Abstract: Provided are embodiments for a system and method for performing real-time performance and health monitoring of an ice detector system. Embodiments include sensing, by a current sensor, a current parameter of a drive coil of an ice detector circuit, and monitoring a performance and health of the ice detector circuit based at least in part on the current parameter, where the drive coil is coupled to a feedback coil that is configured to provide a feedback signal to a driver circuit to control the drive coil. Embodiments also include comparing the performance of the ice detector circuit and expected performance of the ice detector circuit, and providing a report based at least in part on the comparison.

Abstract: The invention relates in particular to a method for determining physical, chemical, and/or biological properties of a medium (M) located in the interior (30) of a waveguide (3) using at least one acoustic wave which has propagated at least partly through the medium (M). According to the invention, a first wall section (31a) and a second wall section (31b) of the waveguide (3) are connected together via a connection piece (31c) such that a second surface wave (OW2) propagates to the first wall section (31a) at least partly via the connection piece (31c). One of the wall sections (31a, 31b) and/or the connection piece (31c) is provided with at least one reflective element (4) on which at least one pert of a: least one first surface wave (OW1) that is excited on the first wall section (31a) by incurs of a transmitter (SE) is reflected ss a third surface wave (OW1?).

Abstract: A refrigerator including a compressor, a condenser, and an expansion unit that constitute a refrigeration cycle, an evaporator that evaporates a refrigerant that has passed through the expansion unit, a heater that provides heat for defrosting the evaporator, and a frost sensor that is provided at one side of the evaporator to sense the amount of frost on the evaporator, the frost sensor including a sound-source transmitter that generates a sound-source of a first volume to the evaporator, and a sound-source receiver that receives a sound-source of a second volume formed after the sound-source transmitted by the sound-source transmitter reflects from or passes through the evaporator, and a controller that controls the heater to generate heat, when the difference between the first volume and the second volume reaches a predetermined volume.

Abstract: Apparatus and associated methods relate to determining liquid-water concentration in a cloud atmosphere based on a frequency of resonance of a magnetostrictive resonator and/or a temporal variation of the resonant frequency of the magnetostrictive resonator. The magnetostrictive resonator is configured to resonate at a resonant frequency indicative of a measure of ice accumulation upon an exterior surface of the magnetostrictive resonator. When in liquid-water ambient, however, the magnetostrictive resonator has a resonant frequency less than a baseline resonant frequency. When in the liquid-water ambient, the magnetostrictive resonator also has temporal variations in resonant frequency that exceed one part in ten thousand. Using one or both of these resonant-frequency responses to liquid-water ambient, a signal indicative of liquid-water content can be generated.

Abstract: An actuator mounting method for mounting at least one actuator involves providing a skin structure and at least one actuator, and fixing the at least one actuator to the inner surface of the skin structure.

Abstract: A system for detecting ice or water within an area of interest having a detection system measuring radiance or reflectance of the area of interest when exposed to shortwave infrared radiation having a wavelength in the range containing a crossover point between the curves representing the absorption of electromagnetic radiation by ice and water. The detection system measures the radiance or reflectance in a first band having a wavelength in a spectral band on a first side of the crossover point and outputting a first band signal, and further measures the radiance or reflectance in a second band having a wavelength in a spectral band on a second opposing side of the same crossover point and outputting a second band signal. A processing unit determines a ratio of the first band signal and the second band signal and compares the ratio to a predetermined critical ratio and outputs a determination signal indicating presence of ice or water.

Abstract: A method is provided that includes a number of operations performed in real-time during flight of the aircraft. That is, the method may include monitoring a continuous electrical signal output by a sensor on a surface of the aircraft, where a magnitude of the electrical signal may be related to an amount of ice buildup. The method may include calculating a liquid water content (LWC) value as a function of a rate of change of the electrical signal, and iteratively calculating a total water exposure (TWE) value as a function of the LWC value. The TWE value may represent a total water exposure of the aircraft from a time of an initial event, and may be calculated as a running total over a plurality of iterations. And the method may include performing a remedial or alert action in an instance in which the TWE value reaches a TWE threshold.

