Abstract: Protective coatings are applied to substrate metals by coating the metal surface, e.g. by dipping the substrate metal in a molten alloy of the coating metals, and then exposing the coating at an elevated temperature to an atmosphere containing a reactive gaseous species which forms a nitride, a carbide, a boride or a silicide. The coating material is a mixture of the metals M.sub.1 and M.sub.2, M.sub.1 being zirconium and/or titanium, which forms a stable nitride, carbide, boride or silicide under the prevailing conditions. The metal M.sub.2 does not form a stale nitride, carbide, boride or silicide. M.sub.2 serves to bond the carbide, etc. of M.sub.1 to the substrate metal. Mixtures of M.sub.1 and/or M.sub.2 metals may be employed. This method is much easier to carry out than prior methods and forms superior coatings. Eutectic alloys of M.sub.1 and M.sub.2 which melt substantially lower than the melting point of the substrate metal are preferred.

Abstract: Protective coatings are applied to substrate metals by coating the metal surface, e.g. by dipping the substrate metal in a molten alloy of the coating metals, and then exposing the coating at an elevated temperature to an atmosphere containing a reactive gaseous species which forms an oxide, a nitride, a carbide, a boride or a silicide. The coating material is a mixture of the metals M.sub.1 and M.sub.2, M.sub.1 being zirconium and/or titanium, which forms a stable oxide, nitride, carbide, boride or silicide under the prevailing conditions. The metal M.sub.2 does not form a stable oxide, nitride, carbide, boride or silicide. M.sub.2 serves to bond the oxide, etc. of M.sub.1 to the substrate metal. Mixtures of M.sub.1 and/or M.sub.2 metals may be employed. This method is much easier to carry out than prior methods and forms superior coatings. Eutectic alloys of M.sub.1 and M.sub.2 which melt substantially lower than the melting point of the substrate metal are preferred.

Abstract: A method of protecting ferrous metal structures from oxidative attack in an aqueous, corrosive, oxidative environment by applying a thin, impervious coating of an oxide of titanium, zirconium, tantalum or niobium (or a mixture of two or more such oxides). The coating is applied as an alloy (preformed or form in situ) of the respective metal and a more noble metal such as nickel, cobalt, copper or iron and the alloy is preferably thermally oxidized under conditions to oxidize the titanium, zirconium and/or niobium without oxidizing the more noble metal, which serves to bind the oxide coating to the substrate. Alternatively the alloy may be applied, and then oxidized by the conditions of use.

Abstract: Protective coatings are applied to substrate metals by coating the metal surface, e.g. by dipping the substrate metal in a molten alloy of the coating metals, and then exposing the coating at an elevated temperature to an atmosphere containing a reactive gaseous species which forms a nitride, a carbide, a boride or a silicide. The coating material is a mixture of the metals M.sub.1 and M.sub.2, M.sub.1 being zirconium and/or titanium, which forms a stable nitride, carbide, boride or silicide under the prevailing conditions. The metal M.sub.2 does not form a stable nitride, carbide, boride or silicide. M.sub.2 serves to bond the carbide, etc. of M.sub.1 to the substrate metal. Mixtures of M.sub.1 and/or M.sub.2 metals may be employed. This method is much easier to carry out than prior methods and forms superior coatings. Eutectic alloys of M.sub.1 and M.sub.2 which melt substantially lower than the melting point of the substrate metal are preferred.

Abstract: Biodegradible polymers are provided which may contain a biologically active substance, e.g. a drug such as insulin, which is released over a period of time as the polymer erodes when in contact with a body fluid. The polymer contains an amine functionality whereby it erodes faster at low acid pH's than at higher acid pH's. As an example, the polymer may contain insulin and may contain or may have an encapsulating hydrogel containing glucose oxidase. As the blood sugar level of a diabetic person rises, e.g., after a meal, glucose diffuses into the polymer or hydrogel and is converted to gluconic acid which lowers the pH, and accelerates erosion and the release of insulin.

Abstract: Biodegradible polymers are provided which may contain a biologically active substance, e.g. a drug such as insulin, which is released over a period of time as the polymer erodes when in contact with a body fluid. The polymer contains an amine functionality whereby it erodes faster at low acid pH's than at higher acid pH's. As an example, the polymer may contain insulin and may contain or may have an encapsulating hydrogel containing glucose oxidase. As the blood sugar level of a diabetic person rises, e.g., afte a meal, glucose diffuses into the polymer or hydrogel and is converted to gluconic acid which lowers the pH, and accelerates erosion and the release of insulin.

