An asymptotic result for the diffraction of plane waves propagating along a cylindrically truncated flat surface

An asymptotic result is obtained for evaluating the diffraction of a plane wave incident along a perfectly conducting fiat surface toward a drop in this surface. This drop is formed with a convex cylinder smoothly joined to the fiat section, thus creating a discontinuity in curvature at the join. The asymptotic result is also useful for analyzing the radiation of a source mounted on the fiat section of the conducting surface. Unlike a previously available solution which still requires a fair amount of numerical evaluation using a hybrid approach combining the moment method with the geometrical theory of diffraction, the computation of this asymptotic result is simple and efficient. Since this result is expressed in the simple format of the geometrical theory of diffraction, it is easily applied to solving more complicated diffraction problems. An application is found in the aperture-matched horn designs.     

有限频率选择表面电磁散射特性的分析方法

针对有限频率选择表面的电磁散射特性难以用一般方法进行分析的难题 ,提出了两种行之有效的适合不同情况的高效处理方法 :谱域伽略金法和基于平面波谱 (PWS)分解逼近的方法 ,大大节约了CPU的计算时间和内存空间。     

Degradation induced variation of LC transition of poly(n-undecyl isocyanate)

The first-order thermal transitions including side-chain melting, crystal-LC, biphasic chimney-like, and isotropic transitions of poly(n-undecyl isocyanate) (PUDIC) were investigated by varying its thermal history. After annealing at 140 °C for different periods of time, it leads to different degrees of backbiting degradation into n-undecyl isocyanurate trimer which behaves as a solvent for the rest non-degraded/rigid PUDIC to change into a lyotropic LC from thermotropic transition. Based on the degree of degradation, various amounts of trimers are present and the PUDIC demonstrates different types of thermal transitions found in DSC thermograms due to the variation of the non-degraded PUDIC concentration in solvent trimers. Finally, a phase diagram includes all types of crystallines, LC, and isotropic regions can be drawn according to the DSC thermograms.     

基于多软件融合方法的真核生物基因启动子预测

基于多个软件的预测结果,提出了一种融合方法(ComPromoter)提高真核生物基因启动子的预测精度.ComPromoter以ProKey、FirstEF和Eponine等软件对启动子的预测结果为基础,融合了可用于启动子识别的多个特征(包括ProKey预测结果中真阳性和假阳性的出现频率随投票距离以及预测分值变化的统计特征),并利用支持向量机构建了启动子预测模型.在人类ENCODE区域测试数据集上测试的结果显示,ComPromoter的Pearson相关系数CC值高于所融合的单个启动子预测软件.     

A 2.4-GHz printed meander-line antenna for USB WLAN with notebook-PC housing

A 2.4-GHz meander-line antenna printed on a USB-WLAN card is presented for WLAN applications. The HFSS 3-D EM simulator is employed for design simulation. The printed meander-line antenna is realized on a FR-4 PCB substrate. The measured VSWR is less than 2 from 2.4 to 2.5 GHz. Besides different orientations, the meander-line antenna printed on a simulated USB-WLAN card was attached to the side wall of a notebook-PC to investigate the PC housing effects on the antenna radiation patterns.     

The effect of F substitution on the magnetic properties of Nd−Fe−B based compounds

Various efforts are currently undertaken to raise the relatively low Curie temperature of the otherwise promising Nd?Fe?B type permanent magnet material. The substitution of Fe by several elements was found to increaseT _c, which, on the other hand, can be accompanied by a reduction of the magnetocrystalline anistropy. In the present paper a systematic Mössbauer study was carried out, using Co, Ni, Al, Si and Ga as substituents. The specific influence of each element upon the magnetic properties is attributed to its preference for entering a certain Fe lattice site. Simple atomic size considerations are proved to be insufficient for explaining the preferred occupation observed experimentally. Obviously the local electronic structure has to be studied more carefully. Finally, the interplay between magnetism and metallurgy (particularly the formation of precipitations), is found to be of some importance.     

Étude sur les familles normales et les familles quasi-normales de fonctions méromorphes

Rendiconti del Circolo Matematico di Palermo Series 1 -     

Structural variations in novel silver(I) complexes with bitopic pyrazole/n-heterocyclic carbene ligands

The synthesis and structural characterization of several new silver complexes of L (L = a bidendate ligand of pyrazole and N-heterocyclic carbene) are described. The result shows that the choice of counterions, N-substitutions of L, and reaction conditions are crucial which lead to a variety of structural motifs, including novel metallomacrocycles [Ag2(mu-L)2]2+ with or without Ag...Ag close contact, a mononuclear [AgL2]+ complex, and a [LAg(NO3)]n coordination polymer. In particular, the nonbonding Ag...Ag distance and the overall geometry of the metallomacrocycles are controllable with different N-substitutions and counterions. All these complexes have been determined by X-ray diffraction. The solid-state aggregates are retained in solution as supported by the electrospray mass spectroscopic studies.     

A mixed metal phosphate incorporating isonicotinate ligand: synthesis, crystal structure, and magnetic properties of Cu(HINT)(VO2)(PO4)

A mixed metal phosphate incorporating isonicotinate ligand, Cu(HINT)(VO₂)(PO₄), was hydrothermally synthesized and characterized by single-crystal X-ray diffraction and magnetic susceptibility. This compound crystallizes in the monoclinic space group C2/c with cell parameters a=22.033(1) Å, b=6.2986(3) Å, c=16.0202(9) Å, β=121.001(1), and Z=8. The structure consists of two-dimensional neutral sheets of CuVO₂(PO₄) with the dipolar isonicotinate ligand being coordinated to Cu ions as a pendent group. Adjacent sheets are connected by hydrogen bonding. Each sheet consists of infinite chains of CuO₆ octahedra sharing trans edges which are connected by double chains of vanadyl(V) phosphate via corner sharing. Magnetic study results indicate the presence of intrachain ferromagnetic coupling between Cu ions. The magnetic exchange parameter was estimated as 2J/k =51.83 K based on an S=1/2 equally spaced ferromagnetic chain model.     

Kondo effect in the presence of magnetic impurities

We measure transport through gold grain quantum dots fabricated using electromigration, with magnetic impurities in the leads. A Kondo interaction is observed between dot and leads, but the presence of magnetic impurities results in a gate-dependent zero-bias conductance peak that is split due to a RKKY interaction between the spin of the dot and the static spins of the impurities. A magnetic field restores the single Kondo peak in the case of an antiferromagnetic RKKY interaction. This system provides a new platform to study Kondo and RKKY interactions in metals at the level of a single spin.