Abstract: A method of significantly improving the brightness and shade properties of a high quality PCC product. The method includes providing a calcium containing feed source that contains discoloring impurities. The calcium containing feed source is formed into an aqueous slurry of calcium carbonate. Thereafter, the slurry is fine screened through a 325 mesh screen in order to yield a slurry of filler grade calcium carbonate. The filler grade calcium carbonate slurry is wet milled in order to liberate the discoloring impurities and reduce the median particle size of the calcium carbonate to less than 2 microns. The discoloring impurities are then magnetically separated from the milled calcium carbonate slurry by subjecting the slurry to a high intensity magnetic filed. After the magnetic separation step, the purified slurry may be de-watered to yield a dry powder; or alternatively, the slurry may be retained in aqueous form.

Abstract: Oriented strand board is post-fabrication treated with a polymeric coating which includes isocyanate constituents to produce a construction material which is smooth, has high gloss, and which is resistant to water, vapor, and chemical penetration. The isocyanate constituents are most preferably MDI or PMDI, and may be present in a coating composition alone or in combination with other binder materials such as PEEG or other polyols. Prior to application of the coating composition, the surface of the oriented strand board is pretreated using heat and pressure to compress and densify wood at the surface, and to smooth out minor surface irregularities. The coating composition is then applied to the wood surface, and is cured to form a polymeric coating which bonds to the wood material.

Abstract: A method of making an aluminum hydroxide and melamine blend. The method comprises jet milling a quantity of coarse particle size melamine until a line particle size melamine is obtain which has a median particle size of from about 0.5 .mu.m to about 45 .mu.m, passing the fine particle size melamine through an air classifier and a cyclone separator, and admixing the fine particle size melamine with a quantity of surface treated aluminum hydroxide in a high speed mixer.

Abstract: A fire retardant coating composition which comprises expandable graphite particles, a solid absorbent material, a polymeric binder, a carbonific material, a blowing agent, a solvent and a rheology modifier. The expandable graphite particles include from about 20 to about 95% by weight of the combined amount of expandable graphite particles and solid absorbent material. The polymeric binder comprises from about 10 to about 50% by weight of the combined amount of the polymeric binder, the expandable graphite particles, and the solid absorbent material. The carbonific material comprises from about 0 to about 70% by weight of the combined amount of the carbonific material and the polymeric binder. Similarly, the blowing agent comprises from about 0 to about 70% by weight of the combined amount of the blowing agent and the polymeric material. The solvent comprises from about 25 to about 50% by weight of the total composition. The rheology modifier is present in an amount of from 0.

Abstract: A dentifrice containing a dye absorbing silica which imparts a speckled appearance in toothpaste or gel formulations. The dye absorbing silica comprises silica granules which have a linseed oil absorption of at least about 150 cc/100 g, an average particle size of about 400 .mu.m to about 600 .mu.m, an attrition value of less than 30%, and a pH of about 6 to about 8.

Abstract: A fire retardant coating composition for lignocellulosic materials which comprises expandable graphite particles, a absorbent material, a polymeric binder, a carbonific material, a blowing agent, and a wetting agent. The expandable graphite particles include from about 20 to about 95% by weight of the combined amount of the expandable graphite particles and the absorbent material. The polymeric binder comprises from about 5 to about 50% by weight of the combined amount of the polymeric binder, the expandable graphite particles, and the solid absorbent material.

Abstract: A flame retardant polyolefin composition comprises at least about 25% by weight magnesium hydroxide and, preferably, at least about 30%, at least about 5% by weight melamine and, preferably, at least about 20%, and at least about 0.5% by weight novolac and, preferably at least about 1%.

Abstract: An active array antenna for use, for example, in a radar system, includes elemental antennas, each with a T/R module, distributed over a circular aperture. For lowest cost, the aperture is thinned. The T/R modules are operated at maximum output, to achieve maximum DC-to-RF efficiency, and for simplicity. A phase controller controls the phase shift which is imparted by each module to its signal, to form a main beam and its associated sidelobes. A perturbation phase generator portion of a phase controller adds a perturbation phase shift selected, in conjunction with a particular thinning distribution, to form a relatively wide null in the sidelobe structure, in which signal transduction is reduced. In a radar context, this null may be placed on a source of ground clutter or a jammer.

Abstract: A method for producing a stabilized magnesium hydroxide slurry comprising physically deflocculating the magnesium hydroxide solids in a starting slurry to produce a stabilized magnesium hydroxide slurry. Depending on the chloride level of the starting slurry, a cationic polymer may be added to the slurry. Optionally a thickening agent may be added to the deflocculated slurry. Also disclosed is a stabilized magnesium hydroxide slurry produced by the method which may be transported and stored without substantial agglomeration of the magnesium hydroxide solids.

Abstract: A stabilized, pressure-hydrated magnesium hydroxide slurry and a process for its production from burnt magnesite are described. According to an embodiment of the invention, a mixture comprising burnt natural magnesite and water is pressure hydrated to provide a pressure hydrated slurry. The pressure hydrated slurry is then deagglomerated. If desired, chloride ions and cationic polymer can be added to further stabilize the slurry.

Abstract: A sparger system for mixing a solid/liquid suspension in a cylindrical container comprises a sparger pipe which extends substantially parallel to the longitudinal axis of the container. The sparger pipe is separated from an inner wall of the container by a first distance and a first end portion of the sparger pipe extends through a side wall of the container. A first flange member is releasably coupled to the first end portion of the sparger pipe so that, when the first flange member is coupled to the first end portion of the sparger pipe, the first end of the sparger pipe is sealed. The flange member may be removed from the first end portion of the sparger so that pressurized liquid may be introduced directly into the sparger pipe to clean the sparger pipe and the container. A fluid passage is coupled to the sparger pipe and extends to an opening which is above a maximum level of liquid to be stored in the container.

