263 results about "Transient analysis" patented technology

The specification discloses a downhole tool that determines hydraulic permeability of a downhole formation taking into account one or both of the dip angle of the borehole relative to the formation, and damage to the borehole wall and invasion of borehole fluid-collectively referred to as skin.

Methods and apparatuses for transient analyses of a circuit using a hierarchical approach. In one embodiment, the cells are grouped locally on the power supply network according to average power dissipation. A time varying current of each cell group is estimated using a probabilistic approach to represent the cell group so that the probability of a more severe waveform for the current of the cell group is under a certain level. For example, the cells in a group are partitioned as switching cells and non-switching cells using cell toggle rates for the determination of the time varying current. The circuit model of the power supply network includes the current sources according to the estimated time varying currents for the cell groups, the power supply wire resistance, the power supply to ground wire capacitance, well capacitance and the de-coupling capacitance from non-switching cells.

A method of dynamic durability analysis and fatigue area identification using modal techniques for a structure includes the steps of simulating a finite element model of the structure to determine modal stresses and modal displacements for an element of the structure and performing a modal transient analysis using the modal displacements. The method also includes the steps of determining a stress bound for the element from the modal stresses and modal transient analysis, determining if a stress bound for the element is greater than a predetermined value and identifying the element as a critical element if the stress bound for the element is greater than the predetermined value. The method further includes the steps of determining a stress time history for the critical element and using the stress time history to perform a fatigue analysis to identify an area of fatigue within the structure.

A method for controlling fluid injection parameters to improve well interactions and control hydrofracture geometries is provided. The method incorporates a systematic, transient analysis process for determining the formation effective displacement, stress and excess pore pressure field quantities at any depth within a stratified subterranean formation resulting from the subsurface injection of pressurized fluids.

Vascular conditions are detected non-invasively in the human body using a collection of acoustic information from small local regions of the vasculature. An array of accelerometers or other sensors are attached to the head or other points of interest of a patient and blood flow sounds are recorded. Vibration signatures of vessel structures such as branches, aneurysms, stenosis, etc. using random, periodic, band limited or transient analysis provides a library for further processing. The signature library is used to localize the origin of the recognized vascular feature, and the localized feature is presented to the physician in a clinically relevant manner.

The invention discloses a transient analysis method under an integrated circuit power supply network full-parameter model. The method comprises the following steps: a determining step of determining the full-parameter model information of a to-be-analyzed integrated circuit power supply network; an establishing step of establishing a power supply network topological graph comprising a plurality of independent sub-circuits based on the full-parameter model information; and an analysis step of in parallel carrying out direct current working site analysis and transient analysis on each sub-circuit of the power supply topological graph to obtain the circuit node voltage distribution graph at each moment of each sub-circuit. As for a full-parameter circuit model, the invention establishes a linear system capable of adopting a symmetric matrix solver, and adopts a direct solver and an iterative solver in a hybrid manner according to the characteristics of problem solving. The method and system disclosed by the invention can be applied to carrying out fast and precise transient voltage drop analysis on the power supply network under the full-parameter model in formats such as an SPICE (Simulation Program with Integrated Circuit Emphasis) net-list form, especially on the aspect of memory consumption, and the system is improved to a great extent in comparison with the original emulator.

The invention provides an electrochemical noise method, apparatus and system for estimating parameters of interest related to corrosion rates of an electrically conductive article, the method comprising: placing a working electrode, a reference electrode, and a counter electrode in an environment of interest; measuring potential at open circuit between the working electrode and the reference electrode over time; placing the working electrode under a potentiostatic control; measuring current between the working electrode and the counter electrode for a predetermined period of time, the period of time of measurements may be extended to include a transient event; and estimating the corrosion rate.

A method for simulating large circuits in full-scale. To enhance the simulation efficiency, subcircuits are extracted from a circuit and thence a hierarchical structure is established using the extracted subcircuits. Subsequently, the circuit is partitioned and a current-voltage table for each subcircuit is dynamically generated. A transient analysis of the circuit is preformed at each incremental time step and a recursive latency check is preformed from the top to the bottom level of the hierarchical structure to determine the active part of the circuit. Using the current-voltage curves, a portion of the conductance matrix corresponding to the active part is rebuild at each incremental time step, which significantly reduces the simulation time.

