364 results about "Reverse time" patented technology

A system and process for generating, and then rendering and displaying, an interactive viewpoint video in which a user can watch a dynamic scene while manipulating (freezing, slowing down, or reversing) time and changing the viewpoint at will. In general, the interactive viewpoint video is generated using a small number of cameras to capture multiple video streams. A multi-view 3D reconstruction and matting technique is employed to create a layered representation of the video frames that enables both efficient compression and interactive playback of the captured dynamic scene, while at the same time allowing for real-time rendering.

A method of prestack reverse-time migration of seismic data that yields significant gains in computer storage and memory bandwidth efficiency is disclosed. The values only of the source wave incident on the boundaries of a simulation domain are saved, rather than all of the values of the wavefield throughout the entire simulation domain. This data allows an accurate and robust approximation of the forward propagated source wave for all finite-difference approximation orders of the acoustic wave equation. The method reduces the amount of data storage required by an order of magnitude and overcomes the present challenge of requiring special large memory hardware while allowing for the implementation of 3D prestack reverse-time migration on off-the-shelf platforms.

Method for converting seismic data to obtain a subsurface model of, for example, bulk modulus or density. The gradient of an objective function is computed (103) using the seismic data (101) and a background subsurface medium model (102). The source and receiver illuminations are computed in the background model (104). The seismic resolution volume is computed using the velocities of the background model (105). The gradient is converted into the difference subsurface model parameters (106) using the source and receiver illumination, seismic resolution volume, and the background subsurface model. These same factors may be used to compensate seismic data migrated by reverse time migration, which can then be related to a subsurface bulk modulus model. For iterative inversion, the difference subsurface model parameters (106) are used as preconditioned gradients (107).

A communication channel is controlled so as to dynamically accommodate network client requests for access thereto. The communication channel may be supported on a wireless link, such as a spread spectrum wireless link, and client requests for access thereto may be dynamically accommodated by allocating time slots for client transmissions on the wireless link. Providing a quiet time slot within which clients may request access to the communication channel may accommodate various client requests for access to the communication channel. These quiet slots may exist with other forward and reverse time slots which are superimposed on the communication channel, each forward and reverse time slot including one or more data frames. The forward and reverse time slots are preferably fixed, but negotiable, time periods. Each of the data frames may include a plurality of data packets, each of the data packets being variable in length. Preferably, each of the data packets includes error correction coding information as well as information which may be used to synchronize pseudo-random number generators of a transmitter and a receiver operating according to the communication protocol. Each of the data frames may further include link identification information that uniquely identifies a wireless link supporting the communication protocol.

The invention discloses an elastic reverse time migration imaging method by combining seismic multi-component and belongs to the field of exploration geophysics. The method comprises the following steps: directly inputting seismic multi-component data; without performing the wave field separation on the input data, extrapolating forwards at inverse time based on an elastic wave equation; building an underground elastic vector seismic wave field by combining with multi-component; acquiring four elastic wave imaging results having specific physical significance, such as longitudinal wave, transverse wave, transition longitudinal wave and transition transverse wave, by applying an elastic wave cross-correlation imaging condition of lighting compensation; and suppressing the low wave number noise in the elastic reverse time migration by performing low-pass angle filtering, thereby acquiring an imaging result of final elastic wave migration. By directly inputting the seismic multi-component data and building the underground elastic vector seismic wave field by combining with multi-component, the method can be used for accurately imaging for complex earth medium.

Images of a subsurface region may be generated in conjunction with reverse time migration with reduced or no backscattering noise. Two or more wavefields may be decomposed to produce two or more corresponding decomposed wavefields. The two or more decomposed wavefields may include a source wavefield and a receiver wavefield. Directivity of the two or more decomposed wavefields may be determined to produce corresponding direction-dependent components of the two or more decomposed wavefields. One or more of the direction-dependent components of one or more decomposed source wavefields may be cross-correlated with one or more of the direction-dependent components of one or more corresponding decomposed receiver wavefields. An image of the subsurface region may be generated based on the cross-correlation.

A vehicle engine is coupled to a driving system that includes a torque converter and an automatic transmission. An ECU sets a target value of an opening degree of a throttle valve based on a depression degree of an acceleration pedal. The ECU changes the throttle opening degree at a predetermined gradual change speed such that the throttle opening degree reaches the set target value. The ECU limits the gradual change speed of the throttle opening degree for a predetermined period such that a changing speed of the engine speed is suppressed at a reverse time when a direction of torque transmitted between the driving system and the engine is reversed. As a result, shock produced when the direction of torque between the driving system and the engine is switched is suppressed.

