Motion Distortion Research Articles

Cam system design: The dynamic synthesis and analysis of the one degree of freedom model

The dynamic synthesis of modeled cam systems is used to validate a number of fundamental design rules of thumb pertaining to classification, motion specification, motion distortion due to off-speed operation, and reduction of system potential for growth of wear. Proper use of these elementary design rules makes complex analysis procedures unnecessary.

The Design of Modeled Cam Systems—Part II: Minimization of Motion Distortion Due to Modeling Errors

The dynamic synthesis procedures of Part I are reinforced by qualitative and quantitative results from analysis. The principal concern is for the motion distortion which results from off-speed operation and from errors in the model parameters. Elementary direct means for calculating errors due to transient vibrations and inertia force variations are given which eliminate the need for complex analysis procedures. Rules of thumb are developed which enable the designer to choose system parameters to minimize motion distortion and inhibit growth of wear and consequent noise.

Collisional depolarization of 2P states of alkalies on weak spin—orbital coupling

Depolarization, relaxation and intramultiplet mixing cross sections for Na *( 2P) in collision with He are calculated using the matching approximation; the distortion of relative motion of partners in the fields of 2Σ and 2Π terms are taken into account. The theory provides an interpretation of inelastic events which is consistent both with experimental data on cross sections and the general pattern of adiabatic potentials.

Left ventricular asynergy

Left ventricular asynergy is a localized morphologic disturbance of ventricular wall motion which disrupts the normal coordinated pattern of left ventricular contraction. Several distinct types of asynergy are seen: akinesis, or local absence of wall motion; dyskinesis, or local expansile or paradoxical wall motion; asyneresis, or geometric distortion or inequality of wall motion; asynchrony, or a disturbed temporal sequence of contraction. These localized abnormalities are closely related to the anatomic, electrocardiographic, and biochemical zones of ischemia in coronary heart disease and are also seen in cardiomyopathy, rheumatic heart disease and other conditions that cause ventricular hypertrophy, and with ectopic excitation and activation of the left ventricle. Although often associated with clinical and, more frequently, laboratory evidence of cardiac failure, asynergy not uncommonly occurs in the absence of cardiac enlargement. Such morphologic abnormalities provide a functional basis for the hemodynamic disturbances seen in coronary heart disease. Thus, ventricular asynergy represents a dynamic abnormality appreciated only in life as a derangement of the integrated function of the left ventricle and represents an important cause of cardiac failure.

Implications of left ventricular asynergy

Ventricular asynergy, local disturbances in ventricular wall motion which disrupt the normal coordinated pattern of left ventricular contraction, is described in a group of patients. There are four distinct types of asynergy: (1) akinesis, or local absence of wall motion; (2) dyskinesis, or local expansile or paradoxical wall motion; (3) asyneresis, or geometric distortion or inequality of wall motion; and (4) asynchrony, or a disturbed temporal sequence of contraction. These local abnormalities are closely related to anatomic, electrocardiographic and biochemical zones of ischemia in coronary heart disease and are also seen in cardiomyopathy and with ectopic excitation and activation of the left ventricle. Although often associated with clinical and more frequently, laboratory evidence of cardiac failure, asynergy sometimes occurs in the absence of cardiac enlargement. Such morphologic abnormalities provide a functional basis for the hemodynamic disturbances seen in coronary heart disease and so poorly explained at postmortem examination. Thus, ventricular asynergy represents a dynamic abnormality appreciated only in life as a derangement of the integrated function of the left ventricle and represents an important cause of cardiac failure.

The growth of Taylor vortices in flow between rotating cylinders

In flow between concentric rotating circular cylinders, it was shown by Taylor (1923) that instability may occur in the form of toroidal vortices spaced regularly along the axis. When the vortex motion occurs additional torque is required to keep the cylinders in motion at given speeds. Stuart (1958) used an energy-balance method, in the case when the annular gap is small compared with the radius, to estimate the additional torque and the associated finite amplitude attained by the vortices. He included the effect of distortion of the mean motion, but ignored the generation of harmonics of the fundamental mode and the distortion of the velocity associated with the fundamental mode. It is now known that these are not valid mathematical approximations and a rigorous perturbation expansion is developed here to remedy the deficiency. The analysis is valid for any gap width and any angular speeds of the containing cylinders, but requires the amplification rate of the disturbance to be small.Numerical results using a digital computer are obtained for the shape and amplitude of the vortices in three cases: (i) when the outer cylinder has twice the radius of the inner one and is kept at rest, (ii) when the gap is small and the cylinders rotate with nearly the same speeds, and (iii) when the gap is small and the outer cylinder is kept at rest. The equilibrium amplitude obtained in the last case is substantially the same as that found by Stuart.The results for cases (i) and (iii) give close agreement with the experimental values obtained by Taylor (1936) and Donnelly (1958) for the torque required to keep the inner cylinder rotating with constant speed while the outer one is at rest, for a certain range of speeds. In the small-gap problem it is shown that the equilibrium amplitude is almost proportional to 1 − m, where m is the ratio of the angular speeds of the outer and inner cylinders.