Hardly a Straight Line

It has always been an important low-level operation to extract edges from images in the fields of computer vision and image procession, in which straight line extraction is typical and representative. Because most man-made spatial objects, e.g. buildings, roads, etc. often take on near straight-line boundaries, extracting straight lines is often the first step to extract these targets. Straight lines can then be looked as the elementary units for other higher level image interpretations. In this paper, a straight line extraction method combining edge detection and depth-first searching on the vector line layer is proposed and applied to extract runways of airports. The steps include: 1) edges are found with the Canny operator and vectorirzed. The reason to use the Canny operator is because it is designed to be an optimal edge detector, which gives very good results on detecting step or slop like edges. It takes as input a grey scale image, and produces as output an image showing the positions of tracked intensity discontinuities. After this operation, we then vectorize the edge points to be a vector layer with edge tracing.2) With the vector-formatted edge lines, the straight line searching can then be carried out. In order to complete this, topology between arcs should be cleaned and rebuilt, which includes the deletion of repetitive, one-node arcs, and splitting on the intersections, etc. 3) Straight lines are detected with the depth-first searching strategy. With the rebuilt topology, we can easily obtain the begin, end nodes of every line. If the distances of its all vertices to the line connecting the begin, end nodes of an arc are less than some pre-defined threshold, it could be looked as a 'straight line' and extracted. Besides, we are certainly only interested in the straight lines with lengths larger than certain threshold, thus a minimum length threshold should be specified to delete these very short lines. In the searching of straight lines, some arcs should be grouped as a single straight line; some un-straight lines should be split to extract its straight parts. The suitable straight lines are outputted to a vector layer after being reselected and re-grouped, with distinguishing short, long isolating, long not isolating straight lines. With all these steps, we can get the initial straight vector line layer. 4) To these lines with small interspaces but locate on a single straight line, we use a simple but effective connecting step to 'fill' the gaps. Starting from the vector layer and with the operations of broken line connecting and parallel line detection, the main airport runway can be well extracted, which helps us to locate and recognize airports from high spatial remotely sensed imagery.

A scheme is proposed for generating multiphase oscillatory signals in millimeter-wave frequencies based on the dynamics of a traveling pulse developed in a closed transmission line periodically loaded with resonant-tunneling diodes (RTDs) that is coupled with several straight RTD lines. When supplied with an appropriate voltage at the end of an RTD line, a pulse edge is shown to exhibit a spatially extended limit-cycle oscillation on the line. We consider the case where several RTD lines are connected halfway to a closed one at even intervals. In this case, the oscillatory edge developed in each straight RTD line is mutually synchronized such that a pulse-shaped rotary traveling wave develops on the closed RTD line. The oscillating edge on each straight line is also synchronized with the traveling pulse on the closed line, such that the leading edge of the traveling pulse on the closed line and the forward edge on the straight line pass the cross point simultaneously. As a result, when N L straight lines are connected to the closed line, the phase difference between two adjacent oscillatory edges becomes 2π/N L . On the other hand, the trailing edge of the traveling pulse at the cross point breaks the voltage wave on the straight line into two pieces, one of which travels forward to form a solitary wave and the other of which travels backward to reach the input end, where it is reflected and starts to travel forward and this forward moving edge is supposed to be synchronized with the leading edge of the traveling pulse. It means that a back-and-forth edge and a forward-moving solitary wave develop periodically on each straight line. Because the time required for the traveling pulse to go around the closed line must be coincident with the period of the edge oscillation on each straight line, a unique traveling pulse cannot synchronize with each oscillating edge when the cell size of the closed line becomes large, resulting in the development of multiple traveling pulses on the closed line. In this paper, the design criteria are discussed concerning the connecting point between the straight and closed lines, the number of straight lines, and the size of the closed line. In addition, we describe several measurement results that validate the essential properties of the traveling pulse and then show several results of full-wave analysis of a monolithically integrated RTD line.

Mixed-model U-shaped assembly lines: Balancing and comparing with straight lines with buffers and parallel workstations

This paper proposes a lane detection method based on the constraint Hough Transform double edge extraction. Firstly, the image of the road is grayed out and dealt with the lane line area extraction process based on the lane width feature and color feature. For grayscale images, the Canny edge detection operator is used to obtain the lane line edge information. Then the lane line features are extracted through the lane line edge information and the lane line area information. For the straight lane line, the Hough transform based on the polar angle and polar radius constraints is used to obtain the double edges of the lane lines, and straight line points are used to determine the end points and starting points of the straight lane lines to complete the straight line fitting. For the curve, the near-field part is a straight line, the far-field is a curve, and the straight part adopts the detection method of the straight lane line, and the characteristic points of the curve are searched in the lane line characteristic diagram. Finally, the curve is fitted by a parabola. Experiments show that the lane detection using the double-edge extraction method is fast and accurate.

