Inhomogeneous Areas Research Articles

A rare case of a spontaneous abscess of the corpus cavernosum: the role of contrast-enhanced ultrasound in diagnosis and post-therapeutic follow-up

In this paper, we describe the pattern of an idiopathic corpus cavernosum (CC) abscess using contrast-enhanced ultrasound (CEUS) and compare this to the lesion characterization achieved using preliminary baseline ultrasound/color doppler (ECD). In a 43-year-old man, who arrived at our emergency department for a penile swelling and hematopyuria, ECD examination showed equivocal mucosal and subcutaneous tissue swelling, an inhomogeneous hypoechoic area in the left CC, and a suspected millimetric interruption of the albuginea. CEUS showed multiple avascular areas wrapped in a hyperperfused rim representing abscesses and a not-perfused balanopreputial-oriented fistula. A CEUS control documented clinical remission after surgery. CEUS is a noninvasive and bedside executable method that allows a more precise evaluation of the entity, localization, and possible complications of CC abscesses and, therefore, permits prescribing the most adequate therapy to the patient, as well as the evaluation of eventual postsurgical sequelae.

Interaction between untreated SrTiO3 substrates and solution-derived YBa2Cu3O7-δ films

In this work it is shown how SrTiO3 substrates interact with YBa2Cu3O7-δ thin films during film processing. The effect of this interdiffusion on morphology and transport properties is analyzed. The films were deposited by low fluorine Metal Organic Decomposition (MOD) on SrTiO3 (0 0 1) single crystals. In general, a sharp c-axis oriented growth and high critical temperature (Tc) were observed in all samples; however, the surface of the otherwise good-quality films is spoiled by the presence of inhomogeneous circular areas of seemingly different appearance and texture. In order to understand the nature of these defects, the substrates and the films were deeply investigated by optical microscopy, scanning and transmission electron microscopy (SEM, TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), contact-stylus surface profilometry (SSP), Atomic Force Microscopy (AFM) and time of flight secondary ion mass spectrometry (ToF-SIMS). The round spots are the manifestation, on the film surface, of ion interdiffusion from the substrate into the YBCO film Spot-free samples can be obtained with different pre-treatments of the SrTiO3 substrates. Although these defects are detrimental for the film local structure, Jc values are not significantly affected, although the defects' influence might become substantial while working on smaller scales.

Effects of different volumes of inhomogeneous medium to the radial dose and anisotropy functions in HDR brachytherapy

The aim of this study is to study the effects of non –homogenous region closer to the HDR Brachytherapy source. Radial widths of 1, 3 and 5 cm of an inhomogeneous cylindrical area filled with bone and lung tissue in a water phantom are modelled in this study. The effects of this inhomogeneity to the g(r) and F(r,θ) of Nucletron 192Ir microSelectron HDR source are assessed. The results show that the assumption of homogeneous water leads to underestimation of the bone dose by the treatment planning system. Meanwhile, overestimation of the dose is observed in the surrounding area. A relative difference of up to 19% is calculated for the largest bone volume. Contrast results are observed for the lung inhomogeneity model. A relative difference of up to 12% is observed in the lung dose. The presence of inhomogeneous region in the water phantom affects the anisotropy function; at a radial distance greater than 5 cm. Our results indicate that the presence of bone and lung inside the water phantom affect the g(r) and F(r,θ) in HDR brachytherapy. The degree of the effects depends on the material, position and volume of the inhomogeneity area.

Solidification phenomena in creep resistant 9Cr weld metals and their implications on mechanical properties

