Saturation Channel Research Articles

A novel color space of fundus images for automatic exudates detection

Abstract This paper has compared the performance of different color spaces of fundus images for automatic detection of exudates. A convolutional neural network was employed to assess the performances of different color spaces generated by orthogonal transformation of the original colors in red/green/blue (RGB) space. Experiments were conducted on two publicly available databases: (1) DIARETDB1 and (2) e-Ophtha. Based on the experimental results, this study has proposed a new color space of fundus images with three channels: (i) second eigenchannel of the RGB space, (ii) hue and (iii) saturation channels of Hue/Saturation and Intensity (HSI) space. This achieved an accuracy, sensitivity and specificity of 98.2%, 0.99 and 0.98, respectively. Twenty times 20-fold cross validation technique confirmed that proposed color space obtained higher replicability compared with conventional color spaces.

Effects of permeability and electric field on nonlinear Oberbeck Electro-convection in a vertical poorly conducting fluid saturated porous channel

The effects of permeability on nonlinear Oberbeck Electro-convection in a poorly conducting fluid saturated porous medium in a vertical channel, when the walls are held at different temperatures with temperature difference perpendicular to gravity, is studied using the modified Navier stokes equation in the presence of both induced and an applied electric field. Both analytical and numerical solutions for the non-linear coupled equations governing the motion are obtained and found that analytical solutions agree well with numerical solutions for values of the buoyancy parameter N <1. It is shown that OBEC can be controlled by maintaining the temperature difference either in the same direction or opposing the potential difference with a suitable value of electric number W. The effect of W on velocity, temperature, rate of heat transfer, skin friction and mass flow rate are computed and the results are depicted graphically. We found that the analytical solutions for velocity and temperature distributions are in close agreement with those obtained from the numerical method for small values of N. We also found that an increase in W accelerates the flow and hence increases linearly the skin friction and mass flow rate. Further, the velocity and temperature have the same behavior for different values of porous parameter when the temperature difference and the potential difference are in the same or in the opposite directions.Kathmandu University Journal of Science, Engineering and Technology Vol. 12, No. I, June, 2016

Viscous Fingering of Miscible Liquids in Porous and Swellable Media for Rapid Diagnostic Tests.

In lateral flow and colorimetric test strip diagnostics, the effects of capillary action and diffusion on speed and sensitivity have been well studied. However, another form of fluid motion can be generated due to stresses and instabilities generated in pores when two miscible liquids with different densities and viscosities come into contact. This study explored how a swellable test pad can be deployed for measuring urea in saliva by partially prefilling the pad with a miscible solution of greater viscosity and density. The resultant Korteweg stresses and viscous fingering patterns were analyzed using solutions with added food color through video analysis and image processing. Image analysis was simplified using the saturation channel after converting RGB image sequences to HSB. The kinetics of liquid mixing agreed with capillary displacement results for miscible liquids undergoing movement from Korteweg stresses. After capillary filling, there was significant movement of liquid due to these fluidic effects, which led to mixing of the saliva sample with an enzyme test solution. Owing to the simplicity and speed of this test method, urea can be analyzed with an electronic nose over a useful range for detecting salivary urea concentration for rapid and early detection of dehydration.

Fake Colorized Image Detection

Image forensics aims to detect the manipulation of digital images. Currently, splicing detection, copy-move detection and image retouching detection are drawing much attentions from researchers. However, image editing techniques develop with time goes by. One emerging image editing technique is colorization, which can colorize grayscale images with realistic colors. Unfortunately, this technique may also be intentionally applied to certain images to confound object recognition algorithms. To the best of our knowledge, no forensic technique has yet been invented to identify whether an image is colorized. We observed that, compared to natural images, colorized images, which are generated by three state-of-the-art methods, possess statistical differences for the hue and saturation channels. Besides, we also observe statistical inconsistencies in the dark and bright channels, because the colorization process will inevitably affect the dark and bright channel values. Based on our observations, i.e., potential traces in the hue, saturation, dark and bright channels, we propose two simple yet effective detection methods for fake colorized images: Histogram based Fake Colorized Image Detection (FCID-HIST) and Feature Encoding based Fake Colorized Image Detection (FCID-FE). Experimental results demonstrate that both proposed methods exhibit a decent performance against multiple state-of-the-art colorization approaches.

