Eccentric Circle Research Articles

Research on Center-Assisted Ring-Core Few-Mode Fiber with Eccentric Circle for Mode Degeneracy Separation in Space Division Multiplexing

Research on Center-Assisted Ring-Core Few-Mode Fiber with Eccentric Circle for Mode Degeneracy Separation in Space Division Multiplexing

Research on Non-Destructive Testing of Log Knot Resistance Based on Improved Inverse-Distance-Weighted Interpolation Algorithm

The objective of this paper is to propose a non-destructive resistance detection imaging algorithm for log knots based on improved inverse-distance-weighted interpolation algorithm, i.e., the eccentric circle-based inverse-distance-weighted (ECIDW) method, to predict the size, shape, and position of internal knots of logs; evaluate its precision and accuracy; and both lay a theoretical foundation and provide a scientific basis for predicting and assessing knots in standing trees. Six sample logs with natural knots were selected for this study. Resistance measurements were performed on the log cross-sections using a digital bridge, and resistance tomography was conducted using the improved ECIDW algorithm, which combines the azimuth search method with the eccentric circle search method. The results indicated that both the conventional inverse-distance-weighted (IDW) algorithm and the ECIDW algorithm accurately predicted the positions of the knots. However, neither algorithm was able to predict the shape of the knots with high precision, leading to some discrepancies between the predicted and actual knot shapes. The relative error (Dt1) between the knot areas measured by the IDW algorithm and the actual knot areas ranged from 18.97% to 88.34%. The relative error (Dt2) for the knot areas predicted by the ECIDW algorithm ranged from 1.82% to 74.16%. The average prediction accuracy for the knot areas using the IDW algorithm was 51.58%, compared to 72.90% using the ECIDW algorithm. This indicates that the ECIDW algorithm has higher accuracy in predicting knot areas compared to the conventional IDW algorithm. The ECIDW algorithm proposed in this paper provides a more reasonable and accurate prediction and evaluation of knots inside logs. Compared to the conventional IDW algorithm, the ECIDW algorithm demonstrates greater precision and accuracy in predicting the shape and size of knots. While the resistance method shows significant potential for predicting internal knots in logs and standing trees, further improvements to the algorithm were needed to enhance the imaging effects and the precision and accuracy of knot area and shape predictions.

ECCENTRIC: A fast and unrestrained approach for high-resolution in vivo metabolic imaging at ultra-high field MR

Abstract A novel method for fast and high-resolution metabolic imaging, called ECcentric Circle ENcoding TRajectorIes for Compressed sensing (ECCENTRIC), has been developed at 7 Tesla MRI. ECCENTRIC is a non-Cartesian spatial-spectral encoding method designed to accelerate magnetic resonance spectroscopic imaging (MRSI) with high signal-to-noise at ultra-high field. The approach provides flexible and random sampling of the Fourier space without temporal interleaving to improve spatial response function and spectral quality. ECCENTRIC enables the implementation of spatial-spectral MRSI with reduced gradient amplitudes and slew-rates, thereby mitigating electrical, mechanical, and thermal stress of the scanner hardware. Moreover, it exhibits robustness against timing imperfections and eddy-current delay. Combined with a model-based low-rank reconstruction, this approach enables simultaneous imaging of up to 14 metabolites over the whole brain at 2–3 mm isotropic resolution in 4–10 min. MRSI ECCENTRIC was performed on four healthy volunteers, yielding high-resolution spatial mappings of neurochemical profiles within the human brain. This innovative tool introduces a novel approach to neuroscience, providing new insights into the exploration of brain activity and physiology.

Investigation of Corrosion Rate and Rust Expansion Form of Segment Reinforcement for Shield Tunnel by Combined Action of Soil Loading, Chloride Ion and Stray Current

Segment reinforcement corrosion can cause bearing-capacity degradation of shield tunnel, which is unsafe for the metro operation. Therefore, a three-dimensional computational model was proposed in this paper to study the corrosion rate and rust expansion form of segment reinforcement by the combined action of soil loading, chloride ion and stray current. The results show that the arch waist segment steel corrosion rate in the middle is larger than the ends. The rust expansion form of segment reinforcement appears be an eccentric circle. The radius size and circular center are related to the non-uniform corrosion coefficient and the maximum corrosion current density.

