scholarly journals A Robust Control Algorithm of a Descent Vehicle Angular Motion in the Earth’s Atmosphere

2022 ◽  
Vol 12 (2) ◽  
pp. 731
Author(s):  
Nikolay Zubov ◽  
Alexey Lapin ◽  
Vladimir Ryabchenko ◽  
Andrey Proletarsky ◽  
Maria Selezneva ◽  
...  
Keyword(s):  
Control Algorithm ◽  
Angular Position ◽  
Angular Motion ◽  
Working Fluid ◽  
Modal Control ◽  
Robust Controller ◽  
New Approach ◽  
Manned Spacecraft ◽  
The Earth ◽  
Descent Vehicle

A new approach to synthesize a robust controller for the angular motion of the Earth lander by decomposition method of output modal control is proposed. A universal analytical solution for the problem of stabilizing the angular position of the lander is obtained. A comparative analysis of the presented algorithm with the currently used onboard algorithm for descent control of the manned spacecraft Soyuz is carried out. The advantages of the new algorithm relative to the existing algorithm are presented, both in terms of stabilization accuracy and the consumption of the working fluid of the control motors.

Reference Coordinate System Requirements for Geophysics

1975 ◽  
Vol 26 ◽  
pp. 87-92
Author(s):  
P. L. Bender
Keyword(s):  
Coordinate System ◽  
Polar Motion ◽  
Main Part ◽  
Measurement Techniques ◽  
Reference Points ◽  
Angular Motion ◽  
Coordinate Systems ◽  
Axis Of Rotation ◽  
The Earth ◽  
Fixed System

AbstractFive important geodynamical quantities which are closely linked are: 1) motions of points on the Earth’s surface; 2)polar motion; 3) changes in UT1-UTC; 4) nutation; and 5) motion of the geocenter. For each of these we expect to achieve measurements in the near future which have an accuracy of 1 to 3 cm or 0.3 to 1 milliarcsec.From a metrological point of view, one can say simply: “Measure each quantity against whichever coordinate system you can make the most accurate measurements with respect to”. I believe that this statement should serve as a guiding principle for the recommendations of the colloquium. However, it also is important that the coordinate systems help to provide a clear separation between the different phenomena of interest, and correspond closely to the conceptual definitions in terms of which geophysicists think about the phenomena.In any discussion of angular motion in space, both a “body-fixed” system and a “space-fixed” system are used. Some relevant types of coordinate systems, reference directions, or reference points which have been considered are: 1) celestial systems based on optical star catalogs, distant galaxies, radio source catalogs, or the Moon and inner planets; 2) the Earth’s axis of rotation, which defines a line through the Earth as well as a celestial reference direction; 3) the geocenter; and 4) “quasi-Earth-fixed” coordinate systems.When a geophysicists discusses UT1 and polar motion, he usually is thinking of the angular motion of the main part of the mantle with respect to an inertial frame and to the direction of the spin axis. Since the velocities of relative motion in most of the mantle are expectd to be extremely small, even if “substantial” deep convection is occurring, the conceptual “quasi-Earth-fixed” reference frame seems well defined. Methods for realizing a close approximation to this frame fortunately exist. Hopefully, this colloquium will recommend procedures for establishing and maintaining such a system for use in geodynamics. Motion of points on the Earth’s surface and of the geocenter can be measured against such a system with the full accuracy of the new techniques.The situation with respect to celestial reference frames is different. The various measurement techniques give changes in the orientation of the Earth, relative to different systems, so that we would like to know the relative motions of the systems in order to compare the results. However, there does not appear to be a need for defining any new system. Subjective figures of merit for the various system dependon both the accuracy with which measurements can be made against them and the degree to which they can be related to inertial systems.The main coordinate system requirement related to the 5 geodynamic quantities discussed in this talk is thus for the establishment and maintenance of a “quasi-Earth-fixed” coordinate system which closely approximates the motion of the main part of the mantle. Changes in the orientation of this system with respect to the various celestial systems can be determined by both the new and the conventional techniques, provided that some knowledge of changes in the local vertical is available. Changes in the axis of rotation and in the geocenter with respect to this system also can be obtained, as well as measurements of nutation.

scholarly journals Motions models of a two-wheeled experimental sample

2021 ◽  
pp. 40-49
Author(s):  
Anatoliy Kulik ◽  
Konstantin Dergachov ◽  
Sergey Pasichnik ◽  
Sergey Yashyn
Keyword(s):  
Automatic Control ◽  
State Space ◽  
Experimental Model ◽  
Functional Properties ◽  
Angular Position ◽  
The Body ◽  
Angular Motion ◽  
Physical Models ◽  
Experimental Sample ◽  
Electric Drives

