality criteria can be designed. It is also apparent that a considerable effort is required to achieve MAGLEV system optimization and refinement.
Jackknifing of Tractor-Semitrailer Trucks—Detection and Corrective Action
Authors: Susemihl E. A. , Krauter A. I.
Published: November 2010

This paper is concerned with the detection of an incipient tractor jackknife of a tractor-semitrailer truck and with corrective action which can be taken after the onset of jackknifing has been sensed. An approach termed local linearization is used to define tractor jackknifing in a quantitative manner. Local linearization is then used to evaluate a second approach, termed side force-slip angle combination. This side force-slip angle combination is employed to study three forms of automatic corrective action that involve braking of the vehicle. The results obtained indicate that local linearization provides an adequate definition of the onset of jackknifing. The results also indicate that the side force-slip angle combination is useful in sensing the onset of a tractor kackknife. Through the use of approximations, the side force-slip angle combination can be implemented in a real vehicle—this implementation is found to require only simple measurements. The results of the corrective action study indicate that a certain anti-skid braking procedure may be effective in the prevention of an incipient jackknife.
Approximate Analysis of Nonlinear Systems With Narrow Band Random Inputs
Authors: Zirkle L. D. , Sumaria V. H.
Published: November 2010

A variational averaging technique is applied to nonlinear systems with narrow band inputs. The technique requires that a form for the approximate solution be obtained by some means. The case of narrow band inputs places unique requirements on the selection of certain parameters in the approximate form. A conceptual development of the important factors is presented and applied to several specific examples. Results show that the technique is capable of producing good approximations and specific methodology is suggested for several cases.
Multiple and Continuous Span Elevated Guideway-Vehicle Dynamic Performance
Authors: Smith C. C. , Gilchrist A. J. , Wormley D. N.
Published: November 2010

Analyses are developed to determine the dynamic performance of vehicles interacting with single, multiple, and continuous span elevated structures. Operating conditions in which multispan resonant conditions occur are identified, and the resulting resonant amplitudes computed. Guideway design examples considering tracked, levitated vehicles are described to illustrate the influence of span configuration and vehicle speed and suspension properties upon guideway span design for vehicle-guideway systems required to provide specified passenger comfort levels. For the 150 and 300 mph (242 and 483 km/h) vehicle systems considered, continuous and multispan guideway configurations were found to have reduced span material requirements in comparison to single span systems which provide the same level of passenger comfort.
A Gas Bearing Mechanism for Stable Electrical Recording From Individual Neurons in Pulsating Human Cerebral Cortex
Authors: Goldstein S. R. , Schmidt E. M. , Bierley F. L. , Bak M.
Published: November 2010

The instrument described enables acute electrical recording from single cells in the human cerebral cortex with minimal tissue trauma. In spite of the great long-term interest that has been manifest in this type of measurement, until now, such recordings have been extremely limited due to difficulties caused by cortical motions of several mm occurring when part of the cranium is removed during surgery. The new mechanism uses gas journal and thrust bearings to enable a recording microelectrode to continuously remain near a single cell while exerting extremely small contact force on the cortex. The recording microelectrode is mounted on a miniature lead screw attached to a rider tube which is supported in gas journal bearings so it can freely follow the pulsatile motion of the brain surface. The microelectrode, protruding up to 5 mm beyond the rider tube into the cortex, moves with the surface and thereby retains its relative position in the tissue throughout the motion. The rider tube weight is offset by an internally generated variable pressure force that automatically maintains the contact force less than 11.7 × 10−4 N (0.004 oz) for electrode insertion angles up to 1 rad from vertical. The resultant contact pressure is approximately 1.1 × 102 Pa (0.9 mm Hg), a value considerably less than the tissue capillary perfusion pressure. Recording depth is varied without disturbance to the cortex by actuating the lead screw with an assembly of gas thrust bearings which do not influence the axial motion of the rider tube. During checkout on rhesus monkeys, a single cell was “held” for 50 min in the presence of 3/4-mm peak-to-peak cortical motions. Recordings were obtained from a single cell in a human cerebral cortex undergoing 1-1/2-mm pulsations over a period of 17-1/2 min at which point the protocol was terminated in order to proceed with the surgery.
Optimal Discrete Finite Preview Problems (Why and How Is Future Information Important?)
Authors: Tomizuka M. , Whitney D. E.
Published: November 2010