Torque characteristics of high torque density partitioned PM consequent pole flux switching machines with flux barriers

Unique double salient structure of Permanent Magnet Flux Switching Machines (PMFSM) with both Concentrated Armature Winding (CAW) and Permanent Magnet (PM) on stator attract researcher's interest for high speed brushless application when high torque density (T den ) and power density (P den ) are the primal requirements. However, despite of stator leakage flux, high rare-earth PM usage, PMFSM is subjected to slot effects due to presence of both PM and CAW in stator and partial saturation due to double salient structure which generates cogging torque (T cog ), torque ripples (T rip ) and lower average torque (T avg ). To overcome aforesaid demerits, this paper presents Partitioned PM (PPM) Consequent Pole Flux Switching Machine (PPM-CPFSM) with flux barriers to enhance flux modulation, curtail PM usage and diminish stator leakage flux which reduces slotting effects and partial saturation to ultimately reduces T cog and T rlp . In comparison with the existing state of the art, proposed PPM-CPFSM reduces 46.53% of the total PM volume and offer T avg higher up to 88.8%, suppress T rlp maximum up to 24.8%, diminish T cog up to 22.74% and offer 2.45 times T den and P den . Furthermore, torque characteristics of proposed PPM-CPFSM is investigated utilizing space harmonics injection i.e. inverse cosine, inverse cosine with 3 rd harmonics and rotor pole shaping techniques i.e., eccentric circle, chamfering and notching. Detailed electromagnetic performance analysis reveals that harmonics injection suppressed T cog maximum up to 83.5%, T rip up to 40.72% at the cost of 4.71% T avg . Finally, rotor mechanical stress analysis is utilized for rotor withstand capability and 3D-FEA based Coupled Electromagnetic-Thermal Analysis (CETA) for thermal behavior of the developed PPM-CPFSM. CETA reveals that open space along PPM act as cooling duct that improve heat dissipation.

Identification of pipe inner surface in heat conduction problems by deep learning and effective thermal conductivity transform

PurposeThe purpose of this paper is to develop a transform method and a deep learning model to identify the inner surface shape based on the measurement temperature at the outer boundary of the pipe.Design/methodology/approachThe training process is assisted by the finite element method (FEM) simulation which solves the direct problem for the data preparation. To avoid re-meshing the domain when the inner surface shape varies, a new transform method is proposed to transform the shape identification problem into the effective thermal conductivity identification problem. The deep learning model is established to set up the relationship between the measurement temperature and the effective thermal conductivity. Then the unknown geometry shape is acquired by the mapping between the inner shape and the effective thermal conductivity through the inverse transform method.FindingsThe new method is successfully applied to identify the internal boundary of a pipe with eccentric circle, ellipse and nephroid inner geometries. The results show that as the measurement points increased and the measurement error decreased, the results became more accurate. The position of the measurement point and mesh density of the FEM model have less effect on the results.Originality/valueThe deep learning model and the transform method are developed to identify the pipe inner surface shape. There is no need to re-mesh the domain during the computation progress. The results show that the proposed method is a fast and an accurate tool for identifying the pipe inner surface.

NURBS interpolation for tangential point tracing grinding of eccentric shaft

The sine eccentric shaft is one of the most important parts for industrial robot RV reducer, and its machining quality has immediate effect on the overall device performance. The eccentric shaft X-C linkage grinding model is built based on the tangential point tracing machining principle, and the method of calculating the roundness error for eccentric circle grinding is proposed here. The research is performed on non-uniform rational B-spline (NURBS) interpolation for the coordinates’ densification of eccentric shaft X-C linkage grinding, and the algorithm process is put forward. The process of eccentric grinding is simulated and analysed by wheel inversion envelope method. The results show that the eccentric tangent point tracking model proposed is correct. Compared with the linear interpolation, NURBS interpolation can remarkably improve the accuracy of eccentric shaft tangent point tracking grinding.

Non-isotropic and Isotropic Ground Motion Prediction Models

Ground motion models have a significant role in probabilistic seismic hazard analysis. In 2013, new event-specific isotropic and non-isotropic ground motion models were introduced by Raschke (J Seismol 17(4):1157–1182, 2013), where non-isotropic behavior is applied by unit isolines. In this study, explicit equations of two different unit-isolines—an eccentric circle and an ellipse with deviation—are presented. The behavior of non-isotropic ground motion models has been described through an ideal and simple example, and the non-uniformity effect of the data recorded in different directions has been highlighted in the results of a non-isotropic ground motion model. This example clearly shows that the non-isotropic ground motion model exhibits better performance in estimating the acceleration in different directions, reducing residual variance and uncertainty. Finally, analyzing the actual data suggests that in the range near the epicenter, the results of the non-isotropic ground motion model are close to the results of other ground motion models, and as the distance increases, the difference increases, and this difference reaches twice to triple the initial value; however, analyzing the residual analysis shows that in the far distances, the non-isotropic ground motion model is also in good agreement with the data recorded at stations.