Martensitic 9% Cr steels play an important role in the implementation of modern and efficiency-enhanced power generation technologies. In the presented study, metallurgical solidification phenomena in heat-resistant 9% Cr filler metals and their effects on the mechanical properties of the weld metal were analysed. The focus was on welded joints of steel grades P91 and CB2, which were welded with flux-cored wires. The investigation of welded joints and weld metals in the creep-damaged and unloaded condition provided detailed inspects into the formation and development of inhomogeneous areas. The microstructure of the individual weld metals was characterized in detail in the as-welded and in the heat-treated condition. It became apparent that inhomogeneities were formed in large areas of the weld metal. In particular, EDX measurements made it possible to explain these solidification phenomena and trace their development within the manufacturing process of the welded joints. It was found that even a slight uneven distribution of chromium and a diffusion of carbon caused extensive negative effects on the development of weld metal microstructures. In addition, the influence of these microstructural inhomogeneities on both the mechanical weld metal properties and the creep rupture strength is discussed. Finally, test welds were performed to optimize the microstructure of the flux-cored wire weld metal and possibilities to avoid microstructural inhomogeneities were derived. The results show that the short-term and long-term properties of the weld metal are affected by the inhomogeneous areas within the weld metal. In summary, it can be assumed that for steel grades P91 and CB2 the safety of plants in high-temperature operation is not endangered.

Enhanced Non-Uniformity Modeling of 4H-SiC Schottky Diode Characteristics Over Wide High Temperature and Forward Bias Ranges

A practical model, adequate for full reproduction of inhomogeneous Schottky diodes' forward characteristics over wide high-temperature and bias ranges, is proposed. According to this p-diode model, the Schottky contact current is considered to flow through m parallel-connected internal diodes, each with stable, constant barrier height and specific series resistance (both main model parameters). The value of m, required to reproduce the entire electrical forward behavior of a non-uniform Schottky contact, is directly connected to a particular model parameter (p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> ), used to define the inhomogeneity degree. The p-diode model was tested on forward characteristics measured for both Ni and commercial Ti Schottky diodes on 4H-SiC, which exhibited varying degrees of inhomogeneity. Excellent replication of experimental curves was achieved for all investigated samples, even those with obvious irregularities, such as “humps”, explained in the model by the series resistances' influence. In the case of m = 1, the proposed model does not produce identical results with the conventional model of a homogeneous Schottky contact if p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> ≠ 0. The value of this parameter indicates how much of an inhomogeneous contact's area is essentially used for current conduction.

Long-range action effects in the formation of nanostructured topocomposites under the impact of combined ion-plasma flows

The article updates the long-range action effect in the formation of nanostructured topocomposites under the conditions of the ion-plasma impact. The authors study the features of the concentration dependences of the distribution of elements in the boundary layers in the formation of the two-layer system "film-base". They determine that under the conditions of the implementation of the cascade cross-effect at considerable depths in the material of the hard-alloy base, locally inhomogeneous areas are formed, resulting in an increase in the microhardness of the material. Within the framework of the worked out simulation model, the study of factors contributing to the manifestation of the long-range action effect is undertaken. The contribution to the change of concentration dependences of the temperature, different diffusion mechanisms and the pressure gradient is established and differentiated. Based on the synthesis and analysis of the dynamics of the competing processes of "deceleration - acceleration" of the diffusion, the explanation to the formation of the hardened sublayers in the hard-alloy base of topocomposites and their role in the manifestation of the long-range action effect is offered.

Modeling of the Markiv random field for the purpose of its further optimization and application

Models of the Markov random field are investigated. The main improvements of the Markov random field model are investigated. If we consider Markov models of random fields with binary conditional distributions, which include stochastic evolution in time, which is based on the autoregression structure for a large-scale model, these models retain the flexibility of static Markov random field models to reproduce the representation of spatial dependence in a small-scale model. Bayesian estimation in this case is achieved through the use of a so-called algorithm that requires the generation of auxiliary random fields, but does not require the use of ideal samples. Markov random fields are a powerful tool in machine learning. It is often necessary to model such fields between dissimilar objects, which leads to the fact that the nodes in the graph belong to different types of data. To model inhomogeneous areas using graphical models, it is necessary to assign different types of distributions (binary, Gaussian, Poisson, exponent, exponential, etc.) to the model nodes. The concept of conditional random fields is considered in the article, their features, advantages and disadvantages are established. The application of binary data in Markov models of random fields is considered, which generates a class of models of binary Markov random fields. It is established that the discrete nature of Markov random fields allows a wider range of possible values of dependence, ie negative dependence. The model, loss function and distribution of the Markov random field function are investigated. Strengthening of Markov random fields is proposed. The pairwise exponential Markov random field is considered.

