Development and validation of a deep learning-based algorithm for drowsiness detection in facial photographs

Multimedia Tools and Applications - Drowsiness is a feeling of sleepiness before the sleep onset and has severe implications from a safety perspective for the individuals involved in industrial...     

Properties of Compliant Substrates Based on Porous Silicon Formed by Two-stage Etching

Semiconductors - Abstract—Our work reports on the influence of etching modes and their combination on the design, microstructural and optical properties of compliant substrates based on...     

M.A.L.D.I.-T.O.F. mass spectrometry characterization of 4-alkyl substituted phenol-formaldehyde novalac type resins

Two methods of synthesis for 4-alkyl substituted phenol-formaldehyde resins are described. A common method for synthesis of novolac type phenol-formaldehyde resin uses sulfuric acid catalyst in the presence of xylene for azeotropic removal of water of reaction. By the use of M.A.L.D.I.-T.O.F. mass spectrometry we have demonstrated that m-xylene is incorporated into these polymers. Polymers free of impurities are best prepared using a cation exchange resin as catalyst in the presence of a less reactive solvent, e.g. chlorobenzene, or in the absence of solvents. © 1997 Elsevier Science Ltd.     

Sequential Template Decomposition to Adjust the Performance of Imperfect Zeolite BEA Membranes

Zeolite membranes offer superior thermal, chemical, and mechanical stability compared to polymeric membranes. However, it is still a challenge to prepare completely defect‐free membranes without any intercrystalline voids, which is necessary for gas separation processes. In this study zeolite beta (*BEA) membranes on stainless‐steel supports were prepared by applying the multiple in situ crystallization technique. The membranes were used as a model system to systematically study the decomposition of the organic structure directing agent tetraethylammoniumhydroxide (TEA‐OH). It was evaluated if the organic decomposition products of TEA‐OH can be used for enhancing the membranes selectivity. Post‐treatment experiments have been carried out to adjust surface properties and pore size dimensions in the zeolitic membrane layer. The results show that membranes calcined at lower temperatures exhibit a higher gas selectivity.     

Adsorption characteristics of toxic chromium(VI) from aqueous media onto nanosized silver nanoparticles-treated activated carbon

The present study reports the use of nanomaterial, e.g. Ag nanoparticles (AgNPs), immobilized activated carbon as an effective solid adsorbent for removal of toxic chromium(VI) from water. Chromium(VI) uptake was found favorable in acidic media at pH ≤ 3. Based on Langmuir model, monolayer adsorption capacities of chromium(VI) found equal 93.5 mg/g. The results fitted well with pseudo second-order and Langmuir models. The mechanism of adsorption was explored using the intra-particle diffusion model and the liquid-film model. Chromatographic separation of chromium(VI) was achieved. The AC-AgNPs was successfully recycled for five successive adsorption–desorption cycles indicating its high reusability.     

A variable range bi-phasic current stimulus driver circuitry for an implantable retinal prosthetic device

This paper reports a driver circuitry to generate bi-phasic (anodic and cathodic) current pulses for stimulating the retinal layer through electrodes which is part of a retinal prosthetic device for implants in blind patients affected by retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Dual voltage architecture is used to halve the number of interface leads from the chip to the stimulation sites compared to a single voltage supply. The driver circuitry is designed to deliver currents with six bit resolution for a wide range of full scale currents up to 600 /spl mu/A. To cater to the varying stimulus requirements among patients and different regions of the retina, variable gain architecture is used to achieve fine resolution even for a narrow range of stimulus. 1:8 demultiplexing feature is embedded within the output stage thus allowing one DAC for eight outputs. A novel charge cancellation circuitry with current limiting capability is implemented to discharge the electrodes for medical safety. Measurement results of a prototype chip fabricated in 1.5-/spl mu/m CMOS technology are presented.     