Research on the effects of double arc oil groove parameters on oil film torque in hydro-viscous drive

In order to study the influence of double arc oil groove parameters on oil film torque in hydro-viscous drive, the numerical simulation and parameterized analyzing platform were built. The flow field characteristics were carried out using CFX. The parameter analysis platform was integrated with parameterized design of grooves, numerical simulation, and design of experiment (DOE). The effects of groove parameters on output torque were analyzed. The results indicate that the output torque consists of shear torque and impact torque, and the oil film shear torque plays a more important role in total torque. The shear torque is mainly affected by coefficient of effective area and velocity distribution. The velocity distribution and dynamic pressure on sidewalls are the main influencing factors on impact torque. The effect of eccentricity and oil grooves depth on the output torque is positive, but others are negative. In addition, the eccentricity and inner diameter of eccentric circle are sensitive parameters. The effects of oil groove parameters on oil film torque are analyzed accurately using the parameterized analyzing platform that is integrated with CAD, CFX, and DOE. A new method and theoretical foundation are provided for design of complex oil grooves in hydro-viscous drive.

“A masterly though neglected work”, Boscovich’s treatise on conic sections

In this paper, we describe the genesis of Boscovich’s Sectionum Conicarum Elementa and discuss the motivations which led him to write this work. Moreover, by analysing the structure of this treatise in some depth, we show how he developed the completely new idea of “eccentric circle” and derived the whole theory of conic sections by starting from it. We also comment on the reception of this treatise in Italy, and abroad, especially in England, where—since the late eighteenth century—several authors found inspiration in Boscovich’s work to write their treatises on conic sections.

Grinding Method and Error Analysis of Eccentric Shaft Parts

RV reducer and various mechanical transmission parts are widely used in eccentric shaft parts, The demand of precision grinding technology for eccentric shaft parts now, In this paper, the model of X-C linkage relation of eccentric shaft grinding is studied; By inversion method, the contour curve of the wheel envelope is deduced, and the distance from the center of eccentric circle is constant. The simulation software of eccentric shaft grinding is developed, the correctness of the model is proved, the influence of the X-axis feed error, the C-axis feed error and the wheel radius error on the grinding process is analyzed, and the corresponding error calculation model is proposed. The simulation analysis is carried out to provide the basis for the contour error compensation.

Preparation of large size ZTA ceramics with eccentric circle shape by microwave sintering

Ultra-large zirconia toughened alumina (ZTA, mass ratio of Al2O3 and ZrO2 is 78:22) ceramics with eccentric circle shape were successfully sintered by microwave sintering with a multi-mode cavity at 2.45 GHz. The dimension of ZTA ceramics (green body) is 165 mm (outer diameter) × 25 mm (thickness). The optimized sintering temperature of microwave sintering is about 1500 °C for 30 min, and the total sintering time is about 4 h which is much shorter than that of conventional sintering. An auxiliary-heating insulation device was designed based on the principle of local caloric compensation to guarantee the intact sintered samples. With the increasing of sintering temperature, more and more microwave energy is absorbed within the entire sample, volumetric densification performs, and phases shift from m-ZrO2 phase to t-ZrO2 phase and cause Al2O3 grain growth.

Thermal performance and stress analyses of the cavity receiver tube in the parabolic trough solar collector

A light ray tracing model and a heat transfer model were built to analyse the heat flux distribution and heat transfer in a 1m cavity receiver tube with Parabolic Trough Collectors as the concentrator. The numerical methods were used to simulate the thermal stress and deformation of the receiver tube. The temperature fields of the receiver tube and the thermal stress distribution in the steel tube at the cross section and along the fluid flowing direction were presented. It is obtained from this study that non-uniform heat flux distribution is absorbed at the receiver tube outer surface due to the structure of the cavity receiver tube. Temperature fields in the steel receiver tube at the inlet and the outlet match well with the incident solar radiation. An eccentric circle temperature gradient is observed at cross section of the outlet fluid. The equivalent stress is a complex result of solar heating flux, energy transfer inside the PTC and the fluid and steel characteristics. Highest deformation is 3.1mm at 0.82m. On increasing the fluid mass flow rate, higher fluid mass flow rate results in higher equivalent stress along the absorber tube.

