Inhomogeneous Texture Research Articles

Ultrasonic studies of texture inhomogeneities in pressure vessel steel subjected to ultrasonic impact treatment and shock compression

Abstract Specimens of Cr-Ni-Mo-V pressure vessel steel 15Kh2NМFА were cut from the achieve wall of the WWER-1000 reactor and were then deformed either using ultrasonic impact treatment (UIT) inducing low energy multiple impacts or by drop-hammer inducing high energy shock compression (HESC). With the aim of texture evaluation comprehensive ultrasonic measurements and X-ray texture analysis were carried out in different sections of the deformed specimens. A nondestructive quantitative analysis of the crystallographic texture in various layers of the deformed specimens was performed on the base of precise measurements of the bulk-wave ultrasonic velocities ( v ij ) by means of the pulse-echo method using a home-made automated apparatus. The mass densities ( ρ ) of the deformed specimens and their cut sections were also precisely measured. The obtained data allowed calculating orientation distribution coefficients ( W 4 i 0 ) of crystallites and to construct ultrasonic pole figures for different specimen layers and cut sections. The ultrasonic pole figures correlate well to the X-ray pole figures registered in the cut sections of the specimens. It is found that maximal pole intensities (Δ I [ ijk ] ) and spatial inhomogeneities of these textures depend on the used regimes of UIT and HESC. The revealed peculiarities of the texture formation correlate well to the depth distributions of microhardness and strain extents. The higher the strain extent or the longer the treatment time, the more intensive texture is registered and the deeper the textured layer is observed. The ultrasonic method applied is shown to be useful and efficient for non-destructive examination of elastically heterogeneous systems, particularly the materials with mechanically treated surfaces.

Phenomenology of current-induced skyrmion motion in antiferromagnets

We study current-driven skyrmion motion in uniaxial thin film antiferromagnets in the presence of the Dzyaloshinskii–Moriya interactions and in an external magnetic field. We phenomenologically include relaxation and current-induced torques due to both spin–orbit coupling and spatially inhomogeneous magnetic textures in the equation for the Néel vector of the antiferromagnet. Using the collective coordinate approach we apply the theory to a two-dimensional antiferromagnetic skyrmion and estimate the skyrmion velocity under an applied DC electric current.

Spin Superfluidity in the ν=0 Quantum Hall State of Graphene.

Strong electron interactions can lead to a variety of broken-symmetry phases in monolayer graphene. In the quantum Hall regime, the interaction effect are enhanced by the formation of highly degenerate Landau levels, catalyzing the emergence of such phases. Recent magnetotransport studies show evidence that the ν=0 quantum Hall state of graphene is in an insulating canted antiferromagnetic phase with the Néel vector lying within the graphene plane. Here, we show that this Néel order can be detected via two-terminal spin transport. We find that a dynamic and inhomogeneous texture of the Néel vector can mediate nearly dissipationless (superfluid) transport of spin angular momentum polarized along the z axis, which could serve as a strong support for the antiferromagnetic scenario. The injection and detection of spin current in the ν=0 region can be achieved using the two spin-polarized edge channels of the |ν|=2 quantum Hall state. Measurements of the dependence of the spin current on the length of the ν=0 region would provide direct evidence for spin superfluidity.

Effect of layerwise structural inhomogeneity on stress- corrosion cracking of steel tubes

Based on X-ray texture and structure analysis data of the material of main gas pipelines it was shown that the layerwise inhomogeneity of tubes is formed during their manufacturing. The degree of this inhomogeneity affects on the tendency of tubes to stress- corrosion cracking under exploitation. Samples of tubes were cut out from gas pipelines located under various operating conditions. Herewith the study was conducted both for sections with detected stress-corrosion defects and without them. Distributions along tube wall thickness for lattice parameters and half-width of X-ray lines were constructed. Crystallographic texture analysis of external and internal tube layers was also carried out. Obtained data testifies about considerable layerwise inhomogeneity of all samples. Despite the different nature of the texture inhomogeneity of gas pipeline tubes, the more inhomogeneous distribution of texture or structure features causes the increasing of resistance to stress- corrosion. The observed effect can be explained by saturation with interstitial impurities of the surface layer of the hot-rolled sheet and obtained therefrom tube. This results in rising of lattice parameters in the external layer of tube as compared to those in underlying metal. Thus, internal layers have a compressive effect on external layers in the rolling plane that prevents cracks opening at the tube surface. Moreover, the high mutual misorientation of grains within external and internal layers of tube results in the necessity to change the moving crack plane, so that the crack growth can be inhibited when reaching the layer with a modified texture.

