Receptances in Mechanical Systems

1954 ◽  
Vol 58 (520) ◽  
pp. 305-305 ◽  
Author(s):  
W. J. Duncan ◽  
M. A. Biot ◽  
D. C. Johnson ◽  
R. E. D. Bishop
Keyword(s):  
Mechanical Systems ◽  
Oscillatory System ◽  
Disturbing Force ◽  
The Cross

We wish to propose that the word “receptance” should be used instead of “admittance” as applied to mechanical systems (see R. and M. 2,000, 1947). By this, we mean that if a generalised disturbing force Fseiωt is applied at the sth generalised co-ordinate qs of a linear oscillatory system, then the response at the rth generalised co-ordinate is given byqs = αrsFseiωtwhere αrs is the “Cross-receptance” between qr and qs. If r = s, then αrs would be the “direct receptance” at qs.

Simplified Calculation of the Eccentric Press Stiffness

2014 ◽  
Vol 613 ◽  
pp. 402-407
Author(s):  
Peter Demeč ◽  
Dominika Palaščáková
Keyword(s):  
Transfer Matrix ◽  
Cross Sections ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Mechanical Systems ◽  
Matrix Form ◽  
Entire Length ◽  
The Press ◽  
The Cross ◽  
Simplified Calculation

The article deals with the simplified calculation of the stiffness of the eccentric press frame. The described method applies to the solving of problem a mathematical identification of condition parameters in the press frame the transfer matrix method (TMM), which is in essence a matrix form of initial parameters method. This method is suitable for mechanical systems with continuously distributed mass in space while the cross-sections along the entire length of the system are not constant.

The Study on Disturbing Force of Dynamic Mechanical Systems Using Kalman Filter Techniques

2013 ◽  
Vol 705 ◽  
pp. 371-377
Author(s):  
Zhang Jing
Keyword(s):  
Kalman Filter ◽  
Mechanical Systems ◽  
Dynamic Structure ◽  
Estimation Accuracy ◽  
Complex Dynamic ◽  
Model Quality ◽  
Disturbing Force ◽  
Dynamic Mechanical ◽  
Multiple Sensors ◽  
Mems Sensor

According to the approach presented in this paper, the disturbing force of dynamic mechanical systems can be estimated using Kalman Filter techniques. It has been shown how multiple sensors can be included to improve the estimation accuracy and how the algorithm responds to changing parameters and model inaccuracies. Finally, the approach has been experimentally verified with a MEMS-sensor and a more complex dynamic structure of a milling machine with active magnetic guides. Future enhancements may especially regard the model side, since the estimation accuracy is directly determined by the model quality.

scholarly journals Study of a Stripper Header for Grain Harvesting as a Vibrating System

2021 ◽  
Vol 31 (3) ◽  
pp. 403-413
Author(s):  
Vladimir Yu. Savin
Keyword(s):  
Differential Equation ◽  
Mathematical Description ◽  
Elastic Element ◽  
Lagrange Equation ◽  
Oscillatory System ◽  
Angular Frequency ◽  
Forced Oscillations ◽  
Disturbing Force ◽  
Vibration Effect ◽  
Generalized Force

Introduction. Grain losses caused by stripping defects are the main problem to be solved in designing a stripper header. To reduce these losses, a design of a stripper header with a vibration drive is proposed. This device combines the processes of stripping grain crops and the vibration effect of the stripping fingers upon the ears of plants. The most important stage of the mathematical description of these processes is composing the differential equation of the stripping fingers motion. Materials and Methods. A computational-graphic diagram of an oscillatory system with one degree of freedom is proposed. To compose the differential equation of the stripping fingers motion, a method based on the application of the Lagrange equation was used. The oscillations of the system under studying arise from the motion of a point in the system according to a given law. The problem of kinematic excitation is reduced to the problem of force perturbation. This stage of the study was carried out without taking into account the resistance forces. Results. An equation for motion of stripping fingers making vibrational reciprocating movements is obtained. It is proposed to select the elastic element in the design scheme and consider a more general case of the stripping fingers movement. In this case, the movement of the stripping fingers is considered to be difficult. A characteristic feature of the mathematical description is the presence of a generalized force of potential forces. The differential equation of motion of a comb in the presence of an elastic element and the solution of this equation are composed. Discussion and Conclusion. Forced oscillations of a system without resistance, excited by a harmonic disturbing force, are harmonic oscillations with constant amplitude. On close values of the angular frequency of vibration of the drive output link and the root of the ratio of the stiffness coefficient of the elastic element to the stripping fingers mass, the case of resonance takes place. The system parameters must be selected so as to avoid this negative phenomenon.

