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181.
Clustering Rules: A Comparison of Partitioning and Hierarchical Clustering Algorithms 总被引:1,自引:0,他引:1
A. P. Reynolds G. Richards B. de la Iglesia V. J. Rayward-Smith 《Journal of Mathematical Modelling and Algorithms》2006,5(4):475-504
Previous research has resulted in a number of different algorithms for rule discovery. Two approaches discussed here, the ‘all-rules’ algorithm and multi-objective metaheuristics, both result in the production of a large number of partial classification rules, or ‘nuggets’, for describing different subsets of the records in the class of interest. This paper describes the application of a number of different clustering algorithms to these rules, in order to identify similar rules and to better understand the data. 相似文献
182.
F. P. La Mantia 《Rheologica Acta》1977,16(3):302-308
Summary Several existing data of non-linear viscoelasticity of amorphous polymers aboveT
g are here interpreted by assuming that the free volume changes during the motion. Equations of a stress-temperature equivalence are suggested which favorably compare with the data. It is also shown that the volume variations are sufficiently small to have escaped observation.
With 9 figures 相似文献
Zusammenfassung Verschiedene vorliegende Meßergebnisse bezüglich des nicht-linear viskoelastischen Verhaltens von amorphen Polymeren oberhalbT g werden mit Hilfe der Annahme interpretiert, daß das freie Volumen sich bei der Bewegung ändert. Es werden dazu Gleichungen für die Spannungs-Temperatur-Äquivalenz in Ansatz gebracht, die eine gute Anpassung an die Meßdaten ergeben. Ebenfalls wird gezeigt, daß die Volumenänderungen hierbei so klein bleiben, daß sie sich der Beobachtung haben entziehen können.
With 9 figures 相似文献
183.
184.
Highly Stereoselective Synthesis of Natural‐Product‐Like Hybrids by an Organocatalytic/Multicomponent Reaction Sequence 下载免费PDF全文
M. Sc. Radell Echemendía M. Sc. Alexander F. de La Torre M. Sc. Julia L. Monteiro M. Sc. Michel Pila Prof. Dr. Arlene G. Corrêa Prof. Dr. Bernhard Westermann Prof. Dr. Daniel G. Rivera Prof. Dr. Márcio W. Paixão 《Angewandte Chemie (International ed. in English)》2015,54(26):7621-7625
In an endeavor to provide an efficient route to natural product hybrids, described herein is an efficient, highly stereoselective, one‐pot process comprising an organocatalytic conjugate addition of 1,3‐dicarbonyls to α,β‐unsaturated aldehydes followed by an intramolecular isocyanide‐based multicomponent reaction. This approach enables the rapid assembly of complex natural product hybrids including up to four different molecular fragments, such as hydroquinolinone, chromene, piperidine, peptide, lipid, and glycoside moieties. The strategy combines the stereocontrol of organocatalysis with the diversity‐generating character of multicomponent reactions, thus leading to structurally unique peptidomimetics integrating heterocyclic, lipidic, and sugar moieties. 相似文献
185.
Electrodes/Electrolyte Interfaces in the Presence of a Surface‐Modified Photopolymer Electrolyte: Application in Dye‐Sensitized Solar Cells 下载免费PDF全文
Dr. Adriano Sacco Federico Bella Stefano De La Pierre Dr. Micaela Castellino Dr. Stefano Bianco Prof. Roberta Bongiovanni Prof. Candido Fabrizio Pirri 《Chemphyschem》2015,16(5):960-969
Since hundreds of studies on photoanodes and cathodes show that the electrode/electrolyte interfaces represent a key aspect at the base of dye‐sensitized solar cell (DSSC) performances, it is reported here that these interfaces can be managed by a smart design of the spatial composition of quasi‐solid electrolytes. By means of a cheap, rapid, and green process of photoinduced polymerization, composition‐tailored polymer electrolyte membranes (PEMs) with siloxane‐enriched surfaces are prepared, and their properties are thoroughly described. When assembled in DSSCs, the interfacial action promoted by the composition‐tailored PEMs enhances the photocurrent and fill factor values, thus increasing the global photovoltaic conversion efficiency with respect to the non‐modified PEMs. Moreover, the presence of the siloxane‐chain‐enriched surface increases the hydrophobicity and reduces the water vapor permeation into the device, thus enhancing the cell′s durability. 相似文献
186.
