Reference Circle Research Articles

Correction Method for Perspective Distortions of Pipeline Images

It is common to find severe perspective distortion in a pipeline’s image in medium-diameter pipeline defect detection by the panoramic image unwrapping method, resulting in low-quality image unwrapping and stitching, which is caused by the camera’s optical axis being completely deviated from the pipeline’s center. To solve this problem, a novel correction method for reducing perspective distortion in pipeline images was proposed for pipeline defect detection. Firstly, the method enhances the edges of unevenly illuminated regions within a pipeline to facilitate image segmentation and identify key points necessary for correcting perspective distortion. Then, a six-feature-point extraction method was proposed for a circle target to establish the projection relationship between the extracted feature and mapped points on the reference circle. Finally, a perspective matrix was constructed to complete the perspective transformation correction of the distorted images. The results show that the average correction rate and the average relative error of the proposed correction method can reach 90.85% and 1.31%, respectively. The study innovatively used the enhancement of uneven illumination to find distorted edge information. It proposed an extraction method using a reference circle and six key feature points to build a mapping model. It can provide a novel method which can be used to obtain a superior image for pipeline detection and lay a solid foundation for subsequent high-quality pipeline image stitching.

Research on the influence on the addendum-shortened-coefficient of the first-last teeth of incomplete driving gear to avoid interference

In order to ensure the normal transmission of incomplete gears without interference during the process of gear meshing. This research first establishes the theoretical model to explore the influence of the reference circle pressure angle (α), the addendum modification coefficient, and the number of teeth on the addendum-shortened-coefficient (σ) of the incomplete driving gear's first-last teeth, and then systematically explores the influence between the key factors and the decrease of σ. The results show that: (1) When the pressure angle of the driven gear addendum circle (αa2) and the maximum critical value of the addendum radius of the driving gear to avoid interference (ra1') increases with the increase of α, σ decreases with the increase of α; (2) In the cases of high-modification gear transmission and angular-modification gear transmission, there are five conditions in which σ decreases due to the addendum modification coefficient of driving gear (x1) and the addendum modification coefficient of driven gear (x2): 1) High-modification gear transmission with one case:① x1+x2=0, x1=−x2≠0 with the increase of x2, that is: x1 and x2 are opposite number; 2) Angular-modification gear transmission with other four cases: ② x1+x2<0, x1<0 with x2=0, that is: The driving and driven gears are negative-modified and standard gears, respectively; ③ x1+x2>0, x1=0 with x2>0, that is: The driving and driven gears are standard and positive-modified gears, respectively; ④ x1+x2<0, x1≠0, x2≠0 with the increase of x2, that is: The sum of x1 and x2 are negative and neither of them is zero, there exist three kinds of addendum modification gears for the driving and driven gear, which are positive-negative, negative-positive and negative-negative. ⑤ x1+x2>0, x1≠0, x2≠0 with the increase of x2, that is: The sum of x1 and x2 are positive and neither of them is zero, there exist three kinds of addendum modification gears for the driving and driven gear, which are positive-negative, negative-positive and positive-positive. (3) While exploring the influence of α, x1 and x2 on σ, the influence of the number of driven gear teeth (Z2) on σ is greater than that of the number of driving gear teeth (Z1). It contributes to the optimization design of incomplete gears to avoid transmission interference in the study and improve its gear strength, load-bearing capacity, and transmission efficiency without reducing, etc.

Design of a compact off-axis two-mirror freeform optical antenna for shaping and transmitting an elliptical beam emitted by laser diode.

Elliptical Gaussian beams generated by laser diodes (LDs) often exhibit asymmetrical divergence angle distribution, which limits their practical applications. In this study, we propose what we believe is a novel approach to shape and collimate the elliptical output beam from a LD. The design process involves the construction of two freeform reflective surfaces on a reference circle using a three-dimensional point-by-point iterative method, based on the law of conservation of energy, the vector reflection theory, and Fermat's principle. The output beam's maximum divergence angle is effectively compressed to 3.1579mrad. The design is compact with a folded optical path and antenna size of 368.8c m 3. This paper presents a comprehensive design and optimization process, along with an in-depth analysis of the system's performance, thereby offering novel insights for emerging optical design practitioners.

