Coherent aperture synthesis by an incoherent signal

The procedure of aperture synthesis by an incoherent source during displacement of the receiving system in space is considered. The advantages of the method are the possibility of aperture synthesis with the help of antenna arrays consisting of two receivers and its applicability to both the source of a quasimonochromatic signal and that possessing a continuous spectrum. The method is applicable with the same limitations as the known methods using the procedures of signal phasing. The results of mathematical simulation of the synthesis upon location of two sources with close frequencies at different distances and in the presence of noise, as well as the results of the in situ experiment with a reverberation interference, are given. The algorithm for decreasing the time of aperture synthesis without resolution deterioration is proposed and tested in situ.     

整体煤气化联合循环(IGCC)系统整体综合优化

本文提出ＩＧＣＣ系统两层次和联合循环两大块交叉迭代的整体综合优化的新思路和新方法,对大型ＩＧＣＣ电站系统进行模块化建模和模拟分析,总结和揭示了ＩＧＣＣ系统综合优化的规律,得出了许多有实用参考价值的结论．     

Approaches for introducing high molecular diversity in scaffolds: Fast parallel synthesis of highly substituted 1H-quinolin-4-one libraries

We have developed a two steps strategy for the parallel synthesis of highly diversified quinolin-ones. In the first step we have combined and improved different synthetic methods for generating quinolin-4-ones bearing four different substitutions at specific positions using round bottomed flasks. The synthesis was assessed for a large number of substituted quinolin-4-ones. In the second step, the improved method was adapted to a parallel array synthesis using a 12 positions carrousel as demonstrated for the synthesis of 42-variable quinolin-4-ones. The first combinatorial library set 14(a-x) was obtained with a chemical purity of more than 95% without purification, the second library set 15(a-r), which included two synthetic steps, needed combinatorial purification using an innovative parallel purifier. The proposed approach contributes to a more extensive diversification of molecular scaffolds in general and provides access to highly substituted quinolinones in particular.     

在Fourier综合中使用Sim权的探讨

应用直接法程序系统MULTAN-78或者MULTAN-80解晶体结构,通常是在直接法找到部分原子位置后,用加权Fourier综合逼近,获得余下的原子位置。本文通过两个实例证明,当大部份原子已知时,尤其是结构含有重原子时,用不加权Fourier逼近比使用加权Fourier逼近更为有效。作者修改了MULTAN-80程序,使之增加了不加权Fourier综合的功能。 关键词：     

全固态快沿脉冲源功率合成的设计与分析

全固态快沿脉冲源具有小型化、高稳定性、高重复频率、输出功率低等特点,为了克服单个脉冲源输出功率低的问题,利用ADS仿真软件建立了多节蛇形微带线结构的功率合成器,并用实验验证了功率合成的效果。利用两路高稳定度的脉冲子源作为功率合成的两路输入,通过该功率合成器使两路快沿双指数信号合成为一路快沿双指数信号,实现了功率的提高。实验中脉冲子源的幅度为1.1kV,前沿约为2ns,脉冲宽度为10ns;两路信号合成后,输出电压为1.6kV,前沿约为2ns,脉冲宽度为18ns。实验验证了该功率合成模块的可行性,该合成模块还可推广至多路的脉冲子源的功率合成,实现提高快沿双指数脉冲功率的目的。     

Comparative study on graphene growth mechanism using Ni films,Ni/Mo sheets,and Pt substrates

We demonstrate a comparative study on graphene growth mechanism using various catalytic metal substrates such as Ni thin films, Ni-deposited Mo (Ni/Mo) sheets, and Pt sheets during chemical vapor deposition (CVD). Depending on the substrates, two kinds of graphene growth mechanisms that involve either precipitation or surface adsorption of carbon have been reported. We synthesized graphene, focusing especially on the initial growth stage during CVD, by varying synthesis parameters such as synthesis time, amount of feedstock, and cooling rate after synthesis. We concluded that precipitation-driven synthesis is dominant in the case of Ni substrates whereas adsorption-driven growth is dominant in the Ni/Mo system. In the case of the Pt substrate, which is generally believed to grow by carbon precipitation, graphene growth by adsorption was found to be dominant. We believe that our results will contribute to a clearer understanding of the graphene synthesis mechanism, and development of manufacturing routes for controllable synthesis of high-quality graphenes.     

