83 results about "Broadband excitation" patented technology

A magnetic resonance system, comprising at least one SQUID, configured to receive a radio frequency electromagnetic signal, in a circuit configured to produce a pulsatile output having a minimum pulse frequency of at least 1 GHz which is analyzed in a processor with respect to a timebase, to generate a digital signal representing magnetic resonance information. The processor may comprise at least one rapid single flux quantum circuit. The magnetic resonance information may be image information. A plurality of SQUIDs may be provided, fed by a plurality of antennas in a spatial array, to provide parallel data acquisition. A broadband excitation may be provided to address a range of voxels per excitation cycle. The processor may digitally compensate for magnetic field inhomogeneities.

An inbuilt damping device for a hollow shaft comprises an elastic shaft arranged in the hollow shaft. The elastic shaft is of a three-segmental stepped shaft structure. One end of the middle segment is sequentially divided into a large diameter, a medium diameter and a small diameter along the axial line; the segments at the two ends are respectively divided into large diameters, medium diameters and small diameters in sequence along the axial line in the direction from the two end faces of the middle segment to the respective ends in the mode of being smaller than the small diameter of the middle segment; the segments of the small diameters of the three segments of stepped shafts are all provided with threads; a cylindrical inertia wheel and a second spacer are installed on the medium diameter of the middle segment in a sleeved mode, and the cylindrical inertia wheel is filled with damping particles and is fastened by connecting a second nut and the threads; the medium diameters of the segments at the two ends are respectively sleeved with a stop block, a taper and a first spacer, wherein the tapers are circular-frustum-shaped bodies provided with center holes; upper membranes and lower membranes are installed on the outer conical surfaces of the tapers in a sleeved mode and provided with taper holes; the tapers are fastened by connecting first nuts and the threads. According to the inbuilt damping device for the hollow shaft, torsional vibration, transverse vibration, longitudinal vibration and coupling vibration on a shafting can be simultaneously controlled; furthermore, the inbuilt damping device has the damping effect of more than 10dB on broadband excitation force within a wide rotating speed range of the shafting.

Method and apparatus for testing a directional acoustic device such as a directional hearing aid having level-dependent non-linear circuitry, in which two or more speakers are placed at desired positions relative to the hearing aid, e.g. in front and behind the hearing aid. The speakers are excited simultaneously with broadband excitation signals formed from components which are orthogonal to each other, e.g. sinusoids, where the bin frequencies of the Direct Fourier Transform (“DFT”) of one excitation signal are different from the bin frequencies of the other excitation signal. Thus, the response to each excitation signal can easily be extracted without filtering, allowing the directional characteristics of the hearing aid to be evaluated.

The invention discloses an alkaline earth molybdate rare earth light conversion material and a preparation method thereof. The light conversion material has a composition general formula of (Sr1-xBax)2(Ca1.05-2yYbyLiy)MoO6, wherein x is greater than or equal to 0 and less than or equal to 1; and y is greater than or equal to 0.02 and less than or equal to 0.12. The preparation method of the fluorescent powder comprises the following steps of: accurately weighing raw materials according to the proportion of the general formula; fully grinding and uniformly mixing oxides or corresponding salts of elements in the composition general formula; sintering the mixture in air atmosphere at the temperature of between 500 and 700 DEG C for 10 to 14 hours, cooling and crushing the mixture; then sintering the mixture in the air atmosphere at the temperature of between 800 and 1,000 DEG C for 10 to 14 hours, cooling and uniformly grinding the mixture in an agate mortar; and finally sintering the mixture in the air atmosphere at the temperature of between 1,000 and 1,200 DEG C for 20 to 28 hours, cooling and uniformly grinding the mixture in the agate mortar so as to obtain the alkaline earth molybdate fluorescent powder. The rare earth light conversion material disclosed by the invention has the advantages of broadband excitation, strong near infrared emission and the like from an ultraviolet region to a visible region and can be used as the rare earth light conversion material for silicon-based solar cells.

The invention relates to a recursive filtering modulating method of a transient broadband excitation signal of parametric array sonar. The method comprises the following steps: performing recursive filtering for a signal to be processed through a recursive filtering device to obtain X(n+1); obtaining an envelope E(n+1); performing up-sampling for the envelope E(n+1) through an interpolation filter; performing double-sideband amplitude modulation together with a digital carrier signal; performing D / A conversion to obtain an analog signal, and thus obtaining the excitation signal of a parametric emitting system. The method applies to both parametric array sonar and an air acoustical parametric array system; the application scope of acoustical parametric array is widely expanded, and a predictable huge potential market value is brought.

The acquisition of multiple images at slightly different time shifts from the spin echo (or from TE=0 for gradient echo sequences), allows the separation of on-resonance spins from off-resonance spins by encoding this information in the received signal. The excitation pulse can be a standard broadband excitation that will excite all spins. The separation of on- and off-resonance spins is then performed on the received signal. The polar and equatorial lobes of a magnetic particle such as SPIO produce signals from excited water molecules near the particle which are frequency offset above and below the frequency of signals from water molecules unaffected by the particle.

The invention discloses a broadband Lamb wave excitation signal generator applied to structural health monitoring, comprising a computer bus interface module, a logic management module, a high-voltage broadband excitation signal output module, a DC / DC (Direct Current / Direct Current) power supply module and an output on-off control module, wherein a computer bus communication interface module is connected with a computer bus; the logic management module is connected with the computer bus interface module; the DC / DC power supply module is subjected to voltage conversion after receiving a bus low-voltage direct current power supply; the bus low-voltage direct current power supply directly provides low-voltage power supply to the high-voltage broadband excitation signal output module; and thehigh-voltage broadband excitation signal output module generates a high-voltage broadband excitation signal to drive a piezoelectric element to work. By using the invention, cost and power consumption of an integrated structural health monitoring integrated system based on the piezoelectric element and an active Lamb wave can be reduced, reliability and integration of software and hardware of theintegrated system can be improved, and the development of a portable structural health monitoring system and the realization of an aircraft carried structure health monitoring system can be promoted.

A full spectrum white light emitting device may include a broadband solid-state excitation source for generating broadband excitation light with a dominant wavelength from about 420 nm to about 480 nm and a full width at half maximum intensity greater than about 25 nm; and a narrowband red photoluminescence material with an emission peak wavelength from about 620 nm to about 640 nm and a full width at half maximum emission intensity of less than about 30 nm; where the device has an efficacy of at least 130 lm / W and generates white light with a CRI Ra≥90, and where over a wavelength range from about 430 nm to about 520 nm, a maximum percentage intensity deviation of the white light from the intensity of light of a black-body curve or CIE Standard Illuminant D of the same Correlated Color Temperature is less than about 50%.