基于加权平滑l_0范数的单快拍波达方向估计

针对现有基于压缩感知的DOA估计算法估计精度不高的问题,提出一种基于加权平滑l0范数的单快拍DOA估计算法。所提算法采用一种新的加权方式,在构造一个恰当的平滑连续函数后,根据接收数据的初始解确定一个合适的递减的{σ}序列[σ_1,σ_2,?,σ_J],并对每一个σ值,用最速下降法来求解l0范数的逼近函数H_σ(S)的最小值;然后将该σ值作为下一次迭代的初始值,并在每次迭代开始时更新权值,通过多次的迭代获得逼近函数的最小解,即逼近的最小l0范数。通过仿真实验表明所提算法可对DOA进行有效估计,且容易实现、精度较高,与未加权的改进平滑l_0范数DOA估计方法相比具有更好的估计性能。     

电感耦合等离子体发射光谱法测定锆材中的铪、铁、铬

建立了电感耦合等离子体发射光谱法(ICP-AES)同时测定锆材中铪、铁、铬元素含量的方法。样品用硝酸-氢氟酸溶解,探讨了基体锆对元素铪、铁、铬以及铪、铁、铬相互之间的干扰情况,确定了铪、铁、铬元素最佳分析谱线分别为264.141nm,238.204nm,267.716nm。线性相关系数r≥0.9999,加标回收率均为95%~105%,铪、铁、铬的相对标准偏差小于3%(n=11)。该方法简便、快速、准确,满足锆材日常生产的检测要求。     

硼铁合金中硼、硅、铝含量分析方法的研究

通过对硼铁合金中硼、硅和铝含量分析方法的研究,开展了试样溶解(熔融)条件的选择、仪器工作条件的确定、校准曲线的选择和干扰元素的消除等条件实验;进行了对照实验、准确度和精密度等实验,本法采用碱熔融分解试样,选用铁基体加入标准溶液为校准曲线,在不需要加入内标元素的条件下,可以直接应用电感耦合等离子体原子发射光谱分析技术测定硼铁合金中硼、硅和铝的含量;本法试剂加入少,操作简便,可实用于生产检验,相对标准偏差为0.5%~5.0%。     

Composite iterative learning controller design for gradually varying references with applications in an AFM system简

Learning control for gradually varying references in iteration domain was considered in this research, and a composite iterative learning control strategy was proposed to enable a plant to track unknown iteration-dependent trajectories. Specifically, by decoupling the current reference into the desired trajectory of the last trial and a disturbance signal with small magnitude, the learning and feedback parts were designed respectively to ensure fine tracking performance. After some theoretical analysis, the judging condition on whether the composite iterative learning control approach achieves better control results than pure feedback contro! was obtained for varying references. The convergence property of the closed-loop system was rigorously studied and the saturation problem was also addressed in the controller. The designed composite iterative learning control strategy is successfully employed in an atomic force microscope system, with both simulation and experimental results clearly demonstrating its superior performance.     

普通高校国防教育规范化建设刍议

国防教育是全民国防教育的基础,是高校思想政治教育的重要内容之一。高校国防教育通过军事技能训练、军事理论教学、日常国防教育活动、国防教育选修课等方式加强大学生的国防意识,分析了高校国防教育在规范化建设中存在的一些问题,探讨解决对策,以便有利于推进国防教育的可持续发展,促进国防教育实践的深入开展。     

两亲嵌段共聚物(聚苯乙烯-b-聚己内酯)的合成与表征

采用原子转移自由基聚合法合成聚苯乙烯,经过四氢铝锂还原,制得单羟基封端的聚苯乙烯.与己内酯进行开环反应制备AB型两亲性嵌段共聚物(聚苯乙烯-b-聚己内酯),并通过凝胶渗透色谱和红外光谱对聚合物进行了结构表征.研究表明,将此两亲性嵌段聚合物加入到环氧树脂/甲基四氢苯酐固化剂混合体系中,经过反应诱导相分离发现,该嵌段在环氧基体中发生微观相分离,相分离尺寸控制在纳米尺度,可以作为环氧改性剂使用.     

Numerical simulation of atomic layer deposition for thin deposit formation in a mesoporous substrate

ZnO deposition in porous γ-Al₂O₃ via atomic layer deposition (ALD) is the critical first step for the fabrication of zeolitic imidazolate framework membranes using the ligand-induced perm-selectivation process (Science, 361 (2018), 1008–1011). A detailed computational fluid dynamics (CFD) model of the ALD reactor is developed using a finite-volume-based code and validated. It accounts for the transport processes within the feeding system and reaction chamber. The simulated precursor spatiotemporal profiles assuming no ALD reaction were used as boundary conditions in modeling diethylzinc reaction/diffusion in porous γ-Al₂O₃, the predictions of which agreed with experimental electron microscopy measurements. Further simulations confirmed that the present deposition flux is much less than the upper limit of flux, below which the decoupling of reactor/substrate is an accurate assumption. The modeling approach demonstrated here allows for the design of ALD processes for thin-film membrane formation including the synthesis of metal–organic framework membranes.     

Atomic layer deposition of GDC cathodic functional thin films for oxide ion incorporation enhancement

In this paper, we report successful fabrication of a gadolinia-doped ceria (GDC) thin film using atomic layer deposition (ALD) for improving the performance of solid oxide fuel cells (SOFCs). By varying the deposition conditions and adjusting the configuration of the ALD supercycle, the doping ratio of ALD GDC was controlled. The morphology, crystallinity, and chemical composition of ALD GDC thin films were analyzed. ALD GDC showed different surface chemistry, including oxidation states, at different doping ratios. The application of ALD GDC in a SOFC led to an output power density enhancement greater than 2.5 times. With an anodic aluminum oxide (AAO) porous support structure, an ALD GDC thin film SOFC (TF-SOFC) showed a high power density of 288.24 mW/cm² at an operating temperature of 450°C.     

321不锈钢钝化膜孔蚀破坏的原子吸收光谱研究

采用原子吸收光谱方法测定不锈钢局部破坏后各种元素的析出量，研究了３２１不锈钢在ＮａＣｌ水不溶液中钝化膜孔蚀破坏的特征。研究结果表明：ＡＡＳ可有效地用于不锈钢孔蚀动力学的研究。     

交变电场下不锈钢的电化学行为

主要研究了交变电场下SS304不锈钢在2.5 mol/L硫酸 溶液中的表面成膜情况.运用电位阶跃研究了不锈钢在交变电场高电位、低电位下的电化学 反应；用AFM准现场地观察了不锈钢在交变电场下各个阶段的成膜状况；用XPS分析了膜层的 纵向组成结构.结果表明：交变电场下不锈钢表面钝化膜的生长机制不同于直流钝化.最后 分析了不锈钢在交变电场下的电化学反应和成膜机理.