Trajectory stabilization control for aerial recovery of cable-drogue-UAV assembly

Unmanned aerial vehicles (UAVs) aerial recovery denotes the technology that UAVs are recovered in the air by the transport aircraft for reuse. During the recovery process, the multiple wind perturbations and fast-changing UAV’s engine shutdown will induce oscillations in the cable-drogue-UAV assembly (CDUA) with strong nonlinearities and tight coupling, which affects the safety and speed of the UAV aerial recovery. Aiming at this problem, this paper proposes a non-constraining force direction (NCFD)-based CDUA anti-disturbance trajectory control method for the first time. First, by transforming the CDUA trajectory control to the NCFD control, the coupling and nonlinear effects in the CDUA can be reduced, and the fast-changing disturbances caused by the engine shutdown can be compensated. Then, feed forward control is designed based on the relationship between the NCFD and cable shape, which is established based on the cable dynamics, to improve the response speed. Furthermore, a fixed-time anti-disturbance controller (FTADC) is designed for the flow angle of drogue-UAV assembly (DUA) given by the NCFD controller and compensates for the effects of wind and parameter perturbations. Finally, the stability of the proposed method is analyzed, and the effectiveness is demonstrated by abundant simulations.

     

高效液相色谱法测定氨纶企业废气中4种酰胺类化合物

采用高效液相色谱法测定氨纶企业废气中4种酰胺类化合物.使用内部装有高纯水的多孔玻璃板吸收管采集空气和废气样品,用0.22μm针式滤器过滤吸收液,使用Shim-pack GIST C18色谱柱(250 mm×4.6 mm,5μm)分离,以乙腈–水作为流动相等度洗脱,用紫外检测器单波长检测,色谱峰面积外标法定量.甲酰胺、二甲基甲酰胺、二甲基乙酰胺和丙烯酰胺的质量浓度在0.50～50.0 mg/L范围内与色谱峰面积线性良好,相关系数均大于0.999,当采样体积为20 L时,甲酰胺、二甲基甲酰胺、二甲基乙酰胺和丙烯酰胺的检出限分别为0.0026、0.0025、0.0017、0.0040 mg/m3,测定值的相对标准偏差小于5％(n=6),加标回收率为100.75％～103.01％.该法样品处理简单,分析速度快,灵敏度高.     

距离深度域最小二乘矩阵滤波器的设计与应用

本文通过最小二乘原理设计出针对拷贝向量进行处理的矩阵滤波器,给出了其详细的推导过程。它可用于距离深度域上的预滤波,在抑制阻带干扰的同时,保证通带信号尽可能不失真。设计过程中发现根据最小二乘原理设计矩阵滤波器比二阶锥规划等其他寻优方法更快捷。最小二乘矩阵滤波器除了能在保证通带尽量不失真的前提下达到很好的阻带抑制效果之外,还可以在任意距离深度设定通、阻带,尤其适用于阵列在探测过程中抑制强干扰对于弱目标源的影响。     

4‐Benzamido‐TEMPO Catalyzed Oxidation of a Broad Range of Alcohols to the Carbonyl Compounds with NaBrO3 under Mild Conditions

4‐Benzamido‐TEMPO catalyzed oxidation system for conversion of a wide range of alcohols to the aldehydes or ketones with NaBrO₃ under room temperature conditions has been developed. The credible, operationally convenient and economical, and condition mild oxidation protocol is particularly of interest in laboratory and in fine chemicals manufacture.     

爆炸作用下土体隧道衬砌结构的动力响应

为了找出爆炸动力作用下的隧道衬砌结构薄弱部位和力学规律,建立了土体隧道动力分析整体有限元模型;利用显式动力有限元程序Ansys/Ls-dyna进行了数值模拟,探讨了土体隧道衬砌结构在爆炸作用下不同部位的时间历程曲线;分析了爆炸作用下土体隧道衬砌结构的动力响应。结果显示:隧道衬砌结构肩部在x、y方向的位移都较大;隧道衬砌结构顶部在y方向的位移较大;隧道衬砌结构顶部、肩部的加速度峰值最大并且加速度曲线均出现了两次或多次峰值。这反映了爆炸冲击波有比较强烈的多次反射;各部位压力时程曲线波动较大,按照肩部、顶部、胯部、底部、腰部的顺序先后到达峰值;顶部和肩部σx峰值最大,顶部和底部σy峰值最大,顶部、肩部、底部τmax峰值最大。顶部和肩部出现最大拉应力说明爆炸对拱顶拱肩损伤较大,隧道衬砌结构将会最先在这两处发生破坏。     

电站锅炉系统性能仿真模型的建立

1引言根据热力学第二定律，燃料中的化学拥将近一半损失在锅炉的燃烧与传热过程中。因此，优化锅炉性能对降低整个火电机组的煤耗率具有明显效果。完整的锅炉系统由磨煤机、送风机、一次风机、弓讯机、炉膛、汽包、过热器、再热器、省煤器、空气预热器等单元组成，这些单元之间的联结错综复杂。本文建立了锅炉系统中通用单元的性能模型，并在此基础上，对锅炉系统的结构特点进行了分析，利用过程系统工程中的序贯模块法建立了整个锅炉系统的性能模型。对单元的划分、回路的切断及断裂流股的收敛与迭代策略提出了自己的观点。最后根据生产厂…     

Analysis on nonlinear effect of unsteady percolation in the inhomogeneous shale gas reservoir