Seasonal Rainfall Variability in Ethiopia and Its Long-Term Link to Global Sea Surface Temperatures

Investigating the influence of sea surface temperatures (SSTs) on seasonal rainfall is a crucial factor for managing Ethiopian water resources. For this purpose, SST and rainfall data were used to study a wide range of inhomogeneous areas in Ethiopia with uneven distribution of rainfall for both summer (1951–2015) and spring (1951–2000) seasons. Firstly, a preliminary subdivision of rainfall grid points into zones was applied depending on spatial homogeneity and seasonality of rainfall. This introduced new clusters, including nine zones for summer rainfall peak (July/August) and five zones for spring rainfall peak (April/May). Afterward, the time series for each zone was derived by calculating the rainfall averaged over grid points within the zone. Secondly, the oceanic regions that significantly correlated with the Ethiopian rainfall were identified through cross-correlations between rainfalls averaged over every homogeneous zone and the monthly averaged SST. For summer rainfall as a main rainy season, the results indicated that the Gulf of Guinea and southern Pacific Ocean had a significant influence on rainfall zones at a lag time of 5–6 and 6–7 months. Besides, for summer rainfall zones 8 and 9 at lag time 5–6 months, the common SST regions of the southern Pacific Ocean showed the opposite sense of positive and negative correlations. Thus, the difference in SSTs between the two regions was more strongly correlated (r ≥ 0.46) with summer rainfall in both zones than others. For the spring season, the results indicated that SST of the northern Atlantic Ocean had a strong influence on spring rainfall zones (3 and 5) at a lag time 6–7 months, as indicated by a significant correlation (r ≥ −0.40). Therefore, this study suggests that SSTs of southern Pacific and northern Atlantic oceans can be used as effective inputs for prediction models of Ethiopian summer and spring rainfalls, respectively.

Triggered gas switch with a sharply non-uniform electric field at the electrode with negative potential

The paper presents the results of studies for two triggered high-pressure gas switches intended for pulse-periodic capacitive storages with the stored energy level of about 100–1000 J. The operating voltage of the first switch is up to 50 kV, for the second switch is over 200 kV. A feature for both switches is a configuration with a sharply non-uniform field at the electrode with negative potential. In the charging process of a capacitive energy storage, a corona-streamer discharge occurs in the switch, the current of which increases with increasing voltage. Cathode discharge plasma shields a sharp cathode edge and local areas of inhomogeneity with increased emission and also gives a uniform flow of initiating electrons into the gap of the switch. As a result, conditions in the discharge gap vary slightly from pulse to pulse.

The stress-strain state of the tank on soil foundation with local inhomogeneity

This article aims to numerically investigate the stress-strain state of the tank at the appearance a local area of inhomogeneity in the soil foundation. We have established the size of the zone of influence of the inhomogeneity area of the base on the work of the tank wall. Also, we have formulated proposals to adjust the requirements of the Russian regulatory and technical documentation.

Groove Pancreatitis - Cause of Recurrent Pancreatitis

Abstract Background. Groove pancreatitis or paraduodenal pancreatitis represents a rare type of pancreatitis, and can be classified into cystic dystrophy of the duodenal wall in heterotopic pancreas, paraduodenal cyst or myoadenomatosis. Case presentation. We present a case of a 58 year old man, drinker and smoker who was admitted in the Department of Gastroenterology for abdominal pain, weight loss and nausea. From his history we have noticed frequent presentations of recurrent acute pancreatitis in the last two years. Laboratory tests have revealed cholestasis, high value of lipase and high value of amylase, with normal value of CA 19.9. The magnetic resonance from the last two years showed the same appearances: a large and edematous head of pancreas, a thickening of the wall of adjacent duodenum and an inhomogeneous area with cystic transformation in the head of the pancreas. We performed endoscopic ultrasound with fine needle aspiration. The histopathological result showed only inflammatory cells. We have established the diagnosis of groove pancreatitis. Conclusion. Groove pancreatitis represents a rare condition, with an incidence of 0.4%-14% on biopsies. Endoscopic ultrasound is the best method for diagnosis, it could evaluate also the duodenal wall.

Is fat suppression in T1 and T2 FSE with mDixon superior to the frequency selection-based SPAIR technique in musculoskeletal tumor imaging?

