280 results about "Stability criterion" patented technology

Learning-type motion control is performed using a hierarchical recurrent neural network. A motion pattern provided through human teaching work is automatically time-serially segmented with the hierarchical recurrent neural network, and the motion control of a machine body is carried out with a combination of the segmented data, whereby various motion patterns can be produced. With the time-serial segmentation, local time-serial patterns and an overall pattern as a combination of the local time-serial patterns are produced. For those motion patterns, indices for static stability and dynamic stability of the machine body, e.g., ZMP stability criteria, are satisfied and hence control stability is ensured.

Methods and systems involve the formation of a classification interval used for sensing a cardiac signal following a pacing pulse to determine a cardiac response to pacing. One or more cardiac signals associated with a type of cardiac pacing response are sensed. The timing of at least one feature of the cardiac signal may be used to define an initial cardiac response classification interval. The classification interval is adapted based on the variability of the timing of the feature. The classification interval may be adapted using a predetermined number of additional cardiac signals or until a predetermined stability criterion is achieved.

The invention relates to a method for controlling a wind park comprising several wind power installations to feed electrical power into an electrical AC grid at a point of common coupling (PCC). The method comprises feeding a 3-phase current at a point of common coupling, identifying a grid voltage on the point of common coupling, comparing the grid voltage that was identified on point of common coupling with at least one predetermined set point value, determining set point values for wind power installations depending on a comparison conducted to meet a stability criterion on point of common coupling, passing the determined set point values to plant control units of the individual wind power installations, and producing electrical current at each of the wind power installations depending on the predetermined set point values to be jointly fed in on point of common coupling.

Techniques for performing adaptive and robust prediction. Prediction techniques are adaptive in that they use a minimal amount of historical data to make predictions, the amount of data being selectable. The techniques are able to learn quickly about changes in the workload traffic pattern and make predictions, based on such learning, that are useful for proactive response to workload changes. To counter the increased variability in the prediction as a result of using minimal history, robustness is improved by checking model stability at every time interval and revising the model structure as needed to meet designated stability criteria. Furthermore, the short term prediction techniques can be used in conjunction with a long term forecaster.

The invention discloses a quadruped robot motion planning method oriented to an unknown rough terrain. A quadruped robot uses a crawling gait in a rough terrain. In a single-legged swing phase, a swinging leg swings along a planned foot trajectory and the center of gravity of the robot moves forwards along the planned path by means of the motion of supporting legs. In a four-foot stance phase, the center of gravity of the robot laterally moves while moving forwards along the planned path. The quadruped robot motion planning method achieves robot online trajectory planning based on COG and ZMP dual-stability criteria, takes full account of the possibility of advanced landing and lagged landing of the swinging leg for the unknown terrain, and estimates the parameter of the unknown terrain by the landing planning and the sensing strategy of the swinging leg. Thus, the robot adaptively adapts to the height and the slope of the unknown terrain, and achieves continuous adaptive walking for the unknown rough terrain according to a motion planning result.

The invention relates to a karst cave type foundation stability estimation method, in particular to a measurement method of karst cave type foundation collapse risks. The measurement method mainly solves the problem that because comprehensive prediction methods for the karst cave type foundation stability are immature in the prior art and judgment models are established on the basis of different angles, the reliability of influence factors is greatly lowered. According to the specific scheme, the relation between vertical stress of overlaying soil on karst caves and limit vertical stress of the overlaying soil on the karst caves is derived and established according to the karst collapse mechanism of karst cave type foundations, stability loss risk estimation parameters for determining karst cave type foundation collapse are proposed, and the one-to-one corresponding relation between the karst cave type foundation stability loss risk estimation parameters and stability factors is established. The measurement method has the advantages of having clear stability criteria, being simple and practical and having high practicality value for effective prediction, prevention and control of karst cave type foundation collapse.

