Abstract: A method for regulating the sodium carbonate concentration of a green liquor in the dissolving tank of the Kraft recovery process by measuring the conductivity of the green liquor from the dissolving tank, measuring the conductivity and flow rate of a weak wash solution being added to the green liquor in the dissolving tank, using these measurements to determine the sodium carbonate concentration of the green liquor in the dissolving tank, and adjusting the volume of the weak wash solution being added to the dissolving tank in response to changes in the concentration of sodium carbonate in the green liquor so as to maintain the concentration of sodium carbonate in the green liquor at a predetermined, preferably constant, level.

Abstract: A vortex sensor 14 measures a flow rate of a fluid flowing through a flow passage by detecting alternating pressure variations 26a and 28a generated by a shedding body 16 placed in the flow passage. The vortex sensor 14 includes a sensor housing 32 enclosing piezoelectric sensing elements 62, 64 which are acted on by a movable member 30. The lifetime of the sensing elements in the closed interior is enhanced by providing surface barriers, oxidizing exposed interior surfaces, or providing a gas reservoir. In applications where fluid leakage may be accepted, a controlled leak restrictor provides a limited rate diffusion path to the atmosphere allowing a minimum partial pressure of oxygen to be maintained.

Abstract: An integrated circuit board assembly includes two integrated circuit boards. The integrated circuit boards have an electronic circuitry configured on the interior face and a dielectric sealant on the other face. The integrated circuit boards are secured to a frame in such a manner that the interior faces of the integrated circuit boards face inward toward each other. The securing of the frame to the integrated circuit boards is such that it forms a sealed enclosure protecting the electronic circuitry configured therein from the process environment. The exterior faces, however, are exposed to the process environment and are helpful in dissipating heat to the exterior environment.

Abstract: Radiant energy is transmitted to a probe element including an interior conical reflecting surface and a fluid sample chamber. Portions of the light which have been transmitted, partially attenuated, or scattered by a fluid sample in the sample chamber are directed by at least a portion of the interior conical reflecting surface to means for collecting the transmitted, partially attenuated, or scattered light. A stilling valve incorporated into the probe element enables elimination of entrained gas bubbles from the chamber. A specific application of the probe is disclosed in which a titration analyzer is combined with electro-optic signal conversion and processing circuits and a probe according to the invention to provide titration colorimetric endpoint determination in measuring the free fatty acid content of a fluid such as a edible oil or fat.

Abstract: An electrodeless conductivity measuring cell having three toroids. In one arrangement, the three toroids are stacked together wherein the center toroid is used for sensing and the two outer toroids are the drive toroids. Alternatively, the center toroid may be used as the drive coil and the outer toroids used as sense coils. Washer-shaped, grounded discs are placed between the outer toroids and the center toroid to provide for improved noise rejection. A method of validating the fluid conductivity measurement of such a measuring cell. The fluid conductivity is measured with a three-cell configuration, and then it is measured with a two-cell configuration. If the conductivity is observed to be the same, the cells are likely functioning normally. If fluid leaks into the cell cavity, the measurement of conductivity will change.

Abstract: A statistical process control system provides asymmetrical nonlinear automatic closed-loop feedback control. The system has application, for example, in the control of equipment that responds to a controlled variable signal to vary a measurable characteristic of a process. The system uses an accumulated deviation of a measured subgroup means minus a target value, divided by the subgroup standard deviation, to modify the manipulated variable each time the accumulated value exceeds a decision interval above or below the target. The system permits the use of independent slack variables subtracted from the accumulated deviation to more closely model the underlying process. Likewise, the system permits the use of independent alarm values and variable gains to permit greater control of the process.

Abstract: Processing plant control apparatus provides real-time indications of performance of plant operations with respect to curent state of process means. The real-time indications enable operations personnel to timely adjust process means to improve current performance of plant operations. Sensors coupled to the process means provide data input to the computer means of control apparatus. The computer means performs programmed computations on the input data to provide quantitative information of current performance of plant operations. The control apparatus provides the computer information in a graphical form displayed on video displays. Video displays of the computed information over time are also provided. The control apparatus also stores the computed information in a relational database which enables access to the information for other applications.

Abstract: A monitoring system for testing the integrity of seal structures, filled with an electrically non-conductive fluid and for validating measurements of a measurement device. The monitoring system includes electrodes disposed in the fluid for measuring an electrical property of the fluid. The system indicates when the measured electrical property changes, which indicates contamination of the fluid.

Abstract: A differential pressure measuring system comprising a transmitter for a pressure-measuring instrument connected to a control room by a two-wire transmission line carrying a d-c signal powered from the control room and representing the measured pressure. The instrument includes a reference pressure device of the falling-ball type, wherein a ball is first lifted to an upper position and then allowed to descend under the force of gravity to produce a reference pressure pulse for calibrating the instrument span. The lifting device for the ball is a two-coil magnetic actuator powered by current from the two-wire transmission line, and is operable at a sufficiently low current to be classified intrinsically safe. The reference pressure device is supported by an adjustable mounting providing two degrees of freedom for movement so as to permit ready adjustment of the device orientation to assure alignment with the force of gravity.

Abstract: A density insensitive mass flowmeter for measuring mass flow of fluid includes a continuous conduit loop with at least two resonant modes of oscillation of conduit and at least one dummy mass disposed on the conduit at a vibrational node of one of said resonant modes of oscillation. The dummy mass has a mass and position on the conduit such that the ratio of resonant frequencies of the resonant modes remains substantially constant for different densities of fluid flowing through the conduit.