scholarly journals Random oscillations of nonlinear systems with distributed Parameter

2021 ◽  
pp. 084-091
Author(s):  
Gavasheli Levan ◽  
Gavasheli Anri
Keyword(s):  
Nonlinear Partial Differential Equations ◽  
Mechanical Systems ◽  
Sharp Decrease ◽  
Damping Capacity ◽  
Pass Band ◽  
Natural Oscillations ◽  
Disturbing Force ◽  
Vibration Effect ◽  
Vibration Protection ◽  
The Creation

The article analyzes random vibrations of nonlinear mechanical systems with distributed parameters. The motion of such systems is described by nonlinear partial differential equations with corresponding initial and boundary conditions. In our case, the system as a whole is limited, so any motion can be considered as the sum of the natural oscillations of the system, i.e. in the form of an expansion of the boundary value problem in terms of own functions. The use of the theory of random processes in the calculation of mechanical systems is a prerequisite for the creation of sound design methods and the creation of effective vibration protection devices, these methods allow us to investigate dynamic processes, to determine the probabilistic characteristics of displacements of points of the system and their first two derivatives. In the work established these conditions are met, they provide effective vibration protection of the system under study with wide changes in the pass band of the frequencies of the random vibration effect, and the frequency of the disturbing force is much greater than the natural frequency of the system as a whole, in addition, with an increase in the damping capacity of the elastic-damping link of the system, the intensity of the random process significantly decreases, which in turn leads to a sharp decrease in the dynamic coefficient of the system.

Design of Vibration Absorbers for Step Motions and Step Disturbances

2001 ◽  
Author(s):  
Joel Fortgang ◽  
William Singhose
Keyword(s):  
Mechanical Systems ◽  
Oscillatory System ◽  
Settling Time ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
External Disturbances

Abstract Mechanical systems with flexible dynamics often suffer from vibration induced by changes in the reference command or from external disturbances. The technique of adding a secondary oscillatory system, called a vibration absorber, has proven useful at eliminating vibrations from external disturbances and rotational imbalances. Traditionally, vibration absorbers have been designed for systems subject to sinusoidal or random excitations. Here the applicability of vibration absorbers to systems with step changes in the reference command or similar disturbances is studied. The absorber can be designed with a weighting on peak overshoot and settling time, with the possibility of a nearly 90% improvement in settling time. The performance of this new absorber is compared with previously proposed vibration absorbers.

scholarly journals On problem of calculating longitudinal vibrations of piston engine crankshaft

2021 ◽  
Vol 2021 (4) ◽  
pp. 75-83
Author(s):  
Alexander Ivanovich Yamanin ◽  
Vladimir Anatoljevich Zhukov
Keyword(s):  
Oscillatory System ◽  
Radial Force ◽  
Regression Equations ◽  
Connecting Rod ◽  
Longitudinal Vibrations ◽  
Empirical Formulas ◽  
Disturbing Force ◽  
Calculation Results ◽  
Engine Crankshaft

One of the initial stages of calculating the crankshaft longitudinal vibrations is developing an oscillatory system model, which includes the determination of longitudinal pliability (rigidity) of elastic sections. If it is impossible to determine the pliability experimental, the empiric formulas or the final element method (FEM) are used. There are given the values of crank longitudinal pliability of the crankshafts of different marine engine types found by using the formulas of L. Gugliemotti – R. Machciotta, P. Draminsky, E. Y. Gorbunov, S. F. Dorey, N. S. Skorchev, V. S. Stoyanov, etc. It is shown that the calculation results obtained from these formulas for the same engine significantly differ; therefore, the choice of one or another empirical formula for practical calculations is difficult. The preference of using FEM for determining the longitudinal (axial) compliance of cranks and other areas with complex geometric shapes has been proven. The possibility of its application is also shown to determine the longitudinal disturbing force as the reaction of the crankshaft support against the action of the radial force exerted to the connecting rod journal. It is proposed to use, along with empirical formulas, regression equations connecting the longitudinal compliance of the cranks with a significantly larger number of their design dimensions.