Abstract: The present invention utilizes an accelerometer (included within a wireless physiology monitoring device or as part of a separate device such as, but not limited to a smartphone, e.g., iPhone, or other mobile device) to link a patient with a separate medical data acquisition device such as a weight scale or a blood pressure monitor in order to collect and transmit a range of medical data associated with the user. The medical data acquisition device includes a vibration source for emitting a vibration at a predetermined or random frequency. When the acquisition device is activated, a vibration is transmitted from the through the patient and is detected by the accelerometer. The accelerometer then measures the particular frequency of vibration and transmits this information to a centralized monitoring unit (CMU). Based on the measured frequency, the CMU is able to know that the same patient wearing/holding the device is also the same patient using the data acquisition device.

Abstract: There is provided a lightweight, slim and compact haptic feedback device due to an actuator module constituted of a piezoelectric element and a vibration plate, and an electronic device having the same. The haptic feedback device includes a haptic device receiving contact pressure applied thereto, and an actuator module being in contact with a lower surface of the haptic device and excited according to variations in contact pressure with the haptic device to thereby generate vibrations.

Abstract: A system for preventing icing in a conduit, as can occur in an aircraft's air conditioning system, includes at least one sensor for acquiring mechanical oscillations of the conduits, an electronic evaluation unit and an electronic control unit. The sensor is connected to the electronic evaluation unit, which knows characteristics relating to the oscillation behavior of the conduit and is equipped to compare the measured conduit oscillations with these characteristics, and through correlation to interpret them as conduit icing, and in the case of conduit icing to emit a signal to the control unit. If the operation-associated oscillations are inadequate, oscillations can be generated or amplified through an actuator. With this system an icing state within the conduit can be detected without the use of sensors located in the interior cross section of the conduit, which itself serves as a sensitive element.

Abstract: Disclosed herein is a vibrotactile device intuitively providing information by inducing a tactile sense to a user, and a method using the same. The device according to an embodiment includes a vibrating contact panel contacting with a user's hand; a plurality of vibratory modules that are attached to the lower part of the vibrating contact panel and vibrate with different intensities according to the amount of supplied power; and a plurality of vibration isolating links that are coupled, respectively, to an end of each of the modules to support the modules and to isolate the vibration from the modules.

Abstract: A content server system includes a remote content server including content license information and a local content player coupled to the remote content server by a network, the local content player requiring verification of a license by a user of the local content player as administered by the remote content server. In an alternate embodiment the network includes a local area network. In another alternate embodiment, the network includes the Internet.

Abstract: An aircraft Ice Detection pitot-static tube is described which uses sensors integrated into the pitot-static tube to determine when and where the pitot-static tube is icing up. Temperature, thermal conductivity and impedance sensor measurements are combined with a mathematical transfer of the impedance sensor output into the complex dielectric plane to identify that the material accreating on the exterior and interior of the pitot-static tube is ice and only ice. Identification of ice realized when the trace in complex dielectric space has a distinctive semi-circular form, which only ice exhibits, with measured values in agreement with reference laboratory data stored in the onboard computer system.

Abstract: An optical system for detecting ice and water on the surface of an aircraft includes an elongated transparent optical element having first and second end portions. A light source and light detector are disposed in one end of the optical element and a reflective surface is disposed in the opposite end portion. The reflective surface defines a critical angle and reflects light from the light source to the light detector when the critical angle is in contact with air and refracts the light toward the external environment when the reflective surface is in contact with ice or water. The system may also incorporate an optical element wherein the reflective surface includes a continuous array of convex elements extending outwardly from and across one end of the optical element and wherein each of the convex elements defines a critical angle.

Abstract: A method for automatically switching an incoming call signal output mode in a mobile communication terminal is disclosed. The method comprises the steps of determining whether or not a present incoming call signal output mode is a vibration mode when receiving incoming call, driving a vibrator to output vibration if it is determined that the present incoming call signal output mode is set to the vibration mode, detecting an intensity of actual vibration of the terminal via a vibration detection sensor when the vibration is output, followed by calculating transfer energy using the intensity of the actual vibration on the terminal, and automatically switching the incoming call signal output mode from the vibration mode to a ringtone mode according to comparison of the calculated transfer energy with a reference value. With the method, a user can easily recognize the incoming call signal.

