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This article reports the successful results from the recently developed non-invasive photonic system AUM - for real time, discrimination and quantification of different pathogenic bacterial strains, and mixtures of bacterial species in air. The uniqueness and novelty of the AUM photonic system, lies in its ability to innovatively apply the concepts of elastic light scattering, statistical mechanics, artificial intelligence, and machine learning to identify, classify and quantify various microbes present in the scattering volume in real time; and therefore, can become a potential tool in the control and management of diseases caused by pathogenic microbes.

The poor state of air quality all over the world in general, and across India in particular, is a cause for extreme concern as it is directly and indirectly linked to the deterioration of human health and economies of nations The many complexities and challenges posed by ambient air quality monitoring, prompted the World Health Organization (WHO) to suggest a road map for all nations for the year 2020 -to arrive at a consensus for effective air quality monitoring by all stakeholders –nations and governments, regulatory and controlling bodies, NGOs, scientists and researchers and private citizens.

This article discusses metal–organic vapor phase epitaxy growth of all-phosphide (AlInP–InGaP) distributed Bragg reflectors (DBRs) and their applications for thin flexible multijunction solar cell devices. DBRs with a peak reflectance of 884 nm—close to the GaAs bandgap energy—were grown. This all-phosphide DBR was monolithically integrated with a dual-junction (DJ) InGaP/GaAs solar cell. The DJ cell with a DBR exhibited a 3% increase in short-circuit current density ( J sc), in comparison with the DJ without a DBR. Both open-circuit voltage ( V oc) and fill factor ( FF) values of the solar cell did not change with the DBR integration.

Building on previous simulation results, this work examines experimentally the incorporation of a longpass (LP) distributed Bragg reflector (DBR), as compared to a standard matched pair DBR, between the GaAs and InGaAs subcells of a triple junction inverted metamorphic design. The GaAs cell was not optically thick, to improve radiation tolerance, and contained InGaAs quantum wells, to increase subcell current generation. Both DBR structures improved bulk GaAs subcell collection in the physically thin absorber, however the LPDBR significantly reduced optical loss in the bottom junction caused by parasitic low energy reflections present in the standard DBR. This shifted the current limiting junction from the bottom InGaAs junction in the case of the DBR to the top InGaP junction, as designed. Simulation and experimental results of external quantum efficiency are presented and discussed.

This work studies the integration of textured back surface reflectors (BSR) in 600 nm-thick InGaAs solar cells to improve radiation tolerance and maintain efficiency in inverted metamorphic (IMM) solar cells. Current enhancement is demonstrated in the InGaAs solar cells with textured BSRs compared to a similar device with an absorbing BSR. The textured BSRs consist of wet-chemical maskless etching and in situ texturing during epitaxial growth. The textured layers achieve higher surface roughness than the pre-textured surface, indicating extended photon scattering. The device characterization emphasizes the impact of free-carrier absorption in the backside textured layers, mainly evident within the Al 0.25 Ga 0.75 As maskless BSR solar cell, which has a high p-type doping concentration. All devices had similar fill factor and V OC near 74% and 0.57 V, respectively, indicating no negative influence on electrical performance from the texture development. Reducing parasitic absorption in the AlGaAs textured layer and back mirror will enhance the current collection and render a platform for thin-film bottom InGaAs subcells with textured BSR to successfully improve radiation tolerance and sustain IMM device performance.

Loss in output power in multi-junction space photovoltaics occurs due to reduction in minority carrier diffusion length caused by on-orbit radiation damage of the crystal. One method to improve the radiation resistance of a multi-junction device is through thickness reduction of the various layers, increasing carrier collection at reduced diffusion length. However, this reduction in thickness can also result in current loss unless some type of mirror is used to increase the optical path length (OPL). In this talk, we will explore two options for increasing the OPL in the middle and bottom junction of a standard InGaP2/GaAs/In0.3Ga0.7As inverted metamorphic (IMM) solar cell using a chirped distributed Bragg reflector (DBR) between the GaAs and InGaAs cell and using a maskless texture at the back side of the InGaAs cell. The fabrication of these structures will be reviewed as well as device and radiation improvements afforded by application of the photonic structures.

