342 results about "Nonlinear systems of equations" patented technology

The invention provides an oil reservoir numerical simulation method and an oil reservoir numerical simulation device based on downhole flow control equipment. The oil reservoir numerical simulation method comprises the following steps: obtaining data of a production well, an injection well, an oil reservoir and flow control equipment; determining dynamic parameters and static parameters of each well, the oil reservoir and the flow control equipment; establishing a multi-well-section model according to the well body structure of each wheel and the flow control equipment; establishing an oil reservoir seepage model according to oil reservoir characteristics and fluid properties, wherein the oil reservoir seepage model comprises an oil-gas-water three-phase seepage equation, an outer boundarycondition and a restraint condition; coupling the multi-well-section model with the oil reservoir seepage model to generate a numerical model; establishing a geological model according to the staticparameters of the oil reservoir, and carrying out initialization on the geological model according to a relationship of original formation pressure distribution or pressure and depth as well as rock and fluid properties; and establishing a nonlinear equation set with a sparsity coefficient matrix according to the numerical model and the initialized geological model, and solving the nonlinear equation set.

An improved transformer oil-paper insulation medium response equivalent circuit parameter identification method comprises the steps that a return voltage method is adopted to measure return voltage peak, peak time and return voltage initial slope of a transformer oil-paper insulation system in a field; an extension Debye model is adopted to simulate an equivalent circuit of the transformer oil-paper insulation system; characteristic quantities of the return voltage peak, peak time and return voltage initial slope are established to solve improved mathematical models of a medium response equivalent circuit parameters, wherein the equivalent models of n relaxed branch circuits have 2n+2 model parameters to be solved, and accordingly a corresponding number of nonlinear equation systems are needed to be established through multiple return voltage testing cycles for solution; the solution of the nonlinear equation systems is converted into solution of the optimization problem of an objective function minimum value, a PSO mixed bacteria foraging optimization algorithm is adopted to identify the equivalent circuit parameters and calculate a return voltage curve, the return voltage curve is compared with a return voltage measurement curve to find that the main time constants of the two curves are identical, and the oil-paper insulation state of a transformer can be accurately judged.

A method for measuring the space position and attitude of a target is characterized by use of said present invented large-size ball-rod instrument to measure distances, and includes such steps as measuring the distances from three fixed points on the rigid body moving in space to the three fixed point in a fixed coordinate system to obtian 9 central distances, reading them from the display of said ball-rod instrument or computer, listing 9 non-linear equations, and analyzing them to obtain the space position and attitude of said rigid body. Its advantages are simple method, low cost and high precision.

The invention relates to an initial value correcting method for space target track improvement, which relates to the space technical field. In the invention, a nonlinear spreading model of prediction error coefficient related to along-track/normal direction prediction errors is established based on the prediction error spreading regulation of a space target track; nonlinear equation sets related to the prediction error coefficient of the along-track and normal direction prediction errors are respectively established based on multiple sets of observation datum acquired in different times; the evaluation to the along-track and normal direction prediction error coefficient is completed by fitting the along-track and normal direction errors; and based on the relationship between the prediction error coefficient and the track initial value error, the track initial value correcting amount is acquired, thus realizing the correction to the track initial value. Through repeated iteration, the accuracy of the track improvement initial value is improved; the track improvement process is promoted to be reliable; and the convergence is rapid.