Abstract: An optical system for detecting ice and water on the surface of an aircraft includes an elongated transparent optical element having first and second end portions. A light source and light detector are disposed in one end of the optical element and a reflective surface is disposed in the opposite end portion. The reflective surface defines a critical angle and reflects light from the light source to the light detector when the critical angle is in contact with air and refracts the light toward the external environment when the reflective surface is in contact with ice or water. The system may also incorporate an optical element wherein the reflective surface includes a continuous array of convex elements extending outwardly from and across one end of the optical element and wherein each of the convex elements defines a critical angle.

Abstract: The present invention relates to a direction guide vibration system of a vehicle operating with a navigation and control method thereof, which applies vibration to a driver's seat on which a driver sits at the spot where a left turn or a right turn and a U turn are expected, on a path to move to a driver's intended destination, informs a driver thereof in advance for people and the hearing impaired using a navigation and informs the driver thereof before an enforcement area in which an over-speed camera is installed, thereby securing a safe driving of a vehicle.

Abstract: An optical system for detecting ice and water on the surface of an aircraft includes an elongated transparent optical element having first and second end portions. A light source and light detector are disposed in one end of the optical element and a reflective surface is disposed in the opposite end portion. The reflective surface defines a critical angle and reflects light from the light source to the light detector when the critical angle is in contact with air and refracts the light toward the external environment when the reflective surface is in contact with ice or water. The system may also incorporate an optical element wherein the reflective surface includes a continuous array of convex elements extending outwardly from and across one end of the optical element and wherein each of the convex elements defines a critical angle.

Abstract: A system for detecting ice formation on metal, painted metal and other material surfaces can include a transparent window having an exterior surface upon which ice can form; a light source and optics configured and arranged to illuminate the exterior surface of the window from behind the exterior surface; and a detector and optics configured and arranged to receive light backscattered by the exterior surface and any ice disposed on the exterior surface and determine the thickness of the ice layer. For example, the system can be used with aircraft by placing one or more windows in the wings of the aircraft. The system is used for a novel optical method for real-time on-board detection and warning of ice formation on surfaces of airplanes, unmanned aerial vehicles (UAVs), and other vehicles and stationary structures to improve their safety and operation.

Abstract: Apparatus, methods, system and devices for monitoring road surface temperature to detect hazardous road surface conditions. An indicator provides the sensed road surface temperature and hazardous road condition warning to a driver while a tail light interface automatically produce a tail light signal to warn drivers traveling behind the vehicle when a hazardous condition is detected. In an embodiment, the system includes a vehicle engine retardation system interfaced with the hazardous road condition warning system. When the retardation system is in use and hazardous road surface conditions are detected the controller automatically produces the brake light signal unless a tail light control switch is used to manually deactivating the automatic tail light flashing signal when the vehicle is traveling in a state that does not allow alternative control of the brake lights.

Abstract: The present invention is a system and method of biometric-based identity verification for authorizing financial transactions between a consumer and a merchant, said system comprising distributed processing to facilitate biometric matching and various types of financial transactions to facilitate said system's integration into current financial networks. System users register at least one biometric identifier, personal and/or business identity-verifying data, and financial account information. A user presents a biometric sample obtained from the user's person and the user's system ID number to conduct financial transactions. This data is used to authenticate the user's identity and authorize transfer of funds from the user's registered financial account to the designated recipient's account by matching the presented transaction biometric with at least one registered biometric template and without the use of a man-made financial account token or identity token.

