280 research outputs found
Geometrical-based lip-reading using template probabilistic multi-dimension dynamic time warping
By identifying lip movements and characterizing their associations with speech sounds, the performance of speech recognition systems can be improved, particularly when operating in noisy environments. In this paper, we present a geometrical-based automatic lip reading system that extracts the lip region from images using conventional techniques, but the contour itself is extracted using a novel application of a combination of border following and convex hull approaches. Classification is carried out using an enhanced dynamic time warping technique that has the ability to operate in multiple dimensions and a template probability technique that is able to compensate for differences in the way words are uttered in the training set. The performance of the new system has been assessed in recognition of the English digits 0 to 9 as available in the CUAVE database. The experimental results obtained from the new approach compared favorably with those of existing lip reading approaches, achieving a word recognition accuracy of up to 71% with the visual information being obtained from estimates of lip height, width and their ratio
Investigation of dimensionality reduction in a finger vein verification system
Popular methods of protecting access such as Personal Identification Numbers and smart cards are subject to security risks that result from accidental loss or being stolen. Risk can be reduced by adopting direct methods that identify the person and these are generally biometric methods, such as iris, face, voice and fingerprint recognition approaches. In this paper, a finger vein recognition method has been implemented in which the effect on performance has of using principal components analysis has been investigated. The data were obtained from the finger-vein database SDMULA-HMT and the images underwent contrast-limited adaptive histogram equalization and noise filtering for contrast improvement. The vein pattern was extracted using repeated line tracking and dimensionality reduction using principal components analysis to generate the feature vector. A ‘speeded-up robust features’ algorithm was used to determine the key points of interest and the Euclidean Distance was used to estimate similarity between database images. The results show that the use of a suitable number of principal components can improve the accuracy and reduce the computational overhead of the verification system
Image fusion based multi resolution and frequency partition discrete cosine transform for palm vein recognition
The rapid growth of technology has increased the demand for automated security systems. Due to the accessibility of the palm region and the unique characteristics of each individual's palm vein features, such biometrics have been receiving particular attention. In the published research relating to palm vein biometrics, usually only a single image is used to supply the data for recognition purposes. Previous experimental work has demonstrated that the fusion of multiple images is able to provide richer feature information resulting in an improved classification performance. However, although most of the image fusion techniques are able to preserve the vein pattern, the fused image is often blurred, the colors are distorted and the spatial resolution reduced. In this paper, the multi-resolution discrete cosine transform (MRDCT) and frequency partition DCT (FPDCT) image fusion are applied and are able to extract the finer details of vein patterns while reducing the presence of noise in the image. The performance shows that the use of MRDCT and FPDCT was able to improve recognition rate compared to using a single image. The equal error rate improvement is also significant, falling to 9% in 700nm image, 7% in 850nm image and 6% in 940nm image
Physical and photophysical properties of a linear copper(I) complex of a bulky acenapthene-based NHC ligand
CFRM and EZ-C wish to thank the Engineering and Physical Sciences Research Council (EP/M02105X/1 and EP/R035164/1) for financial support. We would like to thank the Engineering and Physical Sciences Research Council and CRITICAT Centre for Doctoral Training for financial support (Ph.D. studentship to B. H.; EP/L016419/1).We report the first example of a charge-neutral linear 2-coordinate copper(I) complex bearing a sterically demanding acenaphthoimidazolylidene-based N-heterocyclic carbene ligand. The identity and geometry of the complex was confirmed by single-crystal XRD (X-Ray Diffraction) analysis. The complex is poorly emissive at room temperature, showing either ligand-centered (LC) emission at around 340 nm when excited at 300 nm or ligand-to-ligand charge-transfer (LLCT) emission at around 540 nm when excited at 420 nm; in chloroform, dual emission is observed upon photoexcitation at 300 nm. Nanosecond emission lifetimes were recorded for these processes. This is the first example of emissive linear copper(I) complexes containing this bulky NHC ligand.PostprintPeer reviewe
An Integrated Approach to Understand Relationships Between Shallow Water Benthic Community Structure and Ecosystem Function SERDP Project SI-1335
