390 results about "Acoustic resonance" patented technology

A circuit arrangement and control thereof for igniting a high intensity discharge (HID) lamp, for reducing the high frequency ripple superimposed on the low frequency rectangular waveform lamp current after ignition, and for increased circuit efficiency. The high frequency ignition voltage is only applied to the lamp during ignition phase and is mainly generated by the second stage of the low pass (LP) filter. The first stage of the LP filter whose resonant frequency is below the second stage further attenuates the high frequency ripple current through the lamp in normal operation. The resulting lamp current is a low frequency rectangular wave with less than 10% high frequency ripple. Acoustic resonance is avoided. The inductor in the first stage of LP filter is operated in discontinuous current mode. Doing so, the active switches are in zero current switching (ZCS) to maximize the circuit efficiency.

A method for analyzing gas concentration using doubly resonant photoacoustic spectroscopy, and a doubly resonant photaoacoustic gas detector comprising: i) a continuous wave light beam whose wavelength coincides with an absorption wavelength of a gaseous analyte; ii) a closed path optical cavity having at least two reflective surfaces; iii) an acoustic resonator chamber contained within said optical cavity, and comprising an acoustic sensor for detecting sound waves generated by a gaseous analyte present within said chamber, the light beam passing sequentially into, through and out of said chamber, and being repeatedly reflected back and forth through said chamber, and being modulated at a frequency which is equal to or equal to one-half of an acoustic resonance frequency of said acoustic resonator chamber.

An acoustic resonance device is installed in a compartment of a vehicle so as to reduce a low-frequency sound pressure (or noise) dependent upon a natural vibration. Specifically, an acoustic resonance device is a panel/diaphragm resonator, a resonance pipe, or a Helmholtz resonator, the inner space of which communicates with the compartment via an opening. The acoustic resonance device is positioned in proximity to an antinode of sound pressure owing to a natural vibration occurring in a driver/passenger space inside the compartment. Alternatively, the acoustic resonance device increases a particle velocity at a specific natural frequency or decreases sound pressure at an excitation frequency which occurs due to an external condition of the vehicle. The acoustic resonance device can be installed in a roof, a seat, a pillar supporting the roof, or a door of a vehicle.

A bleed air duct that preferably includes an inlet section configured to include a flush scoop and a louver. The louver is located and configured such that in the desired operating flow range of the duct, the fluid entering the flush scoop is disturbed and as a result creates a low pressure region downstream of the louver. The low pressure region substantially eliminates the generation of any pressure pulses and acoustic resonance also known as Helmholtz resonance.

The invention discloses a microfluidic chip and a cell screening method for screening specific cells. The chip comprises a substrate, a cavity and an acoustic excitation source, wherein the cavity comprises a middle channel, an inlet and an outlet; the acoustic excitation source is positioned on the substrate and at two sides of the middle channel and comprises two parts which extend to a direction of the outlet along the middle channel, wherein the corresponding acoustic resonance frequency of the second part close to the outlet is integer multiples of the corresponding acoustic resonance frequency of the first part far away from the outlet. Based on an acoustic streaming effect formed by targeted microbubbles and asymmetric sound fields, the microbubbles are adhered to the surfaces of the specific cells, so that the enriched cells which flow past the first part can still move in a straight line and cannot diffuse due to a laminar flow characteristic of microfluidics, and the specific cells bonded with the targeted microbubbles can shift because the acoustic resonance frequency of the second part is different from that of the first part. Thus, the screening of the specificity of the specific cells in blood is realized.

A photoacoustic spectroscopy method and apparatus for maintaining an acoustic source frequency on a sample cell resonance frequency comprising: providing an acoustic source to the sample cell to generate a photoacoustic signal, the acoustic source having a source frequency; continuously measuring detection phase of the photoacoustic signal with respect to source frequency or a harmonic thereof; and employing the measured detection phase to provide magnitude and direction for correcting the source frequency to the resonance frequency.

A headset device comprising first and second headphones interconnected through a headband, wherein each of the first and second headphones comprises an earcup defining a unitary acoustic resonance chamber, a foraminous driver mount positioned offset from both a lateral axis and a longitudinal axis defined by the earcup, and a diaphragm retention ring extending from a surface of the foraminous driver mount. Each of the headphones further comprises a driver mounted within the driver mount and including a diaphragm, a foraminous unitary diaphragm support for maintaining the driver within the driver mount, an earcup cover attached to the earcup, and an earpad attached to the earcup.

An embodiment of the present invention provides a device, comprising a multilayered tunable dielectric capacitor, wherein said multilayers of tunable dielectric are adapted to be DC biased to reduce the dielectric constant; and wherein the DC bias is arranged so that the number of layers of tunable dielectric biased positively is equal to the number of layers of tunable dielectric biased negatively.

