Structural health evaluation by optimization techinique and artificial neural network

This paper presents two different approaches to detect, locate, and characterize structural damage. Both techniques utilize electrical impedance in a first stage to locate the damaged area. In the second stage, to quantify the damage severity, one can use neural network, or optimization technique. The electrical impedance-based, which utilizes the electromechanical coupling property of piezoelectric materials, has shown engineering feasibility in a variety of practical field applications. Relying on high frequency structural excitations, this technique is very sensitive to minor structural changes in the near field of the piezoelectric sensors, and therefore, it is able to detect the damage in its early stage. Optimization approaches must be used for the case where a good condensed model is known, while neural network can be also used to estimate the nature of damage without prior knowledge of the model of the structure. The paper concludes with an experimental example in a welded cubic aluminum structure, in order to verify the performance of these two proposed methodologies.

An enhanced genetic algorithm to solve the static and multistage transmission network expansion planning

An enhanced genetic algorithm (EGA) is applied to solve the long-term transmission expansion planning (LTTEP) problem. The following characteristics of the proposed EGA to solve the static and multistage LTTEP problem are presented, (1) generation of an initial population using fast, efficient heuristic algorithms, (2) better implementation of the local improvement phase and (3) efficient solution of linear programming problems (LPs). Critical comparative analysis is made between the proposed genetic algorithm and traditional genetic algorithms. Results using some known systems show that the proposed EGA presented higher efficiency in solving the static and multistage LTTEP problem, solving a smaller number of linear programming problems to find the optimal solutions and thus finding a better solution to the multistage LTTEP problem. Copyright © 2012 Luis A. Gallego et al.

Local and regional features of surface radiation fluxes over the tropical Atlantic ocean near Sao Pedro and Sao Paulo archipelago: Evidence of small scale upwelling

To properly describe the interactions between the ocean and atmosphere, it is necessary to assess a variety of time and spatial scales phenomena. Here, high resolution oceanographic and meteorological data collected during an observational campaign carried out aboard a ship in the tropical Atlantic Ocean, on May 15-24, 2002, is used to describe the radiation balance at the ocean interface. Data collected by two PIRATA buoys, along the equator at 23°W and 35°W and satellite and climate data are compared with the data obtained during the observational campaign. Comparison indicates remarkable similarity for daily and hourly values of radiation fluxes components as consequence of the temporal and spatial consistence presented by the air and water temperatures measured in situ and estimated from large scale information. The discrepancy, mainly in the Sao Pedro and Sao Paulo Archipelago area, seems to be associated to the local upwelling of cold water, which is not detected in all other estimates investigated here. More in situ data are necessary to clarify whether this upwelling flow has a larger scale effect and what are the meteorological and oceanographic implications of the local upwelling area on the tropical waters at the Brazilian coast.

Local and regional ecological drivers of fish assemblages in Brazilian estuaries

Spatial patterns in assemblage structures are generated by ecological processes that occur on multiple scales. Identifying these processes is important for the prediction of impact, for restoration and for conservation of biodiversity. This study used a hierarchical sampling design to quantify variations in assemblage structures of Brazilian estuarine fish across 2 spatial scales and to reveal the ecological processes underlying the patterns observed. Eight areas separated by 0.7 to 25 km (local scale) were sampled in 5 estuaries separated by 970 to 6000 km (regional scale) along the coast, encompassing both tropical and subtropical regions. The assemblage structure varied significantly in terms of relative biomass and presence/absence of species on both scales, but the regional variation was greater than the local variation for either dataset. However, the 5 estuaries sampled segregated into 2 major groups largely congruent with the Brazilian and Argentinian biogeographic provinces. Three environmental variables (mean temperature of the coldest month, mangrove area and mean annual precipitation) and distance between estuaries explained 44.8 and 16.3%, respectively, of the regional-scale variability in the species relative biomass. At the local scale, the importance of environmental predictors for the spatial structure of the assemblages differed between estuarine systems. Overall, these results support the idea that on a regional scale, the composition of fish assemblages is simultaneously determined by environmental filters and species dispersal capacity, while on a local scale, the effect of environmental factors should vary depending on estuary-specific physical and hydrological characteristics © 2013 Inter-Research.