Understanding Chinese consumer adoption of apparel mobile commerce: An extended TAM approach

This study proposes and applies an extended technology acceptance model (TAM) that incorporates brand equity and website quality as determinants of perceived usefulness and perceived ease‐of‐use to predict Chinese consumer intention to use apparel mobile commerce (m-commerce). 786 eligible responses were collected via an online questionnaire survey. The psychometric properties of the proposed extended TAM model were examined and the multiple regression method was applied to test the hypotheses. All dimensions of brand equity (i.e., brand loyalty, brand association, brand perceived quality, and brand image) significantly affect Chinese consumer perceived ease of use of apparel m-commerce while brand loyalty, perceived quality, and image enhance consumer perceived usefulness. This suggests a greater need for attention to branding effect within an increasingly saturated apparel m-commerce channel. All dimensions of website quality (i.e., website system quality, information quality, and service quality) significantly influence consumer perceived usefulness of apparel m-commerce while website system quality and information quality increase perceived use easiness. These website qualities play an important role in meeting the needs of consumers who are looking for good usability of mobile shopping. Both perceived usefulness and perceived ease of use result in positive consumer attitudes toward shopping apparel via m-commerce channel. The positive attitude and perceived usefulness lead to a greater likelihood for Chinese consumers to use apparel m-commerce. The research model exhibits a high explanatory power, collectively accounting for 64.6% of the variance in Chinese consumer intention to use apparel m-commerce.

Floodwater detection on roadways from crowdsourced images

This work proposes an image processing pipeline for detecting floodwater extent on inundated roadways from image data captured and generated by mobile consumer devices, such as smartphones. A sample data-set collected from actual nuisance flooding events in Norfolk, VA and location-matched reference images are used to demonstrate the proposed approach. The highly variable nature of crowdsourced data manifests as discrepancies in location-matched dry/flooded condition image pairs, making extracting inundation information more challenging. These discrepancies may include differences in resolution, lighting and environmental conditions. Scenes may include dynamic objects, such as vehicles and pedestrians, on the roadway. In the proposed pipeline, images go through a set of pre-processing operations consisting of water edge detection, image inpainting and contrast correction. A Region-Based Convolutional Neural Network (R-CNN) is trained, tested and deployed for vehicle detection. An inpainting procedure removes vehicles detected by the R-CNN. The images are registered using the Scale Invariant Feature Transform flow algorithm. Boundaries of the flooded area are detected. Reflections of landmarks and sky/clouds also pose an important challenge to detection of inundated areas. Reflections from nearby landmarks are first identified, then used as a seed for identifying the remaining water body, including reflections of sky/clouds, through saturation channel processing. The result is further processed with the detected water edge lines. False positives are removed. The proposed method is applied to real-world images and its accuracy is evaluated. The results show that the method produces satisfactory results despite the complexities of the crowdsourced image data and dynamic environment.

AUTOMATED ULCER AND BLEEDING CLASSIFICATION FROM WCE IMAGES USING MULTIPLE FEATURES FUSION AND SELECTION

In the area of medical imaging and computer vision, automatic diagnosis of ulcer and bleeding from wireless capsule endoscopy images has been an active research domain. It contains several challenges including low contrast, complex background, lesion shape and color which affect its segmentation and classification accuracy. In this article, a novel method for automated detection and classification of stomach infection is implemented. The proposed method consists of four major steps including preprocessing, lesion segmentation, image representation and classification. The lesion contrast is improved in preprocessing step by employing 3D-box filtering, 3D-median filtering and HSV transformation. In the second step, geometric features are extracted and applied to the saturated channel to give a binary image. The binary image is further improved by fusion of generated mask. After that, extraction of three types of features including color, shape and surf is performed from HSV and binary segmented images and their information is fused by a serial based method. A principal component analysis (PCA) and correlation coefficient based feature selection approach is proposed which are classified by multi class support vector machine (M-SVM). The proposed method is evaluated on personally collected images of three different classes including ulcer, bleeding and healthy. The M-SVM performs well with a maximum accuracy of 98.3% which shows the authenticity of presented method.

