Abstract: Method and apparatus for sensing fluid interface(s) in a complex fluid such as centrifuged blood, includes a sensing assembly with a microwave source and a microwave sensor positioned in spaced opposed relation, the microwave source and sensor defining a microwave propagation path. Relative motion is induced between the sample container and the microwave energy propagation path in the region between the source and sensor in a direction that intersects and is essentially perpendicular to the microwave energy propagation path; and processor apparatus responsive to the scanning apparatus and the modification in microwave energy sensed by the microwave sensor provides an indication(s) of the location(s) of a fluid interface(s) in the container.

Abstract: A particle analyzing apparatus having sample liquid pressurizing means for pressurizing sample liquid containing therein particles to be examined and supplying it to a portion to be examined, sheath liquid pressurizing means for pressurizing sheath liquid and supplying it to the portion to be examined in such a manner as to surround the sample liquid, a pressure sensor provided in the flow path of the sheath liquid between the sheath liquid pressurizing means and the portion to be examined, pressure control means for controlling the pressure value of the sheath liquid pressurizing means so that the output of the pressure sensor becomes constant, and means for applying light to the portion to be examined and photometering light emitted from the particles to be examined to thereby effect particle analysis.

Abstract: A molten metal inclusion sensor intended for "continuous" use in the testing of steel, i.e. a useful life of at least about 30 minutes, comprises a probe which is detachably connected to a water-cooled support member (35). The probe comprises a tube (30) of heat resistant material, preferably silica, having an inner electrode (31) mounted on its interior wall and an outer electrode (32) mounted on its exterior wall, the molten metal entering the tube interior through an orifice (33) upon its immersion in the molten metal, whereupon the flow of metal with entrained inclusions is monitored by measuring the voltage between the electrodes (31, 32). The electrodes (31, 32) are preferably of graphite and are shaped to fit closely against the walls of the part of the tube (30) that is immersed in the metal and are of a material that retains enough mechanical strength to support the tube (30) as the metal is pumped into and out of interior, the metal remaining hot enough for this pumping to occur.

Abstract: A position sensor (25) includes both a position potentiometer (90) and a turns count potentiometer (92). The position potentiometer (90) includes a pair of wipers (12 and 14) positioned on a rotor (10) which each contact both a resistive track (46) and one of two different commutator tracks (48 and 50) on element (26). The sensed percentage of total voltage output, which is a function of the position the wiper (12 or 14) contacts the resistive track (46), corresponds to the angular position between 0.degree. and 360.degree. of the shaft on which the position sensor (25) is mounted. The turns count potentiometer (92) comprises a turns count rotor (66) which is incrementally advanced via a cog (18) on rotor (10) using a gear or geneva type mechanism. The turns count rotor (66) includes a wiper (64) which either contacts both a resistive track (150) and commutator track (152) or contacts one of a plurality of switch pads (154).

Abstract: A molten metal inclusion sensor comprises a single use disposable probe which is detachably connected to a support member. The probe may comprise a tube of heat resistant material having an inner electrode mounted on its interior wall and an outer electrode mounted on its exterior wall, the molten metal entering the tube interior through an orifice in its wall past a jet-preventer insert upon its immersion in the molten metal, whereupon the flow of metal with entrained inclusions is monitored by measuring the voltage between the electrodes. Alternatively the tube may be of electrically-conductive heat-resistant material and constitute the inner electrode. The flow may be assisted by a reduced pressure established within the tube, or may be slowed by a positive pressure to maintain the Reynolds number of the flow below 2000.

Abstract: An automated gemstone sorting apparatus and method that handles, tests, and sorts a batch of irradiated topaz, or similar gemstones, in an efficient manner in accordance with residual radiation levels. The sorting apparatus and methods of the invention include a system of three parallel conveyors, i.e., input, accept and reject conveyors, as well as a vibrator bowl for automatically loading the gemstones in an orderly fashion onto the input conveyor. A multiplicity of isolated testing chambers is located to the side of the conveyor systems, each having a radiation detector and appropriate radiation measuring apparatus. Each of the isolated testing chambers has a single robot station associated therewith for manipulating the gemstones into and out of its respective testing chamber. Each robot station includes a pneumatic "puffer", responsive to a sensing device for directing a puff of air at a specified point on the input conveyor belt when a gemstone is sensed at the specified point.

