Abstract: A circuit for a combustible gas sensor comprising: a bridge circuit having first and second legs; a first node at a first midpoint in the first leg of the bridge circuit; a second node at a second midpoint in the second leg of the bridge circuit; a first temperature responsive resistive sensor element coupled between the first node and a bottom of the bridge circuit and located in a flow of combustible gas; a second temperature responsive resistive sensor element coupled between the bottom of the bridge and ground and located in the flow of combustible gas; and a voltage control circuit coupled to the first and second nodes and to the top of the bridge circuit for maintaining closed loop control of first and second node voltages at the first and second nodes by varying a bridge voltage at the top of the bridge circuit wherein one of the first and second sensor elements includes a catalyst for stimulating reactions of reactive constituents in the flow of combustible gas.

Abstract: Apparatus for the installation of sensors (37) in channels (31), which apparatus comprises a first channel (31) containing at least one sensor location arrangement (35), the first channel (31) and the sensor location arrangement (35) being such that at least one sensor (37) is able to be pumped through the first channel (31) to the sensor location arrangement (35), the sensor location arrangement (35) being provided with at least one turn (3) such that the physical disposition of the sensor (37) after it has been pumped to the sensor location arrangement (35) is not linear, and the turn (3) being such that it comprises a loop of hydraulic conduit.

Abstract: The apparatus measures the liquid volume of a liquid or liquids held in one or more containers. This apparatus has no moving parts and includes an open-ended dynamic pressure tube standing in each container with its open tube end at the lowest point of the container on the bottom surface of it and a pressure measurement converter closing the other tube end so as to form an air column between the pressure measurement converter and a liquid level in it. The apparatus also includes an electronic analyzing device (3,4) including an electronic circuit (3) connected electrically to the pressure measurement converter and producing an electronic signal characteristic of a liquid volume in the container and a digital meter for displaying a volume reading.

Abstract: A method for the qualitative determination of the visible levels of glycol and/or formaldehyde at significant concentrations greater than 10 ppm (10 ppm-10,000 ppm range) in a water sample, in which the sample is treated first with periodic acid, then with iodide-thiosulfate and finally with acetyl acetone to yield a yellow color without the benefit of heat. This yellow color is visible to the naked eye and proportional to the amount of contaminants ethylene glycol, propylene glycol and/or formaldehyde present in the original water sample.

Abstract: This invention relates to a leak tester for testing the tightness of a test object such as a fuel feed apparatus for an internal combustion engine, and specifically to a leak tester for testing the air tightness of a fuel feed apparatus provided with a first opening and a second opening and having a space portion between the first and second openings.

Abstract: Condensed moisture in devices and/or pipe conduits for anti-corrosion applications in chemical engineering is measured at least one point in the devices and/or pipe conduits by measuring an electrochemical potential difference across two different elements, such as iron and copper, which are arranged one beside the other spaced from 0.001 to 1 mm from each other by an electrically insulating material so as to be electrically insulated from each other. An apparatus for making these measurements is also described.

Abstract: A planar separation column device for use in gas or liquid phase sample analysis. The planar separation column device includes complementary microstructures formed in a planar foldable substrate. The complementary microstructures may be superimposed in a controlled manner by folding the foldable substrate. The resulting integrated assembly may be bonded and subsequently operated in an associated sample analysis system. The planar separation column device includes etched features useful for integrated sample analysis, such as for integration of analyte inlet, detection, and fluid communication devices.

Abstract: A gas sensor, suitable for use under non-steady state conditions, has a gas-sensitive resistor with pairs of electrodes which either have different spacings between the electrodes of a pair, or comprise a pair at the active surface and further pairs buried in the resistor at different distances from the active surface. The sensor can be used in place of a sensor array, and is coupled to a processor for processing the resistance signals to detect and/or measure at least one target gas. The sensor is self-diagnostic, and factors such as relative humidity and ambient oxygen, that can otherwise affect the readings, can be compensated for without the aid of additional sensors for that purpose.

Abstract: A method for quantitatively measuring the characteristic physical parameters of a porous medium, such as an aquifer that is initially recharged at a recharge rate and subsequently discharged at a discharge rate by a pumped fluid utilizing a single well into which a tracer is injected during recharge, and at which the tracer is subsequently detected during discharge. A measurement of the elapsed time, together with a formula based on a convective physical model relating the characteristic parameters to the time measurements is provided.

Abstract: A non-contact pneumatic-electric dimensional measurement system comprises a stable base on which a semiconductor wafer or workpiece to be measured is placed. A measurement head is held aloft over the wafer or workpiece and base by a rigid support bracket attached to the base. The tip of an air nozzle in the measurement head is directed at the wafer or workpiece and automatically extended to near contact. The nozzle is servo-positioned by an air sensor and motor combination that maintains an air gap between the tip and wafer of about 150 microns with an overall precision of about 3-4 microns. A Heidenhaim linear displacement gauge is attached to the air nozzle and is used to determine the nozzle position to within 0.5 micron. The dimension of the wafer or workpiece is determined to within 0.5 micron by combining the linear displacement gauge reading with an estimate of the air gap derived from a reading of the air nozzle backpressure that has an accuracy of about 0.1 micron.

Abstract: An isotope ratio monitoring gas chromatograph-mass spectrometer (irm-GC/MS) unit for generating a chromatogram having improved resolution for peaks representative of individual carbon dioxide isotopes measured when a complex GC amenable organic sample (e.g. petroleum hydrocarbons) is combusted in the presence of a metal catalyst. The present irm-GC/MS unit is similar to known irm-GC/MS units of this type except it uses a capillary combustion tube in the furnace which is connected to the capillary column and has approximately the same inside diameter as that of the capillary column (e.g. 0.25 mm I.D.) whereby any "dead volume" attributable to the combustion tube is substantially eliminated.

