High speed detection of retinal blood vessels in fundus image using phase congruency

Detection of blood vessels in retinal fundus image is the preliminary step to diagnose several retinal diseases. There exist several methods to automatically detect blood vessels from retinal image with the aid of different computational methods. However, all these methods require lengthy processing time. The method proposed here acquires binary vessels from a RGB retinal fundus image in almost real time. Initially, the phase congruency of a retinal image is generated, which is a soft-classification of blood vessels. Phase congruency is a dimensionless quantity that is invariant to changes in image brightness or contrast; hence, it provides an absolute measure of the significance of feature points. This experiment acquires phase congruency of an image using Log-Gabor wavelets. To acquire a binary segmentation, thresholds are applied on the phase congruency image. The process of determining the best threshold value is based on area under the relative operating characteristic (ROC) curve. The proposed method is able to detect blood vessels in a retinal fundus image within 10 s on a PC with (accuracy, area under ROC curve) = (0.91, 0.92), and (0.92, 0.94) for the STARE and the DRIVE databases, respectively.     

Women’s mobility,neighbourhood socio-ecologies and homemaking in urban informal settlements

Abstract

The paper contributes to the growing research on relational thinking about housing and home by exploring the informal homes of rural migrants in Khulna city, Bangladesh. The concept of ‘unbounding’ is used to trace the fluidity and connections established between migrant homes and neighbourhood socio-ecologies. Walking interviews exploring women’s livelihoods reveal that different expendable agencies of the urban environment (e.g. trash, weeds and animal excreta) create conditions for labour in which migrant women hold specific competencies to secure essential resources for home. Unbounding positions home within a socio-ecology of multiple houses that women traverse to support their urban living. The approach offers opportunities to examine the unique ways urban homeless populations strategically as well as affectively engage with under-recognized agencies and actors in informal settlements. Unbounding provides a useful lens with which to raise new conceptual and empirical questions about housing and home in relation to the city that contributes to the homes and livelihoods of marginalized populations.     

Development of kenaf fibre reinforced polymer laminate for shear strengthening of reinforced concrete beam

Fabrication of green fibre composite laminate for strengthening of reinforced concrete structure is one of the current interests in the field of construction industry. The aim of this research was to develop kenaf fibre reinforced polymer (KFRP) laminate for shear strengthening of reinforced concrete beam. Comprehensive design and theoretical models were also proposed for KFRP laminate shear strengthened beam. In the experimental programme, KFRP laminate had been fabricated with various fibre content to obtain optimal mix ratio. Physical and mechanical properties of KFRP laminates were experimentally investigated. Three reinforced concrete beam specimens were prepared for structural investigations. Results showed that KFRP laminate with maximum fibre content had the highest tensile strength and the laminate was found to be elastic isotropic in nature. The KFRP laminate strengthened beam had 100 % higher shear crack load and 33 % ultimate failure load as compared to un-strengthened control beam. It reduced the numbers and width of cracks and had shown strain compatibility behavior with shear reinforcement. The failure load, ductility, crack patterns and strain characteristics of KFRP laminate strengthened beam were found to be closely comparable with CFRP laminate strengthened beam. The experimental results satisfactorily verified the proposed design and theoretical models.     

Phonon transmission of vacancy disordered armchair silicene nanoribbon

This work demonstrates the atomic vacancy effects on the phonon properties of armchair silicene nanoribbon in a step by step process for the first time. The phonon localization effect figures out the fact that vacancies cause to high-energy phonons become localized, whereas low-energy phonons can easily transmit. The vacancy reduces high-energy phonon transmission severely compared to low-energy phonon. It is also found from phonon density of states that high-frequency phonons soften towards the low-frequency region. The simulated phonon bandstructure verifies that most of the phonon branches transform to a nondegenerate state from a degenerate state and shifted toward a lower frequency regime due to the presence of vacancies. The overall consequences of atomic vacancies on the phonon thermal conductance disclose the reality that only a few atomic vacancies result in a vital reduction of phonon thermal conductance. In addition, the entropy of the disordered system is investigated.     

Effect of non-equilibrium homogeneous condensation on the self-induced flow oscillation of supersonic impinging jets

Supersonic impinging jets are characterized by a strong coupling between the flow and acoustic fields with a self-contained feedback mechanism. This self-induced oscillatory flow make thermal and mechanical loading more severe and produces severe noise at discrete frequencies, which may cause sonic fatigue of the structures and also may damage various instruments and equipments. These loads are also accompanied by dramatic lift loss, severe ground erosion and hot gas ingestion. To control the flow it is needed to clarify the characteristics and mechanism of oscillation. However, in actual jet flows, the working gas may contain condensable gas such as steam or moist air. In these cases, non-equilibrium condensation may occur at the region between nozzle exit and an object. The jet flow with non-equilibrium condensation may be quite different from that without condensation. Therefore, the numerical investigation of the self-induced flow oscillation of supersonic impinging moist air jet was carried out in this study. Moreover, this paper aims to clarify the effect of non-equilibrium condensation on the characteristic of pressure fluctuations during the impingement of under-expanded supersonic moist air jets on a perpendicular flat plate.     

Enhanced Light‐Harvesting Capability of a Panchromatic Ru(II) Sensitizer Based on π‐Extended Terpyridine with a 4‐Methylstylryl Group for Dye‐Sensitized Solar Cells

A novel Ru π‐expanded terpyridyl sensitizer, referred to as HIS‐2, is prepared based on the molecular design strategy of substitution with a moderately electron‐donating 4‐methylstyryl group onto the terpyridyl ligand. The HIS‐2 dye exhibits a slightly increased metal‐to‐ligand charge transfer (MLCT) absorption at around 600 nm and an intense π–π* absorption in the UV region compared with a black dye. Density functional theory calculations reveal that the lowest unoccupied molecular orbital (LUMO) is distributed over the terpyridine and 4‐methylstyryl moieties, which enhances the light‐harvesting capability and is appropriate for smooth electron injection from the dye to the TiO₂ conduction band. The incident photon‐to‐electricity conversion efficiency spectrum of HIS‐2 exhibits better photoresponse compared with black dye over the whole spectral region as a result of the extended π‐conjugation. A DSC device based on black dye gives a short‐circuit current (J_SC) of 21.28 mA cm^?2, open‐circuit voltage (V_OC) of 0.69 V, and fill factor (FF) of 0.72, in an overall conversion efficiency (η) of 10.5%. In contrast, an HIS‐2 based cell gives a higher J_SC value of 23.07 mA cm^?2 with V_OC of 0.68 V, and FF of 0.71, and owing to the higher J_SC value of HIS‐2, an improved η value of 11.1% is achieved.     

A Computational Model of NBTI and Hot Carrier Injection Time-Exponents for MOSFET Reliability

Theories of interface trap generation in Negative Bias Temperature Instability (NBTI) and Hot Carrier Injection (HCI) mechanisms are unified under the geometric interpretation and computational modeling of Reaction-Diffusion (R-D) theoryframework. Analytical derivations that predict the degradation are shown, simulation methodology is explained and numerical solutions are obtained. Time-exponents and degradation behavior under dynamic bias in agreement with experimental observations are discussed. Implications regarding ultra-scaled surround-gate device structures are presented.