254 resultados para three-electrode-integrated sensor
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This paper presents the design and implementation of an embedded soft sensor, i. e., a generic and autonomous hardware module, which can be applied to many complex plants, wherein a certain variable cannot be directly measured. It is implemented based on a fuzzy identification algorithm called ""Limited Rules"", employed to model continuous nonlinear processes. The fuzzy model has a Takagi-Sugeno-Kang structure and the premise parameters are defined based on the Fuzzy C-Means (FCM) clustering algorithm. The firmware contains the soft sensor and it runs online, estimating the target variable from other available variables. Tests have been performed using a simulated pH neutralization plant. The results of the embedded soft sensor have been considered satisfactory. A complete embedded inferential control system is also presented, including a soft sensor and a PID controller. (c) 2007, ISA. Published by Elsevier Ltd. All rights reserved.
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The design, construction, and characterization of a portable opto-coupled potentiostat are presented. The potentiostat is battery-powered, managed by a microcontroller, which implements cyclic voltammetry (CV) using suitable sensor electrodes. Its opto-coupling permits a wide range of current measurements, varying from mA to nA. Two software interfaces were developed to perform the CV measurement: a virtual instrument for a personal computer (PC) and a C-base interface for personal digital assistant (PDA). The potentiostat has been evaluated by detection of potassium ferrocyanide in KCl medium, both with macro and microelectrodes. There was good agreement between the instrumental results and those from commercial equipment.
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We report here the observation, for the first time, of the enhancement of Europium-Tetracycline complex emission in cholesterol solutions. This enhancement was initially observed with the addition of the enzyme cholesterol oxidase, which produces H2O2, the agent driver of the Europium tetracycline complex, to the solution. However, it was found that the enzyme is not needed to enhance the luminescence. A calibration curve was determined, resulting in a simple method to measure the cholesterol quantity in a solution. This method shows that the complex can be used as a sensor to determine cholesterol in biological systems.
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In many engineering applications, the time coordination of geographically separated events is of fundamental importance, as in digital telecommunications and integrated digital circuits. Mutually connected (MC) networks are very good candidates for some new types of application, such as wireless sensor networks. This paper presents a study on the behavior of MC networks of digital phase-locked loops (DPLLs). Analytical results are derived showing that, even for static networks without delays, different synchronous states may exist for the network. An upper bound for the number of such states is also presented. Numerical simulations are used to show the following results: (i) the synchronization precision in MC DPLLs networks; (ii) the existence of synchronous states for the network does not guarantee its achievement and (iii) different synchronous states may be achieved for different initial conditions. These results are important in the neural computation context. as in this case, each synchronous state may be associated to a different analog memory information. (C) 2010 Elsevier B.V. All rights reserved.
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Back in 1970s and 1980s, cogeneration plants in sugarcane mills were primarily designed to consume all bagasse, and produce steam and electricity to the process. The plants used medium pressure steam boilers (21 bar and 300 degrees C) and backpressure steam turbines. Some plants needed also an additional fuel, as the boilers were very inefficient. In those times, sugarcane bagasse did not have an economic value, and it was considered a problem by most mills. During the 1990s and the beginning of the 2000s, sugarcane industry faced an open market perspective, thus, there was a great necessity to reduce costs in the production processes. In addition, the economic value of by-products (bagasse, molasses, etc.) increased, and there was a possibility of selling electricity to the grid. This new scenario led to a search for more advanced cogeneration systems, based mainly on higher steam parameters (40-80 bar and 400-500 degrees C). In the future, some authors suggest that biomass integrated gasification combined cycles are the best alternative to cogeneration plants in sugarcane mills. These systems might attain 35-40% efficiency for the power conversion. However, supercritical steam cycles might also attain these efficiency values, what makes them an alternative to gasification-based systems. This paper presents a comparative thermoeconomic study of these systems for sugarcane mills. The configurations studied are based on real systems that could be adapted to biomass use. Different steam consumptions in the process are considered, in order to better integrate these configurations in the mill. (C) 2009 Elsevier Ltd. All rights reserved.
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Background: The presence of the periodontal ligament (PDL) makes it possible to absorb and distribute loads produced during masticatory function and other tooth contacts into the alveolar process via the alveolar bone proper. However, several factors affect the integrity of periodontal structures causing the destruction of the connective matrix and cells, the loss of fibrous attachment, and the resorption of alveolar bone. Methods: The purpose of this study was to evaluate the stress distribution by finite element analysis in a PDL in three-dimensional models of the upper central incisor under three different load conditions: 100 N occlusal loading at 45 degrees (model 1: masticatory load); 500 N at the incisal edge at 45 degrees (model 2: parafunctional habit); and 800 N at the buccal surface at 90 degrees (model 3: trauma case). The models were built from computed tomography scans. Results: The stress distribution was quite different among the models. The most significant values (harmful) of tensile and compressive stresses were observed in models 2 and 3, with similarly distinct patterns of stress distributions along the PDL. Tensile stresses were observed along the internal and external aspects of the PDL, mostly at the cervical and middle thirds. Conclusions: The stress generation in these models may affect the integrity of periodontal structures. A better understanding of the biomechanical behavior of the PDL under physiologic and traumatic loading conditions might enhance the understanding of the biologic reaction of the PDL in health and disease. J Periodontol 2009;80:1859-1867.
