Panametrics, Inc.

Norman E Pedersen

James E Bradshaw

Lawrence C Lynnworth

James E Matson

An apparatus and method for changing the optical and/or physical properties of a fluid composition employ an electric field applied across the fluid for controlling the fluid properties. The fluid consists of a dielectric liquid and an electrically conductive, elongated, fibrous particulate material. The fibrous material has a length between approximately 1000 angstroms and five millimeters, a diameter less than about 700 angstroms, and an aspect ratio of length to diameter greater than about five. The particulate material is in colloidal suspension in the liquid. Generally, when the particles are dispersed in the liquid by Brownian movement forces, the fluid composition has an average separation between particles of approximately three to ten or more times the average length of the particulate material. By varying the direction and/or intensity of the applied electric field, the properties of the fluid to both incident light passing therethrough and, with respect to properties such as viscosity, can be controlled and varied. Relatively low electric fields can be employed, for example, between about 100 and 2,000 volts per centimeter.

Method and apparatus for electrically altering properties of a colloidal

A photometric detection method and apparatus employ a variable beam modulation device, such as a planar oscillating disk whose reflectance and transmittance with respect an incident beam of electromagnetic radiation vary with disk angular position, to form, from an incident beam of radiation, two amplitude modulated correlated component beams. Preferably the amplitudes of the component beams vary sinusoidally, 180.degree. out of phase. In one illustrative embodiment, one of the component beams passes through a sample fluid, which absorbs a portion of the radiation at a wavelength characteristic of a selected component. The second component beam passes through a reference path and provides a reference signal relative to which changes in the sample fluid are measured. A feedback mechanism is provided to automatically adjust for variations which can occur while the apparatus is operating. The component beams are combined and are directed onto a detector which produces an output proportional to the intensity of the combined beam. By properly selecting the parameters of the system, the AC component of the combined signal, if any, provides a sensitive measure of the presence generally and if calibrated the relative density, of the selected sample fluid.

Method and apparatus for feedback stabilized photometric detection in

An acoustic burst with a predetermined amplitude envelope is triggered by a square wave signal and transmitted upstream or downstream to a transducer connected to an adaptive control system which tracks the midpoint of the received envelope. The received signal is rectified and fed via a polarity reversing circuit controlled by the square wave to an integrator whose output level controls the frequency of the square wave. The burst transit time is measured to the next zero crossing of the received signal following the half cycle transition point of the square wave.

Acoustic flowmeter with envelope midpoint tracking

A photometric detection method and apparatus employ a variable beam modulation device, such as a planar rotating disk whose reflectance and transmittance with respect an incident beam of electromagnetic radiation vary with disk angular position, to form, from an incident beam of radiation, two amplitude modulated correlated component beams. Preferably the amplitudes of the component beams vary sinusoidally, 180.degree. out of phase. In one embodiment, one of the component beams passes through a sample fluid, which absorbs a portion of the radiation at a wavelength characteristic of a selected component. The second component beam passes through a reference path and provides a reference relative to which changes in the sample fluid are measured. The component beams are combined and are directed onto a detector which produces an output proportional to the intensity of the combined beam. By properly selecting the parameters of the system, the AC component of the combined signal, if any, provides a measure of presence generally and if calibrated the relative density, of the selected sample fluid. In a second embodiment, a beam of polychromatic radiation passes through, and a portion thereof is absorbed by, the sample fluid before the beam impinges on a beam modulation device for forming the time-varying component beams. The thus formed component beams are filtered so that one component beam has energy substantially only at the sample fluid characteristic wavelength, and the other component beam has energy in energy bands which are unaffected by changes in the component of the sample fluid being measured. The component beams are combined and the AC component, if any, is detected and/or measured. In a third embodiment, a second movable element is supported in the path of the incident polychromatic radiation beam and serves as a variable, substantially monochromatic, filter for sequentially transmitting different energy bands to permit time sequential detection and/or analysis of a fluid medium at a plurality of wavelengths of interest.

Method and apparatus for detection and analysis of fluids

An ultrasonic flowmeter for determining fluid flow velocity within a conduit by determining the difference in transit time between interrogating ultrasonic pulses transmitted upstream between a pair of transducers and transmitted downstream between them. A high frequency clock pulse operating for one or more cycles of interrogation allows for accurate digital computation.

Ultrasonic flowmeter

A method and apparatus for determining volumetric fluid flow rate in an arbitrarily shaped fluid conveyance are disclosed. A plurality of functions, f.sub.j (p,m.sub.k) (where p is a position in the conveyance and m.sub.k depends upon the Reynolds number of the fluid flow), each function being approximately representative of the fluid flow velocity across the conveyance, are linearly combined to approximate the velocity, P(p), of the fluid flow at any point in a plane normal to fluid flow. The scalar constants A.sub.j,k, of the linear combination ##EQU1## are estimated by solving a system of linear equations, ##EQU2## in which acoustical measurements along the paths y.sub.i through the conveyance provide an estimate, v.sub.meas(i), of the actual average velocity v.sub.i at paths y.sub.i. The average fluid velocity and hence volumetric flow across the conveyance can then be determined by taking an area integral of the linear combination ##EQU3##

Method and apparatus for determining fluid flow

An apparatus and method for examining the structure of and in particular detecting flaws within a solid are disclosed. The transmitting source directs pseudo-random coded, phase modulated, interrogation signals, at a plurality of frequencies, toward the object being examined. At the receiver, the returning interrogation signals, reflected by structure within the solid object, are demodulated, employing a delayed replica of the pseudo-random code, and are thereafter processed to provide, preferably, both the phase and magnitude of the returning signals relative to the transmitted interrogation signals. The delayed replica of the pseudo-random code provided to the receiver is delayed by selected time increments to provide a range gate. Thus, the data provided by the receiver represents the amplitude and phase of returning signals as a function of both transit time and frequency. By maintaining a sufficiently small transmitting beam or field of view, the resolution of the beam can be made quite small; and for each source transducer position, the transit time can be related to a known examination cell of the solid. The preferred method of the invention further comprises forming determinants based upon at least the phase and magnitude signals to provide an analysis of the solid structure. In preferred embodiments, the frequency may be sequentially varied according to a predetermined pattern, or a plurality of frequencies can be directed toward the object simultaneously. In either circuit configuration, switches and narrow band filters may be provided for separating the received returning signals.

Method and apparatus for examining a solid

In the acoustic flowmeter apparatus disclosed herein, repetitively gated bursts of relatively high frequency acoustic energy are transmitted between upstream and downstream transducers in a conduit in which flow is to be measured, the transmission being alternately in an upstream and a downstream direction. The received signals are amplified and subjected to narrow band filtering so as to extract an essentially continuous component at the high frequency, preserving phase information. By measuring the relative phase shifts of the upstream and downstream transmissions, a measurement proportional to flow rate is obtained. In the preferred embodiment, the sum of the transit times is measured by measuring the phase shifts of the principal repetition frequency modulation component of the received signals.

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Wilmington, MA, United States of America

Norman E Pedersen