Abstract: A parking enforcement device can be secured to a surface adjacent to the area designated as NO PARKING. The enforcement device can include an elongated hollow body, a window provided to the tubular body, a battery, an internal frame assembly disposed inside of the elongated hollow body, and a camera disposed inside of the elongated hollow body. The internal frame assembly defines a cavity in which the battery is located. A camera support pole extends vertically upwards from the internal frame assembly. The camera is secured to the camera support pole and located vertically along the camera support pole such that the camera views outward through the window. A solar panel can be provided atop the parking enforcement device to recharge the battery.

Abstract: A fluid level measuring system comprising a fluid level sensor is disclosed. The fluid level sensor may comprise a top or bottom mounted transducer and limited openings to enable accurate measurement of a fluid's depth while the fluid is moving. The fluid level measuring system may be calibrated without the use of calibration reflectors and may be used to retrofit prior art fluid level measuring systems. A control system may be used to control the fluid level sensor and interface the fluid level sensor to an external subsystem, such as a fuel gauge.

Abstract: A liquid level change indicator is described as an apparatus. which generates a visual indication when a liquid level in a controlled vessel has changed and indicates amount of change for a timed period. Operation of the instrument entails positioning the apparatus in the liquid containment vessel from a support chain. Positioning, is accomplished by a course chain adjustment, followed by a fine-threaded-nut adjustment. A float centering itself in a concentric circle sight gauge indicates initial correct monitoring position. Deviation from one of the concentric rings constitutes a liquid level change. Each concentric ring indicates a larger level change relative to the innermost sight ring per unit test time.

Abstract: A liquid level change indicator is described as an apparatus, which generates a visual indication when a liquid level in a controlled vessel has changed and indicates amount of change for a timed period. Operation of the instrument entails positioning the apparatus in the liquid containment vessel from a support chain. Positioning, is accomplished by a course chain adjustment, followed by a fine-threaded-nut adjustment. A float centering itself in a concentric circle sight gauge indicates initial correct monitoring position. Deviation from the bulls eye of the concentric ring site gauge constitutes a liquid level change. Each concentric ring indicates a larger level change relative to the innermost sight ring per unit test time.

Abstract: A liquid level measuring system having a tubular ultrasonic probe with a length in excess of the depth of liquid to be measured; for vertical insertion into a tank. A transducer inside the tube, at a first distance above the bottom end of probe body, responds transmits a sinusoidal acoustical pulse through the probe to the surface of the liquid. An echo returns from the surface of the liquid to the transducer and provides a sinusoidal echo signal. A receiver responds to the echo signal by providing a start signal corresponding to the transmitter signal crossing a predetermined amplitude in a predetermined direction and by providing a stop signal corresponding to a first selected echo signal crossing a second predetermined reference level in a predetermined direction. The speed of sound in the liquid is measured by measuring the echo time to a calibration rod in the tube at a known distance from the transducer.