We report on integration of wavelength selective photonic structures (WSPS) such as distributed bragg reflectors (DBR) and multi quantum well structures to InGaP-GaAs dual junction (DJ) and GaAs single junction (SJ) solar cells. Epitaxial lift Off (ELO) process compatible InAlP-InGaP DBR structures and strain balanced GaAsP-InGaAs MQW developed. Subcell voltages for DJ cells were extracted from EL measurements. EQE data for GaAs sub cells was modeled and compared with experimental data. 1MeV Electron radiation studies performed to evaluate the radiation hardness of these ELO DJ cells with integrated DBR exhibited 12% improvement in remaining factor P/P 0 values (EoL performance for 1E15 electron irradiation) when compared with baseline DJ cell with no DBR.

Reducing the thickness of the GaAs absorber in a multijunction solar cell can increase radiation tolerance, while incorporation of a distributed Bragg reflector (DBR) can maintain current density by maintaining optical path length. In a closely current matched multijunction design, low energy sidelobe reflections of the DBR parasitically affect the subcell below the GaAs junction. A variation of the DBR design is proposed to mitigate this loss mechanism by maximizing transmission below the main Bragg peak. Through simulated multijunction and experimental verification of test structures, this paper will show how this “longpass” DBR can be optimized to improve current matching while maintaining radiation hardening afforded by thinning the GaAs junction.

In this work, textured back surface reflectors (BSR) produced by inverse progression metal-assisted chemical etching (I-MacEtch) is used to render wavelength-specific (WS) light trapping structures for thin GaAs solar cells. The HAZE reflectance measured on the MacEtch BSR shows 80% HAZE in the GaAs absorbing region indicative of high diffused photon scattering. The MacEtch BSR was implemented in a 500 nm thick GaAs solar cell, and the external quantum efficiency shows a 17% enhancement in the photogenerated carrier collection from the base of the solar cell when compared to the flat BSR device. The Fabry-Perot EQE fringes show a photon lifetime enhancement factor of 5.7 in the MacEtch BSR device, especially evident near the GaAs band edge. The recovered photoabsorption provides evidence that the WS BSR can be implemented into a dual-junction InGaP/GaAs solar cell to provide high current output in a radiation-tolerant thinned GaAs subcell.

We report the first demonstration of MOVPE-grown inverted metamorphic (IMM) cells with QDs embedded in the middle GaAs sub-cell. The IMM cells were fabricated on full 4″ wafer using Epitaxial Lift off (ELO) technology. GaAs sub-cell embedded with 10 and 20 periods of InAs/GaP strain compensated QDs showed increase in current with number of QD periods. The single junction GaAs sub cell embedded with 20 periods of InAs/GaP strain compensated QDs showed 3.2% relative increase in JSC in comparison with control sample without QDs. Integrated short circuit (JSC) from measurements of external quantum efficiency (EQE) of currents showed a 65% increase in sub-band collection in the GaAs sub-cell when the number of QD layers increased from 10 to 20. IMM cells with QD's embedded in the middle cell showed minimal loss in open circuit voltage (VOC) in comparison to control sample without QDs. An efficiency of 30% under 1-sun AM0 spectrum was obtained for IMM cells with 10 xs of InAs/GaP QDs in GaAs sub-cell. Quantum efficiency remaining factor of > 95% in the QD absorption region (940 nm) was measured for IMM devices with InAs/GaAs QD enhanced GaAs sub-cells irradiated with 1 MeV electrons under 2E15 /cm2 fluence.

Introduction: Cerebral palsy is a neuro developmental condition with various antenatal, intranatal and post natal factors associated with it. Cerebral palsy is multi factorial in its aetiology. Aim: To study postnatal factors associated with Cerebral palsy. Materials & Methods: This is a retrospective study collecting birth history data from the mothers of 160 cerebral palsy and 160 normal children to identify the most common post natal factors associated with cerebral palsy. Results: Statistical analysis of the data collected from birth history of 160 cerebral palsy and 160 normal children showed history of jaundice was present in 26 and 1 child in cerebral palsy and normal children respectively, with estimated odds ratio of 30.8507 with lower and upper 95 % confidence interval ranging from 4.1315 - 230.3683. History of meconium aspiration was present in 32 and 2 cases of Cerebral palsy and normal children respectively with estimated odds ratio of 19.75 with 95% confidence interval ranging from 4.6445 – 83.984. History of seizures was present in 48 and 2 cases of Cerebral palsy and normal children respectively, with estimated odds ratio of 33.8571, with 95% confidence interval ranging from 8.0613 – 142.199 was present. Conclusion: Health education to the mothers, regular health check up by a gynaecologist at primary health care level to identify at risk pregnant woman and improving the resuscitation infrastructure facilities for the new born and effective referral services are very essential to prevent/treat some of the underlying causes/factors responsible for the meconium aspiration, jaundice and seizures in the new born which if neglected are important factors for morbidity and mortality of the new born and for long term neuro-developmental problems of the children.

