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1.
Alzate Carlos Suykens Johan A. K. 《IEEE transactions on pattern analysis and machine intelligence》2010,32(2):335-347
A new formulation for multiway spectral clustering is proposed. This method corresponds to a weighted kernel principal component analysis (PCA) approach based on primal-dual least-squares support vector machine (LS-SVM) formulations. The formulation allows the extension to out-of-sample points. In this way, the proposed clustering model can be trained, validated, and tested. The clustering information is contained on the eigendecomposition of a modified similarity matrix derived from the data. This eigenvalue problem corresponds to the dual solution of a primal optimization problem formulated in a high-dimensional feature space. A model selection criterion called the Balanced Line Fit (BLF) is also proposed. This criterion is based on the out-of-sample extension and exploits the structure of the eigenvectors and the corresponding projections when the clusters are well formed. The BLF criterion can be used to obtain clustering parameters in a learning framework. Experimental results with difficult toy problems and image segmentation show improved performance in terms of generalization to new samples and computation times. 相似文献
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Carlos A. Alzate Carlos F. Valdés Arturo Berrio Javier De La Cruz Carlos A. Londoño 《Fuel》2009,88(3):437-529
A pelletization process was designed which produces cylindrical pellets ∼8 mm in length and 4 mm in diameter. These ones were manufactured using a blend of Pinus Patula and Cypress sawdust and coal in proportions of 0%, 5%, 10%, 20%, and 30% v/v of coal of rank sub-bituminous extracted from the Nechí mine (Amagá-Antioquia). For this procedure, sodium carboxymethyl cellulose (CMC) was used as binder at three different concentrations. The co-gasification experiments were carried out with two kinds of mixtures, the first one was composed of granular coal and pellets of 100% wood and the second one was composed of pulverized wood and granular coal pellets. All samples were co-gasified with steam by using an electrical heated fluidized-bed reactor, operating in batches, at 850 °C. The main components of the gaseous product were H2, CO, CO2, CH4, and N2 with approximate quantities of 59%, 6.0%, 20%, 5.0%, and 9.0% v/v, respectively, and the higher heating values ranged from between 7.1 and 9.5 MJ/Nm3. 相似文献
4.
Salazar Alzate BC Montoya Campuzano OI Sepúlveda Valencia JU 《Archivos latinoamericanos de nutrición》2005,55(4):350-353
The objective of this research was to test the viability of a native isolate of Lactobacillus brevis in two fermented milky drinks: a drink without prebiotic ingredient and another drink with oat flour (0.5%, p/v) as prebiotic ingredient. The viability of L. brevis was tested at 7, 14, and 21 after inoculation. Drink pH and lactic acid concentration was measured as a function of time (2, 7, 14, and 21 days after inoculation). The isolate was viable in both drinks because its counting plates was higher than 10(6) CFU/mL until day 21st. Between the 7th and 14th day, the rate of growth was higher in the drink that included oat flour, however, at the day 21st the colony density was similar in both drinks. 相似文献
5.
Yeudy F. Vargas Alzate Lluis G. Pujades Beneit Alex H. Barbat Jorge E. Hurtado Gomez Sergio A. Diaz Alvarado Diego A. Hidalgo Leiva 《Structure and Infrastructure Engineering》2018,14(6):817-829
Most of buildings and structures are usually projected according to two main axes. However, the geographical position of these buildings varies randomly. Such random distributions of the azimuthal positions of structures, in most of the cities, generally, are not accounted for when assessing their seismic risk; certainly, the direction of the seismic loads is another highly random variable. Moreover, an additional important source of uncertainty is related to the structural response, mainly due to the random character of the mechanical properties. There is a consensus that uncertainties must be considered for adequately assessing the seismic risk of structures, but these directionality effects have not been deeply explored so far. In this article, the influence of the high uncertainty involved in these input variables on the expected seismic damage is analysed. Thus, an actual earthquake, which affected the southern part of Spain, is studied. Notably, damages on a group of affected buildings, located close to the epicentre, are analysed and discussed in detail. The results show that the influence of the random azimuthal position of structures is an important source of uncertainty and that it should be taken into account when estimating the expected seismic risk in urban areas. 相似文献
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Synthesis and characterization of quaternary PtRuIrSn/C electrocatalysts for direct ethanol fuel cells 总被引:1,自引:0,他引:1
K. Fatih V. Neburchilov V. Alzate R. Neagu H. Wang 《Journal of power sources》2010,195(21):7168-10631