A urea quality sensor includes an acoustic resonator in order to measure the accurate concentration of urea by measuring change in molecular weight. A change in molecular weight of urea proportionately affects the speed of sound. The change in the composition of the urea solution manifests itself as a change in frequency. The concentration of the urea solution can be determined based on the frequency data obtained as a result of the frequency measurement utilizing the acoustic wave sensor. The urea quality sensor can be used with an NH₃ sensor in order to identify that the solution is urea.

An apparatus and method for reducing brake squeal in a web tension brake. The apparatus comprising an anti-squeal friction pad assembly having a friction pad mounted on a back plate and a rubber isolation layer sandwiched between the back plate and a second back plate. The rubber isolation layer to dampen vibrations and break up the symmetry of the brake assembly minimizing acoustic resonances that cause the objectionable squeal.

The invention provides a generator capable of collecting acoustic energy, which combines a Helmholtz acoustic resonance cavity and a triboelectric nanometer generating component. The triboelectric nanometer generating component with thin membrane structures is arranged on the outer wall or at the opening position of the Helmholtz acoustic resonance cavity. Sound passes through the acoustic resonance cavity to allow an electrode layer and a frictional layer of the triboelectric nanometer generating component to mutually contact and separate and to generate electric energy on two electrode layers. The generator does not need to be provided with a vibrating membrane, and can reduce unnecessary acoustic energy loss, and efficiently convert sound energy into electric energy; the generate can be used as a sound sensor which does not need a power supply, and is a self-driven passive sound sensor.

The invention relates to an acoustic resonance type thermally-driven travelling wave thermo-acoustic refrigerating system. The acoustic resonance type thermally-driven travelling wave thermo-acoustic refrigerating system is composed of N elastic films and N thermo-acoustic units, wherein the thermo-acoustic units are connected end to end through resonance tubes and form an annular loop, N is a positive integer ranging from 3 to 10, and the phase difference of volume flow rates of the two ends of each thermo-acoustic unit is 360 degrees/N. Each thermo-acoustic unit is composed of a thermo-acoustic engine and a pulse tube refrigeration machine. No movable parts are arranged in the refrigerating system, and reliability of the refrigerating system is further improved. Pure travelling wave phase positions can be obtained in an acoustic resonance loop system, acoustic power flowing out of each thermo-acoustic unit through the corresponding pulse tube refrigeration machine is recycled by the next thermo-acoustic unit, and therefore work efficiency of the system can be further improved. In addition, different numbers of thermo-acoustic units can be connected in series according to the required cooling capacity condition so that large-cooling-capacity output can be achieved. The acoustic resonance type thermally-driven travelling wave thermo-acoustic refrigerating system is large in cooling capacity, high in efficiency, long in service life and simple in structure, and has good application prospects in places where the requirements for cooling capacity are high.

A noise control system is operable within a box-like structure provided by the dual bulkhead plenum of the vehicle dashboard positioned within the transfer path along which the noise is being transmitted from the source of the generated noise to the receiver of the noise in the passenger compartment of an automobile. The plenum is divided into discrete chambers into each of which is provided a counter noise generating apparatus to create a counteracting noise offsetting the noise generated at the source. The acoustic resonance of the chambers amplifies the noise control energy. The geometry of the individual chambers can be varied to optimize the packaging and sound control or shaping strategy. The sound energy permitted to pass through the plenum to the driver's side of the passenger compartment can be tuned to be different than the noise received in the passenger's side.

A method and system provides for acoustic sensing of structures, including a general shape and/or configuration of the structure and movement within the structure. Acoustic waves are used to characterize structures, including any activity within. As waves from a sound source travel into the structure, they resonate within cavities and connecting tunnels or halls. This acoustic resonance is received at an acoustic receiver. The received signal is analyzed in comparison to the generated signal, and properties of the structure are determined, including the size and shape of the structure, as well as movement of objects within the structure.

An acoustic resonance igniter uses high-pressure helium to heat a resonance cavity so a hot surface of the resonance cavity forms a source of ignition to a combustion chamber. The resonance cavity may be round or may extend linearly to increase the size of the hot surface. The combustion chamber is cooled by arranging a feed of hydrogen and oxygen which is oxygen rich and which becomes more so when ignition occurs. A second combustion chamber receives the combustion chamber output and adds additional hydrogen through ports tangential to the wall of the second combustion chamber to enrich the fuel ratio and cool the second combustion chamber. The acoustic resonance igniter is used to ignite a large rocket engine or to form a rocket thruster.