The invention provides a time domain analysis method for a transient response of lossy nonuinform multi-conductor transmission lines and aims to solve the problem that the coupling among the lossy nonuniform multi-conductor transmission lines interferes with the computation in the field of integrity of electronic circuit signals. The method comprises the following steps of: performing differential dispersion on space differential operators in an electric wave equation; and integrating time differential operators in the electrical wave equation by a trapezoidal integration method to ensure that the oscillation, which is caused by a central difference method, of a computed result can be eliminated effectively, voltage and current transient response waveforms of any point on the transmissionlines can be acquired; and the transient analysis of the transmission lines in a longer time period is effective, the waveforms can be analyzed in a longer duration without large errors, and the coupled transmission lines are not needed to be decoupled when a model of the transmission lines is built. By the method, the computational load is reduced, and the simulation efficiency is improved. The method can be used for analyzing the transient response of the lossy nonuinform multi-conductor transmission lines.

The invention relates to a method for stimulating an electromagnetism transient of an electric system comprising multiple electric electronic switches and belongs to the technical field of electromagnetism transient analysis of electric systems. According to the method, models for on and off of electric electronic switches are provided by use of the constant impulse response principle. The method comprises the following steps: respectively building a general branch equivalent model and an electric electronic switch equivalent model, and respectively obtaining electromagnetism transient simulation results under various step lengths by virtue of a node voltage equation. The method can be used for solving the problem of state quantity jump numerical oscillation of multiple electric electronic switch models of the electric system. The method for stimulating the electromagnetism transient of the electric system comprising the multiple electric electronic switches can be used for providing a new means for modeling the electromagnetism transient switches of the electric system, and is especially applicable to electromagnetism transient simulation calculation for the electric system comprising multiple electric electronic switch devices such as a modular multilevel module and a high-voltage direct-current module.

A simulation template and method therefor is disclosed that modifies a SPICE netlist that describes a circuit in order to provide customized or pre-installed additional analysis. More specifically, a simulation template is an interactive command language (ICL) script that has embedded instructions telling a netlist where to insert information and which options are to be provided. It is used to expand SPICE beyond the traditional limitations of the basic alternating current (AC), direct current (DC), and transient analysis by allowing parameter variations and multiple simulations passes to be run under one analysis umbrella. Such additional analysis employing parameter variations and multiple analysis passes include sensitivity analysis, root means square (RSS) analysis, extreme value analysis (EVA) and worst case sensitivity (WCS), to name a few. The simulation template includes a routine to add to a netlist for altering circuit parameter values of the circuit design in a pre-determined manner, a routine to add to the netlist for performing simulations of the circuit design for respective altered circuit parameter values to arrive at respective selected vector measurements, and a routine to add to the netlist for manipulating at least one of the vector measurements in accordance with the pre-determined analysis.

The invention discloses a power system dynamic equivalence method suitable for electromagnetic transient analysis. The method comprises the following steps of: retaining a backbone network at the voltage level of 500 kV and above in a power system; classifying 500 kV-buses into two classes; and respectively decomposing and performing equivalence on first-class 500 kV-buses and second-class 500 kV-buses, wherein different equivalence models are adopted to the two classes of the 500 kV-buses. A dynamic simulation analysis result shows that dynamic characteristics before and after performing the equivalence on the power system by the equivalence method are basically consistent, thereby showing the feasibility and the effectiveness of the equivalence method.

