Acoustic ambient temperature and humidity sensing based on determination of sound velocity is described, in addition to sensors, algorithms, devices, systems, and methods therefor. An exemplary embodiment employs sound velocity in the determination of ambient temperature and humidity. Provided implementations include determinations of sound velocity based on time of flight of a coded acoustic signal and/or based on resonance frequency of a Helmholtz resonator.

Faded channels in a distributed acoustic sensing system can be mitigated using a phase modulator. A first pulse and a second pulse of an optical signal can be determined. A phase modulator can modulate the first pulse to have a different wavelength than the second pulse. The first pulse can be launched into a sensing fiber that extends into a wellbore. A first backscattered signal can be received from the sensing fiber in response to the first pulse being launched into the sensing fiber. The second pulse can be launched into the sensing fiber and a second backscattered signal can be received from the sensing fiber. Data about an environment of the wellbore can be determined by processing the first backscattered signal and the second backscattered signal to compensate for fading in the first backscattered signal or the second backscattered signal.

A system for determining gas characteristics at high altitudes in embodiments of the present invention may have one or more of the following features: (a) a high-altitude balloon having one or more of the following features: (a) a balloon, (b) a balloonsat operably coupled to the balloon, (c) an air path chamber wherein gas at a high altitude can occupy the air path chamber, (d) a first speaker located on a substrate within the air path chamber, wherein the first speaker takes an electrical signal input and creates a first sound wave, and (e) a second speaker located on the substrate facing opposite of the first speaker located outside of the air path chamber, wherein the second speaker takes the electrical signal and creates a second sound wave.

Within the scope of the invention, a device for monitoring the quality of a fuel stored in a fuel tank has been developed. The main field of application is diesel-operated vehicles. The fuel is therefore preferably diesel fuel. The device is defined by the fact that means for determining the boiling point of the fuel are provided. Furthermore, a method for monitoring the quality of a fuel stored in a fuel tank has also been developed within the scope of the invention. The main field of application is diesel-operated vehicles. The fuel is therefore preferably diesel fuel. The method is defined by the fact that the boiling point of the fuel or a deviation of this boiling point from a normal value is measured. During the analysis of real injection pumps which have failed it has been detected that an excessively low boiling point of the fuel can cause the fuel to outgas. As a result, bubbles in which the necessary lubrication is no longer provided locally form in the injection pump. Furthermore, the lubricating effect is dependent on the fuel having a certain minimum viscosity. A low boiling point is also correlated with a low viscosity. Therefore, overall, the boiling point (initial boiling point, IBP) is a particularly good indicator especially of those deviations from standard values for the fuel which entail particularly costly damage.

A fluid meter has a measuring tube which has a fluid channel allowing a fluid (F) to flow through and which has a measuring section in which at least one area of a measuring tube wall is formed as a waveguide for surface acoustic waves, which forms an interface with the fluid (F), and at least one transmitter for exciting acoustic waves in the waveguide as well as at least one receiver for receiving acoustic waves from the waveguide, wherein acoustic waves excited by the transmitter can propagate through the fluid (F) as a bulk wave (V) and the bulk wave (V) has at least one reflection point (IP) on the measuring tube wall. The measuring tube wall has a first wall thickness (T1) in the area of the transmitter and in the area of the receiver and has a second wall thickness (T2) which differs from the first wall thickness (T1) in the area of all reflection points (IP) of the bulk wave (V).

Methods and apparatus are disclosed for analyzing structures by applying a continuous ultrasonic excitation and measuring steady state response of the structures using laser Doppler vibrometery, or other techniques. In one example, a method comprises applying a continuous signal having one or more periodic tones to the structure, generating measurements of wave response to the signal at each of a plurality of inspection points of the structure, and, for each of the periodic tones, estimating wavenumbers for a number of the inspection points of the structure based on the wave response measurements and the frequency of the periodic tones. The estimated wavenumbers can be used to determine properties of the structure, including defects, damage, or variation in thickness.

A sensor arrangement and method for measuring the speed of sound in a gas to determine gas characteristics, such as composition, temperature and/or humidity of the gas. The sensor arrangement includes a sound sender, first and second sound receivers, and a signal processing unit. The sound sender and sound receivers are arranged such that the travel distance of the sound provided by the sender to the first receiver is different from the travel distance of the sound provided by the sender to the second receiver. Further the arrangement includes the signal processing unit connected with the sender and the receivers which operates to determine the gas characteristics.

The present invention relates to a surface acoustic wave-based material measuring device, material measuring system, and material measuring method, and more particularly, to a technique of accurately and reliably measuring various inherent physical properties of temperature and frequency-dependent materials by generating multiple resonant waves.

An environmental condition may be measured with a sensor (10) including a wire (20) having an ultrasonic signal transmission characteristic that varies in response to the environmental condition by sensing ultrasonic energy propagated through the wire using multiple types of propagation, and separating an effect of temperature on the wire from an effect of strain on the wire using the sensed ultrasonic energy propagated through the wire using the multiple types of propagation. A positive feedback loop may be used to excite the wire such that strain in the wire is based upon a sensed resonant frequency, while a square wave with a controlled duty cycle may be used to excite the wire at multiple excitation frequencies. A phase matched cone (200, 210) may be used to couple ultrasonic energy between a waveguide wire (202, 212) and a transducer (204, 214).

Systems and methods for analyzing physical characteristics of a battery include arrangements of two or more transducers coupled to the battery. A control module controls one or more of the two or more transducers to transmit acoustic signals through at least a portion of the battery, and one or more of the two or more transducers to receive response acoustic signals. Distribution of physical properties of the battery is determined based at least on the transmitted acoustic signals and the response acoustic signals.