Classical Kinematics Research Articles

Dimensional Synthesis of Closed-Loop Linkages to Match Force and Position Specifications

By combining classical kinematic synthesis and static synthesis, we consider force conditions as well as motions in the dimensional synthesis of linkages. We are concerned with determining the dimensions of linkages that guide a rigid body through several positions and support a specified external load at each position. Three types of planar linkages are studied in detail: four-bar, slider-crank, and double-slider linkages. Incompletely specified problems and spring element synthesis are also discussed.

Assessment of Life of Inner Vessel for a Pool-Type Fast Breeder Reactor Based on Inelastic and Viscoplastic Deformations

Towards assessing the creep-fatigue damage for the inner vessel of a pool-type fast reactor, 3-D elastic and axisymmetric inelastic analysis with classical kinematic hardening model, ORNL material model and more realistic CHABOCHE visco-plastic model have been performed. The material properties of stainless steel type 316 LN at various temperatures are used in the analysis. Using the results of this analysis, the creep-fatigue damage and ratcheting are assessed as per the rules of RCC-MR and results have been compared for the various constitutive models used. Inelastic analysis has been performed only at highly stressed local regions. Computations with the ORNL material model is found to be satisfactory in terms of conservatism and computer cost involved, and hence recommended for use in the design stage. Further, conservatism in estimating the creep fatigue-damage of the component associated with the elastic route of RCC-MR has been quantified. The inelastic and viscoplastic analysis tool has been validated using experimental benchmark problems.

Computational requirements for a discrete Kalman filter in robot dynamics algorithms

SUMMARYIn standard classical kinematic and dynamic considerations the equations of motion for an n-link manipulator can be obtained as recursive Newton-Euler equations. Another approach to finding the inverse dynamics equations is to formulate the system dynamics and kinematics as a two-point boundary-value problem. The equivalence between these two approaches has been proved in this paper. Solution to the two-point boundary-value problem leads to the forward dynamics equations which are similar to the equations of Kalman filtering and Bryson-Frazier fixed time-interval smoothing. The extensive numerical studies conducted by the author on the new inverse and forward dynamics algorithms derived from the two-point boundary-value problem establish the same level of confidence as exists for current methods. In order to obtain the algorithms with the smallest coefficients of the polynomial of order O(n), the categorization procedure has been implemented in this work.

Three-dimensional motion computation and object segmentation in a long sequence of stereo frames

We address the problem of computing the three-dimensional motions of objects in a long sequence of stereo frames. Our approach is bottom-up and consists of two levels. The first level deals with the tracking of 3D tokens from frame to frame and the estimation of their kinematics. The processing is completely parallel for each token. The second level groups tokens into objects based on their kinematic parameters, controls the processing at the low level to cope with problems such as occlusion, disappearance, and appearance of tokens, and provides information to other components of the system. We have implemented this approach using 3D line segments obtained from stereo as the tokens. We use classical kinematics and derive closed-form solutions for some special, but useful, cases of motions. The motion computation problem is then formulated as a tracking problem in order to apply the extended Kalman filter. The tracking is performed in a prediction-matching-update loop in which multiple matches can be handled. Tokens are labeled by a number called its support of existence which measures their adequation to the measurements. If this number goes beyond a threshold, the token disappears. The individual line segments can be grouped into rigid objects according to the similarity of their kinematic parameters. Experiments using synthetic and real data have been carried out and the results found to be quite good.

X-ray activity as statistical age indicator - The disk G-K giants

view Abstract Citations (5) References (40) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X-Ray Activity as Statistical Age Indicator: The Disk G--K Giants Micela, G. ; Maggio, A. ; Vaiana, G. S. Abstract For a sample of late-type disk giant stars, the dependence of coronal emission on age as defined by metallicity and kinematics indicators has been studied. It is found that the mean level of X-ray emission for stars with strong metallic lines and/or small peculiar velocities is larger by about one order of magnitude than the mean level of emission for stars with weak lines and/or high peculiar velocities. Hence, it is suggested that the X-ray activity can be used as a statistical age indicator for late-type giants, as well as the classical metallicity or kinematics indicators. It is found that the spread in metallicity typical of the Galactic disk accounts for less than 50 percent of the observed difference in X-ray emission. To explain the observations it is argued that other effects should be invoked, such as changes in the efficiency of the stellar magnetic dynamo or the influence of metallicity itself on the coronal heating processes. Publication: The Astrophysical Journal Pub Date: March 1992 DOI: 10.1086/171139 Bibcode: 1992ApJ...388..171M Keywords: G Stars; Giant Stars; K Stars; Stellar Activity; Stellar Evolution; X Ray Stars; Color-Magnitude Diagram; Emission Spectra; Hertzsprung-Russell Diagram; Metallicity; Stellar Coronas; Astrophysics; STARS: CORONAE; STARS: EVOLUTION; STARS: LATE-TYPE; X-RAYS: STARS full text sources ADS | data products SIMBAD (66)