Architecture tradeoffs in high-density microstimulators for retinal prosthesis

Electrical stimulation of the retinal layer inside the eye has been identified as a form of visual prosthesis to restore lost vision in blind patients affected by retinitis pigmentosa and age-related macular degeneration, through several studies and experiments. While initial clinical experiments using retinal prosthesis have resulted in visual perception in humans, psychophysical tests and simulations suggest that a high-density retinal prosthesis is required to restore vision to a level of reading and mobility. In the implanted prosthetic device, the microstimulator is functionally the closest to the tissue, delivering the electrical stimulation. Choosing the suitable architecture of the microstimulator requires the knowledge of the available choices and the tradeoffs associated with each of them. This paper presents the different architectures of microstimulator for high-density retinal prosthesis considering both the biomedical and circuit perspectives. The choices for the key aspects of the microstimulator-location of the chip in the eye, electrode configuration, method of stimulation, demultiplexing, stimulation sequence, and communication protocol-are discussed along with the associated tradeoffs for each of them. One of the architectures is used in a prototype microstimulator for an implantable epi-retinal prosthetic device to be used in clinical trials. The chip consists of 60 independently programmable output drivers for delivering electrical stimulus and digital controller for managing run-time and configuration data. The circuit details of the chip fabricated in 1.2-/spl mu/m CMOS technology and its measurement results are presented.     

A computational model of electrical stimulation of the retinal ganglion cell

Localized retinal electrical stimulation in blind volunteers results in discrete round visual percepts corresponding to the location of the stimulating electrode. The success of such an approach to provide useful vision depends on elucidating the neuronal target of surface electrical stimulation. To determine if electrodes preferentially stimulate ganglion cells directly below them or passing fibers from distant ganglion cells, we developed a compartmental model for electric field stimulation of the retinal ganglion cell (RGC). In this model a RGC is stimulated by extracellular electrical fields with active channels and realistic cell morphology derived directly from a neuronal tracing. Three membrane models were applied: a linear passive model, a Hodgkin-Huxley model with passive dendrites (HH), and a model composed of all active compartments (FCM) with five nonlinear ion channels. Idealized monopolar point and disk stimulating electrodes were positioned above the cell. For the HH and FCM models, the position of lowest cathodal threshold to propagate an action potential was over the soma. Brief (100 microseconds) cathodic stimuli were 20% (HH with disk electrode) to 73% (FCM with point-source) more effective over the soma than over the axon. In the passive model, the axon is preferentially stimulated versus the soma. Although it may be possible to electrically stimulate RGC's near their cell body at lower thresholds than at their axon, these differences are relatively small. Alternative explanations should be sought to explain the focal perceptions observed in previously reported patient trials.     

Influence of substrate temperature and solution molarity on CuO thin films' properties prepared by spray pyrolysis

Journal of Materials Science: Materials in Electronics - In the present work, we have investigated the influence of substrate temperature and solution concentration on copper oxide (CuO) thin film...     

A Compact Rhombus Shaped Antenna with Extended Stubs for Ultra-Wideband Applications

Ultra-wideband (UWB) is highly preferred for short distance communication. As a result of this significance, this project targets the design of a compact UWB antennas. This paper describes a printed UWB rhombus-shaped antenna with a partial ground plane. To achieve wideband response, two stubs and a notch are incorporated at both sides of the rhombus design and ground plane respectively. To excite the antenna, a simple microstrip feed line is employed. The suggested antenna is built on a 1.6 mm thick FR4 substrate. The proposed design is very compact with overall electrical size of 0.18λ × 0.25λ (14 × 18 mm²). The rhombus shaped antenna covers frequency ranging from 3.5 to 11 GHz with 7.5 GHz impedance bandwidth. The proposed design simulated and measured bandwidths are 83.33% and 80%, respectively. Radiation pattern in terms of E-field and H-field are discussed at 4, 5.5 and 10 GHz respectively. The proposed design has 65% radiation efficiency and 1.5 dBi peak gain. The proposed design is simulated in CST (Computer Simulation Technology) simulator and the simulated design is fabricated for the measured results. The simulated and measured findings are in close resemblance. The obtained results confirm the application of the proposed design for the ultra-wide band applications.