Coalition Formation With Communication Ranges and Moving Targets

A team of unmanned aerial vehicles (UAVs) with limited communication ranges and limited resources are deployed in a region to search and destroy stationary and moving targets. When a UAV detects a target, depending on the target resource requirement, it is tasked to form a coalition over the dynamic network formed by the UAVs. In this paper, we develop a mechanism to find potential coalition members over the network using principles from internet protocol and introduce an algorithm using Particle Swarm Optimization to generate a coalition that destroys the target is minimum time. Monte-Carlo simulations are carried out to study how coalition are formed and the effects of coalition process delays.

Wet chemical syntheses of ultrafine multicomponent ceramic powders through gel to crystallite conversion

Coarse (BOn/2)-O-n+/xH(2)O (10

Biosorption of copper and zinc using waste Aspergillus niger biomass

Nonliving waste biomass consisting of Aspergillus niger attached to wheat bran was used as a biosorbent for the removal of copper and zinc from aqueous solutions. Copper and zinc uptake by the biomass obeyed Langmuir isotherms. The binding capacity of the biomass for copper was found to be higher than that for zinc. The metal uptake, expressed in milligrams per gram of biomass, was found to be a function of: the initial metal concentration (with the uptake decreasing with increasing initial concentration), the biomass loading (with the uptake decreasing with increasing biomass loading) and pH (with the uptake increasing with increasing pH in the range of 1.5 and 6.0). The metal uptake was significantly affected in the presence of a co-ion. The uptake of copper by the biomass decreased in the presence of zinc and vice versa. The decrease in metal uptake was dependent on the concentrations of metals in the two-component aqueous solutions. The effect of copper on zinc uptake was more pronounced than the effect of zinc on copper uptake.

Microwave-assisted selective deoxygenation of layer- and chain-containing oxides

Very rapid (within 5 min), selective, single-step deoxygenation of layer- and chain-containing oxides, MoO3, CrO3, V2O5, alpha-VOPO4 . 2H(2)O and Ag6Mo10O33 has been accomplished using graphitic carbon in a microwave-assisted reaction. The products were found to be MoO2, Cr2O3, VO2, VPO4 and a mixture of (Ag + MoO2), respectively. Products were characterised by X-ray diffraction (XRD), differential scanning calorimetry (DSC), IR and electron paramagnetic resonance (EPR) spectroscopies. Although conventional methods of preparing these materials are tedious, the present method is simple, fast and yields very homogeneous products of good crystallinity. Our results reveal that while layer- and chain-containing oxides undergo rapid microwave-assisted carbothermal reduction, the non-layered materials do not. The high structural selectivity of these reactions is suggestive of the topochemical nature of the fast reduction process.

Combustion synthesis and properties of the NASICON family of materials

The fine-particle NASICON family of materials, MZr2P3O12(where M = Na, K, ½Ca and ¼Zr) and NbZrP3O12, have been prepared by the combustion of aqueous heterogeneous mixtures of stoichiometric amounts of metal nitrate, zirconyl nitrate, niobium phosphate, diammonium hydrogen phosphate, ammonium perchlorate and carbohydrazide (CH) at 400 °C. The formation of NASICON materials was confirmed by powder X-ray diffraction (XRD), IR, solid-state (31P) NMR spectroscopy and thermal expansion coefficient measurements. The combustion-synthesized NASICON powders have an average agglomerate size of 9�13 µm with a specific surface area varying from 8 to 28 m2 g�1. The powders pelletized and sintered in the range 1100�1200 °C for 5 h achieved 95�97% theoretical density and showed fine-grain microstructure. The coefficient of thermal expansion of a sintered compact was measured up to 500 °C and ranged from �1.5 × 10�6°C�1 to 1.0 × 10�6°C�1 depending on the composition.

Combustion synthesis of yttria

Fine-particle, sinter-active yttria has been prepared by combustion of a redox compound, Y(N2H3COO)3·3H2O and mixtures of Y(N2H3COO)3·3H2O�NH4NO3 or NH4ClO4 as well as yttrium nitrate and hydrazine-based fuels. The fineparticle nature of the combustion-derived yttria has been investigated using powder density, particle size and BET surface area measurements. The uniaxially, cold-pressed fine-particle yttria when sintered at 1450�1500 °C achieved 98% theoretical density and showed a fine-grain (1�2 µm) microstructure.

Demographic history of India and mtDNA-sequence diversity

The demographic history of India was examined by comparing mtDNA sequences obtained from members of three culturally divergent Indian subpopulations (endogamous caste groups). While an inferred tree revealed some clustering according to caste affiliation, there was no clear separation into three genetically distinct groups along caste lines. Comparison of pairwise nucleotide difference distributions, however, did indicate a difference in growth patterns between two of the castes. The Brahmin population appears to have undergone either a rapid expansion or steady growth. The low-ranking Mukri caste, however, may have either maintained a roughly constant population size or undergone multiple bottlenecks during that period. Comparison of the Indian sequences to those obtained from other populations, using a tree, revealed that the Indian sequences, along with ah other non-African samples, form a starlike cluster. This cluster may represent a major expansion, possibly originating in southern Asia, taking place at some point after modern humans initially left Africa.

Superconductivity of La2?ySryCu1?xNixO4+? (y = 0.1, 0.2; 0less-than-or-equals, slantxless-than-or-equals, slant0.5) The hole-compensating effect of Ni

Magnetization measurements below 50 K on ceramic La2?ySryCu1?xNixO4+? (y = 0.1, 0.2; 0less-than-or-equals, slantxless-than-or-equals, slant0.5) show a progressive diminution of superconducting properties with increasing x. The larger suppressive action of Ni in the y=0.1 system than that for y=0.2 is attributed to the hole-compensating effect of Ni3+. The assumption that nickel is in the 3+ state satisfactorily explains: (1) the reduction in hole concentration, (2) a right-shift of the Tc versus y curve with x, and (3) the low magnetic moment carried by Ni atoms, in the La2?ySryCu1?xNixO4+? system.