Inhomogeneous Texture Distribution in a Cu-Ag Lamellar Composite Processed by Cold Rolling

Inhomogeneous Texture Distribution in a Cu-Ag Lamellar Composite Processed by Cold Rolling

Irregularities of crystallographic orientation and residual stresses in the crossed-lamellar shell as a natural functionally graded material.

The microstructures of different groups of molluscs are characterized by preferential orientations of crystallites (texture), leading to a significant anisotropy of the physical properties of the shells. A complementary characteristic, usually neglected, is the distribution of the residual stresses existing within the shell wall. By means of X-ray diffraction, we study the distribution of stresses with thickness in the shell wall of the gastropod Conus marmoreus, which has a microstructure of the crossed-lamellar type. The results revealed an extraordinary texture inhomogeneity and the existence of tensional residual stresses along the shell thickness, the origins of which are unknown. Some of the observed changes in textural parameters and stresses coincide with the transitions between shell layers, although other features are of unknown origin. Our results provide insight into the microstructural regularities that govern the mesoscale construction of shells, such as that of C. marmoreus.

Rapid Assessment of Tablet Film Coating Quality by Multispectral UV Imaging.

Chemical imaging techniques are beneficial for control of tablet coating layer quality as they provide spectral and spatial information and allow characterization of various types of coating defects. The purpose of this study was to assess the applicability of multispectral UV imaging for assessment of the coating layer quality of tablets. UV images were used to detect, characterize, and localize coating layer defects such as chipped parts, inhomogeneities, and cracks, as well as to evaluate the coating surface texture. Acetylsalicylic acid tablets were prepared on a rotary tablet press and coated with a polyvinyl alcohol-polyethylene glycol graft copolymer using a pan coater. It was demonstrated that the coating intactness can be assessed accurately and fast by UV imaging. The different types of coating defects could be differentiated and localized based on multivariate image analysis and Soft Independent Modeling by Class Analogy applied to the UV images. Tablets with inhomogeneous texture of the coating could be identified and distinguished from those with a homogeneous surface texture. Consequently, UV imaging was shown to be well-suited for monitoring of the tablet coating layer quality. UV imaging is a promising technique for fast quality control of the tablet coating because of the high data acquisition speed and its nondestructive analytical nature.

Effective magnetization damping for a dynamical spin texture in metallic ferromagnet

An additional magnetization damping for an inhomogeneous spin texture in metallic ferromagnets is calculated on the basis of the s–d exchange model. The effect of conduction electrons on the magnetization dynamics is accounted for the case of slowly varying spin texture within adiabatic approximation by using a coordinate transformation to the local quantization axis. The moving magnetic vortex in a circular nanodot made of permalloy is considered as an example. The dependence of the damping on the dot geometrical sizes is obtained. It is found that the additional damping can reach up to 50% of magnitude of the phenomenological Gilbert damping in the Landau–Lifshitz equation of magnetization motion and should be taken into account for any inhomogeneous spin texture dynamics in ferromagnetic metals.