Air is the most essential constituent for the sustenance of life on earth. The air we inhale has a tremendous impact on our health and well-being. Hence, it is always advisable to monitor the quality of air in our environment. To forecast the air quality index (AQI), artificial neural networks (ANNs) trained with conjugate gradient descent (CGD), such as multilayer perceptron (MLP), cascade forward neural network, Elman neural network, radial basis function (RBF) neural network, and nonlinear autoregressive model with exogenous input (NARX) along with regression models such as multiple linear regression (MLR) consisting of batch gradient descent (BGD), stochastic gradient descent (SGD), mini-BGD (MBGD) and CGD algorithms, and support vector regression (SVR), are implemented. In these models, the AQI is the dependent variable and the concentrations of NO2, CO, O3, PM2.5, SO2, and PM10 for the years 2010–2016 in Houston and Los Angeles are the independent variables. For the final forecast, several ensemble models of individual neural network predictors and individual regression predictors are presented. This proposed approach performs with the highest efficiency in terms of forecasting air quality index.

Introduction: Cerebral palsy affects 2 – 3 per 1000 live children. It is a group of movement and postural disorders due to non progressive lesion in the immature brain. There are several proposed antenatal, intra natal, and post natal risk factors associated with cerebral palsy. Males are more commonly affected than females for reasons not clearly known. Aim: The aim of this study is to analyse comparative incidence of cerebral palsy in male and female sex and also to analyse comparative incidence of cerebral palsy in preterm births in male and female babies. Materials & Methods: The present study was a retrospective cohort study. Data was collected from the parents of 200 cerebral palsy affected children during the perod 20012 – 2018 in the Rani Chandra Mani Devi Hospital, Visakhapatnam, Andhra Pradesh. The data was analysed regarding the sex distribution among the total children having cerebral palsy and also among the preterm birth children having cerebral palsy. Results: Of the 200 children affected with cerebral palsy 125 were males and 75 were females accounting to 62.24% of males and 37.75% of females. Of the 125 males, 32 were born preterm and among the 75 females, 22 were born preterm. Of the total 54 preterm births with cerebral palsy the percentage contribution of male to female is 59.25% and 40.74% respectively.Conclusion: This study reflects the male preponderance among the cerebral palsy affected children and also reflects the male preponderance among the preterm babies having cerebral palsy. However as this study involves a small group, study involving higher number of cerebral palsy children is needed, before coming to any final conclusions.

Radiation tolerance of a triple junction solar cell can be improved by thinning the GaAs middle junction and maintaining power conversion efficiency through the use of a distributed Bragg reflector. Simulations using Sentaurus RSoft show that current density lost through reduction of the GaAs base thickness can be recovered by increasing the optical path length through the device using photonic structures such as a distributed Bragg reflector (DBR). In this paper, the simulation is further compared to experiment focusing on the GaAs middle cell, where prior to growing the diode a conductive DBR is grown epitaxially using MOCVD. Internal and external quantum efficiency, as well as performance under 1-sun illumination, is presented showing nearly complete recovery of performance to opticallythick conditions, while using half the thickness of GaAs absorber. These devices were then exposed to 1 MeV electrons with total doses of 2×1014, 5×1014, and 1×1015 cm−2. Post-radiation experimental results show improved J SC remaining factor, and absolute J SC , for the optically thin device incorporating a DBR. This allows an improvement of 0.36 mA/cm2 at a fluence of 1×1015 cm−2 over the optically thick control. This result was incorporated into a Ge-based triple junction simulation and predicts a 0.24% absolute efficiency improvement at 1×1015 cm−2 1 MeV e− fluence.