Interaction between supraoptic nucleus and septal area in the control of water, sodium intake and arterial blood pressure induced by injection of angiotensin II

We investigated the effects of injection into the supraoptic nucleus (SON) of losartanand PD 123319 (nonpeptide AT(1) and AT(2)- angiotensin II [ANG II] receptor antagonists, respectively); d(CH2)(5)-Tyr(Me)-AVP (AVPA; an arginine-vasopressin [AVP] V-1 receptor antagonist), FK 409 (a nitric oxide [NO] donor), and N-W-mtro-(L)-arginine methyl ester ((L)-NAME; an NO synthase inhibitor) oil water intake, sodium chloride 3% (NaCl) intake and arterial blood pressure induced by injection of ANG 11 into the lateral septal area (LSA). Mate Holtzman rats (250-300 g) were implanted with cannulae into SON and LSA unilaterally. The drugs were injected in 0.5 mul over 30-60 s. Controls were injected with a similar volume of 0.15 M NaCl. ANG II was injected at a dose of 10 pmol. ANG II antagonists and AVPA were injected at doses of 80 nmol. FK 409 and (L)-NAME were injected at doses of 20 and 40 mug, respectively. Water and NaCl intake was measured over a 2-h period. Prior administration of losartan into the SON decreased water and NaCl intake induced by injection of ANG II. While there was a decrease in water intake, ANG II-induced NaCl intake was significantly increased following injection of AVPA. FK 409 injection decreased water intake and sodium intake induced by ANG II. L-NAME alone increased water and sodium intake and induced a pressor effect. (L)-NAME-potentiated water and sodium intake induced by ANG II. PD 123319 produced no changes in water or sodium intake induced by ANG II. The prior administration of losartan or AVPA decreased mean arterial pressure (MAP) induced by ANG II. PD 123319 decreased the pressor effect of ANG II to a lesser degree than losartan. FK 409 decreased the pressor effect of ANG II while (L)-NAME potentiated it. These results suggest that both ANG II AT, and AVP V, receptors and NO within the SON may be involved in water intake, NaCl intake and the pressor response were induced by activation of ANG II receptors within the LSA. These results do not support the involvement of LSA AT(2) receptors in the mediation of water and NaCl intake responses induced by ANG II, but influence the pressor response. (C) 2004 Elsevier B.V. All rights reserved.

Local and cardiorenal effects of periodontitis in nitric oxide-deficient hypertensive rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Extensive Comparisons of Optical Fast-OFDM and Conventional Optical OFDM for Local and Access Networks

A performance comparison between a recently proposed novel technique known as fast orthogonal frequency-division multiplexing (FOFDM) and conventional orthogonal frequency-division multiplexing (OFDM) is undertaken over unamplified, intensity-modulated, and direct-detected directly modulated laser-based optical signals. Key transceiver parameters, such as the maximum achievable transmission capacity and the digital-to-analog/analog-to-digital converter (DAC/ADC) effects are explored thoroughly. It is shown that, similarly to conventional OFDM, the least complex and bandwidth efficient FOFDM can support up to similar to 20 Gb/s over 500 m worst-case multimode fiber (MMF) links having 3 dB effective bandwidths of similar to 200 MHz X km. For compensation of the DAC/ADC roll-off, a power-loading (PL) algorithm is adopted, leading to an FOFDM system improvement of similar to 4 dB. FOFDM and conventional OFDM give similar optimum DAC/ADC parameters over 500 m worst-case MMF, while over 50 km single-mode fiber a maximum deviation of only similar to 1 dB in clipping ratio is observed due to the imperfect chromatic dispersion compensation caused by one-tap equalizers.

Interaction between paraventricular nucleus and septal area in the control of physiological responses induced by angiotensin II

