Abstract: A system that provides effective and efficient introduction of water droplets into an air flow. The water droplets are sufficiently small so as to evaporate primarily before leaving the mixing enclosure where the droplets are injected by spray nozzles. Large droplets are kept to a minimum, thus reducing condensation and water accumulation to a very small amount. An amount of water usage is significantly less than that of a conventional evaporative humidifier of the same capacity. The present system may be placed in an enclosure that can readily replace other conventional evaporative humidifiers in enclosures. The present enclosure and system may be installed in lieu of a conventional enclosure and evaporative humidifier with minimal effort. The present enclosure has features that facilitate droplet to air mixing, viewing, humidification, and testing. In permissible situations, the present system may replace a conventional system but retain the conventional enclosure.

Abstract: A system that provides effective and efficient introduction of water droplets into an air flow. The water droplets are sufficiently small so as to evaporate primarily before leaving the mixing enclosure where the droplets are injected by spray nozzles. Large droplets are kept to a minimum, thus reducing condensation and water accumulation to a very small amount. An amount of water usage is significantly less than that of a conventional evaporative humidifier of the same capacity. The present system may be placed in an enclosure that can readily replace other conventional evaporative humidifiers in enclosures. The present enclosure and system may be installed in lieu of a conventional enclosure and evaporative humidifier with minimal effort. The present enclosure has features that facilitate droplet to air mixing, viewing, humidification, and testing. In permissible situations, the present system may replace a conventional system but retain the conventional enclosure.

Abstract: A system that provides effective and efficient introduction of water droplets into an air flow. The water droplets are sufficiently small so as to evaporate primarily before leaving the mixing enclosure where the droplets are injected by spray nozzles. Large droplets are kept to a minimum, thus reducing condensation and water accumulation to a very small amount. An amount of water usage is significantly less than that of a conventional evaporative humidifier of the same capacity. The present system may be placed in an enclosure that can readily replace other conventional evaporative humidifiers in enclosures. The present enclosure and system may be installed in lieu of a conventional enclosure and evaporative humidifier with minimal effort. The present enclosure has features that facilitate droplet to air mixing, viewing, humidification, and testing. In permissible situations, the present system may replace a conventional system but retain the conventional enclosure.

Abstract: A photoacoustic detector wherein a detector response transfer function can be measured at various times under predetermined conditions during the life of the detector. One or more of the time related transfer functions each can, when acquired, be compared to the stored initial transfer function established at initial manufacture and calibration of the detector. Span and baseline correction values can be determined. These values can be used to compensate detected output values during normal operation. Time related transfer functions can be compared to each other as well as to the stored initial transfer function.

Abstract: A photoacoustic detector wherein control circuits compensate for long term variations of components therein including a light source and sensing microphones. The control circuits intermittently energize the source to evaluate changes in at least source resistance. The control circuits intermittently energize an acoustic generator to evaluate changes in one or more generator responsive microphones.

Abstract: A photoacoustic detector includes a sensing region for receiving atmospheric samples of a gas. A permeable membrane overlays a gas input port of the sensing region. The membrane is mechanically clamped to the sensing region by a compression force.

Abstract: A photoacoustic detector includes first and second microphones carried by an acoustic sensing chamber. Signals from the microphones are processed using lock-in detection to increase the signal-to-noise ratio. An acoustic pressure generator can be incorporated to calibrate the microphones.

Abstract: A photoacoustic detector includes a sensing region for receiving atmospheric samples. Radiant energy from a source is directed toward the sensing region. A thermal isolator and a displaced optical filter are positioned between the incoming radiant energy and the sensing region so that the radiant energy passes, at least in part, through both elements.

Abstract: Some embodiments relate to a photoacoustic sensor that includes a gas cell having an opening and a detector to collect pressure fluctuations within the gas cell to determine a spectral content of the pressure fluctuations within the ambient environment. The photoacoustic sensor further includes a light source to generate radiation to radiate sample gas within the gas cell and a control that receives signals from the detector that represent the spectral content of the pressure fluctuations within the ambient environment. The control adjusts a frequency of the radiation produced by the light source to a frequency that conflicts less with the spectral content of the pressure fluctuations within the ambient environment. The detector generates output electrical signals in response to acoustic signals generated by pressure fluctuations of the radiated sample gas.

Abstract: A photoacoustic detector wherein control circuits compensate for long term variations of components therein including a light source and sensing microphones. The control circuits intermittently energize the source to evaluate changes in at least source resistance. The control circuits intermittently energize an acoustic generator to evaluate changes in one or more generator responsive microphones.