Abstract: A method and appartatus for determining the parameters (i.e., proportion, mean, and standard deviation) of constituent subpopulations within a sample population of particles which contains overlapping populations. The invention includes the use of the EM algorithm, an iterative process which estimates the probability that a particle belongs to any given overlapping subpopulation.

Abstract: A method and apparatus for determining the power, momentum, energy, and power density profile of high momentum mass flow. Small probe projectiles of appropriate size, shape and composition are propelled through an intense particle beam at equal intervals along an axis perpendicular to the beam direction. Probe projectiles are deflected by collisions with beam particles. The net beam-induced deflection of each projectile is measured after it passes through the intense particle beam into an array of suitable detectors.

Abstract: A process and apparatus for calibrating a particle counter is described. The process comprises the steps of forming a vector gas flow by an aerosol of particles of the same grain size, developing ions in the vector gas with both sign by a bipolar charger, certain particles being electrically charged to a stationary charge state in which the distribution of the number of charges fixed to each particle follows a Gaussian law (Gunn or Boltzmann), passing the charge aerosol into a mobility selector to attract the charged particles to electrodes therein and classify them as a function of the numbers p of their elementary electrical charges e and allowing the electically neutral particles to escape, collecting the neutral particles and passing the neutral particles into the particle counter to be calibrated, the particles counter displaying a value N'.sub.o ; counting the values of N.sub.p and N.sub.

Abstract: A particle detector is designed to detect particles such as cells and blood corpuscles, and this particle detector includes means for passing and recovering a multilayer flow consisting of an inner layer A of conductive liquid specimen, a middle layer B of conductive first sheath liquid, and an outer layer C of nonconductive second sheath liquid surrounding them, in an orifice 12, and a pair of electrodes disposed on both sides of the orifice so as to contact the conductive liquid respectively. A detector circuit 44 is connected to the pair of electrodes so as to detect a particle signal on the basis of difference of electric impedance between the electrodes. The diameter of the orifice 12 is substantially the diameter of the middle layer. By varying the flow rate balance of the conductive liquids and nonconductive liquid, the diameter of the middle layer may be freely changed. Accordingly, the diameter of the orifice may be apparently changed as desired.

Abstract: A position determining device for an adjustment device including two continuous potentiometers having sliders movable to respective positions determininng respective resistance values of the potentiometers, the sliders being coupled with the adjustment drive so that the respective resistance values determined by the positions of the sliders correspond to a set position of the adjustment drive, a device for driving each of the sliders with a transmission ratio different from one another so that the potentiometers have a resistance value different from one another for a given set position of the adjustment drive, and a device for establishing a differential value from the different resistance values as a measure of the set position of the adjustment drive.

Abstract: A method and apparatus for millimeter wave flow cytometry of a cell stream hydrodynamically focused in a zone of interaction with a millimeter wave source and complex ratiometric receiver. The cell stream is characterized by complex power wave scattering parameters as a function of frequency, scattering angle and polarization. These parameters train a signal processor to sort specimen cells into one of a plurality of predetermined reference groups in accordance with a minimum number of normal cell types and functional states.

Abstract: In an apparatus for on-line particle determination in molten metals, a sample of molten metal is drawn through a calibrated passage while a steady current is established through the passage between two electrodes on opposite sides thereof. Particles moving through the passage produce voltage pulses whose magnitude and rate indicate respectively their size and number per unit volume. The wanted test signal can be obtained between the two current carrying electrodes, or between two other electrodes disposed on opposite sides of the passage. The electrodes form an interference-receiving antenna so that the wanted low signal/noise ratio test signal is overlaid with interference from neighboring sources. This interference is reduced by a cancellation signal produced by a cancellation antenna constituted by a similar pair of electrodes, either separate from the main current-carrying electrodes or having one of them in common.

