Abstract: A device and method for determining the depth of contaminant of petroleum based products in a subsurface, such as after an oil spill. The device is implemented either as a manual probe or as attachment to excavating equipment. The device has an ultraviolet radiation source for irradiating waves into the subsurface, and a visible-light detector for receiving fluorescence, which is induced by the contaminant when the contaminant is exposed to the ultraviolet radiation.

Abstract: A system for sealing leaks in a nonconductive liner of a container of liquid or liquid-solid material. A voltage is impressed between an electrode in the material inside the container and an electrode in conductive material outside the liner. The system provides for a current path between these electrodes through any leaks that may exist in the liner. Solid particles suspended in the liquid in the impoundment accumulate at the leak as a result of electrophoresis, thereby sealing the leak. Although the system is especially useful for impounded waste materials, such as a landfill or surface impoundment, it may be used for many other types of containers.

Abstract: This invention is directed to detecting and locating leaks in geomembrane liners used to contain liquid or liquid-solid materials, such as in waste landfills and liquid impoundments. An array of electric or magnetic field detectors is placed on one side of the liner. The detector array is on a plane generally parallel to the liner, and the location of each detector is known. A voltage is impressed across the liner. When a leak occurs in the liner, a current flows through the leak, creating an electric field and a magnetic field around the leak. The existence of the electric or magnetic field is detected by the detector array, which indicates a leak. The leak is located with orthogonal measurements from selected detectors, and these measurements are used to geometrically locate the leak.

Abstract: A compact, low electrical noise power supply for fluorescent lights used in conjunction with a borehole television system. The outputs of first and second power sources are combined to initiate operation of the fluorescent light. After the operation of the light has been initiated, the second power source is disabled and the light is maintained in operation by the first source of electric power. In the preferred embodiment, the first source of electric power is a source of high voltage DC current and the second source of electric power is a high frequency oscillator. A transformer is provided to combine the outputs of the two sources of electric power. The operation of the oscillator is controlled by a momentary start switch which disables the oscillator after the light has been activated.

Abstract: A system for determining the position of a plurality of remotely located switches having a binary weighted current controlling means connected to each switch for providing a waveform having a unique duty cycle corresponding to the position of each of the switches. The duty cycle is decoded at a local test station to provide digital output data indicative of the position of each of the switches. The duty cycle encoder includes a switching means connected across a two conductor line that terminates the cycle of an input waveform generated by a source generator at said local test station. The current controlling means controls the output of a constant current source which depends upon the number of switches that are open and closed. A timing means is responsive to the output of said constant current source for triggering the switching means. The resultant waveform at the local test station has a duty cycle that is decoded to indicate the position of the remote switches.

Abstract: A system and method for sensing the status of a plurality of valves by detecting the total current flowing through a network of constant current devices connected in series with a plurality of limit switches responsive to the open and closed positions of the valves. The system uses a binary constant current encoding network to provide a total current that is a unique binary weighted indication of which switches are closed. The system includes a current measurement circuit that converts the current to a voltage, filters out noise and amplifies the voltage for input to an analog to digital converter. The output of the analog to digital converter is then decoded by a logic hardware or by a computer to derive a digital output indicative of the position of the switches. A bipolar voltage source energizes the constant current encoding network and interacts with the current measurement and decoding circuits to ensure a sufficient voltage level for constant current operation.

Abstract: The depth and lateral offset position of an underground pipeline or the like is calculated by a surface located instrument carrying two spaced sets of orthogonal antennas sensing electromagnetic energy induced in and radiated from the pipeline. The resulting four signals are compared in amplitude to derive by simple triangulation calculations the depth and offset distances in a simple computer-display unit. Thus a set of continuous reading may be made automatically by a self-contained portable unit as an operator tracks the pipeline to make a survey. The readings may be recorded upon a medium advanced by a measuring instrument as a survey progresses along a pipeline.

Abstract: A geophysical exploration system uses a single conductor cable connected to a current source, the cable having a number of earth probes coupled to it at spaced points with addressable switching units. The switching units are activated in sequence so that the probes inject current into the earth. At locations spaced from the probes the resistivity is measured and recorded for each injection. Resistivity measurements are compared with anomaly models to find a match of patterns, indicating the presence, size and location of an anomaly.

Abstract: A battery charger circuit having a temperature-dependent constant voltage region, a constant current region, and a power dissipation limiting current "foldback" region.