Abstract: An acoustic transducer has an output which is fed through a preamplifier to a multiple of parallel filters. Each parallel filter passes a band of signals having frequencies within a predetermined range of frequencies. Each band of signals is converted from analog to digital and input to a signal processing unit. The peak amplitude value and the average value of the output from each parallel filter is determined. The peak amplitude value and average amplitude value are compared to determine if a pretrip condition occurs. If a pretrip condition occurs, the average value is saved and compared with the peak amplitude value for a select number of time periods to determine if a trip condition exists. A special test can be used which alters the number of time periods used in determining if a trip condition exists, based on a comparison the peak amplitude value between two of the bands.

Abstract: A real time remote sensing pressure control system is provided which uses periodically sampled remote sensors to generate a bias signal that modifies the base setpoint of a proportional-integral controller that controls variable speed pumps. This control scheme saves energy by slowing the rotational speed of the variable-speed secondary pumps during periods of light system demand. The system can be provided with more than one zone of system loads (such as chilled or hot water coils) and a remote pressure sensor (gauge or differential) can be provided at each of those zones. In addition, a local pressure sensor (gauge or differential) is provided at the primary and secondary pumps. The process variable signals detected by the remote pressure sensors is communicated by a building automation system or other type of data highway, which inherently delays the real time nature of those sensed signals and only periodically provides an update of those signals.

Abstract: A multiple set point material condition monitoring system is responsive both to the level of material with respect to a sensor and the extent of material coating which has accumulated on the sensor. The system provides an output when a predetermined coating thickness has been exceeded, so that the sensor may be cleaned before the coating can accumulate to the extent where a false level output is generated. The systems include three electrode guarded sensors, a bridge comparing the sensor output with a reference, and a bridge reference which is automatically and repeatedly caused to assume a sequence of values corresponding to material condition set points, one of which causes an output when a predetermined coating thickness has occurred and another of which generates a level output. In one embodiment, separate outputs are provided corresponding to each set point. In another embodiment, a single tri-state output is responsive to both set points.

Abstract: The present invention relates to a modular compressed natural gas fuel unit comprising generally a tank adapted to contain compressed natural gas and a fuel supply unit integrally attached to the main valve of the tank.

Abstract: The safety switch assembly is designed to provide a switch assembly to a tool, such as a meat slicer, in order to prevent the operation of the tool without manually holding the pressure sensitive safety handle. The assembly contains a control box having a ground fault interrupter/on-off switch, signal device, a power receptacle and a control circuit. A safety handle is installed on the tool and the handle has two pressure sensitive strips which function as a dual force sensing resistor and is connected to an electric cable that connects the safety handle to the control box which houses the control circuit. The operation of the tool requires that power be supplied to the control box. When the individual grips the safety handle and squeezes the handle, the control box provides power to the tool itself.

Abstract: A pulse-width modulated (PWM) circuit alternately applies voltage from a power supply across a load, and alternately establishes one or more non-powered, closed paths for freewheeling current. The circuit includes pairs of switches connected to the load and also connected to the power supply. PWM signals derived from a command signal drive the switches in such a manner as to create the freewheeling current paths in a desired pattern and sequence. The circuit effectively reduces ripple current in the load while also substantially reducing the amount of current flowing through the power supply filter capacitor. Thus, the size and rating of the power supply can be reduced. One can use the invention to drive a load in a multiple-phase environment, and also in the context of a three-phase trapezoidal drive.

Abstract: A rotary actuator for opening and closing a valve, damper or linkage for industrial application, the actuator including a housing having a motor mounted thereon for driving a speed reduction gear train to reduce the speed of the motor, the rotary motion of the output shaft of the speed reduction gearing to linear motion against the force of a biasing spring to convert the linear motion of the converting motion to rotary motion of the output shaft.

Abstract: A method for measuring the permeability of a gas through a material, wherein the steps include exposing the material to the gas to be measured and measuring the outgassing characteristics of the material over increments of time, to develop exponential expressions representative of the measured amounts, and solving the exponential expressions for the diffusion coefficient D and the solubility coefficient S; and then calculating the permeability of the material by forming the product of the diffusion coefficient D and the solubility coefficient S.

Abstract: An instrument system provides compensation for signal processing errors by processing both sensor signals and reference signals in a common signal processor. Reference signals may be provided which enable zero compensation, gain compensation, or both. The system outputs compensated signals to a two wire signal loop in either analog or digital form, and selects the form of output signal in accordance with digital input signals received from the signal wires. The system may be embodied as a radio frequency admittance instrument system for monitoring the condition of materials.

Abstract: A valve for fail-safe return to its normally closed condition relies upon solenoid-driven elongation of a magnetostrictive core element, for opening displacement of a valve member, and also relies upon a continuously available, stiffly compliant preload of the valve member into its position of lock-up at valve closure. The currently preferred material of the core is Terfenol-D, which offers a strong elongation response to inductively coupled excitation. The elongation response is sufficient to serve the purposes of driving a poppet-valve member from closed to open position, with a relatively short time constant, as well as to permit a closed condition of the valve wherein the driving end of the core is effectively disconnected from the poppet-valve member, so that the prestressed stiff compliance can alone be operative on the poppet-valve member for fail-safe closure of the valve.