The nonlinear effects of unsteady multi-scale shale gas percolation,such as desorption,slippage,diffusion,pressure-dependent viscosity,and compressibility,are investigated by numerical simulation.A new general mathematical model of the problem is built,in which the Gaussian distribution is used to describe the inhomogeneous intrinsic permeability.Based on the Boltzmann transformation,an efficient semi-analytical method is proposed.The problem is then converted into a nonlinear equation in an integral form for the pressure field,and a related explicit iteration scheme is constructed by numerical discretization.The validation examples show that the proposed method has good convergence,and the simulation results also agree well with the results obtained from both numerical and actual data of two vertical fractured test wells in the literature.Desorption,slippage,and diffusion have significant influence on shale gas flows.The accuracy of the usual technique that the product of viscosity and compressibility is approximated as its value at the average formation pressure is examined.     

Achieving High-Performance Pure-Red Electrophosphorescent Iridium(III) Complexes Based on Optimizing Ancillary Ligands

Two new iridium(III) complexes were synthesized by introducing two trifluoromethyl groups into an ancillary ligand to develop pure-red emitters for organic light-emitting diodes (OLEDs). The electron-donating ability of the ancillary ligands is suppressed, owing to the electron-withdrawing nature of trifluoromethyl groups, which can reduce the HOMO energy levels compared with those of compounds without trifluoromethyl groups. However, the introduction of trifluoromethyl groups into the ancillary ligand has little impact on the LUMO energy levels. Therefore, a well-tuned, pure-red, excited-state energy was achieved by regulating the relative energy level between the HOMO and LUMO. OLEDs with these complexes as emitters showed high external quantum efficiencies (EQEs) of 26 % and realized high EQEs of about 25 % and fairly low driving voltages of 3.3–3.6 V for practical luminance of 1000 cd m⁻², as well as excellent Commission Internationale de L'Eclairage (CIE) coordinates of (0.66, 0.33) and (0.67, 0.33); thus, this demonstrates the successful molecular design strategy by modifying the electron-donating ability of ancillary ligand.     

One-Step Generation of Energy-Time-Polarization-Hyper-Entangled W-Class Triphotons: Nonlinear and Linear Optical Responses

Nonclassical multiphoton have attracted extensive attention to serve as entangled resources for quantum information technology. Here, the continuous-mode hyper-entangled W-class triphotons are theoretically generated through spontaneous six-wave mixing (SSWM) in ⁸⁵Rb. In nonlinear optical response, Zeeman sub-states are high-dimensionally quantized by polarized dressing. High-dimensional entanglement is structured via atomic non-Hermitian nature. Through linear optical response, the temporal correlations are shaped via diverse polarized dressing. SSWM-based triphoton is a genuine triphoton possessing non-Gaussian tripartite entanglement. The high production rate is due to co-action of three strong input fields, electromagnetically induced transparency (EIT) protection, and slow light effect. Non-Hermitian nature endows the system with sensitive adjustability around exceptional points (EP). Eventually, the results demonstrate multiple SSWMs causing oscillations with multiple periods in three-photon temporal correlations for the nonlinear region, build a high-dimensional three-body entangled quantum network and transform multifarious profiles of the three-photon temporal correlations for the linear region. Especially, both high-dimensional and hyper entanglements are obtained, contributing to high quantum information capacity. Further, the system is switched among multiple states when non-Hermitian nature is manipulated by polarized dressing. The research opens a broad prospect for generating the hyper-entangled multiphoton with potential application in adjustable quantum networks of high information capacity.     

铂表面甘油脱除羟基的从头算分子动力学研究

随着生物质能源的开发,从生物柴油制备中大量获取的甘油成为热门的工业原材料. 甘油可以通过氢解生成1,2-丙二醇和1,3-丙二醇两种丙二醇,这两种丙二醇都具有十分广泛的用途. 实验上报道的众多相关金属催化剂中,铂具有性质稳定、不易失活、可活化氢分子提供氢原子等优点. 此外甘油在铂上氢解生成1,2-丙二醇的选择性高于1,3-丙二醇. 本文主要利用从头算分子动力学对甘油在Pt(111)和Pt(211)表面上发生的羟基解离过程进行了模拟计算,并对比分析了其自由能的变化和表面物种结构参数的变化,得出了以下结论：(i)密度泛函理论优化气相甘油分子结构的结果显示,氢键对于气相中分子的结构与能量有较大贡献,三个羟基形成三个分子内氢键结构时甘油分子能量最低;(ii)通过比较从头算分子动力学模拟得到的自由能能垒和反应自由能,可以得出,在Pt(111)和Pt(211)表面,末端碳上的羟基比中间碳上的羟基更容易发生解离. 这表明在类似的条件下,铂作为催化剂可以为1,2-丙二醇的生产提供更高的选择性,这与文献中报道的实验结果一致;(iii)通过对从头算分子动力学模拟得到的初始吸附态和过渡态结构参数的分析,发现在羟基解离的过程中,C-C键的键长没有明显变化,而氧原子的相对位置以及氢键的长度有明显变化,且氢键长度的变化更加剧烈;(iv)通过比较从头算分子动力学研究所得的自由能能垒和结构参数的相关趋势发现,自由能能垒与初始吸附态和过渡态的氧原子间位置的变化量之间存在线性关系,而分子内氢键对自由能能垒的贡献可以忽略不计. 氧原子间位置的变化越大,自由能能垒越高.