Abstract: The invention is an assembly of prefabricated metal receptacles forming a swimming pool and a method for constructing the assembly. Among other features, the assembly is characterized by guided or unguided clamping structures that allow on-site construction without requiring on-site welding or access to the bottom or interior of the assembly.

Abstract: The invention is an assembly of prefabricated metal receptacles forming a swimming pool and a method for constructing the assembly. Among other features, the assembly is characterized by guided clamping structures that allow on-site construction without requiring on-site welding or access to the bottom or interior of the assembly.

Abstract: The invention is an assembly of prefabricated metal receptacles forming a swimming pool and a method for constructing the assembly. Among other features, the assembly is characterized by guided clamping structures that allow on-site construction without requiring on-site welding or access to the bottom or interior of the assembly.

Abstract: A pool cleaning robot can include a main housing configured to be submerged in a pool. A propulsion unit within the main housing can be configured to move the pool cleaning robot along a pool surface. One or more germicidal light sources, configured to disinfect at least a portion of a pool surface, can be positioned on a bottom of the main housing. A power unit can be configured to power the propulsion unit and the one or more germicidal light sources of the pool cleaning robot.

Abstract: A pool cleaning robot can include a main housing configured to be submerged in a pool. A propulsion unit within the main housing can be configured to move the pool cleaning robot along a pool surface. One or more germicidal light sources, configured to disinfect at least a portion of a pool surface, can be positioned on a bottom of the main housing. A power unit can be configured to power the propulsion unit and the one or more germicidal light sources of the pool cleaning robot.

Abstract: A force balanced accelerometer system comprises an accelerometric sensor and a control system. The sensor comprises a conductive pendulum pivotably mounted between first and second electrode plates. The control system establishes a cycle period with three phases. In the first phase, the pendulum is electrically isolated in an electric field established between the electrodes. The pendulum is moved from a null position in response to inertial acceleration, and a pickoff signal indicative of the acceleration-responsive position is generated. The pickoff signal is fed into a sample-and-hold circuit and then into a servo compensation circuit, having proportional and integral control, so as to generate a force-indicative signal indicative of the magnitude and direction of the force required to restore the pendulum to the null position.