Abstract: A surge enhanced cavitating jet for a fluid jetting system. The cavitating jet includes a nozzle portion having a conical throat followed by a fluid separating section. Immediately downstream from the separating section is a substantially cylindrical surge section. The length and inside diameter of the surge section are sized such that a minimum annular area is defined between the inside diameter of the surge section and the outside of the fluid stream as the fluid discharges from the cavitating jet such that cavitation is contained in the surge volume. The fluid stream does not impinge the inside diameter of the cavitating jet. A jetting system including a pump and valve is also disclosed.

Abstract: A control system and method utilizing a race between two responses to a changing stimulus are disclosed. An example of a changing stimulus is pressure which increases at a decreasing rate of change during a closed-in period of a drill stem test in an oil or gas well. In a preferred embodiment two components are moved in different directions, but in a net first direction, until the rate of change of the pressure is sufficiently low (e.g., near steady state), at which time the rates of movement of the two components produce net movement in a second direction. In a preferred embodiment, the change in direction of the net movement moves a control valve which communicates a pressure control signal for opening a bypass valve to commence a flow period of the drill stem test.

Abstract: A pressure control apparatus suitable for controlling pressures in autoclaves permits a plurality of autoclaves to be selectably pressurized from a single pressurizing circuit. The apparatus can be externally controlled to more efficiently multiplex autoclaves to the pressurizing circuit and to more efficiently implement different pressure schedules for the autoclaves. Once a pressure has been set for an autoclave maintained in communication with the main pressurizing circuit, the apparatus automatically monitors the position of the pump piston and resets it from either of its extreme limits of movement to maintain pressure at a desired set point. Corresponding methods are also disclosed.

Abstract: A set point pressure control circuit is disclosed for controlling pressure in a high pressure environment. The circuit includes a high pressure communicating, low pressure actuated valve. The valve includes a housing in which a valve member is disposed. The valve member has an axial passageway defined therethrough for communicating a high pressure port across a piston of the valve member to an opposite high pressure chamber which is placed in communication with a low pressure port when the valve member is in an open position.

Abstract: A security apparatus for interfacing a computer system with a telephone circuit includes a modem and a controller interfacing between the telephone circuit and a modem of the computer system. The first-mentioned modem and the controller operate to answer incoming calls in a manner to disguise that the telephone circuit is connected to a computer system, thereby masking or hiding the computer system from unauthorized users such as "hackers.

Abstract: An apparatus for use in a railway train simulator includes a control station which has a first microcomputer for receiving and transmitting, via a conventional transmission protocol, train simulation signals to a second microcomputer. The second microcomputer provides master control for the apparatus. The second microcomputer is adapted to link with and operate from multiple control stations and multiple computer control terminals. Information is provided in an enhanced manner through one or more color graphics terminals, plotters and printers. Displays of simulated trains and track selections can be displayed at different, selectable scales.

Abstract: An appartus and method for testing characteristics of a substance, such as a cement slurry to be used within an oil or gas well, are provided. The apparatus includes a single drive motor which can be actuated in either a dynamic mode or a static mode to measure, in the preferred embodiment, either consistency or static gel strength of the substance. A single display is switchably connectible to one of two scaling circuits which scale a single transducer output signal to provide the desired measurement.

Abstract: A pressure controller includes a set point switch mechanism by which a selectable pressure to be maintained in a pressure vessel can be set. The actual pressure in the pressure vessel is detected and converted into a corresponding electrical signal by a suitable pressure transducer. Electrical signals from the set point switch mechanism and the transducer are utilized by a computer to generate control signals for controlling a volume adjustment mechanism which adjusts the effective volume of the pressure vessel and adjusts the quantity of pressurizing fluid disposed in the vessel. The volume adjustment mechanism includes a piston disposed in a cavity which is connectable with the chamber of the pressure vessel. The volume adjustment mechanism also includes a stepper motor which can be moved in precise increments to adjust the position of the piston in the cavity.

Abstract: An optical reader contained in a portable case includes elements for rotating a chart containing indicia and for moving a lens and photo-responsive member substantially parallel to the axis of rotation of the chart. These elements are controlled so that the photo-responsive element detects every one of an array of discrete informational units defined by the optical reader on the chart and for generating for each discrete informational unit a respective binary bit having one of two logic values depending upon whether the respective discrete unit is relatively light or relatively dark. The reader also includes circuit elements for detecting every eighth one of the respective binary bits to define a byte of information representing eight of the discrete informational units of the chart. The reader is controlled to commence a read of the chart from the right-hand end and to incrementally read strips of the chart progressing to the left-hand end of the chart.

Abstract: A local station and a central computer subsystem remotely located from each other are interconnected by a transmission system, such as a telephone network, so that a medium containing visual data can be read in the vicinity where the cart is made, but automatically analyzed by a computer at the central computer subsystem. The local station includes an optical reader device for reading the medium and converting the visual data contained thereon into numerical data in the form of binary electrical signals. The binary electrical signals are compressed by a hardware compressor circuit and a software compressor program so that the transmission time for transmitting the data to the central computer subsystem is reduced. Once the data is transmitted to the central computer subsystem, an analysis of the data is made after any desired modifications of the data have been made through a graphics terminal.

Abstract: A high-speed interface for use between a computer having a Unibus data transmission system and a Tektronix graphics terminal includes elements for converting pairs of coordinate words from the host computer into five seven-bit bytes usable by the Tektronix graphics terminal. The interface is capable of emulating a standard interface device and is also capable of cyclically refreshing the Tektronix graphics terminal so that it can operate in a write-through mode.

Abstract: A data compressor includes circuit elements for counting the number of bytes transmitted in a binary bit stream and further includes storage circuit elements for temporarily storing each byte transmitted in the stream and the corresponding byte count of each byte. The data compressor also includes combinational logic control circuitry for detecting when one of the bits in a temporarily stored byte has a predetermined logic value and for generating a retain data control signal for signalling that the byte contains data desired to be retained.

Abstract: An apparatus for converting pressure into motion includes a housing having a plurality of ports formed therein. Movably disposed within the housing is a piston having a first plurality of apertures communicating with a first chamber and a second plurality of apertures communicating with a second chamber therein. The piston is positioned within the housing so that the apertures can register with consecutive ones of the ports as the piston is moved in either of two directions within the housing. The movable member is moved by a pressurizing substance applied to a selectable one of the ports through an appropriate valve circuit. The valve circuit is operated by excitation signals from a control member. By operating the valve circuit in an appropriate sequence, the pressurizing substance is sequentially applied to consecutive ones of the ports to move the piston longitudinally through the housing.

Abstract: An improved diffuser for a wellhead isolation tool which employs a combination of angles in its bore. This improvement reduces the incidence of erosion caused by the flow of fluids through the diffuser, in both the well production tubing adjacent the end of the diffuser and in the diffuser itself.