Through Thickness Microstructural and Texture Inhomogeneity Within Al Layers in ARB-Produced Al-Al(Sc) Layered Composite Sheets

Alternatively layered composite sheets of commercially pure (99.8 pct purity) aluminum and an Al-0.3wtpctSc alloy (either in the supersaturated solid solution or age-hardened conditions) were generated through accumulative roll bonding for up to 5 cycles. The transverse sections of the sheets were examined to investigate the microstructure and texture inhomogeneities developed during the rolling process. Electron backscatter diffraction and transmission electron microscopy was used for this investigation. It was found that an inhomogeneous microstructure and texture was developed through the aluminum layers of the sheet thickness. The nature of inhomogeneities changes as the ARB bonding progresses to higher cycles. Microstructural inhomogeneities remain prominent in the first ARB cycle and diminish during the subsequent cycles. Texture inhomogeneities appear in different forms as rolling progresses. High frictional shear forces in the surface and in-plane shear forces across bonding interfaces derive these inhomogeneities.

Inhomogeneity on texture, microstructure and magnetic properties of hot deformed R2Fe14B-typed magnet

The inhomogeneity on texture, microstructure and magnetic properties of hot deformed (HD) disc shape R 2 Fe 14 B -typed magnets along radial and axial directions has been investigated. HD disc shape NdFeB magnet exhibits inhomogeneous texture, grain morphologies and magnetic properties not only along the radial direction but also along the axial direction. Higher magnetic properties can be found in the middle part of the HD magnet, due to the existence of larger volume fraction of plate-like Nd 2 Fe 14 B grains and the well c-axis alignment parallel to the pressing direction. In addition, particle-like and coarser grains are easily found not only in the bottom but also in the edge of the HD magnet, which may degrade the magnetic performance of the samples cut from those parts. Owing to the inhomogeneity of (00L) texture and grain morphologies along axial and radial directions, the optimal magnetic properties of B r = 12.7 kG, H ci = 5.1 kOe and (BH) max = 39 MGOe can be obtained only in the middle sample of HD magnet with slight polishing the top and bottom surfaces.

Radiological features of metastases to the thyroid.

Thyroid metastases (TM) are uncommon. Dependent on study design, the reported frequency of TM is in the range of 0.1-6% in different analyses. While clinical and histopathological features of TM were well described in the literature, radiological publications consist predominantly of isolated case reports or small series. To estimate the prevalence, clinical signs, and radiological appearances of TM. From 1997 to 2013, a total of 8849 patients with various disorders of the thyroid gland were treated in our institution. In 33 patients TM were diagnosed. Ultrasound (US) images were available in all patients, computed tomography (CT) of the neck in 16 patients, and magnetic resonance imaging (MRI) in nine patients. Clinically, most patients (85%) presented with a painless neck mass. Primary tumors were renal cell carcinoma (79%), colorectal cancer (12%), lung cancer (3%), rhabdomyosarcoma (3%), and breast carcinoma (3%). On US, most lesions were irregular in shape with inhomogenous texture. On CT, all TM were hypodense. On T1-weighted images, most TM were inhomogenously iso-to-hyperintense in comparison to the normal thyroid tissue, and slightly hyperintense on T2-weighted images with an inhomogenous contrast enhancement. The prevalence of TM was 0.4%. Most of the TM originated from renal cell carcinoma. The identified radiological features of TM should be taken into consideration in the differential diagnosis of thyroid lesions.

Fredericks Transition in Pure and Nanodoped Surface Stabilized Ferroelectric Liquid Crystals

Recently, ferroelectric liquid crystals (FLCs) doped with nanoparticles have attracted a wide interest not only from a scientific but also from a practical point of view and there is continuously growing interest in the effects caused by doping the ferroelectric nanoparticles. Furthermore, the presence of external fields exhibits a very interesting transition, reported by recent experiments. In this work, we investigate the response of a surface stabilized ferroelectric liquid crystal (SSFLC) doped with ferroelectric nanoparticles to an applied electric field. We assume that the smectic layers consist of uniform planes with a fixed orientation and the system is free from dislocation of constant layer thickness due to nanoparticles. We obtain the threshold field of orientational transition and the maximum deviation of the polarization vectors for a pure and a doped SSFLC medium. Then, we discuss the Fredericks transtion of the system and formation of inhomogeneous texture. It is found that the ferroelectric nanoparticles have significant influences in ordering behavior of a SSFLC medium and the threshold fields are critically changed by doping nanoparticles in the SSFLC, which is fundamental to operation of many liquid crystal devices.

