New Releases by MARK OWEN

The report investigates the effects of finite amplitude on the diffraction of a spherical N wave by a circular aperture. The investigation was to be carried out in the farfield of the aperture, i.e., where the incident and diffracted signals were not completely resolved. An experiment was done in which an N wave was produced by an electric spark. A condenser microphone received the acoustic signal, and an aperture in a rigid baffle was placed between the spark and the microphone. The preliminary investigations revealed that, in the farfield, absorptions as well as nonlinear distortion is important. A computer algorithm was developed in which the effects of nonlinear distortion and absorption are combined in a stepwise manner. To test the algorithm, it was used to predict the waveform of a propagating N wave. The predicted waveforms agree very favorably with experiment. (Modified author abstract).

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''Não Há Dia Fácil'' é um retrato da vida das equipes do Seal e um relato da Operação Lança de Netuno, realizada em 1o de maio de 2011, que resultou na morte do terrorista Osama Bin Laden. Desde a pane no helicóptero Black Hawk - que quase fez com que a missão fosse abortada - até o comunicado pelo rádio via satélite confirmando que o alvo estava morto, a operação dos vinte e quatro Seal na propriedade secreta de Bin Laden deve ser recontada em detalhes. Das ruas de Badgá ao resgate do capitão Richard Phillips no Oceano Índico; das montanhas ao leste de Cabul ao terceiro andar do esconderijo de Osama Bin Laden em Abbottabad, no Paquistão, ''Não Há Dia Fácil'' coloca o leitor dentro da tropa de elite Equipe Seis do Seal.