A Study of the Transient Pitching Oscillations of a Ship

1959 ◽  
Vol 3 (01) ◽  
pp. 22-30
Author(s):  
Paul Golovato
Keyword(s):  
Vertical Plane ◽  
The Body ◽  
Plane Symmetry ◽  
Moment Equations ◽  
Longitudinal Modes ◽  
Second Order Differential Equations ◽  
Stability Derivatives ◽  
Submerged Body ◽  
Constant Coefficients ◽  
Instantaneous Values

The motions of a deeply submerged body with vertical-plane symmetry, e.g., a submarine, are commonly treated in a manner completely analogous to that used for aircraft motions. The body is assumed to have its lateral and longitudinal modes uncoupled. The small motions are described by a set of force-and-moment equations which are linear, second-order differential equations with constant coefficients. These proportionality constants ("stability derivatives") relate the forces and moments to the instantaneous values of the position, velocity, and acceleration of the body. They are generally experimentally determined in the wind or water tunnel, and the controlled or uncontrolled motions of the craft are predicted based thereon.

ANALYSIS OF THE CREW PART OF THE LOCOMOTIVE TEM23 AND PROPOSALS FOR ELIMINATION OF DISADVANTAGES

2020 ◽  
Author(s):  
Dmitriy Antipin ◽  
Vladimir Vorobev ◽  
Denis Bondarenko ◽  
Gennadiy Petrov
Keyword(s):  
Vertical Plane ◽  
The Body ◽  
Diesel Locomotive ◽  
Design Features ◽  
Bogie Frame ◽  
Spring Suspension ◽  
In Series

The analysis of the design features of the bogie of the TEM23 shunting diesel locomotive is carried out. In the process of analysis, the directions of its improvement are determined. It is proposed to rotate the bogie frame in the vertical plane by reducing the body supports to two and using a pivot with low lowering, equip the bogies with pneumatic spring suspension in the form of two corrugations installed in series with shortened suspension springs. The proposed options for improving the undercarriage of a diesel locomotive will increase the competitiveness of products and reduce costs

The vestibuloocular reflex of the adult flatfish. I. Oculomotor organization

1985 ◽  
Vol 54 (4) ◽  
pp. 887-899 ◽  
Author(s):  
W. Graf ◽  
R. Baker
Keyword(s):  
Eye Movements ◽  
Motor Neuron ◽  
Motor Neurons ◽  
Vertical Plane ◽  
Extraocular Muscles ◽  
The Body ◽  
Medial Rectus ◽  
Inferior Rectus ◽  
Abducens Nucleus ◽  
Eye Muscles

The flatfish species constitute a natural paradigm for investigating adaptive changes in the vertebrate central nervous system. During metamorphosis all species of flatfish experience a 90 degree change in orientation between their vestibular and extraocular coordinate axes. As a result, the optic axes of both eyes maintain their orientation with respect to earth horizontal, but the horizontal semicircular canals become oriented vertically. Since the flatfish propels its body with the same swimming movements when referenced to the body as a normal fish, the horizontal canals are exposed to identical accelerations, but in the flatfish these accelerations occur in a vertical plane. The appropriate compensatory eye movements are simultaneous rotations of both eyes forward or backward (i.e., parallel), in contrast to the symmetric eye movements in upright fish (i.e., one eye moves forward, the other backward). Therefore, changes in the extraocular muscle arrangement and/or the neuronal connectivity are required. This study describes the peripheral and central oculomotor organization in the adult winter flounder, Pseudopleuronectes americanus. At the level of the peripheral oculomotor apparatus, the sizes of the horizontal extraocular muscles (lateral and medial rectus) were considerably smaller than those of the vertical eye muscles, as quantified by fiber counts and area measurements of cross sections of individual muscles. However, the spatial orientations and the kinematic characteristics of all six extraocular muscles were not different from those described in comparable lateral-eyed animals. There were no detectable asymmetries between the left and the right eye. Central oculomotor organization was investigated by extracellular horseradish peroxidase injections into individual eye muscles. Commonly described distributions of extraocular motor neurons in the oculomotor, trochlear, and abducens nuclei were found. These motor neuron pools consisted of two contralateral (superior rectus and superior oblique) and four ipsilateral populations (inferior oblique, inferior rectus, medial rectus, and lateral rectus). The labeled cells formed distinct motor neuron populations, which overlapped little. As expected, the numbers of labeled motoneurons differed in horizontal and vertical eye movers. The numerical difference was especially prominent in comparing the abducens nucleus with one of the vertical recti subdivisions. Nevertheless, there was bilateral symmetry between the motoneurons projecting to the left and right eyes.(ABSTRACT TRUNCATED AT 400 WORDS)

Interdisciplinary approach to the treatment of rare visual illusions in a veteran

