31 results about "Scattering attenuation" patented technology

Methods for characterizing an inspected object on the basis of attenuation determined from pair-wise illuminated voxels. A beam of penetrating radiation characterized by a propagation direction and an energy distribution is scanned across an object, while scatter detectors with collimated fields-of-view detect radiation scattered by each voxel of the inspected object that is intercepted by the incident beam of penetrating radiation. By calculating the attenuation of penetrating radiation between pairs of voxels of incidence of the incident beam, a tomographic image is obtained characterizing the three-dimensional distribution of attenuation in the object of one or more energies of penetrating radiation, and thus of various material characteristics.

A system and methods for characterizing an inspected object on the basis of attenuation between identified regions of scattering and a plurality of detectors. An incident beam of substantially monochromatic penetrating radiation is generated by a source, which may be a radioactive source. The incident beam is characterized by a propagation axis and a source energy. Radiation scattered by the object is detected by means of a plurality of detector elements disposed about the beam of penetrating radiation, each detector element generating a detector signal characterizing a detected energy of scattered radiation. The detector signal provides for determining a displacement for each scattering point of the object relative to a fiducial position on the propagation axis of the incident beam, based upon the detected energy of the scattered radiation. By calculating the attenuation of penetrating radiation between pairs of scattering voxels, a tomographic image is obtained characterizing the three-dimensional distribution of attenuation in the object of one or more energies of penetrating radiation, and thus of material characteristics.

An energy degrading device for attenuating energy of a particle beam with reduced emittance growth. An energy degrader comprises an emittance control material that can preferentially scatter the beam particles that is incident on a surface with a shallow angle. In one approach, the energy degrader may include alternating layers of a low-Z and a high-Z material, wherein the low Z material serves to attenuate energy of the beam particles by virtue of scattering and the high Z material serves to suppress the emittance increase by scattering back the beam particles toward the beam axis. In another approach, the energy degrader may be composed of carbon nanotubes or a material with oriented crystalline structure that is substantially orientated in the incident direction of the particle beam. The carbon nanotubes may serve to preferentially scatter beam particles towards the central beam axis as well as attenuate energy thereof.

The invention relates to a metal anti-fake identification method based on an ultrasonic backscattering attenuation coefficient spectrum. The fake identification on a metal material is completed through five steps of pre-treating a reference sample, acquiring a time-domain signal, calculating the attenuation coefficient spectrum of the reference sample, calculating self-relevance coefficients of the attenuation coefficient spectrum in the reference sample, and calculating relevant coefficients between the sample to be tested and the attenuation coefficient spectrum of the reference sample. By adopting the metal anti-fake identification method, a metal product does not need to be damaged and is not damaged in the identification process, so that non-destructive identification is achieved; in addition, compared with a conventional physical and chemical identification method, the result that whether the metal is true or fake can be obtained through independent identification, and moreover the identification result is accurate and reasonable, the identification method is relatively simple, the cost is low, the identification speed is fast, on-line identification is easy to achieve, and popularization and application are facilitated.

The invention provides an underwater image quality evaluating and measuring method based on power spectrum description. As for an underwater image I, the image quality of I is set as PSVIQE={C,Q}, wherein C is a factor describing underwater imaging environments, and Q is a quality measuring value of the underwater image; C is used for distinguishing the underwater environments where the underwater image is located, wherein the larger C is, the better water transparency is, clear imaging is facilitated, and the smaller C is, the higher absorption and scattering attenuation of water are; Q is used for measuring the clarity degree of the underwater image; if Q is larger, it is shown that the image comprises a target and is relatively clear, and if Q is smaller, it is shown that the underwater image does not comprise the target or is relatively blurred; an average block definition and image quality measuring method is adopted for Q, global contrast is selected in the method, quality measurement is conducted on the basis of partial definition, and a result of image edge detection is used as the basis for judging whether the target exists or not. The underwater image quality evaluating and measuring method is high in universality, combines imaging environment description and image quality measurement, and can be used for evaluating the value of the target image for observers in a severe imaging environment more effectively.

The invention provides a phased array ultrasonic evaluation method of crystal grain size, the method includes: using the primary bottom echo and the secondary bottom echo to obtain the experimental longitudinal wave scattering attenuation coefficient; deriving the linear phased array from the Huygens principle The probe radiates the sound field, receives the average sound pressure through the probe, defines the diffraction correction coefficient of the linear phased array probe and calculates the final diffraction correction coefficient; according to the Weaver ultrasonic scattering model, the theoretical relationship between the grain size and the longitudinal wave scattering attenuation coefficient is obtained, based on the nonlinear minimum The square method uses polynomial fitting to obtain the proxy model of the grain size and the theoretical longitudinal wave scattering attenuation coefficient; the experimental longitudinal wave scattering attenuation after removing the diffraction loss is substituted into the proxy model to invert the grain size value. The invention eliminates diffraction loss interference, fuses multi-angle sound beam information, and greatly reduces relative error compared with traditional methods, and provides a feasible and reliable means for estimating the grain size of polycrystalline materials.