An analog physiologic signal, e.g., the cardiac EGM, sensed by an IMD is filtered with a high pass filter (HPF), the cut-off frequency of the HPF being within a predetermined frequency bandwidth, wherein a low-band portion of the predetermined frequency bandwidth is attenuated in the filtered physiologic signal. The filtered physiologic signal is digitized in real time order, and the digital data set is filtered in reverse time order employing a digital IIR filter having characteristics substantially matching the cut-off frequency and filter characteristics of the HPF. When the system is implemented within an IMD, the filtered digital data set is compressed by lossy compression algorithm, and the compressed data set is filtered in reverse time order. In certain embodiments, the filtered digital data set is uplink telemetry transmitted to an external medical device, and the uplink telemetered data set is filtered in reverse time order employing a digital backward IIR filter resident in the external medical device.

The invention relates to a reverse time migration imaging method and a device. The reverse time migration imaging method comprises the steps of obtaining focus wave field information and detection point wave field information, detaching a focus wave field into a focus upper wave field and a focus lower wave field and detaching a detection point wave field into a detection point upper wave field and a detection point lower wave field according to the obtained focus wave field information and the obtained detection point wave field information, carrying out reverse time migration imaging process on the focus wave field and the detection point wave field which are detached, and then a reverse time migration imaging section is obtained. According to the reverse time migration imaging method and the device, low frequency noise produced in a reverse time migration process is eliminated, amplitude preservation performance is high, and good parallel characteristics of interior wave field calculation are maintained. The reverse time migration imaging method and the device are especially suitable for being used on a central processing unit (CPU) of a graphics processor or on a CPU heterogeneous platform. Calculating efficiency of reverse time migration is greatly improved.

The invention belongs to the field of exploration earth physics and specifically relates to an elastic vector reverse time migration imaging method. According to the invention, multi-component seismic data is used as input, an elastic wave propagation operator is utilized to carry out wave field prolongation, an elastic vector seismic wave field is constructed; and a decoupling prolongation equation method is utilized to obtain longitudinal and transverse wave fields of decoupling; vector points of the longitudinal and transverse wave fields with seismic source illumination compensation are utilized to construct elastic wave cross-correlation imaging conditions, and a multi-component seismic data elastic vector reverse time migration imaging result is obtained; and low-frequency noise suppression is carried out on the imaging result, and a final elastic vector reverse time migration imaging result is obtained. The elastic vector reverse time migration imaging method solves the scalar imaging problem of the longitudinal and transverse wave fields, and the imaging precision of elastic reverse time migration under a complex construction is improved.

When a reverse reproduction is instructed in an image reproducing apparatus (1), reproduced image data per picture generated by an MPEG video decoder (5) in a time series manner are inputted to an MPEG video encoder (6) so as to be recoded to I picture alone or B picture combined with I picture. An MPEG video decoder 7 reads out this recoded data sequence in a reverse time-series manner and decodes it successively, and displays a smooth reverse reproduced image. As the case may be, a data amount reducing circuit which reduces resolution and a data amount restoring circuit which restores the resolution are inserted therebetween. The reverse reproduction which is superior in ease of operation, cost merit, implemented area and so forth is realized.

The invention relates to one time simultaneous method and system for multi-point visual point, which comprises the following steps: a, using network time agreement to process all device simultaneous operations; b, separately starting one collection program on collectors for each camera; c, visual collection program monitors control order from servo; d, the servo detects local network maximum reverse time; e, the servo adds current system time and the maximum reverse time as pre-set collection time sent to each collection program; f, collection program compares the current system time and pre-set collection time, if it supers then starting visual data collection.

A method for finite impulse response (FIR) digital filtering is provided that includes generating a frequency domain sample block from an input sample block of length L, adding the computed frequency domain sample block to a reverse time-ordered set of previously generated frequency domain sample blocks as a newest frequency domain sample block, computing a spectral multiplication of each of K newest frequency domain sample blocks in the reverse time-ordered set with a corresponding frequency domain filter block in a time-ordered set of K frequency domain filter blocks of a FIR filter, adding the K results of the K spectral multiplications to generate an output spectral block, inverse transforming the output spectral block to generate a time domain output block, and outputting L filtered output samples from the time domain output block.

A preserved-amplitude RTM-based FWI method is used to obtain an image of an explored subsurface formation. Model data corresponding to detected data is generated using a velocity model of the formation. Residuals representing differences between the modeled data and the detected data are back-propagated to then update the velocity model a local optimization based on a deconvolution formula employing a backward propagating wavefield and a forward propagating wavefield. Geophysical features of the formation are imaged based on the updated velocity model.

