Parallel Straight Lines Research Articles

Region-Line Association Constraints for High-Resolution Image Segmentation

Man-made objects, including buildings and roads, often feature straight boundaries. Specific shape features, including parallel boundaries (e.g., roads and buildings) and perpendicular corners (e.g., buildings), are strong structural clues for distinguishing man-made objects from natural objects. In this study, such observations are implemented in remote-sensing image segmentation. Several region-line association constraints are proposed, including the parallel straight line (PLSL) neighborhood, the perpendicular straight line (PPSL) neighborhood, and the PLSL zone. A region-merging process with these structural constraints is appended to the hard-boundary-constrained segmentation method (HBC-SEG), which is a multiscale image segmentation method. Results show that, compared with HBC-SEG, the proposed method presents a significant decrease in oversegmentation errors (measured by recall ratio r) and an insignificant increase in undersegmentation errors (measured by precision p). As a result, measure m 2 , which synthetically evaluates undersegmentation and oversegmentation errors, increases significantly. The improved method helps obtain complete objects, thus facilitating feature extraction and image classification for object-based image analysis.

Полевая аналитическая модель магнитоэлектрического вентильного двигателя

Phenomena occurring in a switched magnetoelectric motor can be considered in its non-magnetic gap, which should also embrace the layer of a high-energy magnet. Complex periodic potential functions serve as a mathematical basis for analytically solving the Dirichlet problem in a non-magnetic gap having the shape of an infinite horizontal strip with boundaries confined by two parallel straight lines. The imaginary components of the complex potential functions at the boundaries of the above-mentioned strip represented by trigonometric Fourier series are the known scalar magnetic potentials of the stator winding and permanent magnets on the rotor, which are the magnetic field sources.A comparatively large width of the considered strip results in that the magnetic field in it is two-dimensional in nature due to the presence of permanent magnets. The boundary sources of magnetic field can be used for generating additional magnetic fields corresponding to the stator’s virtual teeth. The geometrical structure of the virtual teeth, which determines the amplitudes of tooth magnetic inductions, can be accurately taken into account using conformal transformation of a non-uniform air gap into an infinite strip or approximately based on the specific permeance method.

Аналитическая модель магнитного поля в ярме магнитоэлектрического вентильного двигателя

The processes occurring in a switched permanent magnet motor can be considered in the nonmagnetic gap. The high-energy magnet layer should also be related to this gap. Complex periodic potential functions serve as the mathematical basis for analytically solving the Dirichlet problem both in the nonmagnetic gap represented by an infinite horizontal strip with the boundaries delineated by two parallel straight lines and in similar strips with homogeneous magnetic permeability of the stator and rotor yokes. The imaginary components of the complex potential functions at the boundaries of the above-mentioned strips represented by trigonometric Fourier series are the known scalar magnetic potentials of magnetic field sources, namely, the stator winding and permanent magnets on the rotor. To fulfill the magnetic field boundary conditions in the yoke belts, a procedure for reducing these fields to the magnetic field in the air gap is implemented by means of special coefficients for each of the harmonic components in the magnetic induction radial and tangential components. The value of magnetic induction uniformly distributed in the yoke body is selected from the maximal magnetic induction inside the yoke without taking into account the induction impulse values at the boundaries with the air gap. Graphs showing the distribution of magnetic fields in the yokes corresponding to the obtained analytical correlations are given.

Analysis of the Dynamics of Piecewise Linear Memristors

In this paper, we consider a class of flux controlled memristive circuits with a piecewise linear memristor (i.e. the characteristic curve of the memristor is given by a piecewise linear function). The mathematical model is described by a discontinuous planar piecewise smooth differential system, which is defined on three zones separated by two parallel straight lines [Formula: see text] (called as discontinuity lines in discontinuous differential systems). We first investigate the stability of equilibrium points and the existence and uniqueness of a crossing limit cycle for the memristor-based circuit under self-excited oscillation. We then analyze the existence of periodic orbits of forced nonlinear oscillation for the memristive circuit with an external exciting source. Finally, we give numerical simulations to show good matches between our theoretical and simulation results.

