Regular and Irregular Motion

2020 ◽  
pp. 27-53
Author(s):  
M. V. Berry
Keyword(s):  
Irregular Motion

Epitasis and Anesis in Aristotle, De caelo 2.6

Phronesis ◽  
2016 ◽  
Vol 61 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Stephen E. Kidd
Keyword(s):  
The Other ◽  
Irregular Motion ◽  
Acceleration And Deceleration ◽  
The One

De caelo 2.6 describes irregular motion differently from the discussion at Physics 5.4. The desire to make the one discussion congrue with the other has strained interpretation of the De caelo passage. Aristotle provides a theory of irregular motion that is tripartite and the passage ought to be interpreted in such a way as to explain this tripartite motion. Akmē is not a ‘top speed’ as it is generally translated, but a point in an object’s motion when epitasis must become anesis. Although the terms epitasis and anesis cover ‘acceleration’ and ‘deceleration’ they cannot be reduced to them.

Motion Detectors

2014 ◽  
pp. 290-310
Keyword(s):  
Visual Motion ◽  
Motion Sensors ◽  
Motion Detector ◽  
Security Systems ◽  
Intelligent Algorithms ◽  
Physical Motion ◽  
Security Personnel ◽  
Irregular Motion ◽  
Detection Capabilities ◽  
Motion Detectors

The first five sections represent the foundation and offer various intelligent algorithms that are the basics for motion detectors and their realization. There are two classes of security system alarm triggers: physical motion sensor and visual motion sensors. Both analog motion detectors and digital motion detectors belong to the group of visual motion sensors. Digital motion detector systems should differentiate between activities that are acceptable and those that breach security. When security-breaching acts occur, the system should identify the individuals and instruct security personnel what to do. Motion detectors can surveil, detect, and assess, as well as analyze information and distribute information to security personnel. Motion detector systems drastically reduce the load of footage that guards must watch for a long period of time. Automated motion detectors are now a standard for serious medium to large security installations; they are necessary for high detection capabilities. All security systems must have an alarming device to signal the guard of irregular motion in a scene, even systems that have a tiny or huge number of cameras.

scholarly journals Chaotic Behaviour Investigation of a Front Opposed-Hemispherical Spiral-Grooved Air Bearing System

2017 ◽  
Vol 2017 ◽  
pp. 1-18
Author(s):  
Cheng-Chi Wang
Keyword(s):  
High Speed ◽  
Critical Speed ◽  
Large Scale ◽  
Air Bearing ◽  
Severe Damage ◽  
Design Problems ◽  
Irregular Motion ◽  
Transformation Methods ◽  
Bearing Number ◽  
Bearing System

In recent years, spiral-grooved air bearing systems have attracted much attention and are especially useful in precision instruments and machines with spindles that rotate at high speed. Load support can be multidirectional and this type of bearing can also be very rigid. Studies show that some of the design problems encountered are dynamic and include critical speed, nonlinearity, gas film pressure, unbalanced rotors, and even poor design, all of which can result in the generation of chaotic aperiodic motion and instability under certain conditions. Such irregular motion on a large scale can cause severe damage to a machine or instrument. Therefore, understanding the conditions under which aperiodic behaviour and vibration arise is crucial for prevention. In this study, numerical analysis, including the Finite Difference and Differential Transformation Methods, is used to study these effects in detail in a front opposed-hemispherical spiral-grooved air bearing system. It was found that different rotor masses and bearing number could cause undesirable behaviour including periodic, subperiodic, quasi-periodic, and chaotic motion. The results obtained in this study can be used as a basis for future bearing system design and the prevention of instability.

scholarly journals RePLaT-Chaos: A Simple Educational Application to Discover the Chaotic Nature of Atmospheric Advection

Atmosphere ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 29
Author(s):  
Tímea Haszpra
Keyword(s):  
Large Scale ◽  
Volcanic Ash ◽  
Initial Conditions ◽  
Industrial Accidents ◽  
Fractal Structures ◽  
Atmospheric Pollutant ◽  
Folded Structure ◽  
Exponential Stretching ◽  
Irregular Motion ◽  
Chaotic Nature