The authors report on the metal-organic vapor phase epitaxial (MOVPE) growth of all III-phosphide (AlInPInGaP) Distributed Bragg Reflectors (DBRs) on large GaAs substrates and their application for multijunction (MJ) solar cell device. DBRs with peak reflectance of 890 nm at GaAs bandgap energy were grown on top of inverted GaAs single junctions. All phosphide DBRs are compatible with epitaxial lift off processing of solar cells. The DBRs grown on 150 mm (6") substrates exhibited smooth surfaces and high degree of homogeneity. In the preliminary integration tests, the dual junction InGaP/GaAs solar cells with AlInP-GaInP DBR resulted in an increase of 3% in J sc and 44% increase in the integrated EL intensity of both GaAs and InGaP peaks when testing under high injection currents. The V oc and FF did not change with the DBR integration into the 2J cells.

In this work, we performed epitaxial lift-off (ELO) for lattice-matched GaInP/GaAs/GaInNAsSb triple junction (3J) solar cells which were grown inverted from top to bottom by using a hybrid growth of metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE). The fabrication of ELO-thin film 3J cells is successfully demonstrated. Then, we focus on the device structure such as thicknesses of the base layers for each subcell to change the amount of light absorption with regard to the key issue of current matching.

Nanostructured quantum well and quantum dot solar cells are being widely investigated as a means of extending infrared absorption and enhancing photovoltaic device performance. In this work, we describe the impact of nanostructured layer number on the performance of flexible, high-voltage InGaAs/GaAs quantum well solar cells. Multiple quantum well structures are observed to have a higher short circuit current but a lower open circuit voltage than similar single quantum well structures. Analysis of the underlying dark diode characteristics indicate that these high-voltage structures are limited by radiative recombination at high bias levels. The results of this study suggest that future development efforts should focus on maximizing the current generating capability of a limited number of nanostructured layers and minimizing recombination within the nanostructured absorber.

We demonstrate the integration of subwavelength moth-eye antireflection nanostructures onto a fully packaged commercial eight cell array of dual junction epitaxial lift-off GaAs solar cells. A low cost, scalable, and large area nanosphere lithography patterning process was used to fabricate the nanostructures on a polymer PET packaging layer. The mechanically flexible array shows 29.80% PCE at normal incidence and enhanced J sc at large angles of incidence due to the anti-reflection nanostructures.

A method of improving the radiation tolerance of a triple junction solar cell, lattice matched to germanium, by thinning the GaAs middle junction and maintaining power conversion efficiency through the use of a distributed Bragg reflector and patterned dielectric diffraction grating is discussed. Simulations using Sentaurus RSoft show that current density lost through reduction of the GaAs base thickness can be recovered by increasing the optical path length through the device using photonic structures such as a distributed Bragg reflector (DBR) and patterned dielectric gratings. In this paper, the simulation is further compared to experiment focusing on the GaAs middle cell, where prior to growing the diode a conductive DBR is grown epitaxially using MOCVD. Internal and external quantum efficiency, as well as performance under 1-sun illumination, is presented showing nearly complete recovery of performance to optically-thick conditions, while using half the thickness of GaAs absorber.

Inhaling particulate matter such as PM2.5 can have a hazardous impact on the human health. In order to predict the PM2.5 concentration, Artificial Neural Networks trained with conjugate gradient descent such as Multi Layer Perceptron (MLP), cascade forward neural network, Elman neural network, Radial Basis Function (RBF) neural network and Non-linear Autoregressive model with exogenous input (NARX) along with regression models such as Multiple Linear Regression (MLR) consisting of batch gradient descent, stochastic gradient descent, mini-batch gradient descent and conjugate gradient descent algorithms and Support Vector Regression (SVR) were implemented. In these models, the concentration of PM2.5 was the dependent variable and the data related to concentrations of PM2.5, SO2, O3 and meteorological data including average Maximum Temperature (MAX T), daily wind speed (WS) for the years 2010–2016 in Houston and New York were the independent variables. For the final forecast, several ensemble models of individual neural network predictors and individual regression predictors have been presented.

We demonstrate the integration of subwavelength moth-eye and Al2O3 nanoisland structures fabricated on polymer packaging sheets and the surface of conventional Al2O3/TiO2 bilayer antireflection coatings, respectively, with epitaxial lift-off single-junction GaAs solar cells. The mechanically flexible cell structure with the integrated optical nanostructures shows substantially improved photovoltaic performance under various incident angles and bending radii compared to devices without such structures: the increase in short-circuit current density arising from integration of these nanostructures ranges from 9% at normal incidence to 52% at 80° incidence; and the reduction in short-circuit current density under moderate bending decreases from 9.7% to 6.7%.