The subject of study is the physical processes of translational and angular motion of a two-wheeled experimental sample. The goal is to develop physical, mathematical, and graphic models of the translational and angular motions of a two-wheeled experimental sample as an object of automatic control. The objectives: to form physical models of a two-wheeled experimental sample; to develop a nonlinear mathematical description of the processes of translational and angular sample`s motions using the Lagrange approach; to obtain a linearized mathematical sample`s description as an object of automatic control in the state space and frequency domain; to generate graphic models in the form of structural diagrams in the time and frequency domains; to analyze the functional properties of an object of automatic control: stability, controllability, observability, structural and signal diagnosability concerning violations of the functional properties of electric drives and sensors of the angular position of the body and wheels. The methods of the study: the Lagrange method, Taylor series, state-space method, Laplace transformations, Lyapunov, Kalman criteria, and diagnosability criterion. The results: physical models of a two-wheeled experimental sample have been obtained in the form of a kinematic diagram of the mechanical part and the electric circuit of an electric drive; mathematical descriptions of translational and angular motions have been developed in nonlinear and linearized forms; structural diagrams have been developed; functional characteristics of a two-wheeled experimental model as an object of automatic control have been analyzed to solve problems of control algorithms synthesis. Conclusions. The scientific novelty lies in obtaining new models that describe the translational and angular motion of a two-wheeled experimental model as an object of automatic control. The obtained models differ from the known ones by considering the dynamic properties of sensors and electric drives, as well as the relationship of movements.

scholarly journals Gravitational differentiation in the regimes from stokes settling to Rayleigh–Raylor flows

2019 ◽  
pp. 15-30
Author(s):  
V. P. Trubitsyn
Keyword(s):  
Viscous Fluid ◽  
Interacting Particles ◽  
Small Particles ◽  
Continuous Transition ◽  
New Approach ◽  
Earth's Core ◽  
The Core ◽  
The Earth ◽  
Large Particles ◽  
Two Component

The Earth’s core was formed under gravitational differentiation in the course of the separation of iron and silicates. Most of the iron has gone into the core as early as when the Earth was growing. However, iron continued to precipitate even during the subsequent partial solidification which developed from the bottom upwards. At the different stages and in the different layers of the mantle, iron was deposited in different regimes. In this paper, the mechanisms of the deposition of a cloud of heavy interacting particles (or drops) in a viscous fluid are considered. A new approach suitable for analytical and numerical tracing the changes in the structure of the flows in a two-component suspension under continuous transition from the Stokessettling (for the case of a cloud of large particles) to the Rayleigh–Taylor flows and heavy diapirs (for the case of a cloud of small particles) is suggested. It is numerically and analytically shown that the both regimes are the different limiting cases of the sedimentation convection in suspensions.

Measurement of the angular motion parameters of the mirror of the scanning device

2021 ◽  
pp. 3-7
Author(s):  
Petr A. Pavlov ◽  
Elena M. Ivashchenko
Keyword(s):  
Angular Velocity ◽  
Angular Position ◽  
Low Frequency ◽  
Frequency Region ◽  
Angular Motion ◽  
Main Attention ◽  
Scanning Angle ◽  
Scanning Device ◽  
Environmental Monitoring System

A scanning device for a space-based environmental monitoring system has been investigated. The main attention is paid to the study of the parameters of the angular motion of the mirror of the scanning device, the uniformity of rotation of which largely determines the quality of the image of the Earth's surface. The principle and results of measuring the parameters of the mirror rotation carried out in a wide angular range are considered. The measurements were performed using a dynamic goniometer-autocollimator, which has been calibrated at the State Standard of Plane Angle Unit GET 22-2014. The repeatability of the average angular velocity of the scanning device mirror and the repeatability of the initial scanning angle are calculated. Nonstationarity in mathematical expectation and variance in random deviations of the angular motion of the mirror from the linear law of scanning is noted. The use of wavelet analysis revealed the frequency of excitation of oscillations in the low-frequency region of the spectrum. The possibility of using the a dynamic goniometer-autocollimator for measuring not only the angular position of the scanning device mirror, but also the angular velocity is shown.

Merengkuh Bumi Merawat Semesta: Mengupayakan Hermeneutik Ekologis dalam Rangka Menanggapi Kerusakan Lingkungan Dewasa Ini

2021 ◽  
Vol 1 (1) ◽  
pp. 71
Author(s):  
Darius Ade Putra
Keyword(s):  
Biblical Text ◽  
New Paradigm ◽  
New Approach ◽  
Ecological Damage ◽  
The Bible ◽  
The Earth ◽  
The 1960S ◽  
The Universe

