A radiative transfer model-based multi-layered regression learning to estimate shadow map in hyperspectral images

The application of Empirical Line Method (ELM) for hyperspectral Atmospheric Compensation (AC) premises the underlying linear relationship between a material’s reflectance and appearance. ELM solves the Radiative Transfer (RT) equation under specialized constraint by means of in-scene white and black calibration panels. The reflectance of material is invariant to illumination. Exploiting this property, we articulated a mathematical formulation based on the RT model to create cost functions relating variably illuminated regions within a scene. In this paper, we propose multi-layered regression learning-based recovery of radiance components, i.e., total ground-reflected radiance and path radiance from reflectance and radiance images of the scene. These decomposed components represent terms in the RT equation and enable us to relate variable illumination. Therefore, we assume that Hyperspectral Image (HSI) radiance of the scene is provided and AC can be processed on it, preferably with QUick Atmospheric Correction (QUAC) algorithm. QUAC is preferred because it does not account for surface models. The output from the proposed algorithm is an intermediate map of the scene on which our mathematically derived binary and multi-label threshold is applied to classify shadowed and non-shadowed regions. Results from a satellite and airborne NADIR imagery are shown in this paper. Ground truth (GT) is generated by ray-tracing on a LIDAR-based surface model in the form of contour data, of the scene. Comparison of our results with GT implies that our algorithm’s binary classification shadow maps outperform other existing shadow detection algorithms in true positive, which is the detection of shadows when it is in ground truth. It also has the lowest false negative i.e., detecting non-shadowed region as shadowed, compared to existing algorithms

Characteristics and impact of nystagmus on visual acuity and eye movements in children with and without Down’s syndrome

Nystagmus, an involuntary oscillation of the eye, is one of the most common visual impairments occurring in individuals with Down’s syndrome, affecting between 15-30% of that population. In the typical population, nystagmus affects 0.02% of children. Due to the frequent occurrence of nystagmus in Down’s syndrome, nystagmus often appears to be assumed to be part of the condition and overlooked in this population of children. This study was designed to determine whether nystagmus is, in fact, the same or a different condition in children with and without Down’s syndrome. First, we investigated the visual characteristics of children with Down’s syndrome with and without nystagmus, by retrospectively reviewing clinical records of 198 children in the Down’s Syndrome Vision Research Unit cohort between 1992 and 2016. To compare the characteristics of nystagmus waveforms and the visual characteristics, we then conducted optometric assessments and recorded eye movements on 28 children with Down’s syndrome and 17 typically developing children with nystagmus. Further to this, we recorded the eye movements of both groups of children with nystagmus along with 20 children with Down’s syndrome and 20 typical children with no nystagmus while fixating on a stationary and a moving target. The aim was to characterize and compare the accuracy and precision of eye movements during fixation and when following a moving target for each group of children. The findings from this study suggest that nystagmus in children with Down’s syndrome is not a different condition from nystagmus in typically developing children. In addition, nystagmus has similar effects on visual acuity and eye movement performance in both groups of children with nystagmus. Therefore, children with Down’s syndrome and nystagmus should receive the same level of attention from health and education services that typical children with nystagmus do

An end-to-end hyperspectral scene simulator with alternate adjacency effect models and its comparison with cameoSim

