Skew Angle Research Articles

AN ACCURATE AND EFFICIENT SKEW ESTIMATION TECHNIQUE FOR SOUTH INDIAN DOCUMENTS: A NEW BOUNDARY GROWING AND NEAREST NEIGHBOR CLUSTERING BASED APPROACH

Skew angle estimation is essential to enhance the accuracy of optical character recognition (OCR) system. In this paper we present a new boundary growing (BG) and nearest neighbor clustering (NNC) to estimate accurate skew angle for the scanned documents. The BG extracts the boundary characters present in each text line of the document and extracts uppermost, lowermost and centroid coordinates of character components of the scanned document image. The NNC helps us in clustering the characters which is presented due to additional modifiers-characters that are usually present in the South Indian scripts. The extracted coordinates are subjected to moments to estimate skew angle of the document image. Several experiments have been conducted on various types of documents such as documents containing South Indian scripts, English documents, journals, textbook, text with picture, text with tables, text with graphs, different languages, noisy images and document with different fonts, documents with different resolutions, to reveal the robustness of the proposed method. The experimental results revealed that the proposed method is accurate compared to the results of well-known existing methods.

A novel boundary growing approach for accurate skew estimation of binary document images

Skew angle estimation is an important component of optical character recognition (OCR) systems and document analysis systems (DAS). In this paper, a novel and an efficient method to estimate the skew angle of a scanned document image is proposed. The proposed method has two stages. In first stage, using boundary-growing approach, text lines containing characters of the scanned document image are extracted. From each text line, coordinates of the positions of the characters are obtained. In second stage, the obtained coordinates are fed to linear regression analysis (LRA) for the purpose of computation of skew angle. Several experiments have been conducted on various types of documents such as documents containing different language texts, documents with different fonts and documents with noise to reveal the robustness of the proposed method. A comparative study with the well-known methods is presented to show that the proposed method is superior in terms of accuracy and computational efficiency.

Effect of Skew Angle on Distribution of Bending Moments in Bridge Slabs

Effect of Skew Angle on Distribution of Bending Moments in Bridge Slabs

Effects of Head Pole Aspect Ratio and Skew Angle on Areal Density in Perpendicular Recording

Semianalytical models have been applied to examine the effect of head pole aspect ratio on areal density in perpendicular recording at different skew angles. It has been found that at zero skew angle, increasing pole length enhances the writing field, which allows higher medium H/sub K/ and smaller grain size and leads to higher areal density. However, when the skew angle is included, the pole aspect ratio needs to be optimized to deliver the optimal areal density. Both the optimal areal density and pole aspect ratio decrease with increasing the skew angle.

Skew angle estimation for printed and handwritten documents using the Wigner–Ville distribution

Abstract A skew estimation algorithm for printed and handwritten documents, based on the document's horizontal projection profile and its Wigner–Ville distribution, is presented. The proposed algorithm is able to correct skew angles that range between −89 and +89° detecting the right oriented position of the page by the alternations of the horizontal projection profile. It is able of processing successfully handwritten documents, even if they consist of non-parallel text lines. It deals with the presence of graphics, while a few text lines suffice for the application of the algorithm. Furthermore, the latter permits the use of only a part of the page for the skew estimation minimizing the computational complexity. The proposed algorithm was evaluated on a wide variety of pages (i.e. printed, handwritten, multi-column, application forms etc.) achieving a success rate of 100% within a confidence range of ±0.3°.

AEROELASTIC PERFORMANCE OF MULTI-STRAND CABLE WITH HORIZONTAL SKEW ANGLE AND EFFECT OF HELICAL STRAND

AEROELASTIC PERFORMANCE OF MULTI-STRAND CABLE WITH HORIZONTAL SKEW ANGLE AND EFFECT OF HELICAL STRAND

COMPUTER-AIDED PHOTOGRAPH MATCHING IN STUDIES USING INDIVIDUAL IDENTIFICATION: AN EXAMPLE FROM SERENGETI CHEETAHS

Photographic identification of naturally marked animals is a powerful and nonintrusive technique for obtaining information on behavior, population size, and life-history parameters in wild populations. Yet handling large quantities of photographs is time consuming and prone to error. Computer-aided matching can limit the number of photographs that must be examined visually to confirm that 2 sightings are the same individual. To identify individuals, I used a 3-dimensional (3-D) computer-matching system to aid in matching nearly 10,000 photographs of Serengeti cheetahs, Acinonyx jubatus, taken over 25 years. Accuracy in matching 2 photographs increased to 100% as the computer-generated similarity coefficient increased to 0.600 on a scale from 0 to 1. Probability of missing a match decreased to 6.4% when I used a threshold of similarity of 0.450. Poor quality of photographs decreased accuracy and resulted in up to 33% of matches being missed. Comparisons of photographs at skewed camera angles generally reduced similarity coefficients. Similarity coefficients were no higher for related or unrelated animals, suggesting that the technique is not appropriate for distinguishing subtle similarities. Because 3-D computer-aided matching does not require familiarity with distinctive features of the particular study animal, it is robust to matcher inexperience. This technique can be modified for other species that have complex and variable pelage patterns.