Analysis and synthesis of fractal antenna radiation patterns

A problem of fractal antenna radiation pattern synthesis is considered. The problem of synthesis of fractal antenna radiation patterns is solved for two kinds of antennas (discrete and linear) in one- and two- dimensional cases. With the use of the theory of fractal synthesis, new modes with new properties are obtained in fractal electrodynamics. Fractal radiation pattern synthesis was conducted by means of the Weierstrass function.     

欠阻尼振动的合成实验研究

本文利用ＪＧＹＷ－２型双单摆振动示波装置研究和探讨了两个相互垂直方向同频率欠阻尼振动的合成和两个同方向频率相近的欠阻尼振动的合成．通过实验观察和理论分析，得到了欠阻尼振动合成的部分图形和表达式，揭示了等角螺线的物理意义．     

Comparison between ZnO nanowires grown by chemical vapor deposition and hydrothermal synthesis

Vertically aligned zinc oxide nanowires (NWs) were synthesized by two different techniques: chemical vapor deposition (CVD) and hydrothermal synthesis. To compare the effects of different growth conditions, both F-doped SnO₂ (FTO) coated-glass and silicon wafers were used as substrates. Before NWs growth, all the substrates were covered with a ZnO seed layer film obtained with the same procedure, which acts as nucleation site for the subsequent growth of the nanowires both during CVD and hydrothermal synthesis. We studied the influence of the two synthesis techniques and the growth duration on the final morphology, orientation, and density of the ZnO NWs using electron microscopy and X-ray diffraction, while the NWs optical quality was addressed by UV–Vis spectroscopy. By discussing advantages and disadvantages of both synthesis methods, we finally show that the application purpose often drives the choice of the NWs growth process and the substrate to be used.     

固体酸催化剂及分子筛晶化过程的核磁共振研究

介绍了一些常规固体核磁共振的技术的发展状况, 并综述了固体核磁共振在多孔材料中的应用情况, 其中包括沸石分子筛酸性和结构表征以及目前在分子筛合成机理研究中的应用进展. 本文的主要内容是利用固体核磁共振结合其它表征技术研究了一类介孔固体酸催化材料的酸性以及两种微孔磷铝分子筛的合成晶化过程.  利用有机聚合物为模板剂合成出两种介孔复合氧化物MoO_x/ZrO₂与WOx/ZrO₂固体酸材料. 并对其进行了物理化学性质的表征. 研究发现它们在较高的焙烧温度下仍保持有较高的比表面积及规整的孔径. 利用固体核磁共振技术及DFT计算的方法发现在介孔WO_x/ZrO₂及MoO_x/ZrO₂表面存在两种类型的Br[AKo¨D]nsted酸位, 其酸强度强于传统的HZSM-5分子筛, 与典型的固体强酸硫酸锆相当, 但弱于100％的硫酸. 借助于理论计算清楚地揭示了酸性位的具体结构和酸强度信息, 且计算结果与实验结果符合得非常好. 除了弱酸性的Zr-OH基团外, 在介孔氧化锆表面存在大量的Lewis酸位（配位不饱和的Zr⁴⁺）. 在引入Mo或W物种后, Mo-OH或W-OH与不饱和的Zr⁴⁺配位产生作为Br[AKo¨D]nsted酸位的桥式Mo-OH-Zr(或W-OH-Zr)羟基, 并且导致氧化锆表面Lewis酸位的大量减少. 利用理论计算证实了单聚或多聚体形式的桥式Mo-OH-Zr(或W-OH-Zr)羟基是强Br[AKo¨D]nsted酸性位产生的根源, 同时提出了酸性位形成的机理. 利用水热晶化法合成了AlPO₄-5和MgAPO-36两种具有重要工业潜在应用价值的分子筛材料并用固体核磁共振技术结合X射线衍射、傅里叶红外、高分辨电子显微镜等技术研究了它们的详细晶化过程. 研究发现在HF存在条件下加热120 min后具有AFI类型的骨架晶化开始. 此时³¹P NMR谱中在δ -22与 δ -29处出现两个来源于骨架P-O-Al单元的信号, ¹⁹F NMR谱中在 δ -120处出现来源于骨架F-Al_pen-O-P单元的信号, 证实了晶体骨架开始形成. 另外, 凝胶中五配位Al（F-Al_pen-O-P）的出现是分子筛晶化开始的另一个标志. 利用²⁷Al→³¹P HETCOR、 ³¹P{²⁷Al} TRAPDOR及¹H→³¹P CP/MAS等双共振实验详细研究了初始凝胶相及晶化开始时凝胶相的结构, 在120 min加热凝胶中区分出具有不同化学环境的配位P原子, 提出了详细的晶化过程机理.  对于另一种具有高活性的镁取代的MgAPO-36分子筛催化材料, XRD发现在第二阶段423 K时, 加热1.5 h后骨架晶化开始. ³¹P NMR证实此时凝胶相中形成了P-O-Al及Mg-O-P骨架单元, 此后（2 h）凝胶相中出现半晶相的棒状颗粒. 并最终晶化为不规则球状的MgAPO 36晶体（18 h后）. 利用²⁷Al→³¹P HETCOR及¹H→³¹P CP/MAS分析了中间凝胶相的微观结构并利用³¹P{²⁷Al} TRAPDOR NMR技术研究骨架晶化开始时凝胶相中P(nAl) (n=1~4)的配位结构, 得出了5种具有不同配位状态的微观化学环境, 提出了详细的晶化过程机理.     