Human activities along our nation\u27s coasts often lead to habitat modification, pollution, and overexploitation of living resources in coastal and estuarine waters (U.S. Commission on Ocean Policy 2004). Coastal areas are the most developed regions of the United States. In addition to recreational and leisure activities, these areas support commercial fishing, aquaculture, shipping, and defense activities. Numerous human activities can have detrimental effects on biodiversity and the provision of ecosystem services that support and sustain human populations. Given their proximity to the land and human population centers, nearshore estuarine ecosystems are especially vulnerable. Effective management can be improved with a better understanding of relationships between ecological integrity and human pressures in these ecosystems (National Estuary Program 2007). Ecologists, coastal managers, and policy-makers are working together to develop better ways to measure and manage human effects on estuarine and coastal ecosystems. Management strategies can be framed in the context of human actions (pressure or stressor), resulting effects on community structure and ecosystem functions (state or condition), and management response
Silicon redistribution, acid site loss and the formation of a core-shell texture upon steaming SAPO-34 and their impact on catalytic performance in the methanol-to-olefins (MTO) reaction
IBM has received funding from the Engineering and Physical Sciences Research Council (EPSRC, Centre for Doctoral Training in Critical Resource Catalysis, EP/I017008/1) and Scotland's Chemistry departments (ScotCHEM). IBM also received a scholarship from the SCI and Santander. Johnson Matthey is thanked for in-kind contributions and hosting IBM in their R&D labs. ABN gratefully acknowledges support from the EPSRC (grants EP/L017008/1 and EP/R023751/1). The research data supporting this publication can be accessed at: https://doi.org/10.17630/09ddc03e-f121-4e79-9b55-674f64d9c8c4 [62].SAPO-34 is a commercially-implemented silicoaluminophosphate catalyst for selective high yield production of ethene and propene from methanol, but high temperature regeneration in the presence of steam leads to its deactivation. A comprehensive investigation of the effect of prolonged hydrothermal treatment on the structure and properties of SAPO 34 explains the changes in its catalytic methanol-to-olefins (MTO) performance. Microcrystalline powdered SAPO-34 (ca. 3 µm crystals, Al17.1P15.6Si3.3O72) and two batches of larger single crystals of SAPO-34 of different Si concentration (20-100 µm; Al17.3P14.7Si4.0O72 and Al17.7P12.3Si5.9O72 ) were steamed (pH2O = 0.95 atm) at 873–1023 K for up to 240 h. The acidity (NH3-TPD), crystallinity (PXRD), framework cation environment (solid-state 27Al, 29Si and 31P MAS NMR) and porosity were followed for all materials; larger crystals were amenable to single crystal X-ray diffraction, FIB-SEM and synchrotron IR microspectroscopy, including operando study during methanol and dimethyl ether conversions. Some level of steaming improved the lifetime of all SAPO-34 materials in MTO catalysis without affecting their olefin selectivity, although more severe conditions led to the formation of core-shell structures, microporosity loss and eventually at 1023 K, recrystallization to a dense phase. All these irreversible changes occurred faster in crystals with higher Si contents. The initial increase in catalytic lifetime results from an activated reduction in acid site density (Eact = 146(18) kJ mol⁻1), a result of redistribution of Si within the SAPO framework without porosity loss. Operando IR with online product analysis during methanol conversion suggests similar reaction pathways in calcined and steamed crystals, but with greatly reduced methoxy group densities in the latter. The gradual development of optically dark crystal cores upon progressive steaming was shown by FIB-SEM to be due to the formation of regions with meso- and macropores, and these were shown by IR mapping to possess low hydroxyl densities.PostprintPostprintPeer reviewe
Analysis of two [2]catenanes based on electron densities from invariom refinement and results from DFT calculations
The authors are grateful to the Deutsche Forschungsgemeinschaft (DFG) for financial support by project DI 921/6-1.Catenanes are of considerable interest as potential building blocks for molecular machines. The simplest [2]catenanes, Hopf links, consist of two macrocycles that are mechanically interlocked. This unusual architecture cannot be opened without breaking at least one covalent bond. Based on these structural characteristics, unusual properties on Hirshfeld or electrostatic potential surfaces could be expected. For a comparison of their structural and electronic properties, the electron densities (EDs) of two [2]catenanes, coded H22 and H4L7 in the original papers, were examined after application of the invariom formalism, relying on X-ray diffraction data collected earlier. The obtained electron density distributions were subjected to an analysis using the QTAIM formalism to yield bond and atomic properties. Moreover, molecular Hirshfeld surfaces and electrostatic potentials (ESP) were calculated. There are different types of intra- and intermolecular interactions in these two [2]catenanes. In addition to classical N-H···N and C-H···O hydrogen bonds, various types of π···π interactions in H22 and in H4L7 exist. Most of them are verified by local ED concentrations visible on the corresponding Hirshfeld surfaces, except for the parallel π···π interactions in H22, which are either too weak or too diffuse to generate an ED signal on the Hirshfeld surface between the contributing aromatic rings. The electrostatic potentials (ESPs) were calculated and displayed on molecular surfaces. The interaction in the cavity of one macrocycle with the penetrated fragment of the second one was examined and it was found that corresponding to the above-mentioned contacts attractive and repulsive interactions exist. Additionally the ED was examined using results of density functional calculations, including non-covalent interaction index (NCI) and electron localizability indicator (ELI-D) surface analysis, complementing experimental findings.Publisher PDFPeer reviewe