Dr. Alessandra Alberti Dr. Ioannis Deretzis Dr. Giovanna Pellegrino Dr. Corrado Bongiorno Dr. Emanuele Smecca Dr. Giovanni Mannino Dr. Filippo Giannazzo Prof. Guglielmo Guido Condorelli Dr. Nobuya Sakai Prof. Tsutomu Miyasaka Dr. Corrado Spinella Dr. Antonino La Magna 《Chemphyschem》2015,16(14):3064-3071
We investigate the degradation path of MAPbI3 (MA=methylammonium) films over flat TiO2 substrates at room temperature by means of X‐ray diffraction, spectroscopic ellipsometry, X‐ray photoelectron spectroscopy, and high‐resolution transmission electron microscopy. The degradation dynamics is found to be similar in air and under vacuum conditions, which leads to the conclusion that the occurrence of intrinsic thermodynamic mechanisms is not necessarily linked to humidity. The process has an early stage, which drives the starting tetragonal lattice in the direction of a cubic atomic arrangement. This early stage is followed by a phase change towards PbI2. We describe how this degradation product is structurally coupled with the original MAPbI3 lattice through the orientation of its constituent PbI6 octahedra. Our results suggest a slight octahedral rearrangement after volatilization of HI+CH3NH2 or MAI, with a relatively low energy cost. Our experiments also clarify why reducing the interfaces and internal defects in the perovskite lattice enhances the stability of the material. 相似文献
187.
Maurizio Casalino Giuseppe Coppola Richard M. De La Rue Dylan F. Logan 《Laser \u0026amp; Photonics Reviews》2016,10(6):895-921
Silicon‐based technologies provide an ideal platform for the monolithic integration of photonics and microelectronics. In this context, a variety of passive and active silicon photonic devices have been developed to operate at telecom and datacom wavelengths, at which silicon has minimal optical absorption ‐ due to its bandgap of 1.12 eV. Although in principle this transparency window limits the use of silicon for optical detection at wavelengths above 1.1 μm, in recent years tremendous advances have been made in the field of all‐silicon sub‐bandgap photodetectors at telecom and datacom wavelengths. By taking advantage of emerging materials and novel structures, these devices are becoming competitive with the more well‐established technologies, and are opening new and intriguing perspectives. In this paper, a review of the state‐of‐the‐art is presented. Devices based on defect‐mediated absorption, two‐photon absorption and the internal photoemission effect are reported, their working principles are elucidated and their performance discussed and compared.
188.
189.
Jacopo La Nasa Marco Zanaboni Daniele Uldanck Ilaria Degano Francesca Modugno Hartmut Kutzke Eva Storevik Tveit Biljana Topalova-Casadiego Maria Perla Colombini 《Analytica chimica acta》2015
Modern oil paints, introduced at the beginning of the 20th century, differ from those classically used in antiquity in their chemical and compositional features. The main ingredients were still traditional drying oils, often used in mixtures with less expensive oils and added with several classes of additives. Consequently, detailed lipid profiling, together with the study of lipid degradation processes, is essential for the knowledge and the conservation of paint materials used in modern and contemporary art. 相似文献
190.
Isotactic polypropylene(i PP) samples obtained by pressure vibration injection molding(PVIM) and conventional injection molding(CIM) were studied by polarized-light microscopy(PLM), respectively. It was found that the alternating bright and dark banded spherulites were generated in the transitional region of PVIM parts. It is the first time that the banded spherulites of isotactic polypropylene were observed in polymer processing. What's more, the banded spherulites were proved to be constituted of ?-form crystal by hot stage polarized-light microscopy(HT-PLM) and wide angle X-ray diffraction(WAXD). Morphology of the banded spherulites was also studied by scaning electronical microscopy(SEM). 相似文献