Abstract: A wireless communication and global location enabled intelligent health monitoring system comprising of a plurality of wireless medical sensor apparatus that include an active sensor, a transducer, a digital-to analog converter, a frequency synthesis, a plurality of bandpass filter, a plurality of linear power amplifier, a signal mixer, a packaged antenna, a thin-film battery, for measuring patient vital signs on different parts of patient body, and a main processing unit apparatus that contains a system software including intelligent controller which uses active, real-time monitoring method to measure and process vital signs and location information for providing alert on location and transmitting emergency request to remote patient monitoring station for immediate assistance. Intelligent controller and all application tasks of said system software are running under separate parallel execution threads.

Abstract: An acoustic wave sensor utilizes one or more acoustic waves trapped in an acoustic wave cavity to detect the presence of one or more substances on a surface of the acoustic wave cavity. To detect the presence of ice, a trapped torsional acoustic wave is used. To detect water, an acoustic wave with flexural or compressional components is used. The sensor includes a number of transducers adjacent the acoustic wave cavity where a controller drives different sets of the transducers to generate different acoustic waves.

Abstract: A sound collecting device is provided which is designed to minimize adverse effects on an output caused by exposure of an electroacoustic transducer to the air. The device includes an electroacoustic transducer and a vibrating circuit. The transducer is exposed to the air and responsive to input of a sound wave to produce a corresponding acoustic signal. The vibrating circuit vibrates the transducer to shake foreign substances such as dust or drops of water from the transducer. In a modified form, an electromagnetic sensor is provided which measures an electromagnetic noise transmitted to the transducer and which removes the electromagnetic noise from an output of the transducer to produce a noiseless acoustic signal.

Abstract: In a method for determining the state of a road during driving of a motor vehicle, the sound which is generated when a vehicle tire rolls on an underlying surface is sensed. A frequency signal is determined by means of a sound level signal which describes the sound, and is divided into at least two sub-zones by means of at least one limiting frequency. The sub-zones are each assigned to an associated frequency band, and an intensity value is determined for each of at least two frequency bands from the assigned sub-zone of the frequency signal. The intensity value is characteristic of the sound intensity which is present in a frequency band. An intensity ratio is formed from two intensity values by dividing the first intensity value of the first frequency band by the second intensity value of the second frequency band, and is used to determine the state of a road.

Abstract: A telecommunications network includes a mobile phone with an audio-modulated vibrotactile module that responds to a telecommunications signal containing information about incoming speech from a called/calling party, for providing an audio-modulated vibrotactile module force containing information about the incoming speech from the called/calling party to vibrate a user's fingers, facial skin, wrist, cheek or other suitable location. The audio-modulated vibrotactile module has an audio-to-vibrotactile converter that responds to the telecommunications signal, for providing an audio-to-vibrotactile converter signal containing information about a vibration modulation of the incoming speech from the called/calling party. The audio-modulated vibrotactile module also has a vibrotactile actuator that responds to the audio-to-vibrotactile converter signal, for providing the audio-modulated vibrotactile module force in the form of a vibrotactile actuator force.

Abstract: Ice accretion on a probe is detected by determining the change of frequency of a vibrating type ice detector or sensor as ice starts to build up. The rate of change of frequency is determined and is combined with parameters including air velocity and air temperature for providing a signal that indicates liquid water content in the airflow as well as ice accretion on the ice detector.

Abstract: An ice detector has a pair of probes, each of which is used for determining the accretion of ice thereon. One of the probes in the assembly is configured so the smaller droplets of supercoooled water are inertially separated and flow away from the one probe. The ice accretion on the one probe is primarily from large (50 microns or greater) supercooled droplets. The ice accreting on the one probe is therefore biased to supercooled large droplets. The probes are connected to detection circuitry that will determine the ratio of the rates of icing between the probes so the presence of supercooled large droplets can be determined. In one form, a flow guide is arranged to create an airflow that carries smaller droplets past one of the probes without impinging on the probe, but the higher inertia, supercooled large droplets will impinge on that one probe.

Abstract: Ice accretion on a probe is detected by determining the change of frequency of a vibrating type ice detector or sensor as ice starts to build up. The rate of change of frequency is determined and is combined with parameters including air velocity and air temperature for providing a signal that indicates liquid water content in the airflow as well as ice accretion on the ice detector.