Longitudinal vibrations in electrodynamics suspension system

A system of electrodynamics suspension (EDS) in which the primary source of the field (electromagnet) is moving in a straight line parallel to the surface of the track and his speed makes small oscillations around a mean value is considered. The approximation of an infinitely wide track is allowed, the primary source of the electromagnetic field acts as a so-called periodic source. This problem is a special case of the general problem of the rate of the transients in the EDS, caused by uneven movement. Named speed determines the amount of time constants that make sense, and in contrast to the simplest case of a one-dimensional linear oscillator system EDS characterizes not by a single time constant, but by infinite set of values. The method of calculation of levitation and braking forces acting in this oscillatory motion on carriage electromagnet is worked out and simple explicit formulas to calculate these forces are got. On the basis of the calculation of time constants the rate of the transients in the EDS, caused by uneven movement is assessed. The calculations of levitation and braking forces according to the developed technique are made. The results obtained allow to delimit the applicability of the so-called quasi-static approach which consists in that the irregularly moving of electromagnet replaced by concurrent, i.e., the same electromagnet, similarly disposed and uniformly moving with a speed coinciding with the instantaneous value of the actual longitudinal speed of the electromagnet. In the quasi-static approximation, fluctuations of levitation and braking forces are in phase with oscillations of speed and amplitude of the forces oscillations do not depends on the frequency of the speed oscillation. The calculations show that in reality there is phase shift between the forces oscillations and speed oscillations depending on the frequency. Amplitudes of levitation and braking forces oscillations also depend on the oscillation frequency, and for each speed value a resonance frequency exists at which they reach the maximum value.

Compression and expansion properties of filter cake accompanied with step change in applied pressure in membrane filtration

Abstract In order to well elucidate the true nature of filter cake formed in membrane filtration of aqueous colloids, the transient flux decline behaviors accompanied with step-up and step-down changes in the applied filtration pressure during the course of constant pressure filtration were investigated by carrying out both microfiltration experiments of kaolin slurry and ultrafiltration experiments of nanosilica sol under various experimental conditions. When the applied pressure was increased stepwise, for each colloid the plot of the reciprocal filtration rate vs. the filtrate volume per unit membrane area referred to as the Ruth plot tends to approach a linear relationship obtained in constant pressure filtration conducted under the increased pressure condition from the beginning of filtration, after a transient period when the preformed cake under the initial pressure was compressed. In contrast, in the case of the step-down change in the applied pressure, when the volume of the preformed cake is adequate, the plot after a transient period tends to approach a higher straight line parallel to a linear relationship for constant pressure filtration conducted under the decreased pressure condition from the beginning. Such flux decay behaviors were well described by the expression having two constants: one is the constant representing the final filterability for the preformed filter cake, and the other is the rate constant describing the change rate in the structure of preformed cake resulting from a pressure jump. Moreover, the influence of experimental conditions on the cake reversibility and the rate constant was revealed both for kaolin slurry and for nanosilica sol.

Solution to the Dirichlet problem for an infinite strip domain with holes

The aim of this work is to develop the method of functional equations to boundary value problems for a strip with mutually disjoint circular holes. The boundary of the strip domain, two parallel straight lines, is treated as two touching circles on the extended complex plane. The general algorithm is effectively implemented to computation of the local flux around holes.

Fresnel-zone-like moiré patterns: optical generation and plasmonic modulation with proposed surface profilometry application

A novel scheme of surface plasmon resonance-assisted Fresnel-zone-like moire pattern generation has been theoretically and experimentally investigated in a dual shearing environment. Lateral shear is followed by radial shear with the help of a Wollaston prism and a birefringent lens, respectively. The superposition of two contrast-reversed Fresnel-zone-like patterns (FZP) with parallel equi-spaced straight lines interestingly generates the displaced replication of the original FZP, particularly when the lateral shear is of a sufficient amount. Modulation due to plasmonic excitation has also been observed on such patterns for two different substrate materials. Binary representation of radially sheared images has been illustrated and further utilized for the proposed non-contact surface profilometry of metal coatings.