The embodiment of the invention provides a phase component fault range finding method based on mu PMU distribution line parameter identification; the method mainly comprises the following steps: usingthe mu PMU on two ends of the line to gather the voltage current phasor data before and after the fault; carrying out Fourier decomposition for the extracted stable state voltage current so as to obtain the fundamental wave component of the phase value; using the fundamental wave components of the three-phase voltage currents on two ends of the line to determine the line parameters; using the phase components on two ends of the line after the fault to build a matrix equation, and combining the constrained condition and the line parameters so as to determine the unique fault distance. The method introduces the mu PMU to determine the line parameters in real time, thus reducing line parameter errors caused by field construction, line aging and weather factors, solving the range finding errors caused by non-synchronization of the information on two ends, preventing the complex circuit transient analysis, and reducing the computational complexity; the range finding method can use the dual-end impedance method to eliminate the range finding errors caused by transition impedance, and the range finding precision is not affected by the neutral point grounding mode.

A subband audio coder employs perfect/non-perfect reconstruction filters, predictive/non-predictive subband encoding, transient analysis, and psycho-acoustic/minimum mean-square-error (mmse) bit allocation over time, frequency and the multiple audio channels to encode/decode a data stream to generate high fidelity reconstructed audio. The audio coder windows the multi-channel audio signal such that the frame size, i.e. number of bytes, is constrained to lie in a desired range, and formats the encoded data so that the individual subframes can be played back as they are received thereby reducing latency. Furthermore, the audio coder processes the baseband portion (0-24 kHz) of the audio band-width for sampling frequencies of 48 kHz and higher with the same encoding/decoding algorithm so that audio coder architecture is future compatible.

The invention provides a detection method and device for pipeline leakage. The detection method comprises the following steps that 1, flow data and pressure data at the start position of a to-be-detected pipeline are obtained, and flow data and pressure data at the end position of the to-be-detected pipeline are obtained; and 2, according to the flow data and the pressure data at the start position of the to-be-detected pipeline and the flow data and the pressure data at the end position of the to-be-detected pipeline, a hydrodynamic transient model and a thermodynamic transient model of the to-be-detected pipeline are solved through the particle swarm optimization so as to obtain a result parameter, and the result parameter is used for determining whether the pipeline leakage occurs or not. According to the detection method, the particle swarm optimization is combined with hydrodynamics transient analysis and thermodynamic transient analysis, the transient models are solved through the particle swarm optimization so as to determine the running condition of the pipeline, and therefore the technical problem that an existing method is limited in application range and poor in leak detection accuracy is solved, and the technical effect of effectively improving the leakage detection accuracy is achieved.

The invention discloses a method for electric transmission line windage yaw transient analysis under action of moving thunderstorm wind. The method comprises the steps that the vertical wind speed is considered in simulation of a moving thunderstorm wind field and the spatial correlation and the pulsation effect are synchronously considered; when the wind load is determined, a transient wind attack angle and a corresponding divided conductor aerodynamic coefficient are introduced, and the wind speed and change of the direction are considered in a time domain; in the analysis process of a wind deflection angle, displacement, caused by the asymmetric load, in the direction of a line is considered, the largest wind deflection angle of part of the electric transmission line is calculated under the condition of the extreme wind load, design work of windproof measures of the electric transmission line is directed, and the power supply reliability of the electric transmission line is improved.

The invention relates to an electromagnetic transient simulation method containing a switching characteristic sub-network, and belongs to the technical field of electromagnetic transient analysis in electric power systems. According to the simulation method, a breaker and electronic power switching elements are designed into an independent switching sub-network; the network only comprises an electronic power sub-switch, the breaker and related elements (resistors, inductors, capacitors and the like); the network performs modeling through a rational polynomial approximation based exponential fitting method provided by the invention; and the rest of networks perform modeling by a conventional method (an implicit trapezoid method, a backward Euler method, a damping trapezoidal method or a modified combining form thereof). In offline/real-time calculation, only the switching sub-network performs iteration or interpolation calculation, and the rest of networks do not participate in iteration or interpolation. The switching sub-network adopts a high-order algorithm provided by the invention, so that numerical oscillation can be immunized; and meanwhile, the workload of model modification is relatively low, so that engineering promotion is facilitated.

