45results about How to "Practical engineering application value is great" patented technology

The invention discloses a multi-harmonic-source harmonic contribution quantitative analysis method based on a total-least square method. The multi-harmonic-source harmonic contribution quantitative analysis method includes: selecting harmonic voltage as the index for evaluating harmonic contribution, and determining the joint action of the harmonic source of each node; sectioning measured data according to time, and calculating the harmonic contribution in each time section according to the projection of the harmonic voltage of one harmonic source at one node on the total harmonic voltage at the node; using the total-least square method to solve harmonic impedance and the harmonic voltage, namely background harmonic voltage, of other harmonic sources at the node, and using a singular value decomposition method to obtain the solution of the total-least square method to obtain the quantitative data of each harmonic source at each node at each harmonic time. The multi-harmonic-source harmonic contribution quantitative analysis method has the advantages that the total-least square method is applied to the harmonic quantitative analysis field, the defect that a traditional method only considers variable harmonic voltage measuring errors and does not consider the independent variable harmonic current measuring errors is overcome, and obtained results are accurate.

The invention provides a method for precisely solving the length of an unstressed cable of a cable-stayed bridge. The length of the unstressed cable is solved by substituting the average value of the nodal force at the end of the stayed cable with a precise calculation method for the force at the end of the stayed cable, and by building a precise expression s0 of the length of the unstressed stayed cable and a characteristic parameter beta constraint equation of the stayed cable when a tensile force at the end of a tower is known without selecting the primary value of the length of the unstressed cable. The method comprises the following steps of: building the precise expression of the length of the unstressed stayed cable and the characteristic parameter beta constraint equation of the stayed cable when the tensile force Tj at the end of the tower is known, and solving the length of the unstressed stayed cable. The method has the advantages of solving the problem on the selection of the primary value of the length of the unstressed cable, with high convergence rate and small calculation error. Compared with the linear search, the dichotomy and the improved chord secant method for iteratively solving the length of the unstressed cable, the method of the invention greatly improves the solution precision and solution efficiency of the length of the unstressed stayed cable, so the method is of relatively high application value in practical projects.

The invention belongs to a blade clearance measuring technology, and particularly relates to a method for measuring the tip clearance of turbine concave cavity blades. Disclosed by the invention is a method for measuring the tip clearance of the turbine concave cavity blades, which comprises the steps of firstly acquiring original blade tip signals and carrying out filtering and smoothing processing, then setting high and low threshold levels according to the shape of the concave cavity blades, enabling the high level to be between the peak of original blade tip clearance signals and the concave cavity valley, enabling the low level to be between inter-blade valley signals and concave cavity valley signals, differentiating different blades according to the low level, identifying two peaks according to the high level, extracting peak level, and then determining tip clearance values at a blade back side and a blade basin side according to a fitting relation between clearance and voltage. According to the invention, blade tip signals at the blade back and the blade basin of turbine concave cavity blades can be identified and extracted based on a full-period sampling technology based tip clearance measuring algorithm, variations in tip clearance at the back and the basin are monitored visually in real time, and whether collision occurs or not between the blade tip and a casing can be judged precisely.

The invention discloses a main switch fault detection method for an asymmetric half-bridge-type power converter of a switched reluctance motor. The method comprises the following steps: detecting the instantaneous value of each phase current of the switched reluctance motor power converter, calculating the difference between the two of the normalized current averages, and treating each difference as an element to construct the fault feature quantity set Ek; determining the condition which the element in the set belongs to in the fault diagnosis table by comparing the relationship between the elements in the set and the diagnostic threshold; detecting the fault occurrence, the fault type and the fault phase according to condition details in the table; if the fault type is open, identifying the fault element by calculating the demagnetization time of the fault phase current; and if the fault type is short circuit, identifying the faulty element by judging the main switch on and off state. The method can precisely and rapidly detect the fault details, is suitable for a variety of phases of switched reluctance motor power converters without adding any additional sensors, and is high in versatility, high in reliability and good in implementation effect.

The invention relates to a method for setting a longitudinal stiffening rib of a high web of an elastic rotation constrained boundary steel-concrete composite beam. The method comprises the following steps: firstly building a displacement function equation with the elastic rotation constrained boundary and the boundary condition, deriving buckling stress calculation expression of the stiffening rib under two states of the rigid stiffening and flexible stiffening based on an energy method, and obtaining a calculation formula of the elastic rotation constrained boundary longitudinal stiffening rib critical rigidity; and then, considering external work and a minimum potential energy principle, presenting a critical buckling stress calculation formula of a non-uniform pressing plate under the elastic rotation constrained boundary; and finally, according to a buckling safety degree equal principle, obtaining the optical position of setting the longitudinal stiffening rib under the elastic rotation constrained boundary. The method is capable of, according to the actual stress situation, accurately setting the longitudinal stiffening rib of the high web of the steel-concrete composite beam, solving the problems of the current steel-concrete composite bridge bream stiffening rib that the design is conservative and the amount of the steel products is large, and remarkably improving the rationality and economy of the stiffening rib setting of the high web.

