Abstract: A method for determining the level of fuel in tanks otherwise un-modified is provided. The method is based on the variation of the acoustic frequency response of the tank in the sonic range with the fuel level in the tank. In a preferred embodiment, the tank is a reservoir for propane used as fuel for preparing food. The operator, such as a homeowner, attaches the tank to his/her grill. The operator engages the proposed new art by tapping the tank and receiving the acoustic signal emanating from the tank with a microphone such as one embedded in a smartphone. The smartphone examines a cluster of peaks in the sonic frequency spectrum between 0 Hz and 20 kHz. By capturing the frequency of the first large peak above 900 Hz in the frequency spectrum, the smartphone converts the frequency into an estimate of the amount of fuel remaining in the tank.

Abstract: Methods and apparatuses for measuring streaming metrics. A method for measuring a streaming metric corresponding to a rotating surface is characterized by rotating the surface around an axis of rotation and measuring the streaming metric at a location within one radius from the axis of rotation and within three radii from the surface, wherein the location does not contact the surface. Apparatus for measuring a streaming metric corresponding to a rotating surface are characterized by a working electrode which does not contact the surface, a counter electrode, a meter connected to the working electrode and the counter electrode, a rotatable spindle on which the surface is mounted, and a container for holding electrolyte, wherein the working electrode, counter electrode, and surface are located within the container.

Abstract: Methods and apparatuses for measuring streaming metrics. A method for measuring a streaming metric corresponding to a rotating surface is characterized by rotating the surface around an axis of rotation and measuring the streaming metric at a location within one radius from the axis of rotation and within three radii from the surface, wherein the location does not contact the surface. Apparatus for measuring a streaming metric corresponding to a rotating surface are characterized by a working electrode which does not contact the surface, a counter electrode, a meter connected to the working electrode and the counter electrode, a rotatable spindle on which the surface is mounted, and a container for holding electrolyte, wherein the working electrode, counter electrode, and surface are located within the container.

Abstract: An apparatus and method is disclosed for measuring the distance between a first body having a first surface separated by a medium from a second body through the use of transmitted evanescent radiation. The first body is substantially radiation transparent and has a critical angle of total internal reflection with respect to the medium and the second body has an optically disseminative opposing surface, that is, the opposing surface inherently disseminates radiation nonspecularly, and is capable of frustrating total internal reflection when brought into close proximity with the first surface.