Effect of recycled powder and gear profile into the functionality of additive manufacturing polymer gears

PurposePolymer laser powder bed fusion (PBF-LB/P) is an additive manufacturing technology that is sustainable due to the possibility of recycling the powder multiple times and allowing the fabrication of gears without the aid of support structures and subsequent assembly. However, there are constraints in the process that negatively affect its adoption compared to other additive technologies such as material extrusion to produce gears. This study aims to demonstrate that it is possible to overcome the problems due to the physics of the process to produce accurate mechanism.Design/methodology/approachTechnological aspects such as orientation, wheel-shaft thicknesses and degree of powder recycling were examined. Furthermore, the evolving tooth profile was considered as a design parameter to provide a manufacturability map of gear-based mechanisms.FindingsResults show that there are some differences in the functioning of the gear depending on the type of powder used, 100% virgin or 50% virgin and 50% recycled for five cycles. The application of a groove on a gear produced with 100% virgin powder allows the mechanism to be easily unlocked regardless of the orientation and wheel-shaft thicknesses. The application of a specific evolutionary profile independent of the diameter of the reference circle on vertically oriented gears guarantees rotation continuity while preserving the functionality of the assembled mechanism.Originality/valueIn the literature, there are various studies on material aging and reuse in the PBF-LB/P process, mainly focused on the powder deterioration mechanism, powder fluidity, microstructure and mechanical properties of the parts and process parameters. This study, instead, was focused on the functioning of gears, which represent one of the applications in which this technology can have great success, by analyzing the two main effects that can compromise it: recycled powder and vertical orientation during construction.

A method for measuring geometric information content of area cartographic objects based on discrepancy degree of shape points

In order to improve the comparability between the geometric information content of vector area objects, this article proposes a method for measuring the geometric information content of area objects based on discrepancy degree of shape points. First, the method selects circles with unique geometric feature as the reference shape for extracting geometric features, and the geometric in-formation carried by each shape point of area objects is represented by the discrepancy degree between the area object and the reference circle at the point position. Second, the proposed method measures the geometric information content of area objects from both local and global perspectives. To avoid the subjectivity of assigning feature weights based on empirical experience, the article uses the relationships between the radii of three reference circles (MIC: Maximum Inscribed Circle, EAC: Equal-area circle, and MCC: Minimum Circumscribed Circle) as adaptive weight parameters for local and global structural geometric information. The amount of geometric information at each shape point is obtained by weighted summation, and the total geometric information content of an area object is the sum of the amount of geometric information of all shape points. To verify the effectiveness and rationality of the proposed method, this article designs a noise simulation dataset for simply building area objects and an empirical ranking dataset for evaluating the measurement performance of the proposed method. The experimental results show that the proposed method achieves a Kendall rank correlation coefficient of 0.88 on the empirical ranking dataset, which is higher than that of the nine existing representative methods. The proposed method is more consistent with human cognition and is highly correlated with the amount and intensity of noise information. Moreover, the proposed method achieves the comparability of geometric information content of area objects and the adaptive determination of geometric feature weights. The proposed method is an effective method for measuring the geometric information quantity of area objects.

Approximate controllability of a 2D linear system related to the motion of two fluids with surface tension

AbstractWe consider a coupled system of partial differential equations describing the interactions between a closed free interface and two viscous incompressible fluids. The fluids are assumed to satisfy the incompressible Navier‐Stokes equations in time‐dependent domains that are determined by the free interface. The mean curvature of the interface induces a surface tension force that creates a jump of the Cauchy stress tensor on both sides. It influences the behavior of the surrounding fluids, and therefore the deformation of this interface via the equality of velocities. In dimension 2, the steady states correspond to immobile interfaces that are circles with all the same volume. Considering small displacements of steady states, we are lead to consider a linearized version of this system. We prove that the latter is approximately controllable to a given steady state for any time by the means of additional surface tension type forces, provided that the radius of the circle of reference does not coincide with a scaled zero of the Bessel function of first kind.

