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1.
NIKITIN S.; PR?TZEL-WOLTERS D. 《IMA Journal of Mathematical Control and Information》1991,8(4):431-439
In 1983 Morse proved, for unknown scalar one-dimensional linearsystems, the nonexistence of rational or polynomial universalstabilizers (UAS). In 1983, Nussbaum gave an example of an analyticUAS. In our paper, it is shown that there exist time-invariantpolynomial UAS's with multidimensional gain adaptation. Thedesign procedure is developed for linear, minimum-phase systemsof relative degree one. Convergence of the closed-loop systemis proved. Some numerical simulations are provided. 相似文献
2.
In this paper we present a series of work covering a range of aspects relating molecular simulation to experiment. The importance
of surface mediation type effects to the adsorption of simple and complex gases is demonstrated. Coupled with the adsorption
of simple gases is their projection area when used for surface area determination. The pressure dependence of a projection
area is demonstrated for argon at 77 and 87.3 K. A simple model is used to account for the degree of graphitisation of a surface
is demonstrated and used to account for the isosteric heat behaviour of non-graphitised carbon blacks. Turning from surfaces
to porous solids, an alternative treatment of experiment data (either sub or super critical) is presented that avoids the
ambiguity of excess amounts adsorbed. Using this method one is able to obtain pore size distributions and amounts adsorbed
without relying on such things as helium expansion volumes. Since this type of method is usually applied to composite solids
we also demonstrate the correct method for calculating the heat of adsorption using independent sets of simulations. The final
topic covered in this paper is an example of the information that can be gained from the heat capacity of an adsorbed phase. 相似文献
3.
The range of chemical flexibilities of the hexagonal frameworks (Ta6Si4O26)6? and (Ta14Si4O47)8? have been partially explored. This has been done with high-temperature preparations as in general ionic mobilities in these frameworks are too low to permit low-temperature ion exchange. Ionic site potential calculations indicate that preferential site-occupancy factors as well as geometric constraints are responsible for the absence of ionic motion. New phases K6?xNaxTa6Si4O26 (x ? 4), K8?xNaxTa14Si4O47 (x ? 5), and impure Ba3?xNa2xTa6Si4O26 have been prepared. Introduction of up to 2 moles of Li+ and 1 mole of Mg2+ ions per formula unit into sites of the framework not normally occupied has been demonstrated as well as the possibility of partially substituting Zr4+ for Ta5+ ions. Substitutions designed to introduce large tunnel vacancies in the presence of only monovalent K+ or Na+ ions (P for Si, W for Ta and F for O) generally proved unsuccessful. Competitive phases also frustrated attempts to substitute either the larger Rb+ or the smaller Li+ ions into the large-tunnel sites. A large area of solid solution was discovered in the BaONa2OTa2O5 phase diagram; it has a (TaO3)-framework with the structure of tetragonal potassium tungsten bronze. 相似文献
4.
5.
Xiao Chi Ma Bao Jing Zhang Sha Deng Shan Shan Huang Ke Xin Liu Jing Ming Jia 《中国化学快报》2009,20(3):317-319
A new ent-labdane diterpenoid lactone with a new natural product was isolated from Andrographis paniculata. Their structures were elucidated on the basis of spectral evidences including 2D NMR. 相似文献
6.
Cruz MD Robles MC Jespersen JB Kilpinen O Birkett M Dewhirst S Pickett J 《Micron (Oxford, England : 1993)》2005,36(5):415-421
Scanning electron microscopy (SEM) studies on the poultry red mite, Dermanyssus gallinae (DeGeer), showed that the tip of the foreleg tarsus of both sexes and early instar stages (larvae, protonymph and deutonymph) bears a cluster of 10 blunt peg-type sensillae. Diversity in size, shape and surface features of the wall of these sensillae characterize the sensilla complex (sensory field). Two short setae (1 and 2) with smooth walls lack detectable pores, whereas three medium-sized setae (4, 5 and 8) bear pores in the wall. Four medium or long setae (3, 6, 7 and 9) have longitudinal grooves or ribs in the wall, whilst one seta (10) possesses both pores and grooves in the wall. Based on the morphology, it is suggested that the porous setae could be olfactory receptors, and the grooved setae could be mechanoreceptors. 相似文献
7.
An alternative approach to synthesize pedamide,a key building block of pederin was described.Iodine-induced asymmetric heterocyclization was used as the key step to construct the skeleton,a tetrahydropyran ring with three chiral centers.Brown's asymmetric allylation and Lewis acid-mediated allylation were investigated to introduce chains and chiral alcohols.Sharpless dihydroxylation decorated the side chain.And high optically pure target was obtained by removing the epimers formed in these reactions on c... 相似文献
8.
A convenient route for the synthesis of 3,4-dihydrocoumarin derivates from salicylaldehyde derivates and 1,3-dicarbonyl compounds under solvent-free microwave irradiation conditions was described. In this way, a range of compounds was obtained in moderate to good yields in a short reaction time. 相似文献
9.
Self-injection length in La0.7Ca0.3MnO3-YBa2Cu3O7-δ ferromagnet-superconductor multilayer thin films
We have carried out extensive studies on the self-injection problem in barrierless heterojunctions between La0.7Ca0.3MnO3 (LCMO) and YBa2Cu3O7-δ (YBCO) thin films. The heterojunctions were formed in situ by sequentially growing LCMO and YBCO films on 〈100〉 LaAlO3 (LAO) substrate using a pulsed laser deposition (PLD) system. YBCO micro-bridges with 64 μm width were patterned both on
the LAO (control) and LCMO side of the substrate. Critical current, I
c, was measured at 77 K on both the control side as well as the LCMO side for different YBCO film thickness. It was observed
that while the control side showed a J
c of ∼ 2 × 106 A/cm2, the LCMO side showed about half the value for the same thickness (1800 ?). The difference in J
c indicates that a certain thickness of YBCO has become ‘effectively’ normal due to self-injection. From the measurement of
J
c at two different thicknesses (1800 ? and 1500 ?) of YBCO films both on the LAO as well as the LCMO side, the value of self-injection
length (at 77 K) was estimated to be ∼ 900 ?. To the authors’ best knowledge, this is the first time that self-injection length
has been quantified. A control experiment carried out with LaNiO3 deposited by PLD on YBCO did not show any evidence of self-injection. 相似文献
10.