Free and forced wave motion in a two-dimensional plate with radial periodicity

In many practical engineering situations, a source of vibrations may excite a large and flexible structure such as a ship’s deck, an aeroplane fuselage, a satellite antenna, a wall panel. To avoid transmission of the vibration and structure-borne sound, radial or polar periodicity may be used. In these cases, numerical approaches to study free and forced wave propagation close to the excitation source in polar coordinates are desirable. This is the paper’s aim, where a numerical method based on Floquet-theory and the FE discretision of a finite slice of the radial periodic structure is presented and verified. Only a small slice of the structure is analysed, which is approximated using piecewise Cartesian segments. Wave characteristics in each segment are obtained by the theory of wave propagation in periodic Cartesian structures and Finite Element analysis, while wave amplitude change due to the changes in the geometry of the slice is accommodated in the model assuming that the energy flow through the segments is the same. Forced response of the structure is then evaluated in the wave domain. Results are verified for an infinite isotropic thin plate excited by a point harmonic force. A plate with a periodic radial change of thickness is then studied. Free waves propagation are shown, and the forced response in the nearfield is evaluated, showing the validity of the method and the computational advantage compared to FE harmonic analysis for infinite structures

Comportamento de recópula de fêmeas selvagens de Ceratitis capitata (Diptera: Tephritidae) no Vale do São Francisco.

Moscas-das-frutas são pragas quarentenárias relevantes na fruticultura mundial. Amosca-do-mediterrâneo, Ceratitis capitata é cosmopolita e atualmente, a mais representativa da família Tephritidae no Submédio do Vale do São Francisco (VSF), no Nordeste do Brasil.Resumo 1003-1

Exposure of sterile Mediterranean fruit fly (Diptera: Tephritidae) males to ginger root oil reduces female remating.

Females of Ceratitis capitata are facultative polyandrous, with remating more common in laboratory strains rather than wild ones. In the application of the Sterile Insect Technique (SIT) against this pest, large overflooding ratios of sterile : wild males can increase the remating frequency. Females that mate for the first time with a sterile male tend to remate more frequently. The exposure of sterile males to ginger root oil (GRO) is used in C. capitata SIT programmes to increase the sterile male mating success. Exposing males to an ?aromatherapy? with GRO may also increase the remating frequency among wild females. The frequency of wild females remating, number of matings per female, the refractory period between the first and second mating, and the duration of the first and second matings of wild females were determined under laboratory conditions for three mating scenarios that included wild males only or wild males competing with sterile males (either GRO-treated or nontreated). Wild females first mated with sterile males exposed to GRO had their remating rate over the following 6 days and the mean number of matings per female reduced in comparison to those first mated with non-exposed sterile males, from 62.5% to 32.2% and from 3.1 to 1.6 respectively. The remating parameters of females mated with sterile GRO-exposed males resembled those of females mated with wild males.Supplement 1