2,634 research outputs found
Easily labelling hierarchical document clusters.
One of the problems of automatic models that generate topic taxonomies is the process of creating the most significant term list that discriminates each document group. In this paper, a new method to label document hierarchical clusters is proposed, which is completely independent from the clustering method. This method automatically decides the number of the words in each label list, avoids word repetitions in a tree branch and provides a kind of cutting for the cluster tree. The obtained results were tested as search queries in a retrieval process and showed a very good performance. Additionally, the use of the method was experimented by some specialists in the text collection domain, trying to evaluate their understanding and expectations over the results
Chemical composition of the scent from living flowers of Temnadenia odorifera (Vell.) J. F. Morales (Apocynaceae).
IFF. P5-S3. 8 a 12 de maio
Unified radio and network control across heterogeneous hardware platforms
Experimentation is an important step in the investigation of techniques for handling spectrum scarcity or the development of new waveforms in future wireless networks. However, it is impractical and not cost effective to construct custom platforms for each future network scenario to be investigated. This problem is addressed by defining Unified Programming Interfaces that allow common access to several platforms for experimentation-based prototyping, research, and development purposes. The design of these interfaces is driven by a diverse set of scenarios that capture the functionality relevant to future network implementations while trying to keep them as generic as possible. Herein, the definition of this set of scenarios is presented as well as the architecture for supporting experimentation-based wireless research over multiple hardware platforms. The proposed architecture for experimentation incorporates both local and global unified interfaces to control any aspect of a wireless system while being completely agnostic to the actual technology incorporated. Control is feasible from the low-level features of individual radios to the entire network stack, including hierarchical control combinations. A testbed to enable the use of the above architecture is utilized that uses a backbone network in order to be able to extract measurements and observe the overall behaviour of the system under test without imposing further communication overhead to the actual experiment. Based on the aforementioned architecture, a system is proposed that is able to support the advancement of intelligent techniques for future networks through experimentation while decoupling promising algorithms and techniques from the capabilities of a specific hardware platform
Dirac-Surface-State-Dominated Spin to Charge Current Conversion in the Topological Insulator Films at Room Temperature
We report the spin to charge current conversation in an intrinsic topological
insulator (TI) film at room temperature. The spin
currents are generated in a thin layer of permalloy (Py) by two different
processes, spin pumping (SPE) and spin Seebeck effects (SSE). In the first we
use microwave-driven ferromagnetic resonance of the Py film to generate a SPE
spin current that is injected into the TI layer in
direct contact with Py. In the second we use the SSE in the longitudinal
configuration in Py without contamination by the Nernst effect made possible
with a thin NiO layer between the Py and layers.
The spin-to-charge current conversion is attributed to the inverse Edelstein
effect (IEE) made possible by the spin-momentum locking in the electron Fermi
contours due to the Rashba field. The measurements by the two techniques yield
very similar values for the IEE parameter, which are larger than the reported
values in the previous studies on topological insulators.Comment: 18 pages and 7 figure
Comparison between GC-MS-SIM and GC-ECD for the determination of residues of organochlorine and organophosphorus pesticides in Brazilian citrus essential oils.
Óleos essenciais cÃtricos brasileiros (mandarina, laranja, limão, bergamota e tangerina) foram analisados a fim de determinar resÃduos de pesticidas organoclorados (aldrin, clordano, dieldrin e dicofol) e organofosforados (clorpirifós metÃlico, dimetoato, metidationa e paration metÃlico). Um estudo comparativo entre cromatografia gasosa acoplada a espectrometria de massas em modo de monitoramento seletivo de Ãons (CG-EM-MSI) e cromatografia gasosa com detector por captura de elétrons (CG-DCE) foi realizado usando extração em fase sólida (EFS) com fase Florisil® para pré-concentração dos pesticidas. A recuperação média dos pesticidas foi de 71 a 83% por CG-EM-MSI e de 99 a 104% por CG-DCE. O limite de quantificação foi de 0,93 a 3,93 mg L-1 por CG-EM-MSI e de 0,09 a 0,12 mg L-1 por CG-DCE. Quinze amostras comerciais de óleos essenciais cÃtricos brasileiros foram analisadas e seis amostras apresentaram contaminação com valores acima do limite máximo de resÃduos (LMR) permitido pelo Codex Alimentarius
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