ObjectiveTo determine the image quality of fast spin echo (FSE) with mDixon relative to spectral attenuated inversion recovery (SPAIR) FSE sequences in musculoskeletal tumor imaging on a 1.5-T MRI system.Materials and methodsIn a HIPAA-compliant prospective study, 265 patients requiring musculoskeletal tumor MRI scans were included. Patient consent was waived by the medical ethical committee. Two radiologists compared SPAIR and mDixon FSE water-only images in both T2- and T1-weighted gadolinium-enhanced (T1-Gd) sequences using a five-point scale (paired samples t test and visual grading characteristics curves (VGC)). Homogeneity of fat suppression, noise, contrast, several artifacts (motion, phase, edge blurring and water–fat swap) and subjective preference were evaluated.ResultsReaders did not have subjective preference for either sequence in 71% and 55% (reader 1 and 2, respectively). Scores for homogeneous fat suppression were significantly (p < 0.01) higher for mDixon (4.88 in T2 and 4.87 in T1-Gd) than for SPAIR (4.31 for T2 and 4.21 for T1-Gd). All VGC curves for homogeneity demonstrated preference for mDixon. In 57 individual mDixon cases, fat-suppression homogeneity was strikingly better (≥ 2 points higher), namely in areas with field heterogeneity. Average noise and contrast scores were slightly higher for mDixon, as were motion artifact scores for SPAIR (< 0.5 points difference).ConclusionsmDixon fat suppression was significantly more homogeneous than SPAIR on both T2 and T1-Gd FSE images in musculoskeletal tumor protocols. In areas of field inhomogeneity, mDixon outperforms SPAIR. SPAIR had slightly less motion artifacts than mDixon.

PSDSD-A Superpixel Generating Method Based on Pixel Saliency Difference and Spatial Distance for SAR Images.

Superpixel methods are widely used in the processing of synthetic aperture radar (SAR) images. In recent years, a number of superpixel algorithms for SAR images have been proposed, and have achieved acceptable results despite the inherent speckle noise of SAR images. However, it is still difficult for existing algorithms to obtain satisfactory results in the inhomogeneous edge and texture areas. To overcome those problems, we propose a superpixel generating method based on pixel saliency difference and spatial distance for SAR images in this article. Firstly, a saliency map is calculated based on the Gaussian kernel function weighted local contrast measure, which can not only effectively suppress the speckle noise, but also enhance the fuzzy edges and regions with intensity inhomogeneity. Secondly, superpixels are generated by the local k-means clustering method based on the proposed distance measure, which can efficiently sort pixels to different clusters. In this step, the distance measure is calculated by combining the saliency difference and spatial distance with a proposed adaptive local compactness parameter. Thirdly, post-processing is utilized to clean up small segments. The evaluation experiments on the simulated SAR image demonstrate that our proposed method dramatically outperforms four state-of-the-art methods in terms of boundary recall, under-segmentation error, and achievable segmentation accuracy under almost all of the experimental parameters at a moderate segment speed. The experiments on real-world SAR images of different sceneries validate the superiority of our method. The superpixel results of the proposed method adhere well to the contour of targets, and correctly reflect the boundaries of texture details for the inhomogeneous regions.

Structural feature learning-based unsupervised semantic segmentation of synthetic aperture radar image

Region map is the sparse representation of a high-resolution synthetic aperture radar (SAR) image on the middle-level semantic layer in its semantic space. Based on the semantic information of the region map, the high-resolution SAR image is divided into hybrid, structural, and homogeneous pixel subspaces. The segmentation of SAR images can be divided into these three subspaces segmentation, of which the segmentation of hybrid subspace has more challenge because of complex structures. There are often many extremely inhomogeneous areas in the hybrid pixel subspace. Are these nonconnected areas in the same or different classes? To solve this problem, a Bayesian learning model with the constraint of sketch characteristic and an initialization method is proposed to construct a structural vector that can reflect the essential features of each extremely inhomogeneous area. Then, the unsupervised segmentation of the hybrid pixel subspace can be realized by using the structural vectors of these areas in this paper. Theoretical analysis and experimental results show that the performance of the hybrid pixel subspace segmentation realized by the structural vectors based on the Bayesian learning model proposed in the paper is better than that only used by hand designing features.