The invention provides a method for evaluating the resistance deterioration of a stay cable of a steel strand of a cable-stayed bridge taking fretting fatigue. The method comprises the following steps of: sampling practical parameters of steel wires of the stay cable of the cable-stayed bridge on site; obtaining a fretting fatigue depth fitting formula among steel wires of the stay cable of the steel strand of the cable-stayed bridge; dividing resistance deterioration phases of the stay cable; and substituting the actual fretting fatigue depth among the steel wires into the deterioration process of the stay cable of the steel strand of the cable-stayed bridge according to division of different phases to obtain a resistance deterioration equation of the stay cable of the steel strand of the cable-stayed bridge taking the fretting fatigue, and evaluating the situation of the resistance deterioration of the stay cable. The method describes the deterioration process of the stay cable of the steel strand more comprehensively and more accurately, and the evaluation process is simple and practical.

The invention discloses a device and a method for measuring alternating current losses under a superconducting magnet alternating current condition. The device mainly comprises a data acquisition module and a processing and display module. The core component of the data acquisition module is a data acquisition card used for collecting voltage and current signals when a superconducting magnet to bedetected works. Through LabVIEW software, the software and hardware online control of the data acquisition card and the processing and display module is realized, and the collected voltage and current signals are transmitted to the processing and display module. In the processing and display module, an energy calculating formula which is a voltage and current integral formula is used to process received data, the total energy change of the superconducting magnet acquired through calculation is used to subtract the energy change of the equivalent inductance of the superconducting magnet to bedetected so as to acquire the alternating current loss measurement result of the superconducting magnet to be detected. In the invention, problems that a speed is slow, operation is complex, only small coils can be measured and so on in an existing alternating current loss measurement method are solved.

The invention discloses an integrated energy microgrid control experiment system based on semi-physical simulation. The integrated energy microgrid control experiment system realizes coordinated and optimized operation of various forms of energy in an AC/DC hybrid microgrid based on an RTDS system to ensure stability, accuracy and rapidity of data transmission and control signals. The purpose of developing a VME controller is to deal with the increasingly complex integrated energy microgrid system, to achieve multi-energy complementarity, grid-source-load coordinated and optimized operation and to solve the power grid economic dispatching problem. The invention aims at developing the experiment system of the integrated energy microgrid system and performing simulation and effect verification of the microgrid structure and the operation control strategy thereof. The application of the semi-physical simulation platform can more truly reflect the operating state of the actual microgrid system and can provide ideas and methods to solve the problems in the actual engineering so as to have great practical engineering application value.

The invention provides a compressor surge fault diagnosis method based on acoustic signals. The compressor surge fault diagnosis method includes the following steps that (1), a sound pressure sensor is installed on a compressor casing; (2), signals obtained by the sound pressure sensor are subjected to filtering and energy spectrum analysis; (3), the energy ratio calculating is carried out on analysis results; and (4), threshold judgment is carried out, and determining signals are output. According to the compressor surge fault diagnosis method and the low frequency acoustic characteristic phenomenon at the time of compressor surge occurring, the acoustic signals at the time of compressor surge occurring are captured by using an acoustic testing method, and a calculation method of energy ratio is used to successfully implement accurate diagnosis of compressor surge faults. The compressor surge fault diagnosis method can be applied to the on-line diagnosis of the compressor surge faults, is simple in testing and accurate in diagnosis, can be popularized and applied on compressors, and has good economic benefits and great practical engineering application value.

The present invention provides a calculation method for an ultimate shear-carrying capacity of bundled long and short shear nails. The method comprises: firstly, launching a push-out test and finite element analysis of long and short shear nails to obtain an average single nail ultimate shear-carrying capacity, studying rules of effects of parameters of long and short shear nails, such as diameter, length, strength, elastic modulus and concrete strength, on shear-carrying capacity of a shear nail, performing non-linear regression analysis on ultimate shear-carrying capacity of the shear nail by a differential evolution method, and establishing a calculation formula of the ultimate shear-carrying capacity of the bundled long and short shear nails; and then, studying load, ultimate shear-carrying capacity and a relative slip value between a steel beam and a concrete slab of the long and short shear nails, and performing regression analysis to obtain a calculation formula of a load-slip curve of the bundled long and short shear nails. The method provided by the present invention solves the problem that the prior specification cannot consider staggered arrangement of different lengths and diameters of the shear nails for calculation of capacity, and provides technical supports for design long and short shear nails in steel-mixed composite structures.