Thickness-dependent electronic structure in ultrathinLaNiO3films under tensile strain

We investigated electronic-structure changes of tensile-strained ultrathin $\mathrm{LaNi}{\mathrm{O}}_{3}$ (LNO) films from ten to one unit cells (UCs) using angle-resolved photoemission spectroscopy (ARPES). We found that there is a critical thickness ${t}_{c}$ between four and three UCs below which Ni ${e}_{g}$ electrons are confined in two-dimensional space. Furthermore, the Fermi surfaces (FSs) of LNO films below ${t}_{c}$ consist of two orthogonal pairs of one-dimensional (1D) straight parallel lines. Such a feature is not accidental as observed in constant-energy surfaces at all binding energies, which is not explained by first-principles calculations or the dynamical mean-field theory. The ARPES spectra also show anomalous spectral behaviors, such as no quasiparticle peak at the Fermi momentum but fast band dispersion comparable to the bare-band one, which is typical in a 1D system. As its possible origin, we propose 1D FS nesting, which also accounts for FS superstructures observed in ARPES.

Efficient Lane Detection Based on Spatiotemporal Images

In this paper, we propose an efficient method for reliably detecting road lanes based on spatiotemporal images. In an aligned spatiotemporal image generated by accumulating the pixels on a scanline along the time axis and aligning consecutive scanlines, the trajectory of the lane points appears smooth and forms a straight line. The aligned spatiotemporal image is binarized, and two dominant parallel straight lines resulting from the temporal consistency of lane width on a given scanline are detected using a Hough transform, reducing alignment errors. The left and right lane points are then detected near the intersections of the straight lines and the current scanline. Our spatiotemporal domain approach is more robust missing or occluded lanes than existing frame-based approaches. Furthermore, the experimental results show not only computation times reduced to as little as one-third but also a slightly improved rate of detection.

Invited Commentary

Invited Commentary

One class of generalized boundary value problem for analytic functions

In this paper, a boundary value problem for analytic functions with two unknown functions on two parallel straight lines is studied, the general solutions in the different domains as well as the conditions of solvability are obtained in class $\{1\}$ , and the behaviors of solutions are discussed at $z=\infty$ and in the different domains, respectively. Therefore, the classic Riemann boundary value problem is extended further.

Modeling a Rotating Circle Thermal Field with a Thermal Source on the Edge

The task of circle heating by a thermal source moving along the circle edge with a constant angular velocity is considered. The circle is a cylinder in which the temperature is the same on each straight line parallel to a cylinder axis, i.e. at each point the temperature is a function of time, distances from a cylinder axis and a polar angle. The computing schemes based on numerical methods are usually used for the similar tasks solution. Explicit schemes solve one equation for each time step of each spatial knot. Implicit schemes solve a system of linear algebraic equations for each time step. The number of equations is connected with the number of spatial knots. In the first case the process is rather simple, but the scheme is not absolutely steady. For this scheme the step order by time should not exceed the square of step order by coordinate. In the second case the scheme is absolutely steady, but it is necessary to solve a complex system of equations, especially for a multidimensional case. The purpose of this work is to use absolutely steady differential-difference explicit scheme based on linear equation application with partial derivatives of the first order which analytical solution (an explicit formula) is known.

The Transmanubrial Approach for Cervicothoracic Junction Lesions : Feasibility, Limitations, and Advantages.