INTRODUCTION: Though spinal block has several advantages like sensory block, muscle relaxation, awake patient, the most common and serious problem with spinal anaesthesia for caesarian section remains rapid profound hypotension due to sympathetic blockade. Preloading i s an established method to prevent hypotension due to spinal anaesthesia . AIM: This study is an attempt to compare the usefulness of hetastarch (colloid) with ringer lactate solution (crystalloid) for volume preloading in the prevention of spinal hypotensi on in caesarian sections . MATERIALS AND METHODS: Informed consent was taken from a total of 120 parturients of ASA grade I, I E without maternal or fetal complications scheduled for elective or emergency for primary or repeat caesarian section at term, for this study in King George Hospital, Visakhapatnam. The study subjects were allocated into 3 groups of 40 each. Group A (40 par turients) - without preloading, Group B (40 parturients) - Crystalloid group - received preload infusion of Ringer lactate solution, 1000 ml, Group C (40 parturients) - Colloid group - received preload infusion of 6% Hydroxy Ethyl starch, 500 ml . CONCLUSIO N: From this study we conclude that 6% hydroxyethyl starch is better choice for prevention of hypotension following spinal anaesthesia in caesarian section in comparison to lactated ringer solution.

MicroLink Devices has developed an epitaxial liftoff (ELO) technology for removing thin device layers from the surface of a semiconductor wafer using a flexible metallic sheet to provide structural support. The wafer is left intact and available for use in a subsequent growth cycle. This technology has been applied to high-efficiency, multi-junction solar cells. Removal of the substrate allows the devices to achieve very high specific power of approximately 1000W/kg. For large area devices, the cost of the substrate can be a significant component of the overall device manufacturing cost. By utilizing ELO technology to reuse the substrate for multiple growth cycles, the manufacturing cost of the device can be dramatically reduced. A flexible solar cell fabricated using ELO is shown in Figure 1. Lightweight, flexible, high-efficiency solar cells have a broad range of applications in both space and terrestrial markets. MicroLink has demonstrated the use of these devices to extend the flight time of electric unmanned aerial vehicles (UAVs). The lightweight and flexible solar cells can be embedded in the wings of the vehicle, adding only minimal weight and conforming to the flight surfaces to avoid introducing addition drag. Figure 2 contains an image of a Raven UAV with MicroLink’s lightweight flexible solar cells integrated into the surface of the wings. The solar array contributes an additional 40W of power to the aircraft under typical operating conditions leading to a 62% increase in flight time. MicroLink has also demonstrated a Mobile Solar Power (MSP) panel designed for use by soldiers in the field which is capable of recharging a standard issue BB-2590 battery. This panel is shown in Figure 3 lying on top of a conventional CIGS panel. MicroLink’s MSP panel dramatically reduces the size of the panel, allowing it to be used on-the-go. This panel has demonstrated a specific power of 117W/kg, more than double the specific power of CIGS based panels (typically 43W/kg). By reducing the weight and cost of high-efficiency photovoltaic devices, MicroLink’s novel approach to device fabrication allows for a wide array of previously impractical applications of solar power. Figure 1

Quantum dot (QD) solar cells with light management allow for increased QD absorption without the need for excessive strain balancing. Single-junction GaAs cells with 10 QD layers are fabricated with back surface reflectors (BSRs) and removed from the substrate by epitaxial lift off. Devices with different BSRs will be compared: a flat mirror, a periodic texture that varies in one dimension, a periodic texture that varies in two dimensions, and a random texture achieved by crystallographic etch. Initial results show a 40% increase in sub-band current when comparing devices with a 1-D texture to the flat mirror. The final paper will present development and device results from the other two BSR types.

InAs/GaAs quantum dots (QDs) have been investigated as a potential method of engineering the bandgap of the middle junction in triple junction solar cells to better match current generation and radiation tolerance to that of the InGaP top cell. While it is possible to successfully include QDs without inducing middle junction voltage degradation, they can lead to a slight reduction of minority carrier diffusion lengths in films grown after the QDs. Switching to an inverted metamorphic structure allows for the top cell to be grown first, but leads to challenges in maintaining current collection in the middle junction. In this work, a novel InAs/GaAs QD middle junction cell design is proposed for improving the efficiency of triple junction inverted metamorphic solar cells. Conventionally designed thin emitter devices as well as the proposed thick emitter devices were grown with and without InAs QDs in the uid region of the middle junction. The conventionally designed QDSC exhibited 1.8% relative increase in J SC over the control device with no loss in V OC resulting in a 1.8% relative increase in efficiency over the control device.