In this research, we developed a new rendering-based end to end Hyperspectral scene simulator CHIMES (Cranfield Hyperspectral Image Modelling and Evaluation System), which generates nadir images of passively illuminated 3-D outdoor scenes in Visible, Near Infrared (NIR) and Short-Wave Infrared (SWIR) regions, ranging from 360 nm to 2520 nm. MODTRAN TM (MODerate resolution TRANsmission), is used to generate the sky-dome environment map which includes sun and sky radiance along with the polarisation effect of the sky due to Rayleigh scattering. Moreover, we perform path tracing and implement ray interaction with medium and volumetric backscattering at rendering time to model the adjacency effect. We propose two variants of adjacency models, the first one incorporates a single spectral albedo as the averaged background of the scene, this model is called the Background One-Spectra Adjacency Effect Model (BOAEM), which is a CameoSim like model created for performance comparison. The second model calculates background albedo from a pixel’s neighbourhood, whose size depends on the air volume between sensor and target, and differential air density up to sensor altitude. Average background reflectance of all neighbourhood pixel is computed at rendering time for estimating the total upwelled scattered radiance, by volumetric scattering. This model is termed the Texture-Spectra Incorporated Adjacency Effect Model (TIAEM). Moreover, for estimating the underlying atmospheric condition MODTRAN is run with varying aerosol optical thickness and its total ground reflected radiance (TGRR) is compared with TGRR of known in-scene material. The Goodness of fit is evaluated in each iteration, and MODTRAN’s output with the best fit is selected. We perform a tri-modal validation of simulators on a real hyperspectral scene by varying atmospheric condition, terrain surface models and proposed variants of adjacency models. We compared results of our model with Lockheed Martin’s well-established scene simulator CameoSim and acquired Ground Truth (GT) by Hyspex cameras. In clear-sky conditions, both models of CHIMES and CameoSim are in close agreement, however, in searched overcast conditions CHIMES BOAEM is shown to perform better than CameoSim in terms of ℓ1 -norm error of the whole scene with respect to GT. TIAEM produces better radiance shape and covariance of background statistics with respect to Ground Truth (GT), which is key to good target detection performance. We also report that the results of CameoSim have a many-fold higher error for the same scene when the flat surface terrain is replaced with a Digital Elevation Model (DEM) based rugged one

Visual and refractive status of children with Down's syndrome and nystagmus

Background/Aims Children with Down’s syndrome (DS) are known to have poorer visual acuity that neurotypical children. One report has shown that children with DS and nystagmus also have poor acuity when compared to typical children with nystagmus. What has not been established, is the extent of any acuity deficit due to nystagmus and whether nystagmus impacts on refractive error is within a population with DS. Methods Clinical records from The Cardiff University Down’s Syndrome Vision Research Unit were examined retrospectively. Binocular visual acuity and refraction data were available for 50 children who had DS and nystagmus (DSN) and 176 children who had DS but no nystagmus. Data were compared between the two groups, and with published data for neurotypical children with nystagmus. Results The study confirms the deficit in acuity in DS, compared to neurotypical children, of approximately 0.2 LogMAR and shows a further deficit attributable to nystagmus of a further 0.2 logMAR beyond the first year of life. Children with DS and no nystagmus appear to have acuity that mirrors that of typical children with nystagmus, while children with both DS and nystagmus have a significant additional impairment. Children with DS have a wide range of refractive errors, but nystagmus increases the likelihood of myopia. Prevalence and axis direction of astigmatism, on the other hand appears unaffected by nystagmus. Conclusion Nystagmus confers an additional visual impairment on children with Down’s syndrome and must be recognised as such by families and educators. Children with both DS and nystagmus clearly need targeted support

Optimisation of silicone-based dielectric elastomer transducers by means of block copolymers – synthesis and compounding

