Showing papers on "Inertia published in 1994"

Tidal propagation in strongly convergent channels

Abstract: Simple first- and second-order analytic solutions, which diverge markedly from classical views of cooscillating tides, are derived for tidal propagation in strongly convergent channels. Theoretical predictions compare well with observations from typical examples of shallow, “funnel-shaped” tidal estuaries. A scaling of the governing equations appropriate to these channels indicates that at first order, gradients in cross-sectional area dominate velocity gradients in the continuity equation and the friction term dominates acceleration in the momentum equation. Finite amplitude effects, velocity gradients due to wave propagation, and local acceleration enter the equations at second order. Applying this scaling, the first-order governing equation becomes a first-order wave equation, which is inconsistent with the presence of a reflected wave. The solution is of constant amplitude and has a phase speed near the frictionless wave speed, like a classical progressive wave, yet velocity leads elevation by 90°, like a classical standing wave. The second-order solution at the dominant frequency is also a unidirectional wave; however, its amplitude is exponentially modulated. If inertia is finite and convergence is strong, amplitude increases along channel, whereas if inertia is weak and convergence is limited, amplitude decays. Compact solutions for second-order tidal harmonics quantify the partially canceling effects of (1) time variations in channel depth, which slow the propagation of low water, and (2) time variations in channel width, which slow the propagation of high water. Finally, it is suggested that phase speed, along-channel amplitude growth, and tidal harmonics in strongly convergent channels are all linked by morphodynamic feedback.

On Nonlinear Modes of Continuous Systems

Abstract: We use several methods to study the nonlinear modes of one-dimensional continuous systems with cubic inertia and geometric nonlinearities. Invariant manifold and perturbation methods applied to the discretized system and the method of multiple scales applied to the partial-differential equation and boundary conditions are discussed and their equivalence is demonstrated. The method of multiple scales is then applied directly to the partial-differential equation and boundary conditions governing several nonlinear beam problems.

Direct-drive manipulator for pen-based force display

Abstract: A pen-based direct-drive manipulator enables precision manipulation and force display of a control point within three degrees of freedom. The control point exhibits substantially no backlash, very low friction and very low inertia making it useful as a force display. The manipulator also has a very high force generation bandwidth allowing high frequency force components to be displayed. A parallel actuator structure controls motion over two degrees of freedom in a horizontal plane. The parallel structure is a redundant structure including three chains in parallel coupled at the control point. The redundant structure provides a uniform force capability throughout the manipulator workspace. A pair of rotational actuators rotate the parallel structure about an axis to approximate a linear motion along a third axis. The rotational actuators provide a third degree of freedom for the control point. Motion about the third axis is substantially decouple from motion about the horizontal plane.

Inertia as a zero-point-field Lorentz force

Abstract: Under the hypothesis that ordinary matter is ultimately made of subelementary constitutive primary charged entities or \"partons\" bound in the manner of traditional elementary Planck oscillators (a timehonored classical technique), it is shown that a heretofore uninvestigated Lorentz force (specifically, the magnetic component of the Lorentz force) arises in any accelerated reference frame from the interaction of the partons with the vacuum electromagnetic zero-point field (ZPF). Partons, though asymptotically free at the highest frequencies, are endowed with a sufficiently large \"bare mass\" to allow interactions with the ZPF at very high frequencies up to the Planck frequencies. This Lorentz force, though originating at the subelementary parton level, appears to produce an opposition to the acceleration of material objects at a macroscopic level having the correct characteristics to account for the property of inertia. We thus propose the interpretation that inertia is an electromagnetic resistance arising from the known spectral distortion of the ZPF in accelerated frames. The proposed concept also suggests a physically rigorous version of Mach's principle. Moreover, some preliminary independent corroboration is suggested for ideas proposed by Sakharov (Dokl. Akad. Nauk SSSR 177, 70 (1968) [Sov. Phys. Dokl. 12, 1040 (1968)J) and further explored by one of us [H. E. Puthoff, Phys. Rev. A 39,2333 (1989)] concerning a ZPF-based model of Newtonian gravity, and for the equivalence of inertial and gravitational mass as dictated by the principle of equivalence.