In this work, a Sentaurus TCAD model of inverted metamorphic triple junction solar cells is demonstrated along with experimental 3J current-voltage and external quantum efficiency measurements for the purpose of predicting end-of-life efficiency improvement from incorporating quantum wells or quantum dots into a metamorphic In 0.3 Ga 0.7 As sub cell in a 3J solar cell. A radiation-hard “end-of-life optimized” design is presented and end-of life efficiency enhancement is predicted from calculated QD and QW absorption coefficients. The resulting QW enhanced solar cell design is predicted to have a 6% relative efficiency enhancement over the optimized baseline design.

Reduction in surface and interface reflectance via the integration of subwavelength nanostructures in flexible polymer packaging material combined with incorporation of dielectric nanoislands into a conventional two-layer antireflection coating has been demonstrated, analyzed and optimized. Transmittance measurements of moth-eye textured polymer packaging sheets with different tapered pillar heights fabricated by reactive-ion etching and nanosphere lithography provide insights into the choice of the optimum nanostructure dimensions. Detailed computational modeling and simulations elucidate the physical nature of the antireflection performance of dielectric nanoisland structures integrated with a commercial two-layer antireflection coating, and provide guidance for design of the nanoisland structure for optimum antireflection performance. Measurements show that the integration of appropriately designed nanostructures in both polymer packaging material and conventional antireflection layers enables substantial increases in external quantum efficiency (E.Q.E.) and short-circuit current density (Jsc) over a broad range of incident angles, compared to structures with conventional bilayer antireflection coatings and unpatterned polymer packaging sheets. A 1.1× increase in Jsc, derived directly from E.Q.E. measurements, at normal incidence, increasing to 1.67× improvement at 80° angle of incidence, suggests that such an approach is promising for a variety of photovoltaic applications, particularly those where solar tracking is not feasible or practical. Copyright © 2014 John Wiley & Sons, Ltd.

High performance and cost effective multi-junction III-V solar cells are attractive for satellite applications. High performance multi-junction solar cells are based on a triple-junction design that employs an InGaP top-junction, a GaAs middle-junction, and a bottom-junction consisting of a 1.0 – 1.25 eV-material. The most attractive 1.0 – 1.25 eV-material is the lattice-matched dilute nitride such as InGaAsN(Sb). A record efficiency of 43.5% was achieved from multi-junction solar cells including dilute nitride materials [1]. In addition, cost effective manufacturing of III-V triple-junction solar cells can be achieved by employing full-wafer epitaxial lift-off (ELO) technology, which enables multiple substrate re-usages. We employed time-resolved photoluminescence (TR-PL) techniques to study carrier dynamics in both pre- and post-ELO processed GaAs double heterostructures (DHs) as well as in MOVPE-grown bulk dilute nitride layers lattice matched to GaAs substrates.

Short-wavelength (λ∼3.6 μm) quantum-cascade-laser (QCL) designs, employing a metamorphic buffer layer (MBL) on a GaAs substrate, have been developed for strong carrier confinement to the active regions, as a result of implementing the deep well and tapered active-region concepts. The strain·thickness product values for the quantum wells and barriers comprising the QCL active regions (ARs) are kept basically the same as those employed for longer wavelength (λ∼4.8 μm) QCL AR structures grown on InP substrates. Strain-compensated superlattice (SL) structures, representative of the QCL AR, are grown by metalorganic vapor phase epitaxy (MOVPE) on an AlInGaAs compositionally step-graded MBL. Structural characterization of the SL structures underscores the importance of reducing the top-surface roughness of the underlying MBL. Intersubband absorption has been observed for doped SL structures grown on hydride-VPE-grown MBLs.