Influence of reference circles on the evaluation results of axis straightness errors

Measurement principle of axis straightness error of cylindrical parts was introduced based on their roundness profiles. The evaluation models of the center coordinates of four kinds of the reference circles were built, and the evaluation models of the axis straightness errors were established by using the least-square and minimum zone criteria. The roundness profiles of eight simulated cylinders, eight holes, and eight shafts were extracted, and their axis straightness errors were evaluated based on the different reference circles and evaluation criteria. The “minimax” issues in the evaluation process of axis straightness errors were be solved by using Equilibrium Optimizer, and its implementation flows were given. Their evaluation results were analyzed under the used reference circles and evaluation criteria. The analysis results showed that both reference circles and evaluation criteria have much influence on the evaluation results, and that among the evaluation results based on the centers’ coordinates of four reference circles and two evaluation criteria, the axis straightness errors evaluated based on the center coordinates of least-square reference circle and the minimum zone criteria is the least one for most of cylindrical parts, the roundness profiles of which may have no singularities, and the differences among the axis straightness errors evaluated on the basis of different reference circles and different evaluation criteria are very large sometimes, which should be noted in checking whether the axis straightness errors of parts are qualified.

Корни, ствол и крона психологии деятельности

&lt;p&gt;The text is a review of the historical and theoretical book by E.E. Sokolova Psychology of activity: formation and prospects of development. The panorama of the ideas of the psychology of activity is reproduced based on the historical and logical foundations of the concept of activity in philosophy and psychology. These ideas are revealed in the context of the polylogue of scientists within the A.N. Leontiev school and its wide reference circle. Special attention is paid to the understanding of activity as casa sui as opposed to its mechanistic interpretation. The contradictions and paradoxes of activity are considered, through the fixation and resolution of which the way of thinking that characterizes the theory of A.N. Leontiev was formed.&lt;/p&gt;

Transform of parameter and teeth surface modification for non-standard planetary spur gear train with X-gears

In view of the lack of ready formulae for modification calculation of non-standard planetary spur gear trains, the paper is focused on new modification methods of non-standard planetary spur gear trains with X-gears. Firstly, a novelty transform method from the parameters on the pitch circle to the parameters on the reference circle for a non-standard planetary spur gear train with X-gears is proposed in order to study the modification method. Secondly, a scheme of teeth surface modification for non-standard planetary spur gear train with X-gears is put forward. Thirdly, the calculation method of loaded transmission error and flash temperature on the tooth surface under mixed elastohydrodynamic lubrication for external meshing spur gear pairs is proposed using tooth contact analysis as well as loaded tooth contact analysis. Then, a new modification optimization method for non-standard planetary spur gear train with X-gears is proposed, and formulae of the maximal modification length along the tooth height are derived. Finally, the effectiveness of the modification optimization method is confirmed by an example, and the transform formulae of the optimized modification parameters for sun gear are derived.

Bayesian Method for Inverse Scattering Problem of Interior Cavity with Phaseless Data

This paper is concerned with the inverse acoustic scattering problem of a sound soft cavity based on phaseless near-field data. By combining the reference circle technique with the Bayesian method, this paper presents a numerical algorithm to retrieve the shape of the interior cavity from phaseless data. In this paper, the well-posedness of the Bayesian method is discussed. The posterior distribution of the shape parameters is obtained by DRAM algorithm and the reconstruction of the cavity boundary is acquired by taking the average value of the posterior distribution.

NMPC-based trajectory tracking control strategy for unmanned surface vehicle

To solve the unmanned surface vehicle trajectory tracking control problem under model uncertainty and external environmental disturbance, a trajectory tracking control strategy based on nonlinear model predictive control (NMPC) has been proposed. Firstly, a hydrodynamic model considering the uncertainty of model parameters and the influence of external environmental disturbance has been established; then, the fourth-order Lundgren-Kutta method has been used to discretize the nonlinear state space model, and the control quantity, control increment and output quantity of the system have been used as constraints to solve the optimization problem by numerical computation; finally, the reference circle has been used as the preset trajectory, and the trajectory tracking experiment has been carried out under the uncertainty of the model and external environmental disturbance. The experimental results show that the trajectory tracking strategy based on NMPC can better track the preset trajectory and has better anti-interference ability and control effect.