The invention discloses a method for determining the shear capacity of a light ultra-high performance concrete beam. The method is characterized by comprising the following steps: testing the sectionwidth, the section effective height and the shear span section length of the LUHPC beam; testing the axial compressive strength, the stirrup yield strength and the stirrup spacing of the concrete; carrying out an LUHPC beam shear test, obtaining the shear bearing capacity of the test beam, studying the influence rule of the shear span ratio and the hooping rate on the LUHPC beam shear bearing capacity, carrying out the nonlinear regression analysis on the LUHPC beam shear bearing capacity through a differential evolution method, and establishing a shear bearing capacity calculation formula ofthe LUHPC beam; and substituting the required data into a calculation formula to obtain the shear capacity of the light ultra-high performance concrete beam. According to the method, the problem thatan existing standard shear capacity formula is not suitable for the LUHPC beam is solved, and technical support is provided for shear design of the LUHPC beam. According to the method, the shear capacity of the LUHPC beam can be accurately determined, and the determination method is simple and easy to implement.

A method considering influence of multiple factors for predicting fatigue life of a large span power transmission wire is disclosed; first, considering the influence of wind speed, ambient temperatureand current carrying capacity on the temperature of the wire, and calculating the actual temperature of the wire; then establishing a mechanical equilibrium equation of the power transmission wire, considering the influence of the temperature on the stress of the wire, and calculating the stress of a steel core aluminum strand of the wire under tension and temperature effects; using an energy method to establish an energy balance equation of the power transmission wire, and calculating the dynamic stress amplitude of the power transmission wire; calculating the equivalent alternating stress of the power transmission wire, and calculating the number of times of vibration resistance of the power transmission wire; calculating the annual vibration cycle number of the power transmission wireunder different frequencies according to the probability distribution of wind speeds and wind directions at each level; and finally, improving a traditional Miner method, considering the influence ofthe interaction between stresses of each level of the wire on the fatigue of the wire, and calculating and evaluating the fatigue life of the wire. The method for calculating the fatigue life of the large span power transmission wire is high in precision and high in speed, and is more in line with the engineering practice of the power transmission wire.

The invention relates to a computing method of dynamic response under nonuniform excitation of an overline overbridge. The computing method of dynamic response under the nonuniform excitation of the overline bridge relates to the computing method of dynamic response of the overline pedestrian overbridge under the action of the nonuniform excitation of a main-line train, the dynamic response of the overline pedestrian overbridge serves as a target value, considering that the nonuniform excitation is generated at the position of a bridge pier of the overline pedestrian overbridge during the high-speed running process of the train, the equation of motion of the overline pedestrian overbridge under the action of the nonuniform excitation is deduced, and the response of the overline pedestrian overbridge under the action of the train can be obtained according to a numerical integration. According to the computing method of dynamic response under the nonuniform excitation of the overline bridge, the analytic method of the nonuniform excitation is brought out creatively to be used for calculating the vibration response under the nonuniform excitation acting on the position of the bridge pier of the overline pedestrian overbridge when the main-line train passing through at a high speed under the overline pedestrian overbridge, the computing method of dynamic response under the nonuniform excitation of the overline bridge is suitable for dynamic response analyses of all overline pedestrian overbridges under the action of the main-line trains and has a comparatively large practical engineering application value and innovativeness.

The invention belongs to the field of the digital speed measuring technology and particularly relates to a median-value average filtering principle-based digital speed measuring method, wherein a speed feedback value is resolved based on the displacement. According to the median-value average filtering principle-based digital speed measuring method provided in the invention, firstly, the number N0of sampling points is selected, and a median-value average filtering-based digital speed measuring scheme is determined. The speed measuring scheme is subjected to mathematical simulation test. In this way, whether the signal characteristic and the phase margin characteristic of the speed measuring scheme meet the requirements at the same time or not can be verified. After that, the entity test is carried out on a motor connected with an absolute displacement sensor, wherein whether the characteristic of the speed feedback signal of the motor and the characteristic of the phase margin of thecontrol loop meet the requirements at the same time or not are verified. According to the invention, the method overcomes the defects of a traditional method in an initial operation stage and reducesthe resolution error. Meanwhile, the introduced phase lag is reduced. The control characteristic in the initial acceleration stage is improved. The method is suitable in all application scenes whereincorresponding speeds need to be resolved by using linear displacement values or angular displacement measurement values. The method has great practical engineering application value.