A ductility exhaustion approach for axial-fatigue—creep damage assessment using type-316 stainless steel: Zamrik, S.Y. and Davis, D.C. J. Pressure Vessel Technol. (Trans. ASME) May 1991 113, (2), 180–186

Ratcheting, which is the strain accumulation observed under the unsymmetrical stress controlled loading and non-proportional loadings, is modeled using the simplified viscoplasticity theory based on overstress (VBO). The influences of kinematic hardening laws on the uniaxial and multiaxial non-proportional ratcheting behavior of CS 1026 carbon steel have been investigated. The following kinematic hardening rules have been considered: the classical kinematic hardening rule, the kinematic hardening rules introduced by Armstrong–Frederick, Burlet–Cailletaud and the modified Burlet–Cailletaud. The investigated loading conditions include uniaxial stress controlled test with non-zero mean stress, and axial strain controlled cyclic test of thin-walled tubular specimen in the presence of constant pressure. Numerical results are compared with the experimental data obtained by Hassan and Kyriakides [Hassan T, Kyriakides S. Ratcheting in cyclic plasticity, part I: uniaxial behavior. Int J Plast 1992;8:91–116] and Hassan et al. [Hassan T, Corona E, Kyriakides S. Ratcheting in cyclic plasticity, part I: multiaxial behavior. Int J Plast 1992;8:117–146]. It is observed that all investigated kinematic hardening rules do not improve ratcheting behavior under multiaxial loading, but over-prediction still exists.

Zur Theorie Der Lorentztransformationen

On the Theory of the Lorentz transformations. A Reply The author defends the notion of absolute time and classical kinematics in special relativity against various objections raised against his theory of the Lorentz transformations.

A short proof of principal kinematic formula and extensions

Federer’s extension of the classical principal kinematic formula of integral geometry to sets with positive reach is proved in a direct way by means of generalised unit normal bundles, associated currents, and the coarea theorem. This enables us to extend the relation to more general sets. At the same time we get a short proof for the well-known variants from convex geometry and differential geometry.

Kinematics and the special theory of relativity

Consistent use of the principles of classical kinematics leads to interesting theorems, connecting the coefficients of linear transformations between systems of inertia. Differential equations expressing such connections diminish the number of independent postulates required for the establishment of the Lorentz group.

Theorie der Lorentztransformationen

By way of mathematical demonstration proof is given that the Lorentz transformations can completely be based upon the theory of absolute time, i. e. upon the Galilei transformations (without neglecting quantities of higher order). Thus, it becomes evident that the theory of special relativity does not imply a revolution of classical kinematics, let alone of idealistic theory of knowledge.

A classical kinematic model for direct reactions of oriented reagents

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA classical kinematic model for direct reactions of oriented reagentsI. Schechter, M. G. Prisant, and R. D. LevineCite this: J. Phys. Chem. 1987, 91, 21, 5472–5480Publication Date (Print):October 1, 1987Publication History Published online1 May 2002Published inissue 1 October 1987https://doi.org/10.1021/j100305a019RIGHTS & PERMISSIONSArticle Views48Altmetric-Citations26LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts

Emission-angle-dependent post-collision interaction.

We studied the autoionization electrons of two doubly excited states of helium---(2s2p${)}^{1}$P and (2${p}^{2}$${)}^{1}$D---that were collisionally excited by multiply charged and relatively fast ions. The ion velocities (2--4.5 a.u.) were faster than the velocities of the emitted electrons (\ensuremath{\sim}1.6 a.u.). The wings of the measured autoionization profiles were significantly different from standard Beutler-Fano profiles. These differences are largest at forward angles, smaller ion velocities, and larger ion charges. The distortion is explained with use of a classical kinematic model. After emission, the autoionization electron is accelerated if emitted in a forward direction (toward the projectile) or slowed down if emitted in a backward direction (away from the projectile). A modification of a post-collision interaction theory accounts for the interference between the bound-state electrons and the continuum electrons. Fits of the measured electron-energy spectra with use of this model show very good agreement.

Actual compatibility between three-dimensional time conjecture and experienced doppler effect

To remove some doubts in this regard, it is pointed out that the idea of one temporal co-ordinate for each spatial freedom degree is by no means in disagreement either with Ives and Stilwell experiment or with more recent data concerning Doppler effect. It is also shown how in such a framework the pure « three-temporal » formalism of classical one-photon kinematics can naturally be matched to a standardlike picture for electromagnetic waves.

