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排序方式: 共有195条查询结果,搜索用时 15 毫秒
81.
Martins J.E. Branco P.J.C. Pires A.J. Dente J.A. 《Fuzzy Systems, IEEE Transactions on》2001,9(1):68-87
Drive systems today determine the productivity and quality of industrial processes. However, they exhibit considerable complexities related with their behavior as large uncertainties at a structure and parameter levels, multidimensionality, and strong mutual interactions. This paper aims to analyze common features, and the potential, but also the drawbacks that fuzzy logic and formal language theories show when used for recognition of patterns in experimental drives. Two prototype systems are used: an electrohydraulic drive and an induction motor drive. We underline the similarities and various aspects of the recognition methodologies, despite their use on different systems. A set of experimental learning situations with critical effects on their performance are presented and discussed 相似文献
82.
Gardenio Diogo Pimentel Da Silva Alessandra Magrini Maurício Tiomno Tolmasquim David Alves Castelo Branco 《影响评估与项目评价》2013,31(6):503-515
ABSTRACTProcurement auctions have been the main mechanism to ensure the deployment of utility-scale solar photovoltaic installations (USSPVI) in Brazil. To participate in the auction, investors must comply with all established requirements. In the solar case, the criteria incorporate State environmental licensing regulations (EL). The procurement auctions are a nationwide competition whereas the environmental licensing for those projects are under state jurisdiction. The lack of national guidance to licensing USSPVI might cause significant movement of projects to States whose EL procedures require fewer studies. This work examines the role of environmental licensing in the energy planning for USSPVI in Brazil. Analysing the 27 state regulations establishing the screening requirements that subject EIA to USSPVI, there are uneven threshold criteria to determine whether the plant will go through simplified licensing or regular process. There is also a need for studies tackling strategic environmental assessment for wind and solar expansion in Brazil. Specifically, incorporation of community concerns, public participation, and environmental constraints into the early stages of decision-making to prevent impacts and conflicts. 相似文献
83.
84.
Maria Carolina S. Soares Marcelo M. Marinho Vera L. M. Huszar Christina W. C. Branco Sandra M. F. O. Azevedo 《Lakes & Reservoirs: Research and Management》2008,13(4):257-269
Although reservoirs are similar to natural lakes in many respects, such driving forces as water retention time and watershed features can play important roles in the limnology of manmade lakes. With the goal of investigating how these factors influence the limnology of tropical reservoirs, physical and chemical variables were measured at four sampling sites in two reservoirs in southern Brazil, from June 2002 to June 2003. Funil Reservoir is located in one of the most-populated areas in the country, in the Paraíba do Sul river basin, which drains and drastically influences the water quality of the reservoir. In contrast, Lajes Reservoir is located in a well-preserved area, with its water retention time varying from six to 30 times longer than for Funil Reservoir. Funil Reservoir is a turbid (median euphotic zone = 4.3 m), eutrophic reservoir (median total phosphorus (TP) = 3.1 µm ), with a high phytoplankton biomass (median chlorophyll-a concentration = 10.0 µg L−1). In contrast, Lajes Reservoir is a transparent (median euphotic zone = 9.2 m), mesotrophic water system (median TP = 1.0 µm ), with a low phytoplankton biomass (median chlorophyll-a = 1.9 µg L−1). Both reservoirs were stratified during the summer months, but isothermy was only observed in Funil Reservoir. Because of its short water retention time, Funil Reservoir is a much more dynamic system than Lajes Reservoir, with a pronounced temporal pattern related to changes in its water column and its phytoplankton biomass. Spatial heterogeneity is more evident in Lajes Reservoir, mainly as a consequence of its location in a preserved area, long water retention time and the presence of net cages for fish culture in the waterbody. The typical spatial zonation found in reservoirs, related to nutrient sedimentation and light availability, however, is more evident in Funil Reservoir than in Lajes Reservoir. Despite the similarities between these two water systems, which are in the same geographical region with similar climate, and are comparable in size, the distinct watershed features and water retention time are responsible for marked differences between these reservoirs. 相似文献
85.
The development of flooring systems with improved durability and higher speed of construction has, in recent years, led to the study of new structural solutions. This paper presents the results of a study of an innovative solution for floors of buildings, with glass fibre reinforced polymer (GFRP) pultruded profiles connected to concrete elements, with either steel bolts or an epoxy adhesive layer. Shear connection tests were first conducted on GFRP I-profiles connected to concrete, using both shear connection systems. The results of those tests were then used to design simply supported beams with a GFRP–concrete hybrid cross-section, which were tested in bending with different spans and load arrangements, comprising two alternative shear connection systems. The experimental programme included also investigations on the strength of different configurations of supports of hybrid beams. In order to better understand some of the experimental results, namely the debonding mechanisms observed at the interface of hybrid beams with bonded shear connection systems, numerical analyses were performed to investigate the stress state at the interfaces. Experimental and numerical investigations showed the viability of using GFRP–concrete hybrid cross-sections in floors of buildings, either for rehabilitation or for new constructions, and proved that adequate constructive detailing can significantly improve the performance of the proposed system. 相似文献
86.