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This work presents for the first time to our knowledge the fabrication and characterization of rib waveguides produced with PbO-GeO(2) (PGO) thin films. The target was manufactured using pure oxides ( 60 PbO-40 GeO(2), in wt%) and amorphous thin films were produced with the RF sputtering technique. PGO thin films present small absorption in the visible and in the near infrared and refractive index of similar to 2.0. The definition of the rib waveguide structure was made using conventional optical lithography followed by plasma etching, performed in a Reactive Ion Etching (RIE) reactor. Light propagation mode in the waveguide structure was analyzed using integrated optic simulation software. Optical loss measurements were performed to determine the propagation loss at 633 nm, for ribs with height of 70 nm and width of 3-5 mu m; experimental values around 2 dB/cm were found for the propagation loss and confirmed the theoretical calculations. The results obtained demonstrate that PGO thin films are potential candidates for application in integrated optics. Published by Elsevier B.V.
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Our aim was to document the benefits of three dimensional finite element model generations from computed tomography data as well as the realistic creation of all oral structures in a patient. The stresses resulting from the applied load in our study did not exceed the structure limitations, suggesting a clinically acceptable physiological condition.
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Captive breeding of peccaries is on the increase in neotropical countries. Few studies, however, have reported behavioural responses of wild animals under farmed conditions. Therefore, the aim of this study was to evaluate the effects of space allowance on the occurrence of social behaviour patterns on farmed collared peccary (Pecan tajacu). We observed three herds of collared peccaries each containing eight acquainted individuals. Using a 3 x 3 Latin square design, herds were allocated, in a random order, to one of the three experimental enclosures, each with a different size. 375, 750 and 1,500 m(2) of total available area, each with three wooden shelters. We recorded all the occurrences of selected positive and agonistic behavioural patterns that occurred 90 min before and during feeding Enclosure size had a significant effect on agonistic patterns of peccaries during feeding, in that more agonistic behaviour was observed in smaller spaces We also found that shelter usage increased as space decreased Differing space allowances, however, did not have an effect on the occurrence of positive interactions that were more frequent before compared to during feeding. We concluded that enclosure size had an effect on the expression of agonistic be and the use of shelters by collared peccaries Thus, animal welfare can be improved by adopting at least 187 5 m(2) per peccary. In addition, our study also confirmed the importance of shelter areas in collared peccary husbandry.
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Contrasting responses of Eucalyptus trees to K fertilizer applications have been reported on soils with low K contents. A complete randomized block experiment was set up in Brazil to test the hypothesis that large atmospheric deposits of NaCl in coastal regions might lead to a partial substitution of K by Na in Eucalyptus physiology and enhance tree growth. Treatments with application of 1.5, 3.0, 4.5 kmol K ha(-1) (K(1.5), K(3.0), 1(4.5, respectively) as KCl, 3.0 kmol K ha(-1) applied as K(2)SO(4), 3.0 kmol Na ha(-1) (Na(3.0)) as NaCl commercialized for cattle feeding, and a mixture of 1.5 kmol K + 1.5 kmol Na ha(-1) (K(1.5) + Na(1.5)) were compared to a control treatment (C) with no K and Na applications. All the plots were fertilized with large amounts of the other nutrients. A positive effect of NaCl applications on the growth of E. grandis trees was observed. NaCl and KCl additions in treatments Na(3.0) and K(3.0) increased above-ground biomass by 56% and 130% three years after planting, respectively, in comparison with the C treatment. By contrast, accumulated litterfall up to age 3 years was not significantly modified. NaCl applications in the Na(3.0) treatment significantly increased Na accumulation in above-ground tree components but did not modify K accumulation, whatever the sampling age. A partial substitution of K by Na in tree physiology, as observed for various agricultural crops, might explain this behaviour. Our results suggest the possibility of applying inexpensive K fertilizers, which are less purified in Na, and explain why high yields are achieved without K fertilizer applications in areas with large dry depositions of marine aerosols. Further investigations are necessary to identify the processes involving Na in Eucalyptus tree physiology. (C) 2009 Elsevier B.V. All rights reserved.
