55 results about "Linear term" patented technology

A method of obtaining a computed tomography image of an object includes determining linear terms and non-linear beam hardening terms in a pair of line integral equations for dual-energy projection data from inserting average and difference from average attenuation terms, obtaining an initial solution of the line integral equation by setting the non-linear beam hardening terms to zero, and iteratively solving the line integral equations to obtain one line integral equations for each basis material. Attenuation by the first basis material corresponds to a photoelectric attenuation process, and attenuation by the second basis material corresponds to a Compton attenuation process. The line integral equations can be inverted by an inverse Radon procedure such as filtered backprojection to give images of each basis material. The images of each basis material can then be optionally combined to give monochromatic images, density and effective atomic number images, or photoelectric and Compton processes images.

A connection admission control (CAC) technique for a telecommunications node approximates probability of loss using a log moment generating function and its two partial derivatives of workload on a queue over a time interval. The approximation uses four state variables, which depend on the log moment generating function and its two partial derivatives. The four state variables are: (1) Linear term in approximation to log loss ratio at a working point; (2) the argument of logarithmic term in approximation to log loss ratio at the working point; (3) a buffer limit used at the working point; and (4) a multiplier of imaginary traffic used at the working point. Advantageously, these state variables vary linearly with the traffic, so a new connection can simply add its contributions to them. The connection admission control (CAC) uses the state variables to produce the following three parameters: (1) an approximation q=z-log(c) to the logarithm of the probability of loss; (2) a buffer size limit B; and (3) a multiple m of imaginary traffic from a design mix. The traffic on all connections is admissable if four conditions are satisfied. The present invention applies, e.g., to a single queue and server, and can be generalized to multiple queues and servers.

A system and method of reconstructing an image through solution of a data fitting problem, wherein the data fitting problem is not susceptible to efficient solution as a whole, is disclosed, which may comprise gathering, via a computing device, k-space image data, selecting a data fitting problem solution algorithm for the k-space data, decomposing the data fitting problem solution into a plurality of sub-problem solutions each susceptible to efficient solution separately for the k-space data, obtaining, via the computing device, the plurality of sub-problem solutions for the k-space data, and reconstructing, via the computing device, the image based upon a weighted average of the plurality of sub-problem solutions for the k-space data. The image may be a magnetic resonance image. The data fitting problem may comprise a minimization of a plurality of linear terms of a least square data fitting solution. The image may comprise under-sampled k-space image data.

A system to compensate for luminance degradation of an emissive display is provided. As its primary components, the system includes a controller and a temperature sensor. The controller is coupled to the emissive display to provide a driving signal thereby controlling the display luminance. The temperature sensor is located proximate the emissive display and is in electrical communication with the controller. The controller receives a temperature signal from the temperature sensor and varies the luminance based on the temperature signal. As the temperature of the emissive display increases, the controller reduces the display luminance according to a transfer function. The transfer function may have a linear term and/or a non-linear term relating the operating luminance to the display temperature.

A method for identifying and modeling nonlinearities in communications channels, particularly optical communication channels. A channel in general is modeled as a summation of linear and non linear terms having memory. The terms are functions of the input to the channel with respect to time, such as a sequence of input bits to the channel. In one embodiment the most recent input bits are used to access a value in a look up table. The value accessed is compared to an actual value received from the channel. The difference between the value in the table and the actual channel value may be used to correct the value in the table. When the look up table and the channel converge the look up table contains a model of the channel with memory that can model nonlinearities. A nonlinear channel having memory may also be modeled in terms of Volterra Kernels.

An active medical device using non-linear filtering for the reconstruction of a surface electrocardiogram (ECG) from an endocardial electrogram (EGM) is disclosed. The device for the reconstruction of the surface ECG comprises: a plurality of inputs, receiving a corresponding plurality of EGM signals from endocardial or epicardial electrogram (x₁[n], x₂[n]) each collected on a respective EGM derivation of a plurality of EGM derivations, and at least one output delivering a reconstructed surface ECG electrocardiogram signal (y[n]), related to an ECG derivation, and a non-linear digital filter (12′, 12′, 14) with a transfer function that determines the reconstructed ECG signal based on said plurality of input EGM signals. The non-linear digital filter includes a Volterra filter type (12, 12′, 12″) whose transfer function includes a linear term (h1) and at least one quadratic (h2) and/or cubic (h3) term(s).