Development of a flexible belt on an elastic multi-stiffness foundation tire model for a heavy load radial tire with a large section ratio

Abstract The study investigates the planar vibration characteristics of a radial tire with a large section ratio for a heavy load vehicle. A proposed tire model with a flexible belt on an elastic multi-stiffness foundation is investigated via theoretical modeling and an experimental modal analysis. Additionally, the parametric identification of the proposed tire model is discussed. When compared with the conventional sidewall stiffness model for general car tires, the analytical multi-stiffness function of a large section ratio sidewall is derived by combining the membrane feature caused by inflation pressure and the structural deformation caused by sidewall curvature. The Euler beam model specifically assesses the circumferential vibration of the flexible belt. Additionally, we combine the sidewall multi-stiffness function of the membrane pre-tension stiffness, and the structural deformation stiffness is integrated into the flexible belt model. The effect of inflation pressure on the circumferential vibration of the flexible belt is investigated via the experimental modal method and theoretical Euler beam model. The stretching, bending, shearing deformations, and stiffness characteristics of the curved sidewall arc are derived via the virtual work principle. The nonlinear stiffness characteristic of the tire sidewall is calculated relative to the radial deformation of the sidewall segment. The effect of the inhomogeneous section area on the multi-stiffness function is discussed. The experimental and theoretical results indicate the following: (1) The multi-stiffness function of the curved sidewall assesses the pre-tension membrane feature and structural deformation, which is related to the inflation pressure, structural curvature, and material properties; (2) the multi-stiffness function of the curved sidewall is nonlinear relative to the radial deformation of the sidewall arc, and the nonlinear characteristic is highlighted with high inflation pressure; (3) the inhomogeneous feature of the section area affects the multi-stiffness of the curved sidewall. Given the combined sidewall multi-stiffness function of the membrane feature and structural deformation, the elastic foundation model acts as an independent module to enrich the flexible belt beam model. Additionally, a flexible belt on an elastic multi-stiffness foundation tire model is suitable for a radial tire with a large section ratio of a heavy load vehicle or tires under impulsive loads and large deformations.

Evaluation of anomaly detection capabilities using a non-orthogonal camera angle in pulse-phase thermography

Pulse-phase thermography (PPT) is widely used to nondestructively inspect internal defects in fiber reinforced polymers. However, the challenges using PPT for complex shapes is poorly documented in literature. Only small changes in the object distance have been considered.Complex parts can have significant variations in object distance and thus, in detected radiation. In this contribution, the effect of a non-orthogonal camera angle with respect to a flat sample, leading to varying object distances and an inhomogeneous sound background area in phasegrams, is investigated. Samples with artificial round and square defects of different sizes are positioned under varying angles with respect to the camera, representing geometric properties of complex parts. The construction of the thermographic system and the experimental setup to systematically vary the angle between camera and specimen is presented. We investigated the change of the signal-to-noise ratio (SNR) of artificial delaminations in PPT measurements under varying object distances. The SNR in a distance of 136 mm out of the focal plane is sufficiently high for image feature extraction. Phasegrams are exported to a colored representation, leading to a higher contrast in distinct color channels. An algorithm which extracts and merges defect information from three different color channels is developed. Challenging lighting conditions lead to a noisy background having artifacts. The developed filter performs better in defect detection and size quantification than a global or local threshold in grayscale phasegrams under those conditions.

A Clutter Suppression Method for Dual-channel Circular SAR-GMTI

Ground moving target indication (GMTI) technology is an important development direction in the field of SAR signal processing, and the performance of GMTI is determined by clutter suppression directly. Since the trajectory of airborne platform is a circular arc and the beam directions of antennas are time-varying in the circular SAR (CSAR) mode, the classical channel registration methods for the strip-map SAR are no longer applicable. Based on the measured data of a CSAR system, channel calibration and channel equalization are investigated to eliminate the phase and amplitude differences of the clutter between the channels. Further, according to the complementary property of displaced phase center antenna (DPCA) and along-track interferometry (ATI) technologies, we propose a clutter suppression method in the complex image domain by utilizing the interference phase of ATI to weight the DPCA amplitude. The process results of measured data prove a good capability for clutter suppression both in homogeneous and inhomogeneous areas.