Selection of Reference Circles in the Analysis of Roundness of Rolling Bearings Parts

Selection of Reference Circles in the Analysis of Roundness of Rolling Bearings Parts

Parametric design optimization approach to petal-type solid surface deployable reflectors

A parametric design approach to the petal-type solid surface deployable reflector is presented, in which the generic parametric model of the reflector is established and its division parameters are optimized to simplify the structure, increase deployment reliability and improve electrical performance. For this goal, the estimated expression of the division number of petals is first derived as the initial value of subsequent optimization algorithm. Then the estimation-trial algorithm is developed, its corresponding three-level nested optimization model is established, and the reference circle model for improving the efficiency in solving the aforementioned model is proposed. Furthermore, the deployment scheme of this kind of reflectors is implemented by Euler’s rotation theorem combined with rigid-body registration. In addition, the parameter analysis is made to determine which parameters dominate the division number of petals. Finally, the effectiveness of this method in configuration, deployment and optimality together with the improvement in deployment reliability and electrical performance are verified. It is revealed that reflectors designed with this method need fewer petals compared with the existing reflectors of this class, deploy smoothly, have lower deployment failure probability, as well as have higher antenna gains and lower relative sidelobe levels. The results indicate the petal-type solid surface deployable reflector characterized by compact structure, high reliability and good electrical performance can be obtained with the approach proposed in this paper.

High precision roundness measurement by error separation techniques (EURAMET.L-S30)

Main textThe results of the supplementary comparison EURAMET.L-S30 on roundness measurement on two spheres by using error separation techniques are reported. Five National Metrology Institutes from EURAMET participated in this comparison, which lasted nine months from March 2020 to November 2020.Two alumina spheres with diameters of 20 mm and 25 mm, respectively, were circulated. The sphere standards were permanently glued to base supports made of steel and they had to be clamped by each laboratory's own usual methods. The measurand was the roundness defect, measured on the equator. Peak-to-valley roundness deviation (RONt) had to be evaluated with reference to the least squares reference circle (LSCI) and, if possible, to the minimum zone reference circles (MZCI), in accordance with the ISO/TS 12181-1:2011.Each laboratory had to use an error separation technique to remove the contribution of the spindle error. In case of using a multistep technique it was advisable to inform on the number of steps used.All participants successfully demonstrated the validity of the claimed measurement capability. Three of them submitted their approved CMCs and two others smaller values which were shown to be valid when compared to the reference value. One participant did not use an error separation technique, showing, as expected, a higher uncertainty with respect to the rest of the participants but according to its declared CMC.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The choice of reference circles when analysis the roundness of parts for ball bearings

The choice of reference circles when analysis the roundness of parts for ball bearings

Geometric characteristics of bicuspid aortic valves.

ObjectiveWe studied the coaptation angles α and β in bicuspid aortic valve geometry from computed tomography scan images.MethodsIn 45 patients, we calculated the coaptation angle α (the angle between the nonfused commissures crossing the center of coaptation), angle β (between the nonfused commissures crossing the center of the reference circle), angles γ1 and γ2 and ε1 and ε2 (angle between the nonfused commissures and the coaptation point at the raphe or the perfect midpoint, respectively), the length of the raphe, the absolute and relative sinuses' surfaces (relative to the perfect circle and the percentage exceeding the ideal circle). Spearman correlation was employed to investigate the associations among all parameters.ResultsThe coaptation angles α and β were significantly different (P < .001). We found a significant correlation of α with the length of the raphe (P = .008), whereas β was dependent on the position of the commissures. Both γ1 and γ2 (P = .04), or ε1 and ε2 (P < .001) significantly differed from each other and ε2 was the most constant angle, although its size geometrically depends on β. The noncoronary was the largest sinus, and β was the primary determinant of its increased size in bicuspid aortic valves with righ/left fusion pattern.ConclusionsThe coaptation angle α is influenced by the length of the raphe, whereas angle β is dependent on the position of the commissures. The position of the raphe can vary and is not always situated in the middle of the free edge. The position of the right/non commissure is variable, whereas the right/left commissure is more fixed.

