Abstract: A mobile device for traversing a ferromagnetic surface. The device includes a frame and at least one surface contacting device attached to the frame. The device also includes a Halbach magnet array attached to the frame, wherein the Halbach magnet array provides a magnetic force to maintain the surface contacting device substantially into contact with the ferromagnetic surface.

Abstract: A mobile device for traversing a ferromagnetic surface. The device includes a frame and at least one surface contacting device attached to the frame. The device also includes a Halbach magnet array attached to the frame, wherein the Halbach magnet array provides a magnetic force to maintain the surface contacting device substantially into contact with the ferromagnetic surface.

Abstract: A mobile device for traversing a ferromagnetic surface. The device includes a frame and at least one surface contacting device attached to the frame. The device also includes a Halbach magnet array attached to the frame, wherein the Halbach magnet array provides a magnetic force to maintain the surface contacting device substantially into contact with the ferromagnetic surface.

Abstract: An acoustic sensor and method of using same for determining the position of a tool from a workpiece are disclosed in which a piezoelectric transducer having a curved surface emits a sound wave which strikes the workpiece and is reflected back to the sensor. The sensor and tool are positioned relative to one another so that the workpiece will be near the focal point of the curved surface when the tool is operating. This positioning substantially overcomes the attenuation problems of high frequency sound waves transmitted through air.

Abstract: A fluid mixing apparatus having means for producing vortex-like motions of the fluids introduced therein, one embodiment of such an apparatus, for example, using two concentrically mounted inner and outer members, preferably cylindrical, moveable relative to each other at rotational speeds such as to produce the desired vortex-like motions of the fluids introduced into the region therebetween. In one embodiment thereof, the vortex-like motions may be obtained at relatively low rotational speeds by the use of V-shaped grooves on the inner member. In addition, suitable means can further be used to generate a de-stabilizing force for the fluids in a direction substantially perpendicular to the velocity streamlines thereof to further enhance the mixing effectiveness and to improve the quality of the mix, such de-stabilizing force in one embodiment, for example, being generated by the application of an electric field across the region between the inner and outer members.