The invention discloses a method for using a polar region ice exploring radar to extract a polar region ice layer position. Two-dimensional Fourier transformation is performed on a radar echo signal propagating in a multilayered medium, and a two-dimensional frequency spectrum of the radar echo signal propagating in the multilayered medium is obtained; the two-dimensional frequency spectrum is multiplied by a reference phase factor, and a radar echo signal influenced by range migration is obtained; metric inverse Fourier transformation is used to perform range migration correction on the radar echo signal influenced by the range migration to converted to a range-Doppler domain, and radar echo signal with influence of a range migration factor linear term being eliminated is obtained; a secondary and tertiary range frequency compensation function and a reference function of azimuth direction compression are used to process the radar echo signal with influence of the range migration factor linear term being eliminated, and a fully compensated radar echo signal is obtained; and later azimuth direction Fourier inverse transformation is performed, a focused image is obtained, and by performing range coordinate contraction on the focused image, the position of a layer target detected by the polar region ice exploring radar is obtained.

The ECC circuit includes a Chien search unit configured to determine whether there is an error in each bit of a data sequence. The Chien search unit selects a coefficient of a nonlinear term from among terms of an error locator polynomial as a nonlinear coefficient, separates the error locator polynomial into a first location equation including only linear terms and a second location equation including only nonlinear terms, determines a third location equation by dividing the first location equation by the nonlinear coefficient, determines a fourth location equation by dividing the second location equation by the nonlinear coefficient, and determines whether there is an error for each of the bits by performing an XOR operation on a result of the third location equation using the substitution value and a result of the fourth location equation using an arbitrary element of the error locator polynomial as a substitution value.

The invention relates to sonar transmission means and in particular to transmission means for achieving omnidirectional acoustic transmission. The invention relates to a method for achieving omnidirectional transmission using of a towed linear antenna of length L greater than the wavelength λ of the signal transmitted. The antenna has a plurality of P projectors. The spacing between projectors is substantially less than λ/2. The method according to the invention includes applying, to each projector, a transmit signal coming from a common transmit signal. The common signal is assigned a delay, the expression for which follows a law containing a non-linear term as a function of the position of the projector in the antenna. Application of this law allows the angular aperture of the transmission pattern to be modulated. The invention makes it possible in particular to produce sonar detection systems comprising transmit and receive antennas having substantially identical diameters, which can be reeled onto the same winch without it being necessary to separate them.

The invention discloses a short-range wide-area SAR high-resolution imaging method based on a three-dimensional isometric circle model. Firstly, main linear RCM is removed by using LRWC at a referencepoint, thereby relieving range-azimuth coupling. Secondly, RCM linear terms of all azimuth zero point targets are removed through KT, and part of the range-azimuth coupling is relieved. Based on a processing result of Bulk RCMC, the new three-dimensional isometric circle model is provided; improved residual high-order RCMC of azimuth space variation is provided in range direction processing for processing residual high-order RCM of the azimuth space variation; and SRC is added in subsequent processing to complete the range direction processing. On the basis of the three-dimensional isometriccircle model, derived azimuth space variation slant range analysis formula and analysis formula for space variation of a spatial squint angle along with a ground distance are used for analyzing the influence of azimuth change characteristics of a Doppler phase on imaging, and removing a Doppler center frequency. The method has a better focusing effect in processing SAR echo data under a short-range wide-area and large-squint imaging condition.

The invention relates to a combustor structure optimization method based on a response surface method. The combustor structure optimization method comprises the following specific steps: (1) determining structural factors, required to be considered, of a combustor, and performing coding conversion on the structural factors; (2) determining a test scheme by adopting CCD (Central Composite Design) method; (3) completing a test according to the CCD-based test scheme; (4) establishing a response surface model, and analyzing a test result; (5) performing ridge analysis, and determining an optimized structure parameter combination. According to the combustor structure optimization method, the test scheme is determined by using the CCD method, and the test result is analyzed by virtue of response surface software, so that the linear term influence and the quadratic term influence on the combustion performance of the combustor caused by all the factors can be determined, the cross term influence of all the factors can also be determined, the optimized structure parameter combination is further determined by the ridge analysis, and a low-nitrogen combustion effect is achieved.