2021 ◽  
Vol 14 (1) ◽  
pp. e238362
Author(s):  
Michelle Zeller ◽  
Wilhelmina Stamps
Keyword(s):  
Vertical Plane ◽  
Interdisciplinary Approach ◽  
Interdisciplinary Team ◽  
Visual Illusions ◽  
The Body ◽  
Hip Surgery ◽  
Coronal Plane ◽  
Team Approach ◽  
Physical Medicine ◽  
Rare Form

Upside-down reversal of vision (UDRV) is a rare form of metamorphopsia, or visual illusions that can distort the size, shape or inclination of objects. This phenomenon is paroxysmal and transient in nature, with patients reporting a sudden inversion of vision in the coronal plane, which typically remains for seconds or minutes, though occasionally persists for hours or days, before returning to normal. Distorted egocentric orientation (ie, the patient perceives the body to be tilted away from the vertical plane) is even more rare as a co-occurring phenomenon. To the best of our knowledge, this is the first reported case of a veteran who presented with UDRV and distorted egocentric orientation during hospitalisation on an inpatient physical medicine and rehabilitation setting following an elective hip surgery. This case serves not only to document the presence of rare visual illusions, but also illustrates the importance and value of an interdisciplinary team approach.

A System to Measure Turbulent Lengthscales on Submerged Bodies of Revolution

2017 ◽  
Author(s):  
Christopher J. Chesnakas ◽  
Daniel R. Cadel
Keyword(s):  
Laser Doppler Velocimetry ◽  
Arrival Time ◽  
Noise Removal ◽  
The Body ◽  
Doppler Velocimetry ◽  
Body Of Revolution ◽  
Sampled Data ◽  
Bodies Of Revolution ◽  
Submerged Body ◽  
Cross Correlations

A system has been developed to measure the turbulent lengthscales in the flow about a submerged body of revolution. The system consists of two Laser Doppler Velocimetry (LDV) probes mounted inside the body of revolution with the beams projected outside of the body through conformal windows. The measurement volumes of the two probes can be independently positioned within a plane perpendicular to the body axis. The probes are used to measure velocity time series at various spacings in the flow field. Auto- and cross-correlations are computed for each measurement pair, from which integral lengthscales are then found. Measurements are compared to canonical data from a turbulent free shear jet. In this paper, the system is described and its theory of operation detailed. Methods of computing the velocity correlations from the random-arrival-time LDV measurements are presented, and a new noise-removal scheme for non-uniformly sampled data is introduced. Six methods for calculating the integral lengthscale from autocorrelation data are reviewed, and the results discussed for the present jet data measured with LDV.

Many-legged maneuverability: dynamics of turning in hexapods

1999 ◽  
Vol 202 (12) ◽  
pp. 1603-1623 ◽  
Author(s):  
D.L. Jindrich ◽  
R.J. Full
Keyword(s):  
Horizontal Plane ◽  
Center Of Mass ◽  
Vertical Plane ◽  
Force Production ◽  
The Body ◽  
Mean Velocity ◽  
Blaberus Discoidalis ◽  
Body Design ◽  
Reaction Forces ◽  
Straight Ahead

Remarkable similarities in the vertical plane of forward motion exist among diverse legged runners. The effect of differences in posture may be reflected instead in maneuverability occurring in the horizontal plane. The maneuver we selected was turning during rapid running by the cockroach Blaberus discoidalis, a sprawled-postured arthropod. Executing a turn successfully involves at least two requirements. The animal's mean heading (the direction of the mean velocity vector of the center of mass) must be deflected, and the animal's body must rotate to keep the body axis aligned with the heading. We used two-dimensional kinematics to estimate net forces and rotational torques, and a photoelastic technique to estimate single-leg ground-reaction forces during turning. Stride frequencies and duty factors did not differ among legs during turning. The inside legs ended their steps closer to the body than during straight-ahead running, suggesting that they contributed to turning the body. However, the inside legs did not contribute forces or torques to turning the body, but actively pushed against the turn. Legs farther from the center of rotation on the outside of the turn contributed the majority of force and torque impulse which caused the body to turn. The dynamics of turning could not be predicted from kinematic measurements alone. To interpret the single-leg forces observed during turning, we have developed a general model that relates leg force production and leg position to turning performance. The model predicts that all legs could turn the body. Front legs can contribute most effectively to turning by producing forces nearly perpendicular to the heading, whereas middle and hind legs must produce additional force parallel to the heading. The force production necessary to turn required only minor alterations in the force hexapods generate during dynamically stable, straight-ahead locomotion. A consideration of maneuverability in the horizontal plane revealed that a sprawled-postured, hexapodal body design may provide exceptional performance with simplified control.

