Directional Modulation Using Frequency Diverse Array For Secure Communications

Wireless Personal Communications - In this paper, to obtain a better physical layer security for wireless communications, a directional modulation (DM) using frequency diverse array (FDA) is...     

MIMO radar OFDM chirp waveform diversity design with sparse modeling and joint optimization

In multiple-input multiple-output radar systems, the employed waveforms should have a large time-bandwidth product, good correlation property and satisfactory ambiguity function performance. This paper proposes a orthogonal frequency division multiplexing (OFDM) chirp waveform diversity design scheme with sparse modeling and joint optimization of the waveform code matrix and amplitude matrix. First, we formulate the waveform diversity design as a mathematical optimization problem with sparse modeling and optimally design a code matrix to select the hopping frequencies for each waveform. Thereafter, the waveform amplitudes are adaptively designed by minimizing the cross-correlation peaks with genetic algorithm. The proposed method can easily generate multiple pseudo-orthogonal waveforms with satisfactory correlation and ambiguity function performance. Additionally, the impacts of waveform number, hopping frequency interval and selectable frequency index are discussed. The superiority of the proposed OFDM chirp waveform design over existing methods is verified by extensive simulation results.     

超高效液相色谱-串联质谱法测定鳗鱼中呋线威和溴氰菊酯残留

建立了同时快速测定鳗鱼中呋线威和溴氰菊酯残留的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法。样品以乙腈为提取剂,经脱脂、浓缩和净化,用流动相溶解,经超高效液相色谱分离,以串联质谱在多反应监测(MRM)模式下测定,在3.2min内完成呋线威和溴氰菊酯的定量分析。结果表明:呋线威和溴氰菊酯的标准曲线在0～10μg/kg浓度范围内线性良好,相关系数(r)分别为0.9998和0.9995;在1、5和10μg/kg添加水平条件下,呋线威和溴氰菊酯的加标回收率分别为83.4%～91.7%和85.6%～95.7%,相对标准偏差(RSD)均小于8%(n=6);本方法对呋线威和溴氰菊酯的定量限分别为0.07μg/kg和0.45μg/kg(S/N≥10)。     

Synthesis and Crystal Structure of N-Benzyl-N'-(2-pyridyl)urea and Its Mononuclear Cu(II) Complex

A new ligand of N-benzyl-N'-(2-pyridyl)urea L and its self-assembly product with CuCl2, [Cu(II)LCl2]∞ 1, have been synthesized and structurally characterized by IR, 1H NMR and single-crystal X-ray diffraction analysis. In the structure of L, the urea groups adopt Z,E conformation to form dimers through intermolecular hydrogen bonds; while in complex 1, it assumes Z,Z conformation to fit for the coordination sphere of the Cu(II) ions. The coordinated units are connected through intermolecular N-H…Cl hydrogen bonds to form an extended 2D framework. Finally, a 3D structure is obtained via π-π stacking interactions between pyridyl rings.     

One-dimensional Coordination Polymers of rctt-1,3-Diphenyl-2,4-bis[2-(5-phenyl)-oxazolyl]cyclobutane with CuCl2 and CoCl2

The Cu(Ⅱ) and Co(Ⅱ) supramolecular coordination polymers,[CuCl2(DPO)-(CH3CN)0.5(CH2Cl2)0.5]n(CuDPO,DPO=rctt-1,3-diphenyl-2,4-bis[2-(5-phenyl)oxazolyl]cyclo-butane) and [CoCl2(DPO)]n(CoDPO),were synthesized and characterized by single-crystal X-ray diffraction method.CuDPO crystallizes in monoclinic,space group P21/n,with a=11.243(5),b=16.070(8),c=19.872(9) ,β=95.678(10)°,Z=4,V=3573(3) 3,C35.50H28.50Cl3CuN2.50O2,Mr=692.00,Dc=1.287 g/cm3,μ=0.868 mm-1,F(000)=1420,S=1.089,(△/σ)max=0.069,the final R=0.0682 and wR=0.1749.CoDPO is of monoclinic,space group P21/n,with a=11.396(4),b=15.151(5),c=17.673(6) ,β=90.528(6)°,Z=4,V=3051.4(17) 3,C34H26Cl2CoN2O2,Mr=624.40,Dc=1.359 g/cm3,μ=0.770 mm-1,F(000)=1284,S=0.981,(△/σ)max=0.001,the final R=0.0471 and wR=0.0961.In each case,the metal cation is coordinated by two Cl anions and two N atoms from oxazole ring of the ligands,which leads to the formation of a one-dimensional polymeric structure.It is found that the cyclobutane ring of coordinated DPO adopts a distorted conformation in the crystal,which is attributed to the increased steric effect between adjacent aryl substituents for the coordination of oxazole ring to metal cation.Thermal gravimetric analysis of the two complexes was also observed.     