Abstract: A method and apparatus are disclosed for obtaining a measurement indicative of the aspect ratio of non-spherical particles in suspension. Conductivity of the suspension is measured for two different orientations of the particles between measuring points and the difference between the conductivities measured is used as an indication of the particle aspect ratio. The particle orientation will be aligned in one measurement and in the other may be aligned and transverse to the first orientation direction or random. Alternatively, there may be a single aligned orientation but transversely directed conductivity measurements.

Abstract: A fluid flow system for use with an analytical instrument is provided having a sample reservoir for holding a liquid suspension of particles to be analyzed, a reagent reservoir for holding a reagent, pump means for pumping fluid to and from the reservoirs to a pumping reservoir, valve means for restricting fluid flow from the reagent reservoir to the pumping reservoir, first conduit means interconnecting the reagent and sample reservoirs, second conduit means connecting the sample and pumping reservoir at a point just behind a metered aperture provided in an end of the second conduit means, and in a preferred embodiment, third conduit means connecting the first and second reservoirs and valve means for restricting fluid flow from the reagent reservoir to the pumping reservoir through the third conduit means, the end of each of the conduit means being maintained at the same physical level.

Abstract: A potentiometric circuit arrangement 30 is based on a resistive potentiometer tarck 11 with a capacitively coupled `wiper` 14', the resistive track being driven by switched alternating voltages of +/- V at 12 and -/+(X-V) at 13, where X is a reference voltage and V is the output of an integrator 15 to which the voltage sensed by the elecrode 37, and rectified at 36, is applied. A null voltage point establishes itself at the position of the electrode and stabilizes the integrator output at a d.c. voltage proportional to the distance of the `wiper` from the track end 12. Any `wiper` displacement taps a non-null signal which integrated applies new voltages to the track until the null point is re-established at the `wiper` position. The capacitive pick-up enables a potentiometer-type voltage output with less wear of the track, less drag against motion and less electrical noise, and electronic differentiation (27) of the position signal to give a rate signal.

Abstract: Apparatus for measuring breakdown plasma, comprising an irradiating device for irradiating a sample with a focused light beam and for causing breakdown of a ultrafine particle to be measured in the sample at the focused beam region to change the particle into plasma; a pair of electrodes arranged on opposite sides of the focused region of the beam; and a device for measuring an electrical resistance between the electrodes under a condition where the breakdown plasma is produced between the electrodes and for determining a diameter of the particle according to the measured electrical resistance serves for accurate measurement of the diameter of the ultrafine particle in the sample.

Abstract: A non-contacting potentiometer includes a resistor and a movable probe which capacitively couples AC signals applied to the resistor to an output terminal. A closed loop control circuit is coupled to the resistor and the probe to compensate for variations in gap spacing between the probe and resistor.

Abstract: The invention relates to apparatus as disclosed for example in U.S. Pat. Nos. 4,555,662 and 4,600,880 for on-line particle determination in molten metals, wherein a sample of the molten metal is drawn by a vacuum through a calibrated passage in the side-wall of a heat-resistant tube while a current is established through the passage between two electrodes on either side thereof. The passage of non-conducting particles through the orifice produces pulses whose magnitude and rate indicate respectively their size and the number of particles per unit volume. The electrodes and their leads form an interference-receiving antenna so that the wanted test signal, whose signal/noise ratio is inherently low, is subject to interference from neighbouring sources, such as motors, fluorescent lamps and particularly induction furnaces.

Abstract: A rotation-sensing device for providing output signals that correspond to rotary hand movement made about the device by an operator is disclosed. The device comprises a cover member including an outer surface having a generally cylindrical, longitudinally elongate, non-rotatable protusion carried thereon. The protrusion projects outwardly from the outer surface and is provided with an outer periphery thereon. The device further includes a plurality of generally longitudinally elongate, circumferentially spaced, sensing means which are positioned adjacent the outer periphery of the protrusion and are responsive to the rotary hand movement of the operator for providing output signals corresponding to such movement. In addition, the device includes means coupled to the sensing means for leading the signals generated in the sensing means away from the switch device.