Electrical capacitance tomography (ECT) is a non destructive technique for obtaining the distribution of some physical quantity in a closed pipe by measuring the permittivity distribution. Several conducting plates are fixed around the circumference of the pipe so they do not disturb the flow or movement of materials. The imaging quality of an electrical capacitance tomography system depends upon many co-influential parameters such as number of electrodes, length and width of electrodes, axial guard electrodes, radial guard electrodes, and screen guard. Optimum selection of these variables coupled with advancements in sensing electronics and imaging algorithm provides the best inside view of a closed vessel/pipe. This, in turn, provides better process information for control. This article is intended to summarize such design rules for ECT electrodes and sensors. Numerical simulations were performed using commercially available finite element method (FEM) software to help verify the optimality of the desig...

The military's need to reduce both fuel and battery resupply is a real-time requirement for increasing combat effectiveness and decreasing vulnerability. Mobile photovoltaics (PV) is a technology that can address these needs by leveraging emerging, flexible space PV technology. In this project, the development and production of a semirigid, lightweight, efficient solar blanket with the ability to mount on, or stow in, a backpack and recharge a high-capacity rechargeable lithium-ion battery was undertaken. The 19% efficient blanket consists of a 10 × 3 solar array of 20 cm2 and single-junction epitaxial lift-off solar cells, which have an efficiency of ∼22% under AM1.5G illumination. A power-conditioning module was also developed to interface the solar panel to the battery. Thirteen systems were outfitted during a Limited Objective Experiment-1 in February 2012, and based on the results, a second version of the system is in development.

State-of-the-art triple junction inverse metamorphic solar cells have been known to have bottom InGaAs junction that are limiting to the overall radiation performance. It has been proposed that the addition of quantum dots to the bottom junction would improve radiation tolerance of the bottom cell, and thus enhance the triple junctions overall performance in high dose applications. A significant amount of development has been made on quantum dots in metamorphic InGaAs for laser applications, however to date little work has been accomplished for photovoltaic devices. For this study we evaluate the growth of InAs quantum dots on In 0 . 31 GaAs grown metamorphically on GaAs. Simulations show that the addition of 50 layers of quantum dots to the bottom junction increases the expected efficiency by 0.2% at a dose of 1×1012 protons/cm2, however this would be a larger increase at a higher dose or if the bottom cell were current limiting. Evaluating the formation by atomic force microscopy with a height of 2.5 nm and density of approximately 7.8×1010 dots/cm2. Temperature dependent photoluminescence measurements were completed to extract an activation energy of 84.6 meV, which corresponds with the calculated electron confinement in the quantum dot.

Thin ELO devices with light management allow for increased quantum dot (QD) absorption without the need for excessive strain management. A growth study was designed to evaluate challenges regarding inverted growth of ELO QDSCs. Two upright GaAs cell designs were investigated: a standard device and a “thick emitter” device. For each design, two QDSCs and a baseline without QDs were grown and fabricated. One standard QDSC was annealed for two hours while one thick emitter QDSC had an increased QD superlattice period. The standard baseline had a Jsc of 20.7 mA/cm2 and a Voc of 1.01 V, while the standard QDSC had a J SC of 21.2 mA/cm2 and V oc of 0.988 V. The thick emitter baseline had a J SC of 21.4 mA/cm2 and a V oc of 1.04, while the thick emitter QDSC with increased period had a J SC of 21.9 mA/cm2 and V oc of 0.99 V which is on par with the best reported QDSC Vocs· Finally, inverted GaAs cells with and without QDs were fabricated with back surface reflectors (BSRs) and removed from the substrate by ELO. Devices with flat BSRs and textured BSRs are compared. The QDSC with the flat BSR had a sub-bandgap integrated spectral response equivalent to 0.38 mA/cm2 while the textured BSR showed 0.57 mA/cm2, which represents a 30% increase over the flat BSR.

