Calibration Method for Angular Positioning Deviation of a High-Precision Rotary Table Based on the Laser Tracer Multi-Station Measurement System

This paper proposes a calibration method for angular positioning deviation of a high-precision rotary table based on the laser tracer multi-station measurement system. The algorithm error of the calibration method for angular positioning deviation of a high-precision rotary table based on the laser tracer multi-station measurement system was mainly discussed. During the experiments, the laser tracer was fixed on the work surface of the rotary table, and the rotary was fixed on the work surface of the coordinate measurement machine (CMM). The rotary table was rotated with the same angular interval. In this case, an optimization method for calculating the coordinates of a laser tracer station by using Levenberg–Marquardt algorithm and singular value decomposition transform was proposed. Then, the angular positioning deviation of the rotary table was calibrated by an established geometric relationship model between the coordinates of laser tracer stations and the rotation angle of the rotary table. The angular positioning deviation of the high-precision rotary table was as low as ±0.9″, and the error of the calibration method was ±0.4″. The experimental results proved the feasibility of the proposed calibration method. The calibration method proposed in this paper is suitable for the case that the rotary table is not linked with the CMM, especially for large high-precision rotary tables.

Tsallis Statistical Interpretation of Transverse Momentum Spectra in High-EnergypA Collisions

In Tsallis statistics, we investigate charged pion and proton production forpCu andpPb interactions at 3, 8, and 15 GeV/c. Two versions of Tsallis distribution are implemented in a multisource thermal model. A comparison with experimental data of the HARP-CDP group shows that they both can reproduce the transverse momentum spectra, but the improved form gives a better description. It is also found that the difference betweenqandq′is small when the temperatureT = T′for the same incident momentum and angular interval, and the value ofqis greater thanq′in most cases.

High Resolution SelfA Rotary Table by the Interpolation Signal Calibration

Self-A (Self-calibratable Angle device) rotary encoder can detect some kinds of angle error, not only its encoder scale error, but also the encoder attachment error (e.g. eccentricity error). When rotary table with built-in Self-A encoder rotates only one revolution, inner Self-A rotary encoder can calibrate the own angle error with a high accuracy. However, in the case of the Self-A using the encoder of 36,000 graduation scales, since the angular interval of the calibrated main scales corresponds to 36", it is insufficient for high resolution angular indexing control with high accuracy. Generally, the angle error of electric interpolation signal is estimated to be 1 % of main scale resolution that corresponds to about 0.36" for 36,000 scales encoder. Accordingly, even if Self-A had the ability which can calibrate in the accuracy 0.1", when it was controlling the rotary table using an electric interpolation signal, its total accuracy worsened to about 0.36". For improvement in precise angular-position control, we developed Self-A rotary table which can calibrate the angle signal at high resolution including electric interpolation signals. In this paper, we introduce the performance of the new high resolution Self-A encoder table. It keeps high accuracy and good repeatability in the 360° whole range as well as in the short range of ±1,000".

The Error Caused by Order Analysis for Rolling Bearing Fault Signal

Defect diagnosis of rolling element bearings operating under time-varying rotational speeds entails order tracking and analysis techniques that convert a vibration signal from the time domain to the angle domain to eliminate the effect of speed variations. When a signal is resampled at a constant angular increment, the amount of data padded into each data segment will vary, depending on the rate of change in the rotational speeds. This leads to changes in the distance between the adjacent impulse peaks, and consequently, the result of order analysis. This paper presents a quantitative analysis of key factors affecting the accuracy of order analysis on rolling element bearings under variable speeds. An analytical model is established and simulated. The effects of speed variation, instantaneous speed, angular interval between impulses, and the rising time of impulse are specified. It is concluded that the results of order analysis will be smaller as the rotational speed increases, and becomes larger when the speed decreases. Furthermore, the error is larger under low speeds than high speed.

Tubular Initial Conditions and Ridge Formation

The 2D azimuth and rapidity structure of the two-particle correlations in relativistic A+A collisions is altered significantly by the presence of sharp inhomogeneities in superdense matter formed in such processes. The causality constraints enforce one to associate the long-range longitudinal correlations observed in a narrow angular interval, the so-called (soft) ridge, with peculiarities of the initial conditions of collision process. This study's objective is to analyze whether multiform initial tubular structures, undergoing the subsequent hydrodynamic evolution and gradual decoupling, can form the soft ridges. Motivated by the flux-tube scenarios, the initial energy density distribution contains the different numbers of high density tube-like boost-invariant inclusions that form a bumpy structure in the transverse plane. The influence of various structures of such initial conditions in the most central A+A events on the collective evolution of matter, resulting spectra, angular particle correlations andvn-coefficients is studied in the framework of the hydrokinetic model (HKM).

Suppression of grating lobes for MMW sparse array setups

For arrays the placement of the single elements determines the angular resolution and the unambiguity interval. The width of the total array determines the resolution capabilities. The wider the elements are placed from each other, the more space in Fourier domain is covered by the measurement and the resolution in time domain will improve. On the other hand the density of the elements has an effect on the angular interval in which objects can be detected unambiguously. For objects within the unambiguous interval grating lobes will appear outside this area while objects outside result in grating lobes in the interval of interest. In this paper the properties of arrays regarding resolution and unambiguity interval will be discussed and methods for the suppression of ambiguous grating lobes are suggested. One approach to suppress the influence of the grating lobes lies in the evaluation of different frequency bands.

Coordination of two crank angles and two acceleration poles for a slider crank mechanism using parametric equations

The current article presents the parametric equations for the synthesis of a slider crank mechanism with a coupler point passing through two specified acceleration poles that accord with two specified crank angles. The parametric equations for the coordinates of the acceleration pole for the coupler with respect to the frame are shown to be functions of only the geometric configuration of the slider crank mechanism driven by the crank with a constant rotational speed. Moreover, a necessary condition for the crank angular interval corresponding to the two acceleration poles on a coupler curve generated by a slider crank mechanism is investigated. The desired coupler point of a given mechanism passing through two acceleration poles should be a double point on the locus of the acceleration pole described on the coupler plane. The transformed parametric equations on the fixed plane are then applied to synthesize the desired mechanism with a coupler point passing through two specified acceleration poles that accord with two specified crank angles.