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461.
The most effective technique to enhance performances of multidimensional databases consists in materializing redundant aggregates called views. In the classical approach to materialization, each view includes all and only the measures of the cube it aggregates. In this paper we investigate the benefits of materializing views in vertical fragments, aimed at minimizing the workload response time. We formalize the fragmentation problem as a 0–1 integer linear programming problem, which is then solved by means of a standard integer programming solver to determine the optimal fragmentation for a given workload. Finally, we demonstrate the usefulness of fragmentation by presenting a large set of experimental results based on the TPC-H benchmark. 相似文献
462.
G Ronsisvalle O Prezzavento L Pasquinucci MS Pappalardo A Marrazzo F Vittorio L Carboni S Spampinato 《Canadian Metallurgical Quarterly》1997,52(6-7):471-476
The synthesis and the in vitro receptor affinity for sigma 1 and opiod receptors of the two diastereoisomers of (+)-cis-MPCB namely, (+)-cis-(1'S,2'R)-6,11-Dimethyl-1,2,3,4,5,6 -hexahydro-3-[[2'-(methoxycarbonyl)-2'-phenylcyclopropyl]methyl]-2 ,6 -methano-3-benzazocin-8-ol, (1'S,2'R)6a and (+)-cis-(1'R,2'S)-6,11-Dimethyl-1,2,3,4,5,6-hexahydro-3- [[2-(methoxycarbonyl)-2'-phenylcyclopropyl]methyl]-2,6-methano-3-+ ++benzazocin-8 -ol, (1'R,2'S)6a are reported. Affinities of (1'S,2'R)6a and (1'R,2'S)6a were compared with those of the (-)-cis-diastereoisomers of MPCB(1), and of its p-Cl phenyl derivative CCB(2). The (+)-cis-N-normetazocine derivatives showed higher affinity for the sigma 1 sites, labeled with [3H]-(+)-pentazocine than the corresponding (-)-cis- analogs. In particular, compound (1'S,2'R)6a showed a Ki = 66.7 nM for sigma 1 receptor, associated with a good selectivity for sigma 1 with respect to kappa, mu, delta opioid receptors subtypes (Ki = > 1,000 nM). Analysis of the data seem to support the hypothesis that the (+)-cis-N-normetazocine nucleus posses a specific enantioselectivity for sigma 1 sites, when supporting bulkier N-substituents functionalized with a carboxy ester group. 相似文献
463.
Solder paste is the strategic material for the electronic card assembly process, based on the surface mounting technology.
The paste is a concentrated suspension (50% of volume) of metallic powder in an organic continuous phase and its screening
on the printed circuit board is the first operation of the assembly. The result of the screening depends strongly on the rheological
characteristics of the solder paste but, nevertheless the research activity on this material is so far very poor. In this
paper, an analytical procedure for the rheological characterization is given and the most important rheological parameters,
affecting the screening performance, are shown. 相似文献
464.
Giuseppe Bianchi Vittorio Trecordi 《International Journal of Communication Systems》1994,7(4):265-273
In this paper we outline a simple strategy to manage bandwidth allocation and congestion control and to guarantee service requirements in a multiservice ATM (asynchronous transfer mode) network. We propose a network architecture based on a core network, making available a limited number of quality of service profiles, and an access network, made of edge adapters in charge to match the user's requirements with the network's available quality of service profiles and to shape input traffic to achieve high network throughput. The connection admission rule is presented, and edge adapter architecture and design examples are given. The effectiveness of the scheme is demonstrated by numerical results which report the network utilization performance when the proposed core network policies and edge adapter design apply. 相似文献
465.
466.
This letter introduces the “mode determination” problem relative to a biomodal image corrupted by noise, i.e., the problem of estimating the mean intensity level of each of the two homogeneous regions constituting a bimodal image. The mode determination problem can be seen as a generalization of the threshold determination problem. This generalization is introduced to cope with the low performances of thresholding techniques when dealing with highly noisy images. A mode determination method is proposed, based on the comparison of the histogram of different (averaging) convolutions of the given image. Experimental results are presented showing the performance of the proposed method. 相似文献
467.
Summary Magic Angle Spinning-Cross Polarization (MAS-CP) 13C NMR spectra of four different unsatured resins reticulated with styrene have been measured.Styrene crosslinks may be constituted essentially by dyads or may consist in (styrene) microdomains (n2), depending mainly upon the molar ratio of maleic acid residues in the original unsaturated polyester to styrene.Also in the case of solid unsaturated resins the MAS-CP 13CNMR technique promises to allow structural insights only very difficultly obtainable by more classical indirect means. 相似文献
468.
Cecconi Vittorio Pagano Enrico Perfetto Aldo 《Industry Applications, IEEE Transactions on》1986,(1):25-31
Losses of inverter-fed asynchronous motors and their experimental evaluation are considered. The formal expressions of iron and copper losses are first recalled, and it is shown as they are influenced by the harmonic content of inverter output voltages. Theoretical and experimental values of these losses are then given together with the presentation of the experimental tests used for their determination. A suitable set of tests is then suggested for the determination of the conventional efficiency of inverter-fed asynchronous motors. The content cannot be considered exhaustive on the matter. It represents only a first contributive approach to the standardization of inverter-fed asynchronous motor tests. 相似文献
469.
A model for estimating the peak dynamic response distribution of a nonlinear beam, based on a special class of non-Gaussian stochastic processes, is proposed in this paper. It is shown that the stochastic response of a cantilever beam with geometrically nonlinear behavior can be accurately calibrated with translation processes. Different models to describe the significant bimodal features in the marginal probability density functions of the response time histories are proposed. Finally, two of these models are used to estimate the response peak value distributions and the results are compared. This comparison demonstrates the effects of inaccurate models for the parent response processes on the peaks estimation. 相似文献
470.
Filip Michniewicz Dr. Federica Saletta Jourdin R. C. Rouaen Dr. Rehana V. Hewavisenti Dr. Daniele Mercatelli Dr. Giuseppe Cirillo Dr. Federico M. Giorgi Dr. Toby Trahair Assoc. Prof. David Ziegler Dr. Orazio Vittorio 《ChemMedChem》2021,16(15):2315-2329
Copper is an essential transition metal frequently increased in cancer known to strongly influence essential cellular processes. Targeted therapy protocols utilizing both novel and repurposed drug agents initially demonstrate strong efficacy, before failing in advanced cancers as drug resistance develops and relapse occurs. Overcoming this limitation involves the development of strategies and protocols aimed at a wider targeting of the underlying molecular changes. Receptor Tyrosine Kinase signaling pathways, epigenetic mechanisms and cell metabolism are among the most common therapeutic targets, with molecular investigations increasingly demonstrating the strong influence each mechanism exerts on the others. Interestingly, all these mechanisms can be influenced by intracellular copper. We propose that copper chelating agents, already in clinical trial for multiple cancers, may simultaneously target these mechanisms across a wide variety of cancers, serving as an excellent candidate for targeted combination therapy. This review summarizes the known links between these mechanisms, copper, and copper chelation therapy. 相似文献