Abstract: Displacement sensors at opposite ends of at least one oscillating conduit produce output signals from which the drive component or the Coriolis component, or preferably both, are recovered. An oscillatory drive signal is derived from the drive component, and a mass flow signal is derived from the Coriolis component. The remaining drive component in a combination of the two sensor outputs is nulled by amplitude control of one sensor output. Two force drivers at opposite ends of the conduit are driven by complementary drive signals to which a perturbation signal is added. The remaining perturbation signal in a combination of the two sensor outputs is nulled by adding compensation to both drive signals to eliminate drive force imbalance. Synchronous demodulation is used in the preferred embodiment to detect several parameters in a combination of the sensor outputs. In a dual loop configuration, pairs of sensors and/or force drivers are located at opposite ends of each conduit section.

Abstract: A shielded electromechanical device for use in a Coriolis type mass flowmeter for interconverting mechanical energy and electrical energy has a coil assembly connected to its distal end, and a magnetic assembly connected to its proximal end. The magnetic assembly is adapted to interact with the coil assembly. A shield assembly surrounds the coil and magnetic assemblies and is adapted to reduce the magnetic field exterior to said shield assembly.

Abstract: Multivariable adaptive feedforward control may be accomplished by detecting the beginning and ending of load transients, characterizing the inputs and process result during the transient by moments, and relating the characterized inputs and process result in a general transfer function model to generate transfer functions relating the input to the output. The transfer functions coefficients are refined with successive disturbances by projecting from the current solution to the nearest point in an updated solution space. The transfer function coefficients of the selected solution are then used in compensators acting on the feedforward inputs to adjust a process control output to counteract the anticipated effects of the inputs.

Abstract: A flex circuit connector assembly of the present invention includes folding one end of a flex circuit having contact pads to form a male contact portion. The male contact portion is then inserted into a female socket of an edge connector for electrically interconnecting the contact pads of the flex circuit to mating contacts disposed in the female socket of the edge connector. The edge connector includes pins for mounting it to a receptacle of a wired circuit.

Abstract: A CAD driven photoplotter selectively exposes a photographic imaging layer without affecting the underlying UV sensitive resist on a substrate to make a printed wiring board, for example. The image layer is developed on the board and used as an in situ mask for the underlying UV resist during exposure to UV. After UV exposure, the image layer is peeled off to allow conventional processing of the resist. The in situ mask is preferably applied in the form of a baseless, high contrast, high gamma emulsion layer bonded to the protective cover sheet over the uncured resist. To facilitate application, the emulsion layer is carried by a release paper which is removed before photoplotting. After UV exposure, the cover sheet and emulsion layer are integrally peeled from the resist.

Abstract: In accordance with the present invention, radiant energy is transmitted to a probe element including an interior conical reflecting surface and a fluid sample chamber. Portions of the light which have been transmitted, partially attenuated, or scattered by a fluid sample in the sample chamber are directed by at least a portion of the interior conical reflecting surface to a location for collection of the transmitted, partially attenuated, or scattered light. A stilling valve incorporated into the probe element enables elimination of entrained gas bubbles from the chamber.

Abstract: A multiple pin block having a distinct electrically readable pin pattern and a corresponding visually readable label is useful as an identifier for electronic modules and other elements in electrical networks. Differing blocks each with identifiable labels, and corresponding electrical pin patterns may be inserted in devices to identify and distinguish the differing network modules or lines and thereby facilitate assembly, maintenance, testing and operation.

Abstract: A vortex sensor 14 for measuring a flow rate of a fluid flowing through a flow passage. The flow rate is measured by detecting alternating pressure variations 26a and 28a generated by a shredding body 16 placed in the flow passage. The vortex sensor 14 includes a sensor housing 32 having two cavities 44 and 46 interconnected by a channel 42. An Axle 52 of a spool member 34 is slideably disposed in the channel 42 and allows each of two flange members 54 and 56, connected proximate each end of the axle 52, to shuttle back and forth with respect to the sensor housing 32. A piezoelectric sensing element 62, 64 and a biasing mechanism 58, 60 are disposed between the flange members 54 and 56 and the sensor housing 32. The alternating pressure variations are applied to each flange member 54, 56 causing the spool member 34 to shuttle back and forth. When the spool 34 moves, mechanical forces are coupled to each sensing element 62 and 64 by biasing mechanisms 58 and 60.

Abstract: A solid state measurand sensor is described in which the pressure sensor element is protected from the measurand by a combination of a pressure transfer medium and a thin covering membrane. A method is described for forming the diaphragm in situ. The diaphragm material is selected from a group of materials which includes fluorosilicone, so as to substantially avoid entrapment of air or formation of voids in the pressure transfer medium such as would degrade the performance of the sensor. The pressure transfer medium is gel-like material such as dimethyl silicone and equivalents. Alternatively, the gel may be fluorosilicone and the diaphragm may be dimethyl silicone. The membrane material is chosen to be substantially impermeable to the ambients or process media being measured and also flexible, is to be poured and cured in place on the assembly during fabrication.

Abstract: A soft start, self-powered coupling for connecting a motor to a load, the coupling including a magnetic particle clutch, a generator having a rotor carried by the clutch and a stator, and an electronic control circuit assembly carried by the generator rotor, the magnetic particle clutch being connector to the motor and to the load, the generator powering the electronic control circuit assembly and the clutch to provide linear timed acceleration of the load.