Abstract: A computer system displays a representation of a field of view of the one or more cameras, including a representation of a portion of a three-dimensional physical environment that is in the field of view of the one or more cameras. The computer system receives a request to add a first virtual effect to the displayed representation of the field of view of the one or more cameras. In response to receiving the request to add the first virtual effect to the displayed representation of the field of view of the one or more cameras and in accordance with a determination that the first virtual effect requires a scan of the physical environment, the computer system initiates a scan of the physical environment to detect one or more features of the physical environment and displays a user interface that indicates a progress of the scan of the physical environment.

Abstract: A bidirectional hydraulic drilling jar includes an elongated mandrel telescopingly disposed within a body and defining spaced apart fluid chambers separated by a restricted bore portion of the body. The mandrel is provided with spaced apart positive mechanical seal assemblies engageable with the restricted bore portion to form a hydraulic dashpot to retard movement of the mandrel in each direction over a limited stroke length so that the spring tension or weight of the drill stem may become effective to deliver an impact blow when the seal assemblies move out of sealing engagement with the restriction. Back-to-back check valves are arranged to bridge the respective seal assemblies to reduce the length of stroke required to cock and trip the jar in each direction. A separate orifice or flow restricting passage is provided across the seal assemblies so that the retarding effect is independent of coacting seal surfaces between the mandrel and the jar body.

Abstract: An improved method of electric fish trawling which utilizes the fright-reaction exhibited by fish exposed to an electric field is disclosed. The method utilizes a trawling net equipped with electrodes which emit DC pulses having a repetition rate of six cycles per second or less, a pulse duration of approximately one millisecond, and producing a field having a voltage gradient of one-hundred eighty volts per meter. A pulse generating circuit, which uses full-wave rectified single phase power or three phase, half-wave rectified power for a condenser discharge circuit is also provided.

Abstract: A new and improved portable hydraulic rig for performing workover, drilling or other operations on a well, usually a petroleum well, wherein the rig has a telescoping mast for telescoping to a reduced length for transportation, wherein the mast is cantilevered in use so that the travelling block moves vertically at one side of the mast, wherein the cable for the travelling block is reeved over the various sheaves including a sheaves on a hydraulic power assembly with the dead end of the line being fastened at or in proximity to the rig floor for balanced loading on the legs of the mast and to enable slack in the cables to be taken up when telescoping the mast.

Abstract: An apparatus for daylight shrimp fishing is disclosed. The apparatus includes a plurality of Otter trawls each having an electrode array and a pulse circuit. Each pulse circuit includes a capacitor which is discharged by a reversal of current to the capacitor which fires an SCR. A control unit located on the boat effects the discharging of the respective capacitors in a predetermined sequence to equalize the load on an alternating current generator. The electrode array has a plurality of electrodes which trail behind a bus extending between the trawl doors at a distance above the bottom. The electrodes are weighted to slide along the bottom and have an insulating material disposed above the conductor so that the electric current pulses are directed into the bottom rather than being dissipated upwardly into the water. The design of the bus and the electrode array is such as to insure uniform current density over the array.

Abstract: The specification describes a drilling jar for connection in a rotary drill string. There is a trap space in the jar for collecting the products of wear between its moving parts. The drilling jar includes a generally tubular housing assembly, which has near its bottom, a wash pipe sleeve. There is a tubular mandrel assembly extending into the housing and movable with respect to it, which has near its bottom a wash pipe that slides in the sleeve. An annular trap space is defined near the top of the sleeve between its outer surface and an inner surface of the housing. Wear products are collected in the trap space and thereby prevented from entering between the wash pipe and sleeve where they would cause abrasion.