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181.
Billye Cheek Mieczyslaw Dabkowski Amr El Nagdi Louis R. Hunt T. P. LaFaveJr Ke Liu Duncan L. MacFarlane Viswanath Ramakrishna 《Acta Appl Math》2012,118(1):107-123
In this work, we consider design questions for an active optical lattice filter, which is being manufactured at the University
of Texas at Dallas, and which has proven to be useful in the signal processing task of RF channelization. The filter can be
described by a linear, discrete time state space model. The controlling agents, the gains, are embedded in the matrices intervening
in this state space model. Consequently, techniques from linear feedback control theory do not apply. We concentrate on the
question of finding real valued gains so that the A matrix of the state space model has a prescribed characteristic polynomial. We find that three of the coefficients can be
arbitrarily picked, but that the remaining are constrained by these and the other system parameters. Our techniques use methods
from constructive algebraic geometry. 相似文献
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[reaction: see text] Catalytic carbonylation of epoxides to beta-lactones was effected by a highly active and selective bimetallic catalyst comprised of a chromium(III) porphyrin cation and a cobalt tetracarbonyl anion. The complex is readily synthesized from commercially available compounds in high yield. Carbonylation of numerous linear epoxides, as well as bicyclic epoxides derived from 8- and 12-membered hydrocarbons, proceeded with high activity, selectivity, and yield. 相似文献
185.
Diphenylamine, barium diphenylamine sulphonate, N-phenylanthranilic acid and 2-nitrodiphenylamine have been investigated as reversible indicators for the titration of antimony(III) with cerium(IV) sulphate in 0.5–2 M sulphuric acid medium. Diphenylamine is the most satisfactory in titrations of antimony(III) in chloride-free solutions, e.g. of potassium antimonyl tartrate. Even low chloride concentrations affect the indicator action of N-phenyl-anthranilic acid or 2-nitrodiphenylamine, but diphenylamine is satisfactory in 1 M hydrochloric acid media. Iodine catalyst is necessary to accelerate the reduction of the oxidized indicator by antimony(III). The indicator colour change is vivid and the colour of the oxidized indicator is stable. Titrations of antimony(III) in mixtures with iron(II) and arsenic(III) are also considered. 相似文献
186.
Thermal degradation of poly(2,2,-propane-bis-4-phenyl carbonate) or bisphenol A polycarbonate (PC) alone and in presence of metal oxide as additives have been discussed. Thermal degradation of PC in presence of metal oxide additives may be surface induced catalytic thermo-oxidative degradation. Some metal oxides retard thermo-oxidative degradation of PC.Thanks are due to RSIC, Nagpur University for recording TG curves, Mr. S. S. Umare for his help during the work and the Director, Laxminarayan Institute of Technology for providing computer facilities. 相似文献
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An environmentally benign and enantioselective Michael addition of nitromethane/thiols to trans-chalcone catalyzed by per-6-amino-β-cyclodextrin (per-6-ABCD) is carried out in water at room temperature with good yield and enantiomeric excess. The catalyst is recovered and reused without loss in its activity. 相似文献
189.
In the scenario of first laser communication relay satellite being launched into geostationary earth orbit, we evaluate the reduction in transmitter power requirement for earth-to-satellite and satellite-to-earth free space optical links in presence of turbulence and various weather conditions using spatial diversity technique. In channel modeling, Beer Lambert Law incorporates the weather effects. The log-normal probability density function (pdf) models weak turbulence and gamma–gamma pdf moderate to strong turbulence. Using the combined channel state pdf, bit error rate (BER) expressions are derived for on-off keying (OOK), M-ary pulse position modulation (M-PPM) and M-ary differential PPM (M-DPPM) schemes. From the BER plots, we evaluate the minimum average received power required to achieve a desired BER for all three schemes for different channel conditions. Subsequently, minimum transmitter power requirement is evaluated for both uplink and downlink using the range equation. It is observed that presence of moderate, light and thin fog cause additional power requirement. Also, among the three schemes, M-PPM scheme requires the least transmitter power, followed by M-DPPM and OOK schemes. Further, it is seen that the transmitter diversity or multiple input single output technique reduces the uplink minimum transmitter power requirement, whereas for downlink aperture averaging and receiver diversity or single input multiple output techniques can achieve the same. The power requirement for uplink is 8–10 dB more as compared to downlink in presence of turbulence and various weather conditions. 相似文献
190.
Allan W. Roczko S. Kasi Viswanadham Andrew G. Sharkey David M. Hercules 《Fresenius' Journal of Analytical Chemistry》1989,334(6):521-526
Summary Metal ions introduced in the +1 oxidation state are better for the cationization of saccharides than cations in other oxidation states. This effect is related to the ease of formation of singly charged adduct ions by reaction with singly charged metal ions. Sample preparation had little effect on the reproducibility of the spectra. Use of a nitrocellulose matrix can introduce competition between the matrix and saccharide for cations, leading to lower ion intensities. The concentration of the salt and saccharide had little effect on cationization signal intensity once a threshold concentration was exceed: 0.1 M metal ion and 0.5 M saccharide.
Untersuchung der Kationisierung von Sacchariden durch Laser-Massenspektrometrie相似文献