Enhancement of the synthesis efficiency of carbon cluster ions by the irradiation of two laser pulses to polymers in vacuum

We investigated the effect of the pre-irradiation of a polymer target in vacuum, using a low-fluence laser pulse, on the synthesis efficiency of carbon cluster ions ejected by laser ablation. A polymer target was irradiated by two laser pulses. The first laser was used for the pre-irradiation, and the second laser was used for ablation. The masses of the ions in the ablation plume were analyzed by time-of-flight mass spectrometry. It was found that the synthesis efficiency of carbon cluster ions was enhanced by the pre-irradiation. The effects of the fluence of the pre-irradiation, the wavelengths of the lasers, and the interval between the oscillations of the two laser pulses on the enhancement of the cluster synthesis are reported. PACS 52.38.Mf; 81.07.-b; 36.40.-c; 61.46.+w     

Composition-Controlled Laser-Induced Alloying of Colloidal Au–Cu Hetero Nanoparticles

Due to their optical properties (localized surface plasmon resonance, LSPR), colloidally dispersed metal nanoparticles are well suited for selective heating by high-energy laser radiation above their melting point without being limited by the boiling point of the solvent, which represents an excellent complement to wet-chemical nanoparticle synthesis. By combining wet-chemical synthesis and postsynthesis laser treatment, the advantages of both methods can be used to specifically control the properties of nanoparticles. Especially in the colloidal synthesis of nanoalloys consisting of two or more metals with different redox potentials, wet-chemical synthesis quickly reaches its limits in terms of composition control and homogeneity. For this reason, the direct synthesis path is divided into two parts to take the strengths of both methods. After preparing Au–Cu hetero nanoparticles by wet-chemical synthesis, nanoalloys with previous adjusted composition can be formed by postsynthesis laser treatment. The formation of these nanoalloys can be followed by different characterization methods, such as transmission electron microscopy (TEM), where the fusion of both metal domains and the formation of spherical and homogeneous Au–Cu nanoparticles can be observed. Moreover, the alloy formation can be followed by different shifts of X-ray diffraction (XRD) reflections and LSPR maxima depending on the composition.     

Aging of starting solutions for nanoparticles synthesis with two different ultrasonication

Novel concept of aging starting solutions for nanoparticle synthesis and the application of two different sonication to aging is introduced. In sonoprocess of nanoparticles from liquid phase, it is usual to irradiate ultrasound to a reacting solution during synthesis. In this work, ultrasound is applied to a starting solution before synthesis. In case of the SiO₂ sphere synthesis, the aging process elongated the induction period of the precipitation, enlarge the sphere size, and enhanced the monodispersity of silica spheres. These effects were promoted by soft sonication at subtle power (~1 mW). In case of the TiO₂ sphere case, ordinary (cavitating) ultrasound during synthesis was found to be effective in more spherical shape. Also, the sonication to aging of the starting solution was useful for uniform spheres synthesis. Existence of miscible liquid such as water-ethanol and feasible relationship to the nucleation of nanoparticles are discussed.     