The invention discloses a multi-component seismic data least squares reverse time migration imaging method and system. The method conducts modification on the basis of the elastic wave reverse time migration method, directly with the multi-component data as input, under the framework of inversion, employs different wave-field propagators and new imaging conditions at different steps of migration so as to achieve multi-component seismic data migration imaging based on inversion. According to the invention, the thought of inversion is introduced to elastic wave reverse time migration, compared with regular elastic wave reverse time migration, a prestack depth migration profile having high precision, high resolution, high signal to noise ratio, and amplitude preservation can be acquired. The method can effectively overcome lineups destructive interference caused by transverse wave polarity-reversal, and can effectively eliminate migration illusion caused by crosstalk among longitudinal and transverse waves while longitudinal and transverse wave vector characteristics, amplitude and phase characteristics are maintained in entirety. The method increases imaging precision, is applicable to multi-component seismic data migration of all kinds of complex medium models, has clear imaging profiles, and is easy for later-stage geology interpretation.

Method for optimal stacking of seismic images to remove noise and enhance signals in seismic images (101) outputted from a Reverse Time Migration (RTM) imaging process. Dip information is calculated (102) and then sorted by image point (104), for each seismic image to be stacked. A dominant dip and azimuth is determined at each image point (106), and only those events are stacked (107). If the image is still noisy or lacking in detail (108), the process may be iterated (109) to improve the selection of most likely dip and azimuth.

The invention relates to an anisotropic reverse time migration method for a quasi-P wave equation in a transverse isotropy with a vertical axis of symmetry (VTI) medium. The method comprises the following steps of: (1) performing discrete differentiation on a first-order quasi-P wave equation in a two-dimensional VTI medium and a perfect matched layer (PML) absorption layer boundary equation by adopting staggered meshes to obtain high-order difference formats of forward continuation and reverse continuation of the two equations; (2) performing numeric calculation to obtain a forwards-continued wave field of a shot point and a reverse time continued wave field of a receiver point, and performing normalized correlation operation on the two wave fields to obtain a migration imaging result of each imaging point in a model; and (3) extracting common imaging point gathers from migration results to obtain a final migration profile. By the method, a problem about the migration imaging of intensive transverse speed variation and a high dip angle stratum can be solved; and the influence of anisotropy of the medium is also taken into account, and the good imaging effect of longitudinal wave data acquired from an anisotropic region can be achieved by an anisotropy-theory-based migration method.

Provided is seismic imaging, particularly, a time-domain reverse-time migration technique for generating a real subsurface image from modeling parameters calculated through waveform inversion, etc. A reverse-time migration apparatus according to an example includes a source estimator configured to estimate sources by obtaining transmission waveforms from data measured by a plurality of receivers, through waveform inversion, and a migration unit configured to receive information about the estimated sources, and to perform reverse-time migration in the time domain. The source estimator estimates sources, by solving first-order matrix equation including a Toeplitz matrix composed of autocorrelation values of the Green's function, and a cross-correlation matrix of measured data and the Green's function, through Levinson Recursion. In more detail, the migration unit includes a back-propagation unit configured to back-propagate the measured data; a virtual source estimator configured to estimate virtual sources from the sources estimated by the source estimator; and a convolution unit that configured to convolve the back-propagated data with the virtual sources and output the results of the convolution.

The invention discloses an elastic wave full-waveform inversion method and apparatus. The method comprise the steps of establishing a convolution-type objective functional according to analog data and observation data; through adoption of an adjoint method based on the Lagrange theory, determining an adjoint equation of a time domain first order rate-stress elastic wave equation, adjoint epicenter items, a gradient expression of a convolution-type objective functional with regard to model parameters; determining a forward-propagating source wavefield according to the time domain first order rate-stress elastic wave equation; determining reverse-time extrapolation accompanying wavefield according to the adjoint equation and the adjoint focus items; determining the gradient of the convolution-type objective functional with regard to the model parameters according to the forward-propagating epicenter wavefield, the reverse-time extrapolation accompanying wavefield and the gradient expression; and carrying out multi-scale full-waveform inversion through utilization of low pass filtering characteristics of the convolution-type objective functional. According to the invention, influences by imprecise estimation of wavelets on inversion results can be eliminated, and problems that wavelets are difficult to accurately extract in practical data are effectively solved.