Abstract: A method to detect, measure or remove trace amounts of condensible vapors in compressed gases. The concentration of droplets detected, measured or removed may be as low as part per trillion. The compressed gas comprising a carrier gas and condensible vapors is discharged through a critical orifice in order to condense the vapors in the form of homogeneous droplets. The droplets are either detected, or their concentration measured or removed from the expanded carrier gas.

Abstract: A filter and filtering apparatus for measuring the deformability of a blood cell passing through a flow passage formed as a space between a surface of a groove formed in a first substrate and a surface of a second substrate with which the groove is sealed. The filtering apparatus includes electrodes mounted at the inlets and outlets of the flow passages, or optical elements to enable cell deformity measurements.

Abstract: A particle detector for detecting particles of blood components in an electrolyte employs a minute hole through which a fixed quantity of the material is drawn. Electrodes inside and outside the detector pass an electric current through the minute hole. When a particle passes through the hole, it partially blocks the hole, whereby a sharp change is experienced in the amount of current passing through the electrolyte. A syringe fluid path in the detector enters the fluid path for the test fluid at right angles thereto. The inside electrode is disposed in the syringe fluid path near its junction with the fluid path for the test fluid. A colorimeter is placed in series with the flow of the test fluid to measure the concentration of hemoglobin in the test fluid. Automated control of the particle detector is provided by a plurality of cams driving a corresponding plurality of pistons.

Abstract: A position detecting apparatus electrically detects the present position of a moving body reciprocated within a movable region. The apparatus comprises a resistance section continuously disposed by a predetermined length along the reciprocating direction within a detecting region corresponding to the movable region on a substrate composed of an insulator. A plurality of region discriminating patterns are formed by combining a conductive section discontinuously disposed by a predetermined length along the reciprocating direction within the detecting region on the substrate, and an insulating section having no conductor. An electric brush is provided which is connected to the moving body and reciprocated within the detecting region in a state in which the brush slidably contacts the resistance section and the plurality of region discriminating pattern section.

Abstract: A particle counter, of the type utilizing a Coulter(R) type aperature and a suction flow path downstream from the aperture, has a pair of electrodes on both sides of the aperture. A current is provided from the downstream electrode to the upstream electrode and pulses in the resulting voltage across the aperture are monitored to detect the passage of blood cells through the aperture. A grounded electrode is placed in the downstream flow path at a position near the package panel to isolate the cell counter from external electrical noise signals. An isolated high input inpedance amplifier is coupled to provide the monitored voltage to an inserted electrode positioned between the downstream aperture electrode and the grounded panel electrode. Because the inserted electrode and downstream electrode are then at the same voltage, no current flows through that portion of the flow path.

Abstract: A portable meter for measuring the impedance of a resistance welding circuit between first and second points on the apparatus. The meter is powered by conventional alternating current and conducts a test alternating current through the welding apparatus at such an amperage so that the voltage measured between the first and second points is equal to the impedance therebetween.

Abstract: A method and apparatus for controlling flows of fluids, suspensions, gases, aerosols, and for sorting individual particles, flowing in transporter ducts of a flow-through duct system, using for control of the flow and hence, for dispensing and sorting processes, a pressure increase for a short time interval, at the entrances of preselected ducts having a value so that the flow of the fluid or gas to be dispensed comes to a stop at these entrances and is thus constrained together with the particle to flow into ducts where the pressure increase does not take place during the same dispensing/sorting phase. The momentary pressure increase is caused at the ducts either by injection of another fluid or gas through the injection duct, corresponding to these ducts, or by generation of a gas bubble or vapor between electrodes situated at the entrance of these ducts.

Abstract: Apparatus and method for studying particles suspended in an electrically conducting fluid by providing an aperture with a current path therethrough, causing the fluid to flow through the aperture and detecting resistive pulses caused by the passage of suspended particles. Additional information about particle size is generated by designing the aperture such that its cross-section changes progressively along its length, and observing the duration of the resistive pulses, which duration varies with particle size. The method is particularly useful for the study of particles suspended in molten metal.