We determined the effects of losartan (40 nmol) and PD 123319 (40 nmol) (both non-peptides and selective antagonists of the AT1 and AT2 angiotensin receptors, respectively), and [Sar¹, Ala8] angiotensin II (ANG II) (40 nmol) (a non-selective peptide antagonist of angiotensin receptors) injected into the paraventricular nucleus (PVN) on the water and salt appetite, diuresis and natriuresis and mean arterial pressure (MAP) induced by administration of 10 nmol of ANG II into the medial septal area (MSA) of male Holtzman rats weighing 250-300 g. The volume of drug solution injected was 0.5 µl over a period of 10-15 s. The responses were measured over a period of 120 min. ANG II alone injected into the MSA induced an increase in all the above parameters (8.1 ± 1.2, 1.8 ± 0.3, and 17.1 ± 1.0 ml, 217 ± 25 µEq/120 min, and 24 ± 4 mmHg, respectively, N = 10-12) compared with vehicle-treated rats (1.4 ± 0.2, 0.6 ± 0.1, and 9.3 ± 0.5 ml, 47 ± 5 µEq/120 min, and 4.1 ± 0.8 mmHg, respectively, N = 10-14). Pretreatment with losartan and [Sar¹, Ala8] ANG II completely abolished the water and sodium intake, and the pressor increase (0.5 ± 0.2, 1.1 ± 0.2, 0.5 ± 0.2, and 0.8 ± 0.2 ml, and 1.2 ± 3.9, 31 ± 4.6 mmHg, respectively, N = 9-12), whereas losartan blunted the urinary and sodium excretion induced by ANG II (13.9 ± 1.0 ml and 187 ± 10 µEq/120 min, respectively, N = 9). Pretreatment with PD 123319 and [Sar¹, Ala8] ANG II blocked the urinary and sodium excretion (10.7 ± 0.8, 9.8 ± 0.7 ml, and 67 ± 13 and 57 ± 17 µEq/120 min, respectively, N = 9), whereas pretreatment with PD 123319 partially blocked the water and sodium intake, and the MAP induced by ANG II administration (2.3 ± 0.3, 1.1 ± 0.1 ml, and 12 ± 3 mmHg, respectively, N = 9-10). These results suggest the angiotensinergic effect of the MSA on the AT1 and AT2 receptors of the PVN in terms of water and sodium homeostasis and MAP modulation.

Local and global magnetic properties of Zn1-xCoxO and Mn-doped GaAs thin films

Amorphous and crystalline thin films of Mn-doped(0.5%-10%) GaAs and crystalline thin films of Zn1-xCoxO(x = 3%-20%) were investigated by means of magnetic susceptibility and electron spin resonance (ESR). For the Mn-doped GaAs samples, our results show the absence of ferromagnetic ordering for the amorphous films in the 300 > T > 2 K temperature range, in contrast to the ferromagnetism found in crystalline films for T-C < 110 K. A single ESR line with a temperature independent g-value (g similar to 2) is observed for the amorphous films, and the behavior of this ESR linewidth depends on the level of crystallinity of the film. For the Mn-doped GaAs crystalline films, only a ferromagnetic mode is observed for T < TC when the film is ferromagnetic. Turning now the Zn1-xCoxO films, ferromagnetic loops were observed at room temperature for these films. The magnetization data show an increasing of the saturation magnetization M. as a function of x reaching a maximum value for x approximate to 10%. ESR experiments at T = 300 K in the same films show a strong anisotropic ferromagnetic mode (FMR) for x = 0.10.

Local and nanoscopic structure of potassium triflate-doped siloxane-polyoxyethylene ormolytes

Siloxane-poly(oxyethylene) hybrids obtained by the sol-gel process and containing short polymer chain have been doped with potassium triflate (KCF3SO3). The local structure of these hybrids was investigated by X-ray absorption spectroscopy near the potassium K-edge. Small angle X-ray scattering was used to determine the structure at the nanometer scale. Results revealed that at low and medium potassium concentration (n = [O][K] >= 8, where n represents the molar ratio of ether-type oxygen atoms per alkaline cation) the cations interact mainly with the polymer chains, while at larger doping level (n < 8) the formation of a polyehter:KCF3SO3 Complex is observed. The nanoscopic structure of the hybrids is also affected by doping. By increasing the doping level, decreasing trends in the electronic density contrast between siloxane nanoparticles and polyether matrix and in the siloxane interparticle distance are observed. At high doping level the small angle X-ray scattering patterns are strongly modified, showing the disappearance of the correlation peak and the formation of a potassium-containing nanophase. (c) 2006 Elsevier B.V. All rights reserved.