Basic consideration of vibration suppression and disturbance rejection control of multi-inertia system using SFLAC (state feedback and load acceleration control)

Abstract: SFLAC (state feedback and load acceleration control) is proposed for vibration suppression and disturbance rejection control of a multi-inertia system A multi-inertia system is the model of a steel rolling mill, a flexible arm, a large-scale space structure, etc, and its control will be an important problem in the future of motion control The main idea of SFLAC is to control the load acceleration which can be estimated by the state observer including the disturbance estimation A simple PI speed controller and SFLAC based on the reduction models using two and three inertia moments are designed The effectiveness of SFLAC is demonstrated showing some simulation results >

The inertial migration of non-neutrally buoyant spherical particles in two-dimensional shear flows

Abstract: The inertial migration of a small rigid spherical particle, suspended in a fluid flowing between two plane boundaries, is investigated theoretically to find the effect on the lateral motion. The channel Reynolds number is of order unity and thus both boundary-induced and Oseen-like inertial migration effects are important. The particle Reynolds number is small but non-zero, and singular perturbation techniques are used to calculate the component of the migration velocity which is directed perpendicular to the boundaries of the channel. The particle is non-neutrally buoyant and thus its buoyancy-induced motion may be either parallel or perpendicular to the channel boundaries, depending on the channel alignment. When the buoyancy results in motion perpendicular to the channel boundaries, the inertial migration is a first-order correction to the magnitude of this lateral motion, which significantly increases near to the boundaries. When the buoyancy produces motion parallel with the channel boundaries, the inertial migration gives the zeroth-order lateral motion either towards or away from the boundaries. It is found that those particles which have a velocity exceeding the undisturbed shear flow will migrate towards the boundaries, whereas those with velocities less than the undisturbed flow migrate towards the channel centreline. This calculation is of practical importance for various chemical engineering devices in which particles must be filtered or separated. It is useful to calculate the forces on a particle moving near to a boundary, through a shear flow. This study may also explain certain migration effects of bubbles and crystals suspended in molten rock flow flowing through volcanic conduits.

Distortions of inertia waves in a rotating fluid cylinder forced near its fundamental mode resonance

Abstract: A series of experimental observations is presented of a flow in which inertial oscillations are excited. The homogeneous fluid is contained in a completely filled right circular cylinder. The cylinder is spun about its axis of symmetry and a small ‘forced precession’ (or coning motion) is impulsively started. The flow is visualized by an electrolytic dyeline method. The mathematical problem for linear inviscid inertial oscillations in this system, although ill-posed in general, admits a solution in terms of wave modes for the specific boundary conditions considered here. The experiments show that while this linear inviscid theory provides some facility for predicting the flow structure at early times, the flow rapidly and irreversibly distorts away from the predicted form. This behaviour is seen as a precursor to some of the more dramatic breakdowns described by previous authors, and it may be pertinent to an understanding of the breakdowns reported in experiments on elliptical flow instabilities.

An active vertical-direction gravity compensation system

Abstract: To perform simulations of partial or microgravity environments on Earth requires some method of compensation for the Earth's gravitational field. This paper discusses an active compensation system that modulates the tension in a counterweight support cable in order to minimize state deviation between the compensated body and the ideal weightless body. The system effectively compensates for inertial effects of the counterweight mass, viscous damping of all pulleys, and static friction in all parts of the gravity compensation (GC) system using a hybrid PI (proportional plus integral)/fuzzy control algorithm. The dynamic compensation of inertia and viscous damping is performed by PI control, while static friction compensation is performed by the fuzzy system. The system provides a very precise gravity compensation force, and is capable of nonconstant gravity force compensation in the case that the payload mass is not constant. >

Schaum's Outline of Theory and Problems of Strength of Materials

Abstract: Tension and compression statically indeterminate force systems - tension and compression thin-walled pressure vessels direct shear stresses torsion shearing force and bending moment centroids, moments of inertia and products of inertia of plane areas stresses in beams elastic deflection of beams - double-integration method elastic deflection of beams - method of singularity functions statically indeterminate elastic beams special topics in elastic beam theory plastic deformation of beams columns strain energy methods combined stresses members subject to combined loadings - theories of failure.