Combined effects of heat and mass transfer to magneto hydrodynamics oscillatory dusty fluid flow in a porous channel

The main aim of this article is to study the combined effects of heat and mass transfer to radiative Magneto Hydro Dynamics (MHD) oscillatory optically thin dusty fluid in a saturated porous medium channel. Based on certain assumptions, the momentum, energy, concentration equations are obtained.The governing equations are non-dimensionalised, simplified and solved analytically. The closed analytical form solutions for velocity, temperature, concentration profiles are obtained. Numerical computations are presented graphically to show the salient features of various physical parameters. The shear stress, the rate of heat transfer and the rate of mass transfer are also presented graphically.

Coupled geophysical characterization of shallow fluvio-clastic sediments in Agwagune, southeastern Nigeria

Geophysical investigation performed using electrical resistivity tomography (ERT), vertical electrical sounding (VES), seismic refraction (SRF) and ground penetrating radar (GPR) techniques were used to constrain and characterize shallow lithologic units in the Cross River bank (CRB) in southeastern Nigeria. Results show that the upper layer sediments comprise a 3-5-layered lithostratigraphic sequence with high clayey content. Around the Cross River bank (CRB), the top sediments consist of loose, silty and clayey sands with low resistivities (<150 Ωm) and low P-wave velocities (300–1000 m/s). These attenuating sediments have no reasonable continuity beyond the vicinity of the CRB. The low attenuating indurated silts/sands characterized by low resistivities (<25 Ωm) and high P-wave velocities (1000–2400 m/s) underlie the first layer around in the CRB. Localized microstructures (e.g., fractures) trending east-west, and saturated sand-filled channels truncate their lateral continuities. The lacustrine clays characterized by low resistivities (<15 Ωm) and high P-wave velocities (>2400 m/s) make up the third layer. The clayey sediments impede vertical percolation of groundwater forcing it to accumulate at the bottom of the second layer resulting in high static water levels of <3 m within the CRB and >5 m elsewhere. Hydraulic gradient in the Cross River bed (CRBD) and in the coastal groundwater drives groundwater flow into the CRBD through macropores. The sediments become unstable when these macropores become enlarged as more materials are continuously transmitted through them.

Self-Aligned van der Waals Heterojunction Diodes and Transistors.

A general self-aligned fabrication scheme is reported here for a diverse class of electronic devices based on van der Waals materials and heterojunctions. In particular, self-alignment enables the fabrication of source-gated transistors in monolayer MoS2 with near-ideal current saturation characteristics and channel lengths down to 135 nm. Furthermore, self-alignment of van der Waals p-n heterojunction diodes achieves complete electrostatic control of both the p-type and n-type constituent semiconductors in a dual-gated geometry, resulting in gate-tunable mean and variance of antiambipolar Gaussian characteristics. Through finite-element device simulations, the operating principles of source-gated transistors and dual-gated antiambipolar devices are elucidated, thus providing design rules for additional devices that employ self-aligned geometries. For example, the versatility of this scheme is demonstrated via contact-doped MoS2 homojunction diodes and mixed-dimensional heterojunctions based on organic semiconductors. The scalability of this approach is also shown by fabricating self-aligned short-channel transistors with subdiffraction channel lengths in the range of 150-800 nm using photolithography on large-area MoS2 films grown by chemical vapor deposition. Overall, this self-aligned fabrication method represents an important step toward the scalable integration of van der Waals heterojunction devices into more sophisticated circuits and systems.

Mass Transfer Influence on Entropy Generation Fluctuation on Saturated Porous Channel Poiseuille Benard Flow

This paper reports a transient state numerical investigation of irreversibility in a saturated porous channel, of an aspect ratio A= 5, under vertical thermal and mass gradients. The governing equations, using the Darcy-Brinkman formulation, have been solved numerically by using Control Volume Finite Element Method (CVFEM). Only two variables are taken into account, the Schmidt number and the floatability ratio. The other parameters values are fixed related to the Poiseuille–Benard flow (at zero mass gradients). Results reveal that the flow tends towards the steady state with different regimes, which depends on both the Schmidt number and the buoyancy ratio.

Numerical study at moderate Reynolds number of peristaltic flow of micropolar fluid through a porous-saturated channel in magnetic field

This paper analyzes the MHD flow of micropolar fluid induced by peristaltic waves passing through the porous saturated channel at large Reynolds number. The flow model is formulated in the absence of assumptions of lubrication theory which yields the governing equations into a non-linear set of coupled partial differential equations which allows studying the peristaltic mechanism at non-zero Reynolds and wave numbers. The influence of other involved parameters on velocity, stream function and microrotation are discussed through graphs plotted by using Galerkin’s finite element method. Besides that, the phenomena of pumping and trapping are also analyzed in the later part of the paper. To ensure the accuracy of the developed code, obtained results are compared with the results available in the literature and found in excellent agreement. It is found that the peristalsis mixing can be enhanced by increasing Hartmann number while it reduces by increasing permeability of the porous medium.

