84 research outputs found

    Characterization of a MEMS acoustic/pressure sensor

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76702/1/AIAA-1999-520-510.pd

    Near Field iToF LIDAR Depth Improvement from Limited Number of Shots

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    Indirect Time of Flight LiDARs can indirectly calculate the scene's depth from the phase shift angle between transmitted and received laser signals with amplitudes modulated at a predefined frequency. Unfortunately, this method generates ambiguity in calculated depth when the phase shift angle value exceeds 2π2\pi. Current state-of-the-art methods use raw samples generated using two distinct modulation frequencies to overcome this ambiguity problem. However, this comes at the cost of increasing laser components' stress and raising their temperature, which reduces their lifetime and increases power consumption. In our work, we study two different methods to recover the entire depth range of the LiDAR using fewer raw data sample shots from a single modulation frequency with the support of sensor's gray scale output to reduce the laser components' stress and power consumption

    Electrical and Optical Properties of Flexible Transparent Silver Nanowires electrodes

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    AgNWs were produced by the one-pot polyol method, and it had been produced by reduction of AgNO3 by ethylene glycol in presence of polyvinylpyrrolidone (PVP) and KCl at high temperature of about 160 oC. AgNWs suspension were purified by centrifuging at 3000 rpm for three times then re-depressed in deionized water with a concentration of 1%. The purified suspension was diluted to different concentrations (2-5) mg. mL-1 using 1% of hydroxy methylcellulose to design different AgNWs transparent conductive films (AgNWs-TCFs). AgNWs suspension inks were coated on the glass and polyethylene terephthalate (PET) substrates. Different AgNWs diameters were obtained by changing the synthesis conditions. It has been observed that the wire diameter will greatly affect both the optical and electrical properties of the obtained AgNWs-TCFs. The best obtained AgNWs-TCFs had high transparency of about 91.5 %, small sheet resistance of about 14 .03 Ω and optical haze less than 2%, which met the requirements for the manufacture of optoelectronic and sensor equipment. Keywords: Silver nanowires, transparent conductive electrode, flexible electrodes, polyol method, AgNWs size control, AgNWs size-dependent and one-pot synthesis

    Assessment of Some Mango Species by Fruit Characters and Fingerprint

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    Abstract: Six local mango accessions; Zebda, Zaghloul, Gemela, Ganofia, El-Madam and ElKobbaneia were collected from private farm in Sharkia Governorate. Physical and chemical characteristics of fruits study besides of molecular characterization (as total proteins). The data showed that El-Kobbaneia fruit had the biggest fruit also El-Madam produced the smallest one. The lowest fiber percentage was clear in Ganofia fruit followed by Zebda fruit as compared with all mango fruits under study. The highest fruit Juice percentage was shown in El-Kobbaneia fruit, while Ganofia fruit had the lowest one. Also, the lowest titrable acidity was clear in Ganofia fruit, but the highest one was detected in Zebda fruit. Meanwhile, the highest total sugar was clear in Gemela fruit. However, El-Madam fruit had the lowest VC. The highest total number of variable bands (seven) was existed in Zebda species while the lowest number was presented in Ganofia species (2 bands). The percentage of polymorphism in all mango species ranged between 16.7% in both EL-Kobbaneia and Gemela species to 29.2 % in Zebda species

    Thermogalvanic effects on the corrosion of copper in heavy brine LiBr solutions

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    Thermogalvanic corrosion of copper in heavy brine LiBr solutions has been investigated using a zero-resistance ammeter (ZRA). The temperature gradients between copper electrodes immersed in the same LiBr solution result in the formation of thermogalvanic cells with hot anodes, leading to high and sustained thermogalvanic currents. Copper loss rates, calculated using Faraday's law, substantially exceed 0.025 mm year−1, a value regarded as the threshold of low corrosion rates. The effects of thermogalvanic coupling on the surface properties of the anode and the cathode have been analysed by means of electrochemical impedance spectroscopy (EIS). The results obtained in this analysis have been related to the process of copper electrodissolution in bromide media

    Passive and transpassive behaviour of Alloy 31 in a heavy brine LiBr solution

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    The passive and transpassive behaviour of Alloy 31, a highly alloyed austenitic stainless steel (UNS N08031), has been investigated in a LiBr heavy brine solution (400 g/l) at 25 °C using potentiostatic polarisation combined with electrochemical impedance spectroscopy and Mott-Schottky analysis. The passive film formed on Alloy 31 has been found to be p-type and/or n-type in electronic character, depending on the film formation potential. The thickness of the film formed at potentials within the passive region increases linearly with applied potential. The film formed at transpassive potentials is thinner and more conductive than the film formed within the passive region. These observations are consistent with the predictions of the Point Defect Model for passive and transpassive films on metals and alloys

    The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

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    INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century
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