Previous Work Clustering

To choose architectural partitions, APARTY uses a unique multistage clustering technique. Multi-stage clustering, which is described in Section 4.3, is based on an established clustering algorithm that has 

For more details on this clustering algorithm, see [Johnson67]. 

Rajan used the same similarity parameters as McFarland in an early version of SUGAR, but used them to measure inter-procedural as well as intra-procedural relationships. The operator groups produced 

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Previous work in our group had shown the power of self-organizing neural networks for the projection of high-dimensional datasets into two dimensions while preserving clusters present in the high-dimensional space even after projection [27]. In effect, 2D maps of the high-dimensional data are obtained that can show clusters of similar objects. 

Dendrimer templated Pt-Au catalysts are also active for the selective catalytic reduction of NO by propylene in the presence of excess O2. In addition to its commercial importance, this reaction is particularly interesting for the Pt-Au system. Previous work with cluster-derived Pt-Au catalysts has demonstrated that this reaction exhibits structure sensitivity, suggesting that it may be possible to use it as a structural probe for Pt based catalysts. ... 

In this subsection we investigate the adsorption of O2 molecules on neutral Aun clusters with 5cluster substrate, which is chosen among the equilibrium structures of pure An clusters obtained in a previous work . We do not consider initial configurations with two separated O atoms. Thus, O2 dissociative adsorption is obtained only when that process occurs without any barrier. 

Previous work (11-16) has regarded the negative ion SSIMS spectra as relatively uninformative in comparison to positive ion emission. In this study we confirm very recent findings (18) that important information on side chain and backbone structure may indeed be obtained on analysis of the negative cluster ions which both compliments and clarifies information previously only obtainable from positive ion emission. The negative ion SSIMS spectrum shows a large amount of structural information without the confusing presence of intense C H species which abound in the positive ion spectrum. 

Ab initio calculations of [(H03T0T(0H)3]" clusters were also performed by Sauer and Engelhardt (119), whose formulation of the problem was quite similar to that of the previous works. The only distinction in the scheme of computations was that the charge compensation was achieved by means of a crystal field simulated by six point charges q [q = e or e for (Si, Al)- and (Al, Al)2-, respectively]. In addition, the alternative structures with point charges q = e, 2e located at the cation positions in a zeolite were also considered. 

Table I summarizes the results of our calculations, along with previous work on two- and three-iron clusters. As we have noted before, the general tendency of the Xa scattered wave method is to overestimate J for example, the experimental estimate of J for the oxidized linear three-iron cluster (18) is 300 cm, about 45% lower than the value we estimate. Estimates for J in oxidized two-iron clusters are smaller than our estimates by similar amounts (6). We expect the behavior to be about the same for the reduced species, but that the qualitative trends should be correct. We have discussed the results of the oxidized three-iron clusters in our previous paper (9), showing that the Xa calculations predict a ground state for the...

Charge transfer between the constituent atoms is thought to be important for the stability of crystal structures. In our previous work [1] the transferred charge in the case of ARNi and AlNia was estimated from Auger parameter measurements. In the present study, performing non relativistic spin-restricted and spin-unrestricted DVY molecular orbital calculations of model cluster we obtain more detailed information on the particular orbitals involved in the charge transfer processes. 

The vaporization of carbon has been studied previously in a very similar apparatus. In that work clusters of up to 190 carbon atoms were observed and it was noted that for clusters of more than 40 atoms, only those containing an even number of atoms were observed. In the mass spectra displayed in ref. 6, the Cso peak is the largest for cluster sizes of >40 atoms, but it is not completely dominant. We have recently re-examined this system and found that under certain clustering conditions the C o peak can be made about 40 times larger than neighbouring clusters. 

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