Considerations about the welding repair effects on the structural integrity of an airframe critical to the flight-safety

Structures critical to the flight-safety are commonly submitted to several maintenance repairs at the welded joints in order to prolong the in-service life of aircrafts. The aim of this study is to analyze the effects of Tungsten Inert Gas (TIG) welding repair on the structural integrity of the AISI 4130 aeronautical steel by means of experimental fatigue crack growth tests in base-material, heat-affected zone (HAZ) and weld metal. The tests were performed on hot-rolled steel plate specimens, 0.89 mm thick, with load ratio R = 0.1, constant amplitude, at 10 Hz frequency and room temperature. Increase of the fracture resistance was observed in the weld metal but decreasing in the HAZ after repair. The results were associated to microhardness and microstructural changes with the welding sequence. (C) 2010 Published by Elsevier Ltd.

On the dynamic behaviour of the "click" mechanism in dipteran flight

In this paper, the dynamic behaviour of the "click" mechanism is analysed. A more accurate model is used than in the past, in which the limits of movement due to the geometry of the flight mechanism are imposed. Moreover, the effects of different damping models are investigated. In previous work, the damping model was assumed to be of the linear viscous type for simplicity, but it is likely that the damping due to drag forces is nonlinear. Accordingly, a model of damping in which the damping force is proportional to the square of the velocity is used, and the results are compared with the simpler model of linear viscous damping. Because of the complexity of the model an analytical approach is not possible so the problem has been cast in terms of non-dimensional variables and solved numerically. The peak kinetic energy of the wing root per energy input in one cycle is chosen to study the effectiveness of the "click" mechanism compared with a linear resonant mechanism. It is shown that, the "click" mechanism has distinct advantages when it is driven below its resonant frequency. When the damping is quadratic, there are some further advantages compared to when the damping is linear and viscous, provided that the amplitude of the excitation force is large enough to avoid the erratic behaviour of the mechanism that occurs for small forces. (C) 2011 Elsevier Ltd. All rights reserved.

Propriedades críticas do processo epidêmico difusivo com interação de Lévy

The diffusive epidemic process (PED) is a nonequilibrium stochastic model which, exhibits a phase trnasition to an absorbing state. In the model, healthy (A) and sick (B) individuals diffuse on a lattice with diffusion constants DA and DB, respectively. According to a Wilson renormalization calculation, the system presents a first-order phase transition, for the case DA > DB. Several researches performed simulation works for test this is conjecture, but it was not possible to observe this first-order phase transition. The explanation given was that we needed to perform simulation to higher dimensions. In this work had the motivation to investigate the critical behavior of a diffusive epidemic propagation with Lévy interaction(PEDL), in one-dimension. The Lévy distribution has the interaction of diffusion of all sizes taking the one-dimensional system for a higher-dimensional. We try to explain this is controversy that remains unresolved, for the case DA > DB. For this work, we use the Monte Carlo Method with resuscitation. This is method is to add a sick individual in the system when the order parameter (sick density) go to zero. We apply a finite size scalling for estimates the critical point and the exponent critical =, e z, for the case DA > DB

Advantages of using nested collision induced dissociation/post-source decay with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: sequencing of novel peptides from wasp venom

We have examined the applicability of the 'nested' collision induced dissociation/post-source decay (CID/PSD) method to the sequencing of novel peptides from solitary wasps which have neurotoxic venom for paralyzing other insects. The CID/PSD spectrum of a ladder peptide derived from an exopeptidase digest was compared with that of the intact peptide. The mass peaks observed only in the CID/PSD spectrum of a ladder peptide were extracted as C-terminal fragment ions. Assignment of C-terminal fragment ions enabled calculation of N-terminal fragment masses, leading to differentiation between N-terminal fragment ions and internal fragment ions. This methodology allowed rapid and sensitive identification by removing ambiguity in the assignment of the fragment ions, and proved useful for sequencing unknown peptides, in particular those available as natural products with a limited supply. Copyright (C) 2000 John Wiley & Sons, Ltd.