Effect of interlayer macrostress on hydride orientation in shell tubes from Zr-based alloys

Methods of texture analysis allowed to show that inhomogeneity of the crystallographic texture in shell tube wall is responsible for rise of tangential macrostress in the tube. This inhomogeneity predetermines a difference of thermal expansion between outside and inside layers of tube at its exploitation temperature. The indicator of such stress is formation of radially-oriented hydrides in the transverse section of tube, subjected to treatment in autoclave.

Defect detection in multi-crystal solar cells using clustering with uniformity measures

Solar cells that convert sunlight into electrical energy are the main component of a solar power system. Quality inspection of solar cells ensures high energy conversion efficiency of the product. The surface of a multi-crystal solar wafer shows multiple crystal grains of random shapes and sizes. It creates an inhomogeneous texture in the surface, and makes the defect inspection task extremely difficult. This paper proposes an automatic defect detection scheme based on Haar-like feature extraction and a new clustering technique. Only defect-free images are used as training samples. In the training process, a binary-tree clustering method is proposed to partition defect-free samples that involve tens of groups. A uniformity measure based on principal component analysis is evaluated for each cluster. In each partition level, the current cluster with the worst uniformity of inter-sample distances is separated into two new clusters using the Fuzzy C-means. In the inspection process, the distance from a test data point to each individual cluster centroid is computed to measure the evidence of a defect. Experimental results have shown that the proposed method is effective and efficient to detect various defects in solar cells. It has shown a very good detection rate, and the computation time is only 0.1s for a 550×550 image.

Direct transfer of magnetic sensor devices to elastomeric supports for stretchable electronics.

A novel fabrication method for stretchable magnetoresistive sensors is introduced, which allows the transfer of a complex microsensor systems prepared on common rigid donor substrates to prestretched elastomeric membranes in a single step. This direct transfer printing method boosts the fabrication potential of stretchable magnetoelectronics in terms of miniaturization and level of complexity, and provides strain-invariant sensors up to 30% tensile deformation.

A Novel Level Set Model Based on Multi-scale Local Structure Operation for Texture Image Segmentation

Regional level set method is a popular approach for image segmentation that uses inside and outside information of contour to extract object boundary. Unfortunately, in many cases, such method is not adequate to model complex textured objects. In this paper, we propose a natural texture image segmentation method which incorporates the pixel-level feature into region-level feature. The multiscale local structure operation is proposed as pixel-level feature to describe the texture structure of image. So the problems of multi-scale and rotation invariance of inhomogeneous texture are addressed by introducing multi-scale local structure operation into level set energy functional. Then, the global intensity information is extracted as the region-level feature and integrated with multi-scale local structure operation. Further, we propose a so-called vector level set method to obtain the segmentation results. Here, we extend the traditional regional level set model into the vector formulation so that the multi-scale local structure operation can be suitably combined with the global intensity information to achieve the more superior image segmentation performance than that of the traditional segmentation methods for texture images. Experiments on some synthesis texture images and real natural scene images demonstrate the excellent performance of the proposed method which successfully combines local structure information and global intensity information to extract the object boundary.

Seam detection of inhomogeneously textured fabrics based on wavelet transform

A large amount of seam detection for inhomogeneously textured fabrics makes those performing it fatigued, which leads to misjudgments by human vision, especially for the seam detection of patterned inhomogeneously textured fabrics. The traditional wavelet texture analysis is no longer applicable to fabrics with inhomogeneous textures and irregular patterns. In this paper, a novel mean weighting factor is proposed to obtain an optimized discriminant measure to detect the fabric seams. Firstly, the wavelet coefficients are extracted in individual decomposition levels. Then a mean weighting factor is calculated on the use of the difference of the coefficient values between two consecutive decomposition levels, and a better discriminant measure for seam detection is obtained. Lastly, a thresholding process is used to segment the seam information from the background. The experimental results show that the proposed approach effectively carries out the seam detection in the inhomogeneously textured fabric images.