When pressure buildup data are plotted on semilogarithmic coordinates, several straight lines can be obtained, even though theoretical considerations indicate that only one straight line should appear. Thus, an engineer is faced with the problem of choosing one of these straight lines to estimate formation permeability, average reservoir pressure, and flow efficiency. During the past few years, methods have been suggested whereby an engineer may extricate himself/herself from this quandary. In this paper we consider a few field examples which demonstrate the correct procedure one may follow to choose a straight line. Methods to identify after flow, the presence of a fracture, and the existence of boundaries are discussed. The advantages and limitations of the various methods are also discussed. Introduction The pressure buildup test is the most common of transient well tests. The procedure, as shown in Figure 1, consists of flowing the well at a constant rate, q, for a time, t, and then shutting-in the well for a time, delta t, while measuring the bottom-hole pressure during the shut-in period. pressure during the shut-in period. There are a substantial number of papers written on the subject of pressure transient analysis. The objective of this paper is to promote the combined and simultaneous use of the traditional semilogarithmic techniques with the newer log-log method. The two best approaches of pressure buildup analysis are the Horner and the Miller, Dyes, Hutchinson methods. The Horner method involves plotting the bottom-hole shut-in pressure, VS. plotting the bottom-hole shut-in pressure, VS. the logarithm of the time ratio (tp + delta t)/delta t, while the Miller-Dyes-Hutchinson (MDH) procedure involves plotting pws vs. the logarithm of delta t. Here, tp is plotting pws vs. the logarithm of delta t. Here, tp is the producing time prior to shut-in and delta t is the shut-in time. These methods show that such a graph should yield a straight line, whose slope is inversely proportional to the permeability-thickness product, proportional to the permeability-thickness product, kh, as illustrated in Figure 2. Other parameters such as wellbore damage or stimulation, average reservoir pressure, and distance to the nearest boundary can be pressure, and distance to the nearest boundary can be obtained from a Horner or MDH graph. The main problem in analyzing pressure buildup data is that, often, when buildup data are plotted on semilogarithmic coordinates, several straight lines can be obtained, even though theoretical considerations indicate that only one straight line should appear. Thus, the engineer is faced with the problem of choosing one of these straight lines for analysis, or concluding that the reservoir is heterogeneous; in the latter case, the conventional procedures suggested in the literature are not applicable. The appearance of several straight lines, or even a smooth curve, may be due to near wellbore effects such as afterflow, and/or fractures intersecting the wellbore. This paper is concerned with the identification of the proper straight line, if such a straight line exists. The methods suggested here should also be helpful in answering such questions as:Has the test run long enough to get the straight line needed to obtain formation permeability, skin factor, and average reservoir pressure?Is the reservoir heterogeneous?Is a more complex procedure or reservoir simulator (computer approach) needed to analyze the data?What special precautions should be taken or what improvements can be made when the test is rerun at a later date? PRELIMINARY CONSIDERATIONS PRELIMINARY CONSIDERATIONS To establish a basis for discussion, let us consider two gas well tests shown in Figure 3 where buildup data have been plotted as suggested by Horner. Since these are gas wells, we use p2, rather than p. From Figure 3, we see two similarities between the two graphs. First, two well-defined straight lines can be seen on both tests—a straight line with a shallow slope, followed by a second straight line with a much steeper slope. Either line on each test could be used to estimate formation permeability. Secondly, on both tests the slope of the second straight line is twice that of the first.

PRESSURE TRANSIENT FIELD DATA SHOWING FRACTAL RESERVOIR STRUCTURE

Conventional pressure transient models strictly apply to areally homogeneous reservoirs. Yet, core and log data indicate this assumption is often not justified. This paper describes a model for heterogeneous reservoirs and supporting field data from the Grayburg/ San Andres formations in southeastern New Mexico. Conventional models fail to match these field data. Instead, a model for a heterogeneous reservoir with a fractal structure provides a quantitative analysis. The fractal reservoir model reduces to the conventional solution in the case of a homogeneous reservoir.