A morphological view of the relationship between indirect flight muscle maturation and the flying needs of two species of advanced eusocial bees

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

Influence of the insecticide pyriproxyfen on the flight muscle differentiation of Apis mellifera (Hymenoptera, Apidae)

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

Differential flight muscle development in workers, queens and males of the eusocial bees, Apis mellifera and Scaptotrigona postica

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

Foraging Behavior of the Swarm-founding Wasp Polybia (Trichothorax) sericea (Hymenoptera, Vespidae): Daily Resource Collection Activity and Flight Capacity

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fight versus flight: the interaction of temperature and body size determines antipredator behaviour in tegu lizards

Ectotherm antipredator behaviour might be strongly affected both by body temperature and size: when environmental temperatures do not favour maximal locomotor performance, large individuals may confront predators, whereas small animals may flee, simply because they have no other option. However, integration of body size and temperature effects is rarely approached in the study of antipredator behaviour in vertebrate ectotherms. In the present study we investigated whether temperature affects antipredator responses of tegu lizards, Tupinambis merianae, with distinct body sizes, testing the hypothesis that small tegus (juveniles) run away from predators regardless of the environmental temperature, because defensive aggression may not be an effective predator deterrent, whereas adults, which are larger, use aggressive defence at low temperatures, when running performance might be suboptimal. We recorded responses of juvenile (small) and adult (large) tegu lizards to a simulated predatory attack at five environmental temperatures in the laboratory. Most differences between the two size classes were observed at low temperatures: large tegus were more aggressive overall than were small tegus at all temperatures tested, but at lower temperatures, the small lizards often used escape responses whereas the large ones either adopted a defensive posture or remained inactive. These results provide strong evidence that body size and temperature affect the antipredator responses of vertebrate ectotherms. We discuss the complex and intricate network of evolutionary and ecological parameters that are likely to be involved in the evolution of such interactions. (C) 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

BORN-INFELD ELECTRODYNAMICS and EULER-HEISENBERG-LIKE MODEL: OUTSTANDING EXAMPLES of THE LACK of COMMUTATIVITY AMONG QUANTIZED TRUNCATED ACTIONS and TRUNCATED QUANTIZED ACTIONS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

On Nonlinear Dynamics and an Optimal Control Design to a Longitudinal Flight

In this work, we analyzed a bifurcational behavior of a longitudinal flight nonlinear dynamics, taking as an example the F-8 aircraft Crusader. We deal with an analysis of high angles of attack in order to stabilize the oscillations; those were close to the critical angle of the aircraft, in the flight conditions, established. We proposed a linear optimal control design applied to the considered nonlinear aircraft model below angle of stall, taking into account regions of Hopf and saddled noddle bifurcations.

In-flight and collisional dissipation as a mechanism to suppress Fermi acceleration in a breathing Lorentz gas

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

Body size and flight distance in stingless bees (Hymenoptera: Meliponini): inference of flight range and possible ecological implications

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

FLIGHT RANGE of AFRICANIZED HONEYBEES, Apis mellifera L. 1758 (Hymenoptera: Apidae) IN AN APPLE GROVE

O estudo do raio de ação das abelhas na coleta de néctar e pólen é de extrema importância para se saber até que distância a polinização por este inseto é promovida com eficiência. Para tanto, cinco colônias de abelhas africanizadas marcadas com 32P foram levadas a um pomar de maçã, sendo agrupadas no centro de uma área de 0,8 ha, a partir do qual foram colocadas estacas a cada 10m, formando quatro alas correspondentes às direções Norte, Sul, Leste e Oeste. As abelhas foram capturadas duas vezes por dia e por dez dias consecutivos, quando visitavam as flores das macieiras, até 50m do centro. Verificou-se que o número de abelhas marcadas coletadas, diminuiu linearmente à medida em que as mesmas se afastavam das colméias. Não houve interferência das orientações geográficas no comportamento de vôo das abelhas.

Isolation and sequence determination of peptides in the venom of the spider wasp (Cyphononyx dorsalis) guided by matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry

Micro-scale (sub-pmol) isolation and sequence determination of three peptides from the venom of the solitary spider wasp Cyphononyx dorsalis is described. We isolated two novel peptides Cd-125 and Cd-146 and a known peptide Thr(6)-bradykinin from only two venom sacs of solitary spider wasp Cyphononyx dorsalis without bioassay-guided fractionation. but instead guided by MALDI-TOF MS. The MALDI-TOF MS analysis of each fraction showed the purity and molecular weight of the components, which led to the isolation of the peptides virtually without loss of sample amount. The sequences of the novel peptides Cd-125 (Asp-Thr-Ala-Arg-Leu-Lys-Trp-His) and Cd-146 (Ser-Glu-Thr-Gly-Asn-Thr-Val-Thr-Val-Lys-Gly-Phe-Ser-Pro-Leu-Arg) were determined by Edman degradation together with mass spectrometry. and finally corroborated by solid-phase synthesis. The known peptide Thr(6)-bradykinin (Arg-Pro-Pro-Gly-Phe-Thr-Pro-Phe-Arg) was identified by comparison with the synthetic authentic specimen. This is the first example for any kinins to be found in Pompilidae wasp venoms. The procedure reported here can be applicable to studies on many other components of solitary wasp venoms with limited sample availability. (C) 2001 Elsevier B.V. Ltd. All rights reserved.