To find a more durable anode with high performance for direct ethanol fuel cells (DEFCs), the present study investigates a series of quaternary electrocatalysts, Pt30Ru30Ir40−xSnx/C (wt.%), for the ethanol electro-oxidation reaction (EOR). The carbon-supported Pt30Ru30Ir40−xSnx/C electrocatalysts were prepared by a known impregnation-reduction (borohydride) method. The microstructure and chemical composition were determined by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). The activity of the electrocatalysts for EOR was compared to commercial Pt67Ru33/C (HISPEC5000) using linear sweep voltammetry (LSV) based on similar Pt loading. The results of this study show that electrocatalyst composition with 10 and 20% Ir (wt.%) exhibit higher electrocatalytic activity than the commercial PtRu electrocatalyst. The single fuel cell testing at 90 °C comparing Pt30Ru30Ir40−xSnx/C to commercial Pt67Ru33/C and Pt83Sn17/C anodes showed an enhancement of Pt activity (normalized to Pt loading) in the following order: Pt30Ru30Ir10Sn30 > Pt30Ru30Sn40 ≥ Pt30Ru30Ir40 ≥ Pt83Sn17 > Pt67Ru33. After a long-term performance test, the activity changed to the following order: Pt30Ru30Ir10Sn30 > Pt30Ru30Ir40 > Pt30Ru30Sn40 > Pt83Sn17 > Pt67Ru33. Pt30Ru30Ir10Sn30/C exhibited both a higher performance with a specific power density of 29 mW mgPt−1 without O2 backpressure at the cathode and an excellent long-term stability in a DEFC operating at 90 °C. 相似文献
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A. Alzate M.C. Pérez-Conde A.M. Gutiérrez C. Cámara 《International Dairy Journal》2010,20(11):761-769
The suitability of Se-enriched fermented milk as a food product for humans has been studied and sensory features, survival of microorganisms in the presence of selenium and Se bioaccessibility are presented. Sensory features and the number of colonies of microorganisms observed until the 4th week after fermentation were not affected at Se concentration levels below 2 μg g?1. To investigate bioaccessible selenium-containing compounds in selenized fermented milk, total Se was quantified after in vitro gastrointestinal digestion. Results showed that 76 ± 3% Se was extracted after gastrointestinal digestion and 24 ± 6% remained in the insoluble residue. To identify the main species of bioaccessible Se of low molecular weight (MW) generated during gastrointestinal digestion, liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS) was used. Results showed that identified selenocompounds were smaller than 1.5 kDa, with selenocystine and Se-methylselenocysteine being the most abundant compounds present in the extracts. 相似文献
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Miguel A. Toro Pedro A. Sánchez‐Murcia Dr. David Moreno Marta Ruiz‐Santaquiteria Prof. Dr. Juan Fernando Alzate Dr. Ana Negri Prof. Dr. María‐José Camarasa Prof. Dr. Federico Gago Dr. Sonsoles Velázquez Prof. Dr. Antonio Jiménez‐Ruiz 《Chembiochem : a European journal of chemical biology》2013,14(10):1212-1217
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Carlos Montalbán Turon Yeudy F. Vargas Alzate 《The Structural Design of Tall and Special Buildings》2023,32(5-6):e1997
This paper presents a new approach to the project of steel buildings, mainly focused on the architectural, structural, and seismic design of stairs. The objective is to design a structural stair system capable of controlling seismic damage and contributing to the bracing system of the building. The article begins with a review of the seismic standard (ATC, FEMA, and EC8) on which the current design criteria for new buildings with stairs are based. The research is based on two spatial building models (A–B) with the same bracing elements but placed differently. Reference Model A follows classical design approaches. It means, stairs are considered nonstructural elements that do not influence the seismic behavior of the building. This structure corresponds to typical braced frames (IV-CBF and EBF) according to EC8. Model B includes a stair system designed to help control the effects of inter-story drifts and inertia forces. In this case, the same bracing elements of Model A were integrated into the stair structure of Model B. A comparative seismic behavior analysis of typically braced frames (A) versus specially braced stairs (B) is presented. The research was based on the static nonlinear (pushover) analysis and the capacity spectrum method (ATC-40) according to the seismic performance levels (FEMA) and damage limitation (EC8). Finally, the braced stairs was verified via nonlinear time-history analysis in order to better capture the structural safety of the evacuation routes and their influence on the behavior of the building. This deterministic analysis of the braced stairs verified satisfactory results compared to reference bracing systems. 相似文献
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Marcela Mejia Néstor Peña Jose L. Muñoz Oscar Esparza Marco Alzate 《Ad hoc Networks》2012,10(7):1379-1398
The scarce resources of a mobile ad hoc network (MANET) should not be wasted attending selfish nodes (those nodes that use resources from other nodes to send their own packets, without offering their own resources to forward other nodes’ packets). Thus, rational nodes (those nodes willing to cooperate if deemed worthy) must detect and isolate selfish nodes in order to cooperate only among themselves. To achieve this purpose, in this paper we present a new game theoretic trust model called DECADE (Distributed Emergent Cooperation through ADaptive Evolution). The design of DECADE is shown by first, analyzing a simple case of packet forwarding between two nodes, and then the results are extended to bigger networks. In DECADE, each node seeks individually to maximize its chance to deliver successfully their own packets, so that the cooperation among rational nodes and the isolation of selfish nodes appear as an emergent collective behavior. This behavior emerges as long as there is a highly dynamic interaction among nodes. So, for those cases where the mobility alone does not suffice to provide this interaction, DECADE includes a sociability parameter that encourages nodes to interact among them for faster learning and adaptability. Additionally, DECADE introduces very low overhead on computational and communication resources, achieving close to optimal cooperation levels among rational nodes and almost complete isolation of selfish nodes. 相似文献