A monitoring device (6) records variables that are characteristic of operating parameters of a continuous casting mold (1) for casting a metal strand (2). The monitoring device (6) records at least some of the characteristic variables by independently performing measurements during the casting of the metal strand (2). The monitoring device (6) forms groups (G1, G2) of operating parameters and independently tests whether the operating parameters of the respective group (G1, G2) satisfy a respective predetermined stability criterion. The monitoring device (6) accepts the operating parameters into a database (12). The monitoring device (6) determines those data records (11) contained in the database (12) that coincide in their input variables with the basic operating parameters and determines admissible operating parameter ranges for supplementary operating parameters. The monitoring device (6) independently tests whether the supplementary operating parameters lie within the admissible operating parameter ranges.

A mobile crane with a carrier and a superstructure which is slewably arranged thereon has a superlift device with an SL counterweight for increasing lifting capacity. The SL counterweight can be lifted from the ground in order to execute slewing movements of the superstructure and its slewing radius is changeable. The crane has an electronic control device with a computing device and with a display. In order to avoid costly conversion work on the SL counterweight and to increase operating safety, a program is stored in the electronic control device, which program determines a permissible operating field for crane parameters from the parameters comprising load size and load radius, size of SL counterweight and SL counterweight radius while taking into account the stability criteria and capacity criteria of the mobile crane and displays this operating field graphically on the display. Within this operating field, these parameters may be safely changed, the rest of the parameters remaining constant, and the lifting of the SL counterweight from the ground can be ensured.

The invention relates to a detection agent for hemostasis and thrombus belonging to medical clinical detection technical field, in particular to a detection agent for measuring activation partial thromboplastin time (APTT) of blood plasma. The invention is characterized in that the agent is prepared from 0.05-0.5g / L agent solid activator, 20-200mg / L phosphatide, 0.1-10mmol / L divalent metal ion salt, 0.1-0.5g / L stabilizer, 0.1-10g / L polyethylene glycol PEG, 0.05-4.0g / L buffer agent, 2.0-5.0g / L revival agent, while the left is water. The invention provides a high-stability standard agent for meeting APTT measurement, with simple operation, suitable price, short activation time and high sensitivity.

The invention discloses a milling finish machining method based on the dynamic rigidity of an impeller blade. The dynamic modality of the impeller blade is obtained through a standard modal test, a flutter model is introduced to obtain a stability criterion, and reasonable machining parameters are acquired. The method comprises the followings steps of: 1, performing the modal test to measure the dynamic modality of the impeller blade; 2, building a milling stability model of the impeller blade; 3, studying the dynamic rigidity stability of the impeller blade; 4, obtaining a cutting stability condition under the dynamic rigidity of the impeller blade; and 5, verifying the cutting stability condition and adopting the finally optimized cutting parameters to machine. The problem of cutting flutter caused by milling of thin-walled parts such as the blade is solved by the method, and the machining stability is obviously improved by optimizing the cutting parameters. The method is suitable for finish machining of various thin-walled parts.

A method for adjusting a drilling parameter of a drill string includes: determining one or more modes of the drill string; sensing a first oscillation amplitude at a first position in the drill string and / or an oscillation parameter of the drill string at the first position or a second position to provide measured first oscillation amplitude data and / or measured oscillation parameter data; identifying a mode of the drill string using one or more determined modes and a stability criterion and at least one of the measured first oscillation amplitude data and the measured oscillation parameter data; calculating an oscillation amplitude at a position of interest in the drill string using the identified mode and at least one of the measured first oscillation amplitude data, the measured oscillation parameter data and the stability criterion; and adjusting the drilling parameter in response to the calculated oscillation amplitude at the position of interest.