Abstract Since the 1960s, started by Lynn White, Christianity has begun to get attacks because it is considered to have triggered ecological damage. Christianity through the teachings of the Bible is accused of legitimizing absolute anthropocentric ideas which then give rise to expansive actions to the environment and nature. In the midst of the massive damage to the environment and in order to fi nd a possible solution to this problem, it is felt necessary to resonance the new approach to the Scriptures that further explores the sound of the earth. One approach that can be developed is ecological hermeneutics. Based on several principles it is possible to see and understand the biblical text from the perspective of the earth. In addittion, this approach will be elaborated with local wisdom so that it can help the text contextualization process. In the end, a new paradigm is expected to encourage awareness of the importance to tend the universe.   Abstrak Sejak tahun 1960an, dimulai oleh Lynn White, Kekristenan mulai mendapat serangan karena dinilai telah menjadi pemicu kerusakan ekologi. Kekristenan melalui ajaran Alkitab dituduh melegitimasi gagasan-gagasan antroposentris absolut yang kemudian melahirkan tinndakan- tindakan ekspansif terhadap lingkungan dan alam. Di tengah masifnya kerusakan lingkungan dan dalam rangka mencari kemungkinan jalan keluar dari persoalan ini, dirasa perlu untuk menggemakan pendekatan baru pada Kitab Suci yang lebih mengeksplorasi suara bumi. Salah satu pendekatan yang bisa dikembangkan adalah hermeneutik ekologi. Berdasarkan beberapa prinsip-prinsipnya memungkinkan untuk melihat dan memahami teks Alkitab dari perspektif bumi. Selain itu, pendekatan ini akan dielaborasi dengan local widom agar membantu proses kontekstualisasi teks. Pada akhirnya diharapkan sebuah paradigma baru yang mendorong kesadaran akan pentingnya merawat alam semesta.

scholarly journals High-accuracy equation of equinoxes and VLBI astrometric Modelling

1991 ◽  
Vol 131 ◽  
pp. 342-345
Author(s):  
A.M. Gontier ◽  
N. Capitaine
Keyword(s):  
High Accuracy ◽  
Classical Representation ◽  
New Approach ◽  
The Earth ◽  
Angle Of Rotation

AbstractIn the course of implementing the use of nonrotating origin (Guinot 1979) in astrometric VLBI, for the transformation between celestial and terrestrial frames, we have compared the new approach with the classical one. We have shown that a difference exists between the two procedures at a few milliarcsecond level; this difference is due to the terms generally neglected when considering the equation of equinoxes in the classical representation of the Earth angle of rotation.

Thermodynamics From a Few Dynamic Particles Raises Questions as to How Temperature and Entropy Should Be Perceived and Defined

2007 ◽  
Author(s):  
W. John Dartnall ◽  
John Reizes
Keyword(s):  
Kinetic Energy ◽  
Single Particle ◽  
Heat Engine ◽  
Working Fluid ◽  
Second Law ◽  
Piston Engine ◽  
New Approach ◽  
Particle Mechanics ◽  
Mechanics Model ◽  
Heat Engines

In a recently developed simple particle mechanics model, in which a single particle represents the working fluid, (gas) in a heat engine, (exemplified by a piston engine) a new approach was outlined for the teaching of concepts to thermodynamic students. By mechanics reasoning, a model was developed that demonstrates the connection between the Carnot efficiency limitation of heat engines, and the Kelvin-Planck statement of Second Law, requiring only the truth of the Clausius statement. In a second paper the model was extended to introduce entropy. The particle’s entropy was defined as a function of its kinetic energy, and the space that it occupies, that is analogous to that normally found in classical macroscopic analyses. In this paper, questions are raised and addressed: How should temperature and entropy be perceived and defined? Should temperature be proportional to average (molecular) translational kinetic energy and should entropy be dimensionless?

scholarly journals The motion of a geosynchronous satellite

1986 ◽  
Vol 114 ◽  
pp. 293-295
Author(s):  
K. B. Bhatnagar
Keyword(s):  
Angular Velocity ◽  
Solar Radiation ◽  
Radiation Pressure ◽  
Angular Position ◽  
Orbital Plane ◽  
Solar Radiation Pressure ◽  
Orbital Inclination ◽  
Geosynchronous Satellite ◽  
The Earth ◽  
Earth’S Equatorial Ellipticity

The motion of a geosynchronous satellite has been studied under the combined gravitational effects of the oblate Earth (including its equatorial ellipticity), the Sun, the Moon and the solar-radiation pressure. It is observed that the orbital plane rotates with an angular velocity the maximum value of which is 0.058°/yr. and regresses with a period which increases both as the orbital inclination and the altitude increase. The effect of earth's equatorial ellipticity on the regression period is oscillatory whereas that of Solar-radiation pressure is to decrease it.The synchronism is achieved when the angular velocity of the satellite is equal to the difference between the spin-rate of the Earth and the regression rate of the orbital plane. With this angular velocity of the satellite, the ground trace is in the shape of figure eight, though its size and position relative to the Earth change as the time elapses. The major effect of earth's equatorial ellipticity is to produce a change in the relative angular position of the satellite as seen from the Earth. If the satellite is allowed to execute large angle oscillations the mid-point of oscillation would be at the position of the minor axis of the earth's equatorial section. The oscillatory period T has been determined in terms of the amplitude Γ and the tesseral harmonic J2(2). From this result we can determine the value of J2(2) as T and Γ can be observed accurately.

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