Abstract: A device for measuring the resistivity of a conductive layer buried beneath an outer layer. The device is capacitively coupled to the buried layer by a driven electrode and a pickup electrode. An adjustable frequency source resonates the two electrodes with an inductor so that an attached meter measures the resistivity of only the buried layer.

Abstract: An apparatus and method for providing a continuous and precise measurement of the number of soot particles emitted in the exhaust gas of a diesel engine. A pair of electrodes is provided in the exhaust gas flow and a voltage is applied across the electrodes so as to develop an electrical current across the electrodes indicative of the conductivity, and therefore the quantity, of the soot particles in the exhaust gas. In accordance with one embodiment of the invention, the electrodes are located in a diluting conduit provided with a pump for providing a constant volume of diluted exhaust gas between the electrodes. In accordance with another embodiment of the invention, the electrodes are located in the exhaust pipe of the diesel engine.

Abstract: Device for measuring the length and number of fibers in an aqueous suspension has a sensor with an upper and lower electrode with an insulating part between the electrodes, a rectifying channel having an inlet and outlet part, the first in close contact with the upper electrode, the second in close contact with the lower electrode, with mutually aligned openings of the sensor and the rectifying means. This arrangement can be applied for such suspensions of fibers or other particles, the electric conductivity of which is different from the conductivity of their carrying medium.

Abstract: Method and apparatus for calibrating a temperature measuring device by operating a heat source at a preset temperature as determined by a temperature sensing resistor and a digitally calculated temperature which varies nonlinearly with the resistance of the resistor, and obtaining the coefficients for the calculation by operating the device at a preset temperature and comparing this temperature with that of a standard temperature measuring device.

Abstract: A particle analyzer which comprises a constricted passage for the passage of fine particles contained in a suspension therethrough for isolation, upstream and downstream passages communicated with the constricted passage and positioned on upstream and downstream sides of the constricted passage with respect to the direction of flow of the suspension, a detector including upstream and downstream electrodes disposed in the upstream and downstream passages, respectively, so as to confront with each other for detecting the fine particles being passed through the constricted passage, and a cleansing passage communicated with either one of the upstream and downstream passages for the supply of a cleansing liquid.

Abstract: A nondestructive apparatus and method for measuring the mass of a moving object, based on the perturbation of the dielectric character of a resonant microwave cavity caused by the object passing through the cavity. An oscillator circuit is formed with a resonant cavity in a positive feedback loop of a microwave power amplifier. The moving object perturbs the resonant characteristics of the cavity causing a shift in the operating frequency of the oscillator proportional to the ratio of the pellet volume to the volume of the cavity. Signals from the cavity oscillation are mixed with a local oscillator. Then the IF frequency from the mixer is measured thereby providing a direct measurement of pellet mass based upon known physical properties and relationships. This apparatus and method is particularly adapted for the measurement of frozen hydrogen pellets.

Abstract: A particle detector in which a pair of pipe elements are coupled together through an aperture and the liquid to be tested is passed through the pipe elements and the aperture with a voltage or current applied to the liquid through the pipe elements acting as electrodes so that the diameter of the pipe elements is reduced because the electrodes are not provided in the pipe elements.

Abstract: A microvertex particle detector for use in a high energy physic collider including a plurality of parallel superconducting thin film strips separated from a superconducting ground plane by an insulating layer to form a plurality of superconducting waveguides. The microvertex particle detector indicates passage of a charged subatomic particle by measuring a voltage pulse measured across a superconducting waveguide caused by the transition of the superconducting thin film strip from a superconducting to a non-superconducting state in response to the passage of a charged particle. A plurality of superconducting thin film strips in two orthogonal planes plus the slow electromagnetic wave propogating in a superconducting transmission line are used to resolve N.sup.2 ambiguity of charged particle events.

Abstract: In a particle counter of the Coulter Counter type the orifice size can be varied by the insertion of an insert into the orifice. This enables particles of a wide ranged of sizes to be effectively detected.