ObjectiveWe report on the technical feasibility and limitations of the transmanubrial approach for cervicothoracic junction (CTJ) lesions and emphasize the advantage of bisecting the upper part of the manubrium in an inverted Y-shape.MethodsThirteen patients who underwent the fourteen transmanubrial approach for various CTJ lesions were enrolled during 2005-2014. For the evaluation of the accessibility for the CTJ lesion, we analyzed the two parallel line defined as a straight line parallel to the inferior and superior plateau of the upper and lower healthy vertebrae, the angle of the two parallel lines and the distance from the sternal notch to lines at the sternum on preoperative magnetic resonance images. Surgical limitations and perspectives, as well as postoperative clinical outcomes were evaluated retrospectively.ResultsThe CTJ lesions were six metastases, three primary bone tumors, two herniated discs, and one each of a traumatic dislocation with syrinx formation and tuberculous spondylitis and ossification of the posterior longitudinal ligament. If two parallel lines pass below the sternal notch, the manubriotomy should be inevitably performed. The mean preoperative Visual analogue scale score was 8 (range, 5-10), which improved to 4 (range, 0-6) postoperatively. Seven cases showed an increase in Frankel score postoperatively.ConclusionThe spatial relationship between the sternal notch and the two parallel lines to the lesion was rational to determine the feasibility of manubriotomy. The transmanubrial approach for CTJ lesions can achieve favorable clinical outcomes by providing direct decompression of lesion and effective reconstruction.

Monitoring of GMAW Weld Pool From the Reflected Laser Lines for Real-Time Control

Controlling the welding process by monitoring the weld pool surface becomes more and more popular in robotic arc welding. In this paper, we propose a monitoring system to infer the P-gas metal arc welding (GMAW) weld pool geometry from the reflected laser lines, which are projected onto the specular weld pool and reflected onto a diffusive plane. The parallel straight lines are distorted according to the shape of the weld pool and thus contain the weld pool's shape information. Accurately computing the equations of the imaged laser lines in the world coordinate system is critical for the subsequent weld pool shape estimation. This paper focuses on accurately segmenting and identifying the reflected laser lines and novel image processing algorithms are proposed to fulfill this specific task. Experimental results verified the effectiveness of the proposed algorithms.

Preparation and Characterization of Lead-Free (K0.5Na0.5)NbO3-LiNbO3 and (K0.5Na0.5)NbO3-LiTaO3 Ferroelectric Single Crystals

Lead-free (K0.5Na0.5)NbO3-LiNbO3 (KNN-LN) and (K0.5Na0.5)NbO3-LiTaO3 (KNN-LT) ferroelectric single crystals, with the dimensions of 11 ´ 11 ´ 5 mm3 and 5 ´ 5 ´ 3 mm3, were grown successfully using the top-seeded solution growth (TSSG) method, respectively. The crystal structures were analyzed by means of X-ray diffraction, showing orthorhombic symmetry for KNN-LN single crystals and coexistence of orthorhombic and tetragonal symmetry for KNN-LT single crystals at room temperature. The orthorhombic-tetragonal (TO-T) and tetragonal-cubic (TC) phase transition temperatures are 195 °C and 420 °C for the KNN-LN single crystals, and 130 °C and 280 °C for KNN-LT single crystals, respectively. The remnant polarization (Pr) is 27.8 μC/cm2 with a coercive field (Ec) of 17 kV/cm for KNN-LT single crystals. The two single crystals showed 90° domains with layers in (parallel) straight lines, while KNN-LT single crystals have a larger domain region. The actual stoichiometry deviates easily from the original composition in the process of crystal growth, thus, an appropriate nominal composition and optimized crystal growth method is desired to get high-quality crystals in the future.

Line structured light vision sensor calibration using parallel straight lines features

Line structured light vision sensor (LSLVS) calibration is to establish the relation between the camera and the light plane projector. This paper proposes a geometrical calibration method for LSLVS via three parallel straight lines on a 2D target. The approach is based on the properties of vanishing points and lines. During the calibration, one important aspect is to determine the normal vector of the light plane, another critical step is to obtain the distance parameter d of the light plane. In this paper, we put the emphasis on the later one. The distance constraint of parallel straight lines is used to compute a 3D feature point on the light plane, resulting in the acquisition of the parameter d. Thus, the equation of the light plane in the camera coordinate frame (CCF) can be solved out. To evaluate the performance of the algorithm, possible factors affecting the calibration accuracy are taken into account. Furthermore, mathematical formulations for error propagation are derived. Both computer simulations and real experiments have been carried out to validate our method, and the RMS error of the real calibration reaches 0.134mm within the field of view 500mm×500mm.