Hetero-atom molecular sieves: (XIII) The studies on the structure of Ti-Si pentasil type molecular sieve

In this paper, the structure of titanium-silicon pentasil type molecular sieve which we synthesized is studied with different methods. IR and Laser Raman spectral analyses indicate that the Ti-O-Si vibration occurs in the molecular sieve. It is proved by ESR analyses that Ti⁴⁺ is located in environment of distorted tetrahedron. The study on the surface of Ti-Si pentasil type molecular sieve by XPS further verifies that Ti⁴+ in framework is present in the form of TiO₄ tetrahedron. The results of the electron probe micrograph analyses indicate that Ti enters the framework of molecular sieve. X-ray powder diffractometer exactly determined unit cell parameters of Ti-Si pentasil type molecular sieve. The unit cell volume of Ti-Si zeolite increased with increasing the content of titanium which is consistent with the longer Ti-O distance, compared with the Si-O one.     

K3Sb0.3Y4O8·6H2O新型低温相的水热合成与表征

低温相合成是水热合成化学的重要特征之一［’j，因此，水热合成对低温相功能材料的开发和应用研究有着十分重要的意义．水热晶化法合成的固体电解质材料具有结晶度高、均匀性好等特点，更有利于材料的制备［’－‘j．低温型质子导体在气体传感器和股分离及股反应器方面有着广泛的应用前景，材料体系多含水或羟基化合物．为此，我们以开发新型低温相质子导体为目的，在K。0－Sb。0。－Y。O。－H。O体系中开展了新型低温相的水热合成研究，本文报道了K3Sbo3Y408·6HZO新型低温相的水热合成与表征．1实验方法以分析纯KOH、Y刀。和C。H…     

USY型分子筛与高岭土的水热热压固化及固化体性能研究

应用水热热压技术制备了各种USY型分子筛-高岭土的固化成型体,并对其进行物相分析、表面酸性以及对正十五烷裂解的催化性能测定。实验结果表明:USY型分子筛与高岭土的固化体具有较强的B酸中心,而几乎没有L酸中心。135℃下得到的固化体对n-十五烷的裂解活性及汽油转化率都高于未经处理的样品。水热热压固化温度是影响固化体性能的重要条件,可以利用固化体组分的改变及固化条件的控制来调节固化体表面酸性及其催化性能。     

（Ga,Fe,B）—β沸石的水热合成及其结构研究

用水热晶化法合成了M－β沸石（M－B，Fe,Ga)，讨论了原始反应物焙Na2O和（TEA）2的含量等因素对（B、Fe)- β沸石成及晶粒大小的影响，通过化学分析、X荧光分析、XRD、IR、XPS和SEM对样品进行SiO2/M2O3比例定及结构特性表征，结果表明，合成的M－β沸石晶粒均匀，结晶度高，由于杂原子的掺入，引起Fe2p3/2电子结合能、Fe- β红外光谱和晶胞体积明显变化。     

曙红Y在介孔分子筛MCM-41膜及粉体中的封装及发光性质研究

由于分子筛材料在催化、吸附、气相分离、电极、传感器和光电子器件等方面有着潜在的应用前景[1-3] ,结构有序并且具有良好稳定性的分子筛膜材料的制备受到人们广泛关注［4-6],将一些功能有机分子封装于薄膜中制得具有特殊光学性质的材料具有实际应用价值[7-8] ．在以往的研究中,曙红Y被引入到有机聚合物膜［9]和无机氧化物粉体［10]中并测定了该复合材料的光学性质,但将其引进具有规则孔道结构及狭窄孔分布的无机微孔材料中的研究尚未见报道．本文通过共混方法成功地将曙红Y引入到具有较大孔径及规则孔结构的介孔分子筛MCM－41膜及粉体中,利用X射线粉末衍射和紫外漫