高功率速调管双管功率合成可行性与技术方案研究

对由两支500kW高功率速调管功率合成得到1MW长脉冲低混杂波(LHCD)微波源的可行性进行了分析,并设计了双管功率合成的方案。在HL-2A装置低杂波实验平台上,利用兆瓦级功率合成器,结合相位反馈技术,对两支高功率速调管、四路250kW进行相干微波功率合成,从而得到1MW LHCD微波。经过可行性分析得到,双管相位偏离15^o时合成效率下降约1.8%,幅度偏差10%时合成效率下降约0.1%。由此可得到双管功率合成技术的具体实施方案。     

基于MATLABGUI的拍频实现方法的研究

在对简谐振动合成“拍”现象理论分析的基础上,介绍了一种基于MatlabGUI的拍频合成方法,并有针对性的设计了Matlab程序,输入一些基本的设计参数,即可获得两个或多个简谐振动合成“拍”现象的图形.     

Multiplexed Optical Fiber Interferometric Sensor System by Synthesis of Optical Coherence Function with Phase Generated Carrier

A novel system for multiplexed optical fiber interferometric sensors is proposed applying the synthesis of optical coherence function with phase generated carriers. The ideal parameters of the laser diode frequency modulation for the phase generated carrier with the synthesis of the optical coherence function are discussed. A basic experimental setup including two interferometric sensors is constructed. The results show that the phase signal from the two sensors can successfully be demultiplexed by scanning the synthesized coherence peak.     

α-FeOOH纳米微粒的凝胶网格沉淀法制备及光谱性质

作为环境矿物材料的羟基氧化铁(FeOOH),可吸附和共沉淀环境介质中的污染物质,其去污能力与产物形貌结构、界面特性及制备方法等密切相关.FeOOH常由水解中和或空气氧化法制备,但其产物颗粒间易凝聚.文章报道了制备针铁矿(α-FeOOH)纳米微粒的一种新颖方法,即凝胶网格沉淀法,它以FeCl3为反应铁盐;明胶为反应介质,可避免沉淀颗粒凝聚成闭.与共沉淀方法比较.它可制得分散均匀、大小均一的α-FeOOH纳米微粒;同时,利用光谱分析手段考察了明胶含量和FeCl3浓度对产物结晶度、颗粒形貌及粒径的影响,结果表明,其他条件一致时,在适宜的明胶含量(12%)和FeCl3浓度(0.6 mol.L1)下所制备的α-FeOOH颗粒分散性最好,为短棒状纳米晶体,颗粒轴跃约110 nm,直径平均约为35 nm,可见,该法合成α-FeOOH的颗粒形貌、大小与凝胶网格结构有关.     

A real decoupled method and free interface component mode synthesis methods for generally damped systems

This paper reports on the development of a new transformation method. In contrast to most existing mode transformation methods in which the first-order state-space equation of the damped vibration system is transformed into a decoupled form with complex coefficient matrices, using the decoupled method presented in this paper, the equation of the damped system can be decomposed into a decoupled equation with real coefficient matrices. Two new free interface component mode synthesis methods are also presented. The equivalent full-mode matrix of the damped structure is used to capture the effects of the higher-order modes. Additionally, this work modifies the compatibility conditions at the junctions that are employed in most of the previous component mode synthesis methods for generally damped systems. The first component mode synthesis method is performed in complex space, whereas the second method can be applied in real space. Because the coefficient matrices of the coupled equation constructed by the second component mode synthesis method are all real-valued, the solution of the eigenproblem for this coupled equation can be performed in real space as well. Additionally, numerical examples demonstrate the accuracy and validity of these two component mode synthesis methods.     

Solid-phase total synthesis of (–)-Phenylhistine and (–)-Aurantiamine. Synthesis of a diverse dehydro-2,5-diketopiperazine library. Part II

The preparation of solid supported glycine phosphonate and its utilization for the total synthesis of two natural products is presented. The proposed protocol combines diversity with accessibility and speed, which makes this scaffold suitable for automated parallel synthesis and combinatorial chemistry. The preparation of a small library of dehydro-2,5-diketopiperazines, combining several natural amino acids with diverse heterocycles (including thiazoles, pyridines, indoles and imidazoles), is also demonstrated.