Emerging artificial muscle technology has developed from metal-based robotics to softtype robotics made from soft matter. Research into artificial muscle technology based on soft matter has been conducted mainly in order to mimic soft and robust human muscle. In this regard, dielectric elastomers have been studied. Their actuation occurs when Maxwell stress exceeds elastic stress in the presence of an electrical field, resulting in contraction in thickness and planar expansion in the area. As well as an actuator, dielectric elastomers can be used as generators and sensors. As a dielectric elastomer, silicones have been used extensively in many applications, due to favourable properties such as thermal stability, non-conductivity, high gas permeability and low toxicity. However, silicones have a low dielectric constant and thereby low energy density. In order to enhance actuation performance, it is the aim of this research to develop silicone elastomers with a high dielectric constant and high electrical breakdown strength, as well as a low Young’s modulus. In this Ph.D. thesis, two methods were developed to enhance silicone properties such as the dielectric constant and electrical breakdown strength. The first method was devised to enhance the dielectric constant of silicone elastomers through the use of a polydimethylsiloxane-polyethyleneglycol (PDMS-PEG) copolymer, in order to obtain an elastomer with high electrical energy. PDMS-PEG copolymers were synthesised and blended in commercial silicone and subsequently cross-linked. The relative permittivity of cross-linked silicone with 5 wt% of PDMS-PEG copolymers increased by nearly 50%, without compromising dielectric loss and mechanical properties, compared to the commercial silicone elastomer. The second investigated method involved enhancing the electrical breakdown strength of silicone by using an aromatic voltage stabiliser. Here, polyphenylmethylsiloxane (PPMS), which contained aromatic voltage stabilisers, was bonded covalently to PDMS through a hydrosilylation reaction obtaining PDMS-PPMS copolymers. The synthesised copolymers were subsequently cross-linked with a vinyl cross-linker. The obtained cross-linked PDMS-PPMS copolymers were inherently soft and robust with increased electrical breakdown strength (21%) compared to the reference elastomer without an aromatic voltage stabiliser. The conducting polymer was developed through the use of a multi-walled carbon nanotube (MWCNT) in a PDMS-PEG matrix as a compliant electrode of dielectric elastomers. The conductive PDMS-PEG copolymer was incorporated with surface-treated MWCNT, in order to obtain highly conductive elastomer. The prepared sample with 4 parts per hundred rubber (phr) MWCNT was soft and the resulting conductivity of the cross-linked PDMS-PEG copolymer with the addition of MWCNT was high, at 10-2 S cm-1, nearly equivalent to a commonly used commercial conducting polymer. In this thesis, the elastomer and electrode system is referred to as a ‘dielectrielastome

Effects of modern instructional technology (MIT) on critical thinking skills of students in agriculture vocational courses in Nigeria

The recent development in modern instruction technology (MIT) methods and equipment warranted for studies to examine their effects on students, teachers, and the education system in general. This study examines the effects of MIT on students’ critical thinking skills in Agriculture vocational courses in Nigeria. The methods and equipment used were identified, and the effect of teachers’ usage behaviour was assessed. A survey approach was adopted, using questionnaires for data collection. The descriptive, correlations and multiple regressions were carried out using SPSS. The result of this study indicates that the most commonly used equipment is electronic whiteboard, while the least are electronic tablets and laptops. Cooperative learning is the most commonly used methods while games and online instruction are the least. There is a moderate positive correlation between MIT methods and the students’ critical thinking skill, but a very weak positive correlation between MIT equipment and students’ critical thinking skill. There is statistically significant contribution of methods to student’s critical thinking, but insignificant method usage behaviour. Therefore, it is concluded that government should incorporate the provision and effective utilisation of MIT equipment and methods in the national education policy. School managements should emphasise the use of MIT methods and review curriculum to improve teachers’ skills in MIT usage. Teachers should utilise the available MIT equipment and method along with their skills for an effective delivery of lessons. Similarly, the students should be encouraged to appreciate the available methods and the equipment, and use them effectively

Splitting and blaming: The psychic life of neoliberal executive women

The aim of the article is to explore the psychic life of executive women under neoliberalism using psychosocial approaches. The article shows how, despite enduring unfair treatment and access to opportunities, many executive women remain emotionally invested in upholding the neoliberal ideal that if one perseveres, one shall be successful, regardless of gender. Drawing on psychosocial approaches, we explore how the accounts given by some executive women of repudiation, as denying gender inequality, and individualization, as subjects completely agentic, are underpinned by the unconscious, intertwined processes of splitting and blaming. Women sometimes split off undesirable aspects of the workplace, which repudiates gender inequality, or blame other women, which individualizes failure and responsibility for change. We explain that splitting and blaming enable some executive women to manage the anxiety evoked from threats to the neoliberal ideal of the workplace. This article thereby makes a contribution to existing postfeminist scholarship by integrating psychosocial approaches to the study of the psychic life of neoliberal executive women, by exploring why they appear unable to engage directly with and redress instances of gender discrimination in the workplace