Abstract: A portable electronic device may include a housing having a wall defining an opening in the housing and at least a portion of four side surfaces of the portable electronic device. The portable electronic device may further include a display at least partially within the housing, a front cover positioned in the opening in the housing and over the display, the front cover defining a front surface, a peripheral side surface extending from the front surface and at least partially surrounded by the wall of the housing, and a notch that, together with a portion of the wall of the housing, defines an acoustic port of the portable electronic device. The electronic device may further include an acoustic port cover positioned at least partially in the acoustic port and a speaker at least partially within the housing and configured to direct sound through the acoustic port cover.

Abstract: The present invention relates to apparatus for influencing fluid flow over a surface, and more particularly, but not exclusively, to turbulent boundary layer flow drag reduction for an aircraft. The present invention provides such apparatus including a plasma generator comprising a first electrode and a signal generator, the apparatus being operable to drive the first electrode with a pulsed signal generated by the signal generator thereby to cause a change in direction of the flow of the fluid over the surface.

Abstract: The present invention relates to apparatus for influencing fluid flow over a surface, and more particularly, but not exclusively, to turbulent boundary layer flow drag reduction for an aircraft. The present invention provides such apparatus including a plasma generator comprising first and second spaced-apart independently controllable electrodes operable to cause a change in direction of the flow of the fluid over the surface.

Abstract: The present invention relates to apparatus for influencing fluid flow over a surface, and more particularly, but not exclusively, to turbulent boundary layer flow drag reduction for an aircraft. The present invention provides such apparatus including a plasma generator comprising first and second spaced-apart independently controllable electrodes operable to cause a change in direction of the flow of the fluid over the surface.

Abstract: The present invention relates to apparatus for influencing fluid flow over a surface, and more particularly, but not exclusively, to turbulent boundary layer flow drag reduction for an aircraft. The present invention provides such apparatus including a plasma generator comprising a first electrode (7) and a signal generator (18), the apparatus being operable to drive the first electrode (7) with a pulsed signal generated by the signal generator (18) thereby to cause a change in direction of the flow of the fluid over the surface.

Abstract: A surface discharge plasma cathode electron beam generating assembly (1) includes an anode (2) maintainable at a substantially constant first potential, a cathode device (3) having a first electrically conductive member (4), a dielectric member (5) at least partially surrounding the first member (4) and electrically conductive means (6) located on the outer surface of the dielectric member (5) and insulated therefrom. A capacitative divider circuit (7) is provided for maintaining the first electrically conductive member (4) at a second potential different from the first potential and for maintaining the electrically conductive means (6) at a high negative third potential relative to the first and second potentials.