Modulator-Controlled Synthesis of Microporous STA-26, an Interpenetrated 8,3-Connected Zirconium MOF with the the-i Topology, and its Reversible Lattice Shift
A fully interpenetrated 8,3-connected zirconium MOF with the the-i topology type, STA-26 (St Andrews porous material-26), has been prepared using the 4,4′,4“-(2,4,6-trimethylbenzene-1,3,5-triyl)tribenzoate (TMTB) tritopic linker with formic acid as a modulating agent. In the as-prepared form STA-26 possesses Im (Formula presented.) m symmetry compared with the Pm (Formula presented.) m symmetry of the non-interpenetrated analogue, NU-1200, prepared using benzoic acid as a modulator. Upon removal of residual solvent there is a shift between the interpenetrating lattices and a resultant symmetry change to Cmcm which is fully reversible. This is observed by X-ray diffraction and 13C MAS NMR is also found to be remarkably sensitive to the structural transition. Furthermore, heating STA-26(Zr) in vacuum dehydroxylates the Zr 6 nodes leaving coordinatively unsaturated Zr 4+ sites, as shown by IR spectroscopy using CO and CD 3CN as probe molecules. Nitrogen adsorption at 77 K together with grand canonical Monte Carlo simulations confirms a microporous, fully interpenetrated, structure with pore volume 0.53 cm 3 g −1 while CO 2 adsorption at 196 K reaches 300 cm 3 STP g −1 at 1 bar. While the pore volume is smaller than that of its non-interpenetrated mesoporous analogue, interpenetration makes the structure more stable to moisture adsorption and introduces shape selectivity in adsorption. </p
Multi-dimensional optimization of In0.53Ga0.47As thermophotovoltaic cell using real coded genetic algorithm
The optimization of thermophotovoltaic (TPV) cell efficiency is essential since it leads to a significant increase in the output power. Typically, the optimization of In0.53Ga0.47As TPV cell has been limited to single variable such as the emitter thickness, while the effects of the variation in other design variables are assumed to be negligible. The reported efficiencies of In0.53Ga0.47As TPV cell mostly remain < 15%. Therefore, this work develops a multi-variable or multi-dimensional optimization of In0.53Ga0.47As TPV cell using the real coded genetic algorithm (RCGA) at various radiation temperatures. RCGA was developed using Visual Basic and it was hybridized with Silvaco TCAD for the electrical characteristics simulation. Under radiation temperatures from 800 to 2000 K, the optimized In0.53Ga0.47As TPV cell efficiency increases by an average percentage of 11.86% (from 8.5 to 20.35%) as compared to the non-optimized structure. It was found that the incorporation of a thicker base layer with the back-barrier layers enhances the separation of charge carriers and increases the collection of photo-generated carriers near the band-edge, producing an optimum output power of 0.55 W/cm2 (cell efficiency of 22.06%, without antireflection coating) at 1400 K radiation spectrum. The results of this work demonstrate the great potential to generate electricity sustainably from industrial waste heat and the multi-dimensional optimization methodology can be adopted to optimize semiconductor devices, such as solar cell, TPV cell and photodetectors
Artificial limb representation in amputees
The human brain contains multiple hand-selective areas, in both the sensorimotor and visual systems. Could our brain repurpose neural resources, originally developed for supporting hand function, to represent and control artificial limbs? We studied individuals with congenital or acquired hand-loss (hereafter one-handers) using functional MRI. We show that the more one-handers use an artificial limb (prosthesis) in their everyday life, the stronger visual hand-selective areas in the lateral occipitotemporal cortex respond to prosthesis images. This was found even when one-handers were presented with images of active prostheses that share the functionality of the hand but not necessarily its visual features (e.g. a \u27hook\u27 prosthesis). Further, we show that daily prosthesis usage determines large-scale inter-network communication across hand-selective areas. This was demonstrated by increased resting state functional connectivity between visual and sensorimotor hand-selective areas, proportional to the intensiveness of everyday prosthesis usage. Further analysis revealed a 3-fold coupling between prosthesis activity, visuomotor connectivity and usage, suggesting a possible role for the motor system in shaping use-dependent representation in visual hand-selective areas, and/or vice versa. Moreover, able-bodied control participants who routinely observe prosthesis usage (albeit less intensively than the prosthesis users) showed significantly weaker associations between degree of prosthesis observation and visual cortex activity or connectivity. Together, our findings suggest that altered daily motor behaviour facilitates prosthesis-related visual processing and shapes communication across hand-selective areas. This neurophysiological substrate for prosthesis embodiment may inspire rehabilitation approaches to improve usage of existing substitutionary devices and aid implementation of future assistive and augmentative technologies
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