Simulation of detonation wave interaction using an ignition and growth model

A kinetics based detonation model has been integrated with an existing object oriented hydrocode. The model has been demonstrated to correctly predict the shock initiation of explosives and captures key features such as the von Neumann pressure spike and reaction zone. Comparisons to experimental flyer plate data for both primary and secondary class explosives have been performed and key features such as detonation wave form and resulting target disk velocities are reproduced. Simulations have also been performed representing the interaction of various mechanical waves. First, the interaction of detonation waves, a key process in energetic systems, is simulated. Next, the response of an established detonation wave to an explosive that has been preconditioned by a weak compression wave is modeled. These have been carried out to determine the utility of the existing kinetic schemes for such problems.     

The synthesis and electrochemical behaviour of carbazole-substituted phthalocyanines

The syntheses of new cobalt and zinc phthalocyanine complexes containing carbazole (Cz) substituents at the peripheral positions are reported (CzCoPc and CzZnPc). The reaction of Cz with 4-iodophthalonitrile in the presence of a catalytic amount of copper(I) oxide and potassium carbonate led to the formation of 4-(9H-carbazol-9-yl) phthalonitrile. Furthermore, by heating the dinitrile and anhydrous metal salts (CoCl₂, Zn(CH₃COO)₂) at 160 °C in n-hexanol in the presence of DBU, the phthalocyanines were obtained. They were characterised by ¹H NMR, FT-IR, UV-Vis and MS spectroscopic data. Aggregation behaviours of Pcs were investigated in THF. Electrochemical redox behaviour of CzCoPc was investigated by cyclic voltammetry depending on the potential range, and the oxidation and reduction products were followed by UV-Visible absorption measurements. Polymerisation of CzCoPc was carried out by potentiodynamic methods on glassy carbon electrode, and the catalytic activity of resulting polymer (P[CzCoPc]) was tested comparatively with polycarbazole (PCz)-coated electrode for dopamine and better response was obtained for P[CzCoPc] modified electrode.     

Conjugacy and dynamics in Thompson’s groups

We give a unified solution to the conjugacy problem for Thompson’s groups \(F, \,T\), and \(V\). The solution uses “strand diagrams”, which are similar in spirit to braids and generalize tree-pair diagrams for elements of Thompson’s groups. Strand diagrams are closely related to piecewise-linear functions for elements of Thompson’s groups, and we use this correspondence to investigate the dynamics of elements of \(F\). Though many of the results in this paper are known, our approach is new, and it yields elegant proofs of several old results.     

Realizability of Graphs

A graph is d-realizable if, for every configuration of its vertices in E^N, there exists a another corresponding configuration in E^d with the same edge lengths. A graph is 2-realizable if and only if it is a partial 2-tree, i.e., a subgraph of the 2-sum of triangles in the sense of graph theory. We show that a graph is 3-realizable if and only if it does not have K₅ or the 1-skeleton of the octahedron as a minor.     

Realizability of Graphs in Three Dimensions

This paper concludes the characterization of 3-realizable graphs begun by Belk and Connelly. A graph is 3-realizable if, for every configuration of its vertices in E^N with N ≥ 3, there exists a corresponding configuration in E³ with the same edge lengths. In this paper the two graphs V₈ and C₅ × C₂ are shown to be 3-realizable. As shown by Belk and Connelly, this means that the forbidden minors for 3-realizability are K₅ and K_2,2,2.A graph is d-realizable if, for every configuration of its vertices in E^N, there exists a another corresponding configuration in E^d with the same edge lengths.     

Demonstration of ignition radiation temperatures in indirect-drive inertial confinement fusion hohlraums

We demonstrate the hohlraum radiation temperature and symmetry required for ignition-scale inertial confinement fusion capsule implosions. Cryogenic gas-filled hohlraums with 2.2 mm-diameter capsules are heated with unprecedented laser energies of 1.2 MJ delivered by 192 ultraviolet laser beams on the National Ignition Facility. Laser backscatter measurements show that these hohlraums absorb 87% to 91% of the incident laser power resulting in peak radiation temperatures of T(RAD)=300 eV and a symmetric implosion to a 100 μm diameter hot core.     

Structural characterization of glassy phases in the system Na2O-Ga2O3-P2O5 by MAS-NMR, EXAFS and vibrational spectroscopy. I. Cations coordination

The cationic coordinations of phosphate based gallium sodium glasses in the system Na2O-Ga2O3-P2O5 have been studied by several techniques (71Ga and 23Na MAS-NMR, EXAFS and vibrational spectroscopies) in order to study the relationship between the structure and the chemical composition. We found that three different environments are available for the gallium ions while it is very difficult to get accurate information on the sodium coordinations. Our data show that in orthophosphate glasses, gallium is mainly tetrahedral but when the mean phosphate chain length increases, its coordination becomes more and more octahedral. In these glassy structure, it becomes then possible to dissolve large amounts of typically octahedral cations like Fe3+ or Cr3+.