Nonlinear Aspects of Subcritical Shallow-Water Flow Past Two-Dimensional Obstructions

1978 ◽  
Vol 22 (04) ◽  
pp. 203-211
Author(s):  
Nils Salvesen ◽  
C. von Kerczek
Keyword(s):  
Free Surface ◽  
Shallow Water ◽  
Flow Problem ◽  
Free Stream ◽  
The Body ◽  
Two Dimensional ◽  
Third Order ◽  
Submerged Body ◽  
The Mean ◽  
The Waves

Some nonlinear aspects of the two-dimensional problem of a submerged body moving with constant speed in otherwise undisturbed water of uniform depth are considered. It is shown that a theory of Benjamin which predicts a uniform rise of the free surface ahead of the body and the lowering of the mean level of the waves behind it agrees well with experimental data. The local steady-flow problem is solved by a numerical method which satisfies the exact free-surface conditions. Third-order perturbation formulas for the downstream free waves are also presented. It is found that in sufficiently shallow water, the wavelength increases with increasing disturbance strength for fixed values of the free-stream-Froude number. This is opposite to the deepwater case where the wavelength decreases with increasing disturbance strength.

scholarly journals Stability Characteristics of Wing Span and Sweep Morphing for Small Unmanned Air Vehicle: A Mathematical Analysis

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Hafiz Muhammad Umer ◽  
Adnan Maqsood ◽  
Rizwan Riaz ◽  
Shuaib Salamat
Keyword(s):  
Equations Of Motion ◽  
Small Scale ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Flight Stability ◽  
Longitudinal Modes ◽  
Flight Vehicles ◽  
Stability Derivatives ◽  
Wing Sweep ◽  
Wing Morphing

Morphing aircraft are the flight vehicles that can reconfigure their shape during the flight in order to achieve superior flight performance. However, this promising technology poses cross-disciplinary challenges that encourage widespread design possibilities. This research aims to investigate the flight dynamic characteristics of various morphed wing configurations that can be incorporated in small-scale UAVs. The objective of this study was to analyze the effects of in-flight wing sweep and wingspan morphing on aerodynamic and flight stability characteristics. Longitudinal, lateral, and directional characteristics were evaluated using linearized equations of motion. An open-source code based on Vortex Lattice Method (VLM) assuming quasi-steady flow was used for this purpose. Trim points were identified for a range of angles of attack in prestall regime. The aerodynamic coefficients and flight stability derivatives were compared for the aforementioned morphing schemes with a fixed-wing counterpart. The results indicated that wingspan morphing is better than wing sweep morphing to harness better aerodynamic advantages with favorable flight stability characteristics. However, extension in wingspan beyond certain limits jeopardizes the advantages. Dynamically, wingspan and sweep morphing schemes behave in an exactly opposite way for longitudinal modes, whereas lateral-directional dynamics act in the same fashion for both morphing schemes. The current study provided a baseline to explore the advanced flight dynamic aspects of employed wing morphing schemes.

scholarly journals The Dynamical Behavior of a Rigid Body Relative Equilibrium Position

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
T. S. Amer
Keyword(s):  
Rigid Body ◽  
Degrees Of Freedom ◽  
Numerical Solutions ◽  
Equations Of Motion ◽  
Relative Equilibrium ◽  
Dynamical Behavior ◽  
Vertical Plane ◽  
The Body ◽  
Physical Parameters ◽  
Pendulum Model

In this paper, we will focus on the dynamical behavior of a rigid body suspended on an elastic spring as a pendulum model with three degrees of freedom. It is assumed that the body moves in a rotating vertical plane uniformly with an arbitrary angular velocity. The relative periodic motions of this model are considered. The governing equations of motion are obtained using Lagrange’s equations and represent a nonlinear system of second-order differential equations that can be solved in terms of generalized coordinates. The numerical solutions are investigated using the fourth-order Runge-Kutta algorithms through Matlab packages. These solutions are represented graphically in order to describe and discuss the behavior of the body at any instant for different values of the physical parameters of the body. The obtained results have been discussed and compared with some previous published works. Some concluding remarks have been presented at the end of this work. The importance of this work is due to its numerous applications in life such as the vibrations that occur in buildings and structures.

scholarly journals PHOTOTROPISM OF DIXIPPUS MOROSUS

1928 ◽  
Vol 11 (3) ◽  
pp. 297-300 ◽  
Author(s):  
N. Yagi
Keyword(s):  
Vertical Plane ◽  
The Body ◽  
Body Axis ◽  
Stimulation Of

1. Local differences in the effects of stimulation of parts of the eye by light are expressed in Dixippus morosus by differential circus movements. 2. The angle of inclination of the body axis toward one source of light when the animal is on a vertical plane with light from one side is inversely proportional to the logarithm of the intensity of the light.

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