秸秆燃烧排放PM2.5特征及影响因素研究

生物质燃烧向大气中排放大量颗粒污染物, 在中国, 收获季节大量秸秆被直接露天燃烧处理, 对区域环境质量和人体健康造成严重影响. 对我国最主要的两种粮食作物玉米和小麦秸秆的露天燃烧进行模拟, 分析颗粒物排放水平, 特征及影响因素. 玉米和小麦秸秆燃烧PM_2.5排放因子分别为1082.8和835.7~897.3 mg/kg. 有机物是颗粒物最主要组分, 总量占PM_2.5质量的42%~66%. Cl^-和K⁺分别占PM_2.5总质量的4%~15%和2%~14%, K⁺/EC值为0.5~3.8. 各物种在颗粒物中所占比例与之前研究结果一致. 秸秆含水量和燃烧温度影响PM_2.5排放水平和组成特征. 随秸秆含水量增加, PM_2.5和OC的排放因子增加; 秸秆含水量增加, 燃烧温度逐渐降低, 由生物质燃料释放进入烟气中的K⁺和Cl^-比例逐渐减小导致二者在颗粒物中的比例降低. 我国每年由玉米和小麦秸秆露天燃烧排放的PM_2.5和OC分别为92.7 Gg和47.5 Gg, 在总量中占重要比例.     

Simultaneous two-way classical communication and measurement-device-independent quantum key distribution on oceanic quantum channels

Simultaneous two-way classical and quantum (STCQ) communication combines both continuous classical coherent optical communication and continuous-variable quantum key distribution (CV-QKD), which eliminates all detection-related imperfections by being measurement-device-independent (MDI). In this paper, we propose a protocol relying on STCQ communication on the oceanic quantum channel, in which the superposition-modulation-based coherent states depend on the information bits of both the secret key and the classical communication ciphertext. We analyse the encoding combination in classical communication and consider the probability distribution transmittance under seawater turbulence with various interference factors. Our numerical simulations of various practical scenarios demonstrate that the proposed protocol can simultaneously enable two-way classical communication and CV-MDI QKD with just a slight performance degradation transmission distance compared to the original CV-MDI QKD scheme. Moreover, the asymmetric situation outperforms the symmetric case in terms of transmission distance and optical modulation variance. We further take into consideration the impact of finite-size effects to illustrate the applicability of the proposed scheme in practical scenarios. The results show the feasibility of the underwater STCQ scheme, which contributes toward developing a global quantum communication network in free space.     

Structure and magnetism of ZnO/Co multilayers prepared by pulsed laser deposition

ZnO/Co multilayers were fabricated on silicate (100) substrate by a pulsed laser deposition method at room temperature. The x‐ray diffraction (XRD) results reveal that the as‐deposited multilayer film is composed of amorphous phase, which leads to high saturation magnetization and low coercivity. Higher coercivity is observed in the ZnO/Co films annealed at 390 °C due to the formation of crystalline metallic Co and semiconducting ZnO. But much higher annealing temperature leads to the oxidation of metallic Co and the reaction between Co and ZnO, which decreases the saturation magnetization and coercivity obviously.     

Growth and spectroscopic investigation of Yb/Nd co‐doped KLu(WO4)2 laser crystals

Single crystals of Yb, Nd: KLu(WO₄)₂ (Yb, Nd: KLW) of dimensions up to 40mm× 40mm×5mm have been grown by top‐seeded solution growth (TSSG) method. X‐ray powder diffraction pattern was measured and compared with that of Nd: KLuW and Yb: KLuW. Absorption and fluorescence spectra were measured at room temperature. The Judd‐Ofelt theory was applied to analyze the spectrum of Nd, Yb: KLuW crystal. The intensity parameters Ω_t (t=2, 4 and 6) were calculated as Ω₂=20.68×10^‐20cm², Ω₄=11.04×10^‐20cm², Ω₆=6.74×10^‐20cm² respectively, with a root mean square deviation of 0.58×10^‐20 cm². (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electrospun Nanofibrous Adsorption Membranes for Wastewater Treatment: Mechanical Strength Enhancement

Functional nanofibrous membranes fabricated by electrospinning technology have attracted much attention in the removal of heavy metal ions from contaminated wastewater. The high specific surface area, high porosity and ease of functionality create an enhanced throughput and high adsorption capacity of the nanofibrous membrane. However, the relatively poor mechanical properties of the membrane with a non-woven nanofibrous structure are one of the major concerns, which can limit the applications in wastewater treatment. Different strategies and methodologies were explored to address the problems and were reviewed in this work, highlighting the possibilities of overcoming the poor mechanical properties of the nanofibrous membrane and to ensure the recyclability and reusability of the membrane during the adsorption process.     

Research on an E-mail Encryption Protocol Based on Quantum Teleportation

With the rapid development of information technology (IT), E-mail has become an important communication tool between human beings. Meanwhile, E-mail safety becomes increasingly important because of its universal applications. In order to overcome shortages of classical E-mail encryption, an E-mail encryption protocol based on quantum teleportation was proposed. It makes quantum encryption of E-mails during sending and receiving processes by taking advantages of entanglement and nonclonability of quantum, thus ensuring safety and reliability of E-mail transmission.     

Learning-based nonlinear model predictive control with accurate uncertainty compensation

Nonlinear Dynamics - A learning-based nonlinear model predictive control (LBNMPC) method is proposed in this paper for general nonlinear systems under system uncertainties and subject to state and...