Nonlinear Kinematics of Wheel-Rail Contact

We derive relations which describe the nonlinear geometry of contact between a railway vehicle wheelset and rail. Geometric constraint relations are derived and expanded about the central (rest) positions. These are solved for the rolling and vertical motions, instantaneous left and right wheel rolling radii, angles between the contact and horizontal planes, and lateral and longitudinal creepages. The results are given explicitly in terms of the lateral and yawing motions for mildly noncircular wheel and rail profiles. A kinematic (pure rolling) solution is obtained for the case where the wheel profile is sufficiently noncircular to invalidate the classical linear kinematic solution.

Classical microscopic calculation of fast heavy-ion collisions

We consider heavy-ion collisions with beam energies of a few hundred MeV/nucleon, because such collisions seem favorable for producing compressed nuclear matter. As an alternative to hydrodynamic ways of calculating such collisions, we are investigating a microscopic, rapid (and therefore economical) simulation method. There are two simplifications basic to this method: (i) using classical particle kinematics, and (ii) taking nucleonnucleon interactions into account via cross sections rather than explicit forces. Some other simplifications, concerning nuclear binding etc., are presently crude but will be improved. Even at normal density, nuclear matter is not so dilute; therefore our calculations show some sensitivity to details of the mechanism assume for nucleon-nucleon scattering. For head-on collision of two mass-235 nuclei, our present calculations yield maximum densities between 2 and 3 times that of normal nuclear matter.

Classical microscopic description of U + U collisions

Calculations simulating head-on collisions between two mass-235 nuclei are made using classical kinematics, Monte-Carlo methods, and nucleon-nucleon cross sections. The calculated ratio of maximum particle density to the pre-collision nuclear density is ≈ 2 or 3, depending on details of the nucleon-nucleon scattering mechanism used.

On nonlinear kinematic hardening plasticity theory

Experimental data for metals, e.g. stainless steel, at elevated temperatures show that the loop of the stress-strain curve obtained in a cyclic tension test grows in size in a bounded fashion with each successive cycle. This implies that either the material follows isotropic hardening during its initial deformation phase from the virgin state, or that the material obeys the kinematic hardening rule by maintaining constant elastic range but with continuously increasing hardening. The known experimental data seems to favor the latter assumption, in which case the classical linear kinematic hardening rule could not adequately describe the cyclic behavior of the material. It becomes necessary, therefore, to generalize the linear hardening rule to nonlinear hardening and furthermore to make the shape of the plastic portion of the stress-strain curve variable with the number of cycles. This paper presents a development of a nonlinear kinematic hardening rule which admits the use of nonlinear stress-strain curves whose shapes can be varied as functions of the number of cycles. It will be shown that the proposed rule leads to a yield surface that depends explicitly on past history in a special way. It will also be shown that, within the original framework of Prager's kinematic hardening postulate, the proposed generalization to nonlinear hardening admits radial as well as nonradial loading for initially isotropic material. A Ramberg-Osgood form of the stress-strain curve will be utilized to demonstrate the utility of the method and, by making the parameters in the stress-strain curve cycle dependent, a cyclic stress-strain curve which grows with the number of cycles can be adequately represented. Finally, an incremental stress-strain relation which can be used in structural analysis is derived on the basis of the proposed nonlinear kinematic hardening rule.

Kinematieal groups as group extensions

Classical kinematical groups are analysed from the viewpoint of the cohomology theory of abstract groups using group extension andG-enlsrgement theory.

Review of Ring Laser Experiments on the Convection of Light

Abstract The ring laser experiments, reported in 1964, by Macek, Schneider, and Salamon on the convection of light in moving media were incorrectly formulated. Optical path changes due to convection were overlooked. The Einstein addition theorem for parallel motion was inappropriately applied for non-parallel motion. The alleged agreement construed between wrong theory and experiment for moving quartz and air is inconclusive. The results presented for flowing CCl4, which did not agree with the incorrect formulation, contradict the correct Einstein and/or ether theory formulation. Excellent agreement is found instead for the experiment on CCl4 and the correctly formulated prediction based on (etherless) classical kinematics.

On the Use of Shell Theory for Determining Stresses in Composite Cylinders

Applying Vlasov-Ambartsumyan shell theory to anisotropic and laminated cylinders, equations are developed for calculating the stresses in a composite tube under combined axial load, torsion, and internal pressure. Comparison to results obtained from exact elasticity theory shows that the shell equations are capable of predicting, with a reasonable degree of accuracy, the large stress gradients found in highly anisotropic tubes. Thus the shell theory provides the experimentalist with a set of closed form expressions for readily defining the proper specimen dimensions for precise characterization of unidirectional and laminated composite tubes. A modification to the shell theory, in which the effects of transverse normal strain are included is also discussed. Numerical results show that such a modification is necessary for determining stresses induced by free thermal expansion. It is also shown that certain classical thin shell kinematic relations are incapable of predicting stresses in composite tubes.