The invention discloses a method for generating the accelerated stability profile of a dynamically tuned gyro based on a finite element, comprising the following steps: 1. selecting a finite element unit by combining the main mechanism of DTG (ate time group) parametric variation; 2. building a material model bank: defining a unit system, and inputting the material attribute of each part; 3. determining a modelling part by analyzing the main mechanism of DTG parametric variation, simplifying a model connection relationship, building a DTG geometric model in finite element software, and carrying out material attribute assignment to the DTG geometric model; 4. building a DTG finite element model: implementing different grid precision partitioning methods aiming at different parts of the DTGto partition a finite element grid; 5. restraining and loading the DTG finite element model, carrying out thermal-structural coupling analysis, and obtaining the variation rule of the internal residual stress of DTG under different temperature profiles through simulated calculation; and 6. analyzing the simulation result of the finite element according to the DTG performance parameter stability criterion, and selecting an optimized DTG accelerated stability simulation profile. The method has high precision and is easy to realize.

A voltage regulator improves its transient adjustment response by amplifying error in its regulation feedback control path, including any droop-related error. Amplifying the error speeds up the voltage regulator's response to load changes and droop control adjustments by exaggerating the feedback error. Thus, in at least one embodiment, a droop control circuit imparts a droop-related offset between an output feedback signal and a reference signal responsive to a droop adjustment signal, and a response-enhancing amplifier circuit amplifies that offset for input to an error sensing circuit of a regulation control circuit. The gain and frequency response of the response-enhancing amplifier circuit may be set as a function one or more regulation stability criteria, and the response-enhancing method may be adapted to a variety of voltage regulator topologies. Such topologies include, but are not limited to, PWM regulators and hysteretic regulators.

The present invention belongs to the technical field of power system, and relates to a method of time-delay stability criterion. The method adopts the idea of Lyapunov stability criterion; an appropriate Lyapunov functional is selected at first, and is transformed into a group of linear matrix inequalities (LMI) for solution through the Leibniz-Newton formula, relaxation and other means; simultaneously, the redundant items which are generated in the deduction process is eliminated so as to acquire the stability criterion. In the method, the items to be calculated are greatly reduced, and the operating efficiency is correspondingly improved. Moreover, because the time-delay stage widely occurs in various systems, the method is suitable for various environments with the time delay.

The invention discloses a stability evaluation method and system for a multi-machine multi-node power generation system. The method comprises the steps of carrying out power flow calculation, and calculating a steady-state control signal of a converter connected with each node and the steady-state harmonic content of an electric parameter according to the obtained voltage amplitude, phase and power of each node in a steady-state operation state; establishing the impedance of each converter considering a frequency coupling effect, and substituting the steady-state control signal and the steady-state harmonic content of the electric parameter to obtain the impedance considering the frequency coupling effect under a specific working condition; connecting the impedance considering the frequency coupling effect and the impedance of a passive element under all specific working conditions according to network topology to obtain a network node admittance matrix, and further obtaining equivalent network impedance aggregated to a set node; and applying a stability criterion to the equivalent network impedance aggregated to the set node to evaluate the system stability. According to the invention, the generation mechanism of the harmonic oscillation of the multi-machine multi-node power generation system can be analyzed, and the stability of the multi-machine multi-node power generation system can be accurately evaluated.

The invention discloses a method for controlling the virtual reactance of a photovoltaic grid-connected inverter, and relates to the technical field of photovoltaic grid-connected inverter control. The problem that an existing photovoltaic grid-connected inverter is poor in stability is solved. The method includes the following steps: obtaining the virtual inductance value, the equivalent internal resistance of the virtual inductance value and the virtual capacitance according to the actual power grid resistance, the inverter output impedance and the inverter output impedance stability criterion; obtaining the equivalent feedforward passage transfer function of a virtual inductor in cooperation with full-bridge gains according to the virtual inductance value and the equivalent internal resistance of the virtual inductance value; obtaining the equivalent feedforward passage transfer function of a virtual capacitor in cooperation with the full-bridge gains, the actual filter capacitance, the filter inductor, the parasitic resistance of the filter inductor, the electric current loop transfer function and the feedback filter loop transfer function according to the virtual capacitance of the virtual capacitor; conducting discretization on the equivalent feedforward passage transfer functions of the virtual inductor and the virtual capacitor to obtain a difference equation; overlaying the difference equation and the electric current loop output value. The method is suitable for controlling the photovoltaic grid-connected inverter.