An effective determination of the minimum circumscribed circle and maximum inscribed circle using the subzone division approach

Aiming to develop a more effective circularity evaluation method that satisfies the definition of a particular reference circle criterion, this paper proposes a strategy to determine the minimum circumscribed circle (MCC) and maximum inscribed circle (MIC) using the subzone division approach. The whole circumference zone space that encloses all the sampling data points is divided into different subzones to determine the target candidate feature points, which are used for constructing the MCC or MIC. The first feature point of the MCC/MIC is evaluated according to the farthest/nearest distance from the center of the least squares circle (LSC) within the whole circumference subzone. Subzone with a 120° central angle is designated in the direction of the first feature point that is mapped about the center of the LSC. The second candidate feature point is constrained and determined within this subzone. The third subzone, which contains the third feature point, is formed in the direction of the first and second feature points that are mapped about the center of the LSC. The mathematical model of the MCC or MIC is then constructed using these three feature points. Experimental examples (using five different datasets) and a comparison with previous studies demonstrate that the proposed method yields the exact solution for the MIC and MCC in only 1–2 iterations.

Perception of means, sums, and areas.

In this age of data visualization, it is important to understand our perception of the symbols that are used. For example, does the perceived size of a disc correspond most closely to its area, diameter, circumference, or some other measure? When multiple items are present, this becomes a question of ensemble perception. Here, we compare observers' performance across three different tasks: judgments of (i) the mean diameter, (ii) the total diameter, or (iii) the total area of (N = 1, 2, 3, or 7) test circles compared with a single reference circle. We draw a parallel between Anne Treisman's feature integration theory and Daniel Kahneman's cognitive systems, comparing the preattentive stage to System 1, and the focused attention stage to System 2. In accordance with Kahneman's prediction, average size (diameter) of the geometric figures can be judged with considerable accuracy, but the total diameter of the same figures cannot. Like the total length, the cumulative area covered by circles was also judged considerably less accurately than the mean diameter. Differences in efficiency between these three tasks illustrate powerful constraints upon visual processing: The visual system is well adapted for the perception of the mean size while there are no analogous mechanisms for the accurate perception of the total length or cumulative area. Thus, in visualizing data, using bubble charts proportional to area may be misleading as our visual system seems better adapted to perceive disc size by the radius rather than the area.

Making roundness measurement applications and control systems on the Roundness Tester Machine

Dial indicator is a comparison device usually used in industrial activities, especially in production. To make measurements at this time must be supported by technology that can facilitate operators when using it and when analyzing measurement results. Involving the programme and microcontroller are a solution to developing in roundness measurement, and then the results can be more accurate or thorough between the readable values read from the measuring instrument with the actual value of varying the amount of data. Roundness application is a program that can input measurement data automatically and can do calculations directly. Then, it can display a reference circle, a table that calculates the values of X, Y, R, X’, Y’, R’, Roundness Deviation, Run out Concentricity or a shift in the center point and also the center point shift or Theta. In measuring roundness, the test object is used the Standard Mandrel which has been certified by PT. Global Quality Indonesia, by determining three points or positions, namely in the first position the amount of data is 180, in the second position the amount of data is 90 and in the third position, the amount of data is 60 with a rotating speed of 15 mm/s. The results of the reference circle can be seen in each calculation in each position, in the second position the roundness deviation values are approaching of the Mandrel.

Geometric Analysis and Systematic Design of a Reflective-Type Phase Shifter With Full 360° Phase Shift Range and Minimal Loss Variation

In this article, a geometric method, along with the concept of the reference circle, is proposed for the analysis of reflective-type phase shifter (RTPS). Comprehensive analyses of popular reflective loads, including capacitive load (CL), resonated load (RL), and $\pi $ -type load, are presented, revealing their limitations. The triple-resonating load technique is proposed to accomplish a full 360° phase shift range and suppress the loss variation. Further, a systematic design methodology for the RTPS using triple-resonating load is developed. Fabricated in 65-nm CMOS technology, the proposed RTPS occupies a core chip area of $0.076~\mu \text{m}^{2}$ . It achieves the first-ever 379° phase shift range at 29 GHz with only one control voltage. With dual-voltage control, a full 360° phase shift range with 8.3 ± 0.2 dB insertion loss is achieved. For both control methods, the return loss is better than 22.8 dB for all phase shift states.