Local and remote lesions in horses subjected to small colon distension and decompression

The purpose of this study was to observe and characterize colonic and lung lesions in horses subjected to experimental distension and decompression of the small colon. Sixteen healthy adult horses were divided into 2 groups: 9 horses that were subjected to distension of the small colon by means of a latex balloon surgically implanted in the lumen and inflated to a pressure of 40 mm Hg for 4 h, and 7 horses in which the balloon was implanted but not inflated. Colonic biopsy specimens were collected before balloon implantation, at the end of the period of obstruction, and 1.5 and 12 h after decompression and were examined for hemorrhage, edema, and neutrophil infiltration; myeloperoxidase (MPO) activity and hemoglobin concentration were measured as well. At the end of the experiment, lung samples were also collected and examined for neutrophil accumulation and MPO activity. The mucosa was not affected by luminal distension; lesions were restricted to the seromuscular layer. Neutrophil accumulation and edema were observed in the samples from both groups of horses but were greater in those from the distension group, in which there was also hemorrhage, fibrin deposition, and increased MPO activity in the seromuscular layer. Similarly, there was greater accumulation of neutrophils in the lung samples from the distension group than in those from the sham-operated group, as determined by histologic evaluation and MPO assay. These findings provide new evidence of reperfusion injury and a systemic inflammatory response, followed by remote lesions, in horses with intestinal obstruction.

Analysis of chromatin and nuclear area alterations in triatomines during starvation

In the present study changes in nuclear area and chromatin distribution in the Malpighian tubules of a blood-feeding insect, the vector of Chagas' disease were analysed. Male and female adult insects were dissected, after a starving period of up to 28 days. The Malpighian tubules were fixed and stained by orcein lacto-acetic. The nuclei were analyzed by photomicrography, karyometry and a statistical analysis was performed. It was observed that with the increase of the starvation period there were alterations in the nuclear phenotype, that is, changes in the nuclear area and chromatin extenuation. In males, starting from the second week of starvation, chromatin extenuation was accentuated, and the beginning of nuclear coalition occurred more frequently in the third and fourth starvation weeks. In females, the accentuated chromatin extenuation was observed after the third starvation week, and irregularities in nuclear borders were more frequent. The descriptive statistical analysis of the male and temale nuclear areas revealed that the nuclear areas continued to increase during starvation reaching highest values in the third week. Another outstanding aspect is that in the third starvation week karyometry presented larger heterogeneity with higher standard deviation values for both genders. Therefore, nuclear alterations related to the distribution and extenuation chromatin and increase in nuclear area were observed. These aspects suggest the presence of nuclear metabolic mechanisms that lead to synthesis of specific proteins necessary for the protection and maintenance of the cell during physiologic stress.

An investigations on local and global behavior of a (SMA) oscillator of 3 - DOF driven by a limited power supply

SMART material systems offer great possibilities in terms of providing novel and economical solutions to engineering problems. The technological advantages of these materials over traditional ones are due to their unique microstructure and molecular properties. Smart materials such as shape memory alloys (SMA), has been used in such diverse areas of engineering science, nowadays. In this paper, we present a numerical investigation of the dynamics interaction of a nonideal structure (NIS). We analyze the phenomenon of the passage through resonance region in the steady state processes. We remarked that this kind of problem can lead to the so-called Sommerfeld effect: steady state frequencies of the DC motor will usually increase as more power (voltage) is given to it in a step-by-step fashion. When a resonance condition with the structure it is reached, the better part of this energy it is consumed to generate large amplitude vibrations of the foundation without sensible change of the motor frequency as before. The results obtained by using numerical simulations are discussed in details. Copyright © 2009 by ASME.

Cluster analysis and artificial neural network on the superovulatory response prediction in mice

Complex biological systems require sophisticated approach for analysis, once there are variables with distinct measure levels to be analyzed at the same time in them. The mouse assisted reproduction, e.g. superovulation and viable embryos production, demand a multidisciplinary control of the environment, endocrinologic and physiologic status of the animals, of the stressing factors and the conditions which are favorable to their copulation and subsequently oocyte fertilization. In the past, analyses with a simplified approach of these variables were not well succeeded to predict the situations that viable embryos were obtained in mice. Thereby, we suggest a more complex approach with association of the Cluster Analysis and the Artificial Neural Network to predict embryo production in superovulated mice. A robust prediction could avoid the useless death of animals and would allow an ethic management of them in experiments requiring mouse embryo.