The invention belongs to the technical field of electric systems. In order to solve the problem of low stability analysis computing efficiency of the original time delay electric system, effectively reduce the dimensionality of a time delay differential equation and achieve higher computing efficiency, the invention adopts a technical scheme that a Lyapunov stability analysis method of a time delay electric system comprises the following steps of establishing a constraint time delay differential equation (CTODE) model of the electric system, rearranging and reorganizing system states in a manner that the states (z1 to z) not considering time delay influence are at the front and the states (z2 to z) considering the time delay influence are at the back, obtaining a CTODE model corresponding to the original time delay system, and basing on a new stability criterion of the CTODE model. The method is mainly applied to the electric system.

The invention relates to a soil layer slope stability determining method based on an orthogonal strain ratio. The method comprises the following steps: step one, determining a slope most dangerous slip plane; step two, arranging a slope orthogonal strain monitoring grid; step three, performing monitoring and data recording on vertical and horizontal strain at each monitoring grid node; step four, determining a slope monitoring grid orthogonal strain ratio parameter; step five, determining a slope orthogonal strain ratio stability criterion and a slip plane plastic zone; step six, determining a slope body damage variable and a damage variable critical value; step seven, analyzing and evaluating slope overall stability; and step eight, determining a slope overall slip plane. The method provided by the invention can accurately determine a slope plastic zone and evaluate the slope stability, and has an important engineering application value in slope stability and land slide geological disaster monitoring early warning and control.

A method for the iterative decoding of a block of bits having a number N of bits to be decoded where N is a whole number greater than or equal to two, using an iterative decoding algorithm, comprises the generation of a current block of N intermediate decision bits by executing an iteration of the decoding algorithm, followed by the verification of a stability criterion for the current block by comparison of the current block with a given block of N reference bits. If the stability criterion is satisfied, the iterations of the iterative decoding algorithm are stopped and the current block of intermediate decision bits is delivered as a block of hard decision bits. Otherwise another iteration of the decoding algorithm is executed.

The invention discloses a feed-forward voltage compensation-based direct-current side oscillation suppression method for a metro traction converter. Proper damping parameters are selected according toa stability criterion condition. Meanwhile, based on the principle that the ratio of effective vectors is maximum and the disturbance is minimum, a feed-forward voltage compensation parameter of a dqshaft is calculated. According to the principles of equal effective action vectors and power conservation, a reference voltage vector after the amplitude-limiting adjustment is obtained through calculation. As a result, the direct-current side stability control of a metro traction transmission system under the compensation over-modulation condition is ensured. According to the invention, the dynamic compensation for the feed-forward voltage is adopted, and the oscillation of the direct-current side voltage and the direct-current side current during the operation process of the traction transmission system is suppressed. The stability of the voltage at the direct-current network side is ensured. Meanwhile, the over-modulation condition caused by voltage compensation is considered, so thatthe effectiveness of the oscillation suppression method under the over-modulation condition is ensured. The condition that existing reference current compensation schemes are easily limited by currentloop bandwidth is avoided, so that the faster dynamic response is achieved.

The invention discloses a jump electric system time lag stability analyzing system and method based on a Markov chain, and belongs to the technical field of electric system stability analysis. The analyzing system comprises a data collecting module, a model building module, a stability analyzing module and a result outputting module, wherein the data collecting module, the model building module, the stability analyzing module and the result outputting module are sequentially connected. The analyzing method includes the steps that electric system parameters of a jump electric system under various operating conditions are collected; the mapping relation between the jump electric system and a Markov process is built; a jump electric system time lag state equation based on the Markov chain is built, and the order of the state equation is reduced; according to the state equation with the order reduced, jump electric system time lag stability criterions are determined; a jump electric system time lag stability upper limit is solved by using a generalized eigenvalue method. Under the condition of considering the jump characteristics of an electric system, the electric system time lag stability can be analyzed effectively.