A New Approach to the Demonstration of Oxidase-Localization Using Tannic Acid Or Catechin

1973 ◽  
Vol 31 ◽  
pp. 698-699
Author(s):  
V. Mizuhira ◽  
Y. Futaesaku
Keyword(s):  
Cross Section ◽  
Tannic Acid ◽  
Elastic Fiber ◽  
The Other ◽  
New Approach ◽  
Tissue Block ◽  
Active Reaction ◽  
The Cross

Previously we reported that tannic acid is a very effective fixative for proteins including polypeptides. Especially, in the cross section of microtubules, thirteen submits in A-tubule and eleven in B-tubule could be observed very clearly. An elastic fiber could be demonstrated very clearly, as an electron opaque, homogeneous fiber. However, tannic acid did not penetrate into the deep portion of the tissue-block. So we tried Catechin. This shows almost the same chemical natures as that of proteins, as tannic acid. Moreover, we thought that catechin should have two active-reaction sites, one is phenol,and the other is catechole. Catechole site should react with osmium, to make Os- black. Phenol-site should react with peroxidase existing perhydroxide.

Structures Resembling Striated Rootlets in Oocytes

1972 ◽  
Vol 30 ◽  
pp. 124-125
Author(s):  
Valerie V. Ernst
Keyword(s):  
Golgi Complex ◽  
Fibrous Structure ◽  
Oocyte Development ◽  
The Cross

During the earliest stage of oocyte development in the limpet, Acmea scutum, Golgi complexes are small, few and randomly dispersed in the cytoplasm. As growth proceeds, the Golgi complexes increase in size and number and migrate to the periphery of the cell. At this time, fibrous structures resembling striated rootlets occur associated with the Golgi complexes. Only one fibrous structure appears to be associated with a Golgi complex.The fibers are periodically cross banded with an average of 4 dense fibrils and 6 lighter fibrils per period (Fig. 1). The cross fibrils have a center to center spacing of about 7 run which appears to be the same as that of the striated rootlets of the gill cilia in this animal.

Energy Distribution in Electron Beams

1972 ◽  
Vol 30 ◽  
pp. 568-569
Author(s):  
Tamotsu Ohno
Keyword(s):  
Electron Beam ◽  
Energy Distribution ◽  
Cross Section ◽  
Integral Curve ◽  
Electron Beams ◽  
Electron Gun ◽  
Angular Divergence ◽  
Apparent Increase ◽  
Integral Width ◽  
The Cross

The energy distribution in an electron; beam from an electron gun provided with a biased Wehnelt cylinder was measured by a retarding potential analyser. All the measurements were carried out with a beam of small angular divergence (<3xl0-4 rad) to eliminate the apparent increase of energy width as pointed out by Ichinokawa.The cross section of the beam from a gun with a tungsten hairpin cathode varies as shown in Fig.1a with the bias voltage Vg. The central part of the beam was analysed. An example of the integral curve as well as the energy spectrum is shown in Fig.2. The integral width of the spectrum ΔEi varies with Vg as shown in Fig.1b The width ΔEi is smaller than the Maxwellian width near the cut-off. As |Vg| is decreased, ΔEi increases beyond the Maxwellian width, reaches a maximum and then decreases. Note that the cross section of the beam enlarges with decreasing |Vg|.

On the cross-sectional shape of the cellulose crystallites in the tunicate Halocynthia papillosa

1990 ◽  
Vol 48 (3) ◽  
pp. 566-567
Author(s):  
J.-F. Revol ◽  
Y. Van Daele ◽  
F. Gaill
Keyword(s):  
Contrast Imaging ◽  
Animal Kingdom ◽  
Bright Field ◽  
Field Mode ◽  
Cross Sectional ◽  
Ultrathin Sections ◽  
The Cross ◽  
Sectional Shape ◽  
Valonia Ventricosa ◽  
C Nmr

The only form of cellulose which could unequivocally be ascribed to the animal kingdom is the tunicin that occurs in the tests of the tunicates. Recently, high-resolution solid-state l3C NMR revealed that tunicin belongs to the Iβ form of cellulose as opposed to the Iα form found in Valonia and bacterial celluloses. The high perfection of the tunicin crystallites led us to study its crosssectional shape and to compare it with the shape of those in Valonia ventricosa (V.v.), the goal being to relate the cross-section of cellulose crystallites with the two allomorphs Iα and Iβ.In the present work the source of tunicin was the test of the ascidian Halocvnthia papillosa (H.p.). Diffraction contrast imaging in the bright field mode was applied on ultrathin sections of the V.v. cell wall and H.p. test with cellulose crystallites perpendicular to the plane of the sections. The electron microscope, a Philips 400T, was operated at 120 kV in a low intensity beam condition.

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