Abstract: An ultrasonic ice detector that can be mounted directly to the skin of an aircraft includes a transducer that is coupled to the interior surface of the skin, and transmits acoustic vibrational energy through the skin. A reflector bar having a reflector surface is mounted on the interior surface of the skin at a location spaced from the transducer and is effective to reflect acoustic energy back to the transducer. The reflector bar is raised from the interior surface and preferably has a width equal to the width of the acoustic wave that is generated by the transducer at the reflector location. The transducer and reflector are non-intrusive and do not alter the aircraft skin structural integrity. The arrangement provides an accurate, responsive sensor for determining presence of ice or other contaminants on the exterior surface of the skin.

Abstract: Disclosed is an apparatus and a method for de-icing an intake opening (2) in an intake duct (1) of a fire alarm system, through which ambient or equipment air is drawn in and supplied to a detector for sensing a fire parameter. To effectively remove an ice deposit on the intake opening (2) there is provided, in or on the intake opening (2), an elastic element having a through-hole (3) coaxial with the intake opening (2) which is adapted to be subjected to a compressed air blast in order to de-ice the intake opening (2) (FIGS. 4a to 4c).

Abstract: An apparatus for determining a road pavement surface condition over a wide area has a road noise sensor (12). A temporal frequency analyzer (18) converts a road noise signal from the road noise sensor (12) to a temporal frequency signal. A processing circuit (20) receives the temporal frequency signal from the temporal frequency analyzer (18) and analyzes the temporal frequency signal to determine the road pavement surface condition.

Abstract: A sensor is provided for detecting the presence of dielectric media, e.g., ice. The sensor includes a plurality of microstrip resonators which are positioned for electromagnetic coupling with a microstrip transmission line. The resonators produce amplitude minima in a radio-frequency signal that is carried over the transmission line. The resonance of the resonators changes in response to the addition of a dielectric coating. Each resonator can be configured with a different resonant frequency which serves as a signature that identifies the respective resonator's position. The sensor has a thin aerodynamic profile, can conform to nonplanar surfaces and its installation requires no intrusion into an aircraft skin.

Abstract: An embodiment of the present invention is a roadway sensor for surface installation in a hole such that a thin ceramic contact sensor may be used to measure and cross-compare fundamental physical antenna parameters of the space immediately above a roadway or bridge surface. Measurements are combined by a microprocessor to discriminate between dry pavement, water (rain), snow and ice above the sensor head. Ambient surface temperature, water depth and ice/slush conditions are determined to estimate any hydroplaning hazard and ice/antifreeze/water mixtures. The sensor comprises an antenna that exhibits a resonant frequency and an input admittance including a real term; a Maxwell bridge coupled to the antenna for detecting the resonant frequency, input admittance and real term; and a frequency sweeping oscillator for driving the antenna at a plurality of frequencies proximate in frequency to the resonant frequency.

Abstract: A sensor arrangement for identifying various states of water on a surface of a structure, comprises a sensor element and a transmitter-receiver unit. The sensor element, adapted to be placed on the surface, has two ends and is made of an acoustically conductive material. The transmitter-receiver unit is connected between the two ends of the sensor element. The transmitter-receiver unit alternately transmits acoustic signals to each of the two ends and receives acoustic signals corresponding to the transmitted signals from each of the two ends for subsequent processing.

Abstract: There is described a method and apparatus for detection and thickness evaluation of a buildup of a solid, e.g. ice, or liquid on a solid surface, such as ice on a body of an aircraft. The apparatus comprises a source of a narrow beam of radiation and a means for remote evaluation of the size of a luminous area created on the solid surface by the beam. The method of the invention involves measuring the size of the luminous area and determining the thickness of any built-up layer, if sufficiently transparent, using a formula which uses the dependency of the size of the luminous are on the thickness of the layer and the refraction index of the medium. Differentiation between ice and a liquid is possible by evaluating regularity of illumination of the luminous area.