Dynamometer for simulating the inertial and road load forces encountered by motor vehicles and method

Abstract: A chassis dynamometer including a frame (33), a set of rolls (14, 18) for engaging the wheels (12) of a motor vehicle (10) and an eddy current brake/inertia simulating unit (30) with a ferrous metal rotor wheel rotatably mounted on the frame and a plurality of stationary field coils. The rotor wheel has a rotational mass within the range 70 % to 90 % of the base or minimum inertia of the dynamometer. A force transducer (34) and a speed encoder (36) provide a measure of the force applied to the roll by the wheel and the speed of the roll, respectively. A controller (38), in response to the roll speed and force applied to the roll, controls the current to the field coils in accordance with a selected simulated inertia and road load for the vehicle.

A consistent finite element formulation for non‐linear dynamic analysis of planar beam

Abstract: SUMMARY A co-rotational finite element formulation for the dynamic analysis of planar Euler beam is presented. Both the internal nodal forces due to deformation and the inertia nodal forces are systematically derived by consistent linearization of the fully geometrically non-linear beam theory using the d'Almbert principle and the virtual work principle. Due to the consideration of the exact kinematics of Euler beam, some velocity coupling terms are obtained in the inertia nodal fonxs. An incremental-iterative method based on the Newmark direct integration method and the Newton-Raphson method is employed here for the solution of the non-linear dynamic equilibrium equations. Numerical examples are presented to investigate the effect of the velocity coupling terms on the dynamic response of the beam structures.

A General Approach to Stress Stiffening Effects on Flexible Multibody Dynamic Systems

Abstract: This paper presents a general way of including stress stiffening effects in the dynamic simulation of flexible multibody systems that undergo large overall motion accompanied by small elastic deformation. Stress stiffening terms are derived from the internal virtual work that includes nonlinear terms of the strain-displacement relationship and reference stresses induced by existing loads before deformation. The resultant stress stiffness matrix for a flexible body is obtained through quasi-static structural analyses by applying D'Alembert inertia, joint reaction, and other applied loads. The DAIembert inertia loads arising from gross motion of the body reference frame are expressed as a combination of space-dependent terms and 12 sets of time-dependent terms. An iterative method is proposed to solve the resultant system equations of motion. Examples are presented to illustrate the method and procedures proposed.

Ultrasonic diagnostic system

Abstract: PURPOSE: To automatically set a region of interest(ROI) suitable for the area of an atrium, etc., in an ultrasonic diagnostic system. CONSTITUTION: The contour point detecting part 42 of an automatic ROI setting part 40 detects the contour point of a bloodstream area along each ultrasonic beam of sector scan. A centroid coordinate arithmetic part 44 finds the centroid of contour point groups from the coordinates of detected contour points. A moment of inertia arithmetic part 46 performs the coordinate transformation of the coordinate of each contour point to a centroid coordinate system setting the centroid as an origin, and finds the moment of inertia and products of inertia of the contour point group around each coordinate axis. An inertia main spindle arithmetic part 48 finds the inclination of an inertia main spindle for the centroid coordinate system based on the moment of inertia and the products of inertia. A ROI arithmetic part 50 finds the inertia main spindle based on the inclination, and decides the length of the major axis and minor axis of an elliptical ROI from the coordinate of the contour point in the neighborhood of the inertia main spindle, and sets the ROI so as to align the major axis and the minor axis with each inertia main spindle.