The invention discloses a method for sub-synchronous current calculation and sub-synchronous over-current and divergent protection of a generator. The method comprises the following steps of: acquiring the three-phase current signals of the generator, converting positive and negative sequence components of various modal sub-synchronous currents of the current into equivalent power-frequency negative sequence currents via the following formula, substituting the results into the original power-frequency negative sequence over-current protection criteria of the generator and then making fixed time-lag and reverse time-lag protection judgments; and judging if the equivalent power-frequency negative sequence over-current increases continuously and forming an divergent protection criteria. When the method is used, multi-modal sub-synchronous currents in the current of the generator armature can be detected, and the over-current protection and divergent protection of the sub-synchronous currents can be realized. Particularly, many sets of signals with sub-synchronous modal frequencies are separated by low-pass filtering and bandpass filtering; the sub-synchronous modal frequencies can be obtained by zero crossing point algorithm, and the amplitude sequence and phasor of the modal signals are obtained by Fourier calculation. The method can be applied in the original power-frequency negative sequence current protection of the generator, the formats and constant values of the protection criteria are unchanged.

Computing device and method for processing seismic traces to produce an image of a subsurface area. The method includes receiving a series of seismic traces related to the subsurface area and recorded by one or more seismic receivers, wherein the one or more seismic sources are originally generated by a source; applying a phase encoding function to the series of seismic traces, at least a portion of said seismic traces comprise signals reflected by geological interfaces of the subsurface area; applying a 3 dimensional (3D) harmonic-source reverse time migration of the series of seismic traces encoded with the phase encoding function; computing a forward wavefield by solving a first wave equation; computing a backward wavefield by solving a second wave equation; and cross-correlating the forward wavefield with the backward wavefield to generate an image of the subsurface.

A time-optimal trajectory generation method, for a robotic manipulator having a transport path with at least one path segment, comprising generating a forward time-optimal trajectory of the manipulator along the at least one path segment from a start point of the at least one path segment towards an end point of the at least one path segment, generating a reverse time-optimal trajectory of the manipulator along the at least one path segment from the end point towards the start point of the at least one path segment, and combining the time-optimal forward and reverse trajectories to obtain a complete time-optimal trajectory, where the forward and reverse trajectories of the at least one path segment are blended together with a smoothing bridge joining the time-optimal forward and reverse trajectories in a position-velocity reference frame with substantially no discontinuity between the time-optimal forward and reverse trajectories.

The invention relates to a controllable loading spectrum hydraulic loading method and a loading device therefore. The loading device comprises a loading cylinder, which is provided with a first oil chamber and a second oil chamber, with hydraulic fluid ports of the first oil chamber and the second oil chamber being connected to an oil pump and an oil tank respectively through a three-position four-way reversing valve; an accumulator is disposed between the three-position four-way reversing valve and the oil pump; a loading piston rod is provided with a force transducer; and the loading devicealso comprises a microcomputer control system for controlling the reversing of the three-position four-way reversing valve. Signals of the force transducer are output to the control system. The method comprises the steps of inputting the to-be-loaded loading spectrum in the microcomputer control system during the loading, controlling the three-position four-way reversing valve to reverse through the microcomputer control system, for acquiring the required loading on the loading piston rod of a loading piston, detecting the loading on the loading piston rod through the force transducer and transmitting a detection result to a microcomputer loading system for comparison, determining whether the loading on the loading piston rod meets the requirement, and adjusting a working position and reversing time of the three-position four-way reversing valve according to a comparison result.

The invention provides an elastic migration seismic wave field construction method and an elastic migration seismic wave field construction device. The method includes computing a finite difference coefficient of extended compact staggered grids according to an elastic wave velocity stress equation; computing a finite difference operator matrix of the extended compact staggered grids; constructing forward direction extrapolation operator of a seismic source wave field, and a reverse-time extrapolation operator of a detection wave field; achieving forward direction extrapolation of a seismic wave field to obtain the seismic source wave field according to the forward direction extrapolation operator of the seismic source wave field, a preset medium model and a preset seismic source function; and achieving reverse-time extrapolation of the seismic wave field to obtain the detection wave field according to the reverse-time extrapolation operator of the detection wave field, a preset medium model and preset multi-component seismic data. Compared with an existing method for constructing an elastic deflection seismic wave field by utilization of a conventional finite difference method and a compact difference method, the number of difference base frame grid points is reduced under the condition of same difference orders, the construction precision of a complex medium wave field can be effectively improved, and therefore the imaging precision of reverse-time migration is improved.