Large-scale atmospheric pollutant spreading via volcano eruptions and industrial accidents may have serious effects on our life. However, many students and non-experts are generally not aware of the fact that pollutant clouds do not disperse in the atmosphere like dye blobs on clothes. Rather, an initially compact pollutant cloud soon becomes strongly stretched with filamentary and folded structure. This is the result of the chaotic behaviour of advection of pollutants in 3-D flows, i.e., the advection dynamics of pollutants shows the typical characteristics such as sensitivity to the initial conditions, irregular motion, and complicated but well-organized (fractal) structures. This study presents possible applications of a software called RePLaT-Chaos by means of which the characteristics of the long-range atmospheric spreading of volcanic ash clouds and other pollutants can be investigated in an easy and interactive way. This application is also a suitable tool for studying the chaotic features of the advection and determines two quantities which describe the chaoticity of the advection processes: the stretching rate quantifies the strength of the exponential stretching of pollutant clouds; and the escape rate characterizes the rate of the rapidity by which the settling particles of a pollutant cloud leave the atmosphere.

scholarly journals Planetary Theories in Sanskrit Astronomical Texts

1987 ◽  
Vol 91 ◽  
pp. 113-124
Author(s):  
S.N. Sen
Keyword(s):  
Day Length ◽  
The Sun ◽  
The Moon ◽  
Irregular Motion ◽  
Correct Ratio ◽  
The Times ◽  
Planetary Theories

The origin and development of planetary theories in India are still imperfectly understood. It is generally believed that fullfledged planetary theories capable of predicting the true positions of the Sun, Moon and Star-planets appeared in India along with the emergence of the siddhāntic astronomical literature. Before this siddhāntic astronomy there had existed the Vedāṅga Jyotiṣa of Lagadha, prepared around circa 400 B.C. in the Sūtra period more or less on the basis of astronomical elements developed in the time of the Saṃhitās and the Brāhmaṇas. This Jyotiṣa propounded a luni-solar calendar based on a five-year period or yuga in which the Sun made 5 complete revolutions. Moreover, this quinquennial cycle contained 67 sidereal and 62 synodic revolutions of the Moon, 1830 sāvana or civil days, 1835 sidereal days, 1800 solar days and 1860 lunar days. An important feature of the Jyotiṣa is its concept of the lunar day or tithi which is a thirtieth part of the synodic month. The tithi concept was also used in Babylonian astronomy of the Seleucid period. To trace the motion of the Sun and the Moon and to locate the positions of fullmoons and newmoons in the sky a stellar zodiac or a nakṣatra system coming down from the times of the Saṃhitās and the Brāhmaṇas was used. The Jyotiṣa was acquainted with the solstices and equinoxes, the variation in day-length of which a correct ratio was given. It is, however, silent about the inclination of the ecliptic, the non-uniform and irregular motion of the Sun and the Moon and various other important elements.

Surface Melting and Surface Diffusion on Clusters

1990 ◽  
Vol 206 ◽  
Author(s):  
Hai-Ping Cheng ◽  
R. Stephen Berry
Keyword(s):  
Surface Layer ◽  
Collective Motion ◽  
Surface Melting ◽  
Surface Structures ◽  
Random Surface ◽  
Lennard Jones ◽  
Embedded Atom ◽  
Diffusion Constants ◽  
Irregular Motion ◽  
Latent Heats

ABSTRACTSurface melting on clusters is investigated by a combination of analytic modeling and computer simulation. Homogeneous, argon-like clusters bound by Lennard-Jones forces and Cu-like clusters bound by ‘embedded atom’ potentials are the systems considered. Molecular dynamics (MD) calculations have been carried out for clusters with 40–147 atoms. Well below the bulk melting temperature, the surfaces become very soft, exhibiting well-defined diffusion constants even while the cores remain nearly rigid and solid-like. The simulations, particularly animations, of atomic motion reveal that the surface melting is associated not with amorphous, random surface structures in constant, irregular motion, but rather in large-amplitude, organized, collective motion of most of the surface atoms accompanied by a few “floaters” and holes. At any time, a few of the surface atoms move out of the surface layer, leaving vacancies; these promoted particles wander diffusively, the holes also but less so, and occasionally exchange with atoms in the surface layer. This result is the basis for an analytic, statistical model. The caloric curves, particularly the latent heats, show that surface melting of clusters is a “phase change” different from the bulk melting of clusters.

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