Dynamics Decomposition for Stewart Platforms

Abstract: This paper shows that special features of the Stewart platform can lead to the decomposition of the moving plate and the legs in the dynamic analysis. Formulas for evaluating, separately, the driving forces needed for the movement of the legs are developed for studying the combined inertia effect of all the leg rotations in a Stewart platform. The proposed formulation is easy to implement for Stewart platforms with nonnegligible leg inertia.

Atom interferometry with arbitrary laser configurations : exact phase shift for potentials including inertia and gravitation

Abstract: We ,tudy in a general treaimeni the influence oi a cla,, of perturbation~ acting on the atom, ot an atomic interferometer. An exact expre,,ion for the re,ulting ;hift of the interference pattern I, given for an arbitrary number of la;er zone; with travelling or ~tanding wave~. The a;;umption made i~ that the two-level model is appropriate for the description of atom~ and that the perturbation~ can be neglected in the la~er zone~. As an important application we calculate the influence of acceleration, rotation, and ~pace-time curvature on the Ramsey interferometer and the atomic fountain. The me»urability of the re~pective pha~e ~hift~ i~ di~cu~sed.

Analysis of Linear Encroachment in Two-Immiscible Fluid Systems in a Porous Medium

Abstract: The flow of two immiscible fluids in a porous medium was analyzed accounting for boundary and inertia effects. This problem was first solved by Muskat using Darcy's equation for fluid flow in a saturated porous medium. In the present analysis the boundary and inertia effects have been included to predict the movement of the interfacial front that is formed as one fluid displaces the other. In the present work a theoretical study that accounts for the boundary and inertia effects in predicting the movement of the interface for linear encroachment in two immiscible fluid system in a porous material is presented for the first time. The results of the present study when compared with the Muskat's model show that consideration of the boundary and inertia effects becomes important for low value of mobility ratio ([epsilon] 1.0 [times] 10[sup [minus]10] m[sup 2]).

Hydraulic control system for an automatic transmission

Abstract: A controller of an automatic transmission provides gear changes with optimum gear change characteristics under any traveling conditions. The controller of the automatic transmission of the present invention includes an input torque detector for determining input torque to the transmission, an inertia torque estimator for estimating an inertia torque corresponding to the rate of change of rotary speed of a rotary member during a gear change, input torque corrector for calculating a required operating torque by adding the input torque and the inertia torque and an operating pressure controller for controlling operating pressure to correspond to the required operating torque. The operating pressure corresponding to the necessary engagement torque is supplied to a hydraulic servo, to effect a gear change, irrespective throttle opening and driving speed and irrespective of whether the gear change is made step by step or jumped.

Optimal trajectories and force distribution for cooperating arms

Abstract: The optimization of trajectories and actuator torques for a dual arm manipulation system is considered. Given the starting and final configurations, we find the trajectories that minimize: (a) the integral of the norm of the vector of derivatives of the actuator forces; and (b) the integral of the norm of the actuator forces. In this way both kinematic and actuator redundancy are resolved. The optimization problem reduces to solving a two-point boundary valve problem for coupled, nonlinear differential equations. The effect of different parameters such as preload and inertia are investigated and the results are compared with those obtained using other well-known cost functions. >

2-Inertia System Control using Resonance Ratio Control and Manabe Polynomials

Abstract: Vibration suppression and disturbance rejection controls are important issues in recent steel rolling mill systems due to the application of high response Ac drive system. Various methods have been already proposed, for example, simple acceleration feedback, state feedback and H∞ control, etc.In this paper, I will propose a novel controller for a 2-inertia system which is the simplest model of the rolling mill system, where the roll is coupled with the motor by a long shaft. By realizing “Manabe Polynomials” using the “resonance ratio control” based on the disturbance observer, the 2-inertia system can be controlled quite effectively. Moreover, the order of the proposed controller is only 2.I will show some simulation results to demonstrate that the proposed controller suppresses the torsional vibration and the disturbance torque effectively in various 2-inertia systems with a wide range of the ratio between the motor and load inertia moments.