The invention belongs to the electromagnetic transient analysis field in an electric power system, and particularly relates to a modeling method for a broadband equivalent model for performing analysis on a tower interlamination transient voltage of an ultra-high-voltage direct current converter valve. The modeling method specifically comprises the steps of taking a valve layer as a unit, and establishing a key component lumped parameter equivalent model in the valve layer and a valve layer terminal capacitor model; enabling the key component lumped parameter equivalent model in the valve layer and the valve layer terminal capacitor model to be connected according to an actual electrical connection condition of the valve tower to obtain the final the broadband equivalent model for performing transient voltage analysis on the tower interlamination of the ultra-high-voltage direct current converter valve. By considering the influence on the valve interlamination voltage distribution from the key component parameters in the valve and shielding cover stray capacitance parameters under a voltage effect, the integrated broadband equivalent circuit model is applicable to perform accurate and efficient analysis on the tower interlamination transient voltage of the ultra-high-voltage direct current converter valve under various kinds of voltages.

The invention discloses an electromagnetic transient analysis method for a large-capacity power-electron conversion system and belongs to the technical field of power-electron conversion and control. The method comprises the following steps: the large-capacity power-electron conversion system carries out one protection action; system parameters before and after protection action of the conversion system are collected to determine a safe working area of the conversion system; stray parameters of the conversion system are extracted to further determine a transient bus structure of the conversion system; a feedback control set value of a gate drive signal of a semiconductor switching device is determined according to the bus structure and the stray parameters; delay time of the conversion system is determined according to the feedback control set value of the gate drive signal of the semiconductor switching device; and at last the delay time of the safe working area of the system is determined. By the method, the existing device safe working area is extended to the system safe working area, the existing lumped parameter topological structure is expanded to a main circuit structure which considers stray parameters, and the existing signal pulse modulation algorithm is extended to main circuit pulse control strategies.

The present invention relates to an interpolation compensation current switch model based power electronic simulation method and belongs to the technical field of electromagnetic transient analysis of power systems. The method provided by the present invention is high in simulation precision, a switch model which still can ensure a node admittance matrix to be unchanged at a switching moment is provided, and a novel switch model based on an interpolation compensation current is designed. The model not only can improve the simulation precision of traditional ADC models, but also can be applied to system-level large step simulation. Therefore, the improved switch model provided by the present invention is of great theoretical and practical engineering significance in both offline simulation and real-time simulation of power systems comprising large-scale power electronic components. The model can be used in module combination type multilevel converter topology and voltage source type converter topology, and can improve the model precision while improving the simulation efficiency. The method is suitable for realizing offline simulation and real-time simulation and facilitates the engineering popularization.

Vascular conditions are detected non-invasively in the human body using a collection of information from small local regions of the vasculature, or from a specific signature or “BrainPulse” that can be derived from a patient's heartbeat-induced cranium movements. An array of accelerometers or other sensors are engaged against the head of a patient and skull movements, preferably under 100 Hz, are recorded. Vibration signatures of vessel structures such as branches, aneurysms, stenosis, etc. using random, periodic, band limited or transient analysis provides a library for further processing. The signature library is used to localize the origin of the recognized vascular feature, and the localized feature is presented to the physician in a clinically relevant manner.

The invention discloses an electromechanical transient model of a distributed power flow controller and an electromechanical transient simulation method. The electromechanical transient model comprises a standard test system, a DPFC (Distributed Power Flow Controller) series connection side user-defined model and a DPFC parallel connection side user-defined model. When power flow analysis is performed on an electric power system according to a working principle of the distributed power flow controller, injection current of the distributed power flow controller for an electric power network interface node is adjusted by applying an injection current method idea considering three times of harmonic dynamic energy exchange inside, and a function of controlling line power flow and bus voltage is realized. According to the invention, a mathematical model of equivalent current injected into nodes at two ends of a line at series and parallel connection sides of the distributed power flow controller considering three times of harmonic dynamic energy exchange inside is derived, and the mathematical model is applicable to the simulation process of electromechanical transient analysis for the electric power system, thereby providing a method for further studying the performance and characteristics of the DPFC, and providing a model basis for performance analysis for the DPFC.