Abstract: Process for applying a protective coating to a metal substrate which provides a thermal barrier and a barrier against oxidation of the substrate. The coating material is a mixture of (1) zirconium and/or hafnium and (2) a metal such as nickel which does not form a stable oxide at a high temperature in an atmosphere having a very low concentration of oxygen. The coating is subjected to such conditions to produce an outer oxide layer of metal zirconium and/or hafnium and an inner metal layer of the second metal alloyed with one or more components of the substrate. The oxide layer provides thermal and oxidation protection and the inner layer bonds the coating to the substrate.

Abstract: Method of producing polysilazanes from precursors having Si-H, Si-N or Si-Si bonds in the presence of a catalyst effective to activate such bonds. The catalyst may be a metal complex, e.g. a carbonyl cluster, which is soluble in an organic solvent and is homogeneous or it may be a heterogeneous catalyst. Higher polymers, and/or less crosslinking and oligomer formation, and/or greater control over the product and/or faster reactions and/or greater yields result. The polymers are soluble in common organic solvents and/or are solids which can be shaped. The products can be pyrolyzed to silicon nitride or used without pyrolysis.

Abstract: A system for gathering topographic data for use in computer generation of topographic maps of various forms. This system includes equipment mounted in an aircraft which can be flown over a terrain area which is to be surveyed. The equipment comprises a low frequency radar which is capable of penetrating foliage in the survey area for generating a signal representative of the distance from the aircraft to the terrain surface, a precision altimeter that produces a signal representative of the altitude of the aircraft with respect to a reference plane such as sea level, temperature and humidity sensors for producing signals representative of those quantities, a clock for producing a signal representative of a standard time, and a digital recorder for recording the previously named signals which are produced during over flight of a survey area.

Abstract: A pair of image fields which are views of an object from two slightly different angles at near enough the same time to constitute a stereo image field pair is produced by providing a pair of similar coaxial counterrotating refracting prisms between the object viewed and the image field and alternately transmitting an image field through the prisms on opposite sides of the plane through or parallel to the central axis of the two prisms.

Abstract: A variable delay memory system (200) has an addressable memory means (66-1) having a data input port and a data output port. A counter (206) is connected to supply a write address on bus (212) for storage of data supplied to the data input port on bus (64-1). A subtracter means (214) is connected to receive the write address as one input on bus (210) and a second input proportional to a desired delay time on bus (72-1). The subtracter means (214) is connected to supply its output as a read address on bus (216) for data stored in the memory means (66-1) to be supplied at the data output port on bus (76-1).

Abstract: Energetic copolymers having repeating mer units derived from different monomers, one or both of which have pendant energetic groups such as azido, nitro or nitrato groups. Copolymers have improved formulating characteristics compared to homopolymers of the energetic monomers; e.g., they are less crystalline or less viscous. Preferably the monomers are cyclic oxides having three to six atoms in the ring. The energetic monomers are preferably azido, nitro or nitrato derivatives of oxetane or THF. Copolymerization is preferably carried out by cationic polymerization using an adduct of the preinitiator precursor (e.g., 1,4-butane diol) and a catalyst suitable for cationic polymerization (e.g., boron trifluoride etherate) which is employed in stoichiometric proportion to the monomers and a low molecular weight, low polydispersity copolymer results. Certain novel monomers also are provided.

Abstract: Process for applying a protective coating to a metal substrate which provides a thermal barrier and a barrier against oxidation of the substrate. The coating material is a mixture of two metals M.sub.1 and M.sub.2, e.g., cerium (M.sub.1) and cobalt (M.sub.2), one of which when exposed to an atmosphere containing a low partial pressure of oxygen and at a high temperature forms a stable oxide, the other of which does not form a stable oxide under such conditions. A coating consisting of such a metal alloy or mixture is subjected to such conditions to produce an outer oxide layer of metal M.sub.1 and an inner metal layer of M.sub.2 alloyed with one or more components of the substrate. The oxide layer provides thermal and oxidation protection and the inner layer bonds the coating to the substrate.

Abstract: An ultrasonic imaging system (50) has an array (52) of transducer elements (54-1 through 54-21) for receiving ultrasonic signals reflected from within an inhomogeneous object (16) being examined. The system (50) has a means (80, 84, 88, 94) connected to generate an image in response to the ultrasonic signals. A cross-correlator (70) is connected to compare the signals received by the transducer elements (54-1 through 54-21). An output addressing circuit (130) is connected to inhibit or otherwise modify gain of selected ones of the signals based on the comparison to reduce multipath ultrasonic wave interference, refraction or obstruction image distortion or degradation. A preferred ultrasonic imaging array (52) for this purpose and for time delay image distortion correction has a plurality of segmented, annular transducer elements (54-2 through 54-21). The elements (54-2 through 54-21) are formed as sectors of circles with substantially equal arc lengths.