Abstract: A photoacoustic detector includes first and second microphones carried by an acoustic sensing chamber. Signals from the microphones are processed using lock-in detection to increase the signal-to-noise ratio. An acoustic pressure generator can be incorporated to calibrate the microphones.

Abstract: Some embodiments relate to a photoacoustic sensor that includes a gas cell having an opening and a detector to collect pressure fluctuations within the gas cell to determine a spectral content of the pressure fluctuations within the ambient environment. The photoacoustic sensor further includes a light source to generate radiation to radiate sample gas within the gas cell and a control that receives signals from the detector that represent the spectral content of the pressure fluctuations within the ambient environment. The control adjusts a frequency of the radiation produced by the light source to a frequency that conflicts less with the spectral content of the pressure fluctuations within the ambient environment. The detector generates output electrical signals in response to acoustic signals generated by pressure fluctuations of the radiated sample gas.

Abstract: A photoacoustic detector includes a sensing region for receiving atmospheric samples. Radiant energy from a source is directed toward the sensing region. A thermal isolator and a displaced optical filter are positioned between the incoming radiant energy and the sensing region so that the radiant energy passes, at least in part, through both elements.

Abstract: A photoacoustic detector includes a sensing region for receiving atmospheric samples of a gas. A permeable membrane overlays a gas input port of the sensing region. The membrane is mechanically clamped to the sensing region by a compression force.

Abstract: A photoacoustic detector wherein a detector response transfer function can be measured at various times under predetermined conditions during the life of the detector. One or more of the time related transfer functions each can, when acquired, be compared to the stored initial transfer function established at initial manufacture and calibration of the detector. Span and baseline correction values can be determined. These values can be used to compensate detected output values during normal operation. Time related transfer functions can be compared to each other as well as to the stored initial transfer function.

Abstract: Electrical power generators incorporating stabilized fuels and methods for the encapsulation of fuels are provided. More particularly, methods for the passivation or encapsulation of water reactive, hydrogen gas generating fuels. The electrical power generators employ water reactive fuels encapsulated in a water vapor permeable, liquid water impermeable membrane, or coated with a water vapor permeable, liquid water impermeable substance to control the quantity of water that is permitted reach the chemical fuel. In the event of damage, electrical power generators incorporating the fuels of the invention are protected from explosions that might otherwise result from rapid, uncontrolled hydrogen generation.

Abstract: Embodiments of the present invention relate to a gas sensor comprising a flow channel, a concentration modulator positioned in the flow channel, a gas generator in contact with the flow channel, one or more gas detectors positioned downstream of the concentration modulator and gas generator and a pump.

Abstract: Various embodiments of the application provide a photoacoustic sensor, which includes: a gas cell having an opening; a light source to generate a radiation to radiate sample gas within the gas cell; a detector to detect the sample gas within the gas cell, and to generate electrical signals in response to acoustic signals generated by pressure fluctuations of the radiated sample gas caused by the radiation; and an active valve having a speaker aligned with the opening of the gas cell. The speaker having a voice coil and a diaphragm attached to the voice coil. A control signal is applicable for the speaker to control access of the gas cell. During sampling, the control signal causes the voice coil of the speaker to repeatedly or constantly lift the diaphragm from contact with the opening of the gas cell to allow sample gas enter the gas cell. While during detecting, the spring force of the voice coil causes the diaphragm in tight contact with the opening of gas cell to seal the gas cell.

Abstract: An improved system for generating electrical power using a fuel cell. More particularly, a system for generating hydrogen gas by reacting water vapor with a substantially non-fluid substance and transporting the generated hydrogen gas to the fuel cell which generates electrical power. Reacting water vapor with the non-fluid hydrogen generating substance rather than liquid water prevents caking of the non-fluid substance and deposition of byproducts onto the non-fluid substance that interfere with continued generation of hydrogen gas. Also, a non-electrically actuated valve for use in a hydrogen gas generating apparatus which regulates the generation of hydrogen as required by the fuel cell.

Abstract: Various embodiments of the application provide a photoacoustic sensor, which includes: a gas cell having an opening; a light source to generate a radiation to radiate sample gas within the gas cell; a detector to detect the sample gas within the gas cell, and to generate electrical signals in response to acoustic signals generated by pressure fluctuations of the radiated sample gas caused by the radiation; and an active valve having a speaker aligned with the opening of the gas cell. The speaker having a voice coil and a diaphragm attached to the voice coil. A control signal is applicable for the speaker to control access of the gas cell. During sampling, the control signal causes the voice coil of the speaker to repeatedly or constantly lift the diaphragm from contact with the opening of the gas cell to allow sample gas enter the gas cell. While during detecting, the spring force of the voice coil causes the diaphragm in tight contact with the opening of gas cell to seal the gas cell.