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991.
R. S. Chen Z. B. Ye Edward K. N. Yung K. F. Tsang 《International Journal of Infrared and Millimeter Waves》2003,24(8):1325-1339
A gradient optimization technique along with a definition of cost function is applied to the CAD of the circulator with a magnetized ferrite sphere for millimeter wave communications. A three-dimensional Finite-Difference Time-Domain (FDTD) approach for the analysis of this ferrite sphere based microstrip circulator is presented. The topology of the structure is enforced at each step of optimization and its physical dimensions are used as optimization variables. The cost function is defined using location of zeros and poles of the circulator's transmission, isolation, and reflection functions. Numerical tests show that the optimization process converges from an arbitrarily selected starting point with the new definition of the cost function. 相似文献
992.
Journal of Nanoparticle Research - 相似文献
993.
Chun‐Guey Wu Hung‐Chieh Lu Liang‐Nien Chen Yung‐Chou Lin 《Journal of polymer science. Part A, Polymer chemistry》2008,46(5):1586-1597
Two new 1,10‐phenanthroline (Phen) containing conjugated oligomers, oligo‐3,8‐bis(4‐octylthiophene‐2‐yl)‐1,10‐phenanthroline) (PDTPh) and oligo‐3,8‐bis‐(4‐octyl‐5‐(4‐ctylthiophene‐2‐yl)thiophene‐2‐yl)‐1,10‐phenanthroline) (PTTPh), as well as their corresponding monomers (OTPhOT and OTOTPhOTOT) were prepared and their metal ion‐sensing properties were investigated. The oligomers showed high thermal stability, good proccessibility, and gave varied color when reacted with different metal ions. Oligomers also showed distinct responses toward metal ions when compared with their corresponding monomers, suggesting that the ionochromic responses were determined by not only the coordinating ability of Phen unit but also the conformation of oligomer chains. Moreover, the differences in the ion‐sensing behaviors between OTPhOT and OTOTPhOTOT also suggested that the coordination ability of Phen depends on its substituents. The oligo‐alkylthiophene moieties in PDTPh and PTTPh acted as spacers to reorganize the conformation of the oligomer chains, as well as the electron donating groups to adjust the coordination ability of the Phen. These findings provide a clue for designing Phen‐containing ion‐sensors for specified ion‐sensing applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1586–1597, 2008 相似文献
994.
Dung-Shing Hung Chen S. Tsai Chin-Chung Yu Yung Liou Shang-Fan Lee Po-Chieh Chiang Chih-Sung Ho Yeong-Der Yao 《Journal of magnetism and magnetic materials》2006
In this study, Fe/Ag/Fe/Ag ferromagnetic structures were epitaxially grown on a GaAs(1 0 0) substrate. Using the Network Analyzer (Agilent 8510C), FMR (ferromagnetic resonant) signals were observed in samples as the in-plane magnetic field was applied to either hard- or easy-axes. Of interest was that our sample demonstrated a FMR-switching behavior in hard-axis but not in easy-axis. The detecting data showed that the switch magnetic field was much smaller than what has been stated previously in Fe/Cu/Fe systems by other laboratories. In addition to the frequency switch in FMR, we also observed a magnetic reversal behavior in its M–H curve. Data presented that both of the FMR and magnetic reverse took place in the same direction (hard-axis). 相似文献
995.
996.
Albert A. Carr Mark W. Dudley Edward W. Huber John M. Kane Francis P. Miller 《Journal of heterocyclic chemistry》1987,24(1):239-241
A series of di-, tri-, tetra- and pentapeptide analogs of leucine-enkephalin have been prepared in which the initial tyrosinylglycine fragment has been replaced by the 5,6-dihydro-5,5-dimethyl-2-oxo-3-phenyl-1(2H)-pyrazineacetic acid moiety. 相似文献
997.
W.E. Billups Long-Jin Lin Benny E. Arney Wayne A. Rodin Edward W. Casserly 《Tetrahedron letters》1984,25(36):3935-3938
Treatment of 1-bromo-2,2-dichloro(trimethylsilyl)cyclopropane (2) with tetra--butylammonium fluoride in tetrahydrofuran yields 1-bromo-2-chlorocyclopropene (1). 1H-Cyclopropa[b]phenanthrene (3) can be prepared by aromatization of the Diels-Alder adduct of 1 and 1,2-dimethylene-3,5,6,7,8,9-hexahydronaphthalene (6) using DDQ followed by potassium -butoxide in tetrahydrofuran. 相似文献
998.
Peter J. Mills Peter F. Green Christopher J. Palmstrm James W. Mayer Edward J. Kramer 《Journal of Polymer Science.Polymer Physics》1986,24(1):1-9
Forward recoil spectrometry is shown to be a useful technique for measuring diffusion of d-polymer chains in h-polymer melts. Concentration profiles of a deuterated diffusing species may be determined with a depth resolution of 80 nm and a sensitivity of 0.1 vol % d-polymer in h-polymer. Consequently diffusion coefficients as small as 10?16 cm2/s can be readily measured. If polymer chains diffuse by a reptation mechanism, the concentration profile ø(x) of diffusing polydisperse polymer should be quite different from øm(x), the Fickian solution, which one obtains for monodisperse polymer. This idea was tested by measuring ø(x) of polydisperse d-polystyrene (d-PS) diffusing into h-PS. The results are in excellent agreement with the ø(x) predicted from the reptation model and the experimentally determined molecular weight distribution. 相似文献
999.
Carmen W. Huie Edward S. Yeung 《Spectrochimica Acta Part B: Atomic Spectroscopy》1985,40(9):1255-1258
Spatial mapping of sodium dimers and sodium atoms produced in a laser-generated plume is reported. The distributions support a sputtering mechanism for atom production. 相似文献
1000.
Edward Witten 《Physics letters. [Part B]》1985,155(3):151-155
Compactification of ten-dimensional supergravity on Calabi-Yau manifolds (as recently proposed by Candelas, Horowitz, Strominger, and the author) gives n=1 supergravity theories in four dimensions. This paper is devoted to working out the Kähler potential and superpotential which arise. 相似文献