The present invention provides a traffic accident detection device of detecting traffic accident that estimates a precise speed variation for a vehicle, and detects dangerous events similar to traffic accidents. A time series estimation unit (202) chronologically estimates a speed from a detected speed of a vehicle that a sensor unit (102) has detected, and acquires a first estimated value; and a reverse time series estimation unit (204) reverse chronologically estimates a speed from the detected speed, and acquires a second estimated value. An integration estimation unit (206) estimates the speed and the speed shift of the vehicle by defining the first estimated value as an integrated estimated value until a time when the distance between the first estimated value and the second estimated value is at maximum, and defining the second estimated value as the integrated estimated value at the time the distance is at maximum and thereafter.

The invention relates to an earthquake multiple migration method. According to the invention, the improvement is carried out on the basis of a reverse time migration method and multiples are fused into the reverse time migration process, so that the multiples are homed to a correct position under the ground. The multiple migration method disclosed by the invention is mainly divided into the following two steps of: a first step of obtaining the multiples by utilizing known methods for forecasting the multiples; and a second step of carrying out pre-salt depth domain imaging by utilizing the reverse time migration method. According to the invention, multiple information is utilized; the multiples are fused into the reverse time migration process; earthquake record wave fields of primaries and the multiples are utilized to carry out imaging. Compared with the prior art, the method disclosed by the invention has the advantages that the multiple pre-salt imaging can be implemented; the underground illumination level which has a larger range and is more balanced is achieved; and the resolution ratio of the pre-salt imaging is greatly improved. The earthquake multiple migration method can be widely used in the field of oil-gas exploration and particularly has a more obvious effect on the imaging of a pre-salt structure.

When a reverse reproduction is instructed, an MPEG video stream is once decoded and is again recoded by an MPEG video encoder so as to generate a recoded data sequence which will be overwritten on a storage area in a hard disk. An MPEG video decoder reads out this recoded data sequence in a reverse time-series manner and decodes it successively, and then converts it to a video signal so as to be outputted to a display.

The invention discloses a multi GPU calculation based reverse time migration imaging method of a 3D TTI medium. According to the method, a stable second-order coupling equation set serves as a calculation model, finite SV wave components are given to enhance the wave field spreading stability, an anisotropy parameter matching method is used to suppress interference of pseudo-transverse waves, uniform anisotropy boundaries corresponding to a random speed boundary and other parameters are introduced, storage of large amount of wave field data and frequency disk reading and writing are avoided, and a GPU-based CUDA platform is used to realize high-performance parallel calculation. According to the invention, a second-order coupling quasi-acoustic equipment in the TTI medium is solved in a difference method on the basis of multi-GPU parallel calculation technology, wave field spreading is stable, pseudo-transverse waves are suppressed effectively, application of the random boundary reduces wave field storage and disk reading and writing, a multi-asynchronous-flow high parallel strategy of multi GPU calculation is used, the calculation efficiency is improved obviously, and the imaging method meets requirements for industrialization of anisotropy reverse time migration.

The invention discloses a pre-stack reverse time migration seismic data processing method by an integral method. According to the method, an integral pre-stack reverse time migration calculation method and data access characteristics are pre-analyzed, and a MapReduce framework is adopted during data management and access; in the specific migration calculation, CUDA programming is adopted to realize cooperative acceleration of CPU / GPU. The method specifically comprises the steps of seismic data preparation, input data division, migration task operation, Reduce operation starting for combining temporary imaging results in all node distribution type file systems, and final imaging result output. The invention further discloses a system for processing the pre-stack reverse time migration seismic data by the integral method. Compared with a conventional pre-stack reverse time migration method based on a CPU cluster, the method provided by the invention is clear in imaging, and the mass data can be more conveniently processed; the calculation efficiency is improved by 15 times, and the processing efficiency is greatly improved.

The invention discloses a full waveform joint inversion method for improving high steep structure velocity inversion efficiency, and belongs to the petroleum geophysical exploration field. The method comprises the steps: establishing an observation system by inputting the initial velocity field, the shot record and the focus wavelet; utilizing traditional reverse time migration to obtain the imaging result which is taken as a reflection coefficient model, and applying linear forward modeling and linear wave field back propagation; calculating the gradient directions of two prism waveforms and adding the gradient directions together to calculate the inverse gradient direction of the prism waveform, using the linear search method or a parabolic fitting method to calculate the updated step, and using the calculated gradient direction and step to update the velocity; using the conventional full waveform inversion method to update the velocity again, and determining whether or not to satisfy the error condition; if not, using the updated velocity as the input velocity, and updating the velocity again; and if so, outputting the inversion result. The full waveform joint inversion method for improving high steep structure velocity inversion efficiency reduces the dependency about whether the high steep structure information is missing in the initial model, and improves the inversion accuracy and efficiency for the high steep structure.