Abstract: A sensor for detecting moisture on a non-conductive support, in particular a windshield of a motor vehicle, has one or more metallic, electrically conductive layers which are arranged in a given pattern on the outer surface of the support. The metallic, electrically conductive layer is produced from a metallic resinate which is applied to the support and then burned-in by the action of heat. Also deseribed is a method for constructing such a moisture sensor whit applies a glass layer in the form of a glass frit paste to be sintered upon the metallic electrically conductive layer, where the burning-in of the metallic resinate and the sintering of the glass frit paste are effected in single step.

Abstract: An analytical system for a trace element, which includes a pressure pump for continuously feeding a carrier solution, a first sample introduction unit for introducing a sample and a reagent using sample loops and switching valves, a first flow passage including a pre-treatment unit for pre-treating the sample by heating, and a second flow passage separated from in pressure from the first flow passage, wherein the sample pre-treated in the first flow passage is sampled into the second flow passage through a second sample introduction unit, and the sample thus sampled in the second flow passage is allowed to coloredly react with a coloring agent and measured in absorbance.

Abstract: An in-line gas monitor capable of accurate gas composition analysis in a continuous real time manner even under strong applied vacuum conditions operates by mixing an air sample with helium forming a sample gas in two complementary sample loops embedded in a manifold which includes two pairs of 3-way solenoid valves. The sample gas is then analyzed in an ion trap mass spectrometer on a continuous basis. Two valve drivers actuate the two pairs of 3-way valves in a reciprocating fashion, so that there is always flow through the in-line gas monitor via one or the other of the sample loops. The duty cycle for the two pairs of 3-way valves is varied by tuning the two valve drivers to a duty cycle typically between 0.2 to 0.7 seconds.

Abstract: A rain sensor for the windshield of a vehicle has one or more electrically conductive layers which are arranged in a given pattern upon the outer surface of such windshield, and is constructed as a laminate of conductive and resistive layers formed by process steps of printing and sintering for construction of electrodes of the sensor. A conductive layer is formed of a mixture of electrically conductive particles and a glass frit which melts at a lower temperature than a melting temperature of the material of the window which serves as a support for the sensor. The conductive paste is applied with a heating action step, in the configuration of an electrode structure, by sintering to the window.

Abstract: A rain sensor system automatically controls windshield wiper action such as the length of time between windshield wiper strokes and/or wiper motor speed and is preferably integrated with a vehicle antenna. The rain sensor system comprises first and second electrical conductors spaced uniformly from one another and an electrical insulator interposed therebetween. A dual network voltage divider circuit couples the first conductor to an applied reference DC voltage level, and the second conductor is coupled to ground potential via a similar network. Airborne raindrops and moisture temporarily adhere to the exposed surfaces of the insulator to electrically couple the exposed surfaces of the first and second conductive surfaces to lower the electrical resistance therebetween. The magnitude of the applied voltage changes in relation to the intensity of rainfall or amount of raindrops adhering to the conductors to affect the rate of windshield wiper action.

Abstract: A photo-acoustic leak detection system for detecting a gas leaking from a component (30), includes at least one laser beam (20), incident on the component (30) and having a wavelength which is absorbed by the gas, the gas emitting a photo-acoustic signal (36) when the gas absorbs light from the beam (20), the beam (20) being pulsed at a pulse frequency, the pulse frequency being related to a detection frequency of the photo-acoustic signal and being a frequency at which the magnitude of background acoustic noise at the detection frequency is at a predetermined low level, at least one acoustic sensor (40), which receives the photo-acoustic signal (36) and provides a sensor signal on the line (42) indicative thereof to a filter (44) and a synchronous detector (18), which provide a filtered signal on a line (50) to a signal processor (52). The processor (52) provides an output signal on a line (54) indicative of the leak in the component.

Abstract: A device for detecting the air-fuel ratio in an engine comprises a limiting current type air-fuel ratio sensor 20, an air-fuel ratio sensor circuit 30, a detecting means 40, a determining means 50 and a correcting means 60. The air-fuel ratio sensor 20, which is arranged in an exhaust system of the engine 10, generates an electric current when a voltage is applied thereto and is made from solid electrolyte. The sensor circuit 30 applies a voltage to the sensor 20 within a range of the limiting current, detects a concurrent limiting current and outputs a signal proportional to the magnitude of the detected current. The detecting means 40 detects a change in the voltage output from the sensor circuit 30 when the voltage applied to the sensor 20 is changed from a voltage within the range of the limiting current to a voltage outside the range of the limiting current a predetermined time after the engine 10 is started.

Abstract: Air pollution gas sensor which efficiently detects smell from smoking, ordinary stinks such as TMA and CH3SH, smell of Kimchi, acetaldehyde, and etc. and also a method for fabricating the same is revealed and described including a substrate, a heater formed on said substrate, electrodes each formed on said substrate insulated from the heater, and a sensing layer formed of SnO.sub.2, including WO.sub.3 on said substrate including said electrodes, with the method for fabricating the gas sensor including the steps of forming the heater on the substrate, forming the electrodes on the substrate insulated from the heater, and forming a sensing layer of SnO.sub.2 including WO.sub.3 on the substrate including the electrodes.

Abstract: The invention provides a preparative liquid chromatography apparatus wherein flow rate control can be effected in a wider range and with a higher degree of accuracy than where a pump is used while preventing production of air bubbles in liquid and the mixture ratio of chemicals can be controlled in a wide range and with a high degree of accuracy.