III-V multi-junction solar cells are based on a triple-junction design that consists of an InGaP top junction, a GaAs middle junction, and a bottom junction that employs either a 1eV material grown on the GaAs substrate or InGaAs grown on the Ge substrate. The most promising 1 eV materials under extensive investigation are the bulk dilute nitride such as InGaAsN(Sb) lattice-matched to GaAs substrate and the dilute-bismide quantum well materials, such as GaAsBi, strain-compensated with GaAsP barriers. Both approaches have the potential to achieve high performance triple-junction solar cells. In addition, space satellite applications utilizing III-V triple-junction solar cells can have significantly reduced weight and high efficiency. An attractive approach to achieve these goals is to employ full-wafer epitaxial lift off (ELO) technology, which can eliminate the substrate weight and also enable multiple substrate re-usages. For the present study, we employed time-resolved photoluminescence (TR-PL) techniques to study carrier dynamics in MOVPE-grown bulk dilute bismide double heterostructures (DH). Carrier lifetime measurements are crucial to optimizing MOVPE materials growth. We have studied carrier dynamics in GaAsBi QW structures with GaAsP barriers. Carrier lifetimes were measured from GaAsBi DH samples at different stages of post-growth thermal annealing steps. Post-growth annealing yielded significant improvements in carrier lifetimes. Based on this study, single junction solar cells (SJSC) were grown and annealed under a variety of conditions and characterized. The SJSC annealed at 600 – 650 °C exhibited improved response in EQE spectra. In addition, we studied carrier dynamics in MOVPE-grown GaAs-In(Al)GaP DH samples grown on GaAs substrates. The structures were grown on top of a thin AlAs release layer, which allowed epitaxial layers grown on top of the AlAs layer to be removed from the substrate. The GaAs active layers had various doping densities and thicknesses. Our TR-PL results from both pre- and post-ELO processed GaAs-In(Al)GaP DH samples are reported.

We propose here a new algorithm for plant classification and identification based on fractal dimension. It is a simple and efficient technique for identifying plants using three levels of fractal refinement on leaf images. Contour, Contour-Nervure and Nervure fractal dimensions are computed and are used in the first, second and third level of refinement respectively. A 50 set species with each set containing 10 samples are used for training the algorithm. The performance of the algorithm was examined with a test set of 500 leaves arbitrarily selected from different groups of species. The fault acceptance rate (FAR), the fault rejection rate (FRR) and the classification accuracy of the algorithm were analyzed experimentally and demonstrated that the proposed method has an accuracy rate of 84%.

In order to gain insight into the formation dynamics of mudbanks off the Kerala coast of India, extensive surveying of the nearshore bathymetry along with sediment characterization was undertaken. The textural and geotechnical properties of the surficial sediments of a mudbank were determined during pre-monsoon, monsoon, and post-monsoon periods. The mudbank sediments were clayey silts with high water and organic carbon contents, high Atterberg limits, and low bulk density, and therefore very susceptible to entrainment. During the monsoon, the mudbank regime was characterised by enhanced turbidity and a benthic fluff layer, triggered by the increasing swell of the early monsoon period. Re-suspension exposed a more consolidated, previously sub-bottom, layer which exhibited lower water content and greater shear strength than the pre-monsoon seabed. Texturally, the monsoon seabed was similar to the pre-monsoon seabed, with the same modal grain size, but the proportions of sand and coarse silt increased nearshore, while the proportions of fine and very fine silt increased offshore. There was a seaward-fining textural gradient at all times, but this became pronounced during the monsoon period. Paradoxically, the monsoonal seabed displayed greatly reduced wet bulk density. It is hypothesized that this was due to the presence of gas, probably methane, in the sediments (while the pre-monsoon sediments were fully saturated, the monsoon sediments were only 83% saturated). We speculate that the gas was forced into the surficial sediments either by wave pumping (at the onset of the monsoon) or by seaward-flowing subbottom freshwater (derived from monsoonal rains). With the waning of the monsoon, the benthic fluid mud layer rapidly disappeared and the seabed returned to its pre-monsoon state as suspended sediments were redeposited. The mudbank regime is therefore essentially an in situ phenomenon. It is suggested that the mudbanks are palimpsest, marshy, lagoonal deposits, rich in organic matter and derived gas, that were submerged after a marine transgression. The surficial sediment is annually entrained during the monsoon, but erosion is limited by the formation of the benthic fluid mud layer, which attenuates wave generated turbulence. Although some fine sediment disperses alongshore and offshore, most is returned to the seabed as the monsoon declines.

This paper discusses the impact of the December 26, 2004 tsunami on the geomorphic features and sediment characteristics along the southwest coast of India. The data used include field observations made after the tsunami, and the inferences drawn from the satellite imagery taken before and after the tsunami. Sediment samples collected from the inner shelf, beach and estuarine environments were analyzed to understand post-tsunami changes in grain-size characteristics. The tsunami eroded and transported landwards significant volumes of distinct black sands, rich in heavy minerals, from the shelf onto the beaches of the Kerala region, and up to 500 m inland of the present coast.