Abstract: A device having a detector element for detecting small particles of metal moving in a stream of particulate matter, such as tobacco filler. The detector element is a coil through which the stream passes. The coil is the inductor of an oscillating circuit and is also part of the negative feedback loop of an operational amplifier. Inductance changes caused by the presence of metal become impedance changes that alter the amplifier gain, changing the amplitude of the AC component of an alternating current output signal. The signal peaks are shifted further, increasing detector amplitude, by coupling the signal through a capacitor to a source of potential so that the DC component of the signal also changes as the change in inductance allows current to flow through the capacitor.

Abstract: An apparatus for the measurement of the red blood cell deformability having a measurement cell formed of two electrically insulated compartments clamped mechanically one against the other, with a commercially available multipore membrane therebetween, each of the parts having inlet and outlet orifices as well as a cavity having one electrode and a lateral hole. One of the cavities contains a buffer, the other being intended to receive a suspension of red blood cells consisting of a dilution of a small volume of red blood cells in a large volume of an isotonic conducting buffer, having a volume concentration allowing substantially the transit of a single red blood cell at a time through the multipore membrane, under the action of a device for applying pressure connected to the cavity containing the suspension. An electronic device translates into transit times the electric impedance variations corresponding to the transit of each single red blood cell through the multipore membrane.

Abstract: A flow cytometer has an aperture in which an inlet chamber and/or an outlet chamber have predetermined geometric relationships with respect to the aperture for decreasing electronic edge effects and increasing the sensitivity of electronic particle volume measurements. In one embodiment, the aperture is triangular and is formed by assembling a plurality of truncated pyramids with their truncated surfaces defining aperture walls. At least one of the elements forming the aperture walls is either part of a lens systems or a transparent cover plate so that simultaneous optical and electronic cell volume measurements can be performed. In one embodiment, a piezoelectric transducer is provided to sonically clear any aperture clogging.

Abstract: An atto amperemeter includes a shop tip (1) correctable to a voltage source (18) providing a known potential (U') via a sample conductor measured, the tip (1) faces a particle detector such as an electron multiplier (4). The count of the free electrons being emitted from the tip (1), multiplied by the electron multiplier (4) and counted by an electronic current (i) passing through the sample conductor (17). Calibration of the arrangement is performed by temporarily connecting the tip (1) to ground and applying a calibration potential (U cal) to a calibrated electrode (3) aligned with the tip (1) and the channel electron multiplier (4).

Abstract: The deformability measurement chamber is subdivided by a foil into two chamber spaces. The foil has a passage opening, the diameter of which is smaller than the diameter, at rest, of a red blood corpuscle. A static pressure gradient exists between the two chamber spaces, so that a flow takes place from one chamber space to the other. In the region of the passage opening there is situated on each side of the foil an electrode, which is connected to an alternating voltage source. In order to achieve a measurement signal which is approximately one order of magnitude greater, at a given alternating voltage frequency, a current-measuring operational amplifier is disposed in the connecton of one electrode to the voltage source.

Abstract: A sensor apparatus for detecting a flow of material along a given path of travel by detecting a change in the dielectric properties of a portion of the path of travel as the material passes therethrough comprises one or more conductive, plate-like electrodes disposed adjacent the path of travel and generally defining a capacitor having the adjacent portion of the path of travel as a dielectric portion, such that the passage of material to be detected changes the dielectric constant, thereby changing the capacitance. A sensor circuit comprises a tuned circuit having the sensor electrode or electrodes being coupled in circuit therewith. The sensing circuit further comprises an oscillator circuit driving the tuned circuit at a predetermined frequency selected near the resonant frequency of the tuned circuit in the absence of material to be detected.

Abstract: An apparatus for determining various characteristics of particles suspended in a liquid, e.g., the deformability or other values of red blood corpuscles. The particles are transported by a method similar to the Coulter method through a measuring channel having sections which are constricted or widened over the length of the measuring channel in, e.g., a foil. The change of certain electrical characteristics of the liquid is measured during passage of each particle, which furnishes a measure of the desired particle characteristics. The volume, as well as the deformability and other characteristics, of a particle can be determined during one passage through one and the same measuring channel. This is accomplished by forming a measuring channel composed of alternate constricted and widened portions in a step-like configuration which are a plurality of cylindrical channel sections, throughout the length of the channel.