Fast Single Image Haze Removal Method based on Atmospheric Scattering Model

In this paper, we propose an effective and efficient method to remove haze from a single input image. We first remove fine details from the minimum channel of RGB channels by a low-pass filter and then use it as a rough estimation of the transmission map. Then, we refine the rough estimation by using the saturation channel of HSI color space and local contrast. Based on the atmospheric scattering model, we then obtain a high-quality haze-removed image. Results on a variety of hazy images demonstrate the effectiveness and efficiency of our method.

Independent Artists' Access to Communications Channels: How Hard Is It Out There?

There is lack of empirical studies on how relevant major labels are for communicating the product in the digital era and, so far, divergent conclusions have been reached on the subject. Therefore, this paper analyses independent artists’ access to communication channels, in order to understand if the digital era has made it possible for these artists to promote their product in an effective and successful manner. Results indicate a not so favourable scenario regarding communication. In the digital era, several new possibilities have emerged, which are quite more accessible for independent artists. However, these are subject to market’s saturation and traditional communication channels importance was not as affected as in distribution. Actually, some of them may even have increased its relevance. Communication, for these artists, as revealed itself a non-straightforward and quite expensive area.

No-reference quality index for color retinal images

Retinal image quality assessment (RIQA) is essential to assure that the images investigated by ophthalmologists or automatic systems are suitable for reliable medical diagnosis. Measure-based RIQA techniques have several advantages over the more commonly used binary classification-based RIQA methods. Numeric quality measures can aid ophthalmologists in associating a degree of confidence to the diagnosis performed through the investigation of a certain retinal image. Moreover, a numeric quality index can provide a mean for identifying the degree of enhancement required as well as to evaluate and compare the improvement achieved by enhancement techniques. In this work, a no-reference retinal image sharpness numeric quality index is introduced that is computed from the wavelet decomposition of the images. In order to account for the obscured retinal structures in unevenly illuminated image regions, the quality index is modified by a homogeneity parameter calculated from the previously introduced retinal image saturation channel. The proposed quality index was validated and tested on two datasets having different resolutions and quality grades. A strong (Spearman's coefficient > 0.8) and statistically highly significant (p-value < 0.001) correlation was found between the introduced quality index and the subjective human scores for the two different datasets. Moreover, multiclass classification using solely the devised retinal image quality index as a feature resulted in a micro average F-measure of 0.84 and 0.95 using the high and low resolution datasets, respectively. Several comparisons with other retinal image quality measures demonstrated superiority of the proposed quality index in both performance and speed.

Computer vision based method for quality and freshness check for fish from segmented gills

The quality and freshness of a fish sample is principally hampered in the post-harvested phase due to storage, handling and processing. The quality of the sample may degrade as the days pass till it finally reaches the consumers. The quality of a post harvested fish is determined mainly by two important factors namely climatic conditions and holding time. This paper presents a completely automated computer vision based segmentation of fish gills from digital images of fish samples. Post segmentation, a statistical relationship of the segmented gill region is established to design an assessment model for fish freshness identification. The fish gills are segmented using various strategic image processing techniques like contrast enhancement, adaptive intensity threshold and active contour based methods. The model for fish freshness testing is based on the image statistical features which are derived from the gills region of the saturation channel. The variation of the statistical distribution is observed to be decreasing monotonic which is basis for design of the framework for fish quality and freshness identification. This process being non-destructive provides an efficient fish quality assessment scheme in real time.