The preview control problem is one in which a controller can use future as well as present and past information to determine the control. In the optimal discrete finite preview problem studied in this paper, the controller is assumed to make use of preview information with respect to command signal (desired trajectory) from the present time i up to Nla time units in the future. Nla is called the preview time, and is usually shorter than N, the problem duration. To make the solution applicable to a broad class of problems, measurement time delay, observation noise and driving noise are included in formulating the problem. The solution shows how to utilize the local future information obtained by finite preview (Nla) to minimize an optimality criterion evaluated over the problem duration (N). An illustrative example is given to show that preview drastically improves the performance of a system relative to non-preview optimal performance, and that there is a critical preview length essential for such an improvement.
A Space Function Approach to the Hyperstability and the Average Hyperstability of Distributed Systems With Space-Varying Linear Parts and Time-Varying Gains
Authors: Jumarie G.
Published: November 2010

We propose an extension of the Popov’s hyperstability theory which applies to a class of single-control distributed systems in which the linear part depends explicitely upon the distributed parameter, z. The nonlinearness of these systems is expressed by means of the control. The main features of our results are the following: (i) The hyperstability conditions that we obtain involve specific z-dependent functions which we can consider as being extensions of the transfer function concept; (ii) they also involve integrals with respect to the distributed parameter, which express an averaging effect of this latter. Then systems in which the admissible controls are defined via time-varying conditions are investigated. For such systems, we define the concept of “average hyperstability” in time, and average hyperstability conditions are given. Similar problems are solved for multi-control distributed systems. As an application we show how these results yield a broad class of absolute stability conditions for distributed systems: they are space averaging conditions and they may apply when other criteria are in-applicable. Three examples are given: the last one illustrates how a space-describing function approach can be used to determine the distributed transfer function of the system.
Analysis of Tool Wear: Part II: Applications of Flank Wear Models
Authors: Bhattacharyya A. , Ghosh A. , Ham Inyong
Published: November 2010

For machining with cemented carbides and ceramics, a quantitative assessment of tool failure at the flank for establishing “limit criterion” is necessary. The arbitrarily chosen flank wear limit for all cutting speeds is not valid at higher cutting speeds because of the earlier appearance of the “inflection point” which is often taken as criterion of flank-failure. In this paper, proceeding from the basic physical model of flank wear described in Part I of the paper (ASME Paper No. 68—WA/Prod-5), tool-life relations in the form of Taylor’s equations have been theoretically developed, the parameters of which have been compared with, experimental results. Further, the critical points of inflexion where the flank-wear characteristic enters temperature sensitive region resulting in accelerated wear have been uniquely defined. The location of these critical points have also been verified experimentally.
Helical Coils as Impact Load Dispersers
Authors: Suh N. P.
Published: November 2010

The concept of using tangentially loaded helical coils as impact load dispersers was examined experimentally and theoretically in order to evaluate its effectiveness in minimizing the amplitude of shock loading. It was found that the initial stress pulse decomposed into several pulses of continuously decreasing amplitude as it propagated along the coil. The initial elastic compressive pulse became sinusoidal with frequencies equal to the natural frequencies of the coil shortly after the initial disturbance. It was observed experimentally that there was always a component of the stress pulse which propagated along the helical coil at a velocity close to the bar velocity, (E/ρ)1/2. The theoretical analysis showed that there are two modes of wave propagation for the radial flexural and tangential deformation. The group velocity for the tangential deformation modes increases quickly from zero to the bar velocity as the wavelength decreases, especially at a large principal radius of the curvature. The group and the phase velocities for the twist and axial flexural deformation of the coil are also given.
On the Design of Oscillating Conveyers: Case of Simultaneous Normal and Longitudinal Oscillations
Authors: Morcos W. A.
Published: November 2010

The motion of a particle on an oscillating trough having both longitudinal and normal accelerations is studied in order to determine the optimum conditions for conveying material using this trough. The analysis is limited to the case where the particle does not lose contact with the trough at any point of the cycle; moreover, simplified hypothetical stepped acceleration cycles both in the longitudinal and normal directions of the trough are assumed. Advantage is taken from the normal acceleration to improve the performance of the oscillating trough. Guidelines for rational design are underlined.
Dimensional Parameters Influencing the Behavior of the Morrison Unsupported Area Seal
Authors: Pick R. J. , Burns D. J.
Published: November 2010

The deformation of a Morrison seal, used successfully at 56,000 lb/in.2 pressure, is determined using finite element techniques. This analysis is used as the basis for a discussion of the likely influences of change in seal geometry and operating pressure on seal behavior.
A Generalized Symbolic Notation for Mechanisms
Authors: Sheth P. N. , Uicker J. J.
Published: November 2010