Abstract: A short horn antenna (10) adapted for array use includes a rectangular waveguide with broad upper (12) and lower (14) walls and narrow side walls (16, 18), defining a radiating aperture (20) and a feed end closed off by a shorting plate (22). A stepped upper ridge (26) has a slot (50) adjacent the shorting plate, and a shorter stepped lower ridge (46) has a corresponding slot. An unbalanced transmission line (75) extends through the shorting wall, and the smaller conductor (76) extends into the waveguide as an electric probe (60). The probe includes a first portion (64), extending parallel to the waveguide axis (8) and into the slot in the upper ridge. The probe (60) also includes a second portion (66) extending at an angle (90.degree.) relative to the first portion (64) of the probe (60).

Abstract: A beamformer for a main antenna and a plurality of auxiliary antennas converts the main and each of the auxiliary signals to digital form. Each of the real and auxiliary digital signals is applied to a pair of real multipliers, in which multiplication by beamforming weights is performed, to produce one weighted real main signal, one weighted imaginary main signal, and a plurality of weighted real and weighted imaginary auxiliary signals. The weighted real main and auxiliary signals are summed together by a cascade of summers, and the weighted imaginary main and auxiliary signals are likewise summed together by another summed cascade. A digital product detector is connected to the output of each summer cascade. The first digital product detector produces in-phase and quadrature components of real detected signals, and the second digital product detector produces in-phase and quadrature components of imaginary detected signals.

Abstract: A multipurpose system provides radar surveillance for air traffic control purposes. The system includes four separate active phased-array antennas, each with .+-.45.degree. coverage in azimuth, from 0.degree. to 60.degree. in elevation. Each antenna element of each phased-array antenna is coupled by a low-loss path to the solid-state amplifier associated with a transmit-receive (TR) module. Each antenna produces a sequenc of pencil beams, which requires less transmitted power from the TR modules than a fan beam, but requires more time beacuse the pencil beam must be sequenced to cover the same volume as the fan beam. In order to scan the volume in a short time, the PRF is responsive to the elevation angle of the beam, so higher elevation angles use a higher PRF. Low elevation angle beams receive long transmitter pulses for high power, and pulse compression is used to restore range resolution, but the long pulse results in a large minimum range within which targets cannot be detected.

Abstract: A radar generates first and second mutually complementary binary code sequences. The autocorrelation functions of the first and second pulse sequences are selected so that, in the sum of their autocorrelation functions, the main lobes add, and the sidelobes are of equal amplitude and opposite polarity, and therefore cancel. The radar sequentially transmits dispersed pulses in which the chips are phase modulated with the two codes. The received pulses are applied uncompressed to the input of a Doppler filter bank, which filters them into various Doppler channels, each representative of a particular radial velocity of the target. Within each channel, the received signals modulated by the first code are matched-filtered by a filter matched to the first code, to produce a first time-compressed pulse, and those modulated by the second code are matched-filtered by a filter matched to the second code, to produce a second time compressed pulse.

Abstract: A multipurpose system provides radar surveillance for air traffic control purposes. The system includes four separate active phased-array antennas, each with .+-.45.degree. coverage in azimuth, from 0.degree. to 60.degree. in elevation. Each antenna element of each phased-array antenna is coupled by a low-loss path to the solid-state amplifier associated with a transmit-receive (TR) module. Each antenna produces a sequence of pencil beams, which requires less transmitted power from the TR modules than a fan beam, but requires more time because the pencil beam must be sequenced to cover the same volume as the fan beam. In order to scan the volume in a short time, the PRF is responsive to the elevation angle of the beam, so higher elevation angles use a higher PRF. Low elevation angle beams receive long transmitter pulses for high power, and pulse compression is used to restored range resolution, but the long pulse results in a large minimum range within which targets cannot be detected.

Abstract: A probe for use in a coax-to-waveguide transition is uniformly coated with a dielectric material by inserting the probe through an elastic membrane covering a container of uncured RTV elastomer to thereby dip the probe. The membrane wipes excess elastomer from the probe during withdrawal, and seals the RTV from ambient air to thereby prevent its premature curing in the container. If moved sideways before withdrawal, the coating thickness can be made to favor one side over another. A magnetic block is fitted into a waveguide. A slot in the magnetic block is also filled with uncured RTV elastomer. The probe is inserted into the slot, embedding it in the uncured RTV. Upon curing, the probe is protected from high voltage arcing to the waveguide. A cured RTV elastomer washer is preassembled to the probe before dipping, to precisely fill the void between the connector base and the magnetic block with a like material.

Abstract: A transmitter driver of this invention is applied to a programmable remote control transmitter for receiving remote control codes for remote-controlling various electric devices in the learning mode and for remote-controlling the electric devices according to the received remote control codes in the remote control mode. The transmitter driver has an output transistor for driving a transmitter constituting a part of a load upon reception of electrical pulses representing the remote control codes, a resistor device arranged between the output side of the output transistor and a given reference potential, and a control transistor device, output electrodes of which are arranged between one end of the resistor device at the side of the output transistor and the reference potential. An input terminal of the control transistor device receives a control signal corresponding to an output signal format of remote control codes necessary for controlling an electric device selected by a user.