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21.
Rachel K. Kalaimani Madhu N. Belur Sivaramakrishnan Sivasubramanian 《Linear algebra and its applications》2013
In this paper we assume dynamical systems are represented by linear differential-algebraic equations (DAEs) of order possibly higher than one. We consider a structured system of DAEs for both the to-be-controlled plant and the controller. We model the structure of the plant and the controller as an undirected and bipartite graph and formulate necessary and sufficient conditions on this graph for the structured controller to generically achieve arbitrary pole placement. A special case of this problem also gives new equivalent conditions for structural controllability of a plant. Use of results in matching theory, and in particular, ‘admissibility’ of edges and ‘elementary bipartite graphs’, make the problem and the solution very intuitive. Further, our approach requires standard graph algorithms to check the required conditions for generic arbitrary pole placement, thus helping in easily obtaining running time estimates for checking this. When applied to the state space case, for which the literature has running time estimates, our algorithm is faster for sparse state space systems and comparable for general state space systems. 相似文献
22.
Umapathi Krishnamoorthy MeenakshiSundaram Nachiappan Kalpana Palanisamy 《Physics and Chemistry of Liquids》2019,57(3):371-381
The aim of this work was to analyse the electrostatic potential profile, various effects of electrolyte concentrations, and the influences of surface charge on a protein bound to a lipid coated Silicon nanowire field effect transistor (Si-NW FET) biosensor by implementing the modified Poisson–Boltzmann (MPB) model. In this work, we modelled a lipid monolayer-coated Si-NW FET for the sensing of proteins, which consisted of variable amounts of aspartic acid. The electrostatic potential profile, protein charge distributions, the response to various electrolyte concentration, and the impacts of various surface charge were studied by implementing the MPB model with the Si-NW FET biosensor. Additionally, a comparison between the use of the MPB and the Poisson–Boltzmann model in studying the effects of various surface charges was carried out. Taken together, it was found that the MPB model showed a higher resolution in studying the Si-NW FET biosensor model when higher concentrations and surface charges were administered. 相似文献
23.
Karteek Boga Sashivinay Kumar Gaddam Ramakishan Rao Chepuri Aruna Palanisamy 《先进技术聚合物》2019,30(11):2742-2749
An eco‐friendly coating system, which is largely biobased, has been developed from castor and cottonseed oil. Cottonseed oil was functionalized with maleic anhydride by “ene” reaction to give maleinized cottonseed oil (MACSO); the anhydride groups were reacted with isocyanates to yield –NCO terminated polyurethane prepolymer. The prepolymer was further chain extended with hydroxyl groups of castor oil to give polyurethane‐imides (PUIs). The cross‐linked films thus obtained had good mechanical properties, and the imide groups in the backbone improved the corrosion resistance of PUIs as revealed by potentiodynamic polarization study. With increasing content of MACSO, thermal stability, glass transition temperatures (Tg), tensile strength, and corrosion resistance of resulting PUIs significantly increased. 相似文献
24.
Magnús M. Halldórsson Guy Kortsarz Jaikumar Radhakrishnan Sivaramakrishnan Sivasubramanian 《Combinatorica》2007,27(5):519-550
A complete partition of a graph G is a partition of its vertex set in which any two distinct classes are connected by an edge. Let cp(G) denote the maximum number of classes in a complete partition of G. This measure was defined in 1969 by Gupta [19], and is known to be NP-hard to compute for several classes of graphs. We
obtain essentially tight lower and upper bounds on the approximability of this problem. We show that there is a randomized
polynomial-time algorithm that given a graph G with n vertices, produces a complete partition of size Ω(cp(G)/√lgn). This algorithm can be derandomized.
We show that the upper bound is essentially tight: there is a constant C > 1, such that if there is a randomized polynomial-time algorithm that for all large n, when given a graph G with n vertices produces a complete partition into at least C·cp(G)/√lgn classes, then NP ⊆ RTime(n
O(lg lg n)). The problem of finding a complete partition of a graph is thus the first natural problem whose approximation threshold
has been determined to be of the form Θ((lgn)
c
) for some constant c strictly between 0 and 1.