Revisions of the Denavit-Hartenberg symbolic notation are proposed which extend its use to the entire domain of rigid link mechanisms. The extended notation provides a clear separation of the pair variables and the invariant parameters of a mechanism and thus provides a framework in which higher pairs can be systematically modeled. The new symbolism can be used directly with the existing matrix methods of kinematic analysis, and a numerical scheme is presented to reduce the task of data collection for these methods.
Minimization of Mechanism Oscillations Through Flywheel Tuning
Authors: Mahig J.
Published: November 2010

The magnitude of the perturbations to the steady-state rotation of most mechanisms is difficult to control with present methods. This paper shows an alternative method of reducing the magnitude of these oscillations. The analysis is carried out for a single slider-crank mechanism found in a tandem compressor. The analysis shows that an order of magnitude reduction in these oscillations is obtainable.
Generalized Cycloidal Motion
Authors: Spragg D. , Tesar D.
Published: November 2010

The motion coefficients and design methods for a wheel rolling externally or internally to a fixed wheel are given in Part I for linkage constraint satisfying up to 6 multiply separated positions. Part II provides design equations and graphical procedures in terms of the cubic circle and center point curves based on four symmetrical, multiply separated positions of the moving wheel. The important special case of an angular-circular transformer mechanism with constant mechanical advantage is treated in detail for four positions in Part III.
Minimum Error Synthesis of Space Mechanisms for the Generation of Constrained and Unconstrained Screws
Authors: Bagci Cemil
Published: November 2010

The RSRC space mechanism is synthesized to generate constrained and unconstrained screws of the form ψˆ(θ) = ψ0(θ) + εψ1(θ), where θ is the input parameter. A variational principle is used to determine the dimensions of the optimum mechanism, where the dual error in the generated screw is minimized at a discrete set of design positions whose number vary from three up to 24 for each component of the screw. Parameters of constraints are introduced to eliminate the equations of constraints. These parameters provide that the related constraining conditions are satisfied exactly. They are also used to generate the rotation interval and advance-to-return time ratios in quick-return mechanisms exactly. Seven numerical examples are given, which include the design of 4R plane mechanism to generate screw of zero pitch having odd order instantaneous dwell: RSRC mechanisms to generate screws of infinite pitch, constant pitch, and variable pitch having odd and even order instantaneous dwells; RSRC (or RSCR) doublecrank mechanism having dwell in the output rotation, and quick-return mechanism.
Design of Spatial Four-Link Crank-Rocker Mechanisms With or Without a Passive Constraint
Authors: Soni A. H. , Harrisberger Lee
Published: November 2010

An analytical method is presented for designing spatial four-link RCCC and RCRC crank-rocker mechanisms with optimum transmission angle. Mathematical relationships are derived for the computation of kinematic parameters of the designed mechanisms. These relationships are utilized to produce design charts.
Dilemmas for Business Education in the 1970’s
Authors: Day John S.
Published: November 2010

The paper discusses the dilemma facing management education as a result of the historical inability of both business and university to define adequately the role of the undergraduate business school as compared with the programs for educating professional business managers. In turn, the rapid development of doctoral programs in-business and the role they play in a total management education structure has further confused the educational picture. The several formal educational philosophies for business are discussed against the current managerial needs of business as stated by executives. The trend toward developing all-encompassing schools of management which consider business as only one of the functions of society about which management education should be provided is reviewed. From this analysis a general forecast of management education at the end of a ten-year period is made.
Strain Histories and Strain Distributions in a Cup Drawing Operation
Authors: Hsu T. C. , Dowle W. R. , Choi C. Y. , Lee P. K.
Published: November 2010

In the axisymmetrical cup drawing process, the principal directions of the strains are fixed with respect to the work material at every point and in every stage of the process; in other words, the strains are entirely coaxial ones—if the small strains in simple shear due to friction are ignored. For a properly chosen set of orthogonal space coordinates, therefore, the strains may be plotted in triangular coordinates. In such a coordinate system for strains, the loci for constant penetrations show the strain distributions, and those for constant initial radial positions show the strain histories. In these loci it is easy to see thinning and thickening, circumferential expansion and contraction, neck formation, variation in thickness, and other points of interest to the sheet metal engineer. Typical examples of strain histories and strain distributions in a cup drawing operation are shown. The method is applicable to any axisymmetrical sheet metal forming process.
The Dynamic Behavior of Surface Grinding: Part 2—Some Surface Grinding Tests
Authors: Thompson R. A.
Published: November 2010