The loci (L) equally spaced from a sphere and a straight line, and from a conic surface and a plane, are considered. The following options have been considered. The straight line passes through the center of the sphere (a = 0), at the same time completely at spheres’ positive radiuses a surface of rotation is obtained, forming which the parabola is, and a rotation axis – this straight line. The parabola’s top forms the biggest parallel on the site points of intersection of the parabola’s forming with the rotation axis. Let's call such paraboloid a perpendicular paraboloid of rotation. The straight line crosses the sphere, but does not pass through the center (0 < a < R/2) – a perpendicular paraboloid, at that the surface is also completely obtained at radiuses’ positive values. The straight line is tangent to the sphere (a = R/2) – a surface which projections are parabolas, lemniscates and circles, and a piece from a tangency point to the sphere center – at radiuses positive values; a beam from the sphere center, perpendicular to this straight line – at radiuses negative values, at that the beam and the piece belong to one straight line. The straight line lies out of the sphere (α > R/2) – two different surfaces, having the general properties with a hyperbolic paraboloid, are obtained, one of which is obtained at radius positive values, and another one – at radius negative values. It has been noticed that loci, equally spaced from a sphere and a straight line, and from a cylinder and a point, coincide at equal radiuses and distances from axes to points and straight lines if to take into account the surfaces obtained both at positive, and negative values of radiuses. Locus, equally spaced from the conic surface of rotation and the plane, are two elliptic conic surfaces which in case 7.4.1 degenerate in the conic surfaces of rotation. In cases 7.4.3 and 7.4.4 one elliptic conic surface degenerates in a plane and a parabolic cylinder respectively.

Increased use of digital imagery has facilitated the opportunity to use features, in addition to points, in photogrammetric applications. Straight lines are often present in object space, and prior research has focused on incorporating straight–line constraints into bundle adjustment for frame imagery. In the research reported in this paper, object–space straight lines are used in a bundle adjustment with self–calibration. The perspective projection of straight lines in the object space produces straight lines in the image space in the absence of distortions. Any deviations from straightness in the image space are attributed to various distortion sources, such as radial and decentric lens distortions. Before incorporating straight lines into a bundle adjustment with self–calibration, the representation and perspective transformation of straight lines between image space and object space should be addressed. In this investigation, images of straight lines are represented as a sequence of points along the image line. Also, two points along the object–space straight line are used to represent that line. The perspective relationship between image– and object–space lines is incorporated in a mathematical constraint. The underlying principle in this constraint is that the vector from the perspective centre to an image point on a straight–line feature lies on the plane defined by the perspective centre and the two object points defining the straight line. This constraint has been embedded in a software application for bundle adjustment with self–calibration that can incorporate point as well as straight–line features. Experiments with simulated and real data have proved the feasibility and the efficiency of the algorithm proposed.

A study was made of the method for determination of swept volume and the proper average temperature to use for interpretation of combustion falloff data using the "pseudo-steady" state concept. Two thermal simulators were used for this study to include non-uniform reservoir temperature and variable saturation effects. Skin and storage effects were not included. Interpretation of the data was based on the finding that, because of the very large contrast between the conductivity of gas in the swept volume and that in the unswept sand ahead, transient effects caused by the swept volume would be characteristic of a section of very high transmissivity (kh/w). This implied that the transition period characteristics of the falloff data will form a straight Cartesian line whose slope will be related Lo the swept volume. This follows from the concept of "pseudo-steady" state. Results obtained from the analysis of simulated data showed good agreement between calculated swept volume and actual swept volume. However, the swept volume was found to include both the burned volume and also the high gas saturation zone ahead of the combustion front. Thus a volume correction is necessary to relate the swept volume to the burned volume. In addition, average temperatures within the swept volume were calculated so that the appropriate physical properties can be included in the interpretation. properties can be included in the interpretation. Graphs which can he used to make these corrections are presented for use in interpreting similar field falloff data. Although a one-dimensional radial model was used for this study, the concept should apply in multi-dimensional cases where gravity override is common. Introduction Many authors have applied different methods to estimate the swept or burned volume from pressure falloff analysis. These methods include pressure falloff analysis. These methods include the radius of investigation method, the semilog intersection method, the deviation time method and material balance methods. Some of these methods yield swept volume that is larger than the actual swept volume. Recently, there has been interest in using the "pseudo-steady" state concept, a material balance method, in the analysis of thermal falloff data. Due to the large contrast between the mobility of the gas in the swept volume and the fluid in the unswept sand ahead of the front, the swept sand tends to behave like a large tank closed except at the well. This phenomenon has been observed by Mangold et al in their study of geothermal reservoirs. They observed that the presence of zones of different temperatures in presence of zones of different temperatures in non-isothermal reservoirs, resulted in a fluid mobility contrast that may resemble permeability barriers during well testing. The use of this concept has been investigated with different models. The results show that a typical pressure falloff curve will normally consist of an initial semilog straight line followed by a transition period and finally by a second semilog straight line. The transition period may contain a straight Cartesian line whose slope is related to the swept volume. In the models used in these investigations, several assumptions were made. These include; that the reservoir temperature is uniform, no saturation gradient exists at the front, the gas in the swept volume behaves as fluid of slight but constant compressibility, and the front interface is an isopotential surface. This study used finite difference thermal simulators to relax some of the assumptions, and to evaluate the appropriate temperature to be used in the analysis of combustion falloff data. Also the swept volume as determined from pressure analysis was compared with the actual simulated volume. THEORY The slopes from the initial semilog straight line and the Cartesian straight lines are related to the reservoir and fluid properties by the following equations: (1) P. 205

