Abstract: Electro acoustic volume measurement of a gas in a housing space may be performed using a hollow tube having a first end and a second end. A speaker is arranged to emit audio signals through the hollow tube. A first microphone of at least two microphones is located at the first end of the hollow tube, while a second microphone is located a defined distance from the first microphone within the hollow tube. A voltage-controlled oscillator controls the frequency of the audio signals to a resonance frequency where signals of the first microphone and the second microphone are 90 degrees out of phase while the first end of the hollow tube is located within the housing. The resonance frequency indicates a volume of the gas. The resonance frequency may be temperature-adjusted, or the volume may be temperature-adjusted.

Abstract: Electro acoustic volume measurement of a gas in a housing space may be performed using a hollow tube having a first end and a second end. A speaker is arranged to emit audio signals through the hollow tube. A first microphone of at least two microphones is located at the first end of the hollow tube, while a second microphone is located a defined distance from the first microphone within the hollow tube. A voltage-controlled oscillator controls the frequency of the audio signals to a resonance frequency where signals of the first microphone and the second microphone are 90 degrees out of phase while the first end of the hollow tube is located within the housing. The resonance frequency indicates a volume of the gas. The resonance frequency may be temperature-adjusted, or the volume may be temperature-adjusted.

Abstract: The load transducer for measuring forces and/or moments on a rotatable member. In one embodiment, the transducer includes an inner ring member attachable to a wheel hub and an outer ring member attachable to a wheel rim. At least one and, preferably, a plurality of beams unitarily extend between the inner and outer ring members and are circumferentially spaced apart. Each beam is formed of a stem and a perpendicular crossleg. Wells are formed in the exterior surfaces of the stem and the crossleg for mounting a strain gage in a force or moment measurement orientation. Additional strain gages may be mounted on the exterior sidewalls of each stem. The strain gages are inter-connected in a bridge configuration for measuring forces and moments exerted on the wheel. Bores formed in the stem and the crossleg provide a passage for the conductors from each strain gage to an electrical connector mounted between the inner and outer ring members.