A Calibration Method for High Precision Vision Measurement System

In order to realize precision measurement for the computer vision measurement system, a system comprehensive calibration method based on straight line imaging characteristics is proposed. The method uses parallel straight line edges of general 00 level gauge groups to comprehensively calibrate the measurement system. It establishes the calibration function that describes the corresponding relationship between the imaging point location and space point position, and then determines the coefficient of the calibration function according to the linear characteristic of gauge block measurement surface edges imaging. This method is simple to operate and is easy to realize and has good versatility. It can comprehensively correct all kinds of system errors such as the optical distortion, the perspective error, the sensor position error and location error of edge detection algorithm. Repeated measurement experiments for the gauges show that the precision of the measurement system can reach by means of this calibration method.

Measurement of clivus-axial angle and correlation between clivus-axial angle and cervico-medullary angle in Chinese population

Objective To measure the clivus-axial angle (CAA) of Chinese,provide a normal value,and explore the correlation between CAA with cervico-medullary angle (CMA).Methods The CAA was measured on the CT of cervical spine in 225 Chinese with normal cranio-vertebral junction (CVJ).Both the CAA and the CMA were measured on the MRI of cervical spine in 117 subjects.All measurements were performed under a bone window (window level,300 Hu; window width,1 000 Hu) with an accuracy of 0.01°.A regression analysis was used for analyzing the correlation between CAA and CMA.The angle between the clivus plane and the straight line parallel to that of the posterior margin of the C2 vertebral body was defined as CAA; moreover,the angle between the strajght line parallel to the ventral side of the cervical spinal cord and the straight line parallel to that of the ventral side of the medulla oblongata was defined as CMA.Two experienced spinal surgeons performed the measurements.The CAA and CMA were measured three times,and the mean value was considered as the result.Results The CAA of 225 subjects was 133.52°-172.16° (156.93°±6.53°).The 95％ confidence interval was 145.10°-170.19° in male and 142.67°-168.47° in female.If the patients were divided into five groups according to their age,a comparison of these groups showed that there were no significant differences among the groups with respect to CAA.It showed that there was consistency between the CAAs measured with MRI and CT.The CMA for 117 patients ranged from 130.38° to 168.75° with a mean value of 154.17°±6.54°,and its 95％ confidence interval ranged from 141.35° to 166.99°.If the patients were distributed according to their gender or to their age,there were no significant differences among the groups.The relationship between CAA and CMA was linearity,and the regression coefficient was as high as 0.95 (P=0.007).Conclusion The normal CAA of Chinese is from 133.52° to 172.16°.The 95％ confidence interval goes from 145.10° to 170.19° in male,and 142.67° to 168.47° in female,close to CMA.It is valuable for measuring the compression of spinal cord,which can be accessed easily during the procedure. Key words: Cranial fossa, posterior; Axis; Medulla oblongata; Spinal Cord; Tomography, X-ray computed; Magnetic resonance imaging

General steady-state solution for thermo-poroelastic material

This study established a general steady-state solution in the z-convex domain (the domain boundary must have at most two points of intersection with any straight line parallel to the z-axis) for thermo-poroelastic materials. Two displacement functions to simplify the equations governing elasticity, pressure, and temperature fields into one Laplace equation and four eighth-order partial–differential governing equations are introduced. The general solutions of displacement, pressure, and temperature are derived in terms of five harmonic functions using the generalized Almansi’s theorem and considering equivalent substitution. The relationship between the Boussinesq–Galerkin general solutions and the general solution proposed in this paper is discussed without considering the changes in pore pressure and temperature to prove the completeness of the latter.