A circuit breaker having a series arc fault detector and method of operation is provided. The series arc fault detector measures the RMS current and monitors current stability in response to a change in current levels. The sensitivity of the series arc fault detection is changed in response to the current satisfying a stability criterion. The circuit breaker further enables and disables series arc fault detection based on an enable threshold. The enable threshold is set based on the level of sensitivity being used to detect a series arc fault.

The invention discloses a research method for analyzing subsynchronous oscillation characteristics of a direct-drive fan based on admittance. A direct-drive fan network side converter mainly comprisesa current controller, an outer ring voltage controller and a phase-locked loop controller. The method comprises the following steps of: the step 1, establishing an admittance model of a current controller; the step 2: on the basis of the step 1, establishing an outer loop voltage controller model, and correcting an admittance model; the step 3: based on the steps 1 and 2, establishing a phase-locked loop controller model to obtain a final direct-drive fan admittance model; the step 4: based on the step 3, evaluating the risk of the direct-drive fan generating sub-synchronous oscillation by utilizing the dissipative property of the admittance matrix; the step 5: establishing a power grid side input impedance matrix; and the step 6: based on the steps 3 and 5, predicting the grid connectionstability of the direct-drive fan by utilizing the stability criterion of the impedance matrix infinite-norm.

The invention belongs to the technical field of power systems and relates to an improved discrimination method of Lyapunov robust stability of a power system containing uncertain delay links, which ischaracterized by solving the Lyapunov functional of a delay system based on the Krasovskii theory, then expressing the derived function of a system trajectory from the functional by a group of linearmatrix inequalities (LMI), reducing the conservation of the criterion by introducing a few necessary loose terms in the process of deducing functional derivatives and then transforming the disturbance terms containing uncertainties by utilizing the Schur complement, thereby obtaining the stability criterion. The method of the invention has the advantages of less conservation and high operation efficiency.

The invention discloses a method for pre-estimating an equivalent thermal conductivity of an unidirectional fiber toughening composite material based on gap defect identification, wherein the method mainly comprises the following steps: processing a material micro electron microscope image by using a picture identification technology, and identifying material internal structure characteristics and gap defects; according to a fiber volume fraction ratio stability criterion, applying a geometric reconstruction technology, establishing a representative element geometric topology model, and simultaneously determining the gap defects; through a method of adding a thermal contact resistance at a representative element internal interface, introducing influence of the gap defects; and simulating to obtain the equivalent thermal conductivity by using an finite element method. According to the method, the representative element considering the gap defects is established based on image identification of an actual micro structure, and calculation of the equivalent thermal conductivity is carried out, an influence rule of gap defect position, number, thickness and other characteristic parameters on the equivalent thermal conductivity is analyzed, and a technical reference is provided for high precision pre-estimation of the thermal conductivity of same-type composite materials.

The invention discloses a transient stability constraint optimal power flow computation method based on an EEAC and trace sensitivity, and belongs to the technical field of power system transient analysis. The method comprises the steps that a conventional optimal power flow solution is adopted as an initial operating point to calculate a transient initial value, and an anticipated fault set is set; transient time-domain simulation and EEAC equivalent operation are carried out on all faults in the anticipated fault set, the faults are classified, and the faults meeting the fault stability margin requirement are removed out of the anticipated fault set; the trace sensitivity of the faults not meeting the fault stability margin requirement is calculated, the margin sensitivity of the faults under different types is given, and a transient stability constraint is constructed according to the margin sensitivity of the faults; after the transient stability constraint is embedded in conventional optimal power flow model, an optimal power flow model including the simple transient stability constraint is obtained, the situation that transient stability cannot be quantized when only power angles are adopted as transient stability criterions is avoided, computation complexity is reduced, and the problem of difficult convergence is solved.