A. S. Fragoso M. B. Silva C. P. de Melo J. L. A. Aguiar C. G. Rodrigues P. L. de Medeiros J. F. Branco Junior C. A. S. Andrade M. D. L. Oliveira 《Journal of materials science. Materials in medicine》2014,25(1):229-237
It is of current interest the identification of appropriate matrices for growing mesenchymal stem cells (MSC). These cells are able not only to regenerate themselves but also to differentiate into other type of functional cells, and so they have been extensively used in tissue engineering. In this work, we have evaluated the use of electric impedance spectroscopy (EIS) to follow the adhesion of MSC from Wharton’s jelly of the human umbilical cord (hWJMSC) on sugarcane biopolymers (SCB). Impedance spectra of the systems were obtained in the frequency range of 102–105 Hz. An EIS investigation showed that when deposited on a metallic electrode SCB films prevent the passage of electrons between the solution and the metallic interface. The impedance spectra of hWJMSCs adhered on SCB revealed that there is a significant increase in the magnitude of the impedance when compared to that of pure SCB. The corresponding resistance (real part of the impedance) was even higher for the SCB–hWJMSC system than for SCB without cells on their surface, in an indication of an increased blockage to the electron transfers. The resistance charge transfer is extracted by curve-fitting the impedance spectra to an equivalent circuit model. Also, a shift of the phase angle to higher frequencies was obtained for SCB–hWJMSC system as a result from hWJMSC adhesion. Our study demonstrates that EIS is an appropriate method to evaluate the adhesion of MSC. SCB can be considered as a promising biomaterial for tissue engineering. 相似文献
87.
Jorge M. Branco Paulo J.S. Cruz Maurizio Piazza 《Construction and Building Materials》2009,23(1):400-410
This work intends to assess the accuracy of the methodology proposed in the Eurocode 5 for laterally loaded nailed timber-to-concrete connections. First, the adequacy of the methodology proposed by Eurocode 5 for the dowel-type fasteners is analyzed and discussed, using timber elements from Pinus pinaster Ait. Square and round smooth nails have been used, initially on push-out tests of single and double shear dowel-type connections. Later, a similar investigation is carried out on timber–concrete connections, using the same kind of fasteners (nails), in single shear, wood species and experimental procedure. The use and the influence of permanent formwork are also investigated. As a result, comparisons between the values obtained for the load-carrying capacity and the slip modulus using the analysis provided by the Eurocode 5, when existing, and the experimental results are presented. 相似文献
88.
Ricardo F Branco Julio C dos Santos Boutros F Sarrouh Juan D Rivaldi Adalberto Pessoa Jr Silvio S da Silva 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(3):326-330
BACKGROUND: Xylitol is a sugar alcohol (polyalcohol) with many interesting properties for pharmaceutical and food products. It is currently produced by a chemical process, which has some disadvantages such as high energy requirement. Therefore microbiological production of xylitol has been studied as an alternative, but its viability is dependent on optimisation of the fermentation variables. Among these, aeration is fundamental, because xylitol is produced only under adequate oxygen availability. In most experiments with xylitol‐producing yeasts, low oxygen transfer volumetric coefficient (KLa) values are used to maintain microaerobic conditions. However, in the present study the use of relatively high KLa values resulted in high xylitol production. The effect of aeration was also evaluated via the profiles of xylose reductase (XR) and xylitol dehydrogenase (XD) activities during the experiments. RESULTS: The highest XR specific activity (1.45 ± 0.21 U mgprotein?1) was achieved during the experiment with the lowest KLa value (12 h?1), while the highest XD specific activity (0.19 ± 0.03 U mgprotein?1) was observed with a KLa value of 25 h?1. Xylitol production was enhanced when KLa was increased from 12 to 50 h?1, which resulted in the best condition observed, corresponding to a xylitol volumetric productivity of 1.50 ± 0.08 gxylitol L?1 h?1 and an efficiency of 71 ± 6.0%. CONCLUSION: The results showed that the enzyme activities during xylitol bioproduction depend greatly on the initial KLa value (oxygen availability). This finding supplies important information for further studies in molecular biology and genetic engineering aimed at improving xylitol bioproduction. Copyright © 2008 Society of Chemical Industry 相似文献
89.
Linda Lee Ho Antonio Fernando Branco Costa 《The International Journal of Advanced Manufacturing Technology》2009,43(7-8):744-755
In this paper, three single-control charts are proposed to monitor individual observations of a bivariate Poisson process. The specified false-alarm risk, their control limits, and ARLs were determined to compare their performances for different types and sizes of shifts. In most of the cases, the single charts presented better performance rather than two separate control charts (one for each quality characteristic). A numerical example illustrates the proposed control charts. 相似文献
90.
Costa Branco P.J. Dente J.A. 《IEEE transactions on systems, man and cybernetics. Part C, Applications and reviews》2000,30(3):305-316
Drive systems are usually modeled using a mathematical characterization of their physical phenomena. However, the difficulty in establishing a relevant model representation, in particular for electro-hydraulic systems, makes important the search for other modeling mechanisms that allow the combination of previously compiled system's knowledge with acquired experimental information. This paper, divided into two parts, describes the potential and possible drawbacks of integrating fuzzy learning mechanisms into a drive system that includes an electro-hydraulic actuator. First, experimental verification of the actuator's fuzzy modeling is presented in Part I of the paper, where the variable selection problem and the performance of the learning algorithm are discussed. In Part II, extensive experimental results employing the extracted fuzzy model and associated learning algorithm are presented. The feasibility and effectiveness of integrating fuzzy learning mechanisms into the actuator's control is also discussed. 相似文献