Effect of Bearing Stiffness and Skew Angle on Performance of Precast Concrete Bridge

Reinforced elastomeric bearing pads generally support precast concrete bridge girders. The condition of these bearing pads and the pad-bridge interface defines the support boundary conditions of the bridge super-structure. The interface between bearing pads and bridge girders affects the performance of the superstructure and the substructure. The pads are designed to carry vertical loads and to accommodate horizontal movements of the bridge girders. A study was conducted to determine the effects of various parameters on bridge superstructure performance and to compare the girder performance with simple support conditions corresponding to the current Florida Department of Transportation design. A parametric study on the interaction of the support boundary conditions and bridge girders was performed. The parameters studied included the skewness of the bridge and the effect of the bearing stiffness on the bridge system. A finite element model of a bridge superstructure containing Florida bulb tee 78 girders was created using ANSYS software. The model was subjected to an HL93 truck load according to the AASHTO load and resistance factor design specifications. The results indicate that pads with higher bearing stiffness are beneficial to bridges with higher skew angles. However, the reductions in deflections and stresses are smaller for increasing skew angles.

Skew Angle Effects on Disk Medium Noise at Ultrahigh Recording Densities

Skew Angle Effects on Disk Medium Noise at Ultrahigh Recording Densities

Suppression of Rotating Stall by Wall Roughness Control in Vaneless Diffusers of Centrifugal Blowers

By positioning the completely rough wall locally on the hub side diffuser wall alone in the vaneless diffuser, the flow rate of rotating stall inception was decreased by 42 percent at a small pressure drop of less than 1 percent. This is based on the fact that the local reverse flow occurs first in the hub side in most centrifugal blowers with a backswept blade impeller. The three-dimensional boundary layer calculation shows that the increase in wall shear component normal to the main-flow direction markedly decreases the skewed angle of the three-dimensional boundary layer, and results in suppression of the three-dimensional separation. It is also clarified theoretically that the diffuser pressure recovery is hardly deteriorated by the rough wall positioned downstream of R = l.2 because the increase in the radial momentum change, resulting from reduction in the skewed angle of the three-dimensional boundary layer, supports the adverse pressure gradient.

Magnetic focusing in triangular electron billiards

The classical ballistic magnetotransport in triangular electron billiards fabricated in a high mobility GaAs heterostructure has been studied at 4.2 K. The sample geometry may be viewed as a double-slit structure with a skewed injection angle. We observe a striking cancellation of the magnetic focusing spectrum compared to the case of a perpendicular injection angle. From numerical and analytical analysis, we confirm that the quenching is a fundamental geometrical effect, and identify two mechanisms responsible for the anomaly. The focusing spectrum of the considered skewed geometry is remarkably sensitive to the angular distribution of injected electrons as well as the overall injection angle.

Influences of Piercing Ratio, Expansion Ratio, Feed, Cross and Skew Angles on Available Piercing Size Range in Rotary Piercing Process.

A cone-type piercing mill was developed by the authors for materials with poor hot workability. This piercing mill is called "the super piercer" in Europe and America. This mill has a pair of cone-type main rolls supported at both ends with their roll axes inclined and crossed so as to enable piercing at high feed and cross angles. In order to ensure the best performance of the rotary piercing, disc rolls are adopted instead of plate guide shoes. The super piercer was put into practice at the small-diameter seamless tube plant operated in 1983. The recent progress in our research and development on the super piercer has resulted in the concept of "the new super piercer", which allows expansion piercing. Namely, the development of the skewing technology for disc roll axes and its application to the cone-type piercing technology has realized remarkable increase in the expansion ratio. The new super piercer was adopted as the core technology of the new medium-diameter seamless tube plant operated in 1997. In this paper, studied in detail were the influences of the piercing ratio, expansion ratio, feed and cross angles for main roll axes and skew angle for disc roll axes on the available piercing size range.

Skew angle, media orientation and head-disk spacing change in proximity recording systems

Experiments reported in this work indicate that for the same head-disk spacing, the outer diameter, corresponding to higher skew angle, is more sensitive to the spacing variation. Conducted investigations cover peak detection channels, PRML channels, oriented media, isotropic media, and the same conclusion can be drawn. Increased skew angle will increase the nonlinear transition shift in the write process. Such phenomena can be observed from both the isotropic media and the media with strong orientation.

Skew angle and read/write off-track asymmetry of MR heads

This paper reports spin-stand based experimental study the asymmetry of off-track capability of a magnetoresistive (MR) head. Tests were conducted at the same track, same head-disk spacing but different skew angles. Results indicate: (1) track profile becomes even more asymmetric when the testing track is narrowed by erasing on both sides of the track; (2) increased skew angle leads to increased asymmetry of the track profile and reduced off-track capability; (3) the off-track capability, represented by the bit-shift is sensitive to the variation of the head-disk separation.

