Author Index

Authors Index

Author Index     

Algebraically Self-Consistent Quasiclassical Approximation on Phase Space

The Wigner–Weyl mapping of quantum operators to classical phase space functions preserves the algebra, when operator multiplication is mapped to the binary * operation. However, this isomorphism is destroyed under the quasiclassical substitution of * with conventional multiplication; consequently, an approximate mapping is required if algebraic relations are to be preserved. Such a mapping is uniquely determined by the fundamental relations of quantum mechanics, as is shown in this paper. The resultant quasiclassical approximation leads to an algebraic derivation of Thomas–Fermi theory, and a new quantization rule which—unlike semiclassical quantization—is non-invariant under action transformations of the Hamiltonian, in the same qualitative manner as the true eigenvalues. The quasiclassical eigenvalues are shown to be significantly more accurate than the corresponding semiclassical values, for a variety of 1D and 2D systems. In addition, certain standard refinements of semiclassical theory are shown to be easily incorporated into the quasiclassical formalism.     

Investigation of operational parameters for an industrial CFB combustor of coal, biomass and sludge

The combustion of coal and/or biomass （sludge, wood waste, RDF, etc.） in a circulating fluidized bed has been a commercial topper for over 20 years, and references to principles and applications are numerous and widespread although few data are presented concerning the operation of large scale CFB-units. The authors studied the CFB-combustion at UPM-Kymmene （Ayr）, a major paper mill relying for its steam production upon the combustion of coal （80-85 %）, wood bark （5-10%） and wastewater treatment sludge （5-10%）. The maximum capacity of the CFB is 58 MWth. A complete diagnostic of the operation was made, and additional tests were performed to assess the operating mode. The plant schematics, relevant dimensions and process data are given. To assess the operation of the UPM-CFB, it is important to review essential design parameters and principles of CFB combustors, which will be discussed in detail to include required data, heat balance and flowrates, operating versus transport velocity, kinetics and conversion （including the possible effect of the Bouduard reaction if carbon is present）. Since the residence time in the riser and the cyclone efficiency determine the burnout of circulating fuel-particles, the UPM-CFB was subjected to a stimulus response technique using nickel oxide as tracer. Results illustrate the efficiency of the cyclone separation and the number of recycle loops for particles of a given size. Results will also be used to assess the cyclone operation and efficiency and to comment upon expected and measured carbon conversion.     

The Journey of Ni(I) Chemistry

In the last twenty years, nickel has successfully imprinted its role in the field of homogeneous catalysis as a valid and complementary alternative to palladium and platinum catalysts. However, compared to those, there are often many different available pathways in nickel catalysis due to the facile access of intermediate oxidation states. Among them, Ni(I) has been increasingly proposed as a key oxidation state in multiple transformations. This oxidation state had already been suggested a long time ago but has only recently undergone a renaissance with extensive ligand design which has led to over 100 isolated Ni(I) complexes. In addition, the analysis of many catalytic cycles has revealed that the Ni(I) species can not only occur as a decomposition product perturbing a Ni(0)–Ni(II) pathway but can also play a key role in alternative Ni(I)–Ni(III) cycles. This behavior is highly dependent on the class of transformation and ligand employed in catalysis. Herein, we concisely describe the journey of this oxidation state, combining the information gathered from inorganic synthesis and mechanistic investigations, from its synthesis to its postulated role in different catalytic cycles.