In Part 1 of “The Dynamic Behavior of Surface Grinding”, a mathematical formulation for surface grinding was developed. The analysis led to several interesting results. As a part of a test program these results were evaluated. The tests were run on an especially equipped Jones-Shipman surface grinder. The machine was so designed and instrumented that the wear coefficients for both the wheel and workpiece as well as the dynamic character of surface grinding vibrations could be monitored for varying, controlled dynamic conditions. The tests substantiated the prediction of the mathematical theory. That is, for three different test conditions the ratio of the chatter frequency to the uncoupled system resonant frequency was found to agree with the theory. Also, a lobe precession test showed that the experimentally measured lobe precession rate was compatible with that predicted by the mathematical model.
Machinery Noise May Indicate Loss of Efficiency and Severity of Dynamic Stresses
Authors: Underwood A. C. , Graff W. J.
Published: November 2010

The general consensus about industrial noise is that it may have harmful effects on hearing, is at best a nuisance, and therefore should be absorbed or alleviated. Although not as universally recognized, noise represents an excellent medium for evaluating machine performance. Energy expended in unwanted machine motion or vibration results in noise and reduces the useful output of the machine. It is generally true that for uniform machine operation the condition of least noise corresponds to minimum loss in efficiency and minimum wear. Information from several industrial situations is presented in support of using noise data to help control the loss of efficiency and assess the severity of dynamic stresses in machine parts.
Spherical Acrylic Pressure Hulls for Undersea Exploration
Authors: Stachiw J. D.
Published: November 2010

The exploratory phase of the research program into the applicability of acrylic to the construction of spherical pressure hulls for undersea exploration has been completed. The findings show that acrylic pressure hulls are as reliable as hulls made from conventional materials if the viscoelastic temperature-dependent properties of the acrylic are taken into account during its design, fabrication, and operational service in the sea. The design data and information from the exploratory phase of the R & D program have been already applied to the fabrication of the NEMO Model 600 acrylic capsules with 66-in. OD × 61-in. ID for 600-ft-depth service.
Rarefied Gas Flow Through Long Square Tubes
Authors: Milligan Mancil W. , Patterson Kerry E.
Published: November 2010

A theoretical model has been developed for gas flow through long square tubes. The continuum differential equation is solved with noncontinuum slip boundary conditions and the “self-diffusion” or normal molecular transport effect is obtained by numerical integration. Specific flow rates as predicted by this theoretical model are compared with experimental data which were obtained using a 0.0985-in-square tube with argon as the test gas. In addition, a comparison is made using a “hydraulic radius” in the equation which Weber developed for rarefied gas flow through cylindrical tubes. Good agreement between theory and experiment give a high confidence level to the theoretical model.
The Joule-Thomson Effect in Compressed Liquid Water
Authors: Potter J. H.
Published: November 2010

This paper reports upon a continuing investigation into the Joule-Thomson effect in H2O. The values of μ are computed over a wide range of temperature and pressure using two independent formulations for the properties of compressed liquid water. Some hitherto unpublished experimental data are presented.
Electrochemical Grinding of Cylindrical Test Specimens
Authors: Knight T. W. , Barrow R. B. , Williams L. W. , Wells C. H.
Published: November 2010

The application of electrochemical grinding to the production of complex cylindrical test specimens of novel high-temperature materials is described. Design features and the performance of an ECM cylindrical grinding machine are presented. The process reduced the grinding time per specimen from several hours to a few minutes and resulted in comparable or superior surface finish and dimensional tolerances, as well as a marked reduction in wheel wear.
Drilling Riser Stress Measurements
Authors: Kopecky J. A.
Published: November 2010

Field measurements of drilling riser stresses during drilling operations have been made. The field-measured stresses are in agreement with those predicted by EPR’s pseudodynamic riser stress analysis computer program. The agreement between computed and measured values for both time-average stress and stress variations substantiates the validity of the computer program for predicting stress in the upper portion of the riser for the conditions of waves (less than 15 ft in height) and current (less than 1/3 kn) encountered during the data gathering sessions. Stress measurements were made on a drilling riser equipped, with an upper ball joint. It was confirmed that a properly operating upper ball joint is capable of providing a desirable reduction in the stress variation in the upper portions of the riser, thereby mitigating fatigue.