Safety-Critical Driver Assistance Over LTE: Toward Centralized ACC

Cooperative advanced driver assistance systems (ADAS) have the potential to increase traffic efficiency and safety beyond the level of sensor-based systems. Further development toward centralized cooperative systems is motivated by the improving performance of cellular technologies. However, the suitability of cellular communication, up to now, remains an unresolved topic in current research due to high system requirements (on, e.g., latency). In a centralized system design, the control algorithm is located at a central unit and the system input, as well as the measured output, is transmitted over the cellular network. This paper addresses the technical feasibility and practicability of centralized longitudinal control of vehicles and vehicle platoons with communication over long-term evolution (LTE). The focus is laid on the investigation of the system in disturbed situations, as well as on the evaluation and optimization of the required LTE resources. Therefore, a novel design of a centralized adaptive cruise control is developed, which satisfies required stability properties and optimizes the resource usage. The evaluation is based on simulation studies since it requires a large number of devices, as well as deep data logging within LTE. In summary, system safety can be achieved with moderate requirements on the cellular technology in the case of high localization accuracy. Considering the objectives of LTE, the communication requirements should be satisfied in areas with gapless coverage and with dedicated resources in the case of saturated channel conditions.

Development of a Quasi-Steady Flow Electrochemical Paper-Based Analytical Device.

An electrochemical paper-based analytical device (ePAD) was developed for quasi-steady flow detection at microwire electrodes, for the first time. The device implements a fan shaped geometry connected to an analysis channel whereby solution is pulled from an inlet, through a channel, and into the steadily increasing capillary network of the fan. The network counteracts the decrease in solution flow rate associated with increasing viscosity within the channel, generating quasi-steady flow within the analysis channel. Microwire electrodes were embedded between two paper layers within the analysis channel, such that solution flow occurred on both sides of the wire electrodes. The quasi-steady flow ePAD increased the current by 2.5 times and 0.7 times from a saturated channel with no flow and from a single-layer paper device with flow, respectively. Amperometric detection was used for flow injection analysis (FIA) of multiple analytes at both Au and Pt microwire working electrodes, both of which provided similar sensitivity (ca. 0.2 mM-1) when normalized to the same standard. The two-layer paper devices provided a detection limit of 31 μM for p-aminophenol (PAP) using Pt electrodes and was also used to detect enzyme activity for the reaction of β-galactosidase with p-aminophenyl-galactopyranoside (PAPG). Measured enzyme kinetics provided similar Vmax (0.079 mM/min) and Km (0.36 mM) values as those found in the literature. This device shows great promise toward use in enzyme-linked immunosorbent assays or other analytical techniques where flow or washing steps are necessary. The developed sensor provides a simple and inexpensive device capable of performing multiple injection analysis with steady-flow and online detection that would normally require an external pump to perform.

Retinal image quality assessment based on image clarity and content.

Retinal image quality assessment (RIQA) is an essential step in automated screening systems to avoid misdiagnosis caused by processing poor quality retinal images. A no-reference transform-based RIQA algorithm is introduced that assesses images based on five clarity and content quality issues: sharpness, illumination, homogeneity, field definition, and content. Transform-based RIQA algorithms have the advantage of considering retinal structures while being computationally inexpensive. Wavelet-based features are proposed to evaluate the sharpness and overall illumination of the images. A retinal saturation channel is designed and used along with wavelet-based features for homogeneity assessment. The presented sharpness and illumination features are utilized to assure adequate field definition, whereas color information is used to exclude nonretinal images. Several publicly available datasets of varying quality grades are utilized to evaluate the feature sets resulting in area under the receiver operating characteristic curve above 0.99 for each of the individual feature sets. The overall quality is assessed by a classifier that uses the collective features as an input vector. The classification results show superior performance of the algorithm in comparison to other methods from literature. Moreover, the algorithm addresses efficiently and comprehensively various quality issues and is suitable for automatic screening systems.

Verilog-A implementation of a double-gate junctionless compact model for DC circuit simulations

A physically based model of the double-gate juntionless transistor which is capable of describing accumulation and depletion regions is implemented in Verilog-A in order to perform DC circuit simulations. Analytical description of the difference of potentials between the center and the surface of the silicon layer allows the determination of the mobile charges. Furthermore, mobility degradation, series resistance, as well as threshold voltage roll-off, drain saturation voltage, channel shortening and velocity saturation are also considered. In order to provide this model to all of the community, the implementation of this model is performed in Ngspice, which is a free circuit simulation with an ADMS interface to integrate Verilog-A models. Validation of the model implementation is done through 2D numerical simulations of transistors with and silicon channel length and 1 × 1019 or doping concentration of the silicon layer with 10 and silicon thickness. Good agreement between the numerical simulated behavior and model implementation is obtained, where only eight model parameters are used.