The invention discloses an on-line measurement method for frequency-sweeping ultrasonic focusing type sediment particle size distribution. The present invention builds a set of measuring devices with a focused ultrasonic probe as the core, and at the same time uses the screening method and microscope method to configure sediment samples of different particle sizes; debugs the measuring system, and starts the measuring device after it is accurate; changes the ultrasonic wave Frequency, a series of experiments with sediment particle size as a variable were carried out at different ultrasonic frequencies to obtain the data of the received waveform; phase space segmentation and symbol dynamic filtering based on the Hilbert transform were performed on the collected signals to obtain the same Measurement of parameter values ​​related to particle size; data fitting is performed on the scatter diagrams of measurement and sediment particle size at different frequencies to obtain a sediment particle size measurement model. The invention can effectively reduce the scattering attenuation in the propagation process, increase the acceptable sound energy at the receiving transducer, improve the signal-to-noise ratio, and the sensitivity and measurement accuracy of the entire measurement system.

The invention provides a method and device for quantitatively evaluating the stratum heterogeneity, and belongs to the field of oil and gas resource exploration. The method comprises the steps that waveform data in a depth interval is obtained; depth correction is conducted, a waveform coherent stacking method is utilized for treatment, and the longitudinal wave speed and transverse wave speed ofa stratum are obtained; a scattering attenuation quality factor and center frequency of the waveform data are calculated; the average longitudinal wave speed, the transverse wave speed and the disturbance quantity of the transverse wave speed are obtained; a random medium model is built; different correlation distances are selected, corresponding characteristics of a sound field of the random medium model are simulated by means of a finite-difference time-domain value, and scattering attenuation quality factors of the random medium model under the different correlation distances are calculated; a scattering attenuation quality factor chart of the random medium model is built; a measured data scattering attenuation quality factor is compared with the scattering attenuation quality factor chart, and the correlation distance of the depth interval is obtained. Accordingly, by adopting the correlation distance of rock, the heterogeneity of the rock is quantitatively evaluated.

The invention relates to a high-pressure medium seismic wave propagation simulation method, comprising the following steps: 1) establishing a novel acoustic elasticity formula combined with pore structural parameters; 2) calculating equivalent elastic moduli and elastic wave velocities in different pressure states by utilizing the novel acoustic elasticity formula; 3) extracting structured data, namely autocorrelation length, among particles inside rocks; 4) specific to each pressure state, taking the equivalent elastic moduli obtained by the step 2) as background values of rock medium elasticmoduli respectively, and according the autocorrelation length extracted in the step 3), by combining an autocorrelation function, adding elastic modulus disturbance in the background values, and building a rock numerical value model in each pressure state; and 5) performing finite element seismic wave field simulation in each rock numerical value model, and extracting a scattering attenuation Qc-1 value of a reservoir specific to characteristics of a deep reservoir, wherein Qc-1 is a coda wave attenuation coefficient.

The invention discloses a rock scattering attenuation calculation method using multi-parameter integrated inversion; the method comprises the following steps: carrying out array acoustic logging in a depth section, thus obtaining dipole array waveform data in the depth section; calculating a power spectrum of each depth point actual measuring waveform; building inversion objective functions; using the least squares to obtain the scattering attenuation of each depth point; loop executing step 2 to step 4, thus finally obtaining the scattering attenuation curve of the depth section. The method can accurately parse the acoustic logging data and extract scattering attenuation of elastic waves, thus providing valuable stratum information; compared with the large scale seismic wave scattering attenuation, the acoustic logging calculated scattering attenuation can provide the underground rock small scale heterogeneity information.

The invention discloses a high-energy laser homogenizing cavity attenuator which comprises a front panel, a small-hole sample plate, an attenuation plate, an output panel and a plurality of scattering attenuation units. Each attenuation unit includes a large-angle sampling taper hole arranged on the small-hole sample plate, a homogenizing cavity and a light transmission channel which are arranged on the attenuation plate, and a homogenizing cavity and a laser output hole which are arranged on the output panel, wherein the light transmission channel is of a circular symmetric structure, which enables the angle characteristic of the attenuator to have circular symmetry. The attenuator has a multi-layer plate structure, which can effectively reduce the influence of high temperature generated due to long-time irradiation of high-energy laser on the front panel to a subsequent measurement unit. According to the attenuator of the invention, laser is output from the output hole after being homogenized for multiple times, substantial attenuation of the laser power density is achieved, and the attenuator has better attenuation angle characteristics.