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Wood-water relationship of untreated and heat-treated wood was studied. Specimens of Eucalyptus grandis, E saligna, and E citriodora were submitted to five conditions of heat treatment: 180 degrees C and 220 degrees C with air; 220 degrees C, 250 degrees C, and 280 degrees C with N(2). The wood-water relationships were accurately studied in a special device, in which the moisture content (MC) of the sample was measured with a highly sensitive electronic microbalance placed in a climatic chamber. The dimensions of the sample were collected continuously without contact by means of two high-speed laser scan micrometers. Sorption curves and shrinkage-MC relationships were observed. To study the effects of heat treatment, the following parameters were also determined: fiber saturation point (FPS), wood anisotropy (T/R ratio), shrinkage slope, reduction in hygroscopicity, and anti-shrink efficiency (ASE). The physical properties were significantly affected only at 220 degrees C and above. At heat temperature levels higher than 220 degrees C, the reduction in hygroscopicity and ASE are higher than 40% and continue to be reduced with increasing temperature level. This work also demonstrates that heat treatment does not change the slope of the curves shrinkage vs. MC, proving that heat treatment affects the domain of alterations in wood properties, but not the behavior within this domain.
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Predatory mites identified as Neoseiulus paspalivorus DeLeon (Phytoseiidae) have been considered as agents for classical biological control of the coconut mite, Aceria guerreronis Keifer (Eriophyidae), in Africa and elsewhere. Preliminary identification of geographically distinct populations as belonging to the same species (N. paspalivorus) was based on their morphological similarity. However, laboratory studies recently conducted have shown large differences in feeding behaviors and biological characteristics among individuals collected from three geographic origins: Brazil (South America), Benin and Ghana (West Africa). As morphologically similar specimens do not necessarily belong to the same species, we evaluated under laboratory conditions, reproductive compatibility between the specimens from three geographic locations to ascertain their conspecificity. Morphological measurements were also made to determine whether there is a means of discriminating between them. Inter-population crosses showed complete reproductive isolation between the three geographic populations, but interpopulation discontinuities in morphometric characters were absent. These results indicate that the tested specimens are distinct biological entities despite morphological similarity. Further molecular genetic studies are therefore proposed, including screening for endosymbionts and assessment of genetic differentiation, to determine the cause of reproductive incompatibility and to clarify the taxonomic relationship between those populations.
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- This paper reports the occurrence of five species of Rhodacaridae mites collected in the State of Sao Paulo, Brazil. One of these corresponds to a new genus and a new species, Binodacarus brasiliensis n. gen. n. sp.; two correspond to new species of kno
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The success in the adoption of peach integrated production (IP) was evaluated in small orchards of the Parana State. The importance of specific technical accompaniment; points of strangulating in adoption of technology and the classification of the areas to IP conformity were evaluated. The seasons 2005/2006 (without IP orientation) and 2006/2007 (with IP orientation) were compared considering 20 producers who were oriented monthly to attend the minimum requisites. The incidence of peach rust (Tranzschelia discolor) and of brown rot (Monilinia fructicola) in full bloom was evaluated in 2006/2007 and 2007/2008 seasons, as biological parameters to accompany the efficiency of system adoption. After the technical accompaniment in 2007/2008 season, the software APOIA-Novo Rural-PI (APOIA-PI) was applied to measure the conformity to IP in peach orchards. The conformity index of each orchard was compared to the minimum requisite to classify as IP (0.7). The major difficulties in register of field book were: pests monitoring; collect of climate data and the harvest evaluation. The technical accompaniment increased in 60% the conformity in use of field book. In 2007/2008 season, the brown rot incidence increased in some areas, caused by not following IP recommendations. The inadequate management caused the increment in pathogen inoculum, promoting the disease development in peach orchards. The APOIA-PI classified two orchards as good agricultural practices (GAP) (0.7 <= conformity index >= 0.4), two as integrated production (IP) (>= 0.7) and the other orchards had conformity index lower than 0.4.
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Sugarcane yellow leaf syndrome caused serious damage to crops in the Sao Paulo State, Brazil, in the 1990`s. The syndrome was also reported in other countries and investigations into the etiology revealed an association between the disease and virus and/or phytoplasma. The disease is potentially important and occurs endemically in that State, and for this reason the present study was conducted in order to demonstrate the occurrence of phytoplasma in three traditional sugarcane-producing areas, in Sao Paulo State, through molecular detection From naturally infected plants. Symptomatic plants belonging to varieties SP71-6163, SP71-6180 and SP89-1115 were sampled from Piracicaba, Jau and Ribeirao Preto, and total DNA was extracted from foliar tissues. Nested PCR was conducted with primer pairs P1/ Tint-16F2n/R2, and the amplified products were analyzed by electrophoresis on agarose gels. Amplified DNA fragments of 1.2 kb evidenced the presence of phytoplasma in 36% of symptomatic plants and revealed its Occurrence in all sampled regions. The results demonstrated that phytoplasma is associated with the disease and that it is important to keep a safe inspection of nurseries and monitoring plants in the field, as well as to Select Sugarcane genotypes with a good level of resistance in breeding programs.