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.

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 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 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 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.