Abstract: A method and an apparatus for detecting and identifying a contaminant, such as ice, on the surface of a structure, such as a wing, are disclosed. The apparatus has a probe having a delay block with an interface apt to be placed flush with the surface of the structure and two faces at the same angle of inclination relative to the interface and having transmission and reception transducers each oriented perpendicularly to one of the faces. The block has an acoustic impedance lying in the range of 0.7 to 3.times.10.sup.6 kg/m.sup.2.s. It further has an energization and analysis unit for applying an electrical energization pulse to the transmission transducer and comparing the amplitude and the phase of the echo from the interface with a reference echo corresponding to no contamination.

Abstract: An embodiment of the present invention is an ice detection system that comprises a network of thin, flexible microstrip antennas distributed on an aircraft wing at critical points and multiplexed into a microcomputer. Each sensor antenna and associated electronics measures the unique electrical properties of compounds that accumulate on the wing surface over the sensor. The electronics include provisions for sensor fusion wherein thermocouple and acoustic data values are measured. A microcomputer processes the information and can discern the presence of ice, water frost, ethylene-glycol or slush. A program executing in the microcomputer can recognize each compound's characteristic signal and can calculate the compounds' thicknesses and can predict how quickly the substance is progressing toward icing conditions. A flight deck readout enables a pilot or ground crew to be informed as to whether deicing procedures are necessary and/or how soon deicing may be necessary.

Abstract: A detector indicating ice formation on the wing of an aircraft or any planear surface, based on a thread-like or a tape-like transducer, through which an ultrasonic signal is transmitted at one end. The attenuation of the signal having passed through the thread is measured with a receiver at the opposite end while the thread is simultaneously being heated such that ice that may surround it melts again, the attenuation thus resuming its initial level.

Abstract: The de-icing system of the present invention comprises a piezoelectric sensor means and a processor means. A piezoelectric film is the preferred sensor means and a microprocessor is the preferred processor means. In a preferred embodiment, a strip of piezoelectric film placed at a point of model kinetic energy such as the boundary layer transition point or the vortex generator of the aircraft. Such placement of the strip provides adequate airflow to excite the piezoelectric film without using a power source, thus providing a passive system. The sensor allows measurement of distributedSTATEMENT REGARDING FEDERALLY SPONSORED RESEARCHThis invention was made with Government support under Contract No. DAAH01-87-C-0860 awarded by the Defense Advanced Research Agency (DoD), Defense Small Business Innovation Research Program. The Government has certain rights in this invention.

Abstract: A matter sensing apparatus includes a piezoelectric transducer, having a face susceptible to matter accretions at a surface for which matter accretion detection is desired. The electrical circuit of the transducer is coupled in the feedback path of an amplifier to establish an oscillator that oscillates at frequencies determined by the resonant frequency of the transducer and the loading on its face. The oscillator signals are converted to binary signals and utilized with binary signals, provided by a thermostat, that a representative of temperatures above or below a selected temperature to provide signals indicative of whether ice or other matter has accredited on the surface.

Abstract: This invention provides an icing preventive device for a supersonic wave transmitting and receiving unit for a vehicle which is composed of a timing device for outputting a timing signal, a supersonic wave transmitting and receiving device for transmitting a supersonic wave signal and receiving a reflected wave in response to the timing signal, a received signal processing device for amplifying the received signal caused by the reflected wave and processing the waveform of the amplified signal, a control device for controlling a vehicle load in response to the received signal of which waveform is processed, a temperature sensing device for sensing a temperature outside the vehicle, a heater operating device for energizing and heating the heater in response to both decrease in the temperature outside the vehicle and a level of the received signal of the reflected wave, and a heater arranged in the supersonic wave transmitting and receiving device, and further the present invention discloses the technology of t

Abstract: The disclosure describes a system for measuring glaze ice, comprising a glaze-ice detector, a device connected to the detector to generate a signal indicating the formation of a specific quantity of glaze ice on the detector, and another device which responds to the signal, and causes sufficient heating of the detector to melt the glaze ice formed on it. The detector is characterized by the fact that it removes the water formed by this melting of the glaze ice before a new quantity of glaze ice has formed on the detector and been detected. An advantage of this system is that it can detect any formation of glaze ice with accuracy and without error.