Microstructure and Texture Evolution of Strip-Cast and Hot-Rolled Fe-3 %Si Steel Sheet

The microstructure and texture evolution of Fe-3 %Si nonoriented silicon steel fabricated by twin-roll casting and hot rolling was investigated. Inhomogeneous microstructure and texture were formed through thickness of both as-cast and hot-rolled strips. In as-cast strip, the microstructure through thickness was characterized by coarse grains at surface layer and fine equiaxed grains at center layer. Surface layer displayed both recrystallization texture of {112} and {110} components and solidification texture of {100} component. The fine equiaxed grains were sandwiched between two coarse-grain layers, which showed recrystallization texture only containing strong {112} and relatively weak {100} and {110} components. After hot rolling, the surface layer exhibited fine equiaxed grains with average size of 50 μm. The major texture components of surface layer were {112} and {110} . Coarse elongated grains were observed at center layer with strong {100} texture. The mechanism of microstructure and texture inhomogeneity in both as-cast and hot-rolled strips is proposed.

An Active Contour Model Based on Texture Distribution for Extracting Inhomogeneous Insulators From Aerial Images

The objects in natural images are often texturally inhomogeneous and prone to be falsely segmented into different parts by conventional methods. To overcome the difficulties caused by texture inhomogeneity, a new active contour model is proposed to extract inhomogeneous insulators from aerial images. First, a semilocal operator is employed to extract the texture features of insulators under the Beltrami framework. The layer of semilocal texture feature is single, and thus, it can avoid the high dimensionality of feature space. Then, a new convex energy functional is defined by taking the Xie's nonconvex model into a global minimization active contour framework during the process of segmentation. The proposed energy functional consists of not only the semilocal texture features of insulators but also their spatial relationship, which improves its ability to deal with textural inhomogeneity. Moreover, it can also avoid the existence of local minima in the minimization of the Xie's nonconvex model, thereby being independent of initial contour. In the process of contour evolution and numerical minimization, a fast dual formulation is employed to overcome the drawbacks of the usual level set and gradient descent method and to make the evolution of the contour more efficient. The experimental results on aerial insulator images confirm the ability of the proposed algorithm to effectively segment inhomogeneous textures with an overall average rmse of 1.87 pixels, a precision of 85.59%, and a recall of 86.47%. In addition, the proposed algorithm is extended to animal images, and satisfactory segmentation results can be obtained as well.

A Case of Marine-Lenhart Syndrome with a Negative TSH Receptor Antibody Titer Successfully Treated with a Fixed, Low Dose of I (131.).

We herein describe a case of Marine-Lenhart syndrome with a negative TSH receptor antibody titer. A 75-year-old female presented to our hospital with malaise, palpitations, and mild fine tremors. She did not have any signs suggestive of Graves' ophthalmopathy, including conjunctival injection, periorbital edema, or proptosis. Her laboratory data were negative for thyroid autoantibodies, including anti-thyroid peroxidase antibodies, anti-thyroglobulin antibodies, and anti-TSH receptor antibodies (TRAb). Ultrasonography of the thyroid gland revealed a tumor in the right lobe. The remaining thyroid gland had an inhomogeneous and rough texture with a high color Doppler flow. I123 scintigraphy disclosed a hot nodule in the right thyroid gland corresponding to the tumor detected on ultrasonography, suggesting Plummer disease. Furthermore, there was an increased uptake of radionuclide in the rest of the thyroid gland, despite the suppressed level of TSH and negative titer of TRAb, suggesting underlying Graves' disease. The present findings suggested a diagnosis of Marine-Lenhart syndrome with a negative TRAb titer. Treatment with 10 mCi of radioiodine was highly effective in treating hyperthyroidism in this case. A negative TSH receptor antibody titer does not necessarily rule out the existence of Graves' disease in patients with Plummer disease.