142 research outputs found

    Random routing scheme with misleading dead ends

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    A new method of sink location security in a Wireless Sensor Network is proposed. In the proposed scheme, all the node addresses are encrypted and an attacker cannot determine the real sink address by capturing the packets and analyzing its contents for the final destination. The main contribution of our proposed method is to use random routing scheme with misleading dead ends. This provides security against traffic analysis attack

    A bilateral shear layer between two parallel Couette flows

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    We consider a shear layer of a kind not previously studied to our knowledge. Contrary to the classical free shear layer, the width of the shear zone does not vary in the streamwise direction but rather exhibits a lateral variation. Based on some simplifying assumptions, an analytic solution has been derived for the new shear layer. These assumptions have been justified by a comparison with numerical solutions of the full Navier-Stokes equations, which accord with the analytical solution to better than 1% in the entire domain. An explicit formula is found for the width of the shear zone as a function of wall-normal coordinate. This width is independent of wall velocities in the laminar regime. Preliminary results for a co-current laminar-turbulent shear layer in the same geometry are also presented. Shear-layer instabilities were then developed and resulted in an unsteady mixing zone at the interface between the two co-current streams.Comment: 6 pages, 7 figures. Accepted for publication in Phys. Rev.

    Dimethyl 4-(3-hydroxy­phen­yl)-2,6-dimethyl-1,4-dihydro­pyridine-3,5-dicarboxyl­ate

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    The 1,4-dihydro­pyridine ring in the title compound, C17H19NO5, has a flattened-boat conformation, and the benzene ring is almost orthogonal to it [dihedral angle = 82.98 (12)°]. The hydr­oxy group is disordered over two positions in a 0.780 (4):0.220 (4) ratio. In the crystal, hydrogen-bonding inter­actions of the type Na—H⋯Oc and Oh—H⋯Oc (a = amine, c = carbonyl and h = hydr­oxy) link the mol­ecules into a three-dimensional network

    (2E)-3-(4-Bromo­phen­yl)-1-(2-methyl-4-phenyl-3-quinol­yl)prop-2-en-1-one

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    The conformation about the ethene bond [1.316 (3) Å] in the title compound, C25H18BrNO, is E. The quinoline ring forms dihedral angles of 67.21 (10) and 71.68 (10)° with the benzene and bromo-substituted benzene rings, respectively. Highlighting the non-planar arrangement of aromatic rings, the dihedral angle formed between the benzene rings is 58.57 (12)°

    Ethyl 4-(3-hydroxy­phen­yl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa­hydro­quinoline-3-carboxyl­ate

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    In the mol­ecular structure of the title compound, C21H25NO4, the dihydro­pyridine ring adopts a flattened boat conformation while the cyclo­hexenone ring is in an envelope conformation. In the crystal structure, mol­ecules are linked into a two-dimensional network parallel to (10) by N—H⋯O and O—H⋯O hydrogen bonds. The network is generated by R 4 4(30) and R 4 4(34) graph-set motifs

    Tris(methyl 3-oxobutanoato-κ2 O,O′)aluminium(III)

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    In the title compound, [Al(C5H7O3)3], three acac-type ligands (methyl 3-oxobutanoate anions) chelate to the aluminium(III) cation in a slightly distorted AlO6 octa­hedral coordination geometry. Electron delocalization occurs within the chelating rings

    3-Ethyl-4-methyl-1H-pyrazol-2-ium-5-olate

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    The title compound, C6H10N2O, is a zwitterionic pyrazole derivative. The crystal packing is predominantly governed by a three-center iminium–amine N+—H⋯O−⋯H—N inter­action, leading to an undulating sheet-like structure lying parallel to (100)

    Ethyl 2-acetyl-3-(4-chloro­anilino)butanoate

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    The title compound, C14H18ClNO3, adopts an extended conformation, with all of the main chain torsion angles associated with the ester and amino groups trans. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds are observed

    4-(4-Chloro­phen­yl)-N-[(E)-4-(dimethyl­amino)­benzyl­idene]-1,3-thia­zol-2-amine

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    The title compound, C18H16ClN3S, adopts an extended mol­ecular structure. The thia­zole ring is inclined by 9.2 (1) and 15.3 (1)° with respect to the chloro­phenyl and 4-(dimethyl­amino)­phenyl rings, respectively, while the benzene ring planes make an angle of 19.0 (1)°. A weak inter­molecular C—H⋯π contact is observed in the crystal structure

    1,1′-(p-Phenyl­enedimethyl­ene)dipiperidin-4-one

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    In the mol­ecule of the title compound, C18H24N2O2, the piperidine rings are in chair conformations. The crystal structure is stabilized by inter­molecular C—H⋯O hydrogen bonding. There are neither C—H⋯π nor π–π inter­actions in the structure
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