Abstract: Method and apparatus for measurement of ice thickness employing ultra-sonic pulse echo technique, wherein an ultra-sonic pulse is emitted from a transducer at the ice-accreting surface of a structure, the pulse is reflected at the periphery of the accreted ice and the reflection is detected. The time delay is calibrated and related to ice thickness and accretion rate.

Abstract: An ice detector of the vibrating element type comprises a tube that vibrates along its longitudinal axis, and is driven by an excitation coil at the natural frequency of the tube is sealed by a diaphragm which has a surface exposed to an air stream in which icing is to be sensed. The exposed diaphragm surface is deflectable during vibration of the tube at a flexible support portion of the diaphragm. As ice accumulates on the exposed surface of the flexible support the spring rate or flexibility of the flexible support changes, thereby changing the natural frequency of the vibration of the tube section. The changes in the natural frequency are sensed to determine that ice is accumulating. The diaphragm is of low mass, and small so that stiffness of small amounts of ice significantly changes the spring constant of the flexible support and the diaphragm is shaped to conform to adjacent aerodynamic surfaces.

Abstract: An ice detector to detect a lyaer of ice on a thin solid sheet 14, such as the skin of an aircraft wing, even in the presence of water, comprises two ultrasonic transducers attached to the sheet. The first transducer 10 is adapted to cause propagation of ultrasonic waves through the sheet 14 having their predominant component parallel to the surface of the sheet 14. Such waves will dissipate energy into an ice layer adhering to the surface, but not into air or a liquid layer. The second transducer 30 is adapted to detect the waves propagating in the sheet and to give a signal representative of their amplitude. A discriminator 34 responsive to the signal detects the presence of an ice layer on the surface.

Abstract: An ice warning system comprising a diaphragm set into vibration at one of its frequencies of resonance by a piezoelectric cell. The diaphragm is coupled thermally to a metallic plate alternately cooled and heated respectively below and above the ambient temperature by Peltier elements connected to a reversible DC current generator. A microprocessor measures any variation of the resonance frequency caused by a deposit of ice on the diaphragm during the cooling or heating periods and delivers an alarm signal if this variation of frequency reaches and/or exceeds a predetermined value. The microprocessor controls the period, intensity and direction of the current delivered by the DC current generator as a function of the ambient temperature and the temperature of the diaphragm. The ice warning system is preferably utilized in the aeronautical field for indicating the likelihood of natural ice formation on the engines and the wings of aircraft.

Abstract: A vibrating body is connected as one element of a voltage divider. A detector circuit is connected to the measuring point of the voltage divider. If ice is deposited on the body, its impedance changes and the resulting voltage change at the voltage divider is detected to provide an alarm or control function. The noted impedance change can be more reliably detected under a variety of conditions than the traditional vibration frequency or amplitude criteria.

Abstract: An improved ice detector has a vibrating element which has a front portion and vibrating means suitably disposed with respect to the vibrating element for exciting the vibrating element into vibration and means for sensing a shift of the frequency of vibration of the vibrating element resulting from a change of mass of the vibrating element due to ice accumulating thereon. The improvement is characterized in that the ice detector is supported with respect to a surface exposed to an air stream such that a cap on which ice forms and which is disposed on the front portion of the vibrating element, is exposed to the air stream and is formed to be substantially conformal to such surface.

Abstract: A sensor for monitoring the deposition of frozen fog and/or ice on evaporator, refrigeration machine or heat pump surfaces, includes a can-shaped housing having opposite sides. A mounting heat conductingly connects the housing to the evaporator. First and second membranes are respectively disposed at the opposite sides of the housing, and first and second electro-acoustic transducers are each attached to a respective one of the membranes. An alternating voltage is applied to the first transducer causing the first transducer to oscillate the first membrane, and the second membrane is spaced from the first membrane by a distance permitting oscillation of the first membrane to oscillate the second membrane.