Abstract: An acoustic displacement flowmeter uses a high-compliance acoustic-type displacement transducer to measure fluid flow accumulated by temporarily restricting the flow of a fluid along a path. The displacement transducer signal, representative of fluid flow rate, is integrated after an initial settling period elapses, and the integrated signal is periodically sampled. The number of samples taken during a measurement cycle depends upon the slope of the integrated signal and the maximum sample period permitted. The samples are summed and the actual flow rate is computed by a microcomputer.

Abstract: A gas flow meter uses the principle of Boyle's law to measure the gas flow rate along a path. Gas flows through a valve into a reservoir until the pressure is maximized in the volume. The valve then vents the reservoir to ambient while blocking the inlet path. The pressure at maximum and minimum values is measured by a pressure sensor and used to generate the flow rate signal. An enlarged volume in the inlet path limits the pressure rise during the exhaust phase of the measurement cycle.

Abstract: Fluid flow along a fluid path is determined by measuring the travel time between two transducers of two oppositely travelling acoustic burst waves. A pair of phase reference signals in phase quadrature are compared with the signals received by each transducer to determine the phase difference therebetween. The phase difference values are used to calculate the flow velocity.After each phase difference determination has been made, the transducer drive signals are adjusted so that the launch time of the next pair of burst waves reduces the phase difference between the previously received signals and the phase reference to zero in the absence of any changes in flow velocity. The duration of each acoustic burst is sufficient to ensure that a predetermined number of successively received cycles in each burst are used in the phase comparison process.

Abstract: A petri dish includes a bottom container member having a circumferential groove located in the bottom corner thereof. The groove facilitates the distribution of liquid culture media during the filling operation, assists in retaining the periphery of the solidified media in place to increase shelf-life, and provides a pleasing visual perception as to the media thickness when the petri dish is viewed from the side. The cover member includes an upstanding rib located on a top surface thereof, such that upon stacking the petri dish with another of like construction, the exterior surface of the circumferential groove and the upstanding rib cooperate to facilitate stacking. Also, the respective top and bottom walls of the cover and bottom container being 30% thinner than their associated side wall portions to provide in a savings in fabrication material.

Abstract: Mobile furniture modules can be releasably installed under a work surface structure, such as provided by a countertop or table top, with convenient rearrangement enabled by providing each module with roller structures, such as typical casters, which are releasably anchored in wheel mounts which receive the caster wheels in a depression seat at a level elevated from the floor in the installed position. In addition the work surface structure is provided with a retainer which prevents movement of installed modules from beneath the work surface structure, preferably by engaging the top of the module with adjustable elevation which levels the module following releasable anchoring of the wheels in the elevated depression seat.The modular furniture system can be employed with particular advantage for movable laboratory cabinets to provide continuous work surface between rearrangeably installed cabinets.