Multipoint Recursive Sequential Three-point Method for On-machine Roundness Measurement

A newtime-domain method, which is called the multipoint recursive sequential three-point method, is proposed for on-machine roundness measurement of cylindrical workpiece. It has the following features: (i) assuming no prior knowledge, (ii) providing more information of the roundness profile than the sequential three-point (S3P) method, (iii) reconstructing the roundness profile including sharp features. In the proposed method, recursion of difference equations in the time domain is used to determine the relationships between different data groups instead of the fast Fourier transform (FFT) algorithm andthe inverse fast Fourier transform(IFFT) algorithm, which is simpler and capable of expressing the discrete roundness profile with sharp features correctly. In the meantime, the establishing conditions of the proposed method are given by theoretical analysis. The eccentric circle, resulting from the inaccurate initial value of the recurrence equation, is removed by the least-squares method. Theoretical analysis and simulations have been conducted to verify the effectiveness of the proposed method.

S波段束流相位探测腔与偏心式波导耦合预聚束器的设计

S波段束流相位探测腔与偏心式波导耦合预聚束器的设计

Design of a beam phase cavity and a waveguide coupled eccentric circle structure prebuncher in S-band

A new waveguide-coupled prebuncher and a new beam phase cavity working at S-band are designed. For increasing the power capacity, the waveguide coupling mechanism is used instead of the traditional coaxial ring coupling for the prebuncher. An eccentric circle structure of the cavity is adopted to solve the problem of an asymmetric electrical field along the radial direction caused by the introduction of the waveguide coupling window, which improves the beam quality on high beam current. The measurement results of a coupling coefficient of 1.73, an unloaded quality factor of 2195 as well as a variable frequency range from 2 854.55 MHz to 2 856.9 MHz are got in the final prototype of prebuncher. For measuring the timing between beam and RF pulse in order to compensate the input power with the high beam current, a beam phase cavity is chosen to be the on-line equipment for the real-time measurement of beam phase. The beam phase cavity has a rotational symmetrical structure, and two coaxial coupling rings are used to extract the inducted signal from the beam, which will be used as the reference signal of the phase-controlling system. The prototype of beam phase cavity has a measurement result of an unloaded quality factor of 2392, a 3 dB bandwidth of 2.05 MHz as well as a variable frequency range from 2 805.45 MHz to 2 809.45 MHz. The measurement results match well with the simulation results. ©, 2015, Editorial Office of High Power Laser and Particle Beams. All right reserved.

From Newton’s bucket to rotating polygons: experiments on surface instabilities in swirling flows

AbstractWe present an experimental study of ‘polygons’ forming on the free surface of a swirling water flow in a partially filled cylindrical container. In our set-up, we rotate the bottom plate and the cylinder wall with separate motors. We thereby vary rotation rate and shear strength independently and move from a rigidly rotating ‘Newton’s bucket’ flow to one where bottom and cylinder wall are rotating oppositely and the surface is strongly turbulent but flat on average. Between those two extremes, we find polygonal states for which the rotational symmetry is spontaneously broken. We investigate the phase diagram spanned by the two rotational frequencies at a given water filling height and find polygons in a regime, where the two frequencies are sufficiently different and, predominantly, when they have opposite signs. In addition to the extension of the family of polygons found with the stationary cylinder, we find a new family of smaller polygons for larger rotation rates of the cylinder, opposite to that of the bottom plate. Further, we find a ‘monogon’, a figure with one corner, roughly an eccentric circle rotating in the same sense as the cylinder. The case where only the bottom plate is rotating is compared with the results of Jansson et al. (Phys. Rev. Lett., vol. 96, 2006, art. 174502), where the same size of cylinder was used, and although the overall structure of the phase diagram spanned by water height and rotational frequency is the same, many details are different. To test the effect of small experimental defects, such as misalignment of the bottom plate, we investigate whether the rotating polygons are phase locked with the bottom plate, and although we find cases where the frequency ratio of figure and bottom plate is nearly rational, we do not find phase locking. Finally, we show that the system has a surprising multistability and excitability, and we note that this can cause quantitative differences between the phase diagrams obtained in comparable experiments.