Methodology of High-Carbon Wire Rod Perlite Grain Grade Identification

The quality of the high-carbon rod is determined by mechanical properties, which depend on microstructure characteristics, in particular the perlite grain grade. The existing technique for determining the perlite dispersion has the main drawback - the subjectivity of choosing the five worst view fields for evaluation, which reduces the accuracy of the determination results. The article presents the results of a study aimed at increasing the objectivity and accuracy of the evaluation of high-carbon wire rod perlite grain grade. An improved technique for determining the high-carbon wire rod perlite grain grade – Pgg with five view fields is proposed. The cross-section of the rod sample is considered as an inhomogeneous area from the perlite dispersion point of view, which is divided into three annular zones with different levels of perlite dispersion. Selection of five view fields is carried out as follows: one from the center of the central zone, two fields in the second - an intermediate zone and two fields in the outer zone. Statistical analysis of the experimental data showed that all view fields should be located on the same diagonal. The location of the view fields is fixed and is unchangeable for all samples under study. The technique described in the article is an effective tool for analyzing the structure of high-carbon steel wire rod.

Selective arterial embolization for a high-flow priapism following perineal trauma in a young gymnast

High-flow priapism is a rare condition in children, usually due to a perineal trauma. We present a case of traumatic highflow priapism investigated by Doppler ultrasound and managed by angiography and selective embolization of a branch of the internal pudendal artery. A 13-year-old gymnast underwent perineal trauma during training and developed a high-flow priapism. The first ultrasound (immediately after the trauma) showed the presence of an inhomogeneous area of 3 x 2 cm associated with an anechoic vascularized area (pseudoaneurysm) in the right corpus cavernosum. On the left side there was a similar finding, but of smaller size. After 3 weeks the pseudoaneurysm on the left was completely obliterated while the right one was still present. Angiography and superselective catheterization of a branch of the left pudendal artery and its embolization with microspheres and with metal microcoils were performed. After the procedure, ultrasound showed that the right pseudoaneurysm was completely obliterated and there were no more branches reaching it. The cavernous arteries were both pervious. Selective arterial embolization is a safe treatment that can also be used in pediatric patients.

True Ohmic contact on RF sputtered ZnO thin film by using the nonalloy Ti/Au metallization scheme

Metal contact (Ohmic or Schottky) is vital for building different ZnO based IC compatible electronic devices. Literature has seen a tremendous development on metal contacts on this specific semiconductor by using a range of metallization scheme, but in all cases, ZnO film was very thick, highly doped, and deposited on Al2O3 substrate, even though this substrate is not appropriate for modern IC technology. For estimation of the specific contact resistance, transmission line method (TLM) has been used predominantly instead of Schottky barrier height (SBH) model, considering thermionic emission (TE) theory. However, SBH model is more realistic and furnishes accurate statistics of the distinct parameters of ohmic contacts compared to TLM theory, where TLM gives only specific contact resistance. So, we are presenting the electrical properties of Ti/Au nonalloy ohmic contact developed on 20 nm undoped RF sputtered ZnO thin film on SiO2/p-Si and SiO2/n-Si substrates using SBH model considering thermionic emission theory. Further, using X-ray diffraction, photo luminance, and scanning electron microscopy, we were investigated the crystal structure, energy band gap, and surface morphology of the thin film. And, current-voltage (I –V) data were measured using a semiconductor parameter analyzer. Barrier heights and other parameters of developed metallization scheme extracted from experimental I-V characteristics of the fabricated ohmic contacts considering carrier transport at the interface is governed by thermionic emission theory. It can be found that the deviation in barrier heights which are estimated from semi -log current versus voltage (ln(I)–V) characteristics and extracted from Richardson plot, because of barrier inhomogeneity, series resistance, and actual contact area. To decrease this deviation we have analyzed the barrier heights after rectify the voltage axis by considering the series resistance, but series resistance correction alone is not sufficient. Finally, lowest specific contact resistance was achieved compared to any metallization scheme using Richardson plot, this approach and structure are first time reported specifically on ZnO.