Abstract: A debris detector for a particle counter, such as a blood cell counter, of the COULTER (R) type. When a particle, or transient debris, passes through the sensing orifice of the particle detector, a voltage pulse occurs; whereas, when debris lodges in or against the orifice of the particle detector, a d.c. voltage shift occurs. The voltage at the orifice is capacitively coupled to an amplifier and the output of the amplifier is integrated. The capacitor coupling the orifice voltage to the amplifier causes an undershoot voltage at the trailing edge of each particle or transient debris pulse, such that a zero average voltage is applied to and, hence, from the amplifier for each voltage pulse. The integrated voltage is applied to a voltage comparator to provide an output signal therefrom whenever the integrated voltage exceeds a reference voltage. The comparator output signal is provided to a delay circuit having a delay related to the time required for a particle to pass through the COULTER detector orifice.

Abstract: In the known electrical mobility analyzer, a novel means for charged particle detection instead of measuring the low level current carried by the particles is provided. This detection is based on the burst corona occuring from a positive corona electrode applied with a voltage slightly lower than its onset voltage at an instant when a negatively charged particle arrives at the tip of the corona electrode. This detection detects and counts the burst corona pulses produced by the particles negatively precharged.

Abstract: An apparatus and method for the detection and measurement in a molten metal sample of suspended particulates comprises a container having a composite wall including concentric electrically conducting outer and inner walls (10) and (12) and a disc (14) of refractory material having a passage (16) of predetermined size therethrough providing communication between the inside and outside of the container. In use, molten metal is pumped through the passage (16) so as to establish a current path from the inner wall through the passage to the out wall. A current is passed along the current path, and voltage changes are measured as indicating passage of suspended particulates through the passage.

Abstract: An improved electronic particle counter is described in which the electrodes and at least part of the signal processing circuitry are integrally formed on the pane in which the orifice is located. The pane is formed from a wafer of sapphire of the grade customarily used in the manufacture of silicon-on-sapphire integrated circuits. A silicon layer is first formed epitaxially on one side of the wafer and integrated circuits are then formed in the silicon layer using conventional photolithographic techniques. Illustratively, the integrated circuits provide the same particle counting and particle sizing functions that are available in separate packages with state-of-the-art particle counters. An electrode is formed on the same side of the wafer as the integrated circuit by converting some of the epitaxial silicon to a conductive polysilicon or by depositing a metallic layer; and the electrode is connected to the signal input lead of the integrated circuit.

Abstract: The arrangement includes a capacitive probe comprising pairs of sensor electrodes, arranged in a pseudo-random sequence, with which a common transmitting electrode is associated. The transmitting electrode is fed by an electrical voltage source and to the sensor electrodes of each pair an electrode circuit is connected which generates an output signal which corresponds to the difference of the displacement currents induced in the sensor electrodes. The electronic circuit is constructed such that it maintains the sensor electrodes at any time at a virtual ground potential. For this purpose each sensor electrode may be connected to the inverting input of an operational amplifier whose non-inverting input lies at the potential at which the sensor electrodes are to be held with respect to the supply voltage. The sensed signal is used in a correlative measurement of speed or travel time.

Abstract: An apparatus capable of detecting the low-speed electrons (photo-electrons, exo-electrons) emitted from an object with increased accuracy, regardless of the condition of operating environment is disclosed. The apparatus consists in the main of a bell-shaped cathode opened to the atmosphere at the bottom thereof, and an anode supported within the cathode. The anode is supplied with a high voltage enough to induce a gaseous discharge upon the entrance of the low-speed electrons into the cathode, and the number of pulses generated by the anode as a result of this gaseous discharge is counted. Also, a sensor is provided to detect the condition of the operating environment and outputs a signal indicative of the condition. This signal is used to adjust the condition for gaseous discharge across the anode and the cathode to thereby maintain a constant counting rate.