Kinematics and Dynamics Analysis of Eccentric Circle Cam Mechanism

Geometric methods and mechanical principles were employed to study the kinematic variables and dynamic variables of eccentric circle cam mechanism, and their formulae were also given. The deductions show that the linear velocity and the acceleration of the driven member and the driving moment are all functions of the rotation angleand the rotation angular velocity of the cam, the numerical results of the given example verify the conclusions.

Limitations of Methods: The Accuracy of the Values Measured for the Earth's/Sun's Orbital Elements in the Middle East, A.D. 800–1500, Part 1

(ProQuest: ... denotes formulae omitted.)(ProQuest: ... denotes non-USASCII text omitted.)The present paper deals with the methods proposed and the values achieved for the eccentricity and the longitude of apogee of the (apparent) orbit of the Sun in the Ptolemaic context in the Middle East during the medieval period. The main goals of this research are as follows: first, to determine the accuracy of the historical values in relation to the theoretical accuracy and/or the intrinsic limitations of the methods used; second, to investigate whether medieval astronomers were aware of the limita- tions, and if so, which alternative methods (assumed to have a higher accuracy) were then proposed; and finally, to see what was the fruit of the substitution in the sense of improving the accuracy of the values achieved.In Section 1, the Ptolemaic eccentric orbit of the Sun and its parameters are introduced. Then, its relation to the Keplerian elliptical orbit of the Earth, which will be used as a criterion for comparing the historical values, is briefly explained. In Section 2, three standard methods of measurement of the solar orbital elements in the medieval period found in the primary sources are reviewed. In Section 3, more than twenty values for the solar eccentricity and longitude of apogee from the medieval period will be classified, provided with historical comments. Discus- sion and conclusions will appear in Section 4 (in Part 2), followed there by two discussions of the medieval astronomers' considerations of the motion of the solar apogee and their diverse interpretations of the variation in the values achieved for the solar eccentricity.1. IntroductionPtolemy, in Almagest ΠΙ, presented a solar model consisting of an eccentric circle whose centre is displaced from the centre of the Earth by an amount of eccentricity e = TO expressed in terms of an arbitrary length R-60 for the radius of the eccentre (Figure 1). The Sun revolves on the eccentre around the Earth but its motion is uniform with respect to the centre of eccentre, and completes one revolution in a tropical year TY (counted in days), i.e., with a mean motion of ? = 360/7T. Due to the eccentricity of its orbit, the true longitude of the Sun (i.e., its longitude as seen from the Earth T) does not match its mean longitude (its longitude as it appears from the centre O of uniform motion) except at apogee (A) and perigee (Π). The difference between the two, called the 'equation of centre' q, is defined as a one-variable function of the solar mean anomaly c, which is the difference between its mean longitude and the longitude Aap of the apogee:Therefore, the solar eccentric model has three parameters (TY or ?, e, and Aap) but only one anomaly due to its eccentricity.Ptolemy assumes that all three parameters are constant.' Since, at least, the latter part of the ninth century, the Middle Eastern astronomers found (cf. Tables 1 and 2) that the longitude of the solar apogee increases with the passage of time and they (seemingly, first of all, the Banu Musa or Thabit b. Qurra and Habash) assumed its rate of change to be the same as the rate of precession, as is the case with the motion of the apogee of the planets in the Ptolemaic context (the relevant discussion will be presented in Section 4). Also, different values for e and TY were observed during the medieval period. The variety in the values obtained for the two was so large that, for example, Copernicus in the prologue of his De revolutionibus complains that [the astronomers] are uncertain of the motion of the Sun and Moon to such an extent that they cannot demonstrate or observe a constant magnitude for the tropical year,2 while BirunT was forced to resolve his readers' worries about the huge differences in the values measured for the solar eccentricity over a short period (see Section 4).In fact both e and TY are changing with the passage of time, e decreases slowly by the average amount of 4. …

Design of Logarithmic Spiral Surface Wedge Block Backstop and Dynamic Simulation

A new contact backstop with logarithmic spiral surface wedge block is pointed out.Based on the existing eccentric circle surface wedge block,the logarithmic spiral surface wedge block is designed by the curve fitting method.The simulation model of the backstop is established with the Pro/E software.The three-dimensional model is imported into ANSYS/LS-DYNA software for dynamic simulation analysis to obtain the stress characteristics during the backstop process.By comparing the contact stress of the two wedge block,results show that the new backstop has much smaller stress,smoother process and better performance than the traditional backstop with eccentric circle surface wedge block,which will offer theoretical basis for the production of the new backstop.