Abstract: A switchmode AC power controller for controlling the current through a load such as a large lamp array connected to an alternating current source. The controller contains an AC solid state switch, a synchro-flywheel, an output inductor and capacitor. The load current is controlled by triggering signals generated by a synchronized modulator.

Abstract: A watertight enclosure for the retention of air-cooled electrical and electronic components, which enclosure includes a labyrinth diverter system of baffles and barriers to divert any water or other liquid, that may enter the enclosure away from the components therein.

Abstract: A thermal relief device releases gas from a storage cylinder when a thermal trigger senses a predetermined temperature threshold. The thermal relief device includes a valve body which has a passage for communication with the interior of the cylinder. A pilot valve assembly is disposed within the valve body and has a popper for blocking the flow path. The poppet has a longitudinal passage extending through the popper. A metal diaphragm sealing the passage of the poppet has a first side exposed to the interior of the cylinder and a second side opposite the first side exposed to the outlet. A hollow bayonet is mounted in alignment with the passage of the popper on the outlet side of the disk and is moveable between a first position and a second position. In the first position, the bayonet is spaced from the disk in the passage, and in the second position the bayonet pierces the disk. A spring is used to biased the bayonet toward the disk.

Abstract: A digital process generates a pulse-width modulated (PWM) signal for providing current to a load. In one embodiment, an input signal is repeatedly sampled at times corresponding to edges of a reference square wave. The sampled values are used to produce a PWM signal, each pulse of the PWM signal having a width corresponding to one of the sampled values. In another embodiment, the sampled values are used to produce a series of intermediate pulses, the intermediate pulses being used to construct an output PWM signal. The pulses of the output PWM signal generally have leading and trailing edges which do not coincide with the times at which sampling occurs. Therefore, in the second embodiment, sampling does not occur when the PWM signal is opening or closing a switch, and the sampling tends to occur near the average value of the input signal.

Abstract: A microwave waveguide is presented which includes a gas tight seal which provides pressure isolation between two portions of the waveguide. In accordance with an important feature of this invention, an upper flange includes a threaded axial opening for receiving and retaining a threadably mated dielectric filling material. If the thread pitch is small relative to the signal wavelength, the threaded section has essentially the same electrical characteristics as a smooth waveguide. The resulting structure provides an economical and practical method of retaining a solid dielectric filling material in a waveguide against high pressure without changing the effective diameter of the waveguide. In accordance with another feature of this invention, a novel high pressure seal is provided between the upper and lower flanges in the area surrounding the threaded axial opening.

Abstract: A pulse-width modulated (PWM) circuit provides current through a load by opening and closing main electronic switches which connect the load to a power supply. Each main electronic switch connects with an auxiliary switch, connected in series with a diode, the auxiliary switch and diode being called "recovery paths". The recovery paths provide a path between the load and the associated main switch, on one side, and the power supply on the other. A first train of pulses, derived from a command signal, drives the main switches, and a second train of pulses, derived from the first pulse train, controls the switches in the recovery paths. One arranges the second train such that the recovery paths carry current only while the main switches change from on to off, or from off to on. In this way, the recovery paths carry part of the current that would otherwise flow transiently through the main switches, due to the inherent inefficiencies in semiconductor switching.

Abstract: On-line control of a process is achieved by feedforward computations of manipulated variable setpoints modified during each of frequent optimization cycles by feedback trim determined by actual versus predicted effects of setpoint changes on the process controlled variables. Process, economic, contractual and equipment parameter values are continuously polled and collected and used to compute the optimal setpoints for the manipulated variables before the feedback trim is applied. Drift factors are added to the feedback trim to provide on-line calibration of key measuring instruments. Drifts in process performance are updated on-line periodically through self-tuning routines computed as calibration factors for predictor and control equations based on rigorous process simulations and actual plant performance. The equations take the form of polynomials in which each term contains an adjustable coefficient and one or more variable process parameter.

Abstract: In a preferred embodiment, in a fluid flow valve having a body and having a movable member with lower face, the movable member being movable between a position spaced from a sealing position in the body when the valve is in an open position and movable to the sealing position when the valve is in a closed position, the improvement including: an annular sealing member disposed in the outer periphery of the lower face of the movable member to sealingly engage a portion of the body when the valve is in the closed position.

Abstract: A dispenser produces negotiable money orders, traveler's checks, and the like at remote locations and prints the check amount on the check while also printing summary data of a day's activities on a blank check form, eliminating the need for a separate printer and paper supply. The dispenser prints the check amount using print icons that form a part of each character in the check amount, but are not as large as a complete character or as small as a dot print element. The check forms are connected together by perforation ties, and the dispenser feeds the forms to the printer such that the force with which the dispenser holds the forms is greater than the force needed to tear apart the forms, thus reducing the risk of unauthorized pulling of blank forms from the dispenser.

Abstract: A strobe light mounting system for underwater cameras with arm segments clamped together with side clamps that grasp balls on the ends of the arm segments. The arm segments are rigid, light, and low in water resistance because they have four longitudinal channels pierced by mutually orthogonal transverse holes of large diameter so that longitudinal ribs are preserved at the maximum diameter of the arm segment. Water flows easily through the orthogonal holes permitting easy movement underwater.