Skew angle detection of digitized Indian script documents

Skew angle detection of scanned documents containing most popular Indian scripts (Devnagari and Bangla) is considered. Most characters in these scripts have horizontal lines at the top, called head lines. The character head lines mostly join one another in a word and the word appears as a single component. In the proposed method the components are at first labeled. The upper envelope of a component is found by columnwise scanning from an imaginary line above the component. Portions of upper envelope satisfying the properties of digital straight line are detected. They are clustered as belonging to single text lines. Estimates from individual clusters are combined to get the skew angle. Apart from accuracy and efficiency, an advantage of the method is that character segmentation and zone detection can be readily done from head line information, which is useful in optical character recognition approaches of these scripts.

Large-Scale Outflows in Edge-on Seyfert Galaxies. II. Kiloparsec-Scale Radio Continuum Emission

We present deep images of the kpc-scale radio continuum emission in 14 edge-on galaxies (ten Seyfert and four starburst galaxies). Observations were taken with the VLA at 4.9~GHz (6~cm). The Seyfert galaxies were selected from a distance-limited sample of 22 objects (defined in paper~I). The starburst galaxies were selected to be well-matched to the Seyferts in radio power, recessional velocity and inclination angle. All four starburst galaxies have a very bright disk component and one (NGC~3044) has a radio halo that extends several kpc out of the galaxy plane. Six of the ten Seyferts observed have large-scale (radial extent $\gapprox$1 kpc) radio structures extending outward from the nuclear region, indicating that large-scale outflows are quite common in Seyferts. Large-scale radio sources in Seyferts are similar in radio power and radial extent to radio halos in edge-on starburst galaxies, but their morphologies do not resemble spherical halos observed in starburst galaxies. The sources have diffuse morphologies, but, in general, they are oriented at skewed angles with respect to the galaxy minor axes. This result is most easily understood if the outflows are AGN-driven jets that are somehow diverted away from the galaxy disk on scales $\gapprox$1 kpc. Starburst-driven winds, however, cannot be ruled out. More observational work is needed to determine whether massive star formation is present at high enough rates to drive galactic winds out to kpc scales in Seyfert galaxies.

Optimization of the adhesive joint Iosipescu specimen for pure shear test

This paper reviews some of the difficulties encountered in achieving a uniform stress distribution within the adhesive layer of bonded Iosipescu shear test specimens. The asymptotic singular stress field at the terminus of a skewed bimaterial interface, intersecting the straight free surface of the wedge, has been studied macroscopically and microscopically using the finite element method (FEM) and the finite element iterative method (FEIM). Different mechanical properties of the adhesives and adherends, and various skewed interface angles have been considered in this study. A critical skewed interface angle, αc=126°, has been found beyond which the interfacial stress singularity vanishes. This critical angle is independent of the elastic properties of the adhesives and adherends. Based on the results obtained in the present investigation, in conjunction with recently reported research on sharp notches [7, 21–23], an optimized adhesive joint Iosipescu specimen geometry is proposed. This specimen should be capable of generating a uniform shear stress state within its adhesive layer under pure shear loading conditions.

An improved document skew angle estimation technique

When a document is fed to a scanner either mechanically or by a human operator for digitization, it suffers from some degrees of skew or tilt. Skew angle detection is an important component of any Optical Character Recognition (OCR) and document analysis system. In this letter we consider skew estimation of Roman script. The method considers the lowermost and uppermost pixels of some selected characters of the text which may be subject to Hough transform for skew angle detection. A fast approach is also proposed which works almost as accurately as Hough transform. Experimental results are presented and compared with results on several other skew detection methods.

Skew angle and its effects on Gb/in/sup 2/ density magnetic recording

This paper reports results of experimental investigations on the relationship between skew angle and achievable recording density. Work is focused on bit density, track density and error rate aspects. The obtained results indicate that large skew angle reduces achievable bit density of both near-isotropic and orientated media. Increased skew angle also increases bit-shift value, therefore reducing applicable recording density from a reliability viewpoint. However, increased skew angle can support higher track density, as the effective track width and the writing interference are reduced when the skew angle is large. For certain head-disk integration, the width of the erase profile can reduce at a faster rate compared with the width of the track profile.

Skew angle and off-track capability of near contact recording systems

Various sliders for near-contact recording systems have begun to appear in high areal density disk drives. In this paper, systematic investigations were conducted to evaluate the effects of skew angle on off-track capability of near-contact recording systems. Tri-pad sliders were used in the investigations. The spacings between read/write elements and disk surface were in the range of 0.6/spl sim/1.2 /spl mu/in. The off-track capability is reduced and the noise level of residual signal after overwriting is increased, when skew angle is increased. A large skew angle also makes the off-track capability asymmetric and sensitive to off-track direction. However, increased skew angle reduces the track-to-track interference in the writing operation.