Abstract: This ultrasonic imaging apparatus has an array (44, 52 or 100) of transducer elements (44, 50 or 104) for transmitting ultrasonic signals having a first predetermined center frequency (fc1) into an object (12) to be analyzed through use of the transmitted signals reflected from within the object. A means (150, 116-1 through 116-X and 120-1 through 120-X) is connected to transmit the ultrasonic signals from the array (44, 52 or 104) in a stepped array mode. A means (150, 116-1 through 116-X and 120-1 through 120-X) is connected to transmit the ultrasonic signals from the array (44, 52 or 104) in an angle scanning mode. There is a means (150, 128-1 through 128-X) for focusing the transmitted signals at a desired depth within the object (12). The reflected signals sensed by the apparatus have a second center frequency (fc2) less than the first center frequency (fc1) as a result of signal attenuation by the object (12).

Abstract: An ultrasonic imaging apparatus has an array (10 or 100) of transducer elements (14 or 104) for transmitting ultrasonic signals into an object (12) to be analyzed through use of the transmitted signals reflected from the object and sensed by the apparatus. The transmitted signals have a first predetermined center frequency. The reflected signals sensed by the apparatus have a second center frequency less than the first center frequency as a result of signal attenuation by the object. A means (70, 62 or 150, 152-1 through 152-X) is connected to select a number of transducers (14 or 104) in the array (10 or 100) for transmitting and/or receiving the ultrasonic signals based on the second center frequency. Adjusting the number of transmitting and/or receiving transducers (14 or 104) with changes in frequency produced by signal attenuation gives improved image resolution under a wider variety of use conditions than with prior art ultrasonic imaging apparatus.

Abstract: A stabilized visual system for directing a beam of energy, such as a laser beam, to a specific selected location in an eye and maintaining the beam in the selected location regardless of eye movements. The system employs a fundus illumination and monitoring device which illuminates the fundus of an eye and allows an observer simultaneously to observe the illuminated fundus, an eye tracker which continuously measures the position and changes in position of the illuminated eye and produces electrical signals in response to the changes in position of the eye, and an input beam stabilizer which directs a beam of electromagnetic energy to a selected location in the eye. Servomotor driven optical elements (e.g., a pair of mirrors) are positioned in the path of the beam of electromagnetic energy and are connected to receive and be driven by the electrical signals produced by the eye tracker so that the electromagnetic beam is maintained at the specific selected location in the eye even though the eye moves.

Abstract: Intra-arterial blood pressure is noninvasively measured and monitored by an electromechanical force sensor which is made up of an array of individual force sensing elements, each of which has at least one dimension smaller than the lumen of the underlying artery wherein blood pressure is to be measured, and the individual force sensitive element which generates the waveform of maximum amplitude is used to monitor blood pressure.

Abstract: An apparatus for controlling positioning of an implement relative to a workpiece, such as a welding head with respect to members to be welded, projects light patterns including an array of light elements each having a known shape and spacing relative to one another on the workpiece. The light elements as reflected from the workpiece are detected and output signals produced in response to the detected light elements. The output signals are classified into groups based on at least one common characteristic resulting from workpiece geometry. The workpiece geometry is defined from at least one relationship between different ones of the groups of the first output signals. Second output signals are produced indicative of the so-determined workpiece geometry. The second output signals are used to control positioning of the implement relative to the workpiece. This apparatus and process allows workpiece geometry to be defined and the implement to be positioned relative to the workpiece on a real-time basis.

Abstract: A three dimensional eye tracker, for measuring as a function of time the point in three dimensional space on which the eye is fixed, includes a portion which functions as a two dimensional double Purkinje eye tracker for measuring movement of the eye in rotation and translation, an automatic optometer portion for measuring the refractive power of the eye, and a common optical path simultaneously to provide corrections for both portions of the instrument. The two dimensional eye tracker portion incorporates a means for directing a beam into the eye, thereby forming first and fourth Purkinje images, and measuring means responsive to the first and fourth Purkinje images to generate output signals indicative of eye rotation and translation. The automatic optometer portion alternately directs a light beam through different areas of the eye lens and includes a mechanism for altering the directed light beam until the image on the retina does not move.