The work reported here is a merger of the results reported in [30] and [21]. 相似文献
25.
Vinitha G Ramalingam A Palanisamy PK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,68(1):1-5
Solid-state dye-doped polymers are attractive alternative to the conventional liquid dye solutions. In this paper, nonlinear properties of the dye Pararosanilin has been studied. The third-order nonlinear optical properties of Pararosanilin dye in 1-butanol and dye-doped polymer film were measured by the Z-scan technique using 532 nm diode pumped Nd:Yag laser. This material exhibits negative optical nonlinearity. The dye at 0.4 mM concentration exhibited nonlinear refractive coefficient (n(2) = -6.8 x 10(-8) and -7.11 x 10(-8) (cm(2)/W) in liquid and solid media, respectively), nonlinear absorption coefficient (beta = -7.7 x 10(-4) and -7.93 x 10(-4)cm/W in liquid and solid media, respectively) and susceptibility (chi((3))=3.38 x 10(-6) and 3.53 x 10(-5)esu in liquid and solid media, respectively). These results show that Pararosanilin dye has potential applications in nonlinear optics. 相似文献
26.
Ganarajan Sivasubramanian Veembil Ramachandran Parameswaran 《Journal of heterocyclic chemistry》2007,44(6):1223-1230
27.
Satyaprakash Sahoo S. Dhara V. Sivasubramanian S. Kalavathi A. K. Arora 《Journal of Raman spectroscopy : JRS》2009,40(8):1050-1054
1‐longitudinal optical (LO) phonons in free‐standing mixed Cd1−xZnxS nanocrystals, synthesized using chemical precipitation, are investigated using Raman spectroscopy. As expected for the nanocrystals, the 1‐LO modes are found to appear at slightly lower wavenumbers than those in the bulk mixed crystals and exhibit one‐mode behavior. On the other hand, the line broadening is found to be much more than that can be accounted on the basis of phonon confinement. From the detailed line‐shape analysis it turns out that the substitutional disorder in the mixed crystals contributes much more to the line broadening than the phonon confinement. The linewidth arising from these mechanisms are also extracted from the analysis. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
28.
Rodrigues LM Sivasubramanian A Pinto EM Oliveira-Campos AM Seijas JA Vázquez-Tato MP 《Magnetic resonance in chemistry : MRC》2009,47(1):84-86
A series of 21 substituted pyrazolo[3,4-d]pyrimidines-4-amines were studied by (1)H and (13)C NMR. The application of two-dimensional techniques, HMQC and HMBC, allowed the complete assignment of the spectra for all the compounds. 相似文献
29.
Sivaramakrishnan Sivasubramanian 《Discrete Mathematics》2009,309(10):3458-3462
Brendan McKay gave the following formula relating the average distance between pairs of vertices in a tree T and the eigenvalues of its Laplacian:
30.
Maheswari PU Roy S den Dulk H Barends S van Wezel G Kozlevcar B Gamez P Reedijk J 《Journal of the American Chemical Society》2006,128(3):710-711
Chemical nucleases based on the transition-metal ions cleave DNA hydrolytically and/or oxidatively, with or without added reductant. We report here the novel DNA cleavage properties of the highly water-soluble, square-planar [Cu(Hpyrimol)Cl] complex, together with the results of cytotoxicities toward selected cancer cell lines. The copper complex cleaves PhiX174 supercoiled DNA efficiently without any reductant and shows high cytotoxicities toward L1210 murine leukemia and A2780 human ovarian carcinoma cancer cell lines that are sensitive and resistant to cisplatin. The IC50 values obtained for the copper complex in the sensitive cell lines are in the range of cisplatin, and for the cisplatin-resistant leukemia cell line, this value is even better. 相似文献