The \u3csup\u3e13\u3c/sup\u3eC-NMR Solid State Spectroscopy of Various Classes of Coals

The 13C-NMR spectra of various classes of coal obtained in the solid state show two resonances, one of which is assigned to aromatic carbon and the other to aliphatic carbon. The resonances are very broad with the high field resonance centered at about 7 ppm below tetramethylsilane and a low field resonance centered at about 140 ppm below tetramethysilane. Based on our previous solid state 13C-NMR studies of graphite and diamond, the high field resonance is typical of a sp3 carbon whereas the low fields resonance is assigned to a sp2 carbon whereas the low fields resonance is assigned to a sp2 carbon. It is found that the antracitic coals have more aromatic (sp2) carbons than the bituminous, subbituminous and lignite coals. The analytical implications of this technique are briefly discussed

The Solid State \u3csup\u3e13\u3c/sup\u3eC-NMR Spectra of Some Carbides

The utility of NMR spectroscopy to the study of liquids or solids dissolved in liquids is well known. This technique has been used infrequently to studies in the solid state[I,2]. Work has been done on diamond, graphite and coa113-6]. The 13C-NMR of ebony and ivory have been studied by the magic angle technique[7]. The solid state 13C-NMR spectra of graphite and diamond can be interpreted in terms of tetrahedral (sp3) and trigonal planar (sp2) carbon atoms[8]. We now report our investigations using solid state 13C-NMR spectroscopy to study various types of carbides

ken

From the beginning, the world of game-playing by machine has been fortunate in attracting contributions from the leading names of computer science. Charles Babbage, Konrad Zuse, Claude Shannon, Alan Turing, John von Neumann, John McCarthy, Alan Newell, Herb Simon and Ken Thompson all come to mind, and each reader will wish to add to this list. Recently, the Journal has saluted both Claude Shannon and Herb Simon. Ken’s retirement from Lucent Technologies’ Bell Labs to the start-up Entrisphere is also a good moment for reflection

Analytical investigations of laminar separations using the ''Crocco-Lees mixing parameter'' method

Analytical studies of laminar separations using Crocco-Lees mixing parameter metho

Test techniques for evaluating flight displays

The rapid development of graphics technology allows for greater flexibility in aircraft displays, but display evaluation techniques have not kept pace. Historically, display evaluation has been based on subjective opinion and not on the actual aircraft/pilot performance. Existing electronic display specifications and evaluation techniques are reviewed. A display rating technique analogous to handling qualities ratings was developed and is recommended for future evaluations. The choice of evaluation pilots is also discussed and the use of a limited number of trained evaluators is recommended over the use of a large number of operational pilots

Space-efficient indexing of endgame tables for chess

Chess endgame tables should provide efficiently the value and depth of any required position during play. The indexing of an endgame’s positions is crucial to meeting this objective. This paper updates Heinz’ previous review of approaches to indexing and describes the latest approach by the first and third authors. Heinz’ and Nalimov’s endgame tables (EGTs) encompass the en passant rule and have the most compact index schemes to date. Nalimov’s EGTs, to the Distance-to-Mate (DTM) metric, require only 30.6 × 109 elements in total for all the 3-to-5-man endgames and are individually more compact than previous tables. His new index scheme has proved itself while generating the tables and in the 1999 World Computer Chess Championship where many of the top programs used the new suite of EGTs

A Solid State \u3csup\u3e13\u3c/sup\u3eC-NMR Study of Diamonds and Graphites

The 13C-NMR spectra of gem quality and industrial diamonds show two resonances with the more intense resonance at high field. Two resonances are also shown in 13C-NMR spectra of various graphites; however, the low field resonance is of greater intensity than the high field resonance in the graphites. The resonances are very broad and they are assigned to graphite type (sp2) carbon and diamond type (sp3) carbon