Solid-state miscibility gap and thermodynamics of the system BaO–SrO

A solid-state miscibility gap in the pseudo-binary system BaO-SrO is delineated by X-ray diffraction studies on samples equilibrated either in vacuum or under flowing inert gas at temperatures between 1073 and 1423 K. For the SrxBa1-xO solid solution an asymmetric phase boundary, characterized by a critical temperature of 1356 (+/-4) K and composition x=0.55 (+/-0.008), is obtained. Thermodynamic mixing properties of the solid solution, derived from the experimental phase boundary compositions and temperatures, can be represented by the expression: Delta G(E)=x(1-x){33 390-7.09T)x+(29 340-6.23T)(1-x)} J mol(-1)It is necessary to include excess entropy terms to obtain a good fit to the experimental data. The chemical spinodal curve is computed from the thermodynamic parameters

Synthesis and structure of oxygen-deficient La2NiCoO5 and LaSrCo2O5 phases

The La2NiCoO5 and LaSrCo2O5 phases have been synthesized by the temperature-programmed reduction (TPR) of the parent mixed perovskites LaNi0.5Co0.5O3 and La0.5Sr0.5CoO3, respectively, under an ammonia atmosphere. While La2NiCoO5 adopts a structure similar to the vacancy-ordered La2Ni2O5, LaSrCo2O5 crystallized in a brownmillerite-like structure. The reactivity of the perovskite oxides towards reduction by ammonia and the structure of the product oxides are found to be guided by factors such as the coordination and oxidation state of the transition-metal cations.

Unusual photobehaviour of crystalline 7-methoxy-4-methylcoumarin

7-Methoxy-4-methylcoumarin undergoes a solid-state photo [2 + 2] cycloaddition upon UV irradiation to yield two photodimers. The formation of the minor product appears to be a direct consequence of the formation of the topochemically controlled dimer.

Nanoscale Ag–Pd and Cu–Pd alloys

Nanoparticles of Ag-Pd and Gu-Pd alloys with diameters in the 5-40 nm range have been prepared over the entire range of compositions, by employing the heterogeneous reaction of dry methanol or ethanol with intimate mixtures of AgNO3+PdOx and CuOx+PdOx, respectively. The nanoscale alloys have been characterized by energy-dispersive Xray (EDX) analysis, transmission electron microscopy (TEM) and X-ray diffraction (XRD). All the alloy particles possess the fee structure and can be obtained in bulk quantities.

Instability, intermittency, and multiscaling in discrete growth models of kinetic roughening

We show by numerical simulations that discretized versions of commonly studied continuum nonlinear growth equations (such as the Kardar-Parisi-Zhangequation and the Lai-Das Sarma-Villain equation) and related atomistic models of epitaxial growth have a generic instability in which isolated pillars (or grooves) on an otherwise flat interface grow in time when their height (or depth) exceeds a critical value. Depending on the details of the model, the instability found in the discretized version may or may not be present in the truly continuum growth equation, indicating that the behavior of discretized nonlinear growth equations may be very different from that of their continuum counterparts. This instability can be controlled either by the introduction of higher-order nonlinear terms with appropriate coefficients or by restricting the growth of pillars (or grooves) by other means. A number of such ''controlled instability'' models are studied by simulation. For appropriate choice of the parameters used for controlling the instability, these models exhibit intermittent behavior, characterized by multiexponent scaling of height fluctuations, over the time interval during which the instability is active. The behavior found in this regime is very similar to the ''turbulent'' behavior observed in recent simulations of several one- and two-dimensional atomistic models of epitaxial growth.

Measurement of Gibbs energy of formation of Ca2PbO4 using a solid-state cell with three electrodes

Phase relations in the system Ca-Pb-O at 1100 K have been determined by equilibrating 18 compositions in the ternary and identifying the phases present in quenched samples by X-ray diffraction and energy dispersive X-ray analysis (EDX). Only one ternary compound Ca2PbO4 was found to be present. The compound coexists with CaO and PbO. The intermetallic compounds Ca2Pb, Ca5Pb3 and CaPb and liquid alloys are in equilibrium with CaO. The standard Gibbs energies of formation of Ca2PbO4 (880 - 1100 K) and Pb3O4 (770 - 910 K) were determined using solid-state cells based on yttria-stabilized zirconia as the solid electrolyte. Pure oxygen gas at 0.1 MPa was used as the reference electrode. For measurements on Ca2PbO4, a novel cell design with three electrodes in series, separated by solid electrolyte membranes, was used to avoid polarization of the electrode containing three solid phases. Two three-phase electrodes were used. The first absorbs the electrochemical flux of oxygen from the reference electrode to the measuring electrode. The other three-phase electrode, which is unaffected by the oxygen flux through the solid electrolyte, is used for electromotive force (EMF) measurement. The results from EMF studies were cross-checked using thermogravimetry (TG) under controlled oxygen partial pressures. The stability of Pb3O4 was investigated using a conventional solid-state cell with RuO2 electrodes. The results can be summarized by the following equations: 2CaO + PbO +1/2O(2) --> Ca2PbO4 Delta(r)G degrees/J mol(-1) = (- 128340 + 93.21 T/K) +/- 200 3PbO + 1/2O(2) --> Pb3O4 Delta(r)G degrees/J mol(-1) = (- 70060 + 77.5 T/K) +/- 150