Motivated by the formation of fingerprint patterns, we consider a class of interacting particle models with anisotropic, repulsive-attractive interaction forces whose orientations depend on an underlying tensor field. This class of models can be regarded as a generalization of a gradient flow of a nonlocal interaction potential which has a local repulsion and a long-range attraction structure. In addition, the underlying tensor field introduces an anisotropy leading to complex patterns which do not occur in isotropic models. Central to this pattern formation are straight line patterns. For a given spatially homogeneous tensor field, we show that there exists a preferred direction of straight lines, i.e., straight vertical lines can be stable for sufficiently many particles, while many other rotations of the straight lines are unstable steady states, both for a sufficiently large number of particles and in the continuum limit. For straight vertical lines we consider specific force coefficients for the stability analysis of steady states, show that stability can be achieved for exponentially decaying force coefficients for a sufficiently large number of particles, and relate these results to the Kücken--Champod model for simulating fingerprint patterns. The mathematical analysis of the steady states is completed with numerical results.

Printed strain sensor based on silver nanowire/silver flake composite on flexible and stretchable TPU substrate

Increased use of digital imagery has facilitated the opportunity to use features, in addition to points, in photogrammetric applications. Straight lines are often present in object space, and prior research has focused on incorporating straight‐line constraints into bundle adjustment for frame imagery. In the research reported in this paper, object‐space straight lines aw used in a bundle adjustment with self‐calibration. The perspective projection of straight lines in the object space produces straight lines in the image space in the absence of distortions. Any deviations from straightness in the image space are attributed to various distortion sources, such as radial and decentric lens distortions. Before incorporating straight lines into a bundle adjustment with self‐calibration, the representation and perspective transformation of straight lines between image space and object space should be addressed. In this investigation. images of straight lines are represented as a sequence of points along the image line. Also, two points along the object‐space straight line are used to represent that line. The perspective relationship between image‐ and object‐space lines is incorporated in a mathematical constraint. The underlying principle in this constraint is that the vector from the perspective centre to an image point on a straight‐line feature lies on the plane defined by the perspective centre and the two object points defining the straight line. This constraint has been embedded in a software application for bundle adjustment with self‐calibration that can incorporate point as well as straight‐line features. Experiments with simulated and real data have proved the feasibility and the eficiency of the algorithm proposed.RésuméLe développement de l'imagerie numérique a fourni l'occasion de recourir davantage aux détails des objets, et non pas seulement aux points qui les constituent, duns toute application photogrammétrique. C'est ainsi que les objets présentent souvent des lignes droites qu'il était tentant, dans une recherche antérieure, d'introduire pour contraindre la compensation par faisceaux d'imageries photographiques. On présente dans cet article cette recherche où les lignes droites de l'espace objet sont utilisées dans une compensation par faisceaux avec auto‐étalonnage. En l'absence de distorsions, la projection de lignes droites de l'espace objet dans l'espace image s'opère également sous forme de lignes droites. Tout écart à une droite sur l'image peut done être attribuéà toutes sortes de distorsions, comme la distorsion radiale ou cello due au décentrement de l'objectif. Avant d'utiliser ces lignes droites dans une compensation par faisceaux avec auto‐étalonnage, il faut efectuer la représentation et la transformation perspective des lignes droites entre les espaces objet et image. Dans cette démarche, on considère les images des lignes droites comme constituées d'une suite de points jalonnant cette image tandis que duns l'espace objet cette ligne droite n'est définie que par deux points seulement. La relation de perspective qui relie les droites des espaces objet et image est alors introduite comme contrainte mathématique. Le principe de base de cette contrainte est que le vecteur issu du centre perspectif vers un point image d'une ligne droite de l'objet appartient au plan défini par re centre perspectif et les deux points retenus dans la définition de cette droite. On a incorporé cette contrainte dans un logiciel appliquéà la compensation par faisceaux avec auto‐étalonnage prenant en compte les points ainsi que les éléments en ligne droite de l'objet. Des essais avec des données simulées puis réelles ont montré la faisabilité et l'efficacité de l'algorithme proposé.ZusummenfussungDurch die zunehmende Nutzung digitaler Bilder wurde die Möglichkeit geschaffen, neben Punkten auch Objektmerkmale in photogrammetrischen Anwendungen zu nutzen. Oftmals finden sich Geraden in Objektraum, und frühere Forschung hat sich darauf konzentriert, Linienbedingungen in die Bündelausgleichung für Flächenkameras zu entwickeln. In den hier vorgestellten Forschungen werden Geraden im Objektraum in einer Bündelausgleichung mit Selbstkalibrierung eingesetzt. Wenn keine Verzeichnungen vorliegen, werden bei einer perspektiven Abbildung Geraden im Objektraum in Geraden im Bildraum abgebildet. Jegliche Abweichung von einer Gerden m Bildraum kann mit verschiedenen Ursachen für Verzeichnung in Verbindung gebracht werden, wie zum Beispiel radiale order asymmetrische Objektivverzeichung. Bevor Gerden in die Bündelausgleichung mit Selbstakalibrierung eingehen können, sollte die Repräsentation und die perspektive Transformation der Gerden zwischen Bild‐ und Objektraum geklärt werden. In dieser Untersuchung werden die Abbildungen der Geraden als eine Sequenz von Punkten entlang einer Bildlinie dargestellt. Zwei Punkte entlang der Objektgeraden werden genutzt, um diese darzustellen. Die perspektive Beziehung zwischen Bild‐ und Objektgeraden wird mit Hilfe einer mathematischen Bedingung formuliert. Das Prinzip, das dieser Beziehung zugrunde liegt, geht davon aus, dass ein Vektor vom Projektionszentrum zu einem Bildpunkt auf einer Geraden auf einer Ebene liegt, die durch das Projektionszentrum und die zwei Objektpunkte, die die Gerade definieren, bestimmt wird. Diese Bedingung wurde in ein Anwendungsprogramm zur Bündelausgleichung mit Selbstakalibrierung eingbaut, das sowohl Punkt‐ als auch Geradenmerkmale verarbeiten kann. Experimente mit simulierten und echten Datensätzen belegen die Anwendbarkeit und die Effizienz des vorgeschlagenen Algorithmus.

