1,734 research outputs found

    (E)-2-[4-tert-Butyl-5-(2,4,5-trimethoxy­benz­yl)thia­zol-2-ylimino­meth­yl]phenol

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    In the title compound, C24H28N2O4S, the dihedral angle between the phenol ring and the thia­zole ring system is 10.6 (1)°, and the trimethoxy­phenyl group is approximately perpendicular to the thia­zole ring, the dihedral angle being 84.7 (2)°. There is a strong intra­molecular hydrogen-bonding inter­action between the Schiff base and the hydr­oxy group

    One-Year Simulation of Ozone and Particulate Matter in China Using WRF/CMAQ Modeling System

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    Abstract. China has been experiencing severe air pollution in recent decades. Although an ambient air quality monitoring network for criteria pollutants has been constructed in over 100 cities since 2013 in China, the temporal and spatial characteristics of some important pollutants, such as particulate matter (PM) components, remain unknown, limiting further studies investigating potential air pollution control strategies to improve air quality and associating human health outcomes with air pollution exposure. In this study, a yearlong (2013) air quality simulation using the Weather Research and Forecasting (WRF) model and the Community Multi-scale Air Quality (CMAQ) model was conducted to provide detailed temporal and spatial information of ozone (O3), total PM2.5, and chemical components. Multi-resolution Emission Inventory for China (MEIC) was used for anthropogenic emissions and observation data obtained from the national air quality monitoring network were collected to validate model performance. The model successfully reproduces the O3 and PM2.5 concentrations at most cities for most months, with model performance statistics meeting the performance criteria. However, overprediction of O3 generally occurs at low concentration range while underprediction of PM2.5 happens at low concentration range in summer. Spatially, the model has better performance in southern China than in northern China, central China, and Sichuan Basin. Strong seasonal variations of PM2.5 exist and wind speed and direction play important roles in high PM2.5 events. Secondary components have more boarder distribution than primary components. Sulfate (SO42−), nitrate (NO3−), ammonium (NH4+), and primary organic aerosol (POA) are the most important PM2.5 components. All components have the highest concentrations in winter except secondary organic aerosol (SOA). This study proves the ability of the CMAQ model to reproduce severe air pollution in China, identifies the directions where improvements are needed, and provides information for human exposure to multiple pollutants for assessing health effects. </jats:p

    The “Groundwater Benefit Zone”, Proposals, Contributions and New Scientific Issues

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    The groundwater has great potential for water resource utilization, accounting for about a quarter of vegetation transpiration globally and contributing up to 84% in shallow groundwater areas. However, in irrigated agricultural regions or coastal areas with shallow groundwater levels, due to the high groundwater salinity, the contribution of groundwater to transpiration is small and even harmful. This paper proposes a new conception of groundwater benefit zone in the groundwater-soil–plant-atmosphere continuum (GSPAC) system. Firstly, it analyzes the mutual feedback processes of the underground hydrological process and aboveground farmland ecosystem. Secondly, it elaborates on the regional water and salt movement model proposed vital technologies based on the optimal regulation of the groundwater benefit zone and is committed to building a synergy that considers soil salt control and groundwater yield subsidies. Finally, based on the GSPAC system water-salt coupling transport mechanism, quantitative model of groundwater benefit zone, and technical parameters of regional water-salt regulation and control, the scientific problems and development opportunities related to the conception of groundwater benefit zone have been prospected

    Dual-Band Eight-Element MIMO Array Using Multi-Slot Decoupling Technique for 5G Terminals

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    This paper presents a dual-band eight-element multiple-input multiple-output (MIMO) array using a multi-slot decoupling technique for the fifth generation (5G) mobile communication. By employing a compact dual-loop antenna element, the proposed array obtains two broad bandwidths of 12.2% and 15.4% for sub-6GHz operation. To reduce the mutual coupling between antenna elements, a novel dual-band decoupling method is proposed by employing a multi-slot structure. The proposed MIMO array achieves 15.5-dB and 19.0-dB isolations across the two operating bands. Furthermore, three decoupling modes generated by different bent slots can be independently tuned. Zero ground clearance is also realized by the coplanar arrangement of the antenna elements and decoupling structures. The proposed MIMO array was simulated, fabricated, and measured. Experimental results agree well with the simulations, showing that the dual-band MIMO array has good impedance matching, high isolation, and high efficiency. In addition, the envelope correlation coefficient and channel capacity are calculated and analyzed to validate the MIMO performance of the 5G terminal array. Such a dual-band high-isolation eight-element MIMO array with zero ground clearance is a promising candidate for 5G or future mobile applications

    A Wideband Triple-Mode Differentially-Fed Microstrip Patch Antenna

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    © 2021 IEEE. This is the accepted manuscript version of an article which has been published in final form at https://dx.doi.org/10.1109/LAWP.2021.3074302A wideband differentially-fed microstrip patch antenna (MPA) with tripe-resonant modes is presented in this letter. The proposed triple-mode MPA is realized by combining two dual-mode MPAs (MPA-I and MPA-II) with different resonant frequency ratios. Firstly, the TM0,1 mode and TM0,1/2 mode of dual-mode MPA-I can be concurrently excited by adding a pair of coupling shorted patches beside the strip MPA. The ratio of f0,1/2/f0,1 can be easily adjusted by moving the shorting pins between the strip MPA and shorted patches. Secondly, by properly designing the dimensions of a conventional MPA, the TM0,1 and TM2,1 modes of dual-mode MPA-II are simultaneously excited. To further reduce the ratio of f2,1/f0,1, four slots are elaborately etched on the conventional MPA. Finally, by combining the two dual-mode MPAs, a triple-mode MPA with the frequency ratio of f0,1/2:f2,1:f0,1 = 1.2:1.1:1 is realized. To verify the design concept, a prototype of triple-mode MPA was fabricated and measured. Experimental results show that the proposed microstrip antenna achieves a wide bandwidth of 26.5%, a low cross-polarization of -23 dB, and high harmonic suppression.Peer reviewe
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