A transmitter includes a polar modulator that creates phase and amplitude signals which in turn drive a power amplifier. To compensate for AM to PM conversion of the amplitude signal into the amplified signal, a compensation signal is generated from the amplitude signal and combined with the phase signal such that when amplified, the compensation signal cancels the AM to PM conversion. The compensation signal may have an offset term, a linear term, a quadratic term, and a cubic term. A second embodiment comprises a technique by which AM to AM conversion may concurrently be addressed using a second compensation signal.

A delta-sigma fractional-N frequency synthesizer having a charge pump with error canceling circuitry eliminates a non-linear term from the charge pump transfer function. The charge pump includes a matched pair of charging current sources, each supplying a first current I_P1 to a common node, when enabled. The charge pump also includes a matched pair of discharging current sources, each sinking a second current I_N1 from the common node, when enabled. The error canceling circuitry includes a charging current source, which supplies a current equal to the second current I_N1 to the common node, when enabled. The error canceling circuitry also includes a discharging current source, which sinks a current equal to the first current I_P1 from the common node, when enabled. The charging and discharging current sources of the error canceling circuitry are both enabled when either one of the matched pairs of charging and discharging current sources is enabled.

The invention provides a speech presence probability calculation method, a speech presence probability calculation device and electronic equipment. A measurement parameter for a first channel signal signal-to-noise ratio and a measurement parameter for a signal power level difference between the first channel and a second channel are introduced in the speech presence probability calculation, the above measurement parameters are subjected to normalization and nonlinear transformation processing, a linear term and a product term of power series of the above parameters are used for fitting the speech presence probability, the computation burden for the speech presence probability can be reduced, the computation result is more robust to parameter fluctuation, and the method and the device can be widely applied to an application scene for each two-microphone speech enhancement system.

The invention discloses a rational approximate optimization method for an unsteady aerodynamic load of an aerodynamic servo elastic system. Two types of original data of an analysis structure are obtained through existing commercial engineering numerical calculation software. On the basis, an unsteady aerodynamic force rational approximate expression form recognized by modern engineering analysisis applied, and a two-stage alternating double-iteration numerical optimization algorithm of two variables including a linear term coefficient and a nonlinear term coefficient is established. Two-stage double optimization iteration is performed until an optimal coefficient in a high-precision rational approximate fitting formula is obtained. The prediction precision of the unsteady aerodynamic load process in modeling analysis of the aerodynamic servo elastic system of the airplane selected structure is improved, rational approximate fitting errors are greatly reduced, and therefore high-precision load process numerical values are provided for dynamic response, dynamic stability and active elastic control of the airplane aerodynamic servo elastic system.

The invention discloses a method for correcting gray distortion of a nuclear magnetic resonance image. The method comprises the following steps that: spherical-harmonic expansion is performed on a nonlinear gradient field so as to obtain a linear term and a higher-order nonlinear term; the heterogeneity of the gradient field can be obtained through conventional fast Fourier transform (FFT); a heterogeneous mapping relationship between the geometric position and brightness of the image is obtained; a weighted coefficient between the nonlinearity of the gradient field and the gray distortion of the image; and therefore, the correction of the gray distortion of the image can be accomplished. Compared with the prior art, the method for correcting the gray distortion of the nuclear magnetic resonance image of the invention can quickly realize the correction of the gray distortion of the nuclear magnetic resonance image, and therefore, imaging quality and the reliability of clinical diagnosis can be improved, and the method has important significance in the nuclear magnetic resonance imaging field.

A method and device for simulating microstructure evolution of a material based on solution in an exponential time-difference format. The method includes: establishing a reaction rate theory model for substance defects, wherein the model is expressed with equations that comprise linear terms having coefficients characterized with matrixes; and iteratively solving the equations by using an exponential time-difference format, wherein during the iterative solving, the linear terms with exponential powers of the matrixes as the coefficients are integrated. Since a rate theory is not limited by spatial-temporal scales, the advantages of the rate theory can be significantly reflected when the microstructure evolution is simulated under a high damage dose condition; and then, the equations are solved by using the exponential time-difference format, with a solved result better in accuracy and higher in precision.