The weight and oxygen consumption of individual locusts, six from each instar, have been measured at 12-hourly intervals throughout each stadium. An analysis of short duration changes shows that fluctuations in live weight are unavoidable in the growing animal, and that they are accompanied by fluctuations in oxygen consumption. In time the latter lag behind the former. As the fluctuations of these two variables are out of phase, there is a considerable range of oxygen consumption which must be regarded as normal for any given weight. Calculations are made to find the limits of these fluctuations compatible with normal growth. The changes that occur during a stadium can be represented by a straight trend line for both weight and oxygen consumption. Exceptions occur in the case of weight of the adult where two straight lines are necessary, one for the growing phase and one for the steady phase of this instar. In certain cases in the fifth instar two straight lines are necessary to express the trend in oxygen consumption which may show an abrupt change in the middle of the stadium. A high degree of correlation is found between the trend lines for weight and oxygen consumption in the early instars. A low degree is found in latter instars where the weight increases and the oxygen consumption remains nearly constant. A curve representing the changes of weight and oxygen consumption that occur during the growth of the locust has been constructed.

In periodic systems, nodal lines are loops in the three-dimensional momentum space with each point on them representing a band degeneracy. Nodal lines exhibit rich topological features, as they can take various configurations such as rings, links, chains, and knots. These line nodes are generally protected by mirror or PT symmetry and frequently accompanied by drumhead surface states. Here, we propose and demonstrate a novel type of photonic straight nodal lines in a D_{2D} metacrystal, which are protected by an unusual rotoinversion time (roto-PT) symmetry. These nodal lines are located at the central axis and hinges of the Brillouin zone. They appear as quadrupole sources of Berry curvature flux in contrast to the Weyl points, which are monopoles. Interestingly, topological surface states exist at all three cutting surfaces, as guaranteed by π-quantized Zak phases along all three directions. As frequency changes, the surface state equifrequency contours evolve from closed to open and become straight lines at a critical transition frequency, at which diffractionless surface wave propagations are experimentally demonstrated, paving the way toward development of superimaging topological devices.