59 research outputs found

    Frangibility Quantification of Frangible Bullet upon Impact on a Hard Target

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    The article presents a new method of quantitative evaluation of the degree of disintegration, called frangibility of frangible bullets, based on shooting experiments. On the basis of the dependence of the Frangibility Factor of the bullet on its impact velocity, the frangibility index is determined as a quantifier of the projectile’s ability to disintegrate into fragments applied for a certain range of interest. The method can be used to assess the ability to disintegrate into fragments of various types of bullets, preferably frangible bullets produced by powder metallurgy technologies. The proposed method was used to quantify the frangibility of five experimental frangible bullets

    REALIZATION OF BROADBAND AND INDEPENDENT POLARIZATION METAMATERIAL PERFECT ABSORBER BASED ON THE THIRD-ORDER RESONANCE

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    In this report, we studied numerically and experimentally the electromagnetic properties of perfect MAs using ring-shaped structures at microwave frequencies. By creating a magnetic resonance, the ring structure confines electromagnetic energy at the first- and third-order resonances. And then, we leveraged the super-cell structures, which consist of different rings in one unit cell to obtain broadband absorption. The results showed that the absorption band of MA is broaden from 1.3 to 2.17 GHz when the number of rings in the unit cell increases from four to nine-ring

    All-dielectric Metamaterial for Electromagnetically-induced Transparency in Optical Region

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    Metamaterial (MM) is emerging as a promising approach to manipulate electromagnetic waves, spanning from radio frequency to the optical region. In this paper, we employ an effect called electromagnetically-induced transparency (EIT) in all-dielectric MM structures to create a narrow transparent window in opaque broadband of the optical region (580-670 nm). Using dielectric materials instead of metals can mitigate the large non-radiative ohmic loss on the metal surface. The unit-cell of MM consists of Silicon (Si) bars on Silicon dioxide (SiO2_{2}) substrate, in which two bars are directed horizontally and one bar is directed vertically. By changing the relative position and dimension of the Si bars, the EIT effect could be achieved. The optical properties of the proposed MM are investigated numerically using the finite difference method with commercial software Computer Simulation Technology (CST). Then, characteristic parameters of MM exhibiting EIT effect (EIT-MM), including Q-factor, group delay, are calculated to evaluate the applicability of EIT-MM to sensing and light confinement

    Fuzzy Equivalence on Standard and Rough Neutrosophic Sets and Applications to Clustering Analysis

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    In this paper, we propose the concept of fuzzy equivalence on standard neutrosophic sets and rough standard neutrosophic sets. We also provide some formulas for fuzzy equivalence on standard neutrosophic sets and rough standard neutrosophic sets. We also apply these formulas for cluster analysis. Numerical examples are illustrated

    HORIZONTALLY PLASMON HYBRIDIZATION ON SYMMETRIC-BREAKING METAMATERIALS

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    In this report, we present a study on the fundamental negative-permeability metamaterials, named as the cut-wire-pair structure. The physics of the cut-wire-pair metamaterial is interpreted using the electromagnetic analog of molecular-orbital theory. It is shown that a symmetric-breaking cut-wire-pair metamaterial is horizontally plasmon-hybridized, leading to an additional magnetic resonance beyond the conventional one. The transmission spectra and the induced energy distributions are performed to demonstrate our prediction

    Investigation of salt-tolerant rhizosphere bacteria from seawater-intruding paddy rice field in Vietnam

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    Salt‐tolerant plant growth‐promoting rhizobacteria (ST‐PGPR) are known as potential tools to improve rice salinity tolerance. In this study, we aimed to investigate the plant growth‐promoting rhizobacteria community richness of the paddy rice fields in Soc Trang and Ben Tre Provinces where were seriously affected by sea level rise. The salinity in the sampling sites ranged from 0.14‰ to 2.17‰ in November 2018, the rainy season. The microbial abundance of samples was evaluated by spreading the samples in tryptic soy agar (TSA) medium supplemented with various concentrations of NaCl. With the increase of salt concentration up to 10% NaCl, a total number of bacteria decreased for all the samples, ranging from 106 to 104 CFU/g, and bacterial colonies were not observed at 30% NaCl. Among a total of 48 salt-resisting bacteria isolated from the rice paddy field mud surrounding the rice root, 22 isolates were able to produce indole-3-acetic acid (IAA: phytohormone for the plant growth). Seventeen out of 48 isolates were able to grow in the medium without nitrogen or phosphor sources. Six isolates having high IAA producing activity, nitrogen fixation and phosphate solubilization were belonged to Bacillus (DT6, LT16, and LHT8), Halobacillus (DT8), Aeromonas (LHT1), and Klebsiella (LHT7) genera. All the sequences of the strains DT6, DT8, LT16, LHT1, LHT7, and LHT8 were registered in the GeneBank with the accession numbers MK335670, MK335671, MK335672, MK335673, MK335674, and MK335675, respectively.

    Toxoplasma gondii contamination in fresh vegetables destined for human and livestock consumption in Thua Thien Hue, Vietnam

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    Toxoplasmosis caused by Toxoplasma gondii is an important zoonosis that shows severe symptoms in immunocompromised patients. High seroprevalences of toxoplasmosis were found in cats, humans, and pigs in traditional farms in Thua Thien Hue province. The main sources of infections remain unknown, thus making toxoplasmosis neglected and uncontrollable in this region. This study aimed to determine T. gondii contamination in vegetables used for human and livestock consumption and its spatial distribution in Thua Thien Hue rural areas. A cross-sectional study was conducted to investigate T. gondii contamination in vegetables grown in households in three different geographic regions. The pathogen DNA was detected from vegetable samples using a primer pair that is highly specific for the 529-bp repetitive element found in T. gondii genome. In this study, 55 out of 221 (24.9%) vegetable samples were positive for T. gondii using PCR. Factors, including location, presence of fence in the garden, owning cats, and treatment of feed for cats, were not significantly associated with T. gondii contamination in vegetables according to the logistic regression. However, vegetables collected in households that have no fence for vegetable gardens, own cats, and feed cats raw or undercooked foods tend to be more heavily contaminated than others. Furthermore, a wide distribution of infected vegetables was observed in all investigated districts, showing a high infection pressure in these residential areas. This is the first report of vegetables contaminated with T. gondii in Vietnam, which reveals an overlooked health risk for humans and animals

    Remotely sensed drought evaluation over rice cultivated areas in Cambodia during 2000 to 2019

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    Drought is one of the costliest natural disasters, effecting many aspects of human livelihoods. This study assessed drought conditions in Cambodia from Moderate Resolution Imaging Spectroradiometer (MODIS) data during 2000 to 2019 using the Vegetation Health Index. The results verified with the satellite soil moisture indicated close agreement between these two datasets. The drought areas were concentrated in the country’s central plains, with the larger drought area particularly observed for 2016. Roughly 31.3% of rice-growing area was affected by severe drought during the dry season in this abnormal year (2016), compared to that of 26.1% in a normal year (2017). The results of drought probability calculated for the entire study period indicated that 63 and 17 districts were associated with droughts in the dry and wet seasons, respectively. This study demonstrated the potential application of MODIS data for decadal drought assessment over rice cultivated areas, which was important for crop and water management
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